ADAM 17 Confers Resistance To Cetuximab In Human Colorectal Cancer Cells

Colorectal cancer(CRC)is the world's third common malignant tumor.Its incidence associated with environmental factors and genetic factors,such as increased genetic instability,methylation phenotype and mutations of KRAS,BRAF and other genes.In recent years,the incidence of CRC showed a rising trend,and most CRC patients have distant metastases before diagnosis.Although surgical resection of metastases can obtain certain prominent curative effect,but due to the number and size of liver metastases,the anatomic location and other reasons,only a small part of colorectal cancer patients with liver metastases could accept the surgical treatment.Therefore,the drugs treatment of metastatic colorectal cancer(mCRC)is particularly important.Although the chemotherapy including irinotecan,oxaliplatin and 5-fluorouracil for CRC can improve the efficacy,but the median survival of patients is still less than 2 years.In the 21st century,monoclonal antibodies have shown clinical benefit in the treatment of numerous cancers including m CRC,and epidermal growth factor receptor(EGFR)-targeted monoclonal antibodies(cetuximab and panitumumab).Cetuximab,a human-mouse chimeric IgG1 monoclonal antibody and panitumumab,a total human monoclonal antibody,both have a very high affinity to EGFR.As EGFR ligands including epidermal growth factor(EOF)can bind the extracellular domain of EGFR,induce receptor dimerization and activate downstream signaling pathways that are crucial for cell survival and proliferation,cetuximab could competitively prevent ligands binding to EGFR,thus blocking EGFR signaling.Thus,cetuximab may inhibit tumor cell survival,proliferation,invasion and metastasis.However,the prices of both cetuximab and panitumumab are quite expensive and these therapies have had only a modest impact on mCRC.Compared with the conventional chemotherapy,the efficacy of the combination therapy of EGFR-targeted monoclonal antibody and FOLFOX or FOLFIRI,the main chemotherapies to mCRC,only increased by 8%-16%.Based on these two aspects,enhance or improve the efficacy of anti-EGFR monoclonal antibody has become an urgent problem to be solved.A key reason for the limited success of cetuximab or panitumumab on mCRC is the severe primary(de novo)and secondary(acquired)resistance to EGFR-targeted therapies.Therefore,it warrants further investigations to further explore the resistance mechanisms of monoclonal antibodies and find out solutions to evaluate their effectiveness in mCRC patients.Objective:The main purpose of this study is to explore new molecular mechanisms that lead to colorectal cancer resistance to cetuximab,increase the effectiveness of cetuximab targeted therapies,and provide a theoretical basis for the personalized precise treatment of colorectal cancer.Methods:1)The expression of ADAM17 in colorectal cancer cells were confirmed by Western blot.High expression levels of the ADAM 17 were extracted.Using the expression of siRNA interference fragment selective cut ADAM17,adopt ADAM 17 expression plasmid DNA.The cytotoxic effect and apoptosis-inducing effect of cetuximab in vitro were evaluated via flow cytometry(Annexin V labeled),observed under the different levels of ADAM 17 expression.2)Express or interfere with the ADAM 17,adopt CCK8 experiment,Transwell migration,cell proliferation test to study the effects on cell proliferation and migration.3)The change of EGFR-AKT signal path with different expression of AD AM17 protein was detected through Western Blot.Results:1)ADAM 17 were differentially expressed in colorectal cancer cell line.The SW480 cells expressing is relatively high,and the RKO cells expressing is low.The cytotoxic effect and apoptosis-inducing effect of cetuximab in vitro were evaluated via flow cytometry(Annexin V labeled),in SW480-Si group,apoptosis cell percentage was increase;Expressed ADAM17 RKO cell group,the proportion of apoptosis cells decreased obviously.2)AD AM17 with Colorectal cancer cell proliferation and migration.Under the action of cetuximab,express ADAM 17 Colorectal cancer cell migration and proliferation ability was significantly improved.Interference ADAM 17 cell migration ability significantly reduced expression of Colorectal cancer cells.3)ADAM 17 able to abnormal activation of EGFR and regulating the AKT signaling pathway activation,regulation of Colorectal cancer cell proliferation shift in role.The further implementation of Colorectal targeting EGFR cetuximab drug resistance.Conclusion:1)ADAM 17 played an essential role in resulting in mCRC resistant to cetuximab.2)ADAM 17 promotes resistant to cetuximab probably via EGFR/AKT signaling pathway in colorectal cancer.