Basal keratinocyte tetrasomy in low-grade squamous intra-epithelial lesions of the cervix is restricted to high and intermediate risk HPV infection but is not type-specific

Human papillomavirus (HPV) infection appears to be an early event in cervic al carcinogenesis with additional abnormality being required for biological transformation. We have analysed 179 low-grade cervical squamous intra-epi thelial lesions (SILs) and 15 normal cervices for the presence of HPV using both in situ hybridization and polymerase chain reaction (PCR). PCR was pe rformed with GP5+/GP6+ primers followed by hybridization using probes for l ow (HPV 6, 11, 40, 42, 43, 44), intermediate (HPV 31,33, 35, 39, 51, 52, 58 , 59, 66 and 68) and high-risk HPVs (HPV 16, 18, 45 and 56). Interphase cyt ogenetic analysis using pericentromeric probes for chromosomes 1, 3, 4, 6, 10, 1 1, 17, 18 and X was also performed to identify numerical chromosomal abnormalities. Tetrasomy of ail nine chromosomes was identified within basa l keratinocytes, was restricted to epithelia infected with high risk (17 of 46) or intermediate risk (23 of 83) HPVs but was not HPV type-specific. Te trasomy was not identified in any of the epithelia infected with low risk H PVs (n = 62). These numbers include multiple infection. These findings indi cate that the induction of tetrasomy is a property restricted to high and i ntermediate-risk HPV types but that it is not type-specific. The factors go verning which lesions will develop this abnormality are as yet unclear. (C) 2000 Cancer Research Campaign.