Stearoyl-CoA desaturase regulates sorafenib resistance via modulation of ER stress-induced differentiation

Metabolic adaptations in cancer stem cells: A key to therapy resistance

Cancer stem cells (CSCs) are a subset of tumor cells that can initiate and sustain tumor growth and cause recurrence and metastasis. CSCs are particularly resistant to conventional therapies compared to their counterparts, owing greatly to their intrinsic metabolic plasticity. Metabolic plasticity allows CSCs to switch between different energy production and usage pathways based on environmental and extrinsic factors, including conditions imposed by conventional cancer therapies. To cope with nutrient deprivation and therapeutic stress, CSCs can transpose between glycolysis and oxidative phosphorylation (OXPHOS) metabolism. The mechanism behind the metabolic pathway switch in CSCs is not fully understood, however, some evidence suggests that the tumor microenvironment (TME) may play an influential role mediated by its release of signals, such as Wnt/β-catenin and Notch pathways, as well as a background of hypoxia. Exploring the factors that promote metabolic plasticity in CSCs offers the possibility of eventually developing therapies that may more effectively eliminate the crucial tumor cell subtype and alter the disease course substantially.

Comprehensive analysis of bulk and single-cell transcriptomic data reveals a novel signature associated with endoplasmic reticulum stress, lipid metabolism, and liver metastasis in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with high probability of recurrence and distant metastasis. Liver metastasis is the predominant metastatic mode developed in most pancreatic cancer cases, which seriously affects the overall survival rate of patients. Abnormally activated endoplasmic reticulum stress and lipid metabolism reprogramming are closely related to tumor growth and metastasis. This study aims to construct a prognostic model based on endoplasmic reticulum stress and lipid metabolism for pancreatic cancer, and further explore its correlation with tumor immunity and the possibility of immunotherapy.

METHODS

Transcriptomic and clinical data are acquired from TCGA, ICGC, and GEO databases. Potential prognostic genes were screened by consistent clustering and WGCNA methods, and the whole cohort was randomly divided into training and testing groups. The prognostic model was constructed by machine learning method in the training cohort and verified in the test, TCGA and ICGC cohorts. The clinical application of this model and its relationship with tumor immunity were analyzed, and the relationship between endoplasmic reticulum stress and intercellular communication was further explored.

RESULTS

A total of 92 characteristic genes related to endoplasmic reticulum stress, lipid metabolism and liver metastasis were identified in pancreatic cancer. We established and validated a prognostic model for pancreatic cancer with 7 signatures, including ADH1C, APOE, RAP1GAP, NPC1L1, P4HB, SOD2, and TNFSF10. This model is considered to be an independent prognosticator and is a more accurate predictor of overall survival than age, gender, and stage. TIDE score was increased in high-risk group, while the infiltration levels of CD8+ T cells and M1 macrophages were decreased. The number and intensity of intercellular communication were increased in the high ER stress group.

CONCLUSIONS

We constructed and validated a novel prognostic model for pancreatic cancer, which can also be used as an instrumental variable to predict the prognosis and immune microenvironment. In addition, this study revealed the effect of ER stress on cell-cell communication in the tumor microenvironment.

Comprehensive analysis of m6A modification in immune infiltration, metabolism and drug resistance in hepatocellular carcinoma

N6-methyladenosine (m6A) is important in regulating mRNA stability, splicing, and translation, and it also contributes to tumor development. However, there is still limited understanding of the comprehensive effects of m6A modification patterns on the tumor immune microenvironment, metabolism, and drug resistance in hepatocellular carcinoma (HCC). In this study, we utilized unsupervised clustering based on the expression of 23 m6A regulators to identify m6A clusters. We identified differential m6A modification patterns and characterized m6A-gene-cluster A, which exhibited poorer survival rates, a higher abundance of Treg cells, and increased expression of TGFβ in the tumor microenvironment (TME). Additionally, m6A-gene-cluster A demonstrated higher levels of glycolysis activity, cholesterol metabolism, and fatty acid biosynthesis. We also found that the m6A score was associated with prognosis and drug resistance. Patients with a low m6A score experienced worse prognoses, which were linked to an abundance of Treg cells, upregulation of TGFβ, and increased metabolic activity. HCC patients with a higher m6A score showed improved prognosis following sorafenib treatment and immunotherapy. In conclusion, we reveals the association between m6A modification patterns and the tumor immune microenvironment, metabolism, and drug resistance in HCC. Furthermore, the m6A score holds potential as a predictive factor for the efficacy of targeted therapy and immunotherapy in HCC.

Lipid Metabolism as a Potential Target of Liver Cancer

Hepatocellular carcinoma (HCC) stands as a severe malignant tumor with a profound impact on overall health, often accompanied by an unfavorable prognosis. Despite some advancements in the diagnosis and treatment of this disease, improving the prognosis of HCC remains a formidable challenge. It is noteworthy that lipid metabolism plays a pivotal role in the onset, development, and progression of tumor cells. Existing research indicates the potential application of targeting lipid metabolism in the treatment of HCC. This review aims to thoroughly explore the alterations in lipid metabolism in HCC, offering a detailed account of the potential advantages associated with innovative therapeutic strategies targeting lipid metabolism. Targeting lipid metabolism holds promise for potentially enhancing the prognosis of HCC.

BAP18 acting as a novel peroxisome proliferator-activated receptor α co-regulator contributes to hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is a common malignancy worldwide with a poor prognosis. The therapeutic outcomes of HCC patients are urgently needed to be improved, and predictive biomarkers for the optimal treatment selection remains to be further defined. In the present study, our results showed that BPTF-associated protein of 18 KDa (BAP18) was highly expressed in HCC tissues. In cultured HCC cells, BAP18 regulated a subset of down-stream genes involved in different functions, particularly including peroxisome proliferator-activated receptor (PPAR) pathway and lipid metabolism. Furthermore, BAP18 co-activated PPARα-mediated transactivation and facilitated the recruitment of nucleosome acetyltransferase of H4 (NuA4)/tat interacting protein 60 (TIP60) complex, thereby increasing histone H4 acetylation on stearoyl-CoA desaturase 1 (SCD1) loci. In addition, BAP18 promoted HCC cell proliferation, increased intracellular lipid levels and enhanced cell survival under the metabolic stress conditions, such as glucose limitation or tyrosine kinase inhibitors (TKIs) treatment. Importantly, higher BAP18 expression was positively correlated with the postoperative recurrence and the poor disease-free survival in clinical patients receiving sorafenib treatment. Altogether, we discovered that BAP18 plays an oncogenic role in the survival and proliferation of HCC cells, and BAP18 may serve as a predictive biomarker for adjunct TKIs treatment in patients with HCC, and further facilitate the precise treatment.

Advances in Targeted Drug Resistance Associated with Dysregulation of Lipid Metabolism in Hepatocellular Carcinoma

Hepatocellular carcinoma is the prevailing malignant neoplasm affecting the liver, often diagnosed at an advanced stage and associated with an unfavorable overall prognosis. Sorafenib and Lenvatinib have emerged as first-line therapeutic drugs for advanced hepatocellular carcinoma, improving the prognosis for these patients. Nevertheless, the issue of tyrosine kinase inhibitor (TKI) resistance poses a substantial obstacle in the management of advanced hepatocellular carcinoma. The pathogenesis and advancement of hepatocellular carcinoma exhibit a close association with metabolic reprogramming, yet the attention given to lipid metabolism dysregulation in hepatocellular carcinoma development remains relatively restricted. This review summarizes the potential significance and research progress of lipid metabolism dysfunction in Sorafenib and Lenvatinib resistance in hepatocellular carcinoma. Targeting hepatocellular carcinoma lipid metabolism holds promising potential as an effective strategy to overcome hepatocellular carcinoma drug resistance in the future.

