Iciartin, a novel FASN inhibitor, exerts anti-melanoma activities through IGF-1R/STAT3 signaling

Unraveling lipid metabolism reprogramming for overcoming drug resistance in melanoma

Cutaneous melanoma is the deadliest form of skin cancer, and its incidence is continuing to increase worldwide in the last decades. Traditional therapies for melanoma can easily cause drug resistance, thus the treatment of melanoma remains a challenge. Various studies have focused on reversing the drug resistance. As tumors grow and progress, cancer cells face a constantly changing microenvironment made up of different nutrients, metabolites, and cell types. Multiple studies have shown that metabolic reprogramming of cancer is not static, but a highly dynamic process. There is a growing interest in exploring the relationship between melanoma andmetabolic reprogramming, one of which may belipid metabolism. This review frames the recent research progresses on lipid metabolism in melanoma.In addition, we emphasize the dynamic ability of metabolism during tumorigenesis as a target for improving response to different therapies and for overcoming drug resistance in melanoma.

Icaritin: A phytomolecule with enormous pharmacological values

Pharmacological studies on flavonoids have always drawn much interest for many years. Icaritin (ICT), a representative flavone containing an 8-prenyl group, is a principal compound detected in medicinal plants of the genus Epimedum, the family Berberidaceae. Experimental results in the phytochemistry and pharmacology of this molecule are abundant now, but a deep overview has not been carried out. The goal of this review is to provide an insight into the natural observation, biosynthesis, biotransformation, synthesis, pharmacology, and pharmacokinetics of prenyl flavone ICT. The relevant data on ICT was collected from bibliographic sources, like Google Scholar, Web of Science, Sci-Finder, and various published journals. "Icaritin" alone or in combination is the main keyword to seek for references, and references have been updated till now. ICT is among the characteristic phytomolecules of Epimedum plants. Bacteria monitored its biosynthesis and biotransformation, while this agent was rapidly synthesized from phloroglucinol by microwave-assistance Claisen rearrangement. ICT is a potential agent in numerous in vitro and in vivo pharmacological records, which demonstrated its role in cancer treatments via apoptotic-related mechanisms. It also brings in various health benefits since it reduced harmful effects on the liver, lung, heart, bone, blood, and skin, and improved immune responses. Pharmacokinetic outcomes indicated that its metabolic pathway involved hydration, hydroxylation, dehydrogenation, glycosylation, and glucuronidation. Molecule mechanisms of action at a cellular level are predominant, but clinical studies are expected to get more. Structure-activity relationship records seem insufficient, and the studies on nano-combined approaches to improve its soluble property in living bodied medium are needed.

STAT proteins in cancer: orchestration of metabolism

Reprogrammed metabolism is a hallmark of cancer. However, the metabolic dependency of cancer, from tumour initiation through disease progression and therapy resistance, requires a spectrum of distinct reprogrammed cellular metabolic pathways. These pathways include aerobic glycolysis, oxidative phosphorylation, reactive oxygen species generation, de novo lipid synthesis, fatty acid β-oxidation, amino acid (notably glutamine) metabolism and mitochondrial metabolism. This Review highlights the central roles of signal transducer and activator of transcription (STAT) proteins, notably STAT3, STAT5, STAT6 and STAT1, in orchestrating the highly dynamic metabolism not only of cancer cells but also of immune cells and adipocytes in the tumour microenvironment. STAT proteins are able to shape distinct metabolic processes that regulate tumour progression and therapy resistance by transducing signals from metabolites, cytokines, growth factors and their receptors; defining genetic programmes that regulate a wide range of molecules involved in orchestration of metabolism in cancer and immune cells; and regulating mitochondrial activity at multiple levels, including energy metabolism and lipid-mediated mitochondrial integrity. Given the central role of STAT proteins in regulation of metabolic states, they are potential therapeutic targets for altering metabolic reprogramming in cancer.

Fatty Acid Synthase (FASN): A Patent Review Since 2016-Present

INTRODUCTION

Fatty acid synthase (FASN), is a key metabolic enzyme involved in fatty acid biosynthesis and is an essential target for multiple disease progressions like cancer, obesity, NAFLD, etc. Aberrant expression of FASN is associated with deregulated energy metabolism of cells in these diseases.

AREA COVERED

This article provides a summary of the most recent developments in the discovery of novel FASN inhibitors with potential therapeutic uses in cancer, obesity, and other metabolic disorders such as nonalcoholic fatty liver disease from 2016 to the present. The recently published patent applications and forthcoming clinical data of FASN inhibitors from both academia and the pharma industries are also highlighted in this study.

EXPERT OPINION

The implication of FASN in multiple diseases has provided an impetus for developing novel inhibitors by both pharma companies and academia. Critical analysis of the patent literature reveals the exploration of diverse molecular scaffolds to identify potential FASN inhibitors that target the different catalytic domains of the enzyme. In spite of these multifaceted efforts, only one molecule, TVB-2640, has reached phase II trials for nonalcoholic steatohepatitis (NASH) and many malignancies. However, thecombined efforts of pharma companies to produce several FASN inhibitors might facilitate the clinical translation of this unique class of inhibitors. Nevertheless, concerted efforts towards developing multiple FASN inhibitors by pharma companies might facilitate the clinical translation of this novel class of inhibitors.

