Orlistat delays hepatocarcinogenesis in mice with hepatic co-activation of AKT and c-Met

Altered fatty acid metabolism rewires cholangiocarcinoma stemness features

Background & Aims

Among the reprogrammed metabolic pathways described in cancer stem cells, aberrant lipid metabolism has recently drawn increasing attention. Our study explored the contribution of fatty acids (FA) in the regulation of stem-like features in intrahepatic cholangiocarcinoma (iCCA).

Methods

We previously identified a functional stem-like subset in human iCCA by using a three-dimensional sphere (SPH) model in comparison to parental cells grown as monolayers (MON). In this study, quantification of intracellular free FA and lipidomic analysis (triacylglycerol [TAG] composition, de novo synthesis products) was performed by Liquid chromatography-mass spectrometry (LC-MS); quadrupole time-of-flight liquid chromatography/mass spectrometry (Q-TOF LC/MS), respectively, in both SPH and MON cultures.

Results

Stem-like SPH showed a superior content of free FA (citric, palmitic, stearic, and oleic acids) and unsaturated TAG. Molecularly, SPH showed upregulation of key metabolic enzymes involved in de novo FA biosynthesis (AceCS1, ACLY, ACAC, FASN, ACSL1) and the mTOR signalling pathway. In patients with iCCA (n = 68), tissue expression of FASN, a key gene involved in FA synthesis, correlated with 5-year overall survival. Interference with FASN activity in SPH cells through both specific gene silencing (siRNA) or pharmacological inhibition (orlistat) decreased sphere-forming ability and expression of stem-like markers. In a murine xenograft model obtained by injection of iCCA-SPH cells, FASN inhibition by orlistat or injection of FASN-silenced cells significantly reduced tumour growth and expression of stem-like genes.

Conclusion

Altered FA metabolism contributes to the maintenance of a stem-like phenotype in iCCA. FASN inhibition may represent a new approach to interfere with the progression of this deadly disease.

Impact and implications

Recent evidence indicates that metabolic disorders correlate with an increased susceptibility to intrahepatic cholangiocarcinoma (iCCA). Our investigation emphasises the pivotal involvement of lipid metabolism in the tumour stem cell biology of iCCA, facilitated by the upregulation of crucial enzymes and the mTOR signalling pathway. From a clinical perspective, this underscores the dual role of FASN as both a prognostic indicator and a therapeutic target, suggesting that FASN inhibitors could enhance patient outcomes by diminishing stemness and tumour aggressiveness. These findings pave the way for novel therapeutic strategies for iCCA and shed light on its relationship with metabolic disorders such as diabetes, obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease.

Pharmacovigilance analysis of orlistat adverse events based on the FDA adverse event reporting system (FAERS) database

Objective

Based on the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS) database, we analyzed the signals of potential adverse events (AEs) of orlistat in the real world to provide a reference for its safe clinical use.

Methods

The FAERS database and OpenVigil 2.1 were used to obtain data on adverse events of orlistat from the first quarter of 2004 to the first quarter of 2023, and to analyze the population in which the adverse events occurred. And the signals of their potential adverse events were mined using reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN) and empirical Bayesian geometric mean (EBGM).

Result

A total of 21,079 reports of adverse events with orlistat as the primary suspected drug were collected in this study. Using four disproportionate analyses, we screened 117 preferred terms (PTs) involving 18 system organ classes (SOCs). We found that the most common adverse events at SOC level for orlistat remained "gastrointestinal disorders", while "metabolism and nutrition disorders", "renal and urinary disorders", "musculoskeletal and connective tissue disorders" and "hepatobiliary disorders" also ranked high in the number of case reports. In addition, at the PT level, we identified several new signals of adverse events not mentioned in the specification, including "lipiduria", "anal haemorrhage", "rectal haemorrhage", "haematochezia", "sigmoiditis", "diverticulitis" and "muscle spasms".

Conclusion

Most of the adverse events found in this study are consistent with the results described in the drug label. At the same time, we also found some new adverse events, which require more prospective studies to verify and elucidate their relationship with orlistat.

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.

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.

Novel quinazoline-based dual EGFR/c-Met inhibitors overcoming drug resistance for the treatment of NSCLC: Design, synthesis and anti-tumor activity

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) have demonstrated the ability to impede tumor cell proliferation by suppressing EGFR expression. Nonetheless, patients undergoing treatment may acquire resistance, which may occur through an EGFR-dependent (such as T790M mutation) or an EGFR-independent (such as c-Met amplification) manner. Therefore, developing dual-target inhibitors might present a potential avenue for addressing treatment-acquired resistance in patients. Herein, we designed, synthesized, and screened several novel 4-phenoxyquinazoline derivatives, aiming to identify a potent dual EGFR/c-Met inhibitor for the treatment of NSCLC, among which H-22 emerged as the most promising candidate exhibiting significant antitumor properties. Moreover, we assessed the in vitro inhibitory effect of H-22 on EGFR kinase and c-Met kinase in five cancer cell lines. In addition, a series of functional experiments (cell cycle, apoptosis assays, in vitro/in vivo animal model, etc.) were conducted to further investigate the anti-tumor mechanisms of H-22. The present study revealed that H-22 exhibited strong antitumor activity both in vitro and in vivo. Interestingly, H-22 exhibited anti-proliferative activity (2.27-3.35 μM) similar to Afatinib against all five cancer cells, with inhibitory functions against EGFRWT, EGFRL858R/T790M, and c-Met kinases at a concentration of 64.8, 305.4 and 137.4 nM, respectively. Cell cycle analysis indicated that the antiproliferative activity of H-22 was associated with its ability to cause G2/M arrest. Furthermore, in vivo data showed that H-22 could inhibit tumor growth in our xenograft models and induce apoptosis. Collectively, our findings uncovered that H-22 is a novel dual EGFR and c-Met inhibitor and a prospective anti-tumor therapeutic drug.

Single-cell RNA-sequencing atlas reveals an FABP1-dependent immunosuppressive environment in hepatocellular carcinoma

BACKGROUND

Single-cell RNA sequencing, also known as scRNA-seq, is a method profiling cell populations on an individual cell basis. It is particularly useful for more deeply understanding cell behavior in a complicated tumor microenvironment. Although several previous studies have examined scRNA-seq for hepatocellular carcinoma (HCC) tissues, no one has tested and analyzed HCC with different stages.

METHODS

In this investigation, immune cells isolated from surrounding normal tissues and cancer tissues from 3 II-stage and 4 III-stage HCC cases were subjected to deep scRNA-seq. The analysis included 15 samples. We distinguished developmentally relevant trajectories, unique immune cell subtypes, and enriched pathways regarding differential genes. Western blot and co-immunoprecipitation were performed to demonstrate the interaction between fatty acid binding protein 1 (FABP1) and peroxisome proliferator-activated receptor gamma(PPARG). In vivo experiments were performed in a C57BL/6 mouse model of HCC established via subcutaneous injection.

RESULTS

FABP1 was discovered to be overexpressed in tumor-associated macrophages (TAMs) with III-stage HCC tissues compared with II-stage HCC tissues. This finding was fully supported by immunofluorescence detection in significant amounts of HCC human samples. FABP1 deficiency in TAMs inhibited HCC progression in vitro. Mechanistically, FABP1 interacted with PPARG/CD36 in TAMs to increase fatty acid oxidation in HCC. When compared with C57BL/6 mice of the wild type, tumors in FABP1-/- mice consistently showed attenuation. The FABP1-/- group's relative proportion of regulatory T cells and natural killer cells showed a downward trend, while dendritic cells, M1 macrophages, and B cells showed an upward trend, according to the results of mass cytometry. In further clinical translation, we found that orlistat significantly inhibited FABP1 activity, while the combination of anti-programmed cell death 1(PD-1) could synergistically treat HCC progression. Liposomes loaded with orlistat and connected with IR780 probe could further enhance the therapeutic effect of orlistat and visualize drug metabolism in vivo.

CONCLUSIONS

ScRNA-seq atlas revealed an FABP1-dependent immunosuppressive environment in HCC. Orlistat significantly inhibited FABP1 activity, while the combination of anti-PD-1 could synergistically treat HCC progression. This study identified new treatment targets and strategies for HCC progression, contributing to patients with advanced HCC from new perspectives.

Pharmacological effect and mechanism of orlistat in anti-tumor therapy: A review

Research has demonstrated that obesity is an important risk factor for cancer progression. Orlistat is a lipase inhibitor with promising therapeutic effects on obesity. In addition to being regarded as a slimming drug, a growing number of studies in recent years have suggested that orlistat has anti-tumor activities, while the underlying mechanism is still not well elucidated. This paper reviewed recent pharmacological effects and mechanisms of orlistat against tumors and found that orlistat can target cancer cells through activation or suppression of multiple signaling pathways. It can induce tumor cells apoptosis or death, interfere with tumor cells' cycles controlling, suppress fatty acid synthase activity, increase ferroptosis, inhibit tumor angiogenesis, and improve tumor cells glycolytic. Thus, this review may shed new light on anti-tumor mechanism and drug repurposing of orlistat, and anti-tumor drug development.