Retention time prediction and MRM validation reinforce the biomarker identification of LC-MS based phospholipidomics

Dysfunctional lipid metabolism plays a crucial role in the development and progression of various diseases. Accurate measurement of lipidomes can help uncover the complex interactions between genes, proteins, and lipids in health and diseases. The prediction of retention time (RT) has become increasingly important in both targeted and untargeted metabolomics. However, the potential impact of RT prediction on targeted LC-MS based lipidomics is still not fully understood. Herein, we propose a simplified workflow for predicting RT in phospholipidomics. Our approach involves utilizing the fatty acyl chain length or carbon-carbon double bond (DB) number in combination with multiple reaction monitoring (MRM) validation. We found that our model's predictive capacity for RT was comparable to that of a publicly accessible program (QSRR Automator). Additionally, MRM validation helped in further mitigating the interference in signal recognition. Using this developed workflow, we conducted phospholipidomics of sorafenib resistant hepatocellular carcinoma (HCC) cell lines, namely MHCC97H and Hep3B. Our findings revealed an abundance of monounsaturated fatty acyl (MUFA) or polyunsaturated fatty acyl (PUFA) phospholipids in these cell lines after developing drug resistance. In both cell lines, a total of 29 lipids were found to be co-upregulated and 5 lipids were co-downregulated. Further validation was conducted on seven of the upregulated lipids using an independent dataset, which demonstrates the potential for translation of the established workflow or the lipid biomarkers.

Current trends and future prospects of drug repositioning in gastrointestinal oncology

Gastrointestinal (GI) cancers comprise a significant number of cancer cases worldwide and contribute to a high percentage of cancer-related deaths. To improve survival rates of GI cancer patients, it is important to find and implement more effective therapeutic strategies with better prognoses and fewer side effects. The development of new drugs can be a lengthy and expensive process, often involving clinical trials that may fail in the early stages. One strategy to address these challenges is drug repurposing (DR). Drug repurposing is a developmental strategy that involves using existing drugs approved for other diseases and leveraging their safety and pharmacological data to explore their potential use in treating different diseases. In this paper, we outline the existing therapeutic strategies and challenges associated with GI cancers and explore DR as a promising alternative approach. We have presented an extensive review of different DR methodologies, research efforts and examples of repurposed drugs within various GI cancer types, such as colorectal, pancreatic and liver cancers. Our aim is to provide a comprehensive overview of employing the DR approach in GI cancers to inform future research endeavors and clinical trials in this field.

LncRNAs-circRNAs as Rising Epigenetic Binary Superstars in Regulating Lipid Metabolic Reprogramming of Cancers

As one of novel hallmarks of cancer, lipid metabolic reprogramming has recently been becoming fascinating and widely studied. Lipid metabolic reprogramming in cancer is shown to support carcinogenesis, progression, distal metastasis, and chemotherapy resistance by generating ATP, biosynthesizing macromolecules, and maintaining appropriate redox status. Notably, increasing evidence confirms that lipid metabolic reprogramming is under the control of dysregulated non-coding RNAs in cancer, especially lncRNAs and circRNAs. This review highlights the present research findings on the aberrantly expressed lncRNAs and circRNAs involved in the lipid metabolic reprogramming of cancer. Emphasis is placed on their regulatory targets in lipid metabolic reprogramming and associated mechanisms, including the clinical relevance in cancer through lipid metabolism modulation. Such insights will be pivotal in identifying new theranostic targets and treatment strategies for cancer patients afflicted with lipid metabolic reprogramming.

Targeting metabolic reprogramming in hepatocellular carcinoma to overcome therapeutic resistance: A comprehensive review

Hepatocellular carcinoma (HCC) poses a heavy burden on human health with high morbidity and mortality rates. Systematic therapy is crucial for advanced and mid-term HCC, but faces a significant challenge from therapeutic resistance, weakening drug effectiveness. Metabolic reprogramming has gained attention as a key contributor to therapeutic resistance. Cells change their metabolism to meet energy demands, adapt to growth needs, or resist environmental pressures. Understanding key enzyme expression patterns and metabolic pathway interactions is vital to comprehend HCC occurrence, development, and treatment resistance. Exploring metabolic enzyme reprogramming and pathways is essential to identify breakthrough points for HCC treatment. Targeting metabolic enzymes with inhibitors is key to addressing these points. Inhibitors, combined with systemic therapeutic drugs, can alleviate resistance, prolong overall survival for advanced HCC, and offer mid-term HCC patients a chance for radical resection. Advances in metabolic research methods, from genomics to metabolomics and cells to organoids, help build the HCC metabolic reprogramming network. Recent progress in biomaterials and nanotechnology impacts drug targeting and effectiveness, providing new solutions for systemic therapeutic drug resistance. This review focuses on metabolic enzyme changes, pathway interactions, enzyme inhibitors, research methods, and drug delivery targeting metabolic reprogramming, offering valuable references for metabolic approaches to HCC treatment.

Circadian clock and lipid metabolism disorders: a potential therapeutic strategy for cancer

Recent research has emphasized the interaction between the circadian clock and lipid metabolism, particularly in relation to tumors. This review aims to explore how the circadian clock regulates lipid metabolism and its impact on carcinogenesis. Specifically, targeting key enzymes involved in fatty acid synthesis (SREBP, ACLY, ACC, FASN, and SCD) has been identified as a potential strategy for cancer therapy. By disrupting these enzymes, it may be possible to inhibit tumor growth by interfering with lipid metabolism. Transcription factors, like SREBP play a significant role in regulating fatty acid synthesis which is influenced by circadian clock genes such as BMAL1, REV-ERB and DEC. This suggests a strong connection between fatty acid synthesis and the circadian clock. Therefore, successful combination therapy should target fatty acid synthesis in addition to considering the timing and duration of drug use. Ultimately, personalized chronotherapy can enhance drug efficacy in cancer treatment and achieve treatment goals.

Resensitizing Paclitaxel-Resistant Ovarian Cancer via Targeting Lipid Metabolism Key Enzymes CPT1A, SCD and FASN

Epithelial ovarian cancer (EOC) is a lethal gynecological cancer, of which paclitaxel resistance is the major factor limiting treatment outcomes, and identification of paclitaxel resistance-related genes is arduous. We obtained transcriptomic data from seven paclitaxel-resistant ovarian cancer cell lines and corresponding sensitive cell lines. Define genes significantly up-regulated in at least three resistant cell lines, meanwhile they did not down-regulate in the other resistant cell lines as candidate genes. Candidate genes were then ranked according to the frequencies of significant up-regulation in resistant cell lines, defining genes with the highest rankings as paclitaxel resistance-related genes (PRGs). Patients were grouped based on the median expression of PRGs. The lipid metabolism-related gene set and the oncological gene set were established and took intersections with genes co-upregulated with PRGs, obtaining 229 co-upregulated genes associated with lipid metabolism and tumorigenesis. The PPI network obtained 19 highly confidential synergistic targets (interaction score > 0.7) that directly associated with CPT1A. Finally, FASN and SCD were up-stream substrate provider and competitor of CPT1A, respectively. Western blot and qRT-PCR results confirmed the over-expression of CPT1A, SCD and FASN in the A2780/PTX cell line. The inhibition of CPT1A, SCD and FASN down-regulated cell viability and migration, pharmacological blockade of CPT1A and SCD increased apoptosis rate and paclitaxel sensitivity of A2780/PTX. In summary, our novel bioinformatic methods can overcome difficulties in drug resistance evaluation, providing promising therapeutical strategies for paclitaxel-resistant EOC via taregting lipid metabolism-related enzymes.

