Mitochondria, cholesterol and cancer cell metabolism

Association of metals and bisphenols exposure with lipid profiles and dyslipidemia in Chinese adults: Independent, combined and interactive effects

BACKGROUND

Although studies have assessed the association of metals and bisphenols with lipid metabolism, the observed results have been controversial, and limited knowledge exists about the combined and interactive effects of metals and bisphenols exposure on lipid metabolism.

METHODS

Plasma metals and serum bisphenols concentrations were evaluated in 888 participants. Multiple linear regression and logistic regression models were conducted to assess individual associations of 18 metals and 3 bisphenols with 5 lipid profiles and dyslipidemia risk, respectively. The dose-response relationships of targeted contaminants with lipid profiles and dyslipidemia risk were captured by applying a restriction cubic spline (RCS) function. The bayesian kernel machine regression (BKMR) model was used to assess the overall effects of metals and bisphenols mixture on lipid profiles and dyslipidemia risk. The interactive effects of targeted contaminants on interested outcomes were explored by constructing an interaction model.

RESULTS

Single-contaminant analyses revealed that exposure to iron (Fe), nickel (Ni), copper (Cu), arsenic (As), selenium (Se), strontium (Sr), and tin (Sn) was associated with elevated lipid levels. Cobalt (Co) showed a negative association with high density lipoprotein cholesterol (HDL-C). Bisphenol A (BPA) and bisphenol AF (BPAF) were associated with decreased HDL-C levels, with nonlinear associations observed. Vanadium (V), lead (Pb), and silver (Ag) displayed U-shaped dose-response relationships with most lipid profiles. Multi-contaminant analyses indicated positive trends between contaminants mixture and total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and non-high-density lipoprotein cholesterol (non-HDL-C). The interaction analyses showed that Se-Fe exhibited synergistic effects on LDL-C and non-HDL-C, and Se-Sn showed a synergistic effect on HDL-C.

CONCLUSIONS

Our study suggested that exposure to metals and bisphenols was associated with changes in lipid levels, and demonstrated their combined and interactive effects.

The mechanism and clinical application of farnesyl diphosphate farnesyltransferase 1 in cancer metabolism

Cancer poses a significant risk to human well-being. Among the crucial characteristics of cancer is metabolic reprogramming. To meet the relentless metabolic needs, cancer cells enhance cholesterol metabolism within the adverse tumor microenvironment. Reprograming cholesterol metabolism includes a series of modifications in the synthesis, absorption, esterification, and metabolites associated with cholesterol. These adjustments have a strong correlation with the proliferation, invasion, metastasis, and other characteristics of malignant tumors. FDFT1, also known as farnesyl diphosphate farnesyltransferase 1, is an enzyme crucial in the process of cholesterol biosynthesis. Its significant involvement in tumor metabolism has garnered considerable interest. The significance of FDFT1 in cancer metabolism cannot be overstated, as it actively interacts with cancer cells. This paper aims to analyze and consolidate the mechanism of FDFT1 in cancer metabolism and explore its clinical application. The goal is to contribute new strategies and targets for the prevention and treatment of cancer metabolism.

Dysregulation of cellular membrane homeostasis as a crucial modulator of cancer risk

Cellular membranes serve as an epicentre combining extracellular and cytosolic components with membranous effectors, which together support numerous fundamental cellular signalling pathways that mediate biological responses. To execute their functions, membrane proteins, lipids and carbohydrates arrange, in a highly coordinated manner, into well-defined assemblies displaying diverse biological and biophysical characteristics that modulate several signalling events. The loss of membrane homeostasis can trigger oncogenic signalling. More recently, it has been documented that select membrane active dietaries (MADs) can reshape biological membranes and subsequently decrease cancer risk. In this review, we emphasize the significance of membrane domain structure, organization and their signalling functionalities as well as how loss of membrane homeostasis can steer aberrant signalling. Moreover, we describe in detail the complexities associated with the examination of these membrane domains and their association with cancer. Finally, we summarize the current literature on MADs and their effects on cellular membranes, including various mechanisms of dietary chemoprevention/interception and the functional links between nutritional bioactives, membrane homeostasis and cancer biology.

Targeting NPC1 in Renal Cell Carcinoma

Rapidly proliferating cancer cells have a greater requirement for cholesterol than normal cells. Tumor cells are largely dependent on exogenous lipids given that their growth requirements are not fully met by endogenous pathways. Our current study shows that ccRCC cells have redundant mechanisms of cholesterol acquisition. We demonstrate that all major lipoproteins (i.e., LDL, HDL, and VLDL) have a comparable ability to support the growth of ccRCC cells and are equally effective in counteracting the antitumor activities of TKIs. The intracellular trafficking of exogenous lipoprotein-derived cholesterol appears to be distinct from the movement of endogenously synthesized cholesterol. De novo synthetized cholesterol is transported from the endoplasmic reticulum directly to the plasma membrane and to the acyl-CoA: cholesterol acyltransferase, whereas lipoprotein-derived cholesterol is distributed through the NPC1-dependent endosomal trafficking system. Expression of NPC1 is increased in ccRCC at mRNA and protein levels, and high expression of NPC1 is associated with poor prognosis. Our current findings show that ccRCC cells are particularly sensitive to the inhibition of endolysosomal cholesterol export and underline the therapeutic potential of targeting NPC1 in ccRCC.

4,8-Dicarboxyl-8,9-iridoid-1-glycoside inhibits apoptosis in human osteoarthritis chondrocytes via enhanced c-MYC-mediated cholesterol metabolism in vitro

BACKGROUND

Osteoarthritis (OA) is a degenerative disease related to cholesterol metabolism disorders. However, current therapies for OA are insufficient and no convincing disease-modifying OA drugs exist. Therefore, we aimed to elucidate the mechanism by which borojoa iridoid glycoside (BIG) inhibits chondrocyte apoptosis in OA.

METHODS

Borojoa pulp was heated to 70 °C, and the main active substance in borojoa, BIG, was extracted by fractionation at an ultraviolet 254-nm absorption peak. Chondrocytes were identified by immunohistochemistry and visualized by immunofluorescence confocal microscopy. The proliferation of chondrocytes cultured with BIG was determined by MTS assay. The apoptosis of chondrocytes cultured with BIG was tested by Annexin V-FITC/PI, and the cytokine, protein, and cholesterol levels in chondrocytes were detected by ELISA, RT‒qPCR, Western blot, and biochemistry analyses. Protein‒protein interactions were verified by a coimmunoprecipitation (Co-IP) assay.

RESULTS

BIG promoted chondrocyte proliferation and reduced apoptosis in vitro. BIG induced an alteration of the total RNA profiles in chondrocytes, and bioinformatic analysis showed that BIG inhibited chondrocyte apoptosis by promoting c-MYC expression; KEGG analysis confirmed that BIG-inhibited apoptosis was enriched in the cell cycle pathway. Flow cell cycle experiments confirmed that BIG promoted chondrocyte proliferation by significantly increasing the S phase cell number. The c-MYC inhibitor 10058-F4 stimulated the increased expression of IL-1β, IL-6, TNF-α, and AGEs and suppressed the cholesterol metabolism, which promoted chondrocyte apoptosis and autophagy. Co-IP analysis showed that BIG promoted the interaction of c-MYC and CH25H, Bcl-2, which suggests that BIG could inhibit chondrocyte apoptosis in part by enhancing c-MYC-mediated cholesterol metabolism.

CONCLUSIONS

This study confirmed that BIG promotes chondrocyte proliferation and inhibits apoptosis and autophagy, and BIG improving OA is associated with cholesterol metabolism. The results identify a potential mechanism by which BIG enhances c-MYC-mediated CH25H regulation of cholesterol metabolism in vitro and suggest that BIG might be a promising new drug against OA.

Mitochondrial Functionality Is Regulated by Alkylphospholipids in Human Colon Cancer Cells

Alkylphospholipids (APLs) have been studied as anticancer drugs that interfere with biological membranes without targeting DNA. Although their mechanism of action is not fully elucidated yet, it is known that they disrupt the intracellular trafficking of cholesterol and its metabolism. Here, we analyzed whether APLs could also interfere with mitochondrial function. For this purpose, we used HT29 colorectal cancer cells, derived from a primary tumor, and SW620 colorectal cancer cells, derived from a metastasis site. After treatment with the APLs miltefosine and perifosine, we analyzed various mitochondrial parameters, including mitochondrial mass, cardiolipin content, mitochondrial membrane potential, H2O2 production, the levels of oxidative phosphorylation (OXPHOS) complexes, metabolic enzymes activity, the oxygen consumption rate, and the levels of apoptosis and autophagy markers. APLs, especially perifosine, increased mitochondrial mass while OXPHOS complexes levels were decreased without affecting the total oxygen consumption rate. Additionally, we observed an increase in pyruvate dehydrogenase (PDH) and isocitrate dehydrogenase (IDH) levels and a decrease in lactate dehydrogenase (LDH) activity, suggesting a metabolic rewiring induced by perifosine. These alterations led to higher mitochondrial membrane potential, which was potentiated by decreased uncoupling protein 2 (UCP2) levels and increased reactive oxygen species (ROS) production. Consequently, perifosine induced an imbalance in mitochondrial function, resulting in higher ROS production that ultimately impacted cellular viability.

