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MDGA2 is a novel tumour suppressor cooperating with DMAP1 in gastric cancer and is associated with disease outcome

View Article: PubMed Central - PubMed

ABSTRACT

Background: Using the promoter methylation assay, we have shown that MDGA2 (MAM domain containing glycosylphosphatidylinositol anchor 2) is preferentially methylated in gastric cancer. We analysed its biological effects and prognostic significance in gastric cancer.

Methods: MDGA2 methylation status was evaluated by combined bisulfite restriction analysis and bisulfite genomic sequencing. The effects of MDGA2 re-expression or knockdown on cell proliferation, apoptosis and the cell cycle were determined. MDGA2 interacting protein was identified by mass spectrometry and MDGA2-related cancer pathways by reporter activity and PCR array analyses. The clinical impact of MDGA2 was assessed in 218 patients with gastric cancer.

Results: MDGA2 was commonly silenced in gastric cancer cells (10/11) and primary gastric cancers due to promoter hypermethylation. MDGA2 significantly inhibited cell proliferation by causing G1–S cell cycle arrest and inducing cell apoptosis in vitro, and suppressed xenograft tumour growth in both subcutaneous and orthotopic xenograft mouse models (both p<0.001). The anti-tumorigenic effect of MDGA2 was mediated through direct stabilising of DNA methyltransferase 1 associated protein 1 (DMAP1), which played a tumour suppressive role in gastric cancer. This interaction activated their downstream key elements of p53/p21 signalling cascades. Moreover, promoter methylation of MDGA2 was detected in 62.4% (136/218) of gastric cancers. Multivariate analysis showed that patients with MDGA2 hypermethylation had a significantly decreased survival (p=0.005). Kaplan–Meier survival curves showed that MDGA2 hypermethylation was significantly associated with shortened survival in patients with early gastric cancer.

Conclusions: MDGA2 is a critical tumour suppressor in gastric carcinogenesis; its hypermethylation is an independent prognostic factor in patients with gastric cancer.

No MeSH data available.


Related in: MedlinePlus

Suppression of gastric cancer growth by MDGA2 is partly dependent on DNA methyltransferase 1 associated protein 1 (DMAP1). (A) Expression of MDGA2 was not affected by DMAP1. (B) Cell viability of AGS and BGC823 cells by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. (C) Colony formation in AGS and BGC823 cells. (D) DMAP1 was knocked down in cells with stable MDGA2 over-expression by short interference RNA (siRNA) transfection. (E) Effect on gastric cancer cell growth by different levels of MDGA2 and DMAP1. Cell growth was monitored by the xCelligence system. Data shown are mean±SD. (F) Effect of different levels of MDGA2 and DMAP1 on colony formation ability of gastric cancer cells. *p<0.05, **p<0.001, ***p<0.0001.
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GUTJNL2015309276F6: Suppression of gastric cancer growth by MDGA2 is partly dependent on DNA methyltransferase 1 associated protein 1 (DMAP1). (A) Expression of MDGA2 was not affected by DMAP1. (B) Cell viability of AGS and BGC823 cells by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. (C) Colony formation in AGS and BGC823 cells. (D) DMAP1 was knocked down in cells with stable MDGA2 over-expression by short interference RNA (siRNA) transfection. (E) Effect on gastric cancer cell growth by different levels of MDGA2 and DMAP1. Cell growth was monitored by the xCelligence system. Data shown are mean±SD. (F) Effect of different levels of MDGA2 and DMAP1 on colony formation ability of gastric cancer cells. *p<0.05, **p<0.001, ***p<0.0001.

Mentions: We examined the importance of DMAP1 in MDGA2-mediated tumour suppressive function. Unlike the changes in DMAP1 following upregulation or downregulation of MDGA2, inversely, MDGA2 expression was not changed following overexpression or knockdown of DMAP1 in AGS and BGC823 cells (figure 6A), suggesting that DMAP1 is a downstream effector of MDGA2. In addition, ectopic expression of DMAP1 significantly suppressed cell growth (figure 6B) and colony formation ability (figure 6C) in AGS and BGC823 cells. Moreover, the inhibitory effect on cell growth and colony formation ability by MDGA2 overexpression in AGS and BGC823 cells was significantly attenuated by DMAP1 knockdown (figure 6D–F). These results collectively indicate that MDGA2 plays a tumour suppressive function, at least in part, depending on DMAP1 in gastric cancer.