ENO2-derived phosphoenolpyruvate functions as an endogenous inhibitor of HDAC1 and confers resistance to antiangiogenic therapy

Metabolic reprogramming is associated with resistance to antiangiogenic therapy in cancer. However, its molecular mechanisms have not been clearly elucidated. Here, we identify the glycolytic enzyme enolase 2 (ENO2) as a driver of resistance to antiangiogenic therapy in colorectal cancer (CRC) mouse models and human participants. ENO2 overexpression induces neuroendocrine differentiation, promotes malignant behaviour in CRC and desensitizes CRC to antiangiogenic drugs. Mechanistically, the ENO2-derived metabolite phosphoenolpyruvate (PEP) selectively inhibits histone deacetylase 1 (HDAC1) activity, which increases the acetylation of β-catenin and activates the β-catenin pathway in CRC. Inhibition of ENO2 with enolase inhibitors AP-III-a4 or POMHEX synergizes the efficacy of antiangiogenic drugs in vitro and in mice bearing drug-resistant CRC xenograft tumours. Together, our findings reveal that ENO2 constitutes a useful predictive biomarker and therapeutic target for resistance to antiangiogenic therapy in CRC, and uncover a previously undefined and metabolism-independent role of PEP in regulating resistance to antiangiogenic therapy by functioning as an endogenous HDAC1 inhibitor.

Fatty acids in cancer chemoresistance

Despite the remarkable clinical success of immunotherapy and molecular targeted therapy in patients with advanced tumors, chemotherapy remains the most commonly used treatment for most tumor patients. Chemotherapy drugs effectively inhibit tumor cell proliferation and survival through their remarkable mechanisms. However, tumor cells often develop severe intrinsic and acquired chemoresistance under chemotherapy stress, limiting the effectiveness of chemotherapy and leading to treatment failure. Growing evidence suggests that alterations in lipid metabolism may be implicated in the development of chemoresistance in tumors. Therefore, in this review, we provide a comprehensive overview of fatty acid metabolism and its impact on chemoresistance mechanisms. Additionally, we discuss the potential of targeting fatty acid metabolism as a therapeutic strategy to overcome drug resistance.

Lipid metabolism as a target for cancer drug resistance: progress and prospects

Cancer is the world's leading cause of human death today, and the treatment process of cancer is highly complex. Chemotherapy and targeted therapy are commonly used in cancer treatment, and the emergence of drug resistance is a significant problem in cancer treatment. Therefore, the mechanism of drug resistance during cancer treatment has become a hot issue in current research. A series of studies have found that lipid metabolism is closely related to cancer drug resistance. This paper details the changes of lipid metabolism in drug resistance and how lipid metabolism affects drug resistance. More importantly, most studies have reported that combination therapy may lead to changes in lipid-related metabolic pathways, which may reverse the development of cancer drug resistance and enhance or rescue the sensitivity to therapeutic drugs. This paper summarizes the progress of drug design targeting lipid metabolism in improving drug resistance, and providing new ideas and strategies for future tumor treatment. Therefore, this paper reviews the issues of combining medications with lipid metabolism and drug resistance.

Toward a Unifying Hypothesis for Redesigned Lipid Catabolism as a Clinical Target in Advanced, Treatment-Resistant Carcinomas

We review extensive progress from the cancer metabolism community in understanding the specific properties of lipid metabolism as it is redesigned in advanced carcinomas. This redesigned lipid metabolism allows affected carcinomas to make enhanced catabolic use of lipids in ways that are regulated by oxygen availability and is implicated as a primary source of resistance to diverse treatment approaches. This oxygen control permits lipid catabolism to be an effective energy/reducing potential source under the relatively hypoxic conditions of the carcinoma microenvironment and to do so without intolerable redox side effects. The resulting robust access to energy and reduced potential apparently allow carcinoma cells to better survive and recover from therapeutic trauma. We surveyed the essential features of this advanced carcinoma-specific lipid catabolism in the context of treatment resistance and explored a provisional unifying hypothesis. This hypothesis is robustly supported by substantial preclinical and clinical evidence. This approach identifies plausible routes to the clinical targeting of many or most sources of carcinoma treatment resistance, including the application of existing FDA-approved agents.

Serum Free Fatty Acid Changes Caused by High Expression of Stearoyl-CoA Desaturase 1 in Tumor Tissues Are Early Diagnostic Markers for Ovarian Cancer

Ovarian cancer has a poor prognosis and is difficult to detect in early stages. Therefore, developing new diagnostic markers for early-stage ovarian cancer is critical. Here, we developed a diagnostic marker for early-stage ovarian cancer on the basis of fatty acid metabolism characteristics of cancer cells. The expression of various fatty acid metabolizing enzymes such as stearoyl-CoA desaturase 1 (SCD1) was altered in early-stage ovarian cancer tissue compared with that in normal ovarian tissue. Changes in the expression of fatty acid metabolizing enzymes, particularly SCD1, in cancer tissues were found to alter concentrations of multiple free fatty acids (FFA) in serum. We were the first to show that fatty acid metabolic characteristics in tissues are related to the FFA composition of serum. Surprisingly, patients with stage I/II ovarian cancer also showed significant changes in serum levels of eight FFAs, which can be early diagnostic markers. Finally, using statistical analysis, an optimal early diagnostic model combining oleic and arachidic acid levels, fatty acids associated with SCD1, was established and confirmed to have higher diagnostic power than CA125, regardless of histology. Thus, our newly developed diagnostic model using serum FFAs may be a powerful tool for the noninvasive early detection of ovarian cancer.

SIGNIFICANCE

Measurement of serum FFA levels by changes in the expression of fatty acid metabolizing enzymes in tumor tissue would allow early detection of ovarian cancer. In particular, the SCD1-associated FFAs, oleic and arachidic acid, would be powerful new screening tools for early-stage ovarian cancer.

Lipid metabolic reprogramming in tumor microenvironment: from mechanisms to therapeutics

Lipid metabolic reprogramming is an emerging hallmark of cancer. In order to sustain uncontrolled proliferation and survive in unfavorable environments that lack oxygen and nutrients, tumor cells undergo metabolic transformations to exploit various ways of acquiring lipid and increasing lipid oxidation. In addition, stromal cells and immune cells in the tumor microenvironment also undergo lipid metabolic reprogramming, which further affects tumor functional phenotypes and immune responses. Given that lipid metabolism plays a critical role in supporting cancer progression and remodeling the tumor microenvironment, targeting the lipid metabolism pathway could provide a novel approach to cancer treatment. This review seeks to: (1) clarify the overall landscape and mechanisms of lipid metabolic reprogramming in cancer, (2) summarize the lipid metabolic landscapes within stromal cells and immune cells in the tumor microenvironment, and clarify their roles in tumor progression, and (3) summarize potential therapeutic targets for lipid metabolism, and highlight the potential for combining such approaches with other anti-tumor therapies to provide new therapeutic opportunities for cancer patients.

Integrated analysis revealing a novel stemness-metabolism-related gene signature for predicting prognosis and immunotherapy response in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant lethal tumor and both cancer stem cells (CSCs) and metabolism reprogramming have been proven to play indispensable roles in HCC. This study aimed to reveal the connection between metabolism reprogramming and the stemness characteristics of HCC, established a new gene signature related to stemness and metabolism and utilized it to assess HCC prognosis and immunotherapy response. The clinical information and gene expression profiles (GEPs) of 478 HCC patients came from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA). The one-class logistic regression (OCLR) algorithm was employed to calculate the messenger ribonucleic acid expression-based stemness index (mRNAsi), a new stemness index quantifying stemness features. Differentially expressed analyses were done between high- and low-mRNAsi groups and 74 differentially expressed metabolism-related genes (DEMRGs) were identified with the help of metabolism-related gene sets from Molecular Signatures Database (MSigDB). After integrated analysis, a risk score model based on the three most efficient prognostic DEMRGs, including Recombinant Phosphofructokinase Platelet (PFKP), phosphodiesterase 2A (PDE2A) and UDP-glucuronosyltransferase 1A5 (UGT1A5) was constructed and HCC patients were divided into high-risk and low-risk groups. Significant differences were found in pathway enrichment, immune cell infiltration patterns, and gene alterations between the two groups. High-risk group patients tended to have worse clinical outcomes and were more likely to respond to immunotherapy. A stemness-metabolism-related model composed of gender, age, the risk score model and tumor-node-metastasis (TNM) staging was generated and showed great discrimination and strong ability in predicting HCC prognosis and immunotherapy response.

