Cholesterol and beyond - The role of the mevalonate pathway in cancer biology

Effects of Lipophilic Statins on Cell Viability and Tissue Factor Expression in Canine Haemangiosarcoma Cells

Canine haemangiosarcoma (HSA) is a highly aggressive cancer often associated with coagulation abnormalities. Statins, inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) clinically prescribed for hypercholesterolemia, are also believed to possess antitumour and anticoagulant properties by inhibiting downstream Akt activation. Akt phosphorylation is involved in the mechanism of the antitumour and tissue factor (TF)-lowering effects of statins. In the present study, we aimed to investigate whether statins could inhibit cell viability while concurrently inducing anticoagulant properties by regulating the expression of TFs in canine HSA cells. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), we initially exclusively detected HMGCR mRNA expression in canine HSA tissues and cell lines but not in normal cephalic vein and spleen tissues. Moreover, treatment with lipophilic statins, including atorvastatin, fluvastatin, and simvastatin, inhibited cell viability in a concentration-dependent manner and decreased TF expression both at the mRNA and protein levels, as evidenced by cell viability assays, RT-qPCR, and immunoblotting, respectively. Further investigation using cell viability assays and flow cytometry revealed that simvastatin decreased Akt phosphorylation, and MK-2206, a specific Akt inhibitor, mirrored the effect of simvastatin on cell viability and cell cycle arrest. However, MK-2206 exhibited different effects on TF expression depending on the cell type, indicating that Akt phosphorylation may not consistently regulate TF expression. Overall, this study provides insights into the potential therapeutic use of statins in targeting tumour growth and coagulation abnormalities in canine HSA. Further research is warranted to fully elucidate the underlying mechanisms and clinical applications of statins in canine HSA treatment.

Targeting the mevalonate pathway enhances the efficacy of 5-fluorouracil by regulating pyroptosis

The 5-fluorouracil (5-FU)-based chemotherapy regimen is a primary strategy for treating pancreatic cancer (PC). However, challenges related to 5-FU resistance persist. Investigating the mechanisms of 5-FU resistance and identifying a clinically viable therapeutic strategy are crucial for improving the prognosis of PC. Here, through clinical samples analysis, we found that the expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting enzyme in mevalonate metabolism, is negatively correlated with the efficacy of 5-FU treatment. There is a significant correlation between HMGCR and the pyroptosis marker gasdermin D (GSDMD), and the HMGCR inhibitor simvastatin can significantly inhibit the activation of pyroptosis signaling. The exogenous addition of geranylgeranyl pyrophosphate (GGPP), a key metabolite of the mevalonate pathway, can significantly reduce sensitivity to 5-FU, and simvastatin combined with 5-FU demonstrates a strong synergistic effect. Furthermore, in organoid models and genetically engineered mice with spontaneous PC, the combination of simvastatin and 5-FU significantly inhibits tumor growth. In conclusion, our study reveals the critical role of the mevalonate pathway in 5-FU resistance and proposes a clinically feasible combination therapy strategy.

Statin use and ovarian cancer outcomes

INTRODUCTION

Ovarian cancer contributed to 13,270 patient deaths in the United States during 2023 and is considered the most aggressive gynecologic malignancy. While surgery, chemotherapy and targeted medications have improved ovarian cancer patient outcomes, novel therapies that further bolster treatment efficacy without compromising toxicity represent an unmet clinical need.

AREAS COVERED

In the current review, we assessed the reported studies involving statin use and ovarian cancer outcomes; a preponderance of the evidence indicated that statins confer a survival benefit in ovarian cancer, especially for patients who underwent treatment post-diagnosis and for a prolonged interval.

EXPERT OPINION

The evidence involving a potential survival benefit from statin use in ovarian cancer remains controversial, especially with hydrophilic statins (e.g. pravastatin). While statin users may exhibit better ovarian cancer survival outcomes than non-statin users, additional research should evaluate the putative clinical benefits of statins in ovarian cancer via randomized controlled trials.

MicroRNA-146b-5p/FDFT1 mediates cisplatin sensitivity in bladder cancer by redirecting cholesterol biosynthesis to the non-sterol branch

Chemotherapy against muscle-invasive bladder cancer is increasingly challenged by the prevalence of chemoresistance. The cholesterol biosynthesis pathway has garnered attention in studies of chemoresistance, but conflicting clinical and molecular findings necessitate a clearer understanding of its underlying mechanisms. Recently, we identified farnesyl-diphosphate farnesyltransferase 1 (FDFT1)-the first specific gene in this pathway-as a tumor suppressor and chemoresistance modulator. Raman spectroscopy revealed higher levels of FDFT1-related metabolites in chemotherapy-sensitive bladder cancer tissue compared to resistant tissue; however, this observation lacks mechanistic insight. FDFT1 expression was reduced in our cisplatin-resistant bladder cancer cells (T24R) compared to parental cisplatin-sensitive cells (T24). Using functional knockdown and ectopic overexpression in T24/T24R cells, we mechanistically demonstrate the pathway through which FDFT1 mediates cisplatin sensitivity in bladder cancer cells. Bioinformatics analysis and rescue experiments showed that microRNA-146b-5p directly targets and downregulates FDFT1, reducing the cisplatin sensitivity of T24 cells, which can be restored by forced FDFT1 expression. Further investigation into the downstream cholesterol pathway revealed that FDFT1 suppression redirects its substrate toward the non-sterol branch of the pathway, as evidenced by the upregulation of non-sterol branch-associated genes and a reduced total cholesterol level in the sterol branch. Since the non-sterol pathway leads to the prenylation of isoprenoids and activation of Ras and Rho family proteins involved in cancer progression and chemoresistance, our findings suggest that redirection of the cholesterol biosynthesis pathway is a key mechanism underlying FDFT1-mediated cisplatin resistance in bladder cancer. The miR-146b-5p/FDFT1 axis represents a promising target for overcoming chemoresistance in bladder cancer.

Assessing the effects of HMGCR, LPL, and PCSK9 inhibition on sleep apnea: Mendelian randomization analysis of drug targets

To investigate the use of lipid-lowering drugs and abnormal serum lipid levels in patients at risk of sleep apnea syndrome. Three types of Mendelian randomization (MR) analyses were used. First, a 2-sample Mendelian randomization (TSMR) analysis was used to investigate the association between sleep apnea syndrome risk and serum lipid levels. Multivariate Mendelian randomization (MVMR) analysis was subsequently used to investigate the effects of confounding variables on SAS incidence of sleep apnea syndrome. Finally, drug-target Mendelian randomization (DMR) analysis was used to analyze the association between lipid-lowering drug use and sleep apnea syndrome risk. According to the TSMR analysis, the serum HDL-C concentration was negatively correlated with sleep apnea syndrome (OR = 0.904; 95% CI = 0.845-0.967; P = .003). Serum TG levels were positively correlated with sleep apnea syndrome (OR = 1.081; 95% CI = 1.003-1.163; P = .039). The association between serum HDL-C levels and sleep apnea syndrome in patients with MVMR was consistent with the results in patients with TSMR (OR = 0.731; 95% CI = 0.500-1.071; P = 3.94E-05). According to our DMR analysis, HMGCR and PCSK9, which act by lowering serum LDL-C levels, were inversely associated with the risk of sleep apnea syndrome (OR = 0.627; 95% CI = 0.511-0.767; P = 6.30E-06) (OR = 0.775; 95% CI = 0.677-0.888; P = .0002). LPL, that lowered serum TG levels, was positively associated with the risk of sleep apnea syndrome (OR = 1.193; 95% CI = 1.101-1.294; P = 1.77E-05). Our analysis suggested that high serum HDL-C levels may reduce the risk of sleep apnea syndrome. Low serum TG levels have a protective effect against sleep apnea syndrome. The DMR results suggested that the use of HMGCR lipid-lowering drugs (such as statins) and PCSK9 inhibitors has a protective effect against sleep apnea syndrome. However, LPL-based lipid-lowering drugs may increase the risk of sleep apnea syndrome.

Statins in the Cause and Prevention of Cancer: Confounding by Indication and Mediation by Rhabdomyolysis and Phosphate Toxicity

Statins are drugs used in cardiovascular pharmacotherapy to decrease hypercholesterolemia and lower the risk of atherosclerosis. Statins also increase the risk of rhabdomyolysis, which is often minimized in comparison with large relative risk reductions of cardiovascular disease reported in clinical trials. By contrast, absolute risk reductions of cardiovascular disease are often clinically insignificant and unreported in statin clinical trials. Additionally, cytotoxic effects of statins inhibit cancer cell proliferation and reduce cancer risk, but other studies found that statins are carcinogenic. Due to an inverse association between incidence of cancer and atherosclerosis, the indication to prescribe statins likely biases the association of statins with cancer prevention. Dietary patterns associated with atherosclerosis and cancer contain inverse amounts of cholesterol and phosphate, an essential mineral that stimulates tumorigenesis. Accordingly, lower cancer risk is associated with high dietary cholesterol intake and increased risk of atherosclerosis. Furthermore, serum is exposed to excessive inorganic phosphate that could increase cancer risk as rhabdomyolysis induced by statins releases phosphate from skeletal muscle breakdown. Increased risk of comorbid conditions associated with statins may share the mediating factor of phosphate toxicity. More research is warranted on statins in the cause and prevention of cancer.

