Aberrant lipid metabolism in cancer cells - the role of oncolipid-activated signaling

Causal links between plasma lipidome and ovarian cancer risk: evidence from Mendelian randomization

S. Plasma lipids in circulation are integral to the physiopathological processes of the ovary and may impact the development of various ovarian conditions, including ovarian cancer (OC). This study utilized a two-sample Mendelian randomization method to examine the causal link between changes in 179 plasma lipid groups and ovarian cancer (OC) to gain deeper insights into this association. We used the inverse variance weighted (IVW) method as the main tool for analysis. We utilized statistical data from plasma lipidomics involving 7,174 Finnish individuals and OC data from the FinnGen consortium, including 2,339 European OC patients and 222,078 European healthy controls. Our analysis revealed that elevated levels of four plasma lipids-Phosphatidylcholine (14:0_16:0, O-18:2_18:2, 16:0_20:4)-are linked to an increased risk of OC, while Sphingomyelin (d34:2) seems to act as a protective factor(all P < 0.05). We also conducted tests for heterogeneity and pleiotropy in the MR results. Additionally, reverse MR analysis indicated that OC does not affect plasma levels of these lipids. To determine whether the observed significant plasma lipids influence OC through common risk factors, we selected BMI as a confounder for multivariable Mendelian randomization (MVMR) analysis. The results showed that Sphingomyelin (d34:2) levels remained significantly associated with OC even after including BMI as an exposure factor. Furthermore, we investigated whether these four lipids mediated the effect of BMI on OC but found no evidence supporting their mediating role. In summary, our findings confirm a causal link between certain plasma lipid species and OC, providing fresh perspectives for risk evaluation and potential therapeutic strategies.

Copy Number Gains of VPS72 Drive De Novo Lipogenesis and Hepatocarcinogenesis via ATF3/mTORC1/SREBP1 Axis

Hepatocellular carcinoma (HCC) is the predominant form of primary liver cancer and a major contributor to cancer-related mortality globally. Central to its pathogenesis is the dysregulation of lipid metabolism in hepatocytes, leading to abnormal lipid accumulation. Our bioinformatics analysis has identified the histone acetyltransferase complex subunit VPS72 as being associated with HCC, yet the precise molecular mechanisms through which VPS72 contributes to hepatocarcinogenesis remain poorly understood. Our analysis of extensive HCC patient cohorts identifies a significant proportion with VPS72 copy number gains, which are strongly linked to adverse prognostic outcomes. By integrating RNA-Seq, ChIP-Seq, ATAC-seq, and experimental validation, we show that VPS72 overexpression activates mTORC1 signaling, subsequently promoting lipid synthesis and driving HCC progression. We further uncover that VPS72 modulates the epigenetic landscape by enhancing DNA methylation at the ATF3 promoter, resulting in ATF3 repression and subsequent activation of mTORC1. This study elucidates a novel regulatory axis that links dysregulated lipid metabolism with HCC progression, highlighting potential epigenetic and metabolic targets for therapeutic intervention.

Pathology-specific lipid alterations with triacylglycerol as a potential biomarker in Focal cortical dysplasia (FCD) and Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS)

Focal Cortical Dysplasia (FCD) & Mesial Temporal Lobe Epilepsy-Hippocampal Sclerosis (MTLE-HS) are two common pathologies of drug-resistant focal epilepsy (DRE). Inappropriate localization of the epileptogenic zones (EZs) in FCD is a significant contributing factor to the unsatisfactory surgical results observed in FCD cases. Currently, no molecular or cellular indicators are available which can aid in identifying the epileptogenic zones (EZs) in FCD. Phospholipid modifications in healthy and malignant tumour tissues have been documented and used to demarcate tumour boundaries. The objective of this research was to analyze and evaluate the lipid profiles in a manner that takes into account the specific disease and subtype. The technique of liquid chromatography and tandem mass spectrometry was utilized to detect changes in lipids in surgically resected brain samples from patients with FCD and MTLE-HS, in comparison to non-epileptic controls. Significant upregulation of TAGs was seen in both FCD and MTLE-HS. Additionally, the levels of triglycerides in the plasma of peripheral blood were measured in patients with FCD, MTLE-HS, and healthy individuals as controls. These findings suggest that employing distinct lipid mass spectra could be an effective method for identifying the EZs in FCD. The unique lipid mass spectra of cortical tissues from patients with FCD can be utilized for real-time surgical guidance. Additionally, the plasma triglyceride (TAG) level has the potential to act as a biomarker once validated on a larger cohort.

METTL16 inhibits papillary thyroid cancer tumorigenicity through m6A/YTHDC2/SCD1-regulated lipid metabolism

Papillary thyroid carcinoma (PTC) stands as the leading cancer type among endocrine malignancies, and there exists a strong correlation between thyroid cancer and obesity. However, the clinical significance and molecular mechanism of lipid metabolism in the development of PTC remain unclear. In this study, it was demonstrated that the downregulation of METTL16 enhanced lipid metabolism and promoted the malignant progression of PTC. METTL16 was expressed at lower levels in PTC tissues because of DNMT1-mediated hypermethylation of its promoter. Loss- and gain-of-function studies clarified the effects of METTL16 on PTC progression. METTL16 overexpression increased the abundance of m6A in SCD1 cells, increasing RNA decay via the m6A reader YTHDC2. The SCD1 inhibitor A939572 inhibited growth and slowed down lipid metabolism in PTC cells. These results confirm the crucial role of METTL16 in restraining PTC progression through SCD1-activated lipid metabolism in cooperation with YTHDC2. This suggests that the combination of METTL16 and anti-SCD1 blockade might constitute an effective therapy for PTC.

A Novel Eight-Gene Signature for Lipid Metabolism Predicts the Progression of Cervical Squamous Cell Carcinoma and Endocervical Adenocarcinoma

Recently, studies on the mechanisms underlying lipid metabolic reprogramming in cancer have increased. However, its significance in cervical cancer remains unclear. In the present study, a prognostic signature was constructed for patients with cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) using the expression profiles of lipid metabolism-related genes (LMRGs). Furthermore, using various bioinformatics methods, a prognostic gene signature was developed for progression-free survival (PFS). This signature was externally validated using a cervical cancer dataset (GSE44001). The characteristics of the molecular subgroups of LMRGs were analyzed, and target LMRGs were identified via differential gene analysis of the expression profiles and weighted gene correlation network analysis. Thereafter, the identified target genes were used to develop the prognostic gene signature using univariate, least absolute shrinkage and selection operator, and multivariate Cox regression analyses. The performance of the LMRG signature was evaluated using Kaplan-Meier curves, time-dependent receiver operating characteristic curves, decision curve analysis, mutation landscapes, gene set enrichment analysis, and immune score calculation. As a result, a novel eight-LMRG signature comprising ALDH3B2, CERS3, FA2H, GLTP, NR1H3, PLIN3, SLC44A3, and SQLE was constructed. Using this gene signature, patients with CESC and significantly distinguished PFS were divided. This eight-LMRG signature exhibited independent prognostic potential and superior predictive performance compared with a previously developed 12-gene signature. Our findings suggest that our novel eight-LMRG signature contributes to the implementation of precision medicine strategies for managing patients with cervical cancer by facilitating CESC prognosis.

Fourier Transform Infrared microspectroscopy identifies single cancer cells in blood. A feasibility study towards liquid biopsy

The management of cancer patients has markedly improved with the advent of personalised medicine where treatments are given based on tumour antigen expression amongst other. Within this remit, liquid biopsies will no doubt improve this personalised cancer management. Identifying circulating tumour cells in blood allows a better assessment for tumour screening, staging, response to treatment and follow up. However, methods to identify/capture these circulating tumour cells using cancer cells' antigen expression or their physical properties are not robust enough. Thus, a methodology that can identify these circulating tumour cells in blood regardless of the type of tumour is highly needed. Fourier Transform Infrared (FTIR) microspectroscopy, which can separate cells based on their biochemical composition, could be such technique. In this feasibility study, we studied lung cancer cells (squamous cell carcinoma and adenocarcinoma) mixed with peripheral blood mononuclear cells (PBMC). The data obtained shows, for the first time, that FTIR microspectroscopy together with Random Forest classifier is able to identify a single lung cancer cell in blood. This separation was easier when the region of the IR spectra containing lipids and the amide A (2700 to 3500 cm-1) was used. Furthermore, this work was carried out using glass coverslips as substrates that are widely used in pathology departments. This allows further histopathological cell analysis (staining, immunohistochemistry, …) after FTIR spectra are obtained. Hence, although further work is needed using blood samples from patients with cancer, FTIR microspectroscopy could become another tool to be used in liquid biopsies for the identification of circulating tumour cells, and in the personalised management of cancer.

Co-Targeting FASN and mTOR Suppresses Uveal Melanoma Growth

Uveal melanoma (UM) displays a high frequency of metastasis; however, effective therapies for metastatic UM are limited. Identifying unique metabolic features of UM may provide a potential targeting strategy. A lipid metabolism protein expression signature was induced in a normal choroidal melanocyte (NCM) line transduced with GNAQ (Q209L), a driver in UM growth and development. Consistently, UM cells expressed elevated levels of fatty acid synthase (FASN) compared to NCMs. FASN upregulation was associated with increased mammalian target of rapamycin (mTOR) activation and sterol regulatory element-binding protein 1 (SREBP1) levels. FASN and mTOR inhibitors alone significantly reduced UM cell growth. Concurrent inhibition of FASN and mTOR further reduced UM cell growth by promoting cell cycle arrest and inhibiting glucose utilization, TCA cycle metabolism, and de novo fatty acid biosynthesis. Our findings indicate that FASN is important for UM cell growth and co-inhibition of FASN and mTOR signaling may be considered for treatment of UM.

Lipid metabolism in tumor immunology and immunotherapy

Lipids are a diverse class of biomolecules that have been implicated in cancer pathophysiology and in an array of immune responses, making them potential targets for improving immune responsiveness. Lipid and lipid oxidation also can affect tumor progression and response to treatment. Although their importance in cellular functions and their potential as cancer biomarkers have been explored, lipids have yet to be extensively investigated as a possible form of cancer therapy. This review explores the role of lipids in cancer pathophysiology and describes how further understanding of these macromolecules could prompt novel treatments for cancer.

PPARα at the crossroad of metabolic-immune regulation in cancer

Rewiring metabolism to sustain cell growth, division, and survival is the most prominent feature of cancer cells. In particular, dysregulated lipid metabolism in cancer has received accumulating interest, since lipid molecules serve as cell membrane structure components, secondary signaling messengers, and energy sources. Given the critical role of immune cells in host defense against cancer, recent studies have revealed that immune cells compete for nutrients with cancer cells in the tumor microenvironment and accordingly develop adaptive metabolic strategies for survival at the expense of compromised immune functions. Among these strategies, lipid metabolism reprogramming toward fatty acid oxidation is closely related to the immunosuppressive phenotype of tumor-infiltrated immune cells, including macrophages and dendritic cells. Therefore, it is important to understand the lipid-mediated crosstalk between cancer cells and immune cells in the tumor microenvironment. Peroxisome proliferator-activated receptors (PPARs) consist of a nuclear receptor family for lipid sensing, and one of the family members PPARα is responsible for fatty acid oxidation, energy homeostasis, and regulation of immune cell functions. In this review, we discuss the emerging role of PPARα-associated metabolic-immune regulation in tumor-infiltrated immune cells, and key metabolic events and pathways involved, as well as their influences on antitumor immunity.

NSCLC Cells Resistance to PI3K/mTOR Inhibitors Is Mediated by Delta-6 Fatty Acid Desaturase (FADS2)

Hyperactivation of the phosphatidylinositol-3-kinase (PI3K) pathway is one of the most common events in human cancers. Several efforts have been made toward the identification of selective PI3K pathway inhibitors. However, the success of these molecules has been partially limited due to unexpected toxicities, the selection of potentially responsive patients, and intrinsic resistance to treatments. Metabolic alterations are intimately linked to drug resistance; altered metabolic pathways can help cancer cells adapt to continuous drug exposure and develop resistant phenotypes. Here we report the metabolic alterations underlying the non-small cell lung cancer (NSCLC) cell lines resistant to the usual PI3K-mTOR inhibitor BEZ235. In this study, we identified that an increased unsaturation degree of lipid species is associated with increased plasma membrane fluidity in cells with the resistant phenotype and that fatty acid desaturase FADS2 mediates the acquisition of chemoresistance. Therefore, new studies focused on reversing drug resistance based on membrane lipid modifications should consider the contribution of desaturase activity.

Organelle-targeted therapies: a comprehensive review on system design for enabling precision oncology

Cancer is a major threat to human health. Among various treatment methods, precision therapy has received significant attention since the inception, due to its ability to efficiently inhibit tumor growth, while curtailing common shortcomings from conventional cancer treatment, leading towards enhanced survival rates. Particularly, organelle-targeted strategies enable precise accumulation of therapeutic agents in organelles, locally triggering organelle-mediated cell death signals which can greatly reduce the therapeutic threshold dosage and minimize side-effects. In this review, we comprehensively discuss history and recent advances in targeted therapies on organelles, specifically including nucleus, mitochondria, lysosomes and endoplasmic reticulum, while focusing on organelle structures, organelle-mediated cell death signal pathways, and design guidelines of organelle-targeted nanomedicines based on intervention mechanisms. Furthermore, a perspective on future research and clinical opportunities and potential challenges in precision oncology is presented. Through demonstrating recent developments in organelle-targeted therapies, we believe this article can further stimulate broader interests in multidisciplinary research and technology development for enabling advanced organelle-targeted nanomedicines and their corresponding clinic translations.

Mechanisms of Anergic Inflammatory Response in Nasopharyngeal Carcinoma Cells Despite Ubiquitous Constitutive NF-κB Activation

Commensal microbes cross talk with their colonized mucosa. We show that microbes and their cell wall components induce an inflammatory response in cultured human mucosal cells derived from the nonmalignant nasopharyngeal epithelium (NNE) cells in vitro. NNE cells show significant induction of NF-κB with nuclear shuttling and inflammatory gene response when exposed to Gram-positive bacteria (streptococci) or peptidoglycan (PGN), a component of the Gram-positive bacterial cell wall. This response is abrogated in nasopharyngeal carcinoma (NPC)–derived cell lines. The inflammatory response induced by NF-κB signaling was blocked at two levels in the tumor-derived cells. We found that NF-κB was largely trapped in lipid droplets (LDs) in the cytoplasm of the NPC-derived cells, while the increased expression of lysine-specific histone demethylase 1 (LSD1, a repressive nuclear factor) reduces the response mediated by remaining NF-κB at the promoters responding to inflammatory stimuli. This refractory response in NPC cells might be a consequence of long-term exposure to microbes in vivo during carcinogenic progression. It may contribute to the decreased antitumor immune responses in NPC, among others despite heavy T-helper cell infiltration, and thus facilitate tumor progression.

Statins Lower Lipid Synthesis But Promote Secretion of Cholesterol-Enriched Extracellular Vesicles and Particles

Lipid droplets are lipid-rich cytosolic organelles that play roles in cell signaling, membrane trafficking, and many other cellular activities. Recent studies revealed that lipid droplets in cancer cells have various biological functions, such as energy production, membrane synthesis, and chemoresistance, thereby fostering cancer progression. Accordingly, the administration of antilipemic agents could improve anti-cancer treatment efficacy given hydrophobic chemotherapeutic drugs could be encapsulated into lipid droplets and then expelled to extracellular space. In this study, we investigated whether statins could promote treatment efficacy of lipid droplet-rich ovarian SKOV-3 cells and the potential influences on generation and composition of cell-derived extracellular vesicles and particles (EVP). Our studies indicate that statins can significantly lower lipid biosynthesis. Moreover, statins can inhibit proliferation, migration, and invasion of SKOV-3 cells and enhance chemosensitivity in vitro and in vivo. Furthermore, statins can lower EVP secretion but enforce the release of cholesterol-enriched EVPs, which can further lower lipid contents in parental cells. It is the first time that the influence of statins on EVP generation and EVP-lipid composition is observed. Overall, we demonstrated that statins could inhibit lipid production, expel cholesterol to extracellular space via EVPs, and improve chemosensitivity.

iTRAQ-Based Proteomic Analysis Reveals Potential Serum Biomarkers for Pediatric Non-Hodgkin's Lymphoma

