P16 immunostaining and HPV testing in histological specimens from the uterine cervix

Background: The cellular tumor suppressor protein pl61NK4a (p16) has been identified as a biomarker for transforming human papilloma virus (HPV) infections. P16 is a cyclin-dependent kinase inhibitor that regulates the cell cycle and cell proliferation by inhibiting cell cycle G1 progression. Purpose of the study: To confirm the role of p16 as biomarker for transforming HPV infections and possible clinical applications in histological samples from the uterine cervix. Materials and methods: The subject of this study included 56 biopsies of the cervical canal collected from January 2012 to September 2012 in the Institute of Pathology of the University of Sassari. The search for HPV immunohistochemistry was performed with the monoclonal antibody DAKO 1:25, while for the detection of p16 was used CINtecTM p16 (INK4a) histology kit. Results: In 56 biopsies performed in women aged between 23 and 69 years, the authors highlighted, by histological analysis, 24 cases of low-grade squamous intraepithelial lesion (LSIL) - cervical intraepithelial neoplasia (CIN1) and 31 cases of high-grade squamous intraepithelial lesion (HSIL) - CIN2/3); 15 CIN2, 14 CIN3, and two cervical squamous cell carcinoma in situ (SCIS). One case was an infiltrating squamous cell carcinoma (ISC). In 24 CIN1, there was a 16.67% positivity for p16 and an equal percentage occurred for HPV. In 15 cases of CIN2 the percentage of positivity for p16 was considerably increased (73.33%), unlike the search for HPV which had a positivity rate of 20%. Finally, in 14 cases of CIN3, and in three carcinomas, the positivity for p16 was equal to 100%, however the search for HPV positivity was between 0% and 7.14%. Conclusions: These results demonstrated that p16 was a highly sensitive marker of cervical dysplasia. The authors have shown that p16 overexpression increased with the severity of cytological abnormalities and that had a greater ability to identify the viral infection compared to the classical immunohistochemical staining for HPV.

Cervical cancer; Human papilloma virus (HPV); P16INK4a; Immunohistochemistry

[1] Tsoumpou I., Arbyn M., Kyrgiou M., Wentzensen N., Koliopoulos G., Martin-Hirsh P. et al.: “p16INK4a immunostaining in cytological and histological specimens from the uterine cervix: a systematic review and meta-analysis”. Cancer Treat. Rev., 2009, 35, 210.

[2] Cuschieri K., Wentzensen N.: “Human papillomavirus mRNA and p16 detection as biomarkers for the improved diagnosis of cervical neoplasia”. Cancer Epidemiol. Biomarkers Prev., 2008, 17, 2536.

[3] Wentzensen N., von Knebel Doeberits M.: “Biomarkers in cervical cancer screening”. Dis. Markers, 2007, 23, 315.

[4] Nakao Y., Yang Y., Yokoyama M., Ferenczy A., Tang S.C., Pater M.M., Pater A.: “Induction of p16 during immortalization by HPV 16 and 18 and not during malignant transformation”. Br. J. Cancer 1997, 75, 1410.

[5] Klaes R., Brenner A., Friedrich T., Ridder R., Herrington S., Jenkins D. et al.: “p16INK4a immunochemistry improves interobserver agreement in the diagnosis of cervical intraepithelial neoplasia”. Am. J. Surg. Pathol., 2002, 26, 1389.

[6] Dray M., Russel P., Dalrymple C., Wallman N., Angus G., Leong A. et al.: “p16INK4a as a complementary marker of high-grade intraepithelial lesions of the uterine cervix. Experience with squamous lesions in 189 consecutive cervical biopsies”. Pathology, 2005, 37, 112.

[7] Wang S.S., Trunk M., Schiffman M., Herrero R., Sherman M.E., Burk R.D. et al.: “p16INK4a as a marker of oncogenic human papillomavirus infection in cervical biopsies from a population-based cohort in Costa Rica”. Cancer Epidemiol. Biomarkers Prev., 2004, 13, 1355.

[8] von Knebel Doeberitz M.: “New markers for cervical dysplasia to visualise genomic chaos created by aberrant oncogenic papillomavirus infection”. Eur. J. Cancer, 2002, 38, 2229.

[9] Carozzi F., Confortini M., Dalla Palma P., Del Mistro A., Gillio-Tos A., De Marco L. et al.: “Use of p16-INK4A overexpression to increase the specificity of human papillomavirus testing: a nested substudy of the NTCC randomised controlled trial”. Lancet Oncol., 2008, 9, 937.