When fats commit crimes: fatty acid metabolism, cancer stemness and therapeutic resistance

Regulation of lung cancer initiation and progression by the stem cell determinant Musashi

Despite advances in therapeutic approaches, lung cancer remains the leading cause of cancer-related deaths. To understand the molecular programs underlying lung cancer initiation and maintenance, we focused on stem cell programs that are normally extinguished with differentiation but can be reactivated during oncogenesis. Here, we have used extensive genetic modeling and patient-derived xenografts (PDXs) to identify a dual role for Msi2: as a signal that acts initially to sensitize cells to transformation, and subsequently to drive tumor propagation. Using Msi reporter mice, we found that Msi2-expressing cells were marked by a pro-oncogenic landscape and a preferential ability to respond to Ras and p53 mutations. Consistent with this, genetic deletion of Msi2 in an autochthonous Ras/p53-driven lung cancer model resulted in a marked reduction of tumor burden, delayed progression, and a doubling of median survival. Additionally, this dependency was conserved in human disease as inhibition of Msi2 impaired tumor growth in PDXs. Mechanistically, Msi2 triggered a broad range of pathways critical for tumor growth, including several novel effectors of lung adenocarcinoma. Collectively, these findings reveal a critical role for Msi2 in aggressive lung adenocarcinoma, lend new insight into the biology of this disease, and identify potential new therapeutic targets.

Lipid metabolic reprograming: the unsung hero in breast cancer progression and tumor microenvironment

Aberrant lipid metabolism is a well-recognized hallmark of cancer. Notably, breast cancer (BC) arises from a lipid-rich microenvironment and depends significantly on lipid metabolic reprogramming to fulfill its developmental requirements. In this review, we revisit the pivotal role of lipid metabolism in BC, underscoring its impact on the progression and tumor microenvironment. Firstly, we delineate the overall landscape of lipid metabolism in BC, highlighting its roles in tumor progression and patient prognosis. Given that lipids can also act as signaling molecules, we next describe the lipid signaling exchanges between BC cells and other cellular components in the tumor microenvironment. Additionally, we summarize the therapeutic potential of targeting lipid metabolism from the aspects of lipid metabolism processes, lipid-related transcription factors and immunotherapy in BC. Finally, we discuss the possibilities and problems associated with clinical applications of lipid‑targeted therapy in BC, and propose new research directions with advances in spatiotemporal multi-omics.

AURKB affects the proliferation of clear cell renal cell carcinoma by regulating fatty acid metabolism

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer with a high metastatic rate and high mortality rate. The molecular mechanism of ccRCC development, however, needs further study. Aurora kinase B (AURKB) functions as an important oncogene in various tumors; therefore, in the present study, we aimed to explore the mechanism by which AURKB affects ccRCC development.

METHODS

We performed bioinformatics analysis, CCK-8 assay, RNA sequencing, RT-PCR and Western blot to analyze the function and mechanism of AURKB in ccRCC.

RESULTS

TIMER2.0 showed that AURKB was overexpressed in Kidney Renal Clear Cell Carcinoma (KIRC), the UALCAN database showed the survival rate of KIRC patients with different expression levels of AURKB and different gender indicated in the same gender, high AURKB expression predicts lower survival rate. Silencing of AURKB expression inhibits the proliferation of ccRCC cells. RNA-seq data suggested that AURKB is involved in fatty acid metabolism. Silencing of AURKB inhibited the expression of fatty acid synthase (FASN). FASN is a key gene involved in fatty acid metabolism. TIMER2.0 showed that FASN is upregulated in KIRC. Silencing of FASN inhibited the proliferation of ccRCC cells.

CONCLUSIONS

AURKB induces the proliferation of ccRCC cells by regulating fatty acid metabolism.

Altered fatty acid metabolism rewires cholangiocarcinoma stemness features

Background & Aims

Among the reprogrammed metabolic pathways described in cancer stem cells, aberrant lipid metabolism has recently drawn increasing attention. Our study explored the contribution of fatty acids (FA) in the regulation of stem-like features in intrahepatic cholangiocarcinoma (iCCA).

Methods

We previously identified a functional stem-like subset in human iCCA by using a three-dimensional sphere (SPH) model in comparison to parental cells grown as monolayers (MON). In this study, quantification of intracellular free FA and lipidomic analysis (triacylglycerol [TAG] composition, de novo synthesis products) was performed by Liquid chromatography-mass spectrometry (LC-MS); quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS), respectively, in both SPH and MON cultures.

Results

Stem-like SPH showed a superior content of free FA (citric, palmitic, stearic, and oleic acids) and unsaturated TAG. Molecularly, SPH showed upregulation of key metabolic enzymes involved in de novo FA biosynthesis (AceCS1, ACLY, ACAC, FASN, ACSL1) and the mTOR signalling pathway. In patients with iCCA (n = 68), tissue expression of FASN, a key gene involved in FA synthesis, correlated with 5-year overall survival. Interference with FASN activity in SPH cells through both specific gene silencing (siRNA) or pharmacological inhibition (orlistat) decreased sphere-forming ability and expression of stem-like markers. In a murine xenograft model obtained by injection of iCCA-SPH cells, FASN inhibition by orlistat or injection of FASN-silenced cells significantly reduced tumour growth and expression of stem-like genes.

Conclusion

Altered FA metabolism contributes to the maintenance of a stem-like phenotype in iCCA. FASN inhibition may represent a new approach to interfere with the progression of this deadly disease.

Impact and implications

Recent evidence indicates that metabolic disorders correlate with an increased susceptibility to intrahepatic cholangiocarcinoma (iCCA). Our investigation emphasises the pivotal involvement of lipid metabolism in the tumour stem cell biology of iCCA, facilitated by the upregulation of crucial enzymes and the mTOR signalling pathway. From a clinical perspective, this underscores the dual role of FASN as both a prognostic indicator and a therapeutic target, suggesting that FASN inhibitors could enhance patient outcomes by diminishing stemness and tumour aggressiveness. These findings pave the way for novel therapeutic strategies for iCCA and shed light on its relationship with metabolic disorders such as diabetes, obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease.

Association between body mass index and lymph node metastasis among women with cervical cancer: a systematic review and network meta-analysis

PURPOSE

Lymph node status is a determinant of survival in patients with early-stage cervical cancer. However, the relationship between obesity and lymph node status remains unclear. Therefore, this systematic review aims to evaluate the correlation between body mass index (BMI) and lymph node metastasis in cervical cancer.

METHODS

Cohort studies through six databases were reviewed until December 2021. Odds ratios (ORs) for lymphatic metastasis were estimated using random-effects models and network meta-analysis. BMI groups for lymph node metastasis were ranked. Heterogeneities were assessed using I2. Subgroup analyses were performed to determine possible sources of heterogeneity.

RESULTS

No significant difference was found between obese (BMI ≥ 25) and non-obese patients (BMI < 25) (OR = 1.01; 95% CI 0.69-1.47; P = 0.97). In subgroup analyses, obesity was associated with higher risk among the Americans and advanced-stage patients. The grouping analysis based on BMI and the rankogram values revealed that the '35 ≤ BMI' group had the highest risk of lymph node metastasis.

CONCLUSION

Although there were no significant differences in lymph node metastasis between obese and non-obese cervical cancer patients in overall analysis, patients with BMI ≥ 35 were at significantly higher risk of lymph node metastasis.

Two metabolic enzymes, LDH and FASN, serum levels in Bladder cancer patients

Background

Bladder cancer is one of the most common cancers in the world and is associated with high treatment costs and mortality. The role of different enzymes and molecules in this cancer has been the subject of extensive research in recent years. Among these, the role of metabolic enzymes such as FASN and LDH has been studied less than others. Therefore, the present study was designed to investigate the role of FASN and LDH in bladder cancer patients.

Methods

One hundred cases diagnosed with bladder cancer and 50 sex-age- matched healthy individuals as control were examined. FASN and LDH serum levels in both patients and controls were determined by human-specific sandwich ELISA kits.

Results

Serum levels of FASN and LDH elevated in bladder cancer patients in comparison to healthy individuals (P= 0.03, P= 0.01, respectively). We also found that than higher stages of bladder cancer (III-IV) had higher serum levels of LDH and FASN compared to early stages (I-II) (P= 0.007 and P= 0.006, respectively). Moreover, there was a statistically significant association between smoking history and serum FASN levels in bladder cancer patients (P=0.015). However, there were no remarkable associations between the serum levels of LDH and FASN with other clinicopathological features including sex, age, tumor grade, and tumor size.

Conclusion

The data indicate that LDH and FASN may be good and useful biomarkers in the diagnosis and clinical management of bladder cancer. However, further studies are needed.

Efavirenz: New Hope in Cancer Therapy

Despite extensive research directed at preventive and treatment strategies, breast cancer remains the leading cause of cancer-related mortality among women. This necessitates the development of a new medication aimed at increasing patient survival and quality of life. A new drug's development from the ground up can cost billions of dollars and take up to ten or more years. Because much of the required safety and pharmacokinetic data are already available from earlier trials, repurposing medications usually results in lower costs and shorter turnaround times. Many antiretroviral medications target biological pathways and enzymes associated with cancer, which becomes an ideal option for repurposing as anticancer medications. Efavirenz is an antiretroviral medication that targets molecular pathways implicated in the growth of breast cancer, such as LINE-1 (long interspersed nuclear elements-1) suppression, hence lowering the proliferation of breast cancer cells and exhibiting anti-cancer properties. Additionally, it suppresses the fatty acid synthase gene and other important genes related to fat metabolism, impairing mitochondrial activity and making cancer cells deprived of energy. Efavirenz also inhibits cancer-initiating stem cells, promotes differentiation, and prevents recurrence. Additionally, efavirenz promotes oxidative damage by the formation of superoxide in cancer cells. In addition to its anti-cancer properties, efavirenz has the advantage of being a well-established and relatively inexpensive medication with a favorable safety profile. If proven effective, efavirenz could offer a cost-effective therapeutic option, which is an intriguing direction that warrants further investigation.

Oncogenic Animal Herpesviruses

Oncogenic viruses play a pivotal role in oncology due to their unique role in unraveling the complexities of cancer development. Understanding the role viruses play in specific cancers is important to provide basic insights into the transformation process, which will help identify potential cellular targets for treatment. This review discusses the diverse role of animal herpesviruses in initiating and promoting various forms of cancer. We will summarize the mechanisms that underlie the development of animal herpesvirus-induced cancer that may provide a basis for developing potential therapeutic interventions or preventative strategies in the future.

Unraveling the intricate relationship between lipid metabolism and oncogenic signaling pathways

Lipids, the primary constituents of the cell membrane, play essential roles in nearly all cellular functions, such as cell-cell recognition, signaling transduction, and energy provision. Lipid metabolism is necessary for the maintenance of life since it regulates the balance between the processes of synthesis and breakdown. Increasing evidence suggests that cancer cells exhibit abnormal lipid metabolism, significantly affecting their malignant characteristics, including self-renewal, differentiation, invasion, metastasis, and drug sensitivity and resistance. Prominent oncogenic signaling pathways that modulate metabolic gene expression and elevate metabolic enzyme activity include phosphoinositide 3-kinase (PI3K)/AKT, MAPK, NF-kB, Wnt, Notch, and Hippo pathway. Conversely, when metabolic processes are not regulated, they can lead to malfunctions in cellular signal transduction pathways. This, in turn, enables uncontrolled cancer cell growth by providing the necessary energy, building blocks, and redox potentials. Therefore, targeting lipid metabolism-associated oncogenic signaling pathways could be an effective therapeutic approach to decrease cancer incidence and promote survival. This review sheds light on the interactions between lipid reprogramming and signaling pathways in cancer. Exploring lipid metabolism as a target could provide a promising approach for creating anticancer treatments by identifying metabolic inhibitors. Additionally, we have also provided an overview of the drugs targeting lipid metabolism in cancer in this review.

Immunotherapy, prognostic, and tumor biomarker based on pancancer analysis, SMARCD3

BACKGROUND

SMARCD3 has recently been shown to be an important gene affecting cancer, playing an important role in medulloblastoma and pancreatic ductal adenocarcinoma. Therefore, we conducted this research to investigate the potential involvement of SMARCD3 across cancers and to offer recommendations for future studies.

METHODS

Utilizing information on 33 malignancies in the UCSC Xena database, SMARCD3 expression and its prognostic value were assessed. The tumor microenvironment was evaluated with the "CIBERSORT" and "ESTIMATE" algorithms. SMARCD3 and immune-related genes were analyzed using the TISIDB website. The pathways related to the target genes were examined using GSEA. MSI (microsatellite instability), TMB (tumor mutational burden), and immunotherapy analysis were used to evaluate the impact of target genes on the response to immunotherapy.

RESULTS

There is heterogeneity in terms of the expression and prognostic value of SMARCD3 among various cancers, but it is a risk factor for many cancers including uterine corpus endometrial cancer (UCEC), renal clear cell carcinoma (KIRC), and gastric adenocarcinoma (STAD). GSEA revealed that SMARCD3 is related to chromatin remodeling and transcriptional activation, lipid metabolism, and the activities of various immune cells. The TMB and MSI analyses suggested that SMARCD3 affects the immune response efficiency of KIRC, LUAD and STAD. Immunotherapy analysis suggested that SMARCD3 may be a potential immunotherapy target. RT-qPCR demonstrated the variation in SMARCD3 expression in KIRC, LUAD, and STAD.

CONCLUSION

Our study revealed that SMARCD3 affects the prognosis and immunotherapy response of some tumors, providing a direction for further research on this gene.

Tanshinone IIA reverses gefitinib resistance in EGFR-mutant lung cancer via inhibition of SREBP1-mediated lipogenesis

BACKGROUND AND AIM

Gefitinib resistance is an urgent problem to be solved in the treatment of non-small cell lung cancer (NSCLC). Tanshinone IIA (Tan IIA) is one of the main active components of Salvia miltiorrhiza, which exhibits significant antitumor effects. The aim of this study is to explore the reversal effect of Tan IIA on gefitinib resistance in the epidermal growth factor receptor (EGFR)-mutant NSCLC and the underlying mechanism.

EXPERIMENTAL PROCEDURE

CCK-8, colony formation assay, and flow cytometry were applied to detect the cytotoxicity, proliferation, and apoptosis, respectively. The changes in lipid profiles were measured by electrospray ionization-mass spectrometry (MS)/MS. Western blot, real-time q-PCR, and immunohistochemical were used to detect the protein and the corresponding mRNA levels. The in vivo antitumor effect was validated by the xenograft mouse model.

KEY RESULTS

Co-treatment of Tan IIA enhanced the sensitivity of resistant NSCLC cells to gefitinib. Mechanistically, Tan IIA could downregulate the expression of sterol regulatory element binding protein 1 (SREBP1) and its downstream target genes, causing changes in lipid profiles, thereby reversing the gefitinib-resistance in EGFR-mutant NSCLC cells in vitro and in vivo.

CONCLUSIONS AND IMPLICATIONS

Tan IIA improved gefitinib sensitivity via SREBP1-mediated lipogenesis. Tan IIA could be a potential candidate to enhance sensitivity for gefitinib-resistant NSCLC patients.

Development of fatty acid metabolism score based on gene signature for predicting prognosis and immunotherapy response in colon cancer

PURPOSE

Metabolic reprogramming is a novel hallmark and therapeutic target of cancer. Our study aimed to establish fatty acid metabolism-associated scores based on gene signature and investigated its effects on immunotherapy in colon cancer.

METHODS

Gene expression and clinical information were collected from Gene Expression Omnibus (GEO) database to identify a gene signature by non-negative matrix factorization (NMF) clustering and Cox regression analysis. Subsequently, we constructed the fatty acid metabolism score (FA-score) model by principal component analysis (PCA) and explored its relativity of prognosis and the response to immunotherapy in colon cancer. Finally, the Cancer Genome Atlas (TCGA) database was introduced and in vitro study was performed for verification.

RESULTS

The FA-score-high group had a higher level of fatty acid metabolism and was associated with worse patient overall survival. Significantly, FA-score correlated closely with the biomarkers of immunotherapy, and the FA-score-high group had a poorer therapeutic efficacy of immune checkpoint blockade. In vitro experiments demonstrated that ACSL5 may be a critical metabolic regulatory target.

CONCLUSIONS

Our study provided a comprehensive analysis of the heterogeneity of fatty acid metabolism in colon cancer. We highlighted the potential clinical utility of fatty acid metabolism-related genes to be biomarkers of colon cancer prognosis and targets to improve the effect of immunotherapy.

Fatty acid synthase (FASN) signalome: A molecular guide for precision oncology

The initial excitement generated more than two decades ago by the discovery of drugs targeting fatty acid synthase (FASN)-catalyzed de novo lipogenesis for cancer therapy was short-lived. However, the advent of the first clinical-grade FASN inhibitor (TVB-2640; denifanstat), which is currently being studied in various phase II trials, and the exciting advances in understanding the FASN signalome are fueling a renewed interest in FASN-targeted strategies for the treatment and prevention of cancer. Here, we provide a detailed overview of how FASN can drive phenotypic plasticity and cell fate decisions, mitochondrial regulation of cell death, immune escape and organ-specific metastatic potential. We then present a variety of FASN-targeted therapeutic approaches that address the major challenges facing FASN therapy. These include limitations of current FASN inhibitors and the lack of precision tools to maximize the therapeutic potential of FASN inhibitors in the clinic. Rethinking the role of FASN as a signal transducer in cancer pathogenesis may provide molecularly driven strategies to optimize FASN as a long-awaited target for cancer therapeutics.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Inside anticancer therapy resistance and metastasis. Focus on CD36

Despite recent advances in targeted cancer therapies, drug resistance remains an important setback in tumor control. Understanding the complex mechanisms involved in both innate and acquired drug resistance represents the first step in discovering novel therapeutic agents. Because of its importance in tumorigenesis, progression, and metastasis, lipid metabolism is increasingly garnering attention. CD36 is a membrane receptor at the top of the signaling cascade that transports lipids. Its expression has been repeatedly presented as an unfavorable prognostic factor for various tumor types, raising the question: could CD36 be a critical factor in cancer treatment resistance? In our review, we set out to explore the most prominent studies on the implication of CD36 in resistance to platinum-based drugs and other adjuvant cancer therapies in solid and haematological neoplasia. Moreover, we provide an overview of the latest anti-CD36 cancer therapies, thus opening new perspectives for future personalized medicine.

Exploring the Influence of the Selected Conjugated Fatty Acids Isomers and Cancerous Process on the Fatty Acids Profile of Spleen

The spleen, traditionally associated with blood filtration and immune surveillance, has recently been recognized for its role in systemic lipid metabolism and potential influence on cancer development and progression. This study investigates effects of dietary supplements, specifically conjugated linolenic acids from pomegranate seed oil and bitter melon extract, on the fatty acid (FA) composition of the spleen in the context of cancerous processes. Advanced methods, including gas chromatography-mass spectrometry and silver ion-impregnated high-performance liquid chromatography, were employed to analyze the spleen's FA profile. Our research uncovered that dietary supplementation leads to alterations in the spleen's FA profile, especially under the carcinogenic influence of 7,12-dimethylbenz[a]anthracene. These changes did not align with a simple protective or anti-carcinogenic pattern, as previously suggested in in vitro studies. We observed shifts in conjugated FA isomer concentrations and variations in desaturase activities, suggesting disrupted lipid metabolism in cancerous conditions. The findings underscore the spleen's vital role in lipid metabolism within the body's systemic health framework, highlighting the complexity of dietary supplements' impact on FA profiles in the spleen and their potential implications in cancer progression and treatment. This study adds valuable insight into the complex interplay between diet, disease, and metabolic regulation, particularly in cancerous environments.

Highly Reproducible Quantitative Proteomics Analysis of Pancreatic Cancer Cells Reveals Proteome-Level Effects of a Novel Combination Drug Therapy That Induces Cancer Cell Death via Metabolic Remodeling and Activation of the Extrinsic Apoptosis Pathway

Pancreatic cancer patients have poor survival rates and are frequently treated using gemcitabine (Gem). However, initial tumor sensitivity often gives way to rapid development of resistance. Gem-based drug combinations are employed to increase efficacy and mitigate resistance, but our understanding of molecular-level drug interactions, which could assist in the development of more effective therapeutic regimens, is limited. Global quantitative proteomic analysis could provide novel mechanistic insights into drug combination interactions, but it is challenging to achieve high-quality quantitative proteomics analysis of the large sample sets that are typically required for drug combination studies. Here, we investigated molecular-level temporal interactions of Gem with BGJ398 (infigratinib), a recently approved pan-FGFR inhibitor, in multiple treatment groups (N = 42 samples) using IonStar, a robust large-scale proteomics method that employs well-controlled, ultrahigh-resolution MS1 quantification. A total of 5514 proteins in the sample set were quantified without missing data, requiring >2 unique peptides/protein, <1% protein false discovery rate (FDR), <0.1% peptide FDR, and CV < 10%. Functional analysis of the differentially altered proteins revealed drug-dysregulated processes such as metabolism, apoptosis, and antigen presentation pathways. These changes were validated experimentally using Seahorse metabolic assays and immunoassays. Overall, in-depth analysis of large-scale proteomics data provided novel insights into possible mechanisms by which FGFR inhibitors complement and enhance Gem activity in pancreatic cancers.

The Lipid Metabolism as Target and Modulator of BOLD-100 Anticancer Activity: Crosstalk with Histone Acetylation

The leading first-in-class ruthenium-complex BOLD-100 currently undergoes clinical phase-II anticancer evaluation. Recently, BOLD-100 is identified as anti-Warburg compound. The present study shows that also deregulated lipid metabolism parameters characterize acquired BOLD-100-resistant colon and pancreatic carcinoma cells. Acute BOLD-100 treatment reduces lipid droplet contents of BOLD-100-sensitive but not -resistant cells. Despite enhanced glycolysis fueling lipid accumulation, BOLD-100-resistant cells reveal diminished lactate secretion based on monocarboxylate transporter 1 (MCT1) loss mediated by a frame-shift mutation in the MCT1 chaperone basigin. Glycolysis and lipid catabolism converge in the production of protein/histone acetylation substrate acetyl-coenzymeA (CoA). Mass spectrometric and nuclear magnetic resonance analyses uncover spontaneous cell-free BOLD-100-CoA adduct formation suggesting acetyl-CoA depletion as mechanism bridging BOLD-100-induced lipid metabolism alterations and histone acetylation-mediated gene expression deregulation. Indeed, BOLD-100 treatment decreases histone acetylation selectively in sensitive cells. Pharmacological targeting confirms histone de-acetylation as central mode-of-action of BOLD-100 and metabolic programs stabilizing histone acetylation as relevant Achilles' heel of acquired BOLD-100-resistant cell and xenograft models. Accordingly, histone gene expression changes also predict intrinsic BOLD-100 responsiveness. Summarizing, BOLD-100 is identified as epigenetically active substance acting via targeting several onco-metabolic pathways. Identification of the lipid metabolism as driver of acquired BOLD-100 resistance opens novel strategies to tackle therapy failure.

Adipose tissue‑derived extracellular vesicles: Systemic messengers in health and disease (Review)

Adipose tissue (AT) is a complicated metabolic organ consisting of a heterogeneous population of cells that exert wide‑ranging effects on the regulation of systemic metabolism and in maintaining metabolic homeostasis. Various obesity‑related complications are associated with the development of dysfunctional AT. As an essential transmitter of intercellular information, extracellular vesicles (EVs) have recently been recognized as crucial in regulating multiple physiological functions. AT‑derived extracellular vesicles (ADEVs) have been shown to facilitate cellular communication both inside and between ATs and other peripheral organs. Here, the role of EVs released from ATs in the homeostasis of metabolic and cardiovascular diseases, cancer, and neurological disorders by delivering lipids, proteins, and nucleic acids between different cells is summarized. Furthermore, the differences in the sources of ADEVs, such as adipocytes, AT macrophages, AT‑derived stem cells, and AT‑derived mesenchymal stem cells, are also discussed. This review may provide valuable information for the potential application of ADEVs in metabolic syndrome, cardiovascular diseases, cancer, and neurological disorders.

