Cuproptosis related gene PDHB is identified as a biomarker inversely associated with the progression of clear cell renal cell carcinoma.

BACKGROUND: Cuproptosis is a newly discovered programmed cell death dependent on mitochondrial respiratory disorder induced by copper overload. Pyruvate dehydrogenase E1 subunit beta (PDHB) is one of the cuproptosis genesand is a nuclear-encoded pyruvate dehydrogenase, which catalyzes the conversion of pyruvate to acetyl coenzyme A. However, the mechanism of PDHB in clear cell renal cell carcinoma (ccRCC) remains unclear. METHODS: We used data from TCGA and GEO to assess the expression of PDHB in normal and tumor tissues. We further analyzed the relationship between PDHB and somatic mutations and immune infiltration. Finally, we preliminarily explored the impact of PDHB on ccRCC. RESULTS: The expression level of PDHB was lower in tumor tissue compared with normal tissue. Meanwhile, the expression level of PDHB was also lower in high-grade tumors than low-grade tumors. PDHB is positively correlated with prognosis in ccRCC. Furthermore, PDHB may be associated with decreased risk of VHL, PBRM1 and KDM5C mutations. In 786-O cells, copper chloride could promote the expression of cuproptosis genes (DLAT, PDHB and FDX1) and inhibit cell growth. Last but not least, we found that PDHB could inhibit the proliferation and migration of ccRCC cells. CONCLUSION: Our results demonstrated that PDHB could inhibit the proliferation, migration and invasion in ccRCC cells, which might be a prognostic predictor of ccRCC. Targeting this molecular might provide a new therapeutic strategy for patients with advanced ccRCC.

Solvent accessibility of E1α and E1ß residues with known missense mutations causing pyruvate dehydrogenase complex (PDC) deficiency: Impact on PDC-E1 structure and function.

Pyruvate dehydrogenase complex deficiency is a major cause of primary lactic acidemia resulting in high morbidity and mortality, with limited therapeutic options. PDHA1 mutations are responsible for >82% of cases. The E1 component of PDC is a symmetric dimer of heterodimers (αß/α'ß') encoded by PDHA1 and PDHB. We measured solvent accessibility surface area (SASA), utilized nearest-neighbor analysis, incorporated sequence changes using mutagenesis tool in PyMOL, and performed molecular modeling with SWISS-MODEL, to investigate the impact of residues with disease-causing missense variants (DMVs) on E1 structure and function. We reviewed 166 and 13 genetically resolved cases due to PDHA1 and PDHB, respectively, from variant databases. We expanded on 102 E1α and 13 E1ß nonduplicate DMVs. DMVs of E1α Arg112-Arg224 stretch (exons 5-7) and of E1α Arg residues constituted 40% and 39% of cases, respectively, with invariant Arg349 accounting for 22% of arginine replacements. SASA analysis showed that 86% and 84% of residues with nonduplicate DMVs of E1α and E1ß, respectively, are solvent inaccessible ("buried"). Furthermore, 30% of E1α buried residues with DMVs are deleterious through perturbation of subunit-subunit interface contact (SSIC), with 73% located in the Arg112-Arg224 stretch. E1α Arg349 represented 74% of buried E1α Arg residues involved in SSIC. Structural perturbations resulting from residue replacements in some matched neighboring pairs of amino acids on different subunits involved in SSIC at 2.9-4.0 Å interatomic distance apart, exhibit similar clinical phenotype. Collectively, this work provides insight for future target-based advanced molecular modeling studies, with implications for development of novel therapeutics for specific recurrent DMVs of E1α.

Neuron-specific knockdown of Drosophila PDHB induces reduction of lifespan, deficient locomotive ability, abnormal morphology of motor neuron terminals and photoreceptor axon targeting.

Pyruvate dehydrogenase complex deficiency (PDCD) is a common primary cause of defects in mitochondrial function and also can lead to peripheral neuropathy. Pyruvate dehydrogenase E1 component subunit beta (PDHB) is a subunit of pyruvate dehydrogenase E1, which is a well-known component of PDC. In Drosophila melanogaster, the CG11876 (dPDHB) gene is a homolog of human PDHB. In this study, we established a Drosophila model with neuron-specific knockdown of dPDHB to investigate its role in neuropathy pathogenesis. Knockdown of dPDHB in pan-neurons induced locomotor defects in both larval and adult stages, which were consistent with abnormal morphology of the motor neuron terminals at neuromuscular junctions and mitochondrial fragmentation in brains. Moreover, neuron-specific knockdown of dPDHB also shortened the lifespan of adult flies. In addition, flies with knockdown of dPDHB manifested a rough eye phenotype and aberrant photoreceptor axon targeting. These results with the Drosophila model suggest the involvement of PDHB in peripheral neuropathy.

Pyruvate dehydrogenase subunit ß of Lactobacillus plantarum is a collagen adhesin involved in biofilm formation.

Multi-functional surface proteins have been observed in a variety of pathogenic bacteria, where they mediate host cell adhesion and invasion, as well as in commensal bacterial species, were they mediate positive interaction with the host. Among these proteins, some glycolytic enzymes, expressed on the bacterial cell surface, can bind human extracellular matrix components (ECM). A major target for them is collagen, an abundant glycoprotein of connective tissues. We have previously shown that the enolase EnoA1 of Lactobacillus plantarum, one of the most predominant species in the gut microbiota of healthy individuals, is involved in binding with collagen type I (CnI). In this study, we found that PDHB, a component of the pyruvate dehydrogenase complex, contributes to the L. plantarum LM3 adhesion to CnI. By a cellular adhesion assay to immobilized CnI, we show that LM3-B1 cells, carrying a null mutation in the pdhB gene, bind to CnI - coated surfaces less efficiently than wild-type cells. Moreover, we show that the PDHB-CnI interaction requires a native state for PDHB. We also analyzed the ability to develop biofilm in wild-type and mutant strains and we found that the lack of the PDHB on cell surface generates cells partially impaired in biofilm development.

Pyruvate dehydrogenase B promoted the growth and migration of the nasopharyngeal carcinoma cells.

Metabolism alteration is one of the hallmarks of cancer cells. Although several studies have demonstrated that glycolysis played important roles in the progression of nasopharyngeal carcinoma (NPC), the functions of specific metabolism-associated genes remain largely unknown. In this study, it was found that Pyruvate dehydrogenase B (PDHB), which catalyzed the conversion of pyruvate to Acetyl-CoA, was downregulated in NPC cells. Forced expression of PDHB in NPC cells inhibited cell growth and migration, while knocking down the expression of PDHB promoted the growth, migration, and tumorigenesis of NPC cells. Mechanism study showed that PDHB inhibited ERK signaling and cell growth driven by RasV12. Collectively, our study demonstrated the suppressive roles of PDHB in the progression of NPC, and restoring the function of PDHB might be a promising strategy for NPC therapy.

MiR-203 promotes the growth and migration of ovarian cancer cells by enhancing glycolytic pathway.

MicroRNAs (miRNAs) play an important role in the tumorigenesis of ovarian cancer. Previously, we have reported the dysregulation of miR-203 in the ovarian cancer tissues. However, the biological functions and molecular mechanisms of miR-203 in ovarian cancer remain unknown. Here, we showed that the expression of miR-203 was increased in ovarian cancer tissues compared with the adjacent non-cancerous tissues and the transcription of miR-203 was inhibited by P53. Forced expression of miR-203 in ovarian cancer promoted cell growth and migration, while depletion of miR-203 inhibited the growth and migration of ovarian cancer cells. In addition, miR-203 promoted the metastasis of ovarian cancer cells in vivo and shorted the survival of the nude mice. Mechanically, miR-203 targeted the 3'-UTR of pyruvate dehydrogenase B (PDHB) and increased the consumption of glucose and the production of lactate. Overexpression of PDHB abolished the oncogenic effects of miR-203 on the growth of ovarian cancer cells. Together, our data suggested the oncogenic roles of miR-203 in ovarian cancer by promoting glycolysis, and miR-203 might be a therapeutic target for ovarian cancer.

