High cholesterol in lipid rafts reduces the sensitivity to EGFR-TKI therapy in non-small cell lung cancer

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.

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

Lenvatinib has become the first-line therapy in advanced hepatocellular carcinoma (HCC), but its efficacy is still limited because of the inevitable development of resistance. It has been reported that cellular cholesterol levels are associated with tyrosine kinase inhibitor (TKI) efficacy. Here, we show that betulin, a sterol regulatory element-binding protein 2 (SREBP2) inhibitor, markedly enhances the anti-tumor effect of lenvatinib in HCC both in vitro and in vivo. Our results also show that the combination treatment of lenvatinib and betulin synergistically inhibits the proliferation and clonogenicity of HCC cells. The mRNA and protein expressions of IL-1β are markedly decreased in HCC cells treated with betulin, while the sensitivity of HCC cells to lenvatinib is enhanced. Moreover, we find that the knockdown of IL-1β also enhances the efficacy of lenvatinib, and recombinant IL-1β protein rescues cell viability, which is reduced by lenvatinib in HCC cells. Further mechanistic studies indicate that betulin decreases the level of IL-1β in HCC cells by inhibiting the mTOR signaling pathway. Finally, the growth of the tumors in xenograft mouse models subjected to combination treatment is significantly suppressed. In summary, our study reveals that the SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1β pathway, which may be a promising therapeutic strategy for patients with HCC.

The emerging role of PPAR-alpha in breast cancer

Breast cancer has been confirmed to have lipid disorders in the tumour microenvironment. Peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcriptional factor that belongs to the family of nuclear receptors. PPARα regulates the expression of genes involved in fatty acid homeostasis and is a major regulator of lipid metabolism. Because of its effects on lipid metabolism, an increasing number of studies have investigated the relationship of PPARα with breast cancer. PPARα has been shown to impact the cell cycle and apoptosis in normal cells and tumoral cells through regulating genes of the lipogenic pathway, fatty acid oxidation, fatty acid activation, and uptake of exogenous fatty acids. Besides, PPARα is involved in the regulation of the tumour microenvironment (anti-inflammation and inhibition of angiogenesis) by modulating different signal pathways such as NF-κB and PI3K/AKT/mTOR. Some synthetic PPARα ligands are used in adjuvant therapy for breast cancer. PPARα agonists are reported to reduce the side effects of chemotherapy and endocrine therapy. In addition, PPARα agonists enhance the curative effects of targeted therapy and radiation therapy. Interestingly, with the emerging role of immunotherapy, attention has been focused on the tumour microenvironment. The dual functions of PPARα agonists in immunotherapy need further research. This review aims to consolidate the operations of PPARα in lipid-related and other ways, as well as discuss the current and potential applications of PPARα agonists in tackling breast cancer.

Modulation of self-organizing circuits at deforming membranes by intracellular and extracellular factors

Mechanical forces exerted to the plasma membrane induce cell shape changes. These transient shape changes trigger, among others, enrichment of curvature-sensitive molecules at deforming membrane sites. Strikingly, some curvature-sensing molecules not only detect membrane deformation but can also alter the amplitude of forces that caused to shape changes in the first place. This dual ability of sensing and inducing membrane deformation leads to the formation of curvature-dependent self-organizing signaling circuits. How these cell-autonomous circuits are affected by auxiliary parameters from inside and outside of the cell has remained largely elusive. Here, we explore how such factors modulate self-organization at the micro-scale and its emerging properties at the macroscale.

A Novel Mechanism Underlying the Inhibitory Effects of Trastuzumab on the Growth of HER2-Positive Breast Cancer Cells

To improve the efficacy of trastuzumab, it is essential to understand its mechanism of action. One of the significant issues that makes it difficult to determine the precise mechanism of trastuzumab action is the formation of various HER receptor dimers in HER2-positive breast cancer cells. So far, studies have focused on the role of HER2-HER3 heterodimers, and little is known regarding EGFR-HER2 heterodimers. Here, we study the role of trastuzumab on the cell signaling and cell proliferation mediated by EGFR-HER2 heterodimers in BT474 and SRBR3 cells. EGF stimulates the formation of both EGFR homodimer and EGFR-HER2 heterodimer. Trastuzumab only binds to HER2, not EGFR. Therefore, any effects of trastuzumab on EGF-induced activation of EGFR, HER2, and downstream signaling proteins, as well as cell proliferation, are through its effects on EGFR-HER2 heterodimers. We show that trastuzumab inhibits EGF-induced cell proliferation and cell cycle progression in BT474 and SKBR3 cells. Interestingly trastuzumab strongly inhibits EGF-induced Akt phosphorylation and slightly inhibits EGF-induced Erk activation, in both BT474 and SKBR3 cells. These data suggest the presence of a novel mechanism that allows trastuzumab to inhibit EGR-induced Akt activation and cell proliferation, without blocking EGF-induced EGFR-HER2 heterodimerization and activation. We show that trastuzumab inhibits EGF-induced lipid raft localization of the EGFR-HER2 heterodimer. Disruption of the lipid raft with MβCD blocks HER2-mediated AKT activation in a similar way to trastuzumab. MβCD and trastuzumab synergically inhibit AKT activation. We conclude that trastuzumab inhibits EGF-induced lipid raft localization of EGFR-HER2 heterodimer, which leads to the inhibition of Akt phosphorylation and cell proliferation, without blocking the formation and phosphorylation of the EGFR-HER2 heterodimer.

Anoctamins and Calcium Signalling: An Obstacle to EGFR Targeted Therapy in Glioblastoma?

Glioblastoma is the most common form of high-grade glioma in adults and has a poor survival rate with very limited treatment options. There have been no significant advancements in glioblastoma treatment in over 30 years. Epidermal growth factor receptor is upregulated in most glioblastoma tumours and, therefore, has been a drug target in recent targeted therapy clinical trials. However, while many inhibitors and antibodies for epidermal growth factor receptor have demonstrated promising anti-tumour effects in preclinical models, they have failed to improve outcomes for glioblastoma patients in clinical trials. This is likely due to the highly plastic nature of glioblastoma tumours, which results in therapeutic resistance. Ion channels are instrumental in the development of many cancers and may regulate cellular plasticity in glioblastoma. This review will explore the potential involvement of a class of calcium-activated chloride channels called anoctamins in brain cancer. We will also discuss the integrated role of calcium channels and anoctamins in regulating calcium-mediated signalling pathways, such as epidermal growth factor signalling, to promote brain cancer cell growth and migration.

Cholesterol: An important actor on the cancer immune scene

Based on the structural and signaling roles of cholesterol, which are necessary for immune cell activity, high concentrations of cholesterol and its metabolites not only trigger malignant cell activities but also impede immune responses against cancer cells. To proliferate and evade immune responses, tumor cells overcome environmental restrictions by changing their metabolic and signaling pathways. Overexpression of mevalonate pathway enzymes and low-density lipoprotein receptor cause elevated cholesterol synthesis and uptake, respectively. Accordingly, cholesterol can be considered as both a cause and an effect of cancer. Variations in the effects of blood cholesterol levels on the outcome of different types of cancer may depend on the stage of cancer. However, positive effects of cholesterol-lowering drugs have been reported in the treatment of patients with some malignancies.

Alteration of cholesterol distribution at the plasma membrane of cancer cells: From evidence to pathophysiological implication and promising therapy strategy

Cholesterol-enriched domains are nowadays proposed to contribute to cancer cell proliferation, survival, death and invasion, with important implications in tumor progression. They could therefore represent promising targets for new anticancer treatment. However, although diverse strategies have been developed over the years from directly targeting cholesterol membrane content/distribution to adjusting sterol intake, all approaches present more or less substantial limitations. Those data emphasize the need to optimize current strategies, to develop new specific cholesterol-targeting anticancer drugs and/or to combine them with additional strategies targeting other lipids than cholesterol. Those objectives can only be achieved if we first decipher (i) the mechanisms that govern the formation and deformation of the different types of cholesterol-enriched domains and their interplay in healthy cells; (ii) the mechanisms behind domain deregulation in cancer; (iii) the potential generalization of observations in different types of cancer; and (iv) the specificity of some alterations in cancer vs. non-cancer cells as promising strategy for anticancer therapy. In this review, we will discuss the current knowledge on the homeostasis, roles and membrane distribution of cholesterol in non-tumorigenic cells. We will then integrate documented alterations of cholesterol distribution in domains at the surface of cancer cells and the mechanisms behind their contribution in cancer processes. We shall finally provide an overview on the potential strategies developed to target those cholesterol-enriched domains in cancer therapy.

Efficacy and safety of EGFR‑TKIs plus Shenqi Fuzheng injection for non-small cell lung cancer patients with EGFR-sensitive mutations

PURPOSE

The aim of this retrospective study is to evaluate the impact on efficacy and safety between epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) alone and in combination with Shenqi Fuzheng injection (SFI) in patients with advanced NSCLC harboring epidermal growth factor receptor (EGFR) activating mutations.

METHODS

Retrospectively, information of 88 patients receiving EGFR-TKIs as first-line targeted treatment or in combination with SFI in the Affiliated Drum Tower Hospital of Nanjing University Medical College and the Affiliated Cancer Hospital of Anhui University of Science and Technology was collected. The primary endpoint was to assess progression-free survival (PFS) and safety of EGFR-TKIs alone or in combination with SFI.

RESULTS

Between January 2016 and December 2019, a total of 88 patients were enrolled in this research, including 50 cases in the EGFR-TKIs single agent therapy group and 38 cases in the SFI combined with EGFR-TKIs targeted-therapy group. The median PFS (mPFS) of monotherapy group was 10.50 months (95%CI 9.81-11.19), and 14.30 months (95%CI 10.22-18.38) in the combination therapy group. Compared to the single EGFR-TKIs administration, combinational regimen with SFI exhibited a lower incidence of rash and diarrhea in patients and was even better tolerated.

CONCLUSIONS

SFI combined with the first-generation EGFR-TKIs are more efficient, can prominently prolong the PFS and attenuate the adverse reactions in patients with advanced NSCLC with EGFR-sensitive mutations.

Dysregulated Metabolism in EGFR-TKI Drug Resistant Non-Small-Cell Lung Cancer: A Systematic Review

Drug resistance is a common barrier to continued effective treatment in cancer. In non-small-cell lung cancer (NSCLC), tyrosine kinase inhibitors that target the epidermal growth factor receptor (EGFR-TKIs) exhibit good efficacy in cancer treatment until acquired resistance occurs. It has been observed that drug resistance is accompanied by numerous molecular-level changes, including significant shifts in cellular metabolism. The purpose of this study was to critically and systematically review the published literature with respect to how metabolism differs in drug-resistant compared to drug-sensitive NSCLC. Understanding the differences between resistant and sensitive cells is vital and has the potential to allow interventions that enable the re-sensitisation of resistant cells to treatment, and consequently reinitiate the therapeutic effect of EGFR-TKIs. The main literature search was performed using relevant keywords in PubMed and Ovid (Medline) and reviewed using the Covidence platform. Of the 1331 potentially relevant literature records retrieved, 27 studies were subsequently selected for comprehensive analysis. Collectively, the literature revealed that NSCLC cell lines resistant to EGFR-TKI treatment possess characteristic metabolic and lipidomic phenotypic signatures that differentiate them from sensitive lines. Further exploration of these reported differences suggests that drug-resistant cell lines are differentially reliant on cellular energy sources and that modulation of relative energy production pathways may lead to the reversal of drug resistance.

