Ubenimex, an APN inhibitor, could serve as an anti-tumor drug in RT112 and 5637 cells by operating in an Akt-associated manner

Abstract

Bladder cancer, a common urinary tract tumor, has high mortality and recurrence rates associated with metastasis. Aminopeptidase N (APN) expression and metastasis have been indicated to be associated with one another. Ubenimex may function as an APN inhibitor to inhibit the degradation of the extracellular matrix during tumorigenesis. Furthermore, APN has been widely used as an adjuvant therapy for the treatment of tumors; however, little information is available regarding the impact of ubenimex on patients. Autophagy is suggested to be important in the transformation and progression of cancer. Additionally, apoptosis, which leads to the rapid demolition of cellular organelles and structures, has also been suggested as an important factor. Thus, the present study investigated the role of ubenimex in inhibiting migration and invasion by downregulating APN expression levels to induce autophagic cell death and apoptosis in bladder cancer cells. RT112 and 5637 cell lines were treated with varying doses of ubenimex. Cell viability was measured by CCK8 colorimetry and flow cytometry. Using fluorescence microscopy, autophagic cell death was assessed using acridine orange/ethidium bromide staining. Furthermore, apoptotic cell death was assessed using flow cytometry and Trypan blue staining was used to evaluate the cell death rate. Protein expression was determined by western blot analysis. Matrigel invasion assays were exploited to assess the invasion capabilities of 5637 cells. Wound-healing migration assays and Matrigel migration assays were exploited to assess the migratory abilities of 5637 cells. Treatment with ubenimex was accompanied by decreased Akt expression, indicating that ubenimex may have similar functions to Akt inhibitors. Results also indicated that ubenimex inhibited cell migration and invasion in bladder cancer cells. Furthermore, ubenimex also induced autophagic cell death and apoptosis, which suggested that mixed programmed cell death occurred in ubenimex-treated bladder cancer cells. The results from the present study suggest that ubenimex may be a potential adjuvant therapy for the treatment of bladder cancer.