Stearoyl-CoA desaturase 1 and paracrine diffusible signals have a major role in the promotion of breast cancer cell migration induced by cancer-associated fibroblasts

Mechanisms of Abnormal Lipid Metabolism in the Pathogenesis of Disease

Lipid metabolism is a critical component in preserving homeostasis and health, and lipids are significant chemicals involved in energy metabolism in living things. With the growing interest in lipid metabolism in recent years, an increasing number of studies have demonstrated the close relationship between abnormalities in lipid metabolism and the development of numerous human diseases, including cancer, cardiovascular, neurological, and endocrine system diseases. Thus, understanding how aberrant lipid metabolism contributes to the development of related diseases and how it works offers a theoretical foundation for treating and preventing related human diseases as well as new avenues for the targeted treatment of related diseases. Therefore, we discuss the processes of aberrant lipid metabolism in various human diseases in this review, including diseases of the cardiovascular system, neurodegenerative diseases, endocrine system diseases (such as obesity and type 2 diabetes mellitus), and other diseases including cancer.

The lipid metabolism remodeling: A hurdle in breast cancer therapy

Lipids, as one of the three primary energy sources, provide energy for all cellular life activities. Lipids are also known to be involved in the formation of cell membranes and play an important role as signaling molecules in the intracellular and microenvironment. Tumor cells actively or passively remodel lipid metabolism, using the function of lipids in various important cellular life activities to evade therapeutic attack. Breast cancer has become the leading cause of cancer-related deaths in women, which is partly due to therapeutic resistance. It is necessary to fully elucidate the formation and mechanisms of chemoresistance to improve breast cancer patient survival rates. Altered lipid metabolism has been observed in breast cancer with therapeutic resistance, indicating that targeting lipid reprogramming is a promising anticancer strategy.

Circadian clock and lipid metabolism disorders: a potential therapeutic strategy for cancer

Recent research has emphasized the interaction between the circadian clock and lipid metabolism, particularly in relation to tumors. This review aims to explore how the circadian clock regulates lipid metabolism and its impact on carcinogenesis. Specifically, targeting key enzymes involved in fatty acid synthesis (SREBP, ACLY, ACC, FASN, and SCD) has been identified as a potential strategy for cancer therapy. By disrupting these enzymes, it may be possible to inhibit tumor growth by interfering with lipid metabolism. Transcription factors, like SREBP play a significant role in regulating fatty acid synthesis which is influenced by circadian clock genes such as BMAL1, REV-ERB and DEC. This suggests a strong connection between fatty acid synthesis and the circadian clock. Therefore, successful combination therapy should target fatty acid synthesis in addition to considering the timing and duration of drug use. Ultimately, personalized chronotherapy can enhance drug efficacy in cancer treatment and achieve treatment goals.

Unraveling the Cave: A Seventy-Year Journey into the Caveolar Network, Cellular Signaling, and Human Disease

In the mid-1950s, a groundbreaking discovery revealed the fascinating presence of caveolae, referred to as flask-shaped invaginations of the plasma membrane, sparking renewed excitement in the field of cell biology. Caveolae are small, flask-shaped invaginations in the cell membrane that play crucial roles in diverse cellular processes, including endocytosis, lipid homeostasis, and signal transduction. The structural stability and functionality of these specialized membrane microdomains are attributed to the coordinated activity of scaffolding proteins, including caveolins and cavins. While caveolae and caveolins have been long appreciated for their integral roles in cellular physiology, the accumulating scientific evidence throughout the years reaffirms their association with a broad spectrum of human disorders. This review article aims to offer a thorough account of the historical advancements in caveolae research, spanning from their initial discovery to the recognition of caveolin family proteins and their intricate contributions to cellular functions. Furthermore, it will examine the consequences of a dysfunctional caveolar network in the development of human diseases.

Correlation of Plasma Membrane Microviscosity and Cell Stiffness Revealed via Fluorescence-Lifetime Imaging and Atomic Force Microscopy

The biophysical properties of cells described at the level of whole cells or their membranes have many consequences for their biological behavior. However, our understanding of the relationships between mechanical parameters at the level of cell (stiffness, viscoelasticity) and at the level of the plasma membrane (fluidity) remains quite limited, especially in the context of pathologies, such as cancer. Here, we investigated the correlations between cells' stiffness and viscoelastic parameters, mainly determined via the actin cortex, and plasma membrane microviscosity, mainly determined via its lipid profile, in cancer cells, as these are the keys to their migratory capacity. The mechanical properties of cells were assessed using atomic force microscopy (AFM). The microviscosity of membranes was visualized using fluorescence-lifetime imaging microscopy (FLIM) with the viscosity-sensitive probe BODIPY 2. Measurements were performed for five human colorectal cancer cell lines that have different migratory activity (HT29, Caco-2, HCT116, SW 837, and SW 480) and their chemoresistant counterparts. The actin cytoskeleton and the membrane lipid composition were also analyzed to verify the results. The cell stiffness (Young's modulus), measured via AFM, correlated well (Pearson r = 0.93) with membrane microviscosity, measured via FLIM, and both metrics were elevated in more motile cells. The associations between stiffness and microviscosity were preserved upon acquisition of chemoresistance to one of two chemotherapeutic drugs. These data clearly indicate that mechanical parameters, determined by two different cellular structures, are interconnected in cells and play a role in their intrinsic migratory potential.

Unveiling the MUFA-Cancer Connection: Insights from Endogenous and Exogenous Perspectives

Monounsaturated fatty acids (MUFAs) have been the subject of extensive research in the field of cancer due to their potential role in its prevention and treatment. MUFAs can be consumed through the diet or endogenously biosynthesized. Stearoyl-CoA desaturases (SCDs) are key enzymes involved in the endogenous synthesis of MUFAs, and their expression and activity have been found to be increased in various types of cancer. In addition, diets rich in MUFAs have been associated with cancer risk in epidemiological studies for certain types of carcinomas. This review provides an overview of the state-of-the-art literature on the associations between MUFA metabolism and cancer development and progression from human, animal, and cellular studies. We discuss the impact of MUFAs on cancer development, including their effects on cancer cell growth, migration, survival, and cell signaling pathways, to provide new insights on the role of MUFAs in cancer biology.

Upregulation of SCD1 by ErbB2 via LDHA promotes breast cancer cell migration and invasion

The incidence of breast cancer ranks at the top of female malignant tumors in China. Metastasis remains the main cause of death among breast cancer patients. The overexpression of ErbB2 is closely related to the metastasis and poor prognosis of breast cancer patients. Therefore, ErbB2 is an important clinical therapeutic target of breast cancer. However, the molecular mechanism of ErbB2 promoting breast cancer metastasis has not been studied clearly. Stearoyl-CoA desaturase 1 (SCD1) is a key enzyme in catalyzing the conversion of saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs). SCD1 is overexpressed in breast cancer, and its overexpression is an indicator of poor prognosis in breast cancer patients. However, the role of SCD1 in ErbB2-overexpressing breast cancer metastasis has not been reported. In this study, we investigated the role of SCD1 in the migration and invasion of ErbB2-overexpressing breast cancer cells and its molecular mechanism. First, we demonstrated that ErbB2 upregulates the expression of SCD1. Second, we found that SCD1 and its catalytic product oleic acid played crucial roles in migration and invasion of ErbB2-overexpressing breast cancer cells. Finally, we found that in breast cancer cells, ErbB2 upregulated SCD1 through lactate dehydrogenase A (LDHA). To sum up, upregulation of SCD1 by ErbB2 via LDHA promotes the migration and invasion of breast cancer cells.

A miR-34a-guided, tRNAiMet-derived, piR_019752-like fragment (tRiMetF31) suppresses migration and angiogenesis of breast cancer cells via targeting PFKFB3

Although we recently demonstrated that miR-34a directly targets tRNA_i^Met precursors via Argonaute 2 (AGO2)-mediated cleavage, consequently attenuating the proliferation of breast cancer cells, whether tRNA_i^Met fragments derived from this cleavage influence breast tumor angiogenesis remains unknown. Here, using small-RNA-Seq, we identified a tRNA_i^Met-derived, piR_019752-like 31-nt fragment tRiMetF31 in breast cancer cells expressing miR-34a. Bioinformatic analysis predicted 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) as a potential target of tRiMrtF31, which was validated by luciferase assay. tRiMetF31 was downregulated, whereas PFKFB3 was overexpressed in cancer cell lines. Overexpression of tRiMetF31 profoundly inhibited the migration and angiogenesis of two breast cancer cell lines while slightly inducing apoptosis. Conversely, knockdown of tRiMetF31 restored PFKFB3-driven angiogenesis. miR-34a was downregulated, whereas tRNA_i^Met and PFKFB3 were upregulated in breast cancer, and elevated PFKFB3 significantly correlated with metastasis. Our findings demonstrate that tRiMetF31 profoundly suppresses angiogenesis by silencing PFKFB3, presenting a novel target for therapeutic intervention in breast cancer.

The long non-coding RNA T cell leukemia homeobox 1 neighbor enhances signal transducer and activator of transcription 5A phosphorylation to promote colon cancer cell invasion, migration, and metastasis

Colon cancer is among the most prevalent gastrointestinal tumor types. The long noncoding RNA (lncRNA) T cell leukemia homeobox 1 neighbor (TLX1NB) is up-regulated in colorectal cancer (CRC). However, the functional role of this lncRNA in colon cancer remains unknown. In our study, we investigated the clinical significance of TLX1NB in colon cancer through bioinformatics analysis and explored its role in migration, invasion and metastasis of colon cancer cell with a series of experiments. Firstly, TLX1NB was up-regulated in colon cancer tissues and increased TLX1NB expression was significantly associated with advanced N stages. In wound healing assays and transwell assays, TLX1NB overexpression promoted HCT116 cell migration and invasion while TLX1NB knockdown inhibited SW620 cell migration and invasion. In vivo, TLX1NB knockdown suppressed pulmonary metastasis of SW620 cell and vimentin expression but increased E-cadherin expression. Then, TLX1NB overexpression enhanced signal transducer and activator of transcription 5A (STAT5A) phosphorylation and TLX1NB knockdown suppressed STAT5A phosphorylation. Moreover, the inhibition of STAT5A phosphorylation reversed TLX1NB overexpression-associated increase in HCT116 cell migratory and invasive activity. In conclusion, TLX1NB enhances STAT5A phosphorylation to promote colon cancer cell invasion, migration, and metastasis.

