DIFFERENTIAL EXPRESSION OF THYMOSIN GENES IN HUMAN TUMORS AND IN THE DEVELOPING HUMAN KIDNEY

Thymosins beta-4 and beta-10 are 2 structurally related polypeptides originally defined in the rat immune system. To date, no truly unambiguous functions have been formally ascribed to these small (< 4.9 kDa) acidic proteins. Previous research has demonstrated relationships between expression of these genes and cell growth/differentiation. These observations prompted the present study which has used cDNA and synthetic oligonucleotide probes in combination with high-performance liquid chromatography (HPLC) to examine the differential expression of these 2 genes in normal and neoplastic human tissues and in the developing human kidney. Low levels of beta-4 and beta-10 mRNA species prevailed in normal tissues; in contrast, these gene transcripts were notably more abundant in malignant renal tumors and in the normal human embryonic kidney. These findings show that the thymosin beta-4 and beta-10 genes are constitutively expressed at higher levels in embryonic/neoplastic as compared to normal/benign tissues and that thymosin in beta-10 in particular may be a new molecular marker for renal-cell carcinoma as well as other malignancies.