The Functions Of PTPRB In The Metastasis Of Colorectal Cancer And Its Potential Mechanism

Part ? The functions of PTPRB in the progression of Colorectal Cancer and its potential mechanism Objective: Colorectal cancer(CRC)is one of the most common digestive tract malignancies,the incidence rate and mortality rate are third and second respectively in all tumors.Metastasis and recurrence are believed to be responsible for limiting long-term survival of patients with CRC.Protein tyrosine phosphatase,receptor type B(PTPRB)belongs to the protein tyrosine phosphatase family,and dysregulation of PTPRB function and expression has been shown to correlate with carcinogenesis and tumor progression in multiple cancer types.However,its role in colorectal cancer metastasis remains unclear.In this research,we explored its biological function and potential mechanismin the metastasis of colorectal cancer.Method: Western blot and RT-PCR were used to analyze the expression of PPTRB in protein and transcription levels in colorectal cancer cell lines.The metastasis ability were tested by wound healing and transwell assay.Si RNA and overexpression plasmid were used to knock down or upregulate the expression of PTPRB.Immunofluorescence was used to observe the phenotype of colorectal cancer cells,RT-PCR and Western blot were used to detect the expression of EMT related proteins to explore the relationship between PTPRB and EMT.The animal model of tumor metastasis was established by tail vein injection of HCT116 transfected with control plasmid,PTPRB-sh RNA andPTPRB overexpression plasmid.The formation of tumor metastasis was observed in each group and the expression of PTPRB and EMT related proteins were detected by Western blot.Result: High expression of PTPRB in colorectal cancer cells was positively correlated with the invasion and metastasis ability.The invasiveness was decreased after down-regulation of PTPRB,while upregulated PTPRB can increase the invasion ability.In LOVO with high PTPRB expression,expression of vimentin was high and E-cadherin was low,while HT29 with low PTPRB expression was in the opposite.After upregulation of PTPRB,the expression of vimentin was increased in colorectal cancer cells.There was a positive correlation between PTPRB and Twist1 expression.After knocking out Twist1,upregulation of PTPRB could not enhance cell invasion and migration.In vivo experiment,compared to control group and PTPRB sh RNA group,the number of metastatic tumors in PTPRB overexpression plasmid group was higher.Also,the expression of Vimentin was higher in PTPRB overexpression plasmid group.Conclusion: Our results revealed that overexpression of PTPRB can increase the expression of transcription factor Twist,increase expression of vimentin and decrease the expression of E-cadherin,and promote EMT to promote Colorectal cancer metastasis.Part ? The role of PTPRB in the prognosis of patients with colorectal carcinoma Objective: Metastasis is one of the most important risk factors responsible for the prognosis of patients diagnosed with colorectal carcinoma(CRC).In the first part of our study,the gene PTPRB was found to significantly induce the epithelial-mesenchymal transition of CRC cells,which further promoted their distant metastasis.Therefore,in this part of our research,we aimed to rule out the expression patterns of PTPRB in human CRC samples and their paired adjacent normal tissues,and to shed light on the relationship between PTPRB levels and the prognosis of CRC patients.Methods: Four hundred fifity-five human CRC samples and their paired adjacent(275)normal tissues were collected and constructed into tissue microarrays,and then PTPRBexpression was detected and compared between cancerous and non-cancerous tissues using immunohistochemical staining.According to the expression profile of PTPRB,the patients were grouped into “weak expression” and “strong expression”,after which the correlations between PTPRB and risk factors including age,gender and TNM staging and so on were evaluated.Thereafter,patients were followed up,and survival curve was calculated to finally elucidate the role of PTPRB in the prognosis of CRC patients.Result: The intensities of PTPRB staining in CRC tissues had no significant correlations with patients' age,gender,tumor pathological grading,or TNM staging,despite their over-expressions in cancerous tissues compared with adjacent normal tissues.What's more,there were no significant differences between weak expression group and strong expression group in the long-time survival.Conclusion: Although PTPRB was strongly expressed in CRC tissues,no evidence was found for the role of PTPRB in the prognosis of CRC patients.