Crocin, a dietary colorant, mitigates cyclophosphamide-induced organ toxicity by modulating antioxidant status and inflammatory cytokines.

OBJECTIVES: This study investigated the protective efficacy of crocin against hepatotoxicity induced by cyclophosphamide (CP) in Wistar rats. METHODS: The experimental rats were treated with crocin orally at a dose of 10 mg/kg for 6 consecutive days after the administration of a single intraperitoneal dose of CP (150 mg/kg). The ameliorative effect of crocin on organ toxicity was studied by evaluating oxidative stress enzymes, inflammatory cytokines and histological sections. KEY FINDINGS: A single intraperitoneal CP injection significantly elevated endogenous reactive oxygen species and oxidation of lipids and proteins, which are the hallmarks of oxidative damage in liver and serum. In consequence, the primary defensive reduced glutathione, total thiol and antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase and glutathione peroxidase, were significantly reduced. In addition, liver and serum aspartate aminotransferase and alanine aminotransferase along with acid and alkaline phosphatase were considerably increased. Oral administration of crocin significantly rejuvenated all the above altered markers to almost normal state. The protective efficacy of crocin was further supported by the histological assessment and restoration of CP-induced inflammatory cytokines and enzyme levels compared with the control drug. CONCLUSION: The results obtained suggest the protective nature of crocin against CP-induced oxidative damage/inflammation and organ toxicity.

Thymoquinone attenuates cyclophosphamide-induced pulmonary injury in rats.

OBJECTIVE: Antioxidant therapy may be useful in diseases with impaired oxidant-antioxidant balance. This study was designed to examine the effects of thymoquinone (TQ), an anti-inflammatory, antioxidant agent against cyclophosphamide (CP)-induced pulmonary oxidative damage. MATERIALS AND METHODS: Male Sprague-Dawley rats were categorized into four groups. Group I was control. Group II received TQ (100 mg/kg/day, p.o.) for 14 consecutive days. Group III was injected once with CP (150 mg/kg, i.p.). Group IV received TQ for 7 consecutive days, before and after CP injection. The parameters of study were tissue oxidant/antioxidant biomarkers and histological changes in rat lungs. RESULTS: A single intraperitoneal injection of CP markedly altered the levels of several biomarkers in lung homogenates. Significant increases in the content of lipid peroxides in lung were seen that paralleled the decreased levels of reduced glutathione. Cyclophosphamide increased the level of serum biomarkers: total protein, lactate dehydrogenase, and tumor necrosis factor-alpha (TNF-α). Treatment of rats with TQ 7 days before and after cyclophosphamide injection significantly attenuated the alterations in lung and serum biomarkers associated with inflammatory reactions, with less lipid peroxidation and restoration of antioxidants. Moreover, TQ attenuated the secretion of pro-inflammatory cytokine, TNF-α in rat serum. In addition, TQ effectively alleviated CP-induced histopathological changes in lung tissue. DISCUSSION AND CONCLUSION: Our results suggest that TQ produces a protective mechanism against CP-induced pulmonary damage and suggest a role of oxidative stress and inflammation in the pathogenesis.

Protection by Salvia extracts against oxidative and alkylation damage to DNA in human HCT15 and CO115 cells.

DNA damage induced by oxidative and alkylating agents contributes to carcinogenesis, leading to possible mutations if replication proceeds without proper repair. However, some alkylating agents are used in cancer therapy due to their ability to induce DNA damage and subsequently apoptosis of tumor cells. In this study, the genotoxic effects of oxidative hydrogen peroxide (H2O2) and alkylating agents N-methyl-N-nitrosourea (MNU) and 1,3-bis-(2-chloroethyl)-1-nitosourea (BCNU) agents were examined in two colon cell lines (HCT15 and CO115). DNA damage was assessed by the comet assay with and without lesion-specific repair enzymes. Genotoxic agents were used for induction of DNA damage in both cell lines. Protective effects of extracts of three Salvia species, Salvia officinalis (SO), Salvia fruticosa (SF), and Salvia lavandulifolia (SL), against DNA damage induced by oxidative and alkylating agents were also determined. SO and SF protected against oxidative DNA damage in HCT15 cells. SO and SL decreased DNA damage induced by MNU in CO115 cells. In addition to chemopreventive effects of sage plant extracts, it was also important to know whether these plant extracts may interfere with alkylating agents such as BCNU used in cancer therapy, decreasing their efficacy. Our results showed that sage extracts tested and rosmarinic acid (RA), the main constituent, protected CO115 cells from DNA damage induced by BCNU. In HCT15 cells, only SF induced a reduction in BCNU-induced DNA damage. Sage water extracts and RA did not markedly change DNA repair protein expression in either cell line. Data showed that sage tea protected colon cells against oxidative and alkylating DNA damage and may also interfere with efficacy of alkylating agents used in cancer therapy.

Impact of ERCC1 expression on treatment outcome in small-cell lung cancer patients treated with platinum-based chemotherapy.

INTRODUCTION: The excision repair cross-complementing 1 (ERCC1) protein is an extensively investigated molecular marker because it may decrease sensitivity to platinum-based chemotherapy. Low ERCC1 expression has already been correlated with better treatment efficacy in non-small-cell lung cancer patients treated with platinum-based chemotherapy. However, the data on a prognostic and/or predictive value of ERCC1 in small-cell lung cancer (SCLC) are still very limited. METHODS: This retrospective pilot study evaluated the impact of ERCC1 expression levels on response to first-line platinum-based chemotherapy with or without radiotherapy and survival outcomes of 77 SCLC patients. ERCC1 protein expression was determined immunohistochemically in primary tumour tissue. RESULTS: ERCC1 protein expression was positive in 40/77 (51.9%) of our patients. No significant association was found between ERCC1 protein expression and response rate to first-line platinum-based chemotherapy, progression-free survival (PFS), or overall survival (OS), either in the overall population or in patients stratified by disease stage. CONCLUSIONS: In our limited group of 77 SCLC patients, ERCC1 protein expression was not found to correlate with either response rate to platinum-based chemotherapy or survival outcomes. Multi-centric prospective trials using a validated method of ERCC1 determination are mandatory in order to obtain a definitive answer on the predictive value of ERCC1 in SCLC.

Egyptian sweet marjoram leaves protect against genotoxicity, immunosuppression and other complications induced by cyclophosphamide in albino rats.

Cyclophosphamide (CP) is one of the most popular alkylating anticancer drugs that show a high therapeutic index, despite the widespread side effects and toxicity particularly in high-dose regimens and long-term use. Here, we evaluated and compared the efficacy of two different doses (50 and 100 mg/kg body weight, given orally for 30 consecutive days) of Egyptian sweet marjoram leaf powder (MLP) and marjoram leaf aqueous extract (MLE) in alleviating the genotoxicity, immunosuppression and other complications induced by CP in non-tumour-bearing albino rats. The present study showed (probably for the first time) that both MLP and MLE significantly alleviated (P < 0·05-0·001) most side effects and toxicity of CP-treated rats including the increase in chromosomal aberrations of bone marrow cells and serum malondialdehyde level, the decrease in the level of serum Ig, the delayed type of hypersensitivity response as also the weights and cellularity of lymphoid organs, and myelosuppression, leucopenia, macrocytic normochromic anaemia as well as thrombocytopenia by reactivating the non-enzymic (reduced glutathione) and enzymic (catalase, glutathione peroxidase, glutathione S-transferase, superoxide dismutase) antioxidant system and increasing the mitotic index of bone marrow cells. The modulatory effects of marjoram leaves shown in the present study were dose dependent in most cases and much higher in MLE (21-23 % for all parameters taken together). In addition, the doses used in the present study were considered safe. In conclusion, sweet marjoram leaves (especially in the form of a herbal tea) may be useful as an immunostimulant and in reducing genotoxicity in patients under chemotherapeutic interventions.

Prevention of chemotherapy-induced osteoporosis by cyclophosphamide with a long-acting form of parathyroid hormone.

BACKGROUND: Most chemotherapeutics reduce bone mineral density (BMD) and increase risk for fractures by causing gonadal suppression, which in turn increases bone removal. Cyclophosphamide (CYP) also has a direct effect of inhibiting bone formation and removal, making the resulting bone loss particularly difficult to treat with antiresorptive therapy. AIM: We tested whether a single dose of the anabolic agent PTH linked to a collagen binding domain (PTHCBD) could prevent the effects of CYP-induced bone loss. METHODS: Mice received either buffer alone, CYP, or CYP+ PTH-CBD. BMD and alkaline phosphatase were measured every 2 weeks for a total of 8 weeks. RESULTS: After 6 weeks, mice treated with CYP showed expected reductions in BMD (increase from baseline: 7.4 ± 6.9 vs 24.35 ± 4.86% in mice without chemotherapy, p<0.05) and decrease in alkaline phosphatase levels (42.78 ± 6.06 vs 60.62 ± 6.23 IU/l in mice without chemotherapy, p<0.05), consistent with osteoporosis from impaired bone formation. Administration of a single dose of PTH-CBD (320 µg/kg ip) prior to CYP treatment improved BMD (change from baseline: 23.4 ± 5.4 vs 7.4 ± 6.9%, CYP treatment alone, p<0.05) and increased alkaline phosphatase levels (50.14 ± 4.86 vs 42.78 ± 6.06 IU/l in CYP treatment alone, p<0.05). BMD values and alkaline phosphatase levels were restored to those seen in mice not receiving chemotherapy. CONCLUSIONS: A single dose of PTHCBD prior to chemotherapy reversed CYP-induced suppression of bone formation and prevented CYP-induced bone loss in mice.

Cytoprotective effects of DL-alpha-lipoic acid or squalene on cyclophosphamide-induced oxidative injury: an experimental study on rat myocardium, testicles and urinary bladder.

The present study aimed to evaluate the role of DL-alpha-lipoic acid (LA) and squalene (SQ) on oxidative cardiac, testicular and urotoxic damage induced by cyclophosphamide (CP). Male Wistar rats were divided into four groups; three groups received a single intraperitoneal injection of CP (200mg/kg BW) to induce toxicity, and two of these groups received either LA (35 mg/kg BW) or SQ (0.4 ml/rat) orally 7 days before and 7 days after CP injection. A vehicle-treated control group was also included. Oxidative damage was observed by decreased serum total antioxidant capacity (TAC) level and abnormal alterations in glutathione peroxidase (GPx) and glutathione reductase (GR) activities, levels of glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO) and calcium (Ca(+2)) in the heart, testes and urinary bladder of CP-administered rats. Cardiac marker enzyme activities; creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and aspartate transaminase (AST) showed severe declines whereas testicular markers; sorbitol dehydrogenase (SDH), gamma-glutamyl transferase (gamma-GT), acid and alkaline phosphatases (ACP and ALP), serum testosterone (T) level and haemoglobin (Hb) absorbance were abnormal. Histopathological observations were also altered. These CP-induced pathological alterations were attenuated by treatment with LA or SQ. These findings highlight the efficacy of LA and SQ as cytoprotectants in CP-induced toxicity.

Protective effects of Nigella sativa oil and thymoquinone against toxicity induced by the anticancer drug cyclophosphamide.

Constituents of the Nigella sativa seed are reported to possess potent antioxidant effects. Treatment with anticancer drugs such as cyclophosphamide (CTX) is associated with significant toxicity due to over-production of reactive oxygen species, resulting in increased levels of oxidative stress. The aim of this study is to test whether or not N. sativa L oil (NSO) or its active ingredient, thymoquinone (TQ), can reduce CTX-induced toxicity. Male albino rats were treated with intraperitoneal administration of phosphate buffered saline (PBS) or 200 mg/Kg CTX followed by intragastric administration of NSO or TQ on alternate days for 12 days. Administration of NSO and TQ was initiated 6 h before or after CTX injection. Twenty-four hours after the last NSO and TQ treatment, blood and liver were harvested to analyse toxicity-related parameters. Treatment with CTX induced significant toxicity as shown by decrease in haemoglobin concentration and increases in blood sugar levels, activities of liver enzymes, bilirubin, urea, creatinine, lipids (triglyceride, cholesterol and low-density lipoprotein (LDL)-cholesterol) and lipid peroxidation in the liver. Treatment with NSO or TQ induced significant reduction in overall toxicity. The antitoxic effects of NSO and TQ were associated with induction of antioxidant mechanisms. These results suggest that administration of NSO or TQ can lower CTX-induced toxicity as shown by an up-regulation of antioxidant mechanisms, indicating a potential clinical application for these agents to minimise the toxic effects of treatment with anticancer drugs.

Supplementation of melatonin protects human lymphocytes in vitro from the genotoxic activity of melphalan.

Melatonin (MLT) is a natural oncostatic factor of the human body as well as an antioxidant thus protects the nuclear DNA from oxidative damage. It also has the ability to reduce the side effects of various drugs when used as a combination therapy. The anti-neoplastic agent melphalan (MEL), which encompasses a number of side effects, is a strong alkylating agent and a potent inducer of sister chromatid exchanges (SCEs). The aim of the current in vitro study was to investigate the ability of MLT to reduce the genotoxic effect of MEL on normal human cultured peripheral lymphocytes. Cells were treated with both agents at various concentrations (MLT 100, 200 and 400 microM and MEL 330, 490 and 650 nM) and incubated for 72 h prior harvesting. The levels of cytostaticity, cytotoxicity and genotoxicity were qualitatively evaluated using the proliferation rate index, the mitotic index and the SCE methodology, respectively. Our results demonstrated the protective effect of MLT on cells treated with MEL in vitro. The greatest protective effect of MLT at 100 and 400 microM was illustrated against 330 nM of MEL in comparison with all other doses of MEL. These observations imply that MLT may be proved useful in reducing some of the toxic effects associated with certain classes of chemotherapeutic agents and other chemical and physical mutagens and carcinogens, acting both as an antioxidant-radical scavenger and a protective mechanism against cellular damage due to exposure to free radical-producing agents. It is essential to investigate substances with protective properties which are normally produced from the human body.

Antigenotoxic effect of apigenin against anti-cancerous drugs.

Mitomycin C and cyclophosphamide are well known anti-tumor drugs. Their genotoxic effects are well established in various test systems. The genotoxic effects in non-tumor cell are of special significance due to the possibility that they may induce secondary tumors in cancer patients. Apigenin is a well known anti-oxidant and possess number of properties that are beneficial in some way to humans. With this view, the present study deals with the effect of apigenin against the genotoxic doses of mitomycin C and cyclophosphamide using chromosomal aberrations, sister chromatid exchanges and cell cycle kinetics as a parameters. The treatment of apigenin results in a significant, dose dependent decrease in the genotoxic damage, induced by mitomycin C and cyclophosphamide. It is concluded that the apigenin is potent in reducing the genotoxic damage, induced by anti-cancerous drugs, thereby reducing the chances of developing secondary tumors during the therapy.

Protective effects of total saponins from stem and leaf of Panax ginseng against cyclophosphamide-induced genotoxicity and apoptosis in mouse bone marrow cells and peripheral lymphocyte cells.

BACKGROUND: Cyclophosphamide (CP), commonly used anti-cancer, induces oxidative stress and is cytotoxic to normal cells. It is very important to choice the protective agent combined CP to reduce the side effects in cancer treatment. Ginsenosides are biological active constituents of Panax ginseng C.A. Meyer that acts as the tonic agent for the cancer patients to reduce the side effects in the clinic application. Because CP is a pro-oxidant agent and induces oxidative stress by the generation of free radicals to decrease the activities of anti-oxidant enzymes, the protective effects of the total saponins from stem and leaf of P. ginseng C.A. Meyer (TSPG) act as an anti-oxidant agent against the decreased anti-oxidant enzymes, the genotoxicity and apoptosis induced by CP was carried out. METHODS: The alkaline single cell gel electrophoresis was employed to detect DNA damage; flow cytometry assay and AO/EB staining assay were employed to measure cell apoptosis; the enzymatic anti-oxidants (T-SOD, CAT and GPx) and non-enzymatic anti-oxidant (GSH) were measured by the various colorimetric methods. RESULTS: CP induced the significant DNA damage in mouse peripheral lymphocytes in time- and dose-dependent manners, inhibited the activities of T-SOD, GPx and CAT, and decreased the contents of GSH in mouse blood, triggered bone marrow cell apoptosis at 6 and 12h. TSPG significantly reduced CP-induced DNA damages in bone marrow cells and peripheral lymphocyte cells, antagonized CP-induced reduction of T-SOD, GPx, CAT activities and the GSH contents, decreased the bone marrow cell apoptosis induced by CP. CONCLUSIONS: TSPG, significantly reduced the genotoxicity of CP in bone marrow cells and peripheral lymphocyte cells, and decreased the apoptotic cell number induced by CP in bone marrow cells. The effects of TSPG on T-SOD, GPx, CAT activities and GSH contents might partially contribute to its protective effects on CP-induced cell toxicities.

