Overexpression of Dock180 and Elmo1 in melanoma is associated with cell survival and migration

Abstract Melanoma is one of the most aggressive and metastatic skin cancers, of these metastatic melanoma is a lethal disease with invasive behavior. Although overexpression of Dock180 and Elmo1 has been identified in various cancers, including glioma, ovarian cancer, hepatocellular carcinoma, and breast cancer, the expression and functions of them in melanoma remain unknown. Therefore, the purpose of this study is to confirm the expression of Dock180 and Elmo1, their underlying mechanisms, and roles in melanoma. Both immunohistochemical staining and Western blotting were used to confirm expression of Dock180 and Elmo1 in human melanoma and normal skin. To identify roles of Dock180 and Elmo1 in cell survival, apoptosis and migration, downregulation of Dock180 or Elmo1 in melanoma cells treated with siRNA was performed in Cell viability assay, Phase contrast images, DAPI staining, Cell cycle analysis, Apoptosis assay, Wound healing assay, Colony formation assay, and Western blotting. We identified overexpression of Dock180 and Elmo1 in human melanoma compared to normal skin ex vivo. Inhibition of Dock180 or Elmo1 following siRNA treatment in melanoma 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 downregulaton of Bcl-2, caspase-3, and PARP and upregulation of Bax, PUMA, cleaved caspase3, and cleaved PARP. Furthermore, knockdown of Dock180 and Elmo1 in melanoma cells reduced cell migration and changed cellular signaling pathways including ERK and AKT. Vemurafenib treatment decreased cell viability in a concentration-dependent manner, while transfection with Dock180- or Elmo1-specific siRNA in melanoma cells significantly reduced cell viability compared to non-transfected cells. Collectively, these findings suggest that both Dock180 and Elmo1 may be associated with cancer progression such as cell survival and migration in melanoma, and can be potential targets for treatment of melanoma.