Regulation Of Cholesterol Metabolism Research Articles

Preliminary exploration of the anti-ovarian cancer activity of peptides derived from bovine bone collagen hydrolysate and its related mechanisms

Ovarian cancer, a malignant tumor that poses a significant threat to women's health, has seen a rise in incidence, prompting the urgent need for more effective treatment. This study primarily aimed to explore the potential of bovine collagen peptides in inhibiting ovarian cancer. The investigation in this study began with the identification of 268 peptide sequences through LC-MS/MS, followed by a screening process using molecular docking techniques to identify potential peptides capable of binding to EGFR. Subsequently, a series of experiments were performed, demonstrating the inhibitory effects of the peptide GPAGADGDRGEAGPAGPAGPAGPR on the proliferation of ovarian cancer cells. Transcriptomic analysis further revealed that this peptide can regulate cholesterol metabolism in ovarian cancer cells. Finally, a combination of time-resolved fluorescence resonance energy transfer, isothermal titration calorimetry, molecular docking, and molecular dynamics simulations were utilized to validate the ability of this peptide to bind to the epidermal growth factor receptor (EGFR) and impede the binding of epidermal growth factor (EGF) and EGFR.

The lncRNA LINC01605 promotes the progression of pancreatic ductal adenocarcinoma by activating the mTOR signaling pathway

BackgroundThis study investigated the molecular mechanism of long intergenic non-protein coding RNA 1605 (LINC01605) in the process of tumor growth and liver metastasis of pancreatic ductal adenocarcinoma (PDAC).MethodsLINC01605 was filtered out with specificity through TCGA datasets (related to DFS) and our RNA-sequencing data of PDAC tissue samples from Renji Hospital. The expression level and clinical relevance of LINC01605 were then verified in clinical cohorts and samples by immunohistochemical staining assay and survival analysis. Loss- and gain-of-function experiments were performed to estimate the regulatory effects of LINC01605 in vitro. RNA-seq of LINC01605-knockdown PDAC cells and subsequent inhibitor-based cellular function, western blotting, immunofluorescence and rescue experiments were conducted to explore the mechanisms by which LINC01605 regulates the behaviors of PDAC tumor cells. Subcutaneous xenograft models and intrasplenic liver metastasis models were employed to study its role in PDAC tumor growth and liver metastasis in vivo.ResultsLINC01605 expression is upregulated in both PDAC primary tumor and liver metastasis tissues and correlates with poor clinical prognosis. Loss and gain of function experiments in cells demonstrated that LINC01605 promotes the proliferation and migration of PDAC cells in vitro. In subsequent verification experiments, we found that LINC01605 contributes to PDAC progression through cholesterol metabolism regulation in a LIN28B-interacting manner by activating the mTOR signaling pathway. Furthermore, the animal models showed that LINC01605 facilitates the proliferation and metastatic invasion of PDAC cells in vivo.ConclusionsOur results indicate that the upregulated lncRNA LINC01605 promotes PDAC tumor cell proliferation and migration by regulating cholesterol metabolism via activation of the mTOR signaling pathway in a LIN28B-interacting manner. These findings provide new insight into the role of LINC01605 in PDAC tumor growth and liver metastasis as well as its value for clinical approaches as a metabolic therapeutic target in PDAC.

The multifaceted role of PCSK9 in cancer pathogenesis, tumor immunity, and immunotherapy.

Proprotein convertase subtilisin/kexin type 9 (PCSK9), a well-known regulator of cholesterol metabolism and cardiovascular diseases, has recently garnered attention for its emerging involvement in cancer biology. The multifunctional nature of PCSK9 extends beyond lipid regulation and encompasses a wide range of cellular processes that can influence cancer progression. Studies have revealed that PCSK9 can modulate signaling pathways, such as PI3K/Akt, MAPK, and Wnt/β-catenin, thereby influencing cellular proliferation, survival, and angiogenesis. Additionally, the interplay between PCSK9 and cholesterol homeostasis may impact membrane dynamics and cellular migration, further influencing tumor aggressiveness. The central role of the immune system in monitoring and controlling cancer is increasingly recognized. Recent research has demonstrated the ability of PCSK9 to modulate immune responses through interactions with immune cells and components of the tumor microenvironment. This includes effects on dendritic cell maturation, T cell activation, and cytokine production, suggesting a role in shaping antitumor immune responses. Moreover, the potential influence of PCSK9 on immune checkpoints such as PD1/PD-L1 lends an additional layer of complexity to its immunomodulatory functions. The growing interest in cancer immunotherapy has prompted exploration into the potential of targeting PCSK9 for therapeutic benefits. Preclinical studies have demonstrated synergistic effects between PCSK9 inhibitors and established immunotherapies, offering a novel avenue for combination treatments. The strategic manipulation of PCSK9 to enhance tumor immunity and improve therapeutic outcomes presents an exciting area for further investigations. Understanding the mechanisms by which PCSK9 influences cancer biology and immunity holds promise for the development of novel immunotherapeutic approaches. This review aims to provide a comprehensive analysis of the intricate connections between PCSK9, cancer pathogenesis, tumor immunity, and the potential implications for immunotherapeutic interventions.

