Emerging potential of natural products for targeting mucins for therapy against inflammation and cancer

Bioactives Promiscuity of Mucin: Insight from Multi-Spectroscopic, Thermodynamic, and Molecular Dynamic Simulation Analyses

Mucosal drug delivery plays an increasing role in the clinical setting owing to mucin's advantageous biochemical and pharmacological properties. However, how this transport system recognizes different substrates remains unclear. In this study, we explore the mechanism of bioactive (quercetin and berberine) promiscuity of mucin using various spectroscopic techniques and molecular dynamics simulations. The UV-visible spectroscopy results and the decreased fluorescence intensity of mucin in the presence of the bioactive compounds via a static quenching mechanism confirmed ground-state complex formation between the bioactives and mucin. The binding constants (K_b) were evaluated at different temperatures to afford K_b values of ∼10⁴ Lmol^-1, demonstrating the moderate and reasonable affinity of the bioactives for mucin, yielding greater diffusion into the tissues. Thermodynamic analysis and molecular dynamics (MD) simulations demonstrate that mucin-bioactive complex formation occurs primarily because of electrostatic/ionic interactions, while hydrophobic interactions were also crucial in stabilizing the complex. Far-UV circular dichroism spectroscopy showed that bioactive binding induced secondary structural changes in mucin. Sitemap and MD simulation indicated the principal binding site of mucin for the bioactives. This study also provides insight into the bioactives promiscuity of mucin in the presence of a crowded environment, which is relevant to the biological activity of mucin in vivo. An in vitro drug release study revealed that crowding assisted drug release in an enhanced burst manner compared with that in a dilute buffer system. This work thus provides fresh insight into drug absorption and distribution in the native cellular environment and helps direct new drug design and use in pharmaceutical and pharmacological fields.

Treatment Strategies for KRAS-Mutated Non-Small-Cell Lung Cancer

Activating mutations in KRAS are highly prevalent in solid tumours and are frequently found in 35% of lung, 45% of colorectal, and up to 90% of pancreatic cancers. Mutated KRAS is a prognostic factor for disease-free survival (DFS) and overall survival (OS) in NSCLC and is associated with a more aggressive clinical phenotype, highlighting the need for KRAS-targeted therapy. Once considered undruggable due to its smooth shallow surface, a breakthrough showed that the activated G12C-mutated KRAS isozyme can be directly inhibited via a newly identified switch II pocket. This discovery led to the development of a new class of selective small-molecule inhibitors against the KRAS G12C isoform. Sotorasib and adagrasib are approved in locally advanced or metastatic NSCLC patients who have received at least one prior systemic therapy. Currently, there are at least twelve KRAS G12C inhibitors being tested in clinical trials, either as a single agent or in combination. In this study, KRAS mutation prevalence, subtypes, rates of occurrence in treatment-resistant invasive mucinous adenocarcinomas (IMAs), and novel drug delivery options are reviewed. Additionally, the current status of KRAS inhibitors, multiple resistance mechanisms that limit efficacy, and their use in combination treatment strategies and novel multitargeted approaches in NSCLC are discussed.

A Review on Annona muricata and Its Anticancer Activity

Simple Summary

Cancer is becoming more prevalent, raising concerns regarding how well current treatments work. Cancer patients frequently seek alternative treatments to surgery, chemotherapy, and radiation therapy. The use of medicinal plants in both preventative and curative healthcare is widely acknowledged. The compounds of graviola have shown promise as possible cancer-fighting agents and could be used to treat cancer. This review discusses bioactive metabolites present in graviola and their role in affecting the growth and death of different cancer cell types and the molecular mechanism of how it works to downregulate anti-apoptotic genes and the genes involved in pro-cancer metabolic pathways. Also, it reviews how simultaneously increasing the expression of genes promotes apoptosis and causes cancer cells to die so that the active phytochemicals found in graviola could be used as a promising anti-cancer agent.

Abstract

The ongoing rise in the number of cancer cases raises concerns regarding the efficacy of the various treatment methods that are currently available. Consequently, patients are looking for alternatives to traditional cancer treatments such as surgery, chemotherapy, and radiotherapy as a replacement. Medicinal plants are universally acknowledged as the cornerstone of preventative medicine and therapeutic practices. Annona muricata is a member of the family Annonaceae and is familiar for its medicinal properties. A. muricata has been identified to have promising compounds that could potentially be utilized for the treatment of cancer. The most prevalent phytochemical components identified and isolated from this plant are alkaloids, phenols, and acetogenins. This review focuses on the role of A. muricata extract against various types of cancer, modulation of cellular proliferation and necrosis, and bioactive metabolites responsible for various pharmacological activities along with their ethnomedicinal uses. Additionally, this review highlights the molecular mechanism of the role of A. muricata extract in downregulating anti-apoptotic and several genes involved in the pro-cancer metabolic pathways and decreasing the expression of proteins involved in cell invasion and metastasis while upregulating proapoptotic genes and genes involved in the destruction of cancer cells. Therefore, the active phytochemicals identified in A. muricata have the potential to be employed as a promising anti-cancer agent.

The ethnomedicinal and functional uses, phytochemical and pharmacology of compounds from Ardisia species: An updated review

Medicinal plants are considered to be a critical source of novel compounds and pharmacophores. The genus Ardisia, consisting of approximately 500 species, is the largest genus in the Myrsinaceae family. Ardisia species are widely distributed throughout tropical and subtropical regions of the world and have been used for the treatment of cancer, hypertension, irregular menstruation, gonorrhea, diarrhea and postnatal syndromes, among others. Phytochemical studies of Ardisia species have resulted in the isolation and identification of 111 compounds, including triterpenoid saponins, quinones, phenols, coumarins, cyclic depsipepetide and flavonoids. Crude extracts and isolates from Ardisia have been reported to have in vitro and in vivo efficacies, including but not limited to anticancer, antiinflammatory, antimicrobial, antioxidant, antithrombotic and antidiabetic, antitubercular compounds. This review focuses on the medical and functional uses, phytochemical profile and pharmacological efficacies of Ardisia species over the past 15 years. This review will provide information indicating that Ardisia species represent an invaluable source of potential therapeutic compounds.

MicroRNAs as Therapeutic Targets for Anticancer Drugs in Lung Cancer Therapy

MicroRNAs (miRNAs) are short, non-coding RNA molecules that regulate gene expression by translational repression or deregulation of messenger RNAs. Accumulating evidence suggests that miRNAs play various roles in the development and progression of lung cancers. Although their precise roles in targeted cancer therapy are currently unclear, miRNAs have been shown to affect the sensitivity of tumors to anticancer drugs. A large number of recent studies have demonstrated that some anticancer drugs exerted antitumor activities by affecting the expression of miRNAs and their targeted genes. These studies have elucidated the specific biological mechanism of drugs in tumor suppression, which provides a new idea or basis for their clinical application. In this review, we summarized the therapeutic mechanisms of drugs in lung cancer therapy through their effects on miRNAs and their targeted genes, which highlights the roles of miRNAs as targets in lung cancer therapy.

Overexpression of Mucin 1 Suppresses the Therapeutical Efficacy of Disulfiram against Canine Mammary Tumor

Simple Summary

Canine mammary tumor is one of the most prevalent canine tumor types in China. Clinical studies showed that the high expression of mucin 1 (MUC1) protein is significantly associated with the malignancy and poor prognosis of canine mammary tumor. Therefore, it is worthwhile to investigate the expression of mucin 1 in developing treatments against canine mammary tumors. In the present study, it is demonstrated that disulfiram, an approved medication in treating human alcoholism, also has inhibitory effects on the growth of canine mammary tumor cells both in vitro and in vivo. With the overexpression of MUC1, the inhibitory effects of disulfiram decrease accordingly. Moreover, disulfiram is shown to inhibit phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (Akt) signaling transduction, which is attenuated by MUC1 overexpression. Overall, these results indicate that the expression level of MUC1 is detrimental to determining the anti-tumor activity of disulfiram. Further consideration should be given when treating the canine mammary tumor with disulfiram or other PI3K/Akt inhibitors.