Cholesterol suppresses GOLM1-dependent selective autophagy of RTKs in hepatocellular carcinoma

Aberrant activation of receptor tyrosine kinases (RTKs) and the subsequent metabolic reprogramming play critical roles in cancer progression. Our previous study has shown that Golgi membrane protein 1 (GOLM1) promotes hepatocellular carcinoma (HCC) metastasis by enhancing the recycling of RTKs. However, how this RTK recycling process is regulated and coupled with RTK degradation remains poorly defined. Here, we demonstrate that cholesterol suppresses the autophagic degradation of RTKs in a GOLM1-dependent manner. Further mechanistic studies reveal that GOLM1 mediates the selective autophagy of RTKs by interacting with LC3 through an LC3-interacting region (LIR), which is regulated by a cholesterol-mTORC1 axis. Lowering cholesterol by statins improves the efficacy of multiple tyrosine kinase inhibitors (TKIs) in vivo. Our findings indicate that cholesterol serves as a signal to switch GOLM1-RTK degradation to GOLM1-RTK recycling and suggest that lowering cholesterol by statin may be a promising combination strategy to improve the TKI efficiency in HCC.

Claudin1 decrease induced by 1,25-dihydroxy-vitamin D3 potentiates gefitinib resistance therapy through inhibiting AKT activation-mediated cancer stem-like properties in NSCLC cells

Claudins, the integral tight junction proteins that regulate paracellular permeability and cell polarity, are frequently dysregulated in cancer; however, their roles in regulating EGFR tyrosine kinase inhibitors (EGFR-TKIs) resistance in non-small cell lung cancer (NSCLC) are unknown. To this end, we performed GEO dataset analysis and identified that claudin1 was a critical regulator of EGFR-TKI resistance in NSCLC cells. We also found that claudin1, which was highly induced by continuous gefitinib treatment, was significantly upregulated in EGFR-TKI-resistant NSCLC cells. By knocking down claudin1 in cell lines and xenograft models, we established that gefitinib resistance was decreased. Moreover, claudin1 knockdown suppressed the expression levels of pluripotency markers (Oct4, Nanog, Sox2, CD133, and ALDH1A1). Claudin1 loss inhibited phosphorylated AKT (p-AKT) expression and reduced cancer cell stemness by suppressing AKT activation. Furthermore, SKL2001, a β-catenin agonist, upregulated the expression levels of claudin1, p-AKT, and pluripotency markers, and 1,25-dihydroxy-vitamin D3 (1,25(OH)₂D₃) reduced claudin1 expression, AKT activation, and cancer cell stemness by inhibiting β-catenin, and suppressed claudin1/AKT pathway mediated cancer stem-like properties and gefitinib resistance. Collectively, inhibition of claudin1-mediated cancer stem-like properties by 1,25(OH)₂D₃ may decrease gefitinib resistance through the AKT pathway, which may be a promising therapeutic strategy for inhibiting gefitinib resistance in EGFR-mutant lung adenocarcinoma.

Cholesterol promotes EGFR-TKIs resistance in NSCLC by inducing EGFR/Src/Erk/SP1 signaling-mediated ERRα re-expression

BACKGROUND

The use of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) brings remarkable benefits for the survival of patients with advanced NSCLC harboring EGFR mutations. Unfortunately, acquired resistance seems to be inevitable and limits the application of EGFR-TKIs in clinical practice. This study reported a common molecular mechanism sustaining resistance and potential treatment options to overcome EGFR-TKIs resistance.

METHODS

EGFR-TKIs resistant NSCLC cells were established and confirmed by MTT assay. Cholesterol content was detected and the promotional function of cholesterol on NSCLC growth was determined in vivo. Then, we identified ERRα expression as the downstream factor of cholesterol-mediated drug resistance. To dissect the regulatory mechanism, we conducted experiments, including immunofluorescence, co-immunoprecipitation, luciferase reporter assay and chromatin immunoprecipitation assay.

RESULTS

Long-term exposure to EGFR-TKIs generate drug resistance with the characteristic of cholesterol accumulation in lipid rafts, which promotes EGFR and Src to interact and lead EGFR/Src/Erk signaling reactivation-mediated SP1 nuclear translocation and ERRα re-expression. Further investigation identifies ERRα as a target gene of SP1. Functionally, re-expression of ERRα sustains cell proliferation by regulating ROS detoxification process. Lovastatin, a drug used to decrease cholesterol level, and XCT790, an inverse agonist of ERRα, overcome gefitinib and osimertinib resistance both in vitro and in vivo.

CONCLUSIONS

Our study indicates that cholesterol/EGFR/Src/Erk/SP1 axis-induced ERRα re-expression promotes survival of gefitinib and osimertinib-resistant cancer cells. Besides, we demonstrate the potential of lowing cholesterol and downregulation of ERRα as effective adjuvant treatment of NSCLC.

Pretreatment HDL-C and ApoA1 are predictive biomarkers of progression-free survival in patients with EGFR mutated advanced non-small cell lung cancer treated with TKI

BACKGROUND

We aimed to explore the correlation between blood lipids (high density lipoprotein cholesterol [HDL-C] and apolipoprotein A1 [ApoA1]) and epidermal growth factor receptor (EGFR) T790M mutation, as well as its predictive role in clinical efficacy and progression-free survial (PFS) in advanced non-small cell lung cancer (NSCLC) patients treated with EGFR tyrosine kinase inhibitors (EGFR-TKI).

METHODS

We retrospectively collected information of 153 patients with advanced NSCLC harboring exon EGFR mutation and receiving EGFR-TKI.

RESULTS

The best cutoff value for HDL-C and ApoA1 was determined to be 1.15 and 1.14 mmol/l. The overall response rate (ORR) was 67.7% in the high HDL-C group and 46.6% in the low HDL-C group, respectively. The ORR of the high ApoA1 group showed a significant increase than that of the low ApoA1 group (68.1% vs. 38.5%). The mean ApoA1 level of the EGFR T790M mutation-positive group was significantly higher than that of the EGFR T790M mutation-negative group (1.13 g/l vs. 1.01 g/l). Patients with high ApoA1 levels were related to the EGFR T790M mutation (r = 0.324). (3) The median progression-free survival (PFS) of the high HDL-C group and low HDL-C group were 13.00 months and 10.20 months. The median PFS of the high ApoA1 group and the low ApoA1 group were 12.10 and 10.00 months, respectively. Multivariate Cox stepwise regression model analysis demonstrated ECOG PS, pathological type and HDL-C were confirmed as critical and independent predictors of PFS.

