Analyses of the Transcriptome and Metabolome Demonstrate That HIF1α Mediates Altered Tumor Metabolism in Clear Cell Renal Cell Carcinoma

Abstract

Hypoxia inducible factor 1 alpha (HIF1α) is a transcription factor that is frequently stabilized and active in human clear cell renal cell carcinoma (ccRCC). We have found that constitutively active HIF1α is sufficient to cause neoplastic transformation in a murine model of ccRCC termed the TRACK model. RNA sequencing (RNAseq) and untargeted metabolomics analyses of samples from TRACK kidneys demonstrate that HIF1α activates the transcription of genes that cause increased glucose uptake, glycolysis, and lactate production, as well as a decrease in the flux of pyruvate entering the tricarboxylic acid (TCA) cycle and a decrease in oxidative phosphorylation; these changes are identical to those observed in human ccRCC samples. These studies show that a constitutively active HIF1α promotes tumorigenesis in TRACK mice by mediating a metabolic switch to aerobic glycolysis, i.e., the Warburg effect, and suggest that TRACK mice are a valid model to test novel therapies targeting metabolic changes to inhibit human ccRCC.

Role of NADH Dehydrogenase (Ubiquinone) 1 Alpha Subcomplex 4-Like 2 in Clear Cell Renal Cell Carcinoma

“…We previously demonstrated that expression of a constitutively active HIF1α mutant protein exclusively in kidney proximal tubule cells is sufficient to drive a program of early tumorigenesis in a murine model of ccRCC called the TRACK ( TRA nsgenic model of C ancer of the K idney) model (9). TRACK mice exhibit increased expression of HIF1α target genes that are associated with a shift in metabolism from mitochondrial oxidative phosphorylation to increased aerobic glycolysis and lactate production, similar to what is observed in human ccRCC (10). Additionally, our metabolomics data show that TRACK kidneys and human ccRCC samples have increased levels of glycolytic intermediates and lactate, and decreased levels of metabolites of the TCA cycle (10).…”

“…TRACK mice exhibit increased expression of HIF1α target genes that are associated with a shift in metabolism from mitochondrial oxidative phosphorylation to increased aerobic glycolysis and lactate production, similar to what is observed in human ccRCC (10). Additionally, our metabolomics data show that TRACK kidneys and human ccRCC samples have increased levels of glycolytic intermediates and lactate, and decreased levels of metabolites of the TCA cycle (10). Similar to our findings in the TRACK kidneys, Arreola et al .…”

“…Cells were plated on 10-cm plates and metabolites were extracted following established protocols using 80% methanol (cooled to −80°C) (10, 26). Metabolites were dried using a SpeedVac (Savant) and stored at −80°C until being shipped on dry ice to the Metabolomics Core Facility at Beth Israel Deaconess Medical Center (BIDMC).…”

“…NDUFA4L2 is one of the most highly expressed genes in almost all ccRCC samples compared to healthy kidney tissue, according to several sets of microarray data from the Oncomine database (12–15) and RNA sequencing (RNAseq) data from The Cancer Genome Atlas (TCGA) (16, 17), and NDUFA4L2 expression is similarly increased by >50 fold in TRACK kidneys (10, 16). Hypoxia induces NDUFA4L2 expression via a mechanism involving HIF1α, but not HIF2α (18).…”

Novel targets in altered tumour metabolism in kidney cancer

“…We have also recently reported metabolomics and transcriptomics analyses of kidneys from the HIF1αdriven TRACK (TRAnsgenic model of Cancer of the Kidney) murine model of RCC 5 and found that HIF1α stimulates a shift from the TCA cycle to aerobic glycolysis. 6 Nature Reviews | Urology Kidney cancer cells exhibit increased glucose uptake, glycolysis and lactate production, with an associated decrease in pyruvate entering the TCA cycle. These pathways can be targeted by inhibiting glucose uptake or the enzymes hexokinase, pyruvate kinase and lactate dehydrogenase.…”