Abstract

Mucin 1 (MUC1), a transmembrane protein, is closely associated with the malignancy and metastasis of canine mammary tumors; however, the role of overexpressed MUC1 in the development of cancer cells and response to drug treatment remains unclear. To address this question, we developed a new canine mammary tumor cell line, CIPp-MUC1, with an elevated expression level of MUC1. In vitro studies showed that CIPp-MUC1 cells are superior in proliferation and migration than wild-type control, which was associated with the upregulation of PI3K, p-Akt, mTOR, Bcl-2. In addition, overexpression of MUC1 in CIPp-MUC1 cells inhibited the suppressing activity of disulfiram on the growth and metastasis of tumor cells, as well as inhibiting the pro-apoptotic effect of disulfiram. In vivo studies, on the other side, showed more rapid tumor growth and stronger resistance to disulfiram treatment in CIPp-MUC1 xenograft mice than in wild-type control. In conclusion, our study demonstrated the importance of MUC1 in affecting the therapeutical efficiency of disulfiram against canine mammary tumors, indicating that the expression level of MUC1 should be considered for clinical use of disulfiram or other drugs targeting PI3K/Akt pathway.

Mucin mutations and aberrant expression are associated with the pathogenesis of immune thrombocytopenia

PURPOSE

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease of unknown aetiology. In this study, we aimed to identify the mutations and aberrant expression of mucins associated with ITP pathogenesis.

METHODS

First, we investigated the DNA mutation profile of bone marrow samples from patients with ITP (n = 20) by using next-generation sequencing (NGS). In addition, MUC3A, MUC5B and MUC6 were mutated in all patients with ITP. ELISA (enzyme-linked immunoassay) was used to measure MUC3A, MUC5B and MUC6 levels in the plasma of bone marrow fluid mononuclear cells (BMMCs) and peripheral blood mononuclear cells (PBMCs). Real-time quantitative PCR was used to study the mRNA expression levels of MUC3A, MUC5B and MUC6 in BMMCs and PBMCs.

RESULTS

The results indicated that there were 3998 missense mutations involving 2269 genes in more than 10 individuals. MUC3A levels were not significantly different among the three groups, whereas MUC5B and MUC6 expression were significantly down-regulated in patients with ITP compared with healthy controls. In addition, serum MUC5B and MUC6 levels were significantly higher in patients with ITP in clinical remission than in patients with active ITP.

CONCLUSIONS

Taken together, these results suggest that genetic alterations and the aberrant serum expression of mucins might be involved in the pathogenesis of ITP.

The "nano to micro" transition of hydrophobic curcumin crystals leading to in situ adjuvant depots for Au-liposome nanoparticle mediated enhanced photothermal therapy

Photothermal therapy (PTT) is emerging as a promising treatment for skin cancer. Plasmon-resonant gold-coated liposome nanoparticles (Au Lipos NPs) specifically absorb Near Infra-Red (NIR) light resulting in localized hyperthermia (PTT). In the current study, curcumin (a hydrophobic anticancer agent) was entrapped in Au Lipos NPs as nanocrystals to act as an adjuvant for the PTT of melanoma. NIR light irradiation on Au Lipos Cur NPs triggered the release of curcumin nanocrystals which coalesce to form curcumin microcrystals (CMCs). An in situ"nano to micro" transition in the crystal state of curcumin was observed. This in situ transition leads to the formation of CMCs. These CMCs exhibited sustained release of curcumin for a prolonged duration (>10 days). The localized availability of curcumin aids in enhancing PTT by inhibiting the growth and mobility of cancer cells that escape PTT. In the in vitro modified scratch assay, the Au Lipos Cur NP + Laser group showed >1.5 fold enhanced therapeutic coverage when compared with the Au Lipos NP + Laser group. In vivo PTT studies performed in a B16 tumor model using Au Lipos Cur NPs showed a significant reduction of the tumor volume along with the localized release of curcumin in the tumor environment. It was observed that the localized release of curcumin enables an immediate adjuvant effect resulting in the enhancement of PTT.

