Differences in effects of oncogenes on sensitivity to anticancer drugs

Arachidonic acid activates extrinsic apoptotic pathway to enhance tumoricidal action of bleomycin against IMR-32 cells

Bleomycin is a commonly used anti-cancer drug in the management of a variety of cancers. Previously, we showed that arachidonic acid (AA) augmented the growth inhibitory action of bleomycin on IMR-32 (human neuroblastoma cells) in vitro by enhancing oxidative stress. Despite these results, the exact molecular mechanism of cytotoxic action of bleomycin and its augmentation by AA is not known. Our current study revealed that a combination of bleomycin and AA significantly enhanced the expression of FAS gene, which is involved in programmed cell death (apoptosis) and caspases 3 and 8 compared to either bleomycin or AA alone implying that activation of extrinsic apoptotic pathway plays a major role in their (bleomycin + AA) tumoricidal action. It is interesting to note that AA by itself enhanced the expression of FAS and caspases 3 and 8 compared to control. Since caspases have a role in inflammation, cell proliferation, tumour suppression, cell differentiation, neural development and axon guidance and ageing, this may explain pleiotropic actions of AA and their metabolites.

Hematologic and Metabolic Effects of Dietary Supplementation with Agaricus sylvaticus Fungi on Rats Bearing Solid Walker 256 Tumor

Background: Many mushrooms have been used since ancient times for their nutritional and therapeutic properties. Alterations of hematologic parameters are commonly observed in patients with cancer, mainly due to the presence of some inflammatory mediators that have hemolytic effects, and yet can stimulate white blood cell release. Abnormalities in biochemical parameters are also found due to alterations in carbohydrate, protein, and lipid metabolism. Objective: The aim of the present study was to evaluate the effects of Agaricus sylvaticus on hematologic and biochemical parameters of rats inoculated with Walker 256 tumor. Methods: The animals were divided into 4 groups, with 20 in each group. Group 1 was inoculated with Walker 256 tumor and treated with A. sylvaticus. Group 2 was inoculated with Walker 256 tumor and administered a placebo solution. Group 3 was not inoculated with the tumor and was treated with A. sylvaticus, and Group 4 was not inoculated with the tumor and was administered a placebo solution. The rats were sacrificed after 12 days of treatment, and blood was collected following heart sectioning. Results: Statistically significant differences between Groups 1 and 2 were observed in red blood cell count, hematocrit, hemoglobin, C-reactive protein, urea, and triglyceride levels. No significant differences between these two groups were noted in hematimetric indices, leukocyte counts, creatinine, and glucose levels. No significant differences in hematologic and biochemical parameters were noted between Groups 3 and 4. Conclusion: A. sylvaticus is able to reduce anemia and improve biochemical parameters in animals with cancer and has no adverse effects on the blood cells of healthy animals.

Mechanisms of resistance to cisplatin and carboplatin

While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.