BRAF-induced tumorigenesis is IKKalpha dependent but NF?B independent

ABSTRACT: Tumor cells carrying KRAS mutations activate the NF-?B pathway by different mechanisms, which contribute to the acquisition of essential cancer properties. The BRAF kinase, a downstream mediator of KRAS, is also mutated in a subset of colorectal cancers (CRC), which predicts bad prognosis and therapy resistance. However, nothing is known on whether NF-?B participates of BRAF-mediated tumorigenesis. We here found that in CRC cells, mutant BRAF does not trigger canonical or alternative NF-?B signaling but induces p45-IKK? activation. Moreover, IKK? activity is required for BRAF-induced transformation and to support BRAF-dependent transcription in CRC cells. Activation of p45-IKK? downstream of BRAF requires the TAK1 kinase, and is associated to the endosomal compartment. Inhibition of endosomal V-ATPase abolished p45-IKK? phosphorylation, and induced apoptosis of BRAF mutated CRC cells. Pharmacologic inhibition of endosome acidification reduced the in vivo growth of tumors carrying mutant BRAF, and abrogated the metastatic capacity of a primary human CRC tumor with acquired resistance to standard chemotherapy in an orthotopic xenograft model. 18 samples were analyzed: HT29 controls (n=3); HT28 BRAF inhibited (n=3), WiDr controls (n=3); WiDr BRAF inhibited (n=3); WiDr transduced with control shRNA (n=3) and WiDr transduced with shRNA against IKKalpha (n=3)

ORGANISM(S): Homo sapiens

SUBMITTER: Lara Nonell 

PROVIDER: E-GEOD-57979 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress