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This study provides insight into therapy for lung cancer, establishing p-C resol ( p-C) as an inhibitor of Pyruvate Dehydrogenase Kinase 3 (PDK3). PDK3 is critical in cancer metabolism by regulating the pyruvate dehydrogenase complex, shifting cellular energy production towards glycolysis, and promoting tumor growth and survival under hypoxic conditions. In this study, we have used computational and experimental approaches. Molecular docking reveals that p-C occupies PDK3’s binding pocket and forms interactions with key residues, especially Asp 287. Molecular dynamic simulation (MD) studies showed that p-C induced minimum alterations in PDK3, suggesting the structural stability of the PDK3- p-C complex. A fluorescence-based binding study demonstrated the binding of p-C to PDK3 with a binding constant of 3.8 × 10 8 M −1 , indicating excellent binding affinity. Cell-based enzyme assay revealed significant inhibition of PDK3 by p-C , establishing it as a PDK3 inhibitor. Moreover, cellular assays also demonstrated significant inhibition of PDK3 activity and tumor progression. This study provides a promising therapeutic avenue for improving lung cancer treatment outcomes by targeting PDK3. 

Polycystic ovary syndrome (PCOS) is a complex common endocrine disorder affecting women of reproductive age. Ovulatory dysfunction is recognized as a primary infertile factor, however, even when ovulation is medically induced and restored, PCOS patients continue to experience reduced cumulative pregnancy rates and a higher spontaneous miscarriage rate. Hyperandrogenism, a hallmark feature of PCOS, affects ovarian folliculogenesis, endometrial receptivity, and the establishment and maintenance of pregnancy. Decidualization denotes the transformation that the stromal compart of the endometrium must undergo to accommodate pregnancy, driven by the rising progesterone levels and local cAMP production. However, studies on the impact of hyperandrogenism on decidualization are limited. In this study, we observed that primary endometrial stromal cells from women with PCOS exhibit abnormal responses to progesterone during in vitro decidualization. A high concentration of testosterone inhibits human endometrial stromal cells (HESCs) decidualization. RNA-Seq analysis demonstrated that pyruvate dehydrogenase kinase 4 (PDK4) expression was significantly lower in the endometrium of PCOS patients with hyperandrogenism compared to those without hyperandrogenism. We also characterized that the expression of PDK4 is elevated in the endometrium stroma at the mid-secretory phase. Artificial decidualization could enhance PDK4 expression, while downregulation of PDK4 leads to abnormal decidualization both in vivo and in vitro. Mechanistically, testosterone excess inhibits IGFBP1 and PRL expression, followed by phosphorylating of AMPK that stimulates PDK4 expression. Based on co-immunoprecipitation analysis, we observed an interaction between SIRT1 and PDK4, promoting glycolysis to facilitate decidualization. Restrain of AR activation resumes the AMPK/SIRT1/PDK4 pathway suppressed by testosterone excess, indicating that testosterone primarily acts on decidualization through AR stimulation. Androgen excess in the endometrium inhibits decidualization by disrupting the AMPK/SIRT1/PDK4 signaling pathway. These data demonstrate the critical roles of endometrial PDK4 in regulating decidualization and provide valuable information for understanding the underlying mechanism during decidualization.

Sarcopenia is a condition that affects one’s activities of daily livingand is rapidly increasing with the ages of the global population. However, the basic molecular mechanisms for prevention and treatment are not fully understood. Although rodent model animals have many valuable aspects for studying sarcopenia, some aspects and mechanisms differ from humans, such as immune response, metabolism, stress response, and myofiber composition. This study established a human cell-based in vitro model to elucidate the molecular mechanism by which SASP from senescence-induced human mesenchymal stem cells led to the narrowing of human myotube diameter, suggesting that this model is useful for studying sarcopenia. Gene expression profiling was performed the molecular mechanisms and devel on the model by RNA sequencing to identify genes whose expression was affected by SASP. Among these, the exposure to SASP upregulated PDK4 expression, and a PDK4 inhibitor, DCA, could increase myotube diameter and reverse SASP-mediated narrowing of the diameter. Pathway analyses suggested that SASP affected energy metabolism by activating OXPHOS and promoting the expression of mitochondrial function-related genes and mitochondrial biosynthesis factors. These results provide insights that contribute to developing new treatments for sarcopenia.

Background: Oral squamous cell carcinoma (OSCC) has a high prevalence and predicted global mortality rate of 67.1%, necessitating better therapeutic strategies. Moreover, the recurrence and resistance of OSCC after chemo/radioresistance remains a major bottleneck for its effective treatment. Molecular targeting is one of the new therapeutic approaches to target cancer. Among a plethora of targetable signaling molecules, PDK1 is currently rising as a potential target for cancer therapy. Its aberrant expression in many malignancies is observed associated with glycolytic re-programming and chemo/radioresistance. Methods: Furthermore, to better understand the role of PDK1 in OSCC, we analyzed tissue samples from 62 patients with OSCC for PDK1 expression. Combining in silico and in vitro analysis approaches, we determined the important association between PDK1/CD47/LDHA expression in OSCC. Next, we analyzed the effect of PDK1 expression and its connection with OSCC orosphere generation and maintenance, as well as the effect of the combination of the PDK1 inhibitor BX795, cisplatin and radiotherapy in targeting it. Results: Immunohistochemical analysis revealed that higher PDK1 expression is associated with a poor prognosis in OSCC. The immunoprecipitation assay indicated PDK1/CD47 binding. PDK1 ligation significantly impaired OSCC orosphere formation and downregulated Sox2, Oct4, and CD133 expression. The combination of BX795 and cisplatin markedly reduced in OSCC cell’s epithelial-mesenchymal transition, implying its synergistic effect. p-PDK1, CD47, Akt, PFKP, PDK3 and LDHA protein expression were significantly reduced, with the strongest inhibition in the combination group. Chemo/radiotherapy together with abrogation of PDK1 inhibits the oncogenic (Akt/CD47) and glycolytic (LDHA/PFKP/PDK3) signaling and, enhanced or sensitizes OSCC to the anticancer drug effect through inducing apoptosis and DNA damage together with metabolic reprogramming. Conclusions: Therefore, the results from our current study may serve as a basis for developing new therapeutic strategies against chemo/radioresistant OSCC.

BackgroundTargeting ferroptosis mediated by autophagy presents a novel therapeutic approach to breast cancer, a mortal neoplasm on the global scale. Pyruvate dehydrogenase kinase isozyme 4 (PDK4) has been denoted as a determinant of breast cancer metabolism. The target of this study was to untangle the functional mechanism of PDK4 in ferroptosis dependent on autophagy in breast cancer.MethodsRT-qPCR and western blotting examined PDK4 mRNA and protein levels in breast cancer cells. Immunofluorescence staining appraised light chain 3 (LC3) expression. Fe (2 +) assay estimated total iron level. Relevant assay kits and C11-BODIPY (591/581) staining evaluated lipid peroxidation level. DCFH-DA staining assayed intracellular reactive oxygen species (ROS) content. Western blotting analyzed the protein levels of autophagy, ferroptosis and apoptosis-signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway-associated proteins.ResultsPDK4 was highly expressed in breast cancer cells. Knockdown of PDK4 induced the autophagy of breast cancer cells and 3-methyladenine (3-MA), an autophagy inhibitor, countervailed the promoting role of PDK4 interference in ferroptosis in breast cancer cells. Furthermore, PDK4 knockdown activated ASK1/JNK pathway and ASK1 inhibitor (GS-4997) partially abrogated the impacts of PDK4 absence on the autophagy and ferroptosis in breast cancer cells. ConclusionTo sum up, deficiency of PDK4 activated ASK1/JNK pathway to stimulate autophagy-dependent ferroptosis in breast cancer.

