Mechanism of CCT2, a new downstream substrate of PDGFRα, on proliferation of tumor cells / 上海交通大学学报（医学版）

ABSTRACT

Objective: To study the molecular mechanism of chaperonin containing TCP1 subunit 2(CCT2), a new downstream substrate of platelet derived growth factor receptor α(PDGFRα), in tumorigenesis. Methods: Non-small cell lung cancer cell line H1703 was used. Western blotting was used to measure the phosphorylation of CCT2 upon PDGFRα inhibitor Gleevec treatment and PDGF stimulation. H1703 cells were divided into siCon group, siPDGFRα group and siCCT2 group; 48 h later, cell number counting was used to test the effect of CCT2 on cell growth after siRNA transfection. H1703 cells were divided into siCon group, siPDGFRα group, siAKT group and siCCT2 group; Western blotting was used to measure the protein level of PDGFRα and PARP. Cell fractionation was used to detect the cellular localization of CCT2 and co-immunoprecipitation was used to test the interaction between CCT2 and PDGFRα. Results: CCT2 phosphorylation was inhibited by Gleevec and induced by PDGF. Compared to the control group, the number of cells transfected by siCCT2 reduced by 30% (P=0.006). The protein level of PDGFRα was also decreased in siCCT2 transfected cells, whereas the cleavage of PARP was increased. CCT2 was localized in both cytoplasmic and membrane fractions and interacted with PDGFRα directly. Conclusion: CCT2 is a new downstream substrate of PDGFRα. CCT2 can promote tumor cells growth by interacting and stabilizing PDGFRα.