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FOXM1 confers to epithelial-mesenchymal transition, stemness and chemoresistance in epithelial ovarian carcinoma cells.

Chiu WT, Huang YF, Tsai HY, Chen CC, Chang CH, Huang SC, Hsu KF, Chou CY - Oncotarget (2015)

Bottom Line: Chemoresistance to anti-cancer drugs substantially reduces survival in epithelial ovarian cancer.Conversely, depletion of FOXM1 via RNA interference reduced cisplatin resistance and sphere formation in cisplatin-resistant and high FOXM1-expressing cells.The combination of cisplatin and the FOXM1 inhibitor thiostrepton inhibited the expression of stem cell markers in chemoresistant cells and subcutaneous ovarian tumor growth in mouse xenografts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.

ABSTRACT
Chemoresistance to anti-cancer drugs substantially reduces survival in epithelial ovarian cancer. In this study, we showed that chemoresistance to cisplatin and paclitaxel induced the epithelial-mesenchymal transition (EMT) and a stem cell phenotype in ovarian cancer cells. Chemoresistance was associated with the downregulation of epithelial markers and the upregulation of mesenchymal markers, EMT-related transcription factors, and cancer stem cell markers, which enhanced invasion and sphere formation ability. Overexpression of FOXM1 increased cisplatin-resistance and sphere formation in cisplatin-sensitive and low FOXM1-expressing ovarian cancer cells. Conversely, depletion of FOXM1 via RNA interference reduced cisplatin resistance and sphere formation in cisplatin-resistant and high FOXM1-expressing cells. Overexpression of FOXM1 also increased the expression, nuclear accumulation, and activity of β-CATENIN in chemoresistant cells, whereas downregulation of FOXM1 suppressed these events. The combination of cisplatin and the FOXM1 inhibitor thiostrepton inhibited the expression of stem cell markers in chemoresistant cells and subcutaneous ovarian tumor growth in mouse xenografts. In an analysis of 106 ovarian cancer patients, high FOXM1 levels in tumors were associated with cancer progression and short progression-free intervals. Collectively, our findings highlight the importance of FOXM1 in chemoresistance and suggest that FOXM1 inhibitors may be useful for treatment of ovarian cancer.

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Chemoresistant IGROV1 sublines exhibit characteristics of the epithelial-mesenchymal transition (EMT)IGROV1 cells resistant to 1 μM cisplatin (CP1), 2 μM cisplatin (CP2), and 0.005 μg/mL paclitaxel (TX0.005) were isolated. (A) The IC50 values of the parental (Ctrl) and resistant cell lines were determined using MTT assays. (B) Phase contrast images of parental and chemoresistant cells. Scale bars, 100 μm. (C) Amounts of the indicated proteins were determined via western blotting. (D) Immunofluorescence staining of nuclei, E-CADHERIN, and VIMENTIN. Images were taken using a confocal microscope under excitation at 405 nm, 488 nm, or 543 nm. Scale bars, 20 μm. (E) In vitro transwell invasion assay. Left panel, representative photomicrographs of cells that penetrated a Matrigel-coated filter. Scale bars: 200 μm. Right panel, invasive cells were counted in 15 random fields on the lower surface of the filters and are expressed as invaded cells per field. Each bar represents mean ± standard error of the mean from two independent experiments. *: significant difference between chemoresistant and parental cells (A, E); #: significant difference between CP1 and CP2 cells (A). *: P < 0.05; **, ##: P < 0.01; ***, ###: P < 0.001 (A, E).
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Figure 1: Chemoresistant IGROV1 sublines exhibit characteristics of the epithelial-mesenchymal transition (EMT)IGROV1 cells resistant to 1 μM cisplatin (CP1), 2 μM cisplatin (CP2), and 0.005 μg/mL paclitaxel (TX0.005) were isolated. (A) The IC50 values of the parental (Ctrl) and resistant cell lines were determined using MTT assays. (B) Phase contrast images of parental and chemoresistant cells. Scale bars, 100 μm. (C) Amounts of the indicated proteins were determined via western blotting. (D) Immunofluorescence staining of nuclei, E-CADHERIN, and VIMENTIN. Images were taken using a confocal microscope under excitation at 405 nm, 488 nm, or 543 nm. Scale bars, 20 μm. (E) In vitro transwell invasion assay. Left panel, representative photomicrographs of cells that penetrated a Matrigel-coated filter. Scale bars: 200 μm. Right panel, invasive cells were counted in 15 random fields on the lower surface of the filters and are expressed as invaded cells per field. Each bar represents mean ± standard error of the mean from two independent experiments. *: significant difference between chemoresistant and parental cells (A, E); #: significant difference between CP1 and CP2 cells (A). *: P < 0.05; **, ##: P < 0.01; ***, ###: P < 0.001 (A, E).

Mentions: To elucidate the underlying mechanisms of chemoresistance in ovarian cancer, human ovarian cancer sublines resistant to cisplatin or paclitaxel were established. As shown in Fig. 1A, the IGROV1 sublines CP1 and CP2 were more resistant to cisplatin than parental cells (IC50 values were 5.88, 12.57, and 2.78 μM, respectively; P = 0.002, Kruskal-Wallis test). Similarly, the IGROV1 subline TX0.005 was more resistant to paclitaxel than parental cells (IC50 values were 0.60 μg/mL and 0.02 μg/mL, respectively; P = 0.002). Compared with parental cells, the drug resistant cells had an elongated mesenchymal-like morphology and fewer cell-cell junctions (Fig. 1B).