Abnormal lipid synthesis as a therapeutic target for cancer stem cells

Cancer stem cells (CSCs) comprise a subpopulation of cancer cells with stem cell properties, which exhibit the characteristics of high tumorigenicity, self-renewal, and tumor initiation and are associated with the occurrence, metastasis, therapy resistance, and relapse of cancer. Compared with differentiated cells, CSCs have unique metabolic characteristics, and metabolic reprogramming contributes to the self-renewal and maintenance of stem cells. It has been reported that CSCs are highly dependent on lipid metabolism to maintain stemness and satisfy the requirements of biosynthesis and energy metabolism. In this review, we demonstrate that lipid anabolism alterations promote the survival of CSCs, including de novo lipogenesis, lipid desaturation, and cholesterol synthesis. In addition, we also emphasize the molecular mechanism underlying the relationship between lipid synthesis and stem cell survival, the signal trans-duction pathways involved, and the application prospect of lipid synthesis reprogramming in CSC therapy. It is demonstrated that the dependence on lipid synthesis makes targeting of lipid synthesis metabolism a promising therapeutic strategy for eliminating CSCs. Targeting key molecules in lipid synthesis will play an important role in anti-CSC therapy.

The Epithelial-Mesenchymal Transition at the Crossroads between Metabolism and Tumor Progression

The transition between epithelial and mesenchymal phenotype is emerging as a key determinant of tumor cell invasion and metastasis. It is a plastic process in which epithelial cells first acquire the ability to invade the extracellular matrix and migrate into the bloodstream via transdifferentiation into mesenchymal cells, a phenomenon known as epithelial–mesenchymal transition (EMT), and then reacquire the epithelial phenotype, the reverse process called mesenchymal–epithelial transition (MET), to colonize a new organ. During all metastatic stages, metabolic changes, which give cancer cells the ability to adapt to increased energy demand and to withstand a hostile new environment, are also important determinants of successful cancer progression. In this review, we describe the complex interaction between EMT and metabolism during tumor progression. First, we outline the main connections between the two processes, with particular emphasis on the role of cancer stem cells and LncRNAs. Then, we focus on some specific cancers, such as breast, lung, and thyroid cancer.

Pharmacological Targeting of Ferroptosis in Cancer Treatment

Ferroptosis is a non-apoptotic mode of Regulated Cell Death (RCD) driven by excessive accumulation of toxic lipid peroxides and iron overload. Ferroptosis could be triggered by inhibiting the antioxidant defense system and accumulating iron-dependent Reactive Oxygen Species (ROS) that react with polyunsaturated fatty acids in abundance. Emerging evidence over the past few years has revealed that ferroptosis is of great potential in inhibiting growth and metastasis and overcoming tumor cell resistance. Thus, targeting this form of cell death could be perceived as a potentially burgeoning approach in cancer treatment. This review briefly presents the underlying mechanisms of ferroptosis and further aims to discuss various types of existing drugs and natural compounds that could be potentially repurposed for targeting ferroptosis in tumor cells. This, in turn, will provide critical perspectives on future studies concerning ferroptosis-based cancer therapy.

Lipid metabolism in cancer: A systematic review

Preclinical studies and clinical trials have emphasized the decisive role of lipid metabolism in tumor proliferation and metastasis. This systematic review aimed to explore the existing literature to evaluate the role and significance of the genes and pathways most commonly involved in the regulation of lipid metabolism in cancer. The literature search was performed as per Preferred Reporting Items for Systematic Reviews and Meta-analyses. Approximately 2396 research articles were initially selected, of which 215 were identified as potentially relevant for abstract review. Upon further scrutiny, 62 of the 215 studies were reviews, seminars, or presentations, and 44 were original study articles and were thus included in the systematic review. The predominant gene involved in lipid metabolism in cancer was stearoyl-coenzyme A desaturase 1 (SCD1), followed by fatty acid synthase (FASN). The pathway most commonly involved in lipid metabolism in cancer was the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, followed by the mitogen activated protein kinase (MAPK) pathway. SCD1 and FASN play significant roles in the initiation and progression of cancer and represent attractive targets for potentially effective anti-cancer treatment strategies. The regulation of cancer metabolism by the Akt kinases will be an interesting topic of future study.

Nanostructured Architectures Promote the Mesenchymal-Epithelial Transition for Invasive Cells

Dynamic modulation of cellular phenotypes between the epithelial and mesenchymal states-the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET)-plays an important role in cancer progression. Nanoscale topography of culture substrates is known to affect the migration and EMT of cancer cells. However, existing platforms heavily rely on simple geometries such as grooved lines or cylindrical post arrays, which may oversimplify the complex interaction between cells and nanotopography in vivo. Here, we use electrodeposition to construct finely controlled surfaces with biomimetic fractal nanostructures as a means of examining the roles of nanotopography during the EMT/MET process. We found that nanostructures in the size range of 100 to 500 nm significantly promote MET for invasive breast and prostate cancer cells. The "METed" cells acquired distinct expression of epithelial and mesenchymal markers, displayed perturbed morphologies, and exhibited diminished migration and invasion, even after the removal of a nanotopographical stimulus. The phosphorylation of GSK-3 was decreased, which further tuned the expression of Snail and modulated the EMT/MET process. Our findings suggest that invasive cancer cells respond to the geometries and dimensions of complex nanostructured architectures.

SCD1 activity promotes cell migration via a PLD-mTOR pathway in the MDA-MB-231 triple-negative breast cancer cell line

BACKGROUND

Breast cancer is the most common cancer in women. Despite high survival rates in Western countries, treatments are less effective in metastatic cases and triple-negative breast cancer (TNBC) patient survival is the shortest across breast cancer subtypes. High expression levels of stearoyl-CoA desaturase-1 (SCD1) have been reported in breast cancer. The SCD1 enzyme catalyzes the formation of oleic acid (OA), a lipid stimulating the migration of metastatic breast cancer cells. Phospholipase activity is also implicated in breast cancer metastasis, notably phospholipase D (PLD).

METHODS

Kaplan-Meier survival plots generated from gene expression databases were used to analyze the involvement of SCD1 and PLD in several cancer subtypes. SCD1 enzymatic activity was modulated with a pharmaceutical inhibitor or by OA treatment (to mimic SCD1 over-activity) in three breast cancer cell lines: TNBC-derived MDA-MB-231 cells as well as non-TNBC MCF-7 and T47D cells. Cell morphology and migration properties were characterized by various complementary methods.

RESULTS

Our survival analyses suggest that SCD1 and PLD2 expression in the primary tumor are both associated to metastasis-related morbid outcomes in breast cancer patients. We show that modulation of SCD1 activity is associated with the modification of TNBC cell migration properties, including changes in speed, direction and cell morphology. Cell migration properties are regulated by SCD1 activity through a PLD-mTOR/p70S6K signaling pathway. These effects are not observed in non-TNBC cell lines.

CONCLUSION

Our results establish a key role for the lipid desaturase SCD1 and delineate an OA-PLD-mTOR/p70S6K signaling pathway in TNBC-derived MDA-MB-231 cell migration.

Dietary fat and obesity as modulators of breast cancer risk: Focus on DNA methylation

Breast cancer (BC) is the most common cancer and second leading cause of cancer mortality in women worldwide. Validated biomarkers enhance efforts for early detection and treatment, which reduce the risk of mortality. Epigenetic signatures have been suggested as good biomarkers for early detection, prognosis and targeted therapy of BC. Here, we highlight studies documenting the modifying effects of dietary fatty acids and obesity on BC biomarkers associated with DNA methylation. We focus our analysis on changes elicited in writers of DNA methylation (i.e., DNA methyltransferases), global DNA methylation and gene-specific DNA methylation. To provide context, we precede this discussion with a review of the available evidence for an association between BC incidence and both dietary fat consumption and obesity. We also include a review of well-vetted BC biomarkers related to cytosine-guanine dinucleotides methylation and how they influence BC risk, prognosis, tumour characteristics and response to treatment. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

Do Olive and Fish Oils of the Mediterranean Diet Have a Role in Triple Negative Breast Cancer Prevention and Therapy? An Exploration of Evidence in Cells and Animal Models

Breast cancer is the most common malignancy and cause of cancer-related mortality among women worldwide. Triple negative breast cancers (TNBC) are the most aggressive and lethal of the breast cancer molecular subtypes, due in part to a poor understanding of TNBC etiology and lack of targeted therapeutics. Despite advances in the clinical management of TNBC, optimal treatment regimens remain elusive. Thus, identifying interventional approaches that suppress the initiation and progression of TNBC, while minimizing side effects, would be of great interest. Studies have documented an inverse relationship between the incidence of hormone receptor negative breast cancer and adherence to a Mediterranean Diet, particularly higher consumption of fish and olive oil. Here, we performed a review of studies over the last 5 years investigating the effects of fish oil, olive oil and their components in model systems of TNBC. We included studies that focused on the fish oil ω-3 essential fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in addition to olive oil polyphenolic compounds and oleic acid. Both beneficial and deleterious effects on TNBC model systems are reviewed and we highlight how multiple components of these Mediterranean Diet oils target signaling pathways known to be aberrant in TNBC including PI3K/Akt/mTOR, NF-κB/COX2 and Wnt/β-catenin.

Sphere-forming culture enriches liver cancer stem cells and reveals Stearoyl-CoA desaturase 1 as a potential therapeutic target

BACKGROUNDS

The role of sphere-forming culture in enriching subpopulations with stem-cell properties in hepatocellular carcinoma (HCC) is unclear. The present study investigates its value in enriching cancer stem cells (CSCs) subpopulations and the mechanism by which HCC CSCs are maintained.

METHODS

HCC cell lines and fresh primary tumor cells were cultured in serum-free and ultra-low attachment conditions to allow formation of HCC spheres. In vitro and in vivo experiments were performed to evaluate CSC characteristics. Expression levels of CSC-related genes were assessed by qRT-PCR and the correlation between sphere formation and clinical characteristics was investigated. Finally, gene expression profiling was performed to explore the molecular mechanism underlying HCC CSC maintenance.

RESULTS

We found that both cell lines and primary tumor cells formed spheres. HCC spheres possessed the capacity for self-renewal, proliferation, drug resistance, and contained different subpopulations of CSCs. Of interest, 500 sphere-forming Huh7 cells or 200 primary tumor cells could generate tumors in immunodeficient animals. Sphere formation correlated with size, multiple tumors, satellite lesions, and advanced stage. Further investigation identified that the PPARα-SCD1 axis plays an important role in maintenance of the CSC properties of HCC sphere cells by promoting nuclear accumulation of β-Catenin. Inhibition of SCD1 interfered with sphere formation, down-regulated expression of CSC-related markers, and reduced β-Catenin nuclear accumulation.

CONCLUSIONS

Sphere-forming culture can effectively enrich subpopulations with stem-cell properties, which are maintained through activation of the PPARα-SCD1 axis. Therefore, we suggest that targeting the SCD1-related CSC machinery might provide a novel insight into HCC treatment.

Stearoyl-CoA Desaturase 1 as a Therapeutic Target for the Treatment of Cancer

A distinctive feature of cancer cells of various origins involves alterations of the composition of lipids, with significant enrichment in monounsaturated fatty acids. These molecules, in addition to being structural components of newly formed cell membranes of intensely proliferating cancer cells, support tumorigenic signaling. An increase in the expression of stearoyl-CoA desaturase 1 (SCD1), the enzyme that converts saturated fatty acids to ∆9-monounsaturated fatty acids, has been observed in a wide range of cancer cells, and this increase is correlated with cancer aggressiveness and poor outcomes for patients. Studies have demonstrated the involvement of SCD1 in the promotion of cancer cell proliferation, migration, metastasis, and tumor growth. Many studies have reported a role for this lipogenic factor in maintaining the characteristics of cancer stem cells (i.e., the population of cells that contributes to cancer progression and resistance to chemotherapy). Importantly, both the products of SCD1 activity and its direct impact on tumorigenic pathways have been demonstrated. Based on these findings, SCD1 appears to be a significant player in the development of malignant disease and may be a promising target for anticancer therapy. Numerous chemical compounds that exert inhibitory effects on SCD1 have been developed and preclinically tested. The present review summarizes our current knowledge of the ways in which SCD1 contributes to the progression of cancer and discusses opportunities and challenges of using SCD1 inhibitors for the treatment of cancer.

Emodin Induced SREBP1-Dependent and SREBP1-Independent Apoptosis in Hepatocellular Carcinoma Cells

Reynoutria multiflora (Thunb.) Moldenke (He Shou Wu) has been used for about 20 centuries as a Chinese medicinal herb for its activities of anticancer, anti-hyperlipidemia, and anti-aging. Previously, we found that He Shou Wu ethanol extract could induce apoptosis in hepatocellular carcinoma cells, and we also screened its active components. In this study, we investigated whether lowering lipid metabolism of emodin, a main active component in He Shou Wu, was associated with inhibitory effects in hepatocellular carcinoma cells. The correlation of apoptosis induction and lipid metabolism was investigated. The intrinsic apoptotic cell death, lipid production, and their signaling pathways were investigated in emodin-treated human hepatocellular carcinoma cells Bel-7402. The data showed that emodin triggered apoptosis in Bel-7402 cells. The mitochondrial membrane potential (ΔΨm) was reduced in emodin-treated Bel-7402 cells. We also found that emodin activated the expression of intrinsic apoptosis signaling pathway-related proteins, cleaved-caspase 9 and 3, Apaf 1, cytochrome c (CYTC), apoptosis-inducing factor, endonuclease G, Bax, and Bcl-2. Furthermore, the level of triglycerides and desaturation of fatty acids was reduced in Bel-7402 cells when exposed to emodin. Furthermore, the expression level of messenger RNA (mRNA) and protein of sterol regulatory element binding protein 1 (SREBP1) as well as its downstream signaling pathway and the synthesis and the desaturation of fatty acid metabolism-associated proteins (adenosine triphosphate citrate lyase, acetyl-CoA carboxylase alpha, fatty acid synthase (FASN), and stearoyl-CoA desaturase D) were also decreased. Notably, knock-out of SREBP1 in Bel-7402 cells was also found to induce less intrinsic apoptosis than did emodin. In conclusion, these results indicated that emodin could induce apoptosis in an SREBP1-dependent and SREBP1-independent manner in hepatocellular carcinoma cells.

The role of YAP/TAZ activity in cancer metabolic reprogramming

In contrast to normal cells, which use the aerobic oxidation of glucose as their main energy production method, cancer cells prefer to use anaerobic glycolysis to maintain their growth and survival, even under normoxic conditions. Such tumor cell metabolic reprogramming is regulated by factors such as hypoxia and the tumor microenvironment. In addition, dysregulation of certain signaling pathways also contributes to cancer metabolic reprogramming. Among them, the Hippo signaling pathway is a highly conserved tumor suppressor pathway. The core oncosuppressive kinase cascade of Hippo pathway inhibits the nuclear transcriptional co-activators YAP and TAZ, which are the downstream effectors of Hippo pathway and oncogenic factors in many solid cancers. YAP/TAZ function as key nodes of multiple signaling pathways and play multiple regulatory roles in cancer cells. However, their roles in cancer metabolic reprograming are less clear. In the present review, we examine progress in research into the regulatory mechanisms of YAP/TAZ on glucose metabolism, fatty acid metabolism, mevalonate metabolism, and glutamine metabolism in cancer cells. Determining the roles of YAP/TAZ in tumor energy metabolism, particularly in relation to the tumor microenvironment, will provide new strategies and targets for the selective therapy of metabolism-related cancers.

Stearoyl coenzyme A desaturase

Background:

Oral cancer is a major public health problem in many parts of South Asia and ranking third among the cancer types in India. Numerous diagnostic, prognostic and metastatic biomarkers have been employed till date to assess various carcinomas. Stearoyl coenzyme A desaturase (SCD) is one such recently introduced biomarker that regulates key cell cycle events in normal cells and during carcinogenesis in neoplastic cells. Although SCD has been used to analyze the prognosis of breast and renal cell carcinomas, its role in oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) remains unexplored. Therefore, there is a need to analyze the role of SCD in OED and OSCC to predict their biologic behaviour.

Objectives:

To assess the expression levels of SCD in OED and OSCC samples and correlate them with normal oral mucosa (NOM) to determine their prognostic potential.

Methodology:

Fifty five tissue samples of OED (20), OSCC (20) and NOM (15) was subjected to immunohistochemistry using SCD. Clinical details and follow-up data (3 years) were recorded. Clinical and histopathological parameters were statistically analyzed using descriptive statistics, univariate and multivariate analyses, Kruskal–Wallis analysis of variance test and Mann–Whitney U tests.

Results:

Descriptive analysis on OED and NOM showed a statistically significant difference in age between OED and NOM ( p = 0.002). Univariate analysis of OSCC cases by log-rank test revealed significant results in the usage of smoked and smokeless tobacco and clinical staging of OSCC ( p = 0.044). Significantly increased SCD expression was identified with poor survival rate ( p = 0.028). However, multivariate analysis of OSCC was statistically insignificant ( p = 1.00). A significantly increased SCD expression was observed in OED and OSCC when compared to NOM ( p = 0.001). The expression of SCD was significantly high in OSCC when compared to OED ( p = 0.029). Although an increased expression of SCD was appreciated in higher grades of OED and poorly differentiated squamous cell carcinoma, a statistical significance was not achieved ( p = 0.546 and 0.388, respectively).

Conclusion:

The expression of SCD in OED was higher than NOM suggesting changes in cell cycle control in OED. An enhanced expression of SCD was identified in OSCC when compared to OED. Correlating the SCD expression with survival rate in OSCC patients revealed an increased SCD expression with diminished survival rate, indicating that SCD may be used to predict prognosis. However, the role of SCD in assessing the prognostic potential within the grades of OED and OSCC requires future research.

Emerging role of lipid metabolism alterations in Cancer stem cells

BACKGROUND

Cancer stem cells (CSCs) or tumor-initiating cells (TICs) represent a small population of cancer cells with self-renewal and tumor-initiating properties. Unlike the bulk of tumor cells, CSCs or TICs are refractory to traditional therapy and are responsible for relapse or disease recurrence in cancer patients. Stem cells have distinct metabolic properties compared to differentiated cells, and metabolic rewiring contributes to self-renewal and stemness maintenance in CSCs.

MAIN BODY

Recent advances in metabolomic detection, particularly in hyperspectral-stimulated raman scattering microscopy, have expanded our knowledge of the contribution of lipid metabolism to the generation and maintenance of CSCs. Alterations in lipid uptake, de novo lipogenesis, lipid droplets, lipid desaturation, and fatty acid oxidation are all clearly implicated in CSCs regulation. Alterations on lipid metabolism not only satisfies the energy demands and biomass production of CSCs, but also contributes to the activation of several important oncogenic signaling pathways, including Wnt/β-catenin and Hippo/YAP signaling. In this review, we summarize the current progress in this attractive field and describe some recent therapeutic agents specifically targeting CSCs based on their modulation of lipid metabolism.

CONCLUSION

Increased reliance on lipid metabolism makes it a promising therapeutic strategy to eliminate CSCs. Targeting key players of fatty acids metabolism shows promising to anti-CSCs and tumor prevention effects.

Pivotal role of human stearoyl-CoA desaturases (SCD1 and 5) in breast cancer progression: oleic acid-based effect of SCD1 on cell migration and a novel pro-cell survival role for SCD5

The influence of cell membrane fluidity on cancer progression has been established in different solid tumors. We previously reported that “cancer-associated fibroblasts” (CAFs) induced epithelial-mesenchymal transition and increased cell membrane fluidity and migration in poorly (MCF-7) and highly invasive (MDA-MB-231) breast cancer cells. We also found that the membrane fluidity regulating enzyme stearoyl-CoA desaturase 1 (SCD1) was upregulated in tumor cells co-cultured with CAFs and established its essential role for both intrinsic and CAF-driven tumor cell motility. Here, we further explored the mechanisms involved in the SCD1-based modulation of breast cancer cell migration and investigated the role of the other human SCD isoform, SCD5. We showed that the addition of oleic acid, the main SCD1 product, nullified the inhibitory effects produced on MCF-7 and MDA-MB-231 cell migration by SCD1 depletion (pharmacological or siRNA-based). Conversely, SCD5 seemed not involved in the regulation of cancer cell motility. Interestingly, a clear induction of necrosis was observed as a result of the depletion of SCD5 in MCF-7 cells, where the expression of SCD5 was found to be upregulated by CAFs. The necrotic effect was rescued by a 48-h treatment of cells with oleic acid. These results provide further insights in understanding the role of SCD1 in both intrinsic and CAF-stimulated mammary tumor cell migration, unveiling the metabolic basis of this desaturase-triggered effect. Moreover, our data suggest the ability of CAFs to promote the maintenance of tumor cell survival by the induction of SCD5 levels.

Phase separation of the plasma membrane in human red blood cells as a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus

Glycosylation, oxidation and other post-translational modifications of membrane and transmembrane proteins can alter lipid density, packing and interactions, and are considered an important factor that affects fluidity variation in membranes. Red blood cells (RBC) membrane physical state, showing pronounced alterations in Type 1 diabetes mellitus (T1DM), could be the ideal candidate for monitoring the disease progression and the effects of therapies. On these grounds, the measurement of RBC membrane fluidity alterations can furnish a more sensitive index in T1DM diagnosis and disease progression than Glycosylated hemoglobin (HbA1c), which reflects only the information related to glycosylation processes. Here, through a functional two-photon microscopy approach we retrieved fluidity maps at submicrometric scale in RBC of T1DM patients with and without complications, detecting an altered membrane equilibrium. We found that a phase separation between fluid and rigid domains occurs, triggered by systemic effects on membranes fluidity of glycation and oxidation. The phase separation patterns are different among healthy, T1DM and T1DM with complications patients. Blood cholesterol and LDL content are positively correlated with the extent of the phase separation patterns. To quantify this extent a machine learning approach is employed to develop a Decision-Support-System (DSS) able to recognize different fluidity patterns in RBC. Preliminary analysis shows significant differences(p<0.001) among healthy, T1DM and T1DM with complications patients. The development of an assay based on Phase separation of the plasma membrane of the Red Blood cells is a potential tool for diagnosis and progression monitoring of type 1 diabetes mellitus, and could allow customization and the selection of medical treatments in T1DM in clinical settings, and enable the early detection of complications.

Dynamics of cancerous tissue correlates with invasiveness

Two of the classical hallmarks of cancer are uncontrolled cell division and tissue invasion, which turn the disease into a systemic, life-threatening condition. Although both processes are studied, a clear correlation between cell division and motility of cancer cells has not been described previously. Here, we experimentally characterize the dynamics of invasive and non-invasive breast cancer tissues using human and murine model systems. The intrinsic tissue velocities, as well as the divergence and vorticity around a dividing cell correlate strongly with the invasive potential of the tissue, thus showing a distinct correlation between tissue dynamics and aggressiveness. We formulate a model which treats the tissue as a visco-elastic continuum. This model provides a valid reproduction of the cancerous tissue dynamics, thus, biological signaling is not needed to explain the observed tissue dynamics. The model returns the characteristic force exerted by an invading cell and reveals a strong correlation between force and invasiveness of breast cancer cells, thus pinpointing the importance of mechanics for cancer invasion.

Panax notoginseng saponins attenuate lung cancer growth in part through modulating the level of Met/miR-222 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng saponins (PNS) are the major chemical constituents of Panax notoginseng (Burkill) F.H. Chen (Araliaceae), a medicinal herb extensively used in China for the treatment of various diseases including cancer. PNS have been reported to contribute to the therapeutic effects of Panax notoginseng in disease conditions including lung cancer.

AIM OF THE STUDY

The current study aims to further understand the molecular mechanisms implicated in the pharmacological activities of PNS in attenuating lung cancer growth.

MATERIALS AND METHODS

Lewis lung carcinoma (LLC) cell line was employed and the impact of PNS treatment on the viability of LLC cells was first examined in vitro. The tumor-suppressive effect of PNS was further validated in vivo by assessing the tumor growth in BALB/c mice inoculated with LLC cells. Whole genome microarray and real-time PCR analyses were performed to examine and verify altered expression of genes associated with PNS treatment. Real-time PCR and western blotting analyses were also carried out to investigate the implication of microRNA (miRNA)-mediated gene expression regulation in the anti-tumor activity of PNS.

RESULTS

PNS treatment resulted in selective impairment of the survival of LLC cells. Furthermore, PNS treatment led to attenuated growth of tumors derived from inoculated LLC cells in mice. Bioinformatic analyses of gene expression profiles revealed that multiple pathways associated with tumorigenesis were significantly modulated by PNS treatment in vivo. The expression of an array of genes promoting tumorigenesis and progression including Hgf, Met, Notch3, Scd1, Epas1, Col1a1, Raf1, Braf1 and CDK6 was significantly decreased by PNS treatment, whereas the expression of tumor suppressive Rxrg was significantly increased as a result of PNS treatment. The level of miR-222, a miRNA regulated by Met, was significantly decreased by PNS treatment. The expression of tumor suppressor p27 and PTEN, miR-222 target genes, was significantly increased by PNS treatment.

CONCLUSION

Out work here presented novel evidence demonstrating that multiple mechanisms were implicated in the anti-tumor effects of PNS in lung cancer models. Particularly, PNS treatment significantly modulated the level of Met/miR-222 axis in LLC cells. Increased understanding of the anti-tumor mechanisms of PNS may provide further experimental evidence to help optimize the therapeutic modalities for the treatment of lung cancer and other types of cancer.

Fatty acid-related modulations of membrane fluidity in cells: detection and implications

Metabolic homeostasis of fatty acids is complex and well-regulated in all organisms. The biosynthesis of saturated fatty acids (SFA) in mammals provides substrates for β-oxidation and ATP production. Monounsaturated fatty acids (MUFA) are products of desaturases that introduce a methylene group in cis geometry in SFA. Polyunsaturated fatty acids (n-6 and n-3 PUFA) are products of elongation and desaturation of the essential linoleic acid and α-linolenic acid, respectively. The liver processes dietary fatty acids and exports them in lipoproteins for distribution and storage in peripheral tissues. The three types of fatty acids are integrated in membrane phospholipids and determine their biophysical properties and functions. This study was aimed at investigating effects of fatty acids on membrane biophysical properties under varying nutritional and pathological conditions, by integrating lipidomic analysis of membrane phospholipids with functional two-photon microscopy (fTPM) of cellular membranes. This approach was applied to two case studies: first, pancreatic beta-cells, to investigate hormetic and detrimental effects of lipids. Second, red blood cells extracted from a genetic mouse model defective in lipoproteins, to understand the role of lipids in hepatic diseases and metabolic syndrome and their effect on circulating cells.

Stearoyl CoA desaturase-1: New insights into a central regulator of cancer metabolism

The processes of cell proliferation, cell death and differentiation involve an intricate array of biochemical and morphological changes that require a finely tuned modulation of metabolic pathways, chiefly among them is fatty acid metabolism. The critical participation of stearoyl CoA desaturase-1 (SCD1), the fatty acyl Δ9-desaturing enzyme that converts saturated fatty acids (SFA) into monounsaturated fatty acids (MUFA), in the mechanisms of replication and survival of mammalian cells, as well as their implication in the biological alterations of cancer have been actively investigated in recent years. This review examines the growing body of evidence that argues for a role of SCD1 as a central regulator of the complex synchronization of metabolic and signaling events that control cellular metabolism, cell cycle progression, survival, differentiation and transformation to cancer.

The mucin MUC1 modulates the tumor immunological microenvironment through engagement of the lectin Siglec-9

Siglec-9 is a sialic acid binding lectin predominantly expressed on myeloid cells. Aberrant glycosylation occurs in essentially all types of cancers resulting in increased sialylation. Thus when MUC1 is expressed on cancer cells it is decorated by multiple short, sialylated O-linked glycans (MUC1-ST). Here we show that this cancer-specific MUC1 glycoform could, through the engagement of Siglec-9, educate myeloid cells to release factors associated with tumor microenvironment determination and disease progression. Moreover MUC1-ST induced macrophages to display a TAM-like phenotype with increased expression of PD-L1. MUC1-ST binding to Siglec-9 did not activate SHP-1/2 but surprisingly induced calcium flux leading to MEK-ERK activation. This work defines a critical role for aberrantly glycosylated MUC1 and identifies an activating pathway following Siglec-9 engagement.