Exploring the Key Amino Acid Residues Surrounding the Active Center of Lactate Dehydrogenase A for the Development of Ideal Inhibitors.

Lactate dehydrogenase A (LDHA) primarily catalyzes the conversion between lactic acid and pyruvate, serving as a key enzyme in the aerobic glycolysis pathway of sugar in tumor cells. LDHA plays a crucial role in the occurrence, development, progression, invasion, metastasis, angiogenesis, and immune escape of tumors. Consequently, LDHA not only serves as a biomarker for tumor diagnosis and prognosis but also represents an ideal target for tumor therapy. Although LDHA inhibitors show great therapeutic potential, their development has proven to be challenging. In the development of LDHA inhibitors, the key active sites of LDHA are emphasized. Nevertheless, there is a relative lack of research on the amino acid residues around the active center of LDHA. Therefore, in this study, we investigated the amino acid residues around the active center of LDHA. Through structure comparison analysis, five key amino acid residues (Ala30, Met41, Lys131, Gln233, and Ala259) were identified. Subsequently, the effects of these five residues on the enzymatic properties of LDHA were investigated using site-directed mutagenesis. The results revealed that the catalytic activities of the five mutants varied to different degrees in both the reaction from lactic acid to pyruvate and pyruvate to lactic acid. Notably, the catalytic activities of LDHAM41G and LDHAK131I were improved, particularly in the case of LDHAK131I. The results of the molecular dynamics analysis of LDHAK131I explained the reasons for this phenomenon. Additionally, the optimum temperature of LDHAM41G and LDHAQ233M increased from 35 °C to 40 °C, whereas in the reverse reaction, the optimum temperature of LDHAM41G and LDHAK131I decreased from 70 °C to 60 °C. These findings indicate that Ala30, Met41, Lys131, Gln233, and Ala259 exert diverse effects on the catalytic activity and optimum temperature of LHDA. Therefore, these amino acid residues, in addition to the key catalytic site of the active center, play a crucial role. Considering these residues in the design and screening of LDHA inhibitors may lead to the development of more effective inhibitors.

Oral hydrogel nanoemulsion co-delivery system treats inflammatory bowel disease via anti-inflammatory and promoting intestinal mucosa repair.

BACKGROUND: Due to oral nano-delivery systems for the treatment of inflammatory bowel disease (IBD) are often failed to accumulated to the colonic site and could not achieve controlled drug release, it's urgent to develop a microenvironment responsive drug delivery to improve therapy efficacy. Inflammation at the IBD site is mainly mediated by macrophages, which are the key effector cells. Excessive inflammation leads to oxidative stress and intestinal mucosal damage. The use of curcumin (CUR) and emodin (EMO) together for the treatment of IBD is promising due to their respective anti-inflammatory and intestinal mucosal repair effects. In view of the pH gradient environment of gastrointestinal tract, here we prepared pH-responsive sodium alginate (SA) hydrogel-coated nanoemulsions to co-deliver CUR and EMO (CUR/EMO NE@SA) to achieve controlled drug release and specifically target macrophages of the colon. RESULTS: In this study, a pH-responsive CUR/EMO NE@SA was successfully developed, in which the CUR/EMO NE was loaded by chitosan and further crosslinked with sodium alginate. CUR/EMO NE@SA had a pH-responsive property and could achieve controlled drug release in the colon. The preparation could significantly alleviate and improve the colon inflammatory microenvironment by decreasing TNF-α and IL-6 expression, increasing IL-10 expression, scavenging reactive oxygen species in macrophages, and by ameliorating the restoration of intestinal mucosal tight junction protein expression. Furthermore, we revealed the molecular mechanism of the preparation for IBD treatment, which might due to the CUR and EMO synergic inhibition of NF-κB to improve the pro-inflammatory microenvironment. Our study provides a new IBD therapy strategy via synergically inhibiting inflammatory, repairing mucosal and clearing ROS by pH-sensitive hydrogel-encapsulated nanoemulsion drug delivery system, which might be developed for other chronic inflammatory disease treatment. CONCLUSIONS: It's suggested that pH-sensitive hydrogel-coated nanoemulsion-based codelivery systems are a promising combinatorial platform in IBD.

Ischemic Preconditioning-Induced SOCS-1 Protects Rat Intestinal Ischemia Reperfusion Injury via Degradation of TRAF6.

BACKGROUND: The inflammatory immune response plays an important role in mesenteric ischemia and ischemia-reperfusion injury. Toll-like receptor 4 (TLR4) is a critical receptor in transduction of the inflammatory response and plays an important role in intestinal homeostasis. Tumor necrosis factor receptor-associated factor 6 (TRAF6), known as a key adaptor protein downstream of TLR4, is involved in the inflammatory response by activating multiple apoptotic signaling pathways. However, mechanisms of the suppressor of cytokine signaling-1 (SOCS-1) in regulating cell inflammation and apoptosis are still obscure. OBJECTIVES: To investigate the TLR4-TRAF6 signaling pathway in intestinal ischemia and reperfusion injury, as well as SOCS-1 expression after ischemic preconditioning in the rat intestine. METHODS: The small bowel ischemia, ischemia-reperfusion, and preconditioning models were induced using ligation of the superior mesenteric artery in male Sprague-Dawley rats; then, the mRNA and protein levels of TLR4, TRAF6, and SOCS-1 were analyzed using real-time PCR, Western blot, and immunohistochemistry, respectively. RESULTS: The expression of TLR4 and TRAF6 was gradually increased with increasing intestinal ischemia duration, but increased substantially after ischemia-reperfusion injury. After ischemic preconditioning, TLR4 and TRAF6 expressions decreased; however, expression of SOCS-1 and the TLR4-TRAF6 pathway inhibitor was increased. CONCLUSION: These data show that ischemic preconditioning may induce the activation of SOCS-1 to inhibit the TLR4-TRAF6 signaling pathway, thereby playing a protective role in ischemia-reperfusion injury.

Hypoxia-inducible factor in breast cancer: role and target for breast cancer treatment.

Globally, breast cancer stands as the most prevalent form of cancer among women. The tumor microenvironment of breast cancer often exhibits hypoxia. Hypoxia-inducible factor 1-alpha, a transcription factor, is found to be overexpressed and activated in breast cancer, playing a pivotal role in the anoxic microenvironment by mediating a series of reactions. Hypoxia-inducible factor 1-alpha is involved in regulating downstream pathways and target genes, which are crucial in hypoxic conditions, including glycolysis, angiogenesis, and metastasis. These processes significantly contribute to breast cancer progression by managing cancer-related activities linked to tumor invasion, metastasis, immune evasion, and drug resistance, resulting in poor prognosis for patients. Consequently, there is a significant interest in Hypoxia-inducible factor 1-alpha as a potential target for cancer therapy. Presently, research on drugs targeting Hypoxia-inducible factor 1-alpha is predominantly in the preclinical phase, highlighting the need for an in-depth understanding of HIF-1α and its regulatory pathway. It is anticipated that the future will see the introduction of effective HIF-1α inhibitors into clinical trials, offering new hope for breast cancer patients. Therefore, this review focuses on the structure and function of HIF-1α, its role in advancing breast cancer, and strategies to combat HIF-1α-dependent drug resistance, underlining its therapeutic potential.

The potential role of glucose metabolism, lipid metabolism, and amino acid metabolism in the treatment of Parkinson's disease.

PURPOSE OF REVIEW: Parkinson's disease (PD) is a common neurodegenerative disease, which can cause progressive deterioration of motor function causing muscle stiffness, tremor, and bradykinesia. In this review, we hope to describe approaches that can improve the life of PD patients through modifications of energy metabolism. RECENT FINDINGS: The main pathological features of PD are the progressive loss of nigrostriatal dopaminergic neurons and the production of Lewy bodies. Abnormal aggregation of α-synuclein (α-Syn) leading to the formation of Lewy bodies is closely associated with neuronal dysfunction and degeneration. The main causes of PD are said to be mitochondrial damage, oxidative stress, inflammation, and abnormal protein aggregation. Presence of abnormal energy metabolism is another cause of PD. Many studies have found significant differences between neurodegenerative diseases and metabolic decompensation, which has become a biological hallmark of neurodegenerative diseases. SUMMARY: In this review, we highlight the relationship between abnormal energy metabolism (Glucose metabolism, lipid metabolism, and amino acid metabolism) and PD. Improvement of key molecules in glucose metabolism, fat metabolism, and amino acid metabolism (e.g., glucose-6-phosphate dehydrogenase, triglycerides, and levodopa) might be potentially beneficial in PD. Some of these metabolic indicators may serve well during the diagnosis of PD. In addition, modulation of these metabolic pathways may be a potential target for the treatment and prevention of PD.

An oral bioactive chitosan-decorated doxorubicin nanoparticles/bacteria bioconjugates enhance chemotherapy efficacy in an in-situ breast cancer model.

Breast cancer is the second leading cause of cancer-related deaths among women worldwide. Despite significant advancements in chemotherapy, its effectiveness is often limited by poor drug distribution and systemic toxicity caused by the weak targeting ability of conventional therapeutic agents. The hypoxic tumor microenvironment (TME) also plays a vital role in treatment outcomes. Oral anticancer therapeutic agents have gained popularity and show promising results due to their ease of repeated administration. This study introduces autopilot biohybrids (Bif@BDC-NPs) for the effective delivery of doxorubicin (DOX) to the tumor site. This hybrid combines albumin-encapsulated DOX nanoparticles (BD-NPs) coated with chitosan (CS) for breast cancer chemotherapy, along with anaerobic Bifidobacterium infantis (B. infantis, Bif) serving as self-propelled motors. Due to Bif's specific anaerobic properties, Bif@BDC-NPs precisely anchor hypoxic regions of tumor tissue and significantly increase drug accumulation at the tumor site, thereby promoting tumor cell death. In an in-situ mouse breast cancer model, Bif@BDC-NPs achieved 94 % tumor inhibition, significantly prolonging the median survival of mice to 62 days, and reducing the toxic side effects of DOX. Therefore, the new bacteria-driven oral drug delivery system, Bif@BDC-NPs, overcomes multiple physiological barriers and holds great potential for the precise treatment of solid tumors.

GM-CSF augmented the photothermal immunotherapeutic outcome of self-driving gold nanoparticles against a mouse CT-26 colon tumor model.

BACKGROUND: Hypoxia is a frequent characteristic observed in solid tumors and is strongly associated with tumor metastasis, angiogenesis, and drug resistance. While the vasculature of hypoxic tumor tissues poses obstacles to the efficient administration of conventional drugs, it may prove advantageous in sustaining hyperthermia. Photothermal therapy (PTT) offers a promising treatment strategy that utilizes the activation of photosensitizers to produce heat, thus facilitating the selective ablation of tumor tissues. METHOD: To enhance the accumulation of photothermal agents in tumor tissue and improve the effectiveness of PTT, we developed a self-propelled hybrid called Bif@PAu-NPs. This hybrid consists of polydopamine (PDA)-coated gold nanoparticles (Au-NPs) loaded onto the anaerobic Bifidobacterium infantis (Bif). RESULTS: The Bif@PAu-NPs actively aggregated at the tumor site because the ability of Bif can target hypoxic regions, and PAu-NPs achieved precise PTT due to their high photothermal conversion efficiency (η = 67.8%). The tumor tissues were ablated by PTT, resulting in the release of antigens through immunogenic cell death (ICD), which stimulates an immune response. The inclusion of GM-CSF enhanced the immune response by recruiting dendritic cells and initiating long-term anti-tumor immunity. CONCLUSION: The Bif@PAu-NPs hybrid effectively suppressed the growth of both primary tumors and re-challenged tumors. The utilization Bif@PAu-NPs in conjunction with GM-SCF exhibits great potential as a photothermal-immunotherapeutic strategy for precisely treating solid tumors. In this study, the bacterial Bif@PAu-NPs biohybrid is exploited the self-driving ability of anaerobic Bifidobacterium infantis to deliver polydopamine-modified gold nanoparticles to hypoxic region of tumor. Under irradiation with 808 nm NIR laser, the hybrid exerts precise photothermal therapy to stimulate the immune response, which is further enhanced by GM-CSF, leading to recruitment of dendritic cells and initiation of a long-term anti-tumor immunity remember to prevent tumor recurrence.

Self-driven bioactive hybrids co-deliver doxorubicin and indocyanine green nanoparticles for chemo/photothermal therapy of breast cancer.

Breast cancer is characterized by insidious onset, rapid progression, easy recurrence, and metastasis. Conventional monotherapies are usually ineffective due to insufficient drug delivery. Therefore, the combination of multimodal therapy with tumor microenvironment (TME)-responsive nanoplatforms is increasingly being considered for the targeted treatment of breast cancer. We synthesized bioactive hybrid nanoparticles for synergistic chemotherapy and photothermal therapy. Briefly, doxorubicin (DOX) and indocyanine green (ICG)-loaded nanoparticles (DI) of average particle size 113.58 ± 2.14 nm were synthesized, and their surface were modified with polydopamine (PDA) and attached to the anaerobic probiotic Bifidobacterium infantis (Bif). The bioactive Bif@DIP hybrid showed good photothermal conversion efficiency of about 38.04%. In addition, the self-driving ability of Bif allowed targeted delivery of the PDA-coated DI nanoparticles (DIP) to the hypoxic regions of the tumor. The low pH and high GSH levels in the TME stimulated the controlled release of DOX and ICG from the Bif@DIP hybrid, which then triggered apoptosis of tumor cells and induced immunogenic cell death (ICD), resulting in effective and sustained anti-tumor effect with minimum systemic toxicity. Thus, the self-driven Bif@DIP hybrid is a promising nanodrug for the targeted chemotherapy and photothermal therapy against solid cancers.

Potential Role of APEX1 During Ferroptosis.

Ferroptosis is a recently discovered category of programmed cell death. It is much different from other types of cell death such as apoptosis, necrosis and autophagy. The main pathological feature of ferroptosis is the accumulation of iron-dependent lipid peroxidation. The typical changes in the morphological features of ferroptosis include cell volume shrinkage and increased mitochondrial membrane area. The mechanisms of ferroptosis may be mainly related to lipid peroxidation accumulation, imbalance in amino acid antioxidant system, and disturbance of iron metabolism. Besides, hypoxia-inducible factor (HIF), nuclear factor-E2-related factor 2 (Nrf2), and p53 pathway have been demonstrated to be involved in ferroptosis. At present, the molecular mechanisms of ferroptosis pathway are still unmapped. In this review, an outlook has been put forward about the crucial role of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) in the regulation of ferroptosis. APEX1 plays an important role in the regulation of intracellular redox balance and can be used as a potential inhibitor of ferroptotic cell death. Bioinformatics analysis indicated that the mRNA level of APEX1 is decreased in cases of ferroptosis triggered by erastin. Besides, it was found that there was a significant correlation between APEX1 and genes in the ferroptosis pathway. We have discussed the possibility to employ APEX1 inducers or inhibitors in the regulation of ferroptosis as a new strategy for the treatment of various human diseases.

Glutamic Acid Transporters: Targets for Neuroprotective Therapies in Parkinson's Disease.

Parkinson's disease (PD) is a common neurodegenerative disease in middle-aged and elderly individuals. At present, no effective drug has been developed to treat PD. Although a variety of drugs exist for the symptomatic treatment of PD, they all have strong side effects. Most studies on PD mainly focus on dopaminergic neurons. This review highlights the function of glutamic acid transporters (GLTs), including excitatory amino acid transporters (EAATs) and vesicular glutamate transporters (VGLUTs), during the development of PD. In addition, using bioinformatics, we compared the expression of different types of glutamate transporter genes in the cingulate gyrus of PD patients and healthy controls. More importantly, we suggest that the functional roles of glutamate transporters may prove beneficial in the treatment of PD. In summary, VGLUTs and EAATs may be potential targets in the treatment of PD. VGLUTs and EAATs can be used as clinical drug targets to achieve better efficacy. Through this review article, we hope to enable future researchers to improve the condition of PD patients.

Notoginsenoside R1 Protects Against the Acrylamide-Induced Neurotoxicity via Upregulating Trx-1-Mediated ITGAV Expression: Involvement of Autophagy.

Acrylamide (ACR) is a common chemical used in various industries and it said to have chronic neurotoxic effects. It is produced during tobacco smoking and is also generated in high-starch foods during heat processing. Notoginsenoside R1 (NR1) is a traditional Chinese medicine, which is used to improve the blood circulation and clotting. The objective of this study was to investigate the mechanism of ACR-triggered neurotoxicity and to identify the protective role of NR1 by upregulating thioredoxin-1 (Trx-1). Our results have shown that NR1 could block the spatial and cognitive impairment caused by ACR administration. Bioinformatics analysis revealed that Trx-1 regulated autophagy via Integrin alpha V (ITGAV). NR1 could resist the ACR-induced neurotoxicity by upregulating thioredoxin-1 in PC12 cells and mice. The autophagy-related proteins like autophagy-related gene (ATG) 4B, Cathepsin D, LC3 II, lysosomal-associated membrane protein 2a (LAMP2a), and ITGAV were restored to normal levels by NR1 treatment in both PC12 cells and mice. Besides, we also found that overexpression of Trx-1 resisted ACR-induced autophagy in PC12 cells and downregulation of Trx-1 triggered autophagy induced by ACR in PC12 cells. Therefore, it could be concluded that Trx-1 was involved in the autophagy pathway. Besides, we also found that ITGAV was an intermediate node linking Trx-1 and the autophagy pathway.

A Mini-Review of the Role of Glutamate Transporter in Drug Addiction.

Goals: The development of new treatment for drug abuse requires identification of targetable molecular mechanisms. The pathology of glutamate neurotransmission system in the brain reward circuit is related to the relapse of multiple drugs. Glutamate transporter regulates glutamate signaling by removing excess glutamate from the synapse. And the mechanisms between glutamate transporter and drug addiction are still unclear. Methods: A systematic review of the literature searched in Pubmed and reporting drug addiction in relation to glutamate transporter. Studies were screened by title, abstract, and full text. Results: This review is to highlight the effects of drug addiction on glutamate transporter and glutamate uptake, and targeting glutamate transporter as an addictive drug addiction treatment. We focus on the roles of glutamate transporter in different brain regions in drug addiction. More importantly, we suggest the functional roles of glutamate transporter may prove beneficial in the treatment of drug addiction. Conclusion: Overall, understanding how glutamate transporter impacts central nervous system may provide a new insight for treatment of drug addiction.

Reduced expression of activin receptor-like kinase 7 in breast cancer is associated with tumor progression.

To explore the clinical implication of activin receptor-like kinase 7 (ALK7) expression in breast cancer, we evaluated its protein level in six kinds of human breast tissue samples, including adjacent normal tissues, adenosis, breast fibroadenoma, ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and lymph node metastases (LNM). Immunohistochemical analyses showed that ALK7 was more frequently and much more intensely expressed in adjacent normal tissues, adenosis, and fibroadenoma tissues than in malignant tissues (DCIS, IDC, and LNM). Furthermore, the ALK7 expression in primary tumors and the corresponding LNM was evaluated in parallel samples from 60 patients with IDC. Results showed that the ALK7 expression status in primary tumors and LNM was concordant in 53 patients (88%), suggesting that ALK7 expression was retained in LNM. Moreover, our results suggested that ALK7 expression inversely correlated with the tumor grade (P=0.009) and clinical stage (P=0.004) in IDC significantly. Finally, the effect of activin-ALK7 pathway on the breast cancer cell growth was elucidated, and results revealed that overexpression of ALK7 could restore the inhibitory effect of activin B on the growth of ALK7-negative breast cancer cell line, ZR-75-30. These findings provide the evidence that the reduction or lack of ALK7 expression may account for the loss of its ligand sensitivity of breast cancer cells, thereby leading to breast tumor progression.