Identification of potential crucial cuproptosis-related genes in myocardial ischemia-reperfusion injury through the bioinformatic analysis.

BACKGROUND: Cuproptosis is known to regulate diverse physiological functions in many diseases, but its role in regulating Myocardial Ischemia-Reperfusion Injury (MI/RI) remains unclear. METHODS: For this purpose, the MI/RI microarray datasets GSE61592 were downloaded from the Gene Expression Omnibus (GEO) database, and the Differently Expressed Genes (DEGs) in MI/RI were identified using R software. Moreover, the MI/RI mice model was established to confirm further the diagnostic value of Pyruvate Dehydrogenase B (Pdhb), Dihydrolipoamide S-acetyltransferase (Dlat), and Pyruvate dehydrogenase E1 subunit alpha 1 (Pdhα1). RESULTS: The analysis of microarray datasets GSE61592 revealed that 798 genes were upregulated and 768 were downregulated in the myocardial tissue of the ischemia-reperfusion injury mice. Furthermore, Dlat, Pdhb, Pdhα1, and cuproptosis-related genes belonged to the downregulated genes. The receiver operating characteristics curve analysis results indicated that the Dlat, Pdhb, and Pdhα1 levels were downregulated in MI/RI and were found to be potential biomarkers for MI/RI diagnosis and prognosis. Similarly, analysis of Dlat, Pdhb, and Pdhα1 levels in the MI/RI mice revealed Pdhb being the key diagnostic marker. CONCLUSIONS: This study demonstrated the prognostic value of cuproptosis-related genes (Dlat, Pdhb, and Pdhα1), especially Pdhb, MI/RI, providing new insight into the MI/RI treatment.

Pyruvate dehydrogenase B regulates myogenic differentiation via the FoxP1-Arih2 axis.

BACKGROUND: Sarcopenia, the age-related decline in skeletal muscle mass and function, diminishes life quality in elderly people. Improving the capacity of skeletal muscle differentiation is expected to counteract sarcopenia. However, the mechanisms underlying skeletal muscle differentiation are complex, and effective therapeutic targets are largely unknown. METHODS: The human Gene Expression Omnibus database, aged mice and primary skeletal muscle cells were used to assess the expression level of pyruvate dehydrogenase B (PDHB) in human and mouse aged state. d-Galactose (d-gal)-induced sarcopenia mouse model and two classic cell models (C2C12 and HSkMC) were used to assess the myogenic effect of PDHB and the underlying mechanisms via immunocytochemistry, western blotting, quantitative real-time polymerase chain reaction, RNA interference or overexpression, dual-luciferase reporter assay, RNA sequencing and untargeted metabolomics. RESULTS: We identified that a novel target PDHB promoted myogenic differentiation. PDHB expression decreased in aged mouse muscle relative to the young state (-50% of mRNA level, P < 0.01) and increased during mouse and primary human muscle cell differentiation (+3.97-fold, P < 0.001 and +3.79-fold, P < 0.001). Knockdown or overexpression of PDHB modulated the expression of genes related to muscle differentiation, namely, myogenic factor 5 (Myf5) (-46%, P < 0.01 and -27%, P < 0.05; +1.8-fold, P < 0.01), myogenic differentiation (MyoD) (-55%, P < 0.001 and -34%, P < 0.01; +2.27-fold, P < 0.001), myogenin (MyoG) (-60%, P < 0.001 and -70%, P < 0.001; +5.46-fold, P < 0.001) and myosin heavy chain (MyHC) (-70%, P < 0.001 and -69%, P < 0.001; +3.44-fold, P < 0.001) in both C2C12 cells and HSkMC. Metabolomic and transcriptomic analyses revealed that PDHB knockdown suppressed pyruvate metabolism (P < 0.001) and up-regulated ariadne RBR E3 ubiquitin protein ligase 2 (Arih2) (+7.23-fold, P < 0.001) in cellular catabolic pathways. The role of forkhead box P1 (FoxP1) (+4.18-fold, P < 0.001)-mediated Arih2 transcription was the key downstream regulator of PDHB in muscle differentiation. PDHB overexpression improved d-gal-induced muscle atrophy in mice, which was characterized by significant increases in grip strength, muscle mass and mean muscle cross-sectional area (1.19-fold to 1.5-fold, P < 0.01, P < 0.05 and P < 0.001). CONCLUSIONS: The comprehensive results show that PDHB plays a sarcoprotective role by suppressing the FoxP1-Arih2 axis and may serve as a therapeutic target in sarcopenia.

