Human papillomavirus oncogenic E6 protein regulates human β-defensin 3 (hBD3) expression via the tumor suppressor protein p53.

Twishasri Dasgupta,Elliot J Androphy,Chad Zender,Jessica Jin,Thomas S Mccormick,Liming Wang,Santosh K Ghosh,Ge Jin,Hong Yue,Aaron Weinberg,Emeka I Nweze,Hameem I Kawsar

doi:10.18632/oncotarget.8443

Abstract

Human β-defensin-3 (hBD3) is an epithelial cell-derived innate immune regulatory molecule overexpressed in oral dysplastic lesions and fosters a tumor-promoting microenvironment. Expression of hBD3 is induced by the epidermal growth factor receptor signaling pathway. Here we describe a novel pathway through which the high-risk human papillomavirus type-16 (HPV-16) oncoprotein E6 induces hBD3 expression in mucosal keratinocytes. Ablation of E6 by siRNA induces the tumor suppressor p53 and diminishes hBD3 in HPV-16 positive CaSki cervical cancer cells and UM-SCC-104 head and neck cancer cells. Malignant cells in HPV-16-associated oropharyngeal cancer overexpress hBD3. HPV-16 E6 induces hBD3 mRNA expression, peptide production and gene promoter activity in mucosal keratinocytes. Reduction of cellular levels of p53 stimulates hBD3 expression, while activation of p53 by doxorubicin inhibits its expression in primary oral keratinocytes and CaSki cells, suggesting that p53 represses hBD3 expression. A p53 binding site in the hBD3 gene promoter has been identified by using electrophoretic mobility shift assays and chromatin immunoprecipitation (ChIP). In addition, the p63 protein isoform ΔNp63α, but not TAp63, stimulated transactivation of the hBD3 gene and was co-expressed with hBD3 in head and neck cancer specimens. Therefore, high-risk HPV E6 oncoproteins may stimulate hBD3 expression in tumor cells to facilitate tumorigenesis of HPV-associated head and neck cancer.

Highlights

Human β-defensins are small cationic peptides originally identified from the plasma of patients with renal disease and from psoriatic skin lesions as innate antimicrobial molecules [1]
We have reported that proliferating oral mucosal basal layer cells as well as tumor cells in carcinoma in situ lesions and at the invasive www.impactjournals.com/oncotarget front of squamous cell carcinoma produce hBD3, which is encoded by the DEFB103A gene, with little-to-no expression of hBD-1 and -2 [2, 3]
Recent epidemiological and molecular studies have determined that Human papillomaviruses (HPV)-associated head and neck cancers are on the rise [7, 34,35,36]

Summary

Introduction

Human β-defensins (hBDs) are small cationic peptides originally identified from the plasma of patients with renal disease and from psoriatic skin lesions as innate antimicrobial molecules [1]. We have reported that proliferating oral mucosal basal layer cells as well as tumor cells in carcinoma in situ lesions and at the invasive www.impactjournals.com/oncotarget front of squamous cell carcinoma produce hBD3, which is encoded by the DEFB103A gene, with little-to-no expression of hBD-1 and -2 [2, 3]. Differentiated epithelial cells of oral epithelia only express hBD-1 and -2 [2, 3]. Tumor cell-derived hBD3 is associated with recruitment and activation of tumor-associated macrophages (TAMs) in the tumor microenvironment, contributing to tumor progression [2, 3]. We have reported that hBD3 expression is induced by activation of epidermal growth factor receptor (EGFR) [2]. The EGFR signaling pathway is critical for hBD3 gene expression in cells following microbial insults [4]. Cetuximab (Erbitux), a humanized monoclonal antibody against EGFR, blocks LPS-induced hBD3 expression, indicating the importance of EGFR in modulation of hBD3 gene expression [4]

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