No abstract

Background and Objective: The cell division cycle 25 (CDC25)is a familyof highly conserved dual-specificity phosphatases that activate cyclin-dependent kinase complexes. These complexes are the main cell cycle regulators. Mammalian cells ,exposure to DNA damaging radiations such as ionizing radiation and ultraviolet light, prevent cell cycle progression by activation of checkpoint pathways and lead to cell death.Methods: In this study, mice were exposed to different doses of ionizing radiation. Their total cellular protein was extracted from the bone marrow. After determining and matching the protein concentrations, CDC25A phosphatase levels were measured by western blotting.Results: The results showed that exposure to different doses of ionizing radiation in vivo significantly increased the expression of CDC25A compared to control group (P <0.05).Conclusion: Exposure to ionizing radiation increases the expression of CDC25A phosphatase, which increases the possibility of tumorigenesis in that area by increasing bone marrow cell proliferation.

No abstract

Background: Breast cancer is one of the most prevalent types of cancer. Factors such as ionizing radiation and chemotherapeutic agents can trigger apoptosis and cancer cell death. An anticonvulsant drug named Valproic acid is a histone deacetylase inhibitor that shows promising anti-tumor effects in a variety of cancers. Telomerase is a ribonucleoprotein enzyme that activated in cancer cells and lead to telomeres shortening inhibition and triggering the apoptosis. Objectives: The purpose of this research was to investigate the simultaneously effect of Valproic acid and gamma radiation on telomerase activity and bax and Bcl-2 protein level in MCF-7 breast cancer cell line. Materials and Methods: MCF-7 cells was treated with different dose of Valproic acid (0, 2, 8 and 16 mM/l) and single dose of gamma radiation (4 Gy/min. (cell toxicity was determined using neutral uptake test. Telomerase activity was determined using TRAP assay (PCR-ELISA) method. Bax and Bcl-2 protein level was determined by ELISA method, as well. Results: Combination of Valproic acid and gamma radiation increased significantly cell toxicity in a time and dose dependent manner compared with control (P < 0.0001). The ratio of Bax/Bcl-2 was increased in a dose dependent manner at 48 and 72 hour treatment (P < 0.0001). There was a decrease in Telomerase activity after 24, 48 and 72 hours treatment in a dose dependent manner (P < 0.0001). Conclusions:The increasing cell toxicity, apoptosis-inducing effects and decreasing telomerase activity may play an important role in the Valproic acid and radiation mechanism. The current survey suggested that it is likely beneficial to combine Valproic acid and gamma radiation to treat breast cancer.