Radiosynthesis and Preliminary Evaluation of [11C]SSI-4 for the Positron Emission Tomography Imaging of Stearoyl CoA Desaturase 1

Stearoyl CoA desaturase 1 (SCD1) is the rate-limiting enzyme for converting saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs) and plays a key role in endogenous (de novo) fatty acid metabolism. Given that this pathway is broadly upregulated across many tumor types with an aggressive phenotype, SCD1 has emerged as a compelling target for cancer imaging and therapy. The ligand 2-(4-(2-chlorophenoxy)piperidine-1-carboxamido)-N-methylisonicotinamide (SSI-4) was identified as a potent and highly specific SCD1 inhibitor with a strong binding affinity for SCD1 at our laboratory. We herein report the radiosynthesis of [11C]SSI-4 and the preliminary biological evaluation including in vivo PET imaging of SCD1 in a human tumor xenograft model. Radiotracer [11C]SSI-4 was labeled at the carbamide position via the direct [11C]CO2 fixation on the Synthra MeIplus module in high molar activity and good radiochemical yield. In vitro cell uptake assays were performed with three hepatocellular carcinoma (HCC) cell lines and three renal cell carcinoma (RCC) cell lines. Additionally, in vivo small animal PET/CT imaging with [11C]SSI-4 and the biodistribution were carried out in a mouse model bearing HCC xenografts. Radiotracer [11C]SSI-4 afforded a 4.14 ± 0.44% (decay uncorrected, n = 10) radiochemical yield based on starting [11]CO2 radioactivity. The [11C]SSI-4 radiosynthesis time including HPLC purification and SPE formulation was 25 min from the end of bombardment to the end of synthesis (EOS). The radiochemical purity of [11C]SSI-4 was 98.45 ± 1.43% (n = 10) with a molar activity of 225.82 ± 33.54 GBq/μmol (6.10 ± 0.91 Ci/μmol) at the EOS. In vitro cell uptake study indicated all SSI-4 responsive HCC and RCC cell line uptakes demonstrate specific uptake and are blocked by standard compound SSI-4. Preliminary small animal PET/CT imaging study showed high specific uptake and block of [11C]SSI-4 uptake with co-injection of cold SSI-4 in high SCD1-expressing organs including lacrimal gland, brown fat, liver, and tumor. In summary, novel radiotracer [11C]SSI-4 was rapidly and automatedly radiosynthesized by direct [11C]CO2 fixation. Our preliminary biological evaluation results suggest [11C]SSI-4 could be a promising radiotracer for PET imaging of SCD1 overexpressing tumor tissues.

ADAR1-mediated RNA editing of SCD1 drives drug resistance and self-renewal in gastric cancer

Targetable drivers governing 5-fluorouracil and cisplatin (5FU + CDDP) resistance remain elusive due to the paucity of physiologically and therapeutically relevant models. Here, we establish 5FU + CDDP resistant intestinal subtype GC patient-derived organoid lines. JAK/STAT signaling and its downstream, adenosine deaminases acting on RNA 1 (ADAR1), are shown to be concomitantly upregulated in the resistant lines. ADAR1 confers chemoresistance and self-renewal in an RNA editing-dependent manner. WES coupled with RNA-seq identify enrichment of hyper-edited lipid metabolism genes in the resistant lines. Mechanistically, ADAR1-mediated A-to-I editing on 3'UTR of stearoyl-CoA desaturase (SCD1) increases binding of KH domain-containing, RNA-binding, signal transduction-associated 1 (KHDRBS1), thereby augmenting SCD1 mRNA stability. Consequently, SCD1 facilitates lipid droplet formation to alleviate chemotherapy-induced ER stress and enhances self-renewal through increasing β-catenin expression. Pharmacological inhibition of SCD1 abrogates chemoresistance and tumor-initiating cell frequency. Clinically, high proteomic level of ADAR1 and SCD1, or high SCD1 editing/ADAR1 mRNA signature score predicts a worse prognosis. Together, we unveil a potential target to circumvent chemoresistance.

Stearoyl-CoA Desaturase 1 as a Therapeutic Biomarker: Focusing on Cancer Stem Cells

The dysregulation of lipid metabolism and alterations in the ratio of monounsaturated fatty acids (MUFAs) to saturated fatty acids (SFAs) have been implicated in cancer progression and stemness. Stearoyl-CoA desaturase 1 (SCD1), an enzyme involved in lipid desaturation, is crucial in regulating this ratio and has been identified as an important regulator of cancer cell survival and progression. SCD1 converts SFAs into MUFAs and is important for maintaining membrane fluidity, cellular signaling, and gene expression. Many malignancies, including cancer stem cells, have been reported to exhibit high expression of SCD1. Therefore, targeting SCD1 may provide a novel therapeutic strategy for cancer treatment. In addition, the involvement of SCD1 in cancer stem cells has been observed in various types of cancer. Some natural products have the potential to inhibit SCD1 expression/activity, thereby suppressing cancer cell survival and self-renewal activity.

Metabolic Reprogramming of HCC: A New Microenvironment for Immune Responses

Hepatocellular carcinoma is the most common primary liver cancer, ranking third among the leading causes of cancer-related mortality worldwide and whose incidence varies according to geographical area and ethnicity. Metabolic rewiring was recently introduced as an emerging hallmark able to affect tumor progression by modulating cancer cell behavior and immune responses. This review focuses on the recent studies examining HCC's metabolic traits, with particular reference to the alterations of glucose, fatty acid and amino acid metabolism, the three major metabolic changes that have gained attention in the field of HCC. After delivering a panoramic picture of the peculiar immune landscape of HCC, this review will also discuss how the metabolic reprogramming of liver cancer cells can affect, directly or indirectly, the microenvironment and the function of the different immune cell populations, eventually favoring the tumor escape from immunosurveillance.

Lipid metabolism of hepatocellular carcinoma impacts targeted therapy and immunotherapy

Hepatocellular carcinoma (HCC) is a common malignant tumor that affecting many people's lives globally. The common risk factors for HCC include being overweight and obese. The liver is the center of lipid metabolism, synthesizing most cholesterol and fatty acids. Abnormal lipid metabolism is a significant feature of metabolic reprogramming in HCC and affects the prognosis of HCC patients by regulating inflammatory responses and changing the immune microenvironment. Targeted therapy and immunotherapy are being explored as the primary treatment strategies for HCC patients with unresectable tumors. Here, we detail the specific changes of lipid metabolism in HCC and its impact on both these therapies for HCC. HCC treatment strategies aimed at targeting lipid metabolism and how to integrate them with targeted therapy or immunotherapy rationally are also presented.

Targeting autophagy and lipid metabolism in cancer stem cells

Cancer stem cells (CSCs) are a subset of cancer cells with self-renewal ability and tumor initiating properties. Unlike the other non-stem cancer cells, CSCs resist traditional therapy and remain a major cause of disease relapse. With the recent advances in metabolomics, various studies have demonstrated that CSCs have distinct metabolic properties. Metabolic reprogramming in CSCs contributes to self-renewal and maintenance of stemness. Accumulating evidence suggests that rewiring of energy metabolism is a key player that enables to meet energy demands, maintains stemness, and sustains cancer growth and invasion. CSCs use various mechanisms such as increased glycolysis, redox signaling and autophagy modulation to overcome nutritional deficiency and sustain cell survival. The alterations in lipid metabolism acquired by the CSCs support biomass production through increased dependence on fatty acid synthesis and β-oxidation and contribute to oncogenic signaling pathways. This review summarizes our current understanding of lipid metabolism in CSCs and how pharmacological regulation of autophagy and lipid metabolism influences CSC phenotype. Increased dependence on lipid metabolism appears as an attractive strategy to eliminate CSCs using therapeutic agents that specifically target CSCs based on their modulation of lipid metabolism.

ncRNA-mediated fatty acid metabolism reprogramming in HCC

The challenges of hepatocellular carcinoma (HCC) pathogenesis, diagnosis, treatment, and prognosis evaluation are obvious. Hepatocyte-specific fatty acid (FA) metabolic reprogramming is an important marker of liver carcinogenesis and progression; elucidating its mechanism will help unravel the complexity of HCC pathogenesis. Noncoding RNAs (ncRNAs) play important roles in HCC development. Moreover, ncRNAs are important mediators of FA metabolism and are directly involved in the reprogramming of FA metabolism in HCC cells. Here we review significant new advances in understanding the mechanisms regulating HCC metabolism by focusing on ncRNA-mediated post-translational modifications of metabolic enzymes, metabolism-related transcription factors, and other proteins in associated signaling pathways. We also discuss the great therapeutic potential of targeting ncRNA-mediated FA metabolism reprogramming in HCC.

