Conophylline suppresses hepatic stellate cells and attenuates thioacetamide-induced liver fibrosis in rats

Molecular Mechanism Pathways of Natural Compounds for the Treatment of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and its incidence continues to increase each year. Yet, there is still no definitive drug that can stop its development. This review focuses mainly on lipotoxicity, oxidative stress, inflammation, and intestinal flora dysbiosis to understand NAFLD's pathogenesis. In this review, we used NCBI's PubMed database for retrieval, integrating in vivo and in vitro experiments to reveal the therapeutic effects of natural compounds on NAFLD. We also reviewed the mechanisms by which the results of these experiments suggest that these compounds can protect the liver from damage by modulating inflammation, reducing oxidative stress, decreasing insulin resistance and lipid accumulation in the liver, and interacting with the intestinal microflora. The natural compounds discussed in these papers target a variety of pathways, such as the AMPK pathway and the TGF-β pathway, and have significant therapeutic effects. This review aims to provide new possible therapeutic lead compounds and references for the development of novel medications and the clinical treatment of NAFLD. It offers fresh perspectives on the development of natural compounds in preventing and treating NAFLD.

Potential of Compounds Originating from the Nature to Act in Hepatocellular Carcinoma Therapy by Targeting the Tumor Immunosuppressive Microenvironment: A Review

Hepatocellular carcinoma (HCC), the most prevalent subtype of liver cancer, is the second main reason for cancer-related deaths worldwide. In recent decades, sufficient evidence supported that immunotherapy was a safe and effective treatment option for HCC. However, tolerance and frequent recurrence and metastasis occurred in patients after immunotherapy due to the complicated crosstalk in the tumor immunosuppressive microenvironment (TIME) in HCC. Therefore, elucidating the TIME in HCC and finding novel modulators to target TIME for attenuating immune suppression is critical to optimize immunotherapy. Recently, studies have shown the potentially immunoregulatory activities of natural compounds, characterized by multiple targets and pathways and low toxicity. In this review, we concluded the unique role of TIME in HCC. Moreover, we summarized evidence that supports the hypothesis of natural compounds to target TIME to improve immunotherapy. Furthermore, we discussed the comprehensive mechanisms of these natural compounds in the immunotherapy of HCC. Accordingly, we present a well-grounded review of the naturally occurring compounds in cancer immunotherapy, expecting to shed new light on discovering novel anti-HCC immunomodulatory drugs from natural sources.

Traditional Chinese medicine: An important source for discovering candidate agents against hepatic fibrosis

Hepatic fibrosis (HF) refers to the pathophysiological process of connective tissue dysplasia in the liver caused by various pathogenic factors. Nowadays, HF is becoming a severe threat to the health of human being. However, the drugs available for treating HF are limited. Currently, increasing natural agents derived from traditional Chinese medicines (TCMs) have been found to be beneficial for HF. A systemic literature search was conducted from PubMed, GeenMedical, Sci-Hub, CNKI, Google Scholar and Baidu Scholar, with the keywords of "traditional Chinese medicine," "herbal medicine," "natural agents," "liver diseases," and "hepatic fibrosis." So far, more than 76 natural monomers have been isolated and identified from the TCMs with inhibitory effect on HF, including alkaloids, flavones, quinones, terpenoids, saponins, phenylpropanoids, and polysaccharides, etc. The anti-hepatic fibrosis effects of these compounds include hepatoprotection, inhibition of hepatic stellate cells (HSC) activation, regulation of extracellular matrix (ECM) synthesis & secretion, regulation of autophagy, and antioxidant & anti-inflammation, etc. Natural compounds and extracts from TCMs are promising agents for the prevention and treatment of HF, and this review would be of great significance to development of novel drugs for treating HF.

Update of Indoles: Promising molecules for ameliorating metabolic diseases

Obesity and metabolic disorders have gradually become public health-threatening problems. The metabolic disorder is a cluster of complex metabolic abnormalities which are featured by dysfunction in glucose and lipid metabolism, and results from the increasing prevalence of visceral obesity. With the core driving factor of insulin resistance, metabolic disorder mainly includes type 2 diabetes mellitus (T2DM), micro and macro-vascular diseases, non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and the dysfunction of gut microbiota. Strategies and therapeutic attention are demanded to decrease the high risk of metabolic diseases, from lifestyle changes to drug treatment, especially herbal medicines. Indole is a parent substance of numerous bioactive compounds, and itself can be produced by tryptophan catabolism to stimulate glucagon-like peptide-1 (GLP-1) secretion and inhibit the development of obesity. In addition, in heterocycles drug discovery, the indole scaffold is primarily found in natural compounds with versatile biological activity and plays a prominent role in drug molecules synthesis. In recent decades, plenty of natural or synthesized indole deriviatives have been investigated and elucidated to exert effects on regulating glucose hemeostasis and lipd metabolism. The aim of this review is to trace and emphasize the compounds containing indole scaffold that possess immense potency on preventing metabolic disorders, particularly T2DM, obesity and NAFLD, along with the underlying molecular mechanisms, therefore facilitate a better comprehension of their druggability and application in metabolic diseases.

Indole-Based Small Molecules as Potential Therapeutic Agents for the Treatment of Fibrosis

Indole alkaloids are widely distributed in nature and have been particularly studied because of their diverse biological activities, such as anti-inflammatory, anti-tumor, anti-bacterial, and anti-oxidant activities. Many kinds of indole alkaloids have been applied to clinical practice, proving that indole alkaloids are beneficial scaffolds and occupy a crucial position in the development of novel agents. Fibrosis is an end-stage pathological condition of most chronic inflammatory diseases and is characterized by excessive deposition of fibrous connective tissue components, ultimately resulting in organ dysfunction and even failure with significant morbidity and mortality. Indole alkaloids and indole derivatives can alleviate pulmonary, myocardial, renal, liver, and islet fibrosis through the suppression of inflammatory response, oxidative stress, TGF-β/Smad pathway, and other signaling pathways. Natural indole alkaloids, such as isorhynchophylline, evodiamine, conophylline, indirubin, rutaecarpine, yohimbine, and vincristine, are reportedly effective in organ fibrosis treatment. In brief, indole alkaloids with a wide range of pharmacological bioactivities are important candidate drugs for organ fibrosis treatment. The present review discusses the potential of natural indole alkaloids, semi-synthetic indole alkaloids, synthetic indole derivatives, and indole-contained metabolites in organ fibrosis treatment.

Trimeric and dimeric Aspidosperma-type alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'

Continued interest in bioactive monoterpenoid indole alkaloids and the purpose to explore the artificial cultivation influence on the chemical composition in the same plant species, 8 undescribed Aspidosperma-type alkaloids including two unprecedented trimers, taberdivarines A-B (1-2), and six new dimers, taberdivarines CH (3-8), together with 9 known bisindoles were isolated from the leaves of Tabernaemontana divaricata 'Dwaft'. Notably, taberdivarines A and B were the first cases of Aspidosperma-Aspidosperma-Aspidosperma-type alkaloids with furan ring linkage patterns of the natural products. Their structures were elucidated by comprehensive spectroscopic analyse. Compounds 1-8 were screened for the cytotoxicity against three human cancer cell lines, SMMC-7721, HT-29 and A549. Among them, Compound 6 exhibited significant activity against three cell lines with IC₅₀ values of 0.30, 0.75 and 3.41 μM, respectively (IC₅₀ = 3.02, 0.14 and 2.23 μM for the positive control, vinorelbine). Compound 1, 3, 4, 6, 7 and 8 also expressed varying degrees of activity. The structure-activity relationships (SARs) of these alkaloids were discussed.

Conophylline Suppresses Angiotensin II-Induced Myocardial Fibrosis In Vitro via the BMP4/JNK Pathway

We studied the effects and mechanisms of action of conophylline in different concentrations in the original in vitro model of myocardial fibrosis (treatment of cardiac fibroblasts isolated form the hearts of newborn rats with angiotensin II). Viability, collagen content, and expression of related protein in cardiac fibroblasts were assessed using the MTT-test, Sircol assay, and Western blotting, respectively. Conophylline markedly protected the cultured cells against the development of angiotensin II-induced fibrosis, which was seen from reduced viability of fibroblasts, decreased collagen content, and down-regulation of the expression of α-smooth muscle actin (α-SMA). Conophylline did not affect the TGF-β pathway altered by angiotensin II, but markedly decreased the level of bone morphogenetic protein-4 (BMP4) enhanced by angiotensin II and BMP4 itself. Conophylline produced no effect on phosphorylation of α-SMA and Smad homologue-1/5/8, the classic BMP4 downstream pathway elements, but reduced the level of c-Jun N-terminal kinase (JNK) elevated by BMP4. Conophylline did not inhibit the development of myocardial fibrosis in the presence of JNK activator anisomycin. Thus, conophylline inhibited angiotensin II-provoked myocardial fibrosis via the BMP4/JNK pathway.

Conophylline Inhibits Hepatocellular Carcinoma by Inhibiting Activated Cancer-associated Fibroblasts Through Suppression of G Protein-coupled Receptor 68

Treatment of hepatocellular carcinoma (HCC) is currently challenging. Cancer-associated fibroblasts (CAFs) promote the malignancy of HCC cells via production of cytokines. Conophylline (CnP), a vinca alkaloid obtained from Ervatamia microphylla leaves, has been reported to suppress activation of hepatic stellate cells and liver fibrosis in rats. We examined the efficacy of CnP in suppressing tumor growth in HCC. Specifically, we investigated whether CnP could inhibit CAFs, which were derived from HCC tissues in vitro and in vivo Same as previous reports, CAFs promoted proliferative and invasive ability of HCC cells. CnP suppressed α-smooth muscle actin expression of CAFs, and inhibited their cancer-promoting effects. CnP significantly suppressed CAFs producting cytokines such as IL6, IL8, C-C motif chemokine ligand 2, angiogenin, and osteopontin (OPN). Combined therapy with sorafenib and CnP against HCC cells and CAFs in vivo showed to inhibit tumor growth the most compared with controls and single treatment with CnP or sorafenib. Transcriptome analysis revealed that GPR68 in CAFs was strongly suppressed by CnP. The cancer-promoting effects of cytokines were eliminated by knockdown of GPR68 in CAFs. CnP inhibited the HCC-promoting effects of CAFs by suppressing several HCC-promoting cytokines secreted by CAFs expressing GPR68. Combination therapy with CnP and existing anticancer agents may be a promising strategy for treating refractory HCC associated with activated CAFs.

Effect of Adrenergic Agonists on High-Fat Diet-Induced Hepatic Steatosis in Mice

The autonomic nervous system, consisting of sympathetic and parasympathetic branches, plays an important role in regulating metabolic homeostasis. The sympathetic nervous system (SNS) regulates hepatic lipid metabolism by regulating adrenergic receptor activation, resulting in the stimulation of hepatic very-low-density lipoprotein-triglyceride (TG) production in vivo. However, only a few studies on the relationship between SNS and hepatic steatosis have been reported. Here, we investigate the effect of adrenergic receptor agonists on hepatic steatosis in mice fed a high-fat diet (HFD). The α-adrenergic receptor agonist phenylephrine (10 mg/kg/d) or the β-adrenergic receptor agonist isoproterenol (30 mg/kg/d) was coadministered with HFD to male mice. After five weeks, hepatic steatosis, TG levels, and hepatic fat metabolism-related biomarkers were examined. HFD treatment induced hepatic steatosis, and cotreatment with phenylephrine, but not isoproterenol, attenuated this effect. Phenylephrine administration upregulated the mRNA levels of hepatic peroxisome proliferator-activated receptor alpha and its target genes (such as carnitine palmitoyltransferase 1) and increased hepatic β-hydroxybutyrate levels. Additionally, phenylephrine treatment increased the expression of the autophagosomal marker LC3-II but decreased that of p62, which is selectively degraded during autophagy. These results indicate that phenylephrine inhibits hepatic steatosis through stimulation of β-oxidation and autophagy in the liver.

Identifying cancer-associated fibroblasts as emerging targets for hepatocellular carcinoma

The tumor microenvironment (TME) is a complex multicellular functional compartment that includes fibroblasts, myofibroblasts, endothelial cells, immune cells, and extracellular matrix (ECM) elements. The microenvironment provides an optimum condition for the initiation, growth, and dissemination of hepatocellular carcinoma (HCC). As one of the critical and abundant components in tumor microenvironment, cancer-associated fibroblasts (CAFs) have been implicated in the progression of HCC. Through secreting various growth factors and cytokines, CAFs contribute to the ECM remodeling, stem features, angiogenesis, immunosuppression, and vasculogenic mimicry (VM), which reinforce the initiation and development of HCC. In order to restrain the CAFs-initiated HCC progression, current strategies include targeting specific markers, engineering CAFs with tumor-suppressive phenotype, depleting CAFs’ precursors, and repressing the secretions or downstream signaling. In this review, we update the emerging understanding of CAFs in HCC, with particular emphasis on cellular origin, phenotypes, biological functions and targeted strategies. It provides insights into the targeting CAFs for HCC treatment.

Nintedanib inhibits intrahepatic cholangiocarcinoma aggressiveness via suppression of cytokines extracted from activated cancer-associated fibroblasts

Background

Intrahepatic cholangiocarcinoma (ICC) is a malignancy that is challenging to treat. Fibroblasts in ICC tissues have been identified as cancer-associated fibroblasts (CAFs) that promote the malignant behaviour of ICC cells. An antifibrotic drug nintedanib has been reported to suppress activated hepatic stellate cells in liver fibrosis.

Methods

We investigated whether nintedanib could suppress the cancer-promoting effect of CAFs derived from ICC tissues in vitro and in vivo.

Results

CAFs promoted the proliferation and invasion of ICC cells. Nintedanib suppressed activated CAFs expressing α-smooth muscle actin (α-SMA) and inhibited the ICC-promoting effects of CAFs. Nintedanib greatly reduced the levels of cancer-promoting cytokines, such as interleukin (IL)-6 (IL-6) and IL-8, secreted by CAFs. An in vivo study demonstrated that nintedanib reduced xenografted ICC growth and activated CAFs expressing α-SMA, and that combination therapy with nintedanib and gemcitabine against CAFs and ICC cells showed the strongest inhibition of tumour growth compared with the control and single-treatment groups.

Conclusions

Nintedanib inhibited the cancer-promoting effect of CAFs via the suppression of CAF activation and secretion of cancer-promoting cytokines. Our findings suggest that therapeutic strategies combining conventional cytotoxic agents with nintedanib targeting CAFs are promising for overcoming refractory ICC with activated CAFs.

Current perspectives on the immunosuppressive tumor microenvironment in hepatocellular carcinoma: challenges and opportunities

Incidence of hepatocellular carcinoma (HCC) is on the rise due to the prevalence of chronic hepatitis and cirrhosis. Although there are surgical and chemotherapy treatment avenues the mortality rate of HCC remains high. Immunotherapy is currently the new frontier of cancer treatment and the immunobiology of HCC is emerging as an area for further exploration. The tumor microenvironment coexists and interacts with various immune cells to sustain the growth of HCC. Thus, immunosuppressive cells play an important role in the anti-tumor immune response. This review will discuss the current concepts of immunosuppressive cells, including tumor-associated macrophages, marrow-derived suppressor cells, tumor-associated neutrophils, cancer-associated fibroblasts, and regulatory T cell interactions to actively promote tumorigenesis. It further elaborates on current treatment modalities and future areas of exploration.

Research progress on the anti-hepatic fibrosis action and mechanism of natural products

Hepatic fibrosis is the most common pathological feature of most chronic liver diseases, and its continuous deterioration gradually develops into liver cirrhosis and eventually leads to liver cancer. At present, there are many kinds of drugs used to treat liver fibrosis. However, Western drugs tend to only target single genes/proteins and induce many adverse reactions. Most of the mechanisms and active ingredients of traditional Chinese medicine (TCM) are not clear, and there is a lack of unified diagnosis and treatment standards. Natural products, which are characterized by structural diversity, low toxicity, and origination from a wide range of sources, have unique advantages and great potential in anti-liver fibrosis. This article summarizes the work done over the previous decade, on the active ingredients in natural products that are reported to have anti-hepatic fibrosis effects. The effective anti-hepatic fibrosis ingredients identified can be generally divided into flavonoids, saponins, polysaccharides and alkaloids. Mechanisms of anti-liver fibrosis include inhibition of liver inflammation, anti-lipid peroxidation injury, inhibition of the activation and proliferation of hepatic stellate cells (HSCs), modulation of the synthesis and secretion of pro-fibrosis factors, and regulation of the synthesis and degradation of the extracellular matrix (ECM). This review provides suggestions for the development of anti-hepatic fibrosis drugs.

Kaempferol attenuates liver fibrosis by inhibiting activin receptor-like kinase 5

Liver fibrosis is a common public health problem. Patients with liver fibrosis are more likely to develop cirrhosis, or hepatocellular carcinoma (HCC) as a more serious consequence. Numerous therapeutic approaches have emerged, but the final clinical outcome remains unsatisfactory. Here, we discovered a flavonoid natural product kaempferol that could dramatically ameliorate liver fibrosis formation. Our data showed that intraperitoneal injection of kaempferol could significantly decrease the necroinflammatory scores and collagen deposition in the liver tissue. In addition, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), laminin (LN) and hyaluronic acid (HA) levels were significantly down-regulated in kaempferol treatment group compared with those in the control group. Our study also demonstrated that kaempferol markedly inhibited the synthesis of collagen and activation of hepatic stellate cells (HSCs) both in vivo and in vitro. Furthermore, the results of Western blotting revealed that kaempferol could down-regulate Smad2/3 phosphorylation dose-dependently. These bioactivities of kaempferol may result from its targeted binding to the ATP-binding pocket of activin receptor-like kinase 5 (ALK5), as suggested by the molecular docking study and LanthaScreen Eu kinase binding assay. Above all, our data indicate that kaempferol may prove to be a novel agent for the treatment of liver fibrosis or other fibroproliferative diseases.

Conophylline inhibits high fat diet-induced non-alcoholic fatty liver disease in mice

Conophylline (CnP), a vinca alkaloid extracted from the leaves of the tropical plant Tabernaemontana divaricate, attenuates hepatic fibrosis in mice. We have previously shown that CnP inhibits non-alcoholic steatohepatitis (NASH) using a methionine-choline-deficient (MCD) diet-fed mouse model. However, little is known about the CnP mediated inhibition of hepatic steatosis in high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) mouse models. CnP (0.5 and 1 μg/g/body weight) was co-administered along with a high-fat diet to male BALB/c mice. After nine weeks of administering the high-fat diet, hepatic steatosis, triglyceride, and hepatic fat metabolism-related markers were examined. Administration of a high-fat diet for 9 weeks was found to induce hepatic steatosis. CnP dose-dependently attenuated the high-fat diet-induced hepatic steatosis. The diet also attenuated hepatic peroxisome proliferator-activated receptor alpha (PPARA) mRNA levels. PPARA is known to be involved in β-oxidation. CnP upregulated the mRNA levels of hepatic PPARA and its target genes, such as carnitine palmitoyl transferase 1 (CPT1) and CPT2, in a dose-dependent manner in the liver. Furthermore, levels of hepatic β-hydroxybutyrate, which is a type of ketone body, were increased by CnP in a dose-dependent manner. Finally, CnP increased the expression of the autophagosomal marker LC3-II and decreased the expression of p62, which are known to be selectively degraded during autophagy. These results indicate that CnP inhibits hepatic steatosis through the stimulation of β-oxidation and autophagy in the liver. Therefore, CnP might prove to be a suitable therapeutic target for NAFLD.

Conophylline suppresses pancreatic cancer desmoplasia and cancer-promoting cytokines produced by cancer-associated fibroblasts

Despite recent advances in cancer treatment, pancreatic cancer is a highly malignant tumor type with a dismal prognosis and it is characterized by dense desmoplasia in the cancer tissue. Cancer-associated fibroblasts (CAF) are responsible for this fibrotic stroma and promote cancer progression. We previously reported that a novel natural compound conophylline (CnP) extracted from the leaves of a tropical plant reduced liver and pancreatic fibrosis by suppression of stellate cells. However, there have been no studies to investigate the effects of CnP on CAF, which is the aim of this work. Here, we showed that CAF stimulated indicators of pancreatic cancer malignancy, such as proliferation, invasiveness, and chemoresistance. We also showed that CnP suppressed CAF activity and proliferation, and inhibited the stimulating effects of CAF on pancreatic cancer cells. Moreover, CnP strongly decreased the various cytokines involved in cancer progression, such as interleukin (IL)-6, IL-8, C-C motif chemokine ligand 2 (CCL2), and C-X-C motif chemokine ligand 12 (CXCL12), secreted by CAF. In vivo, CAF promoted tumor proliferation and desmoplastic formation in a mouse xenograft model, CnP reduced desmoplasia of tumors composed of pancreatic cancer cells + CAF, and combination therapy of CnP with gemcitabine remarkably inhibited tumor proliferation. Our findings suggest that CnP is a promising therapeutic strategy of combination therapy with anticancer drugs to overcome refractory pancreatic cancers.

