LIPG-promoted lipid storage mediates adaptation to oxidative stress in breast cancer

Blocking H1R signal aggravates atherosclerosis by promoting inflammation and foam cell formation

Atherosclerosis (AS) is a chronic inflammatory arterial disease, in which abnormal lipid metabolism and foam cell formation play key roles. Histamine is a vital biogenic amine catalyzed by histidine decarboxylase (HDC) from L-histidine. Histamine H1 receptor (H1R) antagonist is a commonly encountered anti-allergic agent in the clinic. However, the role and mechanism of H1R in atherosclerosis have not been fully elucidated. Here, we explored the effect of H1R on atherosclerosis using Apolipoprotein E-knockout (ApoE-/-) mice with astemizole (AST, a long-acting H1R antagonist) treatment. The results showed that AST increased atherosclerotic plaque area and hepatic lipid accumulation in mice. The result of microarray study identified a significant change of endothelial lipase (LIPG) in CD11b+ myeloid cells derived from HDC-knockout (HDC-/-) mice compared to WT mice. Blocking H1R promoted the formation of foam cells from bone marrow-derived macrophages (BMDMs) of mice by up-regulating p38 mitogen-activated protein kinase (p38 MAPK) and LIPG signaling pathway. Taken together, these findings demonstrate that blocking H1R signal aggravates atherosclerosis by promoting abnormal lipid metabolism and macrophage-derived foam cell formation via p38 MAPK-LIPG signaling pathway. KEY MESSAGES: Blocking H1R signal with AST aggravated atherosclerosis and increased hepatic lipid accumulation in high-fat diet (HFD)-fed ApoE-/- mice. Blocking H1R signal promoted macrophage-derived foam cell formation via p38 MAPK-LIPG signaling pathway.

Role of Perilipins in Oxidative Stress-Implications for Cardiovascular Disease

Oxidative stress is the imbalance between the production of reactive oxygen species (ROS) and antioxidants in a cell. In the heart, oxidative stress may deteriorate calcium handling, cause arrhythmia, and enhance maladaptive cardiac remodeling by the induction of hypertrophic and apoptotic signaling pathways. Consequently, dysregulated ROS production and oxidative stress have been implicated in numerous cardiac diseases, including heart failure, cardiac ischemia-reperfusion injury, cardiac hypertrophy, and diabetic cardiomyopathy. Lipid droplets (LDs) are conserved intracellular organelles that enable the safe and stable storage of neutral lipids within the cytosol. LDs are coated with proteins, perilipins (Plins) being one of the most abundant. In this review, we will discuss the interplay between oxidative stress and Plins. Indeed, LDs and Plins are increasingly being recognized for playing a critical role beyond energy metabolism and lipid handling. Numerous reports suggest that an essential purpose of LD biogenesis is to alleviate cellular stress, such as oxidative stress. Given the yet unmet suitability of ROS as targets for the intervention of cardiovascular disease, the endogenous antioxidant capacity of Plins may be beneficial.

Increased Expression of LIPC Is Associated With the Clinicopathological Features and Development of Head and Neck Squamous Cell Carcinoma

Introduction Lipase C hepatic type (LIPC) is a member of the lipase family and plays a role in tumor development. However, its specific role in head and neck squamous cell carcinoma (HNSCC) is not well understood. Objective This study aims to investigate LIPC gene expression in HNSCC and elucidate its potential role in the context of the disease. Methods LIPC expression was analyzed using the Cancer Genome Atlas-HNSCC (TCGA-HNSCC) dataset. Real-time polymerase chain reaction (qPCR) was used to validate LIPC expression in oral squamous cell carcinoma (OSCC) tissue samples, which is the most common type of HNSCC. The LIPC was assessed to find out if there is a link with HNSCC clinicopathological features, prognosis, and tumor infiltration. Functional pathways associated with the LIPC network were also examined. Results LIPC expression was found to be elevated in both HNSCC and OSCC tissues. The heightened expression of LIPC correlated with various clinicopathological features and influenced the prognosis of HNSCC patients. The LIPC gene demonstrated connections with several oncogenic genes and proteins, participating in lipid catabolic processes and other pathways. These findings suggest that LIPC expression may play a role in the pathogenesis of HNSCC. Conclusion Our study affirms that LIPC expression is linked to the development of HNSCC, suggesting its potential utility as a biomarker or therapeutic target for the disease. However, further functional studies are imperative to validate and expand upon these findings.

