Cholesterol promotes the migration and invasion of renal carcinoma cells by regulating the KLF5/miR-27a/FBXW7 pathway

Copy number amplification of FLAD1 promotes the progression of triple-negative breast cancer through lipid metabolism

Triple-negative breast cancer (TNBC) is known for frequent copy number alterations (CNAs) and metabolic reprogramming. However, the mechanism by which CNAs of metabolic genes drive distinct metabolic reprogramming and affect disease progression remains unclear. Through an integrated analysis of our TNBC multiomic dataset (n = 465) and subsequent experimental validation, we identify copy number amplification of the metabolic gene flavin-adenine dinucleotide synthetase 1 (FLAD1) as a crucial genetic event that drives TNBC progression. Mechanistically, FLAD1, but not its enzymatically inactive mutant, upregulates the enzymatic activity of FAD-dependent lysine-specific demethylase 1 (LSD1). LSD1 subsequently promotes the expression of sterol regulatory element-binding protein 1 (SREBP1) by demethylating dimethyl histone H3 lysine 9 (H3K9me2). The upregulation of SREBP1 enhances the expression of lipid biosynthesis genes, ultimately facilitating the progression of TNBC. Clinically, pharmacological inhibition of the FLAD1/LSD1/SREBP1 axis effectively suppresses FLAD1-induced tumor progression. Moreover, LSD1 inhibitor enhances the therapeutic effect of doxorubicin and sacituzumab govitecan (SG). In conclusion, our findings reveal the CNA-derived oncogenic signalling axis of FLAD1/LSD1/SREBP1 and present a promising treatment strategy for TNBC.

Glycerol Kinase Drives Hepatic de novo Lipogenesis and Triglyceride Synthesis in Nonalcoholic Fatty Liver by Activating SREBP-1c Transcription, Upregulating DGAT1/2 Expression, and Promoting Glycerol Metabolism

Glycerol kinase (GK) participates in triglyceride (TG) synthesis by catalyzing glycerol metabolism. Whether GK contributes to nonalcoholic fatty liver (NAFL) is unclear. The expression of hepatic Gk is found to be increased in diet-induced and genetic mouse models of NAFL and is positively associated with hepatic SREBP-1c expression and TG levels. Cholesterol and fatty acids stimulate GK expression in hepatocytes. In HFD-induced NAFL mice, knockdown of hepatic Gk decreases expression of SREBP-1c and its target lipogenic genes as well as DGAT1/2, increases serum glycerol levels, decreases serum TG levels, and attenuates hepatic TG accumulation. Overexpression of GK in hepatocytes in mice or in culture produces opposite results. Mechanistic studies reveal that GK stimulates SREBP-1c transcription directly by binding to its gene promoter and indirectly by binding to SREBP-1c protein, thereby increasing lipogenic gene expression and de novo lipogenesis. Studies with truncated GK and mutant GKs indicate that GK induces SREBP-1c transcription independently of its enzyme activity. GK contributes to lipid homeostasis under physiological conditions by catalyzing glycerol metabolism rather than by regulating SREBP-1c transcription. Collectively, these results demonstrate that increased hepatic GK promotes de novo lipogenesis and TG synthesis in NAFL by stimulating SREBP-1c transcription and DGAT1/2 expression and catalyzing glycerol metabolism.

Multifunctional Nanomaterials Mediate Cholesterol Depletion for Cancer Treatment

Cholesterol is an essential membrane component, and the metabolites from cholesterol play important biological functions to intricately support cancer progression and dampen immune responses. Preclinical and clinical studies have demonstrated the role of cholesterol metabolism regulation on inhibiting tumor growth, remodeling the immunosuppressive tumor microenvironment (TME), and enhancing anti-tumor immunity. In this minireview, we discuss complex cholesterol metabolism in tumors, its important role in cancer progression, and its influences on immune cells in the TME. We provide an overview of recent advances in cancer treatment through regulating cholesterol metabolism. We discuss the design of cholesterol-altering multifunctional nanomaterials to regulate oxidative stress, modulate immune checkpoints, manipulate mechanical stress responses, and alter cholesterol metabolic pathways. Additionally, we examine the interactions between cholesterol metabolism regulation and established cancer treatments with the aim of identifying efficient strategies to disrupt cholesterol metabolism and synergistic combination therapies for effective cancer treatment.

Niemann-Pick C1-like 1 as a Prognostic Marker in Renal Cell Carcinoma: A Retrospective Cohort Study

BACKGROUND

Renal cell carcinoma (RCC) is a highly aggressive malignancy accounting for the majority of kidney cancers. Despite recent advancements in therapeutic options, the prognosis for advanced-stage RCC remains poor. Niemann-Pick C1-Like 1 (NPC1L1) plays a crucial role in cholesterol absorption and has been implicated in cancer progression across various cancers. However, its expression patterns and prognostic significance in RCC remain unclear.

METHODS

In this study, NPC1L1 expression in normal and RCC tissues, including subtypes, was compared using TCGA, GEPIA2, and The Human Protein Atlas. Clinical correlations were assessed, and the impact of NPC1L1 on overall survival (OS) and progression-free survival (PFS) was evaluated. Gene effect scores were analyzed using the DepMap tool to determine the involvement of NPC1L1 in RCC progression.

RESULTS

NPC1L1 expression was significantly lower in RCC tissues compared to normal tissues, particularly in the clear cell RCC (ccRCC), papillary RCC (pRCC), and chromophobe RCC (chRCC) subtypes, but increased in advanced tumor stages. Higher NPC1L1 expression was associated with worse OS and PFS in RCC patients. Multivariable Cox regression confirmed NPC1L1 as an independent prognostic marker. Additionally, gene effect scores showed that NPC1L1 is essential for the survival of specific RCC cell lines.

CONCLUSIONS

This study determines NPC1L1 as an independent prognostic indicator in RCC, with higher expression associated with poor survival outcomes. These findings suggest that NPC1L1 could serve as a valuable marker for identifying high-risk RCC patients. Further research is required to investigate the molecular mechanisms underlying the role of NPC1L1 in RCC progression.

AGFG1 increases cholesterol biosynthesis by disrupting intracellular cholesterol homeostasis to promote PDAC progression

PURPOSE

Cholesterol metabolism reprograming has been acknowledged as a novel feature of cancers. Pancreatic ductal adenocarcinoma (PDAC) is a cancer with a high demand of cholesterol for rapid growth. The underlying mechanism of how cholesterol metabolism homestasis are disturbed in PDAC is explored.

EXPERIMENTAL DESIGN

The relevance between PDAC and cholesterol was confirmed in TCGA database. The expression and clinical association were discovered in TCGA and GEO datasets. Knockdown and overexpression of AGFG1 was adopted to perform function studies. RNA sequencing, cholesterol detection, transmission electron microscope, co-immunoprecipitation, and immunofluorescence et al. were utilized to reveal the underlying mechanism.

RESULTS

AGFG1 was identified as one gene positively correlated with cholesterol metabolism in PDAC as revealed by bioinformatics analysis. AGFG1 expression was then found associated with poor prognosis in PDAC. AGFG1 knockdown led to decreased proliferation of tumor cells both in vitro and in vivo. By RNA sequencing, we found AGFG1 upregulated expression leads to enhanced intracellular cholesterol biosynthesis. AGFG1 knockdown suppressed cholesterol biosynthesis and an accumulation of cholesterol in the ER. Mechanistically, we confirmed that AGFG1 interacted with CAV1 to relocate cholesterol for the proceeding of cholesterol biosynthesis, therefore causing disorders in intracellular cholesterol metabolism.

CONCLUSIONS

Our study demonstrates the tumor-promoting role of AGFG1 by disturbing cholesterol metabolism homestasis in PDAC. Our study has present a new perspective on cancer therapeutic approach based on cholerstrol metabolism in PDAC.