Non-Hodgkin’s lymphoma (NHL) is the third most common malignant tumor among children. However, at initial NHL diagnosis, most cases are at an advanced stage because of nonspecific clinical manifestations and currently limited diagnostic methods. This study aimed to screen and verify potential serum biomarkers of pediatric NHL using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomic analysis. Serum protein expression profiles from children with B-NHL (n=20) and T-NHL (n=20) and healthy controls (n=20) were detected by utilizing iTRAQ in combination with two-dimensional liquid chromatography-tandem mass spectrometry (2D LC–MS/MS) and analyzed by applying Ingenuity Pathway Analysis (IPA). The candidate biomarkers S100A8 and LRG1 were further validated by using enzyme-linked immunosorbent assays (ELISAs). Receiver operating characteristic (ROC) analysis based on ELISA data was used to evaluate diagnostic efficacy. In total, 534 proteins were identified twice using iTRAQ combined with 2D LC–MS/MS. Further analysis identified 79 and 73 differentially expressed proteins in B-NHL and T-NHL serum, respectively, compared with control serum according to our defined criteria; 34 proteins were overexpressed and 45 proteins underexpressed in B-NHL, whereas 45 proteins were overexpressed and 28 proteins underexpressed in T-NHL (p < 0.05). IPA demonstrated a variety of signaling pathways, including acute phase response signaling and liver X receptor/retinoid X receptor (LXR/RXR) activation, to be strongly associated with pediatric NHL. S100A8 and LRG1 were elevated in NHL patients compared to normal controls according to ELISA (p < 0.05), which was consistent with iTRAQ results. The areas under the ROC curves of S100A8, LRG1, and the combination of S100A8 and LRG1 were 0.873, 0.898 and 0.970, respectively. Our findings indicate that analysis of the serum proteome using iTRAQ combined with 2D LC–MS/MS is a feasible approach for biomarker discovery. Serum S100A8 and LRG1 are promising candidate biomarkers for pediatric NHL, and these differential proteins illustrate a novel pathogenesis and may be clinically helpful for NHL diagnosis in the future.

Hsa_Circ_0098181 Suppresses Hepatocellular Carcinoma by Sponging miR-18a-3p and Targeting PPARA

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths, and its incidence is still high in China. This study aimed to investigate the circular RNAs (circRNAs) involved in the development of HCC and elucidate the mechanism. RNA sequencing found 72 downregulated circRNAs and 88 upregulated circRNAs in human HCC tissues, including hsa_circ_0098181, hsa_circ_0072309, hsa_circ_0000831, and hsa_circ_0000231. The reduction of hsa_circ_0098181 was confirmed in eight paired human HCC tissues, hepatoma cell lines, and CCL4/DEN-induced mouse HCC models by RT-qPCR. The FISH assay revealed that hsa_circ_0098181 is mainly located in the cytoplasm of hepatocytes in the paratumor tissues. Further log-rank analysis performed in 91 HCC patients demonstrated that low expression of hsa_circ_0098181 was related to poor prognosis. The plasmid and lentivirus overexpressing hsa_circ_0098181 were delivered into HCC cell lines. After hsa_circ_0098181 was upregulated, the proliferation, invasion, migration, and colony formation of HCC cell lines were inhibited, and the apoptosis was promoted. Moreover, exogenous hsa_circ_0098181 delivery mitigated the tumor formation ability of Huh7 in Balb/C nude mice. The dual-luciferase reporter assay and the RIP assay verified that hsa_circ_0098181 sponged miR-18a-3p to regulate PPARA. In addition, a rescue experiment found miR-18a-3p mimic partly reversed the suppression of hsa_circ_0098181 on proliferation, invasion, and migration of HCC cell lines. In conclusion, hsa_circ_0098181 can repress the development of HCC through sponging miR-18a-3p and promoting the expression of PPARA in vitro and in vivo, and hsa_circ_0098181 might be a therapeutic target for HCC.

Attenuation of obesity-induced hyperlipidemia reduces tumor growth

Accumulating evidence suggests that hyperlipidemia is associated with obesity and cancer mortality in humans. We tested the hypotheses that inhibition of microsomal triglyceride transfer protein (MTP) would attenuate obesity-induced hyperlipidemia and reduce tumor growth by treating BCR-ABL B cell tumor-bearing hyperlipidemic obese ob/ob obese mice with a MTP inhibitor. MTP inhibition in tumor-bearing mice reduced concentrations of plasma apoB100 5-fold together with a corresponding decrease in VLDL triacylglycerol (TG) and cholesterol. Inhibition of MTP decreased tumor volume by 50%. MTP inhibitor did not alter tumor cell viability in vitro, suggesting that the in vivo tumor shrinkage effect was related to altered circulating lipids. Tumor volume reduction occurred without change in the protein expression of LDLR, FASN and HMGCR in the tumor, suggesting a lack of compensatory mechanisms in response to decreased hyperlipidemia. Expression of genes encoding GLUT4 and PEPCK was increased 6- and 10-fold, respectively, but no change in the expression of genes encoding regulatory enzymes of glycolysis was observed, suggesting that the tumors were not dependent on or switching to carbohydrates for energy requirement to support their growth. No change of proliferative signaling PI3K/AKT and ERK pathways after MTP inhibition was observed in the tumors. In conclusion, MTP inhibition decreased dyslipidemia and tumor growth in obese, insulin resistant mice. Therefore, decreasing VLDL secretion could be further explored as an adjuvant therapeutic intervention together with standard care to reduce tumor growth in obese patients.

Modulation of DNA/RNA Methylation Signaling Mediating Metabolic Homeostasis in Cancer

Nucleic acid methylation is a fundamental epigenetic mechanism that impinges upon several cellular attributes, including metabolism and energy production. The dysregulation of deoxyribonucleic acid (DNA)/ribonucleic acid (RNA) methylation can lead to metabolic rewiring in the cell, which in turn facilitates tumor development. Here, we review the current knowledge on the interplay between DNA/RNA methylation and metabolic programs in cancer cells. We also discuss the mechanistic role of these pathways in tumor development and progression.

Decreased serum levels of glycerol-3- phosphate dehydrogenase 1 and monoacylglycerol lipase act as diagnostic biomarkers for breast cancer

BACKGROUND

Breast cancer (BC) is one of the most life-threatening cancer types among women. Despite major developments in medical sciences and technologies, the incidence and mortality rates of BC cases are still increasing. One of the reasons for this increase is the absence of an easy to perform early-diagnostic tool. Although there are defined BC biomarkers routinely used for diagnostic and prognostic purposes, none of these biomarkers is useful for early diagnosis. Therefore, early diagnosis of BC remains an important challenge and there is a great need for the early-diagnostic biomarker(s).

OBJECTIVE

In this study, we aimed to evaluate the diagnostic and prognostic values of glycerol-3-phosphate dehydrogenase (GPD1) and monoacylglycerol lipase (MAGL) proteins as non-invasive serum biomarkers.

METHODS

GPD1 and MAGL serum levels were determined by ELISA for BC patients (n= 100) from five different subtypes, and healthy controls (n= 20), and a comparative analysis was performed to determine statistically significant expression differences among the groups.

RESULTS

The results provided evidence that GPD1 acted as a diagnostic biomarker in distinguishing triple-negative breast cancer (TNBC) patients from other subtypes, and MAGL acted as a diagnostic biomarker in distinguishing healthy individuals from BC patients.

CONCLUSION

GPD1 and MAGL might be proposed as non-invasive diagnostic biomarkers for BC with high sensitivity and specificity.

Short communication: Distribution of phospholipids in parotid cancer by matrix-assisted laser desorption/ionization imaging mass spectrometry

Background

Parotid cancer is relatively rare, and malignancy varies; therefore, novel markers are needed to predict prognosis. Recent advances in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS), useful for visualization of lipid molecules, have revealed the relationship between cancer and lipid metabolism, indicating the potential of lipids as biomarkers. However, the distribution and importance of phospholipids in parotid cancer remain unclear.

Objective

This study aimed to use MALDI-IMS to comprehensively investigate the spatial distribution of phospholipids characteristically expressed in human parotid cancer tissues.

Methods

Tissue samples were surgically collected from two patients with parotid cancer (acinic cell carcinoma and mucoepidermoid carcinoma). Frozen sections of the samples were assessed using MALDI-IMS in both positive and negative ion modes, with an m/z range of 600–1000. The mass spectra obtained in the tumor and non-tumor regions were compared and analyzed. Ion images corresponding to the peak characteristics of the tumor regions were visualized.

Results

Several candidate phospholipids with significantly different expression levels were detected between the tumor and non-tumor regions. The number of unique lipid peaks with significantly different intensities between the tumor and non-tumor regions was 95 and 85 for Cases 1 and 2, respectively, in positive ion mode, and 99 and 97 for Cases 1 and 2, respectively, in negative ion mode. Imaging differentiated the characteristics that phospholipids were heterogeneously distributed in the tumor regions.

Conclusion

Phospholipid candidates that are characteristically expressed in human parotid cancer tissues were found, demonstrating the localization of their expression. These findings are notable for further investigation of alterations in lipid metabolism of parotid cancer and may have potential for the development of phospholipids as biomarkers.

Microenvironmental Factors Modulating Tumor Lipid Metabolism: Paving the Way to Better Antitumoral Therapy

Metabolic reprogramming is one of the emerging hallmarks of cancer and is driven by both the oncogenic mutations and challenging microenvironment. To satisfy the demands of energy and biomass for rapid proliferation, the metabolism of various nutrients in tumor cells undergoes important changes, among which the aberrant lipid metabolism has gained increasing attention in facilitating tumor development and metastasis in the past few years. Obstacles emerged in the aspect of application of targeting lipid metabolism for tumor therapy, due to lacking of comprehensive understanding on its regulating mechanism. Tumor cells closely interact with stromal niche, which highly contributes to metabolic rewiring of critical nutrients in cancer cells. This fact makes the impact of microenvironment on tumor lipid metabolism a topic of renewed interest. Abundant evidence has shown that many factors existing in the tumor microenvironment can rewire multiple signaling pathways and proteins involved in lipid metabolic pathways of cancer cells. Hence in this review, we summarized the recent progress on the understanding of microenvironmental factors regulating tumor lipid metabolism, and discuss the potential of modulating lipid metabolism as an anticancer approach.

A Novel Lipid Prognostic Signature of ADCY2, LIPE, and OLR1 in Head and Neck Squamous Cell Carcinoma

SIMPLE SUMMARY

Clinically, aberrant lipid metabolism is responsible for overweight and/or obesity. Overweight is considered as an independent factor of cancer risk in 2019. Therefore, lipid metabolic reprogramming is an emerging hallmark of malignancy. It is an urgent need to comprehensively understand the relationship among lipid metabolism and HNSCC and identify a valuable biomarker for predicting prognosis of HNSCC patients. Three new findings were found in this study. Firstly, we identified the lipid-related differentially expressed genes (DEGs) by using the GEO microarrays and TCGA dataset. A novel lipid-related mRNA prognostic signature (LRPS, consisting of ADCY2, LIPE and OLR1) was developed, which could predict the survival and prognosis of HNSCC patients as an independent effective prognostic factor. Secondly, we found that the LRPS could indicate the type of infiltrated immune cells in HNSCC tumor microenvironment. Thirdly, we verified that the LPPS score could interpret the TP53 status of HNSCC. Our new findings indicated that LRPS has a potential to be a promising indicator of overall survival, TP53 status, and immune characteristics in HNSCC, and perhaps can monitor and guide the treatment efficacy and prognosis of HNSCC in the future.

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is characterized by a high frequency of lymph node metastasis and a high mortality. Lipid metabolic reprogramming is an emerging carcinogen as its role in fulfilling cancer growth and spread. However, little is known about the correlation between lipid metabolism and HNSCC.

MATERIALS AND METHODS

Expressions of lipid-related genes were obtained from the Cancer Genome Atlas (TCGA) and Gene expression Omnibus (GEO) databases for differential and functional analyses. A total number of 498 patients from TCGA with complete information were included to identify a lipid-related prognostic signature (LRPS), based on ADCY2, LIPE, and OLR1, by using univariate and multivariate Cox regression analyses. LRPS-high and LRPS-low groups were accordingly divided to pathway and cell enrichment analyses.

RESULTS

LRS-low patients had a better overall survival and relapse - free survival than LRS-high ones in HNSCC. The LRPS-high group was significantly related to perineural invasion of cancer, cancer-related pathways, high TP53 mutation rate, high proportion of natural killer T cells (NKT), dendritic cells, monocytes, Treg, and M1 and M2 macrophage infiltration in HNSCC tumor tissues. Conversely, the LRPS-low group correlated with DNA damage-related and T-cell-regulated pathways, low frequency of mutated TP53, and high infiltration of B cells and CD4+ effector cells including Th1 and Th2.

CONCLUSION

LRPS has a potential to be a promising indicator of overall survival, prognosis, TP53 status, and immune characteristics in HNSCC.

Regulatory role and mechanism of m6A RNA modification in human metabolic diseases

Metabolic diseases caused by disorders in amino acids, glucose, lipid metabolism, and other metabolic risk factors show high incidences in young people, and current treatments are ineffective. N⁶-methyladenosine (m⁶A) RNA modification is a post-transcriptional regulation of gene expression with several effects on physiological processes and biological functions. Recent studies report that m⁶A RNA modification is involved in various metabolic pathways and development of common metabolic diseases, making it a potential disease-specific therapeutic target. This review explores components, mechanisms, and research methods of m⁶A RNA modification. In addition, we summarize the progress of research on m⁶A RNA modification in metabolism-related human diseases, including diabetes, obesity, non-alcoholic fatty liver disease, osteoporosis, and cancer. Furthermore, opportunities and the challenges facing basic research and clinical application of m⁶A RNA modification in metabolism-related human diseases are discussed. This review is meant to enhance our understanding of the molecular mechanisms, research methods, and clinical significance of m⁶A RNA modification in metabolism-related human diseases.

LncRNA PCA3 promotes antimony-induced lipid metabolic disorder in prostate cancer by targeting MIR-132-3 P/SREBP1 signaling

Antimony is a common environmental contaminant that causes biological toxicity in exposed populations worldwide. Previous studies have revealed that antimony promotes prostate cancer growth by stabilizing the c-Myc protein and mimicking androgen activity. However, the role of lncRNAs in the regulation of antimony-induced carcinogenesis remains unknown, and the precise mechanisms need to be explored. In the present study, we found that chronic exposure to antimony promoted cell growth and lipid metabolic disequilibrium in prostate cancer. Mechanistically, we identified a long noncoding RNA molecule, PCA3, that was substantially upregulated in LNCaP cells in response to long-term antimony exposure. Functional studies indicated that abnormal PCA3 expression modulated antimony-induced proliferation and cellular triglyceride and cholesterol levels. In addition, PCA3 levels were found to be inversely correlated with MIR-132-3 P levels by acting as a decoy for MIR-132-3P. Besides, SREBP1 directly interacted with MIR-132-3 P to increase cell growth and disrupt lipid metabolism by targeting its 3'UTR regions. Taken together, our results revealed that lncRNA PCA3 promotes antimony-induced lipid metabolic disorder in prostate cancer by targeting MIR-132-3 P/SREBP1 signaling.

Optical Photothermal Infrared Microspectroscopy Discriminates for the First Time Different Types of Lung Cells on Histopathology Glass Slides

The debate of whether a glass substrate can be used in Fourier transform infrared spectroscopy is strongly linked to its potential clinical application. Histopathology glass slides of 1 mm thickness absorb the mid-IR spectrum in the rich fingerprint spectral region. Thus, it is important to assess whether emerging IR techniques can be employed to study biological samples placed on glass substrates. For this purpose, we used optical photothermal infrared (O-PTIR) spectroscopy to study for the first time malignant and non-malignant lung cells with the purpose of identifying IR spectral differences between these cells placed on standard pathology glass slides. The data in this feasibility study showed that O-PTIR can be used to obtain good-quality IR spectra from cells from both the lipid region (3000-2700 cm^-1) and the fingerprint region between 1770 and 950 cm^-1 but with glass contributions from 1350 to 950 cm^-1. A new single-unit dual-range (C-H/FP) quantum cascade laser (QCL) IR pump source was applied for the first time, delivering a clear synergistic benefit to the classification results. Furthermore, O-PTIR is able to distinguish between lung cancer cells and non-malignant lung cells both in the lipid and fingerprint regions. However, when these two spectral ranges are combined, classification accuracies are enhanced with Random Forest modeling classification accuracy results ranging from 96 to 99% across all three studied cell lines. The methodology described here for the first time with a single-unit dual-range QCL for O-PTIR on glass is another step toward its clinical application in pathology.

Pathogenesis and therapeutic strategy in platinum resistance lung cancer

Platinum compounds (cisplatin and carboplatin) represent the most active anticancer agents in clinical use both of lung cancer in mono-and combination therapies. However, platinum resistance limits its clinical application. It is necessary to understand the molecular mechanism of platinum resistance, identify predictive markers, and develop newer, more effective and less toxic agents to treat platinum resistance in lung cancer. Here, it summarizes the main molecular mechanisms associated with platinum resistance in lung cancer and the development of new approaches to tackle this clinically relevant problem. Moreover, it could lead to the development of more effective treatment for refractory lung cancer in future.