Mechanistic analysis of endothelial lipase G promotion of the occurrence and development of cervical carcinoma by activating the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B/mechanistic target of rapamycin kinase signalling pathway

Lipase G, endothelial type (LIPG) is expressed abundantly in tissues with a high metabolic rate and vascularisation. Research on LIPG has focussed on metabolic syndromes. However, the role of LIPG in providing lipid precursors suggests that it might function in the metabolism of carcinoma cells. Analysis in The Cancer Genome Atlas indicated that patients with cervical carcinoma with high LIPG expression had a lower survival prognosis compared with patients with low LIPG expression. The mechanism underlying the effects of LIPG in cervical carcinoma is unclear. The present study aimed to determine the role of LIPG in cervical carcinoma and its mechanism. The results showed that the LIPG expression level was higher in cervical cancer. Downregulation of LIPG expression inhibited cell migration, invasion, proliferation, and the formation of cell colonies, but increased the rate of apoptosis. The Human papillomavirus E6 protein might reduce the expression of miR-148a-3p, relieve the inhibitory effect of miR-148a-3p on LIPG expression, and promote the progression of cervical cancer through the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B/mechanistic target of rapamycin kinase signalling pathway.IMPACT STATEMENTWhat is already known on this subject? LIPG provides lipid precursors, suggesting that it might function in the metabolism of carcinoma cellsWhat do the results of this study add? LIPG might be regulated by HPV16 E6/miR-148a-3p and promote cervical carcinoma progression via the PI3K/AKT/mTOR signalling pathway.What are the implications of these finding for clinical practice and/or further research? The results indicated that novel treatment and diagnosis strategies for cervical carcinoma could be developed related to LIPG. However, the detailed relationship between LIPG and cervical carcinoma remains to be fully determined.

Deletion of NRF2 disturbs composition, morphology, and differentiation of the murine tail epidermis in chronological aging

NRF2 is a master regulator of the cellular protection against oxidative damage in mammals and of multiple pathways relevant in the mammalian aging process. In the epidermis of the skin NRF2 contributes additionally to the formation of an antioxidant barrier to protect from environmental insults and is involved in the differentiation process of keratinocytes. In chronological aging of skin, the capacity for antioxidant responses and the ability to restore homeostasis after damage are impaired. Surprisingly, in absence of extrinsic stressors, NRF2 deficient mice do not show any obvious skin phenotype, not even at old age. We investigated the differences in chronological epidermal aging of wild type and NRF2-deficient mice to identify the changes in aged epidermis that may compensate for absence of this important transcriptional regulator. While both genotypes showed elevated epidermal senescence markers (increased Lysophospholipids, decreased LaminB1 expression), the aged NRF2 deficient mice displayed disturbed epidermal differentiation manifested in irregular keratin 10 and loricrin expression. The tail skin displayed less age-related epidermal thinning and a less pronounced decline in proliferating basal epidermal cells compared to the wildtype controls. The stratum corneum lipid composition also differed, as we observed elevated production of barrier protective linoleic acid (C18:2) and reduced abundance of longer chain saturated lignoceric acid (C24:0) among the stratum corneum fatty acids in the aged NRF2-deficient mice. Thus, despite epidermal differentiation being disturbed in aged NRF2-deficient animals in homeostasis, adaptations in keratinocyte proliferation and barrier lipid synthesis could explain the lack of a more severe phenotype.

Effective breast cancer therapy based on palmitic acid-loaded PLGA nanoparticles

Although new strategies for breast cancer treatment have yielded promising results, most drugs can lead to serious side effects when applied systemically. Doxorubicin (DOX), currently the most effective chemotherapeutic drug to treat breast cancer, is poorly selective towards tumor cells and treatment often leads to the development of drug resistance. Recent studies have indicated that several fatty acids (FAs) have beneficial effects on inhibiting tumorigenesis. The saturated FA palmitic acid (PA) showed anti-tumor activities in several types of cancer, as well as effective repolarization of M2 macrophages towards the anti-tumorigenic M1 phenotype. However, water insolubility and cellular impermeability limit the use of PA in vivo. To overcome these limitations, here, we encapsulated PA into a poly(d,l-lactic co-glycolic acid) (PLGA) nanoparticle (NP) platform, alone and in combination with DOX, to explore PA's potential as mono or combinational breast cancer therapy. Our results showed that PLGA-PA-DOX NPs and PLGA-PA NPs significantly reduced the viability and migratory capacity of breast cancer cells in vitro. In vivo studies in mice bearing mammary tumors demonstrated that PLGA-PA-NPs were as effective in reducing primary tumor growth and metastasis as NPs loaded with DOX, PA and DOX, or free DOX. At the molecular level, PLGA-PA NPs reduced the expression of genes associated with multi-drug resistance and inhibition of apoptosis, and induced apoptosis via a caspase-3-independent pathway in breast cancer cells. In addition, immunohistochemical analysis of residual tumors showed a reduction in M2 macrophage content and infiltration of leukocytes after treatment of PLGA-PA NPs and PLGA-PA-DOX NPs, suggesting immunomodulatory properties of PA in the tumor microenvironment. In conclusion, the use of PA alone or in combination with DOX may represent a promising novel strategy for the treatment of breast cancer.

miR-3614-5p downregulation promotes cadmium-induced breast cancer cell proliferation and metastasis by targeting TXNRD1

Cadmium (Cd), which is considered an endocrine disruptor, has been linked to the onset of breast cancer (BC). Our recent study demonstrated that Cd-induced BC progression has a strong correlation with miR-374c-5p dysregulation. The aim of our work was to investigate other potential miRNAs involved in Cd-induced BC cell proliferation and metastasis. In our study, the miRNA profiles of Cd-treated T-47D cells (10 μM, 72 h) were analyzed by miRNA-seq, and our results confirmed that miR-3614-5p was the top downregulated miRNA. Moreover, miR-3614-5p mimic transfection significantly decreased the proliferative ability, migration and invasive ability of BC cell lines (T-47D and MCF-7). Furthermore, we analyzed the overlapping genes from our RNA-seq data and predicted targets from the mirDIP database, and twelve genes (ALDH1A3, FBN1, GRIA3, NOS1, PLD5, PTGER4, RASGRF2, RELN, RNF150, SLC17A4, TG, and TXNRD1) were identified as potential binding targets of miR-3614-5p in the current model. Nonetheless, only miR-3614-5p inhibition caused an increase in TXNRD1 expression upon Cd exposure in T-47D and MCF-7 cell lines. Importantly, luciferase reporter assays further verified that miR-3614-5p suppressed the expression of TXNRD1 by directly binding to the 3'-untranslated region (UTR), and TXNRD1 inhibition significantly repressed the proliferation and metastasis capacity of BC cells upon Cd exposure. Together, our findings demonstrated that Cd exposure repressed the expression of miR-3614-5p, thus activating TXNRD1 expression, which promoted the abnormal proliferation and metastasis of BC cells.

A Proof-of-Concept Inhibitor of Endothelial Lipase Suppresses Triple-Negative Breast Cancer Cells by Hijacking the Mitochondrial Function

Simple Summary

Endothelial lipase (EL/LIPG) is a key regulator of tumor cell metabolism. In triple-negative breast cancer (TNBC) cells, we find that the expression of LIPG is associated with long non-coding RNA DANCR and positively correlates with gene signatures of mitochondrial metabolism-oxidative phosphorylation (OXPHOS). DANCR binds to LIPG, which enables tumor cells to maintain the expression. Importantly, LIPG knockdown inhibits OXPHOS and TNBC tumor formation. Finally, our study identifies a natural compound, the LIPG inhibitor cynaroside, which provides a new therapeutic strategy against TNBC.

Abstract

Triple-negative breast cancer (TNBC) cells reprogram their metabolism to provide metabolic flexibility for tumor cell growth and survival in the tumor microenvironment. While our previous findings indicated that endothelial lipase (EL/LIPG) is a hallmark of TNBC, the precise mechanism through which LIPG instigates TNBC metabolism remains undefined. Here, we report that the expression of LIPG is associated with long non-coding RNA DANCR and positively correlates with gene signatures of mitochondrial metabolism-oxidative phosphorylation (OXPHOS). DANCR binds to LIPG, enabling tumor cells to maintain LIPG protein stability and OXPHOS. As one mechanism of LIPG in the regulation of tumor cell oxidative metabolism, LIPG mediates histone deacetylase 6 (HDAC6) and histone acetylation, which contribute to changes in IL-6 and fatty acid synthesis gene expression. Finally, aided by a relaxed docking approach, we discovered a new LIPG inhibitor, cynaroside, that effectively suppressed the enzyme activity and DANCR in TNBC cells. Treatment with cynaroside inhibited the OXPHOS phenotype of TNBC cells, which severely impaired tumor formation. Taken together, our study provides mechanistic insights into the LIPG modulation of mitochondrial metabolism in TNBC and a proof-of-concept that targeting LIPG is a promising new therapeutic strategy for the treatment of TNBC.

Identification of early biomarkers in saliva in genetically engineered mouse model C(3)1-TAg of breast cancer

Breast cancer is one of leading causes of death worldwide in the female population. Deaths from breast cancer could be reduced significantly through earlier and more efficient detection of the disease. Saliva, an oral fluid that contains an abundance of protein biomarkers, has been recognized as a promising diagnostic biofluid that is easy to isolate through non-invasive techniques. Assays on saliva can be performed rapidly and are cost-effective. Therefore, our work aimed to identify salivary biomarkers present in the initial stages of breast cancer, where cell alterations are not yet detectable by histopathological analysis. Using state-of-the-art techniques, we employed a transgenic mouse model of mammary cancer to identify molecular changes in precancerous stage breast cancer through protein analysis in saliva. Through corroborative molecular approaches, we established that proteins related to metabolic changes, inflammatory process and cell matrix degradation are detected in saliva at the onset of tumor development. Our work demonstrated that salivary protein profiles can be used to identify cellular changes associated with precancerous stage breast cancer through non-invasive means even prior to biopsy-evident disease.

Multifunctional Role of Lipids in Modulating the Tumorigenic Properties of 4T1 Breast Cancer Cells

Tumor growth and progression are linked to an altered lipid metabolism in the tumor microenvironment (TME), including tumor cells and tumor-associated macrophages (TAMs). A growing number of lipid metabolism targeting drugs have shown efficacy in anti-tumor therapy. In addition, exogenously applied lipids and lipid analogues have demonstrated anti-tumor activities in several cancers, including breast cancer. In this study, we investigated the anti-tumor efficacies of the natural lipids palmitic acid (PA), sphingomyelin (SM), ceramide (Cer) and docosahexaenoic acid (DHA) on breast cancer cells. All tested lipids reduced the malignancy of breast cancer cells in vitro by impairing cell proliferation, migration and invasiveness. PA showed superior anti-tumor properties, as it additionally impaired cancer cell viability by inducing apoptosis, without affecting healthy cells. Co-culture experiments further demonstrated that Cer and PA reduced the immunosuppressive phenotype of M2 macrophages and the M2 macrophage-promoted the epithelial–mesenchymal transition (EMT) and migration of breast cancer cells. At the molecular level, this coincided with the up-regulation of E-cadherin. Our results highlight a powerful role for exogenously applied PA and Cer in reducing breast cancer tumorigenicity by simultaneously targeting cancer cells and M2 macrophages. Our findings support the notion that lipids represent alternative biocompatible therapeutic agents for breast cancer.

Genome-wide expression reveals potential biomarkers in breast cancer bone metastasis

Breast cancer metastases are most commonly found in bone, an indication of poor prognosis. Pathway-based biomarkers identification may help elucidate the cellular signature of breast cancer metastasis in bone, further characterizing the etiology and promoting new therapeutic approaches. We extracted gene expression profiles from mouse macrophages from the GEO dataset, GSE152795 using the GEO2R webtool. The differentially expressed genes (DEGs) were filtered by log2 fold-change with threshold 1.5 (FDR < 0.05). STRING database and Enrichr were used for GO-term analysis, miRNA and TF analysis associated with DEGs. Autodock Vienna was exploited to investigate interaction of anti-cancer drugs, Actinomycin-D and Adriamycin. Sensitivity and specificity of DEGs was assessed using receiver operating characteristic (ROC) analyses. A total of 61 DEGs, included 27 down-regulated and 34 up-regulated, were found to be significant in breast cancer bone metastasis. Major DEGs were associated with lipid metabolism and immunological response of tumor tissue. Crucial DEGs, Bcl3, ADGRG7, FABP4, VCAN, and IRF4 were regulated by miRNAs, miR-497, miR-574, miR-138 and TFs, CCDN1, STAT6, IRF8. Docking analysis showed that these genes possessed strong binding with the drugs. ROC analysis demonstrated Bcl3 is specific to metastasis. DEGs Bcl3, ADGRG7, FABP4, IRF4, their regulating miRNAs and TFs have strong impact on proliferation and metastasis of breast cancer in bone tissues. In conclusion, present study revealed that DEGs are directly involved in of breast tumor metastasis in bone tissues. Identified genes, miRNAs, and TFs can be possible drug targets that may be used for the therapeutics. However, further experimental validation is necessary.

Identification of potential functional variants and genes at 18q21.1 associated with the carcinogenesis of colorectal cancer

Genome-wide association studies (GWAS) have identified more than 160 susceptibility loci for colorectal cancer (CRC). The effects of these variants, particularly their mechanisms, however, remain unclear. In this study, a comprehensive functional annotation of CRC-related GWAS signals was firstly conducted to identify the potential causal variants. We found that the SNP rs7229639 in intron 3 of SMAD7 at 18q21.1 might serve as a putative functional variant in CRC. The SNP rs7229639 is located in a region with evidence of regulatory potential. Dual-luciferase reporter assays revealed that three other SNPs (rs77544449, rs60385309 and rs72917785), in strong linkage disequilibrium (LD) with rs7229639, exhibited allele-specific enhancer activity, of which one of the target genes may conceivably be LIPG, as suggested by eQTL association data and Hi-C data. We also verified that LIPG promoted malignancy of CRC cells in vitro, with supporting clinical data indicating that LIPG is upregulated and correlated with a poor prognosis in CRC. Finally, pitavastatin was observed to exhibit an anti-CRC activity and modest inhibition of LIPG mRNA levels. Collectively, our data suggest that these functional variants at 18q21.1 are involved in the pathogenesis of CRC by modulating enhancer activity, and possibly LIPG expression, thus indicating a promising therapeutic target for CRC. The results of functional annotation in our investigation could also serve as an inventory for CRC susceptibility SNPs and offer guides for post-GWAS downstream functional studies.

In the latest statistics, the incidence and mortality rate of colorectal cancer (CRC) remains high. Genome-wide association studies (GWAS) have become a powerful tool for identifying genetic susceptibility loci that confer significant risk on disease, and have identified more than 160 risk loci associated with CRC. However, it has proven quite difficult to identify the regulatory variants and target genes involved behind these GWAS signals. Here, we take advantage of multi-omics data and multiple biological experiments to reveal new biological pathways affecting susceptibility to CRC. We show that a specific genetic variant, rs7229639, and three other high linked functional variants (rs77544449, rs60385309 and rs72917785) at 18q21.1 might regulate the expression of LIPG, a gene that was shown to exhibit an oncogenic function by our in-vitro experiments and clinical data analysis. The link between genetic variants, gene expression and CRC phenotype established by us could provide references for follow-up basic and clinical studies.

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

Reactive oxygen species (ROS) play a dual role in the initiation, development, suppression, and treatment of cancer. Excess ROS can induce nuclear DNA, leading to cancer initiation. Not only that, but ROS also inhibit T cells and natural killer cells and promote the recruitment and M2 polarization of macrophages; consequently, cancer cells escape immune surveillance and immune defense. Furthermore, ROS promote tumor invasion and metastasis by triggering epithelial-mesenchymal transition in tumor cells. Interestingly, massive accumulation of ROS inhibits tumor growth in two ways: (1) by blocking cancer cell proliferation by suppressing the proliferation signaling pathway, cell cycle, and the biosynthesis of nucleotides and ATP and (2) by inducing cancer cell death via activating endoplasmic reticulum stress-, mitochondrial-, and P53- apoptotic pathways and the ferroptosis pathway. Unfortunately, cancer cells can adapt to ROS via a self-adaption system. This review highlighted the bidirectional regulation of ROS in cancer. The study further discussed the application of massively accumulated ROS in cancer treatment. Of note, the dual role of ROS in cancer and the self-adaptive ability of cancer cells should be taken into consideration for cancer prevention.

LIPG endothelial lipase and breast cancer risk by subtypes

Experimental data showed that endothelial lipase (LIPG) is a crucial player in breast cancer. However, very limited data exists on the role of LIPG on the risk of breast cancer in humans. We examined the LIPG-breast cancer association within our population-based case-control study from Galicia, Spain, BREOGAN (BREast Oncology GAlicia Network). Plasma LIPG and/or OxLDL were measured on 114 breast cancer cases and 82 controls from our case-control study, and were included in the present study. The risk of breast cancer increased with increasing levels of LIPG (multivariable OR for the highest category (95% CI) 2.52 (1.11-5.81), P-trend = 0.037). The LIPG-breast cancer association was restricted to Pre-menopausal breast cancer (Multivariable OR for the highest LIPG category (95% CI) 4.76 (0.94-28.77), P-trend = 0.06, and 1.79 (0.61-5.29), P-trend = 0.372, for Pre-menopausal and Post-menopausal breast cancer, respectively). The LIPG-breast cancer association was restricted to Luminal A breast cancers (Multivariable OR for the highest LIPG category (95% CI) 3.70 (1.42-10.16), P-trend = 0.015, and 2.05 (0.63-7.22), P-trend = 0.311, for Luminal A and non-Luminal A breast cancers, respectively). Subset analysis only based on HER2 receptor indicated that the LIPG-breast cancer relationship was restricted to HER2-negative breast cancers (Multivariable OR for the highest LIPG category (95% CI) 4.39 (1.70-12.03), P-trend = 0.012, and 1.10 (0.28-4.32), P-trend = 0.745, for HER2-negative and HER2-positive tumors, respectively). The LIPG-breast cancer association was restricted to women with high total cholesterol levels (Multivariable OR for the highest LIPG category (95% CI) 6.30 (2.13-20.05), P-trend = 0.018, and 0.65 (0.11-3.28), P-trend = 0.786, among women with high and low cholesterol levels, respectively). The LIPG-breast cancer association was also restricted to non-postpartum breast cancer (Multivariable OR for the highest LIPG category (95% CI) 3.83 (1.37-11.39), P-trend = 0.003, and 2.35 (0.16-63.65), P-trend = 0.396, for non-postpartum and postpartum breast cancer, respectively), although we lacked precision. The LIPG-breast cancer association was more pronounced among grades II and III than grade I breast cancers (Multivariable ORs for the highest category of LIPG (95% CI) 2.73 (1.02-7.69), P-trend = 0.057, and 1.90 (0.61-6.21), P-trend = 0.170, for grades II and III, and grade I breast cancers, respectively). No association was detected for OxLDL levels and breast cancer (Multivariable OR for the highest versus the lowest category (95% CI) 1.56 (0.56-4.32), P-trend = 0.457).

Endothelial Lipase Is Involved in Cold-Induced High-Density Lipoprotein Turnover and Reverse Cholesterol Transport in Mice

The physiologic activation of thermogenic brown and white adipose tissues (BAT/WAT) by cold exposure triggers heat production by adaptive thermogenesis, a process known to ameliorate hyperlipidemia and protect from atherosclerosis. Mechanistically, it has been shown that thermogenic activation increases lipoprotein lipase (LPL)-dependent hydrolysis of triglyceride-rich lipoproteins (TRL) and accelerates the generation of cholesterol-enriched remnants and high-density lipoprotein (HDL), which promotes cholesterol flux from the periphery to the liver. HDL is also subjected to hydrolysis by endothelial lipase (EL) (encoded by LIPG). Genome-wide association studies have identified various variants of EL that are associated with altered HDL cholesterol levels. However, a potential role of EL in BAT-mediated HDL metabolism has not been investigated so far. In the present study, we show that in mice, cold-stimulated activation of thermogenic adipocytes induced expression of Lipg in BAT and inguinal WAT but that loss of Lipg did not affect gene expression of thermogenic markers. Furthermore, in both wild type (WT) and Lipg-deficient mice, activation of thermogenesis resulted in a decline of HDL cholesterol levels. However, cold-induced remodeling of the HDL lipid composition was different between WT and Lipg-deficient mice. Notably, radioactive tracer studies with double-labeled HDL indicated that cold-induced hepatic HDL cholesterol clearance was lower in Lipg-deficient mice. Moreover, this reduced clearance was associated with impaired macrophage-to-feces cholesterol transport. Overall, these data indicate that EL is a determinant of HDL lipid composition, cholesterol flux, and HDL turnover in conditions of high thermogenic activity.

Ultrastructural Analysis of Inflammatory Breast Cancer Cell Clusters in an Ex Vivo Environment Mechanically Mimicking the Lymph Vascular System

Background:

Inflammatory breast cancer (IBC) is a rare form of breast cancer with a poor prognosis. IBC is characterized by florid lymphovascular tumor emboli in the skin and the parenchyma of the breast. We hypothesized that the formation of these emboli/clusters plays a pivotal role in IBC metastasis and its rapid progression, and that their structure and function may be a key to identifying molecular biological differences between IBC and non IBC.

Methods:

Mechanical methods were used to mimic the lymph fluid viscosity by adding 2.25% of PEG8000 to the media. Clusters were obtained for IBC tumor cell lines (SUM149 and IBC-3), non IBC tumor cell lines (MDA-MB-231, MDA-MB-468, and MCF7), and a non-tumorigenic human mammary epithelial cell line (MCF10A). Clusters were analyzed by light microscopy, and then prepared for and observed by transmission electron microscopy (TEM).

Results:

Significant differences were seen between IBC and non IBC clusters. The TEM analysis revealed that IBC cells harbored numerous microvilli and microvesicles, both on the free outer surface and inside the cluster. Microvilli from IBC cell clusters were noted at higher density and were longer than those of non IBC cell clusters.

Conclusions:

IBC tumor cell clusters exhibited distinct ultrastructural features characterized by the presence of long, crowded microvilli and numerous microvesicles. These microvilli may play an important role in the biology and aggressiveness of IBC.

