Biological And Mechanism Investigation On The Effects Of CDK12 Gene Co-amplification With ERBB2 On The Therapeutic Sensitivity Of Breast Cancer To Lapatinib

Objective:To investigate the biological effects as well as mechanisms of CKD12 and ERBB2 gene co-amplifying on the therapeutic resistance of breast cancer to anti-ERBB2 agents.Methods:We initiatively extracted the co-amplifying genes physically close to ERBB2 site in ERBB2-amplified breast cancers by combining cBioPortal and NCBI databases.The co-amplified genes were included as candidate genes for CRISPR/Cas9 library screening for synergetic targets of anti-ERBB2 therapy.High-throughput CRISPR library sequencing identified the gene targets significantly correlated with anti-ERBB2 therapy resistance.To further verify the biological effects of the target gene on anti-ERBB2 treatment,we knocked-out the target gene by CRISPR-Cas9 technique in two breast cancer cell lines with ERBB2 amplification,followed by series of molecular and biological assays.Transcriptional pathway enrichment was used to unveil the mechanism of target gene to mediate anti-ERBB2 therapy resistance.The synergetic expression and sensitizing activity of target gene were verified in human ERBB2-amplifying breast cancer cases.Results:There are a panel of genes that co-amplify with ERBB2 in part of breast cancers.We found that CDK12,which was frequently co-amplified with ERBB2,mediates the resistance of breast cancer cells to lapatinib treatment.CDK12 increases the resistance of breast cancer cells to anti-ERBB2 treatment through regulating PI3K/AKT pathway.CDK12 amplification marked a shorter survival of ERBB2-amplifying breast cancer patients receiving anti-ERBB2 treatment.The patients with a shorter survival from anti-ERBB2 treatment shared a higher level of CDK12 expression in their tumor tissues.Conclusion:CDK12 co-amplification exerts increased resistance to anti-ERBB2 therapies in ERBB2-amplifying breast cancers,which was manifested by biological assays in cell models and cancer samples as well as clinical data calculation.The evidence from this study rationalize the notion to treat breast cancers with ERBB2 and CDK12 co-amplification with combinational anti-ERBB2 and anti-CDK12 strategies.