CONCLUSIONS

Patients with EGFR T790M mutations often show higher ApoA1 levels. Peripheral serum HDL-C and ApoA1 before treatment can be used as potential significant factors for predicting clinical efficacy and PFS in advanced NSCLC patients treated with EGFR-TKI.

Development of a novel spatiotemporal depletion system for cellular cholesterol

Cholesterol is an essential component of mammalian cell membranes whose subcellular concentration and function are tightly regulated by de novo biosynthesis, transport, and storage. Although recent reports have suggested diverse functions of cellular cholesterol in different subcellular membranes, systematic investigation of its site-specific roles has been hampered by the lack of a methodology for spatiotemporal manipulation of cellular cholesterol levels. Here, we report the development of a new cholesterol depletion system that allows for spatiotemporal manipulation of intracellular cholesterol levels. This system utilizes a genetically encoded cholesterol oxidase whose intrinsic membrane binding activity is engineered in such a way that its membrane targeting can be controlled in a spatiotemporally specific manner via chemically induced dimerization. In combination with in situ quantitative imaging of cholesterol and signaling activity measurements, this system allows for unambiguous determination of site-specific functions of cholesterol in different membranes, including the plasma membrane and the lysosomal membrane.

A Transcriptomic Approach to Elucidate the Mechanisms of Gefitinib-Induced Toxicity in Healthy Human Intestinal Organoids

Gefitinib is a tyrosine kinase inhibitor (TKI) that selectively inhibits the epidermal growth factor receptor (EGFR), hampering cell growth and proliferation. Due to its action, gefitinib has been used in the treatment of cancers that present abnormally increased expression of EGFR. However, side effects from gefitinib therapy may occur, among which diarrhoea is most common, that can lead to interruption of the planned therapy in the more severe cases. The mechanisms underlying intestinal toxicity induced by gefitinib are not well understood. Therefore, this study aims at providing insight into these mechanisms based on transcriptomic responses induced in vitro. A 3D culture of healthy human colon and small intestine (SI) organoids was exposed to 0.1, 1, 10 and 30 µM of gefitinib, for a maximum of three days. These drug concentrations were selected using physiologically-based pharmacokinetic simulation considering patient dosing regimens. Samples were used for the analysis of viability and caspase 3/7 activation, image-based analysis of structural changes, as well as RNA isolation and sequencing via high-throughput techniques. Differential gene expression analysis showed that gefitinib perturbed signal transduction pathways, apoptosis, cell cycle, FOXO-mediated transcription, p53 signalling pathway, and metabolic pathways. Remarkably, opposite expression patterns of genes associated with metabolism of lipids and cholesterol biosynthesis were observed in colon versus SI organoids in response to gefitinib. These differences in the organoids’ responses could be linked to increased activated protein kinase (AMPK) activity in colon, which can influence the sensitivity of the colon to the drug. Therefore, this study sheds light on how gefitinib induces toxicity in intestinal organoids and provides an avenue towards the development of a potential tool for drug screening and development.

It Takes More than Two to Tango: Complex, Hierarchal, and Membrane-Modulated Interactions in the Regulation of Receptor Tyrosine Kinases

The search for an understanding of how cell fate and motility are regulated is not a purely scientific undertaking, but it can also lead to rationally designed therapies against cancer. The discovery of tyrosine kinases about half a century ago, the subsequent characterization of certain transmembrane receptors harboring tyrosine kinase activity, and their connection to the development of human cancer ushered in a new age with the hope of finding a treatment for malignant diseases in the foreseeable future. However, painstaking efforts were required to uncover the principles of how these receptors with intrinsic tyrosine kinase activity are regulated. Developments in molecular and structural biology and biophysical approaches paved the way towards better understanding of these pathways. Discoveries in the past twenty years first resulted in the formulation of textbook dogmas, such as dimerization-driven receptor association, which were followed by fine-tuning the model. In this review, the role of molecular interactions taking place during the activation of receptor tyrosine kinases, with special attention to the epidermal growth factor receptor family, will be discussed. The fact that these receptors are anchored in the membrane provides ample opportunities for modulatory lipid-protein interactions that will be considered in detail in the second part of the manuscript. Although qualitative and quantitative alterations in lipids in cancer are not sufficient in their own right to drive the malignant transformation, they both contribute to tumor formation and also provide ways to treat cancer. The review will be concluded with a summary of these medical aspects of lipid-protein interactions.

Our evolving understanding of how 27-hydroxycholesterol influences cancer

Cholesterol has been implicated in the pathophysiology and progression of several cancers now, although the mechanisms by which it influences cancer biology are just emerging. Two likely contributing mechanisms are the ability for cholesterol to directly regulate signaling molecules within the membrane, and certain metabolites acting as signaling molecules. One such metabolite is the oxysterol 27-hydroxycholesterol (27HC), which is a primary metabolite of cholesterol synthesized by the enzyme Cytochrome P450 27A1 (CYP27A1). Physiologically, 27HC is involved in the regulation of cholesterol homeostasis and contributes to cholesterol efflux through liver X receptor (LXR) and inhibition of de novo cholesterol synthesis through the insulin-induced proteins (INSIGs). 27HC is also a selective modulator of the estrogen receptors. An increasing number of studies have identified its importance in cancer progression of various origins, especially in breast cancer. In this review, we discuss the physiological roles of 27HC targeting these two nuclear receptors and the subsequent contribution to cancer progression. We describe how 27HC promotes tumor growth directly through cancer-intrinsic factors, and indirectly through its immunomodulatory roles which lead to decreased immune surveillance and increased tumor invasion. This review underscores the importance of the cholesterol metabolic pathway in cancer progression and the potential therapeutic utility of targeting this metabolic pathway.