Leukocyte immunoglobulin-like receptor B1 (LILRB1) protects human multiple myeloma cells from ferroptosis by maintaining cholesterol homeostasis

Multiple myeloma (MM) is a hematologic malignancy characterized by uncontrolled proliferation of plasma cells in the bone marrow. MM patients with aggressive progression have poor survival, emphasizing the urgent need for identifying new therapeutic targets. Here, we show that the leukocyte immunoglobulin-like receptor B1 (LILRB1), a transmembrane receptor conducting negative immune response, is a top-ranked gene associated with poor prognosis in MM patients. LILRB1 deficiency inhibits MM progression in vivo by enhancing the ferroptosis of MM cells. Mechanistic studies reveal that LILRB1 forms a complex with the low-density lipoprotein receptor (LDLR) and LDLR adapter protein 1 (LDLRAP1) to facilitate LDL/cholesterol uptake. Loss of LILRB1 impairs cholesterol uptake but activates the de novo cholesterol synthesis pathway to maintain cellular cholesterol homeostasis, leading to the decrease of anti-ferroptotic metabolite squalene. Our study uncovers the function of LILRB1 in regulating cholesterol metabolism and protecting MM cells from ferroptosis, implicating LILRB1 as a promising therapeutic target for MM patients.

A Cu‐Based Single‐Atom Nanozyme Platform with Multi‐Enzyme Simulated Activities for Immunotherapy of Prostate Cancer by Regulating Cholesterol Metabolism and Triggering Pyroptosis

AbstractImmunotherapy, one of the most promising antitumor strategies, is used to treat prostate cancer (PCa). However, owing to the immunosuppressive tumor microenvironment (TME), the therapeutic effect of the antitumor immune response is greatly weakened. Therefore, there is an urgent need to explore new methods to enhance antitumor immune responses. In this study, a single‐atom nanozyme platform (Cu SA‐DOX@COD) that can trigger pyroptosis is developed to activate antitumor immune responses via a gasdermin E (GSDME)‐dependent pathway. It triggered pyroptosis by catalyzing the production of reactive oxygen species (ROS) and depleting reduced glutathione through intrinsic multi‐enzyme simulated activities and providing an oxygen source for cholesterol (CHOL) oxidation. Meanwhile, the loaded CHOL oxidase not only reduces the CHOL content of tumor cells to increase cell membrane permeability and inhibit tumor cell proliferation and invasion but also oxidizes CHOL and increases the level of H2O2 in tumor cells to enhance pyroptosis. In addition, the loaded doxorubicin activated caspase‐3 to cleave GSDME and further augment pyroptosis. Consequently, Cu SA‐DOX@COD enhances tumor cell immunocompetence and reshapes the immunosuppressive TME by triggering pyroptosis caused by a ROS storm, chemotherapy, and depleting CHOL, thereby activating systemic antitumor immunity to treat PCa.

FOXA3 regulates cholesterol metabolism to compensate for low uptake during the progression of lung adenocarcinoma.

Cholesterol metabolism is vital for multiple cancer progression, while how cholesterol affects lung, a low-cholesterol tissue, for cancer metastasis and the underlying mechanism remain unclear. In this study, we found that metastatic lung adenocarcinoma cells acquire cellular dehydrocholesterol and cholesterol by endogenous cholesterol biosynthesis, instead of uptake upon cholesterol treatment. Besides, we demonstrated that exogenous cholesterol functions as signaling molecule to induce FOXA3, a key transcription factor for lipid metabolism via GLI2. Subsequently, ChIP-seq analysis and molecular studies revealed that FOXA3 transcriptionally activated Hmgcs1, an essential enzyme of cholesterol biosynthesis, to induce endogenous dehydrocholesterol and cholesterol level for membrane composition change and cell migration. Conversely, FOXA3 knockdown or knockout blocked cholesterol biosynthesis and lung adenocarcinoma metastasis in mice. In addition, the potent FOXA3 inhibitor magnolol suppressed metastatic gene programs in lung adenocarcinoma patient-derived organoids (PDOs). Altogether, our findings shed light onto unique cholesterol metabolism and FOXA3 contribution to lung adenocarcinoma metastasis.

