LOSS OF HETEROZYGOSITY OF THE RETINOBLASTOMA AND P53 GENES IN PRIMARYCERVICAL CARCINOMAS WITH HUMAN-PAPILLOMAVIRUS INFECTION

Objective. Paired DNA samples from 55 primary uterine cervical carcino mas and normal bloods were studied for chromosomal allelic loss (loss of heterozygosity; LOH) of the retinoblastoma (Rb) and p53 gene loci b y polymerase chain reaction (PCR) or PCR-restriction fragment length p olymorphism analysis. All the study samples contained at least one of the oncogenic human papillomavirus (HPV) type 16 and/or 18 sequences, And the relationships between allelic losses of these genes and conven tional clinicopathological parameters were evaluated. Methods, In orde r to detect LOH of the Rb gene in cervical cancers, we analyzed four p olymorphic intronic sites (intron 1, 17, 20, and 25) of the Rb gene an d one additional microsatellite near the Rb locus (D13S118), For detec tion of the LOH in p53, three intragenic polymorphisms (exon 1, exon 4 , intron 6) and one microsatellite distal to the p53 gene (D17S5) were examined. Results, By analyzing this system, we could increase the he terozygosity of the Rb and p53 loci up to 0.91 and 1, respectively. Th e observed allelic loss rates of the Rb and p53 loci in informative ca ses were 14% (7/50) and 5.5% (3/55), respectively, The patients with L OH at the D13S118 locus also had the allelic loss of the Rb gene, wher eas only one of the four patients with LOH at the D17S5 locus showed a concomittant allelic loss of the p53 gene, The frequency of cervical cancer with one LOH at the Rb or p53 loci was 20% (11/55), No shifted bands were observed in the PCR-single-strand conformation polymorphism analysis of the p53 gene, The LOH of the Rb or p53 gene was not signi ficantly associated with other parameters including clinical stage, hi stological type, degree of differentiation, status of HPV infection, a nd p53 gene mutation. Conclusion, Concerning the results above, we con clude that the allelic imbalance of the Rb or p53 gene itself is not i mplicated as a major contributing factor in the malignant transformati on or the tumor progression in HPV-positive uterine cervical cancers. (C) 1997 Academic Press.