Human Schlafen 5 (SLFN5) Is a Regulator of Motility and Invasiveness of Renal Cell Carcinoma Cells

We provide evidence that human SLFN5, an interferon (IFN)-inducible member of the Schlafen (SLFN) family of proteins, ex-hibits key roles in controlling motility and invasiveness of renal cell carcinoma (RCC) cells. Our studies define the mechanism by which this occurs, demonstrating that SLFN5 negatively controls expression of the matrix metalloproteinase 1 gene (MMP-1), MMP-13, and several other genes involved in the control of malignant cell motility. Importantly, our data establish that SLFN5 expression correlates with a better overall survival in a large cohort of patients with RCC. The inverse relationship between SLFN5 expression and RCC aggressiveness raises the possibility of developing unique therapeutic approaches in the treatment of RCC, by modulating SLFN5 expression. Interferons (IFNs) are cytokines with important antineoplasticactivities and therefore are frequently utilized in the treatment of cancer (1–4). A malignancy that exhibits sensitivity to inter-feron treatment is renal cell carcinoma (RCC) (5). RCC is the most common type of kidney tumor in humans and is associated with high morbidity and mortality (6, 7). In general, patients with recurrent or advanced disease have limited treatment options and a very poor overall prognosis (7). The Schlafen (SLFN) family of genes includes several members that share structural homolog