Metabolic features of tumor-derived extracellular vesicles: challenges and opportunities

Tumor-derived extracellular vesicles (TDEVs) play crucial roles in intercellular communication both in the local tumor microenvironment and systemically, facilitating tumor progression and metastatic spread. They carry a variety of molecules with bioactive properties, such as nucleic acids, proteins and metabolites, that trigger different signaling processes in receptor cells and induce, among other downstream effects, metabolic reprogramming. Interestingly, the cargo of TDEVs also reflects the metabolic status of the producing cells in a time- and context-dependent manner, providing information on the functionality and state of those cells. For these reasons, together with their ability to be detected in diverse biofluids, there is increasing interest in the study of TDEVs, particularly their metabolic cargo, as diagnostic and prognostic tools in cancer management. This review presents a compilation of metabolism-related molecules (enzymes and metabolites) described in cancer extracellular vesicles (EVs) with potential use as cancer biomarkers, and discusses the challenges arising in this rapidly evolving field.

Cholesterol Metabolism and Urinary System Tumors

Cancers of the urinary system account for 13.1% of new cancer cases and 7.9% of cancer-related deaths. Of them, renal cancer, bladder cancer, and prostate cancer are most prevalent and pose a substantial threat to human health and the quality of life. Prostate cancer is the most common malignant tumor in the male urinary system. It is the second most common type of malignant tumor in men, with lung cancer surpassing its incidence and mortality. Bladder cancer has one of the highest incidences and is sex-related, with men reporting a significantly higher incidence than women. Tumor development in the urinary system is associated with factors, such as smoking, obesity, high blood pressure, diet, occupational exposure, and genetics. The treatment strategies primarily involve surgery, radiation therapy, and chemotherapy. Cholesterol metabolism is a crucial physiological process associated with developing and progressing urinary system tumors. High cholesterol levels are closely associated with tumor occurrence, invasion, and metastasis. This warrants thoroughly investigating the role of cholesterol metabolism in urinary system tumors and identifying novel treatment methods for the prevention, early diagnosis, targeted treatment, and drug resistance of urinary system tumors.

Tanshinone IIA acts as a regulator of lipogenesis to overcome osimertinib acquired resistance in lung cancer

Osimertinib is a novel epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), acting as the first-line medicine for advanced EGFR-mutated NSCLC. Recently, the acquired resistance to osimertinib brings great challenges to the advanced treatment. Therefore, it is in urgent need to find effective strategy to overcome osimertinib acquired resistance. Here, we demonstrated that SREBP pathway-driven lipogenesis was a key mediator to promote osimertinib acquired resistance, and firstly found Tanshinone IIA (Tan IIA), a natural pharmacologically active constituent isolated from Salvia miltiorrhiza, could overcome osimertinib-acquired resistance in vitro and in vivo via inhibiting SREBP pathway-mediated lipid lipogenesis by using LC-MS based cellular lipidomics analysis, quantitative real-time PCR (qRT-PCR) analysis, western blotting analysis, flow cytometry, small interfering RNAs transfection, and membrane fluidity assay et al. The results showed that SREBP1/2-driven lipogenesis was highly activated in osimertinib acquired resistant NSCLC cells, while knockdown or inhibition of SREBP1/2 could restore the sensitivity of NSCLC to osimertinib via altered the proportion of saturated phospholipids and unsaturated phospholipids in osimertinib acquired-resistant cells. Furthermore, Tanshinone IIA (Tan IIA) could reverse the acquired resistance to osimertinib in lung cancer. Mechanically, Tan IIA inhibited SREBP signaling mediated lipogenesis, changed the profiles of saturated phospholipids and unsaturated phospholipids, and thus promoted osimertinib acquired resistant cancer cells to be attacked by oxidative stress-induced damage and reduce the cell membrane fluidity. The reversal effect of Tan IIA on osimertinib acquired resistant NSCLC cells was also confirmed in vivo, which is helpful for the development of strategies to reverse osimertinib acquired resistance.

DHCR7 promotes lymph node metastasis in cervical cancer through cholesterol reprogramming-mediated activation of the KANK4/PI3K/AKT axis and VEGF-C secretion

Cervical cancer (CC) patients with lymph node metastasis (LNM) have a poor prognosis. However, the molecular mechanism of LNM in CC is unclear, and there is no effective clinical treatment. Here, we found that 7-dehydrocholesterol reductase (DHCR7), an enzyme that catalyzes the last step of cholesterol synthesis, was upregulated in CC and closely related to LNM. Gain-of-function and loss-of-function experiments proved that DHCR7 promoted the invasion ability of CC cells and lymphangiogenesis in vitro and induced LNM in vivo. The LNM-promoting effect of DHCR7 was partly mediated by upregulating KN motif and ankyrin repeat domains 4 (KANK4) expression and subsequently activating the PI3K/AKT signaling pathway. Alternatively, DHCR7 promoted the secretion of vascular endothelial growth factor-C (VEGF-C), and thereby lymphangiogenesis. Interestingly, cholesterol reprogramming was needed for the DHCR7-mediated promotion of activation of the KANK4/PI3K/AKT axis, VEGF-C secretion, and subsequent LNM. Importantly, treatment with the DHCR7 inhibitors AY9944 and tamoxifen (TAM) significantly inhibited LNM of CC, suggesting the clinical application potential of DHCR7 inhibitors in CC. Collectively, our results uncover a novel molecular mechanism of LNM in CC and identify DHCR7 as a new potential therapeutic target.

Blood Lipid Metabolic Profiles and Causal Links to Site-Specific Cancer Risks: A Mendelian Randomization Study

Observational and Mendelian randomization (MR) studies have established links between dyslipidemia and select cancer susceptibilities. However, there is a lack of comprehensive exploration of causal relationships spanning diverse cancer types. Here, we conducted a two-sample MR analysis to elucidate the causative connections between 9 blood lipid metabolic profiles (namely, adiponectin, leptin, lipoprotein A, apolipoprotein A1, apolipoprotein B, cholesterol, triglycerides, LDL-cholesterol, and HDL-cholesterol) and 21 site-specific cancer risks. Our findings reveal genetically predicted adiponectin levels to be associated with a reduced ovarian cancer risk, while genetically determined leptin increases bladder cancer risk but decreases prostate cancer risk. Lipoprotein A elevates risk of prostate cancer while diminishing risk of endometrial cancer, while apolipoprotein A1 heightens risks of breast and cervical cancers. Furthermore, elevated levels of cholesterol are positively correlated with kidney cancer, and triglycerides demonstrate a positive association with non-melanoma skin cancer but a negative association with breast cancer. Protective effects of genetically predicted LDL-cholesterol on endometrial cancer and adverse effects of HDL-cholesterol on breast cancer are also observed. Our study conclusively establishes that blood lipid metabolic profiles exert causal effects on cancer susceptibility, providing more robust evidence for cancer prevention and prompting contemplation regarding the future health of the human populace.

Extracellular vesicles as mediators of cell-cell communication in ovarian cancer and beyond - A lipids focus

Extracellular vesicles (EVs) are messengers that carry information in the form of proteins, lipids, and nucleic acids and are not only essential for intercellular communication but also play a critical role in the progression of various pathologies, including ovarian cancer. There has been recent substantial research characterising EV cargo, specifically, the lipid profile of EVs. Lipids are involved in formation and cargo sorting of EVs, their release and cellular uptake. Numerous lipidomic studies demonstrated the enrichment of specific classes of lipids in EVs derived from cancer cells suggesting that the EV associated lipids can potentially be employed as minimally invasive biomarkers for early diagnosis of various malignancies, including ovarian cancer. In this review, we aim to provide a general overview of the heterogeneity of EV, biogenesis, their lipid content, and function in cancer progression focussing on ovarian cancer.

Comprehensive analysis of the clinical and biological significances of cholesterol metabolism in lower-grade gliomas

BACKGROUND

As a component of membrane lipids and the precursor of oxysterols and steroid hormones, reprogrammed cholesterol metabolism contributes to the initiation and progression of multiple cancers. Thus, we aim to further investigate the significances of cholesterol metabolism in lower-grade gliomas (LGGs).

METHODS

The present study included 413 LGG samples from TCGA RNA-seq dataset (training cohort) and 172 LGG samples from CGGA RNA-seq dataset (validation cohort). The cholesterol metabolism-related signature was identified by the LASSO regression model. Bioinformatics analyses were performed to explore the functional roles of this signature in LGGs. Kaplan-Meier and Cox regression analyses were enrolled to estimate prognostic value of the risk signature.

RESULTS

Our findings suggested that cholesterol metabolism was tightly associated clinicopathologic features and genomic alterations of LGGs. Bioinformatics analyses revealed that cholesterol metabolism played a key role in immunosuppression of LGGs, mainly by promoting macrophages polarization and T cell exhaustion. Kaplan-Meier curve and Cox regression analysis showed that cholesterol metabolism was an independent prognostic indicator for LGG patients. To improve the clinical application value of the risk signature, we also constructed a nomogram model to predict the 1-, 3- and 5-year survival of LGG patients.

CONCLUSION

The cholesterol metabolism was powerful prognostic indicator and could serve as a promising target to enhance personalized treatment of LGGs.

The biological function of tumor-derived extracellular vesicles on metabolism

Multiple studies have shown that extracellular vesicles (EVs) play a key role in the process of information transfer and material transport between cells. EVs are classified into different types according to their sizes, which includes the class of exosomes. In comparison to normal EVs, tumor-derived EVs (TDEs) have both altered components and quantities of contents. TDEs have been shown to help facilitate an environment conducive to the occurrence and development of tumor by regulation of glucose, lipids and amino acids. Furthermore, TDEs can also affect the host metabolism and immune system. EVs have been shown to have multiple clinically useful properties, including the use of TDEs as biomarkers for the early diagnosis of diseases and using the transport properties of exosomes for drug delivery. Targeting the key bioactive cargoes of exosomes could be applied to provide new strategies for the treatment of tumors. In this review, we summarize the finding of studies focused on measuring the effects of TDE on tumor-related microenvironment and systemic metabolism. Video Abstract.

An elevated preoperative cholesterol-to-lymphocyte ratio predicts unfavourable outcomes in colorectal cancer liver metastasis patients receiving simultaneous resections: a retrospective study

BACKGROUND

To explore the clinical prognostic utility of the preoperative cholesterol-to-lymphocyte ratio (CLR) in outcomes for colorectal cancer liver metastasis (CRLM) patients receiving simultaneous resection of the primary lesion and liver metastases.

METHODS

A total of 444 CRLM patients receiving simultaneous resections were enrolled. The optimal cut-off value for CLR was determined using the highest Youden's index. Patients were divided into the CLR < 3.06 group and the CLR≥3.06 group. Propensity score matching analysis (PSM) and the inverse probability of treatment weighting (IPTW) method were conducted to eliminate bias between the two groups. The outcomes included short-term outcomes and long-term outcomes. Kaplan-Meier curves and log-rank tests were used to analyse progression-free survival (PFS) and overall survival (OS).

RESULTS

In the short-term outcome analysis, after 1:1 PSM, 137 patients were distributed to the CLR < 3.06 group and CLR≥3.06 group. No significant difference was noted between the two groups (P > 0.1). Compared with patients with CLR < 3.06, patients with CLR≥3.06 had comparable operation times (320.0 [272.5-421.0] vs. 360.0 [292.5-434.5], P = 0.088), blood loss (200.0 [100.0-400.0] vs. 200.0 [150.0-450.0], P = 0.831), postoperative complication rates (50.4% vs. 46.7%, P = 0.546) and postoperative ICU rates (5.8% vs. 11.7%, P = 0.087). In the long-term outcome analysis, Kaplan-Meier analysis showed that compared with patients with CLR < 3.06, patients with CLR≥3.06 had worse PFS (P = 0.005, median: 10.2 months vs. 13.0 months) and OS (P = 0.002, median: 41.0 months vs. 70.9 months). IPTW-adjusted Kaplan-Meier analysis showed that the CLR≥3.06 group had worse PFS (P = 0.027) and OS (P = 0.010) than the CLR < 3.06 group. In the IPTW-adjusted Cox proportional hazards regression analysis, CLR≥3.06 was an independent factor for PFS (HR = 1.376, 95% CI 1.097-1.726, P = 0.006) and OS (HR = 1.723, 95% CI 1.218-2.439, P = 0.002). IPTW-adjusted Cox proportional hazards regression analysis including postoperative complications, operation time, intraoperative blood loss, intraoperative blood transfusion and postoperative chemotherapy revealed that CLR≥3.06 was an independent factor for PFS (HR = 1.617, 95% CI 1.252-2.090, P < 0.001) and OS (HR = 1.823, 95% CI 1.258-2.643, P = 0.002).

CONCLUSIONS

The preoperative CLR level predicts unfavourable outcomes in CRLM patients receiving simultaneous resection of the primary lesion and liver metastases and should be taken into consideration when developing treatment and monitoring strategies.

Myeloid-derived suppressor cells deficient in cholesterol biosynthesis promote tumor immune evasion

Cancer immunotherapy targeting myeloid-derived suppressor cells (MDSCs) is one of the most promising anticancer strategies. Metabolic reprogramming is vital for MDSC activation, however, the regulatory mechanisms of cholesterol metabolic reprogramming in MDSCs remains largely unexplored. Using the receptor-interacting protein kinase 3 (RIPK3)-deficient MDSC model, a previously established tumor-infiltrating MDSC-like model, we found that the cholesterol accumulation was significantly decreased in these cells. Moreover, the phosphorylated AKT-mTORC1 signaling was reduced, and downstream SREBP2-HMGCR-mediated cholesterol synthesis was blunted. Interestingly, cholesterol deficiency profoundly elevated the immunosuppressive activity of MDSCs. Mechanistically, cholesterol elimination induced nuclear accumulation of LXRβ, thereby promoting LXRβ-RXRα heterodimer binding of a novel composite element in the promoter of Arg1. Furthermore, itraconazole enhanced the immunosuppressive activity of MDSCs to boost tumor growth by suppressing the RIPK3-AKT-mTORC1 pathway and impeding cholesterol synthesis. Our findings demonstrate that RIPK3 deficiency leads to cholesterol abrogation in MDSCs, which facilitates tumor-infiltrating MDSC activation, and highlight the therapeutic potential of targeting cholesterol synthesis to overcome tumor immune evasion.

Lipophagy-mediated cholesterol synthesis inhibition is required for the survival of hepatocellular carcinoma under glutamine deprivation

Glutamine is critical for tumor progression, and restriction of its availability is emerging as a potential therapeutic strategy. The metabolic plasticity of tumor cells helps them adapting to glutamine restriction. However, the role of cholesterol metabolism in this process is relatively unexplored. Here, we reported that glutamine deprivation inhibited cholesterol synthesis in hepatocellular carcinoma (HCC). Reactivation of cholesterol synthesis enhanced glutamine-deprivation-induced cell death of HCC cells, which is partially duo to augmented NADPH depletion and lipid peroxidation. Mechanistically, glutamine deprivation induced lipophagy to transport cholesterol from lipid droplets (LDs) to endoplasmic reticulum (ER), leading to inhibit SREBF2 maturation and cholesterol synthesis, and maintain redox balance for survival. Glutamine deprivation decreased mTORC1 activity to induce lipophagy. Importantly, administration of U18666A, CQ, or shTSC2 viruses further augmented GPNA-induced inhibition of xenograft tumor growth. Clinical data supported that glutamine utilization positively correlated with cholesterol synthesis, which is associated with poor prognosis of HCC patients. Collectively, our study revealed that cholesterol synthesis inhibition is required for the survival of HCC under glutamine-restricted tumor microenvironment.

