Targeting C4-demethylating genes in the cholesterol pathway sensitizes cancer cells to EGF receptor inhibitors via increased EGF receptor degradation

Chemical Inhibition of Sterol Biosynthesis

Cholesterol is an essential molecule of life, and its synthesis can be inhibited by both genetic and nongenetic mechanisms. Hundreds of chemicals that we are exposed to in our daily lives can alter sterol biosynthesis. These also encompass various classes of FDA-approved medications, including (but not limited to) commonly used antipsychotic, antidepressant, antifungal, and cardiovascular medications. These medications can interfere with various enzymes of the post-lanosterol biosynthetic pathway, giving rise to complex biochemical changes throughout the body. The consequences of these short- and long-term homeostatic disruptions are mostly unknown. We performed a comprehensive review of the literature and built a catalogue of chemical agents capable of inhibiting post-lanosterol biosynthesis. This process identified significant gaps in existing knowledge, which fall into two main areas: mechanisms by which sterol biosynthesis is altered and consequences that arise from the inhibitions of the different steps in the sterol biosynthesis pathway. The outcome of our review also reinforced that sterol inhibition is an often-overlooked mechanism that can result in adverse consequences and that there is a need to develop new safety guidelines for the use of (novel and already approved) medications with sterol biosynthesis inhibiting side effects, especially during pregnancy.

The cholesterol biosynthesis enzyme FAXDC2 couples Wnt/β-catenin to RTK/MAPK signaling

Wnts, cholesterol, and MAPK signaling are essential for development and adult homeostasis. Here, we report that fatty acid hydroxylase domain containing 2 (FAXDC2), a previously uncharacterized enzyme, functions as a methyl sterol oxidase catalyzing C4 demethylation in the Kandutsch-Russell branch of the cholesterol biosynthesis pathway. FAXDC2, a paralog of MSMO1, regulated the abundance of the specific C4-methyl sterols lophenol and dihydro-T-MAS. Highlighting its clinical relevance, FAXDC2 was repressed in Wnt/β-catenin-high cancer xenografts, in a mouse genetic model of Wnt activation, and in human colorectal cancers. Moreover, in primary human colorectal cancers, the sterol lophenol, regulated by FAXDC2, accumulated in the cancerous tissues and not in adjacent normal tissues. FAXDC2 linked Wnts to RTK/MAPK signaling. Wnt inhibition drove increased recycling of RTKs and activation of the MAPK pathway, and this required FAXDC2. Blocking Wnt signaling in Wnt-high cancers caused both differentiation and senescence; and this was prevented by knockout of FAXDC2. Our data show the integration of 3 ancient pathways, Wnts, cholesterol synthesis, and RTK/MAPK signaling, in cellular proliferation and differentiation.

Evaluation of Antifungal Selective Toxicity Using Candida glabrata ERG25 and Human SC4MOL Knock-In Strains

With only four classes of antifungal drugs available for the treatment of invasive systemic fungal infections, the number of resistant fungi is increasing, highlighting the urgent need for novel antifungal drugs. Ergosterol, an essential component of cell membranes, and its synthetic pathway have been targeted for antifungal drug development. Sterol-C4-methyl monooxygenase (Erg25p), which is a greater essential target than that of existing drugs, represents a promising drug target. However, the development of antifungal drugs must consider potential side effects, emphasizing the importance of evaluating their selective toxicity against fungi. In this study, we knocked in ERG25 of Candida glabrata and its human ortholog, SC4MOL, in ERG25-deleted Saccharomyces cerevisiae. Utilizing these strains, we evaluated 1181-0519, an Erg25p inhibitor, that exhibited selective toxicity against the C. glabrata ERG25 knock-in strain. Furthermore, 1181-0519 demonstrated broad-spectrum antifungal activity against pathogenic Candida species, including Candida auris. The approach of utilizing a gene that is functionally conserved between yeast and humans and subsequently screening for molecular target drugs enables the identification of selective inhibitors for both species.

Trogocytosis of cancer-associated fibroblasts promotes pancreatic cancer growth and immune suppression via phospholipid scramblase anoctamin 6 (ANO6)

In pancreatic ductal adenocarcinoma (PDAC), the fibroblastic stroma constitutes most of the tumor mass and is remarkably devoid of functional blood vessels. This raises an unresolved question of how PDAC cells obtain essential metabolites and water-insoluble lipids. We have found a critical role for cancer-associated fibroblasts (CAFs) in obtaining and transferring lipids from blood-borne particles to PDAC cells via trogocytosis of CAF plasma membranes. We have also determined that CAF-expressed phospholipid scramblase anoctamin 6 (ANO6) is an essential CAF trogocytosis regulator required to promote PDAC cell survival. During trogocytosis, cancer cells and CAFs form synapse-like plasma membranes contacts that induce cytosolic calcium influx in CAFs via Orai channels. This influx activates ANO6 and results in phosphatidylserine exposure on CAF plasma membrane initiating trogocytosis and transfer of membrane lipids, including cholesterol, to PDAC cells. Importantly, ANO6-dependent trogocytosis also supports the immunosuppressive function of pancreatic CAFs towards cytotoxic T cells by promoting transfer of excessive amounts of cholesterol. Further, blockade of ANO6 antagonizes tumor growth via disruption of delivery of exogenous cholesterol to cancer cells and reverses immune suppression suggesting a potential new strategy for PDAC therapy.

Arf5-mediated regulation of mTORC1 at the plasma membrane

The mechanistic target of rapamycin (mTOR) kinase regulates a major signaling pathway in eukaryotic cells. In addition to regulation of mTORC1 at lysosomes, mTORC1 is also localized at other locations. However, little is known about the recruitment and activation of mTORC1 at nonlysosomal sites. To identify regulators of mTORC1 recruitment to nonlysosomal compartments, novel interacting partners with the mTORC1 subunit, Raptor, were identified using immunoprecipitation and mass spectrometry. We show that one of the interacting partners, Arf5, is a novel regulator of mTORC1 signaling at plasma membrane ruffles. Arf5-GFP localizes with endogenous mTOR at PI3,4P2-enriched membrane ruffles together with the GTPase required for mTORC1 activation, Rheb. Knockdown of Arf5 reduced the recruitment of mTOR to membrane ruffles. The activation of mTORC1 at membrane ruffles was directly demonstrated using a plasma membrane-targeted mTORC1 biosensor, and Arf5 was shown to enhance the phosphorylation of the mTORC1 biosensor substrate. In addition, endogenous Arf5 was shown to be required for rapid activation of mTORC1-mediated S6 phosphorylation following nutrient starvation and refeeding. Our findings reveal a novel Arf5-dependent pathway for recruitment and activation of mTORC1 at plasma membrane ruffles, a process relevant for spatial and temporal regulation of mTORC1 by receptor and nutrient stimuli.

Cholesterol synthesis enzyme SC4MOL is fine-tuned by sterols and targeted for degradation by the E3 ligase MARCHF6

Cholesterol biosynthesis is a highly regulated pathway, with over 20 enzymes controlled at the transcriptional and post-translational level. Whilst some enzymes remain stable, increased sterol levels can trigger degradation of several synthesis enzymes via the ubiquitin-proteasome system. Of note, we previously identified four cholesterol synthesis enzymes as substrates for one E3 ubiquitin ligase, membrane-associated RING-CH-type finger 6 (MARCHF6). Whether MARCHF6 targets the cholesterol synthesis pathway at other points is unknown. In addition, the post-translational regulation of many cholesterol synthesis enzymes, including the C4-demethylation complex (sterol-C4-methyl oxidase-like, SC4MOL; NAD(P) dependent steroid dehydrogenase-like, NSDHL; hydroxysteroid 17-beta dehydrogenase, HSD17B7) is largely uncharacterized. Using cultured mammalian cell-lines (human-derived and Chinese Hamster Ovary cells), we show SC4MOL, the first acting enzyme of C4-demethylation, is a MARCHF6 substrate, and is rapidly turned over and sensitive to sterols. Sterol depletion stabilizes SC4MOL protein levels, whilst sterol excess downregulates both transcript and protein levels. Furthermore, we found SC4MOL depletion by siRNA results in a significant decrease in total cell cholesterol. Thus, our work indicates SC4MOL is the most regulated enzyme in the C4-demethylation complex. Our results further implicate MARCHF6 as a crucial post-translational regulator of cholesterol synthesis, with this E3 ubiquitin ligase controlling levels of at least five enzymes of the pathway.

