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Life sciences

Epigenetic regulation of protein tyrosine phosphatase PTPN12 in triple-negative breast cancer.


PMID 25817229

Abstract

The present study showed that the expression of PTPN12 is epigenetically regulated. 5-Azacytidine (5-Azac), a DNA hypomethylating agent, significantly increased the expression of PTPN12 at low concentrations (1μM and 2.5μM) and decreased the expression of PTPN12 at 5μM in the MDA-MB-231 and BT-549 triple-negative breast cancer cell lines. Human MCF-7, MDA-MB-231 and BT-549 cells were exposed to different concentrations of 5-Azac for 24 and 48h. RT-PCR was performed to determine the mRNA expression of PTPN12, E-cadherin and miRNA-124. Western blotting was performed to assess the protein expression of various proteins, including PTPN12, E-cadherin, DNMT and PARP. 5-Azac, a DNA hypomethylating agent, significantly increased the expression of PTPN12 at low concentrations (1μM and 2.5μM) and decreased PTPN12 expression at 5μM. We provide the first evidence that PTPN12 expression is epigenetically regulated and that it is up-regulated at a lower dose of a DNMT1 inhibitor in MDA-MB-231 and BT-549 cells. Interestingly, the levels of miRNA-124 were increased only at 5μM, the concentration at which PTPN12 expression was suppressed. To the best of our knowledge, this is the first report that highlights the therapeutic potential of low-dose 5-Azac for the treatment of TNBC. Therefore, 5-Azac, an agent that has already been tested in acute myeloid leukemia, may be more effective at lower doses for the treatment of triple-negative breast cancer.