Cancer-associated missense mutations of caspase-8 activate nuclear factor-κB signaling

Cancer Sci. 2013 Aug;104(8):1002-8. doi: 10.1111/cas.12191. Epub 2013 Jun 7.


Head and neck squamous cell carcinoma (HNSCC) is an aggressive cancer with a 5-year survival rate of ~50%. With the use of a custom cDNA-capture system coupled with massively parallel sequencing, we have now investigated transforming mechanisms for this malignancy. The cDNAs of cancer-related genes (n = 906) were purified from a human HNSCC cell line (T3M-1 Cl-10) and subjected to high-throughput resequencing, and the clinical relevance of non-synonymous mutations thus identified was evaluated with luciferase-based reporter assays. A CASP8 (procaspase-8) cDNA with a novel G-to-C point mutation that results in the substitution of alanine for glycine at codon 325 was identified, and the mutant protein, CASP8 (G325A), was found to activate nuclear factor-κB (NF-κB) signaling to an extent far greater than that achieved with the wild-type protein. Moreover, forced expression of wild-type CASP8 suppressed the growth of T3M-1 Cl-10 cells without notable effects on apoptosis. We further found that most CASP8 mutations previously detected in various epithelial tumors also increase the ability of the protein to activate NF-κB signaling. Such NF-κB activation was shown to be mediated through the COOH-terminal region of the second death effector domain of CASP8. Although CASP8 mutations associated with cancer have been thought to promote tumorigenesis as a result of attenuation of the proapoptotic function of the protein, our results now show that most such mutations, including the novel G325A identified here, separately confer a gain of function with regard to activation of NF-κB signaling, indicating another role of CASP8 in the transformation of human malignancies including HNSCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics
  • Carcinogenesis / genetics
  • Carcinogenesis / metabolism
  • Carcinoma, Squamous Cell / enzymology
  • Carcinoma, Squamous Cell / genetics*
  • Carcinoma, Squamous Cell / metabolism
  • Carcinoma, Squamous Cell / pathology
  • Caspase 8 / genetics*
  • Caspase 8 / metabolism
  • Cell Line, Tumor
  • HEK293 Cells
  • Head and Neck Neoplasms / enzymology
  • Head and Neck Neoplasms / genetics*
  • Head and Neck Neoplasms / metabolism
  • Head and Neck Neoplasms / pathology
  • Humans
  • Mutation, Missense*
  • NF-kappa B / metabolism*
  • Signal Transduction
  • Squamous Cell Carcinoma of Head and Neck


  • NF-kappa B
  • CASP8 protein, human
  • Caspase 8