Deregulated expression of the 14q32 miRNA cluster in clear cell renal cancer cells

Clear cell renal cell carcinomas (ccRCC) are characterized by arm-wide chromosomal alterations. Loss at 14q is associated with disease aggressiveness in ccRCC, which responds poorly to chemotherapeutics. The 14q locus contains one of the largest miRNA clusters in the human genome; however, little is known about the contribution of these miRNAs to ccRCC pathogenesis. In this regard, we investigated the expression pattern of selected miRNAs at the 14q32 locus in TCGA kidney tumors and in ccRCC cell lines. We demonstrated that the miRNA cluster is downregulated in ccRCC (and cell lines) as well as in papillary kidney tumors relative to normal kidney tissues (and primary renal proximal tubule epithelial (RPTEC) cells). We demonstrated that agents modulating expression of DNMT1 (e.g., 5-Aza-deoxycytidine) could modulate 14q32 miRNA expression in ccRCC cell lines. Lysophosphatidic acid (LPA, a lysophospholipid mediator elevated in ccRCC) not only increased labile iron content but also modulated expression of a 14q32 miRNA. Through an overexpression approach targeting a subset of 14q32 miRNAs (specifically at subcluster A: miR-431-5p, miR-432-5p, miR-127-3p, and miR-433-3p) in 769-P cells, we uncovered changes in cellular viability and claudin-1, a tight junction marker. A global proteomic approach was implemented using these miRNA overexpressing cell lines which uncovered ATXN2 as a highly downregulated target. Collectively, these findings support a contribution of miRNAs at 14q32 in ccRCC pathogenesis.

Krüppel-like Factor 13 Promotes HCC Progression by Transcriptional Regulation of HMGCS1-mediated Cholesterol Synthesis

BACKGROUND AND AIMS

Krüppel-like factor (KLF) has a role in the occurrence, development and metabolism of cancer. We aimed to explore the role and potential molecular mechanism of KLF13 in the growth and migration of liver cancer cells.

METHODS

The expression of KLF13 in hepatocellular carcinoma (HCC) tissues was higher than that in normal tissues according to analysis of The Cancer Genome Atlas (TCGA) database. Lentiviral plasmids were used for overexpression and plasmid knockdown of KLF13. Real-time quantitative polymerase chain reaction (qPCR) and western blotting were used to detect mRNA and protein expression in HCC tissues and cells. Cell counting kit-8 (CCK-8), colony formation, cell migration and invasion, and flow cytometry assays were used to assess the in vitro function of KLF13 in HCC cells. The effect of KLF13 on xenograft tumor growth in vivo was evaluated. The cholesterol content of HCC cells was determined by an indicator kit. A dual-luciferase reporter assay and chromatin immunoprecipitation sequencing (ChIP-seq) revealed the binding relationship between KLF13 and HMGCS1.

RESULTS

The expression of KLF13 was upregulated in HCC tissues and TCGA database. KLF13 knockdown inhibited the proliferation, migration and invasion of HepG2 and Huh7 cells and increased the apoptosis of Huh7 cells. The opposite effects were observed with the overexpression of KLF13 in SK-Hep1 and MHCC-97H cells. The overexpression of KLF13 promoted the growth of HCC in nude mice and KLF13 transcription promoted the expression of HMGCS1 and the biosynthesis of cholesterol. KLF13 knockdown inhibited cholesterol biosynthesis mediated by HMGCS1 and inhibited the growth and metastasis of HCC cells.

CONCLUSIONS

KLF13 acted as a tumor promoter in HCC by positively regulating HMGCS1-mediated cholesterol biosynthesis.

Alteration of cholesterol distribution at the plasma membrane of cancer cells: From evidence to pathophysiological implication and promising therapy strategy

Cholesterol-enriched domains are nowadays proposed to contribute to cancer cell proliferation, survival, death and invasion, with important implications in tumor progression. They could therefore represent promising targets for new anticancer treatment. However, although diverse strategies have been developed over the years from directly targeting cholesterol membrane content/distribution to adjusting sterol intake, all approaches present more or less substantial limitations. Those data emphasize the need to optimize current strategies, to develop new specific cholesterol-targeting anticancer drugs and/or to combine them with additional strategies targeting other lipids than cholesterol. Those objectives can only be achieved if we first decipher (i) the mechanisms that govern the formation and deformation of the different types of cholesterol-enriched domains and their interplay in healthy cells; (ii) the mechanisms behind domain deregulation in cancer; (iii) the potential generalization of observations in different types of cancer; and (iv) the specificity of some alterations in cancer vs. non-cancer cells as promising strategy for anticancer therapy. In this review, we will discuss the current knowledge on the homeostasis, roles and membrane distribution of cholesterol in non-tumorigenic cells. We will then integrate documented alterations of cholesterol distribution in domains at the surface of cancer cells and the mechanisms behind their contribution in cancer processes. We shall finally provide an overview on the potential strategies developed to target those cholesterol-enriched domains in cancer therapy.

The tumor-repressing effect of CYP27A1 on renal cell carcinoma by 27-HC arising from cholesterol metabolism

As a key approach to mediate cholesterol metabolism, the role of the CYP27A1/27-HC axis in renal cell carcinoma (RCC) remains unclear. Analysis of CYP27A1 expression from public databases and metastatic cases in our center suggested that CYP27A1 was obviously downregulated in RCC tissues, and survival analysis further showed its correlation with favorable clinicopathological features and prognosis. In vitro, up and downregulation of CYP27A1 expression in RCC cell lines could definitely illustrate its anticipation involving apoptosis, proliferation, invasion, migration, and clonality. This could be achieved through upregulation of 27-HC concentration, which mediates the activation of signaling pathways of apoptosis and cell cycle arrest. Further, recovery of CYP27A1 expression could definitely inhibit the proliferation of RCC tumors in vivo. This is the first study to explore the role of the CYP27A1/27-HC axis in RCC. Attempts to maintain the normal function of the axis may be a potential strategy in the treatment of RCC, and the predictive value of CYP27A1 detection on the efficacy of targeted therapy in metastatic RCC is also worthy of attention.

A novel cuproptosis-related lncRNA nomogram to improve the prognosis prediction of gastric cancer

Background

Cuproptosis is a copper-triggered modality of mitochondrial cell death and cuproptosis process may play important roles in gastric cancer development. However, little is known about cuproptosis-related lncRNAs in gastric adenocarcinoma (STAD). This study is aimed to investigate the potential prognostic signatures of cuproptosis-related lncRNAs in STAD.

Methods

The Cancer Genome Atlas (TCGA) database were used to obtain gene expression profiles, clinicopathological, and OS information for STAD. Cuproptosis-related genes were collected based on previous studies and cuproptosis-related lncRNAs were screened out by co-expression analysis. The nomogram constructed by Cox regression analysis with the minimum absolute contraction and selection operator (lasso) algorithm. In addition, the potential response of ICB therapy and immune evasion incidence were estimated with Tumor Immune Dysfunction and Exclusion (TIDE) algorithm. Immune checkpoint expressions associated with risk scores were also analyzed. The correlation of immune checkpoint CD209 and HAVCR2 expressions associated with risk scores were experimentally testified by RT-qPCR, Western Blot, and IHC.

Results

Patients were classified into high-risk and low-risk groups based on the risk score calculated in this model. The Kaplan–Meier survival curve analysis revealed that the high-risk group was associated with poor prognosis. Multivariate Cox regression analysis suggested that this lncRNA prediction model was an independent risk factor affecting the OS rate. Furthermore, ROC curve indicates that the nomogram was superior to traditional clinicopathological features in predicting STAD prognosis. Finally, functional enrichment analysis and immune checkpoint investigation revealed that the nomogram is notably associated with cholesterol metabolism and immune functions, RT-qPCR and Western Blotting demonstrated the co-expression relationship of LINC01150 with CD209 and HAVCR2.

Conclusion

A novel cuproptosis-related lncRNAs signature impacts on the prognosis and immunological features of GC.

