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

// Twishasri DasGupta 1, * , Emeka I. Nweze 1, 8, * , Hong Yue 1 , Liming Wang 4 , Jessica Jin 5 , Santosh K. Ghosh 1 , Hameem I. Kawsar 1, 7 , Chad Zender 2 , Elliot J. Androphy 6 , Aaron Weinberg 1 , Thomas S. McCormick 3 , Ge Jin 1 1 Department of Biological Sciences, Case Western Reserve University School of Dental Medicine, Cleveland, OH, USA 2 Department of Otolaryngology-Head & Neck Surgery, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA 3 Department of Dermatology, University Hospitals Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA 4 Center for Molecular Cancer Diagnosis Inc., Twinsburg, OH, USA 5 Human Developmental and Regenerative Biology, Harvard University, Cambridge, MA, USA 6 Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA 7 Present Address: St. Luke’s Hospital, Chesterfield, MO, USA 8 Present Address: University of Nigeria, Nsukka, Nigera * These authors have contributed equally to this work Correspondence to: Ge Jin, e-mail: ge.jin@case.edu Keywords: human papillomavirus, human β-defensins, p53, head and neck cancer, microenvironment Received: November 11, 2015     Accepted: March 17, 2016     Published: March 28, 2016 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.