PPARα agonist fenofibrate relieves acquired resistance to gefitinib in non-small cell lung cancer by promoting apoptosis via PPARα/AMPK/AKT/FoxO1 pathway

Recent studies show that intracellular accumulation of cholesterol leads to acquired resistance to gefitinib in non-small cell lung cancer (NSCLC) cells. In this study we investigated how to regulate the cholesterol levels in gefitinib-resistant NSCLC cells. We showed that intracellular cholesterol levels in gefitinib-resistant cell lines (PC-9/GR, H1975, H1650, and A549) were significantly higher than that in gefitinib-sensitive cell line (PC-9). Treatment with gefitinib (5 μM) significantly increased intracellular cholesterol levels in PC-9/GR, H1975, and H1650 cells. Gefitinib treatment downregulated the expression of PPARα, LXRα, and ABCA1, leading to dysregulation of cholesterol efflux pathway. We found that a lipid-lowering drug fenofibrate (20, 40 μM) dose-dependently increased the expression of PPARα, LXRα, and ABCA1, decreased the intracellular cholesterol levels, and enhanced the antiproliferative effects of gefitinib in PC-9/GR, H1975, and H1650 cells. We revealed that fenofibrate increased the gefitinib-induced apoptosis via regulating the key proteins involved in the intrinsic apoptosis pathway. In PC-9/GR, H1975 and H1650 cells, fenofibrate dose-dependently increased the expression of AMPK, FoxO1, and decreased the expression of AKT, which were remarkably weakened by knockdown of PPARα. In PC-9/GR cell xenograft mice, combined administration of gefitinib (25 mg · kg^-1 · d^-1) and fenofibrate (100 mg · kg^-1 · d^-1) caused remarkable inhibition on tumor growth as compared to treatment with either drug alone. All the results suggest that fenofibrate relieves acquired resistance to gefitinib in NSCLC by promoting apoptosis via regulating PPARα/AMPK/AKT/FoxO1 pathway. We propose that combination of gefitinib and fenofibrate is a potential strategy for overcoming the gefitinib resistance in NSCLC.

DPP4 Regulates DHCR24-Mediated Cholesterol Biosynthesis to Promote Methotrexate Resistance in Gestational Trophoblastic Neoplastic Cells

Metabolic reprogramming could promote cellular adaptation in response to chemotherapeutic drugs in cancer cells. Herein, we aimed to characterize the metabolomic profiles regulated by Dipeptidyl Peptidase 4 (DPP4) in methotrexate (MTX)-resistant gestational trophoblastic neoplastic (GTN) cells. A total of eighty metabolites were found to be commonly altered in DPP4-depleted JAR/MTX and JEG3/MTX cells. Cholesterol biosynthesis-related metabolites were markedly impacted by DPP4 knockdown in MTX-resistant sublines. Manipulation of DPP4 expression remarkably affected the level of cellular cholesterol in GTN cells. Our analysis also identified 24-Dehydrocholesterol Reductase (DHCR24) as a potential downstream effector of DPP4. Manipulation of DHCR24 expression affected cellular cholesterol level, reactive oxygen species (ROS) accumulation, and chemosensitivity to MTX in GTN cell models. In addition, over-expression of DHCR24 could markedly restore cellular cholesterol level and rescue cell survival in DPP4-depleted MTX-resistant GTN cells. Highly correlated expression of DPP4 and DHCR24 was observed in clinical GTN specimens. Further, DPP4 inhibitor sitagliptin effectively inhibited cholesterol biosynthesis, reduced DHCR24 expression and enhanced MTX-induced cytotoxicity in vitro and in vivo. In conclusion, our findings suggested that DPP4 might regulate DHCR24-mediated cholesterol biosynthesis to promote methotrexate resistance in GTN cells. Targeting DPP4/DHCR24 signaling might help to sensitize MTX-resistant GTN to MTX treatment.

Mechanistic Insights Delineating the Role of Cholesterol in Epithelial Mesenchymal Transition and Drug Resistance in Cancer

Despite the significant advancements made in targeted anti-cancer therapy, drug resistance constitutes a multifaceted phenomenon leading to therapy failure and ultimately mortality. Emerging experimental evidence highlight a role of cholesterol metabolism in facilitating drug resistance in cancer. This review aims to describe the role of cholesterol in facilitating multi-drug resistance in cancer. We focus on specific signaling pathways that contribute to drug resistance and the link between these pathways and cholesterol. Additionally, we briefly discuss the molecular mechanisms related to the epithelial-mesenchymal transition (EMT), and the documented link between EMT, metastasis and drug resistance. We illustrate this by specifically focusing on hypoxia and the role it plays in influencing cellular cholesterol content following EMT induction. Finally, we provide a proposed model delineating the crucial role of cholesterol in EMT and discuss whether targeting cholesterol could serve as a novel means of combatting drug resistance in cancer progression and metastasis.

Yang-Yin-Jie-Du decoction overcomes gefitinib resistance in non-small cell lung cancer via down-regulation of the PI3K/Akt signalling pathway

CONTEXT

Yang-Yin-Jie-Du Decoction (YYJDD) was used to improve gefitinib efficacy in our clinical practice, but its mechanism remains unclear.

OBJECTIVE

This study explored if YYJDD could reverse gefitinib resistance.

MATERIALS AND METHODS

H1975 cells were exposed to control, 10 μM gefitinib, 3.2 mg/mL YYJDD or combination treatment. Cell viability was detected by MTT during 0-96 h. Apoptosis and the PI3K/Akt proteins were tested by flow cytometry and western-blot at 24 h. LY294002 was applied to further determine the role of the PI3K/Akt. 23 BALB/c nude xenograft mice received normal saline (n = 5), 80 mg/kg gefitinib (n = 6), 2.35 g/kg lyophilised powder of YYJDD (n = 6) or combination treatment (n = 6) by gavage for 4 weeks and submitted to TUNEL, immunohistochemistry, and western-blot.

RESULTS

In vitro, gefitinib (IC₅₀: 20.68 ± 2.06 μM) and YYJDD (IC₅₀: 6.6 ± 0.21 mg/mL) acted in a moderate synergistic way. Combination treatment inhibited cell viability from 100% to 25.66%. Compared to gefitinb (33.23 ± 3.99%), cell apoptosis was increased with combination treatment (54.11 ± 7.32%), accompanied by down-regulation of the PI3K/Akt. LY294002 further inhibited cell viability, increased apoptosis, and down-regulated p-Akt/Akt. In vivo, the tumour sizes in the combination group (1165.13 ± 157.79 mm³) were smaller than gefitinib alone (1630.66 ± 208.30 mm³). The positive rate of TUNEL staining was increased by combination treatment (22.33 ± 2.75%) versus gefitinib (7.37 ± 0.87%), while the PI3K/Akt was down-regulated.