In cancer cells, aerobic glycolysis rather than oxidative phosphorylation (OxPhos) is generally preferred for the production of ATP. In many cancers, highly expressed pyruvate dehydrogenase kinase 1 (PDK1) reduces the activity of pyruvate dehydrogenase (PDH) by inducing the phosphorylation of its E1α subunit (PDHA1) and subsequently, shifts the energy metabolism from OxPhos to aerobic glycolysis. Thus, PDK1 has been regarded as a target for anticancer treatment. Here, we report that ilimaquinone (IQ), a sesquiterpene quinone isolated from the marine sponge Smenospongia cerebriformis, might be a novel PDK1 inhibitor. IQ decreased the cell viability of human and murine cancer cells, such as A549, DLD-1, RKO, and LLC cells. The phosphorylation of PDHA1, the substrate of PDK1, was reduced by IQ in the A549 cells. IQ decreased the levels of secretory lactate and increased oxygen consumption. The anticancer effect of IQ was markedly reduced in PDHA1-knockout cells. Computational simulation and biochemical assay revealed that IQ interfered with the ATP binding pocket of PDK1 without affecting the interaction of PDK1 and the E2 subunit of the PDH complex. In addition, similar to other pyruvate dehydrogenase kinase inhibitors, IQ induced the generation of mitochondrial reactive oxygen species (ROS) and depolarized the mitochondrial membrane potential in the A549 cells. The apoptotic cell death induced by IQ treatment was rescued in the presence of MitoTEMPO, a mitochondrial ROS inhibitor. In conclusion, we suggest that IQ might be a novel candidate for anticancer therapeutics that act via the inhibition of PDK1 activity.

Most cancer cells primarily produce their energy through a high rate of glycolysis followed by lactic acid fermentation even in the presence of abundant oxygen. Pyruvate dehydrogenase kinase (PDK) 1, an enzyme responsible for aerobic glycolysis via phosphorylating and inactivating pyruvate dehydrogenase (PDH) complex, is commonly overexpressed in tumors and recognized as a therapeutic target in colorectal cancer. Hemistepsin A (HsA) is a sesquiterpene lactone isolated from Hemistepta lyrata Bunge (Compositae). Here, we report that HsA is a PDK1 inhibitor can reduce the growth of colorectal cancer and consequent activation of mitochondrial ROS-dependent apoptotic pathway both in vivo and in vitro. Computational simulation and biochemical assays showed that HsA directly binds to the lipoamide-binding site of PDK1, and subsequently inhibits the interaction of PDK1 with the E2 subunit of PDH complex. As a result of PDK1 inhibition, lactate production was decreased, but oxygen consumption was increased. Mitochondrial ROS levels and mitochondrial damage were also increased. Consistent with these observations, the apoptosis of colorectal cancer cells was promoted by HsA with enhanced activation of caspase-3 and -9. These results suggested that HsA might be a potential candidate for developing a novel anti-cancer drug through suppressing cancer metabolism.

Fibroblast-derived exosomes have been reported to transfer microRNAs to recipient cells, where they regulate target gene expression, which is of interest for understanding the basic biology of inflammation, tissue homeostasis, and development of therapeutic approaches. Initial microarray-based analysis carried out in this study identified the rheumatoid arthritis (RA)–related differentially expressed gene pyruvate dehydrogenase kinase 4 (PDK4). Subsequently, the upstream regulatory microRNA-106b (miR-106b) of PDK4 was predicted with bioinformatic analyses. A collagen-induced arthritis (CIA)-induced mouse model was established, and exosomes were isolated from synovial fibroblasts (SFs) and transferred into chondrocytes to identify the role of exosomes in rheumatoid arthritis (RA). We found that PDK4 was poorly expressed in RA cartilage tissues and chondrocytes, while miR-106b was highly expressed in RA SFs and SF-derived exosomes. Notably, PDK4 was confirmed as a target gene of miR-106b. Over-expression of PDK4 promoted the proliferation and migration abilities of chondrocytes and inhibited their apoptosis as well as affected the receptor activator of nuclear factor kappa B ligand (RANKL)/RANK/osteoprotegerin (OPG) system. Meanwhile, miR-106b was delivered from SFs to chondrocytes through exosomes, which suppressed chondrocyte proliferation and migration and accelerated apoptosis as well as affected the RANKL/RANK/OPG system via down-regulation of PDK4. Furthermore, in vivo results validated that miR-106b inhibition could relieve CIA-induced RA. Taken together, SF-derived exosomal miR-106b stimulates RA initiation by targeting PDK4, indicating a physiologically validated potential approach for the prevention and treatment of RA.Key messagesPDK4 is decreased in chondrocytes of RA, while miR-106b is increased in SFBs.PDK4 promotes proliferation and migration of chondrocytes.miR-106b could target 3′UTR of PDK4 gene.SFB-exosomal miR-106b inhibits proliferation and migration of chondrocytes.Inhibition of miR-106b attenuates RA progression in a CIA mouse model.

