Microsatellite Instability in Head and Neck Squamous Cell Carcinoma: A Study of a Brazilian Population

Abstract

Squamous cell carcinoma (SCC) is the sixth most common solid tumor in the world. Apart from known risk factors for head and neck SCC (HNSCC), there is a lack of information about genetic susceptibility regions that may play pivotal roles in the tumorigenesis of these tumors. Therefore, we have aimed to analyze the presence of genetic instability in microsatellite markers distributed in the genome. Microsatellite instability (MSI) was found in 6 HNSCC patients, among which only one was detected by the D17S250 marker, whereas the other 5 occurrences (13.5%) were detected by the D3S1611 marker. No instability was found at markers D5S346, D10S197, D11S922, and D11S988. MSI detected by D3S1611 marker was present in 3 (14.3%) moderately differentiated tumors and in 2 (25.0%) poorly differentiated tumors, but no statistical significance was found. Genotypic frequencies for all markers showed no statistically significant distribution alteration, neither were they related to differentiation grade or patient age. Marker D3S1611 is located in the MLH1 gene, which is part of the mismatch repair system (MMR), helping to maintain genomic stability. We have found a higher rate of D3S1611 MSI in older patients, suggesting that this marker may be affected by aging processes in the DNA repair machinery.