MTA1 coregulator regulates LDHA expression and function in breast cancer

https://doi.org/10.1016/j.bbrc.2019.09.078Get rights and content

Highlights

  • MTA1 interacts with the genes of glucose metabolism.

  • MTA1 regulates LDHA expression and its activity.

  • MTA1 interacts with c-Myc.

  • LDHA mediates MTA1 mediated cell motility.

Abstract

Metastasis Associated Protein1 (MTA1) is a chromatin modifier and its expression is significantly associated with prognosis of many cancers. However, its role in glucose metabolism remains unexplored. Here, we report that MTA1 has a significant role in glucose metabolism where MTA1 regulates the LDHA expression and activity and subsequently its function in breast cancer motility. The results showed that MTA1 expression is positively correlated with the LDHA expression levels in breast cancer patients. Further, it was found that MTA1 is necessary for the optimal expression of LDHA. The underlying molecular mechanism involves the interaction of MTA1 with c-Myc and recruitment of MTA1-c-Myc complex on to the LDHA promoter to regulate its transcription. Consequently, the LDHA knock down using LDHA specific siRNA in MCF7 cells stably expressing MTA1 reduced the migration of MCF7 cells. Altogether these findings revealed the regulatory role for MTA1 in LDHA expression and its resulting biological function.

Introduction

Deregulated metabolism is one of the hallmarks of cancer [1]. Cancer cells rely on glycolysis and exhibit reduced use of oxidative phosphorylation (TCA cycle). This phenomenon is known as Warburg effect which results in preferential pyruvate to lactate conversion, a causal event for cancer progression [2]. Additionally, proliferating cancer cells also regulate the glucose and glutamine metabolism pathways, which contribute to precursors for the biosynthesis of lipids and nucleic acids [3,4]. Lactate dehydrogenase A (LDHA), a key enzyme involved in the Warburg effect converts pyruvate to lactate and NADH to NAD+ [5]. Aberrant expression and activation of LDHA is closely associated with many cancers [[6], [7], [8]]. LDHA has been considered as a target for therapeutic intervention due to its critical role in metabolic reprogramming. LDHA expression was activated in various cancers and found to be regulated by several transcriptional factors including c-Myc, HIF1α, CREB, FOXM1, KLF4 and AP1 [[9], [10], [11], [12], [13], [14]]. Higher levels of LDHA were observed in malignant tumors compared to normal tissues [15]. Several studies reported that LDHA plays an important role in cancer cell growth, invasion and metastasis of malignant tumors [[16], [17], [18]]. The LDHA expression is positively correlated with the cancer prognosis and levels are elevated in metastatic cancers and therefore reported as a marker for the diagnosis and prognosis of cancers [19].

MTA1 is a transcriptional regulator and it is identified as a chromatin modifier, as it plays a key role in cancer progression, invasion and metastasis [20,21]. MTA1 was first identified while screening the cDNA library of rat mammary adenocarcinoma metastatic model as an up-regulated gene [22]. Subsequent studies reported that MTA1 is upregulated in almost all types of human cancers and its expression is positively correlated with tumor invasion and migration [20,21]. MTA1 was found to be instrumental in promoting transformation, epithelial to mesenchymal transition and metastasis [[23], [24], [25]]. Down regulation of MTA1 expression suppressed tumor migration and invasion in various cancer models [[26], [27], [28]]. However, it is unclear whether MTA1 has any significant role in glucose metabolism in order to drive the cancer invasion and migration.

In this study, we investigated the role of MTA1 in glucose metabolism. MTA1 was found to interact with the genes involved in glucose metabolism. It was also found that MTA1 regulates LDHA expression and activity in breast cancer. Overexpression of MTA1 increased the expression and activity of LDHA whereas knockdown of MTA1 decreased the expression and activity of LDHA. Further, MTA1 was found to interact with c-Myc and thereby regulates LDHA transcription and in turn the migratory function of LDHA. These findings demonstrated a novel regulatory role for MTA1 in glucose metabolism. Hence, targeting MTA1-LDHA axis could be a potential strategy for breast cancer therapy.

Section snippets

Cell culture, antibodies and other reagents

All the cell lines used in this study were kindly provided by Dr. Rayala Suresh Kumar, IIT Madras, Chennai, India. MCF7, MDA- MB-231 and BT-474 were cultured in DMEM supplemented with 10% fetal bovine serum (FBS) and 1X antibiotic solution. SKBR3 cells and BT549 were cultured in RPMI medium (RPMI 1640) containing 10% FBS and 1 X antibiotic solution. MCF7 stable clones expressing pcDNA3.1 empty vector (MCF7/pcDNA) and MTA1 (MCF-7/MTA1) were generated in our laboratory and were maintained in DMEM

MTA1 interacts with the genes of glucose metabolism

The MTA1-glucose metabolism and transport interactome were extracted from different databases such as STRING, GeneMANIA, BioGRID and INTACT. Only interactions that have experimental evidence through small scale and large-scale experiments such as affinity purification, pull-down assays, co-localization or high-throughput techniques (S1 Dataset) were extracted. Careful examination of the gene ontology terms associated with the MTA1 interactome (S2 Dataset) shows that MTA1 has direct interactions

Discussion

In summary, our findings demonstrate that MTA1 interacts with the genes of glucose metabolism via MYC and MAX. Regulation of LDHA by MTA1 has introduced a new regulatory player in the event of glycolysis, invasion and migration. Although there are several studies on the overexpression of LDHA and its involvement in cancer cell invasion and migration [5,[9], [10], [11], [12], [13], [14],38], not much is known about LDHA transcriptional regulation. In this context, the present study has

Conflicts of interest

The authors declare that they have no conflict interests.

Acknowledgements

Indian Institute of Science Education and Research (IISER) Tirupati and SERB, New Delhi (SB/YS/LS-57/2014) supported this work. We are thankful to Prof. B. J. Rao for fruitful discussions and constant encouragement. We are grateful to Dr. Joel Mackay, University of Sydney, Australia for kindly providing MTA1 construct cloned in pcDNA3. We are thankful to Dr. Nanda Kumar Yellapu, Vector Control Research Center-ICMR, Pondicherry for helping in Molecular docking studies. We are thankful to Dr.

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  • 1

    These authors contributed equally to the present work.

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