Theranostics 2019; 9(8):2235-2251. doi:10.7150/thno.30678
Sonic hedgehog pathway activation is associated with cetuximab resistance and EPHB3 receptor induction in colorectal cancer
1. Graduate School of Medicine, Korea University College of Medicine, Seoul, 152-703, Republic of Korea.
2. Department of Oncology, Korea University Guro Hospital, Seoul, Republic of Korea.
3. Department of Surgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, 152-703, Republic of Korea.
Park SH, Jo MJ, Kim BR, Jeong YA, Na YJ, Kim JL, Jeong S, Yun HK, Kim DY, Kim BG, Kang SH, Oh SC, Lee DH. Sonic hedgehog pathway activation is associated with cetuximab resistance and EPHB3 receptor induction in colorectal cancer. Theranostics 2019; 9(8):2235-2251. doi:10.7150/thno.30678. Available from http://www.thno.org/v09p2235.htm
A major problem of colorectal cancer (CRC) targeted therapies is relapse caused by drug resistance. In most cases of CRC, patients develop resistance to anticancer drugs. Cetuximab does not show many of the side effects of other anticancer drugs and improves the survival of patients with metastatic CRC. However, the molecular mechanism of cetuximab resistance is not fully understood.
Methods: EPHB3-mediated cetuximab resistance was confirmed by in vitro western blotting, colony-forming assays, WST-1 colorimetric assay, and in vivo xenograft models (n = 7 per group). RNA-seq analysis and receptor tyrosine kinase assays were performed to identify the cetuximab resistance mechanism of EPHB3. All statistical tests were two-sided.
Results: The expression of EFNB3, which upregulates the EPHB3 receptor, was shown to be increased via microarray analysis. When resistance to cetuximab was acquired, EPHB3 protein levels increased. Hedgehog signaling, cancer stemness, and epithelial-mesenchymal transition signaling proteins were also increased in the cetuximab-resistant human colon cancer cell line SW48R. Despite cells acquiring resistance to cetuximab, STAT3 was still responsive to EGF and cetuximab treatment. Moreover, inhibition of EPHB3 was associated with decreased STAT3 activity. Co-immunoprecipitation confirmed that EGFR and EPHB3 bind to each other and this binding increases upon resistance acquisition, suggesting that STAT3 is activated by the binding between EGFR and EPHB3. Protein levels of GLI-1, SOX2, and Vimentin, which are affected by STAT3, also increased. Similar results were obtained in samples from patients with CRC.
Conclusion: EPHB3 expression is associated with anticancer drug resistance.
Keywords: colorectal cancer, Cetuximab Resistance, EPHB3, GLI-1