The Mechanism Of Inflammatory Cytokine Oncostatin M Suppresses Growth Of Liver Cancer Cells

Oncostatin M(OSM)belongs to the Interleukin-6 subfamily,which is mainly produced by immunity cells,including T lymphocytes,monocytes,macrophages.Initially discovered as a multiple functions cytokine released from U937 cells which has cytostatic activities on the growth of melanoma cells,hence its name oncostatin M.In different tumor microenvironment,IL-6 family cytokines play a different or opposite effect on cell proliferation.This effect is mainly by activating STAT3,MAPK and PI3 K signaling.Elevated OSM has been reported to be associated with liver disease,the results suggest the expression of OSM elevated is associated with the earliest stages of hyperplastic growth,but the mechanism remined unclear.By investigating the effects on growth of hepatoma cells and its molecular pathway,this study aims to provide a possible mechanism underling OSM affects tumor growth.Hepatocellular carcinoma is the most common malignant tumor in the word.for its early diagnosis rate is low,easy to transfer the characteristics of the clinical treatment effect is poorer,therefore,it is crucial to search for a new early diagnostic markers.Squamous cell carcinoma antigen1 has been proposed as a serological biomarker that,alone or in combination with ?-fetoprotein,may improve the sensitivity of HCC diagnosis.Serpin B3 belongs to the serine protease inhibitor(Serpin)family of proteins,which mainly expressed in squamous epithelial tissue.It has been reported that OSM can upregulated the expression of Serpin B3,which suggested that OSM inhibit the growth of hepatoma cells may be associated with Serpin B3.Therefore,based on Hep G2 and SMMC-7721 cell model,we treated two cell lines with different concentrations of OSM,to investigate the relationship between OSM and Serpin B3.Furthermore,we knowed down Serpin B3 gene to verify the hypothesis.ObjectiveBy investigating the effects on growth of hepatoma cells and its molecular pathway,this study aims to provide a possible mechanism underling OSM affects tumor growth.MethodsCell growth rates were analyzed after OSM treatment in human liver cancer cell line SMMC-7721 and Hep G2.According to the growth arrest and morphologic phenotype of cells,cellular senescence was detected by senescence-associated ?-galactosidase(SA-?-gal)staining.Cell cycle profile was examined by flow cytometric analysis.The expression of key regulators of cell proliferation including cyclin-dependent kinase inhibitors(p16,p21,p27)and c-Myc were analyzed at the level of m RNA and protein.Immunohistochemical determine Serpin B3 expression in liver cancer tissue.Based on Hep G2 and SMMC-7721 cell model,cell growth curve was assayed and cell cycle profile was examined after lentiviral infections carring Serpin B3.ResultsFirstly,OSM suppressed cell proliferation in a dose-dependent manner.Secondly,upon drug treatment,morphologic changes of cells implicated a senescent phenotype.Thirdly,which was further supported by the positive SA-?-gal staining.Forthly,OSM induced an increased proportion of cells at G0/G1 phase,and upregulated the expression of p21 and p27 at the level of m RNA and protein.Fifthly,oncogene c-Myc was also dramatically upregulated upon OSM treatment.Sixty,by immunohistochemistry,Serpin B3 expression was found mainly in the cell nucleus of liver cancer tissue.Seventy,the expression of Serpin B3 evelated at the level of m RNA and protein.Finally,after lentivirus transfecting low expression Serpin B3 gene human liver cancer cells,we analyzed the cell proliferation,After carrying Serpin B3 gene,the growth of liver cancer cells are no longer present inhibition,cell cycle analysis showed that OSM effect on cell block.Conclusions As a key regulator of cell proliferation and survival,c-Myc can be upregulated though OSM-activated STAT3 pathway.While in short-term,such hyperactive oncogene would induce cellular senescence as a barrier to transformation,in those cells with intact p53 machinery.These findings suggest the elevated OSM during the earliest stages of liver cancer might serve as a tumor suppressor.The expression of Serpin B3 elevated upon OSM treatment,which is the downstream gene of STAT3 signaling pathway.The result suggested that OSM inhibit the growth of liver cancer cell by upregulate Serpin B3 expression.