Protective effects of 4-nerolidylcatechol against genotoxicity induced by cyclophosphamide.

In the present work we evaluated both the mutagenicity and antimutagenicity of the Pothomorphe umbellata root extract (PUE) and its isolated active principle, the 4-nerolidylcatechol (4-NC), in bone marrow cells of mice using the micronucleus test. Swiss male mice were orally treated for 4 days with PUE (200, 100 or 50mg/kg/day) or 4-NC (50, 25 or 12.5mg/kg/day) prior to exposition with a single dose (200mg/kg) of cyclophosphamide (CP), 24h after the end of the treatment. The results demonstrated that the PUE and 4-NC did not have any mutagenic effect on mouse bone marrow cells; quite the opposite, there was a protective effect against genotoxicity induced by cyclophosphamide. Taken together, under the conditions tested herein, mice treated with PUE and 4-NC showed, in a dose-dependent manner, protective effect against CP-induced genotoxicity. Due to their ability to prevent chromosomal damage, with apparent low toxicity and cost, PUE or pure 4-NC are likely to open a field of interest concerning their possible use in clinical applications.

Amifostine and glutathione prevent ifosfamide- and acrolein-induced hemorrhagic cystitis.

INTRODUCTION: Ifosfamide (IFS) is an antineoplastic alkylating agent whose major side effect is hemorrhagic cystitis (HC). This toxicity is attributed to the renal excretion of acrolein (ACR), a highly urotoxic IFS metabolite. Despite the clinical use of mesna to prevent HC, a significant percent ( approximately 33%) of patients present with at last one feature of HC, mainly hematuria. AIM: To investigate the use of two antioxidants-amifostine and glutathione-for the prevention of experimental IFS- and ACR-induced HC. MATERIALS AND METHODS: Male Swiss mice were treated intraperitoneal (i.p.) with saline (control), glutathione (125, 250 or 500 mg/kg) or amifostine (25, 50 or 100 mg/kg), and 30 min later they received a single i.p. injection of IFS at a dose of 400 mg/kg. To investigate the systemic effects of the antioxidants on ACR-induced HC, the animals were treated with saline, amifostine (50 mg/kg, i.p.) or glutathione (500 mg/kg, i.p.), and 30 min afterward with 75 mug ACR intravesically (i.ve.). In another set of experiments, the antioxidants were injected directly into the bladder, where the mice received a single i.ve injection of ACR (75 mug) plus amifostine (1.5 mg/kg) or glutathione (2 mg/kg). HC was measured 3 h after IFS or ACR injection according to bladder wet weight, macroscopic (edema and hemorrhage) and microscopic changes, i.e., edema, hemorrhage, cellular infiltration, fibrin deposition and urothelial desquamation. RESULTS: Pretreatments with amifostine or glutathione prevented IFS-induced HC in a dose-dependent manner. Furthermore, ACR-induced HC was also prevented by systemic (i.p.) or local (i.ve.) pretreatment with glutathione or amifostine. The greatest protective effect was seen with local amifostine treatment (2 mg/kg i.ve.) (P < 0.05). CONCLUSIONS: Glutathione and amifostine show a beneficial effect in experimental IFS- and ACR-induced HC. Thus, they should be investigated as an alternative treatment to prevent HC observed in patients undergoing IFS treatment.

[Mechanisms of action of the stimulators of granulocytopoiesis under cytostatic myelosuppression conditions].

Mechanisms of action of pantogematogen (PG), granulocyte colony-stimulating factor (G-CSF), glycyram, and D-glucuronic asid (D-GA) have been investigated under the conditions of myelosuppression caused by the introduction of cyclophosphane. It is established that the activation of granulocytopoiesis by these preparations is based on various mechanisms: G-CSF directly stimulates the proliferation and differentiation of hemopoietic cells; PG enhances the proliferation of granulocytes due to activation of the regulatory systems; D-GA and glycyram normalize the structural and functional organization of a bone marrow, thus providing intensive maturing of the colony-forming units.

Dexamethasone protected human glioblastoma U87MG cells from temozolomide induced apoptosis by maintaining Bax:Bcl-2 ratio and preventing proteolytic activities.

