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Histone methylase MLL1 has critical roles in tumor growth and angiogenesis and its knockdown suppresses tumor growth in vivo.

ABSTRACT: Mixed lineage leukemias (MLLs) are human histone H3 lysine-4-specific methyl transferases that have critical roles in gene expression, epigenetics and cancer. Herein, we demonstrated that antisense-mediated knockdown of MLL1 induced cell-cycle arrest and apoptosis in cultured cells. Intriguingly, application of MLL1 antisense specifically knocked down MLL1 in vivo and suppressed the growth of xenografted cervical tumor implanted in nude mouse. MLL1 knockdown downregulated various growth and angiogenic factors, such as HIF1?, VEGF and CD31, in tumor tissue affecting tumor growth. MLL1 is overexpressed along the line of vascular network and localized adjacent to endothelial cell layer expressing CD31, indicating potential roles of MLL1 in vasculogenesis. MLL1 is also overexpressed in the hypoxic regions along with HIF1?. Overall, our studies demonstrated that MLL1 is a key factor in hypoxia signaling, vasculogenesis and tumor growth, and its depletion suppresses tumor growth in vivo, indicating its potential in novel cancer therapy.

SUBMITTER: Ansari KI

PROVIDER: S-EPMC3511651 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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Histone methylase MLL1 has critical roles in tumor growth and angiogenesis and its knockdown suppresses tumor growth in vivo.

Ansari K I KI Kasiri S S Mandal S S SS

Oncogene 20120827 28

Mixed lineage leukemias (MLLs) are human histone H3 lysine-4-specific methyl transferases that have critical roles in gene expression, epigenetics and cancer. Herein, we demonstrated that antisense-mediated knockdown of MLL1 induced cell-cycle arrest and apoptosis in cultured cells. Intriguingly, application of MLL1 antisense specifically knocked down MLL1 in vivo and suppressed the growth of xenografted cervical tumor implanted in nude mouse. MLL1 knockdown downregulated various growth and angi ...[more]

PMID: 22926525

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Project description:To investigate the effects of osteopontin (OPN) gene expression knockdown on colon cancer Lovo cells in vitro.Four candidate small interfering RNA (siRNA) constructs targeting the OPN gene and a scrambled control sequence (NC-siRNA) were synthesized and inserted into a pGPU6/GFP/Neo expression vector. After confirmation by restriction enzyme digestion and DNA sequencing, the recombinant plasmids were subsequently transfected into a human colon cancer cell line (Lovo) using a liposome transfection method. Stably transfected cells were maintained with G418 selection and referred to as Lovo-OPN-1, -2, -3, -4, and Lovo-NC cells. Knockdown efficiency of each of the four siRNA constructs was determined by real-time reverse transcription polymerase chain reaction assays and western blotting, and the construct with the most effective silencing was used for subsequent experiments. Cell proliferation, adhesion, and Matrigel invasion assays were performed to analyze the effects of OPN knockdown in stably transfected Lovo cells. The levels of four angiogenic factors, namely vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, MMP-9 and urokinase plasminogen activator were detected by enzyme-linked immunosorbent assays (ELISA).Recombinant vectors containing OPN-specific and scrambled siRNA sequences were successfully constructed and stably transfected into Lovo cells. Compared with the control Lovo and Lovo-NC cells, the levels of OPN mRNA and protein expression in Lovo-OPN-1, -2, -3, and -4 were significantly reduced (all P < 0.05), with the most efficient reduction observed in Lovo-OPN-4 cells (P < 0.05). Relative to untransfected Lovo cells, OPN mRNA expression levels in Lovo-NC and Lovo-OPN-4 cells were 1.008 ± 0.067 and 0.160 ± 0.023, respectively. The relative OPN protein expression levels in Lovo, Lovo-NC, and Lovo-OPN-4 cells were 3.024 ± 0.211, 2.974 ± 0.630, and 0.121 ± 0.008, respectively. Moreover, transfection with the scrambled sequence had no effect on the expression of OPN. After 24, 48, 72, and 96 h of cultivation, absorption values at 450 nm to assess proliferation of Lovo-OPN-4 cells were 0.210 ± 0.017, 0.247 ± 0.024, 0.314 ± 0.037, and 0.359 ± 0.043, respectively, which were significantly lower than those of Lovo (0.244 ± 0.031, 0.313 ± 0.024, 0.513 ± 0.048 and 0.783 ± 0.051) and Lovo-NC cells (0.241 ± 0.029, 0.309 ± 0.022, 0.563 ± 0.023, and 0.735 ± 0.067) (all P < 0.05). The absorption values at 595 nm, which were measured in a cell adhesion assay, showed that adhesion of Lovo-OPN-4 cells (0.215 ± 0.036) was significantly decreased compared to Lovo (0.490 ± 0.037) and Lovo-NC cells (0.462 ± 0.043) (P < 0.05). The number of invasive Lovo-OPN-4 cells (16.1 ± 1.9) was also significantly decreased compared to Lovo (49.9 ± 5.4) and Lovo-NC cells (48.8 ± 4.5) (P < 0.05). ELISA assays showed significant reductions in Lovo-OPN-4 cells compared to Lovo and Lovo-NC cells with regard to the expression of VEGF (1687.85 ± 167.84 ng/L vs 2348.54 ± 143.80 ng/L and 2284.39 ± 138.62 ng/L, respectively), MMP-2 (2966.07 ± 177.36 ?g/L vs 4084.74 ± 349.54 ?g/L and 4011.41 ± 424.48 ?g/L, respectively), MMP-9 (3782.89 ± 300.64 ?g/L vs 5062.90 ± 303.02 ?g/L and 4986.38 ± 300.75 ?g/L, respectively) and uPA (1152.69 ± 120.79 ?g/L vs 1380.90 ± 147.25 ?g/L and 1449.80 ± 189.92 ?g/L, respectively) (all P < 0.05).Knockdown of OPN gene expression suppresses colon cancer cell growth, adherence, invasion, and expression of angiogenic factors.

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Histone methylase MLL1 has critical roles in tumor growth and angiogenesis and its knockdown suppresses tumor growth in vivo.

Publications

Histone methylase MLL1 has critical roles in tumor growth and angiogenesis and its knockdown suppresses tumor growth in vivo.

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