Effects of chlorogenic acid, epicatechin gallate, and quercetin on mucin expression and secretion in the Caco-2/HT29-MTX cell model

Mucins are a family of large glycoproteins that represent the major structural components of the mucus and are encoded by 20 different mucin genes. Mucin expression can be modulated by different stimuli. In this study, we analyzed four mucins (MUC2, MUC3, MUC13, and MUC17) in coculture of Caco-2/HT29-MTX cells to demonstrate the variation in gene expression in the presence of antioxidant compounds like chlorogenic acid, epicatechin gallate, and quercetin (apple, tea, and coffee polyphenols, respectively). coculture of Caco-2/HT29-MTX cells was treated with polyphenols, and the expression of four mucins was determined by reverse-transcriptase PCR. In addition, the secretion levels of MUC2 were established by enzyme-linked immunoassay (ELISA) analysis. The results showed that each polyphenol compound induces different expression patterns of the mucin genes. Statistically significant up-regulation of MUC17 was observed following incubation with epicatechin gallate and quercetin. ELISA results did not prove any significant differences in protein levels of MUC2 after treatment by the polyphenol compounds. The polyphenols considered in this study may influence mucin secretion and act on diverse salivary substrates to change the barrier properties of mucins for mucus secretion in different ways.

Ramifications of secreted mucin MUC5AC in malignant journey: a holistic view

Heavily glycosylated secreted mucin MUC5AC, by the virtue of its cysteine-rich repeats, can form inter- and intramolecular disulfide linkages resulting in complex polymers, which in turn craft the framework of the polymeric mucus gel on epithelial cell surfaces. MUC5AC is a molecule with versatile functional implications including barrier functions to epithelial cells, host-pathogen interaction, immune cell attraction to sites of premalignant or malignant lesions and tumor progression in a context-dependent manner. Differential expression, glycosylation and localization of MUC5AC have been associated with a plethora of benign and malignant pathologies. In this era of robust technologies, overexpression strategies and genetically engineered mouse models, MUC5AC is emerging as a potential diagnostic, prognostic and therapeutic target for various malignancies. Considering the clinical relevance of MUC5AC, this review holistically encompasses its genomic organization, domain structure, glycosylation patterns, regulation, functional and molecular connotation from benign to malignant pathologies. Furthermore, we have here explored the incipient and significant experimental tools that are being developed to study this structurally complex and evolutionary conserved gel-forming mucin.

Effect of Morinda citrifolia and Annona muricata on Erhlich Tumor Cells in Swiss Albino Mice and In Vitro Fibroblast Cells

Morinda citrifolia (MC) and Annona muricata (AM) are popularly used for the treatment of several diseases, including cancer. Our objective was to evaluate the effects of the juice of the MC fruit, and the ethanolic extract of AM leaves on Erhlich tumor cells, in mice and in vitro fibroblastic cells. The animals were divided into G1 and G2: controls; G3: treated with AM, and G4 juice: treated with MC. The animals were subjected to intraperitoneal inoculation of 10³ tumor cells and then treated with the plants. G1 and G2 received a saline solution. Cells were grown in RPMI 1640 medium, supplemented with 10% fetal bovine serum, and maintained at 37°C in 5% CO₂ atmosphere. After growth, the cells were trypsinized and incubated again. Subsequently, serial dilution of extracts and juice was performed and incubated again for 48 h. We evaluated the ascites growth, the survival rate, and cytotoxicity in fibroblast cells. AM and MC did not interfere in the ascites pattern. MC, but not AM showed significance in the survival rate. Both AM and MC produced cytotoxicity activity in T3T cells. Despite advances in medicine, cancer is still one of the leading causes of death in the world and traditional medications are not always effective. The use of MC may bring beneficial effects to patients since they interfere with different mechanisms of action during carcinogenesis. However, we suggest that further investigations should be performed.

