The importance of LDL and cholesterol metabolism for prostate epithelial cell growth

Effects of ketogenic diets on cancer-related variables: A systematic review and meta-analysis of randomised controlled trials

Cancer is a global health concern influenced by genetics, environment and lifestyle choices. Recent research shows that a ketogenic diet (KD) might ease cancer symptoms and reduce tumour size. We hypothesised that the KD could result in improvements in cancer-related variables. Therefore, this study aims to perform a systematic review and meta-analysis to assess the KD's efficacy for patients with cancer. The databases PubMed (MEDLINE), Web of Science, CINAHL and Open Grey were utilised for conducting a systematic review and meta-analysis. The analysis was limited to randomised controlled trials with adult participants aged 18 years and above. Levels of glucose, cholesterol, insulin-like growth factor 1, weight and quality of life were evaluated following the KD. After identifying 596 articles in the initial search, eight studies, lasting between 4 and 16 weeks, were included in the systematic review and seven in the meta-analysis. The KD led to decreased glucose levels in patients with cancer but did not show significant improvements in cholesterol, insulin-like growth factor 1, weight or quality of life. Based on the results of this systematic review and meta-analysis, there is insufficient evidence to establish a definitive link between the KD and cancer-related parameters. While some studies suggest potential benefits in terms of some outcomes and tumour size reduction, further research is required to fully comprehend the effects of this diet.

Computational and physicochemical insight into 4-hydroxy-2-nonenal induced structural and functional perturbations in human low-density lipoprotein

Lipid peroxidation (LPO) is a biological process that frequently occurs under physiological conditions. Undue oxidative stress increases the level of LPO; which may further contribute to the development of cancer. 4-Hydroxy-2-nonenal (HNE), one of the principal by-products of LPO, is present in high concentrations in oxidatively stressed cells. HNE rapidly reacts with various biological components, including DNA and proteins; however, the extent of protein degradation by lipid electrophiles is not well understood. The influence of HNE on protein structures will likely have a considerable therapeutic value. This research elucidates the potential of HNE, one of the most researched phospholipid peroxidation products, in modifying low-density lipoprotein (LDL). In this study, we tracked the structural alterations in LDL by HNE using various physicochemical techniques. To comprehend the stability, binding mechanism and conformational dynamics of the HNE-LDL complex, computational investigations were carried out. LDL was altered in vitro by HNE, and the secondary and tertiary structural alterations were examined using spectroscopic methods, such as UV-visible, fluorescence, circular dichroism and fourier transform infrared spectroscopy. Carbonyl content, thiobarbituric acid-reactive-substance (TBARS) and nitroblue tetrazolium (NBT) reduction assays were used to examine changes in the oxidation status of LDL. Thioflavin T (ThT), 1-anilinonaphthalene-8-sulfonic (ANS) binding assay and electron microscopy were used to investigate aggregates formation. According to our research, LDL modified by HNE results in changes in structural dynamics, oxidative stress and the formation of LDL aggregates. The current investigation must characterize HNE's interactions with LDL and comprehend how it can change their physiological or pathological functions.Communicated by Ramaswamy H. Sarma.

The Causal Relationship between PCSK9 Inhibitors and Malignant Tumors: A Mendelian Randomization Study Based on Drug Targeting

Objective: This study explores the potential causal association between proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors and tumor development using Mendelian randomization (MR) based on drug targets. Methods: Instrumental variables within ±100 kb of the PCSK9 gene locus, impacting low-density lipoprotein cholesterol (LDL-C), were utilized for MR analysis. Coronary heart disease (CHD) served as a positive control to validate the causal relationship between PCSK9 inhibitors and various cancers. We employed reverse MR to address the reverse causation concerns. Data from positive controls and tumors were sourced from OpenGWAS. Results: MR analysis suggested a negative causal relationship between PCSK9 inhibitors and both breast and lung cancers (95%CIBreast cancer 0.81~0.99, p = 2.25 × 10-2; 95%CILung cancer 0.65~0.94, p = 2.55 × 10-3). In contrast, a positive causal link was observed with gastric, hepatic, and oral pharyngeal cancers and cervical intraepithelial neoplasia (95%CIGastric cancer 1.14~1.75, p = 1.88 × 10-2; 95%CIHepatic cancer 1.46~2.53, p = 1.16 × 10-2; 95%CIOral cavity and pharyngeal cancer 4.49~6.33, p = 3.36 × 10-4; 95%CICarcinoma in situ of cervix uteri 4.56~7.12, p = 6.91 × 10-3), without heterogeneity or pleiotropy (p > 0.05). Sensitivity analyses confirmed these findings. The results of MR of drug targets suggested no causal relationship between PCSK9 inhibitors and bladder cancer, thyroid cancer, pancreatic cancer, colorectal cancer, malignant neoplasms of the kidney (except for renal pelvis tumors), malignant neoplasms of the brain, and malignant neoplasms of the esophagus (p > 0.05). Reverse MR helped mitigate reverse causation effects. Conclusions: The study indicates a divergent causal relationship of PCSK9 inhibitors with certain cancers. While negatively associated with breast and lung cancers, a positive causal association was observed with gastric, hepatic, oral cavity, and pharyngeal cancers and cervical carcinoma in situ. No causal links were found with bladder, thyroid, pancreatic, colorectal, certain kidney, brain, and esophageal cancers.

2-Hydroxypropyl-β-cyclodextrin (HPβCD) as a Potential Therapeutic Agent for Breast Cancer

Cholesterol accumulation is documented in various malignancies including breast cancer. Consequently, depleting cholesterol in cancer cells can serve as a viable treatment strategy. We identified the potency of 2-hydroxypropyl-β-cyclodextrin (HPβCD), a cholesterol-depletor in vitro against two breast cancer cell lines: MCF-7 (Oestrogen-receptor positive, ER+) and MDA-MB-231 (Triple negative breast cancer (TNBC)). The results were then compared against two non-cancerous cell lines using cytotoxic-, apoptosis-, and cholesterol-based assays. Treatment with HPβCD showed preferential and significant cytotoxic potential in cancer cells, inducing apoptosis in both cancer cell lines (p < 0.001). This was mediated due to significant depletion of cholesterol (p < 0.001). We further tested HPβCD in a MF-1 mice (n = 14) xenograft model and obtained 73.9%, 94% and 100% reduction in tumour size for late-, intermediate-, and early-stage TNBC, respectively. We also detected molecular-level perturbations in the expression patterns of several genes linked to breast cancer and cholesterol signalling pathways using RT²-PCR arrays and have identified SFRP1 as a direct binding partner to HPβCD through SPR drug interaction analysis. This work unravels mechanistic insights into HPβCD-induced cholesterol depletion, which leads to intrinsic apoptosis induction. Results from this study potentiate employing cholesterol depletion as a promising unconventional anticancer therapeutic strategy, which warrants future clinical investigations.

Pleotropic effects of statins: the dilemma of wider utilization of statin

BACKGROUND

Apart from reducing the circulating LDL-c and the number of cardiovascular cases as well as fatalities, statins have auxiliary non-lipid-related or cholesterol independent effects, the pleiotropic effects. The aim of the present review is to understand the pleotropic effects of statins.

MAIN BODY

Cardiovascular disease (CVD) is presently the major cause of patient misery as well as mortality among non-communicable diseases (NCDs) in the world. Despite the fact that statins are the most extensively affirmed, prescribed and evidence-based lipid-lowering medicine worldwide that curtail low density lipoprotein cholesterol (LDL-c) levels and the number of cardiovascular cases as well as deaths, statins also elicit auxiliary non-lipid-related or cholesterol independent effects, the pleiotropic effects. Improved endothelial function, significantly lowered oxidative stress, atherosclerotic plaque stabilization, immunomodulatory, cessation of vascular smooth muscle proliferation, effects on bone metabolism, anti-inflammatory, antithrombotic effects, and reduced risk of dementia are among these pleotropic effects. Statins have also been explored for its uses in life threatening diseases like cancer and inflammatory bowel disease. They have been demonstrated to revamp vascular tone. Many research and review articles have been thoroughly studied for this systematic review.

CONCLUSIONS

Statins have not only shown to be benefitial in lowering the levels of LDL-C but have also been established to be advantageous in the treatment of cancer, neurological conditions like dementia, multiple sclerosis, inflammatory bowel disease. Future high-quality trials are needed to include statins in the treatment of these conditions as per guidelines.