BACKGROUND: Glioblastoma is the deadliest and most prevalent brain tumor. Dexamethasone (DXM) is a commonly used steroid for treating glioblastoma patients for alleviation of vasogenic edema and pain prior to treatment with chemotherapeutic drugs. Temozolomide (TMZ), an alkylating agent, has recently been introduced in clinical trials for treating glioblastoma. Here, we evaluated the modulatory effect of DXM on TMZ induced apoptosis in human glioblastoma U87MG cells. RESULTS: Freshly grown cells were treated with different doses of DXM or TMZ for 6 h followed by incubation in a drug-free medium for 48 h. Wright staining and ApopTag assay showed no apoptosis in cells treated with 40 microM DXM but considerable amounts of apoptosis in cells treated with 100 microM TMZ. Apoptosis in TMZ treated cells was associated with an increase in intracellular free [Ca2+], as determined by fura-2 assay. Western blot analyses showed alternations in the levels of Bax (pro-apoptotic) and Bcl-2 (anti-apoptotic) proteins resulting in increased Bax:Bcl-2 ratio in TMZ treated cells. Western blot analyses also detected overexpression of calpain and caspase-3, which cleaved 270 kD alpha-spectrin at specific sites for generation of 145 and 120 kD spectrin break down products (SBDPs), respectively. However, 1-h pretreatment of cells with 40 microM DXM dramatically decreased TMZ induced apoptosis, decreasing Bax:Bcl-2 ratio and SBDPs. CONCLUSION: Our results revealed an antagonistic effect of DXM on TMZ induced apoptosis in human glioblastoma U87MG cells, implying that treatment of glioblastoma patients with DXM prior to chemotherapy with TMZ might result in an undesirable clinical outcome.

Aqueous extract of walnut (Juglans regia L.) protects mice against cyclophosphamide-induced biochemical toxicity.

Walnut (Juglans regia L.) is extensively used in traditional systems of medicine for treatment of various ailments. It is described as an anticancer, tonic, blood purifier and detoxifier agent. The present study was undertaken to investigate modulatory effects of walnut extract on the toxicity of an anticancer drug, cyclophosphamide (CP) with special reference to protection against disruption of drug metabolizing and antioxidant enzymes. Plant extract+CP group animals showed restoration in the level of cytochrome P450 (CYP) content and in the activities of glutathione S-transferase (GST), glutathione peroxidase (GP) and catalase (CAT) in both liver and kidneys. But plant extract restored the activity of superoxide dismutase (SOD) and the level of reduced glutathione (GSH) in the kidneys only when compared with CP-treated animals. Plant extract treatment alone caused significant reduction in the content of CYP in the kidneys mainly. The extract showed a significant increase in the level of GSH and in the activities of GP in both the tissues and CAT in liver only, whereas no significant change was observed in the activities of GST and SOD. CP treatment resulted in a significant (P < 0.01) increase in the lipid peroxidation (LPO) in the liver and kidneys compared with controls, while the extract+CP treated group showed a significant decrease in the LPO in liver and kidneys when compared with the CP-treated group. The study shows that the use of J. regia extract might be helpful in abrogation of CP toxicity during the chemotherapy.

Inhibitory effect of chamomile essential oil on the sister chromatid exchanges induced by daunorubicin and methyl methanesulfonate in mouse bone marrow.

Different preparations of chamomile (Matricaria chamomilla) are used to treat various diseases, including inflammation and cancer; however, no studies on the plant's antigenotoxic capacity have been made. The aim of the present work was to determine the inhibitory effect of the chamomile essential oil (CO), on the sister chromatid exchanges (SCEs) produced by daunorubicin and methyl methanesulfonate (MMS) in mouse bone marrow cells. CO was analyzed and was found to contain 13 compounds, mainly bisabolol and its oxides, chamazulene, farnesene, germacrene and other sesquiterpenes. Initially, a toxic and a genotoxic analysis of CO were made; both showed negative results. To determine whether CO can inhibit the mutagenic effects induced by daunorubicin, one group of mice was administered corn oil, another group was treated with the mutagen (10 mg/kg), a third group was treated with 500 mg/kg of CO; three other groups were treated first with CO (5, 50 and 500 mg/kg) and then with 10 mg/kg of daunorubicin. In the case of MMS, the experimental groups consisted of the following: the negative control group which was administered corn oil, a group treated with 25 mg/kg of MMS, a group treated with 1000 mg/kg of CO, and three groups treated first with CO (250, 500 and 1000 mg/kg) and then with MMS (25 mg/kg). The results indicated a dose-dependent inhibitory effect on the SCEs formed by both mutagens. In the case of daunorubicin, a statistically significant result was observed in the three tested doses: from the lowest to the highest dose, the inhibitory values corresponded to 25.7, 63.1 and 75.5%. No alterations were found with respect to the cellular proliferation kinetics, but a reduction in the mitotic index was detected. As regards MMS, the inhibitory values were 24.8, 45.8 and 60.6%; no alterations were found in either the cellular proliferation kinetics or in the mitotic indices. Our results suggest that CO may be an effective antimutagen that could be considered for further study.