Orai inhibition modulates pulmonary ILC2 metabolism and alleviates airway hyperreactivity in murine and humanized models

Ca2+ entry via Ca2+ release-activated Ca2+ (CRAC) channels is a predominant mechanism of intracellular Ca2+ elevation in immune cells. Here we show the immunoregulatory role of CRAC channel components Orai1 and Orai2 in Group 2 innate lymphoid cells (ILC2s), that play crucial roles in the induction of type 2 inflammation. We find that blocking or genetic ablation of Orai1 and Orai2 downregulates ILC2 effector function and cytokine production, consequently ameliorating the development of ILC2-mediated airway inflammation in multiple murine models. Mechanistically, ILC2 metabolic and mitochondrial homeostasis are inhibited and lead to the upregulation of reactive oxygen species production. We confirm our findings in human ILC2s, as blocking Orai1 and Orai2 prevents the development of airway hyperreactivity in humanized mice. Our findings have a broad impact on the basic understanding of Ca2+ signaling in ILC2 biology, providing potential insights into the development of therapies for the treatment of allergic and atopic inflammatory diseases.

Is cholesterol a risk factor for breast cancer incidence and outcome?

Cholesterol plays important roles in many physiological processes, including cell membrane structure and function, hormone synthesis, and the regulation of cellular homeostasis. The role of cholesterol in breast cancer is complex, and some studies have suggested that elevated cholesterol levels may be associated with an increased risk of developing breast cancer, while others have found no significant association. On the other hand, other studies have shown that, for total cholesterol and plasma HDL-associated cholesterol levels, there was inverse association with breast cancer risk. One possible mechanism by which cholesterol may contribute to breast cancer risk is as a key precursor of estrogen. Other potential mechanisms by which cholesterol may contribute to breast cancer risk include its role in inflammation and oxidative stress, which have been linked to cancer progression. Cholesterol has also been shown to play a role in signaling pathways regulating the growth and proliferation of cancer cells. In addition, recent studies have shown that cholesterol metabolism can generate tumor promoters such as cholesteryl esters, oncosterone, 27-hydroxycholesterol but also tumor suppressor metabolites such as dendrogenin A. This review summarizes some of the most important clinical studies that have evaluated the role of cholesterol or its derivatives in breast cancer. It also addresses the role of cholesterol and its derivatives at the cellular level.

Exploring the Potent Anticancer Activity of Essential Oils and Their Bioactive Compounds: Mechanisms and Prospects for Future Cancer Therapy

Cancer is one of the leading causes of death worldwide, affecting millions of people each year. Fortunately, the last decades have been marked by considerable advances in the field of cancer therapy. Researchers have discovered many natural substances, some of which are isolated from plants that have promising anti-tumor activity. Among these, essential oils (EOs) and their constituents have been widely studied and shown potent anticancer activities, both in vitro and in vivo. However, despite the promising results, the precise mechanisms of action of EOs and their bioactive compounds are still poorly understood. Further research is needed to better understand these mechanisms, as well as their effectiveness and safety in use. Furthermore, the use of EOs as anticancer drugs is complex, as it requires absolute pharmacodynamic specificity and selectivity, as well as an appropriate formulation for effective administration. In this study, we present a synthesis of recent work on the mechanisms of anticancer action of EOs and their bioactive compounds, examining the results of various in vitro and in vivo studies. We also review future research prospects in this exciting field, as well as potential implications for the development of new cancer drugs.

Reciprocal Regulation of Peroxisome Biogenesis and Myogenic Factors Is Critical for Myogenesis

Mitochondria (MITO) and peroxisomes (PEXO) are the major organelles involved in the oxidative metabolism of cells, but detailed examination of their dynamics and functional adaptations during skeletal muscle (SKM) development (myogenesis) is still lacking. In this study, we found that during myogenesis, MITO DNA, ROS level, and redox ratio increased in myotubes, but the membrane potential (Δψm) and ATP content reduced, implying that the MITO efficiency might reduce during myogenesis. The PEXO number and density both increased during myogenesis, which probably resulted from the accumulation and increased biogenesis of PEXO. The expression of PEXO biogenesis factors was induced during myogenesis in vitro and in utero, and their promoters were also activated by MyoD. Knockdown of the biogenesis factors Pex3 repressed not only the PEXO density and functions but also the levels of MITO genes and functions, suggesting a close coupling between PEXO biogenesis and MITO functions. Surprisingly, Pex3 knockdown by the CRISPRi system repressed myogenic differentiation, indicating critical involvement of PEXO biogenesis in myogenesis. Taken together, these observations suggest that the dynamics and functions of both MITO and PEXO are coupled with each other and with the metabolic changes that occur during myogenesis, and these metabolic couplings are critical to myogenesis.

The relationship between the serum lipid profile and hepatocellular carcinoma in east Asian population: A mendelian randomization study

Background

Although several studies have found that the serum lipid profile may be correlated with hepatocellular carcinoma (HCC), the causal relationships between the serum lipid profile and HCC have not been determined due to potential confounder. Here, Mendelian randomization (MR) analysis was performed to identify the relationship between the serum lipid profile and HCC in the East Asian population.

Method

Our study made a MR analysis with the validation of two data sets. We obtained genome-wide association study (GWAS) data related to the serum lipid profile from Asian Genetic Epidemiology Network (AGEN). Then, the data from a recent large GWAS of the East Asian ancestry in Japan (BioBank Japan, BBJ) were extracted. Summary-level statistical data for HCC were obtained from a large GWAS of the East Asian ancestry in Japan. Univariable MR analysis were performed to identify whether the genetic evidence of serum lipid profile was significantly associated with HCC risk. Multivariable MR analysis was conducted to estimate the independent effects of exposures on HCC.

Results

Univariable and multivariable MR analyses indicated that the serum lipid profile was not a risk factor for HCC incidence in either data set based on the East Asian population. Multivariable MR analysis revealed that the hazard ratios of the probability of HCC in AGEN were 1.134 (95% confidence interval (CI), 0.903-1.424) for TG, 1.010 (95% CI: 0.824-1.237) for HDL-C, 0.974 (95% CI: 0.746-1.271) for TC, 0.918 (95% CI: 0.734-1.147) for LDL-C, while the results in BBJ were also non-significant: 1.111 (95% CI: 0.869-1.419) for TG, 0.957 (95% CI: 0.790-1.158) for HDL-C, 0.917 (95% CI: 0.643-1.308) for TC, 0.932 (95% CI: 0.699-1.243) for LDL-C.

Conclusion

Our MR study with the validation of two data sets found no strong evidence to support causal associations between the serum lipid profile and HCC risk.

Mitochondrial Metabolism Drives Low-density Lipoprotein-induced Breast Cancer Cell Migration

Most cancer-related deaths are due to metastases. Systemic factors, such as lipid-enriched environments [as low-density lipoprotein (LDL)-cholesterol], favor breast cancer, including triple-negative breast cancer (TNBC) metastasis formation. Mitochondria metabolism impacts TNBC invasive behavior but its involvement in a lipid-enriched setting is undisclosed. Here we show that LDL increases lipid droplets, induces CD36 and augments TNBC cells migration and invasion in vivo and in vitro. LDL induces higher mitochondrial mass and network spread in migrating cells, in an actin remodeling-dependent manner, and transcriptomic and energetic analyses revealed that LDL renders TNBC cells dependent on fatty acids (FA) usage for mitochondrial respiration. Indeed, engagement on FA transport into the mitochondria is required for LDL-induced migration and mitochondrial remodeling. Mechanistically, LDL treatment leads to mitochondrial long-chain fatty acid accumulation and increased reactive oxygen species (ROS) production. Importantly, CD36 or ROS blockade abolished LDL-induced cell migration and mitochondria metabolic adaptations. Our data suggest that LDL induces TNBC cells migration by reprogramming mitochondrial metabolism, revealing a new vulnerability in metastatic breast cancer.

Significance

LDL induces breast cancer cell migration that relies on CD36 for mitochondrial metabolism and network remodeling, providing an antimetastatic metabolic strategy.

