title: 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.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Aarif
authors.initials: A
authors.lastname: Ahsan
authors.forename: Susan M
authors.initials: SM
authors.lastname: Hiniker
authors.forename: Susmita G
authors.initials: SG
authors.lastname: Ramanand
authors.forename: Shyam
authors.initials: S
authors.lastname: Nyati
authors.forename: Ashok
authors.initials: A
authors.lastname: Hegde
authors.forename: Abigail
authors.initials: A
authors.lastname: Helman
authors.forename: Radhika
authors.initials: R
authors.lastname: Menawat
authors.forename: Mahaveer S
authors.initials: MS
authors.lastname: Bhojani
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Nyati
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D016466:CHO Cells; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D004357:Drug Synergism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D050721:Proto-Oncogene Proteins c-cbl / Q000096:biosynthesis; D011799:Quinazolines / Q000494:pharmacology; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D011799:Quinazolines; D025801:Ubiquitin; D004815:Epidermal Growth Factor; D000069347:Erlotinib Hydrochloride; D050721:Proto-Oncogene Proteins c-cbl; D066246:ErbB Receptors; C067419:CBL protein, human; D002945:Cisplatin