Caveolin-1-LRP6 signaling module stimulates aerobic glycolysis in prostate cancer

Inhibition of glycolysis and Src/Akt signaling reduces Caveolin-1-enhanced metastasis

Metastasis is the leading cause of cancer-related deaths, making the development of novel, more effective therapies imperative to alleviate patient suffering. Metabolic switching is a hallmark of cancer cells that facilitates metastasis. Cancer cells obtain most of their energy and intermediate metabolites, which are required to proliferate and metastasize, through aerobic glycolysis. Previous work from our laboratory has shown that Caveolin-1 (CAV1) expression in cancer cells promotes glycolysis and metastasis. Here, we sought to determine if limiting glycolysis reduced CAV1-enhanced metastasis and to identify the mechanism(s) involved. We evaluated the effects of the glycolysis inhibitor 2-deoxy-D-glucose (2-DG) in metastatic melanoma and breast cancer cell lines expressing or not CAV1. Non-cytotoxic concentrations of 2-DG (1 mM) inhibited the migration of B16-F10 melanoma and MDA-MB-231 breast cancer cells. CAV1-mediated activation of Src/Akt signaling was required for CAV1-enhanced migration and was blocked in the presence of 2-DG. Moreover, inhibition of Akt reduced CAV1-enhanced lung metastasis of B16-F10 cells. Collectively, these findings highlight the importance of CAV1-induced metabolic reprogramming for metastasis and point towards possible therapeutic approaches to prevent metastatic disease by inhibiting glycolysis and Src/Akt signaling.

Multifaceted effects of LRP6 in cancer: exploring tumor development, immune modulation and targeted therapies

Low-density lipoprotein receptor (LDLR)-related protein 6 (LRP6), a member of the LDLR superfamily of cell surface receptors, is most widely known as a crucial co-receptor in the activation of canonical Wnt/β-catenin signaling. This signaling pathway is implicated in multiple biological processes, such as lipoprotein metabolism, protease regulation, cell differentiation, and migration. LRP6 is frequently overexpressed in a variety of tumors, including liver cancer, colorectal cancer, and prostate cancer, and is generally considered an oncogene that promotes tumor proliferation, migration, and invasion. However, there are exceptions; some studies have reported that LRP6 inhibits lung metastasis of breast cancer through its ectodomain (LRP6N), and patients with low LRP6 expression tend to have a poor prognosis. Thus, the role of LRP6 in tumors remains controversial. Although limited studies have shown that LRP6 is associated with the expression and roles of a variety of immune cells in tumors, the interaction of LRP6 with the tumor microenvironment (TME) is not fully understood. Furthermore, it is crucial to acknowledge that LRP6 can engage with alternative pathways, including the mTORC1, CXCL12/CXCR4, and KRAS signaling pathways mentioned earlier, resulting in the regulation of biological functions independent of canonical Wnt/β-catenin signaling. Due to the potential of LRP6 as a molecular target for cancer therapy, various treatment modalities have been developed to directly or indirectly inhibit LRP6 function, demonstrating promising anti-cancer effects across multiple cancer types. This review will concentrate on exploring the expression, function, and potential therapeutic applications of LRP6 in different cancer types, along with its influence on the TME.

Targeting LRP6: A new strategy for cancer therapy

Targeting specific molecular drivers of tumor growth is a key approach in cancer therapy. Among these targets, the low-density lipoprotein receptor-related protein 6 (LRP6), a vital component of the Wnt signaling pathway, has emerged as an intriguing candidate. As a cell-surface receptor and vital co-receptor, LRP6 is frequently overexpressed in various cancer types, implicating its pivotal role in driving tumor progression. The pursuit of LRP6 as a target for cancer treatment has gained substantial traction, offering a promising avenue for therapeutic intervention. Here, this comprehensive review explores recent breakthroughs in our understanding of LRP6's functions and underlying molecular mechanisms, providing a profound discussion of its involvement in cancer pathogenesis and drug resistance. Importantly, we go beyond discussing LRP6's role in cancer by discussing diverse potential therapeutic approaches targeting this enigmatic protein. These approaches encompass a wide spectrum, including pharmacological agents, natural compounds, non-coding RNAs, epigenetic factors, proteins, and peptides that modulate LRP6 expression or disrupt its interactions. In addition, also discussed the challenges associated with developing LRP6 inhibitors and their advantages over Wnt inhibitors, as well as the drugs that have entered phase II clinical trials. By shedding light on these innovative strategies, we aim to underscore LRP6's significance as a valuable and multifaceted target for cancer treatment, igniting enthusiasm for further research and facilitating translation into clinical applications.

The inhibition of YTHDF3/m6A/LRP6 reprograms fatty acid metabolism and suppresses lymph node metastasis in cervical cancer

The lipid synthesis of fatty acid (FA) represents a significant hallmark in the occurrence and progression of malignant tumor, which are associated with lymph node (LN) metastasis. Elucidation of the molecular mechanisms underlying LN metastasis could provide therapeutic strategies for cervical cancer (CCa). N6-Methyladenosine (m6A), the most prevalent and abundant RNA modification, exerts specific regulatory control over a series of oncogene expressions. This study demonstrated a clinical correlation between the upregulation of the m6A reader YTHDF3 and LN metastasis, thereby contributing to poor overall survival probability (OS) among CCa patients. The mechanistic investigation revealed that SREBF1 transcriptionally activated YTHDF3 expression by binding to its promoter. Functional experiments demonstrated that the upregulation of YTHDF3 significantly enhanced the in vitro proliferative, migratory, and invasive capacities of CCa cells, while also promoting lymphangiogenesis and facilitating LN metastasis in vivo. Mechanistically, the upregulation of LRP6 through YTHDF3-mediated m6A modification resulted in increased expression of FASN and ACC1, leading to both lipolysis of lipid droplets and synthesis of free fatty acid. Ultimately, this promoted fatty acid metabolism and enhanced LN metastasis by activating the LRP6-YAP-VEGF-C axis, which could induce lymphangiogenesis in CCa. Our study highlighted that YTHDF3 can serve as a promising therapeutic target and predictive biomarker for CCa patients with LN metastasis.

LRP5 competes for SPOP binding to enhance tumorigenesis mediated by Daxx and PD-L1 in prostate cancer

Genetic factors coordinate with environmental factors to drive the pathogenesis of prostate adenocarcinoma (PRAD). SPOP is one of the most mutated genes and LRP5 mediates lipid metabolism that is abnormally altered in PRAD. Here, we investigated the potential cross-talk between SPOP and LRP5 in PRAD. We find a negative correlation between SPOP and LRP5 proteins in PRAD. SPOP knockdown increased LRP5 protein while SPOP overexpression resulted in LRP5 reduction that was fully rescued by proteasome inhibitors. LRP5 intracellular tail has SPOP binding site and the direct interaction between LRP5 and SPOP was confirmed by Co-IP and GST-pulldown. Moreover, LRP5 competed with Daxx for SPOP-mediated degradation, establishing a dynamic balance among SPOP, LRP5 and Daxx. Overexpression of LRP5 tail could shift this balance to enhance Daxx-mediated transcriptional inhibition, and inhibit T cell activity in a co-culture system. Further, we generated human and mouse prostate cancer cell lines expressing SPOP variants (F133V, A227V, R368H). SPOP-F133V and SPOP-A227V have specific effects in up-regulating the protein levels of PD-1 and PD-L1. Consistently, SPOP-F133V and SPOP-A227V show robust inhibitory effects on T cells compared to WT SPOP in co-culture. This is further supported by the mouse syngeneic model showing that SPOP-F133V and SPOP-A227V enhance tumorigenesis of prostate cancer in in-vivo condition. Taken together, our study provides evidence that SPOP-LRP5 crosstalk plays an essential role, and the genetic variants of SPOP differentially modulate the expression and activity of immune checkpoints in prostate cancer.

Caveolin-1 promotes mitochondrial health and limits mitochondrial ROS through ROCK/AMPK regulation of basal mitophagic flux

Caveolin-1 (CAV1), the main structural component of caveolae, is phosphorylated at tyrosine-14 (pCAV1), regulates signal transduction, mechanotransduction, and mitochondrial function, and plays contrasting roles in cancer progression. We report that CRISPR/Cas9 knockout (KO) of CAV1 increases mitochondrial oxidative phosphorylation, increases mitochondrial potential, and reduces ROS in MDA-MB-231 triple-negative breast cancer cells. Supporting a role for pCAV1, these effects are reversed upon expression of CAV1 phosphomimetic CAV1 Y14D but not non-phosphorylatable CAV1 Y14F. pCAV1 is a known effector of Rho-associated kinase (ROCK) signaling and ROCK1/2 signaling mediates CAV1 promotion of increased mitochondrial potential and decreased ROS production in MDA-MB-231 cells. CAV1/ROCK control of mitochondrial potential and ROS is caveolae-independent as similar results were observed in PC3 prostate cancer cells lacking caveolae. Increased mitochondrial health and reduced ROS in CAV1 KO MDA-MB-231 cells were reversed by knockdown of the autophagy protein ATG5, mitophagy regulator PINK1 or the mitochondrial fission protein Drp1 and therefore due to mitophagy. Use of the mitoKeima mitophagy probe confirmed that CAV1 signaling through ROCK inhibited basal mitophagic flux. Activation of AMPK, a major mitochondrial homeostasis protein inhibited by ROCK, is inhibited by CAV1-ROCK signaling and mediates the increased mitochondrial potential, decreased ROS, and decreased basal mitophagy flux observed in wild-type MDA-MB-231 cells. CAV1 regulation of mitochondrial health and ROS in cancer cells therefore occurs via ROCK-dependent inhibition of AMPK. This study therefore links pCAV1 signaling activity at the plasma membrane with its regulation of mitochondrial activity and cancer cell metabolism through control of mitophagy.

β-catenin inhibitors in cancer therapeutics: intricacies and way forward

β-catenin is an evolutionary conserved, quintessential, multifaceted protein that plays vital roles in cellular homeostasis, embryonic development, organogenesis, stem cell maintenance, cell proliferation, migration, differentiation, apoptosis, and pathogenesis of various human diseases including cancer. β-catenin manifests both signaling and adhesive features. It acts as a pivotal player in intracellular signaling as a component of versatile WNT signaling cascade involved in embryonic development, homeostasis as well as in carcinogenesis. It is also involved in Ca2+ dependent cell adhesion via interaction with E-cadherin at the adherens junctions. Aberrant β-catenin expression and its nuclear accumulation promote the transcription of various oncogenes including c-Myc and cyclinD1, thereby contributing to tumor initiation, development, and progression. β-catenin's expression is closely regulated at various levels including its stability, sub-cellular localization, as well as transcriptional activity. Understanding the molecular mechanisms of regulation of β-catenin and its atypical expression will provide researchers not only the novel insights into the pathogenesis and progression of cancer but also will help in deciphering new therapeutic avenues. In the present review, we have summarized the dual functions of β-catenin, its role in signaling, associated mutations as well as its role in carcinogenesis and tumor progression of various cancers. Additionally, we have discussed the challenges associated with targeting β-catenin molecule with the presently available drugs and suggested the possible way forward in designing new therapeutic alternatives against this oncogene.

Molecular pathogenesis, mechanism and therapy of Cav1 in prostate cancer

Prostate cancer is the second incidence of malignant tumors in men worldwide. Its incidence and mortality are increasing year by year. Enhanced expression of Cav1 in prostate cancer has been linked to both proliferation and metastasis of cancer cells, influencing disease progression. Dysregulation of the Cav1 gene shows a notable association with prostate cancer. Nevertheless, there is no systematic review to report about molecular signal mechanism of Cav1 and drug treatment in prostate cancer. This article reviews the structure, physiological and pathological functions of Cav1, the pathogenic signaling pathways involved in prostate cancer, and the current drug treatment of prostate cancer. Cav1 mainly affects the occurrence of prostate cancer through AKT/mTOR, H-RAS/PLCε, CD147/MMPs and other pathways, as well as substance metabolism including lipid metabolism and aerobic glycolysis. Baicalein, simvastatin, triptolide and other drugs can effectively inhibit the growth of prostate cancer. As a biomarker of prostate cancer, Cav1 may provide a potential therapeutic target for the treatment of prostate cancer.

Caveolin-1 promotes glioma progression and maintains its mitochondrial inhibition resistance

BACKGROUND

Glioma is a lethal brain cancer and lacking effective therapies. Challenges include no effective therapeutic target, intra- and intertumoral heterogeneity, inadequate effective drugs, and an immunosuppressive microenvironment, etc. Deciphering the pathogenesis of gliomas and finding out the working mechanisms are urgent and necessary for glioma treatment. Identification of prognostic biomarkers and targeting the biomarker genes will be a promising therapy.

METHODS

From our RNA-sequencing data of the oxidative phosphorylation (OXPHOS)-inhibition sensitive and OXPHOS-resistant cell lines, we found that the scaffolding protein caveolin 1 (CAV1) is highly expressed in the resistant group but not in the sensitive group. By comprehensive analysis of our RNA sequencing data, Whole Genome Bisulfite Sequencing (WGBS) data and public databases, we found that CAV1 is highly expressed in gliomas and its expression is positively related with pathological processes, higher CAV1 predicts shorter overall survival.

RESULTS

Further analysis indicated that (1) the differentiated genes in CAV1-high groups are enriched in immune infiltration and immune response; (2) CAV1 is positively correlated with tumor metastasis markers; (3) the methylation level of CAV1 promoters in glioma group is lower in higher stage than that in lower stage; (4) CAV1 is positively correlated with glioma stemness; (5) higher expression of CAV1 renders the glioma cells' resistant to oxidative phosphorylation inhibitors.

CONCLUSION

Therefore, we identified a key gene CAV1 and deciphered its function in glioma progression and prognosis, proposing that CAV1 may be a therapeutic target for gliomas.

Salinomycin sodium exerts anti diffuse large B-cell lymphoma activity through inhibition of LRP6-mediated Wnt/β-catenin and mTORC1 signaling

Low-density lipoprotein receptor-related protein-6 (LRP6) is overexpressed in various cancers. The small molecule salinomycin sodium inhibits LRP6. We observed a higher proportion of subjects with non-germinal center B (non-GCB) subtypes having high LRP6 expression than those with GCB subtypes by immunohistochemistry. The PCR and Western blot assays demonstrated increased LRP6 expression in non-GCB subtype cells. In addition, CCK-8 assays and transwell cell migration assays revealed that salinomycin sodium exhibited dose- and time-dependent inhibition of proliferation and migration in non-GCB subtype cells. Furthermore, Western blot assays showed that salinomycin sodium decreased the expression of Bcl2, while increasing the expression of Bax. Additionally, salinomycin sodium suppressed LRP6 expression, blocked LRP6 phosphorylation, and inhibited the Wnt/β-catenin and mTORC1 signaling pathways. Our results suggest that LRP6 is highly expressed in non-GCB subtype. Furthermore, salinomycin sodium inhibited LRP6 expression and the Wnt/β-catenin and mTORC1 signaling in non-GCB subtype cells, and displayed potent anticancer activity.