Fatty acid synthase as a new therapeutic target for HER2-positive gastric cancer

PURPOSE

Trastuzumab is an HER2-specific agent approved as the gold-standard therapy for advanced HER2-positive (HER2+) gastric cancer (GC), but the high rate and rapid appearance of resistance limit its clinical efficacy, resulting in the need to identify new vulnerabilities. Defining the drivers influencing HER2+ cancer stem cell (CSC) maintenance/survival could represent a clinically useful strategy to counteract tumor growth and therapy resistance. Accumulating evidence show that targeting crucial metabolic hubs, as the fatty acid synthase (FASN), may be clinically relevant.

METHODS

FASN protein and transcript expression were examined by WB and FACS and by qRT-PCR and GEP analyses, respectively, in trastuzumab-sensitive and trastuzumab-resistant HER2+ GC cell lines cultured in adherent (2D) or gastrosphere promoting (3D) conditions. Molecular data were analyzed in silico in public HER2+ GC datasets. The effectiveness of the FASN inhibitor TVB3166 to overcome anti-HER2 therapy resistance was tested in vitro in gastrospheres forming efficiency bioassays and in vivo in mice bearing trastuzumab-resistant GC cells.

RESULTS

We compared the transcriptome profiles of HER2+ GC cells cultured in 2D versus 3D conditions finding a significant enrichment of FASN in 3D cultures. FASN upregulation significantly correlated with high stemness score and poor prognosis in HER2+ GC cases. TVB3166 treatment significantly decreased GCSCs in all cell targets. HER2 and FASN cotargeting significantly decreased the capability to form gastrospheres versus monotherapy and reduced the in vivo growth of trastuzumab-resistant GC cells.

CONCLUSION

Our findings indicate that cotargeting HER2 and FASN increase the benefit of anti-HER2 therapy representing a new opportunity for metabolically combating trastuzumab-resistant HER2+ GC.

Investigation of fatty acid metabolism-related genes in breast cancer: Implications for Immunotherapy and clinical significance

Breast cancer (BRCA) is a major global health issue, characterized by high mortality and low early diagnosis rates. The tumor immune microenvironment (TME) of BRCA is closely linked to fatty acid metabolism (FAM). This study aimed to identify FAM-related subtypes in BRCA based on gene expression and clinical data from the Cancer Genome Atlas (TCGA) database. The study found two distinct FAM-related subtypes, each with unique immune characteristics and prognostic implications. A FAM-related risk score prognostic model was developed and validated using TCGA and International Cancer Genome Consortium (GEO) cohorts, showing potential clinical applications for chemotherapy and immunotherapy. Additionally, a nomogram was established to facilitate clinical use of the risk score. These results highlight the significant correlation between FAM genes and TME in BRCA, and demonstrate the potential clinical utility of the FAM-related risk score in informing treatment decisions for BRCA patients.

Therapeutic strategies targeting metabolic characteristics of cancer cells

Metabolic reprogramming is one of the important characteristics of cancer and is a key process leading to malignant proliferation, tumor development and treatment resistance. A variety of therapeutic drugs targeting metabolic reaction enzymes, transport receptors, and special metabolic processes have been developed. In this review, we investigate the characteristics of multiple metabolic changes in cancer cells, including glycolytic pathways, lipid metabolism, and glutamine metabolism changes, describe how these changes promote tumor development and tumor resistance, and summarize the progress and challenges of therapeutic strategies targeting various links of tumor metabolism in combination with current study data.

Nobiletin inhibits de novo FA synthesis to alleviate gastric cancer progression by regulating endoplasmic reticulum stress

BACKGROUND

Gastric cancer (GC) is a common malignant tumor with limited treatment options. The natural flavonoid nobiletin (NOB) is a beneficial antioxidant that possesses anticancer activity. However, the mechanisms by which NOB inhibits GC progression remain unclear.

METHODS

A CCK-8 assay was performed to determine cytotoxicity. Cell cycle and apoptosis analyses were performed by flow cytometry. RNA-seq was performed to detect differential gene expression after NOB treatment. RT‒qPCR, Western blot and immunofluorescence staining were used to examine the underlying mechanisms of NOB in GC. Xenograft tumor models were constructed to verify the effect of NOB and its specific biological mechanism in GC.

RESULTS

NOB inhibited cell proliferation, caused cell cycle arrest and induced apoptosis in GC cells. KEGG classification identified that the inhibitory effect of NOB on GC cells mainly involved the lipid metabolism pathway. We further showed that NOB reduced de novo fatty acid (FA) synthesis, as evidenced by the decreased levels of neutral lipids and the expression levels of ACLY, ACACA and FASN, and ACLY abrogated the effect of NOB on lipid deposits in GC cells. In addition, we also found that NOB triggered endoplasmic reticulum (ER) stress by activating the IRE-1α/GRP78/CHOP axis, but overexpression of ACLY reversed ER stress. Mechanistically, inhibiting ACLY expression with NOB significantly reduced neutral lipid accumulation, thereby inducing apoptosis by activating IRE-1α-mediated ER stress and inhibiting GC cell progression. Finally, in vivo results also demonstrated that NOB inhibited tumor growth by decreasing de novo FA synthesis.

CONCLUSION

NOB could inhibit the expression of ACLY to activate IRE-1α-induced ER stress, which ultimately led to GC cell apoptosis. Our results provide novel insight into the use of de novo FA synthesis for GC treatment and are the first to reveal that NOB inhibits GC progression by ACLY-dependent ER stress.

Targeting Mitochondrial Metabolic Reprogramming as a Potential Approach for Cancer Therapy

Abnormal energy metabolism is a characteristic of tumor cells, and mitochondria are important components of tumor metabolic reprogramming. Mitochondria have gradually received the attention of scientists due to their important functions, such as providing chemical energy, producing substrates for tumor anabolism, controlling REDOX and calcium homeostasis, participating in the regulation of transcription, and controlling cell death. Based on the concept of reprogramming mitochondrial metabolism, a range of drugs have been developed to target the mitochondria. In this review, we discuss the current progress in mitochondrial metabolic reprogramming and summarized the corresponding treatment options. Finally, we propose mitochondrial inner membrane transporters as new and feasible therapeutic targets.

STAT proteins in cancer: orchestration of metabolism

Reprogrammed metabolism is a hallmark of cancer. However, the metabolic dependency of cancer, from tumour initiation through disease progression and therapy resistance, requires a spectrum of distinct reprogrammed cellular metabolic pathways. These pathways include aerobic glycolysis, oxidative phosphorylation, reactive oxygen species generation, de novo lipid synthesis, fatty acid β-oxidation, amino acid (notably glutamine) metabolism and mitochondrial metabolism. This Review highlights the central roles of signal transducer and activator of transcription (STAT) proteins, notably STAT3, STAT5, STAT6 and STAT1, in orchestrating the highly dynamic metabolism not only of cancer cells but also of immune cells and adipocytes in the tumour microenvironment. STAT proteins are able to shape distinct metabolic processes that regulate tumour progression and therapy resistance by transducing signals from metabolites, cytokines, growth factors and their receptors; defining genetic programmes that regulate a wide range of molecules involved in orchestration of metabolism in cancer and immune cells; and regulating mitochondrial activity at multiple levels, including energy metabolism and lipid-mediated mitochondrial integrity. Given the central role of STAT proteins in regulation of metabolic states, they are potential therapeutic targets for altering metabolic reprogramming in cancer.

Obesity promotes radioresistance through SERPINE1-mediated aggressiveness and DNA repair of triple-negative breast cancer

Obesity is a risk factor in various types of cancer, including breast cancer. The disturbance of adipose tissue in obesity highly correlates with cancer progression and resistance to standard treatments such as chemo- and radio-therapies. In this study, in a syngeneic mouse model of triple-negative breast cancer (TNBC), diet-induced obesity (DIO) not only promoted tumor growth, but also reduced tumor response to radiotherapy. Serpine1 (Pai-1) was elevated in the circulation of obese mice and was enriched within tumor microenvironment. In vitro co-culture of human white adipocytes-conditioned medium (hAd-CM) with TNBC cells potentiated the aggressive phenotypes and radioresistance of TNBC cells. Moreover, inhibition of both cancer cell autonomous and non-autonomous SERPINE1 by either genetic or pharmacological strategy markedly dampened the aggressive phenotypes and radioresistance of TNBC cells. Mechanistically, we uncovered a previously unrecognized role of SERPINE1 in DNA damage response. Ionizing radiation-induced DNA double-strand breaks (DSBs) increased the expression of SERPINE1 in cancer cells in an ATM/ATR-dependent manner, and promoted nuclear localization of SERPINE1 to facilitate DSB repair. By analyzing public clinical datasets, higher SERPINE1 expression in TNBC correlated with patients' BMI as well as poor outcomes. Elevated SERPINE1 expression and nuclear localization were also observed in radioresistant breast cancer cells. Collectively, we reveal a link between obesity and radioresistance in TNBC and identify SERPINE1 to be a crucial factor mediating obesity-associated tumor radioresistance.

Smarcd3 is an epigenetic modulator of the metabolic landscape in pancreatic ductal adenocarcinoma

Pancreatic cancer is characterized by extensive resistance to conventional therapies, making clinical management a challenge. Here we map the epigenetic dependencies of cancer stem cells, cells that preferentially evade therapy and drive progression, and identify SWI/SNF complex member SMARCD3 as a regulator of pancreatic cancer cells. Although SWI/SNF subunits often act as tumor suppressors, we show that SMARCD3 is amplified in cancer, enriched in pancreatic cancer stem cells and upregulated in the human disease. Diverse genetic mouse models of pancreatic cancer and stage-specific Smarcd3 deletion reveal that Smarcd3 loss preferentially impacts established tumors, improving survival especially in context of chemotherapy. Mechanistically, SMARCD3 acts with FOXA1 to control lipid and fatty acid metabolism, programs associated with therapy resistance and poor prognosis in cancer. These data identify SMARCD3 as an epigenetic modulator responsible for establishing the metabolic landscape in aggressive pancreatic cancer cells and a potential target for new therapies.

Development of fatty acid metabolism-related models in lung adenocarcinomaA Review

BACKGROUD

Lung adenocarcinoma (LUAD) is 1 of the common malignancy with a poor prognosis.

MATERIALS AND METHODS

Based on bioinformatics, the fatty acid metabolism model of LUAD was developed. We downloaded LUAD transcriptome data from the cancer genome atlas and gene expression omnibus databases. We used bioinformatics methods to construct a fatty acid metabolism-related predictive risk model to predict the prognosis of LUAD. We further explored the relationship between prognostic models and survival and immunity.

RESULTS

We identified 17 prognosis-related fatty acid-associated genes and constructed prognostic models. In the the cancer genome atlas cohort, the prognosis was worse in the high-risk score group compared to the low-risk score group. The ROC curve confirmed its accuracy. Subsequently, we used the gene expression omnibus database to confirm the above findings. There were differences in immune infiltrating cell abundance and immune function between the high-risk score group and low-risk score group. The immune dysfunction and exclusion (TIDE) based algorithm showed that the low-risk score group was more suitable for the immune treatment.

CONCLUSION

Fatty acid metabolic patterns can deepen the understanding of the immune microenvironment of LUAD and be used to guide the formulation of immunotherapy protocols.

The prognostic role of fatty acid metabolism-related genes in patients with gastric cancer

BACKGROUND

With the deepening research on fatty acid metabolism, people have achieved a preliminary understanding of it in the development and prognosis of tumors. However, few studies are still on the expression pattern and prognostic value of fatty acid metabolism-related genes in gastric cancer (GC).

METHODS

We chose 93 genes relevant to fatty acid metabolism from the Gene Set Enrichment Analysis (GSEA) database. We analyzed differentially expressed genes (DEGs) in The Cancer Genome Atlas (TCGA) patients. Univariate Cox analysis and LASSO regression were used to select the genes most related to prognosis and therefore developed a prognosis model. In addition, a dataset of 76 samples from Gene Expression Omnibus (GEO) selected as a test set to aid in the development of a prognostic model. The prognostic relevance of this model was confirmed using Kaplan-Meier survival analysis, univariate/multivariate Cox analysis, and receiver operating characteristic (ROC) curve. Finally, enrichment analysis and protein-protein interaction (PPI) were used to analyze the functional differences of patients with different risk. Immune infiltration analysis based on CIBERSORT could check the infiltration degree and immune function changes of immune cell subtypes in patients with different risk groups.

RESULTS

Overexpression of ELOVL4, ADH4, CPT1C, and ADH1B was linked to poor overall survival (OS) in GC patients, according to our findings. Furthermore, according to prognostic factors, patients with lower risk score tend to have better prognosis than patients with higher risk score. In addition, we also found that the infiltration levels of B cells, dendritic cells, auxiliary T cells, mast cells, neutrophils and tumor-infiltrating lymphocytes in patients with high-risk group were significantly increased, and the type II IFN response of immune cells, CCR and MHC class I receptor functions were significantly enhanced, suggesting that the tumor microenvironment immune activity in patients with high-risk group was active.

CONCLUSIONS

Four fatty acid metabolism-related genes were discovered to be closely connected to the prognosis of individuals with GC. Through analysis and verification, we believed that this prognostic model was reliable and instructive in the prediction of the prognosis of GC.

Construction of a prognostic model of colon cancer patients based on metabolism-related lncRNAs

Background

Many studies have shown that metabolism-related lncRNAs may play an important role in the pathogenesis of colon cancer. In this study, a prognostic model for colon cancer patients was constructed based on metabolism-related lncRNAs.

Methods

Both transcriptome data and clinical data of colon cancer patients were downloaded from the TCGA database, and metabolism-related genes were downloaded from the GSEA database. Through differential expression analysis and Pearson correlation analysis, long non-coding RNAs (lncRNAs) related to colon cancer metabolism were obtained. CRC patients were divided into training set and verification set at the ratio of 2:1. Based on the training set, univariate Cox regression analysis was utilized to determine the prognostic differential expression of metabolic-related lncRNAs. The Optimal lncRNAs were obtain by Lasso regression analysis, and a risk model was built to predict the prognosis of CRC patients. Meanwhile, patients were divided into high-risk and low-risk groups and a survival curve was drawn accordingly to determine whether the survival rate differs between the two groups. At the same time, subgroup analysis evaluated the predictive performance of the model. We combined clinical indicators with independent prognostic significance and risk scores to construct a nomogram. C index and the calibration curve, DCA clinical decision curve and ROC curve were obtained as well. The above results were all verified using the validation set. Finally, based on the CIBERSORT analysis method, the correlation between lncRNAs and 22 tumor-infiltrated lymphocytes was explored.

Results

By difference analysis, 2491 differential lncRNAs were obtained, of which 226 were metabolic-related lncRNAs. Based on Cox regression analysis and Lasso results, a multi-factor prognostic risk prediction model with 13 lncRNAs was constructed. Survival curve results suggested that patients with high scores and have a poorer prognosis than patients with low scores (P<0.05). The area under the ROC curve (AUC) for the 3-year survival and 5-year survival were 0.768 and 0.735, respectively. Cox regression analysis showed that age, distant metastasis and risk scores can be used as independent prognostic factors. Then, a nomogram including age, distant metastasis and risk scores was built. The C index was 0.743, and the ROC curve was drawn to obtain the AUC of the 3-year survival and the 5-year survival, which were 0.802 and 0.832, respectively. The above results indicated that the nomogram has a good predictive effect. Enrichment analysis of KEGG pathway revealed that differential lncRNAs may be related to chemokines, amino acid and sugar metabolism, NOD-like receptor and Toll-like receptor activation as well as other pathways. Finally, the analysis results based on the CIBERSORT algorithm showed that the lncRNAs used to construct the model had a strong polarized correlation with B cells, CD8+T cells and M0 macrophages.

Conclusion

13 metabolic-related lncRNAs affecting the prognosis of CRC were screened by bioinformatics methods, and a prognostic risk model was constructed, laying a solid foundation for the research of metabolic-related lncRNAs in CRC.