CPSF1 positively regulates NSDHL by alternative polyadenylation and promotes gastric cancer progression

Gastric cancer (GC) is a common malignancies with unfavourable prognosis. As one of the most common RNA modifications in nature, alternative polyadenylation (APA) plays a critical role in the progression of carcinomas. CPSF1 is a critical APA-related factor and is involved in many cancers. Nevertheless, the roles and underlying mechanisms of CPSF1 remain unclear in GC. In this work, we identified that CPSF1 is significantly upregulated in GC and that high CPSF1 expression indicates an unfavourable prognosis in GC patients. Moreover, CPSF1 expression levels were closely associated with tumour size, TNM stage and lymph node metastasis. CPSF1 depletion dramatically weakened GC cell proliferation and metastasis. We then performed RNA sequencing and found numerous downstream genes involved the regulation of CPSF1 with remarkable changes in 3'UTR length, among which NSDHL was positively regulated by CPSF1 and promoted GC progression. In addition, rescue assays demonstrated that NSDHL mediated the carcinogenic effect of CPSF1, and this process potentially involved APA. Therefore, this study showed that CPSF1 promotes GC progression, at least in part, by enhancing NSDHL and offered new insights into therapeutic targets for GC.

Down-regulation of MSMO1 promotes the development and progression of pancreatic cancer

Background: Methylsterol monooxygenase 1 (MSMO1), as a completely unique tumor biomarker, plays a vital role in the malignant progression of various cancer. Until now, the potential function and pathway of MSMO1 in the development of pancreatic cancer (PC) has not been explored yet, to our knowledge. Methods: We systematically explored the detail function of MSMO1 in Epithelial-mesenchymal transition (EMT) and cell proliferation of PC in vitro and in vivo. Results: MSMO1 expression was much lower in PC tissues than that in paired normal pancreas. MSMO1 positive expression was negatively associated with T stage, lymph node metastasis and vascular permeation of PC patients. Meanwhile, positive MSMO1 expression indicated a significantly better prognosis and an independent favorable prognostic factor. MSMO1 silencing promoted cell invasion and migration via activating EMT and PI3K-AKT-mTOR pathway [p-PI3K (Tyr458), p-AKT (Ser473) and p-mTOR (Ser2448)] in Capan-2, Panc-1 and SW1990 cells. In vivo, subcutaneous tumor size was enhanced by MSMO1 silencing following with the consistent change of EMT and PI3K/AKT signaling shown in vitro. The motivation of EMT and PI3K-AKT-mTOR pathway was also demonstrated in MSMO1 silencing mouse PANC02 cells. Conclusion: Down-regulation of MSMO1 in PC was associated with advanced progression and poor prognosis of PC patients. MSMO1 acts as a tumor suppressor via inhibiting the aggressive malignant biology of PC accompanying with regulating EMT and PI3K/AKT signaling.

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.

Intracellular Cholesterol Synthesis and Transport

Cholesterol homeostasis is related to multiple diseases in humans, including cardiovascular disease, cancer, and neurodegenerative and hepatic diseases. The cholesterol levels in cells are balanced dynamically by uptake, biosynthesis, transport, distribution, esterification, and export. In this review, we focus on de novo cholesterol synthesis, cholesterol synthesis regulation, and intracellular cholesterol trafficking. In addition, the progression of lipid transfer proteins (LTPs) at multiple contact sites between organelles is considered.

Plasma extracellular vesicle long RNA profiles in the diagnosis and prediction of treatment response for breast cancer

A large number RNAs are enriched and stable in extracellular vesicles (EVs), and they can reflect their tissue origins and are suitable as liquid biopsy markers for cancer diagnosis and treatment efficacy prediction. In this study, we used extracellular vesicle long RNA (exLR) sequencing to characterize the plasma-derived exLRs from 112 breast cancer patients, 19 benign patients and 41 healthy participants. The different exLRs profiling was found between the breast cancer and non-cancer groups. Thus, we constructed a breast cancer diagnostic signature which showed high accuracy with an area under the curve (AUC) of 0.960 in the training cohort and 0.900 in the validation cohort. The signature was able to identify early stage BC (I/II) with an AUC of 0.940. Integrating the signature with breast imaging could increase the diagnosis accuracy for breast cancer patients. Moreover, we enrolled 58 patients who received neoadjuvant treatment and identified an exLR (exMSMO1), which could distinguish pathological complete response (pCR) patients from non-pCR with an AUC of 0.790. Silencing MSMO1 could significantly enhance the sensitivity of MDA-MB-231 cells to paclitaxel and doxorubicin through modulating mTORC1 signaling pathway. This study demonstrated the value of exLR profiling to provide potential biomarkers for early detection and treatment efficacy prediction of breast cancer.

Untargeted Lipidomics of Non-Small Cell Lung Carcinoma Demonstrates Differentially Abundant Lipid Classes in Cancer vs. Non-Cancer Tissue

Lung cancer remains the leading cause of cancer death worldwide and non-small cell lung carcinoma (NSCLC) represents 85% of newly diagnosed lung cancers. In this study, we utilized our untargeted assignment tool Small Molecule Isotope Resolved Formula Enumerator (SMIRFE) and ultra-high-resolution Fourier transform mass spectrometry to examine lipid profile differences between paired cancerous and non-cancerous lung tissue samples from 86 patients with suspected stage I or IIA primary NSCLC. Correlation and co-occurrence analysis revealed significant lipid profile differences between cancer and non-cancer samples. Further analysis of machine-learned lipid categories for the differentially abundant molecular formulas identified a high abundance sterol, high abundance and high m/z sphingolipid, and low abundance glycerophospholipid metabolic phenotype across the NSCLC samples. At the class level, higher abundances of sterol esters and lower abundances of cardiolipins were observed suggesting altered stearoyl-CoA desaturase 1 (SCD1) or acetyl-CoA acetyltransferase (ACAT1) activity and altered human cardiolipin synthase 1 or lysocardiolipin acyltransferase activity respectively, the latter of which is known to confer apoptotic resistance. The presence of a shared metabolic phenotype across a variety of genetically distinct NSCLC subtypes suggests that this phenotype is necessary for NSCLC development and may result from multiple distinct genetic lesions. Thus, targeting the shared affected pathways may be beneficial for a variety of genetically distinct NSCLC subtypes.

RORγ is a context-specific master regulator of cholesterol biosynthesis and an emerging therapeutic target in cancer and autoimmune diseases

Aberrant cholesterol metabolism and homeostasis in the form of elevated cholesterol biosynthesis and dysregulated efflux and metabolism is well recognized as a major feature of metabolic reprogramming in solid tumors. Recent studies have emphasized on major drivers and regulators such as Myc, mutant p53, SREBP2, LXRs and oncogenic signaling pathways that play crucial roles in tumor cholesterol metabolic reprogramming. Therapeutics such as statins targeting the mevalonate pathway were tried at the clinic without showing consistent benefits to cancer patients. Nuclear receptors are prominent regulators of mammalian metabolism. Their de-regulation often drives tumorigenesis. RORγ and its immune cell-specific isoform RORγt play important functions in control of mammalian metabolism, circadian rhythm and immune responses. Although RORγ, together with its closely related members RORα and RORβ were identified initially as orphan receptors, recent studies strongly support the conclusion that specific intermediates and metabolites of cholesterol pathways serve as endogenous ligands of RORγ. More recent studies also reveal a critical role of RORγ in tumorigenesis through major oncogenic pathways including acting a new master-like regulator of tumor cholesterol biosynthesis program. Importantly, an increasing number of RORγ orthosteric and allosteric ligands are being identified that display potent activities in blocking tumor growth and autoimmune disorders in preclinical models. This review summarizes the recent preclinical and clinical progress on RORγ with emphasis on its role in reprogramming tumor cholesterol metabolism and its regulation. It will also discuss RORγ functional mechanisms, context-specificity and its value as a therapeutic target for effective cancer treatment.

