Dichloroacetophenone biphenylsulfone ethers as anticancer pyruvate dehydrogenase kinase inhibitors in non-small cell lung cancer models

Lactoferrin-encapsulated dichloroacetophenone (DAP) nanoparticles enhance drug delivery and anti-tumor efficacy in prostate cancer

Pyruvate Dehydrogenase Kinase 1 (PDK1) regulates glycolysis and oxidative phosphorylation pathways and is linked to prostate cancer metastasis and poor prognosis. The therapeutic application of 2,2-dichloroacetophenone (DAP), a PDK1 inhibitor, remains underexplored in prostate cancer. In this study we demonstrated that DAP exhibited a superior ability to inhibit prostate cancer cell proliferation, migration and colony formation at a lower concentration (20 μM) compared to a previously established inhibitor, dichloroacetate (DCA), which required concentrations of 30 mM or higher. However, poor aqueous solubility and lower stability of DAP limits its therapeutic application. Nano formulation of DAP with natural lactoferrin enhanced its dispersion and stability by increasing polydispersity index and intensity, and reduced zeta potential values upon conjugation that overcame the solubility limitations of DAP. The lactoferrin-DAP nanoparticles exhibited enhanced therapeutic efficacy by precisely targeting prostate cancer cells that express high lactoferrin receptors and high anti-tumor activity in vitro (at 1 μM) and in mouse prostate tumor xenografts (20 mg/kg). Mechanistically, these nanoparticles induce apoptosis in cancer cells by inducing caspase3/7 activity and disrupting the glycolytic and oxidative phosphorylation pathways. Moreover, lactoferrin-conjugated DAP nanoparticles suppressed the viability of docetaxel-resistant cells exhibiting a higher inhibitory efficacy compared to free DAP and DCA. Targeting PDK1 through lactoferrin-conjugated DAP nanoparticles represents a potent targeted therapeutic strategy for disrupting prostate tumor metabolism and offers promising implications for overcoming drug resistance.

Identification of a selective pyruvate dehydrogenase kinase 1 (PDHK1) chemical probe by virtual screening

PDHK1 is a non-canonical Ser/Thr kinase that negatively regulates the pyruvate dehydrogenase complex (PDC), restricting entry of acetyl-CoA into the tricarboxylic acid (TCA) cycle and downregulating oxidative phosphorylation. In many glycolytic tumors, PDHK1 is overexpressed to suppress activity of the PDC and cause a shift in metabolism toward an increased reliance on glycolysis (the Warburg effect). Genetic studies have shown that knockdown or knockout of PDHK1 reverts this phenotype and inhibits tumor growth in vitro and in vivo, but chemical tools to pharmacologically validate and build upon these data are lacking. We used AtomNet®, a deep convolutional neural network bioactivity predictor, to identify compound 7 as a potential inhibitor of PDHK1. During the process of hit validation, the active species was determined to be isomeric compound 10. Structure-activity studies based on 10 identified 17 as a low μM inhibitor of PDHK1 (IC50 = 1.5 ± 0.3 μM) that is selective against the other PDHK isoforms in both biochemical and cell-based assays. In A549 epithelial lung carcinoma cells, compound 17 inhibits phosphorylation of PDC E1α Ser232, a site that is specifically phosphorylated only by PDHK1, while minimally suppressing phosphorylation of Ser293, a site that is phosphorylated by all four PDHK isoforms. Altogether, these data identify 17 as a selective PDHK1 chemical probe useful for biochemical and cell-based studies.

Dichloroacetate for Cancer Treatment: Some Facts and Many Doubts

Rarely has a chemical elicited as much controversy as dichloroacetate (DCA). DCA was initially considered a dangerous toxic industrial waste product, then a potential treatment for lactic acidosis. However, the main controversies started in 2008 when DCA was found to have anti-cancer effects on experimental animals. These publications showed contradictory results in vivo and in vitro such that a thorough consideration of this compound's in cancer is merited. Despite 50 years of experimentation, DCA's future in therapeutics is uncertain. Without adequate clinical trials and health authorities' approval, DCA has been introduced in off-label cancer treatments in alternative medicine clinics in Canada, Germany, and other European countries. The lack of well-planned clinical trials and its use by people without medical training has discouraged consideration by the scientific community. There are few thorough clinical studies of DCA, and many publications are individual case reports. Case reports of DCA's benefits against cancer have been increasing recently. Furthermore, it has been shown that DCA synergizes with conventional treatments and other repurposable drugs. Beyond the classic DCA target, pyruvate dehydrogenase kinase, new target molecules have also been recently discovered. These findings have renewed interest in DCA. This paper explores whether existing evidence justifies further research on DCA for cancer treatment and it explores the role DCA may play in it.

