The piwi genes are highly conserved and play essential roles in stem cell self-renewal, gametogenesis and RNA interference. In 6 June Oncogene, Qiao and colleagues from Duke University Medical Center, Durham, USA, show that hiwi — a human member of the piwi gene family — is expressed in both normal and malignant spermatogenic cells and its overexpression is correlated to the development of seminoma (Oncogene 2002, 21:3988-3999).

Qiao et al. observed that hiwi maps to band 12q24.33 on the long arm of chromosome 12, a region linked to the development of testicular germ cell tumors. hiwi encodes a highly basic 861-amino-acid protein and its expression was seen in normal spermatocytes and round spermatids during spermatogenesis.

In addition, they observed enhanced expression of hiwi in samples of testicular seminomas — tumors originating from embryonic germ cells with retention of germ cell phenotype — but not in...