Investigation of senescence effect in prostate cancer stem cell

Prostate cancer is the most common cancer in men and is the second most common cause of death related to cancer worldwide. Today, there are many studies to understand cancer and develop new treatment strategies. Despite all the studies on cancer in the world, there is still no effective treatment method. Despite all the studies that have been done on cancer before, we have not found out an efficient solution. Cancer stem cells, a cancer theory that has been approved recently and also called as tumor-initiating cells, are considered to be one of the reasons that lead to that dilemma. Cancer stem cells are responsible for the tumor onset, progression, conventional therapy resistance, recurrence, and metastasis. In this regard, understanding these cells is important to develop new and more effective treatment strategies. One of the major topics about the fight against these cancer cells, also called immortal cells, is cellular senescence. Senescence (cellular senescence), is the phenomenon of a stable arrest of the cell cycle and a common stress response that occurs in the abnormal environment of tumors. Also, senescence is a strong tumor-suppressing mechanism that limits the onset of cancer. Therefore, it is very important to clarify all aspects of the relationship between senescence and cancer. Besides, there is almost no article in the literature describing the relationship between senescence and cancer stem cells. There is a gap in the literature in terms of this area and it is thought that this study will make a significant contribution to the literature. In the context of this study, therapy-induced senescence is used i) to perform cellular senescence induction in prostate cancer stem cells, in prostate epithelial cells, prostate cancer cell line, and prostate cancer cells without stem cell characteristics and ii) to determine what the effects of senescence on proliferation, cell cycle, and apoptosis in prostate cancer stem cells are. For this purpose, isolation of prostate cancer stem cells was performed using fluorescence-activated cell sorting (FACS) method. Then using the principle of senescence induction therapy by using different doses of Doxorubicin, a chemotherapeutic agent; senescence has been triggered in both cancer stem cells and prostate epithelial cells and prostate cancer cells. To confirm induction; senescence-related β galactosidase staining (SA-β-gal) and Ki-67 senescence markers were used. The effects of senescence on cell viability, cell cycle and apoptosis were analyzed by using the Muse® Cell Analyzer. In addition to these assays, genes in apoptosis-related signaling pathways were analyzed by real-time PCR. With this study; the effects of senescence on proliferation, cell cycle, and apoptosis in prostate cancer stem cells have been demonstrated. Low Ki-67 level and positive SA-β-gal staining at pH 6 are determined in senescent cells after senescence induction in both cancer stem cells and other cell groups with DOX (10 nM, 25 nM and 50nM) administered at a subtoxic dose. Also, the cells showed morphological changes specific to senescence cells. After DOX-induced senescence, the cells were found to stop at the G2/M cell cycle checkpoint. With this study, many significant genes associated with apoptosis and senescence have been identified. All these data have shown that a therapeutic agent can be used in the induction of cancer stem cells. In addition; the cell cycle, apoptotic behavior and various senescence behaviors of prostate cancer stem cells with proliferation stopped are illuminated.