Group III phospholipase A2 downregulation attenuated survival and metastasis in ovarian cancer and promotes chemo-sensitization

Background

Aberrant lipogenicity and deregulated autophagy are common in most advanced human cancer and therapeutic strategies to exploit these pathways are currently under consideration. Group III Phospholipase A2 (sPLA2-III/PLA2G3), an atypical secretory PLA2, is recognized as a regulator of lipid metabolism associated with oncogenesis. Though recent studies reveal that high PLA2G3 expression significantly correlates with poor prognosis in several cancers, however, role of PLA2G3 in ovarian cancer (OC) pathogenesis is still undetermined.

Methods

CRISPR-Cas9 and shRNA mediated knockout and knockdown of PLA2G3 in OC cells were used to evaluate lipid droplet (LD) biogenesis by confocal and Transmission electron microscopy analysis, and the cell viability and sensitization of the cells to platinum-mediated cytotoxicity by MTT assay. Regulation of primary ciliation by PLA2G3 downregulation both genetically and by metabolic inhibitor PFK-158 induced autophagy was assessed by immunofluorescence-based confocal analysis and immunoblot. Transient transfection with GFP-RFP-LC3B and confocal analysis was used to assess the autophagic flux in OC cells. PLA2G3 knockout OVCAR5 xenograft in combination with carboplatin on tumor growth and metastasis was assessed in vivo. Efficacy of PFK158 alone and with platinum drugs was determined in patient-derived primary ascites cultures expressing PLA2G3 by MTT assay and immunoblot analysis.

Results

Downregulation of PLA2G3 in OVCAR8 and 5 cells inhibited LD biogenesis, decreased growth and sensitized cells to platinum drug mediated cytotoxicity in vitro and in in vivo OVCAR5 xenograft. PLA2G3 knockdown in HeyA8MDR-resistant cells showed sensitivity to carboplatin treatment. We found that both PFK158 inhibitor-mediated and genetic downregulation of PLA2G3 resulted in increased number of percent ciliated cells and inhibited cancer progression. Mechanistically, we found that PFK158-induced autophagy targeted PLA2G3 to restore primary cilia in OC cells. Of clinical relevance, PFK158 also induces percent ciliated cells in human-derived primary ascites cells and reduces cell viability with sensitization to chemotherapy.

Conclusions

Taken together, our study for the first time emphasizes the role of PLA2G3 in regulating the OC metastasis. This study further suggests the therapeutic potential of targeting phospholipases and/or restoration of PC for future OC treatment and the critical role of PLA2G3 in regulating ciliary function by coordinating interface between lipogenesis and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01985-9.

The ALDOA Metabolism Pathway as a Potential Target for Regulation of Prostate Cancer Proliferation

Background

ALDOA plays an essential role in cancer progression in different human cancers; however, its function has not been understood in prostate cancer (PCa).

Methods

Associations of ALDOA expression with clinicopathological features and patient prognosis in PCa were evaluated based on data obtained from the Taylor database and our clinical tissue microarray. The potential roles of ALDOA in malignant progression were verified using a series of in vivo and in vitro experiments after stable ALDOA overexpression and knockdown in DU145 and PC3 cell lines. An aldolase A inhibitor was used to determine the effects of inhibition of ALDOA on PCa cell proliferation.

Results

Higher expression of ALDOA was positively correlated with the incidence of postoperative metastasis and biochemical recurrence (BCR) and may predict poor prognosis in PCa patients. In vivo experiments demonstrated that overexpression of ALDOA could significantly promote cell proliferation, prolong the cell cycle, and significantly reduce the apoptosis rate of PCa cells. Knockdown of expression of ALDOA could inhibit the proliferation and shorten the cell cycle of PCa cells significantly, with no significant effects on cell apoptosis (P > 0.05). In vitro experiments showed that overexpression of ALDOA could significantly promote tumor growth (P < 0.05), while treatment with the Aldolase A inhibitor naphthol AS-E phosphate dose-dependently suppressed the growth of PCa cells (P < 0.01). The analysis of datasets from the Taylor database showed that there was negative regulatory relationship between the expression of ALDOA and MYPT1 (P < 0.001).

Conclusion

Our study revealed that ALDOA played an important role in the progression of PCa. The MYPT1-ALDOA signaling axis may be a new target for the clinical treatment of PCa patients given its negative regulatory relationship. Our study suggests that Aldolase A inhibitors may represent a novel approach to inhibit the growth of PCa.

Can non-cholesterol sterols indicate the presence of specific dysregulation of cholesterol metabolism in patients with colorectal cancer?

Colorectal cancer (CRC) is a highly prevalent malignancy. Previous studies suggested that cholesterol might play a signficant role in malignant transformation and proliferation. Non-cholesterol sterols (NCS), which are transported by serum lipoproteins alongside cholesterol, are regarded as cholesterol synthesis and absorption markers. Quantification of NCS in serum and HDL fraction (NCS_HDL), could provide a better insight into the cholesterol metabolism. The aim of this study was to examine the status of cholesterol synthesis and cholesterol absorption markers in serum and HDL fraction and explore their interrelation in CRC patients. Current study was designed as observational, case-control study. The study included 73 CRC patients and 95 healthy subjects. NCS and NCS_HDL concentrations were determined by HPLC-MS/MS. Based on NCS and NCS_HDL concentrations, different cholesterol homeostasis indices were calculated. Patients had significantly lower NCS (P<0.001) and NCS_HDL concentrations (P<0.001 for desmosterol_HDL; P<0.05 for lathosterol_HDL, P=0.001 for campesterol_HDL, P<0.001 for β-sitosterol_HDL). NCS_HDL/NCS (P<0.005 for desmosterol_HDL/desmosterol; P<0.05 for lathosterol_HDL/lathosterol; P<0.001 for both β-sitosterol_HDL/β-sitosterol and campesterol_HDL/campesterol) and synthesis to absorption ratio (CSI/CAI) (P<0.005) were increased in CRC patients. Additionally, low serum concentrations of desmosterol (P<0.001; OR=0.329; 95%CI (0.199-0.542)) and campesterol (P<0.001; OR=0.540; 95%CI (0.424-0.687)) were independent predictors of CRC presence. Our data suggest that cholesterol homeostasis in CRC is shifted towards increased synthesis. Relative abundance of NCS in HDL particles is increased, suggesting the possible overproduction of cholesterol precursors in peripheral tissues.

Skeletal Muscle-Adipose Tissue-Tumor Axis: Molecular Mechanisms Linking Exercise Training in Prostate Cancer

Increased visceral adiposity may influence the development of prostate cancer (PCa) aggressive tumors and cancer mortality. White adipose tissue (WAT), usually referred to as periprostatic adipose tissue (PPAT), surrounds the prostatic gland and has emerged as a potential mediator of the tumor microenvironment. Exercise training (ET) induces several adaptations in both skeletal muscle and WAT. Some of these effects are mediated by ET-induced synthesis and secretion of several proteins, known as myo- and adipokines. Together, myokines and adipokines may act in an endocrine-like manner to favor communication between skeletal muscle and WAT, as they may work together to improve whole-body metabolic health. This crosstalk may constitute a potential mechanism by which ET exerts its beneficial role in the prevention and treatment of PCa-related disorders; however, this has not yet been explored. Therefore, we reviewed the current evidence on the effects of skeletal muscle–WAT–tumor crosstalk in PCa, and the potential mediators of this process to provide a better understanding of underlying ET-related mechanisms in cancer.

Increased Expression of LIPC Is Associated with Aggressive Phenotype of Borrmann Type 4 Gastric Cancer

PURPOSE

To investigate lipase C hepatic type (LIPC) expression in Borrmann type 4 gastric cancer and its correlation with clinical outcome. The biological roles of LIPC in Borrmann type 4 gastric cancer progression were also investigated.

METHODS

We determined LIPC expression in 324 primary gastric cancer tissues and 178 matched adjacent non-tumor tissues by immunohistochemistry. We explored the role of LIPC in Borrmann type 4 gastric cancer cell (OCUM-1) migration, invasion, proliferation, cell cycle, and expression of epithelial-mesenchymal transition-related genes by knocking down LIPC expression.

RESULTS

LIPC expression was upregulated in Borrmann type 4 gastric cancer tissues compared with other types of gastric cancer and adjacent non-tumor tissues. High LIPC expression correlated with lymph node metastasis, advanced TNM stage, and poor overall survival in Borrmann type 4 gastric cancer patients. Multivariate analysis demonstrated that high LIPC expression was an independent prognostic factor in patients with Borrmann type 4 gastric cancer. By reducing LIPC expression, OCUM-1 cell invasion and migration were suppressed and Snail and MMP2 expression was downregulated, while E-cadherin expression was upregulated.

CONCLUSIONS

High LIPC expression correlates with poor clinical outcome and plays an important role in regulating cell migration and invasion in Borrmann type 4 gastric cancer.

