alpha6beta4 integrin activates Rac-dependent p21-activated kinase 1 to drive NF-kappaB-dependent resistance to apoptosis in 3D mammary acini.

Titlealpha6beta4 integrin activates Rac-dependent p21-activated kinase 1 to drive NF-kappaB-dependent resistance to apoptosis in 3D mammary acini.
Publication TypeJournal Article
Year of Publication2007
AuthorsFriedland JC, Lakins JN, Kazanietz MG, Chernoff J, Boettiger D, Weaver VM
JournalJ Cell Sci
Volume120
IssuePt 20
Pagination3700-12
Date Published2007 Oct 15
ISSN0021-9533
KeywordsApoptosis, Enzyme Activation, Humans, Integrin alpha6beta4, Mammary Glands, Human, p21-Activated Kinases, Proto-Oncogene Proteins c-akt, rac GTP-Binding Proteins, Transcription Factor RelA
Abstract

Malignant transformation and multidrug resistance are linked to resistance to apoptosis, yet the molecular mechanisms that mediate tumor survival remain poorly understood. Because the stroma can influence tumor behavior by regulating the tissue phenotype, we explored the role of extracellular matrix signaling and tissue organization in epithelial survival. We report that elevated (alpha6)beta4 integrin-dependent Rac-Pak1 signaling supports resistance to apoptosis in mammary acini by permitting stress-dependent activation of the p65 subunit of NF-kappaB through Pak1. We found that inhibiting Pak1 through expression of N17Rac or PID compromises NF-kappaB activation and renders mammary acini sensitive to death, but that resistance to apoptosis could be restored to these structures by overexpressing wild-type NF-kappaB p65. We also observed that acini expressing elevated levels of Pak1 can activate p65 and survive death treatments, even in the absence of activated Rac, yet will die if activation of NF-kappaB is simultaneously inhibited through expression of IkappaBalphaM. Thus, mammary tissues can resist apoptotic stimuli by activating NF-kappaB through alpha6beta4 integrin-dependent Rac-Pak1 signaling. Our data emphasize the importance of the extracellular matrix stroma in tissue survival and suggest that alpha6beta4 integrin-dependent Rac stimulation of Pak1 could be an important mechanism mediating apoptosis-resistance in some breast tumors.

DOI10.1242/jcs.03484
Alternate JournalJ. Cell. Sci.
PubMed ID17911169
Grant ListCA 117884 / CA / NCI NIH HHS / United States
CA078731 / CA / NCI NIH HHS / United States
GM-57388 / GM / NIGMS NIH HHS / United States