Effect of Hypoxia Inducible Factor-1α on Chemosensitivity of B-ALL Cells to Vincristine and Its Mechanism / 中国实验血液学杂志

OBJECTIVE@#To explore the effect of hypoxia on the chemosensitivity of B-acute lymphoblastic leukemia （B-ALL） cells to Vincristine (VCR) and the mechanisms.@*METHODS@#B-ALL cells SUP-B15, Nalm-6 and RS4;11 were selected as the research objects. The cells were divided into the control group and the hypoxia mimic group (CoCl2 pretreatment). The two groups were treated with VCR at different concentrations for 24 hours, CCK-8 was used to detect cell viability, flow cytometry was used to detect cell apoptosis, and Western bolt method was used to detect hypoxia inducible factor (HIF-1α), BAX, Bcl-2 and β-actin protein expression. Quantitative real-time fluorescent PCR (qRT-PCR) was used to detect BAX and β-actin mRNA levels.@*RESULTS@#CoCl2 could simulate hypoxic environment to induce the expression of HIF-1α. The cells SUP-B15 and RS4;11 of the hypoxia mimic group were lower sensitivity to VCR as compared with the control group; the apoptosis rate of the hypoxia mimic group was lower than that of the control group after 80 nmol/L VCR treatment. The expression levels of BAX protein and mRNA in the hypoxia mimic group were lower than those of the control group, and there was no significant difference in the expression levels of Bcl-2 protein between two groups.@*CONCLUSION@#Under hypoxic conditions, HIF-1α may mediate VCR resistance in B-ALL cells by downregulating the pro-apoptotic protein BAX.

Effect of Arrabidaea chica extract against chemically induced breast cancer in animal model

Abstract Purpose: To examine the effects of Arrabidaa chica (Bignoniacea) extract, a native plant of the Amazon known as crajiru, on a 7,12-dimethyl-1,2-benzanthracene (DMBA)-induced breast cancer model in Wistar rats. Methods: We compared the response of breast cancer to the oral administration of A. chica extract (ACE) for 16 weeks, associated or not with vincristine. Groups: normal control; DMBA (50mg/kg v.o,) without treatment; DMBA+ACE (300 mg/kg); DMBA+vincristine. 500μg/kg injected i.p; DMBA+ACE+Vincristine 250μg/kg i.p. Imaging by microPET and fluorescence, biochemistry, oxidative stress, hematology and histopathology were used to validate the treatments. Results: All animals survived. A gradual weight gain in all groups was observed, with no significant difference (p>0.05). The oral administration of ACE and ACE+vincristine 50% significantly reduced breast tumors incidence examined with PET-18FDG and fluorescence (p<0.001). Significant reduction of serum transaminases, oxidative stress and hematological toxicity were observed in these groups. Antioxidant enzyme levels in breast tissue were significantly higher compared to the DMBA and DMBA+vincristine groups. Conclusion: These results demonstrate for the first time that ACE positively influences the treatment of DMBA-induced breast cancer in animal model, inducing a reduction in oxidative stress and chemotherapy toxicity, meaning that ACE may have clinical implication in further studies.

Proteomic changes in a childhood acute lymphoblastic leukemia cell line during the adaptation to vincristine / Cambios en el proteoma de una línea celular de leucemia linfoblástica aguda infantil durante la adaptación a vincristina

Abstract: Introduction: Relapse occurs in approximately 20% of Mexican patients with childhood acute lymphoblastic leukemia (ALL). In this group, chemoresistance may be one of the biggest challenges. An overview of complex cellular processes like drug tolerance can be achieved with proteomic studies. Methods: The B-lineage pediatric ALL cell line CCRF-SB was gradually exposed to the chemotherapeutic vincristine until proliferation was observed at 6 nM, control cells were cultured in the absence of vincristine. The proteome from each group was analyzed by nanoHPLC coupled to an ESI-ion trap mass spectrometer. The identified proteins were grouped into over-represented functional categories with the PANTHER classification system. Results: We found 135 proteins exclusively expressed in the presence of vincristine. The most represented functional categories were: Toll receptor signaling pathway, Ras Pathway, B and T cell activation, CCKR signaling map, cytokine-mediated signaling pathway, and oxidative phosphorylation. Conclusions: Our study indicates that signal transduction and mitochondrial ATP production are essential during adaptation of leukemic cells to vincristine, these processes represent potential therapeutic targets.

