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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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Flow cytometric analysis of the cell cycle phase distribution(A) DNA content of MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (B) DNA content of MDA-MB-468-NC and MDA-MB-468-CXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (C) The effect of CXCR4 knockdown on cell cycle in MDA-MB-231 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (D) The effect of CXCR4 overexpression on cell cycle in MDA-MB-468 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (E) After treatment with 0 and 1 μM cisplatin for 48 h, the fraction of apoptotic cells was analyzed by flow cytometry. *p < 0.05, **p < 0.01, as compared with untreated cells.
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Figure 2: Flow cytometric analysis of the cell cycle phase distribution(A) DNA content of MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (B) DNA content of MDA-MB-468-NC and MDA-MB-468-CXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (C) The effect of CXCR4 knockdown on cell cycle in MDA-MB-231 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (D) The effect of CXCR4 overexpression on cell cycle in MDA-MB-468 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (E) After treatment with 0 and 1 μM cisplatin for 48 h, the fraction of apoptotic cells was analyzed by flow cytometry. *p < 0.05, **p < 0.01, as compared with untreated cells.

Mentions: To further assess the effect of CXCR4 on the sensitivity of TNBC cells to chemotherapy, we examined the cell cycle using flow cytometry (Figure 2A and 2B). The percentage of cells in each cell phase is shown in Figure 2C and 2D. Cisplatin (1 μM) treatment for 48 h increased the number of MDA-MB-231-shCXCR4 cells in G2/M phase compared with the untreated group (p = 0.001). To quantify apoptosis, we analyzed the percentage of sub-G1 cell cycles. The percentage of apoptosis of MDA-MB-231-shCXCR4 cells was 8.42 ± 0.76%, following treatment with 1 μM cisplatin. However, the same cisplatin concentration induced apoptosis in only 1.06 ± 0.18% of MDA-MB-231-NC cells (p = 0.002; Figure 2E). The percentage of cisplatin-induced apoptosis of CXCR4-negative MDA-MB-468 cells was higher than that of the control groups (4.30 ± 0.89% and 1.04 ± 0.22%, respectively, p = 0.025). However, there was no significantly observation of the G2/M arrest in MDA-MB-468-CXCR4 cells after cisplatin treatment compared with the untreated group (p = 0.162).


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)

Flow cytometric analysis of the cell cycle phase distribution(A) DNA content of MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (B) DNA content of MDA-MB-468-NC and MDA-MB-468-CXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (C) The effect of CXCR4 knockdown on cell cycle in MDA-MB-231 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (D) The effect of CXCR4 overexpression on cell cycle in MDA-MB-468 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (E) After treatment with 0 and 1 μM cisplatin for 48 h, the fraction of apoptotic cells was analyzed by flow cytometry. *p < 0.05, **p < 0.01, as compared with untreated cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Flow cytometric analysis of the cell cycle phase distribution(A) DNA content of MDA-MB-231-NC and MDA-MB-231-shCXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (B) DNA content of MDA-MB-468-NC and MDA-MB-468-CXCR4 cells treated with cisplatin (0, 1 μM) was analyzed by propidium iodide (PI) staining. (C) The effect of CXCR4 knockdown on cell cycle in MDA-MB-231 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (D) The effect of CXCR4 overexpression on cell cycle in MDA-MB-468 cells. From the left to right, the phases of the cell cycle were G1-phase, S-phase, and G2/M-phase. (E) After treatment with 0 and 1 μM cisplatin for 48 h, the fraction of apoptotic cells was analyzed by flow cytometry. *p < 0.05, **p < 0.01, as compared with untreated cells.
Mentions: To further assess the effect of CXCR4 on the sensitivity of TNBC cells to chemotherapy, we examined the cell cycle using flow cytometry (Figure 2A and 2B). The percentage of cells in each cell phase is shown in Figure 2C and 2D. Cisplatin (1 μM) treatment for 48 h increased the number of MDA-MB-231-shCXCR4 cells in G2/M phase compared with the untreated group (p = 0.001). To quantify apoptosis, we analyzed the percentage of sub-G1 cell cycles. The percentage of apoptosis of MDA-MB-231-shCXCR4 cells was 8.42 ± 0.76%, following treatment with 1 μM cisplatin. However, the same cisplatin concentration induced apoptosis in only 1.06 ± 0.18% of MDA-MB-231-NC cells (p = 0.002; Figure 2E). The percentage of cisplatin-induced apoptosis of CXCR4-negative MDA-MB-468 cells was higher than that of the control groups (4.30 ± 0.89% and 1.04 ± 0.22%, respectively, p = 0.025). However, there was no significantly observation of the G2/M arrest in MDA-MB-468-CXCR4 cells after cisplatin treatment compared with the untreated group (p = 0.162).

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