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Metastasis-associated protein 1 is an upstream regulator of DNMT3a and stimulator of insulin-growth factor binding protein-3 in breast cancer

View Article: PubMed Central - PubMed

ABSTRACT

Despite a recognized role of DNA methyltransferase 3a (DNMT3a) in human cancer, the nature of its upstream regulator(s) and relationship with the master chromatin remodeling factor MTA1, continues to be poorly understood. Here, we found an inverse relationship between the levels of MTA1 and DNMT3a in human cancer and that high levels of MTA1 in combination of low DNMT3a status correlates well with poor survival of breast cancer patients. We discovered that MTA1 represses DNMT3a expression via HDAC1/YY1 transcription factor complex. Because IGFBP3 is an established target of DNMT3a, we investigated the effect of MTA1 upon IGFBP3 expression, and found a coactivator role of MTA1/c-Jun/Pol II coactivator complex upon the IGFBP3 transcription. In addition, MTA1 overexpression correlates well with low levels of DNMT3a which, in turn also correlates with a high IGFBP3 status in breast cancer patients and predicts a poor clinical outcome for breast cancer patients. These findings suggest that MTA1 could regulate the expression of IGFBP3 in both DNMT3a-dependent and -independent manner. Together findings presented here recognize an inherent role of MTA1 as a modifier of DNMT3a and IGFBP3 expression, and consequently, the role of MTA1-DNMT3a-IGFBP3 axis in breast cancer progression.

No MeSH data available.


MTA1 regulates DNMT3a expression.(A) Western blot showing the levels of DNMT3a upon overexpression and silencing of MTA1 in MCF-7 cells. β-actin is showed as a control. (B) Western blot showing the levels of DNMT3a upon overexpression and silencing MTA1 along with the control in SKBR-3 cells. Vinculin is showed as a control. (C) Western blot showing the endogenous levels of DNMT3a and MTA1 and Vinculin in the wild type and MTA1−/− MEFs. Vinculin is used as a control. (D) Western blot showing changes in the levels of DNMT3a upon overexpression or silencing MTA1 in HCT116 cells. β-actin and vinculin serve as loading controls, respectively.
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f2: MTA1 regulates DNMT3a expression.(A) Western blot showing the levels of DNMT3a upon overexpression and silencing of MTA1 in MCF-7 cells. β-actin is showed as a control. (B) Western blot showing the levels of DNMT3a upon overexpression and silencing MTA1 along with the control in SKBR-3 cells. Vinculin is showed as a control. (C) Western blot showing the endogenous levels of DNMT3a and MTA1 and Vinculin in the wild type and MTA1−/− MEFs. Vinculin is used as a control. (D) Western blot showing changes in the levels of DNMT3a upon overexpression or silencing MTA1 in HCT116 cells. β-actin and vinculin serve as loading controls, respectively.

Mentions: Because of the significant clinical implications of the noted inverse MTA1-DNMT3a relationship, we next investigated the mechanism of MTA1 regulation of DNMT3a expression in cancer cells. To experimentally validate the noticed, presumed negative regulation of DNMT3a expression by MTA1, we selected breast cancer model system for subsequent studies. First, we examined the effect of overexpression or depletion of MTA1 on the status of DNMT3a in breast cancer cells. We found that MTA1 overexpression results in a marked reduction in the level of DNMT3a, while MTA1 silencing leads to an increased DNMT3a expression in breast cancer MCF-7 and SKBR-3 cells (Fig. 2A,B). Consistent with these results, we found that the genetic depletion of MTA1 in murine embryonic fibroblasts (MEF) accompanies with DNMT3a upregulation as compared to the level in the wild-type MEFs (Fig. 2C). Similar to breast cancer cells, MTA1 silencing or overexpression in HCT116 colon cancer cells also leads to upregulation or downregulation of DNMT3a, respectively (Fig. 2D).


Metastasis-associated protein 1 is an upstream regulator of DNMT3a and stimulator of insulin-growth factor binding protein-3 in breast cancer
MTA1 regulates DNMT3a expression.(A) Western blot showing the levels of DNMT3a upon overexpression and silencing of MTA1 in MCF-7 cells. β-actin is showed as a control. (B) Western blot showing the levels of DNMT3a upon overexpression and silencing MTA1 along with the control in SKBR-3 cells. Vinculin is showed as a control. (C) Western blot showing the endogenous levels of DNMT3a and MTA1 and Vinculin in the wild type and MTA1−/− MEFs. Vinculin is used as a control. (D) Western blot showing changes in the levels of DNMT3a upon overexpression or silencing MTA1 in HCT116 cells. β-actin and vinculin serve as loading controls, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385551&req=5

f2: MTA1 regulates DNMT3a expression.(A) Western blot showing the levels of DNMT3a upon overexpression and silencing of MTA1 in MCF-7 cells. β-actin is showed as a control. (B) Western blot showing the levels of DNMT3a upon overexpression and silencing MTA1 along with the control in SKBR-3 cells. Vinculin is showed as a control. (C) Western blot showing the endogenous levels of DNMT3a and MTA1 and Vinculin in the wild type and MTA1−/− MEFs. Vinculin is used as a control. (D) Western blot showing changes in the levels of DNMT3a upon overexpression or silencing MTA1 in HCT116 cells. β-actin and vinculin serve as loading controls, respectively.
Mentions: Because of the significant clinical implications of the noted inverse MTA1-DNMT3a relationship, we next investigated the mechanism of MTA1 regulation of DNMT3a expression in cancer cells. To experimentally validate the noticed, presumed negative regulation of DNMT3a expression by MTA1, we selected breast cancer model system for subsequent studies. First, we examined the effect of overexpression or depletion of MTA1 on the status of DNMT3a in breast cancer cells. We found that MTA1 overexpression results in a marked reduction in the level of DNMT3a, while MTA1 silencing leads to an increased DNMT3a expression in breast cancer MCF-7 and SKBR-3 cells (Fig. 2A,B). Consistent with these results, we found that the genetic depletion of MTA1 in murine embryonic fibroblasts (MEF) accompanies with DNMT3a upregulation as compared to the level in the wild-type MEFs (Fig. 2C). Similar to breast cancer cells, MTA1 silencing or overexpression in HCT116 colon cancer cells also leads to upregulation or downregulation of DNMT3a, respectively (Fig. 2D).

View Article: PubMed Central - PubMed

ABSTRACT

Despite a recognized role of DNA methyltransferase 3a (DNMT3a) in human cancer, the nature of its upstream regulator(s) and relationship with the master chromatin remodeling factor MTA1, continues to be poorly understood. Here, we found an inverse relationship between the levels of MTA1 and DNMT3a in human cancer and that high levels of MTA1 in combination of low DNMT3a status correlates well with poor survival of breast cancer patients. We discovered that MTA1 represses DNMT3a expression via HDAC1/YY1 transcription factor complex. Because IGFBP3 is an established target of DNMT3a, we investigated the effect of MTA1 upon IGFBP3 expression, and found a coactivator role of MTA1/c-Jun/Pol II coactivator complex upon the IGFBP3 transcription. In addition, MTA1 overexpression correlates well with low levels of DNMT3a which, in turn also correlates with a high IGFBP3 status in breast cancer patients and predicts a poor clinical outcome for breast cancer patients. These findings suggest that MTA1 could regulate the expression of IGFBP3 in both DNMT3a-dependent and -independent manner. Together findings presented here recognize an inherent role of MTA1 as a modifier of DNMT3a and IGFBP3 expression, and consequently, the role of MTA1-DNMT3a-IGFBP3 axis in breast cancer progression.

No MeSH data available.