Metabolic reprogramming and interventions in endometrial carcinoma

Cancer cells are usually featured by metabolic adaptations that facilitate their growth, invasion, and metastasis. Thus, reprogramming of intracellular energy metabolism is currently one of the hotspots in the field of cancer research. Whereas aerobic glycolysis (known as the Warburg effect) has long been considered a dominant form of energy metabolism in cancer cells, emerging evidence indicates that other metabolic forms, especially oxidative phosphorylation (OXPHOS), may play a critical role at least in some types of cancer. Of note, women with metabolic syndromes (MetS), including obesity, hyperglycemia, dyslipidemia, and hypertension, have an increased risk of developing endometrial carcinoma (EC), suggesting a close link between metabolism and EC. Interestingly, the metabolic preferences vary among EC cell types, particularly cancer stem cells and chemotherapy-resistant cells. Currently, it is commonly accepted that glycolysis is the main energy provider in EC cells, while OXPHOS is reduced or impaired. Moreover, agents specifically targeting the glycolysis and/or OXPHOS pathways can inhibit tumor cell growth and promote chemosensitization. For example, metformin and weight control not only reduce the incidence of EC but also improve the prognosis of EC patients. In this review, we comprehensively overview the current in-depth understanding of the relationship between metabolism and EC and provide up-to-date insights into the development of novel therapies targeting energy metabolism for auxiliary treatment in combination with chemotherapy for EC, especially those resistant to conventional chemotherapy.

Novel Liposomal Formulation of Baicalein for the Treatment of Pancreatic Ductal Adenocarcinoma: Design, Characterization, and Evaluation

Pancreatic cancer (PC) is one of the deadliest cancers so there is an urgent need to develop new drugs and therapies to treat it. Liposome-based formulations of naturally-derived bioactive compounds are promising anticancer candidates due to their potential for passive accumulation in tumor tissues, protection against payload degradation, and prevention of non-specific toxicity. We chose the naturally-derived flavonoid baicalein (BAI) due to its promising effect against pancreatic ductal adenocarcinoma (PDAC) and encapsulated it into a liposomal bilayer using the passive loading method, with an almost 90% efficiency. We performed a morphological and stability analysis of the obtained BAI liposomal formulation and evaluated its activity on two-dimensional and three-dimensional pancreatic cell models. As the result, we obtained a stable BAI-encapsulated liposomal suspension with a size of 100.9 nm ± 2.7 and homogeneity PDI = 0.124 ± 0.02, suitable for intravenous administration. Furthermore, this formulation showed high cytotoxic activity towards AsPC-1 and BxPC-3 PDAC cell lines (IC₅₀ values ranging from 21 ± 3.6 µM to 27.6 ± 4.1 µM), with limited toxicity towards normal NHDF cells and a lack of hemolytic activity. Based on these results, this new BAI liposomal formulation is an excellent candidate for potential anti-PDAC therapy.

Investigation of the Exometabolomic Profiles of Rat Islets of Langerhans Cultured in Microfluidic Biochip

Diabetes mellitus (DM) is a complex disease with high prevalence of comorbidity and mortality. DM is predicted to reach more than 700 million people by 2045. In recent years, several advanced in vitro models and analytical tools were developed to investigate the pancreatic tissue response to pathological situations and identify therapeutic solutions. Of all the in vitro promising models, cell culture in microfluidic biochip allows the reproduction of in-vivo-like micro-environments. Here, we cultured rat islets of Langerhans using dynamic cultures in microfluidic biochips. The dynamic cultures were compared to static islets cultures in Petri. The islets' exometabolomic signatures, with and without GLP1 and isradipine treatments, were characterized by GC-MS. Compared to Petri, biochip culture contributes to maintaining high secretions of insulin, C-peptide and glucagon. The exometabolomic profiling revealed 22 and 18 metabolites differentially expressed between Petri and biochip on Day 3 and 5. These metabolites illustrated the increase in lipid metabolism, the perturbation of the pentose phosphate pathway and the TCA cycle in biochip. After drug stimulations, the exometabolome of biochip culture appeared more perturbed than the Petri exometabolome. The GLP1 contributed to the increase in the levels of glycolysis, pentose phosphate and glutathione pathways intermediates, whereas isradipine led to reduced levels of lipids and carbohydrates.

Mitochondrial metabolic reprogramming by SIRT3 regulation ameliorates drug resistance in renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) alters metabolic signals frequently, leading to mitochondrial dysfunction, such as increase of glycolysis and accumulation of lipid. Sirtuin3 (SIRT3) is a key factor for the regulation of both mitochondrial integrity and function. SIRT3 is downregulated and contributes in both cancer development and progression in ccRCC. The aim of this study is to investigate SIRT3-regulated mitochondrial biogenesis in ccRCC. SIRT3 overexpression alone reduced glucose uptake rate and enhanced membrane potential in mitochondria. ccRCC with overexpressed SIRT3 further improved the lethal effects when combined with anticancer drugs (Resveratrol, Everolimus and Temsirolimus). Cell viability was markedly decreased in a dose-dependent manner when treated with resveratrol or mTOR inhibitors in SIRT3 overexpressing ccRCC. In conclusion, SIRT3 improved mitochondrial functions in ccRCC through metabolic reprogramming. Mitochondrial reprogramming by SIRT3 regulation improves the sensitivity to anticancer drugs. The combination of SIRT3 and resveratrol functioned synergistically lethal effect in ccRCC.

Rhenium(I) conjugates as tools for tracking cholesterol in cells

Cholesterol is vital to control membrane integrity and fluidity, but is also a precursor to produce steroid hormones, bile acids, and vitamin D. Consequently, altered cholesterol biology has been linked to many diseases, including metabolic syndromes and cancer. Defining the intracellular pools of cholesterol and its trafficking within cells is essential to understand both normal cell physiology and mechanisms of pathogenesis. We have synthesized a new cholesterol mimic (ReTEGCholestanol), comprising a luminescent rhenium metal complex and a cholestanol targeting unit, linked using a tetraethylene glycol (TEG) spacer. ReTEGCholestanol demonstrated favourable imaging properties and improved water solubility when compared to a cholesterol derivative, and structurally related probes lacking the TEG linker. A non-malignant and three malignant prostate cell lines were used to characterize the uptake and intracellular distribution of ReTEGCholestanol. The ReTEGCholestanol complex was effectively internalized and mainly localized to late endosomes/lysosomes in non-malignant PNT1a cells, while in prostate cancer cells it also accumulated in early endosomes and multivesicular bodies, suggesting disturbed cholesterol biology in the malignant cells. The ReTEGCholestanol is a novel imaging agent for visualizing endosomal uptake and trafficking, which may be used to define cholesterol related biology including membrane integration and altered lipid trafficking/processing.

Regulatory roles of external cholesterol in human airway epithelial mitochondrial function through STARD3 signalling

BACKGROUND

Hypercholesterolemia is found in patients with chronic lung inflammation, during which airway epithelial cells play important roles in maintenance of inflammatory responses to pathogens. The present study aims at molecular mechanisms by which cholesterol changes airway epithelial sensitivity in response to smoking.

METHODS

Human bronchial epithelial cells (HBEs) were stimulated with cigarette smoke extract (CSE) and mice were exposed to CS/lipopolysaccharide (LPS) as models in vitro and in vivo. Severe COPD patients and healthy volunteers were also enrolled and the level of cholesterol in plasma was detected by metabolomics. Filipin III and elisa kits were used to stain free cholesterol. Mitochondrial function was detected by mitotracker green, mitotracker green, and Seahorse. Mitochondrial morphology was detected by high content screening and electron microscopy. The mRNA and protein levels of mitochondrial dynamics-related proteins were detected by RT-qPCR and Western blot,respectively. BODIPY 493/503 was used to stain lipid droplets. Lipidomics was used to detect intracellular lipid components. The mRNA level of interleukin (IL)-6 and IL-8 were detected by RT-qPCR.

RESULTS

We found that the cholesterol overload was associated with chronic obstructive pulmonary disease (COPD) and airway epithelia-driven inflammation, evidenced by hypercholesterolemia in patients with COPD and preclinical models, alteration of lipid metabolism-associated genes in CSE-induced airway epithelia and production of ILs. External cholesterol altered airway epithelial sensitivity of inflammation in response to CSE, through the regulation of STARD3-MFN2 pathway, cholesterol re-distribution, altered transport and accumulation of cholesterol, activities of lipid transport regulators and disorder of mitochondrial function and dynamics. MFN2 down-regulation increased airway epithelial sensitivity and production of ILs after smoking, at least partially by injuring fatty acid oxidation and activating mTOR phosphorylation.