Role of Metabolism and Metabolic Pathways in Prostate Cancer

Prostate cancer (PCa) is the common cause of death in men. The pathophysiological factors contributing to PCa are not well known. PCa cells gain a protective mechanism via abnormal lipid signaling and metabolism. PCa cells modify their metabolism in response to an excessive intake of nutrients to facilitate advancement. Metabolic syndrome (MetS) is inextricably linked to the carcinogenic progression of PCa, which heightens the severity of the disease. It is hypothesized that changes in the metabolism of the mitochondria contribute to the onset of PCa. The studies of particular alterations in the progress of PCa are best accomplished by examining the metabolome of prostate tissue. Due to the inconsistent findings written initially, additional epidemiological research is required to identify whether or not MetS is an aspect of PCa. There is a correlation between several risk factors and the progression of PCa, one of which is MetS. The metabolic symbiosis between PCa cells and the tumor milieu and how this type of crosstalk may aid in the development of PCa is portrayed in this work. This review focuses on in-depth analysis and evaluation of the metabolic changes that occur within PCa, and also aims to assess the effect of metabolic abnormalities on the aggressiveness status and metabolism of PCa.

Metabolic reprogramming of cancer-associated fibroblasts in pancreatic cancer contributes to the intratumor heterogeneity of PET-CT

Intratumor heterogeneity of positron emission tomography-computed tomography (PET-CT) is reflected by variable ¹⁸F-fluorodeoxyglucose (FDG) uptake. Increasing evidence has shown that neoplastic and non-neoplastic components can affect the total ¹⁸F-FDG uptake in tumors. Cancer-associated fibroblasts (CAFs) is considered as the main non-neoplastic components in tumor microenvironment (TME) of pancreatic cancer. Our study aims to explore the impact of metabolic changes in CAFs on heterogeneity of PET-CT. A total of 126 patients with pancreatic cancer underwent PET-CT and endoscopic ultrasound elastography (EUS-EG) before treatment. High maximum standardized uptake value (SUVmax) from the PET-CT was positively correlated with the EUS-derived strain ratio (SR) and indicated poor prognosis of patients. In addition, single-cell RNA analysis showed that CAV1 affected glycolytic activity and correlated with glycolytic enzyme expression in fibroblasts in pancreatic cancer. We also observed the negative correlation between CAV1 and glycolytic enzyme expression in the tumor stroma by using immunohistochemistry (IHC) assay in the SUVmax-high and SUVmax-low groups of pancreatic cancer patients. Additionally, CAFs with high glycolytic activity contributed to pancreatic cancer cell migration, and blocking CAF glycolysis reversed this process, suggesting that glycolytic CAFs promote malignant biological behavior in pancreatic cancer. In summary, our research demonstrated that the metabolic reprogramming of CAFs affects total ¹⁸F-FDG uptake in tumors. Thus, an increase in glycolytic CAFs with decreased CAV1 expression promotes tumor progression, and high SUVmax may be a marker for therapy targeting the neoplastic stroma. Further studies should clarify the underlying mechanisms.

Importance of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs) in cancer cells

Background

In most regions, cancer ranks the second most frequent cause of death following cardiovascular disorders.

Aim

In this article, we review the various aspects of glycolysis with a focus on types of MCTs and the importance of lactate in cancer cells.

Results and Discussion

Metabolic changes are one of the first and most important alterations in cancer cells. Cancer cells use different pathways to survive, energy generation, growth, and proliferation compared to normal cells. The increase in glycolysis, which produces substances such as lactate and pyruvate, has an important role in metastases and invasion of cancer cells. Two important cellular proteins that play a role in the production and transport of lactate include lactate dehydrogenase and monocarboxylate transporters (MCTs). These molecules by their various isoforms and different tissue distribution help to escape the immune system and expansion of cancer cells under different conditions.

Druggable Metabolic Vulnerabilities Are Exposed and Masked during Progression to Castration Resistant Prostate Cancer

There is an urgent need for exploring new actionable targets other than androgen receptor to improve outcome from lethal castration-resistant prostate cancer. Tumor metabolism has reemerged as a hallmark of cancer that drives and supports oncogenesis. In this regard, it is important to understand the relationship between distinctive metabolic features, androgen receptor signaling, genetic drivers in prostate cancer, and the tumor microenvironment (symbiotic and competitive metabolic interactions) to identify metabolic vulnerabilities. We explore the links between metabolism and gene regulation, and thus the unique metabolic signatures that define the malignant phenotypes at given stages of prostate tumor progression. We also provide an overview of current metabolism-based pharmacological strategies to be developed or repurposed for metabolism-based therapeutics for castration-resistant prostate cancer.

CAV1 alleviated CaOx stones formation via suppressing autophagy-dependent ferroptosis

Background

Calcium oxalate (CaOx) is the most common type of kidney stone, but the mechanism of CaOx stones formation remains unclear. The injury of renal cells such as ferroptosis and autophagy has been considered a basis for stones formation.

Methods

We conducted transmission electron microscope (TEM), reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and C11-BODIPY analysis to explore whether CaOx could induce autophagy-dependent ferroptosis in vivo and in vitro. To explore the possible mechanism, we conducted bioinformatic analysis of patients with or without CaOx stones, Western blot and qPCR were used to identify the different genes we found in bioinformatic analysis.

Results

In our study, we found that CaOx could induce autophagy-dependent ferroptosis no matter in vivo or in vitro, which might finally lead to urolithiasis. Bioinformatic analysis of the GSE73680 dataset indicated that the expression of caveolin-1 (CAV1) was higher in control patients than CaOx stone patients, the STRING database indicated that CAV1 might interact with low density lipoprotein receptro-related protein 6 (LRP6), Gene Set Enrichment Analysis (GSEA) showed that the WNT pathway positively associated with the control group while negatively related to the stone group, and LRP6 was the core gene of the WNT pathway. Western blot found that CAV1, LRP6, and Wnt/β-Catenin were decreased in Human Kidney2 (HK2) cells stimulated with CaOx. Furthermore, the WNT pathway was considered to be involved in autophagy and ferroptosis.

Conclusions

We presumed that CAV1 could ameliorate autophagy-dependent ferroptosis through the LRP6/Wnt/β-Catenin axis, and finally alleviate CaOx stone formation.

Interplay between mechanics and signalling in regulating cell fate

Mechanical signalling affects multiple biological processes during development and in adult organisms, including cell fate transitions, cell migration, morphogenesis and immune responses. Here, we review recent insights into the mechanisms and functions of two main routes of mechanical signalling: outside-in mechanical signalling, such as mechanosensing of substrate properties or shear stresses; and mechanical signalling regulated by the physical properties of the cell surface itself. We discuss examples of how these two classes of mechanical signalling regulate stem cell function, as well as developmental processes in vivo. We also discuss how cell surface mechanics affects intracellular signalling and, in turn, how intracellular signalling controls cell surface mechanics, generating feedback into the regulation of mechanosensing. The cooperation between mechanosensing, intracellular signalling and cell surface mechanics has a profound impact on biological processes. We discuss here our understanding of how these three elements interact to regulate stem cell fate and development.

Mitochondrial Dysfunction and the Glycolytic Switch Induced by Caveolin-1 Phosphorylation Promote Cancer Cell Migration, Invasion, and Metastasis

Simple Summary

Caveolin-1 (CAV1) is a membrane protein that has been attributed a dual role in cancer, acting at early stages as a tumor suppressor and in later stages of the disease as a promoter of metastasis. In the latter case, enhanced expression of CAV1 favors the malignant phenotype and correlates with a poorer prognosis of the patients. Bearing in mind that the reprogramming of energy metabolism is required in cancer cells to meet both the bioenergetic and biosynthetic needs to sustain increased proliferation, migration, and invasion, we evaluated the metabolism of metastatic cells expressing or not CAV1. In this study, we show that the expression of CAV1 promotes in cancer cells a metabolic switch to an aerobic, glycolytic phenotype by blocking mitochondrial respiration.

Abstract

Cancer cells often display impaired mitochondrial function, reduced oxidative phosphorylation, and augmented aerobic glycolysis (Warburg effect) to fulfill their bioenergetic and biosynthetic needs. Caveolin-1 (CAV1) is a scaffolding protein that promotes cancer cell migration, invasion, and metastasis in a manner dependent on CAV1 phosphorylation on tyrosine-14 (pY14). Here, we show that CAV1 expression increased glycolysis rates, while mitochondrial respiration was reduced by inhibition of the mitochondrial complex IV. These effects correlated with increased reactive oxygen species (ROS) levels that favored CAV1-induced migration and invasion. Interestingly, pY14-CAV1 promoted the metabolic switch associated with increased migration/invasion and augmented ROS-inhibited PTP1B, a phosphatase that controls pY14 levels. Finally, the glycolysis inhibitor 2-deoxy-D-glucose reduced CAV1-enhanced migration in vitro and metastasis in vivo of murine melanoma cells. In conclusion, CAV1 promotes the Warburg effect and ROS production, which inhibits PTP1B to augment CAV1 phosphorylation on tyrosine-14, thereby increasing the metastatic potential of cancer cells.

Caveolin-1 Regulates Cellular Metabolism: A Potential Therapeutic Target in Kidney Disease

The kidney is an energy-consuming organ, and cellular metabolism plays an indispensable role in kidney-related diseases. Caveolin-1 (Cav-1), a multifunctional membrane protein, is the main component of caveolae on the plasma membrane. Caveolae are represented by tiny invaginations that are abundant on the plasma membrane and that serve as a platform to regulate cellular endocytosis, stress responses, and signal transduction. However, caveolae have received increasing attention as a metabolic platform that mediates the endocytosis of albumin, cholesterol, and glucose, participates in cellular metabolic reprogramming and is involved in the progression of kidney disease. It is worth noting that caveolae mainly depend on Cav-1 to perform the abovementioned cellular functions. Furthermore, the mechanism by which Cav-1 regulates cellular metabolism and participates in the pathophysiology of kidney diseases has not been completely elucidated. In this review, we introduce the structure and function of Cav-1 and its functions in regulating cellular metabolism, autophagy, and oxidative stress, focusing on the relationship between Cav-1 in cellular metabolism and kidney disease; in addition, Cav-1 that serves as a potential therapeutic target for treatment of kidney disease is also described.

LRP5 Promotes Gastric Cancer via Activating Canonical Wnt/β-Catenin and Glycolysis Pathways

The overactivation of canonical Wnt/β-catenin pathway is one of the main cascades for the initiation, progression, and recurrence of most human malignancies. As an indispensable coreceptor for the signaling transduction of the canonical Wnt/β-catenin pathway, LRP5 is up-regulated and exerts a carcinogenic role in most types of cancer. However, its expression level and role in gastric cancer (GC) has not been clearly elucidated. The current work showed that LRP5 was overexpressed in GC tissues and the expression of LRP5 was positively associated with the advanced clinical stages and poor prognosis. Ectopic expression of LRP5 enhanced the proliferation, invasiveness, and drug resistance of GC cells in vitro, and accelerated the tumor growth in nude mice, through activating the canonical Wnt/β-catenin signaling pathway and up-regulating aerobic glycolysis, thus increasing the energy supply for GC cells. Additionally, the expression of LRP5 and glycolysis-related genes showed an obviously positive correlation in GC tissues. By contrast, the exact opposite results were observed when the endogenous LRP5 was silenced in GC cells. Collectively, these results not only reveal the carcinogenic role of LRP5 during GC development through activating the canonical Wnt/β-catenin and glycolysis pathways, but also provide a valuable candidate for the diagnosis and treatment of human GC.

Wnt Signaling in Inner Blood-Retinal Barrier Maintenance

The retina is a light-sensing ocular tissue that sends information to the brain to enable vision. The blood-retinal barrier (BRB) contributes to maintaining homeostasis in the retinal microenvironment by selectively regulating flux of molecules between systemic circulation and the retina. Maintaining such physiological balance is fundamental to visual function by facilitating the delivery of nutrients and oxygen and for protection from blood-borne toxins. The inner BRB (iBRB), composed mostly of inner retinal vasculature, controls substance exchange mainly via transportation processes between (paracellular) and through (transcellular) the retinal microvascular endothelium. Disruption of iBRB, characterized by retinal edema, is observed in many eye diseases and disturbs the physiological quiescence in the retina's extracellular space, resulting in vision loss. Consequently, understanding the mechanisms of iBRB formation, maintenance, and breakdown is pivotal to discovering potential targets to restore function to compromised physiological barriers. These unraveled targets can also inform potential drug delivery strategies across the BRB and the blood-brain barrier into retinas and brain tissues, respectively. This review summarizes mechanistic insights into the development and maintenance of iBRB in health and disease, with a specific focus on the Wnt signaling pathway and its regulatory role in both paracellular and transcellular transport across the retinal vascular endothelium.

Regulation of the Low-Density Lipoprotein Receptor-Related Protein LRP6 and Its Association With Disease: Wnt/β-Catenin Signaling and Beyond

Wnt signaling plays crucial roles in development and tissue homeostasis, and its dysregulation leads to various diseases, notably cancer. Wnt/β-catenin signaling is initiated when the glycoprotein Wnt binds to and forms a ternary complex with the Frizzled and low-density lipoprotein receptor-related protein 5/6 (LRP5/6). Despite being identified as a Wnt co-receptor over 20 years ago, the molecular mechanisms governing how LRP6 senses Wnt and transduces downstream signaling cascades are still being deciphered. Due to its role as one of the main Wnt signaling components, the dysregulation or mutation of LRP6 is implicated in several diseases such as cancer, neurodegeneration, metabolic syndrome and skeletal disease. Herein, we will review how LRP6 is activated by Wnt stimulation and explore the various regulatory mechanisms involved. The participation of LRP6 in other signaling pathways will also be discussed. Finally, the relationship between LRP6 dysregulation and disease will be examined in detail.

Protein networks linking Warburg and reverse Warburg effects to cancer cell metabolism

It was 80 years after the Otto Warburg discovery of aerobic glycolysis, a major hallmark in the understanding of cancer. The Warburg effect is the preference of cancer cell for glycolysis that produces lactate even when sufficient oxygen is provided. "reverse Warburg effect" refers to the interstitial tissue communications with adjacent epithelium, that in the process of carcinogenesis, is needed to be explored. Among these cell-cell communications, the contact between epithelial cells; between epithelial cells and matrix; and between fibroblasts and inflammatory cells in the underlying matrix. Cancer involves dysregulation of Warburg and reverse Warburg cellular metabolic pathways. How these gene and protein-based regulatory mechanisms have functioned has been the basis for this review. The importance of the Warburg in oxidative phosphorylation suppression, with increased glycolysis in cancer growth and proliferation is emphasized. Studies that are directed at pathways that would be expected to shift cell metabolism to an increased oxidation and to a decrease in glycolysis are emphasized. Key enzymes required for oxidative phosphorylation, and affect the inhibition of fatty acid metabolism and glutamine dependence are conferred. The findings are of special interest to cancer pharmacotherapy. Studies described in this review are concerned with the effects of therapeutic modalities that are intimately related to the Warburg effect. These interactions described may be helpful as adjuvant therapy in controlling the process of proliferation and metastasis.