Emerging Hallmarks of Metabolic Reprogramming in Prostate Cancer

Prostate cancer (PCa) is the most common male malignancy and the fifth leading cause of cancer death in men worldwide. Prostate cancer cells are characterized by a hybrid glycolytic/oxidative phosphorylation phenotype determined by androgen receptor signaling. An increased lipogenesis and cholesterogenesis have been described in PCa cells. Many studies have shown that enzymes involved in these pathways are overexpressed in PCa. Glutamine becomes an essential amino acid for PCa cells, and its metabolism is thought to become an attractive therapeutic target. A crosstalk between cancer and stromal cells occurs in the tumor microenvironment because of the release of different cytokines and growth factors and due to changes in the extracellular matrix. A deeper insight into the metabolic changes may be obtained by a multi-omic approach integrating genomics, transcriptomics, metabolomics, lipidomics, and radiomics data.

Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

Role of Lipids and Lipid Metabolism in Prostate Cancer Progression and the Tumor’s Immune Environment

Modulation of lipid metabolism during cancer development and progression is one of the hallmarks of cancer in solid tumors; its importance in prostate cancer (PCa) has been demonstrated in numerous studies. Lipid metabolism is known to interact with androgen receptor signaling, an established driver of PCa progression and castration resistance. Similarly, immune cell infiltration into prostate tissue has been linked with the development and progression of PCa as well as with disturbances in lipid metabolism. Immuno-oncological drugs inhibit immune checkpoints to activate immune cells’ abilities to recognize and destroy cancer cells. These drugs have proved to be successful in treating some solid tumors, but in PCa their efficacy has been poor, with only a small minority of patients demonstrating a treatment response. In this review, we first describe the importance of lipid metabolism in PCa. Second, we collate current information on how modulation of lipid metabolism of cancer cells and the surrounding immune cells may impact the tumor’s immune responses which, in part, may explain the unimpressive results of immune-oncological treatments in PCa.

Cardiometabolic Comorbidities in Cancer Survivors

There are nearly 17 million cancer survivors in the United States, including those who are currently receiving cancer therapy with curative intent and expected to be long-term survivors, as well as those with chronic cancers such as metastatic disease or chronic lymphocytic leukemia, who will receive cancer therapy for many years. Current clinical practice guidelines focus on lifestyle interventions, such as exercise and healthy eating habits, but generally do not address management strategies for clinicians or strategies to increase adherence to medications. We discuss 3 cardiometabolic comorbidities among cancer survivors and present the prevalence of comorbidities prior to a cancer diagnosis, treatment of comorbidities during cancer therapy, and management considerations of comorbidities in long-term cancer survivors or those on chronic cancer therapy. Approaches to support medication adherence and potential methods to enhance a team approach to optimize care of the individual with cancer across the continuum of disease are discussed.

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Cancer survivors are at increased risk for several chronic conditions, including hypertension, dyslipidemia, and diabetes.

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Determining optimal management of comorbidities for patients with cancer is critical.

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A multidisciplinary care approach is recommended throughout the continuum of active cancer treatment and survivorship.

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Survivorship research should focus on medication adherence and coordination of care.

Randomised double-blind phase 3 clinical study testing impact of atorvastatin on prostate cancer progression after initiation of androgen deprivation therapy: study protocol

INTRODUCTION

Blood cholesterol is likely a risk factor for prostate cancer prognosis and use of statins is associated with lowered risk of prostate cancer recurrence and progression. Furthermore, use of statins has been associated with prolonged time before development of castration resistance (CR) during androgen deprivation therapy (ADT) for prostate cancer. However, the efficacy of statins on delaying castration-resistance has not been tested in a randomised placebo-controlled setting.This study aims to test statins' efficacy compared to placebo in delaying development of CR during ADT treatment for primary metastatic or recurrent prostate cancer. Secondary aim is to explore effect of statin intervention on prostate cancer mortality and lipid metabolism during ADT.

METHODS AND ANALYSIS

In this randomised placebo-controlled trial, a total of 400 men with de novo metastatic prostate cancer or recurrent disease after primary treatment and starting ADT will be recruited and randomised 1:1 to use daily 80 mg of atorvastatin or placebo. All researchers, study nurses and patients will be blinded throughout the trial. Patients are followed until disease recurrence or death. Primary outcome is time to formation of CR after initiation of ADT. Serum lipid levels (total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and trigyserides) are analysed to test whether changes in serum cholesterol parameters during ADT predict length of treatment response. Furthermore, the trial will compare quality of life, cardiovascular morbidity, changes in blood glucose and circulating cell-free DNA, and urine lipidome during trial.

ETHICS AND DISSEMINATION

This study is approved by the Regional ethics committees of the Pirkanmaa Hospital District, Science centre, Tampere, Finland (R18065M) and Tarto University Hospital, Tarto, Estonia (319/T-6). All participants read and sign informed consent form before study entry. After publication of results for the primary endpoints, anonymised summary metadata and statistical code will be made openly available. The data will not include any information that could make it possible to identify a given participant.

TRIAL REGISTRATION NUMBER

Clinicaltrial.gov: NCT04026230, Eudra-CT: 2016-004774-17, protocol code: ESTO2, protocol date 10 September 2020 and version 6.

Involvement of LDL and ox-LDL in Cancer Development and Its Therapeutical Potential

Lipid metabolism disorder is related to an increased risk of tumorigenesis and is involved in the rapid growth of cancer cells as well as the formation of metastatic lesions. Epidemiological studies have demonstrated that low-density lipoprotein (LDL) and oxidized low-density lipoprotein (ox-LDL) are closely associated with breast cancer, colorectal cancer, pancreatic cancer, and other malignancies, suggesting that LDL and ox-LDL play important roles during the occurrence and development of cancers. LDL can deliver cholesterol into cancer cells after binding to LDL receptor (LDLR). Activation of PI3K/Akt/mTOR signaling pathway induces transcription of the sterol regulatory element-binding proteins (SREBPs), which subsequently promotes cholesterol uptake and synthesis to meet the demand of cancer cells. Ox-LDL binds to the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and cluster of differentiation 36 (CD36) to induce mutations, resulting in inflammation, cell proliferation, and metastasis of cancer. Classic lipid-lowering drugs, statins, have been shown to reduce LDL levels in certain types of cancer. As LDL and ox-LDL play complicated roles in cancers, the potential therapeutic effect of targeting lipid metabolism in cancer therapy warrants more investigation.

The relationship between lipoprotein A and other lipids with prostate cancer risk: A multivariable Mendelian randomisation study

BACKGROUND

Numerous epidemiological studies have investigated the role of blood lipids in prostate cancer (PCa) risk, though findings remain inconclusive to date. The ongoing research has mainly involved observational studies, which are often prone to confounding. This study aimed to identify the relationship between genetically predicted blood lipid concentrations and PCa.

METHODS AND FINDINGS

Data for low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides (TG), apolipoprotein A (apoA) and B (apoB), lipoprotein A (Lp(a)), and PCa were acquired from genome-wide association studies in UK Biobank and the PRACTICAL consortium, respectively. We used a two-sample summary-level Mendelian randomisation (MR) approach with both univariable and multivariable (MVMR) models and utilised a variety of robust methods and sensitivity analyses to assess the possibility of MR assumptions violation. No association was observed between genetically predicted concentrations of HDL, TG, apoA and apoB, and PCa risk. Genetically predicted LDL concentration was positively associated with total PCa in the univariable analysis, but adjustment for HDL, TG, and Lp(a) led to a null association. Genetically predicted concentration of Lp(a) was associated with higher total PCa risk in the univariable (ORweighted median per standard deviation (SD) = 1.091; 95% CI 1.028 to 1.157; P = 0.004) and MVMR analyses after adjustment for the other lipid traits (ORIVW per SD = 1.068; 95% CI 1.005 to 1.134; P = 0.034). Genetically predicted Lp(a) was also associated with advanced (MVMR ORIVW per SD = 1.078; 95% CI 0.999 to 1.163; P = 0.055) and early age onset PCa (MVMR ORIVW per SD = 1.150; 95% CI 1.015,1.303; P = 0.028). Although multiple estimation methods were utilised to minimise the effect of pleiotropy, the presence of any unmeasured pleiotropy cannot be excluded and may limit our findings.

CONCLUSIONS

We observed that genetically predicted Lp(a) concentrations were associated with an increased PCa risk. Future studies are required to understand the underlying biological pathways of this finding, as it may inform PCa prevention through Lp(a)-lowering strategies.

Outcomes of Screening for Prostate Cancer Among Men Who Use Statins

Importance

Prostate-specific antigen (PSA) screening for prostate cancer has resulted in a slight reduction in prostate cancer mortality but also a concomitant overdiagnosis of low-risk tumors. Prostate-specific antigen levels are affected by use of cholesterol-lowering statin drugs, but the association of statin use with PSA screening performance is unknown.

Objective

To investigate whether statin use was associated with outcomes of a randomized PSA-based prostate cancer screening intervention.

