Study On The Association Of Sorcin And HSP27 Overexpression With Multidrug Resistance In Human Gastric Cancer

Background and Objective:Resistance to anticancer drugs is one of major problems preventing the effective chemotherapy of gastric cancer,but the molecular mechanisms of multidrug resistance(MDR) of gastric cancer is not completely clear.In order to find out new MDR-related proteins of human gastric cancer,in our previous study proteomics was performed to compare the difference of proteome in the vincristine-resistant human gastric cancer cell line SGC7901/VCR and its counterpart SGC7901.As a result,the 24 differentially expressed proteins were identified,of which Sorcin and HSP 27 were significantly upregulated in SGC7901/VCR compared with SGC7901.In this study, we further investigate the relationship between the overexpression of Sorcin and HSP 27 and MDR of human gastric cancer,clarify the role and mechanisms of HSP 27 and MDR in the development of MDR of human gastric cancer,and provide a basis for elucidating the mechanism of MDR development and finding the new target proteins of reversing MDR in human gastric cancer.Methods:(1) Sorcin siRNA and control siRNA were transfected into SGC7901/VCR cells,and pcDNA3.0/Sorcin and pcDNA3.0 were transfected into SGC7901 cells,respectively.Western blotting was used to detect the expression of Sorcin in the transfected cells.(2) MTT assay and flow cytometry were applied to determine the cell proliferation and apoptosis of the transfected cells after vincristine treatment to analyze the effect of Sorcin expression changes on the chemosensitivity of gastric cancer cells.(3) HSP27 antisense oligonucleotides(ASO) and control ASO were transfected into SGC7901/VCR cells,respectively.Western blotting and immunocytochemistry was used to detect the expression of HSP27 in the transfected cells,respectively.(4) MTT assay and Hochest33342 staining were applied to determine the cell proliferation and apoptosis of the transfected cells after vincristine treatment to analyze the effect of HSP27 downregulation on the chemosensitivity of gastric cancer cells.(5)Coimmunoprecipitation coupled with mass spectrometry were performed to identify the interacting proteins of HSP 27 in the SGC7901/VCR cells,and coimmunoprecipitation coupled with Western blotting were done to confirm the partial HSP-interacting proteins to investigate the mechanisms of HSP27 in the development of MDR of gastric cancer.Results:(1) The upregulation of sorcin expression by pcDNA3.0/Sorcin expression plasmid could decrease the vincristine chemosensitivity in the SGC7901,whereas the suppression of sorcin expression by sorcin siRNA could enhance the vincristine chemosensitivity in the SGC7901/VCR.(2) The suppression of HSP27 expression by HSP27 ASO could enhance vincristine chemosensitivity in SGC7901/VCR.(3) Twenty-five HSP27-interacting proteins were identified,which could be classified into eight categories based on their functions:cytoskeleton organization,chaperones,metabolic enzymes, proteins relative to signal transduction,ribosomal proteins,DNA repair proteins,proteins involved in transcription and translation,and RNA processing,the functions of which correspond to the reported functions of HSP27 with MDR.Conclusion:(1)the overexpression of Sorcin and HSP27 is related to MDR development in human gastric cancer cells,and the suppression of Sorcin and HSP27 overexpression could reverse the MDR of human gastric cancer cells.(2) HSP27 is involved in the MDR of human gastric cancer cells possibly through HSP27-interacting proteins.(3) The data provide a basis for elucidating the mechanism of MDR development and finding the new target proteins of reversing MDR in human gastric cancer.