The Expression Of MACC1in Pancreatic Cancer And The Study Of Its Role In Proliferation, Migration And Chemoresistance Of Pancreatic Cancer

1. Background and objective:Pancreatic cancer is one of the most common aggressive malignant tumor. It starts hidden, early time diagnosis is difficult, pathological changes develop fast, the prognosis is poor and the mortality is relatively high. Owing to the environment and genetic factors, pancreatic cancer is thought to be caused by complicated multistage carcinogenesis. The majority of pancreatic cancer patients already have been diagnosed with a terminal condition by the time they present. The operative resection rate was only10%-20%, and the5-year survival rate was less than5%. The prognosis of pancreatic cancer is closely related to early diagnosis and effective therapeutic strategy. Therefore, identification the biomarkers for pancreatic cancer early detection has great significance for the diagnosis and therapy of pancreatic cancer. MACC1,a newly identified oncogene. is related with tumor metastasis and poor prognosis. Until recently, there has been no report about the expression of MACC1in pancreatic cancer. Therefore, we aim to investigate the expression of MACC1in pancreatic cancer and to explore the role of MACC1in the proliferation, migration and chemoresistance in pancreatic cancer. 2. Experimental methods:2.1With approved by the Ethical Committee of our hospital, we have collected109serum samples which included60patients with pancreatic cancer and49healthy controls between January2010and December2011. The serum levels of MACC1were measured by ELIS A. With a comprehensive study of clinical data, we make statistical analysis of the relationship between MACC1and pancreatic cancer.2.2We examined the expression of MACC1both at the mRNA level and at the protein level in five pancreatic cancer cell lines. And we examined the effects of the three MACC1siRNAs, and indentified the most effective siRNA uesd for the following experiments.2.3The effect of down-regulation of MACC1on the proliferation in pancreatic cancer cells was examined using MTT assay.2.4Based on transwell assay, we investigated the role of MACC1on the migration in pancreatic cancer, and measuered the change of the EMT-related proteins.2.5We explored the influence of silencing MACC1on chemoresistance by MTT assay and flow cytometry analysis. The change of anti-apoptosis related proteins were examined with western blot. We also evaluated the signalling pathway which MACC1may involved in.3. Results:3.1We first found that MACC1expression could be deceted in serum,especially in pancreatic cancer patients using a commercial ELIS A kit.The rate of positive MACC1expression in pancreatic cancer was63.3%(38/60), while in healthy subjects it was only4.1%(2/49). In pancreatic cancer patients, a high level of serum MACC1expression was positively correlated with lymph node metastasis, distant metastasis and later TNM stages.3.2MACC1was overexpressed in CFPAC-1cells, while in BXPC-3cells its expression was much weaker. In AsPC-1、PANC-1and MIA PaCa-2cells, it was difficult to detect its expression. In these three MACC1siRNAs, MACC1siRNA-2was the most effective one.3.3The results of MTT assay showed that down-regulation of MACC1significantly inhibited the proliferation of CFPAC-1cells.3.4Trans well assay indicated that silencing MACC1obviously decreased the migration of CFPAC-1cells and western blot analysis showed that the EMT-related protein E-cadherin was up-regulated.3.5Combined the results of flow cytometry analysis and MTT assay, we knowed that down-regulation of MACC1sensitized CFPAC-1cells to gemcitabine, and the related anti-apoptosis proteins, such as Bcl-2,Caspase-3and Caspase-9, were obviously decreased. In addition, the signalling proteins Ras and p-ERK1/2were decreased as well.4. Conclusions:4.1MACC1was highly expressed in the serum of pancreatic cancer paitents, and was correlated with lymph node metastasis, distant metastasis, and a later TNM stage.4.2Silencing MACC1could significantly inhibit the proliferation and migration of pancreatic cancer cells, and sensitize pancreatic cancer cells to gemcitabine treatment.4.3MACC1may play its role though regulating the Ras/ERK signaling pathway.