Topical VX-509 attenuates psoriatic inflammation through the STAT3/FABP5 pathway in keratinocytes

BACKGROUND

Psoriasis is a chronic inflammatory disease, with lesions mainly manifesting as scaly erythematous plaques. The mild or moderate of psoriasis is the main type of patients in hospital, and topical application remains the preferred treatment option for psoriasis therapy, therefore, the development of novel topical agents has an essential role in psoriasis therapy.

OBJECTIVE

To identify potential drugs for psoriasis topical treatment.

METHODS

We performed drug screening by Imiquimod (IMQ)-induced psoriatic like inflammation in mouse model, followed mouse epidermis by RNA-seq to find the key molecules affecting the drug. The qRT-PCR, WB were performed to test mRNA and protein expression, and Chip assay had been conducted to examine Stat3 bound to promoter of FABP5.

RESULTS

In this study, we identified VX-509, which topical application significantly attenuated IMQ-induced psoriatic like inflammation in mouse model. And then, we verified Epidermal Fatty acid binding protein (E-FABP/FABP5) was significantly decreased in VX-509 treated mouse epidermis by RNA-seq. FABP5 is a key molecule in lipid metabolism, administration of FABP5 inhibitor or knock down of FABP5 expression remarkably abrogated psoriatic inflammation as well as lipid metabolism. Mechanistically, our finding showed that VX-509 blocked IL-22 induced signaling pathway, particular in activation of Stat3. Furthermore, we identified Stat3 is a transcriptional factor associated with FABP5 promoters and VX-509 treatment remarkably attenuated IL-22-induced FABP5 expression through Stat3 in KCs.

CONCLUSIONS

This study demonstrated administration of VX-509 is a potential promising topical drug for treatment of psoriasis, FABP5 is a critical targeted molecule in psoriasis therapy.

Insulin-Like Growth Factor 1 Receptor Drives Hepatocellular Carcinoma Growth and Invasion by Activating Stat3-Midkine-Stat3 Loop

BACKGROUND

Activation of the insulin-like growth factor 1 receptor (IGF-1R)-mediated Janus kinase (JAK)1/2-Stat3 pathway contributes to hepatocarcinogenesis. Specifically, a previous study showed that IGF-1R inhibition downregulated Midkine expression in hepatocellular carcinoma (HCC).

AIMS

The present study investigated the role of IGF-1R-JAK1/2-Stat3 and Midkine signaling in HCC, in addition to the molecular link between the IGF-1R-Stat3 pathway and Midkine.

METHODS

The expression levels of IGF-1R, Stat3, and Midkine were measured using reverse transcription-quantitative PCR, following which the association of IGF-1R with Stat3 and Midkine expression was evaluated in HCC. The molecular link between the IGF-1R-Stat3 pathway and Midkine was then investigated in vitro before the effect of IGF-1R-Stat3 and Midkine signaling on HCC growth and invasion was studied in vitro and in vivo.

RESULTS

IGF-1R, Stat3, and Midkine mRNA overexpressions were all found in HCC, where the levels of Stat3 and Midkine mRNA correlated positively with those of IGF-1R. In addition, Midkine mRNA level also correlated positively with Stat3 mRNA expression in HCC tissues. IGF-1R promoted Stat3 activation, which in turn led to the upregulation of Midkine expression in Huh7 cells. Similarly, Midkine also promoted Stat3 activation through potentiating JAK1/2 phosphorylation. Persistent activation of this Stat3-Midkine-Stat3 positive feedback signal loop promoted HCC growth and invasion, the inhibition of which resulted in significant antitumor activities both in vitro and in vivo.

CONCLUSIONS

Constitutive activation of the IGF-1R-mediated Stat3-Midkine-Stat3 positive feedback loop is present in HCC, the inhibition of which can serve as a potential therapeutic intervention strategy for HCC.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

STAT3 as a mediator of oncogenic cellular metabolism: Pathogenic and therapeutic implications

The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is activated constitutively in a wide array of human cancers. It is an appealing molecular target for novel therapy as it directly regulates expression of genes involved in cell proliferation, survival, angiogenesis, chemoresistance and immune responsiveness. In addition to these well-established oncogenic roles, STAT3 has also been found to mediate a wide array of functions in modulating cellular behavior. The transcriptional function of STAT3 is canonically regulated through tyrosine phosphorylation. However, STAT3 phosphorylated at a single serine residue can allow incorporation of this protein into the inner mitochondrial membrane to support oxidative phosphorylation (OXPHOS) and maximize the utility of glucose sources. Conflictingly, its canonical transcriptional activity suppresses OXPHOS and favors aerobic glycolysis to promote oncogenic behavior. Apart from mediating the energy metabolism and controversial effects on ATP production, STAT3 signaling modulates lipid metabolism of cancer cells. By mediating fatty acid synthesis and beta oxidation, STAT3 promotes employment of available resources and supports survival in the conditions of metabolic stress. Thus, the functions of STAT3 extend beyond regulation of oncogenic genes expression to pleiotropic effects on a spectrum of essential cellular processes. In this review, we dissect the current knowledge on activity and mechanisms of STAT3 involvement in transcriptional regulation, mitochondrial function, energy production and lipid metabolism of malignant cells, and its implications to cancer pathogenesis and therapy.

Baicalein Potentiated M1 Macrophage Polarization in Cancer Through Targeting PI3Kγ/ NF-κB Signaling

Baicalein is one of the bioactive compounds extracted from Scutellaria baicalensis. Recent studies indicated the antitumor effects of baicalein, however, the underlying mechanisms are needed to be further determined. In this study, we found that baicalein could inhibit the tumor growth in mice models of breast cancer and melanoma and worked as an immunomodulator to promote the infiltration of tumor-associated macrophages (TAMs) and skew the TAMs towards the M1-like phenotype. Baicalein also induced M1-like phenotype polarization in THP-1-derived macrophages. Meanwhile, the expression of pro-inflammatory factors associated with M1 macrophages, including TNF-α, IL-1β, CXCL9 and CXCL10, were increased after baicalein treatment. Mechanistically, the RNA-seq data suggested that baicalein potentiated the M1 macrophage polarization via the NF-κB/TNF-α signaling pathway. ELISA and confocal microscopy assay confirmed that baicalein significantly induced the production of TNF-α and the activation of NF-κB, while TNF-α neutralization inhibited baicalein-induced macrophage polarization toward M1, and NF-κB P65 knock-down suppressed baicalein-induced TNF-α production in THP-1-derived macrophages. Phosphoinositide 3-kinase (PI3k) γ has been reported as a key molecule in macrophage polarization, and inhibition of PI3Kγ activates the NF-κB-related inflammatory signals. Our pharmacological network analysis predicted that PI3Kγ might be one of the major targets of baicalein. The results from the docking program and surface plasmon resonance (SPR) confirmed that baicalein displayed good binding activity to PI3Kγ. We further found that baicalein not only exhibited a direct inhibitory effect on the protein kinase activity of PI3Kγ, but also reduced the mRNA and protein expression of PI3Kγ, indicating that baicalein might be a novel PI3Kγ inhibitor. In summary, baicalein mediated the TAMs skewing to M1-TAMs, and then retarded tumor growth. These effects, at least in part, were linked to the PI3Kγ/NF-κB signaling.

Microbial transformation of icariin and its derivatives

Microbial transformation is an important tool to perform selective conversion of compounds to derivatives which are difficult to produce synthetically. In order to obtain icariside II and icaritin, the active components in Herba Epimedii in vivo, biotransformation studies using microbes as biocatalysts were carried out. Icariside II (2) and icaritin (3) were produced through biotransformation of icariin (1) using the fungi Hormoconis resinae and Mortierella ramanniana var. angulispora in 98% and 92% yields, respectively. In the subsequent transformation studies, 2 was deglycosylated to form 3 by Gliocladium deliquescens, whereas 3 was further converted to a novel compound icaritin-3-O-β-d-glucopyranoside (4) and previously known icaritin-3,7-O-β-d-diglucopyranoside (5) by Mucor hiemalis. Biological evaluation of these compounds using MTT assay exhibited potent cytotoxic activities against human cancer cell lines A549, A375P, and MCF-7, with icariin being the most active, indicating that glycosylation plays a role in the cytotoxic activity.

Icaritin inhibits PD-L1 expression by Targeting Protein IκB Kinase α

Icaritin, a small molecule currently being investigated in phase III clinical trials in China (NCT03236636 and NCT03236649) for treatment of advanced hepatocellular carcinoma (HCC), is a prenylflavonoid derivative obtained from the Epimedium genus. Previously, it was found that Icaritin decreased the expression of PD-L1, but its direct molecular targets and the underlying mechanisms have not been identified. In this study, we report the identification of IKK-α as the protein target of Icaritin by biotin-based affinity binding assay. The further mutagenesis assay has provided evidence that C46 and C178 in IKK-α were essential amino acids for Icaritin binding to IKK-α, revealing the binding sites of Icaritin to IKK-α for the first time. Functionally, Icaritin inhibited the NF-κB signalling pathway by blocking IKK complex formation, which led to decreased nuclear translocation of NF-κB p65, and subsequent downregulation of PD-L1 expression in a dose-dependent manner. More importantly, PD-L1-positive patients exhibited longer overall survival upon Icaritin therapy. Finally, Icaritin in combination with checkpoints antibodies, such as α-PD-1, has demonstrated much better efficacy than any single therapy in animal models. This is the first report that anticancer effects of Icaritin are mediated, at least in part, by impairing functions of IKK-α.