Ferroptosis, Acyl Starvation, and Breast Cancer

To maintain their growth rate, cancer cells must secure a supply of fatty acids, which are necessary for building cell membranes and maintaining energy processes. This is one of the reasons why tissues with intensive fatty acid metabolism, such as the mammary gland, are more likely to develop tumors. One natural or induced defense process against cancer is ferroptosis, which interferes with normal fatty acid metabolism. This leads to the oxidation of polyunsaturated fatty acids, which causes a rearrangement of the metabolism and damages cell membranes. As a consequence of this oxidation, there is a shortage of normal polyunsaturated fatty acids, which disturbs the complicated metabolism of fatty acids. This imbalance in metabolism, resulting from the deficiency of properly structured fatty acids, is called, by these authors, "acyl starvation." When cancer cells are exposed to alternating hypoxia and reoxygenation, they often develop resistance to neoadjuvant therapies. Blocking the stearoyl-CoA desaturase - fatty acid-binding protein 4 - fatty acid translocase axis appears to be a promising pathway in the treatment of breast cancer. On the one hand, the inhibition of desaturase leads to the formation of toxic phospholipid hydroperoxides in ferroptosis, whereas on the other hand, the inhibition of fatty acid-binding protein 4 and translocase leads to a reduced uptake of fatty acids and disruption of the cellular transport of fatty acids, resulting in intracellular acyl starvation. The disruption in the metabolism of fatty acids in cancer cells may augment the effectiveness of neoadjuvant therapy. SIGNIFICANCE STATEMENT: Regulation of the metabolism of fatty acids in cancer cells seems to be a promising therapeutic direction. Studies show that the induction of ferroptosis in cancer cells, combined with use of neoadjuvant therapies, effectively inhibits the proliferation of these cells. We link the process of ferroptosis with apoptosis and SCD1-FABP4-CD36 axis and propose the term "acyl starvation" for the processes leading to FA deficiency, dysregulation of FA metabolism in cancer cells, and, most importantly, the appearance of incorrect proportions FAs.

RUNX2 interacts with SCD1 and activates Wnt/β-catenin signaling pathway to promote the progression of clear cell renal cell carcinoma

BACKGROUND

Previous studies have demonstrated that Runt-associated transcription factor 2 (RUNX2) serves as the main transcription factor for osteoblast differentiation and chondrocyte maturation. RUNX2 is related to a variety of tumors, particularly tumor invasion and metastasis, while the expression and molecular mechanisms of RUNX2 in clear cell renal cell carcinoma (ccRCC) keep to be determined. Stearyl CoA desaturase 1 (SCD1), an endoplasmic reticulum fatty acid desaturase, transfers saturated fatty acids to monounsaturated fatty acids, is expressed highly in numerous malignancies.

METHODS

The Cancer Genome Atlas (TCGA) datebase and Western blot was used to analyzed the mRNA and protein levels of the target gene in ccRCC tissues and adjacent tissues. The proliferation ability of ccRCC cells was tested by colony forming and EdU assay. The migration ability of cells was detected by transwell assay. Immunoprecipitation was utilized to detect protein-protein interaction. Cycloheximide chase assay was used to measure the half-life of SCD1 protein.

RESULTS

In this study, the expressions of RUNX2 and SCD1 are increased in ccRCC tissues as well as ccRCC cell lines. Both RUNX2 and SCD1 could promote proliferation and migration in ccRCC cells. Furthermore, RUNX2 could physically interact with SCD1. In addition, the functional degradation and the inactivation of Wnt/β-catenin signaling pathway triggered by the downregulation of RUNX2 could be partly offset by the overexpression of SCD1.

CONCLUSION

The findings indicate that the RUNX2/SCD1 axis may act as a potential therapeutic target via the Wnt/β-catenin signaling pathway of ccRCC.

Metabolism as a New Avenue for Hepatocellular Carcinoma Therapy

Hepatocellular carcinoma is today the sixth leading cause of cancer-related death worldwide, despite the decreased incidence of chronic hepatitis infections. This is due to the increased diffusion of metabolic diseases such as the metabolic syndrome, diabetes, obesity, and nonalcoholic steatohepatitis (NASH). The current protein kinase inhibitor therapies in HCC are very aggressive and not curative. From this perspective, a shift in strategy toward metabolic therapies may represent a promising option. Here, we review current knowledge on metabolic dysregulation in HCC and therapeutic approaches targeting metabolic pathways. We also propose a multi-target metabolic approach as a possible new option in HCC pharmacology.

Prognostic factor identification by screening changes in differentially expressed genes in oral squamous cell carcinoma

OBJECTIVE

This study was designed to identify changes in the expression of proteins occurring during the progression of oral squamous cell carcinoma (OSCC) and to validate their impact on patient prognosis.

MATERIALS AND METHODS

The human OSCC cell line UPCI-SCC-040 was treated in vitro with TGF-β1, and transcriptome analysis of differentially expressed genes (DEGs) revealed putative candidates relative to untreated cells. The respective protein expression levels of the most important genes were immunohistochemically validated on a tissue microarray (TMA) containing tissue samples from 39 patients with OSCC and were correlated with disease-free survival (DFS) as the primary clinical endpoint.

RESULTS

Our univariate Cox proportional hazard regression (CR) analysis revealed significant correlations among positive N stage (local lymph node metastasis, p = .04), stearoyl-CoA desaturase-1 (p < .01), sclerostin (p = .01), and CD137L expression (p = .04) and DFS. Stearoyl-CoA desaturase-1 and sclerostin remained the main prognostic factors (p < .01) in the multiple CR model.

CONCLUSION

We identified changes in differentially expressed genes during OSCC progression in vitro and translated the impact of the most deregulated genes on patient prognosis. Stearoyl-CoA desaturase-1 and sclerostin acted as independent prognostic factors in OSCC and could also be interesting candidates for new cancer targeted therapeutic approaches.

Epidemiologic, Genetic, Pathogenic, Metabolic, Epigenetic Aspects Involved in NASH-HCC: Current Therapeutic Strategies

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and is the sixth most frequent cancer in the world, being the third cause of cancer-related deaths. Nonalcoholic steatohepatitis (NASH) is characterized by fatty infiltration, oxidative stress and necroinflammation of the liver, with or without fibrosis, which can progress to advanced liver fibrosis, cirrhosis and HCC. Obesity, metabolic syndrome, insulin resistance, and diabetes exacerbates the course of NASH, which elevate the risk of HCC. The growing prevalence of obesity are related with increasing incidence of NASH, which may play a growing role in HCC epidemiology worldwide. In addition, HCC initiation and progression is driven by reprogramming of metabolism, which indicates growing appreciation of metabolism in the pathogenesis of this disease. Although no specific preventive pharmacological treatments have recommended for NASH, dietary restriction and exercise are recommended. This review focuses on the molecular connections between HCC and NASH, including genetic and risk factors, highlighting the metabolic reprogramming and aberrant epigenetic alterations in the development of HCC in NASH. Current therapeutic aspects of NASH/HCC are also reviewed.

