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Let-7b expression determines response to chemotherapy through the regulation of cyclin D1 in glioblastoma.

Guo Y, Yan K, Fang J, Qu Q, Zhou M, Chen F - J. Exp. Clin. Cancer Res. (2013)

Bottom Line: Microarray analysis identified Let-7b and other miRNAs significantly down-regulated in U251R cells compared to U251 cells.Knockdown of cyclin D1 expression significantly increased cisplatin-induced G1 arrest and apoptosis.Collectively, our results indicated that cisplatin treatment leads to Let-7b suppression, which in turn up-regulates cyclin D1 expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, Xiangya Hospital, Central South University, 410008, Changsha, China.

ABSTRACT

Background: Glioblastoma is the most common type of primary brain tumors. Cisplatin is a commonly used chemotherapeutic agent for Glioblastoma patients. Despite a consistent rate of initial responses, cisplatin treatment often develops chemoresistance, leading to therapeutic failure. Cellular resistance to cisplatin is of great concern and understanding the molecular mechanisms is an utter need.

Methods: Glioblastoma cell line U251 cells were exposed to increasing doses of cisplatin for 6 months to establish cisplatin-resistant cell line U251R. The differential miRNA expression profiles in U251 and U251R cell lines were identified by microarray analysis and confirmed by Q-PCR. MiRNA mimics were transfected into U251R cells, and cellular response to cisplatin-induced apoptosis and cell cycle distribution were examined by FACS analysis.

Results: U251R cells showed 3.1-fold increase in cisplatin resistance compared to its parental U251 cells. Microarray analysis identified Let-7b and other miRNAs significantly down-regulated in U251R cells compared to U251 cells. Transfection of Let-7b mimics greatly re-sensitized U251R cells to cisplatin, while transfection of other miRNAs has no effect or slightly effect. Cyclin D1 is predicted as a target of Let-7b through bioinformatics analysis. Over-expression of Let-7b mimics suppressed cyclin D1 protein expression and inhibited cyclin D1-3'-UTR luciferase activity. Knockdown of cyclin D1 expression significantly increased cisplatin-induced G1 arrest and apoptosis.

Conclusions: Collectively, our results indicated that cisplatin treatment leads to Let-7b suppression, which in turn up-regulates cyclin D1 expression. Let-7b may serve as a marker of cisplatin resistance, and can enhance the therapeutic benefit of cisplatin in glioblastoma cells.

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Let-7b increased cisplatin induced G0/G1 arrest. U251R cells were transfected with scramble (SCR) (A) or Let-7b mimics (B) and then treated with cisplatin; cell cycle was detected by flow cytometry. The percentage of cells in different cell cycle phases was calculated (C). Data is presented from three independent experiments, and the symbol * indicates statistical difference (p < 0.05).
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Figure 4: Let-7b increased cisplatin induced G0/G1 arrest. U251R cells were transfected with scramble (SCR) (A) or Let-7b mimics (B) and then treated with cisplatin; cell cycle was detected by flow cytometry. The percentage of cells in different cell cycle phases was calculated (C). Data is presented from three independent experiments, and the symbol * indicates statistical difference (p < 0.05).

Mentions: To further confirm the role of Let-7b in cisplatin resistance, cell cycle distribution was analyzed by flow cytometry. Compared with negative control, transfection of Let-7b mimics into U251R cells significantly increased cisplatin-induced G1 arrest (FigureĀ 4A-C).


Let-7b expression determines response to chemotherapy through the regulation of cyclin D1 in glioblastoma.

Guo Y, Yan K, Fang J, Qu Q, Zhou M, Chen F - J. Exp. Clin. Cancer Res. (2013)

Let-7b increased cisplatin induced G0/G1 arrest. U251R cells were transfected with scramble (SCR) (A) or Let-7b mimics (B) and then treated with cisplatin; cell cycle was detected by flow cytometry. The percentage of cells in different cell cycle phases was calculated (C). Data is presented from three independent experiments, and the symbol * indicates statistical difference (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3716992&req=5

Figure 4: Let-7b increased cisplatin induced G0/G1 arrest. U251R cells were transfected with scramble (SCR) (A) or Let-7b mimics (B) and then treated with cisplatin; cell cycle was detected by flow cytometry. The percentage of cells in different cell cycle phases was calculated (C). Data is presented from three independent experiments, and the symbol * indicates statistical difference (p < 0.05).
Mentions: To further confirm the role of Let-7b in cisplatin resistance, cell cycle distribution was analyzed by flow cytometry. Compared with negative control, transfection of Let-7b mimics into U251R cells significantly increased cisplatin-induced G1 arrest (FigureĀ 4A-C).

Bottom Line: Microarray analysis identified Let-7b and other miRNAs significantly down-regulated in U251R cells compared to U251 cells.Knockdown of cyclin D1 expression significantly increased cisplatin-induced G1 arrest and apoptosis.Collectively, our results indicated that cisplatin treatment leads to Let-7b suppression, which in turn up-regulates cyclin D1 expression.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, Xiangya Hospital, Central South University, 410008, Changsha, China.

ABSTRACT

Background: Glioblastoma is the most common type of primary brain tumors. Cisplatin is a commonly used chemotherapeutic agent for Glioblastoma patients. Despite a consistent rate of initial responses, cisplatin treatment often develops chemoresistance, leading to therapeutic failure. Cellular resistance to cisplatin is of great concern and understanding the molecular mechanisms is an utter need.

Methods: Glioblastoma cell line U251 cells were exposed to increasing doses of cisplatin for 6 months to establish cisplatin-resistant cell line U251R. The differential miRNA expression profiles in U251 and U251R cell lines were identified by microarray analysis and confirmed by Q-PCR. MiRNA mimics were transfected into U251R cells, and cellular response to cisplatin-induced apoptosis and cell cycle distribution were examined by FACS analysis.

Results: U251R cells showed 3.1-fold increase in cisplatin resistance compared to its parental U251 cells. Microarray analysis identified Let-7b and other miRNAs significantly down-regulated in U251R cells compared to U251 cells. Transfection of Let-7b mimics greatly re-sensitized U251R cells to cisplatin, while transfection of other miRNAs has no effect or slightly effect. Cyclin D1 is predicted as a target of Let-7b through bioinformatics analysis. Over-expression of Let-7b mimics suppressed cyclin D1 protein expression and inhibited cyclin D1-3'-UTR luciferase activity. Knockdown of cyclin D1 expression significantly increased cisplatin-induced G1 arrest and apoptosis.

Conclusions: Collectively, our results indicated that cisplatin treatment leads to Let-7b suppression, which in turn up-regulates cyclin D1 expression. Let-7b may serve as a marker of cisplatin resistance, and can enhance the therapeutic benefit of cisplatin in glioblastoma cells.

Show MeSH
Related in: MedlinePlus