Enzymes in the Cholesterol Synthesis Pathway: Interactomics in the Cancer Context

A global protein interactome ensures the maintenance of regulatory, signaling and structural processes in cells, but at the same time, aberrations in the repertoire of protein-protein interactions usually cause a disease onset. Many metabolic enzymes catalyze multistage transformation of cholesterol precursors in the cholesterol biosynthesis pathway. Cancer-associated deregulation of these enzymes through various molecular mechanisms results in pathological cholesterol accumulation (its precursors) which can be disease risk factors. This work is aimed at systematization and bioinformatic analysis of the available interactomics data on seventeen enzymes in the cholesterol pathway, encoded by HMGCR, MVK, PMVK, MVD, FDPS, FDFT1, SQLE, LSS, DHCR24, CYP51A1, TM7SF2, MSMO1, NSDHL, HSD17B7, EBP, SC5D, DHCR7 genes. The spectrum of 165 unique and 21 common protein partners that physically interact with target enzymes was selected from several interatomic resources. Among them there were 47 modifying proteins from different protein kinases/phosphatases and ubiquitin-protein ligases/deubiquitinases families. A literature search, enrichment and gene co-expression analysis showed that about a quarter of the identified protein partners was associated with cancer hallmarks and over-represented in cancer pathways. Our results allow to update the current fundamental view on protein-protein interactions and regulatory aspects of the cholesterol synthesis enzymes and annotate of their sub-interactomes in term of possible involvement in cancers that will contribute to prioritization of protein targets for future drug development.

Unearthing the Janus-face cholesterogenesis pathways in cancer

Cholesterol biosynthesis, primarily associated with eukaryotes, occurs as an essential component of human metabolism with biosynthetic deregulation a factor in cancer viability. The segment that partitions between squalene and the C₂₇-end cholesterol yields the main cholesterogenesis branch subdivided into the Bloch and Kandutsch-Russell pathways. Their importance in cell viability, in normal growth and development originates primarily from the amphipathic property and shape of the cholesterol molecule which makes it suitable as a membrane insert. Cholesterol can also convert to variant oxygenated product metabolites of distinct function producing a complex interplay between cholesterol synthesis and overall steroidogenesis. In this review, we disassociate the two sides of cholesterogenesisis affecting the type and amounts of systemic sterols-one which is beneficial to human welfare while the other dysfunctional leading to misery and disease that could result in premature death. Our focus here is first to examine the cholesterol biosynthetic genes, enzymes, and order of biosynthetic intermediates in human cholesterogenesis pathways, then compare the effect of proximal and distal inhibitors of cholesterol biosynthesis against normal and cancer cell growth and metabolism. Collectively, the inhibitor studies of druggable enzymes and specific biosynthetic steps, suggest a potential role of disrupted cholesterol biosynthesis, in coordination with imported cholesterol, as a factor in cancer development and as discussed some of these inhibitors have chemotherapeutic implications.

Can non-cholesterol sterols indicate the presence of specific dysregulation of cholesterol metabolism in patients with colorectal cancer?

Colorectal cancer (CRC) is a highly prevalent malignancy. Previous studies suggested that cholesterol might play a signficant role in malignant transformation and proliferation. Non-cholesterol sterols (NCS), which are transported by serum lipoproteins alongside cholesterol, are regarded as cholesterol synthesis and absorption markers. Quantification of NCS in serum and HDL fraction (NCS_HDL), could provide a better insight into the cholesterol metabolism. The aim of this study was to examine the status of cholesterol synthesis and cholesterol absorption markers in serum and HDL fraction and explore their interrelation in CRC patients. Current study was designed as observational, case-control study. The study included 73 CRC patients and 95 healthy subjects. NCS and NCS_HDL concentrations were determined by HPLC-MS/MS. Based on NCS and NCS_HDL concentrations, different cholesterol homeostasis indices were calculated. Patients had significantly lower NCS (P<0.001) and NCS_HDL concentrations (P<0.001 for desmosterol_HDL; P<0.05 for lathosterol_HDL, P=0.001 for campesterol_HDL, P<0.001 for β-sitosterol_HDL). NCS_HDL/NCS (P<0.005 for desmosterol_HDL/desmosterol; P<0.05 for lathosterol_HDL/lathosterol; P<0.001 for both β-sitosterol_HDL/β-sitosterol and campesterol_HDL/campesterol) and synthesis to absorption ratio (CSI/CAI) (P<0.005) were increased in CRC patients. Additionally, low serum concentrations of desmosterol (P<0.001; OR=0.329; 95%CI (0.199-0.542)) and campesterol (P<0.001; OR=0.540; 95%CI (0.424-0.687)) were independent predictors of CRC presence. Our data suggest that cholesterol homeostasis in CRC is shifted towards increased synthesis. Relative abundance of NCS in HDL particles is increased, suggesting the possible overproduction of cholesterol precursors in peripheral tissues.

NSDHL promotes triple-negative breast cancer metastasis through the TGFβ signaling pathway and cholesterol biosynthesis

PURPOSE

Metastasis is the main cause of breast cancer mortality. Recent studies have proved that lipid metabolic reprogramming plays critical roles in breast cancer carcinogenesis and metastasis. We aim to identify critical lipid metabolism genes in breast cancer metastasis.

METHODS

We designed and cloned a CRISPR pooled library containing lipid metabolic gene guide RNAs and performed a genetic screen in vivo. Transwell assay and animal experiments were used to evaluate cell metastatic ability in vitro or in vivo, respectively. We performed immunohistochemistry with breast cancer tissue microarray to study the clinical significance of NSDHL.

FINDINGS

We identified a cholesterol metabolic enzyme, NSDHL, as a potential metastatic driver in triple-negative breast cancer. NSDHL was highly expressed in breast cancer tissues and predicted a poor prognosis. NSDHL knockdown significantly suppressed cell proliferation and migration. Mechanistically, NSDHL activated the TGFβ signaling pathway by inhibiting the endosomal degradation of TGFβR2. In addition, blocking the upstream metabolism of NSDHL with ketoconazole rescued cancer metastasis and TGFβR2 degradation. However, the inactivation of NSDHL (Y151X) did not rescue the migration ability and the TGFβR2 protein expression.

CONCLUSION

Taken together, our findings established that NSDHL serves as a metastatic driver, and its function depends on its enzyme activity in cholesterol biosynthesis and is mediated by the NSDHL-TGFβR2 signal pathway. Our study indicated that NSDHL and steroid biosynthesis may serve as new drug targets for patients with advanced breast cancer.

Crystal structures of human NSDHL and development of its novel inhibitor with the potential to suppress EGFR activity

NAD(P)-dependent steroid dehydrogenase-like (NSDHL), an essential enzyme in human cholesterol synthesis and a regulator of epidermal growth factor receptor (EGFR) trafficking pathways, has attracted interest as a therapeutic target due to its crucial relevance to cholesterol-related diseases and carcinomas. However, the development of pharmacological agents for targeting NSDHL has been hindered by the absence of the atomic details of NSDHL. In this study, we reported two X-ray crystal structures of human NSDHL, which revealed a detailed description of the coenzyme-binding site and the unique conformational change upon the binding of a coenzyme. A structure-based virtual screening and biochemical evaluation were performed and identified a novel inhibitor for NSDHL harboring suppressive activity towards EGFR. In EGFR-driven human cancer cells, treatment with the potent NSDHL inhibitor enhanced the antitumor effect of an EGFR kinase inhibitor. Overall, these findings could serve as good platforms for the development of therapeutic agents against NSDHL-related diseases.

