Low Incidence of Microsatellite Instability in Patients With Cervical Carcinomas

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Abstract
Alterations in microsatellite sequences have been reported in a variety of human cancers. Microsatellite instability is thought to reflect the inactivation of genes involved in DNA mismatch repair (MMR), which could predispose to the accumulation of further genetic errors in affected cells. Genomic instability in human cancers might also result from the inactivation of cell cycle controls such as the p53-dependent G1 checkpoint that prevents cell replication in response to DNA damage. High-risk human papillomavirus (HPV) is thought to contribute to the development of HPV-associated cancers, including cervical carcinoma, through the interaction of the E6 and E7 viral oncoproteins with two major cell cycle regulatory proteins, namely p53 and the retinoblastoma gene product (pRb). Although the high-risk HPV is prevalent in cervical carcinomas, viral DNA is not detected in a minor proportion of the cases. The HPV infection is insufficient for the development of cervical cancer, which indicates that additional genetic events are involved in the process. This study reports the potential role of MMR gene defects (in addition to or independent of HPV infection) in patients with cervical carcinogenesis. Microsatellite instability and HPV status were analyzed in a series of 54 patients with cervical carcinomas and in two associated cell lines. Microsatellite alterations were examined at 10 loci located in different chromosomes by using semiautomated fluorescent DNA technology and polymerase chain reaction. The HPV types were detected by a general primer polymerase chain reaction method. The results indicate that microsatellite instability is very infrequent in cervical carcinoma and occurs independently of HPV status.