Cyclin G2 Inhibits Growth And Metastasis Of Oral Squamous Cancer By Binding To IGFBP3

Objective: Oral squamous cell carcinoma(OSCC),as the sixth most common cancer in the world,is a malignant tumor that occurs in the lips or mouth.The incidence of oral squamous cell carcinoma is related to many factors,but its specific etiology and regulatory mechanism are not clear.Cell cycle protein G2(cyclin G2)is a cellular cycle negative regulatory protein that inhibits the process of cell cycle.Cyclin G2 is a potential cancer-suppressing gene whose expression is missing and may be associated with the development of tumors.Recently,the role of Cyclin G2 in tumors has attracted more and more attention,which inhibits the proliferation,differentiation and invasive metastasis of tumor cells.Cyclin G2 is abnormally expressed in oral squamous cell carcinoma,so it is speculated that cyclin G2 may be involved in the development of oral squamous cell carcinoma.This experiment first combined clinical data to analyze the relationship between cyclin G2 and oral squamous cell carcinoma,studied the effect of cyclin G2 on oral squamous cell on proliferation,migration and invasive metastasis at the cellular level,and study its molecular mechanism,and further verify the relationship between cyclin G2 and oral squamous cell carcinoma in nude mice.It provides a new theoretical basis for the diagnosis and treatment of oral squamous cell carcinoma.Methods: First,we analyzed the relationship between cyclin G2 and oral squamous cell carcinoma.We collected 80 cases oral squamous cell carcinoma tissue samples of patients after signing informed consents.The expression of cyclin G2 in oral squamous cell carcinoma tissue were detected by immunohistification.We collected clinical data of80 cases,including gender,age,tumor size,metastasis,clinical staging and so on.We combined with clinical factors and the expression of cyclin G2,and had statistical analysis.Second,we analyzed the effect of cyclin G2 on the growth and invasive metastasis of oral squamous cell carcinoma cells,and study the mechanism of action.We applied oral squamous cell carcinoma cells SCC-9 and Tca-8113 cells,and cyclin G2 was over-expressed through slow viral infection.The expression of CCNG2 m RNA and cyclin G2 protein were detected by Real time PCR and western blot to.The cell proliferation capacity was detected by CCK8 experiment.We used flow cytometer to detect cell cycle,and scratch experiment to detect cell migration ability,the cell invasion ability was detected by transwell experiment.We found the interaction protein of cyclin G2 insulin binding protein(IGFBP3)through Co-IP detection,and observated the co-location of cyclin G2 and IGFBP3 through immunofluorescent.The effect of cyclin G2 on the interaction between IGFBP3 and integrator was detected by Co-IP experiments,and the effect of cyclin G2 on FAK positioning was observed by immunofluorescent.The expression levels of the related proteins FAK,p-FAK,SRC,p-SRC,STAT3,p-STAT3,and downstream Bcl-2,c-Myc and MMP9 proteins in the integrator pathway were detected using western blot.Real time PCR was used to detect Bcl-2,c-Myc and MMP9 m RNA levels,and the secretion of MMP9 in cells was detected by ELISA detection.Third,we used oral squamous cell carcinoma cells to inject the tongue of the nude mice.We observed the growth of tumor and compared the size and weight of tumors at the tongue.We used HE staining to detected oral tumors and swollen lymph nodes,and observed the formation and metastasis of the tumors.The expression of the tumor marker Ki67 protein in the tumors of the mouth and lymph nodes were detected by immunohistization.The expression of cyclin G2,p-FAK,p-SRC and p-STAT3 in the bottom of the mouth were detected by immunehistification method.We verified the mechanism of cyclin G2 in the body.Results: First,the expression of cyclin G2 in oral squamous cell carcinoma was abnormality.The expression of cyclin G2 in oral squamous cell carcinoma tissue was decreased.The expression of cyclin G2 in oral squamous cell carcinoma tissue was significantly associated with lymph node metastasis and clinical staging.The expression of cyclin G2 is negatively correlated with clinical staging.Age,sex and tumor size were not associated with the expression of cyclin G2.Second,we explored the role of Cyclin G2 and mechanism of oral squamous cell carcinoma cells.Cyclin G2 inhibits the growth of oral squamous cell carcinoma cells,cell cycle process,migration and metastasis.Cyclin G2 and IGFBP3 have interaction,and the total positioning in the cytoplasm.Cyclin G2 affects the positioning of FAK within the cytoplasm,so that FAK no longer accumulates on the cell membrane.Cyclin G2 overexpression inhibits the interaction between IGFBP3 and the integrator.Cyclin G2 inhibits the phosphorylation of FAK,SRC and STAT3,which in turn inhibits the expression of bcl-2,c-myc and MMP9 m RNA and proteins,as well as the secretion of MMP9.Third,we injected oral squamous cell carcinoma cells in the bottom of the mouth of nude mice,and confirmed that cyclin G2 inhibited the growth and invasive metastasis of oral squamous cell carcinoma in vivo.The size and weight of oral tumor were reducted after cyclin G2 overexpression,we found the higher pathological classification level of cyclin G2 overexpression group by histological analysis,and Ki67 staining lower than the control group;The expression of p-FAK,p-SRC and p-STAT3 were decreased in cyclin G2 overexpression group by immunization results.Conclusion: Cyclin G2 was reduced in oral squamous cell carcinoma tissue and was negatively correlated with clinical staging.Cyclin G2 inhibited the growth of oral squamous cell carcinoma cells,cell cycle processes,migration and invasive metastasis.Its molecular mechanism is that cyclin G2 combined with IGFBP3 and inhibited the interaction between cyclin G2 and IGFBP3.Then the activation of the integrin was reduced,which inhibited the growth and metastasis of oral squamous cell carcinoma through the FAK-SRC-STAT3 pathway,and we verified in nude mice.