Virtual screening-based identification of novel fatty acid synthase inhibitor and evaluation of its antiproliferative activity in breast cancer cells

Cancer cells activate de novo lipogenesis by overexpressing the lipogenic enzymes ACLY, ACC and FASN to support rapid cell division. FASN, previously known as oncogenic antigen-519 (OA-519) catalyzes seven sequential reactions to synthesize palmitic acid (C16) from substrates acetyl CoA, and malonyl CoA. The dependence of cancer cells on FASN-derived lipids and the differential expression of FASN in cancer cells compared to their normal counterparts make it an attractive metabolic drug target in cancer therapy. In the present study, an attempt has been made to identify potent FASN inhibitors from Asinex-Synergy compound database using structure-based virtual screening. The serial docking protocols of increasing precisions identified LEG-17649942, with glide score -10.34 kcal/mol as a promising compound which can directly interact with active site residues H293 and H331. LEG-17649942 possesses drug-like pharmacokinetic properties as predicted by Qikprop. LEG-17649942 exhibited cytotoxicity in breast cancer cell lines SK-BR-3, MCF-7 and MDA-MB-231 with maximum activity against MDA-MB-231 cells with IC50 of 50 μM. The study put forward LEG-17649942 as a novel drug-lead compound against triple negative breast cancer with an exquisite binding pattern to FASN-KS domain.

Isolation of Extracellular Vesicles from Biological Fluids via the Aggregation-Precipitation Approach for Downstream miRNAs Detection

Extracellular vesicles (EVs) have high potential as sources of biomarkers for non-invasive diagnostics. Thus, a simple and productive method of EV isolation is demanded for certain scientific and medical applications of EVs. Here we aim to develop a simple and effective method of EV isolation from different biofluids, suitable for both scientific, and clinical analyses of miRNAs transported by EVs. The proposed aggregation-precipitation method is based on the aggregation of EVs using dextran blue and the subsequent precipitation of EVs using 1.5% polyethylene glycol solutions. The developed method allows the effective isolation of EVs from plasma and urine. As shown using TEM, dynamic light scattering, and miRNA analyses, this method is not inferior to ultracentrifugation-based EV isolation in terms of its efficacy, lack of inhibitors for polymerase reactions and applicable for both healthy donors and cancer patients. This method is fast, simple, does not need complicated equipment, can be adapted for different biofluids, and has a low cost. The aggregation-precipitation method of EV isolation accessible and suitable for both research and clinical laboratories. This method has the potential to increase the diagnostic and prognostic utilization of EVs and miRNA-based diagnostics of urogenital pathologies.

Circulating Lysophosphatidylcholines, Phosphatidylcholines, Ceramides, and Sphingomyelins and Ovarian Cancer Risk: A 23-Year Prospective Study

BACKGROUND

Experimental evidence supports a role of lipid dysregulation in ovarian cancer progression. We estimated associations with ovarian cancer risk for circulating levels of four lipid groups, previously hypothesized to be associated with ovarian cancer, measured 3-23 years before diagnosis.

METHODS

Analyses were conducted among cases (N = 252) and matched controls (N = 252) from the Nurses' Health Studies. We used logistic regression adjusting for risk factors to investigate associations of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), ceramides (CERs), and sphingomyelins (SMs) with ovarian cancer risk overall and by histotype. A modified Bonferroni approach (0.05/4 = 0.0125, four lipid groups) and the permutation-based Westfall and Young approach were used to account for testing multiple correlated hypotheses. Odds ratios (ORs; 10th-90th percentile), and 95% confidence intervals of ovarian cancer risk were estimated. All statistical tests were two-sided.

RESULTS

SM sum was statistically significantly associated with ovarian cancer risk (OR = 1.97, 95% CI = 1.16 to 3.32; P = .01/permutation-adjusted P = .20). C16:0 SM, C18:0 SM, and C16:0 CERs were suggestively associated with risk (OR = 1.95-2.10; P = .004-.01; permutation-adjusted P = .08-.21). SM sum, C16:0 SM, and C16:0 CER had stronger odds ratios among postmenopausal women (OR = 2.16-3.22). Odds ratios were similar for serous/poorly differentiated and endometrioid/clear cell tumors, although C18:1 LPC and LPC to PC ratio were suggestively inversely associated, whereas C18:0 SM was suggestively positively associated with risk of endometrioid/clear cell tumors. No individual metabolites were associated with risk when using the permutation-based approach.

CONCLUSIONS

Elevated levels of circulating SMs 3-23 years before diagnosis were associated with increased risk of ovarian cancer, regardless of histotype, with stronger associations among postmenopausal women. Further studies are required to validate and understand the role of lipid dysregulation in ovarian carcinogenesis.

Combined transcriptomic and lipidomic analysis reveals aberrant lipid metabolism in central nervous system hemangioblastomas

Peritumoral cysts are commonly detected in the central nervous system tumors, especially hemangioblastomas (HBs). However, the molecular mechanisms driving their formation and propagation are still unknown. We conducted an integrated lipidomics and transcriptomics analysis on solid and cystic HB samples in order to elucidate the changes in the lipid profile and expression of lipid metabolism-related genes during cyst formation. Transcriptomic analysis revealed differential expression of several genes between the solid and cystic HBs, and those associated with lipid metabolism, such as ADCY4, MGLL, ACOT2, DGKG, SHC1 and LPAR2, were markedly dysregulated in the cystic HBs. The lipidomic analysis further showed a significant reduction in the abundance of triacylglycerol, ceramide, lysophosphatidylcholine and lysophosphatidylethanolamine, and an increase in phosphatidylcholine and phosphatidylethanolamine levels in the cystic HBs. Furthermore, bioinformatics analysis revealed altered lipid biosynthesis, glycerophospholipid metabolism and phospholipase activity in the cystic HBs. Taken together, our findings indicate that cyst formation in HBs is related with aberrant lipid metabolism.

Advances in understanding and in multi-disciplinary methodology used to assess lipid regulation of signalling cascades from the cancer cell plasma membrane

The lipid bilayer is a functional component of cells, forming a stable platform for the initiation of key biological processes, including cell signalling. There are distinct changes in the lipid composition of cell membranes during oncogenic transformation resulting in aberrant activation and inactivation of signalling transduction pathways. Studying the role of the cell membrane in cell signalling is challenging, since techniques are often limited to by timescale, resolution, sensitivity, and averaging. To overcome these limitations, combining 'computational', 'wet-lab' and 'semi-dry' approaches offers the best opportunity to resolving complex biological processes involved in membrane organisation. In this review, we highlight analytical tools that have been applied for the study of cell signalling initiation from the cancer cell membranes through computational microscopy, biological assays, and membrane biophysics. The cancer therapeutic potential of extracellular membrane-modulating agents, such as cholesterol-reducing agents is also discussed, as is the need for future collaborative inter-disciplinary research for studying the role of the cell membrane and its components in cancer therapy.

Advances in the role of m6A RNA modification in cancer metabolic reprogramming

N6-methyladenosine (m6A) modification is the most common internal modification of eukaryotic mRNA and is widely involved in many cellular processes, such as RNA transcription, splicing, nuclear transport, degradation, and translation. m6A has been shown to plays important roles in the initiation and progression of various cancers. The altered metabolic programming of cancer cells promotes their cell-autonomous proliferation and survival, leading to an indispensable hallmark of cancers. Accumulating evidence has demonstrated that this epigenetic modification exerts extensive effects on the cancer metabolic network by either directly regulating the expression of metabolic genes or modulating metabolism-associated signaling pathways. In this review, we summarized the regulatory mechanisms and biological functions of m6A and its role in cancer metabolic reprogramming.

Role of Protein Kinase CK2 in Aberrant Lipid Metabolism in Cancer

Uncontrolled proliferation is a feature defining cancer and it is linked to the ability of cancer cells to effectively adapt their metabolic needs in response to a harsh tumor environment. Metabolic reprogramming is considered a hallmark of cancer and includes increased glucose uptake and processing, and increased glutamine utilization, but also the deregulation of lipid and cholesterol-associated signal transduction, as highlighted in recent years. In the first part of the review, we will (i) provide an overview of the major types of lipids found in eukaryotic cells and their importance as mediators of intracellular signaling pathways (ii) analyze the main metabolic changes occurring in cancer development and the role of oncogenic signaling in supporting aberrant lipid metabolism and (iii) discuss combination strategies as powerful new approaches to cancer treatment. The second part of the review will address the emerging role of CK2, a conserved serine/threonine protein kinase, in lipid homeostasis with an emphasis regarding its function in lipogenesis and adipogenesis. Evidence will be provided that CK2 regulates these processes at multiple levels. This suggests that its pharmacological inhibition combined with dietary restrictions and/or inhibitors of metabolic targets could represent an effective way to undermine the dependency of cancer cells on lipids to interfere with tumor progression.

Reduced Expression of hsa-miR-338-3p Contributes to the Development of Glioma Cells by Targeting Mitochondrial 3-Oxoacyl-ACP Synthase (OXSM) in Glioblastoma (GBM)

Background

MicroRNAs have been identified as major regulators and therapeutic targets of glioblastoma (GBM). It is thus meaningful to study the miRNAs differentially expressed (DE-miRNAs) in GBM.

Materials and Methods

We performed a meta-analysis of previously published microarray data using the R-based “metaMA” package to identify DE-miRNAs.The biological processes of the DE-miRNAs were then analyzed using FunRich. KEGG pathways of the DE-miRNAs gene targets were analyzed by mirPath V.3. Luciferase activity assay was performed to validate that OXSM is a direct target of hsa-miR338-3p. Flow cytometry was used to detect the effects of miR-338-3p on GBM cell proliferation, apoptosis and cell cycle.

Results

DE-miRNAs in blood and brain tissue from GBM were identified. “Type I interferon signaling pathway” and “VEGF and VEGFR signaling network” were the most significantly enriched biological processes shared by all GBM types. In KEGG pathway analysis, DE-miRNAs both in blood and tissue show altered fatty acid biosynthesis. Further validation shows hsa-miR-338-3p regulates fatty acid metabolism by directly targeting OXSM gene. In addition, our data revealed an accelerated cell cycle and an anti-apoptotic role for OXSM in glioma cells, which has not been reported. Finally, we confirmed that hsa-miR-338-3p inhibitor antagonized the effect of downregulation of OXSM on cell cycle and apoptosis of GBM cells.

Conclusion

We revealed that hsa-miR-338-3p, down-regulated in GBM, may affect the biogenesis and rapid proliferation of glioma cells by regulating the level of OXSM, providing new insights into understanding the pathogenesis of GBM and developing strategies to improve GBM prognosis.

Aberrant Expression of Citrate Synthase is Linked to Disease Progression and Clinical Outcome in Prostate Cancer

Purpose

Citrate synthase (CS) is a rate-limiting enzyme in the citrate cycle and is capable of catalyzing oxaloacetate and acetyl-CoA to citrate. CS has been uncovered to be upregulated in a variety of cancers, and its expression and clinical significance in prostate cancer (PCa) remain unknown.

Methods

In this study, we examined the association between CS expression level and clinicopathological features of prostate cancer patients in a TMA cohort and the public cancer database (The Cancer Genome Atlas-Prostate Adenocarcinoma, TCGA-PRAD). The CS knockdown cell lines were constructed to study the effects of CS downregulation on proliferation, colony formation, migration, invasion, and cell cycle of prostate cancer cells in vitro. And the effect of CS downregulation on tumor growth in mice was studied in vivo. In addition, the metabolomics and mitochondrial function were detected in the CS knockdown cell lines.

Results

CS expression level in PCa tissues was higher than that in normal tissues (P < 0.05). CS upregulation was significantly associated with high Gleason score (P < 0.05), advanced pathological stage (P < 0.001), and biochemical recurrence (P < 0.001). Functionally, decreased expression of CS inhibited PCa cell proliferation, colony formation, migration, invasion and cell cycle in vitro, and inhibited tumor growth in vivo. In addition, CS downregulation exerted potential inhibitory effects on the lipid metabolism and mitochondrial function of PCa cells.

Conclusion

In conclusion, these findings suggested that CS upregulation may contribute to the aggressive progression and poor prognosis of PCa patients, which might be partially associated with its influences on the cell lipid metabolism and mitochondrial function.

Lipid Metabolism in Development and Progression of Hepatocellular Carcinoma

: Metabolic reprogramming is critically involved in the development and progression of cancer. In particular, lipid metabolism has been investigated as a source of energy, micro-environmental adaptation, and cell signalling in neoplastic cells. However, the specific role of lipid metabolism dysregulation in hepatocellular carcinoma (HCC) has not been widely described yet. Alterations in fatty acid synthesis, β-oxidation, and cellular lipidic composition contribute to initiation and progression of HCC. The aim of this review is to elucidate the mechanisms by which lipid metabolism is involved in hepatocarcinogenesis and tumour adaptation to different conditions, focusing on the transcriptional aberrations with new insights in lipidomics and lipid zonation. This will help detect new putative therapeutic approaches in the second most frequent cause of cancer-related death.

Novel Paclitaxel Nanoformulation Impairs De Novo Lipid Synthesis in Pancreatic Cancer Cells and Enhances Gemcitabine Efficacy

Pancreatic cancer (PanCa) is a highly lethal disease with a poor 5 year survival rate, less than 7%. It has a dismal prognosis, and more than 50% of cases are detected at an advanced and metastatic stage. Gemcitabine (GEM) is a gold standard chemotherapy used for PanCa treatment. However, GEM-acquired resistance in cancer cells is considered as a major setback for its continued clinical implementation. This phenomenon is evidently linked to de novo lipid synthesis. PanCa cells rely on de novo lipid synthesis, which is a prime event in survival and one of the key drivers for tumorigenesis, cancer progression, and drug resistance. Thus, the depletion of lipogenesis or lipid metabolism can not only improve treatment outcomes but also overcome chemoresistance, which is an unmet clinical need. Toward this effort, our study reports a unique paclitaxel-poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PPNPs) formulation which can target lipid metabolism and improve anticancer efficacy of GEM in PanCa cells. PPNPs inhibit excessive lipid formation and alter membrane stability with compromised membrane integrity, which was confirmed by Fourier transform infrared and zeta potential measurements. The effective interference of PPNPs in lipid metabolic signaling was determined by reduction in the expression of FASN, ACC, lipin, and Cox-2 proteins. This molecular action profoundly enhances efficacy of GEM as evident through enhanced inhibitory effects on the tumorigenic and metastasis assays in PanCa cells. These data clearly suggest that the ablation of lipid metabolism might offer an innovative approach for the improved therapeutic outcome in PanCa patients.

Deriving Lipid Classification Based on Molecular Formulas

Despite instrument and algorithmic improvements, the untargeted and accurate assignment of metabolites remains an unsolved problem in metabolomics. New assignment methods such as our SMIRFE algorithm can assign elemental molecular formulas to observed spectral features in a highly untargeted manner without orthogonal information from tandem MS or chromatography. However, for many lipidomics applications, it is necessary to know at least the lipid category or class that is associated with a detected spectral feature to derive a biochemical interpretation. Our goal is to develop a method for robustly classifying elemental molecular formula assignments into lipid categories for an application to SMIRFE-generated assignments. Using a Random Forest machine learning approach, we developed a method that can predict lipid category and class from SMIRFE non-adducted molecular formula assignments. Our methods achieve high average predictive accuracy (>90%) and precision (>83%) across all eight of the lipid categories in the LIPIDMAPS database. Classification performance was evaluated using sets of theoretical, data-derived, and artifactual molecular formulas. Our methods enable the lipid classification of non-adducted molecular formula assignments generated by SMIRFE without orthogonal information, facilitating the biochemical interpretation of untargeted lipidomics experiments. This lipid classification appears insufficient for validating single-spectrum assignments, but could be useful in cross-spectrum assignment validation.

Lipidome-based rapid diagnosis with machine learning for detection of TGF-β signalling activated area in head and neck cancer

Background

Several pro-oncogenic signals, including transforming growth factor beta (TGF-β) signalling from tumour microenvironment, generate intratumoural phenotypic heterogeneity and result in tumour progression and treatment failure. However, the precise diagnosis for tumour areas containing subclones with cytokine-induced malignant properties remains clinically challenging.

Methods

We established a rapid diagnostic system based on the combination of probe electrospray ionisation-mass spectrometry (PESI-MS) and machine learning without the aid of immunohistological and biochemical procedures to identify tumour areas with heterogeneous TGF-β signalling status in head and neck squamous cell carcinoma (HNSCC). A total of 240 and 90 mass spectra were obtained from TGF-β-unstimulated and -stimulated HNSCC cells, respectively, by PESI-MS and were used for the construction of a diagnostic system based on lipidome.

Results

This discriminant algorithm achieved 98.79% accuracy in discrimination of TGF-β1-stimulated cells from untreated cells. In clinical human HNSCC tissues, this approach achieved determination of tumour areas with activated TGF-β signalling as efficiently as a conventional histopathological assessment using phosphorylated-SMAD2 staining. Furthermore, several altered peaks on mass spectra were identified as phosphatidylcholine species in TGF-β-stimulated HNSCC cells.

