Lactate dehydrogenase 5 (LDH5) relates to up-regulated hypoxia inducible factor pathway and metastasis in colorectal cancer

Metabolic reprogramming and immune evasion: the interplay in the tumor microenvironment

Tumor cells possess complex immune evasion mechanisms to evade immune system attacks, primarily through metabolic reprogramming, which significantly alters the tumor microenvironment (TME) to modulate immune cell functions. When a tumor is sufficiently immunogenic, it can activate cytotoxic T-cells to target and destroy it. However, tumors adapt by manipulating their metabolic pathways, particularly glucose, amino acid, and lipid metabolism, to create an immunosuppressive TME that promotes immune escape. These metabolic alterations impact the function and differentiation of non-tumor cells within the TME, such as inhibiting effector T-cell activity while expanding regulatory T-cells and myeloid-derived suppressor cells. Additionally, these changes lead to an imbalance in cytokine and chemokine secretion, further enhancing the immunosuppressive landscape. Emerging research is increasingly focusing on the regulatory roles of non-tumor cells within the TME, evaluating how their reprogrammed glucose, amino acid, and lipid metabolism influence their functional changes and ultimately aid in tumor immune evasion. Despite our incomplete understanding of the intricate metabolic interactions between tumor and non-tumor cells, the connection between these elements presents significant challenges for cancer immunotherapy. This review highlights the impact of altered glucose, amino acid, and lipid metabolism in the TME on the metabolism and function of non-tumor cells, providing new insights that could facilitate the development of novel cancer immunotherapies.

Involvement of tumor immune microenvironment metabolic reprogramming in colorectal cancer progression, immune escape, and response to immunotherapy

Metabolic reprogramming is a k`ey hallmark of tumors, developed in response to hypoxia and nutrient deficiency during tumor progression. In both cancer and immune cells, there is a metabolic shift from oxidative phosphorylation (OXPHOS) to aerobic glycolysis, also known as the Warburg effect, which then leads to lactate acidification, increased lipid synthesis, and glutaminolysis. This reprogramming facilitates tumor immune evasion and, within the tumor microenvironment (TME), cancer and immune cells collaborate to create a suppressive tumor immune microenvironment (TIME). The growing interest in the metabolic reprogramming of the TME, particularly its significance in colorectal cancer (CRC)-one of the most prevalent cancers-has prompted us to explore this topic. CRC exhibits abnormal glycolysis, glutaminolysis, and increased lipid synthesis. Acidosis in CRC cells hampers the activity of anti-tumor immune cells and inhibits the phagocytosis of tumor-associated macrophages (TAMs), while nutrient deficiency promotes the development of regulatory T cells (Tregs) and M2-like macrophages. In CRC cells, activation of G-protein coupled receptor 81 (GPR81) signaling leads to overexpression of programmed death-ligand 1 (PD-L1) and reduces the antigen presentation capability of dendritic cells. Moreover, the genetic and epigenetic cell phenotype, along with the microbiota, significantly influence CRC metabolic reprogramming. Activating RAS mutations and overexpression of epidermal growth factor receptor (EGFR) occur in approximately 50% and 80% of patients, respectively, stimulating glycolysis and increasing levels of hypoxia-inducible factor 1 alpha (HIF-1α) and MYC proteins. Certain bacteria produce short-chain fatty acids (SCFAs), which activate CD8+ cells and genes involved in antigen processing and presentation, while other mechanisms support pro-tumor activities. The use of immune checkpoint inhibitors (ICIs) in selected CRC patients has shown promise, and the combination of these with drugs that inhibit aerobic glycolysis is currently being intensively researched to enhance the efficacy of immunotherapy.

Metabolic pathways of glucose and fructose: II Spatiotemporal expression of genes involved in synthesis and transport of lactate in ovine conceptuses†

Lactate, an abundant molecule in fetal fluids and blood of mammalian species, is often overlooked as a metabolic waste product generated during pregnancy. Most of the glucose and fructose consumed by ovine conceptuses is converted to lactate, but proteins involved in lactate metabolism and transport have not been investigated. This study characterized total lactate produced by ovine conceptuses throughout gestation, as well as expression of mRNAs and proteins involved in lactate metabolism. Lactate increased in abundance in the uterine lumen during the preimplantation period and was more abundant than pyruvate. The abundance of lactate in allantoic and amniotic fluids increased with advancing days of gestation and most abundant on Day 125 of pregnancy (P < 0.05). Lactate dehydrogenase subunits A (converts pyruvate to lactate) and B (converts lactate to pyruvate) were expressed by conceptuses throughout gestation. Lactate is transported via monocarboxylic acid transporters SLC16A1 and SLC16A3, both of which were expressed by the conceptus throughout gestation. Additionally, the interplacentomal chorioallantois from Day 126 expressed SLC16A1 and SLC16A3 and transported lactate across the tissue. Hydrocarboxylic acid receptor 1 (HCAR1), a receptor for lactate, was localized to the uterine luminal and superficial glandular epithelia of pregnant ewes throughout gestation and conceptus trophectoderm during the peri-implantation period of gestation. These results provide novel insights into the spatiotemporal profiles of enzymes, transporters, and receptor for lactate by ovine conceptuses throughout pregnancy.

Stage-Specific Alteration and Prognostic Relationship of Serum Fumarate Hydratase Autoantibodies in Gastric Cancer

The relationship between energy production and cancer is attracting attention. This study aimed to investigate the clinicopathological significance of fumarate hydratase (FH), a tricarboxylic acid cycle enzyme, in gastric cancer using autoantibodies as biomarkers. The study analyzed 116 patients who underwent gastric cancer surgery and 96 healthy controls. Preoperative serum FH autoantibody (s-FH-Ab) titers were analyzed using an immunosorbent assay with an amplified luminescent proximity homogeneous assay. Receiver operating characteristic analysis was used to determine the cutoff s-FH-Ab titer. Clinicopathological factors and prognosis were compared between the high and low s-FH-Ab groups. The s-FH-Ab levels were significantly higher in the gastric cancer group than in the control group (p = 0.01). Levels were elevated even in patients with stage I gastric cancer compared with healthy controls (p = 0.02). A low s-FH-Ab level was significantly associated with distant metastasis (p = 0.01), peritoneal dissemination (p < 0.05), and poor overall survival (p < 0.01). Multivariate analysis revealed that low s-FH-Ab levels were an independent risk factor for poor prognosis (p < 0.01). Therefore, s-FH-Ab levels may be a useful biomarker for early diagnosis and the prediction of prognosis in patients with gastric cancer.

Targeting Lactate Dehydrogenase-B as a Strategy to Fight Cancer: Identification of Potential Inhibitors by In Silico Analysis and In Vitro Screening

Lactate dehydrogenase (LDH) is an enzyme that catalyzes the reversible conversion of lactate to pyruvate while reducing NAD+ to NADH (or oxidizing NADH to NAD+). Due to its central role in the Warburg effect, LDH-A isoform has been considered a promising target for treating several types of cancer. However, research on inhibitors targeting LDH-B isoform is still limited, despite the enzyme's implication in the development of specific cancer types such as breast and lung cancer. This study aimed to identify small-molecule compounds that specifically inhibit LDH-B. Our in silico analysis identified eight commercially available compounds that may affect LDH-B activity. The best five candidates, namely tucatinib, capmatinib, moxidectin, rifampicin, and acetyldigoxin, were evaluated further in vitro. Our results revealed that two compounds, viz., tucatinib and capmatinib, currently used for treating breast and lung cancer, respectively, could also act as inhibitors of LDH-B. Both compounds inhibited LDH-B activity through an uncompetitive mechanism, as observed in in vitro experiments. Molecular dynamics studies further support these findings. Together, our results suggest that two known drugs currently being used to treat specific cancer types may have a dual effect and target more than one enzyme that facilitates the development of these types of cancers. Furthermore, the results of this study could be used as a new starting point for identifying more potent and specific LDH-B inhibitors.

Effect of serum lactate dehydrogenase-to-albumin ratio (LAR) on the short-term outcomes and long-term prognosis of colorectal cancer after radical surgery

BACKGROUND

Whether serum lactate dehydrogenase-to-albumin ratio (LAR) influenced the outcomes of colorectal cancer (CRC) patients after radical surgery remained unclear. Therefore, this study sought to examine how LAR influences the short-term and long-term outcomes of CRC patients who have undergone radical surgery.

METHODS

This study retrospectively included CRC patients who underwent radical resection between January 2011 and January 2020. We compared short-term outcomes, as well as overall survival (OS) and disease-free survival (DFS), among various groups. Both univariate and multivariate logistic regression analyses were utilized to pinpoint independent risk factors associated with overall complications and major complications. Moreover, Cox regression analysis were conducted for OS and DFS. Odds ratio (OR) and Hazard ratio (HR) were adjusted.

RESULTS

This study encompassed a cohort of 3868 patients. 3440 patients were in the low LAR group and 428 patients constituted the high LAR group. In the high LAR group, patients experienced significantly longer operative times (p < 0.01), larger intraoperative blood loss (p < 0.01), and extended postoperative hospital stays (p < 0.01). Additionally, the incidence of both overall complications (p < 0.01) and major complications (p < 0.01) was higher in the high LAR group compared to the low LAR group. Furthermore, LAR was emerged as an independent prognostic factor for overall complications [OR/95% CI: (1.555/1.237 to 1.954), p < 0.01] and major complications [OR/95% CI: (2.178/1.279 to 3.707), p < 0.01]. As for long-term survival, the high LAR group had worse OS in stage II (p < 0.01) and stage III (p < 0.01). In both stage II (p < 0.01) and stage III (p < 0.01), the high LAR group exhibited poorer DFS. Additionally, according to Cox regression analysis, LAR was identified as an independent predictor for both OS [HR/95% CI: (1.930/1.554 to 2.398), p < 0.01] and DFS [HR/95% CI: (1.750/1.427 to 2.146), p < 0.01].

CONCLUSION

LAR emerged as an independent predictor not only for overall complications and major complications but also for both OS and DFS, highlighting its significance and deserving the attention of surgeons.

Hyperpolarized Carbon 13 MRI: Clinical Applications and Future Directions in Oncology

Hyperpolarized carbon 13 MRI (13C MRI) is a novel imaging approach that can noninvasively probe tissue metabolism in both normal and pathologic tissues. The process of hyperpolarization increases the signal acquired by several orders of magnitude, allowing injected 13C-labeled molecules and their downstream metabolites to be imaged in vivo, thus providing real-time information on kinetics. To date, the most important reaction studied with hyperpolarized 13C MRI is exchange of the hyperpolarized 13C signal from injected [1-13C]pyruvate with the resident tissue lactate pool. Recent preclinical and human studies have shown the role of several biologic factors such as the lactate dehydrogenase enzyme, pyruvate transporter expression, and tissue hypoxia in generating the MRI signal from this reaction. Potential clinical applications of hyperpolarized 13C MRI in oncology include using metabolism to stratify tumors by grade, selecting therapeutic pathways based on tumor metabolic profiles, and detecting early treatment response through the imaging of shifts in metabolism that precede tumor structural changes. This review summarizes the foundations of hyperpolarized 13C MRI, presents key findings from human cancer studies, and explores the future clinical directions of the technique in oncology. Keywords: Hyperpolarized Carbon 13 MRI, Molecular Imaging, Cancer, Tissue Metabolism © RSNA, 2023.

Chromosomal aberrations and prognostic analysis of secondary acute myeloid leukemia-a retrospective study

Background

Secondary acute myeloid leukemia (S-AML) patients generally have a poor prognosis, but the chromosomal aberrations of S-AML have been rarely reported. We aimed to explore the chromosomal aberrations and clinical significance in patients with S-AML.

Patients and methods

The clinical characteristics and karyotypes of 26 patients with S-AML were retrospectively analyzed. The overall survival (OS) was measured from the time of the patients' transition to AML (i.e., at S-AML diagnosis).

Results

The study included 26 S-AML patients (13 males and 13 females), with a median age of 63 years (range, 20-77 years). They transformed from various hematologic malignancies or solid tumors; most of them were secondary to myelodysplastic syndrome (MDS). About 62% of the S-AML patients showed chromosomal aberrations. The serum lactate dehydrogenase (LDH) level in S-AML patients with abnormal karyotype was higher than those with normal karyotype. Apart from the differences in treatment regimens, S-AML patients with chromosomal aberrations had shorter OS (P < 0.05).

Conclusion

S-AML patients with abnormal karyotype have higher LDH levels and shorter OS than normal karyotype patients, and the OS of hypodiploidy was much shorter than hyperdiploid.

Machine learning-based glycolysis-associated molecular classification reveals differences in prognosis, TME, and immunotherapy for colorectal cancer patients

Background

Aerobic glycolysis is a process that metabolizes glucose under aerobic conditions, finally producing pyruvate, lactic acid, and ATP for tumor cells. Nevertheless, the overall significance of glycolysis-related genes in colorectal cancer and how they affect the immune microenvironment have not been investigated.

Methods

By combining the transcriptome and single-cell analysis, we summarize the various expression patterns of glycolysis-related genes in colorectal cancer. Three glycolysis-associated clusters (GAC) were identified with distinct clinical, genomic, and tumor microenvironment (TME). By mapping GAC to single-cell RNA sequencing analysis (scRNA-seq), we next discovered that the immune infiltration profile of GACs was similar to that of bulk RNA sequencing analysis (bulk RNA-seq). In order to determine the kind of GAC for each sample, we developed the GAC predictor using markers of single cells and GACs that were most pertinent to clinical prognostic indications. Additionally, potential drugs for each GAC were discovered using different algorithms.

Results

GAC1 was comparable to the immune-desert type, with a low mutation probability and a relatively general prognosis; GAC2 was more likely to be immune-inflamed/excluded, with more immunosuppressive cells and stromal components, which also carried the risk of the poorest prognosis; Similar to the immune-activated type, GAC3 had a high mutation rate, more active immune cells, and excellent therapeutic potential.

Conclusion

In conclusion, we combined transcriptome and single-cell data to identify new molecular subtypes using glycolysis-related genes in colorectal cancer based on machine-learning methods, which provided therapeutic direction for colorectal patients.

ME2 Promotes Hepatocellular Carcinoma Cell Migration through Pyruvate

Cancer metastasis is still a major challenge in clinical cancer treatment. The migration and invasion of cancer cells into surrounding tissues and blood vessels is the primary step in cancer metastasis. However, the underlying mechanism of regulating cell migration and invasion are not fully understood. Here, we show the role of malic enzyme 2 (ME2) in promoting human liver cancer cell lines SK-Hep1 and Huh7 cells migration and invasion. Depletion of ME2 reduces cell migration and invasion, whereas overexpression of ME2 increases cell migration and invasion. Mechanistically, ME2 promotes the production of pyruvate, which directly binds to β-catenin and increases β-catenin protein levels. Notably, pyruvate treatment restores cell migration and invasion of ME2-depleted cells. Our findings provide a mechanistic understanding of the link between ME2 and cell migration and invasion.

CircRNAs: emerging factors for regulating glucose metabolism in colorectal cancer

Colorectal cancer is a malignant disease with a high incidence and low survival rate, and the effectiveness of traditional treatments, such as surgery and radiotherapy, is very limited. CircRNAs, a kind of stable endogenous circular RNA, generally function by sponging miRNAs and binding or translating proteins. CircRNAs have been identified to play an important role in regulating the proliferation and metabolism of CRC. In recent years, many reports have indicated that by regulating the expression of glycolysis-related proteins, such as GLUT1 and HK2, or directly translating proteins, circRNAs can promote the Warburg effect in cancer cells, thereby driving CRC metabolism. Moreover, the Warburg effect increases lactate production in cancer cells and promotes acidification of the TME, which further drives cancer progression. In this review, we summarized the remarkable role of circRNAs in regulating glucose metabolism in CRC in recent years, which might be useful for finding new targets for the clinical treatment of CRC.

Tumor Microenvironment and Immune Response in Lip Cancer

Tumor-infiltrating lymphocytes (TILs) play a significant role in cancer progression and prognosis of patients. The tumor microenvironment (TME) may affect the anti-tumor immune response. We examined the TIL and tertiary lymphoid structure (TLS) density in the invading front and inner tumor stroma, and the lymphocyte subpopulation (CD8, CD4, FOXP3) density in 60 squamous cell carcinomas of the lip. Analysis was performed in parallel with markers of hypoxia (hypoxia-inducible factor (HIF1α), lactate dehydrogenase (LDHA)) and angiogenesis. Low TIL density in the invading tumor front was related with larger tumor size (p = 0.05), deep invasion (p = 0.01), high smooth-muscle actin (SMA) expression (p = 0.01), and high HIF1α and LDH5 expression (p = 0.04). FOXP3⁺ TILs infiltration and FOXP3⁺/CD8⁺ ratios were higher in inner tumor areas, linked with LDH5 expression, and higher MIB1 proliferation index (p = 0.03) and SMA expression (p = 0.001). Dense CD4⁺ lymphocytic infiltration in the invading front is related to high tumor-budding (TB) (p = 0.04) and angiogenesis (p = 0.04 and p = 0.006, respectively). Low CD8⁺ TIL density, high CD20⁺ B-cell density, high FOXP3⁺/CD8⁺ ratio and high CD68⁺ macrophage presence characterized tumors with local invasion (p = 0.02, 0.01, 0.02 and 0.006, respectively). High angiogenic activity was linked with high CD4⁺, FOXP3⁺, and low CD8⁺ TIL density (p = 0.05, 0.01 and 0.01, respectively), as well as high CD68⁺ macrophage presence (p = 0.003). LDH5 expression was linked with high CD4⁺ and FOXP3⁺ TIL density (p = 0.05 and 0.01, respectively). Further research is needed to explore the prognostic and therapeutic value of TME/TIL interactions.

Understanding the Contribution of Lactate Metabolism in Cancer Progress: A Perspective from Isomers

Lactate mediates multiple cell-intrinsic effects in cancer metabolism in terms of development, maintenance, and metastasis and is often correlated with poor prognosis. Its functions are undertaken as an energy source for neighboring carcinoma cells and serve as a lactormone for oncogenic signaling pathways. Indeed, two isomers of lactate are produced in the Warburg effect: L-lactate and D-lactate. L-lactate is the main end-production of glycolytic fermentation which catalyzes glucose, and tiny D-lactate is fabricated through the glyoxalase system. Their production inevitably affects cancer development and therapy. Here, we systematically review the mechanisms of lactate isomers production, and highlight emerging evidence of the carcinogenic biological effects of lactate and its isomers in cancer. Accordingly, therapy that targets lactate and its metabolism is a promising approach for anticancer treatment.

Gum Arabic nanoformulation rescues neuronal lesions in bromobenzene-challenged rats by its antioxidant, anti-apoptotic and cytoprotective potentials

Bromobenzene (BB) is a hazardous environmental contaminant because of its multiple routes of exposure and the toxicity of its bio-derivates. It could elicit neuronal alterations by stimulating redox imbalance and apoptotic pathways. Gum Arabic (GA) protected the hippocampus of a type 2 diabetic rat model from cognitive decline. Whether gum Arabic nanoemulsion (GANE) can increase the neuroprotectant potency of GA in fighting BB-associated neurological lesions is the question to be answered. To accomplish this objective, 25 adult male Wistar rats were randomly and equally assigned into five groups. Control received olive oil (vehicle of BB). BB group received BB at a dose of 460 mg/kg BW. Blank nanoemulsion (BNE) group supplemented with BNE at 2 mL of 10% w/v aqueous suspension/kg BW. GANE group received GANE at a dose of 2 mL of 10% w/v aqueous suspension/kg BW. BB + GANE group exposed to BB in concomitant with GANE at the same previous doses. All interventions were carried out daily by oral gavage for ten consecutive days. BB caused a marked increase in malondialdehyde and succinate dehydrogenase together with a marked decrease in reduced glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and lactate dehydrogenase in the brain. BB was accompanied by pathological deteriorations, amyloidosis, and reduced immuno-expression of integrase interactor 1 in the hippocampal region. Administration of GANE was beneficial in reversing the aforementioned abnormalities. These results pave the road for further discovery of nano-formulated natural products to counter the threats of BB.

Lactate dehydrogenases promote glioblastoma growth and invasion via a metabolic symbiosis

Lactate is a central metabolite in brain physiology but also contributes to tumor development. Glioblastoma (GB) is the most common and malignant primary brain tumor in adults, recognized by angiogenic and invasive growth, in addition to its altered metabolism. We show herein that lactate fuels GB anaplerosis by replenishing the tricarboxylic acid (TCA) cycle in absence of glucose. Lactate dehydrogenases (LDHA and LDHB), which we found spatially expressed in GB tissues, catalyze the interconversion of pyruvate and lactate. However, ablation of both LDH isoforms, but not only one, led to a reduction in tumor growth and an increase in mouse survival. Comparative transcriptomics and metabolomics revealed metabolic rewiring involving high oxidative phosphorylation (OXPHOS) in the LDHA/B KO group which sensitized tumors to cranial irradiation, thus improving mouse survival. When mice were treated with the antiepileptic drug stiripentol, which targets LDH activity, tumor growth decreased. Our findings unveil the complex metabolic network in which both LDHA and LDHB are integrated and show that the combined inhibition of LDHA and LDHB strongly sensitizes GB to therapy.

Lactate: A regulator of immune microenvironment and a clinical prognosis indicator in colorectal cancer

Lactate can play an immunosuppressive role in the tumor microenvironment and promote tumor development by recruiting and inducing the activity of immunosuppressive cells and molecules. High lactate concentrations are important for tumor cell metastasis, angiogenesis, and treatment resistance. With the in-depth studies on tumor metabolism, lactate, one of the key factors involved in glycolysis, has been increasing emerged its characteristic clinical value in colorectal cancer (CRC). In this study, lactate genes were screened based on lactate metabolism pathways. Subsequently, the lactate subtypes were determined by clustering and analysis of the subtypes at all levels, including immune checkpoints, immune infiltration, and clinical characteristics, which revealed the biological significance of lactate metabolism in CRC. Subtype-based differential gene analysis resulted in a lactate score, which stratifies the prognosis of CRC. We discovered that 27 lactate genes and 61 lactate-phenotype genes are associated with immune cell infiltration and have a significant prognostic efficacy. The CRC patients were clustered into four subtypes and five clusters, based on lactate genes and lactate-phenotype genes, respectively. There are significant differences in survival time and activities of hallmark pathways, namely immune-related signatures and chemokines, among these subtypes and clusters. Particularly, cluster 2 and subtype 1 have significantly higher lactate scores than that of the others. In conclusion, lactate score is an independent prognostic factor for cancer that can be used as a clinical guide for predicting CRC progression and as an evaluation factor for the effect of immunotherapy in CRC.

Digitoxin Affects Metabolism, ROS Production and Proliferation in Pancreatic Cancer Cells Differently Depending on the Cell Phenotype

Digitoxin has repeatedly shown to have negative effects on cancer cell viability; however, the actual mechanism is still unknown. In this study, we investigated the effects of digitoxin (1-100 nM) in four pancreatic cancer cell lines, BxPC-3, CFPAC-1, Panc-1, and AsPC-1. The cell lines differ in their KRAS/BRAF mutational status and primary tumor or metastasis origin. We could detect differences in the basal rates of cell proliferation, glycolysis, and ROS production, giving the cell lines different phenotypes. Digitoxin treatment induced apoptosis in all four cell lines, but to different degrees. Cells derived from primary tumors (Panc-1 and BxPC-3) were highly proliferating with a high proportion of cells in the S/G2 phase, and were more sensitive to digitoxin treatment than the cell lines derived from metastases (CFPAC-1 and AsPC-1), with a high proportion of cells in G0/G1. In addition, the effects of digitoxin on the rate of glycolysis, ROS production, and proliferation were dependent on the basal metabolism and origin of the cells. The KRAS downstream signaling pathways were not altered by digitoxin treatment, thus the effects exerted by digitoxin were probably disconnected from these signaling pathways. We conclude that digitoxin is a promising treatment in highly proliferating pancreatic tumors.

Treatment Approaches and Outcome of Patients with Neuroendocrine Neoplasia Grade 3 in German Real-World Clinical Practice

BACKGROUND

Neuroendocrine neoplasia grade 3 (NEN G3) represents a rare and heterogeneous cancer type with a poor prognosis. The aim of our study was to analyze real-world data from the German NET Registry with a focus on therapeutic and prognostic aspects.

METHODS

NEN G3 patients were identified within the German NET Registry. Demographic data and data on treatments and outcomes were retrieved. Univariate analyses were performed using the Kaplan-Meier-method. Multivariate analysis was performed using a Cox proportional hazard model.

RESULTS

Of 445 included patients, 318 (71.5%) were diagnosed at stage IV. Well-differentiated morphology (NET G3) was described in 31.7%, 60% of cases were classified as neuroendocrine carcinoma (NEC), and the median Ki67 value was 50%. First-line treatment comprised chemotherapy in 43.8%, with differences in the choice of regimen with regard to NET or NEC, and surgery in 41.6% of patients. Median overall survival for the entire cohort was 31 months. Stage, performance status and Ki67 were significant prognostic factors in multivariate analysis.

CONCLUSIONS

The survival data of our national registry compare favorably to population-based data, probably mainly because of a relatively low median Ki67 of 50%. Nevertheless, the best first- and second-line approaches for specific subgroups remain unclear, and an international effort to fill these gaps is needed.

Lactate Dehydrogenase B Is Required for Pancreatic Cancer Cell Immortalization Through Activation of Telomerase Activity

Telomerase activity is elevated in most cancer cells and is required for telomere length maintenance and immortalization of cancer cells. Glucose metabolic reprogramming is a hallmark of cancer and accompanied with increased expression of key metabolic enzymes. Whether these enzymes influence telomerase activity and cell immortalization remains unclear. In the current study, we screened metabolic enzymes using telomerase activity assay and identified lactate dehydrogenase B (LDHB) as a regulator of telomerase activity. Sodium lactate and sodium pyruvate did not influence telomerase activity, indicating LDHB regulates telomerase activity independent of its metabolism regulating function. Further studies revealed that LDHB directly interacted with TERT and regulated the interaction between TERT and TERC. Additionally, long-term knockdown of LDHB inhibited cancer cell growth and induced cell senescence in vitro and in vivo. Higher LDHB expression was detected in pancreatic cancer tissues compared with that in adjacent normal tissues and expression of LDHB correlated negatively with prognosis. Thus, we identified LDHB as the first glucose metabolic enzyme contributing to telomerase activity and pancreatic cancer cell immortalization.

LDH-A—Modulation and the Variability of LDH Isoenzyme Profiles in Murine Gliomas: A Link with Metabolic and Growth Responses

Three murine glioma cell lines (GL261, CT2A, and ALTS1C1) were modified to downregulate the expression of the murine LDH-A gene using shRNA, and compared to shRNA scrambled control (NC) cell lines. Differences in the expression of LDH-A and LDH-B mRNA, protein and enzymatic activity, as well as their LDH isoenzyme profiles, were observed in the six cell lines, and confirmed successful LDH-A KD. LDH-A KD (knock-down) resulted in metabolic changes in cells with a reduction in glycolysis (GlycoPER) and an increase in basal respiratory rate (mitoOCR). GL261 cells had a more limited ATP production capacity compared to CT2A and ALTS1C1 cells. An analysis of mRNA expression data indicated that: (i) GL261 LDH-A KD cells may have an improved ability to metabolize lactate into the TCA cycle; and (ii) that GL261 LDH-A KD cells can upregulate lipid metabolism/fatty acid oxidation pathways, whereas the other glioma cell lines do not have this capacity. These two observations suggest that GL261 LDH-A KD cells can develop/activate alternative metabolic pathways for enhanced survival in a nutrient-limited environment, and that specific nutrient limitations have a variable impact on tumor cell metabolism and proliferation. The phenotypic effects of LDH-A KD were compared to those in control (NC) cells and tumors. LDH-A KD prolonged the doubling time of GL261 cells in culture and prevented the formation of subcutaneous flank tumors in immune-competent C57BL/6 mice, whereas GL261 NC tumors had a prolonged growth delay in C57BL/6 mice. In nude mice, both LDH-A KD and NC GL261 tumors grew rapidly (more rapidly than GL261 NC tumors in C57BL/6 mice), demonstrating the impact of an intact immune system on GL261 tumor growth. No differences between NC and KD cell proliferation (in vitro) or tumor growth in C57BL/6 mice (doubling time) were observed for CT2A and ALTS1C1 cells and tumors, despite the small changes to their LDH isoenzyme profiles. These results suggest that GL261 glioma cells (but not CT2A and ALTS1C1 cells) are pre-programmed to have the capacity for activating different metabolic pathways with higher TCA cycle activity, and that this capacity is enhanced by LDH-A depletion. We observed that the combined impact of LDH-A depletion and the immune system had a significant impact on the growth of subcutaneous-located GL261 tumors.

Tumor-Derived Lactic Acid Modulates Activation and Metabolic Status of Draining Lymph Node Stroma

Communication between tumors and the stroma of tumor-draining lymph nodes (TDLN) exists before metastasis arises, altering the structure and function of the TDLN niche. Transcriptional profiling of fibroblastic reticular cells (FRC), the dominant stromal population of lymph nodes, has revealed that FRCs in TDLNs are reprogrammed. However, the tumor-derived factors driving the changes in FRCs remain to be identified. Taking an unbiased approach, we have shown herein that lactic acid (LA), a metabolite released by cancer cells, was not only secreted by B16.F10 and 4T1 tumors in high amounts, but also that it was enriched in TDLNs. LA supported an upregulation of Podoplanin (Pdpn) and Thy1 and downregulation of IL7 in FRCs of TDLNs, making them akin to activated fibroblasts found at the primary tumor site. Furthermore, we found that tumor-derived LA altered mitochondrial function of FRCs in TDLNs. Thus, our results demonstrate a mechanism by which a tumor-derived metabolite connected with a low pH environment modulates the function of fibroblasts in TDLNs. How lymph node function is perturbed to support cancer metastases remains unclear. The authors show that tumor-derived LA drains to lymph nodes where it modulates the function of lymph node stromal cells, prior to metastatic colonization.

Targeting lactate metabolism and glycolytic pathways in the tumor microenvironment by natural products: A promising strategy in combating cancer

Anticancer drugs are not purely effective because of their toxicity, side effects, high cost, inaccessibility, and associated resistance. On the other hand, cancer is a complex public health problem that could intelligently adopt different signaling pathways and alter the body's metabolism to escape from the immune system. One of the cancer strategies to metastasize is modifying pH in the tumor microenvironment, ranging between 6.5 and 6.9. As a powerful determiner, lactate is responsible for this acidosis. It is involved in immune stimulation, including innate and adaptive immunity, apoptotic-related factors (Bax/Bcl-2, caspase), and glycolysis pathways (e.g., GLUT-1, PKM2, PFK, HK2, MCT-1, and LDH). Lactate metabolism, in turn, is interconnected with several dysregulated signaling mediators, including PI3K/Akt/mTOR, AMPK, NF-κB, Nrf2, JAK/STAT, and HIF-1α. Because of lactate's emerging and critical role, targeting lactate production and its transporters is important for preventing and managing tumorigenesis. Hence, exploring and developing novel promising anticancer agents to minimize human cancers is urgent. Based on numerous studies, natural secondary metabolites as multi-target alternative compounds with health-promoting properties possess more high effectiveness and low side effects than conventional agents. Besides, the mechanism of multi-targeted natural sources is related to lactate production and cancer-associated cross-talked factors. This review focuses on targeting the lactate metabolism/transporters, and lactate-associated mediators, including glycolytic pathways. Besides, interconnected mediators to lactate metabolism are also targeted by natural products. Accordingly, plant-derived secondary metabolites are introduced as alternative therapies in combating cancer through modulating lactate metabolism and glycolytic pathways.

Oncometabolites-A Link between Cancer Cells and Tumor Microenvironment

The tumor microenvironment is the space between healthy tissues and cancer cells, created by the extracellular matrix, blood vessels, infiltrating cells such as immune cells, and cancer-associated fibroblasts. These components constantly interact and influence each other, enabling cancer cells to survive and develop in the host organism. Accumulated intermediate metabolites favoring dysregulation and compensatory responses in the cell, called oncometabolites, provide a method of communication between cells and might also play a role in cancer growth. Here, we describe the changes in metabolic pathways that lead to accumulation of intermediate metabolites: lactate, glutamate, fumarate, and succinate in the tumor and their impact on the tumor microenvironment. These oncometabolites are not only waste products, but also link all types of cells involved in tumor survival and progression. Oncometabolites play a particularly important role in neoangiogenesis and in the infiltration of immune cells in cancer. Oncometabolites are also associated with a disrupted DNA damage response and make the tumor microenvironment more favorable for cell migration. The knowledge summarized in this article will allow for a better understanding of associations between therapeutic targets and oncometabolites, as well as the direct effects of these particles on the formation of the tumor microenvironment. In the future, targeting oncometabolites could improve treatment standards or represent a novel method for fighting cancer.

Hippocalcin-like 1 is a key regulator of LDHA activation that promotes the growth of non-small cell lung carcinoma

BACKGROUND

Hippocalcin-like 1 (HPCAL1), a neuronal calcium sensor protein family member, has been reported to regulate cancer growth. As yet, however, the biological functions of HPCAL1 and its molecular mechanisms have not been investigated in non-small cell lung carcinoma (NSCLC).

METHODS

HPCAL1 expression in NSCLC samples was detected using immunohistochemistry, Western blotting and RT-PCR. The anticancer effects of HPCAL1 knockdown were determined by MTT, soft agar, cell cycle, oxygen consumption and reactive oxygen species assays. The effect of HPCAL1 knockdown on in vivo tumor growth was assessed using NSCLC cancer patient-derived xenograft models. Potentially interacting protein partners of HPCAL1 were identified using IP-MS/MS, immunoprecipitation and Western blotting assays. Metabolic alterations resulting from HPCAL1 knockdown were investigated using non-targeted metabolomics and RNA sequencing analyses.

RESULTS

We found that HPCAL1 is highly expressed in NSCLC tissues and is positively correlated with low survival rates and AJCC clinical staging in lung cancer patients. Knockdown of HPCAL1 strongly increased oxygen consumption rates and the production of reactive oxygen species. HPCAL1 knockdown also inhibited NSCLC cell growth and patient-derived NSCLC tumor growth in vivo. Mechanistically, we found that HPCAL1 can directly bind to LDHA and enhance SRC-mediated phosphorylation of LDHA at tyrosine 10. The metabolomics and RNA sequencing analyses indicated that HPCAL1 knockdown reduces amino acid levels and induces fatty acid synthesis through regulating the expression of metabolism-related genes. Additionally, rescued cells expressing wild-type or mutant LDHA in HPCAL1 knockdown cells suggest that LDHA may serve as the main substrate of HPCAL1.

CONCLUSIONS

Our data indicate that the effect of HPCAL1 knockdown on reducing SRC-mediated LDHA activity attenuates NSCLC growth. Our findings reveal novel biological functions and a mechanism underlying the role of HPCAL1 in NSCLC growth in vitro and in vivo.

[OVERALL SURVIVAL EVALUATION OF PROSTATE CANCER PATIENTS TREATED WITH ANDROGEN DEPRIVATION THERAPY BY ESTIMATING FLUCTUANT PATTERNS OF METABOLIC FACTOR SERUM LEVELS]

(Background) The effects of fluctuant patterns of serum alkaline phosphatase (ALP) and lactic acid dehydrogenase (LDH) levels on overall survival of patients with prostate cancer (PC) treated with androgen deprivation therapy (ADT) remain unclear. (Methods) We enrolled 236 patients with PC and divided into 3 cohorts by fluctuant patterns of serum levels of ALP and LDH between at baseline and at 1 year later, or at diagnosis of castration-resistant prostate cancer (CRPC): intermediate, within interquartile range (IQR) [I]; lower than IQR [L]; higher than IQR [H]. (Results) In the 1 year later ALP cohort, all parameters except age were significantly different. In the L cohort, 75% of patients had bone metastasis and > 50% developed CRPC or died. In the 1 year later LDH cohort, Eastern Cooperative Oncology Group-performance status (ECOG-PS) and clinical metastasis classification were significantly different among the cohorts. In the CRPC/ALP cohorts, baseline prostate-specific antigen values and clinical metastasis classification were significantly different among the cohorts, and all cases had metastasis in the L cohort. In the CRPC/LDH cohort, the L cohort had higher ECOG-PS and shorter time to CRPC. In the 1 year later ALP cohort, the hazard ratio (HR) for death of the L and H cohort to the I cohort was 3.77 and 2.27, respectively and both were significant. In the CRPC/LDH cohort, the HR for death of L cohort to I cohort was 1.99. (Conclusions) Larger fluctuations in serum ALP and LDH levels were a sign of poorer prognosis, especially for patients in the L cohort.

Lactate Dehydrogenase A or B Knockdown Reduces Lactate Production and Inhibits Breast Cancer Cell Motility in vitro

Background: Lactate dehydrogenase (LDH) plays an important role in cancer pathogenesis and enhanced expression/activity of this enzyme has been correlated with poor prognosis. In this study we determined the expression profile of LDH-A and B in normal as well as in endocrine-resistant and -responsive breast cancer cells and the effect of their knockdown on LDH activity, lactate production, proliferation and cell motility.

Methods: Knockdown experiments were performed using siRNA and shRNA. The expression profile of LDH and signaling molecules was determined using PCR and western blotting. Intracellular LDH activity and extracellular lactate levels were measured by a biochemical assay. Cell motility was determined using wound healing, while proliferation was determined using MTT assay.

Results: LDH-A was expressed in all of the tested cell lines, while LDH-B was specifically expressed only in normal and endocrine-resistant breast cancer cells. This was correlated with significantly enhanced LDH activity and lactate production in endocrine resistant breast cancer cells when compared to normal or endocrine responsive cancer cells. LDH-A or -B knockdown significantly reduced LDH activity and lactate production, which led to reduced cell motility. Exogenous lactate supplementation enhanced cell motility co-incident with enhanced phosphorylation of ERK1/2 and reduced E-cadherin expression. Also, LDH-A or -B knockdown reduced ERK 1/2 phosphorylation.

Conclusion: Enhanced cell motility in endocrine resistant breast cancer cells is at least in part mediated by enhanced extracellular lactate levels, and LDH inhibition might be a promising therapeutic target to inhibit cancer cell motility.

Value of pretreatment serum lactate dehydrogenase as a prognostic and predictive factor for small-cell lung cancer patients treated with first-line platinum-containing chemotherapy

BACKGROUND

The current study aimed to evaluate the serum pretreatment lactate dehydrogenase (LDH) and overall survival (OS) in small cell lung cancer (SCLC) patients who received first-line platinum-containing chemotherapy.

METHODS

A total of 234 SCLC patients, who received first-line platinum-based chemotherapy between 2013 and 2018, were retrospectively analyzed. The data of hematological characteristics, age, gender, ECOG score, staging, metastatic site, smoking history, chemotherapy cycle, thoracic radiotherapy and hyponatremia were collected. Overall survival was calculated using the Kaplan-Meier method. The statistically significant factors in the univariate analysis were selected for the multivariate COX model analysis.

RESULTS

Age, ECOG score, stage, thoracic radiotherapy, hyponatremia, liver metastasis, brain metastasis, bone metastasis, LDH, NSE and neutrophil-to-lymphocyte ratio (NLR) were closely correlated to OS in the univariate analysis. Furthermore, the multivariate analysis revealed that age (<65 years), ECOG score (<2 points), limited-stage (LD), thoracic radiotherapy and LDH <215.70 U/L were the independent prognostic factors for survival. The median OS time was worse for patients with LDH ≥215.70 U/L. In the subgroup analysis, LDH ≥215.70 U/L was significant for survival in both limited and extensive disease. Patients who achieved CR + PR in the first-line treatment had lower initial LDH levels. It was found that the pretreatment LDH increased the incidence of patients with liver metastasis.

CONCLUSIONS

Positive independent prognostic factors for SCLC patients were age < 65 years old, ECOG score < 2 points, LD-SCLC, and pretreatment LDH <215.70 U/L. These factors may be useful for stratifying patients with SCLC for treatment approaches.

KEY POINTS

SIGNIFICANT FINDINGS OF THE STUDY: Age < 65 years old, ECOG score < 2 points, LD-SCLC, and pretreatment LDH <215.70 U/L are the positive independent prognostic factors for SCLC patients.

WHAT THIS STUDY ADDS

The current study provided more references for SCLC diagnosis and treatment and determined more factors for stratifying patients with SCLC for treatment approaches.

Ethoxyquin Inhibits the Progression of Murine Ehrlich Ascites Carcinoma through the Inhibition of Autophagy and LDH

Cancer cells exhibit an increased glycolysis rate for ATP generation (the Warburg effect) to sustain an increased proliferation rate. In tumor cells, the oxidation of pyruvate in the Krebs cycle is substituted by lactate production, catalyzed by LDH. In this study, we use ethoxyquin (EQ) as a novel inhibitor to target LDH in murine Ehrlich ascites carcinoma (EAC) and as a combination therapy to improve the therapeutic efficacy of the conventional chemotherapy drug, cisplatin (CIS). We investigated the anti-tumor effect of EQ on EAC-bearing mice and checked whether EQ can sustain the anti-tumor potential of CIS and whether it influences LDH activity. Treatment with EQ had evident anti-tumor effects on EAC as revealed by the remarkable decrease in the expression of the anti-apoptotic gene Bcl-2 and by a significant increase in the expression of apoptotic genes (BAX and caspase-3). EQ also caused a significant decrease in the autophagic activity of EAC cells, as shown by a reduction in the fluorescence intensity of the autophagosome marker. Additionally, EQ restored the altered hematological and biochemical parameters and improved the disrupted hepatic tissues of EAC-bearing mice. Co-administration of EQ and CIS showed the highest anti-tumor effect against EAC. Collectively, our findings propose EQ as a novel inhibitor of LDH in cancer cells and as a combinatory drug to increase the efficacy of cisplatin. Further studies are required to validate this therapeutic strategy in different cancer models and preclinical trials.

The prognostic value of preoperative serum lactate dehydrogenase levels in patients underwent curative-intent hepatectomy for colorectal liver metastases: A two-center cohort study

Background

The prognostic value of lactate dehydrogenase (LDH) in colorectal cancer patients has remained inconsistent between nonmetastatic and metastatic settings. So far, very few studies have included LDH in the prognostic analysis of curative‐intent surgery for colorectal liver metastases (CRLM).

Patients and Methods

Five hundred and eighty consecutive metastatic colorectal cancer patients who underwent curative‐intent CRLM resection from Sun Yat‐sen University Cancer Center (434 patients) and Sun Yat‐sen University Sixth Affiliated Hospital (146 patients) in 2000–2019 were retrospectively collected. Overall survival (OS) was the primary end point. Cox regression model was performed to identify the prognostic values of preoperative serum LDH levels and other clinicopathology variables. A modification of the established Fong CRS scoring system comprising LDH was developed within this Chinese population.

Results

At the median follow‐up time of 60.5 months, median OS was 59.5 months in the pooled cohort. In the multivariate analysis, preoperative LDH >upper limit of normal (250 U/L) was the strongest independent prognostic factor for OS (HR 1.73, 95% confidence interval [CI], 1.22–2.44; p < 0.001). Patients with elevated LDH levels showed impaired OS than patients with normal LDH levels (27.6 months vs. 68.8 months). Five‐year survival rates were 53.7% and 22.5% in the LDH‐normal group and LDH‐high group, respectively. Similar results were also confirmed in each cohort. In the subgroup analysis, LDH could distinguish the survival regardless of most established prognostic factors (number and size of CRLM, surgical margin, extrahepatic metastases, CEA, and CA19‐9 levels, etc.). Integrating LDH into the Fong score contributed to an improvement in the predictive value.

Conclusion

Our study implicates serum LDH as a reliable and independent laboratory biomarker to predict the clinical outcome of curative‐intent surgery for CRLM. Composite of LDH and Fong score is a potential stratification tool for CRLM resection. Prospective, international studies are needed to validate these results across diverse populations.

Long Term Survival With Regorafenib: REALITY (Real Life in Italy) Trial - A GISCAD Study

BACKGROUND

Regorafenib is a key agent in metastatic colorectal cancer (mCRC), but no validated factors predicting longer survival are available.

PATIENTS AND METHODS

REALITY was a retrospective multicenter trial in regorafenib-treated mCRC patients with overall survival (OS) ≥ 6 months. We aimed to assess the association between clinical parameters and outcome to define a panel identifying long term survivors among regorafenib candidates. Primary and secondary endpoints were OS and progression free survival (PFS), respectively. Statistical analysis was performed with MedCalc (survival distribution: Kaplan-Meier; survival comparison: log-rank test; independent role of significant variables at univariate analysis: logistic regression).

RESULTS

Hundred regorafenib-treated mCRC patients with OS ≥ 6 months were enrolled. Median OS was 11.5 m (95%CI:9.60-12.96); median PFS was 4.2 months (95% CI:3.43-43.03). The absence of liver progression and of dose and/or schedule changes during the first 4 cycles (mainly for good tolerability) were independently correlated at multivariate analysis with OS (Exp(b)1.8869, P= .0277and Exp(b)2.2000, P = .0313) and PFS (Exp(b)2.1583, P = .0065 and Exp(b)2.3036, P= .0169). Patients with neither of these variables had a significantly improved OS (n = 14, 20.8 months; 95% CI:12.967-55.267) versus others (n = 86, 10 months; 95% CI:8.367-12.167; HR = 0.4902, P = .0045) and PFS (11.3 months, 95%CI:4.267-35.8 vs. 3.9 months, 95% CI:3.167-43.033; HR = 0.4648, P = .0086).

CONCLUSION

These 2 factors might allow clinicians to better identify patients more likely to benefit from regorafenib. Toxicity management remains crucial.

Lactate dehydrogenases amplify reactive oxygen species in cancer cells in response to oxidative stimuli

Previous studies demonstrated that superoxide could initiate and amplify LDH-catalyzed hydrogen peroxide production in aqueous phase, but its physiological relevance is unknown. Here we showed that LDHA and LDHB both exhibited hydrogen peroxide-producing activity, which was significantly enhanced by the superoxide generated from the isolated mitochondria from HeLa cells and patients’ cholangiocarcinoma specimen. After LDHA or LDHB were knocked out, hydrogen peroxide produced by Hela or 4T1 cancer cells were significantly reduced. Re-expression of LDHA in LDHA-knockout HeLa cells partially restored hydrogen peroxide production. In HeLa and 4T1 cells, LDHA or LDHB knockout or LDH inhibitor FX11 significantly decreased ROS induction by modulators of the mitochondrial electron transfer chain (antimycin, oligomycin, rotenone), hypoxia, and pharmacological ROS inducers piperlogumine (PL) and phenethyl isothiocyanate (PEITC). Moreover, the tumors formed by LDHA or LDHB knockout HeLa or 4T1 cells exhibited a significantly less oxidative state than those formed by control cells. Collectively, we provide a mechanistic understanding of a link between LDH and cellular hydrogen peroxide production or oxidative stress in cancer cells in vitro and in vivo.

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

Metabolic Reprogramming of Colorectal Cancer Cells and the Microenvironment: Implication for Therapy

Colorectal carcinoma (CRC) is one of the most frequently diagnosed carcinomas and one of the leading causes of cancer-related death worldwide. Metabolic reprogramming, a hallmark of cancer, is closely related to the initiation and progression of carcinomas, including CRC. Accumulating evidence shows that activation of oncogenic pathways and loss of tumor suppressor genes regulate the metabolic reprogramming that is mainly involved in glycolysis, glutaminolysis, one-carbon metabolism and lipid metabolism. The abnormal metabolic program provides tumor cells with abundant energy, nutrients and redox requirements to support their malignant growth and metastasis, which is accompanied by impaired metabolic flexibility in the tumor microenvironment (TME) and dysbiosis of the gut microbiota. The metabolic crosstalk between the tumor cells, the components of the TME and the intestinal microbiota further facilitates CRC cell proliferation, invasion and metastasis and leads to therapy resistance. Hence, to target the dysregulated tumor metabolism, the TME and the gut microbiota, novel preventive and therapeutic applications are required. In this review, the dysregulation of metabolic programs, molecular pathways, the TME and the intestinal microbiota in CRC is addressed. Possible therapeutic strategies, including metabolic inhibition and immune therapy in CRC, as well as modulation of the aberrant intestinal microbiota, are discussed.

The Biochemical and Clinical Perspectives of Lactate Dehydrogenase: An Enzyme of Active Metabolism

BACKGROUND

Lactate dehydrogenase (LDH) is a group of oxidoreductase isoenzymes catalyzing the reversible reaction between pyruvate and lactate. The five isoforms of this enzyme, formed from two subunits, vary in isoelectric points and these isoforms have different substrate affinity, inhibition constants and electrophoretic mobility. These diverse biochemical properties play a key role in its cellular, tissue and organ specificity. Though LDH is predominantly present in the cytoplasm, it has a multi-organellar location as well.

OBJECTIVE

The primary objective of this review article is to provide an update in parallel, the previous and recent biochemical views and its clinical significance in different diseases.

METHODS

With the help of certain inhibitors, its active site three-dimensional view, reactions mechanisms and metabolic pathways have been sorted out to a greater extent. Overexpression of LDH in different cancers plays a principal role in anaerobic cellular metabolism, hence several inhibitors have been designed to employ as novel anticancer agents.

DISCUSSION

LDH performs a very important role in overall body metabolism and some signals can induce isoenzyme switching under certain circumstances, ensuring that the tissues consistently maintain adequate ATP supply. This enzyme also experiences some posttranslational modifications, to have diversified metabolic roles. Different toxicological and pathological complications damage various organs, which ultimately result in leakage of this enzyme in serum. Hence, unusual LDH isoform level in serum serves as a significant biomarker of different diseases.

CONCLUSION

LDH is an important diagnostic biomarker for some common diseases like cancer, thyroid disorders, tuberculosis, etc. In general, LDH plays a key role in the clinical diagnosis of various common and rare diseases, as this enzyme has a prominent role in active metabolism.

Worenine reverses the Warburg effect and inhibits colon cancer cell growth by negatively regulating HIF-1α

Background

Some natural compounds inhibit cancer cell growth in various cancer cell lines with fewer side effects than traditional chemotherapy. Here, we explore the pharmacological effects and mechanisms of worenine (isolated from Coptis chinensis) against colorectal cancer.

Methods

The effects of worenine on colorectal cancer cell proliferation, colony formation and cell cycle distribution were measured. Glycolysis was investigated by examining glucose uptake and consumption, lactate production, and the activities and expressions of glycolysis enzymes (PFK-L, HK2 and PKM2). HIF-1α was knocked down and stimulated in vitro to investigate the underlying mechanisms.

Results

Worenine somewhat altered the glucose metabolism and glycolysis (Warburg effect) of cancer cells. Its anti-cancer effects and capability to reverse the Warburg effect were similar to those of HIF-1α siRNA and weakened by deferoxamine (an HIF-1α agonist).

Conclusion

It is suggested that worenine targets HIF-1α to inhibit colorectal cancer cell growth, proliferation, cell cycle progression and the Warburg effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-021-00263-y.

Lactate Metabolism and Signaling in Tuberculosis and Cancer: A Comparative Review

Infection with Mycobacterium tuberculosis (Mtb) leading to tuberculosis (TB) disease continues to be a major global health challenge. Critical barriers, including but not limited to the development of multi-drug resistance, lack of diagnostic assays that detect patients with latent TB, an effective vaccine that prevents Mtb infection, and infectious and non-infectious comorbidities that complicate active TB, continue to hinder progress toward a TB cure. To complement the ongoing development of new antimicrobial drugs, investigators in the field are exploring the value of host-directed therapies (HDTs). This therapeutic strategy targets the host, rather than Mtb, and is intended to augment host responses to infection such that the host is better equipped to prevent or clear infection and resolve chronic inflammation. Metabolic pathways of immune cells have been identified as promising HDT targets as more metabolites and metabolic pathways have shown to play a role in TB pathogenesis and disease progression. Specifically, this review highlights the potential role of lactate as both an immunomodulatory metabolite and a potentially important signaling molecule during the host response to Mtb infection. While long thought to be an inert end product of primarily glucose metabolism, the cancer research field has discovered the importance of lactate in carcinogenesis and resistance to chemotherapeutic drug treatment. Herein, we discuss similarities between the TB granuloma and tumor microenvironments in the context of lactate metabolism and identify key metabolic and signaling pathways that have been shown to play a role in tumor progression but have yet to be explored within the context of TB. Ultimately, lactate metabolism and signaling could be viable HDT targets for TB; however, critical additional research is needed to better understand the role of lactate at the host-pathogen interface during Mtb infection before adopting this HDT strategy.

Glycolytic pathway candidate markers in the prognosis of oral squamous cell carcinoma: a systematic review with meta-analysis

Molecular changes that affect mitochondrial glycolysis have been associated with the maintenance of tumor cells. Some metabolic factors have already been described as predictors of disease severity and outcomes. This systematic review was conducted to answer the question: Is the glycolytic pathway correlated with the prognosis of oral squamous cell carcinoma (OSCC)? A search strategy was developed to retrieve studies in English from PubMed, Scopus, and ISI Web of Science using keywords related to squamous cell carcinoma, survival, and glycolytic pathway, with no restriction of publication date. The search retrieved 1273 publications. After the titles and abstracts were analyzed, 27 studies met inclusion criteria. Studies were divided into groups according to two subtopics, glycolytic pathways and diagnosis, which describe the glycolytic profile of OSCC tumors. Several components of tumor energy metabolism found in this review are important predictors of survival of patients with OSCC.

Glucose Metabolism in Cancer: The Warburg Effect and Beyond

Otto Warburg observed a peculiar phenomenon in 1924, unknowingly laying the foundation for the field of cancer metabolism. While his contemporaries hypothesized that tumor cells derived the energy required for uncontrolled replication from proteolysis and lipolysis, Warburg instead found them to rapidly consume glucose, converting it to lactate even in the presence of oxygen. The significance of this finding, later termed the Warburg effect, went unnoticed by the broader scientific community at that time. The field of cancer metabolism lay dormant for almost a century awaiting advances in molecular biology and genetics, which would later open the doors to new cancer therapies [2, 3].

Endothelium-Derived Extracellular Vesicles Associate with Poor Prognosis in Metastatic Colorectal Cancer

Elevated, tumor-derived extracellular vesicle (tdEV) and circulating tumor cell (CTC) loads in metastatic cancer are associated with poor clinical outcome. Herein, we investigate whether endothelium-derived extracellular vesicles (edEVs) can be detected in the blood of metastatic colorectal cancer (mCRC) patients, and whether those vesicles associate with prognosis. The open-source ACCEPT (Automated CTC Classification, Enumeration, and Phenotyping) software was used to enumerate edEVs, tdEVs, and other objects from digitally stored CellSearch images acquired after CTC and circulating endothelial cell (CEC) enrichment from the blood of 395 mCRC patients before the initiation of a new therapy. Patients had participated in the prospective phase III CAIRO2 study. The presence of edEVs was found 5- to 10-fold higher than CECs. The hazard ratio (HR) (95% CI) of progression-free survival (PFS) for increased CTCs (≥3 in 7.5 mL), tdEVs (≥40 in 7.5 mL), and edEVs (≥287 in 4.0 mL.) was 1.4 (1.1-1.9), 2.0 (1.5-2.6), and 1.7 (1.2-2.5), respectively. The HR of Overall Survival (OS) for increased CTCs, tdEVs and edEVs was 2.2 (1.7-3.0), 2.7 (2.0-3.5), and 2.1 (1.5-2.8), respectively. There was no cut-off value for CECs, leading to a dichotomization of patients with a significant HR. Only tdEVs remained a significant predictor of OS in the final multivariable model.

Factors Associated With Local Tumor Control and Complications After Thermal Ablation of Colorectal Cancer Liver Metastases: A 15-year Retrospective Cohort Study

INTRODUCTION

The purpose of this study was to identify risk factors associated with local tumor progression-free survival (LTPFS) and complications after colorectal liver metastases (CLM) thermal ablation (TA).

PATIENTS AND METHODS

This retrospective analysis included 286 patients with 415 CLM undergoing TA (radiofrequency and microwave ablation) in 378 procedures from January 2003 to July 2017. Prior hepatic artery infusion (HAI), bevacizumab, pre-existing biliary dilatation, ablation modality, minimal ablation margin (MM), prior hepatectomy, CLM number, and size were analyzed as factors influencing complications and LTPFS. Statistical analysis included the Kaplan-Meier method, Cox proportional hazards model, competing risk analysis, univariate/multivariate logistic/exact logistic regressions, and the Fisher exact test. Complications were reported according to modified Society of Interventional Radiology guidelines.

RESULTS

The median follow-up was 31 months. There was no LTP for MM > 10 mm. Smaller tumor size, increased MM, and prior hepatectomy correlated with longer LTPFS. The major complications occurred following 28 (7%) of 378 procedures. There were no biliary complications in HAI-naive patients, versus 11% in HAI patients (P < .001), of which 7% were major. Biliary complications predictors in HAI patients included biliary dilatation, bevacizumab, and MM > 10 mm. In HAI patients, ablation with 6 to 10 mm and > 10 mm MM resulted in major biliary complication rates of 4% and 21% (P = .0011), with corresponding LTP rates of 24% and 0% (P = .0033). In HAI-naive patients, the LTP rates for 6 to 10 mm and > 10 mm MM were 27% and 0%, respectively.

CONCLUSIONS

No LTP was seen for MM > 10 mm. Biliary complications occurred only in HAI patients, especially in those with biliary dilatation, bevacizumab, and MM > 10 mm. In HAI patients, MM of 6 to 10 mm resulted in 76% local tumor control and 4% major biliary complications incidence.

Oncometabolites lactate and succinate drive pro-angiogenic macrophage response in tumors

Macrophages are innate phagocytic leukocytes that are highly present in solid tumors, where they are referred to as tumor-associated macrophages (TAMs). In solid tumors, the microenvironment is often immunosuppressive and hypoxic regions are prevalent. These hypoxic conditions impose tumor cells to reprogram their metabolism, shifting from oxidative phosphorylation to anaerobic glycolysis. This so-called glycolytic switch enables hypoxic tumor cells to survive, proliferate, and eventually to outcompete untransformed cells. The hypoxia-induced change in tumor cell metabolism leads to the production of oncometabolites, among which are the glycolytic end-metabolite lactate and the tricarboxylic acid cycle intermediate succinate. TAMs can react to these oncometabolites, resulting in an altered maturation and the adoption of pro-angiogenic features. These angiogenesis-promoting TAMs have been reported to cooperate with tumor cells in the formation of new vessels, and even have been considered an important cause of resistance against anti-angiogenic therapies. For a long time, the mechanisms by which lactate and succinate activated pro-angiogenic TAMs were not understood. Researchers now start to unravel and understand some of the underlying mechanisms. Here, the importance of microenvironmental cues in inducing different macrophage activation states is discussed, as well as the role of hypoxia in the recruitment and activation of pro-angiogenic macrophages. In addition, the latest findings on the oncometabolites lactate and succinate in the activation of angiogenesis supporting macrophages are reviewed. Finally, various oncometabolite-targeting therapeutic strategies are proposed that could improve the response to anti-angiogenic therapies. SIGNIFICANCE STATEMENT: Tumor-associated macrophages (TAMs) are known promotors of tumor neovascularization, and significantly contribute to the emergence of resistance to anti-angiogenic therapies. Recent evidence suggests that the angiogenesis promoting phenotype of TAMs can be activated by hypoxic tumor cell-derived oncometabolites, including lactate and succinate. Here, the latest findings into the lactate- and succinate-mediated mechanistic activation of pro-angiogenic TAMs are reviewed, and therapeutic strategies that interfere with this mechanism and may delay or even prevent acquired resistance to anti-angiogenic agents are discussed.

The SENECA study: Prognostic role of serum biomarkers in older patients with metastatic colorectal cancer

BACKGROUND

Aging induces meaningful changes in the immune system and inflammation response with increase in monocyte-lymphocyte ratio (MLR) and serum lactate dehydrogenase (LDH) levels. Aim of this study was to explore the prognostic role of MLR and LDH levels in older patients (pts) with metastatic colorectal cancer (mCRC).

METHODS

We conducted a retrospective analysis of a consecutive cohort of 168 older (>70 years) patients with mCRC. The prognostic impact of MLR and LDH levels on overall survival (OS) was investigated through uni-and multivariate Cox regression analyses. Moreover, we categorized patients into three groups according to MLR and LDH levels (group 1: MLR-low and LDH-low; group 2: MLR-high or LDH-high; group 3: MLR-high and LDH-high).

RESULTS

By univariate analysis, high LDH level (HR 1.74, 95% CI 1.05-2.90) and high MLR level (HR 2.19, 95% CI 1.48-3.44) were significantly associated with a worse OS. Conversely, primary tumor resection and left-sidedness were significantly associated with a longer OS. By multivariate analysis, high LDH level (HR 2.00, 95% CI 1.13-3.55) and high MLR level (HR 2.99, 95% CI 1.68-5.33) were independent prognostic factors of worse prognosis. Compared to group 1, a shorter survival was reported for patients included in group 2 (HR 1.97, 95% CI 1.21-3.23 in univariate; HR 2.54, 95% CI 1.43-4.51 in multivariate) or in group 3 (HR 2.42, 95% CI 24-4.74, p = .010 in univariate; HR 5.59, 95% CI 2.15-14.54 in multivariate) CONCLUSIONS: High baseline levels of LDH, MLR or both are independent unfavorable prognostic factors in older patients treated with first-line chemotherapy for mCRC.

The fuel and engine: The roles of reprogrammed metabolism in metastasis of primary liver cancer

Metastasis and metabolism reprogramming are two major hallmarks of cancer. In the initiation and progression of cancer, tumor cells are known to undergo fundamental metabolic changes to sustain their development and progression. In recent years, much more attentions have been drawn to their important roles in facilitating cancer metastasis through regulating the biological properties. In this review, we summarized the recent progresses in the studies of metabolism reprogramming of cancer metastasis, particularly of primary liver cancer, and highlight their potential applications.

MTA1 coregulator regulates LDHA expression and function in breast cancer

Metastasis Associated Protein1 (MTA1) is a chromatin modifier and its expression is significantly associated with prognosis of many cancers. However, its role in glucose metabolism remains unexplored. Here, we report that MTA1 has a significant role in glucose metabolism where MTA1 regulates the LDHA expression and activity and subsequently its function in breast cancer motility. The results showed that MTA1 expression is positively correlated with the LDHA expression levels in breast cancer patients. Further, it was found that MTA1 is necessary for the optimal expression of LDHA. The underlying molecular mechanism involves the interaction of MTA1 with c-Myc and recruitment of MTA1-c-Myc complex on to the LDHA promoter to regulate its transcription. Consequently, the LDHA knock down using LDHA specific siRNA in MCF7 cells stably expressing MTA1 reduced the migration of MCF7 cells. Altogether these findings revealed the regulatory role for MTA1 in LDHA expression and its resulting biological function.

Novel therapies hijack the blood-brain barrier to eradicate glioblastoma cancer stem cells

Glioblastoma (GBM) is amongst the most aggressive brain tumors with a dismal prognosis. Despite significant advances in the current multimodality therapy including surgery, postoperative radiotherapy (RT) and temozolomide (TMZ)-based concomitant and adjuvant chemotherapy (CT), tumor recurrence is nearly universal with poor patient outcomes. These limitations are in part due to poor drug penetration through the blood-brain barrier (BBB) and resistance to CT and RT by a small population of cancer cells recognized as tumor-initiating cells or cancer stem cells (CSCs). Though CT and RT kill the bulk of the tumor cells, they fail to affect CSCs, resulting in their enrichment and their development into more refractory tumors. Therefore, identifying the mechanisms of resistance and developing therapies that specifically target CSCs can improve response, prevent the development of refractory tumors and increase overall survival of GBM patients. Small molecule inhibitors that can breach the BBB and selectively target CSCs are emerging. In this review, we have summarized the recent advancements in understanding the GBM CSC-specific signaling pathways, the CSC-tumor microenvironment niche that contributes to CT and RT resistance and the use of novel combination therapies of small molecule inhibitors that may be used in conjunction with TMZ-based chemoradiation for effective management of GBM.

The significance of CO2 combining power in predicting prognosis of patients with stage II and III colorectal cancer

Aim: This study was to evaluate whether CO₂CP level in venous blood could predict prognosis of patients with colorectal cancer (CRC). Materials & methods: A retrospective cohort of 238 patients with CRC who received surgical resection and 176 CRC Stage IV patients were included. A total of 114 healthy people were recruited as control. CO₂CP levels were obtained from medical records. Survival analysis was performed to evaluate CO₂CP predictive potential. The patients were divided into CO₂CP high or low group based on CO₂CP optimal cut-off values. Conclusion: The decreased CO₂CP in CRC patients was associated with advanced clinical stage, and suggested that decreased CO₂CP may predict the worse outcomes of disease-free survival in II/III stage CRC patients.

A novel scoring system predicting survival benefits of palliative primary tumor resection for patients with unresectable metastatic colorectal cancer: A retrospective cohort study protocol

The role of palliative primary tumor resection (PPTR) in improving survival in patients with synchronous unresectable metastatic colorectal cancer (mCRC) is controversial. In this study, we aimed to evaluate whether our novel scoring system could predict survival benefits of PPTR in mCRC patients.In this retrospective cohort study consecutive patients with synchronous mCRC and unresectable metastases admitted to Sir Run Run Shaw Hospital between January 2005 and December 2013 were identified. A scoring system was established by the serum levels of carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), neutrophil/lymphocyte ratio (NLR), and lactate dehydrogenase (LDH). Patients with scores of 0, 1-2, or 3-4 were considered as being in the low, intermediate, and high score group, respectively. Primary outcome was overall survival (OS).A total of 138 eligible patients were included in the analysis, of whom 103 patients had undergone PPTR and 35 had not. The median OS of the PPTR group was better than that of the Non-PPTR group, with 26.2 and 18.9 months, respectively (P < .01). However, the subgroup of PPTR with a high score (3-4) showed no OS benefit (13.3 months) compared with that of the Non-PPTR group (18.9 months, P = .11). The subgroup of PPTR with a low score (52.1 months) or intermediate score (26.2 months) had better OS than that of the Non-PPTR group (P < .001, P = .017, respectively).A novel scoring system composed of CEA, CA19-9, NLR, and LDH values is a feasible method to evaluate whether mCRC patients would benefit from PPTR. It might guide clinical decision making in selecting patients with unresectable mCRC for primary tumor resection.

Microbial carcinogenesis: Lactic acid bacteria in gastric cancer

While Helicobacter pylori is a fundamental risk factor, gastric cancer (GC) aetiology involves combined effects of microbial (both H. pylori and non-H. pylori), host and environmental factors. Significant differences exist between the gastric microbiome of those with gastritis, intestinal metaplasia and GC, suggesting that dysbiosis in the stomach is dynamic and correlates with progression to GC. Most notably, a consistent increase in abundance of lactic acid bacteria (LAB) has been observed in GC patients including Streptococcus, Lactobacillus, Bifidobacterium and Lactococcus. This review summarises how LAB can influence GC by a number of mechanisms that include supply of exogenous lactate -a fuel source for cancer cells that promotes inflammation, angiogenesis, metastasis, epithelial-mesenchymal transition and immune evasion-, production of reactive oxygen species and N-nitroso compounds, as well as anti-H. pylori properties that enable colonization by other non-H. pylori carcinogenic pathobionts.