FOXM1 confers to epithelial-mesenchymal transition, stemness and chemoresistance in epithelial ovarian carcinoma cells.

Chiu WT, Huang YF, Tsai HY, Chen CC, Chang CH, Huang SC, Hsu KF, Chou CY - Oncotarget (2015)

Chemoresistant IGROV1 sublines exhibit characteristics of the epithelial-mesenchymal transition (EMT)IGROV1 cells resistant to 1 μM cisplatin (CP1), 2 μM cisplatin (CP2), and 0.005 μg/mL paclitaxel (TX0.005) were isolated. (A) The IC50 values of the parental (Ctrl) and resistant cell lines were determined using MTT assays. (B) Phase contrast images of parental and chemoresistant cells. Scale bars, 100 μm. (C) Amounts of the indicated proteins were determined via western blotting. (D) Immunofluorescence staining of nuclei, E-CADHERIN, and VIMENTIN. Images were taken using a confocal microscope under excitation at 405 nm, 488 nm, or 543 nm. Scale bars, 20 μm. (E) In vitro transwell invasion assay. Left panel, representative photomicrographs of cells that penetrated a Matrigel-coated filter. Scale bars: 200 μm. Right panel, invasive cells were counted in 15 random fields on the lower surface of the filters and are expressed as invaded cells per field. Each bar represents mean ± standard error of the mean from two independent experiments. *: significant difference between chemoresistant and parental cells (A, E); #: significant difference between CP1 and CP2 cells (A). *: P < 0.05; **, ##: P < 0.01; ***, ###: P < 0.001 (A, E).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4385856&req=5

Figure 1: Chemoresistant IGROV1 sublines exhibit characteristics of the epithelial-mesenchymal transition (EMT)IGROV1 cells resistant to 1 μM cisplatin (CP1), 2 μM cisplatin (CP2), and 0.005 μg/mL paclitaxel (TX0.005) were isolated. (A) The IC50 values of the parental (Ctrl) and resistant cell lines were determined using MTT assays. (B) Phase contrast images of parental and chemoresistant cells. Scale bars, 100 μm. (C) Amounts of the indicated proteins were determined via western blotting. (D) Immunofluorescence staining of nuclei, E-CADHERIN, and VIMENTIN. Images were taken using a confocal microscope under excitation at 405 nm, 488 nm, or 543 nm. Scale bars, 20 μm. (E) In vitro transwell invasion assay. Left panel, representative photomicrographs of cells that penetrated a Matrigel-coated filter. Scale bars: 200 μm. Right panel, invasive cells were counted in 15 random fields on the lower surface of the filters and are expressed as invaded cells per field. Each bar represents mean ± standard error of the mean from two independent experiments. *: significant difference between chemoresistant and parental cells (A, E); #: significant difference between CP1 and CP2 cells (A). *: P < 0.05; **, ##: P < 0.01; ***, ###: P < 0.001 (A, E).
Mentions: To elucidate the underlying mechanisms of chemoresistance in ovarian cancer, human ovarian cancer sublines resistant to cisplatin or paclitaxel were established. As shown in Fig. 1A, the IGROV1 sublines CP1 and CP2 were more resistant to cisplatin than parental cells (IC50 values were 5.88, 12.57, and 2.78 μM, respectively; P = 0.002, Kruskal-Wallis test). Similarly, the IGROV1 subline TX0.005 was more resistant to paclitaxel than parental cells (IC50 values were 0.60 μg/mL and 0.02 μg/mL, respectively; P = 0.002). Compared with parental cells, the drug resistant cells had an elongated mesenchymal-like morphology and fewer cell-cell junctions (Fig. 1B).

Bottom Line: Chemoresistance to anti-cancer drugs substantially reduces survival in epithelial ovarian cancer.Conversely, depletion of FOXM1 via RNA interference reduced cisplatin resistance and sphere formation in cisplatin-resistant and high FOXM1-expressing cells.The combination of cisplatin and the FOXM1 inhibitor thiostrepton inhibited the expression of stem cell markers in chemoresistant cells and subcutaneous ovarian tumor growth in mouse xenografts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.

ABSTRACT
Chemoresistance to anti-cancer drugs substantially reduces survival in epithelial ovarian cancer. In this study, we showed that chemoresistance to cisplatin and paclitaxel induced the epithelial-mesenchymal transition (EMT) and a stem cell phenotype in ovarian cancer cells. Chemoresistance was associated with the downregulation of epithelial markers and the upregulation of mesenchymal markers, EMT-related transcription factors, and cancer stem cell markers, which enhanced invasion and sphere formation ability. Overexpression of FOXM1 increased cisplatin-resistance and sphere formation in cisplatin-sensitive and low FOXM1-expressing ovarian cancer cells. Conversely, depletion of FOXM1 via RNA interference reduced cisplatin resistance and sphere formation in cisplatin-resistant and high FOXM1-expressing cells. Overexpression of FOXM1 also increased the expression, nuclear accumulation, and activity of β-CATENIN in chemoresistant cells, whereas downregulation of FOXM1 suppressed these events. The combination of cisplatin and the FOXM1 inhibitor thiostrepton inhibited the expression of stem cell markers in chemoresistant cells and subcutaneous ovarian tumor growth in mouse xenografts. In an analysis of 106 ovarian cancer patients, high FOXM1 levels in tumors were associated with cancer progression and short progression-free intervals. Collectively, our findings highlight the importance of FOXM1 in chemoresistance and suggest that FOXM1 inhibitors may be useful for treatment of ovarian cancer.

Show MeSH
Related in: MedlinePlus