The Emerging Role of Tumor Microenvironmental Stimuli in Regulating Metabolic Rewiring of Liver Cancer Stem Cells

Primary liver cancer (PLC) is one of the most devastating cancers worldwide. Extensive phenotypical and functional heterogeneity is a cardinal hallmark of cancer, including PLC, and is related to the cancer stem cell (CSC) concept. CSCs are responsible for tumor growth, progression, relapse and resistance to conventional therapies. Metabolic reprogramming represents an emerging hallmark of cancer. Cancer cells, including CSCs, are very plastic and possess the dynamic ability to constantly shift between different metabolic states depending on various intrinsic and extrinsic stimuli, therefore amplifying the complexity of understanding tumor heterogeneity. Besides the well-known Warburg effect, several other metabolic pathways including lipids and iron metabolism are altered in PLC. An increasing number of studies supports the role of the surrounding tumor microenvironment (TME) in the metabolic control of liver CSCs. In this review, we discuss the complex metabolic rewiring affecting liver cancer cells and, in particular, liver CSCs. Moreover, we highlight the role of TME cellular and noncellular components in regulating liver CSC metabolic plasticity. Deciphering the specific mechanisms regulating liver CSC-TME metabolic interplay could be very helpful with respect to the development of more effective and innovative combinatorial therapies for PLC treatment.

A review on the role of fatty acids in colorectal cancer progression

Colorectal cancer (CRC) is the third leading cause of mortality in cancer patients. The role of fatty acids (FA) and their metabolism in cancer, particularly in CRC raises a growing interest. In particular, dysregulation of synthesis, desaturation, elongation, and mitochondrial oxidation of fatty acids are involved. Here we review the current evidence on the link between cancer, in particular CRC, and fatty acids metabolism, not only to provide insight on its pathogenesis, but also on the development of novel biomarkers and innovative pharmacological therapies that are based on FAs dependency of cancer cells.

Assessment of stromal SCD-induced drug resistance of PDAC using 3D-printed zPDX model chips

Lipid metabolism is extensively reprogrammed in pancreatic ductal adenocarcinoma (PDAC). Stearoyl-coenzyme A desaturase (SCD) is a critical lipid regulator that was unexplored in PDAC. Here, we characterized the existence of cancer-associated fibroblasts (CAFs) with high SCD expression, and revealed them as an unfavorable prognostic factor. Therefore, primary CAFs and pancreatic cancer cells were harvested and genetically labeled. The mixture of CAFs and cancer cells were co-injected into scd^-/-; prkdc^-/-, or hIGF1/INS-expressing zebrafish to generate patient-derived xenograft models (zPDX). The models were aligned in 3D-printed chips for semi-automatic drug administration and high-throughput scanning. The results showed that chaperoning of the SCD-high CAFs significantly improved the drug resistance of pancreatic cancer cells against gemcitabine and cisplatin, while the administration of SCD inhibitors neutralized the protective effect. Our studies revealed the prognostic and therapeutic value of stromal SCD in PDAC, and proposed the application of zPDX model chips for drug testing.

Upregulation of SCD1 by ErbB2 via LDHA promotes breast cancer cell migration and invasion

The incidence of breast cancer ranks at the top of female malignant tumors in China. Metastasis remains the main cause of death among breast cancer patients. The overexpression of ErbB2 is closely related to the metastasis and poor prognosis of breast cancer patients. Therefore, ErbB2 is an important clinical therapeutic target of breast cancer. However, the molecular mechanism of ErbB2 promoting breast cancer metastasis has not been studied clearly. Stearoyl-CoA desaturase 1 (SCD1) is a key enzyme in catalyzing the conversion of saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs). SCD1 is overexpressed in breast cancer, and its overexpression is an indicator of poor prognosis in breast cancer patients. However, the role of SCD1 in ErbB2-overexpressing breast cancer metastasis has not been reported. In this study, we investigated the role of SCD1 in the migration and invasion of ErbB2-overexpressing breast cancer cells and its molecular mechanism. First, we demonstrated that ErbB2 upregulates the expression of SCD1. Second, we found that SCD1 and its catalytic product oleic acid played crucial roles in migration and invasion of ErbB2-overexpressing breast cancer cells. Finally, we found that in breast cancer cells, ErbB2 upregulated SCD1 through lactate dehydrogenase A (LDHA). To sum up, upregulation of SCD1 by ErbB2 via LDHA promotes the migration and invasion of breast cancer cells.

The altered lipidome of hepatocellular carcinoma

Alterations in metabolic pathways are a hallmark of cancer. A deeper understanding of the contribution of different metabolites to carcinogenesis is thus vitally important to elucidate mechanisms of tumor initiation and progression to inform therapeutic strategies. Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide and its altered metabolic landscape is beginning to unfold with the advancement of technologies. In particular, characterization of the lipidome of human HCCs has accelerated, and together with biochemical analyses, are revealing recurrent patterns of alterations in glycerophospholipid, sphingolipid, cholesterol and bile acid metabolism. These widespread alterations encompass a myriad of lipid species with numerous roles affecting multiple hallmarks of cancer, including aberrant growth signaling, metastasis, evasion of cell death and immunosuppression. In this review, we summarize the current trends and findings of the altered lipidomic landscape of HCC and discuss their potential biological significance for hepatocarcinogenesis.

Synergistic antitumor activity of sorafenib and MG149 in hepatocellular carcinoma cells

Advanced hepatocellular carcinoma (HCC) is among the most challenging cancers to overcome, and there is a need for better therapeutic strategies. Among the different cancer drugs that have been used in clinics, sorafenib is considered the standard first-line drug for advanced HCC. Here, to identify a chemical compound displaying a synergistic effect with sorafenib in HCC, we screened a focused chemical library and found that MG149, a histone acetyltransferase inhibitor targeting the MYST family, exhibited the most synergistic anticancer effect with sorafenib on HCC cells. The combination of sorafenib and MG149 exerted a synergistic anti-proliferation effect on HCC cells by inducing apoptotic cell death. We revealed that cotreatment with sorafenib and MG149 aggravated endoplasmic reticulum (ER) stress to promote the death of HCC cells rather than adaptive cell survival. In addition, combined treatment with sorafenib and MG149 significantly increased the intracellular levels of unfolded proteins and reactive oxygen species, which upregulated ER stress. Collectively, these results suggest that MG149 has the potential to improve the efficacy of sorafenib in advanced HCC via the upregulation of cytotoxic ER stress. [BMB Reports 2022; 55(10): 506-511].

Lipids in cancer: a global view of the contribution of lipid pathways to metastatic formation and treatment resistance

Lipids are essential constituents for malignant tumors, as they are absolutely required for tumor growth and dissemination. Provided by the tumor microenvironment (TME) or by cancer cells themselves through activation of de novo synthesis pathways, they orchestrate a large variety of pro-tumorigenic functions. Importantly, TME cells, especially immune cells, cancer-associated fibroblasts (CAFs) and cancer-associated adipocytes (CAAs), are also prone to changes in their lipid content, which hinder or promote tumor aggressiveness. In this review, we address the significant findings for lipid contribution in tumor progression towards a metastatic disease and in the poor response to therapeutic treatments. We also highlight the benefits of targeting lipid pathways in preclinical models to slow down metastasis development and overcome chemo-and immunotherapy resistance.

Metabolic targeting of malignant tumors: a need for systemic approach

PURPOSE

Dysregulated metabolism is now recognized as a fundamental hallmark of carcinogenesis inducing aggressive features and additional hallmarks. In this review, well-established metabolic changes displayed by tumors are highlighted in a comprehensive manner and corresponding therapeutical targets are discussed to set up a framework for integrating basic research findings with clinical translation in oncology setting.

METHODS

Recent manuscripts of high research impact and relevant to the field from PubMed (2000-2021) have been reviewed for this article.

RESULTS

Metabolic pathway disruption during tumor evolution is a dynamic process potentiating cell survival, dormancy, proliferation and invasion even under dismal conditions. Apart from cancer cells, though, tumor microenvironment has an acting role as extracellular metabolites, pH alterations and stromal cells reciprocally interact with malignant cells, ultimately dictating tumor-promoting responses, disabling anti-tumor immunity and promoting resistance to treatments.

