engleski

Molecular Analysis of the APC Gene in Renal Cell Carcinoma

The role of adenomatous polyposis coli (APC) gene was investigated in development and progression of renal carcinoma. Thirty-six human renal cell carcinoma samples and 18 adjacent normal kidney tissues were tested for the expression of APC protein, both wild and truncated types, by western blot method. The same tumor samples together with autologous peripheral blood were also analysed at the DNA level. Using specific oligonucleotide primers for exons 11 and 15, gene instability was followed by polymerase chain reaction/loss of heterozygosity (LOH) using RFLP method. The results of our study show that all normal renal tissues express wild-type APC protein. Neither wild nor mutant type proteins were found in 36% (13/36) of tumor samples ; the rest of tumor tissues expressed the wild-type protein (312 kDa). Mutated APC protein, with a molecular weight of 117 kDa, was found in only one tumor sample. From 36 tumor samples 16 (44.4%) were informative for Rsa I exon 11 polymorphic site, while only half of these (8/16) demonstrated LOH. From 13 tumor samples that had no detectable protein product 8 were homozygous for the exon 11 polymorphism and were tested for another polymorphic site, Msp I/exon 15. The overall proportion of LOH cases for both polymorphisms was 52.9% (9/17). 56% of samples with LOH show loss of the wild type APC protein expression. Pathohistological diagnosis showed no correlation with molecular data. However, multivariate analysis indicated strong positive correlation of age and TNM stage with the presence of LOH and the absence of the wild-type APC protein. Our results suggest that APC tumor suppressor gene is not the initiator of renal tumorigenesis, but that alterations in this gene are responible for tumor evolution and progression.

APC gene; LOH; APC protein; RCC

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