TIAM2 Contributes to Osimertinib Resistance, Cell Motility, and Tumor-Associated Macrophage M2-like Polarization in Lung Adenocarcinoma

Background: Osimertinib-based therapy effectively improves the prognosis of lung adenocarcinoma (LUAD) patients with epidermal growth factor receptor mutations. However, patients will have cancer progression after approximately one year due to the occurrence of drug resistance. Extensive evidence has revealed that lipid metabolism and tumor-associated macrophage (TAM) are associated with drug resistance, which deserves further exploration. Methods: An osimertinib resistance index (ORi) was built to investigate the link between lipid metabolism and osimertinib resistance. The ORi was constructed and validated using TCGA and GEO data, and the relationship between ORi and immune infiltration was discussed. Weighted gene co-expression network analysis based on the M2/M1 macrophage ratio determined the hub gene TIAM2 and the biological function of TIAM2 in LUAD was verified in vitro. Results: ORi based on nine lipid metabolism-related genes was successfully constructed, which could accurately reflect the resistance of LUAD patients to osimertinib, predict the prognosis, and correlate with M2-like TAM. Additionally, TIAM2 was found to increase osimertinib tolerance, enhance cell motility, and promote M2-like TAM polarization in LUAD. Conclusions: The lipid metabolism gene is strongly connected with osimertinib resistance. TIAM2 contributes to osimertinib resistance, enhances cell motility, and induces M2-like TAM polarization in LUAD.

Purinergic receptors are a key bottleneck in tumor metabolic reprogramming: The prime suspect in cancer therapeutic resistance

ATP and other nucleoside phosphates have specific receptors named purinergic receptors. Purinergic receptors and ectonucleotidases regulate various signaling pathways that play a role in physiological and pathological processes. Extracellular ATP in the tumor microenvironment (TME) has a higher level than in normal tissues and plays a role in cancer cell growth, survival, angiogenesis, metastasis, and drug resistance. In this review, we investigated the role of purinergic receptors in the development of resistance to therapy through changes in tumor cell metabolism. When a cell transforms to neoplasia, its metabolic processes change. The metabolic reprogramming modified metabolic feature of the TME, that can cause impeding immune surveillance and promote cancer growth. The purinergic receptors contribute to therapy resistance by modifying cancer cells' glucose, lipid, and amino acid metabolism. Limiting the energy supply of cancer cells is one approach to overcoming resistance. Glycolysis inhibitors which reduce intracellular ATP levels may make cancer cells more susceptible to anti-cancer therapies. The loss of the P2X7R through glucose intolerance and decreased fatty acid metabolism reduces therapeutic resistance. Potential metabolic blockers that can be employed in combination with other therapies will aid in the discovery of new anti-cancer immunotherapy to overcome therapy resistance. Therefore, therapeutic interventions that are considered to inhibit cancer cell metabolism and purinergic receptors simultaneously can potentially reduce resistance to treatment.

Title: Involvement of unsaturated fatty acid biosynthesis in CRC progression based on in vitro and in silico studies

Obesity is one of the risk factors concerns of colorectal cancer (CRC), the most common type of gastrointestinal cancer, due to the changing lifestyle and especially diet. There are various molecular pathways associated with obesity and the risk of CRC incidence, such as insulin resistance or elevated plasma free fatty acids, which alter the signaling pathways of intestinal epithelial cells. The aim of this study was to better understand the significance of unsaturated fatty acid biosynthesis on pathogenesis of colon cancer in obese. Based on GSE20931 dataset, obese individuals affected by CRC had higher increased gene expression than non-obese individuals. The analysis showed that in obese individuals, the 16 signaling pathway genes were activated and increased (FDR <0.05) significantly. The biosynthetic pathway of unsaturated fatty acids showed a cross-talk with the arachidonic acid metabolism pathway and the PPAR signaling pathway is influenced and regulated via these pathways. The biosynthetic pathway of unsaturated fatty acids consisting of 22 genes, were analyzed using GEO data and revealed that 4 genes (HSD17B12, TECR, FADS2, ELOVL5) from this pathway were significantly increased (FDR <0.05). These data were validated based on TCGA data (Adj.p.value <0.001). The expression level of candidate genes in HT-29 cells decreased significantly (P.value <0.01), and PPARγ expression increased under linoleic acid treatment (200 μM) compared to control cells. Moreover, in presence of linoleic acid treatment, migration, colony formation, and proliferation decreased (P.value <0.01) in presence of treatment. In summary, the Biosynthesis pathway of unsaturated fatty acids is an interesting and critical pathway in CRC.

Fatty acids of type 2 diabetic serum decrease the stemness properties of human adipose-derived mesenchymal stem cells

In type 2 diabetes, dyslipidemia and increased serum free fatty acids (FFAs) exacerbate the development of the disease through a negative effect on insulin secretion. Adipose-derived mesenchymal stem cells (AdMSCs) play a key role in regenerative medicine, and these cells can potentially be applied as novel therapeutic resources in the treatment of diabetes. In this study, AdMSCs were treated with diabetic or nondiabetic serum FFAs isolated from women of menopausal age. Serum FFAs were analyzed using gas-liquid chromatography. The expression level of the stemness markers CD49e and CD90 and the Wnt signaling target genes Axin-2 and c-Myc were evaluated using real-time PCR. The proliferation rate and colony formation were also assessed using a BrdU assay and crystal violet staining, respectively. The level of glutathione was assessed using cell fluorescence staining. Compared to nondiabetic serum, diabetic serum contained a higher percentage of oleate (1.5-fold, p < 0.01). In comparison with nondiabetic FFAs, diabetic FFAs demonstrated decreasing effects on the expression of CD90 (-51%, p < 0.001) and c-Myc (-48%, p < 0.05), and proliferation rate (-35%, p < 0.001), colony formation capacity (-50%, p < 0.01), and GSH levels (-62%, p < 0.05). The negative effect of the FFAs of diabetic serum on the stemness characteristics may impair the regenerative capabilities of AdMSCs.

The Role of Lipid Metabolism in Gastric Cancer

Gastric cancer has been one of the most common cancers worldwide with extensive metastasis and high mortality. Chemotherapy has been found as a main treatment for metastatic gastric cancer, whereas drug resistance limits the effectiveness of chemotherapy and leads to treatment failure. Chemotherapy resistance in gastric cancer has a complex and multifactorial mechanism, among which lipid metabolism plays a vital role. Increased synthesis of new lipids or uptake of exogenous lipids can facilitate the rapid growth of cancer cells and tumor formation. Lipids form the structural basis of biofilms while serving as signal molecules and energy sources. It is noteworthy that lipid metabolism is capable of inducing drug resistance in gastric cancer cells by reshaping the tumor micro-environment. In this study, new mechanisms of lipid metabolism in gastric cancer and the metabolic pathways correlated with chemotherapy resistance are reviewed. In particular, we discuss the effects of lipid metabolism on autophagy, biomarkers treatment and drug resistance in gastric cancer from the perspective of lipid metabolism. In brief, new insights can be gained into the development of promising therapies through an in-depth investigation of the mechanism of lipid metabolism reprogramming and resensitization to chemotherapy in gastric cancer cells, and scientific treatment can be provided by applying lipid-key enzyme inhibitors as cancer chemical sensitizers in clinical settings.

Targeting lipid metabolism in the treatment of ovarian cancer

Cancer cells undergo alterations in lipid metabolism to support their high energy needs, tumorigenesis and evade an anti-tumor immune response. Alterations in fatty acid production are controlled by multiple enzymes, chiefly Acetyl CoA Carboxylase, ATP-Citrate Lyase, Fatty Acid Synthase, and Stearoyl CoA Desaturase 1. Ovarian cancer (OC) is a common gynecological malignancy with a high rate of aggressive carcinoma progression and drug resistance. The accumulation of unsaturated fatty acids in ovarian cancer supports cell growth, increased cancer cell migration, and worse patient outcomes. Ovarian cancer cells also expand their lipid stores via increased uptake of lipids using fatty acid translocases, fatty acid-binding proteins, and low-density lipoprotein receptors. Furthermore, increased lipogenesis and lipid uptake promote chemotherapy resistance and dampen the adaptive immune response needed to eliminate tumors. In this review, we discuss the role of lipid synthesis and metabolism in driving tumorigenesis and drug resistance in ovarian cancer conferring poor prognosis and outcomes in patients. We also cover some aspects of how lipids fuel ovarian cancer stem cells, and how these metabolic alterations in intracellular lipid content could potentially serve as biomarkers of ovarian cancer.