The Hepatic Microenvironment Uniquely Protects Leukemia Cells through Induction of Growth and Survival Pathways Mediated by LIPG

Due to the disseminated nature of leukemia, malignant cells are exposed to many different tissue microenvironments, including a variety of extramedullary sites. In the present study, we demonstrate that leukemic cells residing in the liver display unique biological properties and also contribute to systemic changes that influence physiologic responses to chemotherapy. Specifically, the liver microenvironment induces metabolic adaptations via upregulating expression of endothelial lipase in leukemia cells, which not only stimulates tumor cell proliferation through polyunsaturated fatty acid-mediated pathways, but also promotes survival by stabilizing antiapoptotic proteins. Additionally, hepatic infiltration and tissue damage caused by malignant cells induces release of liver-derived enzymes capable of degrading chemotherapy drugs, an event that further protects leukemia cells from conventional therapies. Together, these studies demonstrate a unique role for liver in modulating the pathogenesis of leukemic disease and suggest that the hepatic microenvironment may protect leukemia cells from chemotherapeutic challenge. SIGNIFICANCE: The studies presented herein demonstrate that the liver provides a microenvironment in which leukemia cells acquire unique metabolic properties. The adaptations that occur in the liver confer increased resistance to chemotherapy. Therefore, we propose that therapies designed to overcome liver-specific metabolic changes will yield improved outcomes for patients with leukemia.This article is highlighted in the In This Issue feature, p. 211.

LIPG: an inflammation and cancer modulator

Endothelial lipase (LIPG/EL) performs fundamental and vital roles in the human body, including cell composition, cytokine expression, and energy provision. Since LIPG predominantly functions as a phospholipase as well as presents low levels of triglyceride lipase activity, it plays an essential role in lipoprotein metabolism, and involves in the metabolic syndromes such as inflammatory response and atherosclerosis. Cytokines significantly affect LIPG expression in endothelial cells in many diseases. Recently, it is suggested that LIPG contributes to cancer initiation and progression, and LIPG attached increasing importance to its potential for future targeted therapy.

UVA Induced Oxidative Stress Was Inhibited by Paeoniflorin/Nrf2 Signaling or PLIN2

Photodamages caused by UVA radiation induced oxidative injuries are closely related to photoaging and skin cancer. Paeoniflorin (PF), extracted from the root of Paeonia lactiflora, has been reported to be an effective antioxidant. PLIN2, known as adipose differentiation-related protein, has been previously involved in the regulation of oxidative stress. In this study, we were sought to investigate the photo-protective property of PF and PLIN2 in UVA-radiated human dermal fibroblasts (HDFs). HDFs were pre-treated with PF (800 μM) followed by UVA radiation (22.5 J/cm2). MTS activity, cell apoptosis, ROS, MDA, and SOD were detected, respectively. The expressions of Nrf2, HO-1, NQ-O1, and PLIN2 were determined using RT-qPCR or western blot. Nrf2 was silenced by siRNA, and PLIN2 was overexpressed via lentiviral transduction. Comparing to the UVA radiation, PF pre-treatment could prominently increase the MTS activity, decrease cell apoptosis, reduce the generations of ROS and MDA, increase the activity of SOD and increase the expression of Nrf2 and its target genes HO-1 and NQ-O1. When Nrf2 was knocked down, PF lost above protective properties. In addition, UVA induced oxidative stress led to upregulation of PLIN2 and the latter could be decreased by PF. Overexpression of PLIN2 improved MTS activity and reduced MDA level in HDFs. The combination of PLIN2 overexpression and PF pre-treatment corporately inhibited UVA-induced injury. Besides, we also found that PF and PLIN2 had a compensatory protection against UVA induced oxidative stress. In conclusion, our study demonstrated that UVA induced photodamages could be inhibited by PF via Nrf2/HO-1/NQ-O1 signaling pathway or by PLIN2, and the combination of PLIN2 overexpression and PF played additive effects against UVA-related oxidative stress.