Serum ApoB/ApoA1 ratio in patients with CHB and the occurrence of HBV related cirrhosis and HBV related hepatocellular carcinoma

Clinical research has suggested that chronic HBV infection exerts a certain effect on the occurrence of cardiovascular disease by regulating cholesterol metabolism in liver cells. High serum apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio plays a certain role in the above regulation, and it serves as a risk factor for cardiovascular disease. However, whether the ApoB/ApoA1 ratio is correlated with chronic HBV infection and its disease progression remains unclear. In accordance with the inclusion and exclusion criteria, all 378 participants administrated at Renmin Hospital of Wuhan University from March 2021 to March 2022, fell into Healthy Control (HC) group (50 participants), Hepatocellular carcinoma (HCC) group (107 patients), liver cirrhosis (LC) group (64 patients), chronic hepatitis B (CHB) group (62 patients), chronic hepatitis C (CHC) group (46 patients) and Hepatitis E Virus (HEV) group (49 patients). Serum ApoA1 and ApoB concentrations were measured at admission, and the ApoB/ApoA1 ratio was determined. The levels of laboratory parameters in the respective group were compared and ApoB/ApoA1 ratios in HCC patients and LC patients with different severity were further analyzed. ROC curves were plotted to analyze the early diagnostic ability of ApoB/ApoA1 ratio for HBV-associated HCC. Logistic regression and restricted cubic spline analysis were used to explore the correlation between ApoB/ApoA1 ratio and LC and HCC risk. A comparison was drawn in terms of ApoB/ApoA1 ratio between the groups, and the result was expressed in descending sequence: HEV group > CHB group > LC group > HCC group > CHC group > HC group, early-stage HCC < middle-stage HCC < advanced-stage HCC, Class A LC < Class B LC < Class C LC. Serum ApoB/ApoA1 ratio combined diagnosis with AFP exhibited the capability of increasing the detection efficacy and specificity of AFP for HCC and AFP-negative HCC. The incidence of LC and HCC in the respective logistic regression model showed a negative correlation with the serum ApoB/ApoA1 ratio in CHB patients (P < 0.05). After all confounding factors covered in this study were regulated, the result of the restricted cubic spline analysis suggested that in a certain range, serum ApoB/ApoA1 ratio showed an inverse correlation with the prevalence of LC or HCC in CHB patients. Serum ApoB/ApoA1 ratio in CHB patients may be conducive to identifying high-risk patients for HCC or LC, such that LC and HCC can be early diagnosed and treated.

β-sitosterol alleviates high fatty acid-induced lipid accumulation in calf hepatocytes by regulating cholesterol metabolism

A significant reduction in plasma concentration of cholesterol during early lactation is a common occurrence in high-yielding dairy cows. An insufficient synthesis of cholesterol in the liver has been linked to lipid accumulation caused by high concentrations of fatty acids during negative energy balance (NEB). As ruminant diets do not provide quantitative amounts of cholesterol for absorption, phytosterols such as β-sitosterol may serve to mitigate the shortfall in cholesterol within the liver during NEB. To gain mechanistic insights, primary hepatocytes were isolated from healthy female 1-day old calves for in vitro studies with or without 1.2 mM fatty acids (FA) to induce metabolic stress. Furthermore, hepatocytes were treated with 50 μM β-sitosterol with or without FA. Data were analyzed by one-way ANOVA with subsequent Bonferroni correction. Results revealed that calf hepatocytes treated with FA had greater content of non-esterified fatty acids (NEFA) and triacylglycerol (TAG), and greater mRNA and protein abundance of the lipid synthesis-related SREBF1 and FASN. In contrast, mRNA and protein of CPT1A (fatty acid oxidation) and the cholesterol metabolism-related targets SREBF2, HMGCR, ACAT2, APOA1, ABCA1 and ABCG5 was lower. Content of the antioxidant-related glutathione (GSH) and activities of superoxide dismutase (SOD) also was lower. Compared with FA challenge alone, 50 μM β-sitosterol led to greater mRNA and protein abundance of SREBF2, HMGCR, ACAT2 and ABCG5, and greater content of GSH and activity of SOD. In contrast, compared with the FA group, the mRNA and protein abundance of SREBF1 and ACC1 and the content of TAG and NEFA in the β-sitosterol + FA group were lower. Overall, β-sitosterol can promote cholesterol metabolism and reduce oxidative stress while reducing lipid accumulation in hepatocytes challenged with high concentrations of fatty acids.

SOAT1 regulates cholesterol metabolism to induce EMT in hepatocellular carcinoma

Cholesterol metabolism reprogramming is one of the significant characteristics of hepatocellular carcinoma (HCC). Cholesterol increases the risk of epithelial–mesenchymal transition (EMT) in cancer. Sterol O-acyltransferases 1 (SOAT1) maintains the cholesterol homeostasis. However, the exact mechanistic contribution of SOAT1 to EMT in HCC remains unclear. Here we demonstrated that SOAT1 positively related to poor prognosis of HCC, EMT markers and promoted cell migration and invasion in vitro, which was mediated by the increased cholesterol in plasmalemma and cholesterol esters accumulation. Furthermore, we reported that SOAT1 disrupted cholesterol metabolism homeostasis to accelerate tumorigenesis and development in HCC xenograft and NAFLD-HCC. Also, we detected that nootkatone, a sesquiterpene ketone, inhibited EMT by targeting SOAT1 in vitro and in vivo. Collectively, our finding indicated that SOAT1 promotes EMT and contributes to hepatocarcinogenesis by increasing cholesterol esterification, which is suppressed efficiently by nootkatone. This study demonstrated that SOAT1 is a potential biomarker and therapeutic target in NAFLD-HCC and SOAT1-targeting inhibitors are expected to be the potential new therapeutic treatment for HCC.

Abstract 2004: Sex Differences In Bile Acid Metabolism Impact Cholesterol Homeostasis And Cardiovascular Disease

Cardiovascular disease (CVD) remains the leading cause of death in the United States for both men and women, despite cholesterol-lowering drugs such as statins. Diets rich in cholesterol are well-known to contribute to disease progression. The absorption of dietary cholesterol is facilitated by liver-synthesized detergents called bile acids. We hypothesized that manipulating bile acid metabolism to reduce cholesterol absorption would result in decreased plasma cholesterol levels and protect from atherosclerosis. To alter the bile acid pool, we used liver-directed AAV-CRISPR to disrupt Cyp7a1, which catalyzes the rate-limiting step of bile acid synthesis. Consequently, we show that loss of CYP7A1 in adult male mice reduces the size of the bile acid pool. To study atherosclerosis, we co-disrupted Cyp7a1 concurrently with Low Density Lipoprotein Receptor ( Ldlr ) to induce hypercholesterolemia on a Western diet for 20 weeks. Loss of hepatic CYP7A1 in males reduced atherosclerosis and reduced cholesterol absorption. In stark contrast to what we observed in male mice, the absence of this rate limiting enzyme in female mice resulted in only a modest reduction in the bile acid pool. This blunted reduction in bile acids in female Cyp7a1 CRISPR mice was not sufficient to decrease cholesterol absorption, resulting in accumulation of cholesterol, and consequently increasing cardiovascular risk. We hypothesize that there is a female-specific mechanism to preserve bile acid production that operates in the absence of CYP7A1. We are currently in the process of testing candidate female-specific enzymes for bile acid production. These studies indicate new avenues by which female bile acid and cholesterol metabolism regulation differs from than that of males. The resulting differences in cardiovascular risk highlight the essential need for male- and female-specific personalized medicine approaches for cardiovascular disease prevention.

Towards a Unitary Hypothesis of Alzheimer's Disease Pathogenesis.

The "amyloid cascade" hypothesis of Alzheimer's disease (AD) pathogenesis invokes the accumulation in the brain of plaques (containing the amyloid-β protein precursor [AβPP] cleavage product amyloid-β [Aβ]) and tangles (containing hyperphosphorylated tau) as drivers of pathogenesis. However, the poor track record of clinical trials based on this hypothesis suggests that the accumulation of these peptides is not the only cause of AD. Here, an alternative hypothesis is proposed in which the AβPP cleavage product C99, not Aβ, is the main culprit, via its role as a regulator of cholesterol metabolism. C99, which is a cholesterol sensor, promotes the formation of mitochondria-associated endoplasmic reticulum (ER) membranes (MAM), a cholesterol-rich lipid raft-like subdomain of the ER that communicates, both physically and biochemically, with mitochondria. We propose that in early-onset AD (EOAD), MAM-localized C99 is elevated above normal levels, resulting in increased transport of cholesterol from the plasma membrane to membranes of intracellular organelles, such as ER/endosomes, thereby upregulating MAM function and driving pathology. By the same token, late-onset AD (LOAD) is triggered by any genetic variant that increases the accumulation of intracellular cholesterol that, in turn, boosts the levels of C99 and again upregulates MAM function. Thus, the functional cause of AD is upregulated MAM function that, in turn, causes the hallmark disease phenotypes, including the plaques and tangles. Accordingly, the MAM hypothesis invokes two key interrelated elements, C99 and cholesterol, that converge at the MAM to drive AD pathogenesis. From this perspective, AD is, at bottom, a lipid disorder.