Recent advances in pyruvate dehydrogenase kinase inhibitors: Structures, inhibitory mechanisms and biological activities

Metabolism is reprogrammed in a variety of cancer cells to ensure their rapid proliferation. Cancer cells prefer to utilize glycolysis to produce energy as well as to provide large amounts of precursors for their division. In this process, cancer cells inhibit the activity of pyruvate dehydrogenase complex (PDC) by upregulating the expression of pyruvate dehydrogenase kinases (PDKs). Inhibiting the activity of PDKs in cancer cells can effectively block this metabolic transition in cancer cells, while also activating mitochondrial oxidative metabolism and promoting apoptosis of cancer cells. To this day, the study of PDKs inhibitors has become one of the research hotspots in the field of medicinal chemistry. Novel structures targeting PDKs are constantly being discovered, and some inhibitors have entered the clinical research stage. Here, we reviewed the research progress of PDKs inhibitors in recent years and classified them according to the PDKs binding sites they acted on, aiming to summarize the structural characteristics of inhibitors acting on different binding sites and explore their clinical application value. Finally, the shortcomings of some PDKs inhibitors and the further development direction of PDKs inhibitors are discussed.

Targeting the pyruvate dehydrogenase complex/pyruvate dehydrogenase kinase (PDC/PDK) axis to discover potent PDK inhibitors through structure-based virtual screening and pharmacological evaluation

Proliferating cancer cells are characterized by the Warburg effect, a metabolic alteration in which ATP is generated from cytoplasmic glycolysis instead of oxidative phosphorylation. The pyruvate dehydrogenase complex/pyruvate dehydrogenase kinase (PDC/PDK) axis plays a crucial role in this effect and has been identified as a potential target for anticancer drug development. Herein, we present the discovery and pharmacological evaluation of potent PDK inhibitors targeting the PDK/PDC axis. We successfully identified 6 compounds from a small molecule library through a structure-based virtual screening campaign and evaluated their enzymatic inhibitory potencies for PDK1-4. Our results indicated that compound 1 exhibited submicromolar inhibitory activities against PDK1-3 (IC50 = 109.3, 135.8, and 458.7 nM, respectively), but is insensitive to PDK4 (IC50 = 8.67 μM). Furthermore, compound 1 inhibited the proliferation of A549 cells with an EC50 value of 10.7 μM. In addition, compound 1 induced cell apoptosis, arrested the cell cycle at the S phase, and reduced cell invasion and migration, while showing low in vivo toxicity at a high dose. Based on these observations, it can be concluded that compound 1 is a promising anti-PDK1-3 lead that merits further investigation.

Combined inhibition of pyruvate dehydrogenase kinase 1 and lactate dehydrogenase a induces metabolic and signaling reprogramming and enhances lung adenocarcinoma cell killing

Lung adenocarcinoma (LUAD) is one of the most prevalent and aggressive types of lung cancer. Metabolic reprogramming plays a critical role in the development and progression of LUAD. Pyruvate dehydrogenase kinase 1 (PDK1) and lactate dehydrogenase A (LDHA) are two key enzymes involved in glucose metabolism, whilst their aberrant expressions are often associated with tumorigenesis. Herein, we investigated the anticancer effects of combined inhibition of PDK1 and LDHA in LUAD in vitro and in vivo and its underlying mechanisms of action. The combination of a PDK1 inhibitor, 64, and a LDHA inhibitor, NHI-Glc-2, led to a synergistic growth inhibition in 3 different LUAD cell lines and more than additively suppressed tumor growth in the LUAD xenograft H1975 model. This combination also inhibited cellular migration and colony formation, while it induced a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) resulting in mitochondrial depolarization and apoptosis in LUAD cells. These effects were related to modulation of multiple cell signaling pathways, including AMPK, RAS/ERK, and AKT/mTOR. Our findings demonstrate that simultaneous inhibition of multiple glycolytic enzymes (PDK1 and LDHA) is a promising novel therapeutic approach for LUAD.