Metabolic enzyme LDHA activates Rac1 GTPase as a noncanonical mechanism to promote cancer

LDHA-mediated M2-type macrophage polarization via tumor-derived exosomal EPHA2 promotes renal cell carcinoma progression

Lactate dehydrogenase A (LDHA) is known to promote the growth and invasion of various types of tumors, affects tumor resistance, and is associated with tumor immune escape. But how LDHA reshapes the tumor microenvironment and promotes the progression of renal cell carcinoma (RCC) remains unclear. In this study, we found that LDHA was highly expressed in clear cell RCC (ccRCC), and this high expression was associated with macrophage infiltration, while macrophages were highly infiltrated in ccRCC, affecting patient prognosis via M2-type polarization. Our in vivo and in vitro experiments demonstrated that LDHA and M2-type macrophages could enhance the proliferation, invasion, and migration abilities of ccRCC cells. Mechanistically, high expression of LDHA in ccRCC cells upregulated the expression of EPHA2 in exosomes derived from renal cancer. Exosomal EPHA2 promoted M2-type polarization of macrophages by promoting activation of the PI3K/AKT/mTOR pathway in macrophages, thereby promoting the progression of ccRCC. All these findings suggest that EPHA2 may prove to be a potential therapeutic target for advanced RCC.

A Novel Nanozyme to Enhance Radiotherapy Effects by Lactic Acid Scavenging, ROS Generation, and Hypoxia Mitigation

Uveal melanoma (UM) is a leading intraocular malignancy with a high 5-year mortality rate, and radiotherapy is the primary approach for UM treatment. However, the elevated lactic acid, deficiency in ROS, and hypoxic tumor microenvironment have severely reduced the radiotherapy outcomes. Hence, this study devised a novel CoMnFe-layered double oxides (LDO) nanosheet with multienzyme activities for UM radiotherapy enhancement. On one hand, LDO nanozyme can catalyze hydrogen peroxide (H2O2) in the tumor microenvironment into oxygen and reactive oxygen species (ROS), significantly boosting ROS production during radiotherapy. Simultaneously, LDO efficiently scavenged lactic acid, thereby impeding the DNA and protein repair in tumor cells to synergistically enhance the effect of radiotherapy. Moreover, density functional theory (DFT) calculations decoded the transformation pathway from lactic to pyruvic acid, elucidating a previously unexplored facet of nanozyme activity. The introduction of this innovative nanomaterial paves the way for a novel, targeted, and highly effective therapeutic approach, offering new avenues for the management of UM and other cancer types.

Implication of Rac1 GTPase in molecular and cellular mitochondrial functions

Rac1 is a member of the Rho GTPase family which plays major roles in cell mobility, polarity and migration, as a fundamental regulator of actin cytoskeleton. Signal transduction by Rac1 occurs through interaction with multiple effector proteins, and its activity is regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). The small protein is mainly anchored to the inner side of the plasma membrane but it can be found in endocellular compartments, notably endosomes and cell nuclei. The protein localizes also into mitochondria where it contributes to the regulation of mitochondrial dynamics, including both mitobiogenesis and mitophagy, in addition to signaling processes via different protein partners, such as the proapoptotic protein Bcl-2 and chaperone sigma-1 receptor (σ-1R). The mitochondrial form of Rac1 (mtRac1) has been understudied thus far, but it is as essential as the nuclear or plasma membrane forms, via its implication in regulation of oxidative stress and DNA damages. Rac1 is subject to diverse post-translational modifications, notably to a geranylgeranylation which contributes importantly to its mitochondrial import and its anchorage to mitochondrial membranes. In addition, Rac1 contributes to the mitochondrial translocation of other proteins, such as p53. The mitochondrial localization and functions of Rac1 are discussed here, notably in the context of human diseases such as cancers. Inhibitors of Rac1 have been identified (NSC-23766, EHT-1864) and some are being developed for the treatment of cancer (MBQ-167) or central nervous system diseases (JK-50561). Their effects on mtRac1 warrant further investigations. An overview of mtRac1 is provided here.

