Tissue-specific expression of the human pyruvate dehydrogenase alpha (Pdha-1)/chloramphenicol acetyltransferase fusion gene in transgenic mice

Targeting pyruvate dehydrogenase kinase signaling in the development of effective cancer therapy

Pyruvate is irreversibly decarboxylated to acetyl coenzyme A by mitochondrial pyruvate dehydrogenase complex (PDC). Decarboxylation of pyruvate is considered a crucial step in cell metabolism and energetics. The cancer cells prefer aerobic glycolysis rather than mitochondrial oxidation of pyruvate. This attribute of cancer cells allows them to sustain under indefinite proliferation and growth. Pyruvate dehydrogenase kinases (PDKs) play critical roles in many diseases because they regulate PDC activity. Recent findings suggest an altered metabolism of cancer cells is associated with impaired mitochondrial function due to PDC inhibition. PDKs inhibit the PDC activity via phosphorylation of the E1a subunit and subsequently cause a glycolytic shift. Thus, inhibition of PDK is an attractive strategy in anticancer therapy. This review highlights that PDC/PDK axis could be implicated in cancer's therapeutic management by developing potential small-molecule PDK inhibitors. In recent years, a dramatic increase in the targeting of the PDC/PDK axis for cancer treatment gained an attention from the scientific community. We further discuss breakthrough findings in the PDC-PDK axis. In addition, structural features, functional significance, mechanism of activation, involvement in various human pathologies, and expression of different forms of PDKs (PDK1-4) in different types of cancers are discussed in detail. We further emphasized the gene expression profiling of PDKs in cancer patients to prognosis and therapeutic manifestations. Additionally, inhibition of the PDK/PDC axis by small molecule inhibitors and natural compounds at different clinical evaluation stages has also been discussed comprehensively.

Cloning and characterization of a 5.9 kb promoter region of the human pyruvate dehydrogenase alpha subunit gene

A human genomic clone containing a 5.9 kb promoter region of the human pyruvate dehydrogenase (E1) alpha subunit gene (PDHA1) was isolated from a human X-chromosome library. The nucleotide sequence showed two Alu repeats at the -2880 and -2200 bp regions. Comparison between the -1400 bp E1alpha promoter and the -1241 bp E1beta promoter revealed a 57% homology, with a high degree of homology at the putative protein binding regions in these two promoters. Computer-aided transcription factor binding consensus sequence analysis revealed the presence of PPAR, HOXD, MyoD and other tissue-specific transcription factor binding sites. Promoter function analysis using the chloramphenicol acetyltransferase reporter gene indicated that the -2.2 kb/-1.7 kb and -5.9 kb/-5.2 kb regions of the E1alpha promoter may possess negative regulatory elements which are likely to function in a tissue-specific manner.