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Caveolae contribute to the apoptosis resistance induced by the alpha(1A)-adrenoceptor in androgen-independent prostate cancer cells.

Katsogiannou M, El Boustany C, Gackiere F, Delcourt P, Athias A, Mariot P, Dewailly E, Jouy N, Lamaze C, Bidaux G, Mauroy B, Prevarskaya N, Slomianny C - PLoS ONE (2009)

Bottom Line: In addition, we showed that agonist stimulation of the alpha(1A)-adrenoceptor induced resistance to thapsigargin-induced apoptosis and that caveolin-1 was necessary for this process.We also show by immunoblotting that the TG-induced apoptosis resistance described in DU145 cells is mediated by extracellular signal-regulated kinases (ERK).In conclusion, we propose that alpha(1A)-adrenoceptor stimulation in androgen-independent prostate cancer cells via caveolae constitutes one of the mechanisms contributing to their protection from TG-induced apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Inserm U800, Université Lille 1 Sciences et Technologies, Villeneuve d'Ascq, France.

ABSTRACT

Background: During androgen ablation prostate cancer cells' growth and survival become independent of normal regulatory mechanisms. These androgen-independent cells acquire the remarkable ability to adapt to the surrounding microenvironment whose factors, such as neurotransmitters, influence their survival. Although findings are becoming evident about the expression of alpha(1A)-adrenoceptors in prostate cancer epithelial cells, their exact functional role in androgen-independent cells has yet to be established. Previous work has demonstrated that membrane lipid rafts associated with key signalling proteins mediate growth and survival signalling pathways in prostate cancer cells.

Methodology/principal findings: In order to analyze the membrane topology of the alpha(1A)-adrenoceptor we explored its presence by a biochemical approach in purified detergent resistant membrane fractions of the androgen-independent prostate cancer cell line DU145. Electron microscopy observations demonstrated the colocalization of the alpha(1A)-adrenoceptor with caveolin-1, the major protein component of caveolae. In addition, we showed that agonist stimulation of the alpha(1A)-adrenoceptor induced resistance to thapsigargin-induced apoptosis and that caveolin-1 was necessary for this process. Further, immunohistofluorescence revealed the relation between high levels of alpha(1A)-adrenoceptor and caveolin-1 expression with advanced stage prostate cancer. We also show by immunoblotting that the TG-induced apoptosis resistance described in DU145 cells is mediated by extracellular signal-regulated kinases (ERK).

Conclusions/significance: In conclusion, we propose that alpha(1A)-adrenoceptor stimulation in androgen-independent prostate cancer cells via caveolae constitutes one of the mechanisms contributing to their protection from TG-induced apoptosis.

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Cell surface modification and caveolin-1 mobilization following α1A-AR stimulation.(A) Representative electron micrograph of DU145 cells in (a) non-treated condition (b) after 10 min treatment by 10 µM PHE. Caveolae and caveolin containing vesicles of 50–80 nm diameter are dense in electrons are indicated by black arrowheads. White arrowheads indicate complex shaped caveolae. Bar, 500 nm. (B) Representative electron micrograph of plasma membrane “ripped-off” from (a) non-treated cells, (b) treated for 10 min with 10 µM PHE alone and (c) PHE in the presence of 1 µM PRA. 6 nm gold particles represent anti-α1A-AR labelling (black arrowheads) and 12 nm particles represent anti-cav-1 (white arrowheads). Bar, 200 nm. (d) The area of randomly selected negatives of electron micrographs (ten/condition) was measured at a magnification of 20000. The number of cav-1 and α1A-adrenoceptor-containing clusters (minimum 3 gold particles for each protein) was counted (mean ± SEM).
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pone-0007068-g003: Cell surface modification and caveolin-1 mobilization following α1A-AR stimulation.(A) Representative electron micrograph of DU145 cells in (a) non-treated condition (b) after 10 min treatment by 10 µM PHE. Caveolae and caveolin containing vesicles of 50–80 nm diameter are dense in electrons are indicated by black arrowheads. White arrowheads indicate complex shaped caveolae. Bar, 500 nm. (B) Representative electron micrograph of plasma membrane “ripped-off” from (a) non-treated cells, (b) treated for 10 min with 10 µM PHE alone and (c) PHE in the presence of 1 µM PRA. 6 nm gold particles represent anti-α1A-AR labelling (black arrowheads) and 12 nm particles represent anti-cav-1 (white arrowheads). Bar, 200 nm. (d) The area of randomly selected negatives of electron micrographs (ten/condition) was measured at a magnification of 20000. The number of cav-1 and α1A-adrenoceptor-containing clusters (minimum 3 gold particles for each protein) was counted (mean ± SEM).

Mentions: It is thought that upon extracellular stimulus, the plasma membrane is prepared for the formation of more stabilized domains and molecular clusters with enhanced size and lifetime such as caveolae [35], [36]. In order to understand the involvement of caveolae in the α1A-AR signalling, we explored the effect of PHE stimulation on the DU145 cell surface morphology (Figure 3A). Cells treated for 10 min with 10 µM PHE present numerous surface invaginations corresponding to caveolae (Figure 3A, b) as compared to non-treated cells (Figure 3A, a). Caveolae are evident as circular profiles with uniform shape and 50–80 nm diameter. In this representative electron micrograph caveolae are present as single pits (Figure 3A, b, black arrowheads) and sometimes in more complex arrangements interconnected with cytoplasmic caveolar profiles (Figure 3A, b, white arrowheads).


