Overexpression of Dock180 and Elmo1 in Melanoma is Associated with Cell Survival and Migration

Abstract

Background: Melanoma is one of the most aggressive and metastatic skin cancers. Although overexpression of Dock180 and Elmo1 has been identified in various cancers, including gli- oma, ovarian cancer, and breast cancer, their expression and functions in melanoma remain unknown. Objective: This study aims to confirm the expression of Dock180 and Elmo1, their underly- ing mechanisms, and roles in melanoma. Methods: Both immunohistochemical staining and Western blotting were used to confirm expression of Dock180 and Elmo1 in human melanoma. To identify roles of Dock180 and Elmo1 in cell survival, apoptosis and migration, downregulation of Dock180 or Elmo1 in melanoma cells with small interfering RNA (siRNA) was performed. Results: We identified overexpression of Dock180 and Elmo1 in human melanoma com- pared to normal skin ex vivo. Inhibition of Dock180 or Elmo1 following siRNA in melano- ma cells reduced cell viability and increased apoptosis as supported by increased proportion of cells with Annexin V-PE (+) staining and sub-G0/G1 peak in cell cycle analysis. Moreover, inhibition of Dock180 or Elmo1 regulated apoptosis-related proteins, showing downregula- tion of Bcl-2, caspase-3, and PARP and upregulation of Bax, PUMA, cleaved caspase-3, and cleaved PARP. Furthermore, knockdown of Dock180 and Elmo1 in melanoma cells reduced cell migration and changed cellular signaling pathways including ERK and AKT. Vemu- rafenib decreased cell viability in concentration-dependent manner, while transfection with Dock180- or Elmo1-specific siRNA in melanoma cells significantly reduced cell viability. Conclusion: Our results suggest that both Dock180 and Elmo1 may be associated with can- cer progression, and can be potential targets for treatment of melanoma.