VHL Dependent Expression of REDD1 and PDK3 Proteins in Clear-cell Renal Cell Carcinoma

The expression pattern of pyruvate dehydrogenase kinases predicts prognosis and correlates with immune exhaustion in clear cell renal cell carcinoma

Renal cancer cells constitute a paradigm of tumor cells with a glycolytic reprogramming which drives metabolic alterations favouring cell survival and transformation. We studied the expression and activity of pyruvate dehydrogenase kinases (PDK1-4), key enzymes of the energy metabolism, in renal cancer cells. We analysed the expression, subcellular distribution and clinicopathological correlations of PDK1-4 by immunohistochemistry of tumor tissue microarray samples from a cohort of 96 clear cell renal cell carcinoma (ccRCC) patients. Gene expression analysis was performed on whole tumor tissue sections of a subset of ccRCC samples. PDK2 and PDK3 protein expression in tumor cells correlated with lower patient overall survival, whereas PDK1 protein expression correlated with higher patient survival. Gene expression analysis revealed molecular association of PDK2 and PDK3 expression with PI3K signalling pathway, as well as with T cell infiltration and exhausted CD8 T cells. Inhibition of PDK by dichloroacetate in human renal cancer cell lines resulted in lower cell viability, which was accompanied by an increase in pAKT. Together, our findings suggest a differential role for PDK enzymes in ccRCC progression, and highlight PDK as actionable metabolic proteins in relation with PI3K signalling and exhausted CD8 T cells in ccRCC.

Expression and clinical significance of PDK family in breast cancer based on data mining

The pyruvate dehydrogenase kinase (PDK) family, including PDK1, PDK2, PDK3, and PDK4, is involved in tumor progression. However, its role in breast cancer (BC) remains unknown. This study aims to mine the expression, clinical significance, and downstream pathways of PDK family in BC. By analyzing data downloaded from The Cancer Genome Atlas (TCGA) database, we found an enhanced level of PDK3 and decreased expression of PDK2 and PDK4 in BC tissues compared to normal tissues. Also, the expression of PDK3 mRNA is negatively related to that of PDK2 and PDK4, while there is a positive relation between PDK2 mRNA expression and PDK3 mRNA expression. Moreover, we found that PDK2 expression is related to lymph node metastasis, and PDK4 is associated with T stage and stage using analysis of data obtained from TCGA database. Finally, we identified several gene sets related to cancer initiation and progression regulated by PDK2-4 after performing Gene set enrichment analysis (GSEA). In conclusion, PDK2-4 possess potential as targets for BC treatment.

Overexpression of PDK2 and PDK3 reflects poor prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematological malignancy characterized by the proliferation of immature myeloid cells, with impaired differentiation and maturation. Pyruvate dehydrogenase kinase (PDK) is a pyruvate dehydrogenase complex (PDC) phosphatase inhibitor that enhances cell glycolysis and facilitates tumor cell proliferation. Inhibition of its activity can induce apoptosis of tumor cells. Currently, little is known about the role of PDKs in AML. Therefore, we screened The Cancer Genome Atlas (TCGA) database for de novo AML patients with complete clinical information and PDK family expression data, and 84 patients were included for the study. These patients did not undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). Univariate analysis showed that high expression of PDK2 was associated with shorter EFS (P = 0.047), and high expression of PDK3 was associated with shorter OS (P = 0.026). In multivariate analysis, high expression of PDK3 was an independent risk factor for EFS and OS (P < 0.05). In another TCGA cohort of AML patients who underwent allo-HSCT (n = 71), PDK expression was not associated with OS (all P > 0.05). Our results indicated that high expressions of PDK2 and PDK3, especially the latter, were poor prognostic factors of AML, and the effect could be overcome by allo-HSCT.

The lncRNA-DLEU2/miR-186-5p/PDK3 axis promotes the progress of glioma cells

Long non-coding RNAs (lncRNAs) have great value in research on tumour targeted therapy, including for glioma. In the present study, we investigated the role of the lncRNA deleted in lymphocytic leukaemia 2 (lncRNA-DLEU2) in glioma. First, we found that lncRNA-DLEU2 is highly expressed in glioma tissues and cell lines. Next, experiments in cells showed that lncRNA-DLEU2 knockdown inhibited, whereas lncRNA-DLEU2 overexpression promoted, the clone formation, migration and invasion of glioma cells. A luciferase reporter assay and an RNA immunoprecipitation assay demonstrated that lncRNA-DLEU2 acts as a sponge for miR-186-5p in glioma cells. Further, studies suggested that miR-186-5p inhibits the expression of PDK3, which is an oncogene in glioma. Moreover, with rescue experiments, we demonstrated that lncRNA-DLEU2 regulates the expression of PDK3 and the progression of glioma in a miR-186-5p-dependent manner. Finally, we also showed that lncRNA-DLEU2 promotes glioma growth in a manner that is related to miR-186-5p and PDK3 in vivo. In conclusion, our study reported for the first time that lncRNA-DLEU2 promotes glioma progression by targeting the miR-186-5p/PDK3 axis. These findings provide novel strategies for the gene therapy treatment of glioma.