MDGA2 is a novel tumour suppressor cooperating with DMAP1 in gastric cancer and is associated with disease outcome
Suppression of gastric cancer growth by MDGA2 is partly dependent on DNA methyltransferase 1 associated protein 1 (DMAP1). (A) Expression of MDGA2 was not affected by DMAP1. (B) Cell viability of AGS and BGC823 cells by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. (C) Colony formation in AGS and BGC823 cells. (D) DMAP1 was knocked down in cells with stable MDGA2 over-expression by short interference RNA (siRNA) transfection. (E) Effect on gastric cancer cell growth by different levels of MDGA2 and DMAP1. Cell growth was monitored by the xCelligence system. Data shown are mean±SD. (F) Effect of different levels of MDGA2 and DMAP1 on colony formation ability of gastric cancer cells. *p<0.05, **p<0.001, ***p<0.0001.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036270&req=5

GUTJNL2015309276F6: Suppression of gastric cancer growth by MDGA2 is partly dependent on DNA methyltransferase 1 associated protein 1 (DMAP1). (A) Expression of MDGA2 was not affected by DMAP1. (B) Cell viability of AGS and BGC823 cells by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. (C) Colony formation in AGS and BGC823 cells. (D) DMAP1 was knocked down in cells with stable MDGA2 over-expression by short interference RNA (siRNA) transfection. (E) Effect on gastric cancer cell growth by different levels of MDGA2 and DMAP1. Cell growth was monitored by the xCelligence system. Data shown are mean±SD. (F) Effect of different levels of MDGA2 and DMAP1 on colony formation ability of gastric cancer cells. *p<0.05, **p<0.001, ***p<0.0001.
Mentions: We examined the importance of DMAP1 in MDGA2-mediated tumour suppressive function. Unlike the changes in DMAP1 following upregulation or downregulation of MDGA2, inversely, MDGA2 expression was not changed following overexpression or knockdown of DMAP1 in AGS and BGC823 cells (figure 6A), suggesting that DMAP1 is a downstream effector of MDGA2. In addition, ectopic expression of DMAP1 significantly suppressed cell growth (figure 6B) and colony formation ability (figure 6C) in AGS and BGC823 cells. Moreover, the inhibitory effect on cell growth and colony formation ability by MDGA2 overexpression in AGS and BGC823 cells was significantly attenuated by DMAP1 knockdown (figure 6D–F). These results collectively indicate that MDGA2 plays a tumour suppressive function, at least in part, depending on DMAP1 in gastric cancer.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Using the promoter methylation assay, we have shown that MDGA2 (MAM domain containing glycosylphosphatidylinositol anchor 2) is preferentially methylated in gastric cancer. We analysed its biological effects and prognostic significance in gastric cancer.

Methods: MDGA2 methylation status was evaluated by combined bisulfite restriction analysis and bisulfite genomic sequencing. The effects of MDGA2 re-expression or knockdown on cell proliferation, apoptosis and the cell cycle were determined. MDGA2 interacting protein was identified by mass spectrometry and MDGA2-related cancer pathways by reporter activity and PCR array analyses. The clinical impact of MDGA2 was assessed in 218 patients with gastric cancer.

Results: MDGA2 was commonly silenced in gastric cancer cells (10/11) and primary gastric cancers due to promoter hypermethylation. MDGA2 significantly inhibited cell proliferation by causing G1&ndash;S cell cycle arrest and inducing cell apoptosis in vitro, and suppressed xenograft tumour growth in both subcutaneous and orthotopic xenograft mouse models (both p&lt;0.001). The anti-tumorigenic effect of MDGA2 was mediated through direct stabilising of DNA methyltransferase 1 associated protein 1 (DMAP1), which played a tumour suppressive role in gastric cancer. This interaction activated their downstream key elements of p53/p21 signalling cascades. Moreover, promoter methylation of MDGA2 was detected in 62.4% (136/218) of gastric cancers. Multivariate analysis showed that patients with MDGA2 hypermethylation had a significantly decreased survival (p=0.005). Kaplan&ndash;Meier survival curves showed that MDGA2 hypermethylation was significantly associated with shortened survival in patients with early gastric cancer.

Conclusions: MDGA2 is a critical tumour suppressor in gastric carcinogenesis; its hypermethylation is an independent prognostic factor in patients with gastric cancer.

No MeSH data available.


Related in: MedlinePlus