Résumé
Objective To examine loss of heterozygosity (LOH) and microsatellite instability (MSI) of locus D8S532 on chromosome 8 and their influence on the expression of sFRP1 in the hepatocellular carcinoma (HCCs), which may provide an experimental evidence for clarifying the mechanism of sFRP1 gene and tumor development. Methods DNA was extracted from formalin-fixed paraffin-embedded tissues. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and ordinary silver stain were used to study LOH and MSI of locus D8S532. Envision immunohistochemistry, Leica-Qwin computerized imaging system and Image-Pro PluS (IPP) version 4.5 professional imaging analysis software were used to assess the expression of sFRP1. Results The detection rates of LOH and MSI of locus D8S532 in the 36 specimens of HCC were 11.11% and 8.33% respectively. The down-regulation of sFRP1 was observed in 31 of 36 HCCs (86.11%) compared with non-carcinoma liver tissues, and the positive rate of sFRP1 protein of the HCCs was 52.78%( 19/36 ). The frequency of LOH was lower in the cases with positive expression of sFRP1 protein than those negative (0 vs 23.53%, P <0.05). Conclusion It was a common phenomenon that expression of sFRP1 protein is negative or low in Chinese with HCCs. The genetic instability of sFRP1 gene was one of causes, which lead to HCCs. LOH may play a major role in negative expression of sFRP1.