Icaritin Inhibits Skin Fibrosis through Regulating AMPK and Wnt/β-catenin Signaling

Skin fibrosis is one of the major features of scleroderma. WNT/β-catenin signaling is associated with the progression of skin fibrosis. In this study, we aimed to determine the effect of icaritin (IT), a natural compound, on scleroderma-related skin fibrosis and its mechanisms. We found that IT could reduce the expression of COL1A1, COL1A2, COL3A1, CTGF, and α-SMA in human foreskin fibroblasts (HFF-1 cells), scleroderma skin fibroblasts (SSF cells), and TGF-β-induced HFF-1 cells. Wnt/β-catenin signaling was shown to be suppressed by IT. Additionally, IT activated AMPK signaling in HFF-1 cells. In conclusion, IT has an anti-skin fibrotic effect through activation of AMPK signaling and inhibition of WNT/β-catenin signaling. Our findings indicate the potential role of IT in the treatment of scleroderma and provide novel insight for the selection of drug therapy for scleroderma.

Upregulation of cell surface GD3 ganglioside phenotype is associated with human melanoma brain metastasis

Melanoma metastasis to the brain is one of the most frequent extracranial brain tumors. Cell surface gangliosides are elevated in melanoma metastasis; however, the metabolic regulatory mechanisms that govern these specific changes are poorly understood in melanoma particularly brain metastases (MBM) development. We found ganglioside GD3 levels significantly upregulated in MBM compared to lymph node metastasis (LNM) but not for other melanoma gangliosides. Moreover, we demonstrated an upregulation of ST8SIA1 (GD3 synthase) as melanoma progresses from melanocytes to MBM cells. Using RNA‐ISH on FFPE specimens, we evaluated ST8SIA1 expression in primary melanomas (PRM) (n = 23), LNM and visceral metastasis (n = 45), and MBM (n = 39). ST8SIA1 was significantly enhanced in MBM compared to all other specimens. ST8SIA1 expression was assessed in clinically well‐annotated melanoma patients from multicenters with AJCC stage III B‐D LNM (n = 58) with 14‐year follow‐up. High ST8SIA1 expression was significantly associated with poor overall survival (HR = 3.24; 95% CI, 1.19–8.86, P = 0.02). In a nude mouse human xenograft melanoma brain metastasis model, MBM variants had higher ST8SIA1 expression than their respective cutaneous melanoma variants. Elevated ST8SIA1 expression enhances levels of cell surface GD3, a phenotype that favors MBM development, hence associated with very poor prognosis. Functional assays demonstrated that ST8SIA1 overexpression enhanced cell proliferation and colony formation, whereby ST8SIA1 knockdown had opposite effects. Icaritin a plant‐derived phytoestrogen treatment significantly inhibited cell growth in high GD3‐positive MBM cells through targeting the canonical NFκB pathway. The study demonstrates GD3 phenotype associates with melanoma progression and poor outcome.

Natural product corynoline suppresses melanoma cell growth through inducing oxidative stress

Natural product corynoline is a unique isoquinoline alkaloid extracted from traditional Chinese medicine Corydalis bungeana Turcz, whereas its anticancer properties have not been investigated. In this study, we found that corynoline potently impairs the growth of melanoma cells, B16F10, and A375 in a concentration-dependent manner. Treatment of melanoma cells with corynoline results in G2 cell arrest accompanied by reduced cdc2 activation. Furthermore, corynoline triggers apoptosis of melanoma cells, which is associated with increased expression of Bax and cleaved caspase-3. Mechanistic study indicates that corynoline strongly induces reactive oxygen species (ROS) generation and subsequent DNA damage as evidenced by γ-H2AX accumulation. Notably, the effect of corynoline on melanoma cell cycle and apoptosis is abolished by a ROS scavenger N-acetyl cysteine (NAC), indicating a ROS-dependent mechanism. Finally, corynoline significantly inhibits in vivo B16F10 melanoma tumor growth accompanied by reduced expression of Ki-67 in tumor tissue. Taken together, our data suggest that corynoline suppresses melanoma cell growth in vitro and in vivo by inducing oxidative stress and represents a potential therapeutic agent for melanoma patients.