Pyruvate dehydrogenase beta subunit (Pdhb) promotes peripheral axon regeneration by regulating energy supply and gene expression.

Key metabolic enzymes not only regulate Glucose, lipid, amino acid metabolism to serve the cellular energy needs, but also modulate noncanonical or nonmetabolic signaling pathway such as gene expression, cell-cycle progression, DNA repair, apoptosis and cell proliferation in regulating the pathologic progression of disease. However, the role of glycometabolism in peripheral nerve axon regeneration is little known. In this study, we investigated the expression of Pyruvate dehydrogenase E1(PDH), a key enzyme linking glycolysis and the tricarboxylic acid (TCA) cycle, with qRT-PCR and found that pyruvate dehydrogenase beta subunit (Pdhb) is up-regulated at the early stage during peripheral nerve injury. The knockdown of Pdhb inhibits neurite outgrowth of primary DRG neurons in vitro and restrains axon regeneration of sciatic nerve after crush injury. Pdhb overexpression promoting axonal regeneration is reversed by knockdown of Monocarboxylate transporter 2(Mct2), a transporter involved in the transport and metabolism of lactate, indicating Pdhb promoting axon regeneration depends on lactate for energy supply. Given the nucleus-localization of Pdhb, further analysis revealed that Pdhb enhances the acetylation of H3K9 and affecting the expression of genes involved in arachidonic acid metabolism and Ras signaling pathway, such as Rsa-14-44 and Pla2g4a, thereby promoting axon regeneration. Collectively, our data indicates that Pdhb is a positive dual modulator of energy generation and gene expression in regulating peripheral axon regeneration.

A combined analysis of bulk and single-cell sequencing data reveals metabolic enzyme, pyruvate dehydrogenase E1 subunit beta (PDHB), as a prediction biomarker for the tumor immune response and immunotherapy.

Pyruvate dehydrogenase E1 subunit beta (PDHB) is located in mitochondria and catalyzes the conversion of glucose-derived acetyl-CoA. The detailed roles of PDHB in human cancers is unclear. Here, through comprehensive bioinformatics analysis, we found that PDHB was aberrantly expressed in multiple human cancers and is associated with patients' clinical stage. The abnormal expression of PDHB was related to the prognostic values of cancers, such as kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP). The Wanderer database with clinical data from Cancer Genome Atlas (TCGA) showed a significant correlation between PDHB expression and the pathologic stage of KIRP patients. We also evaluated the mutation profiles of PDHB in pan-cancer, and showed its roles on the patients' prognosis. At last, from several immunity algorithms, we demonstrated that the expression of PDHB was correlated with the infiltration of various immune cells in pan-cancer. Moreover, the aberrant PDHB had effects on the response to immune checkpoint inhibitors in cancer patients, such as anti-PD-1. Taken together, our study demonstrated the prognostic values of PDHB in pan-cancers. PDHB may be a potential molecular marker to predicting the immune response in cancer patients.

Integrated single-cell and bulk characterization of cuproptosis key regulator PDHB and association with tumor microenvironment infiltration in clear cell renal cell carcinoma.

Background: Renal clear cell carcinoma (ccRCC) is one of the most prevalent cancers worldwide. Accumulating evidence revealed that copper-induced cell death played a vital role in various tumors. However, the underlying mechanism of cuproptosis with molecular heterogeneity and tumor microenvironment (TME) in ccRCC remains to be elucidated. The present study aimed to discover the biological function of cuproptosis regulators with the potential to guide clinical therapy. Methods: Using Single-cell RNA-seq, bulk transcriptome and other multi-omics datasets, we identify essential cuproptosis-related hub gene PDHB for further study. The dysregulation of PDHB in ccRCC was characterized, together with survival outcomes, pathway enrichment and immune infiltration among tumor microenvironments. The functional significance and clinical association of PDHB was validated with loss of function experiments and surgical removal specimens. Results: PDHB mRNA and protein expression level was significantly downregulated in ccRCC tissues compared with normal and paired normal tissues. Clinicopathological parameters and tissue microarray (TMA) indicated that PDHB was identified as a prognostic factor for survival outcomes among ccRCC patients. Additionally, low PDHB was negatively correlated with Treg cells, indicating an immunosuppressive microenvironment. Mechanistically, knockdown PDHB appeared to promote the RCC cells proliferation, migration, and invasion potentials. Subsequent studies showed that copper-induced cell death activation could overcome sunitinib resistance in RCC cells. Conclusion: This research illustrated a cuproptosis-related hub gene PDHB which could serve as a potential prognostic marker and provide therapeutic benefits for clinical treatment of ccRCC patients.

[Identification and expression analysis of apple PDHB-1 gene family].

Pyruvate dehydrogenase E1 component subunit beta-1 (PDHB-1) is a gene encoding the ß-subunit of pyruvate dehydrogenase complex, which plays an important role in fruit acid accumulation. The aim of this study was to investigate the evolution characteristics of apple PDHB-1 family and its expression in apples with different acid contents. Bioinformatics analysis was performed using databases including NCBI, Pfam and software including ClustalX, MEGA, and TBtools. By combining titratable acid content determination and quantitative real-time PCR (qRT-PCR), the expression of this family genes in the peel and pulp of apple 'Asda' and 'Chengji No.1' with different acid content were obtained, respectively. The family members were mainly located in chloroplast, cytoplasm and mitochondria. α-helix and random coil were the main factors for the formation of secondary structure in this family. Tissue-specific expression profiles showed that the expression of most members were higher in fruit than in other tissues. qRT-PCR results showed that the expression profile of most members was consistent with the profile of titratable acid contents. In the peel, the expression levels of 14 members in 'Asda' apples with high acid content were significantly higher than that in 'Chengji No.1' apples with low acid content, where the expression difference of MdPDHB1-15 was the most significant. In the pulp, the expression levels of 17 members in 'Asda' apples were significantly higher than that in 'Chengji No.1' apples, where MdPDHB1-01 was the most highly expressed. It was predicted that PDHB-1 gene family in apple plays an important role in the regulation of fruit acidity.

Relationship between transcriptional expression of pyruvate dehydrogenase and local control of disease in patients with oral cavity carcinomas.

BACKGROUND: The altered cellular metabolism is one of the hallmarks of the cancer cells, favoring the process of aerobic glycolysis, known as the Warburg effect. The pyruvate dehydrogenase (PDH) complex is one of the elements involved in this metabolic process. The present study aims to evaluate the relationship between the transcriptional expression of PDHB and the risk of local recurrence in patients with oral cavity carcinomas. METHODS: We determined the transcriptional expression of PDHB in biopsies from 41 patients with oral cavity carcinomas treated with surgery. The PDHB expression was categorized according to the local control of the disease with a recursive partitioning analysis. RESULTS: During the follow-up period 13 patients (31.7%) had a local recurrence of the tumor. Considering local disease control as the dependent variable, the recursive partitioning analysis classified the patients in two categories according to high (n=16, 39.0%) or low (n=25, 61.0%) PDHB expression. Five-year local recurrence-free survival for patients with high PDHB expression was 84.8% (95% CI: 65.2-100%), and for patients with low expression it was 54.3% (95% CI: 34.3-74.2 %) (P=0.034). The results of multivariate analysis showed that patients with a low PDHB expression had a 4.90 times higher risk of local recurrence of the tumor (95% CI: 1.02-22.68, P=0.042). CONCLUSION: There is a relationship between the metabolic characteristics of the tumor and its aggressiveness. According to our results, patients with oral cavity carcinomas with low transcriptional expression levels of PDHB have a significantly higher risk of local tumor recurrence.

Identification and expression analysis of apple PDHB-1 gene family / 生物工程学报

Pyruvate dehydrogenase E1 component subunit beta-1 (PDHB-1) is a gene encoding the β-subunit of pyruvate dehydrogenase complex, which plays an important role in fruit acid accumulation. The aim of this study was to investigate the evolution characteristics of apple PDHB-1 family and its expression in apples with different acid contents. Bioinformatics analysis was performed using databases including NCBI, Pfam and software including ClustalX, MEGA, and TBtools. By combining titratable acid content determination and quantitative real-time PCR (qRT-PCR), the expression of this family genes in the peel and pulp of apple 'Asda' and 'Chengji No.1' with different acid content were obtained, respectively. The family members were mainly located in chloroplast, cytoplasm and mitochondria. α-helix and random coil were the main factors for the formation of secondary structure in this family. Tissue-specific expression profiles showed that the expression of most members were higher in fruit than in other tissues. qRT-PCR results showed that the expression profile of most members was consistent with the profile of titratable acid contents. In the peel, the expression levels of 14 members in 'Asda' apples with high acid content were significantly higher than that in 'Chengji No.1' apples with low acid content, where the expression difference of MdPDHB1-15 was the most significant. In the pulp, the expression levels of 17 members in 'Asda' apples were significantly higher than that in 'Chengji No.1' apples, where MdPDHB1-01 was the most highly expressed. It was predicted that PDHB-1 gene family in apple plays an important role in the regulation of fruit acidity.

Utilizing Optimized Tools to Investigate PTM Crosstalk: Identifying Potential PTM Crosstalk of Acetylated Mitochondrial Proteins.

Post-translational modification (PTM) crosstalk is recognized as a major cell-regulatory mechanism, and studies of several proteins have validated the premise that PTMs work in concert. Previous work by our group investigated the potential PTM crosstalk on proteins in the EGFR-Ras-c-Fos axis by utilizing a comprehensive set of PTM reagents termed Signal-Seeker toolkits. In this study, these tools were used to investigate the potential PTM crosstalk that occurs in acetylated mitochondrial proteins in response to a mitochondrial stress-inducing agent hydrogen peroxide (H2O2). Mitochondrial protein acetylation has been shown to participate in PTM crosstalk as exemplified by the regulation of the pyruvate dehydrogenase complex via kinase, phosphatase, acetyltransferase, and deacetylase activities. Changes in the acetylated state of mitochondrial proteins were investigated, in response to H2O2, using a novel anti acetyl lysine (Ac-K) antibody. Signal-Seeker PTM detection tools were used to validate the acetylation state of ten mitochondrial targets, as well as their endogenous acetylation state in response to H2O2. Importantly, the endogenous acetylation, ubiquitination, SUMOylation 2/3, and tyrosine phosphorylation state of four target mitochondrial proteins were also investigated with the toolkit. Each of the four proteins had unique PTM profiles, but diverging acetylation and ubiquitin or SUMO 2/3 signals appeared to be a common theme. This proof-of-concept study identifies the Signal-Seeker toolkits as a useful tool to investigate potential PTM crosstalk.

MiR-370 functions as oncogene in melanoma by direct targeting pyruvate dehydrogenase B.

BACKGROUND: Accumulating evidence has shown that miR-370 play an important role in the development and progression of tumor. However, the role of miR-370 in melanoma remains largely unknown. The present study is designed to investigate the function of miR-370 in melanoma and to explore the molecular mechanism underlying its function. MATERIALS AND METHODS: The expression level of miR-370 was detected in melanoma tissues and cell lines by real-time quantitative polymerase chain reaction (qRT-PCR). The effect of overexpression of miR-370 on in vitro cell proliferation, apoptosis, invasion as well as glyclolysis was examined. Western blotting analysis was used to detect the influence of miR-370 on the expression of target genes, and Pearson analysis was used to calculate the correlation between the expression of targets gene and miR-370 in melanoma tissues. RESULTS: Our study showed that miR-370 was upregulated in melanoma tissues compared with non-cancerous tissues (P<0.01). In addition, the expression of miR-370 in melanoma cell lines was also significantly higher (P<0.01). Enforced expression of miR-370 promotes melanoma cell proliferation, inhibits apoptosis and enhances invasion and glycolysis and led to downregulation of the PDHB protein. Moreover, the expression level of miR-370 in melanoma tissues showed inverse relationship with the expression level of PDHB protein. CONCLUSIONS: In conclusion, our findings suggested that miR-370 represents a potential oncogenic miRNA and plays an important role in melanoma progression by directly targeting PDHB.

miR-146b-5p regulates cell growth, invasion, and metabolism by targeting PDHB in colorectal cancer.

MiRNA have been found to play a role in a plethora of cellular processes of cancer cells such as cell apoptosis, cell proliferation, invasion, migration metabolism and stem cell differentiation. Dysregulation of miR-146b-5p has been documented in a variety of human malignancies. However, the biological functions and molecular mechanisms of miR-146b-5p in ovarian cancer remain unknown. In this study, our results show that miR-146b-5p was unregulated in colorectal cancer (CRC) tissues compared with the adjacent non-cancerous tissues. Ectopic overexpression of miR-146b-5p in CRC promoted cell growth, invasion and glycolysis, while knockdown of miR-146b-5p inhibited the growth, invasion and glycolysis of CRC cells. The oncogenic effect of miR-146b-5p is also confirmed in vivo. Mechanically, miR-146b-5p targets the 3'-UTR of pyruvate dehydrogenase B (PDHB) and exerts oncogenic effect. Overexpression of PDHB abolished the oncogenic effects of miR-146b-5p on the growth, invasion and glycolysis of CRC cells. Taken together, our results show that miR-146b-5p is an oncogenic miRNA in CRC which exerts its effect by directly targeting PDHB.

The E1 beta-subunit of pyruvate dehydrogenase is surface-expressed in Lactobacillus plantarum and binds fibronectin.

Lactobacillus plantarum is among the species with a probiotic activity. Adhesion of probiotic bacteria to host tissues is an important principle for strain selection, because it represents a crucial step in the colonization process of either pathogens or commensals. Most bacterial adhesins are proteins, and a major target for them is fibronectin, an extracellular matrix glycoprotein. In this study we demonstrate that PDHB, a component of the pyruvate dehydrogenase complex, is a factor contributing to fibronectin-binding in L. plantarum LM3. By means of fibronectin overlay immunoblotting assay, we identified a L. plantarum LM3 surface protein with apparent molecular mass of 35 kDa. Mass spectrometric analysis shows that this protein is the pyruvate dehydrogenase E1 beta-subunit (PDHB). The corresponding pdhB gene is located in a 4-gene cluster encoding pyruvate dehydrogenase. In LM3-B1, carrying a null mutation in pdhB, the 35 kDa adhesin was not anymore detectable by immunoblotting assay. Nevertheless, the pdhB null mutation did not abolish pdhA, pdhC, and pdhD transcription in LM3-B1. By adhesion assays, we show that LM3-B1 cells bind to immobilized fibronectin less efficiently than wild type cells. Moreover, we show that pdhB expression is negatively regulated by the CcpA protein and is induced by bile.

Relationship between transcriptional expression of pyruvate dehydrogenase and local control of disease in patients with oral cavity carcinomas / Relación entre la expresión transcripcional de piruvato deshidrogenasa y el control local de la enfermedad en pacientes con cáncer en la cavidad oral

Background The altered cellular metabolism is one of the hallmarks of the cancer cells, favoring the process of aerobic glycolysis, known as the Warburg effect. The pyruvate dehydrogenase (PDH) complex is one of the elements involved in this metabolic process. The present study aims to evaluate the relationship between the transcriptional expression of PDHB and the risk of local recurrence in patients with oral cavity carcinomas. Methods We determined the transcriptional expression of PDHB in biopsies from 41 patients with oral cavity carcinomas treated with surgery. The PDHB expression was categorized according to the local control of the disease with a recursive partitioning analysis. Results During the follow-up period 13 patients (31.7%) had a local recurrence of the tumor. Considering local disease control as the dependent variable, the recursive partitioning analysis classified the patients in two categories according to high (n=16, 39.0%) or low (n=25, 61.0%) PDHB expression. Five-year local recurrence-free survival for patients with high PDHB expression was 84.8% (95% CI: 65.2-100%), and for patients with low expression it was 54.3% (95% CI: 34.3–74.2 %) (P=0.034). The results of multivariate analysis showed that patients with a low PDHB expression had a 4.90 times higher risk of local recurrence of the tumor (95% CI: 1.02–22.68, P=0.042). Conclusion There is a relationship between the metabolic characteristics of the tumor and its aggressiveness. According to our results, patients with oral cavity carcinomas with low transcriptional expression levels of PDHB have a significantly higher risk of local tumor recurrence. (AU)

Antecedentes La alteración del metabolismo celular es una de las características distintivas de las células cancerígenas, y favorece el proceso de la glucólisis aeróbica, conocido como efecto de Warburg. El complejo de piruvato deshidrogenasa (PDH) es uno de los elementos implicados en este proceso metabólico. El objetivo del presente estudio es evaluar la relación entre la expresión transcripcional de PDHB y el riesgo de recidiva local en los pacientes con cáncer en la cavidad oral. Métodos Determinamos la expresión transcripcional de PDHB en biopsias de 41 pacientes con cáncer en la cavidad oral tratados con cirugía. Se categorizó la expresión de PDHB de acuerdo con el control local de la enfermedad, con un análisis de partición recursiva. Resultados Durante el periodo de seguimiento, trece pacientes (31,7%) tuvieron una recidiva local del tumor. Considerando el control de la enfermedad local como variable dependiente, el análisis de partición recursiva clasificó a los pacientes en dos categorías, de acuerdo con la expresión de PDHB alta (n=16, 39%) o baja (n=25, 61%). La tasa de supervivencia libre de enfermedad a cinco años con expresión alta de PDHB fue del 84,8% (95% IC: 65,2–100%), siendo del 54,3% (95% IC: 34,3–74,2%) (P=0,034) para los pacientes con expresión baja. Los resultados del análisis multivariante reflejaron que los pacientes con expresión baja de PDHB tuvieron un riesgo 4,90 veces mayor de recidiva local del tumor (95% IC: 1,02–22,68, P=0,042). Conclusión Existe una relación entre las características metabólicas del tumor y su agresividad. Conforme a nuestros resultados, los pacientes con cáncer en la cavidad oral y bajos niveles transcripcionales de PDHB tienen un riesgo significativamente mayor de recidiva local del tumor. (AU)