Role of caveolin-1 in hepatocellular carcinoma arising from non-alcoholic fatty liver disease

Proanthocyanidins-Based Synbiotics as a Novel Strategy for Nonalcoholic Fatty Liver Disease (NAFLD) Risk Reduction

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, is a spectrum of liver abnormalities ranging from steatosis to nonalcoholic steatohepatitis (NASH) characterized by excessive lipid accumulation. The prevalence of NAFLD is predicted to increase rapidly, demanding novel approaches to reduce the global NAFLD burden. Flavonoids, the most abundant dietary polyphenols, can reduce the risk of NAFLD. The majority of dietary flavonoids are proanthocyanidins (PACs), which are oligomers and polymers of the flavonoid sub-group flavan-3-ols. The efficacy of PAC in reducing the NAFLD risk can be significantly hindered by low bioavailability. The development of synbiotics by combining PAC with probiotics may increase effectiveness against NAFLD by biotransforming PAC into bioavailable metabolites. PAC and probiotic bacteria are capable of mitigating steatosis primarily through suppressing de novo lipogenesis and promoting fatty acid β-oxidation. PAC and probiotic bacteria can reduce the progression of steatosis to NASH mainly through ameliorating hepatic damage and inflammation induced by hepatic oxidative stress, endoplasmic reticulum stress, and gut microbiota dysbiosis. Synbiotics of PAC are superior in reducing the risk of NAFLD compared to independent administration of PAC and probiotics. The development of PAC-based synbiotics can be a novel strategy to mitigate the increasing incidence of NAFLD.

Caveolin-1 is critical for hepatic iron storage capacity in the development of nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with disordered lipid and iron metabolism. Our previous study has substantiated the pivotal role of Caveolin-1 (Cav-1) in protecting hepatocytes and mediating iron metabolism in the liver. This study aimed to explore the specific mechanisms underlying the regulation of iron metabolism by Cav-1 in NAFLD.

METHODS

Hepatocyte-specific Cav-1 overexpression mice and knockout mice were used in this study. Cav-1-knockdown of RAW264.7 cells and mouse primary hepatocytes were performed to verify the changes in vitro. Moreover, a high-fat diet and palmitic acid plus oleic acid treatment were utilized to construct a NAFLD model in vivo and in vitro, respectively, while a high-iron diet was used to construct an in vivo iron overload model. Besides, iron concentration, the expression of Cav-1 and iron metabolism-related proteins in liver tissue or serum were detected using iron assay kit, Prussian blue staining, Western blotting, immunofluorescence staining, immunohistochemical staining and ELISA. The related indicators of lipid metabolism and oxidative stress were evaluated by the corresponding reagent kit and staining.

RESULTS

Significant disorder of lipid and iron metabolism occurred in NAFLD. The expression of Cav-1 was decreased in NAFLD hepatocytes (P < 0.05), accompanied by iron metabolism disorder. Cav-1 enhanced the iron storage capacity of hepatocytes by activating the ferritin light chain/ferritin heavy chain pathway in NAFLD, subsequently alleviating the oxidative stress induced by excess ferrous ions in the liver. Further, CD68+CD163+ macrophages expressing Cav-1 were found to accelerate iron accumulation in the liver, which was contrary to the effect of Cav-1 in hepatocytes. Positive correlations were also observed between the serum Cav-1 concentration and the serum iron-related protein levels in NAFLD patients and healthy volunteers (P < 0.05).

CONCLUSIONS

These findings confirm that Cav-1 is an essential target protein that regulates iron and lipid metabolic homeostasis. It is a pivotal molecule for predicting and protecting against the development of NAFLD.

Caveolin-1 protects against liver damage exacerbated by acetaminophen in non-alcoholic fatty liver disease by inhibiting the ERK/HIF-1α pathway

