Liver endothelium promotes HER3-mediated cell survival in KRAS wild-type and mutant colorectal cancer cells

Abstract We previously showed that human epidermal growth factor receptor 3 (HER3, also known as ERBB3) is a key mediator in liver endothelial cell (EC) promoting colorectal cancer (CRC) growth and chemoresistance, and suggested HER3-targeted therapy as a strategy for treating patients with metastatic CRC (mCRC) in the liver. Meanwhile, KRAS mutations occur in 40–50% of mCRC and render CRC resistant to therapies targeting the other HER family protein epidermal growth factor receptor (EGFR). It is necessary to elucidate the roles of KRAS mutation status in HER3-mediated cell survival and CRC response to HER3 inhibition. In the present study, we demonstrated that liver EC-secreted factors activated HER3 and promoted cell survival in KRAS wild-type and mutant CRC cells and tumors, and that blocking HER3 with an antibody, seribantumab, blocked EC-induced CRC survival. Our findings highlight a potential of utilizing HER3-targeted therapies for treating patients with mCRC regardless of KRAS mutation status.