Mutant p53, the Mevalonate Pathway and the Tumor Microenvironment Regulate Tumor Response to Statin Therapy

Tumor cells have the ability to co-opt multiple metabolic pathways, enhance glucose uptake and utilize aerobic glycolysis to promote tumorigenesis, which are characteristics constituting an emerging hallmark of cancer. Mutated tumor suppressor and proto-oncogenes are frequently responsible for enhanced metabolic pathway signaling. The link between mutant p53 and the mevalonate (MVA) pathway has been implicated in the advancement of various malignancies, with tumor cells relying heavily on increased MVA signaling to fuel their rapid growth, metastatic spread and development of therapy resistance. Statin drugs inhibit HMG-CoA reductase, the pathway’s rate-limiting enzyme, and as such, have long been studied as a potential anti-cancer therapy. However, whether statins provide additional anti-cancer properties is worthy of debate. Here, we examine retrospective, prospective and pre-clinical studies involving the use of statins in various cancer types, as well as potential issues with statins’ lack of efficacy observed in clinical trials and future considerations for upcoming clinical trials.

Surface cholesterol-enriched domains specifically promote invasion of breast cancer cell lines by controlling invadopodia and extracellular matrix degradation

Tumor cells exhibit altered cholesterol content. However, cholesterol structural subcellular distribution and implication in cancer cell invasion are poorly understood mainly due to difficulties to investigate cholesterol both quantitatively and qualitatively and to compare isogenic cell models. Here, using the MCF10A cell line series (non-tumorigenic MCF10A, pre-malignant MCF10AT and malignant MCF10CAIa cells) as a model of breast cancer progression and the highly invasive MDA-MB-231 cell line which exhibits the common TP53 mutation, we investigated if cholesterol contributes to cancer cell invasion, whether the effects are specific to cancer cells and the underlying mechanism. We found that partial membrane cholesterol depletion specifically and reversibly decreased invasion of the malignant cell lines. Those cells exhibited dorsal surface cholesterol-enriched submicrometric domains and narrow ER-plasma membrane and ER-intracellular organelles contact sites. Dorsal cholesterol-enriched domains can be endocytosed and reach the cell ventral face where they were involved in invadopodia formation and extracellular matrix degradation. In contrast, non-malignant cells showed low cell invasion, low surface cholesterol exposure and cholesterol-dependent focal adhesions. The differential cholesterol distribution and role in breast cancer cell invasion provide new clues for the understanding of the molecular events underlying cellular mechanisms in breast cancer.

Recent Insight on Regulations of FBXW7 and Its Role in Immunotherapy

SCF^FBXW7 E3 ubiquitin ligase complex is a crucial enzyme of the ubiquitin proteasome system that participates in variant activities of cell process, and its component FBXW7 (F-box and WD repeat domain–containing 7) is responsible for recognizing and binding to substrates. The expression of FBXW7 is controlled by multiple pathways at different levels. FBXW7 facilitates the maturity and function maintenance of immune cells via functioning as a mediator of ubiquitination-dependent degradation of substrate proteins. FBXW7 deficiency or mutation results in the growth disturbance and dysfunction of immune cell, leads to the resistance against immunotherapy, and participates in multiple illnesses. It is likely that FBXW7 coordinating with its regulators and substrates could offer potential targets to improve the sensitivity and effects of immunotherapy. Here, we review the mechanisms of the regulation on FBXW7 and its tumor suppression role in immune filed among various diseases (mostly cancers) to explore novel immune targets and treatments.

Copy number amplification of ENSA promotes the progression of triple-negative breast cancer via cholesterol biosynthesis

Copy number alterations (CNAs) are pivotal genetic events in triple-negative breast cancer (TNBC). Here, our integrated copy number and transcriptome analysis of 302 TNBC patients reveals that gene alpha-endosulfine (ENSA) exhibits recurrent amplification at the 1q21.3 region and is highly expressed in TNBC. ENSA promotes tumor growth and indicates poor patient survival in TNBC. Mechanistically, we identify ENSA as an essential regulator of cholesterol biosynthesis in TNBC that upregulates the expression of sterol regulatory element-binding transcription factor 2 (SREBP2), a pivotal transcription factor in cholesterol biosynthesis. We confirm that ENSA can increase the level of p-STAT3 (Tyr705) and activated STAT3 binds to the promoter of SREBP2 to promote its transcription. Furthermore, we reveal the efficacy of STAT3 inhibitor Stattic in TNBC with high ENSA expression. In conclusion, the amplification of ENSA at the 1q21.3 region promotes TNBC progression and indicates sensitivity to STAT3 inhibitors.

Copy number alterations are pivotal genetic events in triple-negative breast cancer. Here the authors show the amplification of ENSA at the 1q21.3 region promotes the progression of TNBC via up-regulation of cholesterol biosynthesis.

Krüppel-like factor (KLF)5: An emerging foe of cardiovascular health

Krüppel-like factors (KLFs) are DNA-binding transcriptional factors, which regulate various pathways that pertain to development, metabolism and other cellular mechanisms. KLF5 was first cloned in 1993 and by 1999, it was reported as the intestinal-enriched KLF. Beyond findings that have associated KLF5 with normal development and cancer, it has been associated with various types of cardiovascular (CV) complications and regulation of metabolic pathways in the liver, heart, adipose tissue and skeletal muscle. Specifically, increased KLF5 expression has been linked with cardiomyopathy in diabetes, end-stage heart failure, and as well as in vascular atherosclerotic lesions. In this review article, we summarize research findings about transcriptional, post-transcriptional and post-translational regulation of KLF5, as well as the role of KLF5 in the biology of cells and organs that affect cardiovascular health either directly or indirectly. Finally, we propose KLF5 inhibition as an emerging approach for cardiovascular therapeutics.

Blood cholesterol-to-lymphocyte ratio as a novel prognostic marker to predict postoperative overall survival in patients with colorectal cancer

Background

Lipid disequilibrium and systemic inflammation are reported to correlate with tumorigenesis and development of colorectal cancer (CRC). We construct the novel biomarker cholesterol-to-lymphocyte ratio (CLR) to reflect the synergistic effect of cholesterol metabolism and inflammation on CRC outcomes. This study aims to investigate the clinical significance of CLR and establish a prognostic model for CRC.

Methods

Our study retrospectively enrolled 223 CRC patients who underwent curative surgical resection. The Kaplan-Meier method was employed to estimate the overall survival (OS) rates, and the association between serological biomarkers and survival was assessed with a log-rank test. Cox proportional hazard regression was applied in the univariate and multivariate analyses to identify independent prognostic factors, which were then used to develop a predictive nomogram model for OS in CRC. The nomogram was evaluated by the C-index, receiver operator characteristic curve (ROC) analysis, and calibration plot. All cases were grouped into three stratifications according to the total risk points calculated from the nomogram, and the difference in OS between them was assessed with the Kaplan-Meier method.

Results

At the end of the study, death occurred in 47 (21%) cases. Patients with low CLR (< 3.23) had significantly prolonged survival (P < 0.001). Multivariate analyses revealed that N stage (P < 0.001), harvested lymph nodes (P = 0.021), and CLR (P = 0.005) were independent prognostic factors for OS and a prognostic nomogram was established based on these variables. The nomogram showed good calibration and predictive performance with a superior C-index than TNM stage (0.755 (0.719–0.791) vs. 0.663 (0.629–0.697), P = 0.001). Patients of different risk stratifications based on the total score of nomogram showed distinct survival (P < 0.001).

Conclusions

The nomogram based on CLR and other clinical features can be used as a potentially convenient and reliable tool in predicting survival in patients with CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02471-4.