The role of the MAD2-TLR4-MyD88 axis in paclitaxel resistance in ovarian cancer

Despite the use of front-line anticancer drugs such as paclitaxel for ovarian cancer treatment, mortality rates have remained almost unchanged for the past three decades and the majority of patients will develop recurrent chemoresistant disease which remains largely untreatable. Overcoming chemoresistance or preventing its onset in the first instance remains one of the major challenges for ovarian cancer research. In this study, we demonstrate a key link between senescence and inflammation and how this complex network involving the biomarkers MAD2, TLR4 and MyD88 drives paclitaxel resistance in ovarian cancer. This was investigated using siRNA knockdown of MAD2, TLR4 and MyD88 in two ovarian cancer cell lines, A2780 and SKOV-3 cells and overexpression of MyD88 in A2780 cells. Interestingly, siRNA knockdown of MAD2 led to a significant increase in TLR4 gene expression, this was coupled with the development of a highly paclitaxel-resistant cell phenotype. Additionally, siRNA knockdown of MAD2 or TLR4 in the serous ovarian cell model OVCAR-3 resulted in a significant increase in TLR4 or MAD2 expression respectively. Microarray analysis of SKOV-3 cells following knockdown of TLR4 or MAD2 highlighted a number of significantly altered biological processes including EMT, complement, coagulation, proliferation and survival, ECM remodelling, olfactory receptor signalling, ErbB signalling, DNA packaging, Insulin-like growth factor signalling, ion transport and alteration of components of the cytoskeleton. Cross comparison of the microarray data sets identified 7 overlapping genes including MMP13, ACTBL2, AMTN, PLXDC2, LYZL1, CCBE1 and CKS2. These results demonstrate an important link between these biomarkers, which to our knowledge has never before been shown in ovarian cancer. In the future, we hope that triaging patients into alterative treatment groups based on the expression of these three biomarkers or therapeutic targeting of the mechanisms they are involved in will lead to improvements in patient outcome and prevent the development of chemoresistance.

NAD(P)-dependent steroid dehydrogenase-like protein and neutral cholesterol ester hydrolase 1 serve as novel markers for early detection of gastric cancer identified using quantitative proteomics

BACKGROUND

Gastric cancer (GC) is the third most common cause of cancer deaths worldwide. In the present study, we aimed to identify novel GC biomarkers by integrating isobaric tags of relative and absolute quantitation (iTRAQ) for aberrantly expressed proteins in GC patients.

METHODS

Using stable isotope tags, we labeled an initial discovery group comprising four paired gastric cancer and adjacent gastric tissue samples, and subjected them to LC-ESI-MS/MS. We used a validation set comprising 129 paired gastric cancer and adjacent gastric tissues from patients and benign healthy controls to validate the candidate targets.

RESULTS

We identified two proteins, NAD(P)-dependent steroid dehydrogenase-like (NSDHL) and neutral cholesterol ester hydrolase 1 (NCEH1), that were significantly overexpressed in GC tissues. The sensitivity and specificity of NSDHL were 80.6% and 74.4%, respectively, in GC compared with a sensitivity of 25.6% in adjacent tissues and 24% in benign healthy controls. The area under the ROC curve (AUC) for NSDHL was 0.810 for GC detection. Overexpression of NSDHL in GC was significantly correlated with local tumor invasion. The sensitivity and specificity of NCEH1 were 77.5% and 73.6%, respectively, in GC compared with a sensitivity of 26.4% in adjacent tissues and 20% in benign controls. The AUC for NSDHL was 0.792. Overexpression of NCEH1 was significantly associated with tumor histological classification and local invasion. Moreover, a combined analysis of NSDHL and NCEH1 achieved a sensitivity and specificity of 85.7% and 83%, respectively, and the AUC was 0.872. The combined analysis of NSDHL and NCEH1 was significantly correlated with histological grade and TNM Ⅱ-Ⅳ staging.

CONCLUSIONS

iTRAQ-labeled quantitative proteomics represents a powerful method to identify novel cancer biomarkers. The present study identified NSDHL and NCEH1 as useful biomarkers for screening, diagnosis, and prognosis of patients with gastric cancer.

Role of cholesterol metabolism in the anticancer pharmacology of selective estrogen receptor modulators

Selective estrogen receptor modulators (SERMs) are a class of compounds that bind to estrogen receptors (ERs) and possess estrogen agonist or antagonist actions in different tissues. As such, they are widely used drugs. For instance, tamoxifen, the most prescribed SERM, is used to treat ERα-positive breast cancer. Aside from their therapeutic targets, SERMs have the capacity to broadly affect cellular cholesterol metabolism and handling, mainly through ER-independent mechanisms. Cholesterol metabolism reprogramming is crucial to meet the needs of cancer cells, and different key processes involved in cholesterol homeostasis have been associated with cancer progression. Therefore, the effects of SERMs on cholesterol homeostasis may be relevant to carcinogenesis, either by contributing to the anticancer efficacy of these compounds or, conversely, by promoting resistance to treatment. Understanding these aspects of SERMs actions could help to design more efficacious therapies. Herein we review the effects of SERMs on cellular cholesterol metabolism and handling and discuss their potential in anticancer pharmacology.

TRIB3-EGFR interaction promotes lung cancer progression and defines a therapeutic target

High expression or aberrant activation of epidermal growth factor receptor (EGFR) is related to tumor progression and therapy resistance across cancer types, including non-small cell lung cancer (NSCLC). EGFR tyrosine kinase inhibitors (TKIs) are first-line therapy for NSCLC. However, patients eventually deteriorate after inevitable acquisition of EGFR TKI-resistant mutations, highlighting the need for therapeutics with alternative mechanisms of action. Here, we report that the elevated tribbles pseudokinase 3 (TRIB3) is positively associated with EGFR stability and NSCLC progression. TRIB3 interacts with EGFR and recruits PKCα to induce a Thr654 phosphorylation and WWP1-induced Lys689 ubiquitination in the EGFR juxtamembrane region, which enhances EGFR recycling, stability, downstream activity, and NSCLC stemness. Disturbing the TRIB3-EGFR interaction with a stapled peptide attenuates NSCLC progression by accelerating EGFR degradation and sensitizes NSCLC cells to chemotherapeutic agents. These findings indicate that targeting EGFR degradation is a previously unappreciated therapeutic option in EGFR-related NSCLC.

KRAS Status is Associated with Metabolic Parameters in Metastatic Colorectal Cancer According to Primary Tumour Location

Colorectal cancer (CRC) is characterized by complex interplay between macroenvironmental factors and tumour microenvironment, leading to variable outcomes in CRC patients. To date, there is still a need to identify macroenvironment/microenvironment factors that could define subgroup of patients that would benefit from specific anti-cancer treatment in order to improve patient selection for individualized targeted-based therapy. Aim of this study was to evaluate associations between metabolic parameters and KRAS status in metastatic CRC (mCRC) according to a new tumour site classification. Retrospective data were extracted from a total of 201 patients diagnosed with mCRC between 2012 and 2017 extracted from an established CRC database at our tertiary institute. Clinical-pathological data, including age, gender, BMI, hypertension, diabetes, pre-CRC diagnosis serum lipid levels and KRAS status were recorded. Categorical characteristics were compared using chi-squared test. Continuous characteristics were compared using Mann-Whitney U test. Log rank test was used to compare hazards for survival. In all comparisons, a two-sided P value <0.05 was considered statistically significant. Out of 201 patients, 170 patients with complete serum lipid profile were included in the analysis. In recto-sigmoid cancers there was a statistically significant association between high cholesterol:high-density lipoprotein (chol:HDL) ratio and KRAS mutation (OR 2.69, 95% CI 1.1–6.4, p = 0,02). In non recto-sigmoid cancers, high cholesterol was associated with KRAS WT (OR 0.39, CI 0.15–0.97, p = 0.04). In 22 patients with KRAS mutated recto-sigmoid cancer stage IV at diagnosis normal chol:HDL ratio was associated with a trend to better survival (p = 0.06). High chol:HDL ratio was significantly associated with KRAS mutated metastatic recto-sigmoid cancers. A subgroup of mCRC patients with KRAS mutated recto-sigmoid cancer may benefit from optimal lipid lowering treatment.

