Lonidamine ameliorates MASH by reducing SREBP1 and inhibiting the MAPK pathway

Abstract

Metabolic dysfunction-associated steatohepatitis (MASH) has become a global epidemic, and effective therapeutic strategies are urgently needed. Lonidamine (LND) has been reported to possess anti-inflammatory effects; however, few studies have investigated whether LND exerts a therapeutic effect on MASH. Therefore, in this study, we aim to explore the effects of LND on inflammatory responses and abnormal lipid metabolism in MASH mice. A mouse MASH model is established by feeding C57BL/6 mice a high-fat, high-cholesterol (CL) diet. The results show that LND attenuates CL-induced increases in body weight, serum glucose and lipid levels, inflammatory responses, and hepatocellular steatosis. In addition, the mitogen-activated protein kinase (MAPK) signaling pathway is inhibited, and the expression level of sterol regulatory element-binding protein 1 (SREBP1) protein is significantly reduced. Meanwhile, in vitro models of cellular inflammation and lipid metabolism are simulated, and molecular docking and biolayer interferometry (BLI) analysis are used to verify that LND and SREBP1 have a direct interaction and that LND promotes the degradation of SREBP1. Furthermore, specific knockdown of Srebp1 in AML12 cells is performed to further verify the effect of LND on MASH. The results confirm that LND exerts anti-inflammatory effects in MASH by inhibiting the activity of the MAPK signaling pathway and improves abnormal lipid metabolism through its interaction with SREBP1. Overall, LND holds promise as a potential therapeutic agent for the treatment of MASH.

1. Introduction

Metabolic-associated steatotic liver disease (MASLD), as the hepatic manifestation of metabolic syndrome, has become the most prevalent chronic liver disease worldwide, currently affecting approximately one-quarter of the global population. It is projected that by 2030, end-stage liver diseases related to MASLD, including decompensated cirrhosis and hepatocellular carcinoma, will become the main indications for liver transplantation [1]. This will impose an extremely heavy burden on global public health. MASLD is an insulin resistance-driven continuum from simple steatosis through metabolic dysfunction-associated steatohepatitis (MASH) to fibrosis, cirrhosis, and hepatocellular carcinoma [2]. At present, MASH has been widely recognized as a complex multifactorial disease. In recent years, the multiple-hit hypothesis has gained increasing acceptance among scholars [3]. The main content of the multiple-hit hypothesis includes insulin resistance [4–7], hormones secreted by adipose tissue [8,9], nutritional factors [10,11], gut microbiota [12,13], and genetic factors [14,15].

Lonidamine (LND), a derivative of the indazole class, was first introduced as a spermatostatic agent in 1979 [16]. Subsequently, LND was identified to exert antitumor effects by disrupting cellular energy metabolism, with a particular focus on its regulatory role in the mitochondrial function of tumor cells. LND inhibits the uptake of pyruvate into mitochondria by suppressing the mitochondrial pyruvate carrier (MPC) [17]. LND is also recognized to inhibit the activity of Complex II in the mitochondrial electron transport chain by interfering with the ubiquinone-binding sites of succinate dehydrogenase C (SDHC) and succinate dehydrogenase D (SDHD) [18]. Studies have also demonstrated that LND suppresses hexokinase II (HK–II), thereby inhibiting the glycolytic pathway and the pentose phosphate pathway (PPP). This inhibition leads to reduced levels of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), which in turn contribute to its antitumor effects [19]. Moreover, LND has been shown to directly target apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), a key adaptor protein in inflammasome assembly, thereby suppressing inflammasome-driven inflammatory responses in conditions such as neuroinflammation and rheumatoid arthritis [20,21]. In vivo, LND exhibits selectivity toward tumors and exerts no significant toxic effects on skeletal muscle or the brain [22]. Currently, LND has been investigated for the treatment of non-small cell lung cancer (NSCLC), breast cancer, colon cancer, astrocytoma, squamous cell carcinoma, human brain glioma, and other malignancies [23]. In recent years, researchers have also identified that LND plays an important role in other non-tumor diseases. Excessive glycolysis and the induction of the key glycolytic enzyme hexokinase are necessary for microglia-mediated neuroinflammation under hypoxic conditions [24]. LND inhibits glycolysis and exerts anti-inflammatory effects in microglia-mediated neuroinflammation. It has also been found that abnormal glycolytic metabolism leads to joint inflammation and destruction in rheumatoid arthritis. By blocking hexokinase, LND has been shown to reduce the incidence and severity of arthritis in collagen-induced arthritis animal models, indicating its potential to inhibit inflammatory responses [25]. Currently, LND is no longer used as a single chemotherapeutic agent but rather as a sensitizing agent in combination therapy, enhancing the effectiveness of traditional therapies by altering the tumor metabolic microenvironment [26].