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Molecular deregulation induced by silencing of the high mobility group protein A2 gene in retinoblastoma cells.

Venkatesan N, Krishnakumar S, Deepa PR, Deepa M, Khetan V, Reddy MA - Mol. Vis. (2012)

Bottom Line: These deregulated genes were compared for their constitutive expression in primary RB tumors (n=10).Zymographic analysis revealed that the increase in MMP mRNA expression in the post-silenced RB cells did not correlate with corresponding enzyme activity.HMGA2 may be considered a promising candidate for gene silencing therapy in RB.

View Article: PubMed Central - PubMed

Affiliation: Department of Ocular pathology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.

ABSTRACT

Aim: To explore the molecular mechanisms deregulated by high mobility group protein A2 (HMGA2) gene silencing in retinoblastoma (RB) cells.

Methods: Synthetic anti-HMGA2 short interfering RNA (siRNA) was used to silence the HMGA2 gene in cultured Y79 RB cells that were subjected to whole genome microarray analysis. The expression of differentially regulated key genes was confirmed with quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) in post-silenced RB cell lines (Y79 and WERI Rb1). These deregulated genes were compared for their constitutive expression in primary RB tumors (n=10). Zymographic determination of matrix metalloproteinase (MMP) activity was performed in RB cells. A cell cycle assay and a proliferation assay were performed in post-transfected RB cells.

Results: HMGA2 gene silencing in cultured RB cells results in reduced cell proliferation and transition in the G1/S phase. The whole genome microarray analysis of HMGA2 silenced Y79 cells revealed overall upregulation of 1,132 genes (≥ 1.0 fold) and downregulation of 1,562 genes (≤ -1.0 fold). Specific quantitative pathway analysis of the deregulated genes (using Biointerpreter) revealed 150 upregulated genes and 77 downregulated genes (≥ 1.0 fold) involved in vital pathways, namely, mitogen-activated protein kinase, Janus kinase/signal transducers and activators of transcription, Ras pathway, Ras-induced extracellular signal-regulated protein kinases 1 and 2, and tumor protein p53. The differential expression of genes obtained from microarray analysis (Homo sapiens ELK1, member of ETS oncogene family [ELK1], Homo sapiens cyclin-dependent kinase 6 [CDK6], Homo sapiens E2F transcription factor 4, p107/p130-binding [E2F4], Homo sapiens G-2 and S-phase expressed 1 [GTSE1], Damage-regulated autophagy modulator [DRAM], Homo sapiens cadherin 1, type 1,E-cadherin (epithelial) [CDH1], Homo sapiens snail homolog 1 (Drosophila) [SNAI1], Homo sapiens matrix metallopeptidase 2 [MMP2], and Homo sapiens matrix metallopeptidase 9 [MMP9]) was confirmed with quantitative reverse-transcriptase polymerase chain reaction in post-silenced RB cells. Zymographic analysis revealed that the increase in MMP mRNA expression in the post-silenced RB cells did not correlate with corresponding enzyme activity.

Conclusions: Our study revealed molecular regulatory changes induced by HMGA2 silencing in RB cancer cells, offering mechanistic insights into the anticancer potential. HMGA2 may be considered a promising candidate for gene silencing therapy in RB.

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Related in: MedlinePlus

Effect of small interfering RNA on the expression of p21, p53, and caspase 3 in retinoblastoma (Y79, WERI Rb1) cells in vitro. A: western blot analysis demonstrates a marked increase in p21 and p53 expression in Y79 cells treated with HMGA2-siRNA (lane 1), and p21 and p53 expression of HMGA2 in non-transfected Y79 cells (lane 2), a marked increase in p21 and p53 expression in WERI Rb 1 cells treated with HMGA2 siRNA (lane 3), and p21 and p53 expression in non-transfected WERI Rb1 cells (lane 4). B: The graphical representation of increased caspase 3 expression in HMGA2 siRNA transfected RB cells is compared to the non-transfected RB cells with flow cytometric analyses.
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f6: Effect of small interfering RNA on the expression of p21, p53, and caspase 3 in retinoblastoma (Y79, WERI Rb1) cells in vitro. A: western blot analysis demonstrates a marked increase in p21 and p53 expression in Y79 cells treated with HMGA2-siRNA (lane 1), and p21 and p53 expression of HMGA2 in non-transfected Y79 cells (lane 2), a marked increase in p21 and p53 expression in WERI Rb 1 cells treated with HMGA2 siRNA (lane 3), and p21 and p53 expression in non-transfected WERI Rb1 cells (lane 4). B: The graphical representation of increased caspase 3 expression in HMGA2 siRNA transfected RB cells is compared to the non-transfected RB cells with flow cytometric analyses.

Mentions: In the current study, we found deregulation of genes associated with the mitogen-activated protein (MAP) kinase, Ras, Janus kinase/signal transducers and activators of transcription (Jak/STAT), and p53 signaling pathways. The downregulated genes involved in the MAP kinase pathway are CRK, ELK1, MYC, CDC25B, and GRB2. The downregulated genes involved in the Ras pathway are Rac1, RALGDS, and ELK1. The downregulated genes involved in the Jak/STAT pathway are SPREAD2, PIAS3, CCND2, and CNTFR. The increased levels of ATM, PUMA /BB3, PTEN, and DRAM, the downstream molecules of p53-mediated apoptosis, reveal the modulation of cell apoptosis. The role of p53-mediated apoptosis was confirmed by the overexpression of p53 and p21 proteins as well as the caspase 3 protein in HMGA2-silenced Y79 and WERI Rb1 cells (Figure 6A,B).


