The interplay of transcriptional coregulator NUPR1 with SREBP1 promotes hepatocellular carcinoma progression via upregulation of lipogenesis

Lactylation-Driven NUPR1 Promotes Immunosuppression of Tumor-Infiltrating Macrophages in Hepatocellular Carcinoma

While checkpoint immunotherapy effectively mobilizes T-cell responses against tumors, its success in hepatocellular carcinoma (HCC) is frequently undermined by immunosuppressive myeloid cells within the tumor microenvironment. This study investigates the role of nuclear protein 1 (NUPR1), a gene prominently expressed in tumor-associated macrophages (TAMs), in mediating this suppression and influencing immunotherapy outcomes. Through comprehensive analysis of single-cell RNA sequencing (scRNA-seq) datasets and functional assays in vitro and in vivo, NUPR1 is identified as a critical regulator within TAMs. The upregulation of NUPR1 is associated with enhanced M2 macrophage polarization and increased expression of immune checkpoints PD-L1 and SIRPA, resulting in CD8+ T cell exhaustion and a diminished response to immunotherapy. Mechanistically, NUPR1 inhibits the ERK and JNK signaling pathways, thereby creating an immunosuppressive milieu conducive to tumor progression. Additionally, tumor-derived lactate is shown to upregulate NUPR1 expression in macrophages via histone lactylation, perpetuating a feedback loop that intensifies immune suppression. Pharmacological targeting of NUPR1 reverses M2 polarization, curtails tumor growth, and augments the efficacy of PD-1 blockade in preclinical models, positioning NUPR1 as both a potential biomarker for immunotherapy responsiveness and a therapeutic target to boost immunotherapy efficacy in HCC.

Elevated SREBP1 accelerates the initiation and growth of pancreatic cancer by targeting SOX9

Pancreatic cancer is a lethal disease with an insidious onset, and little is known about its early molecular events. Here, we found that the sterol regulatory element-binding protein 1 (SREBP1) expression is gradually upregulated during the initiation of pancreatic cancer. Through in vitro 3D culture of pancreatic acinar cells and experiments in LSL-KrasG12D/+;Pdx1-Cre (KC) mice, we found that pharmacological inhibition of SREBP1 suppressed pancreatic tumorigenesis. In vitro, either knockdown or pharmacological inhibition of SREBP1 suppressed tumor proliferation but SREBP1 overexpression promoted tumor proliferation. In LSL-KrasG12D/+;Trp53fl/+;Pdx1-Cre (KPC) mice, we confirmed the tumor-promoting role of SREBP1 in pancreatic cancer progression. Mechanistically, we revealed SOX9 as a downstream target of SREPB1. SREBP1 inhibition decreased SOX9 expression in both acinar cells and pancreatic cancer cells. Indeed, we identified SREBP1 binding sites in the SOX9 promoter region and reported that SOX9 is transcriptionally regulated by SREBP1. Taken together, our findings demonstrate that SREBP1/SOX9 inhibition suppresses pancreatic cancer initiation and growth, suggesting that SREBP1 could serve as a potential target for cancer screening and treatment.

The switch triggering the invasion process: Lipid metabolism in the metastasis of hepatocellular carcinoma

ABSTRACT

In humans, the liver is a central metabolic organ with a complex and unique histological microenvironment. Hepatocellular carcinoma (HCC), which is a highly aggressive disease with a poor prognosis, accounts for most cases of primary liver cancer. As an emerging hallmark of cancers, metabolic reprogramming acts as a runaway mechanism that disrupts homeostasis of the affected organs, including the liver. Specifically, rewiring of the liver metabolic microenvironment, including lipid metabolism, is driven by HCC cells, propelling the phenotypes of HCC cells, including dissemination, invasion, and even metastasis in return. The resulting formation of this vicious loop facilitates various malignant behaviors of HCC further. However, few articles have comprehensively summarized lipid reprogramming in HCC metastasis. Here, we have reviewed the general situation of the liver microenvironment and the physiological lipid metabolism in the liver, and highlighted the effects of different aspects of lipid metabolism on HCC metastasis to explore the underlying mechanisms. In addition, we have recapitulated promising therapeutic strategies targeting lipid metabolism and the effects of lipid metabolic reprogramming on the efficacy of HCC systematical therapy, aiming to offer new perspectives for targeted therapy.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Molecular mechanism and therapeutic significance of essential amino acids in metabolically associated fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), also known as metabolically associated fatty liver disease (MAFLD), is a systemic metabolic disease characterized by lipid accumulation in the liver, lipid toxicity, insulin resistance, intestinal dysbiosis, and inflammation that can progress from simple steatosis to nonalcoholic steatohepatitis (NASH) and even cirrhosis or cancer. It is the most prevalent illness threatening world health. Currently, there are almost no approved drug interventions for MAFLD, mainly dietary changes and exercise to control weight and regulate metabolic disorders. Meanwhile, the metabolic pathway involved in amino acid metabolism also influences the onset and development of MAFLD in the body, and most amino acid metabolism takes place in the liver. Essential amino acids are those amino acids that must be supplemented from outside the diet and that cannot be synthesized in the body or cannot be synthesized at a rate sufficient to meet the body's needs, including leucine, isoleucine, valine (collectively known as branched-chain amino acids), tryptophan, phenylalanine (which are aromatic amino acids), histidine, methionine, threonine and lysine. The metabolic balance of the body is closely linked to these essential amino acids, and essential amino acids are closely linked to the pathophysiological process of MAFLD. In this paper, we will focus on the metabolism of essential amino acids in the body and further explore the therapeutic strategies for MAFLD based on the studies conducted in recent years.

The implications of FASN in immune cell biology and related diseases

Fatty acid metabolism, particularly fatty acid synthesis, is a very important cellular physiological process in which nutrients are used for energy storage and biofilm synthesis. As a key enzyme in the fatty acid metabolism, fatty acid synthase (FASN) is receiving increasing attention. Although previous studies on FASN have mainly focused on various malignancies, many studies have recently reported that FASN regulates the survival, differentiation, and function of various immune cells, and subsequently participates in the occurrence and development of immune-related diseases. However, few studies to date systematically summarized the function and molecular mechanisms of FASN in immune cell biology and related diseases. In this review, we discuss the regulatory effect of FASN on immune cells, and the progress in research on the implications of FASN in immune-related diseases. Understanding the function of FASN in immune cell biology and related diseases can offer insights into novel treatment strategies for clinical diseases.