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1.
J Clin Pathol ; 70(12): 1079-1083, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28775171

RESUMO

Gliosarcoma, which is regarded as a variant of glioblastoma, is a rare malignant neoplasm of the central nervous system. Both its sarcomatous component and glial component are reported to share significant clinical and genetic similarities. However, gliosarcomas are considered to be characterised by a lack of the BRAF V600E mutation. Here, we report two cases of gliosarcoma harbouring the BRAF V600E mutation, of which one case appears to have arisen de novo, while the other likely arose from ganglioglioma. Interestingly, the BRAF V600E mutation was detected only in the glial component in the first case, but was present in both the glial and the sarcomatous components in the recurrent gliosarcoma. Furthermore, the different mutation state of BRAF V600E in our two cases suggests that the malignant transformation of gliosarcoma might have different underlying genetic alterations and mechanisms in de novo versus recurrent gliosarcoma.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias Encefálicas/genética , Ganglioglioma/genética , Gliossarcoma/genética , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Adulto , Biópsia , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/terapia , Análise Mutacional de DNA , Progressão da Doença , Evolução Fatal , Feminino , Ganglioglioma/enzimologia , Ganglioglioma/patologia , Ganglioglioma/terapia , Predisposição Genética para Doença , Gliossarcoma/enzimologia , Gliossarcoma/patologia , Gliossarcoma/terapia , Humanos , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Fenótipo , Resultado do Tratamento
2.
Cancer Gene Ther ; 14(12): 935-44, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17853921

RESUMO

The therapeutic utility of cytochrome P450-based enzyme prodrug therapy is well established by preclinical studies and in initial clinical trials. The underlying premise of this gene therapy is that intratumoral P450 expression leads to in situ activation of anticancer P450 prodrugs, such as cyclophosphamide (CPA), with intratumoral accumulation of its activated 4-OH metabolite. In mice bearing 9L gliosarcomas expressing the CPA 4-hydroxylase P450 2B6, enhanced tumor apoptosis was observed 48 h after CPA treatment; however, intratumoral 4-OH-CPA levels were indistinguishable from those of P450-deficient tumors, indicating that the bulk of activated CPA is derived from hepatic metabolism. In contrast, in 9L tumors expressing P450 2B11, a low K(m) CPA 4-hydroxylase, intratumoral 4-OH-CPA levels were higher than in blood, liver and P450-deficient tumors. Intratumoral 4-OH-CPA increased dose-dependently, without saturation at 140 mg kg(-1) CPA, suggesting restricted tumor cell permeation of the parent drug. To circumvent this problem, CPA was administered by direct intratumoral injection, which increased the maximum concentration and area under the curve of drug concentration x time (AUC) of intratumoral 4-OH-CPA by 1.8- and 2.7-fold, respectively. An overall 3.9-fold increase in intratumoral 4-OH-CPA AUC, and in antitumor activity, was obtained when CPA release to systemic circulation was delayed using the slow-release polymer poloxamer 407 as vehicle for intratumoral CPA delivery. These findings highlight the advantage of gene therapy strategies that combine low K(m) P450 prodrug activation enzymes with slow, localized release of P450 prodrug substrates.


Assuntos
Antineoplásicos Alquilantes/farmacocinética , Hidrocarboneto de Aril Hidroxilases/biossíntese , Ciclofosfamida/farmacocinética , Terapia Genética , Gliossarcoma/enzimologia , Gliossarcoma/terapia , Pró-Fármacos/farmacocinética , Esteroide Hidroxilases/biossíntese , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Hidrocarboneto de Aril Hidroxilases/genética , Linhagem Celular Tumoral , Família 2 do Citocromo P450 , Preparações de Ação Retardada/farmacocinética , Relação Dose-Resposta a Droga , Expressão Gênica , Gliossarcoma/genética , Humanos , Fígado/enzimologia , Camundongos , Camundongos Endogâmicos ICR , Camundongos SCID , Poloxâmero/farmacocinética , Esteroide Hidroxilases/genética
3.
Cancer Sci ; 98(5): 674-84, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17355261

RESUMO

The membrane-anchored metalloproteinase tumor necrosis factor-alpha-converting enzyme (TACE/a disintegrin and metalloproteinase [ADAM] 17) is key in proteolytic ectodomain shedding of several membrane-bound growth factors, cytokines and receptors. The expression and activity of ADAM17 increases under some pathological conditions including stroke, and promotes neural progenitor cell migration and contributes to stroke-induced neurogenesis. Hypoxia initiates cellular invasive processes that occur under both physiological and pathological conditions such as invasion and metastasis of some tumors. In the present study, we sought to elucidate whether ADAM17 contributes to brain tumor invasion. To this end, we examined the role of ADAM17 in the invasiveness of two different brain tumor cell lines, 9L rat gliosarcoma and U87 human glioma, under normoxic and hypoxic conditions. Additionally, we tested the effects of ADAM17 suppression on in vitro tumor cell invasion by means of ADAM17 proteolytic inhibitors and specific small interfering RNA. We found that tumor cells upregulated ADAM17 expression under hypoxia, and that ADAM17 activity correlated with increased tumor cell invasion. Conversely, suppression of ADAM17 proteolysis decreased invasiveness induced by hypoxia in 9L and U87 cells. Furthermore, the contribution of ADAM17 to tumor invasion was independent of matrix metalloproteinase (MMP)-2 and MMP-9 activity. ADAM17 was also found to activate the epidermal growth factor/phosphoinositide-3 kinase/serine/threonine kinase signal transduction pathway. Our data suggest that hypoxia-induced ADAM17 contributes to glioma cell invasiveness through activation of the EGFR signal pathway.