Osteocytes/Osteoblasts Produce SAA3 to Regulate Hepatic Metabolism of Cholesterol.

Hypercholesterolaemia is a systemic metabolic disease, but the role of organs other than liver in cholesterol metabolism is unappreciated. The phenotypic characterization of the Tsc1Dmp1 mice reveal that genetic depletion of tuberous sclerosis complex 1 (TSC1) in osteocytes/osteoblasts (Dmp1-Cre) triggers progressive increase in serum cholesterol level. The resulting cholesterol metabolic dysregulation is shown to be associated with upregulation and elevation of serum amyloid A3 (SAA3), a lipid metabolism related factor, in the bone and serum respectively. SAA3, elicited from the bone, bound to toll-like receptor 4 (TLR4) on hepatocytes to phosphorylate c-Jun, and caused impeded conversion of cholesterol to bile acids via suppression on cholesterol 7 α-hydroxylase (Cyp7a1) expression. Ablation of Saa3 in Tsc1Dmp1 mice prevented the CYP7A1 reduction in liver and cholesterol elevation in serum. These results expand the understanding of bone function and hepatic regulation of cholesterol metabolism and uncover a potential therapeutic use of pharmacological modulation of SAA3 in hypercholesterolaemia.

Intestinal FGF15 regulates bile acid and cholesterol metabolism but not glucose and energy balance.

Fibroblast growth factor 15/19 (FGF15/19, mouse/human ortholog) is expressed in the ileal enterocytes of the small intestine and released postprandially in response to bile acid absorption. Previous reports of FGF15-/- mice have limited our understanding of gut-specific FGF15's role in metabolism. Therefore, we studied the role of endogenous gut-derived FGF15 in bile acid, cholesterol, glucose, and energy balance. We found that circulating levels of FGF19 were reduced in individuals with obesity and comorbidities, such as type 2 diabetes and metabolic dysfunction-associated fatty liver disease. Gene expression analysis of ileal FGF15-positive cells revealed differential expression during the obesogenic state. We fed standard chow or a high-fat metabolic dysfunction-associated steatohepatitis-inducing diet to control and intestine-derived FGF15-knockout (FGF15INT-KO) mice. Control and FGF15INT-KO mice gained similar body weight and adiposity and did not show genotype-specific differences in glucose, mixed meal, pyruvate, and glycerol tolerance. FGF15INT-KO mice had increased systemic bile acid levels but decreased cholesterol levels, pointing to a primary role for gut-derived FGF15 in regulating bile acid and cholesterol metabolism when exposed to obesogenic diet. These studies show that intestinal FGF15 plays a specific role in bile acid and cholesterol metabolism regulation but is not essential for energy and glucose balance.

Cholesterol metabolism: physiological versus pathological aspects in intracerebral hemorrhage

Cholesterol is an important component of plasma membranes and participates in many basic life functions, such as the maintenance of cell membrane stability, the synthesis of steroid hormones, and myelination. Cholesterol plays a key role in the establishment and maintenance of the central nervous system. The brain contains 20% of the whole body’s cholesterol, 80% of which is located within myelin. A huge number of processes (e.g., the sterol regulatory element-binding protein pathway and liver X receptor pathway) participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis, intracellular transport, and efflux. Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences. Therefore, we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases. Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype, with high mortality and morbidity. Historical cholesterol levels are associated with the risk of intracerebral hemorrhage. Moreover, secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation, such as neuroinflammation, demyelination, and multiple types of programmed cell death. Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage. In this paper, we review normal cholesterol metabolism in the central nervous system, the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage, and the links between cholesterol metabolism and cell death. We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.

