Jiang Z et al. (2006) Analysis of RNA-binding protein IMP3 to predict metastasis and prognosis of renal-cell carcinoma: a retrospective study. Lancet Oncol 7: 556–564

Preliminary studies have demonstrated that the insulin-like growth factor mRNA-binding protein IMP3 can promote the proliferation of human leukemia cells. As part of a program to develop clinical biomarkers to predict metastasis and prognosis of renal-cell carcinomas, Jiang et al. have investigated whether expression levels of IMP3 in renal-cell carcinomas are related to tumor metastasis.

By using immunohistochemical analysis, the investigators quantified levels of IMP3 in 406 primary renal carcinomas obtained from radical or partial nephrectomy and 95 samples of metastatic renal-cell carcinoma. A total of 371 patients with localized primary tumors were also followed up over a median of 63 months to determine whether their cancer had spread. Compared with nonmetastatic renal-cell tumors, markedly elevated levels of IMP3 expression were found in metastatic tumors, as well as in a subset of primary tumors that were likely to subsequently develop metastases. Approximately 80% of patients with primary tumors that tested positive for IMP3 developed metastatic cancer, compared with 13% of patients with IMP3-negative tumors. After adjustment for well-known clinical variables, statistical analysis showed that over 5 years patients with IMP3-positive tumors were almost six times more likely to develop metastasis and four times more likely to die than those with IMP3-negative tumors.

In summary, these data indicate that IMP3 has a role in the metastasis of renal-cell carcinoma and could prove to be a useful prognostic marker, with therapeutic implications for the selection of patients to undergo early systemic treatment following a nephrectomy.