Metabolic Enzyme SLC27A5 Regulates PIP4K2A pre-mRNA Splicing as a Noncanonical Mechanism to Suppress Hepatocellular Carcinoma Metastasis

Solute carrier family 27 member 5, a key enzyme in fatty acid transport and bile acid metabolism in the liver, is frequently expressed in low quantities in patients with hepatocellular carcinoma, resulting in poor prognosis. However, it is unclear whether SLC27A5 plays non-canonical functions and regulates HCC progression. Here, an unexpected non-canonical role of SLC27A5 is reported: regulating the alternative splicing of mRNA to inhibit the metastasis of HCC independently of its metabolic enzyme activity. Mechanistically, SLC27A5 interacts with IGF2BP3 to prevent its translocation into the nucleus, thereby inhibiting its binding to target mRNA and modulating PIP4K2A pre-mRNA splicing. Loss of SLC27A5 results in elevated levels of the PIP4K2A-S isoform, thus positively regulating phosphoinositide 3-kinase signaling via enhanced p85 stability in HCC. SLC27A5 restoration by AAV-Slc27a5 or IGF2BP3 RNA decoy oligonucleotides exerts an inhibitory effect on HCC metastasis with reduced expression of the PIP4K2A-S isoform. Therefore, PIP4K2A-S may be a novel target for treating HCC with SLC27A5 deficiency.

The bidirectional relationship between metabolism and cell cycle control

The relationship between metabolism and cell cycle progression is complex and bidirectional. Cells must rewire metabolism to meet changing biosynthetic demands across cell cycle phases. In turn, metabolism can influence cell cycle progression through direct regulation of cell cycle proteins, through nutrient-sensing signaling pathways, and through its impact on cell growth, which is linked to cell division. Furthermore, metabolism is a key player in mediating quiescence-proliferation transitions in physiologically important cell types, such as stem cells. How metabolism impacts cell cycle progression, exit, and re-entry, as well as how these processes impact metabolism, is not fully understood. Recent advances uncovering mechanistic links between cell cycle regulators and metabolic processes demonstrate a complex relationship between metabolism and cell cycle control, with many questions remaining.

Identifying the critical oncogenic mechanism of LDHA based on a prognostic model of T-cell synthetic drivers

BACKGROUND

Despite its early success, immunotherapy focused on removing T-cell inhibition does not achieve the desired effect in most patients. New strategies that target antigen-driven T-cell activation are needed to improve immunotherapy outcomes. However, a comprehensive analysis of synthetic drivers of T-cells is greatly lacking in lung adenocarcinoma (LUAD) and other types of tumors.

METHODS

We comprehensively evaluated the patterns of LUAD patients based on T -cell synthetic drivers by unsupervised clustering analysis. A risk model was constructed using Lasso Cox regression analysis. The predicted survival and immunotherapy efficacy of the model was validated by independent cohorts. Finally, single-cell sequencing analysis, and a series of in vitro experiments were conducted to explore the role of lactate dehydrogenase A (LDHA) in the malignant progression of LUAD.

RESULTS

Patients in the high-risk group were characterized by survival disadvantage, a "cold" immune phenotype, and by not having benefitted from immunotherapy. LDHA was shown to promote LUAD cell proliferation, cell cycle, invasion, and migration. Secondly, we found that LDHA induced NF-κB pathway activation, tyrosine kinase inhibitor resistance and immunosuppressant microenvironment. Finally, LDHA was found to be highly expressed in fibroblasts, which may be involved in promoting TKI resistance and mediating the immune escape.

CONCLUSION

This study revealed that the T-cell synthetic driver-associated prognostic model developed herein significantly predicted prognosis and immunotherapy efficacy in LUAD. We further investigated the role of LDHA in the malignant phenotype of tumor cells and tumor microenvironment remodeling, providing a promising and novel therapeutic strategy for LUAD.

Multi-omics identification of GPCR gene features in lung adenocarcinoma based on multiple machine learning combinations

Background: Lung adenocarcinoma is a common malignant tumor that ranks second in the world and has a high mortality rate. G protein-coupled receptors (GPCRs) have been reported to play an important role in cancer; however, G protein-coupled receptor-associated features have not been adequately investigated. Methods: In this study, GPCR-related genes were screened at single-cell and bulk transcriptome levels based on AUcell, single-sample gene set enrichment analysis (ssGSEA) and weighted gene co-expression network (WGCNA) analysis. And a new machine learning framework containing 10 machine learning algorithms and their multiple combinations was used to construct a consensus G protein-coupled receptor-related signature (GPCRRS). GPCRRS was validated in the training set and external validation set. We constructed GPCRRS-integrated nomogram clinical prognosis prediction tools. Multi-omics analyses included genomics, single-cell transcriptomics, and bulk transcriptomics to gain a more comprehensive understanding of prognostic features. We assessed the response of risk subgroups to immunotherapy and screened for personalized drugs targeting specific risk subgroups. Finally, the expression of key GPCRRS genes was verified by RT-qPCR. Results: In this study, we identified 10 GPCR-associated genes that were significantly associated with the prognosis of lung adenocarcinoma by single-cell transcriptome and bulk transcriptome. Univariate and multivariate showed that the survival rate was higher in low risk than in high risk, which also suggested that the model was an independent prognostic factor for LUAD. In addition, we observed significant differences in biological function, mutational landscape, and immune cell infiltration in the tumor microenvironment between high and low risk groups. Notably, immunotherapy was also relevant in the high and low risk groups. In addition, potential drugs targeting specific risk subgroups were identified. Conclusion: In this study, we constructed and validated a lung adenocarcinoma G protein-coupled receptor-related signature, which has an important role in predicting the prognosis of lung adenocarcinoma and the effect of immunotherapy. It is hypothesized that LDHA, GPX3 and DOCK4 are new potential targets for lung adenocarcinoma, which can achieve breakthroughs in prognosis prediction, targeted prevention and treatment of lung adenocarcinoma and provide important guidance for anti-tumor.

An aging-related gene signature to predict the prognosis of hepatocellular carcinoma

Aging increases the susceptibility of various diseases, including hepatocellular carcinoma (HCC). This study aimed to establish an aging-related prognostic model for HCC and to investigate the role of aging-related genes in HCC progression. Transcriptome and clinical information of HCC cases were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Aging-related prognostic genes were identified through univariate Cox regression analysis, protein-protein interaction analysis, and least absolute shrinkage and selection operator (LASSO) analysis. An aging-related risk signature was then constructed, including LDHA, MMP12, ATAD3A, CD8A, TPI1, CST3, and TPM1. The risk score was inversely associated with the overall survival of patients with HCC and correlated well with known prognostic factors. The area under the curve of 1-, 3-, and 5-year survival in the training dataset was 0.83, 0.83, and 0.84, respectively. Univariate and multivariate cox regression analysis verified that the aging-related risk signature independently predicted the overall survival in HCC. To increase the clinical utility of the prognostic model, a nomogram was developed by incorporating the risk score with key clinical features. Finally, single-cell transcriptomes of HCC were analyzed to elucidate the expression pattern of the prognostic genes across different tissues, pathologic stages, and cell types. Collectively, the aging-related prognostic model shed light on HCC pathogenesis and held potential for optimizing the management of HCC.

The Significance of Microenvironmental and Circulating Lactate in Breast Cancer

Lactate represents the main product of pyruvate reduction catalyzed by the lactic dehydrogenase family of enzymes. Cancer cells utilize great quantities of glucose, shifting toward a glycolytic metabolism. With the contribution of tumor stromal cells and under hypoxic conditions, this leads toward the acidification of the extracellular matrix. The ability to shift between different metabolic pathways is a characteristic of breast cancer cells and is associated with an aggressive phenotype. Furthermore, the preliminary scientific evidence concerning the levels of circulating lactate in breast cancer points toward a correlation between hyperlactacidemia and poor prognosis, even though no clear linkage has been demonstrated. Overall, lactate may represent a promising metabolic target that needs to be investigated in breast cancer.

Targeting small GTPases: emerging grasps on previously untamable targets, pioneered by KRAS

Small GTPases including Ras, Rho, Rab, Arf, and Ran are omnipresent molecular switches in regulating key cellular functions. Their dysregulation is a therapeutic target for tumors, neurodegeneration, cardiomyopathies, and infection. However, small GTPases have been historically recognized as "undruggable". Targeting KRAS, one of the most frequently mutated oncogenes, has only come into reality in the last decade due to the development of breakthrough strategies such as fragment-based screening, covalent ligands, macromolecule inhibitors, and PROTACs. Two KRAS^G12C covalent inhibitors have obtained accelerated approval for treating KRAS^G12C mutant lung cancer, and allele-specific hotspot mutations on G12D/S/R have been demonstrated as viable targets. New methods of targeting KRAS are quickly evolving, including transcription, immunogenic neoepitopes, and combinatory targeting with immunotherapy. Nevertheless, the vast majority of small GTPases and hotspot mutations remain elusive, and clinical resistance to G12C inhibitors poses new challenges. In this article, we summarize diversified biological functions, shared structural properties, and complex regulatory mechanisms of small GTPases and their relationships with human diseases. Furthermore, we review the status of drug discovery for targeting small GTPases and the most recent strategic progress focused on targeting KRAS. The discovery of new regulatory mechanisms and development of targeting approaches will together promote drug discovery for small GTPases.

The Role of NAD+, SIRTs Interactions in Stimulating and Counteracting Carcinogenesis

The World Health Organization has identified oncological diseases as one of the most serious health concerns of the current century. Current research on oncogenesis is focused on the molecular mechanisms of energy-biochemical reprogramming in cancer cell metabolism, including processes contributing to the Warburg effect and the pro-oncogenic and anti-oncogenic roles of sirtuins (SIRTs) and poly-(ADP-ribose) polymerases (PARPs). However, a clear understanding of the interaction between NAD⁺, SIRTs in cancer development, as well as their effects on carcinogenesis, has not been established, and literature data vary greatly. This work aims to provide a summary and structure of the available information on NAD⁺, SIRTs interactions in both stimulating and countering carcinogenesis, and to discuss potential approaches for pharmacological modulation of these interactions to achieve an anticancer effect.

On the Role of Glycolysis in Early Tumorigenesis-Permissive and Executioner Effects

Reprogramming energy production from mitochondrial respiration to glycolysis is now considered a hallmark of cancer. When tumors grow beyond a certain size they give rise to changes in their microenvironment (e.g., hypoxia, mechanical stress) that are conducive to the upregulation of glycolysis. Over the years, however, it has become clear that glycolysis can also associate with the earliest steps of tumorigenesis. Thus, many of the oncoproteins most commonly involved in tumor initiation and progression upregulate glycolysis. Moreover, in recent years, considerable evidence has been reported suggesting that upregulated glycolysis itself, through its enzymes and/or metabolites, may play a causative role in tumorigenesis, either by acting itself as an oncogenic stimulus or by facilitating the appearance of oncogenic mutations. In fact, several changes induced by upregulated glycolysis have been shown to be involved in tumor initiation and early tumorigenesis: glycolysis-induced chromatin remodeling, inhibition of premature senescence and induction of proliferation, effects on DNA repair, O-linked N-acetylglucosamine modification of target proteins, antiapoptotic effects, induction of epithelial-mesenchymal transition or autophagy, and induction of angiogenesis. In this article we summarize the evidence that upregulated glycolysis is involved in tumor initiation and, in the following, we propose a mechanistic model aimed at explaining how upregulated glycolysis may play such a role.

Beyond Warburg: LDHA activates RAC for tumour growth

The physiological role of aerobic glycolysis (also known as the Warburg effect), which is observed in many tumours, is still not fully understood. The finding that lactate dehydrogenase A (LDHA) activates RAC1 in breast cancer sheds new light on this persistently enigmatic aspect of cancer metabolism.