Mechanism of Tougu Xiaotong Capsules in delaying degeneration of osteoarthritis by regulating cholesterol metabolism in chondrocytes through lncRNA MALAT1

From the perspective of lncRNA MALAT1 regulating cholesterol metabolism in chondrocytes, this paper explores the effect and mechanism of Tougu Xiaotong Capsules(TGXTC) in delaying the degeneration of osteoarthritis. After one week of adaptive feeding, 48(8-week-old) C57BL/6 mice were randomly divided into a blank group(12 mice) and a model group(36 mice) by random number table method. The mice in the model group were anesthetized by inhalation of 5% isoflurane, and the OA model was induced by Hulth method. The experiment randomly divided the mice into a model group(12 mice), a drug-positive group(taururso-deoxycholic acid)(12 mice), and a TGXTC group(12 mice). The drug-positive group was given 500 mg·kg~(-1) taurodeoxycholic acid by intragastric administration. TGXTC group was given TGXTC 368 mg·kg~(-1) by gavage. The blank group and model group were given the same amount of normal saline for four weeks. After the intervention, the mice in each group were killed under anesthesia, and the knee cartilage tissue was separated and collected. The morphologic changes of knee cartilage were observed. The level of lncRNA MALAT1 in the cartilage tissue was detected by real-time PCR. The protein expressions of ABCA1, ApoA1, LXRβ, CHOP, and caspase-3 in mouse articular cartilage were detected by Western blot. Lentivirus-coated plasmid was used to transfect mouse chondrocytes with sh-MALAT1. The gene levels of lncRNA MALAT1 in mouse chondrocytes transfected with sh-MALAT1 were detected by real-time PCR. Western blot was used to detect the effect of TGXTC on the protein content of ABCA1, ApoA1, LXRβ, CHOP, and caspase-3 in thapsigargin(TG)-induced mouse chondrocytes after lncRNA MALAT1 knockdown. Flow cytometry was used to detect the effect of TGXTC on apoptosis of TG-induced mouse chondrocytes after lncRNA MALAT1 knockdown. The results of HE and saffranine O staining showed that compared with the model group, the structure of the cartilage layer was basically intact; the damage degree of joint structure was significantly improved, and the cartilage matrix was significantly enhanced by saffranine O staining in the TGXTC group and drug-positive group. Compared with the model group, the lncRNA MALAT1 level was significantly decreased in the TGXTC group and drug-positive group. Compared with the model group, the protein content of ABCA1, ApoA1, and LXRβ was significantly increased, while that of CHOP and caspase-3 in the TGXTC group and drug-positive group significantly decreased. Compared with the TG group, the lncRNA MALAT1 level in the TG+sh-MALAT1 group was decreased. The lncRNA MALAT1 level in the TG+sh-MA-LAT1+TGXTC group was increased compared with the TG+TGXTC group. Western blot results showed that compared with the model group, protein expressions of ABCA1, ApoA1, LXRβ, CHOP, and caspase-3 in the TGXTC group were significantly decreased, after lncRNA MALAT1 knockdown, the regulation and apoptosis of ABCA1, ApoA1, LXRβ, CHOP, and caspase-3 in TG-induced mouse chondrocytes were weakened by TGXTC. TGXTC can improve the disorder of cholesterol metabolism in OA chondrocytes and delay OA degeneration, which is closely related to the regulation of lncRNA MALAT1.

Molecular Mechanisms Associated with the Development of the Metritis Complex in Dairy Cattle.

The metritis complex (MC), a group of post-partum uterine diseases, is associated with increased treatment costs and reduced milk yield and fertility. The goal of this study was to identify genetic variants, genes, or genomic regions that modulate MC disease. A genome-wide association study was performed using a single-locus mixed linear model of 1967 genotypes (624,460 SNPs) and metritis complex records. Then, in-silico functional analyses were performed to detect biological mechanisms and pathways associated with the development of MC. The ATP8A2, COX16, AMN, and TRAF3 genes, located on chromosomes 12, 10, and 21, were associated with MC at p ≤ 0.0001. These genes are involved in the regulation of cholesterol metabolism in the stromal tissue of the uterus, which can be directly associated with the mode of transmission for pathogens causing the metritis complex. The modulation of cholesterol abundance alters the efficiency of virulence factors and may affect the susceptibility of the host to infection. The SIPA1L1, DEPDC5, and RNF122 genes were also significantly associated with MC at p ≤ 0.0001 and are involved in the PI3k-Akt pathway, responsible for activating the autophagic processes. Thus, the dysregulation of these genes allows for unhindered bacterial invasion, replication, and survival within the endometrium.