Assuntos
Proteínas ADAM/antagonistas & inibidores , Ácidos Hidroxâmicos/farmacologia , Proteínas ADAM/genética , Proteínas ADAM/metabolismo , Proteína ADAM17 , Animais , Western Blotting , Hipóxia Celular , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Cromonas/farmacologia , Inibidores Enzimáticos/farmacologia , Expressão Gênica , Glioma/enzimologia , Glioma/genética , Glioma/patologia , Gliossarcoma/enzimologia , Gliossarcoma/genética , Gliossarcoma/patologia , Humanos , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Microscopia de Fluorescência , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Morfolinas/farmacologia , Invasividade Neoplásica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Quinazolinas , Interferência de RNA , RNA Interferente Pequeno/genética , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Tirfostinas/farmacologia
4.
J Neurooncol ; 78(3): 295-302, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16636750

RESUMO

PURPOSE: Because raised matrix metalloprotease (MMP) levels are associated with glioma invasion and angiogenesis, we tested the efficacy of marimastat (MT) an orally active drug that can reduce MMP levels, in patients with gliomas. PATIENTS AND METHODS: A total of 162 patients with intracranial glioblastoma multiforme or gliosarcomas who had undergone surgery and radiotherapy participated in this multicenter, double-blind, placebo-controlled, parallel group study conducted at 20 institutions. Seventy-nine patients (57 male, 22 female, median age 58 years) were randomized to receive placebo (PB), and 83 patients (51 male, 32 female, median age 57 years) were randomized to receive MT, 10 mg orally twice daily, until tumor progression. RESULTS: This intention-to-treat efficacy analysis showed no statistically significant difference between MT and PB groups with respect to survival (P = 0.38, log rank test). The median survival time from protocol initiation was 37.9 weeks for the PB group and 42.9 weeks for the MT group, with a hazard ratio of 1.16 (95% CI 0.83 to 1.60). There were no statistically significant differences in quality of life between the PB and MT groups, as assessed by the FACT-BR questionnaire. Musculoskeletal toxicities led to dose modification or withdrawal in 20% of MT-treated and 1.2% of PB-treated patients. CONCLUSION: MT does not improve survival in patients with glioblastoma or gliosarcoma following surgery and radiotherapy. Therefore, single-agent MT appears unwarranted; however, MT in combination with cytotoxic chemotherapy may be warranted, as suggested by observations in our study and other studies.


Assuntos
Neoplasias Encefálicas/tratamento farmacológico , Inibidores Enzimáticos/uso terapêutico , Glioblastoma/tratamento farmacológico , Gliossarcoma/tratamento farmacológico , Ácidos Hidroxâmicos/uso terapêutico , Inibidores de Metaloproteinases de Matriz , Adulto , Idoso , Neoplasias Encefálicas/enzimologia , Terapia Combinada , Método Duplo-Cego , Inibidores Enzimáticos/efeitos adversos , Feminino , Glioblastoma/enzimologia , Gliossarcoma/enzimologia , Humanos , Ácidos Hidroxâmicos/efeitos adversos , Masculino , Metaloproteinases da Matriz/metabolismo , Pessoa de Meia-Idade , Doenças Musculoesqueléticas/induzido quimicamente , Qualidade de Vida , Análise de Sobrevida , Falha de Tratamento
5.
Cancer Res ; 62(23): 6928-37, 2002 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-12460909

RESUMO

Cytochrome P450 gene-directed enzyme prodrug therapy substantially augments intratumoral activation of anticancer prodrugs, such as cyclophosphamide (CPA), leading to a strong increase in antitumor effect without a corresponding increase in host toxicity. Attempts to additionally increase tumor cell kill by enhancing the intrinsic chemosensitivity of P450-expressing tumor cells by chemical means (depletion of cellular glutathione) or by coexpression of proapoptotic factors was shown to result in the desired increase in chemosensitivity, but with a decrease in net production of bystander cytotoxic drug metabolites because of accelerated death of the prodrug-activating tumor cells. Moreover, tumor cell P450 activity declined during the course of apoptosis induced by P450-activated CPA, limiting the potential of the tumor cell for continued production of activated drug metabolites. This limitation could be overcome by retroviral delivery of the baculovirus-encoded caspase inhibitor p35 to P450-expressing tumor cells. p35 substantially prolonged the activation of CPA by P450 "factory cells," leading to an increase in their bystander cytotoxicity toward P450-deficient tumor cells. This effect was greatest in tumor cells treated with CPA for an 8-h period, a schedule designed to model the effective time period of drug exposure in bolus CPA-treated patients in vivo. Notably, retroviral transduction of tumor cells with p35 did not induce drug resistance, as shown by the absence of long-term tumor cell survival or detectable colony formation activity after CPA treatment. These findings demonstrate that antiapoptotic factors, such as p35, can be used in a novel manner to enhance prodrug activation gene therapy by delaying tumor cell death, thereby increasing the net production of bystander cytotoxic metabolites and, hence, the overall effectiveness of the anticancer strategy.


Assuntos
Ciclofosfamida/análogos & derivados , Ciclofosfamida/farmacocinética , Sistema Enzimático do Citocromo P-450/genética , Terapia Genética/métodos , Pró-Fármacos/farmacocinética , Proteínas Virais/biossíntese , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Biotransformação , Inibidores de Caspase , Caspases/metabolismo , Ciclofosfamida/farmacologia , Sistema Enzimático do Citocromo P-450/biossíntese , Sistema Enzimático do Citocromo P-450/metabolismo , Ativação Enzimática , Gliossarcoma/tratamento farmacológico , Gliossarcoma/enzimologia , Gliossarcoma/genética , Gliossarcoma/metabolismo , Glutationa/deficiência , Glutationa/metabolismo , Humanos , Proteínas Inibidoras de Apoptose , NADPH-Ferri-Hemoproteína Redutase/biossíntese , NADPH-Ferri-Hemoproteína Redutase/genética , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Ratos , Células Tumorais Cultivadas , Proteínas Virais/genética , Proteínas Virais/metabolismo
6.
Cancer Gene Ther ; 9(10): 840-5, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12224025

RESUMO

Radiation therapy is an established modality for the treatment of malignant gliomas. Several reports have shown the advantage of additional radiation in combination with gene therapy. In this study, we investigated the ability of radiation therapy to enhance 5-fluorocytosine (5-FC)/cytosine deaminase (CD) plus uracil phosphoribosyltransferase (UPRT) gene therapy in malignant gliomas. In vitro study suggested evidence of a significant cytotoxic interaction between radiation therapy and 5-FC/CD + UPRT gene therapy for glioma cells. In vivo experiments demonstrated that the combination of gene therapy and radiation possessed superior antitumor effect in comparison to single therapy. However, the adverse effects of radiation therapy in combination with the gene therapy were observed with respect to normal brain. This combination therapy may be feasible for the treatment of gliomas, although the radiation dose and area should be reduced in order to prevent side effects.