Mucin 2 (MUC2) modulates the aggressiveness of breast cancer

PURPOSE

Tumors that secrete large volumes of mucus are chemotherapy resistant, however, mechanisms underlying this resistance are unknown. One protein highly expressed in mucin secreting breast cancers is the secreted mucin, Mucin 2 (MUC2). While MUC2 is expressed in some breast cancers it is absent in normal breast tissue, implicating it in breast cancer. However, the effects of MUC2 on breast cancer are largely unknown. This study examined the role of MUC2 in modulating breast cancer proliferation, response to chemotherapy and metastasis.

METHODS

Using patient derived xenografts we developed two novel cell lines, called BCK4 and PT12, which express high levels of MUC2. To modulate MUC2 levels, BCK4 and PT12 cells were engineered to express shRNA targeted to MUC2 (shMUC2, low MUC2) or a non-targeting control (shCONT, high MUC2) and proliferation and apoptosis were measured in vitro and in vivo. BCK4 cells with shCONT or shMUC2 were labeled with GFP-luciferase and examined in an experimental metastasis model; disease burden and site specific dissemination were monitored by intravital imaging and fluorescence guided dissection, respectively.

RESULTS

Proliferation decreased in BCK4 and PT12 shMUC2 cells versus control cells both in vitro and in vivo. Chemotherapy induced minimal apoptosis in control cells expressing high MUC2 but increased apoptosis in shMUC2 cells containing low MUC2. An experimental metastasis model showed disease burden decreased when breast cancer cells contained low versus high MUC2. Treatment with Epidermal Growth Factor (EGF) increased MUC2 expression in BCK4 cells; this induction was abolished by the EGF-receptor inhibitor, Erlotinib.

CONCLUSIONS

MUC2 plays an important role in mediating proliferation, apoptosis and metastasis of breast cancer cells. MUC2 may be important in guiding treatment and predicting outcomes in breast cancer patients.

Mucoadhesive role of tamarind xyloglucan on inflammation attenuates ulcerative colitis

Tamarind xyloglucan (TXG) is edible, bioavailable and mucoadhesive polysaccharide. The aim of this study was (i) to investigate molecular docking studies on the interaction of TXG to MUC1 and cytokine receptors and (ii) to assess the mucoadhesive role of TXG in UC. In vivo study: C57Bl6 mice were administered with DSS 3% (w/v) in drinking water; TXG 100 or 300 mg/kg/day was given orally for 7 days simultaneously. TXG consistently binds to MUC1 and cytokine receptors in molecular docking studies. TXG decreased the expression of MUC1 and MUC2. The mucoadhesive ability of TXG decreased IL-1β and IL-6 levels. Furthermore, TXG decreased the expression of TLR4, MyD88, I-κB and NF-κB thereby attenuating inflammation via TLR4/NF-κB signaling pathway. TXG mucoadhesion to MUC1 played a pivotal role in attenuating inflammation. To conclude, the mucoadhesive role of TXG is important in the attenuation of inflammation and healing of UC.

Umbelliprenin shows antitumor, antiangiogenesis, antimetastatic, anti-inflammatory, and immunostimulatory activities in 4T1 tumor-bearing Balb/c mice

Umbelliprenin (UMB) has shown various pharmacological properties in vitro. We investigated the antineoplastic and immunostimulatory effects of UMB in 4T1 mammary-tumor-bearing mice. Two-hundred microliter of UMB (12.5 mg/ml) was intraperitoneally administrated to healthy and tumor-bearing female Balb/c mice for a period of 18 days. Data was analyzed using GraphPad Prism 5 software for Windows (version 5, La Jolla, CA). UMB caused a significant decrease in tumor size (P < 0.01). Serum interferon gamma (IFNγ) was augmented in both healthy and tumor-bearing animals (P < 0.01), and IL-4 declined in healthy animals (P < 0.01) treated with UMB. Expressions of Ki-67, VEGF, CD31, MMP2, MMP9, VCAM1, and NF-κB were significantly decreased in tumors from UMB-treated animals (P < 0.001), whereas E-Cadherin and TNFR1 expressions were markedly increased (P < 0.001). The rates of liver and lung metastases in UMB-administrated animals were smaller compared to the control. UMB can potently inhibit tumor growth, angiogenesis, metastasis, and inflammation and potentiate an antitumor immune response in vivo. However, further investigations are required to evaluate the UMB mechanisms of action in cancerous cells.

Emerging therapeutic potential of graviola and its constituents in cancers

Cancer remains a leading cause of death in the USA and around the world. Although the current synthetic inhibitors used in targeted therapies have improved patient prognosis, toxicity and development of resistance to these agents remain a challenge. Plant-derived natural products and their derivatives have historically been used to treat various diseases, including cancer. Several leading chemotherapeutic agents are directly or indirectly based on botanical natural products. Beyond these important drugs, however, a number of crude herbal or botanical preparations have also shown promising utility for cancer and other disorders. One such natural resource is derived from certain plants of the family Annonaceae, which are widely distributed in tropical and subtropical regions. Among the best known of these is Annona muricata, also known as soursop, graviola or guanabana. Extracts from the fruit, bark, seeds, roots and leaves of graviola, along with several other Annonaceous species, have been extensively investigated for anticancer, anti-inflammatory and antioxidant properties. Phytochemical studies have identified the acetogenins, a class of bioactive polyketide-derived constituents, from the extracts of Annonaceous species, and dozens of these compounds are present in different parts of graviola. This review summarizes current literature on the therapeutic potential and molecular mechanism of these constituents from A.muricata against cancer and many non-malignant diseases. Based on available data, there is good evidence that these long-used plants could have both chemopreventive and therapeutic potential. Appropriate attention to safety studies will be important to assess their effectiveness on various diseases caused or promoted by inflammation.

Toll like receptors TLR1/2, TLR6 and MUC5B as binding interaction partners with cytostatic proline rich polypeptide 1 in human chondrosarcoma

Metastatic chondrosarcoma is a bone malignancy not responsive to conventional therapies; new approaches and therapies are urgently needed. We have previously reported that mTORC1 inhibitor, antitumorigenic cytostatic proline rich polypeptide 1 (PRP-1), galarmin caused a significant upregulation of tumor suppressors including TET1/2 and SOCS3 (known to be involved in inflammatory processes), downregulation of oncoproteins and embryonic stem cell marker miR-302C and its targets Nanog, c-Myc and Bmi-1 in human chondrosarcoma. To understand better the mechanism of PRP-1 action it was very important to identify the receptor it binds to. Nuclear pathway receptor and GPCR assays indicated that PRP-1 receptors are not G protein coupled, neither do they belong to family of nuclear or orphan receptors. In the present study, we have demonstrated that PRP-1 binding interacting partners belong to innate immunity pattern recognition toll like receptors TLR1/2 and TLR6 and gel forming secreted mucin MUC5B. MUC5B was identified as PRP-1 receptor in human chondrosarcoma JJ012 cell line using Ligand-receptor capture technology. Toll like receptors TLR1/2 and TLR6 were identified as binding interaction partners with PRP-1 by western blot analysis in human chondrosarcoma JJ012 cell line lysates. Immunocytochemistry experiments confirmed the finding and indicated the localization of PRP-1 receptors in the tumor nucleus predominantly. TLR1/2, TLR6 and MUC5B were downregulated in human chondrosarcoma and upregulated in dose-response manner upon PRP-1 treatment. Experimental data indicated that in this cellular context the mentioned receptors had tumor suppressive function.

