The Growth Affection Comparison Among Inhibitors Which Antagonize Pro-survival Members Of Bcl-2Family

Cancer is a lethal disease which severely influence people’s life.8million peopledie of cancer every year in the world, nearly a quarter are Chinese. Breast cancer hasthe highest morbidity in women’s cancer. Therefore, much effort has been spent tn thestudy of breast cancer. Surgery，chemotherapy and radiotherapy remain to be themajor cure for breast cancer in clinical.But patients often suffer from relapse afterthese remedies. And relapse often accompanys with chemotherapy and radiotherapyresistance. New therapies for breast cancer are urgently needed. Targeted cancertherapies are drugs or other substances that block the growth and spread of cancer byinterfering with specific molecules involved in tumor progression and it hold greatpromise for cancer treatment. The development of targeted therapies, therefore, requiresthe identification of good targets—that is, targets that are known to play a key role incancer cell growth and survival.Anti-apoptotic members of Bcl-2family have beenwidely implicated in cancer. Elevated levels of Bcl-2have been identified in a numberof lymphoma types. Increased expression of the Bcl-2gene can be caused bychromosomal translocation, gene amplification, DNA hypomethylation, and loss ofregulatory microRNA expression. When levels of Bcl-2are high, pro-apoptoticproteins cannot form pores in the mitochondrial membrane. This allows cells toignore signals to undergo apoptosis, which may contribute to the formation andgrowth of tumors. Therefore we use small molecular inhibitors to antagonizepro-survival members of Bcl-2family in breast cancer cell lines and further analysethe potential efficacy of applying these inhibitors in clinical trials.Pro-survival members of Bcl-2family always have a high expression in breastcancer cell lines. There are three small molecular inhibitors which could antagonize pro-survival members of Bcl-2family: ABT-737, ABT-199and Tw-37. We use MTTassay to compare these inhibitors with traditional chemotherapeutic drugs in7breastcancer cell lines. ABT-737inhibits HBL-100， MDA-MB-468， MCF-7，MDA-MB-231，MDA-MB-435breast cancer cell lines in a dose dependent manner.ABT-199has a moderate effect on HBL-100， MDA-MB-468， MCF-7andMDA-MB-435. While Tw-37can inhibit MDA-MB-468and MDA-MB-435efficiently, it can also inhibit MCF-7and MDA-MB-435modestly.We conduct clone formation experiment in MDA-MB-231and MCF-7cell linesto evaluate the effect of Bcl-2inhibitors. The concentration of inhibitors are0.1μM，1μM and6μM. Consistent with MTT assay, Chemotherapeutic drugs conspicuouslyreduce the clone numbers.And ABT-737could inhibit the clone formation of thesetwo breast cancer cell lines. While ABT-199and Tw-37can’t affect clone formationeven in high concentration. The results indicate that pro-survival members of Bcl-2family coordinate the function of anti-apoptosis. If one member is inhibited, the othermembers could compensate this defect. ABT-737could inhibit Bcl-2, Bcl-xl, Bcl-w,but it can’t bind Mcl-1. This is the possible reason why ABT-737could inhibit breastcancer cell lines’ proliferation only in high concerntration.TUNEL assay demonstrate ABT-737could induce apoptosis in MDA-MB-231.Because ABT-737could bind to Bcl-2，Bcl-xl, Bcl-w and inhibit their function. WhenABT-737added into medium，cell would undergo apoptosis in two hours. However,ABT-199and Tw-37can’t induce apoptosis in MDA-MB-231and MCF-7.Drug combination assay manifests ABT-737could enhance efficacy ofdoxorubicin and paclitaxel in killing BT-549and T47D cell lines.Above all, these experiments indicate inhibitors antagonize pro-survival membersof Bcl-2family could impair tumor growth. Pro-survival members of Bcl-2familywould be crucial for breast cell lines’ survival. These Bcl-2family inhibitors arepotential candidate for targeted therapy.