Assuntos
Adenoviridae/genética , Neoplasias Encefálicas/terapia , Terapia Genética/métodos , Gliossarcoma/terapia , Nucleosídeo Desaminases/genética , Pentosiltransferases/genética , Radioterapia/métodos , Animais , Apoptose , Encéfalo/efeitos da radiação , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/patologia , Divisão Celular , Terapia Combinada , Citosina Desaminase , Citometria de Fluxo , Fluoruracila/uso terapêutico , Técnicas de Transferência de Genes , Vetores Genéticos , Gliossarcoma/enzimologia , Gliossarcoma/patologia , Óperon Lac , Masculino , Nucleosídeo Desaminases/metabolismo , Pentosiltransferases/metabolismo , Ratos , Ratos Wistar , Taxa de Sobrevida , Sais de Tetrazólio , Tiazóis , Células Tumorais Cultivadas
7.
Anticancer Res ; 21(4A): 2265-72, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11724281

RESUMO

The in vivo gene delivery of E. coli cytosine deaminase (cd) cDNA and systemic 5-fluorocytosine (5-FC) administration have been studied extensively because of their clinical relevance to cancer gene therapy. This approach has the potent advantage of a stronger bystander effect compared to the previous thymidine kinase suicide gene system of the herpes simplex virus. However, 5-fluorouracil (5-FU), an active metabolite in cd with 5-FC therapy, is not always effective for every type of tumor since the enzymes responsible for further drug metabolism vary significantly in each tissue. In this study, we aimed to increase the sensitivity of 5-FU by transduction of thymidine phosphorylase (dThdPase) cDNA into brain tumor cells. After retroviral transfer of the cDNA, we obtained 9L murine gliosarcoma cells showing stable expression of the target enzyme (9L-dThdPase). The growth of the cells was identical to wild type (9L-WT) or control-vector transfected (9L-Neo) cells in vitro. Sensitivity to 5-FU was increased in 9L-dThdPase cells. After the adenoviral delivery of cytosine deaminase gene into these cells, 9L-dThdPase cells also demonstrated an increased sensitivity to 5-FC. Moreover, we showed that transduction of dThdPase cDNA prolongs the survival of animals bearing intracerebral tumors after experimental in vivo cytosine deaminase gene therapy. These results suggest that transduction of thymidine phosphorylase may be a beneficial approach to increasing the efficacy of cd/5-FC suicide gene therapy in certain types of tumor.


Assuntos
Antimetabólitos Antineoplásicos/farmacologia , Neoplasias Encefálicas/terapia , DNA Complementar/genética , Flucitosina/farmacologia , Terapia Genética/métodos , Gliossarcoma/terapia , Nucleosídeo Desaminases/genética , Timidina Fosforilase/genética , Adenoviridae/genética , Animais , Antimetabólitos Antineoplásicos/farmacocinética , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/genética , Citosina Desaminase , DNA Complementar/administração & dosagem , Flucitosina/farmacocinética , Fluoruracila/farmacocinética , Fluoruracila/farmacologia , Vetores Genéticos/genética , Gliossarcoma/enzimologia , Gliossarcoma/genética , Masculino , Nucleosídeo Desaminases/metabolismo , Ratos , Ratos Endogâmicos F344 , Timidina Quinase/genética , Timidina Quinase/metabolismo , Timidina Fosforilase/biossíntese , Timidina Fosforilase/metabolismo , Transdução Genética
8.
Cancer Res ; 61(11): 4437-44, 2001 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-11389073

RESUMO

Transduction of tumor cells with a cyclophosphamide (CPA)-activating cytochrome P-450 (P450) gene provides the capacity for localized prodrug activation and greatly sensitizes solid tumors to CPA treatment in vivo. The therapeutic impact of this P450-based cancer gene therapy strategy can be substantially enhanced by cotransduction of P450 reductase, a rate-limiting component of P450-dependent intratumoral CPA activation. The present study examined the possibility of further improving P450/P450 reductase-based gene therapy by using a novel schedule of CPA administration, involving repeated CPA injection every 6 days and previously shown to have an antiangiogenic component. 9L gliosarcoma cells transduced with the CPA-activating enzyme couple P450 2B6/P450 reductase and grown s.c. in immunodeficient severe combined immunodeficient (scid) mice were repeatedly challenged with 140 mg/kg CPA every 6 days. Full tumor regression leading to eradication of six of eight tumors was observed when the tumor size at the time of initial drug treatment was approximately 400 mm(3) (approximately 1.5% of body weight). Little or no overt toxicity of the repeated CPA treatment regimen was observed. The same CPA schedule was much less effective in inducing regression of 9L tumors that were not transduced with P450/P450 reductase. Repeated CPA treatment of mice bearing large, late-stage P450/P450 reductase-transduced tumors (approximately 9-16% of body weight) resulted in major (> or =95%) regression in 15 of 16 tumors, with tumor eradication observed in 2 cases. Although CPA resistance was found to emerge in the population of P450/P450 reductase-transduced tumors, this resistance primarily involved a loss of expression of the transduced P450 and/or P450 reductase gene, rather than development of intrinsic cellular resistance to the activated form of CPA. These findings demonstrate that repeated CPA treatment on a 6 day schedule can be highly effective when combined with P450/P450 reductase gene therapy and suggest that repeated transduction of tumors with prodrug-activation genes may be necessary to achieve tumor eradication and a sustained therapeutic response.


Assuntos
Antineoplásicos Alquilantes/administração & dosagem , Ciclofosfamida/administração & dosagem , Sistema Enzimático do Citocromo P-450/genética , Terapia Genética/métodos , NADPH-Ferri-Hemoproteína Redutase/genética , Animais , Antineoplásicos Alquilantes/farmacocinética , Biotransformação , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Terapia Combinada , Ciclofosfamida/farmacocinética , Sistema Enzimático do Citocromo P-450/metabolismo , Relação Dose-Resposta a Droga , Esquema de Medicação , Gliossarcoma/tratamento farmacológico , Gliossarcoma/enzimologia , Gliossarcoma/genética , Gliossarcoma/terapia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos ICR , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Ratos , Transdução Genética
9.
Cancer Res ; 60(23): 6656-62, 2000 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-11118049

RESUMO

Tyrosinase has been suggested as a prodrug-converting enzyme for the treatment of melanoma. We hypothesized that tyrosinase expression in transfected nonmelanotic cells can be used in a gene therapy paradigm of prodrug activation. To verify our hypothesis, we used the following tyrosinase variants: (a) a full-length human tyrosinase clone (T); (b) a mutant lacking the COOH-terminal cytoplasmic domain (TdeltaC); (c) a mutant lacking the COOH-terminal transmembrane and cytoplasmic domains (TdeltaTC); and (d) a fusion with the eight COOH-terminal amino acids of lysosome-associated membrane protein-1 (TL). Expression of mutant and wild-type tyrosinases was induced by transfection in nontumorigenic human cells of epithelial origin (293HEK, MCF-10A adenoma, and NHDF-Ad human dermal fibroblasts) as well as in tumor cells (9L gliosarcoma, MCF7 adenocarcinoma, and HT-1080 fibrosarcoma). When compared with the wild-type tyrosinase transfectants, truncated mutant expression resulted in higher mRNA levels that paralleled higher enzyme activity of the truncated mutants. Two model tyrosinase prodrugs, hydroxyphenyl-propanol (HPP) and N-acetyl-4-S-cysteaminylphenol (NAcSCAP) inhibited proliferation and caused cell death of transfected cells in a dose-dependent manner. Effects of prodrug treatment were compared for tumorigenic cells and their nontumorigenic counterparts. Two truncated mutants (TdeltaC and TdeltaTC) showed low endogenous cytotoxicity and efficiently suppressed proliferation and induced cytotoxicity in transfected tumor cells in the presence of NAcSCAP. Overall, these results indicate that the developed tyrosinase mutants hold promise as prodrug activation systems for tumoral gene therapy.


Assuntos
Cisteamina/análogos & derivados , Monofenol Mono-Oxigenase/genética , Monofenol Mono-Oxigenase/metabolismo , Pró-Fármacos/farmacocinética , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/enzimologia , Adenocarcinoma/genética , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Biotransformação , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Cisteamina/farmacocinética , Cisteamina/farmacologia , Fibrossarcoma/tratamento farmacológico , Fibrossarcoma/enzimologia , Fibrossarcoma/genética , Gliossarcoma/tratamento farmacológico , Gliossarcoma/enzimologia , Gliossarcoma/genética , Humanos , Rim/citologia , Rim/enzimologia , Melaninas/biossíntese , Mutação , Fenóis/farmacocinética , Fenóis/farmacologia , Propanóis/farmacocinética , Propanóis/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Células Tumorais Cultivadas
10.
Cancer Res ; 60(22): 6307-10, 2000 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11103789

RESUMO

Local delivery of carmustine (BCNU) via biodegradable polymers prolongs survival against experimental brain tumors and in human clinical trials. O6-benzylguanine (O6-BG), a potent inhibitor of the DNA repair protein, O6-alkylguanine-DNA alkyltransferase (AGT), has been shown to reduce nitrosourea resistance and, thus, enhance the efficacy of systemic BCNU therapy in a variety of tumor models. In this report, we demonstrate that O6-BG can potentiate the activity of BCNU delivered intracranially via polymers in rats challenged with a lethal brain tumor. Fischer 344 rats received a lethal intracranial challenge of 100,000 F98 glioma cells (F98 cells have significant AGT activity, 328 fmol/mg protein). Five days later, animals receiving an i.p. injection of O6-BG (50 mg/kg) 2 h prior to BCNU polymer (3.8% BCNU by weight) implantation had significantly improved survival (n = 7; median survival, 34 days) over animals receiving either O6-BG alone (n = 7; median survival, 22 days; P = 0.0002) or BCNU polymer alone (n = 8; median survival, 25 days; P = 0.0001). Median survival for the control group (n = 8) was 23.5 days. Moreover, there was no physical, behavioral, or pathological evidence of treatment-related toxicity. These findings suggest that O6-BG can potentiate the effects of interstitially delivered BCNU and, for tumors expressing significant AGT, may be necessary for the BCNU to provide a meaningful therapeutic benefit. Given the clinical use of BCNU polymers against malignant gliomas, concurrent treatment with O6-BG may provide an important addition to our therapeutic armamentarium.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Carmustina/farmacologia , Inibidores Enzimáticos/farmacologia , Glioma/tratamento farmacológico , Guanina/análogos & derivados , Guanina/farmacologia , Animais , Antineoplásicos Alquilantes/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias Encefálicas/enzimologia , Carmustina/administração & dosagem , Implantes de Medicamento , Sinergismo Farmacológico , Inibidores Enzimáticos/administração & dosagem , Glioma/enzimologia , Gliossarcoma/tratamento farmacológico , Gliossarcoma/enzimologia , Guanina/administração & dosagem , Humanos , Masculino , Meduloblastoma/tratamento farmacológico , Meduloblastoma/enzimologia , O(6)-Metilguanina-DNA Metiltransferase/antagonistas & inibidores , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Ratos , Ratos Endogâmicos F344 , Técnicas Estereotáxicas , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
11.
Anticancer Res ; 20(5A): 3099-103, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11062728