Design, Setting, and Participants

This post hoc subgroup analysis of a cohort from a population-based randomized clinical trial used data from the population-based Finnish Randomized Study of Prostate Cancer Screening, which randomized men to PSA screening or routine care from March 1, 1996, to December 31, 1999, with follow-up continuing until December 31, 2015. The population included all men aged 55 to 67 years at baseline and residing in the Tampere or Helsinki districts of Finland. Information on statin purchases from 1996 to 2009 was obtained from a national prescription registry. Eligible men were identified from the population registry of Finland. Prevalent prostate cancer cases at baseline were excluded. Data were analyzed from January 1, 2019 to March 31, 2021.

Interventions

Three invitations for PSA screening at 4-year intervals from 1996 to 2007 vs routine care.

Main Outcomes and Measures

Risk for prostate cancer overall, high-risk disease, and prostate cancer mortality in the screening group vs the control group as an intention-to-treat analysis. The analysis was stratified by statin use.

Results

The study comprised 78 606 men (median age, 59 years [range, 55-67 years]) with statin purchase data available. Although PSA screening was associated with increased prostate cancer incidence among statin nonusers (screening vs control, 11.2 vs 8.6 per 1000 person-years); rate ratio [RR], 1.31; 95% CI, 1.24-1.38), no similar increase in incidence was observed among statin users (6.9 vs 5.9 per 1000 person-years; RR, 1.02; 95% CI, 0.95-1.10; P < .001 for interaction). Incidence of low-risk (Gleason score 6) and localized tumors was lower among statin users, whereas detection of tumors with a Gleason score of 8 to 10 was similar. Screening was associated with a lower incidence of metastatic tumors regardless of statin use.

Conclusion and Relevance

In this post hoc subgroup analysis of a cohort from a population-based randomized clinical trial, PSA screening among statin users was associated with a decreased incidence of advanced prostate cancer that was similar among statin nonusers, but with less increase in detection of low-grade localized tumors in statin users than in nonusers. These findings suggest that statin use does not materially compromise benefits of PSA-based screening.

Lipoproteins as Markers for Monitoring Cancer Progression

Lipoproteins are among the contributors of energy for the survival of cancer cells. Studies indicate there are complex functions and metabolism of lipoproteins in cancer. The current review is aimed at providing updates from studies related to the monitoring of lipoproteins in different types of cancer. This had led to numerous clinical and experimental studies. The review covers the major lipoproteins such as LDL cholesterol (LDL-C), oxidized low-density lipoprotein cholesterol (oxLDL-C), very low-density lipoprotein cholesterol (VLDL-C), and high-density lipoprotein cholesterol (HDL-C). This is mainly due to increasing evidence from clinical and experimental studies that relate association of lipoproteins with cancer. Generally, a significant association exists between LDL-C with carcinogenesis and high oxLDL with metastasis. This warrants further investigations to include Mendelian randomization design and to be conducted in a larger population to confirm the significance of LDL-C and its oxidized form as prognostic markers of cancer.

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

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

Atorvastatin induces adrenal androgen downshift in men with prostate cancer: A post Hoc analysis of a pilot adaptive Randomised clinical trial

BACKGROUND

Prostate cancer (PCa) progression depends on androgen receptor activity. Cholesterol is required for biosynthesis of all steroid hormones, including androgens. Impact of cholesterol-lowering statins on androgens is unknown. We explored atorvastatin influence on serum and prostatic tissue steroidomic profiles (SP) to expose novel pathways for limiting androgen concentration in men with PCa.

METHODS

This is a pre-planned post hoc analysis of ESTO-1 pilot randomised, double-blinded, clinical trial. Statin naïve men, scheduled for radical prostatectomy due to localised PCa, were randomised 1:1 to use daily 80 mg of atorvastatin or placebo before the surgery for a median of 28 days. Participants were recruited and treated at the Pirkanmaa Hospital District, Tampere, Finland. 108 of the 158 recruited men were included in the analysis based on sample availability for hormone profiling. Serum and prostatic tissue steroid profiles were determined using liquid chromatography mass spectrometry. Wilcoxon rank sum test and bootstrap confidence intervals (CI) were used to analyse the difference between placebo and atorvastatin arms.

FINDINGS

Most serum and prostatic steroids, including testosterone and dihydrotestosterone, were not associated with atorvastatin use. However, atorvastatin use induced serum SP changes in 11-ketoandrostenedione (placebo 960pM, atorvastatin 617.5pM, p-value <0.0001, median difference -342.5; 95% CI -505.23 - -188.98). In the prostatic tissue, atorvastatin was associated with plausible downshift in 11- ketodihydrotestosterone (placebo 25.0pM in 100 mg tissue/1 mL saline, atorvastatin 18.5pM in 100 mg tissue/1 mL saline, p-value 0.027, median difference -6.53; 95% CI -12.8 - -0.29); however, this association diminished after adjusting for multiple testing. No serious harms were reported.

INTERPRETATION

Atorvastatin was associated with adrenal androgen downshift in the serum and possibly in the prostate. The finding warrants further investigation whether atorvastatin could improve androgen deprivation therapy efficacy.

FUNDING

Funded by grants from the Finnish Cultural Foundation, Finnish Cancer Society, Academy of Finland, and the Expert Responsibility Area of the Tampere University Hospital. CLINICALTRIALS.

GOV IDENTIFIER

NCT01821404.

PCSK9 and cancer: Rethinking the link

BACKGROUND

Cancer is emerging as a major problem globally, as it accounts for the second cause of death despite medical advances. According to epidemiological and basic studies, cholesterol is involved in cancer progression and there are abnormalities in cholesterol metabolism of cancer cells including prostate, breast, and colorectal carcinomas. However, the importance of cholesterol in carcinogenesis and thereby the role of cholesterol homeostasis as a therapeutic target is still a debated area in cancer therapy. Proprotein convertase subtilisin/kexin type-9 (PCSK9), a serine protease, modulates cholesterol metabolism by attachment to the LDL receptor (LDLR) and reducing its recycling by targeting the receptor for lysosomal destruction. Published research has shown that PCSK9 is also involved in degradation of other LDLR family members namely very-low-density-lipoprotein receptor (VLDLR), lipoprotein receptor-related protein 1 (LRP-1), and apolipoprotein E receptor 2 (ApoER2). As a result, this protein represents an interesting therapeutic target for the treatment of hypercholesterolemia. Interestingly, clinical trials on PCSK9-specific monoclonal antibodies have reported promising results with high efficacy in lowering LDL-C and in turn reducing cardiovascular complications. It is important to note that PCSK9 mediates several other pathways apart from its role in lipid homeostasis, including antiviral activity, hepatic regeneration, neuronal apoptosis, and modulation of various signaling pathways. Furthermore, recent literature has illustrated that PCSK9 is closely associated with incidence and progression of several cancers. In a number of studies, PCSK9 siRNA was shown to effectively suppress the proliferation and invasion of the several studied tumor cells. Hence, a novel application of PCSK9 inhibitors/silencers in cancer/metastasis could be considered. However, due to poor data on effectiveness and safety of PCSK9 inhibitors in cancer, the impact of PCSK9 inhibition in these pathological conditions is still unknown.

SEARCH METHODS

A vast literature search was conducted to find intended studies from 1956 up to 2020, and inclusion criteria were original peer-reviewed publications.

PURPOSE OF REVIEW

To date, PCSK9 has been scantly investigated in cancer. The question that needs to be discussed is "How does PCSK9 act in cancer pathophysiology and what are the risks or benefits associated to its inhibition?". We reviewed the available publications highlighting the contribution of this proprotein convertase in pathways related to cancer, with focus on the potential implications of its long-term pharmacological inhibition in cancer therapy.

Serum lipids and prostate cancer

BACKGROUND

Conflicting results are found in the literature relating serum lipids levels and prostate cancer. Some results imply a relationship between them; others contradict this association. The purpose of this study was to investigate a possible association between serum lipids levels and prostate cancer, at time of diagnosis.

METHODS

We measured serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides in 237 patients submitted to a prostate biopsy, with PSA between 2 and 10 ng/ml. Patients without cancer at biopsy were used as controls, and the others were considered as cases. No information about lipid-lowering therapy, including statins, was available neither in cases nor in controls. Cases were divided into risk groups, according to the disease severity, based on staging. Lipids levels were compared between groups, using parametric and nonparametric tests. Logistic regression analysis and odds ratios were calculated.

RESULTS

LDL and total cholesterol levels were lower in patients with cancer, with the difference being statistically significant for LDL cholesterol (p = 0.010) and borderline for total cholesterol (p = 0.050). No significant differences were found between the several risk groups. Odds ratios for low LDL cholesterol (<130 mg/dl) and low total cholesterol (<200 mg/dl), with prostate cancer as the outcome, were 1.983 and 1.703, respectively. There were no significant differences between cases and controls for the other lipids.

