Sodium butyrate opens mitochondrial permeability transition pore (MPTP) to induce a proton leak in induction of cell apoptosis

Short-chain fatty acids reverses gut microbiota dysbiosis-promoted progression of glioblastoma by up-regulating M1 polarization in the tumor microenvironment

Glioblastoma (GBM), known as the most malignant and common primary brain tumor of the central nervous system, has finite therapeutic options and a poor prognosis. Studies have shown that host intestinal microorganisms play a role in the immune regulation of parenteral tumors in a number of different ways, either directly or indirectly. However, the potential impact of gut microbiota on tumor microenvironment, particularly glioma immunological milieu, has not been clarified exactly. In this study, by using an orthotopic GBM model, we found gut microbiota dysbiosis caused by antibiotic cocktail treatment boosted the tumor process in vivo. An obvious change that followed gut microbiota dysbiosis was the enhanced percentage of M2-like macrophages in the TME, in parallel with a decrease in the levels of gut microbial metabolite, short-chain fatty acids (SCFAs) in the blood and tumor tissues. Oral supplementation with SCFAs can increase the proportion of M1-like macrophages in the TME, which improves the outcomes of glioma. In terms of mechanism, SCFAs-activated glycolysis in the tumor-associated macrophages may be responsible for the elevated M1 polarization in the TME. This study will enable us to better comprehend the "gut-brain" axis and be meaningful for the development of TAM-targeting immunotherapeutic strategies for GBM patients.

Microbial metabolite sodium butyrate enhances the anti-tumor efficacy of 5-fluorouracil against colorectal cancer by modulating PINK1/Parkin signaling and intestinal flora

Colorectal cancer (CRC) is a prevalent global health issue, with 5-fluorouracil (5-FU) being a commonly used chemotherapeutic agent for its treatment. However, the efficacy of 5-FU is often hindered by drug tolerance. Sodium butyrate (NaB), a derivative of intestinal flora, has demonstrated anti-cancer properties both in vitro and in vivo through pro-apoptotic effects and has shown promise in improving outcomes when used in conjunction with traditional chemotherapy agents. This study seeks to evaluate the impact and potential mechanisms of NaB in combination with 5-FU on CRC. We employed a comprehensive set of assays, including CCK-8, EdU staining, Hoechst 33258 staining, flow cytometry, ROS assay, MMP assay, immunofluorescence, and mitophagy assay, to detect the effect of NaB on the biological function of CRC cells in vitro. Western blotting and immunohistochemistry were used to verify the above experimental results. The xenograft tumor model was established to evaluate the in vivo anti-CRC activity of NaB. Subsequently, 16S rRNA gene sequencing was used to analyze the intestinal flora. The findings of our study demonstrate that sodium butyrate (NaB) exerts inhibitory effects on tumor cell proliferation and promotes tumor cell apoptosis in vitro, while also impeding tumor progression in vivo through the enhancement of the mitophagy pathway. Furthermore, the combined treatment of NaB and 5-fluorouracil (5-FU) yielded superior therapeutic outcomes compared to monotherapy with either agent. Moreover, this combination therapy resulted in the specific enrichment of Bacteroides, LigiLactobacillus, butyric acid-producing bacteria, and acetic acid-producing bacteria in the intestinal microbiota. The improvement in the intestinal microbiota contributed to enhanced therapeutic outcomes and reduced the adverse effects of 5-FU. Taken together, these findings indicate that NaB, a histone acetylation inhibitor synthesized through intestinal flora fermentation, has the potential to significantly enhance the therapeutic efficacy of 5-FU in CRC treatment and improve the prognosis of CRC patients.

Mitochondrial carrier homolog 2 increases malignant phenotype of human gastric epithelial cells and promotes proliferation, invasion, and migration of gastric cancer cells

BACKGROUND

The precise role of mitochondrial carrier homolog 2 (MTCH2) in promoting malignancy in gastric mucosal cells and its involvement in gastric cancer cell metastasis have not been fully elucidated.

AIM

To determine the role of MTCH2 in gastric cancer.

METHODS

We collected 65 samples of poorly differentiated gastric cancer tissue and adjacent tissues, constructed MTCH2-overexpressing and MTCH2-knockdown cell models, and evaluated the proliferation, migration, and invasion of human gastric epithelial cells (GES-1) and human gastric cancer cells (AGS) cells. The mitochondrial membrane potential (MMP), mitochondrial permeability transformation pore (mPTP) and ATP fluorescence probe were used to detect mitochondrial function. Mitochondrial function and ATP synthase protein levels were detected via Western blotting.

RESULTS

The expression of MTCH2 and ATP2A2 in gastric cancer tissues was significantly greater than that in adjacent tissues. Overexpression of MTCH2 promoted colony formation, invasion, migration, MMP expression and ATP production in GES-1 and AGS cells while upregulating ATP2A2 expression and inhibiting cell apoptosis; knockdown of MTCH2 had the opposite effect, promoting overactivation of the mPTP and promoting apoptosis.

CONCLUSION

MTCH2 can increase the malignant phenotype of GES-1 cells and promote the proliferation, invasion, and migration of gastric cancer cells by regulating mitochondrial function, providing a basis for targeted therapy for gastric cancer cells.

Metabolic basis of solute carrier transporters in treatment of type 2 diabetes mellitus

Solute carriers (SLCs) constitute the largest superfamily of membrane transporter proteins. These transporters, present in various SLC families, play a vital role in energy metabolism by facilitating the transport of diverse substances, including glucose, fatty acids, amino acids, nucleotides, and ions. They actively participate in the regulation of glucose metabolism at various steps, such as glucose uptake (e.g., SLC2A4/GLUT4), glucose reabsorption (e.g., SLC5A2/SGLT2), thermogenesis (e.g., SLC25A7/UCP-1), and ATP production (e.g., SLC25A4/ANT1 and SLC25A5/ANT2). The activities of these transporters contribute to the pathogenesis of type 2 diabetes mellitus (T2DM). Notably, SLC5A2 has emerged as a valid drug target for T2DM due to its role in renal glucose reabsorption, leading to groundbreaking advancements in diabetes drug discovery. Alongside SLC5A2, multiple families of SLC transporters involved in the regulation of glucose homeostasis hold potential applications for T2DM therapy. SLCs also impact drug metabolism of diabetic medicines through gene polymorphisms, such as rosiglitazone (SLCO1B1/OATP1B1) and metformin (SLC22A1-3/OCT1-3 and SLC47A1, 2/MATE1, 2). By consolidating insights into the biological activities and clinical relevance of SLC transporters in T2DM, this review offers a comprehensive update on their roles in controlling glucose metabolism as potential drug targets.

Energy Metabolic Disorder of Astrocytes May Be an Inducer of Migraine Attack

Migraine is a chronic headache disease, which ranks second in years lost due to disability. However, the mechanism of migraines is still not clear. In migraine patients, fasting can trigger headache attacks. We explored the probable mechanism of why fasting can induce headaches. Nitroglycerin (NTG) was used to induce acute migraine attacks in mice. Primary astrocytes were used to study the pathophysiological mechanism and a Seahorse analyzer was used to detect mitochondrial function. NTG induced more serious headaches in the fasting group. Both the head-scratching times and climbing-cage times in the fasting group were higher than those in normal-diet group. More ROS and inflammatory factors, such as IL-6 and IL-1β, were induced in low-glucose conditions. Seahorse showed that the basal oxygen consumption rate (OCR) and OCR for ATP production were lower in mice who had received NTG with low glucose levels than in other groups. The activity of AMPK was inhibited in this group, which may explain the Seahorse results. We concluded that in the low-glucose state, astrocytes produce more inflammatory factors, ROS, which may be a result of mitochondrial metabolism dysfunction. Improving mitochondrial function and supplying enough substrates may be an option for relieving migraine attacks.

NF-κB regulates brown adipocyte function through suppression of ANT2

The transcription factor nuclear factor of kappa-light-chain-enhancer of activated B cells (NF-κB) is expressed in brown adipocytes, but its role remains largely unknown in the cells. This issue was addressed in current study by examining NF-κB in brown adipocytes in vitro and in vivo. NF-κB activity was increased by differentiation of brown adipocytes through elevation of p65 (RelA) expression. The transcriptional activity of NF-κB was induced by the cold stimulation with an elevation in S276 phosphorylation of p65 protein. Inactivation of NF-κB in brown adipocytes made the knockout mice [uncoupling protein 1 (Ucp1)–CreER–p65^f/f, U-p65-KO] intolerant to the cold environment. The brown adipocytes exhibited an increase in apoptosis, a decrease in cristae density and uncoupling activity in the interscapular brown adipose tissue (iBAT) of p65-KO mice. The alterations became severer after cold exposure of the KO mice. The brown adipocytes of mice with NF-κB activation (p65 overexpression, p65-OE) exhibited a set of opposite alterations with a reduction in apoptosis, an increase in cristae density and uncoupling activity. In mechanism, NF-κB inhibited expression of the adenine nucleotide translocase 2 (ANT2) in the control of apoptosis. Data suggest that NF-κB activity is increased in brown adipocytes by differentiation and cold stimulation to protect the cells from apoptosis through down-regulation of ANT2 expression.

Combining Sodium Butyrate With Cisplatin Increases the Apoptosis of Gastric Cancer In Vivo and In Vitro via the Mitochondrial Apoptosis Pathway

Introduction: The gastrointestinal malignancy, gastric cancer (GC), has a high incidence worldwide. Cisplatin is a traditional chemotherapeutic drug that is generally applied to treat cancer; however, drug tolerance affects its efficacy. Sodium butyrate is an intestinal flora derivative that has general anti-cancer effects in vitro and in vivo via pro-apoptosis effects and can improve prognosis in combination with traditional chemotherapy drugs. The present study aimed to assess the effect of sodium butyrate combined with cisplatin on GC. Methods: A Cell Counting Kit-8 assay was used to assess the viability of GC cells in vitro. Hoechst 33,258 staining and Annexin V-Phycoerythrin/7-Aminoactinomycin D were used to qualitatively and quantitatively detect apoptosis in GC cells. Intracellular reactive oxygen species (ROS) measurement and a mitochondrial membrane potential (MMP) assay kit were used to qualitatively and quantitatively reflect the function of mitochondria in GC cells. Western blotting was used to verify the above experimental results. A nude mouse xenograft tumor model was used to evaluate the anti-tumor efficacity of sodium and cisplatin butyrate in vivo. Results: Cisplatin combined with sodium butyrate increased the apoptosis of GC cells. In the nude mouse xenograft tumor model, sodium butyrate in combination with cisplatin markedly inhibited the growth of the tumor more effectively than either single agent. The combination of sodium butyrate and cisplatin increased the intracellular ROS, decreased the MMP, and suppressed the invasion and migration abilities of GC cells. Western blotting verified that the combination of sodium butyrate and cisplatin remarkably enhanced the levels of mitochondrial apoptosis-related pathway proteins. Conclusion: Sodium butyrate, a histone acetylation inhibitor produced by intestinal flora fermentation, combined with cisplatin enhanced the apoptosis of GC cells through the mitochondrial apoptosis-related pathway, which might be considered as a therapeutic option for GC.

High doses of butyrate induce a reversible body temperature drop through transient proton leak in mitochondria of brain neurons

AIMS

Sodium butyrate (SB) is a major product of gut microbiota with signaling activity in the human body. It has become a dietary supplement in the treatment of intestinal disorders. However, the toxic effect of overdosed SB and treatment strategy remain unknown. The two issues are addressed in current study.

MATERIALS AND METHODS

SB (0.3-2.5 g/kg) was administrated through a single peritoneal injection in mice. The core body temperature and mitochondrial function in the brown adipose tissue and brain were monitored. Pharmacodynamics, targeted metabolomics, electron microscope, oxygen consumption rate and gene knockdown were employed to dissect the mechanism for the toxic effect.

KEY FINDINGS

The temperature was reduced by SB (1.2-2.5 g/kg) in a dose-dependent manner in mice for 2-4 h. In the brain, the effect was associated with SB elevation and neurotransmitter reduction. Metabolites changes were seen in the glycolysis, TCA cycle and pentose phosphate pathways. Adenine nucleotide translocase (ANT) was activated by butyrate for proton transportation leading to a transient potential collapse through proton leak. The SB activity was attenuated by ANT inhibition from gene knockdown or pharmacological blocker. ROS was elevated by SB for the increased ANT activity in proton leak in Neuro-2a.

SIGNIFICANCE

Excessive SB generated an immediate and reversible toxic effect for inhibition of body temperature through transient mitochondrial dysfunction in the brain. The mechanism was quick activation of ANT proteins for potential collapse in mitochondria. ROS may be a factor in the ANT activation by SB.

Mitochondrial protein IF1 is a potential regulator of glucagon-like peptide (GLP-1) secretion function of the mouse intestine

IF1 (ATPIF1) is a nuclear DNA-encoded mitochondrial protein whose activity is inhibition of the F1Fo-ATP synthase to control ATP production. IF1 activity remains unknown in the regulation of GLP-1 activity. In this study, IF1 was examined in the diet-induced obese mice using the gene knockout (If1-KO) mice. The mice gained more body weight on a high fat diet without a change in food intake. Insulin tolerance was impaired, but the oral glucose tolerance was improved through an increase in GLP-1 secretion. The KO mice exhibited an improved intestine structure, mitochondrial superstructure, enhanced mitophagy, reduced apoptosis and decreased adenine nucleotide translocase 2 (ANT2) protein in the intestinal epithelial cells together with preserved gut microbiota. The data suggest that GLP-1 secretion was enhanced in the obese If1-KO mice to preserve glucose tolerance through a signaling pathway of ANT2/mitochondria/L-cells/GLP-1/insulin. IF1 is a potential mitochondrial target for induction of GLP-1 secretion in L-cells.

Regulating glucose metabolism using nanomedicines for cancer therapy

The regulation of glucose metabolism is a research focus in cancer treatment. Glucose metabolism is essential for maintaining the growth and proliferation of tumor cells, thus offering us great opportunities for tumor treatment. Recently, much progress has been made in efficient cancer treatment by regulating the pathway of glucose metabolism with nanomedicines due to the rapid development of nanotechnology and promising drug targets. In this review, we first introduced the pathway of cell energy supply from the perspective of aerobic and anaerobic processes. Then, we discussed the recent research progress in regulating glucose metabolism for various tumor resistance strategies including heat resistance, multiple drug resistance, and hypoxia. Finally, we presented the prospects and challenges of developing multifunctional nanoagents for efficient chemotherapy, hyperthermia, dynamic therapy and so on by regulating glucose metabolism.