Increased in vitro tetraploidy: tissue specific within the heritable colorectal cancer syndromes with polyposis coli.

In vivo expression of human hereditary tumors are known to be tissue specific; in familial polyposis coli the genotype is expressed solely as colonic polyps that become malignant and in the Gardner syndrome as extracolonic connective tissue tumors and related neoplasms in addition to such colonic lesions. In vitro such tissue specificity was also seen in these 2 syndromes. Increased tetraploidy has been observed only in those cultures derived from tissues, which although appearing normal in the patient, were known to undergo malignant transformation in vivo based on clinical phenotypes and family histories: colonic mucosa in familial polyposis coli, skin and colonic mucosa in the Gardner syndrome. Cultures established from tissues known not to show neoplastic growth or from benign tumors (fibromas, sebaceous cysts and lipomas) did not show increased tetraploidy. Increased tetraploidy in cultures established from these 2 syndromes did not identify all cultured cells with either mutant genotype or those cells showing abnormal benign growths in vivo but rather only in those that are known to undergo malignant transformation in vivo in both syndromes. Such observations suggested that in these 2 syndromes there was a population of tetraploid cells, at least in culture, constantly present which may be relevant to the multi-step process of carcinogenesis.