TRAF6 is an amplified oncogene bridging the RAS and NF-κB pathways in human lung cancer
Daniel T. Starczynowski, … , Wan L. Lam, Aly Karsan
Daniel T. Starczynowski, … , Wan L. Lam, Aly Karsan
Published September 12, 2011
Citation Information: J Clin Invest. 2011;121(10):4095-4105. https://doi.org/10.1172/JCI58818.
View: Text | PDF
Research Article Oncology

TRAF6 is an amplified oncogene bridging the RAS and NF-κB pathways in human lung cancer

Abstract

Somatic mutations and copy number alterations (as a result of deletion or amplification of large portions of a chromosome) are major drivers of human lung cancers. Detailed analysis of lung cancer–associated chromosomal amplifications could identify novel oncogenes. By performing an integrative cytogenetic and gene expression analysis of non–small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC) cell lines and tumors, we report here the identification of a frequently recurring amplification at chromosome 11 band p13. Within this region, only TNF receptor–associated factor 6 (TRAF6) exhibited concomitant mRNA overexpression and gene amplification in lung cancers. Inhibition of TRAF6 in human lung cancer cell lines suppressed NF-κB activation, anchorage-independent growth, and tumor formation. In these lung cancer cell lines, RAS required TRAF6 for its oncogenic capabilities. Furthermore, TRAF6 overexpression in NIH3T3 cells resulted in NF-κB activation, anchorage-independent growth, and tumor formation. Our findings show that TRAF6 is an oncogene that is important for RAS-mediated oncogenesis and provide a mechanistic explanation for the previously apparent importance of constitutive NF-κB activation in RAS-driven lung cancers.

Authors

Daniel T. Starczynowski, William W. Lockwood, Sophie Deléhouzée, Raj Chari, Joanna Wegrzyn, Megan Fuller, Ming-Sound Tsao, Stephen Lam, Adi F. Gazdar, Wan L. Lam, Aly Karsan

×

Figure 2

TRAF6 overexpression causes malignant phenotype.

Options: View larger image (or click on image) Download as PowerPoint
TRAF6 overexpression causes malignant phenotype. (A–C) NIH3T3 cells tran...
(A–C) NIH3T3 cells transduced with vector (MSCVpac) or FLAG-tagged TRAF6 were selected in puromycin and assessed (A) for growth in 2% serum by BrdU incorporation and (B) for colony formation in 0.3% soft agar (1 × 104 cells plated). (C) Morphology of vector- and TRAF6-expressing NIH3T3 cells is shown in agar and in liquid culture. Original magnification, ×20 (agar); ×40 (liquid). (D) NIH3T3 cells transduced with vector or TRAF6 were subcutaneously injected (2.5 × 105 cells/flank) into NOD/SCID mice and assessed for tumor formation by measuring tumor volume. (E) Individual colonies formed by TRAF6-expressing NIH3T3 cells were extracted from soft agar, expanded in liquid culture, and reanalyzed for soft agar colony formation. Representative cells are shown. Original magnification, ×20 (agar); ×40 (liquid). (F) 3 TRAF6 clones (C1–C3), along with 2 independently created parental TRAF6 cells and vector-expressing cells, were evaluated for FLAG-TRAF6 expression by IB (anti-FLAG). Densitometric values for FLAG-TRAF6 protein relative to actin are shown below. (G) Colony-forming frequency (no. colonies/1 × 103 cells plated) is shown relative to expression of FLAG-TRAF6 for TRAF6 clones (n = 3) and parental TRAF6 cells (n = 2). (H and I) NIH3T3 cells transduced with vector, TRAF6, vH-RAS, or TRAF6 clone C1 were subcutaneously injected (2.5 × 105 cells/flank) into NOD/SCID mice and assessed for tumor formation by measuring (H) tumor mass at day 15 and (I) tumor volume. *P < 0.05.