High-Risk Human Papillomavirus Is Transcriptionally Active in a Subset of Sinonasal Squamous Cell Carcinomas

Ana B Larque; Sofia Hakim; Jaume Ordi; Alfons Nadal; Alba Diaz; Marta del Pino; Lorena Marimon; Isam Alobid; Antonio Cardesa; Llucia Alos

Disclosures

Mod Pathol. 2014;27(3):343-351. 

In This Article

Abstract and Introduction

Abstract

It has been reported that high-risk human papillomavirus (HPV) is a causative agent of a subgroup of oropharyngeal carcinomas. In these tumors, the presence of the transcriptionally active HPV has been proved through the identification of HPV E6 or E7 messenger RNA (mRNA) transcripts. The aim of the study was to assess the HPV-active transcription in a series of sinonasal carcinomas, in correlation with the HPV DNA identification and the p16 immunohistochemistry. Seventy patients with squamous cell carcinomas of the sinonasal tract were included in the survey. The main clinicopathological characteristics were recorded. All tumors were investigated for HPV through the HPV DNA detection by PCR, using the SPF10 primers and by in situ hybridization, using the high-risk GenPoint probe (Dako, Glostrup, Denmark). HPV16 E7 mRNA transcripts detection was performed by RT-PCR in 27 cases. The immunostaining for p16 was performed in all cases. Fourteen carcinomas (20%) were positive for high-risk HPV by PCR: 13 HPV16 and one HPV35. In situ hybridization showed a dotted nuclear positivity in all these cases. HPV16 E7 mRNA was detected in seven tumors harboring HPV16; in the remaining HPV-positive cases, RNA did not reach the quality for analysis. Strong, diffuse positivity for p16 was observed only in the HPV-positive cases. The 14 HPV-positive squamous cell carcinomas were non-keratinizing or scarcely keratinizing tumors. No significant differences were found in terms of gender, age, or staging at diagnosis between HPV-positive and HPV-negative tumors. However, differences in disease-free survival and overall survival between both groups of patients were significant (P=0.004 and P=0.028, respectively). In conclusion, we have shown that HPV is the etiological agent of a subset of sinonasal carcinomas demonstrating the transcriptionally active HPV in these tumors. Immunostaining for p16 can be used as a surrogate marker to identify these tumors.

Introduction

High-risk human papillomavirus (HPV) has been etiologically associated with a subgroup of squamous cell carcinomas of the head and neck. The prevalence of the HPV-associated squamous cell carcinomas in this area mainly depends on the anatomic location: they are unusual in the larynx and oral mucosa and are frequent in the oropharynx.[1–3]

Over the past few years, the clinical importance of detecting these HPV-associated squamous cell carcinomas in the head and neck region has been stressed, and the HPV assessment is already recommended in the pathological evaluation of oropharyngeal squamous cell carcinomas by the American Joint Committee on Cancer.[4] The HPV-associated squamous cell carcinomas are a biologically different entity from HPV-negative squamous cell carcinomas. They usually are non-keratinizing or scarcely keratinizing and may have the morphology of a poorly differentiated or basaloid squamous cell carcinoma, with high-proliferative scores. However, in spite of these apparently poor prognostic histological characteristics, these tumors present a very good response to therapy adjuvant to surgery, such as radiotherapy and chemotherapy, even when they are diagnosed at advanced stages.[5–8] This fact has a great relevance for squamous cell carcinomas of the sinonasal tract, where adjuvant therapy is usually required to treat the tumors, because of the complexity of the region anatomy that makes extensive surgery difficult in a large number of cases. However, it has been shown that HPV detection in squamous cell carcinomas is clinically and prognostically relevant only in those cases in which the virus is transcriptionally active.[9] HPV causes malignant transformation of keratinocytes through the expression of the oncoproteins E6 and E7. The HPV E6 protein forms a complex with an ubiquitin ligase (E6-associated protein), and ubiquinates the p53 tumor-supressor protein. The HPV E7 protein binds to the cullin 2 ubiquitin ligase complex and ubiquitinates the retinoblastoma tumor-suppressor protein (pRb). Because of the absence of pRb function, the E2F family of transcription factors is released, leading to S-phase genes transcription and cell proliferation.[10] The detection of HPV E6 or E7 messenger RNA (mRNA) is considered the gold standard in identifying the transcriptionally active HPV infection.[9,11] This identification permits confirmation that the HPV is the causative agent of the neoplasm, and has been previously reported in oropharyngeal carcinomas.[9,12,13] In the sinonasal tract, previous studies performed by us and others have identified the presence of high-risk HPV DNA in about 20% of squamous cell carcinomas, in more than 90% of cases corresponding to HPV16.[7,14–16]

In this study, we correlate the results of different techniques employed to detect HPV in a series of sinonasal squamous cell carcinomas, including the HPV16 E7 mRNA transcripts detection, with the aim of confirming the HPV as a causative agent of these neoplasms. In addition, we want to establish p16 immunostaining as a surrogate marker of this infection.

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