| Background and Objective Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors in gastrointestinal tract, which has the characteristics of rapid progression and poor prognosis. The mechanism of initiation and progression of PDAC still remains unclear. In previous work we found Prohibitin might be the candidate immunogenic membrane antigens of pancreatic cancer. The prohibitin (PHB) is a highly conserved protein in eukaryotic cells that are present in multiple cellular compartments. In addition to their role as chaperone proteins and can modulate transcriptional activity, processes of cell cycle regulation, cell signaling mediation, aging, apoptosis, proliferation, tumor suppression and so on. In addition PHB is present in many kinds of tumors and circulative blood, suggesting that PHB is involved in the initiation and development of cancer. This research aims to investigate the relationships between PHB and the biological behaviour of pancreatic cancer and chemoresistance, and to evaluate the level of PHB in blood serum of the pancreatic cancer patient. Moreover to explore correlations between PHB expression and patients' clinicopathological factors and prognosis in PDAC.Materials and Methods The expression of Prohibitin in nine pancreatic cancer cell lines were tested by real-time PCR and Western blot. Two human PDAC cell lines as AsPC-1and MIAPaCa-2were employed for in vitro experiments. The ability of cellular proliferation, migration, invasion and chemosensitivity changes were evaluated after applying small interfering RNA transfection as down-regulators the expression of prohibitin gene. Finally, changes of apoptosis rate, caspase-3activity and relative protein expression in apoptosis pathway were observed in gemcitabine treatment combined with reducing prohibtin compared with gemcitabine treatment alone. Moreover, expression of Prohibitin protein was tested by ELISA Kit in blood sera of31pancreatic cancer patients and31healthy volunteers, and expression of Prohibitin protein was examined by immunohistochemistry in66surgically resected specimens of PDAC and adjacent tissues. The relationships between Prohibitin expression and clinicopathological and prognostic variables of patients were further evaluated.Results All of the nine pancreatic cancer lines are expressions of Prohibitin mRNA and protein. Reducing prohibitin by Prohibitin siRNA induced depressed the ability of cellular proliferation, migration, invasion, and decreased chemosensitivity to gemcitabine and5-FU, which accompanied with lower apoptosis and caspase-3activity, decreased expression of PARP, Caspase-3, Cleaved Caspase-3, Caspase-9protein and overexpression of Bcl-2. The content of Prohibitn in blood serum of pancreatic cancer patient significant higher than healthy volunteer (P<0.001). Immunohistochemistry staining showed that the high expression rate of Prohibitin in tumor tissue was significantly higher than in normal tissue (P=0.009). There were correlations between Prohibitin expression and distant metastasis. Kaplan-Meier analysis showed high expression of Prohibitin had a significantly poorer prognosis. Multivariate Cox proportional hazards regression analysis confirmed that Prohibitin was an independent predictor for overall survival and disease-free survival.Conclusions Prohibitin related with the ability of cellular proliferation, migration, invasion, as a protooncogene. Prohibitin enhanced chemosensitivity by activating the apoptosis pathway through intrinsic stress pathway. Prohibitin expression predicts an unfavorable prognosis and may serve as a novel independent prognostic and diagnostic marker.
|
PDF Full Text Request