Wnt/β-catenin signaling in cancers and targeted therapies

Wnt/β-catenin signaling has been broadly implicated in human cancers and experimental cancer models of animals. Aberrant activation of Wnt/β-catenin signaling is tightly linked with the increment of prevalence, advancement of malignant progression, development of poor prognostics, and even ascendence of the cancer-associated mortality. Early experimental investigations have proposed the theoretical potential that efficient repression of this signaling might provide promising therapeutic choices in managing various types of cancers. Up to date, many therapies targeting Wnt/β-catenin signaling in cancers have been developed, which is assumed to endow clinicians with new opportunities of developing more satisfactory and precise remedies for cancer patients with aberrant Wnt/β-catenin signaling. However, current facts indicate that the clinical translations of Wnt/β-catenin signaling-dependent targeted therapies have faced un-neglectable crises and challenges. Therefore, in this study, we systematically reviewed the most updated knowledge of Wnt/β-catenin signaling in cancers and relatively targeted therapies to generate a clearer and more accurate awareness of both the developmental stage and underlying limitations of Wnt/β-catenin-targeted therapies in cancers. Insights of this study will help readers better understand the roles of Wnt/β-catenin signaling in cancers and provide insights to acknowledge the current opportunities and challenges of targeting this signaling in cancers.

Caveolin-1 increases glycolysis in pancreatic cancer cells and triggers cachectic states

In pancreatic cancer, autocrine insulin-like growth factor-1 (IGF-1) and paracrine insulin stimulate both IGF-1 receptor (IGF1R) and insulin receptor (IR) to increase tumor growth and glycolysis. In pancreatic cancer patients, cancer-induced glycolysis increases hepatic gluconeogenesis, skeletal muscle proteolysis, and fat lipolysis and, thereby, causes cancer cachexia. As a protein coexisting with IGF1R and IR, caveolin-1 (cav-1) may be involved in pancreatic cancer-induced cachexia. We undertook the present study to test this hypothesis. Out of wild-type MiaPaCa2 and AsPC1 human pancreatic cancer cell lines, we created their stable sub-lines whose cav-1 expression was diminished with RNA interference or increased with transgene expression. When these cells were studied in vitro, we found that cav-1 regulated IGF1R/IR expression and activation and also regulated cellular glycolysis. We transplanted the different types of MiaPaCa2 cells in growing athymic mice for 8 weeks, using intact athymic mice as tumor-free controls. We found that cav-1 levels in tumor grafts were correlated with expression levels of the enzymes that regulated hepatic gluconeogenesis, skeletal muscle proteolysis, and fat lipolysis in the respective tissues. When the tumors had original or increased cav-1, their carriers' body weight gain was less than the tumor-free reference. When cav-1 was diminished in tumors, the tumor carriers' body weight gain was not changed significantly, compared to the tumor-free reference. In conclusion, cav-1 in pancreatic cancer cells stimulated IGF1R/IR and glycolysis in the cancer cells and triggered cachectic states in the tumor carrier.

Caveola-forming proteins and prostate cancer

Caveolae are specialised and dynamic plasma membrane subdomains, involved in many cellular functions including endocytosis, signal transduction, mechanosensing and lipid storage, trafficking, and metabolism. Two protein families are indispensable for caveola formation and function, namely caveolins and cavins. Mutations of genes encoding these caveolar proteins cause serious pathological conditions such as cardiomyopathies, skeletal muscle diseases, and lipodystrophies. Deregulation of caveola-forming protein expression is associated with many types of cancers including prostate cancer. The distinct function of secretion of the prostatic fluid, and the unique metabolic phenotype of prostate cells relying on lipid metabolism as a main bioenergetic pathway further suggest a significant role of caveolae and caveolar proteins in prostate malignancy. Accumulating in vitro, in vivo, and clinical evidence showed the association of caveolin-1 with prostate cancer grade, stage, metastasis, and drug resistance. In contrast, cavin-1 was found to exhibit tumour suppressive roles. Studies on prostate cancer were the first to show the distinct function of the caveolar proteins depending on their localisation within the caveolar compartment or as cytoplasmic or secreted proteins. In this review, we summarise the roles of caveola-forming proteins in prostate cancer and the potential of exploiting them as therapeutic targets or biological markers.

Caveolin-1-mediated sphingolipid oncometabolism underlies a metabolic vulnerability of prostate cancer

Plasma and tumor caveolin-1 (Cav-1) are linked with disease progression in prostate cancer. Here we report that metabolomic profiling of longitudinal plasmas from a prospective cohort of 491 active surveillance (AS) participants indicates prominent elevations in plasma sphingolipids in AS progressors that, together with plasma Cav-1, yield a prognostic signature for disease progression. Mechanistic studies of the underlying tumor supportive onco-metabolism reveal coordinated activities through which Cav-1 enables rewiring of cancer cell lipid metabolism towards a program of 1) exogenous sphingolipid scavenging independent of cholesterol, 2) increased cancer cell catabolism of sphingomyelins to ceramide derivatives and 3) altered ceramide metabolism that results in increased glycosphingolipid synthesis and efflux of Cav-1-sphingolipid particles containing mitochondrial proteins and lipids. We also demonstrate, using a prostate cancer syngeneic RM-9 mouse model and established cell lines, that this Cav-1-sphingolipid program evidences a metabolic vulnerability that is targetable to induce lethal mitophagy as an anti-tumor therapy.

The regulatory pathways leading to stem-like cells underlie prostate cancer progression

Prostate cancer (PCa) is the most common cause of malignancy in males and the third leading cause of cancer mortality in the United States. The standard care for primary PCa with local invasive disease mainly is surgery and radiation. For patients with distant metastases, androgen deprivation therapy (ADT) is a gold standard. Regardless of a favorable outcome of ADT, patients inevitably relapse to an end-stage castration-resistant prostate cancer (CRPC) leading to mortality. Therefore, revealing the mechanism and identifying cellular components driving aggressive PCa is critical for prognosis and therapeutic intervention. Cancer stem cell (CSC) phenotypes characterized as poor differentiation, cancer initiation with self-renewal capabilities, and therapeutic resistance are proposed to contribute to the onset of CRPC. In this review, we discuss the role of CSC in CRPC with the evidence of CSC phenotypes and the possible underlying mechanisms.

Cellular effects and clinical implications of SLC2A3 copy number variation

SLC2A3 encodes the predominantly neuronal glucose transporter 3 (GLUT3), which facilitates diffusion of glucose across plasma membranes. The human brain depends on a steady glucose supply for ATP generation, which consequently fuels critical biochemical processes, such as axonal transport and neurotransmitter release. Besides its role in the central nervous system, GLUT3 is also expressed in nonneural organs, such as the heart and white blood cells, where it is equally involved in energy metabolism. In cancer cells, GLUT3 overexpression contributes to the Warburg effect by answering the cell's increased glycolytic demands. The SLC2A3 gene locus at chromosome 12p13.31 is unstable and prone to non-allelic homologous recombination events, generating multiple copy number variants (CNVs) of SLC2A3 which account for alterations in SLC2A3 expression. Recent associations of SLC2A3 CNVs with different clinical phenotypes warrant investigation of the potential influence of these structural variants on pathomechanisms of neuropsychiatric, cardiovascular, and immune diseases. In this review, we accumulate and discuss the evidence how SLC2A3 gene dosage may exert diverse protective or detrimental effects depending on the pathological condition. Cellular states which lead to increased energetic demand, such as organ development, proliferation, and cellular degeneration, appear particularly susceptible to alterations in SLC2A3 copy number. We conclude that better understanding of the impact of SLC2A3 variation on disease etiology may potentially provide novel therapeutic approaches specifically targeting this GLUT.