Fatty acid metabolism: A new therapeutic target for cervical cancer

Cervical cancer (CC) is one of the most common malignancies in women. Cancer cells can use metabolic reprogramming to produce macromolecules and ATP needed to sustain cell growth, division and survival. Recent evidence suggests that fatty acid metabolism and its related lipid metabolic pathways are closely related to the malignant progression of CC. In particular, it involves the synthesis, uptake, activation, oxidation, and transport of fatty acids. Similarly, more and more attention has been paid to the effects of intracellular lipolysis, transcriptional regulatory factors, other lipid metabolic pathways and diet on CC. This study reviews the latest evidence of the link between fatty acid metabolism and CC; it not only reveals its core mechanism but also discusses promising targeted drugs for fatty acid metabolism. This study on the complex relationship between carcinogenic signals and fatty acid metabolism suggests that fatty acid metabolism will become a new therapeutic target in CC.

Enhanced De Novo Lipid Synthesis Mediated by FASN Induces Chemoresistance in Colorectal Cancer

BACKGROUND

Oxaliplatin is one of the most widely used chemotherapy drugs for colorectal cancer (CRC). Resistance to oxaliplatin threatens the prognosis of CRC. Since previous studies have aroused interest in fatty acid metabolism in cancer, in this study, we determined whether fatty acid biosynthesis and the related regulating mechanism contribute to oxaliplatin resistance in CRC.

METHODS

The effect of the fatty acid synthase (FASN) and its inhibitor Orlistat was characterized in Gene Expression Omnibus (GEO) databases, oxaliplatin-resistant cell lines, and xenografts. MRNA-seq and analysis identified related pathway changes after the application of Orlistat, which was verified by Western blotting.

RESULTS

By leveraging the GEO databases, FASN and closely related gene signatures were identified as being correlated with the response to oxaliplatin-based chemotherapy and poor prognosis. Additionally, FASN-upregulated expression promoted oxaliplatin resistance in CRC cell lines. We then applied Orlistat, a typical FASN inhibitor, in cell culture and xenograft models of oxaliplatin-resistant CRC, which attenuated the resistance to oxaliplatin. Additionally, the combination of the FASN inhibitor and oxaliplatin significantly increased cell cycle arrest and facilitated apoptosis, partly due to the diminished phosphorylation of the MAPK/ERK and PI3K/AKT pathways. In vivo studies showed that inhibiting fatty acid biosynthesis with Orlistat restrained the growth of xenograft tumors and increased the responsiveness to oxaliplatin.

CONCLUSIONS

Our study revealed that FASN enhanced resistance to oxaliplatin in CRC. The inhibition of FASN could rescue the response to oxaliplatin by regulating MAPK/ERK and PI3K/AKT pathways.

Sperm associated antigen 4 promotes SREBP1-mediated de novo lipogenesis via interaction with lamin A/C and contributes to tumor progression in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor and its progression is associated with altered lipid metabolism in precancerous lesions, such as non-alcoholic fatty liver disease. Here, we identified sperm associated antigen 4 (SPAG4), and explored its oncogenic role in HCC progression. Database analysis and immunohistochemistry indicated increased level of SPAG4 in HCC tissues which was of prognostic value. Gain/loss-of-function experiments showed that SPAG4 exerted oncogenic roles in HCC growth both in vitro and in vivo. RNA sequencing revealed activation of a lipogenic state and SREBP1-mediated pathway following SPAG4 overexpression. Mechanistically, the N-terminal region of SPAG4 bound to lamin A/C, which increased SREBP1 expression, nuclear translocation, and transcriptional activity. Treatment with orlistat, a lipid synthesis inhibitor, reversed SPAG4-mediated oncogenic effects, and its efficacy varied with SPAG4 level. The effect of orlistat was further amplified when combined with sorafenib in tumor xenograft mouse models. Our study provides evidence that SPAG4 mediates HCC progression by affecting lipid metabolism. Administration of orlistat combined with sorafenib reverses SPAG4-mediated oncogenesis in HCC cells and ectopic xenograft tumors in mice, suggesting that this pathway represents a potential target for HCC treatment.

