RAS mutations affect tumor necrosis factor-induced apoptosis in colon carcinoma cells via ERK-modulatory negative and positive feedback circuits along with non-ERK pathway effects

Cancer Res. 2009 Oct 15;69(20):8191-9. doi: 10.1158/0008-5472.CAN-09-1921. Epub 2009 Sep 29.


More than 40% of colon cancers have a mutation in K-RAS or N-RAS, GTPases that operate as central hubs for multiple key signaling pathways within the cell. Utilizing an isogenic panel of colon carcinoma cells with K-RAS or N-RAS variations, we observed differences in tumor necrosis factor-alpha (TNFalpha)-induced apoptosis. When the dynamics of phosphorylated ERK response to TNFalpha were examined, K-RAS mutant cells showed lower activation whereas N-RAS mutant cells exhibited prolonged duration. These divergent trends were partially explained by differential induction of two ERK-modulatory circuits: negative feedback mediated by dual-specificity phosphatase 5 and positive feedback by autocrine transforming growth factor-alpha. Moreover, in the various RAS mutant colon carcinoma lines, the transforming growth factor-alpha autocrine loop differentially elicited a further downstream chemokine (CXCL1/CXCL8) autocrine loop, with the two loops having opposite effects on apoptosis. Although the apoptotic responses of the RAS mutant panel to TNFalpha treatment showed significant dependence on the respective phosphorylated ERK dynamics, successful prediction across the various cell lines required contextual information concerning additional pathways including IKK and p38. A quantitative computational model based on weighted linear combinations of these pathway activities successfully predicted not only the spectrum of cell death responses but also the corresponding chemokine production responses. Our findings indicate that diverse RAS mutations yield differential cell behavioral responses to inflammatory cytokine exposure by means of (a) differential effects on ERK activity via multiple feedback circuit mechanisms, and (b) differential effects on other key signaling pathways contextually modulating ERK-related dependence.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / genetics*
  • Autocrine Communication
  • Blotting, Western
  • Chemokines
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology*
  • Computational Biology
  • Dual-Specificity Phosphatases / genetics
  • Dual-Specificity Phosphatases / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Feedback, Physiological*
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Genes, ras / genetics*
  • Humans
  • Mutation / genetics*
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins p21(ras)
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor-alpha / pharmacology*
  • ras Proteins / genetics*


  • Chemokines
  • KRAS protein, human
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Transforming Growth Factor beta
  • Tumor Necrosis Factor-alpha
  • Extracellular Signal-Regulated MAP Kinases
  • DUSP5 protein, human
  • Dual-Specificity Phosphatases
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins