EXPRESSION OF KERATIN-13, KERATIN-14 AND KERATIN-19 IN ORAL SQUAMOUS-CELL CARCINOMAS FROM SUDANESE SNUFF DIPPERS - LACK OF ASSOCIATION WITHHUMAN-PAPILLOMAVIRUS INFECTION

In stratified squamous epithelia, altered expression of keratins (Ks) is one possible marker of malignant potential. In the epithelium of th e uterine cervix, presence of human papillomaviruses (HPVs) is increas ingly regarded as a marker of risk for cervical cancer. However, a sim ilar role in oral cancer and precancer remains controversial. To addre ss these questions, formalin-fixed, paraffin-embedded oral carcinomas from Sudanese snuff dippers (n = 14) and oral carcinomas from Sudanese (n = 14), Swedish (n = 19) and Norwegian (n = 41) non-snuff dippers w ere examined by immunohistochemistry for expression of K types 13, 14 and 19 using monoclonal antibodies. HPV infection was searched for in all the carcinomas by in situ hybridization (ISH) using the cocktail H PV OmniProbe and the ViraType probe. Carcinomas from Sudanese (snuff d ippers/non-snuff dippers) were also examined for HPV infection by poly merase chain reaction (PCR) using the general HPV primers GP5+/GP6+. F or the oral carcinomas from snuff dippers, moderate to intense express ion of K13 (71%; 10/14), K14 (86%; 12/14) and K19 (93%; 13/14) was fou nd. For the oral carcinomas from non-snuff dippers, weak to moderate e xpression of K13 (64%; 47/74), K14 (43%; 32/74) and K19 (45%; 33/74) w as found. HPV DNA was not detected in any of the carcinomas from three countries when examined by ISH. The Sudanese (from snuff dippers/non- snuff dippers) oral carcinomas were also negative for HPV DNA with the PCR. The present study shows that (i) there is a high level of expres sion of K13, K14 and K19 in oral carcinomas from snuff dippers compare d to those from non-snuff dippers, (ii) this high level of expression may arise from dysregulation of keratinocyte proliferation and maturat ion caused by damaging effects of snuff, (iii) the HPV genome is not f ound in Sudanese (snuff dippers/ non-snuff dippers), Swedish or Norweg ian oral carcinomas, and (:iv) this may suggest that these viruses do not play a prominent role in the aetiology of oral carcinomas from the se countries.