CONCLUSIONS

Our data provide new insights for understanding molecular mechanisms of cholesterol-altered airway epithelial inflammation and for developing diagnostic biomarkers and therapeutic targets to improve patient outcomes.

miR‑99a‑5p inhibits glycolysis and induces cell apoptosis in cervical cancer by targeting RRAGD

Cervical cancer (CC) is one of the most common gynecological malignancies that endangers women's health. A negative effect of glycolysis is that it contributes to abnormal tumor growth. MicroRNA (miR)-99a expression has been found to be decreased in CC. The present study aimed to investigate the role of miR-99a-5p in glycolysis in CC. For this purpose, the association between miR-99a and the prognosis of patients with CC from The Cancer Genome Atlas database was analyzed using Kaplan-Meier analysis. miR-99a-5p expression and Ras-related GTP binding D (RRAGD) expression were assessed using reverse transcription-quantitative PCR and western blot analysis. Cell proliferation and apoptosis were examined using an MTT assay and flow cytometry, respectively. Glucose uptake, lactate concentration and extracellular acidification rate were measured using a glucose uptake colorimetric assay, a lactate colorimetric assay and a Seahorse XFe96 extracellular flux analyzer, respectively. The association between miR-99a-5p and RRAGD was predicted using TargetScan 7.1, and was confirmed using dual luciferase reporter assay. The results revealed that miR-99a-5p expression was decreased and that of RRAGD was increased in CC tissues and cell lines. RRAGD was negatively regulated by miR-99a-5p. The overexpression of miR-99a-5p induced apoptosis and inhibited glycolysis in CC cells by targeting RRAGD. On the whole, the present study revealed a novel mechanism through which miR-99a-5p regulates cell apoptosis and glycolysis in CC, thus providing a potential therapeutic target for CC.

Proteomic characterization of a candidate polygenic driver of metabolism in non-small cell lung cancer

Proteome analysis revealed signatures of co-expressed upregulated metabolism proteins highly conserved between primary and non-small cell lung cancer (NSCLC) patient-derived xenograft tumors (Li et al. 2014, Nat. Communications 5:5469). The C10 signature is encoded by seven genes (ADSS, ATP2A2, CTPS1, IMPDH2, PKM2, PTGES3, SGPL1) and DNA alterations in C10-encoding genes are associated with longer survival in a subset of NSCLC. To explore the C10 signature as an oncogenic driver and address potential mechanisms of action, C10 protein expression and protein-protein interactions were determined. In independent NSCLC cohorts, the coordinated expression of C10 proteins was significant and mutations in C10 genes were associated with better outcome. Affinity purification-mass spectrometry and in vivo proximity-based biotin identification defined a C10 interactome involving 667 proteins including candidate drug targets and clusters associated with glycolysis, calcium homeostasis, and nucleotide and sphingolipid metabolism. DNA alterations in genes encoding C10 interactome components were also found to be associated with better survival. These data support the notion that the coordinated upregulation of the C10 signature impinges metabolic processes that collectively function as an oncogenic driver in NSCLC.

Extraction, Encapsulation into Lipid Vesicular Systems, and Biological Activity of Rosa canina L. Bioactive Compounds for Dermocosmetic Use

Valorization of wild plants to obtain botanical ingredients could be a strategy for sustainable production of cosmetics. This study aimed to select the rosehip extract containing the greatest amounts of bioactive compounds and to encapsulate it in vesicular systems capable of protecting their own antioxidant activity. Chemical analysis of Rosa canina L. extracts was performed by LC-DAD-MS/MS and ¹H-NMR and vitamins, phenolic compounds, sugars, and organic acids were detected as the main compounds of the extracts. Liposomes, prepared by the film hydration method, together with hyalurosomes and ethosomes, obtained by the ethanol injection method, were characterized in terms of vesicle size, polydispersity index, entrapment efficiency, zeta potential, in vitro release and biocompatibility on WS1 fibroblasts. Among all types of vesicular systems, ethosomes proved to be the most promising nanocarriers showing nanometric size (196 ± 1 nm), narrow polydispersity (0.20 ± 0.02), good entrapment efficiency (92.30 ± 0.02%), and negative zeta potential (−37.36 ± 0.55 mV). Moreover, ethosomes showed good stability over time, a slow release of polyphenols compared with free extract, and they were not cytotoxic. In conclusion, ethosomes could be innovative carriers for the encapsulation of rosehip extract.

Mitochondria and the NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

Alcoholic (ASH) and nonalcoholic steatohepatitis (NASH) are advanced stages of fatty liver disease and two of the most prevalent forms of chronic liver disease. ASH and NASH are associated with significant risk of further progression to cirrhosis and hepatocellular carcinoma (HCC), the most common type of liver cancer, and a major cause of cancer-related mortality. Despite extensive research and progress in the last decades to elucidate the mechanisms of the development of ASH and NASH, the pathogenesis of both diseases is still poorly understood. Mitochondrial damage and activation of inflammasome complexes have a role in inducing and sustaining liver damage. Mitochondrial dysfunction produces inflammatory factors that activate the inflammasome complexes. NLRP3 inflammasome (nucleotide-binding oligomerization domain-like receptor protein 3) is a multiprotein complex that activates caspase 1 and the release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-18 (IL-18), and contributes to inflammatory pyroptotic cell death. The present review, which is part of the issue "Mitochondria in Liver Pathobiology", provides an overview of the role of mitochondrial dysfunction and NLRP3 activation in ASH and NASH.

Transforming the Chemical Structure and Bio-Nano Activity of Doxorubicin by Ultrasound for Selective Killing of Cancer Cells

Reconfiguring the structure and selectivity of existing chemotherapeutics represents an opportunity for developing novel tumor-selective drugs. Here, as a proof-of-concept, the use of high-frequency sound waves is demonstrated to transform the nonselective anthracycline doxorubicin into a tumor selective drug molecule. The transformed drug self-aggregates in water to form ≈200 nm nanodrugs without requiring organic solvents, chemical agents, or surfactants. The nanodrugs preferentially interact with lipid rafts in the mitochondria of cancer cells. The mitochondrial localization of the nanodrugs plays a key role in inducing reactive oxygen species mediated selective death of breast cancer, colorectal carcinoma, ovarian carcinoma, and drug-resistant cell lines. Only marginal cytotoxicity (80-100% cell viability) toward fibroblasts and cardiomyocytes is observed, even after administration of high doses of the nanodrug (25-40 µg mL^-1 ). Penetration, cytotoxicity, and selectivity of the nanodrugs in tumor-mimicking tissues are validated by using a 3D coculture of cancer and healthy cells and 3D cell-collagen constructs in a perfusion bioreactor. The nanodrugs exhibit tropism for lung and limited accumulation in the liver and spleen, as suggested by in vivo biodistribution studies. The results highlight the potential of this approach to transform the structure and bioactivity of anticancer drugs and antibiotics bearing sono-active moieties.

Cholesterol-Lowering Phytochemicals: Targeting the Mevalonate Pathway for Anticancer Interventions

There are a plethora of cancer causes and the road to fully understanding the carcinogenesis process remains a dream that keeps changing. However, a list of role players that are implicated in the carcinogens process is getting lengthier. Cholesterol is known as bad sterol that is heavily linked with cardiovascular diseases; however, it is also comprehensively associated with carcinogenesis. There is an extensive list of strategies that have been used to lower cholesterol; nevertheless, the need to find better and effective strategies remains vastly important. The role played by cholesterol in the induction of the carcinogenesis process has attracted huge interest in recent years. Phytochemicals can be dubbed as magic tramp cards that humans could exploit for lowering cancer-causing cholesterol. Additionally, the mechanisms that are regulated by phytochemicals can be targeted for anticancer drug development. One of the key role players in cancer development and suppression, Tumour Protein 53 (TP53), is crucial in regulating the biogenesis of cholesterol and is targeted by several phytochemicals. This minireview covers the role of p53 in the mevalonate pathway and how bioactive phytochemicals target the mevalonate pathway and promote p53-dependent anticancer activities.

It Takes More than Two to Tango: Complex, Hierarchal, and Membrane-Modulated Interactions in the Regulation of Receptor Tyrosine Kinases

The search for an understanding of how cell fate and motility are regulated is not a purely scientific undertaking, but it can also lead to rationally designed therapies against cancer. The discovery of tyrosine kinases about half a century ago, the subsequent characterization of certain transmembrane receptors harboring tyrosine kinase activity, and their connection to the development of human cancer ushered in a new age with the hope of finding a treatment for malignant diseases in the foreseeable future. However, painstaking efforts were required to uncover the principles of how these receptors with intrinsic tyrosine kinase activity are regulated. Developments in molecular and structural biology and biophysical approaches paved the way towards better understanding of these pathways. Discoveries in the past twenty years first resulted in the formulation of textbook dogmas, such as dimerization-driven receptor association, which were followed by fine-tuning the model. In this review, the role of molecular interactions taking place during the activation of receptor tyrosine kinases, with special attention to the epidermal growth factor receptor family, will be discussed. The fact that these receptors are anchored in the membrane provides ample opportunities for modulatory lipid-protein interactions that will be considered in detail in the second part of the manuscript. Although qualitative and quantitative alterations in lipids in cancer are not sufficient in their own right to drive the malignant transformation, they both contribute to tumor formation and also provide ways to treat cancer. The review will be concluded with a summary of these medical aspects of lipid-protein interactions.

Sex differences in cardiovascular risk may be related to sex differences in diet patterns: a narrative review

CONTEXT

Cardiovascular disease (CVD) is the leading cause of death in the United States and globally. The social and biological differences in diet patterns among men and women may play a role in their differential cardiovascular risk.

