The Prognostic Significance of Low-Frequency Somatic Mutations in Metastatic Cutaneous Melanoma

Autor: Xiaobei Zhao, Paul Little, Alan P. Hoyle, Guillaume J. Pegna, Michele C. Hayward, Anastasia Ivanova, Joel S. Parker, David L. Marron, Matthew G. Soloway, Heejoon Jo, Ashley H. Salazar, Michael P. Papakonstantinou, Deeanna M. Bouchard, Stuart R. Jefferys, Katherine A. Hoadley, David W. Ollila, Jill S. Frank, Nancy E. Thomas, Paul B. Googe, Ashley J. Ezzell, Frances A. Collichio, Carrie B. Lee, H. Shelton Earp, Norman E. Sharpless, Willy Hugo, James S. Wilmott, Camelia Quek, Nicola Waddell, Peter A. Johansson, John F. Thompson, Nicholas K. Hayward, Graham J. Mann, Roger S. Lo, Douglas B. Johnson, Richard A. Scolyer, D. Neil Hayes, Stergios J. Moschos
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Frontiers in Oncology, Vol 8 (2019)
Druh dokumentu: article
ISSN: 2234-943X
DOI: 10.3389/fonc.2018.00584
Popis: Background: Little is known about the prognostic significance of somatically mutated genes in metastatic melanoma (MM). We have employed a combined clinical and bioinformatics approach on tumor samples from cutaneous melanoma (SKCM) as part of The Cancer Genome Atlas project (TCGA) to identify mutated genes with potential clinical relevance.Methods: After limiting our DNA sequencing analysis to MM samples (n = 356) and to the CANCER CENSUS gene list, we filtered out mutations with low functional significance (snpEFF). We performed Cox analysis on 53 genes that were mutated in ≥3% of samples, and had ≥50% difference in incidence of mutations in deceased subjects versus alive subjects.Results: Four genes were potentially prognostic [RAC1, FGFR1, CARD11, CIITA; false discovery rate (FDR) < 0.2]. We identified 18 additional genes (e.g., SPEN, PDGFRB, GNAS, MAP2K1, EGFR, TSC2) that were less likely to have prognostic value (FDR < 0.4). Most somatic mutations in these 22 genes were infrequent (< 10%), associated with high somatic mutation burden, and were evenly distributed across all exons, except for RAC1 and MAP2K1. Mutations in only 9 of these 22 genes were also identified by RNA sequencing in >75% of the samples that exhibited corresponding DNA mutations. The low frequency, UV signature type and RNA expression of the 22 genes in MM samples were confirmed in a separate multi-institution validation cohort (n = 413). An underpowered analysis within a subset of this validation cohort with available patient follow-up (n = 224) showed that somatic mutations in SPEN and RAC1 reached borderline prognostic significance [log-rank favorable (p = 0.09) and adverse (p = 0.07), respectively]. Somatic mutations in SPEN, and to a lesser extent RAC1, were not associated with definite gene copy number or RNA expression alterations. High (>2+) nuclear plus cytoplasmic expression intensity for SPEN was associated with longer melanoma-specific overall survival (OS) compared to lower (≤ 2+) nuclear intensity (p = 0.048). We conclude that expressed somatic mutations in infrequently mutated genes beyond the well-characterized ones (e.g., BRAF, RAS, CDKN2A, PTEN, TP53), such as RAC1 and SPEN, may have prognostic significance in MM.
Databáze: Directory of Open Access Journals