RESUMO

Rats with 9L or 9L-2 intracerebral brain tumors were treated with streptozotocin (STZ) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) at various doses either as single agents or in combination. Treatment of rats bearing 9L or 9L-2 tumors with either STZ or BCNU produced a significant increase the level of sister chromatid exchanges (SCEs) (p < .001). Compared with 9L-2 tumors, 9L tumors were 7.8-fold more sensitive to the induction of SCEs by BCNU treatment. After combination treatments of STZ and BCNU, the number of SCEs observed in 9L tumors was additive but was synergistic in 9L-2 tumors. O6-alkylguanine DNA alkyltransferase activity (AGT) was measured in 9L and 9L-2 cells in vitro. No AGT activity was detected in 9L cells, however, a low level of activity was measured in 9L-2. In vitro, treatment of 9L-2 cells with STZ produced a dose dependent inhibition of AGT activity. We interpret, these results to suggest that STZ pretreatment potentiated the effects of BCNU in 9L-2 tumors by inhibiting AGT activity. The observations in this study suggest that measurement of SCE induction in intracerebral tumor models may provide a useful strategy for evaluating the effectiveness of new agents and potential therapeutic combinations for the treatment of gliomas.


Assuntos
Antibióticos Antineoplásicos/uso terapêutico , Antineoplásicos Alquilantes/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Carmustina/uso terapêutico , Gliossarcoma/tratamento farmacológico , Troca de Cromátide Irmã/efeitos dos fármacos , Estreptozocina/uso terapêutico , Telencéfalo , Animais , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/genética , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Quimioterapia Combinada , Estudos de Avaliação como Assunto , Gliossarcoma/enzimologia , Gliossarcoma/genética , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Ratos , Ratos Endogâmicos F344
12.
Cancer Res ; 60(15): 4277-83, 2000 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-10945642

RESUMO

We have shown recently that the multifunctional growth factor, scatter factor/hepatocyte growth factor (SF/HGF), and its receptor c-met enhance the malignancy of human glioblastoma through an autocrine stimulatory loop (R. Abounader et al., J. Natl. Cancer Inst., 91: 1548-1556, 1999). This report examines the effects of SF/HGF:c-met signaling on human glioma cell responses to DNA-damaging agents. Pretreating U373 human glioblastoma cells with recombinant SF/HGF partially abrogated their cytotoxic responses to gamma irradiation, cisplatin, camptothecin, Adriamycin, and Taxol in vitro. This cytoprotective effect of SF/HGF occurred at least in part through an inhibition of apoptosis, as evidenced by diminished terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling index and reduced DNA laddering. Anti-c-met U1/ribozyme gene transfer inhibited the ability of SF/HGF to protect against single-strand DNA breakage, DNA fragmentation, and glioblastoma cell death caused by DNA-damaging agents, demonstrating a requirement for c-met receptor function. Phosphorylation of the cell survival-promoting kinase Akt (protein kinase B) resulted from SF/HGF treatment of U373 cells, and both Akt phosphorylation and cell survival induced by SF/HGF were inhibited by phosphatidylinositol 3-kinase inhibitors but not by inhibitors of mitogen-activated protein kinase kinase or protein kinase C. Cytoprotection by SF/HGF in vitro was also inhibited by transient expression of dominant-negative Akt. Transgenic SF/HGF expression by intracranial 9L gliosarcomas reduced tumor cell sensitivity to gamma irradiation, confirming the cytoprotective effect of SF/HGF in vivo. These findings demonstrate that c-met receptor activation by SF/HGF protects certain glioblastoma cells from DNA-damaging agents by activating phosphoinositol 3-kinase-dependent and Akt-dependent antiapoptotic pathways.


Assuntos
Apoptose/efeitos dos fármacos , Glioblastoma/patologia , Fator de Crescimento de Hepatócito/farmacologia , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Serina-Treonina Quinases , Proteínas Proto-Oncogênicas/fisiologia , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/fisiologia , Expressão Gênica , Técnicas de Transferência de Genes , Glioblastoma/enzimologia , Gliossarcoma/enzimologia , Gliossarcoma/patologia , Fator de Crescimento de Hepatócito/fisiologia , Humanos , Masculino , Proteínas Tirosina Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-met/genética , Proteínas Proto-Oncogênicas c-met/fisiologia , RNA Catalítico/genética , Ratos , Ratos Endogâmicos F344 , Proteínas Recombinantes/farmacologia , Ribonucleoproteína Nuclear Pequena U1/genética , Transdução de Sinais/fisiologia , Células Tumorais Cultivadas
13.
Cancer Gene Ther ; 7(7): 1034-42, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10917206