Fatty Acid Synthase Inhibitor G28 Shows Anticancer Activity in EGFR Tyrosine Kinase Inhibitor Resistant Lung Adenocarcinoma Models

Epidermal growth factor receptor (EGFR) tyrosine kinases inhibitors (TKIs) are effective therapies for non-small cell lung cancer (NSCLC) patients whose tumors harbor an EGFR activating mutation. However, this treatment is not curative due to primary and secondary resistance such as T790M mutation in exon 20. Recently, activation of transducer and activator of transcription 3 (STAT3) in NSCLC appeared as an alternative resistance mechanism allowing cancer cells to elude the EGFR signaling. Overexpression of fatty acid synthase (FASN), a multifunctional enzyme essential for endogenous lipogenesis, has been related to resistance and the regulation of the EGFR/Jak2/STAT signaling pathways. Using EGFR mutated (EGFRm) NSCLC sensitive and EGFR TKIs’ resistant models (Gefitinib Resistant, GR) we studied the role of the natural polyphenolic anti-FASN compound (−)-epigallocatechin-3-gallate (EGCG), and its derivative G28 to overcome EGFR TKIs’ resistance. We show that G28’s cytotoxicity is independent of TKIs’ resistance mechanisms displaying synergistic effects in combination with gefitinib and osimertinib in the resistant T790M negative (T790M−) model and showing a reduction of activated EGFR and STAT3 in T790M positive (T790M+) models. Our results provide the bases for further investigation of G28 in combination with TKIs to overcome the EGFR TKI resistance in NSCLC.

Molecular and cellular basis of the anticancer activity of the prenylated flavonoid icaritin in hepatocellular carcinoma

The prenylated flavonoid icaritin (ICT) is currently undergoing phase 3 clinical trial for the treatment of advanced hepatocellular carcinoma (HCC), based on a solid array of preclinical and clinical data. The antitumor activity originates from the capacity of the drug to modulate several signaling effectors in cancer cells, mainly the estrogen receptor splice variant ERα36, the transcription factors STAT3 and NFκB, and the chemokine receptor CXCR4. Recent studies have implicated additional components, including different microRNAs, the generation of reactive oxygen species and the targeting of sphingosine kinase-1. ICT also engages the RAGE-HMGB1 signaling route and modulates the apoptosis/autophagy crosstalk to promote its anticancer activity. In addition, ICT exerts profound changes on the tumor microenvironment to favor an immune-response. Collectively, these multiple biochemical and cellular characteristics confer to ICT a robust activity profile which can be exploited to treat HCC, as well as other cancers, including glioblastoma and onco-hematological diseases such as chronic myeloid leukemia. This review provides an update of the pharmacological properties of ICT and its metabolic characteristics. It also addresses the design of derivatives, including both natural products and synthetic molecules, such as SNG1153 also in clinical trial. The prenylated flavonoid ICT deserves attention as a multifunctional natural product potentially useful to improve the treatment of advanced hepatocellular carcinoma.

Chrysoeriol ameliorates TPA-induced acute skin inflammation in mice and inhibits NF-κB and STAT3 pathways

BACKGROUND

Chrysoeriol is a flavone found in diverse dietary and medicinal herbs such as Lonicerae Japonicae Flos (the dried flower bud or newly bloomed flower of Lonicera japonica Thunb.). These herbs are commonly used for treating inflammatory diseases. Herbal extracts containing chrysoeriol have been shown to have anti-inflammatory effects and inhibit nuclear factor-kappa B (NF-κB) signaling. Some of these extracts can inhibit signal transducers and activators of transcription 3 (STAT3) signaling in cancer cells.

PURPOSE

This study aimed to determine whether chrysoeriol has anti-inflammatory effects and whether NF-κB and STAT3 pathways are involved in the effects.

STUDY DESIGN AND METHODS

A TPA (12-O-tetradecanoylphorbol-13-acetate)-induced ear edema mouse model and LPS-stimulated RAW264.7 cells were used to evaluate the effects of chrysoeriol. Griess reagent was used to measure the production of nitric oxide (NO). Western blot and enzyme-linked immunosorbent assays were employed to detect protein levels. RT-qPCR analyses were used to detect mRNA levels. Haematoxylin and eosin (H&E) staining was employed to examine the pathological conditions in animal tissues.

RESULTS

In the mouse model, chrysoeriol ameliorated acute skin inflammation, evidenced by reduced ear thickness, ear weight and number of inflammatory cells in inflamed ear tissues. The compound lowered protein levels of phospho-p65 (Ser536), phospho-STAT3 (Tyr705), inducible nitric oxide synthases (iNOS), cyclooxygenase-2 (COX-2), interleukin 6 (IL-6), IL-1β and tumor necrosis factor α (TNF-α) in mouse swollen ears. In LPS-stimulated RAW264.7 cells, chrysoeriol also lowered levels of these proteins. In addition, chrysoeriol decreased the production of NO and prostaglandin E2; inhibited the phosphorylation of inhibitor of κB (Ser32), p65 (Ser536) and Janus kinase 2 (Tyr1007/1008); decreased nuclear localization of p50, p65 and STAT3; and down-regulated mRNA levels of pro-inflammatory cytokines IL-6, IL-1β and TNF-α that are transcriptionally regulated by NF-κB and STAT3 in the cell model.

CONCLUSION

We for the first time demonstrated that chrysoeriol ameliorates TPA-induced ear edema in mice, and that inhibition of JAK2/STAT3 and IκB/p65 NF-κB pathways are involved in the anti-inflammatory effects of chrysoeriol. This study provides chemical and pharmacological justifications for the use of chrysoeriol-containing herbs in treating inflammatory diseases, and provides pharmacological groundwork for developing chrysoeriol as a novel anti-inflammatory agent.

