Abstract 5296: Evaluation of HER2 and topoisomera II alpha (TOP2a) expression and gene number in penile carcinoma according to HPV status.

Abstract

BACKGROUND: Penile squamous cell carcinoma (PSCC) is a rare tumor. In specific regions of developing countries, however, it may represent one the most frequent male tumors. Presence of lymph node metastasis (LNM) is the main factor significantly associated with reduced survival, and molecular markers to predict it have been extensively pursued. HER2 is an oncogene part of the EGFR family, often overexpressed in PSCC. HER2 overexpression is associated with poor prognosis and presence of LNM in breast tumors, and it is generally coamplified with topoisomerase IIα (TOP2A), a neighboring gene that is a target for anthracyclines. MATERIAL AND METHODS: We evaluated the frequency of HPV infection in 84 PSCC samples.The presence or absence of HPV DNA was established using generic primers (GP5+/GP6+) specific for the L1 gene of several HPVs. Genotyping of positive samples was done by dot blot hybridization using radioactive probes. Expression of HER2 and TOP2a was evaluated through immunohistochemistry and automatedly quantified using ScanScope XT, Aperio. Sixty cases were also submitted to a triple-color fluorescence in situ hybridization (FISH) assay using probes for the genes of HER2 and TOP2a, and also for the chromosome 17 centromere. Cases showing two signals of each probe were considered non-altered, those showing more than two signals of each probe were considered polysomy and those showing more HER2 or TOP2a signals compared to centromere signals were considered amplified. RESULTS: HPV infection, characterized by detection of viral DNA on the samples, was observed in 22.6% (19) of the cases. Among the positive HPV samples, 51.3% were infected by HPV16, 21.6% by HPV18, and 2.7% by both subtypes concomitantly. In agreement with studies that showed better prognosis of tumors with HPV infection, 5-year and 10-year survival of HPV-positive patients was, respectively, 79.1% and 70.8%, whereas of HPV-negative patients was 60.2% and 38.7% (p=0,018). Immunohistochemistry showed nuclear positivity for TOP2a in 74.2% (106) cases and cytoplasmic expression of HER2 was seen in 20,3% (29) of cases, which was associated with higher histologic grade (p <0,001) and lower overall survival in multivariate analysis (RR=2,966; IC 95% [1,6-5,2]; p<0,001). No membrane staining for HER2 was observed. There was not an association between expression of HER2 and TOP2a (p=0.970), nor with these markers and HPV infection (p=0.177 and p=0.336, respectively). FISH analysis revealed 55 out of 60 cases without gene alterations (91.7%), and five cases (8,3%) presenting polysomy of chromosome 17. No amplification of HER2 or TOP2a genes was observed.CONCLUSIONS: Overexression of TOP2a was frequent and cytoplasmic HER2 associates with poor outcome of PSCC patients. HPV infection seem to have a positive impact in patients’ survival, as reported for other tumors. Citation Format: Alice M. Silva, Lara Termini, Jose Ivanildo Neves, Isabela Cunha, Ademar Lopes, Gustavo Guimaraes, Fernando A. Soares. Evaluation of HER2 and topoisomera II alpha (TOP2a) expression and gene number in penile carcinoma according to HPV status. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5296. doi:10.1158/1538-7445.AM2013-5296