Resumen: Introducción: Aproximadamente el 20% de los pacientes mexicanos con leucemia linfoblástica aguda (LLA) infantil presentan recaídas. En este grupo, la quimiorresistencia es uno de los principales desafíos. Los estudios proteómicos pueden dar un panorama general de procesos celulares complejos como la tolerancia a fármacos. Métodos: La línea celular de LLA de linaje B, CCRF-SB, fue expuesta de manera gradual al fármaco quimioterapéutico vincristina hasta observar proliferación celular en presencia de 6 nM, como control se cultivaron células en ausencia del fármaco. Se analizó el proteoma de cada grupo mediante nanoHPLC acoplado a un espectrómetro de masas de tipo trampa de iones. Las proteínas identificadas se agruparon en categorías funcionales sobre-representadas con el sistema de clasificación PANTHER. Resultados: Encontramos 135 proteínas expresadas exclusivamente en presencia de vincristina. Las categorías funcionales más representadas fueron la señalización asociada a los receptores tipo Toll, señalización dependiente de Ras, activación de células B y T, mapa de señalización CCKR, señalización mediada por citoquinas y la fosforilación oxidativa. Conclusiones: Nuestro estudio indica que la transducción de señales y la producción de ATP mitocondrial son procesos esenciales durante la adaptación de células leucémicas a vincristina por lo que estos procesos representan potenciales blancos terapéuticos.

Isolation of breast cancer stem cell from MDA-MB231 cell line using vincristine / Aislamiento de células madre de cáncer de mama de la línea celular MDA-MB231 utilizando vincristina

Cancer has been considered as a stem cell disease. Suspension culture combined with anti-cancer drugs has recently been proposed for isolation of cancer stem cells (CSCs). In the current study, Vincristine as an anti-cancer drug combined with suspension culture was used for isolation and purification of CSCs from human breast cancer cell line (MDA-MB231). The cells were treated with different concentrations of vincristine (0, 2, 4, 6 and 8 ng/ml). Stem cells were identified with the expression of OCT4, nanog, SOX2 and nucleostemin genes by RT-PCR. Mammosphere forming unit was measured upon suspension culture containing EGF, bFGF, LIF, B27, insulin and BSA. The isolated mammospheres were investigated for CD44 expression. Results showed that 4 ng/ml of vincristine for 72 hours could be utilized as the best and most reliable dose which eliminates around 80 % of non-cancer stem cells with no destructive effect on CSCs' viability (P> 0.05). RT-PCR demonstrated that drug treated cells expressed OCT4, nanog, SOX2 and nucleostemin. Mammosphere formation unit of cells pretreated with vincristine was significantly higher than unpretreated ones (P>0.05). Immunofluorescence staining for CD44 depicted high expression of CSC marker among the isolated mammospheres. Vincristine combined with suspension culture can be considered as an appropriate method to isolate CSC.

