Transcriptionally Active HPV Infection and Salivary Adenoid Cystic Carcinomas
Tatyana Isayeva, Deyin Xing, Margaret S Brandwein-Gensler. University of Alabama at Birmingham, Birmingham, AL
Background: The rate of high-risk Human Papillomavirus (HR-HPV)-mediated carcinogenesis has been steadily increasing over the past three decades with respect to oropharyngeal cancer. The issue of HPV as a potential contributor to salivary malignancies is currently under investigation. We have previously demonstrated transcriptionally active HPV16/18 in 43% of mucoepidermoid carcinomas. HR-HPV has been detected by Boland et al in salivary adenoid cystic carcinomas (ACC) studied by in-situ hybridization. Here, we assess the detection rate of transcriptionally active HPV16/18 in ACC.
Design: 41 patients with confirmed diagnosis of ACC were studied. This is a retrospective cohort from 2004 to 2012, the female to male ratio was 1:1, and mean age was 59 years (range 29-93). Samples were procured from paraffin blocks by sterile technique, tumor selection was morphologically guided to avoid including any overlying squamous mucosa. Nested PCR was performed on the extracted DNA with Gp5+/6+ consensus primers including appropriate internal, positive, and negative controls. All tumors positive by PCR were further studied by nested real-time PCR for type-specific cDNA; RNA was extracted and reverse transcription was performed. DNAase was used to remove any residual DNA. Primer pairs for HPV16E6, HPV16E7, HPV18E6, and HPV18E7 were used and appropriate controls were included. ACC samples were designated as HPV positive only if both concordant type-specific E6 and E7 cDNA sequences were detected.
Results: HPV genome (untyped) was detected in 20/41 (48.8%) of patient samples. HPV16E6/E7 was detected in 12/41 (29.3%) and HPV18E6/E7 was detected in 2/41 (4.9%) of ACC. One ACC was HPV16/18 double positive. Six ACC were consensus primer positive and HPV16/18 negative, suggesting infection by other HPV types; HPV typing in ongoing. No association was seen between HPV status and patient gender, age, and tumor site; there was no association between HPV genome detection and specimen age. However, HPV cDNA was significantly less likely to be detected in specimens prior to 2010, as compared to specimens from 2010 and later (p = 0.0171, Fisher's two-tailed exact test).
Conclusions: HPV genome has been detected in almost half of 41 ACC studied by nested PCR using consensus primers; these data do not address the issue of passenger versus driver infection. Transcriptionally active HPV16/18 was detected in almost one third of ACC. RNA degradation may account for the decreased transcript detection rate for older specimens. These data do not establish causality, but suggest a potential for HR-HPV to contribute to ACC-carcinogenesis.
Category: Head & Neck
Tuesday, March 5, 2013 9:30 AM
Poster Session III # 157, Tuesday Morning