| Pancreatic cancer is one of malignant tumors with the highest mortality. The lethality of the pancreatic cancer is largely due to the chemotherapy drug resistance, that is closely related with the changes of the pancreatic cancer cell death signaling pathways. It is generally believed that the mechanism of tumor cells' resistance to chemotherapy is its resistance to apoptosis. Mechanisms of apoptosis resistance has always been the hot topic of research. However, more and more evidence proved that the ways of tumor cell death caused by chemotheropy are diversified. Deeper understanding of the forms tumor cell death induced by chemotherapy drugs and its changes of the signaling pathways are very important for overcoming chemoresistance, and they plays a great role in finding effective drug targets.Necroptosis or programmed necrosis is a newly founded programmed cell death in recent years, just like apoptosis, is a kind of cell death strictly regulated. Generally, when apoptosis signaling pathways is blocked or caspase activity is in restrained conditions, and RIP3 is highly expressed, necroptosis would happened, which makes necroptosis has the potential to overcome cancer chemotherapy drug resistance, and makes necroptosis a hotspot for chemoresistance. However, we still don't understand whether necroptosis could happen in tumor cell death induced by traditional chemotherapy drugs and the roles it plays in chemoresistance, and what are these key factors functions in these pathways. In this study, we will explore these problems preliminarily.In our study, we analyzed 168 cases of pancreatic cancer patient samples, and found RIP3 expression level significantly associated with pancreatic cancer patients' overall survival time, and we figured out, for the first time, that RIP3 high expression is a risk factor for pancreatic cancer patients' dead.In order to investigate the way RIP3 expression affects pancreatic cancer patient survival, we studied pancreatic cancer cell death resistance in vitro. At first, we found that necroptosis could occur to pancreatic cancer cell line CFPAC-1, and gemcitabine could induce necroptosis with or without pan-caspase inhibitor Z-VAD-fmk. Then it takes a year to get the gemcitabine resistant cell line R1 and R2 whose IC50 is 200 times higher than CFPAC-1. After comparison of CFPAC-1 and R1, R2, we found that the resistance cell line CFPAC-1(R) finally got the ability of resistance to both apoptosis and necroptosis. And it's the first time we prove that cell could resist to necroptosis induced by chemotheropy. Secondly, we found that RIP3, CD147, p-Drp1 is high expressed in chemoresist cell lines, and RIP3 has double agent identities in the regulation of cell death. siRNA of RIP3 plays different roles in CFPAC-1 and R1 cell. Knock down the expression of RIP3 could promote cells' sensitivity to gemcitabine in R1, but could not in CFPAC-1. In addition, the interference of CD147 or CD147 monoclonal antibody Hab18/6H8 could reverse CFPAC-1(R) gemcitabine resistance. We also found that Dephosphorylation of Drp-1 in S637 and mitochondria fission are closely related to cell death induced by Gemcitabine and pancreatic cancer cell drug resistance. Finally, we discovered that CD147 could inhibite Drp1 S637 dephosphorylation,Drp1 dimeration and mitochondria fission in order to inhibite cell death induced by Gemcitabine. RIP3 could participate in pancreatic cell death resistance through regulating CD147 and its downstream signaling molecules, such as Bcl- 2, Drp-1, NF- k B. |
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