The Evasion Mechanisms of Cancer Immunity and Drug Intervention in the Tumor Microenvironment

Recently, in the field of cancer treatment, the paradigm has changed to immunotherapy that activates the immune system to induce cancer attacks. Among them, immune checkpoint inhibitors (ICI) are attracting attention as excellent and continuous clinical results. However, it shows not only limitations such as efficacy only in some patients or some indications, but also side-effects and resistance occur. Therefore, it is necessary to understand the factors of the tumor microenvironment (TME) that affect the efficacy of immunotherapy, that is, the mechanism by which cancer grows while evading or suppressing attacks from the immune system within the TME. Tumors can evade attacks from the immune system through various mechanisms such as restricting antigen recognition, inhibiting the immune system, and inducing T cell exhaustion. In addition, tumors inhibit or evade the immune system by accumulating specific metabolites and signal factors within the TME or limiting the nutrients available to immune cells. In order to overcome the limitations of immunotherapy and develop effective cancer treatments and therapeutic strategies, an approach is needed to understand the functions of cancer and immune cells in an integrated manner based on the TME. In this review, we will examine the effects of the TME on cancer cells and immune cells, especially how cancer cells evade the immune system, and examine anti-cancer strategies based on TME.

Over-Reduced State of Mitochondria as a Trigger of "β-Oxidation Shuttle" in Cancer Cells

A considerable amount of data have accumulated in the last decade on the pronounced mitochondrial fatty acid oxidation (mFAO) in many types of cancer cells. As a result, mFAO was found to coexist with abnormally activated fatty acid synthesis (FAS) and the mevalonate pathway. Recent studies have demonstrated that overactivated mitochondrial β-oxidation may aggravate the impaired mitochondrial redox state and vice versa. Furthermore, the impaired redox state of cancerous mitochondria can ensure the continuous operation of β-oxidation by disconnecting it from the Krebs cycle and connecting it to the citrate-malate shuttle. This could create a new metabolic state/pathway in cancer cells, which we have called the "β-oxidation-citrate-malate shuttle", or "β-oxidation shuttle" for short, which forces them to proliferate. The calculation of the phosphate/oxygen ratio indicates that it is inefficient as an energy source and must consume significantly more oxygen per mole of ATP produced when combined with acetyl-CoA consuming pathways, such as the FAS and mevalonate pathways. The "β-oxidation shuttle" is an unconventional mFAO, a separate metabolic pathway that has not yet been explored as a source of energy, as well as a source of cataplerosis, leading to biomass accumulation, accelerated oxygen consumption, and, ultimately, a source of proliferation. The role of the "β-oxidation shuttle" and its contribution to redox-altered cancer metabolism provides a new direction for the development of future anticancer strategies. This may represent the metabolic "secret" of cancer underlying hypoxia and genomic instability.

A “Weird” Mitochondrial Fatty Acid Oxidation as a Metabolic “Secret” of Cancer

Cancer metabolism is an extensively studied field since the discovery of the Warburg effect about 100 years ago and continues to be increasingly intriguing and enigmatic so far. It has become clear that glycolysis is not the only abnormally activated metabolic pathway in the cancer cells, but the same is true for the fatty acid synthesis (FAS) and mevalonate pathway. In the last decade, a lot of data have been accumulated on the pronounced mitochondrial fatty acid oxidation (mFAO) in many types of cancer cells. In this article, we discuss how mFAO can escape normal regulation under certain conditions and be overactivated. Such abnormal activation of mitochondrial β-oxidation can also be combined with mutations in certain enzymes of the Krebs cycle that are common in cancer. If overactivated β-oxidation is combined with other common cancer conditions, such as dysfunctions in the electron transport complexes, and/or hypoxia, this may alter the redox state of the mitochondrial matrix. We propose the idea that the altered mitochondrial redox state and/or inhibited Krebs cycle at certain segments may link mitochondrial β-oxidation to the citrate-malate shuttle instead to the Krebs cycle. We call this abnormal metabolic condition “β-oxidation shuttle”. It is unconventional mFAO, a separate metabolic pathway, unexplored so far as a source of energy, as well as a source of cataplerosis, leading to biomass accumulation, accelerated oxygen consumption, and ultimately a source of proliferation. It is inefficient as an energy source and must consume significantly more oxygen per mole of ATP produced when combined with acetyl-CoA consuming pathways, such as the FAS and mevalonate pathway.

Active mitochondrial respiration in cancer: a target for the drug

The relative contribution of mitochondrial respiration and subsequent energy production in malignant cells has remained controversial to date. Enhanced aerobic glycolysis and impaired mitochondrial respiration have gained more attention in the metabolic study of cancer. In contrast to the popular concept, mitochondria of cancer cells oxidize a diverse array of metabolic fuels to generate a majority of the cellular energy by respiration. Several mitochondrial respiratory chain (MRC) subunits' expressions are critical for the growth, metastasis, and cancer cell invasion. Also, the assembly factors, which regulate the integration of individual MRC complexes into native super-complexes, are upregulated in cancer. Moreover, a series of anti-cancer drugs function by inhibiting respiration and ATP production. In this review, we have specified the roles of mitochondrial fuels, MRC subunits, and super-complex assembly factors that promote active respiration across different cancer types and discussed the potential roles of MRC inhibitor drugs in controlling cancer.

Aberrant lipid metabolism in cancer cells and tumor microenvironment: the player rather than bystander in cancer progression and metastasis

As the primary cause of cancer-induced fatality and morbidity, cancer metastasis has been a hard nut to crack. Existing studies indicate that lipid metabolism reprogramming occurring in cancer cells and surrounding cells in TME also endows the aggressive and spreading properties with malignant cells. In this review we describe the lipid metabolic reprogramming of cancer cells at different steps along the metastatic process, we also summarize the altered lipid metabolism of non-cancer cells in TME during tumor metastasis. Additionally, we reveal both intrinsic and extrinsic factors which influence the cellular lipid metabolism reprogramming.

Adipose Tissue-Breast Cancer Crosstalk Leads to Increased Tumor Lipogenesis Associated with Enhanced Tumor Growth

We sought to identify therapeutic targets for breast cancer by investigating the metabolic symbiosis between breast cancer and adipose tissue. To this end, we compared orthotopic E0771 breast cancer tumors that were in direct contact with adipose tissue with ectopic E0771 tumors in mice. Orthotopic tumors grew faster and displayed increased de novo lipogenesis compared to ectopic tumors. Adipocytes release large amounts of lactate, and we found that both lactate pretreatment and adipose tissue co-culture augmented de novo lipogenesis in E0771 cells. Continuous treatment with the selective FASN inhibitor Fasnall dose-dependently decreased the E0771 viability in vitro. However, daily Fasnall injections were effective only in 50% of the tumors, while the other 50% displayed accelerated growth. These opposing effects of Fasnall in vivo was recapitulated in vitro; intermittent Fasnall treatment increased the E0771 viability at lower concentrations and suppressed the viability at higher concentrations. In conclusion, our data suggest that adipose tissue enhances tumor growth by stimulating lipogenesis. However, targeting lipogenesis alone can be deleterious. To circumvent the tumor's ability to adapt to treatment, we therefore believe that it is necessary to apply an aggressive treatment, preferably targeting several metabolic pathways simultaneously, together with conventional therapy.

Epigenetic interplay between methylation and miRNA in bladder cancer: focus on isoform expression

BACKGROUND

Various epigenetic factors are responsible for the non-genetic regulation on gene expression. The epigenetically dysregulated oncogenes or tumor suppressors by miRNA and/or DNA methylation are often observed in cancer cells. Each of these epigenetic regulators has been studied well in cancer progressions; however, their mutual regulatory relationship in cancer still remains unclear. In this study, we propose an integrative framework to systematically investigate epigenetic interactions between miRNA and methylation at the alternatively spliced mRNA level in bladder cancer. Each of these epigenetic regulators has been studied well in cancer progressions; however, their mutual regulatory relationship in cancer still remains unclear.