Caveolae contribute to the apoptosis resistance induced by the alpha(1A)-adrenoceptor in androgen-independent prostate cancer cells.

Katsogiannou M, El Boustany C, Gackiere F, Delcourt P, Athias A, Mariot P, Dewailly E, Jouy N, Lamaze C, Bidaux G, Mauroy B, Prevarskaya N, Slomianny C - PLoS ONE (2009)

Cell surface modification and caveolin-1 mobilization following α1A-AR stimulation.(A) Representative electron micrograph of DU145 cells in (a) non-treated condition (b) after 10 min treatment by 10 µM PHE. Caveolae and caveolin containing vesicles of 50–80 nm diameter are dense in electrons are indicated by black arrowheads. White arrowheads indicate complex shaped caveolae. Bar, 500 nm. (B) Representative electron micrograph of plasma membrane “ripped-off” from (a) non-treated cells, (b) treated for 10 min with 10 µM PHE alone and (c) PHE in the presence of 1 µM PRA. 6 nm gold particles represent anti-α1A-AR labelling (black arrowheads) and 12 nm particles represent anti-cav-1 (white arrowheads). Bar, 200 nm. (d) The area of randomly selected negatives of electron micrographs (ten/condition) was measured at a magnification of 20000. The number of cav-1 and α1A-adrenoceptor-containing clusters (minimum 3 gold particles for each protein) was counted (mean ± SEM).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2742726&req=5

pone-0007068-g003: Cell surface modification and caveolin-1 mobilization following α1A-AR stimulation.(A) Representative electron micrograph of DU145 cells in (a) non-treated condition (b) after 10 min treatment by 10 µM PHE. Caveolae and caveolin containing vesicles of 50–80 nm diameter are dense in electrons are indicated by black arrowheads. White arrowheads indicate complex shaped caveolae. Bar, 500 nm. (B) Representative electron micrograph of plasma membrane “ripped-off” from (a) non-treated cells, (b) treated for 10 min with 10 µM PHE alone and (c) PHE in the presence of 1 µM PRA. 6 nm gold particles represent anti-α1A-AR labelling (black arrowheads) and 12 nm particles represent anti-cav-1 (white arrowheads). Bar, 200 nm. (d) The area of randomly selected negatives of electron micrographs (ten/condition) was measured at a magnification of 20000. The number of cav-1 and α1A-adrenoceptor-containing clusters (minimum 3 gold particles for each protein) was counted (mean ± SEM).
Mentions: It is thought that upon extracellular stimulus, the plasma membrane is prepared for the formation of more stabilized domains and molecular clusters with enhanced size and lifetime such as caveolae [35], [36]. In order to understand the involvement of caveolae in the α1A-AR signalling, we explored the effect of PHE stimulation on the DU145 cell surface morphology (Figure 3A). Cells treated for 10 min with 10 µM PHE present numerous surface invaginations corresponding to caveolae (Figure 3A, b) as compared to non-treated cells (Figure 3A, a). Caveolae are evident as circular profiles with uniform shape and 50–80 nm diameter. In this representative electron micrograph caveolae are present as single pits (Figure 3A, b, black arrowheads) and sometimes in more complex arrangements interconnected with cytoplasmic caveolar profiles (Figure 3A, b, white arrowheads).

Bottom Line: In addition, we showed that agonist stimulation of the alpha(1A)-adrenoceptor induced resistance to thapsigargin-induced apoptosis and that caveolin-1 was necessary for this process.We also show by immunoblotting that the TG-induced apoptosis resistance described in DU145 cells is mediated by extracellular signal-regulated kinases (ERK).In conclusion, we propose that alpha(1A)-adrenoceptor stimulation in androgen-independent prostate cancer cells via caveolae constitutes one of the mechanisms contributing to their protection from TG-induced apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Inserm U800, Université Lille 1 Sciences et Technologies, Villeneuve d'Ascq, France.

ABSTRACT

Background: During androgen ablation prostate cancer cells' growth and survival become independent of normal regulatory mechanisms. These androgen-independent cells acquire the remarkable ability to adapt to the surrounding microenvironment whose factors, such as neurotransmitters, influence their survival. Although findings are becoming evident about the expression of alpha(1A)-adrenoceptors in prostate cancer epithelial cells, their exact functional role in androgen-independent cells has yet to be established. Previous work has demonstrated that membrane lipid rafts associated with key signalling proteins mediate growth and survival signalling pathways in prostate cancer cells.

Methodology/principal findings: In order to analyze the membrane topology of the alpha(1A)-adrenoceptor we explored its presence by a biochemical approach in purified detergent resistant membrane fractions of the androgen-independent prostate cancer cell line DU145. Electron microscopy observations demonstrated the colocalization of the alpha(1A)-adrenoceptor with caveolin-1, the major protein component of caveolae. In addition, we showed that agonist stimulation of the alpha(1A)-adrenoceptor induced resistance to thapsigargin-induced apoptosis and that caveolin-1 was necessary for this process. Further, immunohistofluorescence revealed the relation between high levels of alpha(1A)-adrenoceptor and caveolin-1 expression with advanced stage prostate cancer. We also show by immunoblotting that the TG-induced apoptosis resistance described in DU145 cells is mediated by extracellular signal-regulated kinases (ERK).

Conclusions/significance: In conclusion, we propose that alpha(1A)-adrenoceptor stimulation in androgen-independent prostate cancer cells via caveolae constitutes one of the mechanisms contributing to their protection from TG-induced apoptosis.

Show MeSH
Related in: MedlinePlus