Potent Cytotoxic Natural Flavonoids: The Limits of Perspective

BACKGROUND

Besides the numerous biologic and pharmacologic functions in the human body that act as potent antioxidants, flavonoids (flavones, flavanones, flavonols, flavanols and isoflavones) are noted as cancer preventive or therapeutic agents.

METHODS

This review summarizes the published data using PubMed, Science Direct, and Scopus.

RESULTS

In this context, recognition and introduction of the most active cytotoxic flavonoids as promising agents for cancer therapy gives insight for further evaluations. However, there are some critical points that may affect the entering of flavonoids as active cytotoxic phytochemicals in the clinical phase. Issues such as the abundance of active species in nature, the methods of extraction and purification, solubility, pharmacokinetic profile, presence of the chiral moieties, method of synthesis, and structure modification may limit the entry of a selected compound for use in humans. Although plenty of basic evidence exists for cytotoxic/antitumor activity of the versatility of flavonoids for entry into clinical trials, the above-mentioned concerns must be considered.

CONCLUSION

This review is an effort to introduce cytotoxic natural flavonoids (IC50< 10 µM) that may have the potential to be used against various tumor cells. Also, active constituents, molecular mechanisms, and related clinical trials have been discussed as well as the limitations and challenges of using flavonoids in clinic.

Dual Inhibitors as a New Challenge for Cancer Multidrug Resistance Treatment

BACKGROUND

Dual-targeting in cancer treatment by a single drug is an unconventional approach in relation to drug combinations. The rationale for the development of dualtargeting agents is to overcome incomplete efficacy and drug resistance frequently present when applying individual targeting agents. Consequently, -a more favorable outcome of cancer treatment is expected with dual-targeting strategies.

METHODS

We reviewed the literature, concentrating on the association between clinically relevant and/or novel dual inhibitors with the potential to modulate multidrug resistant phenotype of cancer cells, particularly the activity of P-glycoprotein. A balanced analysis of content was performed to emphasize the most important findings and optimize the structure of this review.

RESULTS

Two-hundred and forty-five papers were included in the review. The introductory part was interpreted by 9 papers. Tyrosine kinase inhibitors' role in the inhibition of Pglycoprotein and chemosensitization was illustrated by 87 papers. The contribution of naturalbased compounds in overcoming multidrug resistance was reviewed using 92 papers, while specific dual inhibitors acting against microtubule assembling and/or topoisomerases were described with 55 papers. Eleven papers gave an insight into a novel and less explored approach with hybrid drugs. Their influence on P-glycoprotein and multidrug resistance was also evaluated.

CONCLUSION

These findings bring into focus rational anticancer strategies with dual-targeting agents. Most evaluated synthetic and natural drugs showed a great potential in chemosensitization. Further steps in this direction are needed for the optimization of anticancer treatment.

Functionalization of 9-thioxanthone at the 1-position: From arylamino derivatives to [1]benzo(thio)pyrano[4,3,2-de]benzothieno[2,3-b]quinolines of biological interest

Original 1-amino substituted thioxanthone derivatives were easily prepared from the bare heterocycle by a deprotometalation-iodolysis-copper-catalyzed CN bond formation sequence. This last reaction delivered mono- or/and diarylated products depending on the aniline involved. 1-Amino-9-thioxanthone was also prepared and reacted with 2-iodoheterocycles. Interestingly, while 1-(arylamino)-9-thioxanthones could be isolated, their subsequent cyclization was found to deliver original hexacyclic derivatives of helicoidal nature. Evaluation of their photophysical properties revealed high fluorescence in polar media, indicating potential applications for biological imaging. These compounds being able to inhibit PIM1 kinase, their putative binding mode was examined through molecular modeling experiments. Altogether, these results tend to suggest the discovery of a new family of fluorescent PIM inhibitors and pave the way for their future rational optimization.

Advances in the Regulatory Effects of Bioactive Peptides on Metabolic Signaling Pathways in Tumor Cells

Changes in cell metabolism are an important feature of tumors that has always been an intense topic of study, particularly in regard to whether metabolic disorders are a cause or an effect of tumorigenesis. Studies have shown that the processes underlying metabolic changes in tumors involve the activation of protooncogenes and the inactivation of cancer suppressor genes, as well as changes in metabolic flux in cells due to the abnormal activation of signaling pathways that modulate metabolic enzymes and/or metabolic regulatory proteins at several levels, including transfer and posttranslational modification. Thus, the repair of abnormal metabolic pathways via intervention in the relevant tumor metabolic pathways that impact specific targets has become a new method of cancer prevention and treatment. Bioactive peptides, which have many biological functions, could specifically target malignant tumors. Their interaction with signal transduction molecules involved in the development and transference of tumors could regulate the relevant cell metabolic pathways and inhibit the development of tumors and/or accelerate apoptosis in tumor cells. In this review, several aspects of tumor suppression using bioactive peptides will be discussed and summarized, including the regulation of the PI3K/AKT/mTOR, AMPK, and STST3 signaling pathways, the modulation of the TRAIL death receptor signaling pathway, the regulation of aerobic glycolysis by PKM2, and the modulation of the NF-кB signaling pathway, to aid in the search for better and more specific antineoplastic drugs in the form of bioactive peptides.