Therapeutic Potential of Thymoquinone in Triple-Negative Breast Cancer Prevention and Progression through the Modulation of the Tumor Microenvironment

To date, the tumor microenvironment (TME) has gained considerable attention in various areas of cancer research due to its role in driving a loss of immune surveillance and enabling rapid advanced tumor development and progression. The TME plays an integral role in driving advanced aggressive breast cancers, including triple-negative breast cancer (TNBC), a pivotal mediator for tumor cells to communicate with the surrounding cells via lymphatic and circulatory systems. Furthermore, the TME plays a significant role in all steps and stages of carcinogenesis by promoting and stimulating uncontrolled cell proliferation and protecting tumor cells from the immune system. Various cellular components of the TME work together to drive cancer processes, some of which include tumor-associated adipocytes, fibroblasts, macrophages, and neutrophils which sustain perpetual amplification and release of pro-inflammatory molecules such as cytokines. Thymoquinone (TQ), a natural chemical component from black cumin seed, is widely used traditionally and now in clinical trials for the treatment/prevention of multiple types of cancer, showing a potential to mitigate components of TME at various stages by various pathways. In this review, we focus on the role of TME in TNBC cancer progression and the effect of TQ on the TME, emphasizing their anticipated role in the prevention and treatment of TNBC. It was concluded from this review that the multiple components of the TME serve as a critical part of TNBC tumor promotion and stimulation of uncontrolled cell proliferation. Meanwhile, TQ could be a crucial compound in the prevention and progression of TNBC therapy through the modulation of the TME.

Exosomes: Small vesicles with big roles in cancer, vaccine development, and therapeutics

Cancer is a deadly disease that is globally and consistently one of the leading causes of mortality every year. Despite the availability of chemotherapy, radiotherapy, immunotherapy, and surgery, a cure for cancer has not been attained. Recently, exosomes have gained significant attention due to the therapeutic potential of their various components including proteins, lipids, nucleic acids, miRNAs, and lncRNAs. Exosomes constitute a set of tiny extracellular vesicles with an approximate diameter of 30-100 nm. They are released from different cells and are present in biofluids including blood, cerebrospinal fluid (CSF), and urine. They perform crucial multifaceted functions in the malignant progression of cancer via autocrine, paracrine, and endocrine communications. The ability of exosomes to carry different cargoes including drug and molecular information to recipient cells make them a novel tool for cancer therapeutics. In this review, we discuss the major components of exosomes and their role in cancer progression. We also review important literature about the potential role of exosomes as vaccines and delivery carriers in the context of cancer therapeutics.

Cholesterol-Lowering Drugs on Akt Signaling for Prevention of Tumorigenesis

Cholesterol has been reported to be accumulated in cancer cells. The metabolic dysregulation of the cholesterol is associated with tumor development and progression. The cholesterol-lowering drugs have been found to be involved in the prevention and treatment of various cancers. Akt, a serine/threonine kinase, can modulate the role of several downstream proteins involved in cell proliferation, migration, invasion, metabolism, and apoptosis. Since its involvement in several signaling pathways, its dysregulation is commonly reported in several cancers. Thus, targeting Akt could be an effective approach for cancer prevention and therapy. Cholesterol-lowering drugs have been found to affect the expression of Akt, and its activation in the cancer cells and thus have shown anticancer activity in different type of cancers. These drugs act on various signaling pathways such as PTEN/Akt, PI3k/Akt, Akt/NF-κB, Akt/FOXO1, Akt/mTOR, etc., which will be discussed in this article. This review article will discuss the significance of cholesterol in cancer cells, cholesterol-lowering drugs, the role of Akt in cancer cells, and the effects of cholesterol-lowering drugs on Akt in the prevention of therapy resistance and metastasis.

Implications of FBXW7 in Neurodevelopment and Neurodegeneration: Molecular Mechanisms and Therapeutic Potential

The ubiquitin-proteasome system (UPS) mediated protein degradation is crucial to maintain quantitive and functional homeostasis of diverse proteins. Balanced cellular protein homeostasis controlled by UPS is fundamental to normal neurological functions while impairment of UPS can also lead to some neurodevelopmental and neurodegenerative disorders. Functioning as the substrate recognition component of the SCF-type E3 ubiquitin ligase, FBXW7 is essential to multiple aspects of cellular processes via targeting a wide range of substrates for proteasome-mediated degradation. Accumulated evidence shows that FBXW7 is fundamental to neurological functions and especially implicated in neurodevelopment and the nosogenesis of neurodegeneration. In this review, we describe general features of FBXW7 gene and proteins, and mainly present recent findings that highlight the vital roles and molecular mechanisms of FBXW7 in neurodevelopment such as neurogenesis, myelination and cerebral vasculogenesis and in the pathogenesis of some typical neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease. Additionally, we also provide a prospect on focusing FBXW7 as a potential therapeutic target to rescue neurodevelopmental and neurodegenerative impairment.

Cholesterol Metabolic Reprogramming in Cancer and Its Pharmacological Modulation as Therapeutic Strategy

Cholesterol is a ubiquitous sterol with many biological functions, which are crucial for proper cellular signaling and physiology. Indeed, cholesterol is essential in maintaining membrane physical properties, while its metabolism is involved in bile acid production and steroid hormone biosynthesis. Additionally, isoprenoids metabolites of the mevalonate pathway support protein-prenylation and dolichol, ubiquinone and the heme a biosynthesis. Cancer cells rely on cholesterol to satisfy their increased nutrient demands and to support their uncontrolled growth, thus promoting tumor development and progression. Indeed, transformed cells reprogram cholesterol metabolism either by increasing its uptake and de novo biosynthesis, or deregulating the efflux. Alternatively, tumor can efficiently accumulate cholesterol into lipid droplets and deeply modify the activity of key cholesterol homeostasis regulators. In light of these considerations, altered pathways of cholesterol metabolism might represent intriguing pharmacological targets for the development of exploitable strategies in the context of cancer therapy. Thus, this work aims to discuss the emerging evidence of in vitro and in vivo studies, as well as clinical trials, on the role of cholesterol pathways in the treatment of cancer, starting from already available cholesterol-lowering drugs (statins or fibrates), and moving towards novel potential pharmacological inhibitors or selective target modulators.

Impact of cholesterol-pathways on breast cancer development, a metabolic landscape

ApoB-lipoproteins and their components modulate intracellular metabolism and have been associated with the development of neoplastic phenomena, such as proliferation, anchorage-independent growth, epithelial-mesenchymal transition, and cancer invasion. In cancer cells, the modulation of targets that regulate cholesterol metabolism, such as synthesis de novo, endocytosis, and oxidation, are contributing factors to cancer development. While mechanisms associated with sterol regulatory element-binding protein 2 (SREBP-2)/mevalonate, the low-density lipoprotein receptor (LDL-R) and liver X receptor (LXR) have been linked with tumor growth; metabolites derived from cholesterol-oxidation, such as oxysterols and epoxy-cholesterols, also have been described as tumor processes-inducers. From this notion, we perform an analysis of the role of lipoproteins, their association with intracellular cholesterol metabolism, and the impact of these conditions on breast cancer development, mechanisms that can be shared during atherogenesis promoted mainly by LDL. Pathways connecting plasma dyslipidemias in conjunction with the effect of cholesterol-derived metabolites on intracellular mechanisms and cellular plasticity phenomena could provide new approaches to elucidate the triggering factors of carcinogenesis, conditions that could be considered in the development of new therapeutic approaches.

Baseline Serum Cholesterol Levels Predict the Response of Patients with Advanced Non-Small Cell Lung Cancer to Immune Checkpoint Inhibitor-Based Treatment

Purpose

Although predictive markers of immune checkpoint inhibitor (ICI)-based treatments have been extensively studied, with the exception of programmed death ligand 1 (PD-L1), most are not widely used in the clinic due to poor effects or defective practicability. The aim of this study was to identify those patients with high baseline serum cholesterol who benefit from ICI-based treatments.