Orlistat Resensitizes Sorafenib-Resistance in Hepatocellular Carcinoma Cells through Modulating Metabolism

Sorafenib is one of the options for advanced hepatocellular carcinoma treatment and has been shown to extend median overall survival. However, sorafenib resistance often develops a few months after treatment. Hence, developing various strategies to overcome sorafenib resistance and understand the possible mechanisms is urgently needed. We first established sorafenib-resistant hepatocellular carcinoma (HCC) cells. Then, we found that sorafenib-resistant Huh7 cells (Huh7/SR) exhibit higher glucose uptakes and express elevated fatty acid synthesis and glucose metabolism-related proteins than their parental counterparts (Huh7). The current study investigated whether sorafenib resistance could be reversed by suppressing fatty acid synthesis, using a fatty acid synthase (FASN) inhibitor, orlistat, in HCC cells. FASN inhibition-caused changes in protein expressions and cell cycle distribution were analyzed by Western blot and flow cytometry, and changes in glucose uptakes were also evaluated by ¹⁸F-FDG uptake. Orlistat remarkably enhanced the cytotoxicity of sorafenib in both Huh7 and Huh7/SR cells, and flow cytometry showed that combination treatment significantly increased the sub-G1 population in both cell lines. Western blot revealed that the combination treatment effectively increased the ratio of Bax/Bcl-2 and decreased expressions of pERK; additionally, the combination treatment also strongly suppressed fatty acid synthesis-related proteins (e.g., FASN and SCD) in both cell lines. Lastly, the ¹⁸F-FDG uptake was repressed by the combination treatment in both cell lines. Our results indicated that orlistat-mediated FASN inhibition could overcome sorafenib resistance and enhance cell killing in HCC by changing cell metabolism.

Lipid alterations in chronic liver disease and liver cancer

Lipids are a complex and diverse group of molecules with crucial roles in many physiological processes, as well as in the onset, progression, and maintenance of cancers. Fatty acids and cholesterol are the building blocks of lipids, orchestrating these crucial metabolic processes. In the liver, lipid alterations are prevalent as a cause and consequence of chronic hepatitis B and C virus infections, alcoholic hepatitis, and non-alcoholic fatty liver disease and steatohepatitis. Recent developments in lipidomics have also revealed that dynamic changes in triacylglycerols, phospholipids, sphingolipids, ceramides, fatty acids, and cholesterol are involved in the development and progression of primary liver cancer. Accordingly, the transcriptional landscape of lipid metabolism suggests a carcinogenic role of increasing fatty acids and sterol synthesis. However, limited mechanistic insights into the complex nature of the hepatic lipidome have so far hindered the development of effective therapies.

Role of Lipogenesis Rewiring in Hepatocellular Carcinoma

Metabolic rewiring is one of the hallmarks of cancer. Altered de novo lipogenesis is one of the pivotal metabolic events deregulated in cancers. Sterol regulatory element-binding transcription factor 1 (SREBP1) controls the transcription of major enzymes involved in de novo lipogenesis, including ACLY, ACACA, FASN, and SCD. Studies have shown the increased de novo lipogenesis in human hepatocellular carcinoma (HCC) samples. Multiple mechanisms, such as activation of the AKT/mechanistic target of rapamycin (mTOR) pathway, lead to high SREBP1 induction and the coordinated enhanced expression of ACLY, ACACA, FASN, and SCD genes. Subsequent functional analyses have unraveled these enzymes' critical role(s) and the related de novo lipogenesis in hepatocarcinogenesis. Importantly, targeting these molecules might be a promising strategy for HCC treatment. This paper comprehensively summarizes de novo lipogenesis rewiring in HCC and how this pathway might be therapeutically targeted.

Orlistat induces ferroptosis-like cell death of lung cancer cells

Aberrant de novo lipid synthesis is involved in the progression and treatment resistance of many types of cancers, including lung cancer; however, targeting the lipogenetic pathways for cancer therapy remains an unmet clinical need. In this study, we tested the anticancer activity of orlistat, an FDA-approved anti-obesity drug, in human and mouse cancer cells in vitro and in vivo, and we found that orlistat, as a single agent, inhibited the proliferation and viabilities of lung cancer cells and induced ferroptosis-like cell death in vitro. Mechanistically, we found that orlistat reduced the expression of GPX4, a central ferroptosis regulator, and induced lipid peroxidation. In addition, we systemically analyzed the genome-wide gene expression changes affected by orlistat treatment using RNA-seq and identified FAF2, a molecule regulating the lipid droplet homeostasis, as a novel target of orlistat. Moreover, in a mouse xenograft model, orlistat significantly inhibited tumor growth and reduced the tumor volumes compared with vehicle control (P < 0.05). Our study showed a novel mechanism of the anticancer activity of orlistat and provided the rationale for repurposing this drug for the treatment of lung cancer and other types of cancer.