Mezenkimal Kök Hücre-Kanser Hücresi Ko-Kültürü Sonrası Tgf-Βeta ve Cxcl12 Sinyal Yolaklarındaki Değişimin Araştırılması

Abstract

Cancer is the second leading cause of death worldwide, following ischemic heart disease, among human diseases. During carcinogenesis, healthy cells exhibit similar protective characteristics to malignant cell types. Cancer develops as a result of intricate interactions between genetics/epigenetics and the tumor microenvironment. Breast cancer and glioblastoma are well-known as aggressive and prevalent types of cancer. Mesenchymal stem cells (MSCs) play a critical role in regenerative therapy and are considered a significant cell therapy candidate for cancer research. A variety of studies have been conducted on the interaction between MSCs and the tumor microenvironment, revealing a highly complex and variable relationship. This thesis focuses on the analysis of cell viability after co-culturing triple-negative breast cancer, glioblastoma cancer, and human bone marrow MSCs. Additionally, the study aims to investigate changes in the expression changes for the Transforming Growth Factor Beta (TGF-β) and Chemokine-dependent Ligand 12 (CXCL12) signaling pathways in both cancer cells and MSCs. The experimental setup consist of co-culturing human bone marrow-derived MSCs with cancer cells (T98G and MDA-MB-231) using transwell systems. Cell viability was analyzed at the 24th, 48th, and 72nd hours and the 4th, 7th, and 10th days after co-culture using the MTT method. Expression changes for the TGF-β signaling pathway, pTGFβRI, and pSMAD3 molecules were selected, while for the CXCL12 signaling pathway, pCXCR4 and pERK1/2 molecules were chosen. The expression of pTGFβRI was measured through immunofluorescence, while the expression of pCXCR4 was observed immunohistochemically. The ELISA method was used to analyze the expression of pSMAD3 and pERK1/2. The results showed that the viability of cancer cells decreased when compared with the control group after co-culture. After cancer cells/MSC co-culture, MSC cell viability was found to be decreased compared to control MSC cells. The expression of pTGFβRI in cancer cells and MSCs did not change significantly compared to the control groups. However, the intracellular signaling molecule pSMAD3 showed a more pronounced expression than in the control group. In the CXCL12 signaling pathway, the expression of pCXCR4 was observed to be weak to moderate in both cancer cells and MSCs. The expression of pCXCR4 in cancer cells and the activity of the intracellular molecule pERK1/2 increased. It was observed that increased pCXCR4 expression in MSCs did not affect intracellular pERK1/2 expression. This thesis study determined that MSCs can suppress the viability of cancer cells for both cancer types when co-cultured with MSCs. Additionally, the viability of MSCs was maintained after co-culture. The increase in the receptor activity of the TGF-β signaling pathway after co-culture indicates that the signaling pathway increases as a result of interaction with MSCs, but the decrease in pSMAD3 expression indicates that active molecules secreted from MSCs suppress this signaling pathway. Weak and to moderate levels of CXCL12 signaling pathway receptors activity resulted in increased expression of pERK1/2. This does not prevent cancer cell viability from being suppressed by MSCs. On the contrary, it is thought that CXCL signaling pathway activity contributes to the retention of MSCs in the cancerous region and suppression of cancer cell viability through bioactive molecules secreted from MSCs.