The functional significance of microRNA-145 in prostate cancer - PubMed (original) (raw)

The functional significance of microRNA-145 in prostate cancer

M S Zaman et al. Br J Cancer. 2010.

Erratum in

Br J Cancer. 2011 Mar 1;104(5):892

Abstract

Background: MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in numerous cellular processes. Recent studies have shown aberrant expression of miRNAs in prostate cancer tissues and cell lines. On the basis of miRNA microarray data, we found that miR-145 is significantly downregulated in prostate cancer.

Methods and results: We investigated the expression and functional significance of miR-145 in prostate cancer. The expression of miR-145 was low in all the prostate cell lines tested (PC3, LNCaP and DU145) compared with the normal cell line, PWR-1E, and in cancerous regions of human prostate tissue when compared with the matched adjacent normal. Overexpression of miR-145 in PC3-transfected cells resulted in increased apoptosis and an increase in cells in the G2/M phase, as detected by flow cytometry. Investigation of the mechanisms of inactivation of miR-145 through epigenetic pathways revealed significant DNA methylation of the miR-145 promoter region in prostate cancer cell lines. Microarray analyses of miR-145-overexpressing PC3 cells showed upregulation of the pro-apoptotic gene TNFSF10, which was confirmed by real-time PCR and western analysis.

Conclusion: One of the genes significantly upregulated by miR-145 overexpression is the proapoptotic gene TNFSF10. Therefore, modulation of miR-145 may be an important therapeutic approach for the management of prostate cancer.

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Figures

Figure 1

miR-145 expression is silenced in prostate cancer cell lines and tumour samples. (A) Level of miR-145 in untreated PC3, LNCaP, Du145 and PWR-1E cell lines. The expression of miR-145 was found to be low in all the prostate cancer cell lines tested (untreated PC3, LNCaP and Du145) when compared with the normal PWR-1E cells. (B) 5-aza treatment of prostate cancer cell lines resulted in a significant increase in the expression of miR-145. (C) Relative miR-145 levels in cancerous regions of prostate tissue, as normalised to adjacent normal (value 1). The level of miR-145 expression in adjacent normal prostate tissue regions was found to be significantly higher when compared with the matched cancerous regions in 80% of the samples tested.

Figure 2

Methylation status of the 5′ upstream region of the miR-145 transcription start site in prostate cancer cell lines. The x axis denotes the number of bases. The +ve and −ve values attached to the bases represent downstream (+ve) and upstream (−ve) of the putative transcriptional start site of the precursor of miR-145. The y axis indicates the percentage of methylation in the CpG sites.

Figure 3

Effect of genistein, 5-aza and TSA on miR-145 expression in PC3 cells. Genistein in combination with 5-aza and TSA significantly increased miR-145 levels.

Figure 4

Overexpression of miR-145 in PC3 cells. (A) Increase in the level of miR-145 after transfection in PC3 cells. (B) Decrease in cell viability in a time-dependent manner in miR-145-transfected cells compared with the negative control and mock samples.

Figure 5

Flow cytometry analysis of miR-145-transfected PC3 cells. (A) Cell cycle analyses showed a decrease in the G0–G1 stage with a concomitant increase in cells in the G2–M phase in those cells transfected with a precursor of miR-145 when compared with both mock and negative control. (B) miR-145 upregulation increased apoptosis (5%) in the total number of PC3 cells undergoing apoptosis (apoptotic and early apoptotic) in miR-145-transfected PC3 cells when compared with both negative control and mock. (C) Cell cycle analysis of miR-145-transfected Du145 cells showed an increase of ∼9% in the cells in G0–G1 stage when compared with mock, with a concomitant decrease of ∼7% of cells in the G2–M phase. (D) There was a significant increase (∼11%) in the total number of Du145 cells undergoing apoptosis (apoptotic and early apoptotic) in the miR-145-transfected Du145 cells when compared with mock.

Figure 5

Figure 6

Effect of miR-145 overexpression on apoptosis/cell cycle genes in PC3 cells. Increased expression of (A) TNFSF10, (B) HERC5 and (C) IL24 in miR-145-transfected PC3 cells when compared with mock and the negative control. (D) Western analysis of upregulated and downregulated genes in miR-145-transfected PC3 cells. Upregulation of TNFSF10 protein expression occurred concomitantly with downregulation of cdk6 in PC3 cells transfected with miR-145 precursor.

References

1. Baek D, Villen J, Shin C, Camargo FD, Gygi SP, Bartel DP (2008) The impact of microRNAs on protein output. Nature 455: 64–71 - PMC - PubMed
1. Barbarotto E, Schmittgen TD, Calin GA (2008) MicroRNAs and cancer: profile, profile, profile. Int J Cancer 122: 969–977 - PubMed
1. Bektic J, Guggenberger R, Eder IE, Pelzer AE, Berger AP, Bartsch G, Klocker H (2005) Molecular effects of the isoflavonoid genistein in prostate cancer. Clin Prostate Cancer 4: 124–129 - PubMed
1. Bender CM, Pao MM, Jones PA (1998) Inhibition of DNA methylation by 5-aza-2′-deoxycytidine suppresses the growth of human tumor cell lines. Cancer Res 58: 95–101 - PubMed
1. Bloomston M, Frankel WL, Petrocca F, Volinia S, Alder H, Hagan JP, Liu CG, Bhatt D, Taccioli C, Croce CM (2007) MicroRNA expression patterns to differentiate pancreatic adenocarcinoma from normal pancreas and chronic pancreatitis. JAMA 297: 1901–1908 - PubMed

The functional significance of microRNA-145 in prostate cancer - PubMed (original) (raw)