Involvement of intracellular caveolin-1 distribution in the suppression of antigen-induced mast cell activation by cationic liposomes

Cationic liposomes are commonly used as vectors to effectively introduce foreign genes into target cells. In another function, we recently showed that cationic liposomes bound to the mast cell surface suppress the degranulation induced by the cross-linking of high-affinity immunoglobulin E receptor in a time- and dose-dependent manner. This suppression is mediated by the impairment of the sustained level of intracellular Ca²⁺ concentration ([Ca²⁺ ]_i ) via the inhibition of store-operated Ca²⁺ entry. Further, we revealed that the mechanism underlying an impaired [Ca²⁺ ]_i increase is the inhibition of the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Yet, how cationic liposomes inhibit the PI3K-Akt pathway is still unclear. Here, we focused on caveolin-1, a major component of caveolae, which is reported to be involved in the activation of the PI3K-Akt pathway in various cell lines. In this study, we showed that caveolin-1 translocated from the cytoplasm to the plasma membrane after the activation of mast cells and colocalized with the p85 subunit of PI3K, which seemed to be essential for PI3K activity. Meanwhile, cationic liposomes suppressed the translocation of caveolin-1 to the plasma membrane and the colocalization of caveolin-1 with PI3K p85 also at the plasma membrane. This finding provides new information for the development of therapies using cationic liposomes against allergies.

Targeting FAT1 Inhibits Carcinogenesis, Induces Oxidative Stress and Enhances Cisplatin Sensitivity through Deregulation of LRP5/WNT2/GSS Signaling Axis in Oral Squamous Cell Carcinoma

FAT atypical cadherin 1 (FAT1) regulates cell-cell adhesion and extracellular matrix architecture, while acting as tumor suppressor or oncogene, context-dependently. Despite implication of FAT1 in several malignancies, its role in oral squamous cell carcinoma (OSCC) remains unclear. Herein, we document the driver-oncogene role of FAT1, and its mediation of cell-death evasion, proliferation, oncogenicity, and chemoresistance in OSCC. In-silica analyses indicate FAT1 mutations are frequent and drive head-neck SCC, with enhanced expression defining high-risk population and poor prognosis. We demonstrated aberrant FAT1 mRNA and protein expression in OSCC compared with non-cancer tissues, whereas loss-of-FAT1-function attenuates human primary SAS and metastatic HSC-3 OSCC cell viability, without affecting normal primary human gingival fibroblast cells. shFAT1 suppressed PCNA and upregulated BAX/BCL2 ratio in SAS and HSC-3 cells. Moreover, compared with wild-type cells, shFAT1 concomitantly impaired HSC-3 cell migration, invasion, and clonogenicity. Interestingly, while over-expressed FAT1 characterized cisplatin-resistance (CispR), shFAT1 synchronously re-sensitized CispR cells to cisplatin, enhanced glutathione (GSH)/GSH synthetase (GSS)-mediated oxidative stress and deregulated LRP5/WNT2 signaling. Concisely, FAT1 is an actionable driver-oncogene in OSCC and targeting FAT1 in patients with erstwhile cisplatin-resistant OSCC is therapeutically promising.

Caveolin-1 Y14 phosphorylation suppresses tumor growth while promoting invasion

Caveolin-1 is a transmembrane protein with both tumor promoter and suppressor functions that remain poorly understood. Cav1 phosphorylation by Src kinase on tyrosine 14 is closely associated with focal adhesion dynamics and tumor cell migration, however the role of pCav1 in vivo in tumor progression remains poorly characterized. Herein, we expressed phosphomimetic Y14D, wild type, and non-phosphorylatable Y14F forms of Cav1 in MDA-MB-435 cancer cells. Expression of Cav1Y14D reduced cell proliferation and induced the TP53 tumor suppressor. Ectopic expression in MDA-MB-435 cells of Y14 phosphorylatable Cav1 was required for induction of TP53 in response to oxidative stress. Cav1Y14D promotes an apparent reversal of the Warburg effect and markedly inhibited tumor growth in vivo. However, Cav1 induced pseudopodial recruitment of glycolytic enzymes, and time-lapse intravital imaging showed increased invadopodia protrusion and extravasation into blood vessels for Cav1WT and Y14D but not for Y14F. Our results suggest that Cav1 Y14 phosphorylation levels play a role in the conflicting demands on metabolic resources associated with cancer cell proliferation versus motility.

Human steroid sulfatase enhances aerobic glycolysis through induction of HIF1α and glycolytic enzymes

Human steroid sulfatase (STS) has been linked with poor prognosis in steroid-associated tumors and represents an important clinical target in cancers, yet the mechanism of STS-induced carcinogenesis remains unclear. To correlate STS with cancer metabolism, we determined the effects of STS on aerobic glycolysis. STS overexpression increased cellular levels of lactic acid, the final product of aerobic glycolysis. Moreover, STS suppressed the oxygen consumption rate (OCR), which represents mitochondrial respiration. Inhibition of STS by the specific inhibitor STX064 recovered STS-induced OCR repression and lactic acid over-production. DHEA, but not DHEA-S, suppressed the OCR level and enhanced lactic acid production. To understand the molecular mechanism of STS-induced cancer metabolism, we measured the expression of glycolytic enzymes hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2), which was highly upregulated by STS and DHEA at both protein and mRNA levels. HIF1α is a key mediator of aerobic glycolysis, and STS enhanced HIF1α promoter activity, mRNA expression, and protein expression. Down-regulation of HIF1α by siRNA suppressed the HK2 and PKM2 expression induced by both STS and DHEA. HIF1α siRNA also recovered the OCR repression and lactic acid over-production induced by both STS and DHEA. To explore the mechanism in vivo, we produced transgenic mice overexpressing STS and found that STS expression was particularly enhanced in the lung. Consistent with our in vitro results, the expression of HIF1α, HK2, and PKM2 was also increased in mouse lung tissues. In conclusion, we suggest that STS may induce aerobic glycolysis through enhancing HIF1α expression.

MiR-1180 from bone marrow MSCs promotes cell proliferation and glycolysis in ovarian cancer cells via SFRP1/Wnt pathway

Background

The ovarian cancer microenvironment is responsible for cancer cell growth and disease relapse. Bone marrow mesenchymal stem cells (BM-MSCs) play important roles in ovarian cancer, however, the mechanism of BM-MSCs inducing cell proliferation and glycolysis needs further research.

Methods

miRNA array was used to analyze the significant miRNAs. RT-qPCR was used to examine the level of miR-1180 and SFRP1. The western blotting was used to detect the protein level of SFRP1 and Wnt signal pathway. We utilized luciferase reporter assay to confirm the direct interaction of SFRP1 with miR-1180. MTT assay were employed to investigate the proliferation of ovarian cancer cells. ECAR, ATP assay were used to measure the glycolysis state of ovarian cancer cells.

Results

It was demonstrated that BM-MSCs promoted ovarian cancer cell proliferation and glycolysis. The miRNA profile from the BM-MSCs indicated that miR-1180 was up-regulated in the conditioned medium of BM-MSCs. MiR-1180 could accelerate ovarian cancer cell proliferation and glycolysis. We also found that up-regulation of miR-1180 activated Wnt signaling by targeting SFRP1 in ovarian cancer cells.

Conclusion

The study demonstrated that miR-1180 was a critical miRNA mediating BM-MSCs induced cell proliferation and glycolysis and could be a new target in ovarian cancer therapy.