The mevalonate pathway contributes to breast primary tumorigenesis and lung metastasis

The mevalonate pathway plays an important role in breast cancer and other tumor types. However, many issues remain obscure as yet regarding its mechanism of regulation and action. In the present study, we report that the expression of mevalonate pathway enzymes is mediated by the RHO guanosine nucleotide exchange factors VAV2 and VAV3 in a RAC1- and sterol regulatory element-binding factor (SREBF)-dependent manner in breast cancer cells. Furthermore, in vivo tumorigenesis experiments indicated that the two most upstream steps of this metabolic pathway [3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR)] are important for primary tumorigenesis, angiogenesis, and cell survival in breast cancer cells. HMGCR, but not HMGCS1, is also important for the extravasation and subsequent fitness of breast cancer cells in the lung parenchyma. Genome-wide expression analyses revealed that HMGCR influences the expression of gene signatures linked to proliferation, metabolism, and immune responses. The HMGCR-regulated gene signature predicts long-term tumor recurrence but not metastasis in cohorts of nonsegregated and chemotherapy-resistant breast cancer patients. These results reveal a hitherto unknown, VAV-catalysis-dependent mechanism involved in the regulation of the mevalonate pathway in breast cancer cells. They also identify specific mevalonate-pathway-dependent processes that contribute to the malignant features of breast cancer cells.

Therapeutic targeting of voltage-gated sodium channel NaV1.7 for cancer metastasis

This review focuses on the expression and function of voltage-gated sodium channel subtype NaV1.7 in various cancers and explores its impact on the metastasis driving cell functions such as proliferation, migration, and invasiveness. An overview of its structural characteristics, drug binding sites, inhibitors and their likely mechanisms of action are presented. Despite the lack of clarity on the precise mechanism by which NaV1.7 contributes to cancer progression and metastasis; many studies have suggested a connection between NaV1.7 and proteins involved in multiple signaling pathways such as PKA and EGF/EGFR-ERK1/2. Moreover, the functional activity of NaV1.7 appears to elevate the expression levels of MACC1 and NHE-1, which are controlled by p38 MAPK activity, HGF/c-MET signaling and c-Jun activity. This cascade potentially enhances the secretion of extracellular matrix proteases, such as MMPs which play critical roles in cell migration and invasion activities. Furthermore, the NaV1.7 activity may indirectly upregulate Rho GTPases Rac activity, which is critical for cytoskeleton reorganization, cell adhesion, and actin polymerization. The relationship between NaV1.7 and cancer progression has prompted researchers to investigate the therapeutic potential of targeting NaV1.7 using inhibitors. The positive outcome of such studies resulted in the discovery of several inhibitors with the ability to reduce cancer cell migration, invasion, and tumor growth underscoring the significance of NaV1.7 as a promising pharmacological target for attenuating cancer cell proliferation and metastasis. The research findings summarized in this review suggest that the regulation of NaV1.7 expression and function by small molecules and/or by genetic engineering is a viable approach to discover novel therapeutics for the prevention and treatment of metastasis of cancers with elevated NaV1.7 expression.

Thonzonium bromide inhibits progression of malignant pleural mesothelioma through regulation of ERK1/2 and p38 pathways and mitochondrial uncoupling

BACKGROUND

Malignant Pleural Mesothelioma (MPM) is a rare malignancy with a poor prognosis. Current therapies are unsatisfactory and novel cures are urgently needed. In a previous drug screening, we identified thonzonium bromide (TB) as one of the most active compounds against MPM cells. Since the biological effects of TB are poorly known, in this work we departed from some hints of previous studies and investigated several hypotheses. Moreover, we evaluated the efficacy of TB in an in vivo xenograft rodent model.

METHODS

In vitro assessment was made on five MPM (Mero-14, Mero-25, Ren, NCI-H28, MSTO-211H) and one SV40-immortalized mesothelial cell line (MeT-5A). We evaluated TB ability to affect proliferation, apoptosis, mitochondrial functions and metabolism, and the mevalonate pathway. In vivo assay was carried out on MPM-xenograft NOD-SCID mice (4 mg/kg delivered intraperitoneally, twice a week for 4 weeks) and the overall survival was analysed with Kaplan-Meier curves.

RESULTS

After TB treatment, we observed the suppression of ERK 1/2 phosphorylation, the increase of BAX expression and p38 phosphorylation. TB affected Ca2+ homeostasis in both mitochondrial and cytosolic compartments, it regulated the mitochondrial functioning, respiration, and ATP production as well as the mevalonate pathway. The in vivo study showed an increased overall survival for TB treated group vs. vehicle control group (P = 0.0076).

CONCLUSIONS

Both in vitro and in vivo results confirmed the effect of TB on MPM and unravelled novel targets with translational potential.

Nomogram incorporating preoperative pan-immune-inflammation value and monocyte to high-density lipoprotein ratio for survival prediction in patients with colorectal cancer: a retrospective study

OBJECTIVE

Using the preoperative pan-immune-inflammation value (PIV) and the monocyte to high-density lipoprotein ratio (MHR) to reflect inflammation, immunity, and cholesterol metabolism, we aim to develop and visualize a novel nomogram model for predicting the survival outcomes in patients with colorectal cancer (CRC).

METHODS

A total of 172 patients with CRC who underwent radical resection were retrospectively analyzed. Survival analysis was conducted after patients were grouped according to the optimal cut-off values of PIV and MHR. Univariate and multivariate analyses were performed using Cox proportional hazards regression to screen the independent prognostic factors. Based on these factors, a nomogram was constructed and validated.

RESULTS

The PIV was significantly associated with tumor location (P < 0.001), tumor maximum diameter (P = 0.008), and T stage (P = 0.019). The MHR was closely related to gender (P = 0.016), tumor maximum diameter (P = 0.002), and T stage (P = 0.038). Multivariate analysis results showed that PIV (Hazard Ratio (HR) = 2.476, 95% Confidence Interval (CI) = 1.410-4.348, P = 0.002), MHR (HR = 3.803, 95%CI = 1.609-8.989, P = 0.002), CEA (HR = 1.977, 95%CI = 1.121-3.485, P = 0.019), and TNM stage (HR = 1.759, 95%CI = 1.010-3.063, P = 0.046) were independent prognostic indicators for overall survival (OS). A nomogram incorporating these variables was developed, demonstrating robust predictive accuracy for OS. The area under the curve (AUC) values of the predictive model for 1-, 2-, and 3- year are 0.791,0.768,0.811, respectively. The calibration curves for the probability of survival at 1-, 2-, and 3- year presented a high degree of credibility. Furthermore, Decision curve analysis (DCA) for the probability of survival at 1-, 2-, and 3- year demonstrate the significant clinical utility in predicting survival outcomes.

CONCLUSION

Preoperative PIV and MHR are independent risk factors for CRC prognosis. The novel developed nomogram demonstrates a robust predictive ability, offering substantial utility in facilitating the clinical decision-making process.

Lovastatin-Induced Mitochondrial Oxidative Stress Leads to the Release of mtDNA to Promote Apoptosis by Activating cGAS-STING Pathway in Human Colorectal Cancer Cells

Statins are 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitors widely used in the treatment of hyperlipidemia. The inhibition of HMG-CoA reductase in the mevalonate pathway leads to the suppression of cell proliferation and induction of apoptosis. The cyclic GMP-AMP synthase (cGAS) stimulator of the interferon genes (STING) signaling pathway has been suggested to not only facilitate inflammatory responses and the production of type I interferons (IFN), but also activate other cellular processes, such as apoptosis. It has not been studied, however, whether cGAS-STING activation is involved in the apoptosis induced by statin treatment in human colorectal cancer cells. In this study, we reported that lovastatin impaired mitochondrial function, including the depolarization of mitochondrial membrane potential, reduction of oxygen consumption, mitochondrial DNA (mtDNA) integrity, and mtDNA abundance in human colorectal cancer HCT116 cells. The mitochondrial dysfunction markedly induced ROS production in mitochondria, whereas the defect in mitochondria respiration or depletion of mitochondria eliminated reactive oxygen species (ROS) production. The ROS-induced oxidative DNA damage by lovastatin treatment was attenuated by mitochondrial-targeted antioxidant mitoquinone (mitoQ). Upon DNA damage, mtDNA was released into the cytosol and bound to DNA sensor cGAS, thus activating the cGAS-STING signaling pathway to trigger a type I interferon response. This effect was not activated by nuclear DNA (nuDNA) or mitochondrial RNA, as the depletion of mitochondria compromised this effect, but not the knockdown of retinoic acid-inducible gene-1/melanoma differentiation-associated protein 5 (RIG-I/MDA5) adaptor or mitochondrial antiviral signaling protein (MAVS). Moreover, lovastatin-induced apoptosis was partly dependent on the cGAS-STING signaling pathway in HCT116 cells as the knockdown of cGAS or STING expression rescued cell viability and mitigated apoptosis. Similarly, the knockdown of cGAS or STING also attenuated the antitumor effect of lovastatin in the HCT116 xenograft model in vivo. Our findings suggest that lovastatin-induced apoptosis is at least partly mediated through the cGAS-STING signaling pathway by triggering mtDNA accumulation in the cytosol in human colorectal cancer HCT116 cells.

Overcoming statin resistance in prostate cancer cells by targeting the 3-hydroxy-3-methylglutaryl-CoA-reductase

Prostate cancer is the most prevalent malignancy in men. While diagnostic and therapeutic interventions have substantially improved in recent years, disease relapse, treatment resistance, and metastasis remain significant contributors to prostate cancer-related mortality. Therefore, novel therapeutic approaches are needed. Statins are inhibitors of the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway which plays an essential role in cholesterol homeostasis. Numerous preclinical studies have provided evidence for the pleiotropic antitumor effects of statins. However, results from clinical studies remain controversial and have shown substantial benefits to even no effects on human malignancies including prostate cancer. Potential statin resistance mechanisms of tumor cells may account for such discrepancies. In our study, we treated human prostate cancer cell lines (PC3, C4-2B, DU-145, LNCaP) with simvastatin, atorvastatin, and rosuvastatin. PC3 cells demonstrated high statin sensitivity, resulting in a significant loss of vitality and clonogenic potential (up to - 70%; p < 0.001) along with an activation of caspases (up to 4-fold; p < 0.001). In contrast, C4-2B and DU-145 cells were statin-resistant. Statin treatment induced a restorative feedback in statin-resistant C4-2B and DU-145 cells through upregulation of the HMGCR gene and protein expression (up to 3-folds; p < 0.01) and its transcription factor sterol-regulatory element binding protein 2 (SREBP-2). This feedback was absent in PC3 cells. Blocking the feedback using HMGCR-specific small-interfering (si)RNA, the SREBP-2 activation inhibitor dipyridamole or the HMGCR degrader SR12813 abolished statin resistance in C4-2B and DU-145 and induced significant activation of caspases by statin treatment (up to 10-fold; p < 0.001). Consistently, long-term treatment with sublethal concentrations of simvastatin established a stable statin resistance of a PC3SIM subclone accompanied by a significant upregulation of both baseline as well as post-statin HMGCR protein (gene expression up to 70-fold; p < 0.001). Importantly, the statin-resistant phenotype of PC3SIM cells was reversible by HMGCR-specific siRNA and dipyridamole. Our investigations reveal a key role of a restorative feedback driven by the HMGCR/SREBP-2 axis in statin resistance mechanisms of prostate cancer cells.

Statins as anti-tumor agents: A paradigm for repurposed drugs

BACKGROUND

Statins, frequently prescribed medications, work by inhibiting the rate-limiting enzyme HMG-CoA reductase (HMGCR) in the mevalonate pathway to reduce cholesterol levels. Due to their multifaceted benefits, statins are being adapted for use as cost-efficient, safe and effective anti-cancer treatments. Several studies have shown that specific types of cancer are responsive to statin medications since they rely on the mevalonate pathway for their growth and survival.

RECENT FINDINGS

Statin are a class of drugs known for their potent inhibition of cholesterol production and are typically prescribed to treat high cholesterol levels. Nevertheless, there is growing interest in repurposing statins for the treatment of malignant neoplastic diseases, often in conjunction with chemotherapy and radiotherapy. The mechanism behind statin treatment includes targeting apoptosis through the BCL2 signaling pathway, regulating the cell cycle via the p53-YAP axis, and imparting epigenetic modulations by altering methylation patterns on CpG islands and histone acetylation by downregulating DNMTs and HDACs respectively. Notably, some studies have suggested a potential chemo-preventive effect, as decreased occurrence of tumor relapse and enhanced survival rate were reported in patients undergoing long-term statin therapy. However, the definitive endorsement of statin usage in cancer therapy hinges on population based clinical studies with larger patient cohorts and extended follow-up periods.

CONCLUSIONS

The potential of anti-cancer properties of statins seems to reach beyond their influence on cholesterol production. Further investigations are necessary to uncover their effects on cancer promoting signaling pathways. Given their distinct attributes, statins might emerge as promising contenders in the fight against tumorigenesis, as they appear to enhance the efficacy and address the limitations of conventional cancer treatments.

Tumour cell-expressed PD-L1 reprograms lipid metabolism via EGFR/ITGB4/SREBP1c signalling in liver cancer

Background & Aims

The programmed death-ligand 1 (PD-L1) is a major co-inhibitory checkpoint factor that controls T-cell activities in tumours. PD-L1 is expressed on immune cells and tumour cells. Whether tumour cell-expressed PD-L1 affects tumour cells in an immune cell-independent fashion remains largely elusive. In this study, we investigated the significance of tumour cell-expressed PD-L1 with a focus on downstream signals and changes in lipid metabolism.

Methods

Immune-independent functions of PD-L1 in tumour growth were investigated in vitro and in immuno-deficient mice in vivo. The global influence of PD-L1 in targeted/untargeted lipidomic metabolites was studied by comprehensive mass spectrometry-based metabolomic analysis in liver cancer. Effects on lipid metabolism were confirmed by triglyceride and cholesterol assays as well as by Oil Red O staining in liver, pancreatic, breast, and oesophageal squamous cancer. Underlying mechanisms were investigated by real-time quantitative PCR, Western blot analysis, co-immunoprecipitation, pull-down assays, immunofluorescence staining, and RNA sequencing.

Results

PD-L1 enhanced the accumulation of triglycerides, cholesterol, and lipid droplets in tumours. PD-L1 influenced targeted/untargeted lipidomic metabolites in hepatoma, including lipid metabolism, glucose metabolism, amino acid metabolism, nucleotide metabolism, and energy metabolism, suggesting that PD-L1 globally modulates the metabolic reprogramming of tumours. Mechanistically, PD-L1 activated epidermal growth factor receptor (EGFR) and/or integrin β4 (ITGB4) by forming a complex of PD-L1/EGFR/ITGB4 in the cell membrane, prior to activating PI3K/mTOR/SREBP1c signalling, leading to reprogramming of lipid metabolism in tumours. Functionally, PD-L1-mediated lipid metabolism reprogramming supported the tumour growth in vitro and in vivo through EGFR and/or ITGB4 in an immune cell-independent manner.

Conclusions

Our findings on lipogenesis and EGFR activation by tumour cell-expressed PD-L1 suggest that, in addition to its immunostimulatory effects, anti-PD-L1 may restrict lipid metabolism and EGFR/ITGB4 signalling in liver cancer therapy.

Impact and implications

In this study, we present evidence that PD-L1 drives the reprogramming of lipid metabolism in tumours. PD-L1 forms a complex with epidermal growth factor receptor (EGFR) and ITGB4, activating the PI3K/Akt/mTOR/SREBP1c signalling pathway and thereby contributing to lipid metabolism in cancer progression. Our findings offer novel insights into the mechanisms by which PD-L1 initiates the reprogramming of lipid metabolism in tumours. From a clinical perspective, the anti-PD-L1 antibody may alleviate resistance to the anti-EGFR antibody cetuximab and inhibit the reprogramming of lipid metabolism in tumours.

Squalene Epoxidase: Its Regulations and Links with Cancers

Squalene epoxidase (SQLE) is a key enzyme in the mevalonate-cholesterol pathway that plays a critical role in cellular physiological processes. It converts squalene to 2,3-epoxysqualene and catalyzes the first oxygenation step in the pathway. Recently, intensive efforts have been made to extend the current knowledge of SQLE in cancers through functional and mechanistic studies. However, the underlying mechanisms and the role of SQLE in cancers have not been fully elucidated yet. In this review, we retrospected current knowledge of SQLE as a rate-limiting enzyme in the mevalonate-cholesterol pathway, while shedding light on its potential as a diagnostic and prognostic marker, and revealed its therapeutic values in cancers. We showed that SQLE is regulated at different levels and is involved in the crosstalk with iron-dependent cell death. Particularly, we systemically reviewed the research findings on the role of SQLE in different cancers. Finally, we discussed the therapeutic implications of SQLE inhibitors and summarized their potential clinical values. Overall, this review discussed the multifaceted mechanisms that involve SQLE to present a vivid panorama of SQLE in cancers.

Research status and hotspots on the mechanisms of liver X receptor in cancer progression: A bibliometric analysis

BACKGROUND

The mechanism of liver X receptor in cancer has been gradually revealed in recent years. This study is committed to analyzing the current research status of the mechanism of liver × receptor in cancer progression by using bibliometric methods and to explore the development trend of liver × receptor related research in the future, in order to provide some reference for further exploration in this field.

METHODS

The Web of Science core collection database was used to carry out the original data retrieval. Excel software was used for data statistics. Vosviewer and CiteSpace software were used to analyze the publication situation, cooperation network, reference co-citation, keyword and term co-occurrence, term bursts, and cluster analysis, and draw visual maps.

RESULTS

A total of 631 publications meeting the research criteria were included by December 2022, with an average of 32.5 citations per paper. The main research fields were molecular biology, oncology and cell biology, and the papers were mainly published in journals about molecular, biology and immunology. Cell is the journal with the highest citation. The United States is the most influential country, the University of California, Los Angeles is the main research institution, and Gustafsson, Jan-ake is the author with the highest output. In reference co-citation clustering, cluster#2 "cancer development" is the main cluster, and the period from 2014 to 2018 is an important stage of relevant theoretical progress. "Tumor microenvironment" with high burst and novelty became the most noteworthy term in term burst.

CONCLUSION

Using bibliometric methods to reveal the current status of LXR and cancer mechanisms, and making predictions of possible future hotspots based on the analysis of the current situation, the translation of LXR anti-cancer research to clinical applications, the impact on the tumor microenvironment as a whole and more immune pathways, and the formation of a systematic cognition of the effects of more cancer cell lines and oncogenic signaling crosstalk, which is a possible direction for future research.

Blockade of isoprenoids biosynthesis by simvastatin induces autophagy-mediated cell death via downstream c-Jun N-terminal kinase activation and cell cycle dysregulation in canine T-cell lymphoma cells

Statins are inhibitors of the mevalonic acid pathway that mediates cellular metabolism by producing cholesterol and isoprenoids and are widely used in treating hypercholesterolaemia in humans. Lipophilic statins, including simvastatin, induce death in various tumour cells. However, the cytotoxic mechanisms of statins in tumour cells remain largely unexplored. This study aimed to elucidate the cytotoxic mechanisms of simvastatin in canine lymphoma cells. Simvastatin induced cell death via c-Jun N-terminal kinase (JNK) activation and autophagy in canine T-cell lymphoma cell lines Ema and UL-1, but not in B-cell lines. Cell death was mediated by induction of caspase-dependent apoptosis in UL-1 cells, but not in Ema cells. Blockade of autophagy by lysosomal inhibitors attenuated simvastatin-induced JNK activation and cell death. Isoprenoids, including farnesyl pyrophosphate and geranylgeranyl pyrophosphate, attenuated simvastatin-induced autophagy, JNK activation, and cell death. In UL-1 cells, simvastatin treatment resulted in the cell cycle arrest at the G2/M phase, which was altered to G0/1 phase cell cycle arrest by treatment with lysosomal inhibitors. These findings demonstrate that depletion of isoprenoids by simvastatin induces autophagy-mediated cell death via downstream JNK activation and cell cycle dysregulation in canine T-cell lymphoma cells.

Role of hydroxymethylglutharyl-coenzyme A reductase in the induction of stem-like states in breast cancer

PURPOSE

De novo synthesis of cholesterol and its rate-limiting enzyme, 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMGCR), is deregulated in tumors and critical for tumor cell survival and proliferation. However, the role of HMGCR in the induction and maintenance of stem-like states in tumors remains unclear.

METHODS

A compiled public database from breast cancer (BC) patients was analyzed with the web application SurvExpress. Cell Miner was used for the analysis of HMGCR expression and statin sensitivity of the NCI-60 cell lines panel. A CRISPRon system was used to induce HMGCR overexpression in the luminal BC cell line MCF-7 and a lentiviral pLM-OSKM system for the reprogramming of MCF-7 cells. Comparisons were performed by two-tailed unpaired t-test for two groups and one- or two-way ANOVA.

RESULTS

Data from BC patients showed that high expression of several members of the cholesterol synthesis pathway were associated with lower recurrence-free survival, particularly in hormone-receptor-positive BC. In silico and in vitro analysis showed that HMGCR is expressed in several BC cancer cell lines, which exhibit a subtype-dependent response to statins in silico and in vitro. A stem-like phenotype was demonstrated upon HMGCR expression in MCF-7 cells, characterized by expression of the pluripotency markers NANOG, SOX2, increased CD44 +/CD24low/ -, CD133 + populations, and increased mammosphere formation ability. Pluripotent and cancer stem cell lines showed high expression of HMGCR, whereas cell reprogramming of MCF-7 cells did not increase HMGCR expression.

CONCLUSION

HMGCR induces a stem-like phenotype in BC cells of epithelial nature, thus affecting tumor initiation, progression and statin sensitivity.

Appraising associations between signature lipidomic biomarkers and digestive system cancer risk: novel evidences from a prospective cohort study of UK Biobank and Mendelian randomization analyses

BACKGROUND

The roles of serum lipids on digestive system cancer (DSC) risk were still inconclusive. In this study, we systematically assessed indicative effects of signature lipidomic biomarkers (high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG)) on DSC (oesophagus, stomach, colorectal, liver, gallbladder, and pancreas cancers) risk.

METHODS

HDL-C, LDL-C, and TG concentration measurements were respectively analyzed with enzyme immunoinhibition, enzymatic selective protection, and GPO-POD methods in AU5800 supplied from Beckman Coulter. The diagnoses of DSCs were coded using International Classification of Diseases, Tenth Revision (ICD-10) codes updated until October 2022 in the UK Biobank (UKB). In this study, we assessed phenotypic association patterns between signature lipidomic biomarkers and DSC risk using restricted cubic splines (RCSs) in multivariable-adjusted Cox proportional hazards regression models. Moreover, linear and nonlinear causal association patterns of signature lipidomic biomarkers with DSC risk were determined by linear and nonlinear Mendelian randomization (MR) analyses.

RESULTS

A median follow-up time of 11.8 years was recorded for 319,568 participants including 6916 DSC cases. A suggestive independent nonlinear phenotypic association was observed between LDL-C concentration and stomach cancer risk (Pnonlinearity < 0.05, Poverall < 0.05). Meanwhile, a remarkable independent linear negative phenotypic association was demonstrated between HDL-C concentration and stomach cancer risk (Pnonlinearity > 0.05, Poverall < 0.008 (0.05/6 outcomes, Bonferroni-adjusted P)), and suggestive independent linear positive associations were observed between HDL-C concentration and colorectal cancer risk, and between TG concentration and gallbladder cancer risk (Pnonlinearity > 0.05, Poverall < 0.05). Furthermore, based on nonlinear and linear MR-based evidences, we observed an suggestive independent negative causal association (hazard ratio (HR) per 1 mmol/L increase: 0.340 (0.137-0.843), P = 0.020) between LDL-C and stomach cancer risk without a nonlinear pattern (Quadratic P = 0.901, Cochran Q P = 0.434). Meanwhile, subgroup and stratified MR analyses both supported the category of LDL-C ≥ 4.1 mmol/L was suggestively protective against stomach cancer risk, especially among female participants (HR: 0.789 (0.637-0.977), P = 0.030) and participants aged 60 years or older (HR: 0.786 (0.638-0.969), P = 0.024), and the category of TG ≥ 2.2 mmol/L concluded to be a suggestive risk factor for gallbladder cancer risk in male participants (HR: 1.447 (1.020-2.052), P = 0.038) and participants aged 60 years or older (HR: 1.264 (1.003-1.593), P = 0.047).

CONCLUSIONS

Our findings confirmed indicative roles of signature lipidomic biomarkers on DSC risk, notably detecting suggestive evidences for a protective effect of high LDL-C concentration on stomach cancer risk, and a detrimental effect of high TG concentration on gallbladder cancer risk among given participants.

Exploratory focused pharmacogenetic testing reveals novel markers associated with risperidone pharmacokinetics in Saudi children with autism

Background: Autism spectrum disorders (ASDs) encompass a broad range of phenotypes characterized by diverse neurological alterations. Genomic studies have revealed considerable overlap between the molecular mechanisms implicated in the etiology of ASD and genes involved in the pharmacokinetic (PK) and pharmacodynamic (PD) pathways of antipsychotic drugs employed in ASD management. Given the conflicting data originating from candidate PK or PD gene association studies in diverse ethnogeographic ASD populations, dosage individualization based on "actionable" pharmacogenetic (PGx) markers has limited application in clinical practice. Additionally, off-label use of different antipsychotics is an ongoing practice, which is justified given the shortage of approved cures, despite the lack of satisfactory evidence for its safety according to precision medicine. This exploratory study aimed to identify PGx markers predictive of risperidone (RIS) exposure in autistic Saudi children. Methods: This prospective cohort study enrolled 89 Saudi children with ASD treated with RIS-based antipsychotic therapy. Plasma levels of RIS and 9-OH-RIS were measured using a liquid chromatography-tandem mass spectrometry system. To enable focused exploratory testing, genotyping was performed with the Axiom PharmacoFocus Array, which included a collection of probe sets targeting PK/PD genes. A total of 720 PGx markers were included in the association analysis. Results: A total of 27 PGx variants were found to have a prominent impact on various RIS PK parameters; most were not located within the genes involved in the classical RIS PK pathway. Specifically, 8 markers in 7 genes were identified as the PGx markers with the strongest impact on RIS levels (p < 0.01). Four PGx variants in 3 genes were strongly associated with 9-OH-RIS levels, while 5 markers in 5 different genes explained the interindividual variability in the total active moiety. Notably, 6 CYP2D6 variants exhibited strong linkage disequilibrium; however, they significantly influenced only the metabolic ratio and had no considerable effects on the individual estimates of RIS, 9-OH-RIS, or the total active moiety. After correction for multiple testing, rs78998153 in UGT2B17 (which is highly expressed in the brain) remained the most significant PGx marker positively adjusting the metabolic ratio. For the first time, certain human leukocyte antigen (HLA) markers were found to enhance various RIS exposure parameters, which reinforces the gut-brain axis theory of ASD etiology and its suggested inflammatory impacts on drug bioavailability through modulation of the brain, gastrointestinal tract and/or hepatic expression of metabolizing enzymes and transporters. Conclusion: Our hypothesis-generating approach identified a broad spectrum of PGx markers that interactively influence RIS exposure in ASD children, which indicated the need for further validation in population PK modeling studies to define polygenic scores for antipsychotic efficacy and safety, which could facilitate personalized therapeutic decision-making in this complex neurodevelopmental condition.

LncRNAs-circRNAs as Rising Epigenetic Binary Superstars in Regulating Lipid Metabolic Reprogramming of Cancers

As one of novel hallmarks of cancer, lipid metabolic reprogramming has recently been becoming fascinating and widely studied. Lipid metabolic reprogramming in cancer is shown to support carcinogenesis, progression, distal metastasis, and chemotherapy resistance by generating ATP, biosynthesizing macromolecules, and maintaining appropriate redox status. Notably, increasing evidence confirms that lipid metabolic reprogramming is under the control of dysregulated non-coding RNAs in cancer, especially lncRNAs and circRNAs. This review highlights the present research findings on the aberrantly expressed lncRNAs and circRNAs involved in the lipid metabolic reprogramming of cancer. Emphasis is placed on their regulatory targets in lipid metabolic reprogramming and associated mechanisms, including the clinical relevance in cancer through lipid metabolism modulation. Such insights will be pivotal in identifying new theranostic targets and treatment strategies for cancer patients afflicted with lipid metabolic reprogramming.

PaSTe. Blockade of the Lipid Phenotype of Prostate Cancer as Metabolic Therapy: A Theoretical Proposal

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy in 112 countries and is the leading cause of death in eighteen. In addition to continuing research on prevention and early diagnosis, improving treatments and making them more affordable is imperative. In this sense, the therapeutic repurposing of low-cost and widely available drugs could reduce global mortality from this disease. The malignant metabolic phenotype is becoming increasingly important due to its therapeutic implications. Cancer generally is characterized by hyperactivation of glycolysis, glutaminolysis, and fatty acid synthesis. However, prostate cancer is particularly lipidic; it exhibits increased activity in the pathways for synthesizing fatty acids, cholesterol, and fatty acid oxidation (FAO).

OBJECTIVE

Based on a literature review, we propose the PaSTe regimen (Pantoprazole, Simvastatin, Trimetazidine) as a metabolic therapy for prostate cancer. Pantoprazole and simvastatin inhibit the enzymes fatty acid synthase (FASN) and 3-hydroxy-3-methylglutaryl- coenzyme A reductase (HMGCR), therefore, blocking the synthesis of fatty acids and cholesterol, respectively. In contrast, trimetazidine inhibits the enzyme 3-β-Ketoacyl- CoA thiolase (3-KAT), an enzyme that catalyzes the oxidation of fatty acids (FAO). It is known that the pharmacological or genetic depletion of any of these enzymes has antitumor effects in prostatic cancer.

RESULTS

Based on this information, we hypothesize that the PaSTe regimen will have increased antitumor effects and may impede the metabolic reprogramming shift. Existing knowledge shows that enzyme inhibition occurs at molar concentrations achieved in plasma at standard doses of these drugs.

CONCLUSION

We conclude that this regimen deserves to be preclinically evaluated because of its clinical potential for the treatment of prostate cancer.

Dysregulated cholesterol regulatory genes in hepatocellular carcinoma

Cholesterol is an indispensable component in mammalian cells, and cholesterol metabolism performs important roles in various biological activities. In addition to the Warburg effect, dysregulated cholesterol metabolism is one of the metabolic hallmarks of several cancers. It has reported that reprogrammed cholesterol metabolism facilitates carcinogenesis, metastasis, and drug-resistant in various tumors, including hepatocellular carcinoma (HCC). Some literatures have reported that increased cholesterol level leads to lipotoxicity, inflammation, and fibrosis, ultimately promoting the development and progression of HCC. Contrarily, other clinical investigations have demonstrated a link between higher cholesterol level and lower risk of HCC. These incongruent findings suggest that the connection between cholesterol and HCC is much complicated. In this report, we summarize the roles of key cholesterol regulatory genes including cholesterol biosynthesis, uptake, efflux, trafficking and esterification in HCC. In addition, we discuss promising related therapeutic targets for HCC.

Expression of cholesterol synthesis and steroidogenic markers in females of the Chinese brown frog (Rana dybowskii) during prespawning and prehibernation

The oviduct of the Chinese brown frog (Rana dybowskii) expands in prehibernation rather than in prespawning, which is one of the physiological phenomena that occur in the preparation for hibernation. Steroid hormones are known to regulate oviductal development. Cholesterol synthesis and steroidogenesis may play an important role in the expansion of the oviduct before hibernation. In this study, we investigated the expression patterns of the markers that are involved in the de novo steroid synthesis pathway in the oviduct of R. dybowskii during prespawning and prehibernation. According to histological analysis, the oviduct of R. dybowskii contains epithelial cells, glandular cells, and tubule lumens. During prehibernation, oviductal pipe diameter and weight were significantly larger than during prespawning. 3-Hydroxy-3-methylglutaryl CoA reductase (HMGCR), low-density lipoprotein receptor (LDLR), steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and steroidogenic factor 1 (SF-1) were detected in epithelial cells in prehibernation and glandular cells during prespawning. HMGCR, LDLR, StAR, and P450scc protein expression levels were higher in prehibernation than during prespawning, but the SF-1 protein expression level did not significantly differ. HMGCR, LDLR, StAR, P450scc (CYP11A1), and SF-1 (NR5A1) mRNA expression levels were significantly higher in prehibernation compared with prespawning. The transcriptome results showed that the steroid synthesis pathway was highly expressed during prehibernation. Existing results indicate that the oviduct is able to synthesize steroid hormones using cholesterol, and that steroid hormones may affect the oviductal functions of R. dybowskii.

Lanosterol Synthase Prevents EMT During Lens Epithelial Fibrosis Via Regulating SREBP1

Purpose

Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a predominant pathological process underlying fibrotic cataracts. Here we investigated the role and mechanism of lanosterol synthase (LSS), a key rate-limiting enzyme in sterol biosynthesis, in EMT of LECs.

Methods

Human lens epithelial explants, primary rabbit LECs, and whole rat lenses were treated with TGFβ2. RNA-sequencing was conducted to explore genetic changes during fibrosis of human lens epithelial explants. Loss- and gain-of-function studies were performed in primary LECs to investigate roles and mechanisms of LSS, lanosterol and sterol regulatory element binding transcription protein 1 (SREBP1) in EMT. Rat lenses were applied to evaluate the potential effect of lanosterol on lens fibrosis. Expression of LSS, SREBP1, EMT-related regulators, and markers were analyzed by Western blot, qRT-PCR, or immunofluorescent staining.

Results

LSS and steroid biosynthesis were downregulated in TGFβ2-induced lens fibrosis. LSS inhibition directly triggered EMT by inducing Smad2/3 phosphorylation and nucleus translocation, an overexpression of LSS protected LECs from EMT by inhibiting Smad2/3 activation. Moreover, LSS inhibition decreased the expression of SREBP1, which regulated EMT via intervening TGFβ2/Smad2/3 transduction. Furthermore, lanosterol protected LECs from EMT caused by both TGFβ2 treatment and LSS inhibition via suppressing Smad2/3 activation and maintained lens transparency by preventing fibrotic plaques formation.

Conclusions

We first identified that LSS protected LECs from EMT and played an antifibrotic role to maintain lens transparency. Additionally, lanosterol and sterol biosynthesis regulation might be promising strategies for preventing and treating fibrotic cataracts.

New Steroidal Selenides as Proapoptotic Factors

Cytostatic and pro-apoptotic effects of selenium steroid derivatives against HeLa cells were determined. The highest cytostatic activity was shown by derivative 4 (GI50 25.0 µM, almost complete growth inhibition after three days of culture, and over 97% of apoptotic and dead cells at 200 µM). The results of our study (cell number measurements, apoptosis profile, relative expression of apoptosis-related APAF1, BID, and mevalonate pathway-involved HMGCR, SQLE, CYP51A1, and PDHB genes, and computational chemistry data) support the hypothesis that tested selenosteroids induce the extrinsic pathway of apoptosis by affecting the cell membrane as cholesterol antimetabolites. An additional mechanism of action is possible through a direct action of derivative 4 to inhibit PDHB expression in a way similar to steroid hormones.

Don't Judge a Book by Its Cover: The Role of Statins in Liver Cancer

Statins, which are inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, are an effective pharmacological tool for lowering blood cholesterol levels. This property makes statins one of the most popular drugs used primarily to prevent cardiovascular diseases, where hyperlipidemia is a significant risk factor that increases mortality. Nevertheless, studies conducted mainly in the last decade have shown that statins might prevent and treat liver cancer, one of the leading causes of cancer-related mortality worldwide. This narrative review summarizes the scientific achievements to date regarding the role of statins in liver tumors. Molecular biology tools have revealed that cell growth and proliferation can be inhibited by statins, which further inhibit angiogenesis. Clinical studies, supported by meta-analysis, confirm that statins are highly effective in preventing and treating hepatocellular carcinoma and cholangiocarcinoma. However, this effect may depend on the statin's type and dose, and more clinical trials are required to evaluate clinical effects. Moreover, their potential hepatotoxicity is a significant caveat for using statins in clinical practice. Nevertheless, this group of drugs, initially developed to prevent cardiovascular diseases, is now a key candidate in hepato-oncology patient management. The description of new drug-statin-like structures, e.g., with low toxicity to liver cells, may bring another clinically significant improvement to current cancer therapies.

Unraveling the Anticancer Potential of Statins: Mechanisms and Clinical Significance

Statins are an essential medication class in the treatment of lipid diseases because they inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. They reduce cholesterol levels and reduce the risk of cardiovascular disease in both primary and secondary prevention. In addition to their powerful pharmacologic suppression of cholesterol production, statins appear to have pleitropic effects in a wide variety of other diseases by modulating signaling pathways. In recent years, statins have seen a large increase in interest due to their putative anticancer effects. Statins appear to cause upregulation or inhibition in key pathways involved in cancer such as inhibition of proliferation, angiogenesis, and metastasis as well as reducing cancer stemness. Further, statins have been found to induce oxidative stress, cell cycle arrest, autophagy, and apoptosis of cancer cells. Interestingly, clinical studies have shown that statin use is associated with a decreased risk of cancer formation, lower cancer grade at diagnosis, reduction in the risk of local reoccurrence, and increasing survival in patients. Therefore, our objective in the present review is to summarize the findings of the publications on the underlying mechanisms of statins' anticancer effects and their clinical implications.

Regulation of cellular cholesterol distribution via non-vesicular lipid transport at ER-Golgi contact sites

Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of cholesterol is critical for maintaining its proper distribution in the cell, yet the underlying mechanisms remain unclear. Here, we show that lipid transfer proteins, namely ORP9, OSBP, and GRAMD1s/Asters (GRAMD1a/GRAMD1b/GRAMD1c), control non-vesicular cholesterol transport at points of contact between the ER and the trans-Golgi network (TGN), thereby maintaining cellular cholesterol distribution. ORP9 localizes to the TGN via interaction between its tandem α-helices and ORP10/ORP11. ORP9 extracts PI4P from the TGN to prevent its overaccumulation and suppresses OSBP-mediated PI4P-driven cholesterol transport to the Golgi. By contrast, GRAMD1s transport excess cholesterol from the Golgi to the ER, thereby preventing its build-up. Cells lacking ORP9 exhibit accumulation of cholesterol at the Golgi, which is further enhanced by additional depletion of GRAMD1s with major accumulation in the plasma membrane. This is accompanied by chronic activation of the SREBP-2 signalling pathway. Our findings reveal the importance of regulated lipid transport at ER-Golgi contacts for maintaining cellular cholesterol distribution and homeostasis.

Dietary fats and serum lipids in relation to the risk of ovarian cancer: a meta-analysis of observational studies

Although numerous epidemiological studies investigated the association between dietary fat intakes or serum lipid levels and ovarian cancer risk, a consistent and explicit conclusion for specific dietary fats or serum lipids that increase the risk of ovarian cancer is not available. In this study, a systematic review and meta-analysis were conducted to assess the key dietary fats and serum lipids that increased the risk of ovarian cancer. Databases such as PubMed, Web of Science, and EMBASE were searched for observational studies. A total of 41 studies met the inclusion criteria, including 18 cohort and 23 case-control studies (109,507 patients with ovarian cancer and 2,558,182 control/non-ovarian cancer participants). Higher dietary intakes of total fat (RR = 1.19, 95% CI = 1.06-1.33, I2 = 60.3%), cholesterol (RR = 1.14, 95% CI = 1.03-1.26, I2 = 19.4%), saturated fat (RR = 1.13, 95% CI = 1.04-1.22, I2 = 13.4%), and animal fat (RR = 1.21, 95% CI = 1.01-1.43, I2 = 70.5%) were significantly associated with a higher risk of ovarian cancer. A higher level of serum triglycerides was accompanied by a higher risk of ovarian cancer (RR = 1.33, 95% CI = 1.02-1.72, I2 = 89.3%). This meta-analysis indicated that a higher daily intake of total fat, saturated fat, animal fat, and cholesterol and higher levels of serum triglycerides were significantly associated with an increased risk of ovarian cancer.

Functional significance of cholesterol metabolism in cancer: from threat to treatment

Cholesterol is an essential structural component of membranes that contributes to membrane integrity and fluidity. Cholesterol homeostasis plays a critical role in the maintenance of cellular activities. Recently, increasing evidence has indicated that cholesterol is a major determinant by modulating cell signaling events governing the hallmarks of cancer. Numerous studies have shown the functional significance of cholesterol metabolism in tumorigenesis, cancer progression and metastasis through its regulatory effects on the immune response, ferroptosis, autophagy, cell stemness, and the DNA damage response. Here, we summarize recent literature describing cholesterol metabolism in cancer cells, including the cholesterol metabolism pathways and the mutual regulatory mechanisms involved in cancer progression and cholesterol metabolism. We also discuss various drugs targeting cholesterol metabolism to suggest new strategies for cancer treatment.

New molecular targets in canine hemangiosarcoma-Comparative review and future of the precision medicine

Human angiosarcoma and canine hemangiosarcoma reveal similarities not only in their aggressive clinical behaviour, but especially in molecular landscape and genetic alterations involved in tumorigenesis and metastasis formation. Currently, no satisfying treatment that allows for achieving long overall survival or even prolonged time to progression does not exist. Due to the progress that has been made in targeted therapies and precision medicine the basis for a new treatment design is to uncover mutations and their functions as possible targets to provide tailored drugs for individual cases. Whole exome or genome sequencing studies and immunohistochemistry brought in the last few years important discoveries and identified the most common mutations with probably crucial role in this tumour development. Also, despite a lack of mutation in some of the culprit genes, the cancerogenesis cause may be buried in main cellular pathways connected with proteins encoded by those genes and involving, for example, pathological angiogenesis. The aim of this review is to highlight the most promising molecular targets for precision oncology treatment from the veterinary perspective aided by the principles of comparative science. Some of the drugs are only undergoing laboratory in vitro studies and others entered the clinic in the management of other cancer types in humans, but those used in dogs with promising responses have been mentioned as priorities.

Regulation of VKORC1L1 is critical for p53-mediated tumor suppression through vitamin K metabolism

Here, we identified vitamin K epoxide reductase complex subunit 1 like 1 (VKORC1L1) as a potent ferroptosis repressor. VKORC1L1 protects cells from ferroptosis by generating the reduced form of vitamin K, a potent radical-trapping antioxidant, to counteract phospholipid peroxides independent of the canonical GSH/GPX4 mechanism. Notably, we found that VKORC1L1 is also a direct transcriptional target of p53. Activation of p53 induces downregulation of VKORC1L1 expression, thus sensitizing cells to ferroptosis for tumor suppression. Interestingly, a small molecular inhibitor of VKORC1L1, warfarin, is widely prescribed as an FDA-approved anticoagulant drug. Moreover, warfarin represses tumor growth by promoting ferroptosis in both immunodeficient and immunocompetent mouse models. Thus, by downregulating VKORC1L1, p53 executes the tumor suppression function by activating an important ferroptosis pathway involved in vitamin K metabolism. Our study also reveals that warfarin is a potential repurposing drug in cancer therapy, particularly for tumors with high levels of VKORC1L1 expression.

New insights into the therapeutic potentials of statins in cancer

The widespread clinical use of statins has contributed to significant reductions of cardiovascular morbidity and mortality. Increasing preclinical and epidemiological evidences have revealed that dyslipidemia is an important risk factor for carcinogenesis, invasion and metastasis, and that statins as powerful inhibitor of HMG-CoA reductase can exert prevention and intervention effects on cancers, and promote sensitivity to anti-cancer drugs. The anti-cancer mechanisms of statins include not only inhibition of cholesterol biosynthesis, but also their pleiotropic effects in modulating angiogenesis, apoptosis, autophagy, tumor metastasis, and tumor microenvironment. Moreover, recent clinical studies have provided growing insights into the therapeutic potentials of statins and the feasibility of combining statins with other anti-cancer agents. Here, we provide an updated review on the application potential of statins in cancer prevention and treatment and summarize the underneath mechanisms, with focuses on data from clinical studies.

Expression of housekeeping genes varies depending on mevalonate pathway inhibition in cancer cells

Statins have anticancer effects and may be used as anticancer agents via drug repositioning. In reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays, the internal reference gene must not be affected by any experimental conditions. As statins exert a wide range of effects on cells by inhibiting the mevalonate pathway, it is possible that statin treatment might alter the expression of housekeeping genes used as internal reference genes, thereby misleading the assessment of obtained gene expression data. Here, we evaluated the expression stability of internal reference genes in atorvastatin-treated cancer cell lines. We treated both statin-sensitive and statin-resistant cancer cell lines with atorvastatin at seven different concentrations and performed RT-qPCR on 15 housekeeping genes whose expression stability was then assessed using five different algorithms. In both statin-sensitive and statin-resistant cancer cell lines, atorvastatin affected the expression of certain internal reference genes in a dose-dependent and cancer cell line-dependent manner; therefore, caution should be exercised when comparing target gene expression between cells. Our findings emphasize the importance of the validation of internal reference genes in gene expression analyses in drug treatment-based cancer research.

P4HA1 activates HMGCS1 to promote nasopharyngeal carcinoma ferroptosis resistance and progression

Ferroptosis is a novel type of iron-dependent regulatory cell death. To date, the regulatory mechanism of ferroptosis in nasopharyngeal carcinoma (NPC) remains poorly understood. In this study, we found that the prolyl 4-hydroxylase (P4H) subunit P4HA1 protects NPC cells from erastin-induced ferroptosis by activating HMGCS1, a key enzyme in the mevalonate pathway. We also found that the P4HA1/HMGCS1 axis promoted NPC cell proliferation in vitro. In vivo, downregulation of the P4HA1/HMGCS1 axis inhibited the growth of NPC cell xenografts and enhanced the inhibitory effect of erastin on tumor growth. Extracellular matrix (ECM) detachment is an important trigger for ferroptosis. We found that the P4HA1/HMGCS1 axis promoted the ferroptosis resistance and survival of ECM-detached NPC cells. In vivo, downregulation of the P4HA1/HMGCS1 axis inhibited the lung colonization of NPC cells and enhanced the inhibitory effect of erastin on NPC lung metastasis. Moreover, the high expression of P4HA1 predicted a poor prognosis and served as a potential independent prognostic factor in patients with NPC. In conclusion, P4HA1 is a novel molecular marker of NPC ferroptosis resistance and a poor prognosis, and the P4HA1/HMGCS1 axis provides a new target for the treatment of NPC progression.

Network Analysis Reveals the Molecular Bases of Statin Pleiotropy That Vary with Genetic Background

Many approved drugs are pleiotropic: for example, statins, whose main cholesterol-lowering activity is complemented by anticancer and prodiabetogenic mechanisms involving poorly characterized genetic interaction networks. We investigated these using the Saccharomyces cerevisiae genetic model, where most genetic interactions known are limited to the statin-sensitive S288C genetic background. We therefore broadened our approach by investigating gene interactions to include two statin-resistant genetic backgrounds: UWOPS87-2421 and Y55. Networks were functionally focused by selection of HMG1 and BTS1 mevalonate pathway genes for detection of genetic interactions. Networks, multilayered by genetic background, were analyzed for key genes using network centrality (degree, betweenness, and closeness), pathway enrichment, functional community modules, and Gene Ontology. Specifically, we found modification genes related to dysregulated endocytosis and autophagic cell death. To translate results to human cells, human orthologues were searched for other drug targets, thus identifying candidates for synergistic anticancer bioactivity. IMPORTANCE Atorvastatin is a highly successful drug prescribed to lower cholesterol and prevent cardiovascular disease in millions of people. Though much of its effect comes from inhibiting a key enzyme in the cholesterol biosynthetic pathway, genes in this pathway interact with genes in other pathways, resulting in 15% of patients suffering painful muscular side effects and 50% having inadequate responses. Such multigenic complexity may be unraveled using gene networks assembled from overlapping pairs of genes that complement each other. We used the unique power of yeast genetics to construct genome-wide networks specific to atorvastatin bioactivity in three genetic backgrounds to represent the genetic variation and varying response to atorvastatin in human individuals. We then used algorithms to identify key genes and their associated FDA-approved drugs in the networks, which resulted in the distinction of drugs that may synergistically enhance the known anticancer activity of atorvastatin.

Biosynthesis of anticancer phytochemical compounds and their chemistry

Cancer is a severe health issue, and cancer cases are rising yearly. New anticancer drugs have been developed as our understanding of the molecular mechanisms behind diverse solid tumors, and metastatic malignancies have increased. Plant-derived phytochemical compounds target different oncogenes, tumor suppressor genes, protein channels, immune cells, protein channels, and pumps, which have attracted much attention for treating cancer in preclinical studies. Despite the anticancer capabilities of these phytochemical compounds, systemic toxicity, medication resistance, and limited absorption remain more significant obstacles in clinical trials. Therefore, drug combinations of new phytochemical compounds, phytonanomedicine, semi-synthetic, and synthetic analogs should be considered to supplement the existing cancer therapies. It is also crucial to consider different strategies for increased production of phytochemical bioactive substances. The primary goal of this review is to highlight several bioactive anticancer phytochemical compounds found in plants, preclinical research, their synthetic and semi-synthetic analogs, and clinical trials. Additionally, biotechnological and metabolic engineering strategies are explored to enhance the production of bioactive phytochemical compounds. Ligands and their interactions with their putative targets are also explored through molecular docking studies. Therefore, emphasis is given to gathering comprehensive data regarding modern biotechnology, metabolic engineering, molecular biology, and in silico tools.

Canine-Inspired Chemometric Analysis of Volatile Organic Compounds in Urine Headspace to Distinguish Prostate Cancer in Mice and Men

Canines can identify prostate cancer with high accuracy by smelling volatile organic compounds (VOCs) in urine. Previous studies have identified VOC biomarkers for prostate cancer utilizing solid phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS) but have not assessed the ability of VOCs to distinguish aggressive cancers. Additionally, previous investigations have utilized murine models to identify biomarkers but have not determined if the results are translatable to humans. To address these challenges, urine was collected from mice with prostate cancer and men undergoing prostate cancer biopsy and VOCs were analyzed by SPME GC-MS. Prior to analysis, SPME fibers/arrows were compared, and the fibers had enhanced sensitivity toward VOCs with a low molecular weight. The analysis of mouse urine demonstrated that VOCs could distinguish tumor-bearing mice with 100% accuracy. Linear discriminant analysis of six VOCs in human urine distinguished prostate cancer with sensitivity = 75% and specificity = 69%. Another panel of seven VOCs could classify aggressive cancer with sensitivity = 78% and specificity = 85%. These results show that VOCs have moderate accuracy in detecting prostate cancer and a superior ability to stratify aggressive tumors. Furthermore, the overlap in the structure of VOCs identified in humans and mice shows the merit of murine models for identifying biomarker candidates.

Dysregulated cholesterol regulatory genes as a diagnostic biomarker for cancer

BACKGROUND

A dysregulation of cholesterol homeostasis is often seen in various cancer cell types, and elevated cholesterol content and that of its metabolites appears to be crucial for cancer progression and metastasis. Cholesterol is a precursor of various steroid hormones and a key plasma membrane component especially in lipid-rafts, also modulating many intracellular signaling pathways.

METHODS

To provide an insight of dysregulated cholesterol regulatory genes, their transcript levels were analyzed in different cancers and their influence was correlated with the overall survival of cancer patients using cancer database analysis.

RESULTS

This analysis found a set of genes (e.g., ACAT1, RXRA, SOAT1 and SQLE) that were not only often dysregulated, but also had been associated with poorer overall survival in most cancer types. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed elevated SQLE and SOAT1 transcript levels and downregulated expression of RXRA and ACAT1 genes in triple negative breast cancer tissues compared to adjacent control tissues, indicating that this dysregulated expression of the gene signature is a diagnostic marker for breast cancer.

CONCLUSION

For the first time, the present study identified a gene signature associated with the dysregulation of cholesterol homeostasis in cancer cells that may not only be used as a diagnostic marker, but also comprise a promising drug target for the advancement of cancer therapy.

Lipid metabolism reprogramming in colorectal cancer

The hallmark feature of metabolic reprogramming is now considered to be widespread in many malignancies, including colorectal cancer (CRC). Of the gastrointestinal tumors, CRC is one of the most common with a high metastasis rate and long insidious period. The incidence and mortality of CRC has increased in recent years. Metabolic reprogramming also has a significant role in the development and progression of CRC, especially lipid metabolic reprogramming. Many studies have reported that lipid metabolism reprogramming is similar to the Warburg effect with typical features affecting tumor biology including proliferation, migration, local invasion, apoptosis, and other biological behaviors of cancer cells. Therefore, studying the role of lipid metabolism in the occurrence and development of CRC will increase our understanding of its pathogenesis, invasion, metastasis, and other processes and provide new directions for the treatment of CRC. In this paper, we mainly describe the molecular mechanism of lipid metabolism reprogramming and its important role in the occurrence and development of CRC. In addition, to provide reference for subsequent research and clinical diagnosis and treatment we also review the treatments of CRC that target lipid metabolism.

Synergistic antitumor activity of regorafenib and rosuvastatin in colorectal cancer

Introduction: Colorectal cancer is one of the most prevalent life-threatening malignant tumors with high incidence and mortality. However, the efficacy of current therapeutic regimens is very limited. Regorafenib has been approved for second- or third-line treatment of patients who are refractory to standard chemotherapy diagnosed with metastatic colorectal cancer, but its clinical efficacy needs to be further improved. Accumulating evidence demonstrates that statins also possess potent anticancer activities. However, whether regorafenib and statins pose synergistic anticancer effects in colorectal cancer is still unclear. Methods: Sulforhodamine B (SRB) assays were applied to evaluate the anti-proliferative activity of regorafenib or/and rosuvastatin in vitro, and immunoblotting analysis were applied to detect the effects of regorafenib/rosuvastatin combined treatment on mitogen-activated protein kinase (MAPK) signaling and apoptosis-related proteins. MC38 tumors were applied to investigate the synergistic anticancer effects of regorafenib in combination with rosuvastatin in vivo. Results: We found that regorafenib in combination with rosuvastatin exerted significant synergistic inhibition against colorectal cancer growth in vitro and in vivo. Mechanistically, regorafenib and rosuvastatin combination synergistically suppressed MAPK signaling, a crucial signaling pathway promoting cell survival, as indicated by the reduction of phosphorylated MEK/ERK. In addition, regorafenib in combination with rosuvastatin synergistically induced the apoptosis of colorectal cancer in vitro and in vivo. Discussion: Our study demonstrated the synergistic anti-proliferative and pro-apoptotic effects of regorafenib/rosuvastatin combined treatment in colorectal cancer in vitro/vivo and might potentially be evaluated as a novel combination regimen for clinical treatment of colorectal cancer.

We are what we eat: The role of lipids in metabolic diseases

Lipids play a fundamental role, both structurally and functionally, for the correct functioning of the organism. In the last two decades, they have evolved from molecules involved only in energy storage to compounds that play an important role as components of cell membranes and signaling molecules that regulate cell homeostasis. For this reason, their interest as compounds involved in human health has been gaining weight. Indeed, lipids derived from dietary sources and endogenous biosynthesis are relevant for the pathophysiology of numerous diseases. There exist pathological conditions that are characterized by alterations in lipid metabolism. This is particularly true for metabolic diseases, such as liver steatosis, type 2 diabetes, cancer and cardiovascular diseases. The main issue to be considered is lipid homeostasis. A precise control of fat homeostasis is required for a correct regulation of metabolic pathways and safe and efficient energy storage in adipocytes. When this fails, a deregulation occurs in the maintenance of systemic metabolism. This happens because an increased concentrations of lipids impair cellular homeostasis and disrupt tissue function, giving rise to lipotoxicity. Fat accumulation results in many alterations in the physiology of the affected organs, mainly in metabolic tissues. These alterations include the activation of oxidative and endoplasmic reticulum stress, mitochondrial dysfunction, increased inflammation, accumulation of bioactive molecules and modification of gene expression. In this chapter, we review the main metabolic diseases in which alterations in lipid homeostasis are involved and discuss their pathogenic mechanisms.

