Transcriptionally Active High-Risk Human Papillomavirus in Salivary Mucoepidermoid Carcinoma – A Novel Finding.
Tatyana Isayeva, Shuting Bai, Nasser Said-Al-Naief, Douglas Gnepp, Margaret Brandwein-Gensler. UAB, Birmingham; University of the Pacific, San Francisco, CA; Rhode Island Hospital, Providence
Background: Mucoepidermoid carcinoma (MEC) is a common salivary tumor of unknown pathogenesis. Epidemiological and molecular data have established high-risk human papillomavirus (HR HPV) in the pathogenesis of many oropharyngeal squamous carcinomas. Interestingly, a recent analysis of the SEER data suggests that the incidences of oral/oropharyngeal MEC are significantly increased in young females from 1975 to 2005. Here we test the hypotheses that HPV is involved in pathogenesis of MEC, with increasing contribution over time.
Design: This exploratory study included consecutive patients from 1980-2010 with confirmed diagnoses, and available paraffin-embedded specimens. Morphologically-guided 1 mm tumor cores were harvested from the paraffin blocks and deparaffinized, DNA was extracted with phenol-chloroform and precipitated with ammonium acetate; total RNA was isolated with TRIzol and precipitated with isopropyl alcohol. DNA and RNA were treated with RNase and DNase respectively. RNA was reverse-transcribed using cDNA synthesis kit. HPV16 / HPV18 E6 / E7 transcripts were measured by PCR and RT-PCR. Quantitative PCR was performed using Bio-Rad SYBR green supermix and Opticon2 detection system. Assays were performed in triplicate with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and beta-actin internal controls to confirm specimen suitability. HeLa and SiHa cells were the positive controls for HPV18 and HPV16, respectively. All specimens negative for HR HPV and GAPDH/B-actin transcripts were deemed unsuitable and excluded.
Results: We had suitable specimens from 90 patients, ages 17-85, (mean 49); 70 tumors were intraoral, 16 were parotid-based, and 2 arose in the submandibular and sublingual glands, respectively. At least one HR HPV transcript was detected in 56 of 90 tumors; 8 MEC had both HPV16 E6/E7 transcripts, 6 had both HPV18 E6/E7 transcripts, and 2 MEC had all four transcripts (HPV16/HPV18 E6/E7). MEC diagnosed in 2000 or later were significantly more likely to harbor at least one HR HPV transcript as compared to MEC diagnosed prior to 2000 (p = 0.0467, Fischer two-tailed exact test).
Conclusions: These intriguing results demonstrate that transcriptionally active HPV16/18 can be detected in MEC, and are more common in tumors diagnosed after 2000. Thus it is likely that HR HPV may be an increasing contributor to the pathogenesis of MEC; it is unlikely that RNA degradation in older specimens spuriously contributed to this finding, as all specimens had confirmed housekeeping internal controls.
Category: Head & Neck
Tuesday, March 1, 2011 8:15 AM
Platform Session: Section G, Tuesday Morning