DISCUSSION AND CONCLUSION

YYJDD has potential to overcome gefitinib resistance. Future investigations should be focussed on its specific targets.

Prognostic significance of preoperative serum triglycerides and high-density lipoproteins cholesterol in patients with non-small cell lung cancer: a retrospective study

Background

Abnormalities in serum lipids and lipoproteins have been documented to link to the risk of cancers in recent years, but its prognostic value for cancer is not known. This study retrospectively evaluated the significance of preoperative serum lipids and lipoproteins for NSCLC’s prognosis.

Methods

A retrospective review was implemented of 551 patients succumbed to NSCLC. A ROC curve was utilized to determine the best cut-off value and area under the ROC curve. Kaplan-Meier and a Cox proportional hazards model were utilized to perform survival analysis.

Results

With a median follow-up of 42 months, the NSCLC patients in the high TG (> 1.21 mmol/L) and low HDL-C (≤ 1.26 mmol/L) two groups exhibited shorter OS and DFS. In multivariable analysis, preoperative HDL-C and TG can work as independent prognosis factors for OS (P<0.001 for both) and DFS (P<0.05 for both) in patients succumbed to NSCLC.

Conclusion

Abnormalities of serum lipids and lipoproteins metabolism linked to the survival outcomes of NSCLC. Preoperative serum HDL-C and TG may be promising biomarkers to predict the NSCLC patients’ prognosis.

Evaluation of Drug-Drug Interactions in EGFR-Mutated Non-Small-Cell Lung Cancer Patients during Treatment with Tyrosine-Kinase Inhibitors

(1) Background. The onset of a drug–drug interaction (DDI) may affect treatment efficacy and toxicity of advanced non-small-cell lung cancer (aNSCLC) patients during epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitor (TKI) use. Here we present the use of Drug-PIN^® (Personalized Interactions Network) software to detect DDIs in aNSCLC patients undergoing EGFR-TKIs. (2) Methods. We enrolled patients with Stage IV aNSCLC already treated with or candidates to receive EGFR-TKIs, in any line; ECOG PS 0–2; taking at least one concomitant drug. Cancer treatments, concomitant drugs, and clinical and laboratory data were collected and inserted in Drug-PIN^®. (3) Results. Ninety-two patients, median age of 68.5 years (range 43–89), were included. In total, 20 clinically relevant DDIs needing medical intervention in a total of 14 patients were identified; the 14 major DDIs were related to a high-grade interaction between TKIs and SSRIs, antipsychotics, antiepileptics, H2-receptor antagonist and calcium antagonists. A negative association between statin intake and PFS was identified (p = 0.02; HR 0.281, 95% CI 0.096–0.825). (4) Conclusions. This is the first retrospective study assessing the prevalence of DDIs, the clinical need for medical intervention and the impact of concomitant drugs on EGFR-TKIs survival in aNSCLC.

Cholesterol and Sphingolipid Enriched Lipid Rafts as Therapeutic Targets in Cancer

Lipid rafts are critical cell membrane lipid platforms enriched in sphingolipid and cholesterol content involved in diverse cellular processes. They have been proposed to influence membrane properties and to accommodate receptors within themselves by facilitating their interaction with ligands. Over the past decade, technical advances have improved our understanding of lipid rafts as bioactive structures. In this review, we will cover the more recent findings about cholesterol, sphingolipids and lipid rafts located in cellular and nuclear membranes in cancer. Collectively, the data provide insights on the role of lipid rafts as biomolecular targets in cancer with good perspectives for the development of innovative therapeutic strategies.

Lipid Metabolism and Resistance to Anticancer Treatment

Simple Summary

Cancer cells directly control nutrient uptake and utilization in a different manner from that of normal cells. These metabolic changes drive growth, proliferation of cancer cells as well as their ability to develop resistance to traditional therapies. We review published studies with pre-clinical models, showing the essential roles of lipid metabolism in anticancer drug resistance. We also discuss how changes in cellular lipid metabolism contribute to the acquisition of drug resistance and the new therapeutic opportunities to target lipid metabolism for treating drug resistant cancers.

Abstract

Metabolic reprogramming is crucial to respond to cancer cell requirements during tumor development. In the last decade, metabolic alterations have been shown to modulate cancer cells’ sensitivity to chemotherapeutic agents including conventional and targeted therapies. Recently, it became apparent that changes in lipid metabolism represent important mediators of resistance to anticancer agents. In this review, we highlight changes in lipid metabolism associated with therapy resistance, their significance and how dysregulated lipid metabolism could be exploited to overcome anticancer drug resistance.

Erlotinib entrapped in cholesterol-depleting cyclodextrin nanoparticles shows improved antitumoral efficacy in 3D spheroid tumors of the lung and the liver

Erlotinib (ERL), a tyrosine kinase inhibitor approved for therapeutic use in non-small cell lung cancer is further researched for eventual liver cancer treatment. However, conventional ERL has important bioavailability problems resulting from oral administration, poor solubility and gastrointestinal degradation into inactive metabolites. Alternative administration routes and nanoparticulate drug delivery systems are studied to prevent or reduce these drawbacks. In this study, ERL-loaded CD nanosphere and nanocapsule formulations capable of cholesterol depletion in resistant cancer cells were evaluated for ERL delivery. Drug loading and release profile depended largely on the surface charge of nanoparticles. Antiproliferative activity data obtained from 2D and 3D cell culture models demonstrated that polycationic βCD nanocapsules were the most effective formulation for ERL delivery to lung and liver cancer cells. 3D tumour tumoral penetration studies further revealed that nanocapsule formulations penetrated deeper into the tumour through the multilayered cells. Furthermore, all formulations were able to extract membrane cholesterol from lung and liver cancer cell lines, indicating the induction of apoptosis and overcoming drug resistance. In conclusion, given their tumoral penetration and cell membrane cholesterol depletion abilities, amphiphilic CD nanocapsules emerge as promising alternatives to improve the safety and efficiency of ERL treatment of both liver and lung tumours.