El cáncer ha sido considerado como una enfermedad de células madre. Recientemente se ha propuesto cultivo en suspensión en combinación con medicamentos contra el cáncer para aislamiento de las células madre del cáncer (CMC). En este estudio se utilizó la vincristina como fármaco anticanceroso combinado con cultivo en suspensión para el aislamiento y purificación de las células madre cancerosas, de la línea celular de cáncer de mama humano (MDA-MB231). Las células se trataron con diferentes concentraciones de vincristina (0, 2, 4, 6 y 8 ng/ml). Las células madre se identificaron mediante la expresión de los genes OCT4, Nanog, SOX2 y nucleostemin por RT-PCR. La unidad de formación mammosphere se midió a través de cultivo en suspensión que contenía EGF, bFGF, LIF, B27, insulina y BSA. Los mammospheres aislados fueron estudiados para la expresión de CD44. Los resultados mostraron que 4 ng/ml de vincristina durante 72 horas podrían ser utilizados como la mejor y más fiable dosis que permite eliminar alrededor del 80 % de las células madre no cancerosas, sin causar un efecto destructivo sobre la viabilidad de las CMC (P> 0,05). La RT-PCR mostró que en las células tratadas con él fármaco hubo expresión de los genes OCT4, Nanog, SOX2 y nucleostemin. La unidad de formación de las células pretratadas con vincristina fue significativamente más alta que las unidades sin tratamiento previo (P>0,05). La inmunofluorescencia para CD44 muestró una alta expresión del marcador de CMC entre mammospheres aisladas. La vincristina en combinación con el cultivo en suspensión puede ser considerado como un método apropiado para aislar CMC.

Identification of microRNAs and mRNAs associated with multidrug resistance of human laryngeal cancer Hep-2 cells

Multidrug resistance (MDR) poses a serious impediment to the success of chemotherapy for laryngeal cancer. To identify microRNAs and mRNAs associated with MDR of human laryngeal cancer Hep-2 cells, we developed a multidrug-resistant human laryngeal cancer subline, designated Hep-2/v, by exposing Hep-2 cells to stepwise increasing concentrations of vincristine (0.02-0.96'µM). Microarray assays were performed to compare the microRNA and mRNA expression profiles of Hep-2 and Hep-2/v cells. Compared to Hep-2 cells, Hep-2/v cells were more resistant to chemotherapy drugs (∼45-fold more resistant to vincristine, 5.1-fold more resistant to cisplatin, and 5.6-fold more resistant to 5-fluorouracil) and had a longer doubling time (42.33±1.76 vs 28.75±1.12'h, P<0.05), higher percentage of cells in G0/G1 phase (80.98±0.52 vs 69.14±0.89, P<0.05), increased efflux of rhodamine 123 (95.97±0.56 vs 12.40±0.44%, P<0.01), and up-regulated MDR1 expression. A total of 7 microRNAs and 605 mRNAs were differentially expressed between the two cell types. Of the differentially expressed mRNAs identified, regulator of G-protein signaling 10, high-temperature requirement protein A1, and nuclear protein 1 were found to be the putative targets of the differentially expressed microRNAs identified. These findings may open a new avenue for clarifying the mechanisms responsible for MDR in laryngeal cancer.

In vitro evaluation of vincristine and fluconazole combination against Candida

Infections associated with cancer are a major scourge and cause of substantial morbidity and mortality in cancer patients. The aim of present study was to appraise the in vitro activity of anticancer agent vincristine and antifungal fluconazole alone and in combination against Candida spp. Results were interpreted in terms of fractional inhibitory concentration index [FICI]. Antifungal activity of fluconazole showed marked synergism when used in combination with vincristine, with FICI ranging from 0.25-0.5 against different Candida spp. Although, the use of vincristine with fluconazole is always disputed due to its side effects including decreased peristalsis, but the present research can help to perform suitability analysis of fluconazole use in life threatening invasive candidiasis associated with cancer patients. In addition, the synergism in antifungal activity after using with vincristine also warrants further research in the direction of minimizing adverse reaction associated with combined use of fluconazole and vincristine

Isolation of stem-like cells from human MG-63 osteosarcoma cells using limiting dilution in combination with vincristine selection.