Molecular deregulation induced by silencing of the high mobility group protein A2 gene in retinoblastoma cells.

Venkatesan N, Krishnakumar S, Deepa PR, Deepa M, Khetan V, Reddy MA - Mol. Vis. (2012)

Effect of small interfering RNA on the expression of p21, p53, and caspase 3 in retinoblastoma (Y79, WERI Rb1) cells in vitro. A: western blot analysis demonstrates a marked increase in p21 and p53 expression in Y79 cells treated with HMGA2-siRNA (lane 1), and p21 and p53 expression of HMGA2 in non-transfected Y79 cells (lane 2), a marked increase in p21 and p53 expression in WERI Rb 1 cells treated with HMGA2 siRNA (lane 3), and p21 and p53 expression in non-transfected WERI Rb1 cells (lane 4). B: The graphical representation of increased caspase 3 expression in HMGA2 siRNA transfected RB cells is compared to the non-transfected RB cells with flow cytometric analyses.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472926&req=5

f6: Effect of small interfering RNA on the expression of p21, p53, and caspase 3 in retinoblastoma (Y79, WERI Rb1) cells in vitro. A: western blot analysis demonstrates a marked increase in p21 and p53 expression in Y79 cells treated with HMGA2-siRNA (lane 1), and p21 and p53 expression of HMGA2 in non-transfected Y79 cells (lane 2), a marked increase in p21 and p53 expression in WERI Rb 1 cells treated with HMGA2 siRNA (lane 3), and p21 and p53 expression in non-transfected WERI Rb1 cells (lane 4). B: The graphical representation of increased caspase 3 expression in HMGA2 siRNA transfected RB cells is compared to the non-transfected RB cells with flow cytometric analyses.
Mentions: In the current study, we found deregulation of genes associated with the mitogen-activated protein (MAP) kinase, Ras, Janus kinase/signal transducers and activators of transcription (Jak/STAT), and p53 signaling pathways. The downregulated genes involved in the MAP kinase pathway are CRK, ELK1, MYC, CDC25B, and GRB2. The downregulated genes involved in the Ras pathway are Rac1, RALGDS, and ELK1. The downregulated genes involved in the Jak/STAT pathway are SPREAD2, PIAS3, CCND2, and CNTFR. The increased levels of ATM, PUMA /BB3, PTEN, and DRAM, the downstream molecules of p53-mediated apoptosis, reveal the modulation of cell apoptosis. The role of p53-mediated apoptosis was confirmed by the overexpression of p53 and p21 proteins as well as the caspase 3 protein in HMGA2-silenced Y79 and WERI Rb1 cells (Figure 6A,B).

Bottom Line: These deregulated genes were compared for their constitutive expression in primary RB tumors (n=10).Zymographic analysis revealed that the increase in MMP mRNA expression in the post-silenced RB cells did not correlate with corresponding enzyme activity.HMGA2 may be considered a promising candidate for gene silencing therapy in RB.

View Article: PubMed Central - PubMed

Affiliation: Department of Ocular pathology, Vision Research Foundation, Sankara Nethralaya, Chennai, India.

ABSTRACT

Aim: To explore the molecular mechanisms deregulated by high mobility group protein A2 (HMGA2) gene silencing in retinoblastoma (RB) cells.

Methods: Synthetic anti-HMGA2 short interfering RNA (siRNA) was used to silence the HMGA2 gene in cultured Y79 RB cells that were subjected to whole genome microarray analysis. The expression of differentially regulated key genes was confirmed with quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) in post-silenced RB cell lines (Y79 and WERI Rb1). These deregulated genes were compared for their constitutive expression in primary RB tumors (n=10). Zymographic determination of matrix metalloproteinase (MMP) activity was performed in RB cells. A cell cycle assay and a proliferation assay were performed in post-transfected RB cells.

Results: HMGA2 gene silencing in cultured RB cells results in reduced cell proliferation and transition in the G1/S phase. The whole genome microarray analysis of HMGA2 silenced Y79 cells revealed overall upregulation of 1,132 genes (≥ 1.0 fold) and downregulation of 1,562 genes (≤ -1.0 fold). Specific quantitative pathway analysis of the deregulated genes (using Biointerpreter) revealed 150 upregulated genes and 77 downregulated genes (≥ 1.0 fold) involved in vital pathways, namely, mitogen-activated protein kinase, Janus kinase/signal transducers and activators of transcription, Ras pathway, Ras-induced extracellular signal-regulated protein kinases 1 and 2, and tumor protein p53. The differential expression of genes obtained from microarray analysis (Homo sapiens ELK1, member of ETS oncogene family [ELK1], Homo sapiens cyclin-dependent kinase 6 [CDK6], Homo sapiens E2F transcription factor 4, p107/p130-binding [E2F4], Homo sapiens G-2 and S-phase expressed 1 [GTSE1], Damage-regulated autophagy modulator [DRAM], Homo sapiens cadherin 1, type 1,E-cadherin (epithelial) [CDH1], Homo sapiens snail homolog 1 (Drosophila) [SNAI1], Homo sapiens matrix metallopeptidase 2 [MMP2], and Homo sapiens matrix metallopeptidase 9 [MMP9]) was confirmed with quantitative reverse-transcriptase polymerase chain reaction in post-silenced RB cells. Zymographic analysis revealed that the increase in MMP mRNA expression in the post-silenced RB cells did not correlate with corresponding enzyme activity.

Conclusions: Our study revealed molecular regulatory changes induced by HMGA2 silencing in RB cancer cells, offering mechanistic insights into the anticancer potential. HMGA2 may be considered a promising candidate for gene silencing therapy in RB.

Show MeSH
Related in: MedlinePlus