HPV infection and microsatellite instability in squamous lesions of the uterine cervix

The role of human papillomavirus (HPV) in the development of squamous lesions of the uterine cervix has been clearly established but other factors could be involved in cervical tumorigenesis, such as microsatellite instability (MI). The aim of the present study was to analyze the relationship between HPV infection and MI. Thirty-two cervical samples were analyzed: 11 low-grade CIN (LCIN), 18 high-grade CIN (HCIN) and 3 carcinomas. DNA was extracted from formalin-fixed, paraffin embedded tissue for PCR study with HPV 6/11, 16, 18 and 7 microsatellite primers: D2S123 (cr2), MFD39 (cr8), 635-636 (cr15q), MFD67 (cr1), D11S905 (cr11), SCZD1 (cr5q) and DM (cr19). HPV was detected in 82% of LCIN (16 and 18 types in 64% of cases) and in 33% of HCIN (16 type in 22% of cases). The difference between LCIN and HCIN was statistically significant (p = 0.014), in particular for 16 and 18 HPV types (p = 0.033). Forty-seven per cent of total cases showed MI with no more than 3 different loci per case: 27% of LSIL, 61% of HCIN and 33% of carcinomas (not statistically significant). In 45% of HCIN cases there were both MI and HPV. In conclusion, cervical carcinoma is linked to HPV infection but MI could also be involved in cervical tumorigenesis.