To isolate stem-like cells from the human MG-63 osteosarcoma cell line, different subpopulations of MG-63 cells were cloned by limiting dilution and passaged to obtain different sublines. The subline with highest clonogenicity was identified using a proliferation assay, cell-cycle analysis, and soft-agar colony-forming assay. The sublines were further selected in serum-free medium containing 20 ng/ml vincristine to identify cells that could form suspended sarcospheres. Identified cells were then characterized based on morphology, cell surface markers, adipogenic and osteogenic differentiation, and tumorigenicity in nude mice. A total of 19 holoclones that could be stably passaged were obtained. Sublines A1, A3, and D1 were markedly different from other sublines and the parental cell line. Subline D1 not only had a higher colony-forming efficiency and formed larger colonies, but also possessed a shorter latency of tumorigenesis in vivo. After subline D1 was cultured in suspension in medium containing vincristine, a highly enriched subpopulation of cells that could form sarcospheres and be stably passaged were obtained. These cells, designated as MG-63-M expressed multiple markers of multipotent or embryonic stem cells and possessed the capacity for self-renewal, multilineage differentiation, and significant multi-drug resistance. Thus, our results suggest that a subpopulation of stem-like cells can be isolated from human MG-63 osteosarcoma cell line.

Does usnic acid affect microtubules in human cancer cells? / O ácido úsnico pode afetar microtúbulos em células cancerosas humanas?

Usnic acid, a lichen metabolite, is known to exert antimitotic and antiproliferative activities against normal and malignant human cells. Many chemotherapy agents exert their activities by blocking cell cycle progression, inducing cell death through apoptosis. Microtubules, protein structure involved in the segregation of chromosomes during mitosis, serve as chemotherapeutical targets due to their key role in cellular division as well as apoptosis. The aim of this work was to investigate whether usnic acid affects the formation and/or stabilisation of microtubules by visualising microtubules and determining mitotic indices after treatment. The breast cancer cell line MCF7 and the lung cancer cell line H1299 were treated with usnic acid 29 µM for 24 hours and two positive controls: vincristine (which prevents the formation of microtubules) or taxol (which stabilizes microtubules). Treatment of MCF7 and H1299 cells with usnic acid did not result in any morphological changes in microtubules or increase in the mitotic index. These results suggest that the antineoplastic activity of usnic acid is not related to alterations in the formation and/or stabilisation of microtubules.

O ácido úsnico, um metabólito de liquens, é conhecido por sua atividade antimitótica e antiproliferativa em células humanas normais e malignas. Muitos quimioterápicos exercem suas atividades bloqueando a progressão do ciclo celular e induzindo morte celular por apoptose. Os microtúbulos, estruturas protéicas envolvidas na segregação dos cromossomos durante a mitose, servem como alvo quimioterapêutico devido ao seu importante papel tanto na divisão celular quanto nos mecanismos de morte celular por apoptose. O objetivo deste trabalho foi investigar se o ácido úsnico afeta a formação e/ou estabilização dos microtúbulos, a partir da visualização de microtúbulos e determinação de índices mitóticos após o tratamento. Células de câncer de mama MCF7 e de câncer de pulmão H1299 foram tratadas por 24 horas com 29 µM de ácido úsnico e dois controles positivos: vincristina (que impede a formação de microtúbulos) e taxol (que estabiliza microtúbulos). O tratamento das células MCF7 e H1299 com o ácido úsnico não resultou em aumento do índice mitótico. Os resultados sugerem que a atividade antineoplásica do ácido úsnico não está relacionada a alterações na formação e/ou estabilização de microtúbulos.