OBJECTIVE

To describe the dietary patterns associated with CVD risk and investigate the differences in diet patterns between men and women, if these differences affect cardiovascular risk, and to explore potential mechanisms of action.

METHODS

Diet patterns associated with CVD risk were described based on epidemiological and experimental trials. Observational and experimental studies together with systematic and non-systematic reviews were synthesised to examine sex differences in diet and cardiovascular risk factors.

RESULTS

Differences in vasculature and body composition between sexes may be mediated by dissimilarities in adherence to diet patterns and nutrient metabolism. Salt sensitivity and breakdown and storage of lipids may account for some differences in CVD risk between men and women. Sex differences in social norms, cognitive processing, and odour perception may be affected by biological differences and contribute to differences in cardiovascular risk and dietary patterns.

CONCLUSION

The relation between diet patterns and cardiovascular risk is well-established and sex differences in diet patterns likely differentially affect CVD risk between men and women.

Lipoproteins and cancer: The role of HDL-C, LDL-C, and cholesterol-lowering drugs

Cholesterol is an amphipathic sterol molecule that is vital for maintaining normal physiological homeostasis. It is a relatively complicated molecule with 27 carbons whose synthesis starts with 2-carbon units. This in itself signifies the importance of this molecule. Cholesterol serves as a precursor for vitamin D, bile acids, and hormones, including estrogens, androgens, progestogens, and corticosteroids. Although essential, high cholesterol levels are associated with cardiovascular and kidney diseases and cancer initiation, progression, and metastasis. Although there are some contrary reports, current literature suggests a positive association between serum cholesterol levels and the risk and extent of cancer development. In this review, we first present a brief overview of cholesterol biosynthesis and its transport, then elucidate the role of cholesterol in the progression of some cancers. Suggested mechanisms for cholesterol-mediated cancer progression are plentiful and include the activation of oncogenic signaling pathways and the induction of oxidative stress, among others. The specific roles of the lipoprotein molecules, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), in this pathogenesis, are also reviewed. Finally, we hone on the potential role of some cholesterol-lowering medications in cancer.

Emerging Roles of the Tumor Suppressor p53 in Metabolism

Metabolism plays critical roles in maintaining the homeostasis of cells. Metabolic abnormalities are often considered as one of the main driving forces for cancer progression, providing energy and substrates of biosynthesis to support neoplastic proliferation effectively. The tumor suppressor p53 is well known for its roles in inducing cell cycle arrest, apoptosis, senescence and ferroptosis. Recently, emerging evidence has shown that p53 is also actively involved in the reprogramming of cellular metabolism. In this review, we focus on recent advances in our understanding of the interplay between p53 and metabolism of glucose, fatty acid as well as amino acid, and discuss how the deregulation of p53 in these processes could lead to cancer.

The Role of Chloride Channels in the Multidrug Resistance

Nowadays, one of medicine's main and most challenging aims is finding effective ways to treat cancer. Unfortunately, although there are numerous anti-cancerous drugs, such as cisplatin, more and more cancerous cells create drug resistance. Thus, it is equally important to find new medicines and research the drug resistance phenomenon and possibilities to avoid this mechanism. Ion channels, including chloride channels, play an important role in the drug resistance phenomenon. Our article focuses on the chloride channels, especially the volume-regulated channels (VRAC) and CLC chloride channels family. VRAC induces multidrug resistance (MDR) by causing apoptosis connected with apoptotic volume decrease (AVD) and VRAC are responsible for the transport of anti-cancerous drugs such as cisplatin. VRACs are a group of heterogenic complexes made from leucine-rich repetition with 8A (LRRC8A) and a subunit LRRC8B-E responsible for the properties. There are probably other subunits, which can create those channels, for example, TTYH1 and TTYH2. It is also known that the ClC family is involved in creating MDR in mainly two mechanisms-by changing the cell metabolism or acidification of the cell. The most researched chloride channel from this family is the CLC-3 channel. However, other channels are playing an important role in inducing MDR as well. In this paper, we review the role of chloride channels in MDR and establish the role of the channels in the MDR phenomenon.

Role of bioactive peptides derived from food proteins in programmed cell death to treat inflammatory diseases and cancer

Bioactive peptides are specific peptide which usually contains 2-20 amino acid residues and actively exerts various functions and biological activities and ultimately affect health. Programmed cell deaths are some styles of cell death discovered in recent years, which is the key to tissue development and balance, eliminating excess, damaged or aging cells. More importantly, programmed cell death is a potential way to treat inflammatory diseases and cancer. In this review, through screening references from 2015 to present, we introduce the effect of bioactive peptides derived from food proteins on inflammatory diseases or cancer through regulating programmed cell deaths, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. And this review also introduces the targets of these bioactive peptides to regulate programmed cell death. The purpose of this review is to help to expand the prospective applications of bioactive peptides in the field of inflammatory disease and cancer to provide some guidance.

Mechanisms of induction of tumors by cholesterol and potential therapeutic prospects

Increasing evidence suggested that cholesterol is an important integrant of cell membranes, that plays a key role in tumor progression, immune dysregulation, and pathological changes in epigenetic mechanisms. Based on these theories, there is a growing interest on targeting cholesterol in the treatment of cancer. Here, we comprehensively reviewed the major function of cholesterol on oncogenicity, the therapeutic targets of cholesterol and its metabolites in cancer, and provide detailed insight into the essential roles of cholesterol in mediating immune and epigenetic mechanisms of the tumor microenvironment. It is also worth mentioning that the gut microbiome is an indispensable component of cancer mediation because of its role in cholesterol metabolism. Finally, we summarized recent studies on the potential targets of cholesterol and their metabolism, to provide more therapeutic interventions in oncology.

Atomistic simulations modify interpretation of spin-label oximetry data. Part 1: intensified water-lipid interfacial resistances

The role of membrane cholesterol in cellular function and dysfunction has been the subject of much inquiry. A few studies have suggested that cholesterol may slow oxygen diffusive transport, altering membrane physical properties and reducing oxygen permeability. The primary experimental technique used in recent years to study membrane oxygen transport is saturation-recovery electron paramagnetic resonance (EPR) oximetry, using spin-label probes targeted to specific regions of a lipid bilayer. The technique has been used, in particular, to assess the influence of cholesterol on oxygen transport and membrane permeability. The reliability of such EPR recordings at the water-lipid interface near the phospholipid headgroups has been challenged by all-atom molecular dynamics (MD) simulation data that show substantive agreement with spin-label probe measurements throughout much of the bilayer. This work uses further MD simulations, with an updated oxygen model, to determine the location of the maximum resistance to permeation and the rate-limiting barrier to oxygen permeation in 1-palmitoyl,2-oleoylphosphatidylcholine (POPC) and POPC/cholesterol bilayers at 25 and 35°C. The current simulations show a spike of resistance to permeation in the headgroup region that was not detected by EPR but was predicted in early theoretical work by Diamond and Katz. Published experimental nuclear magnetic resonance (NMR) oxygen measurements provide key validation of the MD models and indicate that the positions and relative magnitudes of the phosphatidylcholine resistance peaks are accurate. Consideration of the headgroup-region resistances predicts bilayer permeability coefficients lower than estimated in EPR studies, giving permeabilities lower than the permeability of unstirred water layers of the same thickness. Here, the permeability of POPC at 35°C is estimated to be 13 cm/s, compared with 10 cm/s for POPC/cholesterol and 118 cm/s for simulation water layers of similar thickness. The value for POPC is 12 times lower than estimated from EPR measurements, while the value for POPC/cholesterol is 5 times lower. These findings underscore the value of atomic resolution models for guiding the interpretation of experimental probe-based measurements.

Inhibition of Scavenger Receptor Class B Type 1 (SR-B1) Expression and Activity as a Potential Novel Target to Disrupt Cholesterol Availability in Castration-Resistant Prostate Cancer

There have been several studies that have linked elevated scavenger receptor class b type 1 (SR-B1) expression and activity to the development and progression of castration-resistant prostate cancer (CRPC). SR-B1 facilitates the influx of cholesterol to the cell from lipoproteins in systemic circulation. This influx of cholesterol may be important for many cellular functions, including the synthesis of androgens. Castration-resistant prostate cancer tumors can synthesize androgens de novo to supplement the loss of exogenous sources often induced by androgen deprivation therapy. Silencing of SR-B1 may impact the ability of prostate cancer cells, particularly those of the castration-resistant state, to maintain the intracellular supply of androgens by removing a supply of cholesterol. SR-B1 expression is elevated in CRPC models and has been linked to poor survival of patients. The overarching belief has been that cholesterol modulation, through either synthesis or uptake inhibition, will impact essential signaling processes, impeding the proliferation of prostate cancer. The reduction in cellular cholesterol availability can impede prostate cancer proliferation through both decreased steroid synthesis and steroid-independent mechanisms, providing a potential therapeutic target for the treatment of prostate cancer. In this article, we discuss and highlight the work on SR-B1 as a potential novel drug target for CRPC management.