The plant alkaloid conophylline inhibits matrix formation of fibroblasts

Conophylline is a Vinca alkaloid from leaves of the tropical plant Ervatamia microphylla and has been shown to mimic the effect of the growth and differentiation factor activin A on pancreatic progenitor cells. However, activin A stimulates fibrosis of pancreatic stellate cells, whereas conophylline inhibits it, suggesting that this compound may serve as an antifibrotic drug. Here we investigated the effects of conophylline on human foreskin fibroblasts, especially focusing on extracellular matrix (ECM) proteins. A gene microarray analysis revealed that conophylline remarkably suppressed expression of the gene for hyaluronan synthase 2 (HAS2) and of its antisense RNA, whereas the expression of collagen genes was unaffected. Of note, immunostaining experiments revealed that conophylline substantially inhibits incorporation of versican and collagens into the ECM in cells treated with transforming growth factor β (TGFβ), which promotes collagen synthesis, but not in cells not treated with TGFβ. Moreover, a protein biosynthesis assay disclosed that conophylline decreases collagen biosynthesis, concomitant with a decrease in total protein biosynthesis, indicating that conophylline-mediated inhibition of fibrosis is not specific to collagen synthesis. Conophylline affected neither TGFβ-induced nuclear translocation of SMAD family member 2/3 (SMAD2/3) nor phosphorylation of SMAD2. However, conophylline substantially inhibited phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), suggesting that conophylline inhibits HAS2 expression via TGFβ-mediated activation of the ERK1/2 pathway. Taken together, our results indicate that conophylline may be a useful inhibitor of ECM formation in fibrosis.

Therapeutic activity of plant-derived alkaloid conophylline on metabolic syndrome and neurodegenerative disease models

Increasing metabolic syndromes including type-2 diabetes mellitus, obesity, and steatohepatitis are serious problems in most countries in the world. Neurodegenerative diseases such as Alzheimer, Parkinson's, and Huntington's diseases are increasing in many countries. However, therapy for these diseases is not sufficient yet. Thus, effective chemotherapy for these diseases is being expected. Conophylline is an alkaloid isolated from the leaves of Ervatamia microphylla and related plants. It was found to induce beta-cell differentiation in the precursor pancreatic cells. Oral administration of this compound ameliorated type-2 diabetes mellitus model in mice and rats. Later, fibrosis of the pancreatic islets was found to be greatly reduced by conophylline in the pancreatic islets. It also inhibited chemically induced liver cirrhosis. Further study indicated that conophylline inhibited non-alcoholic steatohepatitis in the model mice. On the one hand, loss of autophagy often causes protein aggregation to give neural cell death. Conophylline was found to activate autophagy in cultured neural cells. Activation of autophagy ameliorated cellular models of Parkinson's and Huntington's diseases. Thus, conophylline is likely to be useful for the development of chemotherapy for metabolic and neurodegenerative diseases.