CONCLUSION

In the field of cancer metabolism, there are several emerging prognostic and therapeutic targets either in the form of gene expression, enzyme activity or metabolites which could be exploited for clinical purposes; both standard-of-care and novel treatments may be evaluated in the context of metabolism rewiring and indeed, synergistic effects between metabolism-targeting and other therapies would be an attractive perspective for further research.

Stearoyl-CoA desaturase 1 as a therapeutic target for cancer: a focus on hepatocellular carcinoma

One of the main characteristics of cancer cells is the alteration in lipid composition, which is associated with a significant monounsaturated fatty acids (MUFAs) enrichment. In addition to their structural functions in newly synthesized membranes in proliferating cancer cells, these fatty acids are involved in tumorigenic signaling. Increased expression and activity of stearoyl CoA desaturase (SCD1), i.e., an enzyme converting saturated fatty acids to Δ9-monounsaturated fatty acids, has been observed in various cancer cells. This increase in expression and activity has also been associated with cancer aggressiveness and poor patient outcome. Previous studies have also indicated the SCD1 involvement in increased cancer cells proliferation, growth, migration, epithelial to mesenchymal transition, metastasis, chemoresistance, and maintenance of cancer stem cells properties. Hence, SCD1 seems to be a player in malignancy development and may be considered a novel therapeutic target in cancers, including hepatocellular carcinoma (HCC). This review study aims to discuss the impact of SCD1 as a major component in lipid signaling in HCC.

Stemness Analysis Uncovers That The Peroxisome Proliferator-Activated Receptor Signaling Pathway Can Mediate Fatty Acid Homeostasis In Sorafenib-Resistant Hepatocellular Carcinoma Cells

Hepatocellular carcinoma (HCC) stem cells are regarded as an important part of individualized HCC treatment and sorafenib resistance. However, there is lacking systematic assessment of stem-like indices and associations with a response of sorafenib in HCC. Our study thus aimed to evaluate the status of tumor dedifferentiation for HCC and further identify the regulatory mechanisms under the condition of resistance to sorafenib. Datasets of HCC, including messenger RNAs (mRNAs) expression, somatic mutation, and clinical information were collected. The mRNA expression-based stemness index (mRNAsi), which can represent degrees of dedifferentiation of HCC samples, was calculated to predict drug response of sorafenib therapy and prognosis. Next, unsupervised cluster analysis was conducted to distinguish mRNAsi-based subgroups, and gene/geneset functional enrichment analysis was employed to identify key sorafenib resistance-related pathways. In addition, we analyzed and confirmed the regulation of key genes discovered in this study by combining other omics data. Finally, Luciferase reporter assays were performed to validate their regulation. Our study demonstrated that the stemness index obtained from transcriptomic is a promising biomarker to predict the response of sorafenib therapy and the prognosis in HCC. We revealed the peroxisome proliferator-activated receptor signaling pathway (the PPAR signaling pathway), related to fatty acid biosynthesis, that was a potential sorafenib resistance pathway that had not been reported before. By analyzing the core regulatory genes of the PPAR signaling pathway, we identified four candidate target genes, retinoid X receptor beta (RXRB), nuclear receptor subfamily 1 group H member 3 (NR1H3), cytochrome P450 family 8 subfamily B member 1 (CYP8B1) and stearoyl-CoA desaturase (SCD), as a signature to distinguish the response of sorafenib. We proposed and validated that the RXRB and NR1H3 could directly regulate NR1H3 and SCD, respectively. Our results suggest that the combined use of SCD inhibitors and sorafenib may be a promising therapeutic approach.

Emerging roles of fatty acid metabolism in cancer and their targeted drug development

Metabolic reprogramming is now considered as one of hallmark of tumor cells and provides them with a selective survival/growth advantage to resist harsh micro-environmental stress. Fatty acid (FA) metabolism of tumor cells supports the biosynthetic needs and provides fuel sources for energy supply. Since FA metabolic reprogramming is a critical link in tumor metabolism, its various roles in tumors have attracted increasing interest. Herein, we review the mechanisms through which cancer cells rewire their FA metabolism with a focus on the pathway of FA metabolism and its targeting drug development. The failure and successful cases of targeting tumor FA metabolism are expected to bypass the metabolic vulnerability and improve the efficacy of targeted therapy.

Mechanisms of resistance to tyrosine kinase inhibitors in liver cancer stem cells and potential therapeutic approaches

The administration of tyrosine kinase inhibitors (TKIs) for the treatment of advanced-stage patients is common in hepatocellular carcinoma (HCC). However, therapy resistance is often encountered, and its emergence eventually curtails long-term clinical benefits. Cancer stem cells (CSCs) are essential drivers of tumor recurrence and therapy resistance; thus, the elucidation of key hallmarks of resistance mechanisms of liver CSC-driven HCC may help improve patient outcomes and reduce relapse. The present review provides a comprehensive summary of the intrinsic and extrinsic mechanisms of TKI resistance in liver CSCs, which mediate treatment failure, and discusses potential strategies to overcome TKI resistance from a preclinical perspective.

Metabolic Adaptation-Mediated Cancer Survival and Progression in Oxidative Stress

Undue elevation of ROS levels commonly occurs during cancer evolution as a result of various antitumor therapeutics and/or endogenous immune response. Overwhelming ROS levels induced cancer cell death through the dysregulation of ROS-sensitive glycolytic enzymes, leading to the catastrophic depression of glycolysis and oxidative phosphorylation (OXPHOS), which are critical for cancer survival and progression. However, cancer cells also adapt to such catastrophic oxidative and metabolic stresses by metabolic reprograming, resulting in cancer residuality, progression, and relapse. This adaptation is highly dependent on NADPH and GSH syntheses for ROS scavenging and the upregulation of lipolysis and glutaminolysis, which fuel tricarboxylic acid cycle-coupled OXPHOS and biosynthesis. The underlying mechanism remains poorly understood, thus presenting a promising field with opportunities to manipulate metabolic adaptations for cancer prevention and therapy. In this review, we provide a summary of the mechanisms of metabolic regulation in the adaptation of cancer cells to oxidative stress and the current understanding of its regulatory role in cancer survival and progression.

New insights into antiangiogenic therapy resistance in cancer: Mechanisms and therapeutic aspects

Angiogenesis is a hallmark of cancer and is required for tumor growth and progression. Antiangiogenic therapy has been revolutionarily developing and was approved for the treatment of various types of cancer for nearly two decades, among which bevacizumab and sorafenib continue to be the two most frequently used antiangiogenic drugs. Although antiangiogenic therapy has brought substantial survival benefits to many cancer patients, resistance to antiangiogenic drugs frequently occurs during clinical treatment, leading to poor outcomes and treatment failure. Cumulative evidence has demonstrated that the intricate interplay among tumor cells, bone marrow-derived cells, and local stromal cells critically allows for tumor escape from antiangiogenic therapy. Currently, drug resistance has become the main challenge that hinders the therapeutic efficacies of antiangiogenic therapy. In this review, we describe and summarize the cellular and molecular mechanisms conferring tumor drug resistance to antiangiogenic therapy, which was predominantly associated with redundancy in angiogenic signaling molecules (e.g., VEGFs, GM-CSF, G-CSF, and IL17), alterations in biological processes of tumor cells (e.g., tumor invasiveness and metastasis, stemness, autophagy, metabolic reprogramming, vessel co-option, and vasculogenic mimicry), increased recruitment of bone marrow-derived cells (e.g., myeloid-derived suppressive cells, tumor-associated macrophages, and tumor-associated neutrophils), and changes in the biological functions and features of local stromal cells (e.g., pericytes, cancer-associated fibroblasts, and endothelial cells). We also review potential biomarkers to predict the response to antiangiogenic therapy in cancer patients, which mainly consist of imaging biomarkers, cellular and extracellular proteins, a certain type of bone marrow-derived cells, local stromal cell content (e.g., pericyte coverage) as well as serum or plasma biomarkers (e.g., non-coding RNAs). Finally, we highlight the recent advances in combination strategies with the aim of enhancing the response to antiangiogenic therapy in cancer patients and mouse models. This review introduces a comprehensive understanding of the mechanisms and biomarkers associated with the evasion of antiangiogenic therapy in cancer, providing an outlook for developing more effective approaches to promote the therapeutic efficacy of antiangiogenic therapy.