Abstract 3085: Cholesterol sulfotransferase SULT2B1b suppresses prostate tumor growth and regulates cholesterol metabolism in prostate cancer cells

Abstract Prostate cancer (PrCa) ranks as the second leading cause of cancer death in males in the United States. The 5-year survival rate drops drastically from 100% in patients with early-stage confined PrCa to 30% in those with advanced metastatic PrCa. Patients with advanced PrCa face limited long-term treatment options, often developing resistance to androgen-deprivation therapy and chemotherapy. Identifying and targeting pivotal molecules or pathways in advanced PrCa can substantially enhance patient survival. Our previous findings unveiled an inverse relationship between cholesterol sulfotransferase SULT2B1b and the severity of human PrCa. The highest levels of SULT2B1b were observed in the epithelium of normal prostates, with a progressive decrease as cancer advanced. The lowest levels were found in the most advanced metastatic samples. This study aims to determine whether SULT2B1b performs any active and critical functions in PrCa progression and assess whether it regulates cholesterol metabolism in PrCa cells. We generated SULT2B1b knockout (KO) clones from mouse PrCa cell line MyC-CaP and established inducible SULT2B1b overexpression lines from androgen receptor (AR)+ LNCaP and AR- PC3 human PrCa cells. These modified mouse and human cells were implanted into syngeneic FVB mice and immunodeficient NRG mice, respectively. MyC-CaP KO cells formed significantly larger tumors compared to parental cells, accompanied by reduced survival rates. In contrast, both LNCaP and PC3 tumors with induced SULT2B1b exhibited smaller sizes compared to control tumors, leading to improved survival rates. To investigate the impact of SULT2B1b on cholesterol metabolism and the underlying mechanisms behind SULT2B1b-regulated tumor growth, we examined genes related to lipoprotein signaling and cholesterol metabolism in MyC-CaP SULT2B1b KO cells using PCR arrays and qRT-PCR. Genes responsible for cholesterol uptake and synthesis (e.g. Ldlr, Cyp51, Sorl1, Pcsk9 and Insig1) were among the top upregulated genes, while genes controlling cholesterol efflux (e.g. Abca1) and esterification (e.g. Soat1 and Soat2) were downregulated in KO cells. Consistent with these gene expression patterns, intracellular cholesterol levels significantly increased in KO cells. Interestingly, although SULT2B1b did not affect cell proliferation under normal conditions, KO cells exhibited faster growth than parental cells when cultured in lipid-depleted or charcoal-stripped media, possibly due to altered intracellular cholesterol levels. In summary, these findings align with the expression pattern of SULT2B1b in human PrCa, demonstrating that SULT2B1b inhibits tumor growth, whereas its removal promotes tumor growth. This suggests SULT2B1b may serve as a critical tumor suppressor in PrCa. Its modulation of tumor growth may occur through the regulation of cholesterol metabolism. Citation Format: Jiang Yang, Dilinaer Wusiman, Timothy L. Ratliff. Cholesterol sulfotransferase SULT2B1b suppresses prostate tumor growth and regulates cholesterol metabolism in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3085.

Abstract 632: AKT supports cancer cell survival through modulation of cholesterol homeostasis

Abstract AKT is a critical effector kinase downstream of PI3K activation. It has been shown to regulate a variety of cellular processes important for homeostasis, many of which are altered during oncogenesis. Not surprisingly, AKT is constitutively activated in a large number of human cancers, and has consequently been pursued as a therapeutic target for many years. Some of these functions are directly involved in establishing one or more hallmarks of cancer including sustained proliferative signaling, resisting cell death, and reprogrammed cellular metabolism. Although AKT inhibitors have demonstrated clinical benefit (most recently in a phase III trial) in combination with other therapies, single agent activity has been limited to a few cases with relatively infrequent activating AKT1 mutations. We have previously proposed that the clear disconnect between the high frequency of AKT activation in cancer and the lack of broad clinical activity of AKT inhibitors is due, at least in part, to the inability of existing compounds to block non-catalytic functions. We have found that while allosteric AKT inhibitors are partial suppressors of these functions, ATP-competitive inhibitors fail to suppress these functions to any significant extent. We now provide evidence that one important non-catalytic function of AKT that impinges on its oncogenic function is the regulation of cholesterol metabolism. We show that AKT represses the activation of LXRβ, thereby maintaining a level of intracellular cholesterol that is compatible with cancer cell viability, and that this repression does not require catalytic activity. Consistently, we find that allosteric AKT inhibitors induce LXRβ activation, and that genetic or pharmacological suppression of LXRβ function limit the growth inhibiting effects of these drugs. Our findings suggest that through a kinase-independent activity, AKT may play a significant role in the regulation of cholesterol homeostasis, and that the therapeutic potential of AKT inhibitors could be broaden by optimizing their ability to interfere with these functions. Citation Format: Igor Vivanco, Khine N. Myint, Sean Wallace, Glorianne Lazaro, Eleftherios Kostaras, Nikolaos Palaskas. AKT supports cancer cell survival through modulation of cholesterol homeostasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 632.