MUC4 mucin- a therapeutic target for pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic cancer (PC) is characterized by mucin overexpression. MUC4 is the most differentially overexpressed membrane-bound mucin that plays a functional role in disease progression and therapy resistance. Area covered: We describe the clinicopathological significance of MUC4, summarize mechanisms contributing to its deregulated expression, review preclinical studies aimed at inhibiting MUC4, and discuss how MUC4 overexpression provides opportunities for developing targeted therapies. Finally, we discuss the challenges for developing MUC4-based therapeutics, and identify areas where efforts should be directed to effectively exploit MUC4 as a therapeutic target for PC. Expert opinion: Studies demonstrating that abrogation of MUC4 expression reduces proliferation and metastasis of PC cells and enhances sensitivity to therapeutic agents affirm its utility as a therapeutic target. Emerging evidence also supports the suitability of MUC4 as a potential immunotherapy target. However, these studies have been limited to in vitro, ex vivo or in vivo approaches using xenograft tumors in immunodeficient murine models. For translational relevance, MUC4-targeted therapies should be evaluated in murine models with intact immune system and accurate tumor microenvironment. Additionally, future studies evaluating MUC4 as a target for immunotherapy must entail characterization of immune response in PC patients and investigate its association with immunosuppression and survival.

Selectivity of major isoquinoline alkaloids from Chelidonium majus towards telomeric G-quadruplex: A study using a transition-FRET (t-FRET) assay

BACKGROUND

Natural bioproducts are invaluable resources in drug discovery. Isoquinoline alkaloids of Chelidonium majus constitute a structurally diverse family of natural products that are of great interest, one of them being their selectivity for human telomeric G-quadruplex structure and telomerase inhibition.

METHODS

The study focuses on the mechanism of telomerase inhibition by stabilization of telomeric G-quadruplex structures by berberine, chelerythrine, chelidonine, sanguinarine and papaverine. Telomerase activity and mRNA levels of hTERT were estimated using quantitative telomere repeat amplification protocol (q-TRAP) and qPCR, in MCF-7 cells treated with different groups of alkaloids. The selectivity of the main isoquinoline alkaloids of Chelidonium majus towards telomeric G-quadruplex forming sequences were explored using a sensitive modified thermal FRET-melting measurement in the presence of the complementary oligonucleotide CT22. We assessed and monitored G-quadruplex topologies using circular dichroism (CD) methods, and compared spectra to previously well-characterized motifs, either alone or in the presence of the alkaloids. Molecular modeling was performed to rationalize ligand binding to the G-quadruplex structure.

RESULTS

The results highlight strong inhibitory effects of chelerythrine, sanguinarine and berberine on telomerase activity, most likely through substrate sequestration. These isoquinoline alkaloids interacted strongly with telomeric sequence G-quadruplex. In comparison, chelidonine and papaverine had no significant interaction with the telomeric quadruplex, while they strongly inhibited telomerase at transcription level of hTERT. Altogether, all of the studied alkaloids showed various levels and mechanisms of telomerase inhibition.

CONCLUSIONS

We report on a comparative study of anti-telomerase activity of the isoquinoline alkaloids of Chelidonium majus. Chelerythrine was most effective in inhibiting telomerase activity by substrate sequesteration through G-quadruplex stabilization.

GENERAL SIGNIFICANCE

Understanding structural and molecular mechanisms of anti-cancer agents can help in developing new and more potent drugs with fewer side effects. Isoquinolines are the most biologically active agents from Chelidonium majus, which have shown to be telomeric G-quadruplex stabilizers and potent telomerase inhibitors.

