Mitochondrial transcription factor A (TFAM) shapes metabolic and invasion gene signatures in melanoma

L F Araujo,J R Plaça,K C Peronni,D B Brotto,B R Muys,E M Espreafico,W A Silva,A P West,C A O Biagi,I I Barros,L C West,A D D Siena,J F Sousa,A M Leopoldino,G A Molfetta

doi:10.1038/s41598-018-31170-6

L F Araujo, J R Plaça + Show 13 more

Open Access

https://doi.org/10.1038/s41598-018-31170-6

Copy DOI

Abstract

Mitochondria are central key players in cell metabolism, and mitochondrial DNA (mtDNA) instability has been linked to metabolic changes that contribute to tumorigenesis and to increased expression of pro-tumorigenic genes. Here, we use melanoma cell lines and metastatic melanoma tumors to evaluate the effect of mtDNA alterations and the expression of the mtDNA packaging factor, TFAM, on energetic metabolism and pro-tumorigenic nuclear gene expression changes. We report a positive correlation between mtDNA copy number, glucose consumption, and ATP production in melanoma cell lines. Gene expression analysis reveals a down-regulation of glycolytic enzymes in cell lines and an up-regulation of amino acid metabolism enzymes in melanoma tumors, suggesting that TFAM may shift melanoma fuel utilization from glycolysis towards amino acid metabolism, especially glutamine. Indeed, proliferation assays reveal that TFAM-down melanoma cell lines display a growth arrest in glutamine-free media, emphasizing that these cells rely more on glutamine metabolism than glycolysis. Finally, our data indicate that TFAM correlates to VEGF expression and may contribute to tumorigenesis by triggering a more invasive gene expression signature. Our findings contribute to the understanding of how TFAM affects melanoma cell metabolism, and they provide new insight into the mechanisms by which TFAM and mtDNA copy number influence melanoma tumorigenesis.

Highlights

Melanoma is a malignancy caused by a stochastic process model of mutation events in melanocytes, pigment-producing cells that can be found in the skin throughout the body and other organs[1]
Mitochondrial genome sequences from each cell line were compared to the revised human Cambridge reference sequence[23], as most of cell lines in our study were derived from patients with no non-neoplastic control available
We undertook several novel approaches to investigate the relationship between mitochondrial DNA (mtDNA) alterations and TFAM expression to energetic metabolism in melanoma cell lines

Summary

Introduction

Melanoma is a malignancy caused by a stochastic process model of mutation events in melanocytes, pigment-producing cells that can be found in the skin throughout the body and other organs[1]. The most mutated driver genes (BRAF, RAS, and NF1) code for members of the MAPK pathway, a canonical signalling pathway that transfers mitogenic signals from growth factors to the nucleus through the activation of Ras GTPase and RAF/MEK/ERK kinases[2]. These gene products act on the same pathway, each mutated subtype has its own gene expression profile[2]. To compensate for the low efficiency in ATP production of aerobic glycolysis, many cancer cells increase glucose uptake In this context, many oncogenes regulate energetic metabolism[8], including other metabolic pathways such as glutamine metabolism. It has been reported that cancer cells with mitochondrial defects rely on glutamine metabolism to replenish tricarboxylic acid cycle intermediates (anaplerosis) essential for maintaining the function of the major biosynthesis pathways[10]

Methods

Results

Conclusion