SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1β pathway

Geniposide ameliorates cholesterol accumulation and promotes osteoblast differentiation by mediating the GLP-1R/AMPK/SREBP2 pathway

BACKGROUND

Glucocorticoid (GC)-induced OP (GIOP) is a systemic metabolic bone disease with a high risk of fracture. Recently, lipid metabolic disorders, particularly hypercholesterolemia, have been correlated to the development of OP. However, the roles of cholesterol accumulation in osteoblasts during GIOP pathological development are still unclear. Our previous study shows that intracellular cholesterol accumulation can suppress osteoblast differentiation and promote cell apoptosis. Geniposide (GEN), a natural activator of glucagon-like peptide-1 receptor (GLP-1R), exhibited protective activity against dexamethasone (DEX)-induced cholesterol accumulation and osteoblast differentiation inhibition. Sterol regulatory element-binding protein 2 (SREBP2) regulates cholesterol synthesis. Whether SREBP2 was involved in DEX-induced cholesterol accumulation and osteoblast differentiation was still unknown.

METHODS

DEX-induced rat OP models were duplicated. Micro-computed tomography (µCT) was used to scan the proximal femurs, and hematoxylin and eosin (H&E) staining was used for histological examination. MC3T3-E1 cells were used for the cell study, and ALP and Alizarin Red S were employed to study osteoblast differentiation. pcDNA3.1-SREBP2 was used to transfect MC3T3-E1 cells. Western blotting assays were employed to study the protein expression.

RESULTS

DEX enhanced the expression of SREBP2 and mTOR and promoted cholesterol accumulation and osteoblast differentiation inhibition in MC3T3-E1 cells. These could be rescued by GEN treatment. However, overexpression of SREBP2, mTOR activation, and AMPK and GLP-1R inhibition could block the protective effects of GEN.

CONCLUSION

GEN improved DEX-induced cholesterol accumulation and osteoblast differentiation inhibition by mediating the GLP-1R/AMPK/mTOR/SREBP2 signaling.

Hypercapnia Increases Influenza A Virus Infection of Bronchial Epithelial Cells by Augmenting Cellular Cholesterol via mTOR and Akt

Hypercapnia, the elevation of CO2 in blood and tissue, is a risk factor for mortality in patients with severe lung disease and pulmonary infections. We previously showed that hypercapnia increases viral replication and mortality in mice infected with influenza A virus (IAV). Elevated CO2 also augmented cholesterol content and pseudo-SARS-CoV-2 entry in bronchial epithelial cells. Interestingly, cellular cholesterol facilitates IAV uptake, replication, assembly, and egress from cells. Here, we report that hypercapnia increases viral protein expression in airway epithelium of mice infected with IAV. Elevated CO2 also enhanced IAV adhesion and internalization, viral protein expression, and viral replication in bronchial epithelial cells. Hypercapnia increased the expression and activation of the transcription factor sterol-regulatory element binding protein 2 (SREBP2), resulting in elevated expression of cholesterol synthesis enzymes, decreased expression of a cholesterol efflux transporter, and augmented cellular cholesterol. Moreover, reducing cellular cholesterol with an SREBP2 inhibitor or statins blocked hypercapnia-induced increases in viral adhesion and internalization, viral protein expression, and IAV replication. Inhibitors of mTOR and Akt also blocked the effect of hypercapnia on viral growth. Our findings suggest that targeting cholesterol synthesis and/or mTOR/Akt signaling may hold promise for reducing susceptibility to influenza infection in patients with advanced lung disease and hypercapnia.