CONCLUSION

Lower LDL cholesterol (<130 mg/dl) and lower total cholesterol (<200 mg/dl) serum levels seem to associate with prostate cancer, at time of diagnosis.

Influence of cholesterol on cancer progression and therapy

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Abnormality in blood cholesterol level is significantly correlated with risk of different cancers.

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Majority of tumor tissue from cancer patient exhibits overexpression of LDLR and ACAT for supporting rapid cancer cell proliferation.

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Alteration of the cholesterol metabolism in cancer cells hampers therapeutic response.

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Targeting cholesterol metabolism for treatment of cancer with other conventional chemotherapeutic drugs appears to be beneficial.

Cholesterol is a fundamental molecule necessary for the maintenance of cell structure and is vital to various normal biological functions. It is a key factor in lifestyle-related diseases including obesity, diabetes, cardiovascular disease, and cancer. Owing to its altered serum chemistry status under pathological states, it is now being investigated to unravel the mechanism by which it triggers various health complications. Numerous clinical studies in cancer patients indicate an alteration in blood cholesterol level (either decreased or increased) in comparison to normal healthy individuals. This article elaborates on our understanding as to how cholesterol is being hijacked in the malignancy for the development, survival, stemness, progression, and metastasis of cancerous cells. Also, it provides a glimpse of how cholesterol derived entities, alters the signaling pathway towards their advantage. Moreover, deregulation of the cholesterol metabolism pathway has been often reported to hamper various treatment strategies in different cancer. In this context, attempts have been made to bring forth its relevance in being targeted, in pre-clinical and clinical studies for various treatment modalities. Thus, understanding the role of cholesterol and deciphering associated molecular mechanisms in cancer progression and therapy are of relevance towards improvement in the management of various cancers.

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

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

Pharmacoepidemiological Evaluation in Prostate Cancer-Common Pitfalls and How to Avoid Them

Simple Summary

Pharmacoepidemiologic research provides opportunities to evaluate how commonly used drug groups, such as cholesterol-lowering drugs, may affect the prostate cancer risk or mortality. However, such studies need to be carefully designed in order to avoid biases caused by systematic differences between medication users and non-users. Similarly, data must be carefully analyzed and interpreted while acknowledging possible biases that can lead to erroneous conclusions. Here, we review common pitfalls in such studies and describe ways to avoid them in an effort to aid future research.

Abstract

Pharmacoepidemiologic research provides opportunities to evaluate how commonly used drug groups, such as cholesterol-lowering or antidiabetic drugs, may affect the prostate cancer risk or mortality. This type of research is valuable in estimating real-life drug effects. Nonetheless, pharmacoepidemiological studies are prone to multiple sources of bias that mainly arise from systematic differences between medication users and non-users. If these are not appreciated and properly controlled for, there is a risk of obtaining biased results and reaching erroneous conclusions. Therefore, in order to improve the quality of future research, we describe common biases in pharmacoepidemiological studies, particularly in the context of prostate cancer research. We also list common ways to mitigate these biases and to estimate causality between medication use and cancer outcomes.

Obesity, Type 2 Diabetes, and Cancer Risk

Obesity and type 2 diabetes have both been associated with increased cancer risk and are becoming increasingly prevalent. Metabolic abnormalities such as insulin resistance and dyslipidemia are associated with both obesity and type 2 diabetes and have been implicated in the obesity-cancer relationship. Multiple mechanisms have been proposed to link obesity and diabetes with cancer progression, including an increase in insulin/IGF-1 signaling, lipid and glucose uptake and metabolism, alterations in the profile of cytokines, chemokines, and adipokines, as well as changes in the adipose tissue directly adjacent to the cancer sites. This review aims to summarize and provide an update on the epidemiological and mechanistic evidence linking obesity and type 2 diabetes with cancer, focusing on the roles of insulin, lipids, and adipose tissue.

Revisiting prostate cancer metabolism: From metabolites to disease and therapy

Prostate cancer (PCa), one of the most commonly diagnosed cancers worldwide, still presents important unmet clinical needs concerning treatment. In the last years, the metabolic reprogramming and the specificities of tumor cells emerged as an exciting field for cancer therapy. The unique features of PCa cells metabolism, and the activation of specific metabolic pathways, propelled the use of metabolic inhibitors for treatment. The present work revises the knowledge of PCa metabolism and the metabolic alterations that underlie the development and progression of the disease. A focus is given to the role of bioenergetic sources, namely, glucose, lipids, and glutamine sustaining PCa cell survival and growth. Moreover, it is described as the action of oncogenes/tumor suppressors and sex steroid hormones in the metabolic reprogramming of PCa. Finally, the status of PCa treatment based on the inhibition of metabolic pathways is presented. Globally, this review updates the landscape of PCa metabolism, highlighting the critical metabolic alterations that could have a clinical and therapeutic interest.

LDL, HDL and endocrine-related cancer: From pathogenic mechanisms to therapies

Cholesterol is essential for a variety of functions in endocrine-related cells, including hormone and steroid production. We have reviewed the progress to date in research on the role of the main cholesterol-containing lipoproteins; low-density lipoprotein (LDL) and high-density lipoprotein (HDL), and their impact on intracellular cholesterol homeostasis and carcinogenic pathways in endocrine-related cancers. Neither LDL-cholesterol (LDL-C) nor HDL-cholesterol (HDL-C) was consistently associated with endocrine-related cancer risk. However, preclinical studies showed that LDL receptor plays a critical role in endocrine-related tumor cells, mainly by enhancing circulating LDL-C uptake and modulating tumorigenic signaling pathways. Although scavenger receptor type BI-mediated uptake of HDL could enhance cell proliferation in breast, prostate, and ovarian cancer, these effects may be counteracted by the antioxidant and anti-inflammatory properties of HDL. Moreover, 27-hydroxycholesterol a metabolite of cholesterol promotes tumorigenic processes in breast and epithelial thyroid cancer. Furthermore, statins have been reported to reduce the incidence of breast, prostate, pancreatic, and ovarian cancer in large clinical trials, in part because of their ability to lower cholesterol synthesis. Overall, cholesterol homeostasis deregulation in endocrine-related cancers offers new therapeutic opportunities, but more mechanistic studies are needed to translate the preclinical findings into clinical therapies.

Circulatory and prostatic tissue lipidomic profiles shifts after high-dose atorvastatin use in men with prostate cancer

Prostate cancer patients using cholesterol-lowering statins have 30% lower risk of prostate cancer death compared to non-users. The effect is attributed to the inhibition of the mevalonate pathway in prostate cancer cells. Moreover, statin use causes lipoprotein metabolism changes in the serum. Statin effect on serum or intraprostatic lipidome profiles in prostate cancer patients has not been explored. We studied changes in the serum metabolomic and prostatic tissue lipidome after high-dose 80 mg atorvastatin intervention to expose biological mechanisms causing the observed survival benefit. Our randomized, double-blind, placebo-controlled clinical trial consisted of 103 Finnish men with prostate cancer. We observed clear difference in post-intervention serum lipoprotein lipid profiles between the study arms (median classification error 11.7%). The atorvastatin effect on intraprostatic lipid profile was not as clear (median classification error 44.7%), although slightly differing lipid profiles by treatment arm was observed, which became more pronounced in men who used atorvastatin above the median of 27 days (statin group median classification error 27.2%). Atorvastatin lowers lipids important for adaptation for hypoxic microenvironment in the prostate suggesting that prostate cancer cell survival benefit associated with statin use might be mediated by both, local and systemic, lipidomic/metabolomic profile changes.

Alterations in glycolytic/cholesterogenic gene expression in hepatocellular carcinoma

Metabolic reprogramming is a hallmark of tumors, including hepatocellular carcinoma (HCC). We used data from The Cancer Genome Atlas and the International Cancer Genome Consortium to assess the alterations in glycolytic and cholesterogenic genes in HCC and to determine their association with clinical features in HCC patients. Based on the gene expression profiles from these databases, we established four subtypes of HCC: cholesterogenic, glycolytic, mixed, and quiescent. The prognosis of the cholesterogenic subgroup was poorer than that of the glycolytic group. Tumors in the glycolytic group were more sensitive to chemotherapy. We also explored the relationships between these metabolic subtypes and previously established HCC subgroups. Glycolytic gene expression correlated strongly with poorer prognostic gene expression in the Hoshida classification of HCC. Whole-genome analyses indicated that aberrant amplification of TP53 and MYC in HCC were associated with abnormal anabolic cholesterol metabolism. The mRNA levels of mitochondrial pyruvate carriers 1 and 2 differed among the HCC metabolic subtypes. In a bioinformatics analysis we identified genomic characteristics of tumor metabolism that varied among different cancer types. These findings demonstrate that metabolic subtypes may be valuable prognostic indicators in HCC patients.