Icaritin inhibits glioblastoma cell viability and glycolysis by blocking the IL-6/Stat3 pathway

Glioblastoma (GBM) is a common and aggressive brain tumor that is associated with significant increase in glycolysis for energy production. Icaritin is a natural compound and exhibits anticancer activity in GBM. However, the effect of icaritin on glycolysis in GBM cells remains unclear. The aim of the current study was to investigate the effect of icaritin on glycolysis in GBM cells. The human GBM cell lines U87 and T98G were treated with icaritin or the inhibitor of Stat3 (S3I-201) in the presence or absence of recombinant human interleukin (IL)-6. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. The glycolysis was analyzed by detecting the glucose consumption and lactate production. The Western blot analysis was conducted to detect the expressions of hexokinase 2 (HK2), signal transducer and activator of transcription 3 (Stat3), p-Stat3, and B lymphoma Mo-MLV insertion region 1 (Bmi-1). Results showed that icaritin inhibited the viability of U87 and T98G cells in a dose-dependent manner. The decreased glucose consumption and lactate production, accompanied by reduced expressions of HK2, were found in both U87 and T98G cells. Icaritin inhibited the IL-6/Stat3 pathway, which is evidenced by the decreased expressions of p-Stat3 and Bmi-1. IL-6 treatment induced the phosphorylation of Stat3 and Bmi-1 expression, increased cell viability, as well as elevated glucose consumption, lactate production, and HK2 expression; however, the effects of IL-6 were attenuated by icaritin or S3I-201 treatment. In conclusion, icaritin exerted inhibitory effects on cell viability and glycolysis in GBM cells, which was mediated by the IL-6/Stat3 pathway.

Predominance of triple wild-type and IGF2R mutations in mucosal melanomas

BACKGROUND

Primary mucosal melanoma (MM) is a rare subtype of melanoma that arises from melanocytes in the mucosa. MM has not been well profiled for mutations and its etiology is not well understood, rendering current treatment strategies unsuccessful. Hence, we investigated mutational landscape for MM to understand its etiology and to clarify mutations that are potentially relevant for MM treatment.

METHODS

Forty one MM and 48 cutaneous melanoma (CM) tissues were profiled for mutations using targeted deep next-generation sequencing (NGS) for 89 cancer-related genes. A total of 997 mutations within exons were analyzed for their mutational spectrum and prevalence of mutation, and 685 non-synonymous variants were investigated to identify mutations in individual genes and pathways. PD-L1 expression from 21 MM and 18 CM were assessed by immunohistochemistry.

RESULTS

Mutational spectrum analysis revealed a lower frequency of UV-induced DNA damage in MM than in CM (p = 0.001), while tobacco exposure was indicated as a potential etiologic factor for MM. In accordance with low UV damage signatures, MM demonstrated an overall lower number of mutations compared to CM (6.5 mutations/Mb vs 14.8 mutations/Mb, p = 0.001), and less PD-L1 expression (p = 0.003). Compared to CM, which showed frequent mutations in known driver genes (BRAF 50.0%, NRAS 29.2%), MM displayed lower mutation frequencies (BRAF; 12.2%, p < 0.001, NRAS; 17.1%), and was significantly more enriched for triple wild-type (no mutations in BRAF, RAS, or NF1, 70.7% vs 25.0%, p < 0.001), IGF2R mutation (31.7% vs 6.3%, p = 0.002), and KIT mutation (9.8% vs 0%, p = 0.042). Of clinical relevance, presence of DCC mutations was significantly associated with poorer overall survival in MM (log-rank test, p = 0.02). Furthermore, mutational spectrum analysis distinguished primary anorectal MM from CM metastasized to the bowel (spectrum analysis p < 0.001, number of mutations p = 0.002).

CONCLUSIONS

These findings demonstrated a potential etiologic factor and driver mutation for MM and strongly suggested that MM initiation or progression involves distinct molecular-mechanisms from CM. This study also identified mutational signatures that are clinically relevant for MM treatment.

The sphingosine kinase-1/sphingosine-1-phosphate axis in cancer: Potential target for anticancer therapy

Sphingolipid metabolites, such as ceramide, sphingosine and sphingosine-1-phosphate (S1P), play many important roles in cellular activities. Ceramide and sphingosine inhibit cell proliferation and induce cell apoptosis while S1P has the opposite effect. Maintaining a metabolic balance of sphingolipids is essential for growth and development of cells. Sphingosine kinase (SPHK) is an important regulator for keeping this balance. It controls the level of S1P and plays important roles in proliferation, migration, and invasion of cancer cells and tumor angiogenesis. There are two isoenzymes of sphingosine kinase, SPHK1 and SPHK2. SPHK1 is ubiquitously expressed in most cancers where it promotes survival and proliferation, while SPHK2 is restricted to only certain tissues and its functions are not well characterized. SPHK1 is currently considered as a novel target for the treatment of cancers. Targeting SPHK1 would provide new strategies for cancer treatment and improve the prognosis of cancer patients. Here we review and summarize the current research findings on the SPHK1-S1P axis in cancer from many aspects including structure, expression, regulation, mechanism, and potential inhibitors.