Multifaceted Effects of Lycopene: A Boulevard to the Multitarget-Based Treatment for Cancer

Lycopene is a pigment belonging to the group of carotenoids and it is among the most carefully studied antioxidants found especially in fruit and vegetables. As a carotenoid, lycopene exerts beneficial effects on human health by protecting lipids, proteins, and DNA from damage by oxidation. Lycopene is a powerful oxygen inactivator in the singlet state. This is suggestive of the fact that lycopene harbors comparatively stronger antioxidant properties over other carotenoids normally present in plasma. Lycopene is also reported to hinder cancer cell proliferation. The uncontrolled, rapid division of cells is a characteristic of the metabolism of cancer cells. Evidently, lycopene causes a delay in the progression of the cell cycle, which explains its antitumor activity. Furthermore, lycopene can block cell transformation by reducing the loss of contact inhibition of cancer cells. This paper collects recent studies of scientific evidence that show the multiple beneficial properties of lycopene, which acts with different molecular and cellular mechanisms.

ATAD3A stabilizes GRP78 to suppress ER stress for acquired chemoresistance in colorectal cancer

AAA domain containing 3A (ATAD3A) is a nucleus-encoded mitochondrial protein with vital function in communication between endoplasmic reticulum (ER) and mitochondria which is participated in cancer metastasis. Here we show that elevated ATAD3A expression is clinically associated with poor 5-year disease-free survival in patients with colorectal cancer (CRC), especially high-risk CRC patients who received adjuvant chemotherapy. Our results indicated ATAD3A is significantly upregulated to reduce chemotherapy-induced cancer cell death. We found that knockdown of ATAD3A leads to dysregulation in protein processing for inducing ER stress by RNA sequencing (RNA-seq). In response to chemotherapy-induced ER stress, ATAD3A interacts with elevated GRP78 protein to assist protein folding and alleviate ER stress for cancer cell survival. This reduction of ER stress leads to reduce the surface exposure of calreticulin, which is the initiator of immunogenic cell death and antitumor immunity. However, silencing of ATAD3A enhances cell death, triggers the feasibility of chemotherapy-induced ER stress for antitumor immunity, increases infiltration of T lymphocytes and delays tumor regrowth in vitro and in vivo. Clinically, CRC patients with less ATAD3A have high density of CD45+ intratumoral infiltrating lymphocytes (TILs) and memory CD45RO+ TILs. Taken together, our results suggest that pharmacologic targeting to ATAD3A might be a potential therapeutic strategy to enhance antitumor immunity for CRC patients who received adjuvant chemotherapy.

Exploring lipid-dependent conformations of membrane-bound α-synuclein with the VDAC nanopore

Regulation of VDAC by α-synuclein (αSyn) is a rich and instructive example of protein-protein interactions catalyzed by a lipid membrane surface. αSyn, a peripheral membrane protein involved in Parkinson's disease pathology, is known to bind to membranes in a transient manner. αSyn's negatively charged C-terminal domain is then available to be electromechanically trapped by the VDAC β-barrel, a process that is observed in vitro as the reversible reduction of ion flow through a single voltage-biased VDAC nanopore. Binding of αSyn to the lipid bilayer is a prerequisite of the channel-protein interaction; surprisingly, however, we find that the strength of αSyn binding to the membrane does not correlate in any simple way with its efficiency of blocking VDAC, suggesting that the lipid-dependent conformations of the membrane-bound αSyn control the interaction. Quantitative models of the free energy landscape governing the capture and release processes allow us to discriminate between several αSyn (sub-) conformations on the membrane surface. These results, combined with known structural features of αSyn on anionic lipid membranes, point to a model in which the lipid composition determines the fraction of αSyn molecules for which the charged C terminal domain is constrained to be close, but not tightly bound, to the membrane surface and thus readily captured by the VDAC nanopore. We speculate that changes in the mitochondrial membrane lipid composition may be key regulators of the αSyn-VDAC interaction and consequently of VDAC-facilitated transport of ions and metabolites in and out of mitochondria and, i.e. mitochondrial metabolism.

Dietary and Genetic Cholesterol Loading Rather Than Steatosis Promotes Liver Tumorigenesis and NASH-Driven HCC

Simple Summary

In the present study, which is part of the Special Issue “Theranostic Advances in Hepatobiliary Tumors”, we address whether hepatic steatosis per se or cholesterol sensitizes to NASH-driven HCC. This is a very important health issue, as the incidence of HCC derived from NASH is expected to keep rising due to the association of NASH with the obesity and type 2 diabetes epidemic. Using dietary and genetic models to generate hepatic steatosis with or without cholesterol accumulation, we provide evidence for the tumor promoter role of cholesterol in NASH-HCC associated with an increased expression of the genes involved in immune checkpoints, which suggests that cholesterol favors a milieu prone to T-cell exhaustion.

Abstract

The association of nonalcoholic steatohepatitis (NASH) with obesity and type 2 diabetes is a major determinant factor for the continued rise of NASH-driven HCC. Unfortunately, the mechanisms underlying the progression from NASH to HCC are not well-understood. Steatosis is characterized by the accumulation of different lipid species, and cholesterol has emerged as an important player in NASH development, which has been shown to promote NASH-driven HCC. However, recent findings indicated a tumor suppressor role of cholesterol in liver carcinogenesis and HCC development. Thus, we examined the contribution of hepatic steatosis with or without cholesterol accumulation induced by dietary or genetic approaches in liver tumorigenesis and whether the role of cholesterol in NASH-driven HCC is species-dependent. While diethylnitrosamine (DEN) treatment to rats or mice fed a choline-deficient diet decreased the hepatic steatosis, feeding an atherogenic diet enriched in cholesterol potentiated the liver tumor markers. Similar effects were observed in DEN-treated transgenic SREBP-2 mice but not wild-type (WT) mice fed a regular chow diet. Remarkably, long-term feeding of a high-fat high-cholesterol diet (HFHC) but not a high-fat diet (HFD) to WT mice caused severe NASH with spontaneous progression to HCC. A similar outcome was observed in MUP-uPA transgenic mice fed a HFHC diet, which resulted in increased liver tumors and expression of the genes involved in the immune checkpoints. Ezetimibe treatment ameliorated chronic liver disease and, more importantly, tumor multiplicity in HFHC-fed MUP-uPA mice or DEN-treated WT mice. Thus, these results revealed a differential role of steatosis and cholesterol in NASH-driven HCC and indicated that the tumor-promoter role of cholesterol is species-independent and associated with impaired immunosurveillance.

Identification of subgroups along the glycolysis-cholesterol synthesis axis and the development of an associated prognostic risk model

BACKGROUND

Skin cutaneous melanoma (SKCM) is one of the most highly prevalent and complicated malignancies. Glycolysis and cholesterogenesis pathways both play important roles in cancer metabolic adaptations. The main aims of this study are to subtype SKCM based on glycolytic and cholesterogenic genes and to build a clinical outcome predictive algorithm based on the subtypes.

METHODS

A dataset with 471 SKCM specimens was downloaded from The Cancer Genome Atlas (TCGA) database. We extracted and clustered genes from the Molecular Signatures Database v7.2 and acquired co-expressed glycolytic and cholesterogenic genes. We then subtyped the SKCM samples and validated the efficacy of subtypes with respect to simple nucleotide variations (SNVs), copy number variation (CNV), patients' survival statuses, tumor microenvironment, and proliferation scores. We also constructed a risk score model based on metabolic subclassification and verified the model using validating datasets. Finally, we explored potential drugs for high-risk SKCM patients.

RESULTS

SKCM patients were divided into four subtype groups: glycolytic, cholesterogenic, mixed, and quiescent subgroups. The glycolytic subtype had the worst prognosis and MGAM SNV extent. Compared with the cholesterogenic subgroup, the glycolytic subgroup had higher rates of DDR2 and TPR CNV and higher proliferation scores and MK167 expression levels, but a lower tumor purity proportion. We constructed a forty-four-gene predictive signature and identified MST-321, SB-743921, Neuronal Differentiation Inducer III, romidepsin, vindesine, and YM-155 as high-sensitive drugs for high-risk SKCM patients.

CONCLUSIONS

Subtyping SKCM patients via glycolytic and cholesterogenic genes was effective, and patients in the glycolytic-gene enriched group were found to have the worst outcome. A robust prognostic algorithm was developed to enhance clinical decisions in relation to drug administration.