Zebrafish models of skeletal dysplasia induced by cholesterol biosynthesis deficiency

Human disorders of the post-squalene cholesterol biosynthesis pathway frequently result in skeletal abnormalities, yet our understanding of the mechanisms involved is limited. In a forward-genetic approach, we have found that a late-onset skeletal mutant, named kolibernu7 , is the result of a cis-acting regulatory mutation leading to loss of methylsterol monooxygenase 1 (msmo1) expression within pre-hypertrophic chondrocytes. Generated msmo1nu81 knockdown mutation resulted in lethality at larval stage. We demonstrated that this is a result of both cholesterol deprivation and sterol intermediate accumulation by creating a mutation eliminating activity of Lanosterol synthase (Lss). Our results indicate that double lssnu60;msmo1nu81 and single lssnu60 mutants survive significantly longer than msmo1nu81 homozygotes. Liver-specific restoration of either Msmo1 or Lss in corresponding mutant backgrounds suppresses larval lethality. Rescued mutants develop dramatic skeletal abnormalities, with a loss of Msmo1 activity resulting in a more-severe patterning defect of a near-complete loss of hypertrophic chondrocytes marked by col10a1a expression. Our analysis suggests that hypertrophic chondrocytes depend on endogenous cholesterol synthesis, and blocking C4 demethylation exacerbates the cholesterol deficiency phenotype. Our findings offer new insight into the genetic control of bone development and provide new zebrafish models for human disorders of the cholesterol biosynthesis pathway.

Low-density lipoprotein receptor (LDLR) is an independent adverse prognostic factor in acute myeloid leukaemia

The low-density lipoprotein receptor (LDLR) is a membrane receptor that mediates the endocytosis of low-density lipoprotein (LDL). Uptake of LDL has been proposed to contribute to chemotherapy resistance of acute myeloid leukaemia (AML) cell lines in vitro. In the present study, we analysed LDLR expression and survival using bone marrow biopsies from 187 intensively treated patients with AML. Here, increasing LDLR expression was associated with decreasing overall (58·4%, 44·2%, and 24·4%; P = 0·0018), as well as event-free survival (41·7%, 18·1%, and 14·3%; P = 0·0077), and an increasing cumulative incidence of relapse (33·9%, 55·1%, and 71·4%; P = 0·0011). Associations of LDLR expression with survival were confirmed in 557 intensively treated patients from two international validation cohorts. In the analytic and validation cohorts, LDLR expression remained associated with outcome in multivariable regression analyses including the European LeukemiaNet genetic risk classification. Thus, LDLR predicts outcome of patients with AML beyond existing risk factors. Furthermore, we found low expression levels of LDLR in most healthy tissues, suggesting it as a promising target for antibody-based pharmacodelivery approaches in AML.

NAD(P)-dependent steroid dehydrogenase-like is involved in breast cancer cell growth and metastasis

BACKGROUND

The cholesterol biosynthesis pathway is typically upregulated in breast cancer. The role of NAD(P)-dependent steroid dehydrogenase-like (NSDHL) gene, which is involved in cholesterol biosynthesis, in breast cancer remains unknown. This study aimed to uncover the role of NSDHL in the growth and metastasis of breast cancer.

METHODS

After NSDHL knockdown by transfection of short interfering RNA into human breast cancer cell lines (MCF-7, MDA-MB-231 and BT-20) and human breast epithelial cell line (MCF10A), cell proliferation assay, cell cycle analysis, three-dimensional cell culture, clonogenic assay, transwell migration and invasion assays, and wound healing assay were performed. Erlotinib was used as the target drug for epidermal growth factor receptor. Immunodeficient mice (NOD.Cg-Prkdcscid Il2rgtm1wjl /SzJ) were used as orthotropic breast tumor models by injecting them with NSDHL-knockdown MDA-MB-231 cells using lentivirus-carrying NSDHL short hairpin RNA. Clinical data from 3951 breast cancer patients in Gene Expression Omnibus databases were used to investigate the potential prognostic role of NSDHL by survival analysis.

RESULTS

NSDHL knockdown in BT-20, and MDA-MB-231 resulted in a significant decrease in their viability, colony formation, migration, and invasion abilities (p < 0.05). Total cholesterol levels were observed to be significantly decreased in NSDHL-knockdown BT-20 and MDA-MB-231 (p < 0.0001). NSDHL knockdown significantly increased the rate of erlotinib-induced cell death, especially in MDA-MB-231 (p = 0.01). NSDHL knockdown led to significantly decreased tumor growth and lung metastasis in the MDA-MB-231 xenograft model (p < 0.01). Clinically, high NSDHL expression in tumors of patients with breast cancer was associated with significantly reduced recurrence-free survival (p < 0.0001).

CONCLUSIONS

NSDHL might have a role in promoting breast cancer progression. The usage of NSDHL as a therapeutic target in breast cancer needs to be clarified in further studies.

Application of Immunohistochemistry in Basic and Clinical Studies

Immunohistochemistry (IHC), also known as immunohistochemical staining, is an immune morphological analysis. It is a process of selectively identifying antigens (proteins) by antibodies in cells or tissue sections. This chapter introduces the procedure and application of immunohistochemistry. Although immunohistochemistry has a vast application in basic and clinical studies, this chapter focuses on its application in biomarker study, particularly in biomarkers that related to cancer diagnosis, prognosis, and drug development. Detail protocol of immunohistochemistry in formalin-fixed and paraffin-embedded tissue sections is included.

Transcriptional and metabolic rewiring of colorectal cancer cells expressing the oncogenic KRASG13D mutation

Background

Activating mutations in KRAS frequently occur in colorectal cancer (CRC) patients, leading to resistance to EGFR-targeted therapies.

Methods

To better understand the cellular reprogramming which occurs in mutant KRAS cells, we have undertaken a systems-level analysis of four CRC cell lines which express either wild type (wt) KRAS or the oncogenic KRAS^G13D allele (mtKRAS).

Results

RNAseq revealed that genes involved in ribosome biogenesis, mRNA translation and metabolism were significantly upregulated in mtKRAS cells. Consistent with the transcriptional data, protein synthesis and cell proliferation were significantly higher in the mtKRAS cells. Targeted metabolomics analysis also confirmed the metabolic reprogramming in mtKRAS cells. Interestingly, mtKRAS cells were highly transcriptionally responsive to EGFR activation by TGFα stimulation, which was associated with an unexpected downregulation of genes involved in a range of anabolic processes. While TGFα treatment strongly activated protein synthesis in wtKRAS cells, protein synthesis was not activated above basal levels in the TGFα-treated mtKRAS cells. This was likely due to the defective activation of the mTORC1 and other pathways by TGFα in mtKRAS cells, which was associated with impaired activation of PKB signalling and a transient induction of AMPK signalling.

Conclusions

We have found that mtKRAS cells are substantially rewired at the transcriptional, translational and metabolic levels and that this rewiring may reveal new vulnerabilities in oncogenic KRAS CRC cells that could be exploited in future.

Urea Cycle Sustains Cellular Energetics upon EGFR Inhibition in EGFR-Mutant NSCLC

Mutations in oncogenes and tumor suppressor genes engender unique metabolic phenotypes crucial to the survival of tumor cells. EGFR signaling has been linked to the rewiring of tumor metabolism in non-small cell lung cancer (NSCLC). We have integrated the use of a functional genomics screen and metabolomics to identify metabolic vulnerabilities induced by EGFR inhibition. These studies reveal that following EGFR inhibition, EGFR-driven NSCLC cells become dependent on the urea cycle and, in particular, the urea cycle enzyme CPS1. Combining knockdown of CPS1 with EGFR inhibition further reduces cell proliferation and impedes cell-cycle progression. Profiling of the metabolome demonstrates that suppression of CPS1 potentiates the effects of EGFR inhibition on central carbon metabolism, pyrimidine biosynthesis, and arginine metabolism, coinciding with reduced glycolysis and mitochondrial respiration. We show that EGFR inhibition and CPS1 knockdown lead to a decrease in arginine levels and pyrimidine derivatives, and the addition of exogenous pyrimidines partially rescues the impairment in cell growth. Finally, we show that high expression of CPS1 in lung adenocarcinomas correlated with worse patient prognosis in publicly available databases. These data collectively reveal that NSCLC cells have a greater dependency on the urea cycle to sustain central carbon metabolism, pyrimidine biosynthesis, and arginine metabolism to meet cellular energetics upon inhibition of EGFR. IMPLICATIONS: Our results reveal that the urea cycle may be a novel metabolic vulnerability in the context of EGFR inhibition, providing an opportunity to develop rational combination therapies with EGFR inhibitors for the treatment of EGFR-driven NSCLC.

