Microsatellite Instability and the Expression of Tumor-associated Genes in Multiple Cancer

ABSTRACT

Genetic changes associated with oncogenes or tumor suppressor genes are frequently observed in human cancers. These changes may be more frequent in multiple primary cancers than sporadic cancers. These experiments were designed in order to know the genetic changes using microsatellite PCR technique and the expression of tumor-associated genes by immunohistochemistry for c-myc and p53 in 17 cases of multiple primary carcinomas. The niicrosatellite instability (MSI) were found in 8 of 17 cases (47.1 %); six cases showed MSI in more than two microsatellite loci and two cases revealed MSI in one locus. MSI was found in 2 out of 7.patients (28.6%) of multiple primary carcinomas arising from the unrelated organs, and 6 out of 10 patients (60.0%) arising from the same or related organs. When each case of multiple primary carcinomas was examined, immunohistochemistry for c-myc was positive in 25 cases (71.4%) and p53 was positive in 21 cases (60.0%) out of 35 cases. But there was no correlation between MSI and expression of tumor-associated genes. From the above the results, MSI is more important in carcinogenesis of multiple primary carcinomas arising from the same or related organs than those from unrelated organs.