Expression And Effect Of GDF11 In Pancreatic Cancer

BackgroundPancreatic cancer is a digestive system tumor with high degree of malignancy and poor prognosis,accounting for the sixth leading cause of cancer mortality rate in China.The incidence and mortality rates of pancreatic cancer show a sustained increase in the world,with the overall 5-year survival rate less than 8%.Surgical radical resection is currently the most effective treatment for pancreatic cancer,but most patients are at advanced stages of diagnosis and thus lost the opportunity for radical resection.Therefore,exploring the mechanism of occurrence and development of pancreatic cancer and finding prognosis-related factors are significantly important for the overall therapeutic effect of pancreatic cancer patients.The growth differentiation factor 11(GDF11 is a secreted protein in the transforming growth factor-?(TGF-?)superfamily and bone morphogenetic protein(BMP)subfamily.Regarding cancer,BMP acted as a series of factors that regulated cell proliferation,apoptosis and differentiation,and was also shown to be correlated with various cancers such as esophageal cancer,prostate cancer and breast cancer.However,to our knowledge,there is no information regarding GDF11 in pancreatic cancer and the biological function of GDF11 in cancer cells remain largely unknown.ObjectiveTo clarify the relationship between GDF 11 expression in pancreatic cancer tissues and cell lines and its relationship with clinicopathological parameters;to explore the biological function of high and low expression of GDF 11 on pancreatic cancer cells.Methods1.1)Twenty-eight pairs of surgically resected specimens and paired adjacent tissues of pancreatic cancer were collected.The expression of GDF 11 mRNA and protein in pancreatic cancer tissue and paracancerous tissues was detected by qPCR and Western-Blot;2)The expression of GDF11 mRNA and protein of a pancreatic normal cell line(HPDE6-C7)and five pancreatic cancer cell lines(ASPC-1,BXPC-3,CFPAC-1,PANC-1,SW1990)were examined by qPCR and Western-Blot;3)Immunohistochemical(IHC)method was used to detect the expression of GDF11 protein in a tissue microarray including 63 pairs of pancreatic cancer and paired adjacent tissues and 28 pairs of self-picking pancreatic cancer tissue and paracancerous tissues.The relationship between the expression level of GDF11 and clinicopathological parameters of pancreatic cancer was analyzed;4)The relationship between GDF11 expression and prognosis of pancreatic cancer patients was analyzed using Kaplan-Meier and Cox regression analysis.2.1)Overexpression and knockdown of GDF11 gene in pancreatic cancer cells were established by GDF11-overexpressing lentiviral vector and siRNA vector,and stable GDF11 overexpression and siRNA low expression of pancreatic cancer cells were screened.2)The effects of high and low expression of GDF 11 on proliferation of pancreatic cancer cells were detected by MTS assay and plate cloning experiments.3)The effect of high and low expression of GDF 11 on migration and invasion of pancreatic cancer cells was detected by Transwell migration and invasion assay.4)The effect of high and low expression of GDF 11 on apoptosis rates of pancreatic cancer cells was examined by flow cytometry.Results1.1)The mRNA and protein expression levels of GDF 11 in pancreatic cancer tissues were significantly lower than those in paired adjacent tissues(p<0.05).2)The mRNA and protein expression levels of GDF 11 in pancreatic cancer cell lines were significantly lower than those in normal pancreatic cell line(p<0.05).3)The results of immunohistochemistry showed that GDF 11 protein was mainly expressed in the cytoplasm of pancreatic cancer and paraneoplastic tissue,and the high expression rate of GDF11 in paracancerous tissues was significantly higher than that in cancer tissues(40.7%vs.71.4%,p<0.05);4)The difference of GDF11 protein expression was related to the neural invasion(p=0.019),T stage(p=0.010)and N stage(p=0.029)of pancreatic cancer;5)Cox regression analysis showed that high expression of GDF11(HR=0.496,p=0.040)was associated with better prognosis in pancreatic cancer.2.1)Compared with the control groups,the expression level of GDF11 in cells transfected with the GDF11 overexpression sequence was increased,and GDF11 expression was decreased in cells transfected with GDF11-siRNA;2)Compared with the corresponding negative control cells,the proliferation efficiency of PANC-1 cells with overexpressing GDF11 was lower,and the proliferation efficiency of CFPAC-1 cells with down-regulated GDF11 expression was higher;3)Compared with the corresponding negative control cells,PANC-1 cells with over-expressing GDF11 showed decreased migration and invasion ability,and CFPAC-1 cells with down-regulated GDF11 expression had increased migration and invasion ability;4)Compared with the corresponding negative control cells,the apoptosis rates of PANC-1 cells with over-expressing GDF11 was higher,while the apoptosis rates of CFPAC-1 cells with down-regulated GDF11 expression was lower.Conclusion1.The expression of GDF11 in pancreatic cancer tissues is lower than that in paracancerous tissues;the expression level in pancreatic cancer cell lines is lower than that in normal pancreatic cell lines;the high expression of GDF11 is related to the neural invasion,T stage,and N stage of pancreatic cancer.High expression of GDF11 is also associated with a better prognosis in pancreatic cancer patients;2.GDF11 inhibits the proliferation,migration and invasion of pancreatic cancer cells and promotes apoptosis of pancreatic cancer cells.