Acetaminophen (APAP) is a common antipyretic and analgesic drug that can cause long-term liver damage after an overdose. Non-alcoholic fatty liver disease (NAFLD) increases susceptibility to APAP. In NAFLD, excessive accumulation of lipids leads to an abnormal increase in hypoxia-inducible factor-1α (HIF-1α). Caveolin-1 (CAV1) may protect against NAFLD by inhibiting HIF-1α. This research aimed to determine whether CAV1 could attenuate APAP-exacerbated liver injury in NAFLD by inhibiting oxidative stress involving HIF-1α. In this study, 7-week-old C57BL/6 mice were fed a high-fat diet (HFD) for eight weeks, followed by the instillation of APAP. Levels of oxidative stress and liver lipid deposition were determined, and p-ERK1/2 and HIF-1α protein expression were measured by the Western blot (WB) method. In the APAP-treated group, the level of CAV1 was decreased, while the levels of HIF-1α and reactive oxygen species (ROS) were significantly increased. AML12 cells were treated with a mixture of palmitic acid (PA) and oleic acid (OA) (1:2 mix) for 48 h, and APAP was added for the last 24 h. Overexpression of CAV1 in AML12 cells significantly inhibited the expression of ROS and HIF-1α. And the results of immunofluorescence after treatment with CAV1-SiRNA showed that the HIF-1α levels were significantly increased in mitochondria. In conclusion, our experimental results suggest that CAV1 has a protective function in the fatty liver based on preventing oxidative stress, which involves HIF-1α. Thus, upregulation of CAV1 may attenuate APAP-exacerbated liver injury in NAFLD.

Tumor-Suppressor Role of the α1-Na/K-ATPase Signalosome in NASH Related Hepatocellular Carcinoma †

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality worldwide, with an estimate of 0.84 million cases every year. In Western countries, because of the obesity epidemic, non-alcoholic steatohepatitis (NASH) has become the major cause of HCC. Intriguingly, the molecular mechanisms underlying tumorigenesis of HCC from NASH are largely unknown. We hypothesized that the growing uncoupled metabolism during NASH progression to HCC, manifested by lower cell redox status and an apoptotic ‘switch’ activity, follows a dysregulation of α1-Na/K-ATPase (NKA)/Src signalosome. Our results suggested that in NASH-related malignancy, α1-NKA signaling causes upregulation of the anti-apoptotic protein survivin and downregulation of the pro-apoptotic protein Smac/DIABLO via the activation of the PI3K → Akt pro-survival pathway with concomitant inhibition of the FoxO3 circuit, favoring cell division and primary liver carcinogenesis. Signalosome normalization using an inhibitory peptide resets apoptotic activity in malignant cells, with a significant decrease in tumor burden in vivo. Therefore, α1-NKA signalosome exercises in HCC the characteristic of a tumor suppressor, suggesting α1-NKA as a putative target for clinical therapy.

Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.

Elevated Expression of CAV1 is Associated with Unfavorable Prognosis of Patients with Breast Cancer Who Undergo Surgery and Neoadjuvant Chemotherapy

INTRODUCTION

Neoadjuvant chemotherapy (NACT), which is standard treatment for locally advanced breast cancer, improves the resectability of patients with early breast cancer and reduces the extent of breast and axillary surgery. Caveolin-1 (CAV1) is implicated in human cancers, although its utility for cancer prognosis is unknown. Here, we investigated the expression of CAV1 in breast cancer tissues to evaluate its prognostic significance on patients with breast cancer administered NACT.

METHODS

CAV1 expression in 80 breast cancer tissue samples was evaluated using immunohistochemistry (IHC). The association between CAV1 levels and clinical factors was analyzed using the chi-square test and that between CAV1 and prognosis was evaluated using multivariate Cox regression and Kaplan-Meier analyses.

RESULTS

High levels of CAV1 were significantly associated with survival, and patients with overexpression of CAV1 had a poor prognosis. Adjusted multivariate Cox regression analyses revealed that a high level of CAV1 expression was an independent, significant prognostic factor for patients with breast cancer treated with NACT.

DISCUSSION

Overexpression of CAV1 in patients with breast cancer administered NACT was associated with shorter disease-free survival and overall survival. Therefore, high levels of CAV1 may serve as a prognostic biomarker for such patients.

NONO promotes hepatocellular carcinoma progression by enhancing fatty acids biosynthesis through interacting with ACLY mRNA

Background

Dysregulation of fatty acid (FA) metabolism is involved in hepatocellular carcinoma (HCC) development. Non-POU domain-containing octamer binding protein (NONO), known as the component of nuclear paraspeckles, has recently been found to promote HCC progression. In this study, we investigated the functions of NONO in regulating de novo FA synthesis and its underling mechanism during HCC development.

