Sema6A and Mical1 control cell growth and survival of BRAFV600E human melanoma cells

Oncotarget. 2015 Feb 20;6(5):2779-93. doi: 10.18632/oncotarget.2995.

Abstract

We used whole genome microarray analysis to identify potential candidate genes with differential expression in BRAFV600E vs NRASQ61R melanoma cells. We selected, for comparison, a peculiar model based on melanoma clones, isolated from a single tumor characterized by mutually exclusive expression of BRAFV600E and NRASQ61R in different cells. This effort led us to identify two genes, SEMA6A and MICAL1, highly expressed in BRAF-mutant vs NRAS-mutant clones. Real-time PCR, Western blot and immunohistochemistry confirmed preferential expression of Sema6A and Mical1 in BRAFV600E melanoma. Sema6A is a member of the semaphorin family, and it complexes with the plexins to regulate actin cytoskeleton, motility and cell proliferation. Silencing of Sema6A in BRAF-mutant cells caused cytoskeletal remodeling, and loss of stress fibers, that in turn induced cell death. Furthermore, Sema6A depletion caused loss of anchorage-independent growth, inhibition of chemotaxis and invasion. Forced Sema6A overexpression, in NRASQ61R clones, induced anchorage-independent growth, and a significant increase of invasiveness. Mical1, that links Sema/PlexinA signaling, is also a negative regulator of apoptosis. Indeed, Mical-1 depletion in BRAF mutant cells restored MST-1-dependent NDR phosphorylation and promoted a rapid and massive NDR-dependent apoptosis. Overall, our data suggest that Sema6A and Mical1 may represent new potential therapeutic targets in BRAFV600E melanoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apoptosis
  • Blotting, Western
  • Cell Adhesion
  • Cell Line, Tumor
  • Cell Movement
  • Cell Proliferation*
  • Cell Survival
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Gene Expression Profiling / methods
  • Gene Expression Regulation, Neoplastic
  • Genetic Association Studies
  • Humans
  • Immunohistochemistry
  • LIM Domain Proteins / genetics
  • LIM Domain Proteins / metabolism*
  • Male
  • Melanoma / enzymology*
  • Melanoma / genetics
  • Melanoma / pathology
  • Mice, Nude
  • Microfilament Proteins
  • Mixed Function Oxygenases
  • Mutation*
  • Neoplasm Invasiveness
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Oligonucleotide Array Sequence Analysis
  • Phosphorylation
  • Proto-Oncogene Proteins B-raf / genetics*
  • RNA Interference
  • Real-Time Polymerase Chain Reaction
  • Semaphorins / genetics
  • Semaphorins / metabolism*
  • Signal Transduction
  • Skin Neoplasms / enzymology*
  • Skin Neoplasms / genetics
  • Skin Neoplasms / pathology
  • Transfection

Substances

  • Adaptor Proteins, Signal Transducing
  • Cytoskeletal Proteins
  • HEMGN protein, human
  • LIM Domain Proteins
  • Microfilament Proteins
  • Nuclear Proteins
  • SEMA6A protein, human
  • Semaphorins
  • MICAL1 protein, human
  • Mixed Function Oxygenases
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf