Inhibition of Mitochondrial Metabolism Leads to Selective Eradication of Cells Adapted to Acidic Microenvironment

α-Hederin inhibited pancreatic cancer cell malignant progression by inhibiting LDHA-mediated glycolysis

α-Hederin is a pentacyclic triterpenoid saponin extracted from Pulsatilla chinensis, which is known to suppress cancer cell proliferation. However, the role of this compound in pancreatic cancer cells remains unclear. The aim of this study was to reveal the docking molecular and the regulatory mechanism of α-hederin in pancreatic cancer. Here, we cultured Capan-1 and BxPC-3 cells and treated with different doses of α-hederin. Cell proliferation, migration, and apoptosis were detected using CCK8, EdU, Transwell, wound healing assay, and flow cytometer apoptosis assay. The in vivo experiment using subcutaneous tumor and caudal vein metastasis model to evaluate the inhibit effect of α-hederin Capan-1 cell tumor growth and metastasis. Proteomics were used to reveal the regulatory mechanism. The result shows that α-hederin treatment inhibits cell proliferation and invasion in concentration dependence way in both vivo and in vitro. The result shows that the IC50 for both Capan-1 and BxPC-3 were 32.5 Mµ and 15 Mµ, respectively. Flow cytometer apoptosis assay shows that α-hederin treatment promotion cell apoptosis in both Capan-1 and BxPC-3 cells. Proteomics and immunofluorescence detection confirmed that α-hederin treatment downregulated lactate dehydrogenase A (LDHA) expression and inhibited glycolysis. Molecular docking of α-hederin and LDHA proteins further confirmed that LDHA is a target of α-hederin. Taken together, this study confirms that α-hederin inhibits pancreatic cancer cell proliferation and invasion by inhibiting LDHA-mediated glycolysis. LDHA may be a direct target of α-hederin in pancreatic cancer.

Unveiling the hidden risks: albumin-corrected anion gap as a superior marker for cardiovascular mortality in type 2 diabetes: insights from a nationally prospective cohort study

Aims

Hypoalbuminemia can lead to underestimations of the true anion gap levels. There are few data on albumin-corrected serum anion gap (ACAG) status and mortality in the diabetes. The study aimed to examine the association between ACAG and all-cause, cardiovascular, and cancer mortality in type 2 diabetes (T2D) patients.

Methods

Herein, 8,161 diabetic adults were included in the National Health and Nutrition Examination Survey (NHANES) 1999-2018. National Mortality Index (NDI) data were used for determining mortality outcomes through 31 December 2019. Cox proportional hazards models were used to estimate the risk of all-cause, cardiovascular, and cancer mortality. We conducted a mediation analysis using the counterfactual framework method to estimate how ACAG may be indirectly associated with increased mortality risk through mediators.

Results

A total of 2,309 deaths were documented over 8,161 person-years of follow up, including 659 cardiovascular and 399 cancer deaths. In multivariate analyses, higher ACAG levels had a significant correlation with an increase in all-cause (HR, 1.58; 95% CI, 1.38-1.81; P=0.001), cardiovascular (HR, 1.34; 95% CI, 1.05-1.72; P=0.019), and cancer (HR, 1.41; 95% CI, 1.02-1.96; P=0.018) mortality rates than the controls. Results of the mediation analysis showed that altered levels of C-reactive protein and estimated glomerular filtration rate (eGFR) explained 7.867% and 7.669% of the relation between serum ACAG and all-cause mortality, respectively (all P<0.05). Total cholesterol and HbA1c mediated 15.402% and 14.303% of the associations with cardiovascular mortality, respectively (all P<0.05).

Conclusions

Higher ACAG levels were significantly associated with increased all-cause, cardiovascular, and cancer mortality. Researchers suggest that patients with T2D who control ACAG in a normal state may be at a lower risk of mortality.

The rheumatoid arthritis drug auranofin exerts potent anti-lymphoma effect by stimulating TXNRD-mediated ROS generation and inhibition of energy metabolism

Since the survival of lymphoma patients who experience disease progression or relapse remains very poor, new therapeutic approaches and effective drugs are urgently needed. Here we show that auranofin (AF), an anti-rheumatoid drug thought to inhibit thioredoxin reductases (TXNRDs) as its mechanism of action, exhibited potent activity against multiple cancer types, especially effective against B cell lymphoma. Surprisingly, a knockdown of TXNRD1 and TXNRD2 did not cause significant cytotoxicity, suggesting that abrogation of TXNRD enzyme per se was insufficient to cause cancer cell death. Further mechanistic study showed that the interaction of AF with TXNRD could convert this antioxidant enzyme to a ROS-generating molecule via disrupting its electron transport, leading to a leak of electrons that interact with molecular oxygen to form superoxide. AF also suppressed energy metabolism by inhibiting both mitochondria complex II and the glycolytic enzyme GAPDH, leading to a significant depletion of ATP and inhibition of cancer growth in vitro and in vivo. Importantly, we found that the AF-mediated ROS stress could induce PD-L1 expression, revealing an unwanted effect of AF in causing immune suppression. We further showed that a combination of AF with anti-PD-1 antibody could enhance the anticancer activity in a syngeneic immune-competent mouse B-cell lymphoma model. Our study suggests that AF could be a potential drug for lymphoma treatment, and its combination with immune checkpoint inhibitors would be a logical strategy to increase the therapeutic activity.

Warburg-associated acidification represses lactic fermentation independently of lactate, contribution from real-time NMR on cell-free systems

Lactate accumulation and acidification in tumours are a cancer hallmark associated with the Warburg effect. Lactic acidosis correlates with cancer malignancy, and the benefit it offers to tumours has been the subject of numerous hypotheses. Strikingly, lactic acidosis enhances cancer cell survival to environmental glucose depletion by repressing high-rate glycolysis and lactic fermentation, and promoting an oxidative metabolism involving reactivated respiration. We used real-time NMR to evaluate how cytosolic lactate accumulation up to 40 mM and acidification up to pH 6.5 individually impact glucose consumption, lactate production and pyruvate evolution in isolated cytosols. We used a reductive cell-free system (CFS) to specifically study cytosolic metabolism independently of other Warburg-regulatory mechanisms found in the cell. We assessed the impact of lactate and acidification on the Warburg metabolism of cancer cytosols, and whether this effect extended to different cytosolic phenotypes of lactic fermentation and cancer. We observed that moderate acidification, independently of lactate concentration, drastically reduces the glucose consumption rate and halts lactate production in different lactic fermentation phenotypes. In parallel, for Warburg-type CFS lactate supplementation induces pyruvate accumulation at control pH, and can maintain a higher cytosolic pyruvate pool at low pH. Altogether, we demonstrate that intracellular acidification accounts for the direct repression of lactic fermentation by the Warburg-associated lactic acidosis.

How Warburg-Associated Lactic Acidosis Rewires Cancer Cell Energy Metabolism to Resist Glucose Deprivation

Lactic acidosis, a hallmark of solid tumour microenvironment, originates from lactate hyperproduction and its co-secretion with protons by cancer cells displaying the Warburg effect. Long considered a side effect of cancer metabolism, lactic acidosis is now known to play a major role in tumour physiology, aggressiveness and treatment efficiency. Growing evidence shows that it promotes cancer cell resistance to glucose deprivation, a common feature of tumours. Here we review the current understanding of how extracellular lactate and acidosis, acting as a combination of enzymatic inhibitors, signal, and nutrient, switch cancer cell metabolism from the Warburg effect to an oxidative metabolic phenotype, which allows cancer cells to withstand glucose deprivation, and makes lactic acidosis a promising anticancer target. We also discuss how the evidence about lactic acidosis' effect could be integrated in the understanding of the whole-tumour metabolism and what perspectives it opens up for future research.

Lactate, histone lactylation and cancer hallmarks

Histone lactylation, an indicator of lactate level and glycolysis, has intrinsic connections with cell metabolism that represents a novel epigenetic code affecting the fate of cells including carcinogenesis. Through delineating the relationship between histone lactylation and cancer hallmarks, we propose histone lactylation as a novel epigenetic code priming cells toward the malignant state, and advocate the importance of identifying novel therapeutic strategies or dual-targeting modalities against lactylation toward effective cancer control. This review underpins important yet less-studied area in histone lactylation, and sheds insights on its clinical impact as well as possible therapeutic tools targeting lactylation.

Lactic Acidosis in Patients with Solid Cancer

Significance: Cancer-associated tissue-specific lactic acidosis stimulates and mediates tumor invasion and metastasis and is druggable. Rarely, malignancy causes systemic lactic acidosis, the role of which is poorly understood. Recent Advances: The understanding of the role of lactate has shifted dramatically since its discovery. Long recognized as only a waste product, lactate has become known as an alternative metabolism substrate and a secreted nutrient that is exchanged between the tumor and the microenvironment. Tissue-specific lactic acidosis is targeted to improve the host body's anticancer defense and serves as a tool that allows the targeting of anticancer compounds. Systemic lactic acidosis is associated with poor survival. In patients with solid cancer, systemic lactic acidosis is associated with an extremely poor prognosis, as revealed by the analysis of 57 published cases in this study. Although it is considered a pathology worth treating, targeting systemic lactic acidosis in patients with solid cancer is usually inefficient. Critical Issues: Research gaps include simple questions, such as the unknown nuclear pH of the cancer cells and its effects on chemotherapy outcomes, pH sensitivity of glycosylation in cancer cells, in vivo mechanisms of response to acidosis in the absence of lactate, and overinterpretation of in vitro results that were obtained by using cells that were not preadapted to acidic environments. Future Directions: Numerous metabolism-targeting anticancer compounds induce lactatemia, lactic acidosis, or other types of acidosis. Their potential to induce acidic environments is largely overlooked, although the acidosis might contribute to a substantial portion of the observed clinical effects. Antioxid. Redox Signal. 37, 1130-1152.

Avenue to X-ray-induced photodynamic therapy of prostatic carcinoma with octahedral molybdenum cluster nanoparticles

X-Ray-induced photodynamic therapy represents a suitable modality for the treatment of various malignancies. It is based on the production of reactive oxygen species by radiosensitizing nanoparticles activated by X-rays. Hence, it allows overcoming the depth-penetration limitations of conventional photodynamic therapy and, at the same time, reducing the dose needed to eradicate cancer in the frame of radiotherapy treatment. The direct production of singlet oxygen by octahedral molybdenum cluster complexes upon X-ray irradiation is a promising avenue in order to simplify the architecture of radiosensitizing systems. One such complex was utilized to prepare water-stable nanoparticles using the solvent displacement method. The nanoparticles displayed intense red luminescence in aqueous media, efficiently quenched by oxygen to produce singlet oxygen, resulting in a substantial photodynamic effect under blue light irradiation. A robust radiosensitizing effect of the nanoparticles was demonstrated in vitro against TRAMP-C2 murine prostatic carcinoma cells at typical therapeutic X-ray doses. Injection of a suspension of the nanoparticles to a mouse model revealed the absence of acute toxicity as evidenced by the invariance of key physiological parameters. This study paves the way for the application of octahedral molybdenum cluster-based radiosensitizers in X-ray-induced photodynamic therapy and its translation to in vivo experiments.