ASPP2 inhibits tumor growth by repressing the mevalonate pathway in hepatocellular carcinoma

Cancer is, fundamentally, a disorder of cell growth and proliferation, which requires adequate supplies of energy and nutrients. In this study, we report that the haplo-insufficient tumor suppressor ASPP2, a p53 activator, negatively regulates the mevalonate pathway to mediate its inhibitory effect on tumor growth in hepatocellular carcinoma (HCC). Gene expression profile analysis revealed that the expression of key enzymes in the mevalonate pathway were increased when ASPP2 was downregulated. HCC cells gained higher cholesterol levels and enhanced tumor-initiating capability in response to the depletion of ASPP2. Simvastatin, a mevalonate pathway inhibitor, efficiently abrogated ASPP2 depletion-induced anchorage-independent cell proliferation, resistance to chemotherapy drugs in vitro, and tumor growth in xenografted nude mice. Mechanistically, ASPP2 interacts with SREBP-2 in the nucleus and restricts the transcriptional activity of SREBP-2 on its target genes, which include key enzymes involved in the mevalonate pathway. Moreover, clinical data revealed better prognosis in patients with high levels of ASPP2 and low levels of the mevalonate pathway enzyme HMGCR. Our findings provide functional and mechanistic insights into the critical role of ASPP2 in the regulation of the mevalonate pathway and the importance of this pathway in tumor initiation and tumor growth, which may provide a new therapeutic opportunity for HCC.

Cholesterol and 27-hydroxycholesterol promote thyroid carcinoma aggressiveness

Cholesterol mediates its proliferative and metastatic effects via the metabolite 27-hydroxycholesterol (27-HC), at least in breast and endometrial cancer. We determined the serum lipoprotein profile, intratumoral cholesterol and 27-HC levels in a cohort of patients with well-differentiated papillary thyroid carcinoma (PTC; low/intermediate and high risk), advanced thyroid cancers (poorly differentiated, PDTC and anaplastic thyroid carcinoma, ATC) and benign thyroid tumors, as well as the expression of genes involved in cholesterol metabolism. We investigated the gene expression profile, cellular proliferation, and migration in Nthy-ori 3.1 and CAL-62 cell lines loaded with human low-density lipoprotein (LDL). Patients with more aggressive tumors (high-risk PTC and PDTC/ATC) showed a decrease in blood LDL cholesterol and apolipoprotein B. These changes were associated with an increase in the expression of the thyroid’s LDL receptor, whereas 3-hydroxy-3-methylglutaryl-CoA reductase and 25-hydroxycholesterol 7-alpha-hydroxylase were downregulated, with an intratumoral increase of the 27-HC metabolite. Furthermore, LDL promoted proliferation in both the Nthy-ori 3.1 and CAL-62 thyroid cellular models, but only in ATC cells was its cellular migration increased significantly. We conclude that cholesterol and intratumoral accumulation of 27-HC promote the aggressive behavior process of PTC. Targeting cholesterol metabolism could be a new therapeutic strategy in thyroid tumors with poor prognosis.

Influence of serum total cholesterol, LDL, HDL, and triglyceride on prostate cancer recurrence after radical prostatectomy

Purpose

The clinical impacts of serum lipid levels on prostate cancer recurrence after radical prostatectomy have been evaluated by several observational studies with conflicting results. We performed the present meta-analysis to summarize the evidence evaluating the role of serum lipid profile in prostate cancer patients.

Methods

We comprehensively searched the PubMed database for potentially relevant studies through January 2019. Pooled hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) for the highest versus the lowest level of serum lipid levels were calculated with the DerSimonian and Laird random-effects model.

Results

A total of 12 eligible studies with 10,978 prostate cancer cases were included in this study. The pooled HRs of prostate cancer recurrence after racial prostatectomy were 0.92 (95% CI 0.73–1.16, P=0.462), 0.87 (95% CI 0.56–1.35, P=0.535), 1.09 (95% CI 0.92–1.30, P=0.320), and 1.01 (95% CI 0.78–1.31, P=0.938) for serum total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglyceride, respectively. Sensitivity analysis was conducted by excluding each study sequentially and the results showed that all the summary risk estimates were stable and not influenced by any single study.

Conclusion

The present meta-analysis indicated that serum lipid levels in patients undergoing radical prostatectomy were not associated with prostate cancer recurrence.

Removal of Serum Lipids and Lipid-Derived Metabolites to Investigate Breast Cancer Cell Biology

The use of cultured cells has been instrumental in studying biochemical, molecular, and cellular processes. The composition of serum that cells are maintained in can have a profound impact on important cellular checkpoints. Cell growth and apoptosis are analyzed in an estrogen receptor positive breast cancer cell line in the presence of serum that have been treated to remove steroids or lipids, as well-described in the literature. It is shown that maintaining cells in the presence of charcoal-dextran-treated serum causes reduced growth rate, which can be reversed by the addition of estradiol. Silica-treated-serum also slows down cell growth and induces apoptosis. In order to investigate the role of lipids in these phenotypes, the levels of a wide range of lipids in different sera are investigated. It is shown that silica-treatment significantly depletes phosphatidylcholines and cholesterol. It is also shown that lipogenesis is stimulated when cells are cultured with silica-treated-serum and this is reversed by the addition of exogenous lipids, which also restores growth rate and apoptosis. The results show that cultured cells are sensitive to different serum, most likely due to the differences in levels of structural and signaling metabolites present in their growth environment.

The Potential of Isoprenoids in Adjuvant Cancer Therapy to Reduce Adverse Effects of Statins

The mevalonate pathway provides sterols for membrane structure and nonsterol intermediates for the post-translational modification and membrane anchorage of growth-related proteins, including the Ras, Rac, and Rho GTPase family. Mevalonate-derived products are also essential for the Hedgehog pathway, steroid hormone signaling, and the nuclear localization of Yes-associated protein and transcriptional co-activator with PDZ-binding motif, all of which playing roles in tumorigenesis and cancer stem cell function. The phosphatidylinositol-4,5-bisphosphate 3-kinase-AKT-mammalian target of rapamycin complex 1 pathway, p53 with gain-of-function mutation, and oncoprotein MYC upregulate the mevalonate pathway, whereas adenosine monophosphate-activated protein kinase and tumor suppressor protein RB are the downregulators. The rate-limiting enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), is under a multivalent regulation. Sterol regulatory element binding protein 2 mediates the sterol-controlled transcriptional downregulation of HMGCR. UbiA prenyltransferase domain-containing protein-1 regulates the ubiquitination and proteasome-mediated degradation of HMGCR, which is accelerated by 24, 25-dihydrolanosterol and the diterpene geranylgeraniol. Statins, competitive inhibitors of HMGCR, deplete cells of mevalonate-derived intermediates and consequently inhibit cell proliferation and induce apoptosis. Clinical application of statins is marred by dose-limiting toxicities and mixed outcomes on cancer risk, survival and mortality, partially resulting from the statin-mediated compensatory upregulation of HMGCR and indiscriminate inhibition of HMGCR in normal and tumor cells. Tumor HMGCR is resistant to the sterol-mediated transcriptional control; consequently, HMGCR is upregulated in cancers derived from adrenal gland, blood and lymph, brain, breast, colon, connective tissue, embryo, esophagus, liver, lung, ovary, pancreas, prostate, skin, and stomach. Nevertheless, tumor HMGCR remains sensitive to isoprenoid-mediated degradation. Isoprenoids including monoterpenes (carvacrol, L-carvone, geraniol, perillyl alcohol), sesquiterpenes (cacalol, farnesol, β-ionone), diterpene (geranylgeranyl acetone), “mixed” isoprenoids (tocotrienols), and their derivatives suppress the growth of tumor cells with little impact on non-malignant cells. In cancer cells derived from breast, colon, liver, mesothelium, prostate, pancreas, and skin, statins and isoprenoids, including tocotrienols, geraniol, limonene, β-ionone and perillyl alcohol, synergistically suppress cell proliferation and associated signaling pathways. A blend of dietary lovastatin and δ-tocotrienol, each at no-effect doses, suppress the growth of implanted murine B16 melanomas in C57BL6 mice. Isoprenoids have potential as adjuvant agents to reduce the toxicities of statins in cancer prevention or therapy.

High-Density Lipoprotein Components and Functionality in Cancer: State-of-the-Art

Cancer is the second leading cause of death in western countries, and thus represents a major global public health issue. Whilst it is well-recognized that diet, obesity, and smoking are risk factors for cancer, the role of low levels of high-density lipoprotein cholesterol (HDL-C) in cancer is less well appreciated. Conflicting evidence suggests that serum HDL-C levels may be either positively or negatively associated with cancer incidence and mortality. Such disparate associations are supported in part by the multitude of high-density lipoprotein (HDL) functions that can all have an impact on cancer cell biology. The aim of this review is to provide a comprehensive overview of the crosstalk between HDLs and cancer, focusing on the molecular mechanisms underlying this association.

Serum cholesterol and prostate cancer risk in the Finnish randomized study of screening for prostate cancer

BACKGROUND

Hypercholesterolemia has been associated with advanced stage prostate cancer (PCa), but the role of lipid parameters such as HDL and triglycerides is unclear. We examined PCa risk by lipid parameters in a population nested within the Finnish Randomized Study of Screening for Prostate Cancer (FinRSPC).

METHODS

Cholesterol measurements were available on 17,696 men. During the 17-year median follow-up, 2404 PCa cases were diagnosed. Cox regression model was used to estimate hazard ratios (HR) and their 95% confidence intervals (95% CI) for overall PCa risk and stratified by Gleason grade and tumor stage. We compared normolipidemic and hyperlipidemic men on four cholesterol parameters total cholesterol (TC), HDL, LDL, and triglycerides (TG), analyzed as time-dependent variables.

RESULTS

TC in the highest tertile (above 5.1 mmol/l) and LDL above 3 mmol/l were associated with increased risk of Gleason 8-10 cancer (HR 1.42, 95% CI 1.04-1.95 and HR 1.38, 95% CI 1.02-1.86, respectively). Further, overall PCa risk was elevated in the 3-year lag time analysis by TC in the highest two tertiles (HR 1.27, 95% CI 1.05-1.54 for TC above 4.4 mmol/l, and HR 1.26, 95% CI 1.05-1.51 for TC above 5.1 mmol/l) and HDL in the highest tertile (HR 1.33, 95% CI 1.08-1.64) and above 1 mmol/l (HR 1.29, 95% CI 1.01-1.65). In contrast, TC in the highest tertile was associated with a decreased risk of PCa with 20-year lag time. The risk associations for overall PCa grew stronger with added lag time but were observed only in the FinRSPC control arm. Statin use did not modify the risk association.

CONCLUSIONS

Hypercholesterolemia may increase overall PCa risk in short-term, inverse risk association was observed with 20-years' time lag. Similar risk increase of overall PCa was also observed for elevated HDL, conflicting with previous findings on the subject.

Inhibition of cholesterol biosynthesis overcomes enzalutamide resistance in castration-resistant prostate cancer (CRPC)

Enzalutamide, a nonsteroidal second-generation antiandrogen, has been recently approved for the management of castration-resistant prostate cancer (CRPC). Although patients can benefit from enzalutamide at the beginning of this therapy, acquired enzalutamide resistance usually occurs within a short period. This motivated us to investigate the mechanism involved and possible approaches for overcoming enzalutamide resistance in CRPC. In the present study, we found that 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), a crucial enzyme in the mevalonate pathway for sterol biosynthesis, is elevated in enzalutamide-resistant prostate cancer cell lines. HMGCR knockdown could resensitize these cells to the drug, and HMGCR overexpression conferred resistance to it, suggesting that aberrant HMGCR expression is an important enzalutamide-resistance mechanism in prostate cancer cells. Furthermore, enzalutamide-resistant prostate cancer cells were more sensitive to statins, which are HMGCR inhibitors. Of note, a combination of simvastatin and enzalutamide significantly inhibited the growth of enzalutamide-resistant prostate cancer cells in vitro and tumors in vivo Mechanistically, simvastatin decreased protein levels of the androgen receptor (AR), which was further reduced in combination with enzalutamide. We observed that the decrease in AR may occur through simvastatin-mediated inhibition of the mTOR pathway, whose activation was associated with increased HMGCR and AR expression. These results indicate that simvastatin enhances the efficacy of enzalutamide-based therapy, highlighting the therapeutic potential of statins to overcome enzalutamide resistance in CRPC.

High cholesterol in lipid rafts reduces the sensitivity to EGFR-TKI therapy in non-small cell lung cancer

Overcoming EGFR-TKI resistant which has the initial enthusiasm over substantial clinical responses is a formidable challenge on nowadays. In this study, we showed that cholesterol level in lipid rafts in gefitinib resistant non-small cell lung cancer (NSCLC) cell lines was remarkably higher than gefitinib sensitive cell line, and depletion of cholesterol increased gefitinib sensitivity. Furthermore, cholesterol-depleted enhanced gefitinib inhibit phosphorylation of EGFR, Akt-1, MEK1/2, and ERK1/2 and these were reversed in cholesterol add-back experiments. Gefitinib resistant cell lines showed high affinity of gefitinib and EGFR when cholesterol was depleted. Therefore, targeting cholesterol combined with EGFR-TKI is potentially a novel therapeutic strategy for gefitinib resistant treatment.

Simvastatin Therapy for Drug Repositioning to Reduce the Risk of Prostate Cancer Mortality in Patients With Hyperlipidemia

Prostate cancer (PCa) is one of the most commonly diagnosed cancers in the western world, and the mortality rate from PCa in Asia has been increasing recently. Statins are potent inhibitors of 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase and are commonly used for treating hyperlipidemia, with beneficial effects for cardiovascular disease and they also exhibit anti-cancer activity. However, the protective effects of statins against PCa are controversial. In this study, we investigated the effect of two types of statins (simvastatin and lovastatin) and the mortality rate of PCa patients by using the Taiwan National Health Insurance Research Database (NHIRD). A total of 15,264 PCa patients with hyperlipidemia records and medical claims from the Registry of Catastrophic Illness were enrolled. The patients were divided into two cohorts based on their statin use before the diagnosis of PCa: statin users (n = 1,827) and non-statin users (n = 1,826). The results showed that patients who used statins exhibited a significantly reduced risk of mortality from PCa [adjusted hazard ratio (HR) = 0.84, 95% CI = 0.73–0.97]. Analysis of the cumulative defined daily dose (DDD) indicated that patients who were prescribed simvastatin ≥ 180 DDD had a dramatically decreased risk of death from PCa (adjusted HR = 0.63; 95% CI = 0.51–0.77). This population-based cohort study demonstrated that statin use significantly decreased the mortality of PCa patients, and that this risk was inversely associated with the cumulative DDD of simvastatin therapy. The results of this study revealed that statins may be used for drug repositioning and in the development of a feasible approach to prevent death from PCa.

Western diet enhances benzo(a)pyrene-induced colon tumorigenesis in a polyposis in rat coli (PIRC) rat model of colon cancer

Consumption of Western diet (WD), contaminated with environmental toxicants, has been implicated as one of the risk factors for sporadic colon cancer. Our earlier studies using a mouse model revealed that compared to unsaturated dietary fat, the saturated dietary fat exacerbated the development of colon tumors caused by B(a)P. The objective of this study was to study how WD potentiates B(a)P-induced colon carcinogenesis in the adult male rats that carry a mutation in the Apc locus - the polyposis in the rat colon (PIRC) rats. Groups of PIRC rats were fed with AIN-76A standard diet (RD) or Western diet (WD) and received 25, 50, or 100 μg B(a)P/kg body weight (wt) via oral gavage for 60 days. Subsequent to exposure, rats were euthanized; colons were retrieved and preserved in 10% formalin for counting the polyp numbers, measuring the polyp size, and histological analyses. Blood samples were collected and concentrations of cholesterol, triglycerides, glucose, insulin and leptin were measured. Rats that received WD + B(a)P showed increased levels of cholesterol, triglycerides, and leptin in comparison to RD + B(a)P groups or controls. The colon tumor numbers showed a B(a)P dose-response relationship. Adenomas with high grade dysplasia were prominent in B(a)P + WD rats compared to B(a)P + RD rats and controls (p < 0.05). The larger rat model system used in this study allows for studying more advanced tumor phenotypes over a longer duration and delineating the role of diet - toxicant interactions in sporadic colon tumor development.