Vincristine delays gastric emptying and gastrointestinal transit of liquid in awake rats

We evaluated the effects of vincristine on the gastrointestinal (GI) motility of awake rats and correlated them with the course of vincristine-induced peripheral neuropathy. Vincristine or saline was injected into the tail vein of male Wistar rats (180-250 g) on alternate days: 50 µg/kg (5 doses, N = 10), 100 µg/kg (2, 3, 4 and 5 doses, N = 49) or 150 µg/kg (1, 2, or 5 doses, N = 37). Weight and stool output were measured daily for each animal. One day after completing the vincristine treatment, the animals were fasted for 24 h, gavage-fed with a test meal and sacrificed 10 min later to measure gastric emptying (GE), GI transit and colon weight. Sensory peripheral neuropathy was evaluated by hot plate testing. Chronic vincristine treatments with total cumulative doses of at least 250 µg/kg significantly decreased GE by 31-59 percent and GI transit by 55-93 percent. The effect of 5 doses of vincristine (150 µg/kg) on GE did not persist for more than 1 week. Colon weight increased after 2 and 5 doses of vincristine (150 µg/kg). Fecal output decreased up to 48 h after the fifth dose of vincristine (150 µg/kg). Vincristine decreased the heat pain threshold 1 day after 5 doses of 50-100 µg/kg or after 3-5 doses of 150 µg/kg. This effect lasted for at least 2 weeks after the fifth dose. Chronic intravenous vincristine treatment delayed GE and GI transit of liquid. This effect correlated with the peak increase in colon weight but not with the pain threshold changes.

Cytotoxic and DNA-topoisomerase effects of lapachol amine derivatives and interactions with DNA

The cytotoxic activity of amino (3a-e), aza-1-antraquinone (4a-e) lapachol derivatives against Ehrlich carcinoma and human K562 leukemia cells was investigated. Cell viability was determined using MTT assay, after 48 (Ehrlich) or 96 h (K562) of culture, and vincristine (for K562 leukemia) and quercetin (for Ehrlich carcinoma) were used as positive controls. The results showed dose-dependent growth-inhibiting activities and that the amino derivatives were active against the assayed cells, whereas the 4a-e derivatives were not. The allylamine derivative 3a was the most active against Ehrlich carcinoma, with IC50 = 16.94 ± 1.25 muM, and against K562 leukemia, with IC50 = 14.11 ± 1.39 muM. The analogous lawsone derivative, 5a, was also active against Ehrlich carcinoma (IC50 = 23.89 ± 2.3 muM), although the 5d and 5e derivatives showed lower activity. The interaction between 3a-d and calf thymus DNA was investigated by fluorimetric titration and the results showed a hyperchromic effect indicating binding to DNA as presented of ethidium bromide, used as positive control. The inhibitory action on DNA-topoisomerase II-a was also evaluated by a relaxation assay of supercoiled DNA plasmid, and the etoposide (200 muM) was used as positive control. Significant inhibitory activities were observed for 3a-d at 200 muM and a partial inhibitory action was observed for lapachol and methoxylapachol.

A study of the effects of pinealectomy on intestinal cell proliferation in infant newborn rats

OBJETIVO: Estudar a taxa de proliferação celular no jejuno e nas células epiteliais das criptas do intestino grosso em ratos pinealectomizados imediatamente após o nascimento. MÉTODOS: 24 ratos machos Wistar foram divididos em dois grupos. Grupo agudo (n=12) e Grupo Crônico (n=12). Seis animais de cada grupo foram operados para remover-se a glândula pineal (Pinealectomia-PnX), e outros seis animais foram controle (sham pinealectomia-C). Os animais de ambos os grupos foram sacrificados 15 e 90 dias após a cirurgia, respectivamente. RESULTADOS: No grupo agudo, a pinealectomia dos ratos não causou alterações significativas na proliferação celular (PnX=58,77±1,77 e C=60,88±1,10 no cólon descendente / PnX=31,56±0,45 e C=31,73±0,47 no jejuno proximal) e na população celular de criptas (PnX=24,92±4,82 e C=23,60±2,48 no cólon descendente / PnX=39,92±3,49 e C=44,32±5,56 no jejuno proximal). Contudo, no grupo crônico houve aumento na proliferação celular das criptas no jejuno proximal (PnX=57,54±2,19 e C=47,19±7,3), e no cólon descendente (PnX=37,78±2,22 e C=17,92±2,28). CONCLUSAO: Como o aumento epitelial celular das criptas intestinais no grupo crônico pode ser avaliado como fator predeterminante da carcinogênese, faz-se necessário o conhecimento da interação entre esta glândula e este evento.

Multidrug resistance in tumour cells: characterization of the multidrug resistant cell line K562-Lucena 1

Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed

Quimioterapia neoadyuvante en cáncer de cuello uterino localmente avanzado / Neoadjuvant chemotherapy in advanced cervical cancer

Se presentan los resultados de una serie clínica de 15 pacientes portadoras de cáncer escamoso de cuello uterino localmente avanzado, estadios clínico I B2-II B, a quienes se les administró una quimioterapia neoadyuvante con cisplatino, vincristina y bleomicina durante 3 ciclos y luego fueron evaluadas para cirugía radical. Se logró una respuesta parcial o completa que permitió realizar la cirugía en 14 de las 15 pacientes tratadas. Cuando los márgenes o los ganglios estuvieron positivos para tumor se agregó raditerapia pelviana

Early results evaluating the efficacy and toxicity of adriamycin, vincristine and etoposide Ave in the management of childhood hodgkin's disease

This study aimed to evaluate efficacy and toxicity of adriamycin, vincristine and etoposide in the management of childhood Hodgkin's disease as a salvage and first line therapy as well as limiting the use of involved field radiotherapy to partial responders to avoid unnecessary complications of radiotherapy children. Thirty-six patients with Hodgkin's disease were included in this study, twenty- four had no previous treatment and twelve were previously treated with either C-MOPP or Chl-VPP [five of them had refractory disease and the remaining seven attained a complete remission but relapsed later]. All patients were treated with adriamycin 30 mg/m2, vincristine 1.4 mg/m2 and etoposide 100 mg/m2 D1 and D15 repeated every 28 days for six cycles. Partial responders [PR] were subjected to a field radiation treatment after three cycles of chemotherapy [20 Gy/ten treatments/two weeks]. At the end of the six cycles of chemotherapy, all patients were in a complete remission [CR]. All the previously untreated patients were in a complete remission after a median follow up of 15.5 months. The relapse free survival in previously treated patients was 58.3% after a median follow up of 14 months. The relapse free survival for the whole group was 86.7% after a median follow up of 15 months

Suppression of multidrug resistance via inhibition of heat shock factor by quercetin in MDR cells

MDR1 promoter has been shown to contain heat shock elements (HSE), and it has been reported that FM3A/M and P388/M MDR cells show a constitutively activated heat shock factor (HSF), suggesting that HSF might be an important target for reversing the multidrug resistance. Therefore, it was examined whether quercetin, which has been shown to interfere with the formation of the complex between HSE and HSF, and to downregulate the level of HSF1, can sensitize MDR cells against anticancer drugs by inhibition of HSF DNA-binding activity. In this study, quercetin appeared to inhibit the constitutive HSF DNA-binding activity and the sodium arsenite-induced HSF DNA-binding activity in the MDR cells. The basal and sodium arsenite-induced MDRCAT activities were remarkably suppressed by the treatment of quercetin. These results were well consistent with the finding that the treatment of quercetin decreased the expression level of P-gp, MDR1 gene product, in dose-dependent manner, and markedly increased the sensitivity of MDR cells to vincristine or vinblastine. These results suggest that quercetin can decrease the expression of P-gp via inhibition of HSF DNA-binding activity, and might be useful as a chemosensitizer in MDR cells.

Specific effect of vincristine on epididymis.

Wistar strain male albino rats were administered with vincristine (VCR) sulphate (10 micrograms/day for 15 days); epithelial cell types of the caput (zone II) and cauda (zone V) were studied light microscopically adopting semithin sectioning. VCR caused conspicuous pathological changes in the principal and apical cells of the caput and the clear cells of the cauda. The study points to toxic effect of VCR on these cell types, suggesting impairment of epididymal function, particularly concerning sperm maturation and endocytotic removal of the contents of the cytoplasmic droplets and dead sperm.

