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Silencing of CXCR4 sensitizes triple-negative breast cancer cells to cisplatin.

Liang S, Peng X, Li X, Yang P, Xie L, Li Y, Du C, Zhang G - Oncotarget (2015)

Bottom Line: We found that CXCR4 silencing significantly inhibited cell growth, decreased colony formation, and enhanced cisplatin sensitivity while overexpression of CXCR4 rendered cells more resistant to cisplatin.Moreover, the percentage of apoptosis and cell cycle arrest at the G2/M phase of cisplatin-treated CXCR4 knockdown cells was significantly higher than control cells.However overexpression of CXCR4 had the reverse effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Breast Medical Oncology, Cancer Hospital of Shantou University Medical College, Shantou 515031, PR China.

ABSTRACT
Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer for which there is no effective treatment. Previously, we and others demonstrated that CXCR4 surface expression is an independent prognostic factor for disease relapse and survival in breast cancer. In this study, we investigated the effects of CXCR4 gene silencing on cisplatin chemosensitivity in human triple-negative breast cancer cell lines. We found that CXCR4 silencing significantly inhibited cell growth, decreased colony formation, and enhanced cisplatin sensitivity while overexpression of CXCR4 rendered cells more resistant to cisplatin. Moreover, the percentage of apoptosis and cell cycle arrest at the G2/M phase of cisplatin-treated CXCR4 knockdown cells was significantly higher than control cells. Furthermore, we demonstrated CXCR4 knockdown cells showed lower levels of mutant p53 and Bcl-2 protein than the control group, while also having higher levels of caspase-3 and Bax. However overexpression of CXCR4 had the reverse effect. In vivo experiments confirmed that downregulation of CXCR4 enhanced cisplatin anticancer activity in tumor-bearing mice, and that this enhanced anticancer activity is attributable to tumor cell apoptosis. Thus, this study indicates that CXCR4 can modulate cisplatin sensitivity in TNBC cells and suggests that CXCR4 may be a therapeutic target for TNBC.

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The effect of CXCR4 on protein expression and cell cycle associated proteins in TNBC cells(A) MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (B) MDA-MB-468-NC and MDA-MB-468-CXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (C) Immunohistochemical staining of xenograft tumors for p53, Bax, Bcl-2 and caspase-3 (magnification = 40×).
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Figure 4: The effect of CXCR4 on protein expression and cell cycle associated proteins in TNBC cells(A) MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (B) MDA-MB-468-NC and MDA-MB-468-CXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (C) Immunohistochemical staining of xenograft tumors for p53, Bax, Bcl-2 and caspase-3 (magnification = 40×).

Mentions: To further understand the molecular events involved in the apoptosis resulting from CXCR4 knockdown, we next investigated the expression of p53, Bcl-2, Bax, and caspase-3, which are pivotal for cell apoptosis. Figure 4A shows the expression of these proteins in MDA-MB-231 cells. Expression of mutant p53 was clearly downregulated in MDA-MB-231 cells after transfection of CXCR4 shRNA and/or treatment with cisplatin. Simultaneously, we observed upregulation of Bax and cleaved caspase-3 and downregulation of Bcl-2, suggesting that a decrease in the Bcl-2/Bax ratio might be involved in the apoptosis induced by CXCR4 shRNA combined with cisplatin in MDA-MB-231 cells. Furthermore, the expression of mutant p53 and Bcl-2 were increased and decreased Bax was decreased in CXCR4 transfected MDA-MB-468 cells (Figure 4B). But no observation of cleaved caspase-3 in MDA-MB-468-CXCR4 cells after treatment with cisplatin.


Silencing of CXCR4 sensitizes triple-negative breast cancer cells to cisplatin.

Liang S, Peng X, Li X, Yang P, Xie L, Li Y, Du C, Zhang G - Oncotarget (2015)

The effect of CXCR4 on protein expression and cell cycle associated proteins in TNBC cells(A) MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (B) MDA-MB-468-NC and MDA-MB-468-CXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (C) Immunohistochemical staining of xenograft tumors for p53, Bax, Bcl-2 and caspase-3 (magnification = 40×).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359214&req=5

Figure 4: The effect of CXCR4 on protein expression and cell cycle associated proteins in TNBC cells(A) MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (B) MDA-MB-468-NC and MDA-MB-468-CXCR4 cells were treated with cisplatin (0, 10 μM) for 48 h, cellular protein was harvested, and Western blot analysis was performed to investigate the levels of mutant p53, Bax, Bcl-2 and caspase-3. The β-Actin was detected as a loading control. (C) Immunohistochemical staining of xenograft tumors for p53, Bax, Bcl-2 and caspase-3 (magnification = 40×).
Mentions: To further understand the molecular events involved in the apoptosis resulting from CXCR4 knockdown, we next investigated the expression of p53, Bcl-2, Bax, and caspase-3, which are pivotal for cell apoptosis. Figure 4A shows the expression of these proteins in MDA-MB-231 cells. Expression of mutant p53 was clearly downregulated in MDA-MB-231 cells after transfection of CXCR4 shRNA and/or treatment with cisplatin. Simultaneously, we observed upregulation of Bax and cleaved caspase-3 and downregulation of Bcl-2, suggesting that a decrease in the Bcl-2/Bax ratio might be involved in the apoptosis induced by CXCR4 shRNA combined with cisplatin in MDA-MB-231 cells. Furthermore, the expression of mutant p53 and Bcl-2 were increased and decreased Bax was decreased in CXCR4 transfected MDA-MB-468 cells (Figure 4B). But no observation of cleaved caspase-3 in MDA-MB-468-CXCR4 cells after treatment with cisplatin.

Bottom Line: We found that CXCR4 silencing significantly inhibited cell growth, decreased colony formation, and enhanced cisplatin sensitivity while overexpression of CXCR4 rendered cells more resistant to cisplatin.Moreover, the percentage of apoptosis and cell cycle arrest at the G2/M phase of cisplatin-treated CXCR4 knockdown cells was significantly higher than control cells.However overexpression of CXCR4 had the reverse effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Breast Medical Oncology, Cancer Hospital of Shantou University Medical College, Shantou 515031, PR China.

ABSTRACT
Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer for which there is no effective treatment. Previously, we and others demonstrated that CXCR4 surface expression is an independent prognostic factor for disease relapse and survival in breast cancer. In this study, we investigated the effects of CXCR4 gene silencing on cisplatin chemosensitivity in human triple-negative breast cancer cell lines. We found that CXCR4 silencing significantly inhibited cell growth, decreased colony formation, and enhanced cisplatin sensitivity while overexpression of CXCR4 rendered cells more resistant to cisplatin. Moreover, the percentage of apoptosis and cell cycle arrest at the G2/M phase of cisplatin-treated CXCR4 knockdown cells was significantly higher than control cells. Furthermore, we demonstrated CXCR4 knockdown cells showed lower levels of mutant p53 and Bcl-2 protein than the control group, while also having higher levels of caspase-3 and Bax. However overexpression of CXCR4 had the reverse effect. In vivo experiments confirmed that downregulation of CXCR4 enhanced cisplatin anticancer activity in tumor-bearing mice, and that this enhanced anticancer activity is attributable to tumor cell apoptosis. Thus, this study indicates that CXCR4 can modulate cisplatin sensitivity in TNBC cells and suggests that CXCR4 may be a therapeutic target for TNBC.

Show MeSH
Related in: MedlinePlus