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Caveolin-1 limits the contribution of BKCa channel to MCF-7 breast cancer cell proliferation and invasion.

Du C, Chen L, Zhang H, Wang Z, Liu W, Xie X, Xie M - Int J Mol Sci (2014)

Bottom Line: These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility.These effects were attenuated in the presence of BKCa-siRNA.Similarly, these opposing effects were abrogated by BKCa up-regulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China. doctorducheng@gmail.com.

ABSTRACT
Increasing evidence suggests that caveolin-1 and large conductance Ca²⁺-activated potassium (BKCa) channels are implicated in the carcinogenesis processes, including cell proliferation and invasion. These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility. In this study, we investigated the probable interaction between caveolin-1 and BKCa in MCF-7 breast cancer cells. We identified that caveolin-1 and BKCa were co-localized and could be reciprocally co-immunoprecipitated in human breast cancer MCF-7 cells. siRNA mediated caveolin-1 knockdown resulted in activation and increased surface expression of BKCa channel, and subsequently promoted the proliferation and invasiveness of breast cancer cells. These effects were attenuated in the presence of BKCa-siRNA. Conversely, up-regulated caveolin-1 suppressed function and surface expression of BKCa channel and exerted negative effects on breast cancer cell proliferation and invasion. Similarly, these opposing effects were abrogated by BKCa up-regulation. Collectively, our findings suggest that BKCa is a critical target for suppression by caveolin-1 in suppressing proliferation and invasion of breast cancer cells. The functional complex of caveolin-1 and BKCa in the membrane microdomain may be served as a potential therapeutic target in breast cancer.

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Caveolin-1 knockdown mediated activation of BKCa channel promotes proliferation and invasion in MCF-7 cells. MCF-7 cells were transfected with indicated amounts of siRNAs for 48 h. For MTT assays (A–C), cells were plated in 96-well plates at an initial density of 4000 cells/well and cultured for the indicated time; For invasion assay (D–F), cells were plated in 24-well plates at an initial density of 30,000 cells/well and cultured for 24 h. Representative photographs of tumor cells that invaded through a Matrigel-coated filter were taken and shown. The invasive cells were counted in 10 random fields. The experiment was repeated at least three times and results are expressed relative to the number of control. All the experiments were repeated three times. (* p < 0.05).
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ijms-15-20706-f003: Caveolin-1 knockdown mediated activation of BKCa channel promotes proliferation and invasion in MCF-7 cells. MCF-7 cells were transfected with indicated amounts of siRNAs for 48 h. For MTT assays (A–C), cells were plated in 96-well plates at an initial density of 4000 cells/well and cultured for the indicated time; For invasion assay (D–F), cells were plated in 24-well plates at an initial density of 30,000 cells/well and cultured for 24 h. Representative photographs of tumor cells that invaded through a Matrigel-coated filter were taken and shown. The invasive cells were counted in 10 random fields. The experiment was repeated at least three times and results are expressed relative to the number of control. All the experiments were repeated three times. (* p < 0.05).

Mentions: Recent studies suggest that caveolin-1 inhibits breast cancer cell proliferation and invasion [6,10,11]. Furthermore, it is reported that enhanced expression of BKCa contributes to a high proliferation rate and greater invasiveness of breast cancer cells [16,17]. Therefore, we determined the effects of caveolin-1 knockdown mediated up-regulation and activation of BKCa channel on breast cancer proliferation and invasion. First, we knocked down the expression of caveolin-1 and found that the proliferation and invasiveness of MCF-7 cells were significantly increased (Figure 3A,D). Second, we down-regulated the expression of BKCa channel and found that the proliferation and invasion of MCF-7 cells were inhibited (Figure 3B,E). Finally, we co-transfected both siCav-1 and siBKCa into MCF-7 cells and found that siBKCa attenuated the proliferation and invasiveness of caveolin-1-downregulated MCF-7 cells (Figure 3C,F).


Caveolin-1 limits the contribution of BKCa channel to MCF-7 breast cancer cell proliferation and invasion.

Du C, Chen L, Zhang H, Wang Z, Liu W, Xie X, Xie M - Int J Mol Sci (2014)

Caveolin-1 knockdown mediated activation of BKCa channel promotes proliferation and invasion in MCF-7 cells. MCF-7 cells were transfected with indicated amounts of siRNAs for 48 h. For MTT assays (A–C), cells were plated in 96-well plates at an initial density of 4000 cells/well and cultured for the indicated time; For invasion assay (D–F), cells were plated in 24-well plates at an initial density of 30,000 cells/well and cultured for 24 h. Representative photographs of tumor cells that invaded through a Matrigel-coated filter were taken and shown. The invasive cells were counted in 10 random fields. The experiment was repeated at least three times and results are expressed relative to the number of control. All the experiments were repeated three times. (* p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264191&req=5

ijms-15-20706-f003: Caveolin-1 knockdown mediated activation of BKCa channel promotes proliferation and invasion in MCF-7 cells. MCF-7 cells were transfected with indicated amounts of siRNAs for 48 h. For MTT assays (A–C), cells were plated in 96-well plates at an initial density of 4000 cells/well and cultured for the indicated time; For invasion assay (D–F), cells were plated in 24-well plates at an initial density of 30,000 cells/well and cultured for 24 h. Representative photographs of tumor cells that invaded through a Matrigel-coated filter were taken and shown. The invasive cells were counted in 10 random fields. The experiment was repeated at least three times and results are expressed relative to the number of control. All the experiments were repeated three times. (* p < 0.05).
Mentions: Recent studies suggest that caveolin-1 inhibits breast cancer cell proliferation and invasion [6,10,11]. Furthermore, it is reported that enhanced expression of BKCa contributes to a high proliferation rate and greater invasiveness of breast cancer cells [16,17]. Therefore, we determined the effects of caveolin-1 knockdown mediated up-regulation and activation of BKCa channel on breast cancer proliferation and invasion. First, we knocked down the expression of caveolin-1 and found that the proliferation and invasiveness of MCF-7 cells were significantly increased (Figure 3A,D). Second, we down-regulated the expression of BKCa channel and found that the proliferation and invasion of MCF-7 cells were inhibited (Figure 3B,E). Finally, we co-transfected both siCav-1 and siBKCa into MCF-7 cells and found that siBKCa attenuated the proliferation and invasiveness of caveolin-1-downregulated MCF-7 cells (Figure 3C,F).

Bottom Line: These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility.These effects were attenuated in the presence of BKCa-siRNA.Similarly, these opposing effects were abrogated by BKCa up-regulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China. doctorducheng@gmail.com.

ABSTRACT
Increasing evidence suggests that caveolin-1 and large conductance Ca²⁺-activated potassium (BKCa) channels are implicated in the carcinogenesis processes, including cell proliferation and invasion. These two proteins have been proven to interact with each other in vascular endothelial and smooth muscle cells and modulate vascular contractility. In this study, we investigated the probable interaction between caveolin-1 and BKCa in MCF-7 breast cancer cells. We identified that caveolin-1 and BKCa were co-localized and could be reciprocally co-immunoprecipitated in human breast cancer MCF-7 cells. siRNA mediated caveolin-1 knockdown resulted in activation and increased surface expression of BKCa channel, and subsequently promoted the proliferation and invasiveness of breast cancer cells. These effects were attenuated in the presence of BKCa-siRNA. Conversely, up-regulated caveolin-1 suppressed function and surface expression of BKCa channel and exerted negative effects on breast cancer cell proliferation and invasion. Similarly, these opposing effects were abrogated by BKCa up-regulation. Collectively, our findings suggest that BKCa is a critical target for suppression by caveolin-1 in suppressing proliferation and invasion of breast cancer cells. The functional complex of caveolin-1 and BKCa in the membrane microdomain may be served as a potential therapeutic target in breast cancer.

Show MeSH
Related in: MedlinePlus