WT1 Gene Expression in Human Testicular Germ-Cell Tumors

The Wilms' tumor 1 gene (WT1) is a tumor suppressor gene whose alterations are linked to the genesis of Wilms¹ tumor. The gene is expressed in the urogenital organs and plays a key role in their development. Recent studies have shown that the WT1 gene product acts as a growth promoter of human leukemic cells. Because WT1 has been reported to be important in testicular development, we have investigated WT1 messenger RNA (mRNA) expression in testicular germ-cell tumors. Quantitative reverse transcription­polymerase chain reaction (RT-PCR) was used to examine the levels of WT1 mRNA in 34 patients with testicular germ-cell tumor, including 25 low-stage and 9 high-stage tumors. There were 23 seminomas and 11 nonseminomas. The WT1 mRNA was highly expressed in 6 of 9 high-stage lesions (67%) but only 5 of 25 low-stage cases (20%). A significant correlation was observed between the extent of WT1 mRNA expression and tumor stage (P = 0.017). There was no significant difference in WT1 mRNA expression between seminomas and nonseminomatous tumors. These results suggest that WT1 may be causal for the progression of testicular germ-cell tumors.