Patients and Methods

Patients with advanced non-small cell lung cancer (NSCLC) treated at Ningbo Medical Center, Li Huili Hospital between August 2017 and December 2019 were enrolled in this retrospective study. The Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1) were used to evaluate the efficacy of the ICI-based treatment. Progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan–Meier survival curves and compared using the log rank test. Univariate and multivariate analyses were conducted using the logistic regression analysis and Cox proportional hazards model. A receiver operating characteristic curve was created, and the area under the curve (AUC) was calculated to compare the predictive value of baseline serum cholesterol with PD-L1 expression for patient response to ICI-based treatment.

Results

In our cohort of 169 NSCLC patients, the objective response rate (ORR) and disease control rate (DCR) of the treatment were significantly higher in patients with hypercholesterolemia (>5.18 mmol/L) than in those with hypocholesterolemia (ORR: 33.67% vs 14.08%, P=0.004; DCR: 68.37% vs 42.25%, P=0.001). The median PFS was 7.9 months in the hypercholesterolemia group, significantly longer than in the hypocholesterolemia group (4.4 months, 95% CI: 4.620–7.380, P<0.001). The median OS in the two groups were 11 months and 8 months, with 95% CIs of 8.980–10.420 (P<0.001). The AUC for the baseline level of cholesterol was 0.706 (P<0.001), while it was 0.643 (P=0.001) for PD-L1 expression.

Conclusion

The baseline serum cholesterol level is predictive of a clinical benefit for advanced NSCLC patients who undergo ICI-based treatment, and hence it is a promising prognostic indicator for ICI-based treatment of NSCLC.

The roles and regulation of the KLF5 transcription factor in cancers

Krüppel‐like factor 5 (KLF5) is a member of the KLF family. Recent studies have suggested that KLF5 regulates the expression of a large number of new target genes and participates in diverse cellular functions, such as stemness, proliferation, apoptosis, autophagy, and migration. In response to multiple signaling pathways, various transcriptional modulation and posttranslational modifications affect the expression level and activity of KLF5. Several transgenic mouse models have revealed the physiological and pathological functions of KLF5 in different cancers. Studies of KLF5 will provide prognostic biomarkers, therapeutic targets, and potential drugs for cancers.

Roles of Krüppel-like factor 5 in kidney disease

Transcription factor Krüppel-like factor 5 (KLF5) is a member of the Krüppel-like factors' (KLFs) family. KLF5 regulates a number of cellular functions, such as apoptosis, proliferation and differentiation. Therefore, KLF5 can play a role in many diseases, including, cancer, cardiovascular disease and gastrointestinal disorders. An important role for KLF5 in the kidney was recently reported, such that KLF5 regulated podocyte apoptosis, renal cell proliferation, tubulointerstitial inflammation and renal fibrosis. In this review, we have summarized the available information in the literature with a brief description on how transcriptional, post-transcriptional and post-translational modifications of KLF5 modulate its function in a variety of organs including the kidney with a focus of its importance on the pathogenesis of various kidney diseases. Furthermore, we also have outlined the current and possible mechanisms of KLF5 activation in kidney diseases. These studies suggest a need for more systemic investigations, particularly for generation of animal models with renal cell-specific deletion or overexpression of KLF5 gene to examine direct contributions of KLF5 to various kidney diseases. This will promote further experimentation in the development of therapies to prevent or treat various kidney diseases.

MicroRNA‑223‑induced inhibition of the FBXW7 gene affects the proliferation and apoptosis of colorectal cancer cells via the Notch and Akt/mTOR pathways

The tumour suppressor gene F-box and WD repeat domain-containing 7 (FBXW7) plays an important role in human cancer by regulating cell division, proliferation and differentiation. However, the exact regulatory mechanisms of microRNA (miR)-223 in colorectal cancer (CRC) cells are still unknown. The present study aimed to investigate the effect and mechanism of miR-223 inhibiting FBXW7 on the proliferation and apoptosis of CRC cells. HCT116 cells were transfected with miR-223 mimics or small interfering RNA (siRNA) targeting FBXW7 (siFBXW7), and the effects of these treatments on cell proliferation and apoptosis were examined. The downstream Notch and Akt/mTOR pathways were also assessed. Following miR-223 overexpression, the mRNA and protein expression levels of FBXW7 were downregulated. Transfection with miR-223 mimics or siFBXW7 promoted the proliferation of HCT116 cells and inhibited apoptosis by promoting the Notch and Akt/mTOR signalling pathways. Conversely, miR-223 mimics transfection with FBXW7 overexpression inhibited cell viability and restored apoptosis. Thus, the present study demonstrated that miR-223 could bind to the FBXW7 gene and inhibit its expression, ultimately increasing the proliferation and preventing the apoptosis of CRC cells through the Notch and Akt/mTOR signalling pathways.

Apolipoprotein C1 (APOC1): A Novel Diagnostic and Prognostic Biomarker for Clear Cell Renal Cell Carcinoma

Background: Apolipoprotein C1 (APOC1) has been proved to play a critical role in gastric, breast, lung, and pancreatic cancer. However, the relationship between APOC1 and urinary tumors remains unclear. This study aimed to assess the diagnostic and prognostic value of APOC1 in urinary tumors.

Methods: We performed a pan analysis of APOC1 mRNA expression in urinary cancer using the Gene Expression Profiling Interactive Analysis (GEPIA) database. To further investigate the prognostic value of APOC1 expression in urinary cancers, the Kaplan-Meier plotter database was used. Furthermore, we collected the tumor and adjacent normal samples of 32 ccRCC patients to perform qRT-PCR and western blotting assays. A total of 72 cases with ccRCC were analyzed using tissue microarrays (TMAs).

Results: Our results based on Kaplan-Meier plotter database indicated that a high expression of APOC1 may lead to poor overall survival (OS, p = 0.0019) in patients with ccRCC. Furthermore, the cancer stages and tumor grade of ccRCC appeared to be strongly linked with APOC1 expression according to UALCAN database. Hence, we reached a preliminary conclusion that APOC1 may play a key role in the tumorigenesis and progression of ccRCC. Furthermore, the Kaplan-Meier survival curve analyses of 72 clinical patients indicated that high expression of APOC1 was associated with poor progression-free survival (PFS, p = 0.007) and OS (p = 0.022). In addition, univariate Cox regression analysis confirmed the significant relationship between APOC1 expression and survival (p = 0.038). The TMAs analysis in combination with the patients' clinicopathological features was also performed. The expression of APOC1 was found to be significantly correlated with the tumor size (p = 0.018) and histological grade (p = 0.016).

Conclusions: In conclusion, the findings of our study suggest that APOC1 may serve as a novel diagnostic and prognostic biomarker for ccRCC. Further evidence on the mechanism of APOC1 promoting tumor progression may transform it to a new therapeutic target for the treatment of ccRCC.

The crosstalk: exosomes and lipid metabolism

Exosomes have been considered as novel and potent vehicles of intercellular communication, instead of "cell dust". Exosomes are consistent with anucleate cells, and organelles with lipid bilayer consisting of the proteins and abundant lipid, enhancing their "rigidity" and "flexibility". Neighboring cells or distant cells are capable of exchanging genetic or metabolic information via exosomes binding to recipient cell and releasing bioactive molecules, such as lipids, proteins, and nucleic acids. Of note, exosomes exert the remarkable effects on lipid metabolism, including the synthesis, transportation and degradation of the lipid. The disorder of lipid metabolism mediated by exosomes leads to the occurrence and progression of diseases, such as atherosclerosis, cancer, non-alcoholic fatty liver disease (NAFLD), obesity and Alzheimer's diseases and so on. More importantly, lipid metabolism can also affect the production and secretion of exosomes, as well as interactions with the recipient cells. Therefore, exosomes may be applied as effective targets for diagnosis and treatment of diseases. Video abstract.

