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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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FOXM1 downregulates the expression of SP1 and hCTR1Western blots of FOXM1, SP1, hCTR1, and the internal control β-ACTIN in Ad293 cells expressing vector alone (pcDNA), vector encoding FOXM1, control siRNA (siControl), or FOXM1 siRNA (siFOXM1).
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Figure 6: FOXM1 downregulates the expression of SP1 and hCTR1Western blots of FOXM1, SP1, hCTR1, and the internal control β-ACTIN in Ad293 cells expressing vector alone (pcDNA), vector encoding FOXM1, control siRNA (siControl), or FOXM1 siRNA (siFOXM1).

Mentions: The higher expression of FOXM1 in chemoresistant cells than parental cells (Figs. 1C and 4A) suggests that FOXM1 may contribute to chemoresistance. To test this premise, we examined FOXM1 expression in two additional ovarian cancer cell lines. BG-1 cells expressed less FOXM1 than SKOV-3 cells (Fig. 3B) and were less resistant to cisplatin (IC50 of SKOV-3 = 7.31 μM, IC50 of BG-1 = 3.13 μM) (Fig. 3B). We then established three BG-1 stable clones that overexpressed FOXM1 and three stable SKOV-3 clones that expressed FOXM1 shRNA. As shown in Fig. 5A, FOXM1-overexpressing cells (#a, #b, and #c) exhibited higher cisplatin resistance than vector-transfected cells (IC50 values were 6.90, 4.83, 4.36, and 1.95 μM, respectively; P = 0.016, one-way ANOVA) and higher sphere formation ability. Conversely, SKOV-3 cells depleted of FOXM1 (#a, #b, and #c) were less resistant to cisplatin than vector-transfected cells (IC50 values were 3.14, 4.68, 6.01, and 8.82 μM, respectively; P < 0.001, one-way ANOVA) and had lower sphere formation ability (Fig. 5B). The effect of FOXM1 on chemoresistance and stemness was also investigated in A2780 and A2780CP70 cells. Overexpression of FOXM1 in A2780 cells (#a and #b) enhanced cisplatin resistance compared with the vector control (IC50 values were 12.44, 10.19, and 7.45 μM, respectively; P < 0.001, one-way ANOVA) and sphere formation (Figs. 4B and 5C). In contrast, FOXM1 silencing in A2780CP70 cells decreased cisplatin resistance compared with the vector control (IC50 values were 10.89, 21.39, and 26.07 μM, respectively; P < 0.001, Kruskal-Wallis test) and sphere formation (Figs. 4B and 5D). Of note, the effects of FOXM1 on these responses were dose-dependent. We also determined whether FOXM1 affects the expression of human copper transporter 1 (hCTR1), which transports cisplatin into cells to elicit a cytotoxic effect. Overexpression of FOXM1 in the human embryonic kidney Ad293 cells decreased amounts of hCTR1 and its regulatory transcription factor SP1, while knockdown of FOXM1 via RNA interference increased amounts of hCTR1 and SP1 (Fig. 6). These findings suggest FOXM1 promotes cisplatin resistance by impairing cisplatin uptake.


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)

FOXM1 downregulates the expression of SP1 and hCTR1Western blots of FOXM1, SP1, hCTR1, and the internal control β-ACTIN in Ad293 cells expressing vector alone (pcDNA), vector encoding FOXM1, control siRNA (siControl), or FOXM1 siRNA (siFOXM1).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: FOXM1 downregulates the expression of SP1 and hCTR1Western blots of FOXM1, SP1, hCTR1, and the internal control β-ACTIN in Ad293 cells expressing vector alone (pcDNA), vector encoding FOXM1, control siRNA (siControl), or FOXM1 siRNA (siFOXM1).
Mentions: The higher expression of FOXM1 in chemoresistant cells than parental cells (Figs. 1C and 4A) suggests that FOXM1 may contribute to chemoresistance. To test this premise, we examined FOXM1 expression in two additional ovarian cancer cell lines. BG-1 cells expressed less FOXM1 than SKOV-3 cells (Fig. 3B) and were less resistant to cisplatin (IC50 of SKOV-3 = 7.31 μM, IC50 of BG-1 = 3.13 μM) (Fig. 3B). We then established three BG-1 stable clones that overexpressed FOXM1 and three stable SKOV-3 clones that expressed FOXM1 shRNA. As shown in Fig. 5A, FOXM1-overexpressing cells (#a, #b, and #c) exhibited higher cisplatin resistance than vector-transfected cells (IC50 values were 6.90, 4.83, 4.36, and 1.95 μM, respectively; P = 0.016, one-way ANOVA) and higher sphere formation ability. Conversely, SKOV-3 cells depleted of FOXM1 (#a, #b, and #c) were less resistant to cisplatin than vector-transfected cells (IC50 values were 3.14, 4.68, 6.01, and 8.82 μM, respectively; P < 0.001, one-way ANOVA) and had lower sphere formation ability (Fig. 5B). The effect of FOXM1 on chemoresistance and stemness was also investigated in A2780 and A2780CP70 cells. Overexpression of FOXM1 in A2780 cells (#a and #b) enhanced cisplatin resistance compared with the vector control (IC50 values were 12.44, 10.19, and 7.45 μM, respectively; P < 0.001, one-way ANOVA) and sphere formation (Figs. 4B and 5C). In contrast, FOXM1 silencing in A2780CP70 cells decreased cisplatin resistance compared with the vector control (IC50 values were 10.89, 21.39, and 26.07 μM, respectively; P < 0.001, Kruskal-Wallis test) and sphere formation (Figs. 4B and 5D). Of note, the effects of FOXM1 on these responses were dose-dependent. We also determined whether FOXM1 affects the expression of human copper transporter 1 (hCTR1), which transports cisplatin into cells to elicit a cytotoxic effect. Overexpression of FOXM1 in the human embryonic kidney Ad293 cells decreased amounts of hCTR1 and its regulatory transcription factor SP1, while knockdown of FOXM1 via RNA interference increased amounts of hCTR1 and SP1 (Fig. 6). These findings suggest FOXM1 promotes cisplatin resistance by impairing cisplatin uptake.

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