Chondrocytes can shift their metabolism to oxidative phosphorylation (OxPhos) in the early stages of osteoarthritis (OA), but as the disease progresses, this metabolic adaptation becomes limited and eventually fails, leading to mitochondrial dysfunction and oxidative stress. Here we investigated whether enhancing OxPhos through the inhibition of pyruvate dehydrogenase kinase (PDK) 2 affects the metabolic flexibility of chondrocytes and cartilage degeneration in a surgical model of OA. Among the PDK isoforms, PDK2 expression was increased by IL-1β in vitro and in the articular cartilage of the DMM model in vivo, accompanied by an increase in phosphorylated PDH. Mice lacking PDK2 showed significant resistance to cartilage damage and reduced pain behaviors in the DMM model. PDK2 deficiency partially restored OxPhos in IL-1β-treated chondrocytes, leading to increases in APT and the NAD + /NADH ratio. These metabolic changes were accompanied by a decrease in reactive oxygen species and senescence in chondrocytes, as well as an increase in the expression of antioxidant proteins such as NRF2 and HO-1 after IL-1β treatment. At the signaling level, PDK2 deficiency reduced p38 signaling and maintained AMPK activation without affecting the JNK, mTOR, AKT and NF-κB pathways. p38 MAPK signaling was critically involved in reactive oxygen species production under glycolysis-dominant conditions in chondrocytes. Our study provides a proof of concept for PDK2-mediated metabolic reprogramming toward OxPhos as a new therapeutic strategy for OA. Boosting OxPhos in chondrocytes mitigates osteoarthritis progression Osteoarthritis is a common joint disease where cartilage breaks down, causing pain and stiffness. Chondrocytes, the cells in cartilage, usually rely on glycolysis for energy production. However, in early OA, they can switch to oxidative phosphorylation as an alternative energy pathway. This study aimed to see if modulating chondrocyte metabolism could slow OA progression. Researchers focused on PDK2, a protein that inactivates PDH, thereby reducing OxPhos activity in chondrocytes. They used mice genetically modified to lack PDK2 and compared them with normal mice with surgically induced OA. They found that, without PDK2, chondrocytes had better energy balance by using OxPhos more effectively and less oxidative stress, which slowed OA progression. This suggests that targeting PDK2 could be a new way to treat OA by improving chondrocyte metabolism. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.

Budding at the tumor invasive front has been correlated with the malignant properties of many cancers. Malic enzyme 1 (ME1) promotes the Warburg effect in cancer cells and induces epithelial–mesenchymal transition (EMT) in oral squamous cell carcinoma (OSCC). Therefore, we investigated the role of ME1 in tumor budding in OSCC. Tumor budding was measured in 96 human OSCCs by immunostaining for an epithelial marker (AE1/AE3), and its expression was compared with that of ME1. A significant correlation was observed between tumor budding and ME1 expression. The correlation increased with the progression of cancer. In human OSCC cells, lactate secretion decreased when lactate fermentation was suppressed by knockdown of ME1 and lactate dehydrogenase A or inhibition of pyruvate dehydrogenase (PDH) kinase. Furthermore, the extracellular pH increased, and the EMT phenotype was suppressed. In contrast, when oxidative phosphorylation was suppressed by PDH knockdown, lactate secretion increased, extracellular pH decreased, and the EMT phenotype was promoted. Induction of chemical hypoxia in OSCC cells by CoCl2 treatment resulted in increased ME1 expression along with HIF1α expression and promotion of the EMT phenotype. Hypoxic conditions also increased matrix metalloproteinases expression and decreased mitochondrial membrane potential, mitochondrial oxidative stress, and extracellular pH. Furthermore, the hypoxic treatment resulted in the activation of Yes-associated protein (YAP), which was abolished by ME1 knockdown. These findings suggest that cancer cells at the tumor front in hypoxic environments increase their lactate secretion by switching their energy metabolism from oxidative phosphorylation to glycolysis owing to ME1 overexpression, decrease in extracellular pH, and YAP activation. These alterations enhance EMT and the subsequent tumor budding. Tumor budding and ME1 expression are thus considered useful markers of OSCC malignancy, and ME1 is expected to be a relevant target for molecular therapy.