| Colorectal cancer(CRC)is one of the common malignant tumors of digestive tract,and its morbidity ranks fourth only after lung cancer,breast cancer and prostate cancer,and the mortality is second only to lung cancer.Hepatic and pulmonary metastasis after radical surgery and radiotherapy and chemotherapy in patients with colorectal cancer is an important cause of death.Therefore,to elucidate the molecular mechanism of colorectal cancer infiltration and metastasis,and to intervene and treat its progress,it has important scientific significance to improve the cure rate of malignant tumors and the survival rate of patients.In the previous study,our group found that Cdc42-interacting protein 4(CIP4)is up-regulated in colorectal cancer tissues and also is associated with poor prognosis in patients with colorectal cancer.CIP4 is one of the members of the F-BAR family that regulates actin-based cell motility and plays an important role in cell migration and invasion.It has been reported that CIP4 is involved in the development and metastasis of various tumors.However,the specific role of CIP4 in the development of colorectal cancer and related molecular regulation mechanisms have not yet been fully elucidated.Therefore,in order to explore the exact role and specific mechanism of CIP4 in the development of CRC,we are going to carry out the following study based on our previous findings,which including the effect of CIP4 on the progression of CRC,its role in the tumour biological behavior of CRC and signalling molecular mechanisms.Firstly,we found that the expression of CIP4 in the tissues samples of CRC patients was significantly up-regulated by western blot.Large sample size analysis of immnohistochemistry showed that CIP4 overexpression was associated with the infiltrating depth and differentiation degree of colorectal cancer patients.We also found that the expression of CIP4 in the tumor invasion front was higher than that in the central area of tumor.Then we constructed stable CRC cells with overexpression and knockdown of CIP4 and used various classical cell function experiments proved that the stable overexpression or knockdown of CIP4 could promote or inhibit the migration and invasion ability of CRC cells in vitro.As well as inhibiting liver metastasis of CRC in vivo when decreased expression of CIP4.We found that the stable overexpression of CIP4 can promote the formation of invadopodia and enhance the degradation of matrix in CRC cells by immunofluorescent confocal laser scanning.Secondly,CIP4 and Cdc42 protein expression levels positively related in consecutive paraffin-embedded slice of human CRC tissue were detected by IHC.Similarly,we also found that CIP4 and Cdc42 colocalized in CRC cells by immunofluorescence.Subsequently,we performed chromatin immunoprecipitation assay to confirmed that CIP4 can combined Cdc42 and regulated the expression of Cdc42.Finally,we found that CIP4 promoted the expression and activation of Cdc42 in colorectal cancer cells,and acceleated CRC progression via binding and arecruiting activated Cdc42 in the invadopodia by GTP-bound GTPase pull-down、GST-pull-down and immunofluorescence.The overexpression of CIP4 functionally promoted CRC cell migration,invasion,and metastasis by combining with Cdc42 and acceleating the formation of invadopodia.In summary,we demonstrated that CIP4 was up-regulated and had a close relationship with tumor invasion depth,differentiation degree and poor prognosis in CRC.CIP4 promoted invasion and metastasis of colorectal cancer cells both in vivo and in vitro by acceleating the formation of invadopodia and the degradation of matrix.We identified Cdc42,as an interactive protein of CIP4,participated in this process.Therefore,our study is the first to prove the molecular mechanism of CIP4 in the development and metastasis of colorectal cancer,and to explore the prevention and treatment strategies for colorectal cancer metastasis,so as to provide new ideas and breakthroughs for the clinical treatment of CRC patients. |
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