Potential of radiosensitizing agents in cancer chemo-radiotherapy.

Potential of herbs and other plant-based formulations have been increasingly recognized in prevention and treatment of human diseases including cancer. There exist enormous prospect for screening and evaluation of herbal/plant products for developing effective radiosensitization and radioprotection relevant to nuclear research program. Investigations in our laboratory have focused on the mechanism of activity of variety of anticancer and antioxidant agents, namely, Eugenol, (EU), Ellagic acid (EA), Triphala (TPL), Tocopherol Succinate (TOS) and Arachidonic acid on normal and cancer cells with view to design effective protocols in practical radioprotection and cancer radiotherapy. This paper is mainly focused on studies on cytotoxic effects on cancer cell lines. Results have shown that these agents produced radiosensitizing action involving oxidative damage, membrane alteration and damage to nucleic acid in various human cell lines. Studies were performed employing fluorescence probes and electron spin resonance methods and gel electrophoresis protocols. It has been found that cytotoxic effect was induced by initiating membrane oxidative damage and by triggering intracellular generation of reactive oxygen species (ROS) by gamma radiation in combination with phytochemicals like TPL, EA and TOS in tumor cell line Ehrlich Ascites (EAC), Human cervical (HeLa) and breast (MCF-7) cells. Membrane damage and ROS generation was measured by DPH and DCF-FDA fluorescent probes respectively after exposure to low to moderate doses of gamma radiation. This talk will present the cytotoxic effects of phytochemicals in combination with ionizing radiation. It is emphasized that modulation of membrane peroxidative damage and intra cellular ROS may help achieve efficient killing of cancer cells which may provide a new approach to developing effective treatment of cancer.

Programmed cell death as a prognostic indicator for radiation therapy in cervical carcinoma patients: a pilot study.

PURPOSE: In clinical practice, radiation therapy often fails in cervical carcinoma stage IIIB and there is a need to develop a predictive assay for prognosis of radiation treatment outcome in cancer patient. We have attempted to evaluate the relevance of changes in Membrane Fluidity (MF) and associated apoptotic cell death in cervical cancer cells after first fractionated dose of radiation therapy to treatment outcome of stage IIIB cervical carcinoma patients. MATERIALS AND METHODS: Biopsies of 15 patients with histologically proven cervix cancer were collected from the patients before and 24 h after first fractionated radiation dose of 2 grays (Gy). Cell suspension made in Dulbecco's Modified Eagle's Medium (DMEM) were used for further investigations and cell suspension of cervix cancer patient were used to measure MF by fluorescence polarization method and apoptotic index (AI) was determined by Tdt dUTP Nucleotide End Labeling (TUNEL) assay. RESULTS: A substantial increase in MF and AI was observed in cervical cancer cells irradiated ex vivo . A significant correlation ( P P > 0.1) was detected between changes in MF and treatment outcome of patients. CONCLUSION: Preliminary results showed significant change in MF and a marked increase in percentage apoptosis of cervix cancer cells irradiated ex vivo . The changes in AI after first fractionated dose of radiotherapy in cervical carcinoma patients may provide a predictor of prognosis for radiotherapy in uterine cervical carcinoma patients.