Metabolism and Biological Activities of 4-Methyl-Sterols

4,4-Dimethylsterols and 4-methylsterols are sterol biosynthetic intermediates (C4-SBIs) acting as precursors of cholesterol, ergosterol, and phytosterols. Their accumulation caused by genetic lesions or biochemical inhibition causes severe cellular and developmental phenotypes in all organisms. Functional evidence supports their role as meiosis activators or as signaling molecules in mammals or plants. Oxygenated C4-SBIs like 4-carboxysterols act in major biological processes like auxin signaling in plants and immune system development in mammals. It is the purpose of this article to point out important milestones and significant advances in the understanding of the biogenesis and biological activities of C4-SBIs.

Acetyl-CoA Metabolism Supports Multistep Pancreatic Tumorigenesis

Pancreatic ductal adenocarcinoma (PDA) has a poor prognosis, and new strategies for prevention and treatment are urgently needed. We previously reported that histone H4 acetylation is elevated in pancreatic acinar cells harboring Kras mutations prior to the appearance of premalignant lesions. Because acetyl-CoA abundance regulates global histone acetylation, we hypothesized that altered acetyl-CoA metabolism might contribute to metabolic or epigenetic alterations that promote tumorigenesis. We found that acetyl-CoA abundance is elevated in KRAS-mutant acinar cells and that its use in the mevalonate pathway supports acinar-to-ductal metaplasia (ADM). Pancreas-specific loss of the acetyl-CoA-producing enzyme ATP-citrate lyase (ACLY) accordingly suppresses ADM and tumor formation. In PDA cells, growth factors promote AKT-ACLY signaling and histone acetylation, and both cell proliferation and tumor growth can be suppressed by concurrent BET inhibition and statin treatment. Thus, KRAS-driven metabolic alterations promote acinar cell plasticity and tumor development, and targeting acetyl-CoA-dependent processes exerts anticancer effects. SIGNIFICANCE: Pancreatic cancer is among the deadliest of human malignancies. We identify a key role for the metabolic enzyme ACLY, which produces acetyl-CoA, in pancreatic carcinogenesis. The data suggest that acetyl-CoA use for histone acetylation and in the mevalonate pathway facilitates cell plasticity and proliferation, suggesting potential to target these pathways.See related commentary by Halbrook et al., p. 326.This article is highlighted in the In This Issue feature, p. 305.

Specifically blocking the fatty acid synthesis to inhibit the malignant phenotype of bladder cancer

Fatty acid synthesis is regulated by transcription factors SREBPs and their escort protein SCAP. Malignant cells become dependent on de novo lipogenesis, which sustains rapid proliferation and resistance to cellular stress. Increasing evidence showed SCAP participated in various disease processes including malignant tumors, which regulate transcription factors SREBPs Tumorigenesis is associated with incur glucose consumption and lipogenesis. In our study, we discovered that SCAP was upregulated in BC tissues. SCAP knockdown by CRISPR-Cas9 inhibit the cell proliferation, invasion and migration. Additionally, the cell apoptosis was facilitated. What's more, downregulation of SCAP could weaken the cancer-promoting effects of estrogen on BC. Our study revealed that SCAP played a carcinogenic role in BC and lipogenesis might promote the initiation of BC by inducing SCAP. Thus, Targeting SCAP may provide a promising means of treating BC and a new perspective for the tumorigenesis of bladder cancer.

RNA-Seq analysis reveals a negative role of MSMO1 with a synergized NSDHL expression during adipogenesis of 3T3-L1

To investigate a comprehensive transcriptome information of adipogenesis, we assessed global changes in the transcriptional events during 3T3-L1 adipogenesis by RNA-Seq. Compared to the preadipocyte stage (day 0), gene expression profiling demonstrated that 2013 genes were up-regulated, and 2430 genes were down-regulated at the differentiated adipocyte stage (day 13). Among these differentially expressed genes, we found the expression of MSMO1 was down-regulated at day 13, but whether it impacts adipogenesis has not been characterized. Thus, we investigated its role in adipogenesis. Results showed that overexpression of MSMO1 inhibited the differentiation of 3T3-L1, and led to the down-regulated expression of adipogenic marker genes, while knockdown of MSMO1 had totally opposite effects. Furthermore, interaction network model allowed us to validate an unexpected role between MSMO1 and its partner, NSDHL, in regulating adipogenesis, which plays a synergized expression pattern with MSMO1. Our findings indicate that MSMO1 and NSDHL are novel modulators of adipogenesis.

Caveolin-1 mediates cellular distribution of HER2 and affects trastuzumab binding and therapeutic efficacy

Human epidermal growth factor receptor 2 (HER2) gene amplification and/or protein overexpression in tumors is a prerequisite for initiation of trastuzumab therapy. Although HER2 is a cell membrane receptor, differential rates of endocytosis and recycling engender a dynamic surface pool of HER2. Since trastuzumab must bind to the extracellular domain of HER2, a depressed HER2 surface pool hinders binding. Using in vivo biological models and cultures of fresh human tumors, we find that the caveolin-1 (CAV1) protein is involved in HER2 cell membrane dynamics within the context of receptor endocytosis. The translational significance of this finding is highlighted by our observation that temporal CAV1 depletion with lovastatin increases HER2 half-life and availability at the cell membrane resulting in improved trastuzumab binding and therapy against HER2-positive tumors. These data show the important role that CAV1 plays in the effectiveness of trastuzumab to target HER2-positive tumors.

Trastuzumab binding to tumor cells depends on the availability of HER2 at the cell membrane. Here the authors show that caveolin-1 (CAV1) regulates HER2 density at the cell membranes and that CAV1 gene knockdown or protein depletion via the cholesterol modulator lovastatin, increases trastuzumab binding and anti-tumor activity.

Merlin/ERM proteins regulate growth factor-induced macropinocytosis and receptor recycling by organizing the plasma membrane:cytoskeleton interface

The architectural and biochemical features of the plasma membrane are governed by its intimate association with the underlying cortical cytoskeleton. The neurofibromatosis type 2 (NF2) tumor suppressor merlin and closely related membrane:cytoskeleton-linking protein ezrin organize the membrane:cytoskeleton interface, a critical cellular compartment that both regulates and is regulated by growth factor receptors. An example of this poorly understood interrelationship is macropinocytosis, an ancient process of nutrient uptake and membrane remodeling that can both be triggered by growth factors and manage receptor availability. We show that merlin deficiency primes the membrane:cytoskeleton interface for epidermal growth factor (EGF)-induced macropinocytosis via a mechanism involving increased cortical ezrin, altered actomyosin, and stabilized cholesterol-rich membranes. These changes profoundly alter EGF receptor (EGFR) trafficking in merlin-deficient cells, favoring increased membrane levels of its heterodimerization partner, ErbB2; clathrin-independent internalization; and recycling. Our work suggests that, unlike Ras transformed cells, merlin-deficient cells do not depend on macropinocytic protein scavenging and instead exploit macropinocytosis for receptor recycling. Finally, we provide evidence that the macropinocytic proficiency of NF2-deficient cells can be used for therapeutic uptake. This work provides new insight into fundamental mechanisms of macropinocytic uptake and processing and suggests new ways to interfere with or exploit macropinocytosis in NF2 mutant and other tumors.