New Insights Into Targeting Membrane Lipids for Cancer Therapy

Modulation of membrane lipid composition and organization is currently developing as an effective therapeutic strategy against a wide range of diseases, including cancer. This field, known as membrane-lipid therapy, has risen from new discoveries on the complex organization of lipids and between lipids and proteins in the plasma membranes. Membrane microdomains present in the membrane of all eukaryotic cells, known as lipid rafts, have been recognized as an important concentrating platform for protein receptors involved in the regulation of intracellular signaling, apoptosis, redox balance and immune response. The difference in lipid composition between the cellular membranes of healthy cells and tumor cells allows for the development of novel therapies based on targeting membrane lipids in cancer cells to increase sensitivity to chemotherapeutic agents and consequently defeat multidrug resistance. In the current manuscript strategies based on influencing cholesterol/sphingolipids content will be presented together with innovative ones, more focused in changing biophysical properties of the membrane bilayer without affecting the composition of its constituents.

JuBei Oral Liquid Induces Mitochondria-Mediated Apoptosis in NSCLC Cells

Background

Although gefitinib brings about tremendous advances in the treatment of non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations, most of patients become incurable due to drug resistance. JuBei oral liquid (JB) has been widely used to treat pneumonia in clinic. Components of JB were reported to induce apoptosis in NSCLC, which indicated that JB could be a potential antitumor agent for NSCLC patients. In this study, we investigated the effect of JB on gefitinib-sensitive PC-9 and gefitinib-resistant PC-9/GR, H1975 cells as well as its underlying molecular mechanisms.

Methods

PC-9, PC-9/GR and H1975 cells were treated with JB, LY294002, SCH772984, gefitinib alone or in combination. Then, cell viability, colony formation, cell death, expression of mitochondria-dependent pathway proteins, expression of EGFR, PI3K/AKT, MAPK signal pathway proteins, Bcl-2 mitochondrial translocation, ROS generation and cell apoptosis were examined by MTT, colony forming, live/dead cell staining, Western blot, immunofluorescence and flow cytometry assay.

Results

Our results showed that JB significantly induced cell growth inhibition and apoptotic cell death in PC-9, PC-9/GR and H1975 cells. JB activated mitochondria-mediated apoptotic pathway through inhibiting Bcl-2 mitochondrial translocation while inducing Bax translocated into mitochondria along with accumulated ROS production, thereby increasing the release of cytochrome c, subsequently cleaving procaspase9 into cleaved-caspase9 and then cleaving procaspase3 into cleaved-caspase3. Furthermore, the employment of protein kinase inhibitors LY294002 and SCH772984 revealed that the induction of mitochondria-mediated apoptosis by JB was reliant on inactivation of PI3K/AKT and MAPK signal pathways. Moreover, JB could synergize with gefitinib to induce apoptosis in PC-9, PC-9/GR and H1975 cells.

Conclusion

These data indicated that JB could be a potential therapeutic agent for NSCLC patients harboring EGFR mutations as well as those under gefitinib resistance.

Chelidonine selectively inhibits the growth of gefitinib-resistant non-small cell lung cancer cells through the EGFR-AMPK pathway

Tyrosine kinase inhibitors (TKIs) have been widely used for the clinical treatment of patients with non-small cell lung cancer (NSCLC) harboring mutations in the EGFR. Unfortunately, due to the secondary mutation in EGFR, eventual drug-resistance is inevitable. Therefore, to overcome the resistance, new agent is urgently required. Chelidonine, extracted from the roots of Chelidonium majus, was proved to effectively suppress the growth of NSCLC cells with EGFR double mutation. Proteomics analysis indicated that mitochondrial respiratory chain was significantly inhibited by chelidonine, and inhibitor of AMPK effectively blocked the apoptosis induced by chelidonine. Molecular dynamics simulations indicated that chelidonine could directly bind to EGFR and showed a much higher binding affinity to EGFR^L858R/T790M than EGFR^WT, which demonstrated that chelidonine could selectively inhibit the phosphorylation of EGFR in cells with EGFR double-mutation. In vivo study revealed that chelidonine has a similar inhibitory effect like second generation TKI Afatinib. In conclusion, targeting EGFR and inhibition of mitochondrial function is a promising anti-cancer therapeutic strategy for inhibiting NSCLC with EGFR mutation and TKI resistance.

Lung cancer cells survive epidermal growth factor receptor tyrosine kinase inhibitor exposure through upregulation of cholesterol synthesis

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) provide clinical benefits over chemotherapy for lung cancer patients with EGFR activating mutations. Despite initial clinical responses, long-term efficacy is not possible because of acquired resistance to these therapies. We have developed EGFR TKI drug-tolerant (DT) human lung cancer cell lines as a model for de novo resistance. Mass spectroscopic analysis revealed that the cytochrome P450 protein, CYP51A1 (Lanosterol 14α-demethylase), which is directly involved with cholesterol synthesis, was significantly upregulated in the DT cells. Total cellular cholesterol, and more specifically, mitochondrial cholesterol, were found to be upregulated in DT cells. We then used the CYP51A1 inhibitor, ketoconazole, to downregulate cholesterol synthesis. In both parental and DT cells, ketoconazole and EGFR TKIs acted synergistically to induce apoptosis and overcome the development of EGFR tolerance. Lastly, this combination therapy was shown to shrink the growth of tumors in an in vivo mouse model of EGFR TKI resistance. Thus, our study demonstrates for the first time that ketoconazole treatment inhibits upregulation of mitochondrial cholesterol and thereby overcomes EGFR-TKI resistance in lung cancer cells.