Quimioterapia basada en cisplatino más vincristina, bleomicina y etoposide en ciclos semanales para neoplasias de células germinales / Chemotherapy based on cisplatin plus, bleomycin and ethoposide in weekly cycles for germ-cell malignancies

La finalidad de esta investigación prospectiva fue evaluar la eficacia de los fármacos quimioterapéuticos para las neoplasias de células germinales. El protocolo consistió en cisplatino, bleomicina, vincristina y etoposide en dosis semanales (6 ciclos), que se administraron a siete varones con etapas B (5) y C (2) identificadas según historia clínica, exploración física, exámenes de laboratorio y de imágenes y marcadores tumorales. Se estableció una eficacia posquimioterapéutica de 71 por ciento, con 86 por ciento de reacciones completas, 14 por ciento de reacciones parciales y promedio de recaídas de 28 por ciento, con resultados similares a los de otros estudios. Se observó tolerancia adecuada con toxicidad mínima, sólo estadísticamente significativa para leucocitos y eritrocitos, pues esta protocolo resultó menos tóxico y más seguro que otros esquemas con una estancia hospitalaria menor (promedio 2 días por ciclo), lo que además redujo costos. El periodo de seguimiento fue de 13.2 ñ 6.5 meses

Multidrug resistance in leukemias: the problem and some approaches to its circumvention

The phenomenon of multidrug resistance (MDR), representing cross-resistance among a number of unrelated chemotherapeutic drugs, is the major cause of chemotherapy failure in many tumors. It has been also detected in leukemias and in these cancers, as well as in many others, resistance can be reversed by a number of substances known as modulators or reversing agents. The capacity of identifying tumors resistant to chemotherapy could orientate the treatment employed. In leukemias, tumor cells are easily obtainable and many techniques have been used to evaluate resistance in these cells. Studying 42 leukemia patients we found a correlation of nearly 60 per cent among surface expression of P-glycoprotein, in vitro resistance reversal by cyclosporin A (CS-A) and extrusion of the rhodamine 123 dye. This latter assay has the advantage of measuring a functional aspect related to resistance (intracellular drug accumulation), being reproducible and affordable by most laboratories. The data generated by this assay were in accordance with those reported by other authors using different methods. To allow for an experimental approach in the study of MDR in leukemias, an in vitro model of a vincristine-induced erythroleukemia resistant cell line was established by us, and was shown to display MDR characteristics: resistance to unrelated drugs, surface expression of P-glycoprotein, extrusion of rhodamine 123 and resistance reversal by trifluoperazine, a reversing agent. Furthermore, this vincristine-resistant line was as sensitive to cell mediated lysis by natural killer (NK) cells as the parental line. Models like this one allow for the in vitro testing of new reversing agents, and when combined to in vitro tests for NK and LAK activity, may select for substances capable of modulating resistance without affecting a potentially useful cell mediated immunotherapy.

Estabelecimento de um método "in vitro" de controle biológico de agentes antineoplásicos em uso no Instituto Nacional de Câncer

O objetivo do presente trabalho foi desenvolver um método capaz de verificar a eficácia, a nível biológico, das drogas antineoplásicas, que näo necessitem de metabolismo prévio para sua açäo e que atualmente estäo sendo usadas no Instituto Nacional de Câncer (INCa). O princípio de ensaio foi baseado na medida de inibiçäo da proliferaçäo celular da linhagem K562 e de células ativadas por fitohemaglutinina (PHA), usando-se como marcador a incorporaçäo no DNA de timidina tritiada. Conclui-se que esse ensaio näo é adequado para testar a atividade antitumoral do Methotrexate, mas pode ser extremamente sensível para os estudos com derivados da Vinca