Abstract 364: Targeting LILRB1 to sensitize human myeloma to ferroptosis through disrupting cholesterol homeostasis

Abstract Multiple myeloma (MM) is a hematologic malignancy characterized by the uncontrolled clonal proliferation of plasma cells in the bone marrow (BM). Despite the demonstrated benefits of novel therapies, relapses are frequent, and acquired resistance to MM treatment eventually emerges in most, if not all, patients. MM patients who suffer more aggressive progression usually result in poorer survival. The genes driving such unfavored outcomes in MM have not been fully understood. Therefore, there is an urgent need to identify the genes and mechanisms that contribute to the aggressive behaviors of MM in order to develop improved therapeutic strategies for the disease. To discover new potential therapeutic targets for MM patients, we analyzed gene-profiling data of MM patients and identified leukocyte immunoglobulin-like receptor B1 (LILRB1), a transmembrane receptor conducting negative immune response, as one of the top-ranked genes associated with poor prognosis. LILRB1 on immune cells was reported to bind to its ligand, b2-microglobulin, on tumor cells. This interaction leads to immune suppression responses in various immune cells. However, the function of tumor-derived LILRB1 in tumor biology remains unclear and the role of LILRB1 in MM has been poorly studied. Our further analysis of the patient data demonstrated that MM patients with high expression of LILRB1 are closely related to higher MM recurrence rates, advanced stages, and lower survival rates, indicating that LILRB1 is an important player in MM pathogenesis and thus a promising target for MM therapy. Interestingly, RNA-seq data of human MM cells from the BM of MM-bearing mice showed that knockdown (KD) of LILRB1 activated cholesterol metabolism- and ferroptosis-related pathways in murine BM. Moreover, KD of LILRB1 significantly impaired tumor progression in murine models. Consistently, in vitro experiments also demonstrated that LILRB1 protected MM cells from ferroptosis inducer-caused lipid ROS and ferroptotic cell death, indicating that LILRB1 promotes the progression of MM cells by protecting them from ferroptosis. Further study were then conducted to reveal the underlying mechanism. LC-MS/MS analysis followed by co-IP demonstrated that LDLRAP1, an adaptor protein that interacts with LDLR, bound with LILRB1 and formed a complex together with LDLR. KD of LILRB1 inhibited LDL uptake by disrupting the interaction between LDLR and LDLRAP1 and triggering the compensatory cholesterol synthesis by upregulating the expression of SQLE that converted squalene to (S)-2,3-epoxysqualene. With less squalene to protect MM cells from lipid peroxidation, MM cells were more susceptible to the induction of ferroptosis. Thus, this study uncovers a novel function of LILRB1 in regulating cholesterol metabolism and protecting MM cells from ferroptosis during MM progression and implicates LILRB1 as a promising therapeutic target for MM patients. Citation Format: Miao Xian, Qing Yi, Qiang Wang, Liuling Xiao, Ling Zhong, chuanchao zhang, yabo Li, Jianfei Qian. Targeting LILRB1 to sensitize human myeloma to ferroptosis through disrupting cholesterol homeostasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 364.

Liver X Receptors (LXRs) in cancer-an Eagle's view on molecular insights and therapeutic opportunities.

Cancer has become a serious health burden that results in high incidence and mortality rates every year, mainly due to various molecular alterations inside the cell. Liver X receptors (LXRs) dysregulation is one among them that plays a vital role in cholesterol metabolism, lipid metabolism and inflammation and also plays a crucial role in various diseases such as obesity, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular diseases, Type 2 diabetes, osteoporosis, and cancer. Studies report that the activation of LXRs inhibits cancer growth by inhibiting cellular proliferation, inducing apoptosis and autophagy, regulating cholesterol metabolism, various signalling pathways such as Wnt, and PI3K/AKT, modulating the expression levels of cell-cycle regulators, and promoting antitumor immunity inside the tumor microenvironment. In this review, we have discussed the role, structure, and functions of LXRs and also summarized their ligands along with their mechanism of action. In addition, the role of LXRs in various cancers, tumor immunity and tumor microenvironment (TME) along with the importance of precision medicine in LXR-targeted therapies has been discussed to emphasize the LXRs as potent targets for the development of novel cancer therapeutics.