THE EXPRESSION PATTERN OF WILMS-TUMOR GENE (WT1) PRODUCT IN NORMAL-TISSUES AND PEDIATRIC RENAL TUMORS

WT1, the Wilms' tumour suppressor gene located at chromosome 11p13, pl ays an important role in the development of the kidney, It is mutated in 10 per cent of Wilms' tumours (WTs) and their putative precursors c alled nephrogenic rests (NRs). A sensitive immunohistochemical techniq ue was established to localize the WT1 gene product in archival normal tissues and paediatric renal tumour samples, Strong nuclear signal wa s seen in the various sites such as the kidneys, gonads, and decidua. Nuclear immunoreactivity of variable intensity was also seen in the sk eletal muscle, smooth muscle of urinary bladder, ureter, and arteries. All 28 WTs (including the anaplastic variant) showed the WT1 gene pro duct in a varying proportion of the blastema, epithelium, and stroma, The anaplastic nuclei in sis WTs showed an intensity of staining compa rable to their adjacent favourable histology counterparts. All the int ralobar and perilobar types of NR demonstrated the WT1 gene product, A ll three malignant rhabdoid rumours were positive, while three of four mesoblastic nephromas and a clear cell sarcoma were negative, These f indings pro,ide an insight into the interrelationships of these renal tumours.