title: Suppression of oncogenic NRAS by RNA interference induces apoptosis of human melanoma cells.
abstract: The majority of human melanomas harbor activating mutations in either the BRAF or NRAS gene. To date, the role of oncogenic NRAS in melanoma remains poorly defined and no current therapies are directed at specifically suppressing oncogenic NRAS in human melanoma tumors. The aim of our study, therefore, was to investigate the effects of suppressing oncogenic NRAS in human melanoma cell lines in vitro. Using both small interfering RNA- and plasmid based-RNA interference techniques, oncogenic NRAS was specifically suppressed in 2 human melanoma cell lines, 224 and BL, which harbor a codon 61 CAA (glutamine) to CGA (arginine) NRAS mutation. Suppression of oncogenic NRAS in these cell lines resulted in increased apoptosis. Furthermore, in 224 cells we demonstrated decreased phosphorylation of extracellular signal-regulated kinase (ERK) and Akt, and reduced expression of NF-kappaB and cyclin D1 in the N-Ras signaling pathway. In contrast, RNA interference directed at wild-type (WT) NRAS had no significant effect on apoptosis of 224 cells or 2 human melanoma cell lines (A375 and 397) containing WT NRAS but a codon 600 GTG (valine) to GAG (glutamate) mutation in BRAF. These data suggest that oncogenic NRAS is important for avoidance of apoptosis in melanomas that harbor the codon 61 NRAS mutation and emphasizes oncogenic NRAS as a therapeutic target in patients with tumors that harbor this mutation.
authors.affiliation: Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska University Hospital Solna and Karolinska Institute, Stockholm, Sweden.
authors.forename: Malihe
authors.initials: M
authors.lastname: Eskandarpour
authors.forename: Shahryar
authors.initials: S
authors.lastname: Kiaii
authors.forename: Chaoyong
authors.initials: C
authors.lastname: Zhu
authors.forename: Juan
authors.initials: J
authors.lastname: Castro
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sakko
authors.forename: Johan
authors.initials: J
authors.lastname: Hansson
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003062:Codon; D004396:Coloring Agents / Q000494:pharmacology; D019938:Cyclin D1 / Q000378:metabolism; D015536:Down-Regulation; D004996:Ethidium / Q000494:pharmacology; D011905:Genes, ras / Q000235:genetics*; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D020287:In Situ Nick-End Labeling; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D008856:Microscopy, Fluorescence; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
chemical_list: D003062:Codon; D004396:Coloring Agents; D034741:RNA, Small Interfering; D019938:Cyclin D1; D048052:Mitogen-Activated Protein Kinase 3; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D004996:Ethidium