Methods

The roles of NONO in HCC development by applying gene function loss analysis in HCC cells were detected by quantitative real-time polymerase chain reaction, cell proliferation, and cell invasion assays. The underlying mechanism of NONO in HCC development was examined by western blotting, subcellular fractionation, RNA-binding protein immunoprecipitation-sequencing, chromatin immunoprecipitation, co-immunoprecipitation and mass spectrometry. The effect of NONO on tumorigenesis in vivo was performed with a subcutaneous xenograft mouse model of HCC.

Results

NONO promotes HCC progression by interacting with and increasing ATP-citrate lyase (ACLY) mRNA to enhance FA biosynthesis. Furthermore, NONO promotes ACLY expression through enhancing nuclear ACLY mRNA stability in Diethylnitrosamine-stimulated HCC cells, not related to nuclear paraspeckles. Moreover, we find that NONO/SFPQ (Splicing factor proline and glutamine rich) heterodimer is essential for NONO interacting with ACLY mRNA in DEN stimulated HCC cells. In addition, NONO, Insulin like growth factor 2 mRNA binding protein 1 (IGF2BP1) and ACLY expressions contribute HCC development in mice and are related to poor survival.

Conclusion

NONO promotes HCC progression by enhancing FA biosynthesis through interacting with ACLY mRNA and provide a novel potential target for HCC therapy.

Oleate acid-stimulated HMMR expression by CEBPα is associated with nonalcoholic steatohepatitis and hepatocellular carcinoma

Non-alcoholic steatohepatitis (NASH) is a type of nonalcoholic fatty liver disease and has become a major risk factor for hepatocellular carcinoma (HCC). However, the underlying pathophysiological mechanisms are still elusive. Here, we identify hyaluronan-mediated motility receptor (HMMR) as a critical gene associated with NASH/HCC by combination of bioinformatic analysis and functional experiments. Analysis of differentially expressed genes (DEGs) between normal controls and NASH/HCC identified 5 hub genes (HMMR, UBE2T, TYMS, PTTG1 and GINS2). Based on the common DEGs, analyses of univariate and multivariate Cox regression and the area under the curve (AUC) value of the receiver operating characteristic (ROC) indicate that HMMR is the most significant gene associated with NASH/HCC among five hub genes. Oleate acid (OA), one of fatty acids that induce cellular adipogenesis, stimulates HMMR expression via CCAAT/enhancer-binding protein α (CEBPα). CEBPα increases the expression of HMMR through binding to its promoter. HMMR promotes HCC cell proliferation in vitro via activation of G1/S and G2/M checkpoint transitions, concomitant with a marked increase of the positive cell cycle regulators, including cyclin D1, cyclin E, and cyclin B1. Knockdown of HMMR suppresses HCC tumor growth in nude mice. Our study identifies an important role of HMMR in NASH/HCC, and suggests that HMMR may be a useful target for therapy and prognostic prediction of NASH/HCC patients.

The Genetic and Endoplasmic Reticulum-Mediated Molecular Mechanisms of Primary Open-Angle Glaucoma

Glaucoma is a heterogenous, chronic, progressive group of eye diseases, which results in irreversible loss of vision. There are several types of glaucoma, whereas the primary open-angle glaucoma (POAG) constitutes the most common type of glaucoma, accounting for three-quarters of all glaucoma cases. The pathological mechanisms leading to POAG pathogenesis are multifactorial and still poorly understood, but it is commonly known that significantly elevated intraocular pressure (IOP) plays a crucial role in POAG pathogenesis. Besides, genetic predisposition and aggregation of abrogated proteins within the endoplasmic reticulum (ER) lumen and subsequent activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent unfolded protein response (UPR) signaling pathway may also constitute important factors for POAG pathogenesis at the molecular level. Glaucoma is commonly known as a ‘silent thief of sight’, as it remains asymptomatic until later stages, and thus its diagnosis is frequently delayed. Thereby, detailed knowledge about the glaucoma pathophysiology is necessary to develop both biochemical and genetic tests to improve its early diagnosis as well as develop a novel, ground-breaking treatment strategy, as currently used medical therapies against glaucoma are limited and may evoke numerous adverse side-effects in patients.

Tenascin C in the Tumor-Nerve Microenvironment Enhances Perineural Invasion and Correlates With Locoregional Recurrence in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Perineural invasion is common in pancreatic ductal adenocarcinoma (PDAC) and worsens the postoperative prognosis. Tenascin C (TNC), an extracellular matrix glycoprotein, modulates tumor progression. We evaluated the functional roles of TNC, especially in perineural invasion of PDAC.

METHODS

We examined immunohistochemical TNC expression in 78 resected PDAC specimens. The relationships between TNC expression and clinicopathological features were retrospectively analyzed. Interactions between cancer cells and nerves with TNC supplementation were investigated using an in vitro coculture model with PDAC cell line and mouse dorsal root ganglion (DRG).

RESULTS

Tenascin C expression was predominant in perineural sites at the invasive tumor front. High perineural TNC expression in 30 patients (38%) was associated with perineural invasion, pathological T stage ≥3, and postoperative locoregional recurrence. High TNC expression was independently associated with postoperative, poor recurrence-free survival by multivariate analysis. In the in vitro coculture model, a TNC-rich matrix enhanced both PDAC cell colony extensions toward nerves and DRG axonal outgrowth toward cancer cell colonies, whereas TNC did not affect axonal outgrowth or cancer cell proliferation in separately cultured DRG and PDAC cells.

CONCLUSIONS

Strong perineural TNC expression indicated poor prognosis with locoregional recurrence. The neurotropism of TNC-induced PDAC suggests that TNC is a potential PDAC therapeutic target.

Caveolin-1 dictates ferroptosis in the execution of acute immune-mediated hepatic damage by attenuating nitrogen stress

Ferroptosis is a new regulated cells death manner defined as results of iron-dependent accumulation of lipid peroxidation. However, the specific mechanisms of regulating ferroptosis remain unclear. In our present study, we demonstrated that Caveolin-1 (Cav-1) played a central role in protecting hepatocytes against ferroptosis in autoimmunity-mediated hepatitis (AIH). The down-regulated Cav-1 in liver tissues, accompanied by ferroptotic events and RNS production, were contributed to the outcome of ConA-induced hepatic damage, which were rescued by ferrostatin-1 (an inhibitor of ferroptosis) in vivo and in vitro. Additionally, Cav-1 deficiency aggravated ConA-induced hepatocellular death and ferroptosis associated with excessive nitrogen stress response. Short hairpin RNA of Cav-1 in hepatocytes promoted ferroptosis and nitrative stress in response to erastin in vitro, which was ameliorated by Cav-1 over-expression. Meanwhile, administration of the iNOS inhibitor (1400W) or ONOO^- scavenger (Fe-TMPyP), diminished reactive nitrogen species (RNS), remarkably reduced hepatocytes ferroptosis and attenuated ConA-induced liver damage. Furthermore, immune inhibition by gadolinium chloride (GdCl₃), a well-known Kupffer cell depletor, elevated hepatic Cav-1 but inhibited ferroptosis and nitrative stress under ConA exposure. In conclusion, these data revealed a novel molecular mechanism of ferroptosis with the Cav-1 regulation was essential for pathogenesis of ConA-induced hepatitis. Downstream of Cav-1, RNS-mediated ferroptosis was a pivotal step that drives the execution of acute immune-mediated hepatic damage.

Role of lipids in pathophysiology, diagnosis and therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive and widespread cancer. Patients with liver cirrhosis of different aetiologies are at a risk to develop HCC. It is important to know that in approximately 20% of cases primary liver tumors arise in a non-cirrhotic liver. Lipid metabolism is variable in patients with chronic liver diseases, and lipid metabolites involved therein do play a role in the development of HCC. Of note, lipid composition of carcinogenic tissues differs from non-affected liver tissues. High cholesterol and low ceramide levels in the tumors protect the cells from oxidative stress and apoptosis, and do also promote cell proliferation. So far, detailed characterization of the mechanisms by which lipids enable the development of HCC has received little attention. Evaluation of the complex roles of lipids in HCC is needed to better understand the pathophysiology of HCC, the later being of paramount importance for the development of urgently needed therapeutic interventions. Disturbed hepatic lipid homeostasis has systemic consequences and lipid species may emerge as promising biomarkers for early diagnosis of HCC. The challenge is to distinguish lipids specifically related to HCC from changes simply related to the underlying liver disease. This review article discusses aberrant lipid metabolism in patients with HCC.