Annexin A6 improves anti-migratory and anti-invasive properties of tyrosine kinase inhibitors in EGFR overexpressing human squamous epithelial cells

Annexin A6 (AnxA6), a member of the calcium (Ca²⁺ ) and membrane binding annexins, is known to stabilize and establish the formation of multifactorial signaling complexes. At the plasma membrane, AnxA6 is a scaffold for protein kinase Cα (PKCα) and GTPase-activating protein p120GAP to promote downregulation of epidermal growth factor receptor (EGFR) and Ras/mitogen-activated protein kinase (MAPK) signaling. In human squamous A431 epithelial carcinoma cells, which overexpress EGFR, but lack endogenous AnxA6, restoration of AnxA6 expression (A431-A6) promotes PKCα-mediated threonine 654 (T654)-EGFR phosphorylation, which inhibits EGFR tyrosine kinase activity. This is associated with reduced A431-A6 cell growth, but also decreased migration and invasion in wound healing, matrigel, and organotypic matrices. Here, we show that A431-A6 cells display reduced EGFR activity in vivo, with xenograft analysis identifying increased pT654-EGFR levels, but reduced tyrosine EGFR phosphorylation compared to controls. In contrast, PKCα depletion in A431-A6 tumors is associated with strongly reduced pT654 EGFR levels, yet increased EGFR tyrosine phosphorylation and MAPK activity. Moreover, tyrosine kinase inhibitors (TKIs; gefitinib, erlotinib) more effectively inhibit cell viability, clonogenic growth, and wound healing of A431-A6 cells compared to controls. Likewise, the ability of AnxA6 to inhibit A431 motility and invasiveness strongly improves TKI efficacy in matrigel invasion assays. This correlates with a greatly reduced invasion of the surrounding matrix of TKI-treated A431-A6 when cultured in 3D spheroids. Altogether, these findings implicate that elevated AnxA6 scaffold levels contribute to improve TKI-mediated inhibition of growth and migration, but also invasive properties in EGFR overexpressing human squamous epithelial carcinoma.

SFI Enhances Therapeutic Efficiency of Gefitinib: An Insight into Reversal of Resistance to Targeted Therapy in Non-small Cell Lung Cancer Cells

Background: The clinical application of EGFR tyrosine kinase inhibitors is always accompanied by inevitable drug resistance. However, the mechanism remains elusive. In the present study, we investigate the involvement of MAPK/SREBP1 pathway in NSCLC gefitinib resistance and evaluate the synergistic effects of shenqi fuzheng injection (SFI) and gefitinib on NSCLC cells.

Methods: To investigate the MAPK/SREBP1 pathway involved in gefitinib resistance, Western blotting was used to examine p-MEK, p-ERK and SREBP1 expression in PC-9 and PC-9/GR cells, MTT was used on cell proliferation, wound healing assay was used on cell migration. To detect the cooperative effects of SFI and gefitinib, clonogenic assay was used on cell proliferation. Apoptosis assay was analyzed by flow cytometry. Immunofluorescence was used to detect gefitinib binding to EGFR. Western blotting was used to detect whether SFI regulate the resistance to gefitinib via the suppression of MAPK/SREBP1 pathway.

Results: Our results showed that MAPK/SREBP1 pathway mediated resistance to gefitinib in NSCLC cells. MAPK pathway was found to directly target SREBP1 and inhibition of SREBP1 increased gefitinib sensitivity. In addition, SFI showed cooperative anti-proliferation and pro-apoptosis impacts on gefitinib resistant cells via down-regulating MAPK/SREBP1 pathway. Moreover, the combination of SFI and gefitinib enhanced gefitinib binding to EGFR resulting in the restoration of sensitivity to gefitinib.

Conclusions: Taken together, MAPK/SREBP1 pathway could be regarded as the potential treatment target for overcoming resistance to EGFR-TKIs in NSCLC and adjuvant therapy of SFI could be a potential therapeutic strategy for gefitinib resistant treatment.

Docosahexaenoic Acid Serving As Sensitizing Agents And Gefitinib Resistance Revertants In EGFR Targeting Treatment

Objective

Due to the resistance of cancer cells, chemotherapy has been severely restricted. Docosahexaenoic acid (DHA) has been broadly identified as the chemo-sensitizing agent and revertant of multidrug resistance owing to its pleiotropic characteristics; however, it has not been well interpreted. The purpose of this research was to identify the anticancer role of DHA and its combination with the chemotherapeutic agent Gefitinib in non-small cell lung cancer (NSCLC).

Methods

Human chemo-sensitive NSCLC PC-9 cells and the Gefitinib-resistant counterpart PC-9/GR cells were adopted to assess the effects of the integrated DHA and Gefitinib treatments in vitro and vivo, for which the combination index (CI), apoptosis rate and the epithelial growth factor receptor (EGFR) pathway were analyzed.

Results

Comparing with the control cells, the DHA-treated PC-9/GR cells triggered the increase of drug absorption and sensitivity, suggesting that the sensitivity of chemotherapeutic drug could be induced by DHA. Moreover, the elevation of phosphorylation levels of EGFR and the downstream extracellular signal-regulated kinase (ERK) in the cellular lysates were induced by the DHA+Gefitinib treatment. Additionally, the long-term Gefitinib stimulated PC-9 model revealed that DHA could revert the Gefitinib resistance.

Conclusion

This is the first research that indicated the novel biochemical effect of DHA, which can help in overcoming the resistance of EGFR-TKI in NSCLC cells and broaden the horizon of the DHA supplementation during the NSCLC therapy.

Perturbing the Dynamics and Organization of Cell Membrane Components: A New Paradigm for Cancer-Targeted Therapies

Cancer is a multi-process disease where different mechanisms exist in parallel to ensure cell survival and constant adaptation to the extracellular environment. To adapt rapidly, cancer cells re-arrange their plasma membranes to sustain proliferation, avoid apoptosis and resist anticancer drugs. In this review, we discuss novel approaches based on the modifications and manipulations that new classes of molecules can exert in the plasma membrane lateral organization and order of cancer cells, affecting growth factor signaling, invasiveness, and drug resistance. Furthermore, we present azurin, an anticancer protein from bacterial origin, as a new approach in the development of therapeutic strategies that target the cell membrane to improve the existing standard therapies.