Role of Epidermal Growth Factor Receptor Degradation in Cisplatin-Induced Cytotoxicity in Head and Neck Cancer

Abstract

Cisplatin and its analogues are the most commonly used agents in the treatment of head and neck squamous cell carcinoma. In this study, we investigated a possible role of epidermal growth factor (EGF) receptor (EGFR) phosphorylation and degradation in cisplatin-induced cytotoxicity. Cisplatin treatment led to an increase in initial EGFR phosphorylation at Y1045, the binding site of ubiquitin ligase, Casitas B-lineage lymphoma (c-Cbl), followed by ubiquitination in the relatively cisplatin-sensitive cell lines. However, cisplatin-resistant cell lines underwent minimal EGFR phosphorylation at the Y1045 site and minimal ubiquitination. We found that EGFR degradation in response to cisplatin was highly correlated with cytotoxicity in seven head and neck cancer cell lines. Pretreatment with EGF enhanced cisplatin-induced EGFR degradation and cytotoxicity, whereas erlotinib pretreatment blocked EGFR phosphorylation, degradation, and cisplatin-induced cytotoxicity. Expression of a mutant Y1045F EGFR, which is relatively resistant to c-Cbl-mediated degradation, in Chinese hamster ovary cells and the UMSCC11B human head and neck cancer cell line protected EGFR from cisplatin-induced degradation and enhanced cell survival compared with wild-type (WT) EGFR. Transfection of WT c-Cbl enhanced EGFR degradation and cisplatin-induced cytotoxicity compared with control vector. These results show that cisplatin-induced EGFR phosphorylation and subsequent ubiquitination and degradation is an important determinant of cisplatin sensitivity. Our findings suggest that treatment with an EGFR inhibitor before cisplatin would be antagonistic, as EGFR inhibition would protect EGFR from cisplatin-mediated phosphorylation and subsequent ubiquitination and degradation, which may explain the negative results of several recent clinical trials. Furthermore, they suggest that EGFR degradation is worth exploring as an early biomarker of response and as a target to improve outcome.

Mechanisms for DNA‑damaging agent‑induced inactivation of ErbB2 and ErbB3 via the ERK and p38 signaling pathways

“…These agents induce the suppression of protein levels of ErbB2 and ErbB3 through the ERK and p38 MAPK signaling pathways, suggesting a novel non-canonical mechanism of ErbB downregulation. Ahsan et al (28) previously reported that EGFR degradation serves a role in cisplatin-induced cytotoxicity in head and neck cancer. Preliminary results using a Phos-tag have demonstrated that CDDP induces phosphorylation of ErbB members at multiple non-canonical residues (Park, unpublished); therefore, the identification of novel serine/threonine sites that regulate the degradation of ErbB receptors is essential for understanding the underlying molecular mechanisms of chemotherapy-induced inactivation of these receptors.…”

Effect of erlotinib on epidermal growth factor receptor and downstream signaling in oral cavity squamous cell carcinoma

“…For instance, knockdown of EGFR with small interfering ribonucleic acid (siRNA) can induce autophagic cell death independent of receptor tyrosine kinase activity (27). We have also found that EGFR degradation is an important mechanism that regulates chemotherapy-induced cytotoxicity (24, 26). These findings suggest that EGFR receptor degradation may be more effective in producing cytotoxicity of EGFR driven tumors than inhibition of EGFR activity alone.…”

Destabilization of the Epidermal Growth Factor Receptor (EGFR) by a Peptide That Inhibits EGFR Binding to Heat Shock Protein 90 and Receptor Dimerization

“…We and others have found that EGFR degradation increases tumor cell-specific cytotoxicity of chemotherapy and radiotherapy beyond that of EGFR inhibition alone (25)(26)(27). These studies suggest that not just inhibition of EGFR tyrosine kinase activity but down-regulation of EGFR is an important target in cancer therapy (28,29).…”