Tumour cells fulfil the bioenergetic and biosynthetic needs of proliferation using the available environmental metabolites. Metabolic adaptation to hypoxia causes decreased mitochondrial function and increased lactate production. This work examines the biological importance of the hypoxia-inducible inhibitory phosphorylations on the pyruvate dehydrogenase E1a subunit. Pancreatic cancer cell lines were genetically manipulated to alter the net phosphorylation of PDH E1a through reduced kinase expression or enhanced phosphatase expression. The modified cells were tested for hypoxic changes in phosphorylated E1a, mitochondrial metabolism and growth as xenografted tumours. Even though there are four PDHK genes, PDHK1 is essential for inhibitory PDH phosphorylation of E1a at serine 232, is partially responsible for modification of serines 293 and 300, and these phosphorylations are necessary for model tumour growth. In order to determine the clinical relevance, a cohort of head and neck cancer patient biopsies was examined for phosphorylated E1a and expression of PDHK1. Patients with detectable 232 phosphorylation or expression of PDHK1 tend to have worse clinical outcome. These data show that PDHK1 activity is unique and non-redundant in the family of PHDK enzymes and a PDHK1 specific inhibitor would therefore have anti-cancer activity with reduced chance of side effects from inhibition of other PDHKs.
View details for DOI 10.1038/srep31146
View details for PubMedID 27498883
View details for PubMedCentralID PMC4976358