The Role Of DUSP18 In The Progression Of Hepatocellular Carcinoma And Clinical Correlation Research

Background & Aims Hepatocellular carcinoma is the sixth most common cancer and it is the third leading cause of cancer-related death,with high heterogeneity and poor prognosis.With the change of people’s living habits,the popularization of cancer screening and the improvement of diagnostic level,the incidence of liver cancer is on the rise.Most patients have developed been in advanced stage when tumor is detected.Hepatectomy is still the most effective treatment for early-stage liver cancer,but the 5-year recurrence rate is as high as 70%.For advanced liver cancer,transcatheter arterial chemoembolization and target therapy are still the first choice of treatment,with effective rates being as low as 52.5% and 40%respectively.Most patients will suffer from recurrence,metastasis or drug resistance within one year after treatment.Therefore,how to improve the effective rate of liver cancer treatment and reduce the occurrence of adverse events is an urgent problem to be solved.Various signaling pathways play a vital role in the occurrence and development of liver cancer,and the phosphorylation status of key molecules determines the activity of related pathways.Therefore,the protein kinase family and protein phosphatase family,which can change the phosphorylation state of proteins,play an important role in a variety of tumors including liver cancer.Protein phosphatases are divided into two families according to their substrates,including protein tyrosine phosphatases and protein serine/threonine phosphatases.Protein tyrosine Phosphatases can be further divided into classical protein tyrosine phosphatases and dual-Specificity phosphatases(DUSPs).While classical protein tyrosine phosphatases target at phosphorylated tyrosine,DUSPs catalyze the dephosphorylation of both phosphorylated tyrosine and serine/threonine.As an important member of phosphatase family,the role of DUSPs in cancer has been widely studied.Typical DUSPs such as DUSP1,DUSP4 and DUSP6 can affect the progression of various malignant tumors such as breast cancer and liver cancer by regulating the activity of MAPK pathway.Atypical DUSPs such as DUSP19 and DUSP26 have also been confirmed to be associated with the invasion and metastasis of pancreatic cancer.Dual-Specificity Phosphatase 18(DUSP18)is a kind of atypical DUSP,which is widely expressed in various tissues.Some studies have shown that DUSP18 can dephosphorylate JNK,and another study suggested that DUSP18 can promote the dephosphorylation of Tyr62 and Tyr63 residues of SHP2.Both JNK pathway and SHP2 play important roles in HCC,and DUSP18,as a potential upstream of them,is likely to affect the occurrence and development of HCC.However,there are few studies focusing on the biological role of DUSP18 in cancer.This study systematically analyzed the expression,function and mechanism of DUSP18 in liver cancer to help clarify the phosphatase network in hepatocellular carcinoma.Methods1.The expression of DUSP18 in liver cancer and adjacent tissues was analyzed by real-time quantitative PCR and immunohistochemical staining,and the expression of DUSP18 in tumorous and adjacent tissues was compared.2.Survival analysis was conducted by combining the immunohistochemical staining score of liver cancer tissues with clinical data to investigate the effect of DUSP18 on the prognosis of patients with liver cancer.3.The factors which can affect the expression of DUSP18 were analyzed by searching the public database and modifying epigenetic status of liver cancer cells.4.DUSP18-knockdown liver cancer cell lines and control cell lines were established by lentivirus.The effect of DUSP18 on liver cancer stem cells was analyzed by detecting the expression of cancer stem cell markers and performing spherosis assay.5.Using the above cell lines,the effects of DUSP18 on the proliferative ability of hepatocellular carcinoma cells were studied by CCK8 assay,Ed U assay,colony formation assay and cell cycle assay6.The above cell lines were treated with several kinds of targeted drugs and chemotherapy drugs.The effects of DUSP18 on drug resistance were evaluated by IC50 assay,Ed U assay,colony formation assay and cell apoptosis assay.7.The above cells were treated with small molecule inhibitors of MAPK pathway.The effects of DUSP18 on MAPK pathway were studied by proliferation-related assays.Results1.DUSP18 was decreased significantly in liver cancer tissues.2.The high expression of DUSP18 suggested a better prognosis for HCC patients;3.Epigenetic changes affected DUSP18 expression in HCC;4.Hepatocellular carcinoma cells with low DUSP18 expression showed stronger cancer stem cell characteristics.5.Hepatoma cells with low DUSP18 expression had higher proliferation ability;6.HCC cells with low DUSP18 expression showed stronger resistance to cisplatin.7.ERK1/2 and JNK pathways were affected by DUSP18 expression and might be potential downstream of DUSP18.Conclusion In this study,expression of DUSP18 was found to be significantly lowered in HCC patients and low expression of DUSP18 was associated with poor prognosis.In hepatoma cells,the change of epigenetic status could affect DUSP18 expression,which might be one of the mechanisms of the differential expression of DUSP18 between HCC and adjacent tissues.DUSP18 was found to be able to affect the stemness,proliferation and drug resistance of hepatocellular carcinoma cells,and could change the activation status of ERK1/2 and JNK in MAPK pathway.In conclusion,we systematically studied the expression and function of DUSP18 in liver cancer,providing a basis for further research.