Beyond the Biomarker: Understanding the Diverse Roles of Human Epididymis Protein 4 in the Pathogenesis of Epithelial Ovarian Cancer

Human epididymis protein 4 (HE4) is an important clinical biomarker used for the detection of epithelial ovarian cancer (EOC). While much is known about the predictive power of HE4 clinically, less has been reported regarding its molecular role in the progression of EOC. A deeper understanding of HE4’s mechanistic functions may help contribute to the development of novel targeted therapies. Thus far, it has been difficult to recommend HE4 as a therapeutic target owing to the fact that its role in the progression of EOC has not been extensively evaluated. This review summarizes what is collectively known about HE4 signaling and how it functions to promote tumorigenesis, chemoresistance, and metastasis in EOC, with the goal of providing valuable insights that will have the potential to aide in the development of new HE4-targeted therapies.

Inhibition of SLC1A5 sensitizes colorectal cancer to cetuximab

Cetuximab resistance is a key barrier in treating metastatic colorectal cancer (mCRC). Targeting of metabolic resources import could resensitize drug-resistant cancer cells to anticancer treatments. Here we showed that the expression of the glutamine transporter solute carrier 1 family member 5 (SLC1A5) in clinical CRC samples of patients resisted to cetuximab was significantly higher than in those of patients responded to cetuximab. Inhibition of SLC1A5 by shRNA-mediated gene silencing or pharmacological inhibitor significantly suppressed the growth of CRC. Moreover, inhibition of SLC1A5 significantly enhanced the inhibitory efficacy of cetuximab on CRC proliferation both in vitro and in vivo. Mechanistically, SLC1A5 inhibition facilitated EGFR degradation through the ubiquitin-proteasome pathway, and decreased the expression of nuclear EGFR, both of which might have contribution to the improved response to cetuximab. This study provides the metabolic molecule SLC1A5 as a potential therapeutic target to increase the efficacy of cetuximab on CRC.

Liver X receptors agonist GW3965 re-sensitizes gefitinib-resistant human non-small cell lung cancer cell to gefitinib treatment by inhibiting NF-κB in vitro

The recent research shows that the inhibition of the nuclear factor-κB (NF-κB) pathway is a promising therapeutic option for patients who progress after treatment with the novel mutant-selective EGFR-TKIs. For propose to find a nontoxic drug to reverse the acquired gefitinib resistance, we examined whether the Liver X Receptors agonist GW3965 affect gefitinib resistance of HCC827/GR-8-2 cells. Cell viability was measured by CCK-8 assay. Levels of NF-κB, p-AKT and caspases were detected by Western blot analysis. Immunocytochemical analysis was used to detect the expression of NF-κB, p-AKT intracellularly. Induction of apoptosis and cell cycle arrest was measured by Flow cytometry assay. And results revealed that more than 90% of HCC827/GR-8-2 cells lived upon treatment with gefitinib at a dose of 5μM for 48h. However, when under the combine treatment of GW3965 (5μM) & gefitinib(5μM), cell death rate was increased observably. Co-administration of gefitinib & GW3965 induced cell apoptosis and cell cycle arrest. Additionally, we observed a dose-dependent- down-regulation of NF-κB in HCC827/GR-8-2 cells treated with gefitinib & GW3965. GW3965 and gefitinib synergistically decreased cell proliferation and induced apoptosis by inhibiting NF-κB signaling pathway in gefitinib resistant cells. These findings support our hypothesis that GW3965 could act as a useful drug to reverse the gefitinib resistance.

Steatosis induced CCL5 contributes to early-stage liver fibrosis in nonalcoholic fatty liver disease progress

The rapidly increasing prevalence of nonalcoholic fatty liver disease (NAFLD) has become one of the major public health threats in China and worldwide. However, during the development of NAFLD, the key mechanism underlying the progression of related fibrosis remains unclear, which greatly impedes the development of optimal NAFLD therapy. In the current study, we were endeavored to characterize a proinflammatory cytokine, CCL5, as a major contributor for fibrosis in NAFLD. The results showed that CCL5 was highly expressed in fatty liver and NASH patients. In NAFLD rats induced by 8-week-HFD, CCL5 and its receptor, CCR5, were significantly up-regulated and liver fibrosis exclusively occurred in this group. In addition, we showed that hepatocytes are the major source contributing to this CCL5 elevation. Interestingly, a CCL5 inhibitor Met-CCL5, significantly decreased liver fibrosis but not hepatic steatosis. Using a cell model of hepatic steatosis, we found that the conditioned medium of lipid-overloaded hepatocytes (Fa2N-4 cells) which produced excessive CCL5 stimulated the profibrotic activities of hepatic stellate cells (LX-2) as manifested by increased migration rate, proliferation and collagen production of LX-2 cells. CCL5 knockdown in Fa2N-4 cells, Met-CCL5 or CCR5 antibody treatment on LX-2 cells all significantly inhibited the conditioned medium of FFA-treated Fa2N-4 cells to exert stimulatory effects on LX-2 cells. Consistently, the conditioned medium of Fa2N-4 cells with CCL5 over-expression significantly enhanced migration rate, cell proliferation and collagen production of LX-2 cells. All these results support that CCL5 produced by steatotic hepatocytes plays an essential role in fibrotic signaling machinery of NAFLD. In addition, we were able to identify C/EBP-β as the up-stream regulator of CCL5 gene transcription in hepatocytes treated with free fatty acid (FFA). Our data strongly supported that CCL5 plays a pivotal regulatory role in hepatic fibrosis during NAFLD, which constitutes a novel and exciting observation that may call for potential future development of specific CCL5-targeted NAFLD therapy.

EGFR and RB1 as Dual Biomarkers in HPV-Negative Head and Neck Cancer

Clinical decision making for human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) is predominantly guided by disease stage and anatomic location, with few validated biomarkers. The epidermal growth factor receptor (EGFR) is an important therapeutic target, but its value in guiding therapeutic decision making remains ambiguous. We integrated analysis of clinically annotated tissue microarrays with analysis of data available through the TCGA, to investigate the idea that expression signatures involving EGFR, proteins regulating EGFR function, and core cell-cycle modulators might serve as prognostic or drug response-predictive biomarkers. This work suggests that consideration of the expression of NSDHL and proteins that regulate EGFR recycling in combination with EGFR provides a useful prognostic biomarker set. In addition, inactivation of the tumor suppressor retinoblastoma 1 (RB1), reflected by CCND1/CDK6-inactivating phosphorylation of RB1 at T356, inversely correlated with expression of EGFR in patient HNSCC samples. Moreover, stratification of cases with high EGFR by expression levels of CCND1, CDK6, or the CCND1/CDK6-regulatory protein p16 (CDKN2A) identified groups with significant survival differences. To further explore the relationship between EGFR and RB1-associated cell-cycle activity, we evaluated simultaneous inhibition of RB1 phosphorylation with the CDK4/6 inhibitor palbociclib and of EGFR activity with lapatinib or afatinib. These drug combinations had synergistic inhibitory effects on the proliferation of HNSCC cells and strikingly limited ERK1/2 phosphorylation in contrast to either agent used alone. In summary, combinations of CDK and EGFR inhibitors may be particularly useful in EGFR and p^T356RB1-expressing or CCND1/CDK6-overexpressing HPV-negative HNSCC. Mol Cancer Ther; 15(10); 2486-97. ©2016 AACR.

4-Methylzymosterone and Other Intermediates of Sterol Biosynthesis from Yeast Mutants Engineered in the ERG27 Gene Encoding 3-Ketosteroid Reductase

Studies in the post-squalene section of sterol biosynthesis may be hampered by the poor availability of authentic standards. The present study used different yeast strains engineered in 3-ketosteroid reductase (Erg27p) to obtain radioactive and non-radioactive intermediates of sterol biosynthesis hardly or not available commercially. Non-radioactive 3-keto 4-monomethyl sterones were purified from non-saponifiable lipids extracted from cells bearing point-mutated 3-ketosteroid reductase. Two strategies were adopted to prepare the radioactive compounds: (1) incubation of cell homogenates of an ERG27-deletant strain with radioactive lanosterol, (2) incubation of growing cells of a strain expressing point-mutated 3-ketosteroid reductase with radioactive acetate. Chemical reduction of both radioactive and non-radioactive 3-keto sterones gave the physiological 3-β OH sterols, as well as the non-physiological 3-α OH isomers. This combined biological and chemical preparation procedure provided otherwise unavailable or hardly available 4-mono-methyl intermediates of sterol biosynthesis, paving the way for research into their roles in physiological and pathological conditions.

The Role of Cholesterol in Cancer

The roles played by cholesterol in cancer development and the potential of therapeutically targeting cholesterol homeostasis is a controversial area in the cancer community. Several epidemiologic studies report an association between cancer and serum cholesterol levels or statin use, while others suggest that there is not one. Furthermore, the Cancer Genome Atlas (TCGA) project using next-generation sequencing has profiled the mutational status and expression levels of all the genes in diverse cancers, including those involved in cholesterol metabolism, providing correlative support for a role of the cholesterol pathway in cancer development. Finally, preclinical studies tend to more consistently support the role of cholesterol in cancer, with several demonstrating that cholesterol homeostasis genes can modulate development. Because of space limitations, this review provides selected examples of the epidemiologic, TCGA, and preclinical data, focusing on alterations in cholesterol homeostasis and its consequent effect on patient survival. In melanoma, this focused analysis demonstrated that enhanced expression of cholesterol synthesis genes was associated with decreased patient survival. Collectively, the studies in melanoma and other cancer types suggested a potential role of disrupted cholesterol homeostasis in cancer development but additional studies are needed to link population-based epidemiological data, the TCGA database results, and preclinical mechanistic evidence to concretely resolve this controversy. Cancer Res; 76(8); 2063-70. ©2016 AACR.

Endogenous Sterol Metabolites Regulate Growth of EGFR/KRAS-Dependent Tumors via LXR

Meiosis-activating sterols (MAS) are substrates of SC4MOL and NSDHL in the cholesterol pathway and are important for normal organismal development. Oncogenic transformation by epidermal growth factor receptor (EGFR) or RAS increases the demand for cholesterol, suggesting a possibility for metabolic interference. To test this idea in vivo, we ablated Nsdhl in adult keratinocytes expressing KRAS(G12D). Strikingly, Nsdhl inactivation antagonized the growth of skin tumors while having little effect on normal skin. Loss of Nsdhl induced the expression of ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, reduced the expression of low-density lipoprotein receptor (LDLR), decreased intracellular cholesterol, and was dependent on the liver X receptor (LXR) α. Importantly, EGFR signaling opposed LXRα effects on cholesterol homeostasis, whereas an EGFR inhibitor synergized with LXRα agonists in killing cancer cells. Inhibition of SC4MOL or NSDHL, or activation of LXRα by sterol metabolites, can be an effective strategy against carcinomas with activated EGFR-KRAS signaling.

Compounds identified by virtual docking to a tetrameric EGFR extracellular domain can modulate Grb2 internalization

Background

Overexpression or mutation of the epidermal growth factor receptor (EGFR) potently enhances the growth of many solid tumors. Tumor cells frequently display resistance to mechanistically-distinct EGFR-directed therapeutic agents, making it valuable to develop therapeutics that work by additional mechanisms. Current EGFR-targeting therapeutics include antibodies targeting the extracellular domains, and small molecules inhibiting the intracellular kinase domain. Recent studies have identified a novel prone extracellular tetrameric EGFR configuration, which we identify as a potential target for drug discovery.

Methods

Our focus is on the prone EGFR tetramer, which contains a novel protein-protein interface involving extracellular domain III. This EGFR tetramer is computationally targeted for stabilization by small molecule ligand binding. This study performed virtual screening of a Life Chemicals, Inc. small molecule library of 345,232 drug-like compounds against a molecular dynamics simulation of protein-protein interfaces distinct to the novel tetramer. One hundred nine chemically diverse candidate molecules were selected and evaluated using a cell-based high-content imaging screen that directly assessed induced internalization of the EGFR effector protein Grb2. Positive hits were further evaluated for influence on phosphorylation of EGFR and its effector ERK1/2.

Results

Fourteen hit compounds affected internalization of Grb2, an adaptor responsive to EGFR activation. Most hits had limited effect on cell viability, and minimally influenced EGFR and ERK1/2 phosphorylation. Docked hit compound poses generally include Arg270 or neighboring residues, which are also involved in binding the effective therapeutic cetuximab, guiding further chemical optimization.

Conclusions

These data suggest that the EGFR tetrameric configuration offers a novel cancer drug target.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1415-6) contains supplementary material, which is available to authorized users.

Analysis of hedgehog signaling in cerebellar granule cell precursors in a conditional Nsdhl allele demonstrates an essential role for cholesterol in postnatal CNS development

NSDHL is a 3β-hydroxysterol dehydrogenase that is involved in the removal of two C-4 methyl groups in one of the later steps of cholesterol biosynthesis. Mutations in the gene encoding the enzyme are responsible for the X-linked, male lethal mouse mutations bare patches and striated, as well as most cases of human CHILD syndrome. Rare, hypomorphic NSDHL mutations are also associated with X-linked intellectual disability in males with CK syndrome. Since hemizygous male mice with Nsdhl mutations die by midgestation, we generated a conditional targeted Nsdhl mutation (Nsdhl(tm1.1Hrm)) to investigate the essential role of cholesterol in the early postnatal CNS. Ablation of Nsdhl in radial glia using GFAP-cre resulted in live-born, normal appearing affected male pups. However, the pups develop overt ataxia by postnatal day 8-10 and die shortly thereafter. Histological abnormalities include progressive loss of cortical and hippocampal neurons, as well as deficits in the proliferation and migration of cerebellar granule precursors and subsequent massive apoptosis of the cerebellar cortex. We replicated the granule cell precursor proliferation defect in vitro and demonstrate that it results from defective signaling by SHH. Furthermore, this defect is almost completely rescued by supplementation of the culture media with exogenous cholesterol, while methylsterol accumulation above the enzymatic block appears to be associated with increased cell death. These data support the absolute requirement for cholesterol synthesis in situ once the blood-brain-barrier forms and cholesterol transport to the fetus is abolished. They further emphasize the complex ramifications of cholesterogenic enzyme deficiency on cellular metabolism.

Two C4-sterol methyl oxidases (Erg25) catalyse ergosterol intermediate demethylation and impact environmental stress adaptation in Aspergillus fumigatus

The human pathogen Aspergillus fumigatus adapts to stress encountered in the mammalian host as part of its ability to cause disease. The transcription factor SrbA plays a significant role in this process by regulating genes involved in hypoxia and low-iron adaptation, antifungal drug responses and virulence. SrbA is a direct transcriptional regulator of genes encoding key enzymes in the ergosterol biosynthesis pathway, including erg25A and erg25B, and ΔsrbA accumulates C4-methyl sterols, suggesting a loss of Erg25 activity [C4-sterol methyl oxidase (SMO)]. Characterization of the two genes encoding SMOs in Aspergillus fumigatus revealed that both serve as functional C4-demethylases, with Erg25A serving in a primary role, as Δerg25A accumulates more C4-methyl sterol intermediates than Δerg25B. Single deletion of these SMOs revealed alterations in canonical ergosterol biosynthesis, indicating that ergosterol may be produced in an alternative fashion in the absence of SMO activity. A Δerg25A strain displayed moderate susceptibility to hypoxia and the endoplasmic reticulum stress-inducing agent DTT, but was not required for virulence in murine or insect models of invasive aspergillosis. Inducing expression of erg25A partially restored the hypoxia growth defect of ΔsrbA. These findings implicated Aspergillus fumigatus SMOs in the maintenance of canonical ergosterol biosynthesis and indicated an overall involvement in the fungal stress response.