Aldo-keto reductase 1C1 induced by interleukin-1β mediates the invasive potential and drug resistance of metastatic bladder cancer cells

In treating bladder cancer, determining the molecular mechanisms of tumor invasion, metastasis, and drug resistance are urgent to improving long-term patient survival. One of the metabolic enzymes, aldo-keto reductase 1C1 (AKR1C1), plays an essential role in cancer invasion/metastasis and chemoresistance. In orthotopic xenograft models of a human bladder cancer cell line, UM-UC-3, metastatic sublines were established from tumors in the liver, lung, and bone. These cells possessed elevated levels of EMT-associated markers, such as Snail, Slug, or CD44, and exhibited enhanced invasion. By microarray analysis, AKR1C1 was found to be up-regulated in metastatic lesions, which was verified in metastatic human bladder cancer specimens. Decreased invasion caused by AKR1C1 knockdown suggests a novel role of AKR1C1 in cancer invasion, which is probably due to the regulation of Rac1, Src, or Akt. An inflammatory cytokine, interleukin-1β, was found to increase AKR1C1 in bladder cancer cell lines. One particular non-steroidal anti-inflammatory drug, flufenamic acid, antagonized AKR1C1 and decreased the cisplatin-resistance and invasion potential of metastatic sublines. These data uncover the crucial role of AKR1C1 in regulating both metastasis and drug resistance; as a result, AKR1C1 should be a potent molecular target in invasive bladder cancer treatment.