Melanoma is the deadliest form of skin cancer, and little is known about the impact of deregulated expression of long noncoding RNAs (lncRNAs) in the progression of this cancer.,In this study, we explored RNA-Seq data to search for lncRNAs associated with melanoma progression.,We found distinct lncRNA gene expression patterns across melanocytes, primary and metastatic melanoma cells.,Also, we observed upregulation of the lncRNA ZEB1-AS1 (ZEB1 antisense RNA 1) in melanoma cell lines.,Data analysis from The Cancer Genome Atlas (TCGA) confirmed higher ZEB1-AS1 expression in metastatic melanoma and its association with hotspot mutations in BRAF (B-Raf proto-oncogene, serine/threonine kinase) gene and RAS family genes.,In addition, a positive correlation between ZEB1-AS1 and ZEB1 (zinc finger E-box binding homeobox 1) gene expression was verified in primary and metastatic melanomas.,Using gene expression signatures indicative of invasive or proliferative phenotypes, we found an association between ZEB1-AS1 upregulation and a transcriptional profile for invasiveness.,Enrichment analysis of correlated genes demonstrated cancer genes and pathways associated with ZEB1-AS1.,We suggest that the lncRNA ZEB1-AS1 could function by activating ZEB1 gene expression, thereby influencing invasiveness and phenotype switching in melanoma, an epithelial-to-mesenchymal transition (EMT)-like process, which the ZEB1 gene has an essential role.
Combined inhibition of BRAF and MEK1/2 (CIBM) improves therapeutic efficacy of BRAF-mutant melanoma.,However, drug resistance to CIBM is inevitable and the drug resistance mechanisms still remain to be elucidated.,Here, we show that BMK1 pathway contributes to the drug resistance to CIBM.,Considering that ERK1/2 pathway regulates cellular processes by phosphorylating, we first performed a SILAC phosphoproteomic profiling of CIBM.,Phosphorylation of 239 proteins was identified to be downregulated, while phosphorylation of 47 proteins was upregulated.,Following siRNA screening of 47 upregulated proteins indicated that the knockdown of BMK1 showed the most significant ability to inhibit the proliferation of CIBM resistant cells.,It was found that phosphorylation of BMK1 was enhanced in resistant cells, which suggested an association of BMK1 with drug resistance.,Further study indicated that phospho-activation of BMK1 by MEK5D enhanced the resistance to CIBM.,Conversely, inhibition of BMK1 by shRNAi or BMK1 inhibitor (XMD8-92) impaired not only the acquirement of resistance to CIBM, but also the proliferation of CIBM resistant cells.,Further kinome-scale siRNA screening demonstrated that SRC\MEK5 cascade promotes the phospho-activation of BMK1 in response to CIBM.,Our study not only provides a global phosphoproteomic view of CIBM in melanoma, but also demonstrates that inhibition of BMK1 has therapeutic potential for the treatment of melanoma.