Role of ubenimex as an anticancer drug and its synergistic effect with Akt inhibitor in human A375 and A2058 cells

Xiaoqing Wang,¹ Yang Liu,¹ Rongde Wu,¹ Feng Guo,¹ Lijuan Zhang,¹ Mingyu Cui,¹ Xiangyu Wu,¹ Yongfei Zhang,² Wei Liu<sup>1

1</sup>Department of Pediatric Surgery, Shandong Provincial Hospital affiliated to Shandong University, Jinan, People’s Republic of China; ²Department of Dermatology, Shandong Provincial Qianfoshan Hospital affiliated to Shandong University, Jinan, People’s Republic of China

Background: Malignant melanoma (MM) is a malignant tumor produced by changes in melanocytes in the skin or other organs. In the classification of skin tumor mortality, skin melanoma ranks the highest. Ubenimex, an Aminopeptidase N (APN) inhibitor, is now widely used for cancer as an adjunct therapy, conferring antitumor effects. Apoptosis and the induction of autophagy have both been found to be closely associated with tumor cell death.
Methods: In this study, the A375 and A2058 cell lines were treated with ubenimex. Cell viability was measured using the Cell Counting Kit 8 assay. Apoptosis and autophagic cell death were assessed using flow cytometry and acridine orange/ethidium bromide staining. Protein expression was assessed by Western blot analyses and immunofluorescence. Matrigel invasion and migration assays were used to examine the metastatic ability of melanoma cells.
Results: The results revealed that ubenimex inhibited the expression of APN in melanoma cells, which may be connected with the inhibition of metastasis. In addition, it increased melanoma cell death by inducing apoptosis and autophagic cell death. This effect was accompanied by increased levels of p-JNK. Moreover, treatment with ubenimex induced protective Akt activation, and combined use of an Akt inhibitor with ubenimex provided a better effect for inducing tumor cell death.
Conclusion: As an effective anti-tumor drug in vitro, ubenimex might be an excellent adjunctive therapy for the treatment of melanoma, with greater effects when combined with the use of an Akt inhibitor.

Keywords: melanoma, ubenimex, jnk, Akt, mixed cell death, metastasis