Atorvastatin improves cisplatin sensitivity through modulation of cholesteryl ester homeostasis in breast cancer cells

BACKGROUND

Acquired treatment resistance is a significant problem in breast cancer management, and alterations in lipid metabolism have been proposed to contribute to the development of drug resistance as well as other aspects of tumor progression. The present study aimed to identify the role of cholesterol metabolism in MCF-7 and MDA-MB-231 breast cancer cell response to cisplatin (CDDP) treatment in the acute setting and in a model of CDDP resistance.

METHODS

MCF-7 (luminal A), MDA-MB-231 (triple-negative) and CDDP-resistant MDA-MB-231 (MDACR) cell lines were grown in the presence or absence of CDDP in combination with atorvastatin (ATV), lipid depletion or low-density lipoprotein loading and were analyzed by a variety of biochemical and radiometric techniques.

RESULTS

Co-administration of CDDP and ATV strongly reduced cell proliferation and viability to a greater extent than CDDP alone, especially in MDA-MB-231 cells. These findings were associated with reduced cholesteryl ester synthesis and storage in MDA-MB-231 cells. In MDACR cells, acetyl-CoA acetyltransferase 1 (ACAT-1) was upregulated compared to naïve MDA-MB-231 cells and ATV treatment restored CDDP sensitivity, suggesting that aberrant ACAT-1 expression and associated changes in cholesterol metabolism contribute to CDDP resistance in MDA-MB-231 cells.

CONCLUSION

These findings indicate that the elevated susceptibility of MDA-MB-231 cells to co-administration of CDDP and ATV, is associated with an increased reliance on cholesteryl ester availability. Our data from these cell culture-based studies identifies altered cholesterol homeostasis as an adaptive response to CDDP treatment that contributes to aggressiveness and chemotherapy resistance.

Statins and the Risk of Gastric Cancer: A Systematic Review and Meta-Analysis

Previous epidemiological studies have reported that the use of statins is associated with a decreased risk of gastric cancer, although the beneficial effects of statins on the reduction of gastric cancer remain unclear. Therefore, we conducted a systematic review and meta-analysis to investigate the association between the use of statins and the risk of gastric cancer. Electronic databases such as PubMed, EMBASE, Scopus, and Web of Science were searched between 1 January 2000 and 31 August 2022. Two authors used predefined selection criteria to independently screen all titles, abstracts, and potential full texts. Observational studies (cohort and case-control) or randomized control trials that assessed the association between statins and gastric cancer were included in the primary and secondary analyses. The pooled effect sizes were calculated using the random-effects model. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines were followed to conduct this study. The total sample size across the 20 included studies was 11,870,553. The use of statins was associated with a reduced risk of gastric cancer (RRadjusted: 0.72; 95%CI: 0.64−0.81, p < 0.001). However, the effect size of statin use on the risk of gastric cancer was lower in Asian studies compared to Western studies (RRAsian: 0.62; 95%CI: 0.53−0.73 vs. RRwestern: 0.88; 95%CI: 0.79−0.99). These findings suggest that the use of statins is associated with a reduced risk of gastric cancer. This reverse association was even stronger among Asian people than Western individuals.

Alterations in the omics profiles in mevalonate pathway-inhibited cancer cells

AIMS

Statins, cholesterol-lowering drugs, are potential therapeutic agents for inhibiting cancer proliferation. However, the mechanisms that mediate the effects of statins, the homeostatic responses of tumor cells to statin therapy, and the modes underlying the antitumor effects of statins remain unclear.

MAIN METHODS

To uncover the effects of statins on cancer cells in vitro, we performed transcriptome and metabolome analyses on atorvastatin-treated statin-resistant and statin-sensitive lung cancer cells.

KEY FINDINGS

The results of Gene Ontology terms and pathway enrichment analyses showed that after 24 h of atorvastatin treatment, the expression of cell cycle- and DNA replication-related genes was significantly decreased in the statin-sensitive cancer cells. The results of metabolome analysis showed that the components of polyamine metabolism and purine metabolism, glycolysis, and pentose phosphate pathway were decreased in the statin-sensitive cancer cells.

SIGNIFICANCE

Differences in cellular properties between statin-sensitive and statin-resistant cancer cells revealed additional candidates for therapeutic targets in statin-treated cancer cells and suggested that inhibiting these metabolic pathways could improve efficacy. In conclusion, combining statins with inhibitors of polyamine metabolism (cell proliferation and protein translation), purine metabolism (DNA synthesis), glycolytic system (energy production), and pentose phosphate pathway (antioxidant stress) might enhance the anticancer effects of statins.

Synthesis, function, and regulation of sterol and nonsterol isoprenoids

Cholesterol, the bulk end-product of the mevalonate pathway, is a key component of cellular membranes and lipoproteins that transport lipids throughout the body. It is also a precursor of steroid hormones, vitamin D, and bile acids. In addition to cholesterol, the mevalonate pathway yields a variety of nonsterol isoprenoids that are essential to cell survival. Flux through the mevalonate pathway is tightly controlled to ensure cells continuously synthesize nonsterol isoprenoids but avoid overproducing cholesterol and other sterols. Endoplasmic reticulum (ER)-localized 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase (HMGCR), the rate limiting enzyme in the mevalonate pathway, is the focus of a complex feedback regulatory system governed by sterol and nonsterol isoprenoids. This review highlights transcriptional and post-translational regulation of HMGCR. Transcriptional regulation of HMGCR is mediated by the Scap-SREBP pathway. Post-translational control is initiated by the intracellular accumulation of sterols, which causes HMGCR to become ubiquitinated and subjected to proteasome-mediated ER-associated degradation (ERAD). Sterols also cause a subfraction of HMGCR molecules to bind the vitamin K₂ synthetic enzyme, UbiA prenyltransferase domain-containing protein-1 (UBIAD1). This binding inhibits ERAD of HMGCR, which allows cells to continuously synthesize nonsterol isoprenoids such as geranylgeranyl pyrophosphate (GGPP), even when sterols are abundant. Recent studies reveal that UBIAD1 is a GGPP sensor, dissociating from HMGCR when GGPP thresholds are met to allow maximal ERAD. Animal studies using genetically manipulated mice disclose the physiological significance of the HMGCR regulatory system and we describe how dysregulation of these pathways contributes to disease.

Metabolic Reprogramming in Hematologic Malignancies: Advances and Clinical Perspectives

Metabolic reprogramming is a hallmark of cancer progression. Metabolic activity supports tumorigenesis and tumor progression, allowing cells to uptake essential nutrients from the environment and use the nutrients to maintain viability and support proliferation. The metabolic pathways of malignant cells are altered to accommodate increased demand for energy, reducing equivalents, and biosynthetic precursors. Activated oncogenes coordinate with altered metabolism to control cell-autonomous pathways, which can lead to tumorigenesis when abnormalities accumulate. Clinical and preclinical studies have shown that targeting metabolic features of hematologic malignancies is an appealing therapeutic approach. This review provides a comprehensive overview of the mechanisms of metabolic reprogramming in hematologic malignancies and potential therapeutic strategies to target cancer metabolism.

Targeting the key cholesterol biosynthesis enzyme squalene monooxygenasefor cancer therapy

Cholesterol metabolism is often dysregulated in cancer. Squalene monooxygenase (SQLE) is the second rate-limiting enzyme involved in cholesterol synthesis. Since the discovery of SQLE dysregulation in cancer, compelling evidence has indicated that SQLE plays a vital role in cancer initiation and progression and is a promising therapeutic target for cancer treatment. In this review, we provide an overview of the role and regulation of SQLE in cancer and summarize the updates of antitumor therapy targeting SQLE.

STUB1-SMYD2 Axis Regulates Drug Resistance in Glioma cells

SET and MYND domain-containing protein 2 (SMYD2) is an important epigenetic regulator that methylates histone and non-histone proteins. The study aimed to investigate the oncogenic role of SMYD2 in gliomas and explore its degradation mechanism induced by cisplatin. Tumor tissue microarray of 441 patients with glioma was collected for SMYD2 immunohistochemical staining. Kaplan-Meier survival curves were constructed using the overall survival values. mRNA-sequencing analysis was performed for understanding the downstream mechanisms mediated by SMYD2. The half-inhibitory concentrations (IC50) of temozolomide and cisplatin in AZ505-treated and control cells were calculated. The potential E3 ubiquitin ligase of SMYD2 was predicted in UbiBrowser and confirmed by a knockdown test. The effect of SMYD2 and its E3 ligase on apoptosis and migration of glioma cells was determined via cell-function assays. High SMYD2 expression correlated with a high WHO stage (P = 0.004) and a low survival probability (P = 0.012). The inhibition of SMYD2 suppressed the process of epithelial to mesenchymal transition (EMT) by downregulating the expression of Collagen 1A1 (COL1A1). AZ505 treatment significantly increased the drug sensitivity of glioma cells. SMYD2 expression was markedly reduced by cisplatin treatment via STIP1 Homology And U-Box Containing Protein 1 (STUB1)-mediated degradation. The knockdown of STUB1 could partly reverse the cell function impairment induced by cisplatin. Our findings suggested that SMYD2 could be a potential drug target for the treatment of gliomas, and STUB1-mediated degradation of SMYD2 plays an important role in reversing chemotherapy resistance in patients with gliomas.