Lenalidomide and pomalidomide inhibit growth of prostate stromal cells and human prostate smooth muscle contraction.

AIMS: Medical treatment for lower urinary tract symptoms secondary to benign prostatic hyperplasia is characterized by an unfavorable balance between limited efficacy and pronounced side effects. We recently reported, that thalidomide reduces prostate smooth muscle contraction and inhibits cell growth. Like thalidomide, its analogs lenalidomide and pomalidomide are also in clinical use. Therefore, we investigated the effects of lenalidomide and pomalidomide on human prostate smooth muscle contraction, cytoskeletal organization, and growth-related functions in stromal cells. MATERIALS AND METHODS: Proliferation was assessed by EdU assay and colony formation, cytoskeletal organization by phalloidin staining, cell viability by CCK8, and apoptosis and cell death by flow cytometry in cultured prostate stromal cells (WPMY-1). Contractions of human prostate tissues from radical prostatectomy were induced by methoxamine, noradrenaline, phenylephrine, endothelin-1, U46619, or electric field stimulation (EFS) in an organ bath. KEY FINDINGS: Proliferation of WPMY-1 cells was significantly reduced by lenalidomide (5-200 µM) and pomalidomide (2.5-5 µM). In parallel, organization of actin filaments collapsed after treatment with lenalidomide and pomalidomide. Lenalidomide and pomalidomide inhibited both adrenergic contractions and non-adrenergic contractions as well as neurogenic contractions induced by EFS. Neither reduction in viability, nor increase in cell death or apoptosis was observed in WPMY-1 cells. SIGNIFICANCE: Thalidomide-derivatives impair growth of human prostate stromal cells, without showing a decrease in cell viability and, in parallel, inhibit adrenergic, neurogenic, and non-adrenergic contractions by breakdown of the actin cytoskeleton. Urodynamic effects in vivo appear possible.