Lithium effects on vesicular trafficking in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the most commonly malignant tumors worldwide, characterized by the presence of many heterogeneous molecular cell events that contribute to tumor growth and progression. Endocytic processes are intimately involved in various pathological conditions, including cancer, since they interface with various cellular signaling programs. The ability of lithium to induce cell death and autophagy and affect cell proliferation and intracellular signaling has been shown in various experimental tumor models. The aim of this study was to evaluate the effects of lithium on vesicular transport in hepatocellular carcinoma cells. Using transmission electron microscopy we have characterized the endocytic apparatus in hepatocellular carcinoma-29 (HCC-29) cells in vivo and detailed changes in endocytotic vesicles after 20 mM lithium carbonate administration. Immunofluorescent analysis was used to quantify cells positive for EEA1-positive early endosomes, Rab11-positive recycling endosomes and Rab7-positive late endosomes. Lithium treatment caused an increase in EEA1- and Rab11-positive structures and a decrease in Rab7-positive vesicles. Thus, lithium affects diverse endocytic pathways in HCC-29 cells which may modulate growth and development of hepatocellular carcinoma.

Non-Cirrhotic Liver is Associated with Poor Prognosis of Hepatocellular Carcinoma: A Literature Review

Primary hepatocellular carcinoma (HCC) is the fifth most frequently reported malignancy, and it is also the second most common cause of cancer-related deaths worldwide. Although most HCC cases have been reported to develop from cirrhosis, accumulating data suggest that HCC is also closely related to non-cirrhotic chronic liver disease. Traditionally, HCC was thought to develop mostly from cirrhosis; however, an increasing number of reports have found that HCC can develop directly from inflammation without cirrhosis. The incidence of HCC in non-cirrhotic liver (HCC-NCL) is high, especially in developed countries. Studies have found that the most common cause of HCC-NCL is neglected fatty liver disease. This type of HCC has unique clinical characteristics and is closely related to metabolic disorders. Unfortunately, the prevention of HCC-NCL has not received enough attention worldwide, and there is also a lack of specific screening methods and clinical guidelines. This article mainly reviews the etiology, incidence, clinical characteristics, and screening markers of HCC-NCL to improve the understanding and prevention of this disease.

Caveolin-1: a multifaceted driver of breast cancer progression and its application in clinical treatment

Human breast cancer is one of the most frequent cancer diseases and causes of death among female population worldwide. It appears at a high incidence and has a high malignancy, mortality, recurrence rate and poor prognosis. Caveolin-1 (Cav1) is the main component of caveolae and participates in various biological events. More and more experimental studies have shown that Cav1 plays a critical role in the progression of breast cancer including cell proliferation, apoptosis, autophagy, invasion, migration and breast cancer metastasis. Besides, Cav1 has been found to be involved in chemotherapeutics and radiotherapy resistance, which are still the principal problems encountered in clinical breast cancer treatment. In addition, stromal Cav1 may be a potential indicator for breast cancer patients' prognosis. In the current review, we cover the state-of-the-art study, development and progress on Cav1 and breast cancer, altogether describing the role of Cav1 in breast cancer progression and application in clinical treatment, in the hope of providing a basis for further research and promoting CAV1 gene as a potential target to diagnose and treat aggressive breast cancers.

Role of caveolin-1 in hepatocellular carcinoma arising from non-alcoholic fatty liver disease

The molecular features of hepatocellular carcinoma arising from non-alcoholic fatty liver disease (NAFLD-HCC) are not well known. In this study, we investigated the mechanism by which NAFLD-HCC survives in a fat-rich environment. We found that caveolin (CAV)-1 was overexpressed in clinical specimens from NAFLD-HCC patients. HepG2, HLE, and HuH-7 HCC cell lines showed decreased proliferation in the presence of the saturated fatty acids palmitic acid and stearic acid, although only HLE cells expressed high levels of CAV-1. HLE cells treated with oleic acid (OA) showed robust proliferation, whereas CAV-null HepG2 cells showed reduced proliferation and increased apoptosis. CAV-1 knockdown in HLE cells attenuated the OA-induced increase in proliferation and enhanced apoptosis. Liquid chromatography-tandem mass spectrometry analysis revealed that the levels of OA-containing ceramide, a pro-apoptotic factor, were higher in HepG2 and CAV-1-deficient HLE cells than in HLE cells, suggesting that CAV-1 inhibits apoptosis by decreasing the level of OA-containing ceramide. These results indicate that CAV-1 is important for NAFLD-HCC survival in fatty acid-rich environments and is a potential therapeutic target.