MITOCHONDRIAL CHOLESTEROL AND CANCER

Cholesterol is a crucial component of membrane bilayers that determines their physical and functional properties. Cells largely satisfy their need for cholesterol through the novo synthesis from acetyl-CoA and this demand is particularly critical for cancer cells to sustain dysregulated cell proliferation. However, the association between serum or tissue cholesterol levels and cancer development is not well established as epidemiologic data do not consistently support this link. While most preclinical studies focused on the role of total celular cholesterol, the specific contribution of the mitochondrial cholesterol pool to alterations in cancer cell biology has been less explored. Although low compared to other bilayers, the mitochondrial cholesterol content plays an important physiological function in the synthesis of steroid hormones in steroidogenic tissues or bile acids in the liver and controls mitochondrial function. In addition, mitochondrial cholesterol metabolism generates oxysterols, which in turn, regulate multiple pathways, including cholesterol and lipid metabolism as well as cell proliferation. In the present review, we summarize the regulation of mitochondrial cholesterol, including its role in mitochondrial routine performance, cell death and chemotherapy resistance, highlighting its potential contribution to cancer. Of particular relevance is hepatocellular carcinoma, whose incidence in Western countries had tripled in the past decades due to the obesity and type II diabetes epidemic. A better understanding of the role of mitochondrial cholesterol in cancer development may open up novel opportunities for cancer therapy.

STARD1 promotes NASH-driven HCC by sustaining the generation of bile acids through the alternative mitochondrial pathway

BACKGROUND & AIMS

Besides their physiological role in bile formation and fat digestion, bile acids (BAs) synthesised from cholesterol in hepatocytes act as signalling molecules that modulate hepatocellular carcinoma (HCC). Trafficking of cholesterol to mitochondria through steroidogenic acute regulatory protein 1 (STARD1) is the rate-limiting step in the alternative pathway of BA generation, the physiological relevance of which is not well understood. Moreover, the specific contribution of the STARD1-dependent BA synthesis pathway to HCC has not been previously explored.

METHODS

STARD1 expression was analyzed in a cohort of human non-alcoholic steatohepatitis (NASH)-derived HCC specimens. Experimental NASH-driven HCC models included MUP-uPA mice fed a high-fat high-cholesterol (HFHC) diet and diethylnitrosamine (DEN) treatment in wild-type (WT) mice fed a HFHC diet. Molecular species of BAs and oxysterols were analyzed by mass spectrometry. Effects of NASH-derived BA profiles were investigated in tumour-initiated stem-like cells (TICs) and primary mouse hepatocytes (PMHs).

RESULTS

Patients with NASH-associated HCC exhibited increased hepatic expression of STARD1 and an enhanced BA pool. Using NASH-driven HCC models, STARD1 overexpression in WT mice increased liver tumour multiplicity, whereas hepatocyte-specific STARD1 deletion (Stard1ΔHep) in WT or MUP-uPA mice reduced tumour burden. These findings mirrored the levels of unconjugated primary BAs, β-muricholic acid and cholic acid, and their tauroconjugates in STARD1-overexpressing and Stard1ΔHep mice. Incubation of TICs or PMHs with a mix of BAs mimicking this profile stimulated expression of genes involved in pluripotency, stemness and inflammation.

CONCLUSIONS

The study reveals a previously unrecognised role of STARD1 in HCC pathogenesis, wherein it promotes the synthesis of primary BAs through the mitochondrial pathway, the products of which act in TICs to stimulate self-renewal, stemness and inflammation.

LAY SUMMARY

Effective therapy for hepatocellular carcinoma (HCC) is limited because of our incomplete understanding of its pathogenesis. The contribution of the alternative pathway of bile acid (BA) synthesis to HCC development is unknown. We uncover a key role for steroidogenic acute regulatory protein 1 (STARD1) in non-alcoholic steatohepatitis-driven HCC, wherein it stimulates the generation of BAs in the mitochondrial acidic pathway, the products of which stimulate hepatocyte pluripotency and self-renewal, as well as inflammation.

Mitochondrial Targeting Involving Cholesterol-Rich Lipid Rafts in the Mechanism of Action of the Antitumor Ether Lipid and Alkylphospholipid Analog Edelfosine

The ether lipid edelfosine induces apoptosis selectively in tumor cells and is the prototypic molecule of a family of synthetic antitumor compounds collectively known as alkylphospholipid analogs. Cumulative evidence shows that edelfosine interacts with cholesterol-rich lipid rafts, endoplasmic reticulum (ER) and mitochondria. Edelfosine induces apoptosis in a number of hematological cancer cells by recruiting death receptors and downstream apoptotic signaling into lipid rafts, whereas it promotes apoptosis in solid tumor cells through an ER stress response. Edelfosine-induced apoptosis, mediated by lipid rafts and/or ER, requires the involvement of a mitochondrial-dependent step to eventually elicit cell death, leading to the loss of mitochondrial membrane potential, cytochrome c release and the triggering of cell death. The overexpression of Bcl-2 or Bcl-xL blocks edelfosine-induced apoptosis. Edelfosine induces the redistribution of lipid rafts from the plasma membrane to the mitochondria. The pro-apoptotic action of edelfosine on cancer cells is associated with the recruitment of F1FO-ATP synthase into cholesterol-rich lipid rafts. Specific inhibition of the FO sector of the F1FO-ATP synthase, which contains the membrane-embedded c-subunit ring that constitutes the mitochondrial permeability transcription pore, hinders edelfosine-induced cell death. Taking together, the evidence shown here suggests that the ether lipid edelfosine could modulate cell death in cancer cells by direct interaction with mitochondria, and the reorganization of raft-located mitochondrial proteins that critically modulate cell death or survival. Here, we summarize and discuss the involvement of mitochondria in the antitumor action of the ether lipid edelfosine, pointing out the mitochondrial targeting of this drug as a major therapeutic approach, which can be extrapolated to other alkylphospholipid analogs. We also discuss the involvement of cholesterol transport and cholesterol-rich lipid rafts in the interactions between the organelles as well as in the role of mitochondria in the regulation of apoptosis in cancer cells and cancer therapy.

Reduction of host cell mitochondrial activity as Mycobacterium leprae's strategy to evade host innate immunity

Leprosy is a much-feared incapacitating infectious disease caused by Mycobacterium leprae or M lepromatosis, annually affecting roughly 200,000 people worldwide. During host-pathogen interaction, M leprae subverts the immune response, leading to development of disease. Throughout the last few decades, the impact of energy metabolism on the control of intracellular pathogens and leukocytic differentiation has become more evident. Mitochondria play a key role in regulating newly-discovered immune signaling pathways by controlling redox metabolism and the flow of energy besides activating inflammasome, xenophagy, and apoptosis. Likewise, this organelle, whose origin is probably an alphaproteobacterium, directly controls the intracellular pathogens attempting to invade its niche, a feature conquered at the expense of billions of years of coevolution. In the present review, we discuss the role of reduced host cell mitochondrial activity during M leprae infection and the consequential fates of M leprae and host innate immunity. Conceivably, inhibition of mitochondrial energy metabolism emerges as an overlooked and novel mechanism developed by M leprae to evade xenophagy and the host immune response.

A Novel FACS-Based Workflow for Simultaneous Assessment of RedOx Status, Cellular Phenotype, and Mitochondrial Genome Stability

Intracellular reduction-oxidation (RedOx) status mediates a myriad of critical biological processes. Importantly, RedOx status regulates the differentiation of hematopoietic stem and progenitor cells (HSPCs), mesenchymal stromal cells (MSCs) and maturation of CD8+ T Lymphocytes. In most cells, mitochondria are the greatest contributors of intracellular reactive oxygen species (ROS). Excess ROS leads to mitochondrial DNA (mtDNA) damage and protein depletion. We have developed a fluorescence-activated cell sorting (FACS)-based protocol to simultaneously analyze RedOx status and mtDNA integrity. This simultaneous analysis includes measurements of ROS (reduced glutathione (GSH)), ATP5H (nuclear encoded protein), MTCO1 (mitochondrial DNA encoded protein), and cell surface markers to allow discrimination of different cell populations. Using the ratio of MTCO1 to ATP5H median fluorescence intensity (MFI), we can gain an understanding of mtDNA genomic stability, since MTCO1 levels are decreased when mtDNA becomes significantly damaged. Furthermore, this workflow can be optimized for sorting cells, using any of the above parameters, allowing for downstream quantification of mtDNA genome copies/nucleus by quantitative PCR (qPCR). This unique methodology can be used to enhance analyses of the impacts of pharmacological interventions, as well as physiological and pathophysiological processes on RedOx status along with mitochondrial dynamics in most cell types.

Links between mitochondrial retrograde response and mitophagy in pathogenic cell signalling

Preservation of mitochondrial quality is paramount for cellular homeostasis. The integrity of mitochondria is guarded by the balanced interplay between anabolic and catabolic mechanisms. The removal of bio-energetically flawed mitochondria is mediated by the process of mitophagy; the impairment of which leads to the accumulation of defective mitochondria which signal the activation of compensatory mechanisms to the nucleus. This process is known as the mitochondrial retrograde response (MRR) and is enacted by Reactive Oxygen Species (ROS), Calcium (Ca2+), ATP, as well as imbalanced lipid and proteostasis. Central to this mitochondria-to-nucleus signalling are the transcription factors (e.g. the nuclear factor kappa-light-chain-enhancer of activated B cells, NF-κB) which drive the expression of genes to adapt the cell to the compromised homeostasis. An increased degree of cellular proliferation is among the consequences of the MRR and as such, engagement of mitochondrial-nuclear communication is frequently observed in cancer. Mitophagy and the MRR are therefore interlinked processes framed to, respectively, prevent or compensate for mitochondrial defects.In this review, we discuss the available knowledge on the interdependency of these processes and their contribution to cell signalling in cancer.

