IGFBP-rP1 acts as a potential tumor suppressor via the suppression of ERK signaling pathway in endometrial cancer cells

Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) is a potential tumor-suppressor gene in various cancers. However, its biological role and underlying mechanism has not been well investigated in endometrial cancer yet. The aim of the present study aimed to investigate the role and underlying molecular mechanisms of IGFBP-rP1 in endometrial cancer cells in vitro. The authors used transfection of IGFBP-rP1 or small interfering (si)RNA in endometrial cancer HEC-1A or Ishikawa cells, respectively. Biological functional alterations, such as cell growth and cell cycle were analyzed in endometrial cancer cells, combined with the use of PD98059. A panel of proteins including phospho-retinoblastoma (p-RB) and p-extracellular signal-regulated kinase (ERK)/ERK were detected by western blot analysis. It was observed that IGFBP-rP1 transfection inhibited cell growth, and induced G1 phase arrest and cellular senescence in HEC-1A cells while gene silencing presented the adverse functional changes. Moreover, p-RB and p-ERK were significantly downregulated or upregulated in HEC-1A-IGFBP-rP1 cells or Ishikawa-siRNA (IGFBP-rP1) compared with control cells, respectively. These observations were reinforced in endometrial cancer cells by PD98059 treatment. The authors conclude that IGFBP-rP1 acts as a potential tumor suppressor via the suppression of the ERK signaling pathway in endometrial cancer cells. These findings suggested that IGFBP-rP1 may serve as a potential therapeutic target for cancer intervention in the future.