Cholesterol uptake and regulation in high-grade and lethal prostate cancers

Lethal prostate cancers have higher expression of squalene monooxygenase (SQLE), the second rate-limiting enzyme of cholesterol synthesis. Preclinical studies suggested that aberrant cholesterol regulators, receptors and transporters contribute to cholesterol accumulation uniformly. We assessed their association with features of aggressive cancers. In the prospective prostate cancer cohorts within the Health Professional Follow-up Study, the Physicians' Health Study and the Swedish Watchful Waiting Study, tumor mRNA expression profiling was performed. Lethal disease was defined as mortality or metastases from prostate cancer (n = 266) in contrast to non-lethal disease without metastases after >8 years of follow-up (n = 476). Associations with Gleason grade were additionally assessed using The Cancer Genome Atlas primary prostate cancer dataset (n = 333). Higher Gleason grade was associated with lower LDLR expression, lower SOAT1 and higher SQLE expression. Besides high SQLE expression, cancers that became lethal despite primary treatment were characterized by low LDLR expression (odds ratio for highest versus lowest quintile, 0.37; 95% CI 0.18-0.76) and by low SOAT1 expression (odds ratio, 0.41; 95% CI 0.21-0.83). The association of LDLR expression and lethality was not present in tumors with high IDOL expression. ABCA1, PCSK9 or SCARB1 expressions were not associated with Gleason grade or lethal cancer. In summary, prostate cancers that progress to lethal disease rely on de novo cholesterol synthesis (via SQLE), rather than transcellular uptake (via LDLR) or cholesterol esterification (via SOAT1). These results may help design pharmacotherapy for high-risk patients.

Stromal regulation of prostate cancer cell growth by mevalonate pathway enzymes HMGCS1 and HMGCR

It has been suggested that the tumor microenvironment plays an important role in tumor progression, acquisition of androgen independence, and distant metastasis in prostate cancer (PC). However, little is known about the transcriptional basis of cellular interactions in the human PC microenvironment. To clarify the mechanism of PC progression and metastasis, we investigated the interaction of PC, epithelial, and stromal cells using genome-wide gene expression profiling. We hypothesized that PC cells could induce stromal cells to differentiate into so-called cancer-associated fibroblasts (CAFs), which might contribute to cancer invasion and metastasis. Genes upregulated in normal human prostate stromal cells (PrSC) co-cultured with human PC cells (LNCaP) included the mevalonate pathway enzymes 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Knockdown of endogenous HMGCS1 or HMGCR in PC cells by shRNA resulted in a significant reduction of PC cell viability. Importantly, exogenous overexpression of HMGCS1 or HMGCR in either PC cells or prostate stromal cells stimulated PC cell growth, suggesting a possible autocrine/paracrine mechanism of action. Immunohistochemical analysis confirmed that HMGCS1 and HMGCR were overexpressed in PC stroma, especially in early stage PC. These results provide clues to the molecular mechanisms underlying PC invasion and metastasis, and suggest that HMGCS1 and HMGCR in PC, as well as in PC stroma, might serve as molecular targets for the treatment of PC.

Dissecting the role of AMP-activated protein kinase in human diseases

AMP-activated protein kinase (AMPK), known as a sensor and a master of cellular energy balance, integrates various regulatory signals including anabolic and catabolic metabolic processes. Accompanying the application of genetic methods and a plethora of AMPK agonists, rapid progress has identified AMPK as an attractive therapeutic target for several human diseases, such as cancer, type 2 diabetes, atherosclerosis, myocardial ischemia/reperfusion injury and neurodegenerative disease. The role of AMPK in metabolic and energetic modulation both at the intracellular and whole body levels has been reviewed elsewhere. In the present review, we summarize and update the paradoxical role of AMPK implicated in the diseases mentioned above and put forward the challenge encountered. Thus it will be expected to provide important clues for exploring rational methods of intervention in human diseases.

Prognostic Role of Preoperative Serum Lipid Levels in Patients Undergoing Radical Prostatectomy for Clinically Localized Prostate Cancer

BACKGROUND

The prognostic role of preoperative serum lipid levels in patients undergoing radical prostatectomy (RP) for clinically localized prostate cancer (PCa) is unclear. The aim of the present study was to investigate preoperative serum lipid levels in patients with clinically localized PCa undergoing RP and their association with clinicopathological features and oncological outcome.

METHODS

Preoperative lipid levels (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides) and statin use from consecutive patients with clinically localized PCa undergoing RP in a tertiary referral center between 2008 and 2015 were recorded and patients were followed prospectively. Logistic regression analysis was used to test the association between lipid levels and clinicopathological parameters. Lipid values were analyzed both as continuous and dichotomized variables. Univariable and multivariable Cox regression analyses were performed to identify predictors for recurrence-free survival (RFS). Recurrence was defined as rising and verified PSA levels >0.1 ng/ml.

RESULTS

Our cohort consisted of 371 men with a median age of 63 years (range 41-78 years) and a median preoperative PSA value of 6.79 ng/ml (0.43-81.4 ng/ml). Median follow-up was 28 months (1-64). No association was found between lipid levels and adverse pathological characteristics such as ≥pT3, Gleason score ≥8, positive nodal status and positive surgical margins. Recurrence occurred in 49 patients (15.4%) at a median time of 18 months (2-51 month). Compared to low LDL cholesterol, high LDL cholesterol was associated with longer RFS in univariable analysis (continuous: Hazard Ratio (HR): 0.67, 95%-Confidence Interval (CI): 0.47-0.96, P = 0.03; 3 mM cut-point: HR: 0.44, 95%-CI: 0.24-0.79, P = 0.006). Neither levels of other lipids, nor statin use were associated with RFS. Preoperative LDL cholesterol remained an independent predictor for PCa recurrence in a multivariable model adjusted for age, preoperative PSA, statin use, tumor stage, Gleason score, nodal status and surgical margin status (continuous: HR: 0.66, 95%-CI: 0.44-0.99, P = 0.04; 3 mM cut-point: HR: 0.41, 95%-CI: 0.21-0.78, P = 0.007).

CONCLUSIONS

This is the first prospective study showing the potential adverse and independent prognostic role of low preoperative LDL cholesterol levels in patients with localized PCa undergoing RP. Prostate 77:549-556, 2017. © 2017 Wiley Periodicals, Inc.

CYP27A1 Loss Dysregulates Cholesterol Homeostasis in Prostate Cancer

In this study, we used a bioinformatic approach to identify genes whose expression is dysregulated in human prostate cancers. One of the most dramatically downregulated genes identified encodes CYP27A1, an enzyme involved in regulating cellular cholesterol homeostasis. Importantly, lower CYP27A1 transcript levels were associated with shorter disease-free survival and higher tumor grade. Loss of CYP27A1 in prostate cancer was confirmed at the protein level by immunostaining for CYP27A1 in annotated tissue microarrays. Restoration of CYP27A1 expression in cells where its gene was silenced attenuated their growth in vitro and in tumor xenografts. Studies performed in vitro revealed that treatment of prostate cancer cells with 27-hydroxycholesterol (27HC), an enzymatic product of CYP27A1, reduced cellular cholesterol content in prostate cancer cell lines by inhibiting the activation of sterol regulatory-element binding protein 2 and downregulating low-density lipoprotein receptor expression. Our findings suggest that CYP27A1 is a critical cellular cholesterol sensor in prostate cells and that dysregulation of the CYP27A1/27HC axis contributes significantly to prostate cancer pathogenesis. Cancer Res; 77(7); 1662-73. ©2017 AACR.

Cholesterol Metabolism and Prostate Cancer Lethality

Cholesterol metabolism has been implicated in prostate cancer pathogenesis. Here, we assessed the association of intratumoral mRNA expression of cholesterol synthesis enzymes, transporters, and regulators in tumor specimen at diagnosis and lethal prostate cancer, defined as mortality or metastases from prostate cancer in contrast to nonlethal disease without evidence of metastases after at least 8 years of follow-up. We analyzed the prospective prostate cancer cohorts within the Health Professionals Follow-up Study (n = 249) and the Physicians' Health Study (n = 153) as well as expectantly managed patients in the Swedish Watchful Waiting Study (n = 338). The expression of squalene monooxygenase (SQLE) was associated with lethal cancer in all three cohorts. Men with high SQLE expression (>1 standard deviation above the mean) were 8.3 times (95% confidence interval, 3.5 to 19.7) more likely to have lethal cancer despite therapy compared with men with the mean level of SQLE expression. Absolute SQLE expression was associated with lethal cancer independently from Gleason grade and stage, as was a SQLE expression ratio in tumor versus surrounding benign prostate tissue. Higher SQLE expression was tightly associated with increased histologic markers of angiogenesis. Collectively, this study establishes the prognostic value of intratumoral cholesterol synthesis as measured via SQLE, its second rate-limiting enzyme. SQLE expression at cancer diagnosis is prognostic for lethal prostate cancer both after curative-intent prostatectomy and in a watchful waiting setting, possibly by facilitating micrometastatic disease. Cancer Res; 76(16); 4785-90. ©2016 AACR.