Deciphering the metabolic role of AMPK in cancer multi-drug resistance

Multi-drug resistance (MDR) is a curious bottleneck in cancer research and chemotherapy, whereby some cells rapidly adapt to the tumor microenvironment via a myriad of heterogeneous metabolic activities. Despite being a major impediment to treatment, there is a silver lining: control over metabolic regulation could be an effective approach to overcome or correct resistance pathways. In this critical review, we comprehensively and carefully curated and analyzed large networks of previously identified proteins associated with metabolic adaptation in MDR. We employed data and text mining to study and categorize more than 600 studies in PubMed, with particular focus on AMPK, a central and fundamental modulator in the energy metabolism network that has been specifically implicated in cancer MDR pathways. We have identified one protein set of metabolic adaptations with 137 members closely related to cancer MDR processes, and a second protein set with 165 members derived from AMPK-based networks, with 28 proteins found at the intersection between the two sets. Furthermore, according to genomics analysis of the cancer genome atlas (TCGA) provisional data, the highest alteration frequency (80.0%) of the genes encoding the intersected proteins (28 proteins), ranked three cancer types with quite remarkable significance across 166 studies. The hierarchical relationships of the entire identified gene and protein networks indicate broad correlations in AMPK-mediated metabolic regulation pathways, which we use decipher and depict the metabolic roles of AMPK and demonstrate the potential of metabolic control for therapeutic intervention in MDR.

Icariin and icaritin recover UVB-induced photoaging by stimulating Nrf2/ARE and reducing AP-1 and NF-κB signaling pathways: a comparative study on UVB-irradiated human keratinocytes

Icariin (ICA) and icaritin (ICT) have potential to treat UVB-induced skin oxidative stress, inflammation and photoaging.

Inhibiting STAT3 signaling is involved in the anti-melanoma effects of a herbal formula comprising Sophorae Flos and Lonicerae Japonicae Flos

A herbal formula (SL) comprising Sophorae Flos and Lonicerae Japonicae Flos was traditionally used to treat melanoma. Constitutively active signal transducer and activator of transcription 3 (STAT3) has been proposed as a therapeutic target in melanoma. Here we investigated whether an ethanolic extract of SL (SLE) exerted anti-melanoma activities by inhibiting STAT3 signaling. B16F10 allograft model, A375 and B16F10 cells were employed to assess the in vivo and in vitro anti-melanoma activities of SLE. A375 cells stably expressing STAT3C, a constitutively active STAT3 mutant, were used to determine the role of STAT3 signaling in SLE’s anti-melanoma effects. Intragastric administration of SLE (1.2 g/kg) potently inhibited melanoma growth in mice and inhibited STAT3 phosphorylation in the tumors. In cultured cells, SLE dramatically reduced cell viability, induced apoptosis, suppressed migration and invasion, and restrained STAT3 activation and nuclear localization. STAT3C overexpression in A375 cells diminished SLE’s effects on cell viability, apoptosis and invasion. Collectively, SLE exerted potent anti-melanoma effects partially by inhibiting STAT3 signaling. This study provides pharmacological justification for the traditional use of this formula in treating melanoma, and suggests that SLE has the potential to be developed as a modern alternative and/or complimentary agent for melanoma treatment and prevention.

Sensitization of melanoma cells to alkylating agent-induced DNA damage and cell death via orchestrating oxidative stress and IKKβ inhibition

Nitrosourea represents one of the most active classes of chemotherapeutic alkylating agents for metastatic melanoma. Treatment with nitrosoureas caused severe systemic side effects which hamper its clinical use. Here, we provide pharmacological evidence that reactive oxygen species (ROS) induction and IKKβ inhibition cooperatively enhance nitrosourea-induced cytotoxicity in melanoma cells. We identified SC-514 as a ROS-inducing IKKβ inhibitor which enhanced the function of nitrosoureas. Elevated ROS level results in increased DNA crosslink efficiency triggered by nitrosoureas and IKKβ inhibition enhances DNA damage signals and sensitizes nitrosourea-induced cell death. Using xenograft mouse model, we confirm that ROS-inducing IKKβ inhibitor cooperates with nitrosourea to reduce tumor size and malignancy in vivo. Taken together, our results illustrate a new direction in nitrosourea treatment, and reveal that the combination of ROS-inducing IKKβ inhibitors with nitrosoureas can be potentially exploited for melanoma therapy.