Par6 is an essential mediator of apoptotic response to transforming growth factor beta in NMuMG immortalized mammary cells

Hdl Handle:
http://hdl.handle.net/10147/314187
Title:
Par6 is an essential mediator of apoptotic response to transforming growth factor beta in NMuMG immortalized mammary cells
Authors:
Avery-Cooper, Geordon; Doerr, Meghan; Gilbert, Richard WD; Youssef, Mahmoud; Richard, Amy; Huether, Patricia; Viloria-Petit, Alicia M
Citation:
Cancer Cell International. 2014 Mar 01;14(1):19
Issue Date:
1-Mar-2014
URI:
http://dx.doi.org/10.1186/1475-2867-14-19; http://hdl.handle.net/10147/314187
Abstract:
Abstract Background We previously observed that the TGFbeta-Par6 pathway mediates loss of polarity and apoptosis in NMuMG cells. Here we investigate the contribution of Par6 versus TGFbeta receptor I activation to TGFbeta-induced apoptosis in association with changes in apico-basal polarity. We focus on the effect of Par6 activation on alpha6beta4 integrin expression and localization, and Nuclear Factor-kappaB (p65/RelA) activation, previously shown to mediate polarity-dependent cell survival. Methods Using immunoblotting and/or immunofluorescence we investigated the effect of TGFbeta1 on apoptosis, alpha6, beta4 and beta1 integrin expression/localization, and p65/RelA phosphorylation/localization in monolayer and three-dimensional (3D) cultures of NMuMG cells with an overactive or inactive Par6 pathway. Results were quantified by band densitometry or as percent of 3D structures displaying a phenotype. Differences among means were compared by two-way ANOVA. Results Blocking Par6 activation inhibits TGFbeta-induced apoptosis. Par6 overactivation enhances TGFbeta-induced apoptosis, notably after 6-day exposure to TGFbeta (p < 0.001), a time when parental NMuMG cells no longer respond to TGFbeta apoptotic stimuli. 48-hour TGFbeta treatment reduced beta4 integrin levels in NMuMG monolayers and significantly reduced the basal localization of alpha6 (p < 0.001) and beta4 (p < 0.001) integrin in NMuMG 3D structures, which was dependent on both Par6 and TGFbeta receptor I activation and paralleled apoptotic response. After 6-day exposure to TGFbeta, Par6-dependent changes to beta4 integrin were no longer apparent, but there was reduced phosphorylation of p65/RelA (p < 0.001) only in Par6 overexpressing cells. Differences in p65/RelA localization were not observed among the different cell lines after 48-hour TGFbeta exposure. Conclusions Par6 and TGFbeta receptor I activation are both necessary for TGFbeta-induced apoptosis in NMuMG cells. Importantly, Par6 overexpression enhances the sensitivity of NMuMG to TGFbeta-induced apoptosis, notably upon prolonged exposure to this growth factor, when NMuMG parental cells are usually apoptosis-resistant. Thus, endogenous Par6 level might be important in determining whether TGFbeta will function as either a pro-apoptotic or pro-survival factor in breast cancer, and potentially aid in predicting patient’s prognosis and therapy response.
Language:
en
Keywords:
BREAST CANCER
Local subject classification:
CELL BIOLOGY

Full metadata record

DC FieldValue Language
dc.contributor.authorAvery-Cooper, Geordonen_GB
dc.contributor.authorDoerr, Meghanen_GB
dc.contributor.authorGilbert, Richard WDen_GB
dc.contributor.authorYoussef, Mahmouden_GB
dc.contributor.authorRichard, Amyen_GB
dc.contributor.authorHuether, Patriciaen_GB
dc.contributor.authorViloria-Petit, Alicia Men_GB
dc.date.accessioned2014-03-18T13:11:15Z-
dc.date.available2014-03-18T13:11:15Z-
dc.date.issued2014-03-01-
dc.identifier.citationCancer Cell International. 2014 Mar 01;14(1):19en_GB
dc.identifier.urihttp://dx.doi.org/10.1186/1475-2867-14-19-
dc.identifier.urihttp://hdl.handle.net/10147/314187-
dc.description.abstractAbstract Background We previously observed that the TGFbeta-Par6 pathway mediates loss of polarity and apoptosis in NMuMG cells. Here we investigate the contribution of Par6 versus TGFbeta receptor I activation to TGFbeta-induced apoptosis in association with changes in apico-basal polarity. We focus on the effect of Par6 activation on alpha6beta4 integrin expression and localization, and Nuclear Factor-kappaB (p65/RelA) activation, previously shown to mediate polarity-dependent cell survival. Methods Using immunoblotting and/or immunofluorescence we investigated the effect of TGFbeta1 on apoptosis, alpha6, beta4 and beta1 integrin expression/localization, and p65/RelA phosphorylation/localization in monolayer and three-dimensional (3D) cultures of NMuMG cells with an overactive or inactive Par6 pathway. Results were quantified by band densitometry or as percent of 3D structures displaying a phenotype. Differences among means were compared by two-way ANOVA. Results Blocking Par6 activation inhibits TGFbeta-induced apoptosis. Par6 overactivation enhances TGFbeta-induced apoptosis, notably after 6-day exposure to TGFbeta (p < 0.001), a time when parental NMuMG cells no longer respond to TGFbeta apoptotic stimuli. 48-hour TGFbeta treatment reduced beta4 integrin levels in NMuMG monolayers and significantly reduced the basal localization of alpha6 (p < 0.001) and beta4 (p < 0.001) integrin in NMuMG 3D structures, which was dependent on both Par6 and TGFbeta receptor I activation and paralleled apoptotic response. After 6-day exposure to TGFbeta, Par6-dependent changes to beta4 integrin were no longer apparent, but there was reduced phosphorylation of p65/RelA (p < 0.001) only in Par6 overexpressing cells. Differences in p65/RelA localization were not observed among the different cell lines after 48-hour TGFbeta exposure. Conclusions Par6 and TGFbeta receptor I activation are both necessary for TGFbeta-induced apoptosis in NMuMG cells. Importantly, Par6 overexpression enhances the sensitivity of NMuMG to TGFbeta-induced apoptosis, notably upon prolonged exposure to this growth factor, when NMuMG parental cells are usually apoptosis-resistant. Thus, endogenous Par6 level might be important in determining whether TGFbeta will function as either a pro-apoptotic or pro-survival factor in breast cancer, and potentially aid in predicting patient’s prognosis and therapy response.-
dc.language.isoenen
dc.subjectBREAST CANCERen_GB
dc.subject.otherCELL BIOLOGYen_GB
dc.titlePar6 is an essential mediator of apoptotic response to transforming growth factor beta in NMuMG immortalized mammary cellsen_GB
dc.language.rfc3066en-
dc.rights.holderGeordon Avery-Cooper et al.; licensee BioMed Central Ltd.-
dc.description.statusPeer Reviewed-
dc.date.updated2014-03-07T09:17:42Z-
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