P21Cip1/WAF1 expression is strongly associated with HPV-positive tonsillar carcinoma and a favorable prognosis

Abstract

Human papillomavirus is involved in the carcinogenesis of tonsillar squamous cell carcinomas. Here, we investigated the expression and the prognostic value of key cell cycle proteins in the pRb and p53 pathways in both human papillomavirus type 16-positive and -negative tonsillar squamous cell carcinomas. Using immunohistochemistry, 77 tonsillar squamous cell carcinomas with known human papillomavirus type 16 status and clinical outcome were analyzed for expression of Ki67, p16 INK4A, cyclin D1, pRb, p14 ARF , MDM2, p53, p21 Cip1/WAF1 , and p27 KIP1 . Results were correlated with each other and with clinical and demographic patient data. A total of 35% of tonsillar carcinomas harbored integrated human papillomavirus type 16 DNA and p16 INK4A overexpression, both being considered essential features for human papillomavirus association. These tumors also showed the overexpression of p14 ARF (Po0.0001) and p21 Cip1/WAF1 (P ¼ 0.001), and downregulation of pRb (Po0.0001) and cyclin D1 (P ¼ 0.027) compared with the human papillomavirus-negative cases. Univariate Cox regression analyses revealed a favorable survival rate for non-smokers (P ¼ 0.006), as well as for patients with T1-2 tumors (Po0.0001) or tumors showing low expression of cyclin D1 (P ¼ 0.028), presence of human papillomavirus and overexpression of p16 INK4A (P ¼ 0.01), p14 ARF (P ¼ 0.02) or p21 Cip1/WAF1 (P ¼ 0.004). In multivariate regression analyses, smoking and tumor size, as well as expression of cyclin D1 and p21 Cip1/WAF1 , were found to be independent prognostic markers. We conclude that human papillomavirus positivity in tonsillar squamous cell carcinomas strongly correlates with p21 Cip1/WAF1 and p14 ARF overexpression and downregulation of pRb and cyclin D1. In particular p21 Cip1/WAF1 overexpression is an excellent favorable prognosticator in tonsillar squamous cell carcinomas. Modern Pathology ( Head-and-neck squamous cell carcinoma is the sixth most prevalent malignancy in the world, contributing 6% of new cancer cases annually worldwide. 1,2 These tumors have a 5-year survival rate of approximately 50%, which has not improved in the last two decades. 3 Well-recognized risk factors in the etiology of head-and-neck squamous cell carcinomas are extensive tobacco and alcohol consumption in B90% of cases, as well as oncogenic human papillomaviruses (HPVs), predominantly HPV type 16. 3,4 Interestingly, the association of HPV is strongest for tonsillar squamous cell carcinoma with a prevalence up to 50%. [5][6][7][8]

Chromosome stability in tonsillar squamous cell carcinoma is associated with HPV16 integration and indicates a favorable prognosis

“…33 We regarded a p value 0.05 as level of significance. The Kaplan-Meier method was used to calculate Cancer Genetics disease-specific survival curves.…”

“…Sections had been previously examined for HPV16 and -18 association by type specific FISH and PCR and cell cycle protein expression profiles. 19,33 Patient material was used according to the code for proper secondary use of human tissue (Federation of Medical Scientific Societies, The Netherlands; 2003). Demographic data, tumor site, degree of differentiation, TNM classification and clinical follow-up data of all patients were available.…”

“…Chromosome copy number-data were correlated with the HPV16 status, as well as clinical and lifestyle parameters. 31,33 Furthermore, we were able to select eight additional HPVpositive tonsillar dysplasias, seven of which were found adjacent to a TSCC, for comparison of chromosomal (in)stability and the physical status of HPV.…”

Discrimination of ‘Driver’ and ‘Passenger’ HPV in Tonsillar Carcinomas by the Polymerase Chain Reaction, Chromogenic In Situ Hybridization, and p16INK4a Immunohistochemistry

“…Moreover, HPV status is important in TSCC patient management since HPV positive tumors may have a favorable prognosis [1][2][3][4][5][6][7][8][9][10]. The prevalence of HPV (mostly HPV16) in TSCC varies from 29 to 93% [1][2][3][4][5][11][12][13][14]; the highest values have been reported using PCR methods; lower ones have generally been found following in situ hybridization or immunohistochemical (IHC) assays [15]. Episomal and integrated HPV DNA have been reported in TSCC [6,7].…”

“…INK4a immunoreactivity has been demonstrated in 35-56% of TSCCs; staining is usually absent in non-HPV associated oropharyngeal SCC [4,6,20].…”