Polymorphisms in microRNA binding sites of mucin genes as predictors of clinical outcome in colorectal cancer patients

Polymorphisms in microRNA (miRNA) binding sites may affect miRNA/target gene interaction, resulting in differential mRNA/protein expression and susceptibility to common diseases. Mucins have been identified as markers of adverse prognosis. We hypothesized that genetic variations in miRNA binding sites located in mucin genes may modulate signaling response and the maintenance of genomic stability ultimately affecting cancer susceptibility, efficacy of chemotherapy and survival. In this study, we analyzed the association of single nucleotide polymorphisms in predicted miRNA target sites (miRSNPs) of mucin genes with colorectal cancer (CRC) risk and clinical outcome. Thirteen miRSNPs in 9 genes were assessed in 1111 cases and 1469 controls. No strongly significant associations were observed in the case-control study. Patients carrying the CC genotype of rs886403 in MUC21 displayed a shorter survival and higher recurrence risk when compared with TT carriers [overall survival (OS): hazard ratios (HR) 1.69; 95% confidence intervals (CI) 1.13-2.46; P = 0.01 and event-free survival (EFS): HR 1.99; 95% CI 1.38-2.84; P = 0.0002, respectively]. The observed associations were more striking after stratification for tumor site (in patients with colon cancer, OS: HR 2.63; 95% CI 1.69-4.10; P < 0.0001 and EFS: HR 2.65; 95% CI 1.72-4.07; P < 0.0001). In contrast, rectal cancer cases carrying the CC genotype of rs4729655 in MUC17 displayed a longer survival (OS: HR 0.27; 95% CI 0.14-0.54; P = 0.0002) than those with the most common genotype. To our knowledge, this is the first study investigating miRSNPs potentially affecting miRNA binding to mucin genes and revealing their impact on CRC susceptibility or patient's survival.

Natural small molecule FMHM inhibits lipopolysaccharide-induced inflammatory response by promoting TRAF6 degradation via K48-linked polyubiquitination

TNF receptor-associated factor 6 (TRAF6) is a key hub protein involved in Toll-like receptor-dependent inflammatory signaling pathway, and it recruits additional proteins to form multiprotein complexes capable of activating downstream NF-κB inflammatory signaling pathway. Ubiquitin-proteasome system (UPS) plays a crucial role in various protein degradations, such as TRAF6, leading to inhibitory effects on inflammatory response and immunologic function. However, whether ubiquitination-dependent TRAF6 degradation can be used as a novel anti-inflammatory drug target still remains to be explored. FMHM, a bioactive natural small molecule compound extracted from Chinese herbal medicine Radix Polygalae, suppressed acute inflammatory response by targeting ubiquitin protein and inducing UPS-dependent TRAF6 degradation mechanism. It was found that FMHM targeted ubiquitin protein via Lys48 site directly induced Lys48 residue-linked polyubiquitination. This promoted Lys48 residue-linked polyubiquitin chain formation on TRAF6, resulting in increased TRAF6 degradation via UPS and inactivation of downstream NF-κB inflammatory pathway. Consequently, FMHM down-regulated inflammatory mediator levels in circulation, protected multiple organs against inflammatory injury in vivo, and prolong the survival of endotoxemia mouse models. Therefore, FMHM can serve as a novel lead compound for the development of TRAF6 scavenging agent via ubiquitination-dependent mode, which represents a promising strategy for treating inflammatory diseases.

[Effect of Chemical Prevention Drugs-based MicroRNAs and Their Target Genes on Tumor Inhibition]

Chemopreventive drugs including natural chemopreventive drugs and synthetic chemopreventive drugs, it not only can prevent cancer, can also play a role in tumor treatment. MicroRNAs (miRNAs) is a kind of short chains of non-coding RNA, regulating the expression of many genes through the way of degradation of mRNA or inhibitting mRNA translation. In recent years, more and more studies have shown that chemopreventive drugs through influence the expression of miRNAs and their target genes play a role in the prevention and treatment in a variety of tumors, and chemopreventive drugs on the experimental study of miRNAs and their target genes in tumor have demonstrated a good safety and efficacy. Effect on chemopreventive drugs-based microRNAs and their target genes into cancer cells will be expected as a new starting point for cancer research. The thesis expounds and analyzes between the natural chemopreventive drugs and synthetic chemopreventive drugs and miRNAs and their target genes in tumor research progress.