RESUMO

The effect of the antithyroid drug methimazole (MMI) on cytochrome P450/P450 reductase-dependent activation of the anti-cancer prodrug cyclophosphamide (CPA) was investigated in a rat model of P450 prodrug activation-based cancer gene therapy. MMI treatment decreased the expression of hepatic P450 reductase by approximately 75% but did not alter P450 reductase levels in a 9L gliosarcoma growing in vivo as a subcutaneous solid tumor. In a pharmacokinetic study, MMI treatment significantly decreased the peak plasma concentration of the active, P450-generated metabolite 4-hydroxy-CPA, from 84.1 to 57.8 microM, and substantially prolonged its apparent half-life, from 25.4 to 54.3 minutes. The area under the plasma concentration x time curve and clearance values for 4-hydroxy-CPA were largely unchanged, however, indicating that MMI decreases the rate but not the overall extent of hepatic CPA activation. MMI alleviated some of the systemic toxicities of CPA treatment, as judged by the moderation of CPA-induced body weight loss and hematuria. The impact of MMI on CPA antitumoral activity was evaluated in rats implanted with 9L tumors transduced with P450 reductase in combination with the CPA-activating P450 2B1, which confers the capacity for intratumoral prodrug activation and leads to markedly enhanced chemosensitivity. CPA given as a single, subtherapeutic dose of 75 mg/kg resulted in a 13.8 day growth delay, whereas CPA in combination with MMI increased the growth delay to 17.4 days. By contrast, a tumor growth delay of only 3.4 days was observed in animals bearing 9L wild-type tumors given the same drug combination. We conclude that the selective reduction of liver P450 reductase after MMI treatment decreases the rate of hepatic drug activation and the host toxicity of CPA without loss of the antitumoral effect, thus increasing the therapeutic index of CPA in a P450-based cancer gene therapy model, where CPA undergoes localized drug activation at its intratumoral site of action.


Assuntos
Antineoplásicos Alquilantes/farmacocinética , Ciclofosfamida/farmacocinética , Terapia Genética , Gliossarcoma/terapia , Fígado/enzimologia , NADPH-Ferri-Hemoproteína Redutase/metabolismo , Neoplasias Cutâneas/terapia , Animais , Antineoplásicos Alquilantes/farmacologia , Área Sob a Curva , Peso Corporal , Divisão Celular , Ciclofosfamida/farmacologia , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Gliossarcoma/enzimologia , Meia-Vida , Fígado/efeitos dos fármacos , Masculino , Metimazol/farmacologia , Pró-Fármacos/farmacocinética , Pró-Fármacos/farmacologia , Ratos , Ratos Endogâmicos F344 , Neoplasias Cutâneas/embriologia , Células Tumorais Cultivadas
14.
J Cell Biochem ; 71(2): 169-81, 1998 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-9779816

RESUMO

Organization of intermediate filament, a major component of cytoskeleton, is regulated by protein phosphorylation/dephosphorylation, which is a dynamic process governed by a balance between the activities of involved protein kinases and phosphatases. Blocking dephosphorylation by protein phosphatase inhibitors such as okadaic acid (OA) leads to an apparent activation of protein kinase(s) and to genuine activation of phosphatase-regulated protein kinase(s). Treatment of 9L rat brain tumor cells with OA results in a drastically increased phosphorylation of vimentin, an intermediate filament protein. In-gel renaturing assays and in vitro kinase assays using vimentin as the exogenous substrate indicate that certain protein kinase(s) is activated in OA-treated cells. With specific protein kinase inhibitors, we show the possible involvement of the cdc2 kinase- and p38 mitogen-activated protein kinase (p38MAPK)-mediated pathways in this process. Subsequent in vitro assays demonstrate that vimentin may serve as an excellent substrate for MAPK-activated protein kinase-2 (MAPKAPK-2), the downstream effector of p38MAPK, and that MAPKAPK-2 is activated with OA treatment. Comparative analysis of tryptic phosphopeptide maps also indicates that corresponding phosphopeptides emerged in vimentin from OA-treated cells and were phosphorylated by MAPKAPK-2. Taken together, the results clearly demonstrate that MAPKAPK-2 may function as a vimentin kinase in vitro and in vivo. These findings shed new light on the possible involvement of the p38MAPK signaling cascade, via MAPKAPK-2, in the maintenance of integrity and possible physiological regulation of intermediate filaments.


Assuntos
Neoplasias Encefálicas/enzimologia , Ácido Okadáico/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Neoplasias Encefálicas/patologia , Citosol/enzimologia , Eletroforese em Gel Bidimensional , Ativação Enzimática , Gliossarcoma/enzimologia , Gliossarcoma/patologia , Imidazóis/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular , Cinetina , Mapeamento de Peptídeos , Fosforilação , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Purinas/farmacologia , Piridinas/farmacologia , Ratos , Células Tumorais Cultivadas
15.
J Neurooncol ; 36(2): 149-57, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9525814

RESUMO

Malignant gliomas have been associated with a high rate of glycolytic activity which is believed necessary to sustain cellular function and integrity. Since lonidamine (LND) is believed to reduce tumor glucose utilization by inhibition of the mitochondrially-bound glycolytic enzyme hexokinase (HK), 31P magnetic resonance spectroscopy (MRS) was used to noninvasively follow the effects of LND on both tumor pH and the high-energy phosphate metabolites: ATP, phosphocreatine (PCr) and inorganic phosphate (Pi) in subcutaneous rat 9L gliosarcomas. 31P tumor spectra acquired in 5 min intervals pre- and post LND administration of 50 and 100 mg/kg, i.p. revealed an acidotic pH shift of -0.25 and -0.45 pH units, respectively within 30 min post administration. The ATP/Pi ratio of 9L tumors decreased to 40% of control and Pi levels increased to 280% of control over a 3 hr period. LND exerted no effect on tumor blood flow and mean arterial blood pressure. Brain and muscle metabolite levels and pH were also unaffected by LND. In vitro measurements of cultured 9L tumor cell intra- and extracellular lactate, pentose phosphate pathway (PPP) and hexokinase (HK) activities suggest that the mode of action of LND involves inhibition of lactate efflux and intracellular acidification. The selective reduction of tumor energy metabolites and pH by LND may be exploitable for sensitizing gliomas to radiation, chemotherapy or hyperthermia.