MiR-644a Disrupts Oncogenic Transformation and Warburg Effect by Direct Modulation of Multiple Genes of Tumor-Promoting Pathways

Castration-resistant prostate cancer (CRPC) is defined by tumor microenvironment heterogeneity affecting intrinsic cellular mechanisms including dysregulated androgen signaling, aerobic glycolysis (Warburg effect), and aberrant activation of transcription factors including androgen receptor (AR) and c-Myc. Using in vitro, in vivo, and animal models, we find a direct correlation between miR-644a downregulation and dysregulation of essential cellular processes. MiR-644a downregulated expression of diverse tumor microenvironment drivers including c-Myc, AR coregulators, and antiapoptosis factors Bcl-xl and Bcl2. Moreover, miR-644a modulates epithelial-mesenchymal transition (EMT) by directly targeting EMT-promoting factors ZEB1, cdk6, and Snail. Finally, miR-644a expression suppresses the Warburg effect by direct targeting of c-Myc, Akt, IGF1R, and GAPDH expression. RNA sequencing analysis revealed an analogous downregulation of these factors in animal tumor xenografts. These data demonstrate miR-644a mediated fine-tuning of oncogenesis, stimulating pathways and resultant potentiation of enzalutamide therapy in CRPC patients. SIGNIFICANCE: This study demonstrates that miR-644a therapeutically influences the CRPC tumor microenvironment by suppressing androgen signaling and additional genes involved in metabolism, proliferation, Warburg effect, and EMT, to potentiate the enzalutamide therapy.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/8/1844/F1.large.jpg.

Biglycan Regulates MG63 Osteosarcoma Cell Growth Through a LPR6/β-Catenin/IGFR-IR Signaling Axis

Biglycan, a small leucine rich proteoglycan (SLRP), is an important participant in bone homeostasis and development as well as in bone pathology. In the present study biglycan was identified as a positive regulator of MG63 osteosarcoma cell growth (p ≤ 0.001). IGF-I was shown to increase biglycan expression (p ≤ 0.01), whereas biglycan-deficiency attenuated significantly both basal and IGF-I induced cell proliferation of MG63 cells (p ≤ 0.001; p ≤ 0.01, respectively). These effects were executed through the IGF-IR receptor whose activation was strongly attenuated (p ≤ 0.01) in biglycan-deficient MG63 cells. Biglycan, previously shown to regulate Wnt/β-catenin pathway, was demonstrated to induce a significant increase in β-catenin protein expression evident at cytoplasmic (p ≤ 0.01), membrane (p ≤ 0.01), and nucleus fractions in MG63 cells (p ≤ 0.05). As demonstrated by immunofluorescence, increase in β-catenin expression is attributed to co-localization of biglycan with the Wnt co-receptor low-density lipoprotein receptor-related protein 6 (LRP6) resulting in attenuated β-catenin degradation. Furthermore, applying anti-β-catenin and anti-pIGF-IR antibodies to MG-63 cells demonstrated a cytoplasmic and to the membrane interaction between these molecules that increased upon exogenous biglycan treatment. In parallel, the downregulation of biglycan significantly inhibited both basal and IGF-I-dependent ERK1/2 activation, (p ≤ 0.001). In summary, we report a novel mechanism where biglycan through a LRP6/β-catenin/IGF-IR signaling axis enhances osteosarcoma cell growth.

Wnt Signaling and Its Impact on Mitochondrial and Cell Cycle Dynamics in Pluripotent Stem Cells

The core transcriptional network regulating stem cell self-renewal and pluripotency remains an intense area of research. Increasing evidence indicates that modified regulation of basic cellular processes such as mitochondrial dynamics, apoptosis, and cell cycle are also essential for pluripotent stem cell identity and fate decisions. Here, we review evidence for Wnt regulation of pluripotency and self-renewal, and its connections to emerging features of pluripotent stem cells, including (1) increased mitochondrial fragmentation, (2) increased sensitivity to cell death, and (3) shortened cell cycle. We provide a general overview of the stem cell–specific mechanisms involved in the maintenance of these uncharacterized hallmarks of pluripotency and highlight potential links to the Wnt signaling pathway. Given the physiological importance of stem cells and their enormous potential for regenerative medicine, understanding fundamental mechanisms mediating the crosstalk between Wnt, organelle-dynamics, apoptosis, and cell cycle will be crucial to gain insight into the regulation of stemness.

The sweet trap in tumors: aerobic glycolysis and potential targets for therapy

Metabolic change is one of the hallmarks of tumor, which has recently attracted a great of attention. One of main metabolic characteristics of tumor cells is the high level of glycolysis even in the presence of oxygen, known as aerobic glycolysis or the Warburg effect. The energy production is much less in glycolysis pathway than that in tricarboxylic acid cycle. The molecular mechanism of a high glycolytic flux in tumor cells remains unclear. A large amount of intermediates derived from glycolytic pathway could meet the biosynthetic requirements of the proliferating cells. Hypoxia-induced HIF-1α, PI3K-Akt-mTOR signaling pathway, and many other factors, such as oncogene activation and tumor suppressor inactivation, drive cancer cells to favor glycolysis over mitochondrial oxidation. Several small molecules targeting glycolytic pathway exhibit promising anticancer activity both in vitro and in vivo. In this review, we will focus on the latest progress in the regulation of aerobic glycolysis and discuss the potential targets for the tumor therapy.

Lipid rafts disruption induces apoptosis by attenuating expression of LRP6 and survivin in triple negative breast cancer

Triple negative breast cancer is a clinically challenging subtype due to lack of biomarker for rational targeted therapy. Lipid rafts are cholesterol enriched rigid platforms, which colocalize signalling molecules of cancer progression. This study explores the effect of lipid rafts disruption by cholesterol depleting agent, MβCD on induction of apoptosis and expression of WNT receptor LRP6, survivin and common apoptotic markers in TNBC cell lines. The in vitro effect of lipid rafts disruption on viability, single cell reproductive ability, proliferation and migration were evaluated by MTT, clonogenic, BrdU incorporation and wound scratch assays, respectively. The morphological changes were assessed by tryphan blue, Wright and Giemsa staining; nuclear changes by Hoechst staining. The induction of apoptosis was evaluated by AO/EtBr staining, DNA damage and DNA fragmentation assays. Expression of Caveolin-1, LRP6, β-Catenin, Survivin, Bcl2, BAX, Caspase-3, Ki67 and c-myc were analyzed by PCR and Western blotting techniques. The lipid raft disruption resulted in reduction of the proliferation of MDA-MB 231 and MDA-MB 468 cells by 56.3 and 42.0%; survival fraction by 54.7 and 59.4%; migration by 44.3 and 48.4%, respectively. It also induced apoptosis by causing cell shrinkage, membrane blebbing, nuclear condensation, chromatin cleavage, oligonucleotide fragmentation with an apoptotic index of 59.1 and 46.6% in MDA-MB 231 and 468 cells, respectively. Further, it downregulated the expression of caveolin-1, LRP6, β-catenin, survivin, Bcl2, ki67, c-myc and upregulated BAX, caspase-3. The cholesterol supplementation enhanced the clonogenic potential and upregulated the expression of caveolin-1 and LRP6. The results underline a potential effect of lipid rafts disruption on induction of apoptosis in TNBC cells.

Proteomics profiling identifies induction of caveolin-1 in chronic lymphocytic leukemia cells by bone marrow stromal cells

Chronic lymphocytic leukemia (CLL) is an indolent B-cell malignancy in which cells reside in bone marrow, lymph nodes, and peripheral blood, each of which provides a unique microenvironment. Although the levels of certain proteins are reported to induce, changes in the CLL cell proteome in the presence of bone marrow stromal cells have not been elucidated. Reverse-phase protein array analysis of CLL cells before and 24 h after stromal cell interaction revealed changed levels of proteins that regulate cell cycle, gene transcription, and protein translation. The most hit with respect to both the extent of change in expression level and statistical significance was caveolin-1, which was confirmed with immunoblotting. Caveolin-1 mRNA levels were also upregulated in CLL cells after stromal cell interaction. The induction of caveolin-1 levels was rapid and occurred as early as 1 h. Studies to determine the significance of upregulated caveolin-1 levels in CLL lymphocytes are warranted.