Lenvatinib and immune-checkpoint inhibitors in hepatocellular carcinoma: mechanistic insights, clinical efficacy, and future perspectives

Lenvatinib is a multi-target tyrosine kinase inhibitor widely used in the treatment of hepatocellular carcinoma (HCC). Its primary mechanism of action involves inhibiting signal pathways such as vascular endothelial growth factor receptors (VEGFR) and fibroblast growth factor receptors (FGFR), thereby reducing tumor cell proliferation and angiogenesis and affecting the tumor's immune microenvironment. In the treatment of liver cancer, although lenvatinib monotherapy has shown good clinical effect, the problem of drug resistance is becoming more and more serious. This resistance may be caused by a variety of factors, including genetic mutations, signaling pathway remodeling, and changes in the tumor microenvironment. In order to overcome drug resistance, the combination of lenvatinib and other therapeutic strategies has gradually become a research hotspot, and it is worth noting that the combination of lenvatinib and immune checkpoint inhibitors (ICIs) has shown a good application prospect. This combination not only enhances the anti-tumor immune response but also helps improve therapeutic efficacy. However, combination therapy also faces challenges regarding safety and tolerability. Therefore, studying the mechanisms of resistance and identifying relevant biomarkers is particularly important, as it aids in early diagnosis and personalized treatment. This article reviews the mechanisms of lenvatinib in treating liver cancer, the mechanisms and efficacy of its combination with immune checkpoint inhibitors, the causes of resistance, the exploration of biomarkers, and other novel combination therapy strategies for lenvatinib. We hope to provide insights into the use and research of lenvatinib in clinical and scientific settings, offering new strategies for the treatment of liver cancer.

Targeting the mTOR Pathway in Hepatocellular Carcinoma: The Therapeutic Potential of Natural Products

Despite advancements in cancer treatment through surgery and drugs, hepatocellular carcinoma (HCC) remains a significant challenge, as reflected by its low survival rates. The mammalian target of rapamycin (mTOR) signaling pathway plays a crucial role in regulating the cell cycle, proliferation, apoptosis, and metabolism. Notably, dysregulation leading to the activation of the mTOR signaling pathway is common in HCC, making it a key focus for in-depth research and a target for current therapeutic strategies. This review focuses on the role of the mTOR signaling pathway and its downstream effectors in regulating HCC cell proliferation, apoptosis, autophagy, cell cycle, and metabolic reprogramming. Moreover, it emphasizes the potential of natural products as modulators of the mTOR signaling pathway. When incorporated into combination therapies, these natural products have been demonstrated to augment therapeutic efficacy and surmount drug resistance. These products target key signaling pathways such as mTOR signaling pathways. Examples include 11-epi-sinulariolide acetate, matrine, and asparagus polysaccharide. Their inhibitory effects on these processes suggest valuable directions for the development of more effective HCC therapeutic strategies. Various natural products have demonstrated the ability to inhibit mTOR signaling pathway and suppress HCC progression. These phytochemicals, functioning as mTOR signaling pathway inhibitors, hold great promise as potential anti-HCC agents, especially in the context of overcoming chemoresistance and enhancing the outcomes of combination therapies.

Recent advancements in the small-molecule drugs for hepatocellular carcinoma (HCC): Structure-activity relationships, pharmacological activities, and the clinical trials

BACKGROUND AND AIMS: Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world and the sixth leading cause of cancer death worldwide, and it is urgent to find safe and effective drugs for treatment. As an important therapeutic method, small-molecule drugs are continually being updated to achieve improved therapeutic effects. The purpose of this study was to investigate the structural effects of various FDA-listed small-molecule drugs sorafenib, cabozantinib, lenvatinib, and regorafenib on the corresponding HCC targets and possible structural optimization methods, and to explore the mechanism for identifying potential therapeutic drugs that offer better efficacy and fewer side effects.

METHODS

The structure-activity relationship, pharmacological actions, and clinical applications of small-molecule drugs were reviewed by referencing MEDLINE, Web of Science, CNKI, and other databases, summarizing and integrating the relevant content.

RESULTS

The results showed that small-molecule drugs can inhibit HCC primarily by forming hydrogen bonds with Glu885, Asp1046, and Cys919 on the HCC target. HCC can be targeted by inhibiting the activation of multiple pathways, blocking the conduction of downstream signaling, and reducing the formation of tumor blood vessels. In general, small-molecule drugs primarily target four key receptors in HCC: VEGFR, PDGFR, EGFR, and FGFR, to achieve effective treatment.

CONCLUSIONS

By revealing their structure-activity relationships, pharmacological actions, and clinical trials, small-molecule drugs can offer broad prospects for the development of new medications.