Conophylline inhibits non-alcoholic steatohepatitis in mice

Conophylline (CnP), a vinca alkaloid extracted from the leaves of the tropical plant Ervatamia microphylla, attenuates hepatic fibrosis in mice. However, little is known about whether CnP inhibits steatosis, inflammation, and fibrosis in non-alcoholic steatohepatitis (NASH) in mice. A methionine-choline-deficient (MCD) diet was administered to male db/db mice as a NASH model, and CnP (1 μg/kg/d) was co-administered. Eight weeks after the commencement of the MCD diet, hepatic steatosis, inflammation, and fibrosis, and hepatic fat metabolism-, inflammation-, and fibrosis-related markers were examined. Feeding on an MCD for 8 weeks induced hepatic steatosis, inflammation, and fibrosis. CnP significantly attenuated the MCD-induced increases in hepatic steatosis, as well as hepatic inflammation and fibrosis. The MCD diet increased hepatic transforming growth factor-β (TGF-β) mRNA levels, which are correlated with hepatic steatosis, inflammation, and fibrosis. The diet also attenuated acyl-coenzyme A oxidase 1 (ACOX1) and carnitine palmitoyltransferase 1 (CPT1) mRNA levels, which are involved in β-oxidation. The putative mechanism of the CnP effect involves reduced hepatic TGF-β mRNA levels, and increased mRNA levels of hepatic peroxisome proliferator-activated receptor (PPAR) α and its target genes ACOX1 and CPT1. The results of this study indicate that CnP inhibits steatohepatitis, possibly through the inhibition of hepatic TGF-β mRNA levels, and induces an increase in PPARα mRNA levels, resulting in the attenuation of hepatic steatosis, inflammation, and fibrosis in mice. CnP might accordingly be a suitable therapeutic option for NASH.

Cancer-associated fibroblasts in hepatocellular carcinoma

The hepatic stellate cells in the liver are stimulated sustainably by chronic injury of the hepatocytes, activating myofibroblasts, which produce abundant collagen. Myofibroblasts are the major source of extracellular proteins during fibrogenesis, and may directly, or secreted products, contribute to carcinogenesis and tumor progression. Cancer-associated fibroblasts (CAFs) are one of the components of the tumor microenvironment that promote the proliferation and invasion of cancer cells by secreting various growth factors and cytokines. CAFs crosstalk with cancer cells stimulates tumor progression by creating a favorable microenvironment for progression, invasion, and metastasis through the epithelial-mesenchymal transition. Basic studies on CAFs have advanced, and the role of CAFs in tumors has been elucidated. In particular, for hepatocellular carcinoma, carcinogenesis from cirrhosis is a known fact, and participation of CAFs in carcinogenesis is supported. In this review, we discuss the current literature on the role of CAFs and CAF-related signaling in carcinogenesis, crosstalk with cancer cells, immunosuppressive effects, angiogenesis, therapeutic targets, and resistance to chemotherapy. The role of CAFs is important in cancer initiation and progression. CAFtargeted therapy may be effective for suppression not only of fibrosis but also cancer progression.

Inhibition of receptor activator of nuclear factor-κB ligand- or lipopolysaccharide-induced osteoclast formation by conophylline through downregulation of CREB

The effect of conophylline (CNP) on the receptor activator of nuclear factor-κB ligand (RANKL) or lipopolysaccharide (LPS)-induced osteoclast formation was studied in vitro using bone marrow-derived macrophages (BMMs) or the mouse macrophage-like cell line RAW 264.7. CNP inhibited RANKL-induced formation of osteoclasts identified as tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells in a culture of BMMs. It also inhibited RANKL- or LPS-induced osteoclast formation in RAW 264.7 cells. CNP lowered the osteoclast maturation markers such as calcitonin receptor, MMP9 and cathepsin K in BMMs, suggesting that CNP would inhibit the process of osteoclast differentiation. CNP inhibited the RANKL-induced expressions of c-Fos and nuclear factor of activated T cells (NFATc1), key transcription factors for osteoclastogenesis. On the other hand, CNP did not inhibit the signaling pathway of NF-κB and mitogen-activated protein kinases (MAPKs) in RANKL-stimulated BMMs. Interestingly, CNP inhibited RANKL-induced CREB activation that can mediate c-Fos and NFATc1. CNP also inhibited RANKL- or LPS-induced CREB, c-Fos and NFATc1 activation in RAW 264.7 cells. We have previously found that CNP directly binds to ADP-ribosylation-like factor-6 interacting protein (ARL6ip), although its role in osteoclastogenesis is not clear. Gene knockdown of ARL6ip by siRNA inhibited RANKL-induced c-Fos expression, suggesting that inactivation of ARL6ip may be involved in an inhibitory effect of CNP. Taken together, CNP was shown to inhibit osteoclast formation possibly via CREB inactivation following a decrease in c-Fos and NFATc1 expression.