Conclusions

This diagnostic system combined with PESI-MS and machine learning encourages us to clinically diagnose intratumoural phenotypic heterogeneity induced by TGF-β.

Identification of a Glass Substrate to Study Cells Using Fourier Transform Infrared Spectroscopy: Are We Closer to Spectral Pathology?

The rising incidence of cancer worldwide is causing an increase in the workload in pathology departments. This, coupled with advanced analysis methodologies, supports a developing need for techniques that could identify the presence of cancer cells in cytology and tissue samples in an objective, fast, and automated way. Fourier transform infrared (FT-IR) microspectroscopy can identify cancer cells in such samples objectively. Thus, it has the potential to become another tool to help pathologists in their daily work. However, one of the main drawbacks is the use of glass substrates by pathologists. Glass absorbs IR radiation, removing important mid-IR spectral data in the fingerprint region (1800 cm^-1 to 900 cm^-1). In this work, we hypothesized that, using glass coverslips of differing compositions, some regions within the fingerprint area could still be analyzed. We studied three different types of cells (peripheral blood mononuclear cells, a leukemia cell line, and a lung cancer cell line) and lymph node tissue placed on four different types of glass coverslips. The data presented here show that depending of the type of glass substrate used, information within the fingerprint region down to 1350 cm^-1 can be obtained. Furthermore, using principal component analysis, separation between the different cell lines was possible using both the lipid region and the fingerprint region between 1800 cm^-1 and 1350 cm^-1. This work represents a further step towards the application of FT-IR microspectroscopy in histopathology departments.

Oxidative Stress, Nutrition and Cancer: Friends or Foes?

The relationship between cancer and nutrition, as well as nutrition and oxidative stress, shares puzzling aspects that current research is investigating as the possible components of an intriguing regulating mechanism involving the complex interplay between adipose tissue and other compartments. Along the very recent biological evolution, humans underwent a rapid change in their lifestyles and henceforth the role of the adipocytes earned a much more complex task in the fine tuning of the tissue microenvironment. A lipidic signaling language probably evolved in association with the signaling role of reactive oxygen species, which gained a fundamental part in the regulation of cell stem and plasticity. The possible relationship with cancer onset might have some causative mechanism in the impairment of this complex task, usually deregulated by drastic changes in one's own lifestyle and dietary habit. This review tries to address this issue.

Sterculic Acid: The Mechanisms of Action beyond Stearoyl-CoA Desaturase Inhibition and Therapeutic Opportunities in Human Diseases

In many tissues, stearoyl-CoA desaturase 1 (SCD1) catalyzes the biosynthesis of monounsaturated fatty acids (MUFAS), (i.e., palmitoleate and oleate) from their saturated fatty acid (SFA) precursors (i.e., palmitate and stearate), influencing cellular membrane physiology and signaling, leading to broad effects on human physiology. In addition to its predominant role in lipid metabolism and body weight control, SCD1 has emerged recently as a potential new target for the treatment for various diseases, such as nonalcoholic steatohepatitis, Alzheimer’s disease, cancer, and skin disorders. Sterculic acid (SA) is a cyclopropene fatty acid originally found in the seeds of the plant Sterculia foetida with numerous biological activities. On the one hand, its ability to inhibit stearoyl-CoA desaturase (SCD) allows its use as a coadjuvant of several pathologies where this enzyme has been associated. On the other hand, additional effects independently of its SCD inhibitory properties, involve anti-inflammatory and protective roles in retinal diseases such as age-related macular degeneration (AMD). This review aims to summarize the mechanisms by which SA exerts its actions and to highlight the emerging areas where this natural compound may be of help for the development of new therapies for human diseases.

Mass spectrometry imaging to detect lipid biomarkers and disease signatures in cancer

BACKGROUND

Current methods to identify, classify, and predict tumor behavior mostly rely on histology, immunohistochemistry, and molecular determinants. However, better predictive markers are required for tumor diagnosis and evaluation. Due, in part, to recent technological advancements, metabolomics and lipid biomarkers have become a promising area in cancer research. Therefore, there is a necessity for novel and complementary techniques to identify and visualize these molecular markers within tumors and surrounding tissue.

RECENT FINDINGS

Since its introduction, mass spectrometry imaging (MSI) has proven to be a powerful tool for mapping analytes in biological tissues. By adding the label-free specificity of mass spectrometry to the detailed spatial information of traditional histology, hundreds of lipids can be imaged simultaneously within a tumor. MSI provides highly detailed lipid maps for comparing intra-tumor, tumor margin, and healthy regions to identify biomarkers, patterns of disease, and potential therapeutic targets. In this manuscript, recent advancement in sample preparation and MSI technologies are discussed with special emphasis on cancer lipid research to identify tumor biomarkers.

CONCLUSION

MSI offers a unique approach for biomolecular characterization of tumor tissues and provides valuable complementary information to histology for lipid biomarker discovery and tumor classification in clinical and research cancer applications.

Hypoxia Downregulates LPP3 and Promotes the Spatial Segregation of ATX and LPP1 During Cancer Cell Invasion

Hypoxia is a common characteristic of advanced solid tumors and a potent driver of tumor invasion and metastasis. Recent evidence suggests the involvement of autotaxin (ATX) and lysophosphatidic acid receptors (LPARs) in cancer cell invasion promoted by the hypoxic tumor microenvironment; however, the transcriptional and/or spatiotemporal control of this process remain unexplored. Herein, we investigated whether hypoxia promotes cell invasion by affecting the main enzymes involved in its production (ATX) and degradation (lipid phosphate phosphatases, LPP1 and LPP3). We report that hypoxia not only modulates the expression levels of lysophosphatidic acid (LPA) regulatory enzymes but also induces their significant spatial segregation in a variety of cancers. While LPP3 expression was downregulated by hypoxia, ATX and LPP1 were asymmetrically redistributed to the leading edge and to the trailing edge, respectively. This was associated with the opposing roles of ATX and LPPs in cell invasion. The regulated expression and compartmentalization of these enzymes of opposing function can provide an effective way to control the generation of an LPA gradient that drives cellular invasion and migration in the hypoxic zones of tumors.

Comparative Proteome Analysis of Breast Cancer Tissues Highlights the Importance of Glycerol-3-phosphate Dehydrogenase 1 and Monoacylglycerol Lipase in Breast Cancer Metabolism

BACKGROUND/AIM

Breast cancer (BC) incidence and mortality rates have been increasing due to the lack of appropriate diagnostic tools for early detection. Proteomics-based studies may provide novel targets for early diagnosis and efficient treatment. The aim of this study was to investigate the global changes occurring in protein profiles in breast cancer tissues to discover potential diagnostic or prognostic biomarkers.

MATERIALS AND METHODS

BC tissues and their corresponding healthy counterparts were collected, subtyped, and subjected to comparative proteomics analyses using two-dimensional gel electrophoresis (2-DE) and two-dimensional electrophoresis fluorescence difference gel (DIGE) coupled to matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF/TOF) to explore BC metabolism at the proteome level. Western blot analysis was used to verify changes occurring at the protein levels.

RESULTS

Bioinformatics analyses performed with differentially regulated proteins highlighted the changes occurring in triacylglyceride (TAG) metabolism, and directed our attention to TAG metabolism-associated proteins, namely glycerol-3-phosphate dehydrogenase 1 (GPD1) and monoacylglycerol lipase (MAGL). These proteins were down-regulated in tumor groups in comparison to controls.

CONCLUSION

GPD1 and MAGL might be promising tissue-based protein biomarkers with a predictive potential for BC.

Immunity, Hypoxia, and Metabolism-the Ménage à Trois of Cancer: Implications for Immunotherapy

It is generally accepted that metabolism is able to shape the immune response. Only recently we are gaining awareness that the metabolic crosstalk between different tumor compartments strongly contributes to the harsh tumor microenvironment (TME) and ultimately impairs immune cell fitness and effector functions. The major aims of this review are to provide an overview on the immune system in cancer; to position oxygen shortage and metabolic competition as the ground of a restrictive TME and as important players in the anti-tumor immune response; to define how immunotherapies affect hypoxia/oxygen delivery and the metabolic landscape of the tumor; and vice versa, how oxygen and metabolites within the TME impinge on the success of immunotherapies. By analyzing preclinical and clinical endeavors, we will discuss how a metabolic characterization of the TME can identify novel targets and signatures that could be exploited in combination with standard immunotherapies and can help to predict the benefit of new and traditional immunotherapeutic drugs.