RESULTS

The integrative analyses yielded 136 significant combinations (methylation, miRNA and isoform). Further, overall survival analysis on the 136 combinations based on methylation and miRNA, high and low expression groups resulted in 13 combinations associated with survival. Additionally, different interaction patterns were examined.

CONCLUSIONS

Our study provides a higher resolution of molecular insight into the crosstalk between two epigenetic factors, DNA methylation and miRNA. Given the importance of epigenetic interactions and alternative splicing in cancer, it is timely to identify and understand the underlying mechanisms based on epigenetic markers and their interactions in cancer, leading to alternative splicing with primary functional impact.

Adipokine Apelin/APJ Pathway Promotes Peritoneal Dissemination of Ovarian Cancer Cells by Regulating Lipid Metabolism

Adipose tissue, which can provide adipokines and nutrients to tumors, plays a key role in promoting ovarian cancer metastatic lesions in peritoneal cavity. The adipokine apelin promotes ovarian cancer metastasis and progression through its receptor APJ, which regulates cell proliferation, energy metabolism, and angiogenesis. The objective of this study was to investigate the functional role and mechanisms of the apelin-APJ pathway in ovarian cancer metastasis, especially in context of tumor cell-adipocyte interactions. When co-cultured in the conditioned media (AdipoCM) derived from 3T3-L1 adipocytes, which express and secrete high apelin, human ovarian cancer cells with high APJ expression showed significant increases in migration and invasion in vitro. We also found that cells expressing high levels of APJ had increased cell adhesion to omentum ex vivo, and preferentially "home-in" on the omentum in vivo. These apelin-induced pro-metastatic effects were reversed by APJ antagonist F13A in a dose-dependent manner. Apelin-APJ activation increased lipid droplet accumulation in ovarian cancer cells, which was further intensified in the presence of AdipoCM and reversed by F13A or APJ knockdown. Mechanistically, this increased lipid uptake was mediated by CD36 upregulation via APJ-STAT3 activation, and the lipids were utilized in promoting fatty acid oxidation via activation of AMPK-CPT1a axis. Together, our studies demonstrate that adipocyte-derived apelin activates APJ-expressing tumor cells in a paracrine manner, promoting lipid uptake and utilization and providing energy for ovarian cancer cell survival at the metastatic sites. Hence, the apelin-APJ pathway presents a novel therapeutic target to curb ovarian cancer metastasis. IMPLICATIONS: Targeting the APJ pathway in high-grade serous ovarian carcinoma is a novel strategy to inhibit peritoneal metastasis.

Malignant Ascites in Ovarian Cancer: Cellular, Acellular, and Biophysical Determinants of Molecular Characteristics and Therapy Response

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades of evidence showing that the accumulation of peritoneal fluid portends the poorest outcomes for cancer patients, the role of malignant ascites in promoting metastasis and therapy resistance remains poorly understood. This review summarizes the current understanding of malignant ascites, with a focus on ovarian cancer. The first section provides an overview of heterogeneity in ovarian cancer and the pathophysiology of malignant ascites. Next, analytical methods used to characterize the cellular and acellular components of malignant ascites, as well the role of these components in modulating cell biology, are discussed. The review then provides a perspective on the pressures and forces that tumors are subjected to in the presence of malignant ascites and the impact of physical stress on therapy resistance. Treatment options for malignant ascites, including surgical, pharmacological and photochemical interventions are then discussed to highlight challenges and opportunities at the interface of drug discovery, device development and physical sciences in oncology.

Cancer Metabostemness and Metabolic Reprogramming via P2X7 Receptor

The heterogeneity of tumor cell mass and the plasticity of cancer cell phenotypes in solid tumors allow for the insurgence of resistant and metastatic cells, responsible for cancer patients' clinical management's main challenges. Among several factors that are responsible for increased cancer aggression, metabolic reprogramming is recently emerging as an ultimate cancer hallmark, as it is central for cancer cell survival and self-renewal, metastasis and chemoresistance. The P2X7 receptor, whose expression is upregulated in many solid and hematological malignancies, is also emerging as a good candidate in cancer metabolic reprogramming and the regulation of stem cell proliferation and differentiation. Metabostemness refers to the metabolic reprogramming of cancer cells toward less differentiated (CSCs) cellular states, and we believe that there is a strong correlation between metabostemness and P2X7 receptor functions in oncogenic processes. Here, we summarize important aspects of P2X7 receptor functions in normal and tumor tissues as well as essential aspects of its structure, regulation, pharmacology and its clinical use. Finally, we review current knowledge implicating P2X7 receptor functions in cancer-related molecular pathways, in metabolic reprogramming and in metabostemness.

Identification of Hub Genes and Small Molecule Drugs Associated with Acquired Resistance to Gefitinib in Non-Small Cell Lung Cancer

Targeting EGFR, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs), brings lights to the treatment of non-small cell lung cancer (NSCLC). Although T790M mutation responded as one of the main reasons of acquired resistance, still 15% of the resistance patients can't be explained by the known mechanisms. The purpose of this research was to identify some new mechanisms of gefitinib acquired resistance, and to predict small molecules drugs which may reverse drug resistance by integrated bioinformatics analysis. The GSE34228 data package containing the microarray data of acquired gefitinib-resistant cell line (PC9GR) and gefitinib-sensitive cell line (PC9) from the GEO database were downloaded, and gene co-expression networks by weighted gene co-expression network analysis (WGCNA) were constructed to identified key modules and key genes related to gefitinib resistance. Furthermore, the significantly differentially expressed genes (DEGs) between the two cell types were screened out, and a protein-protein interaction (PPI) network to obtain the key genes of DEGs was accordingly constructed. Through the above two methods, 4 hub genes, PI3, S100A8, AXL and PNPLA4 were mined as the most relevant to gefitinib resistance. Among them, PI3, S100A8 were down-regulated in PC9GR cell samples, while AXL, PNPLA4 were up-regulated. The gene set enrichment analysis (GSEA) for single gene showed that the four hub genes were mainly correlated with cell proliferation and cycle. Besides, small molecule drugs with the potential to overcome resistance, such as Emetine and cephaeline, were screened by CMap database. Consistent with this, in vitro experiments results have shown that emetine and cephaeline can increase the sensitivity of drug-resistant cells to gefitinib, and the mechanism may be related to the regulation of PI3 and S100A8. In conclusion, 4 hub genes were found to be related to the occurrence of gefitinib resistance in non-small cell lung cancer, and several small molecule drugs were screened out as potential therapeutic agents to overcome gefitinib resistance, which may lead a new way for the treatment of NSCLC of acquired resistance to gefitinib.

Pieces of the Complex Puzzle of Cancer Cell Energy Metabolism: An Overview of Energy Metabolism and Alternatives for Targeted Cancer Therapy

Over the past decades, several advances in cancer cell biology have led to relevant details about a phenomenon called the 'Warburg effect'. Currently, it has been accepted that the Warburg effect is not compatible with all cancer cells, and thus the process of aerobic glycolysis is now challenged by the knowledge of a large number of cells presenting mitochondrial function. The energy metabolism of cancer cells is focused on the bioenergetic and biosynthetic pathways in order to meet the requirements of rapid proliferation. Changes in the metabolism of carbohydrates, amino acids and lipids have already been reported for cancer cells and this might play an important role in cancer progression. To the best of our knowledge, these changes are mainly attributed to genetic reprogramming which leads to the transformation of a healthy into a cancerous cell. Indeed, several enzymes that are highly relevant for cellular energy are targets of oncogenes (e.g. PI3K, HIF1, and Myc) and tumor suppressor proteins (e.g. p53). As a consequence of extensive studies on cancer cell metabolism, some new therapeutic strategies have appeared that aim to interrupt the aberrant metabolism, in addition to influencing genetic reprogramming in cancer cells. In this review, we present an overview of cancer cell metabolism (carbohydrate, amino acid, and lipid), and also describe oncogenes and tumor suppressors that directly affect the metabolism. We also discuss some of the potential therapeutic candidates which have been designed to target and disrupt the main driving forces associated with cancer cell metabolism and proliferation.

Metabolic alterations mediated by STAT3 promotes drug persistence in CML

Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.