MEHP interferes with mitochondrial functions and homeostasis in skeletal muscle cells

Di (2-ethylhexyl) phthalate (DEHP) is a plasticizer frequently leached out from polyvinyl chloride (PVC) products and is quickly metabolized to its monoester equivalent mono(2-ethylhexyl) phthalate (MEHP) once enters organisms. Exposure to DEHP/MEHP through food chain intake has been shown to modified metabolism but its effect on the development of metabolic myopathy of skeletal muscle (SKM) has not been revealed so far. Here, we found that MEHP repressed myogenic terminal differentiation of proliferating myoblasts (PMB) and confluent myoblasts (CMB) but had weak effect on this process once it had been initiated. The transition of mitochondria (MITO) morphology from high efficient filamentary network to low efficient vesicles was triggered by MEHP, implying its negative effects on MITO functions. The impaired MITO functions was further demonstrated by reduced MITO DNA (mtDNA) level and SDH enzyme activity as well as highly increased reactive oxygen species (ROS) in cells after MEHP treatment. The expression of metabolic genes, including PDK4, CPT1b, UCP2, and HO1, was highly increased by MEHP and the promoters of PDK4 and CPT1b were also activated by MEHP. Additionally, the stability of some subunits in the oxidative phosphorylation system (OXPHOS) complexes was found to be reduced by MEHP, implying defective oxidative metabolism in MITO and which was confirmed by repressed palmitic acid oxidation in MEHP-treated cells. Besides, MEHP also blocked insulin-induced glucose uptake. Taken together, our results suggest that MEHP is inhibitory to myogenesis and is harmful to MITO functions in SKM, so its exposure should be avoided or limited.

Warburg's Ghost-Cancer's Self-Sustaining Phenotype: The Aberrant Carbon Flux in Cholesterol-Enriched Tumor Mitochondria via Deregulated Cholesterogenesis

Interpreting connections between the multiple networks of cell metabolism is indispensable for understanding how cells maintain homeostasis or transform into the decontrolled proliferation phenotype of cancer. Situated at a critical metabolic intersection, citrate, derived via glycolysis, serves as either a combustible fuel for aerobic mitochondrial bioenergetics or as a continuously replenished cytosolic carbon source for lipid biosynthesis, an essentially anaerobic process. Therein lies the paradox: under what conditions do cells control the metabolic route by which they process citrate? The Warburg effect exposes essentially the same dilemma—why do cancer cells, despite an abundance of oxygen needed for energy-generating mitochondrial respiration with citrate as fuel, avoid catabolizing mitochondrial citrate and instead rely upon accelerated glycolysis to support their energy requirements? This review details the genesis and consequences of the metabolic paradigm of a “truncated” Krebs/TCA cycle. Abundant data are presented for substrate utilization and membrane cholesterol enrichment in tumors that are consistent with criteria of the Warburg effect. From healthy cellular homeostasis to the uncontrolled proliferation of tumors, metabolic alterations center upon the loss of regulation of the cholesterol biosynthetic pathway. Deregulated tumor cholesterogenesis at the HMGR locus, generating enhanced carbon flux through the cholesterol synthesis pathway, is an absolute prerequisite for DNA synthesis and cell division. Therefore, expedited citrate efflux from cholesterol-enriched tumor mitochondria via the CTP/SLC25A1 citrate transporter is fundamental for sustaining the constant demand for cytosolic citrate that fuels the elevated flow of carbons from acetyl-CoA through the deregulated pathway of cholesterol biosynthesis.

The Transcriptomic Landscape of Prostate Cancer Development and Progression: An Integrative Analysis

Next-generation sequencing of primary tumors is now standard for transcriptomic studies, but microarray-based data still constitute the majority of available information on other clinically valuable samples, including archive material. Using prostate cancer (PC) as a model, we developed a robust analytical framework to integrate data across different technical platforms and disease subtypes to connect distinct disease stages and reveal potentially relevant genes not identifiable from single studies alone. We reconstructed the molecular profile of PC to yield the first comprehensive insight into its development, by tracking changes in mRNA levels from normal prostate to high-grade prostatic intraepithelial neoplasia, and metastatic disease. A total of nine previously unreported stage-specific candidate genes with prognostic significance were also found. Here, we integrate gene expression data from disparate sample types, disease stages and technical platforms into one coherent whole, to give a global view of the expression changes associated with the development and progression of PC from normal tissue through to metastatic disease. Summary and individual data are available online at the Prostate Integrative Expression Database (PIXdb), a user-friendly interface designed for clinicians and laboratory researchers to facilitate translational research.

Remodeling Lipids in the Transition from Chronic Liver Disease to Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) has poor prognosis. We studied blood lipids by comparing healthy volunteers to patients with chronic liver disease (CLD), and to patients with HCC caused by viral infections. We contrasted our findings in blood to lipid alterations in liver tumor and nontumor tissue samples from HCC patients. In blood, most lipid species were found at increased levels in CLD patients compared to healthy volunteers. This trend was mostly reversed in HCC versus CLD patients. In liver tumor tissues, levels of many lipids were decreased compared to paired nontumor liver tissues. Differences in lipid levels were further defined by alterations in the degree of saturation in the fatty acyl chains. Some lipids, including free fatty acids, saturated lysophosphatidylcholines and saturated triacylglycerides, showed a continuous trend in the transition from the blood of healthy controls to CLD and HCC patients. For HCC patients, phosphatidylglycerides showed similar alterations in both blood and tissues.

Abstract

Hepatocellular carcinoma (HCC) is a worldwide health problem. HCC patients show a 50% mortality within two years of diagnosis. To better understand the molecular pathogenesis at the level of lipid metabolism, untargeted UPLC MS—QTOF lipidomics data were acquired from resected human HCC tissues and their paired nontumor hepatic tissues (n = 46). Blood samples of the same HCC subjects (n = 23) were compared to chronic liver disease (CLD) (n = 15) and healthy control (n = 15) blood samples. The participants were recruited from the National Liver Institute in Egypt. The lipidomics data yielded 604 identified lipids that were divided into six super classes. Five-hundred and twenty-four blood lipids were found as significantly differentiated (p < 0.05 and qFDR p < 0.1) between the three study groups. In the blood of CLD patients compared to healthy control subjects, almost all lipid classes were significantly upregulated. In CLD patients, triacylglycerides were found as the most significantly upregulated lipid class at qFDR p = 1.3 × 10⁻⁵⁶, followed by phosphatidylcholines at qFDR p = 3.3 × 10⁻⁵¹ and plasmalogens at qFDR p = 1.8 × 10^-46. In contrast, almost all blood lipids were significantly downregulated in HCC patients compared to CLD patients, and in HCC tissues compared to nontumor hepatic tissues. Ceramides were found as the most significant lipid class (qFDR p = 1 × 10⁻¹⁴) followed by phosphatidylglycerols (qFDR p = 3 × 10⁻⁹), phosphatidylcholines and plasmalogens. Despite these major differences, there were also common trends in the transitions between healthy controls, CLD and HCC patients. In blood, several mostly saturated triacylglycerides showed a continued increase in the trajectory towards HCC, accompanied by reduced levels of saturated free fatty acids and saturated lysophospatidylcholines. In contrast, the largest overlaps of lipid alterations that were found in both HCC tissue and blood comparisons were decreased levels of phosphatidylglycerols and sphingolipids. This study highlights the specific impact of HCC tumors on the circulating lipids. Such data may be used to target lipid metabolism for prevention, early detection and treatment of HCC in the background of viral-related CLD etiology.

LDL cholesterol promotes the proliferation of prostate and pancreatic cancer cells by activating the STAT3 pathway

Hypercholesterolemia has been found to be closely linked with a significant increase in both cancer incidence and mortality. However, the exact correlation between serum cholesterol levels and cancer has not been completely deciphered. Here we analyzed the effect of low-density lipoprotein (LDL) cholesterol on prostate and pancreatic cancer cells. We noted that LDL induced a substantial STAT3 activation and JAK1, JAK2, Src activation in diverse prostate and pancreatic tumor cells. Moreover, LDL promoted cancer cell proliferation, migration, and invasion as well as upregulated the expression of diverse oncogenic gene products. However, deletion of LDL-activated STAT3 in LNCaP and PANC-1 cells and reduced LDL-induced cell viability. Simvastatin (SV) treatment also alleviated LDL-induced cell viability and migration ability in both the prostate and pancreatic tumor cells. These results demonstrate that LDL-induced STAT3 activation may exert a profound effect on the proliferation and survival of tumor cells.