The Glycolytic Switch in Tumors: How Many Players Are Involved?

Reprogramming of cellular metabolism is a hallmark of cancers. Cancer cells more readily use glycolysis, an inefficient metabolic pathway for energy metabolism, even when sufficient oxygen is available. This reliance on aerobic glycolysis is called the Warburg effect, and promotes tumorigenesis and malignancy progression. The mechanisms of the glycolytic shift in tumors are not fully understood. Growing evidence demonstrates that many signal molecules, including oncogenes and tumor suppressors, are involved in the process, but how oncogenic signals attenuate mitochondrial function and promote the switch to glycolysis remains unclear. Here, we summarize the current information on several main mediators and discuss their possible mechanisms for triggering the Warburg effect.

Baseline and longitudinal plasma caveolin-1 level as a biomarker in active surveillance for early-stage prostate cancer

OBJECTIVES

To evaluate the role of caveolin-1 (Cav-1) as a predictor of disease reclassification (DR) in men with early prostate cancer undergoing active surveillance (AS).

PATIENTS AND METHODS

We analysed archived plasma samples prospectively collected from patients with early prostate cancer in a single-institution AS study. Of 825 patients enrolled, 542 had ≥1 year of follow-up. Baseline and longitudinal plasma Cav-1 levels were measured using an enzyme-linked immunosorbent assay. Tumour volume or Gleason grade increases were criteria for DR. Logistic regression analyses were used to assess associations between clinicopathological characteristics and reclassification risk.

RESULTS

In 542 patients, 480 (88.6%) had stage cT1c disease, 542 (100.0%) had a median prostate-specific antigen level of 4.1 ng/mL, and 531 (98.0%) had a median Cancer of the Prostate Risk Assessment score of 1. In all, 473 (87.3%) had a Gleason score of 3+3. After a median of 3.1 years of follow-up, disease was reclassified in 163 patients (30.1%). The mean baseline Cav-1 level was 2.2 ± 8.5 ng/mL and the median 0.2 ng/mL (range, 0-85.5 ng/mL). In univariate analysis, baseline Cav-1 was a significant predictor for risk of DR (odds ratio [OR] 1.82, 95% confidence interval [CI] 1.24-2.65; P = 0.002). In multivariate analysis, with adjustments for age, tumour length, group risk stratification and number of positive cores, reclassification risk associated with Cav-1 remained significant (OR 1.91, 95% CI 1.28-2.84; P = 0.001).

CONCLUSION

Baseline plasma Cav-1 level was an independent predictor of disease classification. New methods for refining AS and intervention may result.

Milk's Role as an Epigenetic Regulator in Health and Disease

It is the intention of this review to characterize milk's role as an epigenetic regulator in health and disease. Based on translational research, we identify milk as a major epigenetic modulator of gene expression of the milk recipient. Milk is presented as an epigenetic "doping system" of mammalian development. Milk exosome-derived micro-ribonucleic acids (miRNAs) that target DNA methyltransferases are implicated to play the key role in the upregulation of developmental genes such as FTO, INS, and IGF1. In contrast to miRNA-deficient infant formula, breastfeeding via physiological miRNA transfer provides the appropriate signals for adequate epigenetic programming of the newborn infant. Whereas breastfeeding is restricted to the lactation period, continued consumption of cow's milk results in persistent epigenetic upregulation of genes critically involved in the development of diseases of civilization such as diabesity, neurodegeneration, and cancer. We hypothesize that the same miRNAs that epigenetically increase lactation, upregulate gene expression of the milk recipient via milk-derived miRNAs. It is of critical concern that persistent consumption of pasteurized cow's milk contaminates the human food chain with bovine miRNAs, that are identical to their human analogs. Commercial interest to enhance dairy lactation performance may further increase the epigenetic miRNA burden for the milk consumer.

Drug discovery strategies in the field of tumor energy metabolism: Limitations by metabolic flexibility and metabolic resistance to chemotherapy

The search for new drugs capable of blocking the metabolic vulnerabilities of human tumors has now entered the clinical evaluation stage, but several projects already failed in phase I or phase II. In particular, very promising in vitro studies could not be translated in vivo at preclinical stage and beyond. This was the case for most glycolysis inhibitors that demonstrated systemic toxicity. A more recent example is the inhibition of glutamine catabolism in lung adenocarcinoma that failed in vivo despite a strong addiction of several cancer cell lines to glutamine in vitro. Such contradictory findings raised several questions concerning the optimization of drug discovery strategies in the field of cancer metabolism. For instance, the cell culture models in 2D or 3D might already show strong limitations to mimic the tumor micro- and macro-environment. The microenvironment of tumors is composed of cancer cells of variegated metabolic profiles, supporting local metabolic exchanges and symbiosis, but also of immune cells and stroma that further interact with and reshape cancer cell metabolism. The macroenvironment includes the different tissues of the organism, capable of exchanging signals and fueling the tumor 'a distance'. Moreover, most metabolic targets were identified from their increased expression in tumor transcriptomic studies, or from targeted analyses looking at the metabolic impact of particular oncogenes or tumor suppressors on selected metabolic pathways. Still, very few targets were identified from in vivo analyses of tumor metabolism in patients because such studies are difficult and adequate imaging methods are only currently being developed for that purpose. For instance, perfusion of patients with [¹³C]-glucose allows deciphering the metabolomics of tumors and opens a new area in the search for effective targets. Metabolic imaging with positron emission tomography and other techniques that do not involve [¹³C] can also be used to evaluate tumor metabolism and to follow the efficiency of a treatment at a preclinical or clinical stage. Relevant descriptors of tumor metabolism are now required to better stratify patients for the development of personalized metabolic medicine. In this review, we discuss the current limitations in basic research and drug discovery in the field of cancer metabolism to foster the need for more clinically relevant target identification and validation. We discuss the design of adapted drug screening assays and compound efficacy evaluation methods for the discovery of innovative anti-cancer therapeutic approaches at the level of tumor energetics. This article is part of a Special Issue entitled Mitochondria in Cancer, edited by Giuseppe Gasparre, Rodrigue Rossignol and Pierre Sonveaux.

Shared gene expression patterns in mesenchymal progenitors derived from lung and epidermis in pulmonary arterial hypertension: identifying key pathways in pulmonary vascular disease

Rapid access to lung-derived cells from stable subjects is a major challenge in the pulmonary hypertension field, given the relative contraindication of lung biopsy. In these studies, we sought to demonstrate the importance of evaluating a cell type that actively participates in disease processes, as well as the potential to translate these findings to vascular beds in other nonlung tissues, in this instance perivascular skin mesenchymal cells (MCs). We utilized posttransplant or autopsy lung explant-derived cells (ABCG2-expressing mesenchymal progenitor cells [MPCs], fibroblasts) and skin-derived MCs to test the hypothesis that perivascular ABCG2 MPCs derived from pulmonary arterial hypertension (PAH) patient lung and skin would express a gene profile reflective of ongoing vascular dysfunction. By analyzing the genetic signatures and pathways associated with abnormal ABCG2 lung MPC phenotypes during PAH and evaluating them in lung- and skin-derived MCs, we have identified potential predictor genes for detection of PAH as well as a targetable mechanism to restore MPCs and microvascular function. These studies are the first to explore the utility of expanding the study of ABCG2 MPC regulation of the pulmonary microvasculature to the epidermis, in order to identify potential markers for adult lung vascular disease, such as PAH.