PI(18:1/18:1) is a SCD1-derived lipokine that limits stress signaling

Cytotoxic stress activates stress-activated kinases, initiates adaptive mechanisms, including the unfolded protein response (UPR) and autophagy, and induces programmed cell death. Fatty acid unsaturation, controlled by stearoyl-CoA desaturase (SCD)1, prevents cytotoxic stress but the mechanisms are diffuse. Here, we show that 1,2-dioleoyl-sn-glycero-3-phospho-(1’-myo-inositol) [PI(18:1/18:1)] is a SCD1-derived signaling lipid, which inhibits p38 mitogen-activated protein kinase activation, counteracts UPR, endoplasmic reticulum-associated protein degradation, and apoptosis, regulates autophagy, and maintains cell morphology and proliferation. SCD1 expression and the cellular PI(18:1/18:1) proportion decrease during the onset of cell death, thereby repressing protein phosphatase 2 A and enhancing stress signaling. This counter-regulation applies to mechanistically diverse death-inducing conditions and is found in multiple human and mouse cell lines and tissues of Scd1-defective mice. PI(18:1/18:1) ratios reflect stress tolerance in tumorigenesis, chemoresistance, infection, high-fat diet, and immune aging. Together, PI(18:1/18:1) is a lipokine that links fatty acid unsaturation with stress responses, and its depletion evokes stress signaling.

Fatty acid unsaturation by stearoyl-CoA desaturase 1 (SCD1) protects against cellular stress through unclear mechanisms. Here the authors show 1,2-dioleoyl-sn-glycero-3-phospho-(1’-myo-inositol) is an SCD1-derived signaling lipid that regulates stress-adaption, protects against cell death and promotes proliferation.

UDP-glucose 6-dehydrogenase lessens sorafenib sensitivity via modulating unfolded protein response

As the first-generation targeted therapy, sorafenib remains an effective single-drug treatment for advanced hepatocellular carcinoma (HCC). Unfortunately, the existence of resistance restricts the long-term benefit of patients. UDP-glucose 6-dehydrogenase (UGDH) is the key enzyme of glucuronic acid metabolism which was largely reported in mediating drug systemic elimination. In this study, we explore its critical role in regulating sorafenib sensitivity. Here we find sorafenib exposure could activate glucuronic acid metabolism, accompanied with the elevated expression of UGDH. Interference with the route by silencing UGDH could boost HCC cells sensitivity to sorafenib. Meanwhile, the analysis of HCC patients with sorafenib treatment displayed that low UGDH expression predicted superior prognosis. Further screening assay suggested that unfolded protein response (UPR) involves in UGDH silencing-mediated apoptosis. Xenograft model confirmed that combined UGDH intervention could significantly improve sorafenib efficacy. Our results reveal the impact of sorafenib exposure on glucuronic acid metabolism reprogramming and provide UGDH as a promising target to improve sorafenib efficacy.

Novel Insights on Lipid Metabolism Alterations in Drug Resistance in Cancer

Chemotherapy is one of the primary treatments for most human cancers. Despite great progress in cancer therapeutics, chemotherapy continues to be important for improving the survival of cancer patients, especially for those who has unresectable metastatic tumors or fail to respond to immunotherapy. However, intrinsic or acquired chemoresistance results in tumor recurrence, which remains a major obstacle in anti-cancer treatment. The high prevalence of chemoresistant cancer makes it urgent to deepen our understanding on chemoresistance mechanisms and to develop novel therapeutic strategies. Multiple mechanisms, including drug efflux, enhanced DNA damage reparability, increased detoxifying enzymes levels, presence of cancer stem cells (CSCs), epithelial mesenchymal transition (EMT), autophagy, ferroptosis and resistance to apoptosis, underlie the development of chemoresistance. Recently, accumulating evidence suggests that lipid metabolism alteration is closely related to drug resistance in tumor. Targeting lipid metabolism in combination with traditional chemotherapeutic drugs is a promising strategy to overcome drug resistance. Therefore, this review compiles the current knowledge about aberrant lipid metabolism in chemoresistant cancer, mainly focusing on aberrant fatty acid metabolism, and presents novel therapeutic strategies targeting altered lipid metabolism to overcome chemoresistance in cancer.

Cholesterol sensor SCAP contributes to sorafenib resistance by regulating autophagy in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most malignant tumors and the fourth leading cause of cancer-related death worldwide. Sorafenib is currently acknowledged as a standard therapy for advanced HCC. However, acquired resistance substantially limits the clinical efficacy of sorafenib. Therefore, further investigations of the associated risk factors are highly warranted.

Methods

We analysed a group of 78 HCC patients who received sorafenib treatment after liver resection surgery. The expression of SCAP and its correlation with sorafenib resistance in HCC clinical samples were determined by immunohistochemical analyses. Overexpression and knockdown approaches in vitro were used to characterize the functional roles of SCAP in regulating sorafenib resistance. The effects of SCAP inhibition in HCC cell lines were analysed in proliferation, apoptosis, and colony formation assays. Autophagic regulation by SCAP was assessed by immunoblotting, immunofluorescence and immunoprecipitation assays. The combinatorial effect of a SCAP inhibitor and sorafenib was tested using nude mice.

Results

Hypercholesterolemia was associated with sorafenib resistance in HCC treatment. The degree of sorafenib resistance was correlated with the expression of the cholesterol sensor SCAP and consequent deposition of cholesterol. SCAP is overexpressed in HCC tissues and hepatocellular carcinoma cell lines with sorafenib resistance, while SCAP inhibition could improve sorafenib sensitivity in sorafenib-resistant HCC cells. Furthermore, we found that SCAP-mediated sorafenib resistance was related to decreased autophagy, which was connected to decreased AMPK activity. A clinically significant finding was that lycorine, a specific SCAP inhibitor, could reverse acquired resistance to sorafenib in vitro and in vivo.

Conclusions

SCAP contributes to sorafenib resistance through AMPK-mediated autophagic regulation. The combination of sorafenib and SCAP targeted therapy provides a novel personalized treatment to enhance sensitivity in sorafenib-resistant HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02306-4.

Comparative Proteomics Analysis Reveals the Reversal Effect of Cryptotanshinone on Gefitinib-Resistant Cells in Epidermal Growth Factor Receptor-Mutant Lung Cancer

Cryptotanshinone (CTS) is a lipophilic constituent of Salvia miltiorrhiza, with a broad-spectrum anticancer activity. We have observed that CTS enhances the efficacy of gefitinib in human lung cancer H1975 cells, yet little is known about its molecular mechanism. To explore how CTS enhances H1975 cell sensitivity to gefitinib, we figured out differential proteins of H1975 cells treated by gefitinib alone or in combination with CTS using label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein–protein interaction (PPI) bioinformatic analyses of the differential proteins were performed. CTS enhanced H1975 cell sensitivity to gefitinib in vitro and in vivo, with 115 and 128 differential proteins identified, respectively. GO enrichment, KEGG analysis, and PPI network comprehensively demonstrated that CTS mainly impacted the redox process and fatty acid metabolism in H1975 cells. Moreover, three differential proteins, namely, catalase (CAT), heme oxygenase 1 (HMOX1), and stearoyl-CoA desaturase (SCD) were validated by RT-qPCR and Western blot. In conclusion, we used a proteomic method to study the mechanism of CTS enhancing gefitinib sensitivity in H1975 cells. Our finding reveals the potential protein targets of CTS in overcoming gefitinib resistance, which may be therapeutical targets in lung cancer.