MAPK and Hippo signaling pathways crosstalk via the RAF-1/MST-2 interaction in malignant melanoma

Ruizheng Feng, Junsheng Gong, Lina Wu, Lei Wang, Baolin Zhang, Gang Liang, Huixia Zheng, Hong Xiao
2017 Oncology Reports  
The aim of the present study was to expound on the interactions between the mitogen-activated protein kinase (MAPK) and Hippo pathway members, and to further elucidate the molecular mechanisms of melanoma tumorigenesis. Four melanoma cell lines (C32, HS695T, SK-MEL-28 and A375) were used in the present study. Western blotting was used to assess the expression levels of the MAPK and Hippo pathway effector proteins: rapidly accelerated fibrosarcoma-1 proto-oncogene, serine/threonine kinase
more » ... ; serine/threonine kinase 3 (STK3; also known as MST-2); yes-associated protein (YAP); and tafazzin (TAZ). Immunoprecipitation was used to identify interactions between the effector proteins of the Hippo and MAPK pathways. RAF-1 was knocked down in melanoma cells using siRNA transfection, and cell proliferation, migration and invasion were determined by the MTT, wound-healing and Transwell invasion assays, respectively. Additionally, the cell cycle and apoptosis were analyzed by flow cytometry 48 h after RAF-1 knockdown. We found that the expression levels of the four proteins were variable, and that the HS695T cells expressed the highest levels of RAF-1. Immunoprecipitation studies revealed that RAF-1 bound to MST-2 in melanoma cells. Knockdown of RAF-1 inhibited the expression of YAP and TAZ, but did not affect MST-2 expression. Additionally, RAF-1 knockdown in melanoma cells significantly inhibited cell proliferation, migration and invasion, and induced apoptosis in these cells. Collectively, our results indicate that the RAF-1/MST-2 interaction may be a novel link between the MAPK and Hippo pathways.
doi:10.3892/or.2017.5774 pmid:28677804 fatcat:eiophg42wre47ixur4kinb4zkm