Recent insight into the role of FBXW7 as a tumor suppressor

FBXW7 (also known as Fbw7, Sel10, hCDC4, or hAgo) is a tumor suppressor and the most frequently mutated member of the F-box protein family in human cancers. FBXW7 functions as the substrate recognition component of an SCF-type E3 ubiquitin ligase. It specifically controls the proteasome-mediated degradation of many oncoproteins such as c-MYC, NOTCH, KLF5, cyclin E, c-JUN, and MCL1. In this review, we summarize the molecular and biological features of FBXW7 and its substrates as well as the impact of mutations of FBXW7 on cancer development. We also address the clinical potential of anticancer therapy targeting FBXW7.

Prognostic and clinicopathological significance of SR-B1 in solid tumors: A meta-analysis

BACKGROUND

The expression of cell surface receptors is abnormal in malignant tumors. The scavenger receptor class B type I (SR-B1) is an integral membrane glycoprotein receptor that facilitates the selective uptake of cholesterol by malignant cells. Accumulated studies investigated the prognostic role of SR-B1 in many solid tumors, such as breast cancer, lung cancer and so on. However, the conclusions remain undefined. Therefore, we conducted this meta-analysis to obtain more accurate evaluation of prognostic significance of SR-B1 in solid tumors.

MATERIALS AND METHODS

We searched PubMed, Embase, Web of science and Cochrane library for eligible studies published before November 2018. The included studies investigated the association between the SR-B1 level and clinicopathological features including survival outcomes in solid tumors. Hazard ratios (HRs) with 95% confidence intervals (CIs) were adopted to assess the survival outcomes and odds ratio (ORs) with 95% confidence intervals (CIs) were pooled to evaluated the clinicopathological features.

RESULTS

A total of 10 studies involving 2585 patients were included in this meta-analysis. The results showed that low SR-B1 level was significantly correlated with earlier tumor grade (pooled OR = 2.09, 95%CI = 1.28-3.43, P = 0.001), less nodal involvement (pooled OR = 2.07, 95%CI = 1.43-3.0, P < 0.001), less distant metastasis (OR = 19.8, 95%CI = 2.58-151.65, P = 0.004), smaller tumor size (OR = 2.34, 95%CI = 1.53-3.57, P < 0.001), earlier TNM stage (OR = 3.77, 95%CI = 1.67-8.48, P = 0.001), lower recurrence (HR = 1.98, 95%CI = 1.57-2.49, P = 0.000), and better OS (HR = 1.99, 95%CI = 1.70-2.31, P = 0.000).

CONCLUSION

The low expression of SR-B1 was significantly associated with better clinicopathological status and longer survival in patients with solid tumors. SR-B1 might act as a promising prognostic biomarker for solid tumors.

Cholesterol metabolism in cancer: mechanisms and therapeutic opportunities

Cholesterol metabolism produces essential membrane components as well as metabolites with a variety of biological functions. In the tumour microenvironment, cell-intrinsic and cell-extrinsic cues reprogram cholesterol metabolism and consequently promote tumourigenesis. Cholesterol-derived metabolites play complex roles in supporting cancer progression and suppressing immune responses. Preclinical and clinical studies have shown that manipulating cholesterol metabolism inhibits tumour growth, reshapes the immunological landscape and reinvigorates anti-tumour immunity. Here, we review cholesterol metabolism in cancer cells, its role in cancer progression and the mechanisms through which cholesterol metabolites affect immune cells in the tumour microenvironment. We also discuss therapeutic strategies aimed at interfering with cholesterol metabolism, and how the combination of such approaches with existing anti-cancer therapies can have synergistic effects, thus offering new therapeutic opportunities.

N6-Isopentenyladenosine Inhibits Colorectal Cancer and Improves Sensitivity to 5-Fluorouracil-Targeting FBXW7 Tumor Suppressor

N6-isopentenyladenosine has been shown to exert potent in vitro antitumor activity on different human cancers, including colorectal cancer. Although some potential biochemical targets have been identified, its precise mechanism of action remains unclear. We found that N6-isopentenyladenosine affects colorectal cancer proliferation in in vitro models carrying different mutational status of FBXW7 and TP53 genes, and in HCT116 xenografts in SCID mice, by increasing the expression of the well-established tumor suppressor FBXW7, a component of the SCF-E3 ubiquitin ligase complex that promotes degradation of various oncoproteins and transcription factors, such as c-Myc, SREBP and Mcl1. Corroborating our previous studies, we identified for the first time the FBXW7/SREBP/FDPS axis as a target of the compound. Pull down of ubiquitinated proteins, immunoprecipitation and luciferase assays, reveal that through the increase of FBXW7/c-Myc binding, N6-isopentenyladenosine induces the ubiquitination of c-Myc, inhibiting its transcriptional activity. Moreover, in FBXW7- and TP53-wild type cells, N6-isopentenyladenosine strongly synergizes with 5-Fluorouracil to inhibit colon cancer growth in vitro. Our results provide novel insights into the molecular mechanism of N6-isopentenyladenosine, revealing its multi-targeting antitumor action, in vitro and in vivo. Restoring of FBXW7 tumor-suppressor represents a valid therapeutic tool, enabling N6-isopentenyladenosine as optimizable compound for patient-personalized therapies in colorectal cancer.

MicroRNA-27a (miR-27a) in Solid Tumors: A Review Based on Mechanisms and Clinical Observations

MicroRNAs (miRNAs) are a family of highly conserved, non-coding single-stranded RNAs transcribed as ~70 nucleotide precursors to an 18–22 nucleotide product (1). miRNAs can silence their homologous target genes at the post-transcriptional level, and these genes have been revealed to play an important role in tumorigenesis, invasion and metastasis (2). MicroRNA-27a (miR-27a), transcripted by miR-27a gene, has proved to implicate with many kinds of solid tumors, showing potential as a useful biomarker or drug target for clinical application. However, even though miR-27a has been reported in many cancers, the mechanism and signal pathways of miR-27 in oncogenesis, invasion, and metastasis are still obscure. Moreover, recent studies show that miR-27a pays an important role in epithelial-mesenchymal-transition, regulating tumor immune response, and chemoresistance. In this review, we summarize the current literature, demonstrate the established link between miR-27a and tumorigenesis, and focus on recently identified mechanisms. The review also aims to demonstrate the potential of miR-27a as a diagnostic and/or prognostic biomarker in solid tumors and to discuss the possibilities of targeted therapy and drug design.

Metformin exhibited anticancer activity by lowering cellular cholesterol content in breast cancer cells

Metformin, a widely prescribed anti-diabetic drug, shows anticancer activity in various cancer types. Few studies documented that there was a decreased level of LDL and total cholesterol in blood serum of metformin users. Based on these views, this study aimed to determine if metformin exhibits anticancer activity by alleviating cholesterol level in cancer cells. The present study found that treatment of breast cancer MDA-MB-231 cells with metformin significantly decreased cholesterol content with concomitant inhibition of various cholesterol regulatory genes (e.g., HMGCoR, LDLR and SREBP1). Metformin decreased cell viability, migration and stemness in metastatic MDA-MB-231 cells. Similarly, metformin treatment suppressed expressions of anti-apoptotic genes BCL2 and Bcl-xL, and mesenchymal genes vimentin, N-cadherin, Zeb1 and Zeb2 with simultaneous enhancement of apoptotic caspase 3 and Bax, and epithelial genes E-cadherin and keratin 19 expressions, confirming an inhibitory effect of metformin in tumorigenesis. Similar to metformin, depletion of cholesterol by methyl beta cyclodextrin (MBCD) diminished cell viability, migration, EMT and stemness in breast cancer cells. Moreover, metformin-inhibited cell viability, migration, colony and sphere formations were reversed back by cholesterol treatment. Similarly, cholesterol treatment inverted metformin-reduced several gene expressions (e.g., Bcl-xL, BCL2, Zeb1, vimentin, and BMI-1). Additionally, zymography data demonstrated that cholesterol upregulated metformin-suppressed MMP activity. These findings suggested that metformin revealed anticancer activity by lowering of cholesterol content in breast cancer cells. Thus, this study, for the first time, unravelled this additional mechanism of metformin-mediated anticancer activity.