Roles of clinical application of lenvatinib and its resistance mechanism in advanced hepatocellular carcinoma (Review)

Lenvatinib (LEN) is a multi-target TKI, which plays a pivotal role in the treatment of advanced hepatocellular carcinoma (HCC). The inevitable occurrence of drug resistance still prevents curative potential and is deleterious for the prognosis, and a growing body of studies is accumulating, which have devoted themselves to unveiling its underlying resistance mechanism and made some progress. The dysregulation of crucial signaling pathways, non-coding RNA and RNA modifications were proven to be associated with LEN resistance. A range of drugs were found to influence LEN therapeutic efficacy. In addition, the superiority of LEN combination therapy has been shown to potentially overcome the limitations of LEN monotherapy in a series of research, and a range of promising indicators for predicting treatment response and prognosis have been discovered in recent years. In this review, we summarize the latest developments in LEN resistance, the efficacy and safety of LEN combination therapy as well as associated indicators, which may provide new insight into its resistance as well as ideas in the treatment of advanced HCC.

New insights into the mechanism of resistance to lenvatinib and strategies for lenvatinib sensitization in hepatocellular carcinoma

Lenvatinib is a multikinase inhibitor that suppresses vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor α (PDGFRα), as well as the proto-oncogenes RET and KIT. Lenvatinib has been approved by the US Food and Drug Administration (FDA) for the first-line treatment of hepatocellular carcinoma (HCC) due to its superior efficacy when compared to sorafenib. Unfortunately, the development of drug resistance to lenvatinib is becoming increasingly common. Thus, there is an urgent need to identify the factors that lead to drug resistance and ways to mitigate it. We summarize the molecular mechanisms that lead to lenvatinib resistance (LR) in HCC, which involve programmed cell death (PCD), translocation processes, and changes in the tumor microenvironment (TME), and provide strategies to reverse resistance.

Cholesterol metabolism: physiological regulation and diseases

Cholesterol homeostasis is crucial for cellular and systemic function. The disorder of cholesterol metabolism not only accelerates the onset of cardiovascular disease (CVD) but is also the fundamental cause of other ailments. The regulation of cholesterol metabolism in the human is an extremely complex process. Due to the dynamic balance between cholesterol synthesis, intake, efflux and storage, cholesterol metabolism generally remains secure. Disruption of any of these links is likely to have adverse effects on the body. At present, increasing evidence suggests that abnormal cholesterol metabolism is closely related to various systemic diseases. However, the exact mechanism by which cholesterol metabolism contributes to disease pathogenesis remains unclear, and there are still unknown factors. In this review, we outline the metabolic process of cholesterol in the human body, especially reverse cholesterol transport (RCT). Then, we discuss separately the impact of abnormal cholesterol metabolism on common diseases and potential therapeutic targets for each disease, including CVD, tumors, neurological diseases, and immune system diseases. At the end of this review, we focus on the effect of cholesterol metabolism on eye diseases. In short, we hope to provide more new ideas for the pathogenesis and treatment of diseases from the perspective of cholesterol.

Dysregulated cholesterol regulatory genes in hepatocellular carcinoma

Cholesterol is an indispensable component in mammalian cells, and cholesterol metabolism performs important roles in various biological activities. In addition to the Warburg effect, dysregulated cholesterol metabolism is one of the metabolic hallmarks of several cancers. It has reported that reprogrammed cholesterol metabolism facilitates carcinogenesis, metastasis, and drug-resistant in various tumors, including hepatocellular carcinoma (HCC). Some literatures have reported that increased cholesterol level leads to lipotoxicity, inflammation, and fibrosis, ultimately promoting the development and progression of HCC. Contrarily, other clinical investigations have demonstrated a link between higher cholesterol level and lower risk of HCC. These incongruent findings suggest that the connection between cholesterol and HCC is much complicated. In this report, we summarize the roles of key cholesterol regulatory genes including cholesterol biosynthesis, uptake, efflux, trafficking and esterification in HCC. In addition, we discuss promising related therapeutic targets for HCC.