The effects of metformin and simvastatin on the growth of LNCaP and RWPE-1 prostate epithelial cell lines

The anti-diabetic drug metformin and cholesterol-lowering statins inhibit prostate cancer cell growth in vitro and have been linked with lowered risk of prostate cancer in epidemiological studies. We evaluated the effects of these drugs on cancerous and non-cancerous prostate epithelial cell lines. Cancer (LNCaP) and normal (RWPE-1) prostate epithelial cell lines were treated with pharmacologic concentrations of metformin and simvastatin alone and in combinations. Relative changes in cell number were measured with crystal violet staining method. Drug effects on apoptosis and cell cycle were measured with flow cytometry. We also measured changes in the activation and expression of a set of reported target proteins of metformin and statins with Western blotting. Metformin decreased the relative cell number of LNCaP cells by inducing G1 cell cycle block, autophagy and apoptosis, and slightly increased cytosolic ATP levels, whereas RWPE-1 cells were resistant to metformin. However, RWPE-1 cells were sensitive to simvastatin, which induced G2 cell cycle block, autophagy and apoptosis, and increased cytosolic ATP levels in these cells. Combination of metformin and simvastatin synergistically decreased cytosolic ATP levels, increased autophagy and instead of apoptosis, induced necrosis in LNCaP cells. Synergistic effects were not observed in RWPE-1 cells. These results suggest, that prostate cancer cells may be more vulnerable to combined growth-inhibiting effects of metformin and simvastatin compared to normal cells. The data presented here provide evidence for the potency of combined metformin and statin, also at pharmacologic concentrations, as a chemotherapeutic option for prostate cancer.

Statin Use and Prostate Cancer Survival in the Finnish Randomized Study of Screening for Prostate Cancer

BACKGROUND

Recent research has suggested that statins have an effect on prostate cancer prognosis. It is currently unclear how prostate cancer screening, tumor and patient characteristics, or treatment selection may affect this association.

OBJECTIVE

To evaluate the risk of prostate cancer death among statin users. To determine how disease and treatment characteristics affect the association.

DESIGN, SETTING, AND PARTICIPANTS

This is a population-based cohort study consisting of a general male population of Finland participating in the Finnish Randomized Study for Prostate Cancer Screening. The cohort of consisted of 6537 prostate cancer cases diagnosed in the Finnish Randomized Study of Screening for Prostate Cancer population during 1996-2012. The cohort was linked to the National Prescription Database for information on the use of statins and other drugs.

INTERVENTION

Statin use before and after prostate cancer diagnosis compared with nonuse.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Hazard ratios (HRs) for the risk of prostate cancer death by amount, duration, and intensity of statin use. Cox proportional hazards regression with postdiagnostic statin use as a time-dependent variable.

RESULTS

During the median follow-up of 7.5 yr postdiagnosis 617 men died of prostate cancer. Statin use after diagnosis was associated with a decreased risk of prostate cancer death (HR 0.80; 95% confidence interval 0.65-0.98). A decreasing risk trend was observed by increasing intensity of usage (doses/year). The risk decrease was clearest in men managed with androgen deprivation therapy. Prediagnostic statin use was not associated with risk of prostate cancer death (HR 0.92; 95% confidence interval 0.75-1.12).

CONCLUSIONS

Decreased risk of prostate cancer death by statin use after diagnosis suggests that statins may delay or prevent prostate cancer progression. The risk decrease was significant only in men managed with androgen deprivation therapy, but statistical power was limited to estimate the association in men managed with surgery or radiotherapy.

PATIENT SUMMARY

Use of statins after prostate cancer diagnosis was associated with a decreased risk of prostate cancer death. The risk decrease was dose-dependent and observed especially among patients treated with hormone therapy.

Blood lipids and prostate cancer: a Mendelian randomization analysis

Genetic risk scores were used as unconfounded instruments for specific lipid traits (Mendelian randomization) to assess whether circulating lipids causally influence prostate cancer risk. Data from 22,249 prostate cancer cases and 22,133 controls from 22 studies within the international PRACTICAL consortium were analyzed. Allele scores based on single nucleotide polymorphisms (SNPs) previously reported to be uniquely associated with each of low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride (TG) levels, were first validated in an independent dataset, and then entered into logistic regression models to estimate the presence (and direction) of any causal effect of each lipid trait on prostate cancer risk. There was weak evidence for an association between the LDL genetic score and cancer grade: the odds ratio (OR) per genetically instrumented standard deviation (SD) in LDL, comparing high- (≥7 Gleason score) versus low-grade (<7 Gleason score) cancers was 1.50 (95% CI: 0.92, 2.46; P = 0.11). A genetically instrumented SD increase in TGs was weakly associated with stage: the OR for advanced versus localized cancer per unit increase in genetic risk score was 1.68 (95% CI: 0.95, 3.00; P = 0.08). The rs12916-T variant in 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) was inversely associated with prostate cancer (OR: 0.97; 95% CI: 0.94, 1.00; P = 0.03). In conclusion, circulating lipids, instrumented by our genetic risk scores, did not appear to alter prostate cancer risk. We found weak evidence that higher LDL and TG levels increase aggressive prostate cancer risk, and that a variant in HMGCR (that mimics the LDL lowering effect of statin drugs) reduces risk. However, inferences are limited by sample size and evidence of pleiotropy.

Low-density lipoprotein receptors play an important role in the inhibition of prostate cancer cell proliferation by statins

Background

There are some reports about the antitumor effects of statins in these days. Statins decrease the level of cholesterol in the blood by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Inhibition of this enzyme decreases intracellular cholesterol synthesis. Thus, the expression of low-density lipoprotein receptor (LDLr) is increased to import more cholesterol from the bloodstream. In this study, we assessed the effects of statins on the proliferation of prostate cancer cells, and studied the relationship between the expression of LDLr and the effects of statins.

Methods

Simvastatin was used in the experiments. We studied the effect of simvastatin on PC-3 and LNCaP cell proliferation using the MTS assay, and evaluated the expression of LDLr after administration of simvastatin by quantitative polymerase chain reaction and Western blotting. Intracellular cholesterol levels in the prostate cancer cells were measured after administration of simvastatin. Furthermore, small interfering RNA (siRNA) was used to knockdown the gene expression of LDLr.

Results

In PC-3 cells, simvastatin inhibited cell proliferation. In LNCaP cells, only a high concentration of simvastatin (100μM) inhibited cell proliferation. In LNCaP cells, the protein level of LDLr was increased by simvastatin. In PC-3 cells, the protein levels of LDLr were unregulated. In PC-3 cells, but not in LNCaP cells, intracellular cholesterol levels were significantly decreased by simvastatin. After knocking down LDLr expression by siRNA, intracellular cholesterol levels were decreased, and cell proliferation was inhibited by simvastatin in LNCaP cells.

Conclusion

Simvastatin inhibited prostate cancer cell growth by decreasing cellular cholesterol and could be more effective in androgen-independent prostate cancer, where there is loss of regulation of LDLr expression. LDLr was shown to play an important role in the statin-induced inhibition of prostate cancer cell proliferation. These results suggest that future studies evaluating the cholesterol-lowering effects of statin may lead to new approaches to the prevention and treatment of prostate cancer.

The vitamin D receptor inhibits the respiratory chain, contributing to the metabolic switch that is essential for cancer cell proliferation

We recently described the mitochondrial localization and import of the vitamin D receptor (VDR) in actively proliferating HaCaT cells for the first time, but its role in the organelle remains unknown. Many metabolic intermediates that support cell growth are provided by the mitochondria; consequently, the identification of proteins that regulate mitochondrial metabolic pathways is of great interest, and we sought to understand whether VDR may modulate these pathways. We genetically silenced VDR in HaCaT cells and studied the effects on cell growth, mitochondrial metabolism and biosynthetic pathways. VDR knockdown resulted in robust growth inhibition, with accumulation in the G0G1 phase of the cell cycle and decreased accumulation in the M phase. The effects of VDR silencing on proliferation were confirmed in several human cancer cell lines. Decreased VDR expression was consistently observed in two different models of cell differentiation. The impairment of silenced HaCaT cell growth was accompanied by sharp increases in the mitochondrial membrane potential, which sensitized the cells to oxidative stress. We found that transcription of the subunits II and IV of cytochrome c oxidase was significantly increased upon VDR silencing. Accordingly, treatment of HaCaT cells with vitamin D downregulated both subunits, suggesting that VDR may inhibit the respiratory chain and redirect TCA intermediates toward biosynthesis, thus contributing to the metabolic switch that is typical of cancer cells. In order to explore this hypothesis, we examined various acetyl-CoA-dependent biosynthetic pathways, such as the mevalonate pathway (measured as cholesterol biosynthesis and prenylation of small GTPases), and histone acetylation levels; all of these pathways were inhibited by VDR silencing. These data provide evidence of the role of VDR as a gatekeeper of mitochondrial respiratory chain activity and a facilitator of the diversion of acetyl-CoA from the energy-producing TCA cycle toward biosynthetic pathways that are essential for cellular proliferation.