Gene amplification and multiple mutations of the K-ras oncogene in Kaposi's sarcoma.

Thirty one biopsy samples of fresh Kaposi's sarcoma (KS) skin lesions were examined for alteration of the K-ras oncogene by differential PCR, SSCP and nucleic acid sequencing. Three KS specimens showed amplification of K-ras and 7 were found to have various mutations at exon 1 of the K-ras gene. Eight of the 10 K-ras gene alterations detected were found in more advanced nodular stage KS lesions, while only 2 were observed in the plaque stage KS tumors. Activation of the K-ras oncogene may play a role in the malignant progression of this unusual neoplasm.