Assuntos
Antineoplásicos/farmacologia , Neoplasias Encefálicas/metabolismo , Gliossarcoma/metabolismo , Indazóis/farmacologia , Líquido Intracelular/metabolismo , Ácido Láctico/metabolismo , Animais , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/enzimologia , Gliossarcoma/tratamento farmacológico , Gliossarcoma/enzimologia , Concentração de Íons de Hidrogênio , Injeções Subcutâneas , Espectroscopia de Ressonância Magnética , Masculino , Neoplasias Musculares , Transplante de Neoplasias , Radioisótopos de Fósforo , Ratos , Ratos Endogâmicos F344 , Coxa da Perna
16.
Hum Gene Ther ; 9(2): 185-93, 1998 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-9472778

RESUMO

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) generated in the stereoselective deamination of D-amino acids catalyzed by D-amino acid oxidase (DAAO). H2O2 readily crosses cellular membranes and damages DNA, proteins, and lipids. The scarcity of DAAO substrates in mammalian organisms and its co-localization with catalase in the peroxisomal matrix suggested that the cytotoxicity of ROS could be harnessed by administration of D-amino acids to tumor cells ectopically expressing DAAO in the cytoplasm. To evaluate this hypothesis, the cDNA encoding the highly active DAAO from the red yeast Rhodotorula gracilis was mutated to remove the carboxy-terminal peroxisomal targeting sequence. A clonal line of 9L glioma cells stably transfected with this construct (9Ldaao17) was found to synthesize active R. gracilis DAAO. Exposure of 9Ldaao17 cells to D-alanine resulted in cytotoxicity at concentrations that were nontoxic to parental 9L cells. Depletion of cellular glutathione further sensitized 9Ldaao17 cells to D-alanine (D-Ala). This result, combined with stimulation of pentose phosphate pathway activity and the production of extracellular H2O2 by 9Ldaao17 cells incubated with D-alanine implicates oxidative stress as the mediator of cytotoxicity. These results demonstrate that expression of R. gracilis DAAO in tumor cells confers chemosensitivity to D-alanine that could be exploited as a novel cancer gene therapy paradigm.


Assuntos
Alanina/toxicidade , Aminoácido Oxirredutases/genética , Neoplasias Encefálicas/tratamento farmacológico , Terapia Genética/métodos , Gliossarcoma/tratamento farmacológico , Estresse Oxidativo/efeitos dos fármacos , Rhodotorula/enzimologia , Alanina/uso terapêutico , Aminoácido Oxirredutases/biossíntese , Aminoácido Oxirredutases/uso terapêutico , Animais , Antioxidantes/metabolismo , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Catalase/metabolismo , Gliossarcoma/enzimologia , Gliossarcoma/metabolismo , Gliossarcoma/patologia , Glutationa Peroxidase/metabolismo , Peróxido de Hidrogênio/metabolismo , Ratos , Rhodotorula/genética , Células Tumorais Cultivadas
17.
Cancer Res ; 57(21): 4830-7, 1997 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-9354446

RESUMO

Intratumoral expression of cytochrome P450 2B1 sensitizes tumor cells to the cytotoxic action of the alkylating agent prodrug cyclophosphamide (CPA) and provides a novel strategy for cancer gene therapy that may enhance the selectivity and the effectiveness of this class of antitumor drugs [L. Chen and D. J. Waxman, Cancer Res., 55: 581-589, 1995]. P450-catalyzed drug metabolism is obligatorily dependent on electron input from the flavoenzyme NADPH-P450 reductase (RED), which is widely expressed in many cell types, including tumor cells. Here, we investigate the potential utility of combining RED gene transfer with CPA-based P450 gene therapy. Rat 9L gliosarcoma cells stably expressing either basal or elevated (up to 10-fold increase) levels of RED, in the presence or absence of P450 2B1, were selected and characterized. RED overexpression substantially increased the sensitivity of these cells to CPA, but only when combined with P450 2B1 expression. An enhanced cytotoxic response was also obtained when recombinant adenovirus encoding P450 2B1 was used to deliver the P450 gene to RED-overexpressing tumor cells. CPA cytotoxicity was substantially decreased by the RED inhibitor diphenyleneiodonium chloride or by the P450 inhibitor metyrapone, providing evidence of its dependence on the catalytic contributions of both protein components of the P450 metabolic pathway. Conditioned media from P450 2B1-expressing and RED-overexpressing tumor cells treated with CPA exhibited increased formation of the primary 4-hydroxy metabolite and greater cell contact-independent bystander cytotoxic potential compared to tumor cells containing P450 2B1 and basal levels of RED. Evaluation of the impact of P450/RED combination gene therapy using a s.c. solid tumor model/tumor excision assay revealed a dramatic 50-100-fold increase in tumor cell kill in vivo over that provided by liver drug activation alone. These findings establish the importance of endogenous RED levels as a determinant of the sensitivity of tumor cells to CPA/P450 gene therapy and demonstrate the striking therapeutic effectiveness of an anticancer prodrug activation strategy based on the combination of a cytochrome P450 gene with the gene encoding RED.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Ciclofosfamida/farmacologia , Citocromo P-450 CYP2B1/metabolismo , Terapia Genética/métodos , Gliossarcoma/terapia , NADH NADPH Oxirredutases/genética , Proteínas de Neoplasias/genética , Pró-Fármacos/farmacologia , Adenoviridae/genética , Animais , Antineoplásicos Alquilantes/metabolismo , Comunicação Celular/genética , Ciclofosfamida/metabolismo , Citocromo P-450 CYP2B1/antagonistas & inibidores , Feminino , Vetores Genéticos/genética , Gliossarcoma/enzimologia , Gliossarcoma/genética , Metirapona/farmacologia , NADH NADPH Oxirredutases/antagonistas & inibidores , NADH NADPH Oxirredutases/metabolismo , NADPH-Ferri-Hemoproteína Redutase , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Pró-Fármacos/metabolismo , Ratos , Ratos Endogâmicos F344 , Células Tumorais Cultivadas , Ensaio Tumoral de Célula-Tronco
18.
Tumour Biol ; 18(6): 321-31, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9372865

RESUMO

Several laboratories have introduced the lacZ gene into 9L cells to improve the usefulness of this already popular rat brain tumor model. However, these laboratories were not concerned about possible changes in the phenotypic characteristics of the 9L cell line which can be induced by the selection of lacZ-expressing clones. Here, we describe a method for introducing the lacZ gene into 9L cells without selective cloning. The 9L parent cells (passaged the same number of times) and 9L/lacZ cells were compared in a number of tests and found to have the same phenotype. Specifically, they had the same sensitivity to radiation from external gamma or internal beta radiation, the same growth rates with or without frequent media changes and the same patterns of growth in rat brain. We demonstrated that the 9L/lacZ cells could be sorted from dissociated tumors by flow cytometry and the percentage of nonmalignant versus malignant cells determined. These percentages were variable from rat to rat. The colony-forming efficiency could be determined on the basis of whole tumor or, by using the percent of lacZ-positive cells, on the basis of malignant cells in a tumor. These novel approaches should render the 9L tumor model even more useful.