The epidermal growth factor receptor pathway mediates resistance to sequential administration of radiation and chemotherapy in primary human glioblastoma cells in a RAS-dependent manner.

Resistance to conventional adjuvant therapies (i.e., chemotherapy and radiation) has been well documented in malignant gliomas. Unlike many other tumor types, combined modality therapy involving radiation and chemotherapy has failed to appreciably enhance outcome for glioblastoma patients compared with radiation alone. In vitro, we have observed an actual antagonistic effect between sequential administration of radiation and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) chemotherapy in three primary human glioblastoma cell lines (referred as the GBME3-5 cell lines), which also happen to demonstrate strong expression of the epidermal growth factor receptor (EGFR). Upon inhibition of EGFR with the EGFR tyrosine kinase inhibitor, AG1478, it was found that this cross-resistance between sequential administration of radiation and BCNU was abrogated. To dissect which of these pathways may be responsible for the observed antagonism, known EGFR-regulated downstream signaling pathways including RAS, phosphatidylinositol 3-kinase (PI3-K), mitogen-activated protein kinase (p44/p42), and protein kinase C were inactivated with both pharmacological inhibitors and transient transfection experiments with dominant-negative and constitutively active constructs in the presence of exogenous EGF stimulation. It was found that BCNU inhibited radiation-induced apoptosis through EGFR-mediated activation of PI3-K/AKT via RAS. On the other hand, radiation was found to inhibit BCNU-induced apoptosis through EGFR-mediated activation of both PI3-K and mitogen-activated protein kinase (p44/p42) pathways, also via RAS. Inhibition of either EGFR or RAS activity appears to not only abrogate the observed antagonism between sequentially administered radiation and chemotherapy but actually results in a greater enhancement of apoptosis in the setting of combined modality therapy than when administered with either radiation or chemotherapy as single agents. Therefore, these findings suggest that strategies to inactivate EGFR or RAS signaling may be critical to improving not only the efficacy of single-agent therapy but also of combined modality therapy in gliomas.

Dietary curcumin inhibits chemotherapy-induced apoptosis in models of human breast cancer.

Curcumin, the major component of the spice turmeric, is used as a coloring and flavoring additive in many foods and has attracted interest because of its anti-inflammatory and chemopreventive activities. However, this agent also inhibits the generation of reactive oxygen species (ROS) and the c-Jun NH(2)-terminal kinase (JNK) pathway, and because many chemotherapeutic drugs generate ROS and activate JNK in the course of inducing apoptosis, we considered the possibility that curcumin might antagonize their antitumor efficacy. Studies in tissue culture revealed that curcumin inhibited camptothecin-, mechlorethamine-, and doxorubicin-induced apoptosis of MCF-7, MDA-MB-231, and BT-474 human breast cancer cells by up to 70%. Inhibition of programmed cell death was time and concentration dependent, but occurred after relatively brief 3-h exposures, or at curcumin concentrations of 1 microM that have been documented in Phase I chemoprevention trials. Under these conditions, curcumin exhibited antioxidant properties and inhibited both JNK activation and mitochondrial release of cytochrome c in a concentration-dependent manner. Using an in vivo model of human breast cancer, dietary supplementation with curcumin was found to significantly inhibit cyclophosphamide-induced tumor regression. Such dietary supplementation was accompanied by a decrease in the activation of apoptosis by cyclophosphamide, as well as decreased JNK activation. These findings support the hypothesis that dietary curcumin can inhibit chemotherapy-induced apoptosis through inhibition of ROS generation and blockade of JNK function, and suggest that additional studies are needed to determine whether breast cancer patients undergoing chemotherapy should avoid curcumin supplementation, and possibly even limit their exposure to curcumin-containing foods.