Assuntos
Neoplasias Encefálicas/genética , Gliossarcoma/genética , Óperon Lac/genética , Transdução Genética/genética , Animais , Encéfalo/enzimologia , Encéfalo/patologia , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/patologia , Clonagem Molecular , Citometria de Fluxo , Vetores Genéticos , Gliossarcoma/enzimologia , Gliossarcoma/patologia , Fenótipo , Ratos , Ratos Endogâmicos F344 , Células Tumorais Cultivadas/patologia , Células Tumorais Cultivadas/transplante , beta-Galactosidase/metabolismo
19.
Int J Radiat Oncol Biol Phys ; 33(4): 861-8, 1995 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-7591895

RESUMO

PURPOSE: To demonstrate in a well-characterized tumor model that the radiosensitivity of tumor cells transduced with a herpes simplex virus thymidine kinase gene (HS-tk) would be selectively enhanced by antiviral agents. METHODS AND MATERIALS: Rat 9L gliosarcoma cells transduced with a retroviral vector containing an HS-tk gene, 9L-tk cells were exposed to various doses of irradiation under either in vitro or in vivo conditions. The radiation sensitizing potential of two antiviral drugs, bromovinyl deoxyuridine (BVdU) and dihydroxymethyl ethyl methyl guanine (acyclovir), was evaluated in vitro. The radiosensitizing ability of BVdU was also evaluated with a 9L-tk tumor growing in the rat brain. Tumors growing in the right hemisphere of rat brains were irradiated stereotactically with single-dose irradiation. RESULTS: The radiation response of 9L-tk cells was selectively enhanced by antiviral agents relative to nontransduced cells. In the cell culture, when a 24-h drug exposure (20 micrograms/ml) preceded radiation, the sensitizer enhancement ratio (SER) for BVdU and acyclovir was 1.4 +/- 0.1 and 1.3 +/- 0.1, respectively. Exposure of cells to 10 micrograms/ml acyclovir for two 24-h periods both pre- and postirradiation resulted in a SER of 1.6 +/- 0.1. In vivo, a significant increase in median survival time of rats with 9L-tk tumors was found when BVdU was administered prior to single-dose irradiation relative to the survival time of similar rats receiving radiation alone. CONCLUSION: An antiviral agent can enhance cell killing by radiation with selective action in cells transduced with the herpes simplex virus thymidine kinase gene. The results suggest that the three-pronged therapy of HS-tk gene transduction, systemically administered antiviral drug, and stereotactically targeted radiation therapy will improve the effectiveness of radiation therapy for the treatment of radioresistant tumors.


Assuntos
Aciclovir/farmacologia , Antivirais/farmacologia , Neoplasias Encefálicas/radioterapia , Bromodesoxiuridina/análogos & derivados , Gliossarcoma/radioterapia , Radiossensibilizantes/farmacologia , Timidina Quinase/genética , Transfecção/métodos , Animais , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/genética , Bromodesoxiuridina/farmacologia , Gliossarcoma/enzimologia , Gliossarcoma/genética , Masculino , Ratos , Ratos Endogâmicos F344 , Simplexvirus/enzimologia , Células Tumorais Cultivadas
20.
Cancer Res ; 54(22): 5745-51, 1994 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-7954393

RESUMO

Survival of rats harboring cerebral 9L gliosarcomas can be significantly extended by an intratumoral inoculation with a herpes simplex virus vector, designated as hrR3. This vector, which bears the lacZ reporter gene, is defective in the gene encoding ribonucleotide reductase, allowing for replication in dividing tumor cells but not in postmitotic neural cells. It also possesses an intact viral thymidine kinase (TK) gene, which confers chemosensitivity to ganciclovir. In this study, the ability of ganciclovir to potentiate the antitumor effect of hrR3 was evaluated. In culture, there was a 23% decrease in the growth of 9L cells treated with hrR3 plus ganciclovir compared to hrR3 alone (P < 0.01). The combination of hrR3 plus ganciclovir led to the long-term survival of 48% of rats harboring intracerebral 9L gliosarcomas compared to 20% survival in the hrR3 group (P < 0.05). Ganciclovir treatment had no effect on the growth of tumor cells in vitro or in vivo when a herpes simplex virus vector with a defective TK gene was used. Immunocytochemistry confirmed selective expression of the TK gene in cells within the tumor. These findings indicate that the TK gene can potentiate the antitumor effect of the hrR3 herpes simplex virus vector and provide the basis for placing additional therapeutic genes in the genome of hrR3.


Assuntos
Neoplasias Encefálicas/terapia , Ganciclovir/uso terapêutico , Terapia Genética/métodos , Gliossarcoma/terapia , Simplexvirus/genética , Timidina Quinase/genética , Animais , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/patologia , Terapia Combinada , Vetores Genéticos/genética , Gliossarcoma/enzimologia , Gliossarcoma/genética , Gliossarcoma/mortalidade , Gliossarcoma/patologia , Masculino , Ratos , Ratos Endogâmicos F344 , Simplexvirus/enzimologia , Timidina Quinase/análise , Células Tumorais Cultivadas
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