c-Myc target genes involved in cell growth, apoptosis, and metabolism

Myc plays an important role in Drosophila P-M hybrid dysgenesis to eliminate germline cells with genetic damage

Genetic damage in the germline induced by P-element mobilization causes a syndrome known as P-M hybrid dysgenesis (HD), which manifests as elevated mutation frequency and loss of germline cells. In this study, we found that Myc plays an important role in eliminating germline cells in the context of HD. P-element mobilization resulted in downregulation of Myc expression in the germline. Myc knockdown caused germline elimination; conversely, Myc overexpression rescued the germline loss caused by P-element mobilization. Moreover, restoration of fertility by Myc resulted in the production of gametes with elevated mutation frequency and reduced ability to undergo development. Our results demonstrate that Myc downregulation mediates elimination of germline cells with accumulated genetic damage, and that failure to remove these cells results in increased production of aberrant gametes. Therefore, we propose that elimination of germline cells mediated by Myc downregulation is a quality control mechanism that maintains the genomic integrity of the germline.

A drug-like imidazole-benzothiazole conjugate inhibits malignant melanoma by stabilizing the c-MYC G-quadruplex

Aberrant expression of c-MYC oncogene is significantly associated with the occurrence and development of malignant melanoma. Suppression of the c-MYC transcriptional activity accordingly provides a new idea for treating melanoma. Notably, stabilizing the G-quadruplex (G4) structure in the promoter is proved to be effective in downregulating c-MYC transcription. In this work, we developed a drug-like imidazole-benzothiazole conjugate called IZTZ-1, which was confirmed to preferentially stabilize the promoter G4 and thus lower c-MYC expression. Intracellular assays revealed that IZTZ-1 induced cell cycle arrest, apoptosis, thereby inhibiting cell proliferation. Furthermore, IZTZ-1 was demonstrated to effectively inhibit tumor growth in a melanoma mouse model. Consequently, IZTZ-1 showed good potential in the treatment of melanoma. This study provides an alternative strategy to treat melanoma by targeting the c-MYC G4.

Discovery of WD Repeat-Containing Protein 5 (WDR5)-MYC Inhibitors Using Fragment-Based Methods and Structure-Based Design

The frequent deregulation of MYC and its elevated expression via multiple mechanisms drives cells to a tumorigenic state. Indeed, MYC is overexpressed in up to ∼50% of human cancers and is considered a highly validated anticancer target. Recently, we discovered that WD repeat-containing protein 5 (WDR5) binds to MYC and is a critical cofactor required for the recruitment of MYC to its target genes and reported the first small molecule inhibitors of the WDR5-MYC interaction using structure-based design. These compounds display high binding affinity, but have poor physicochemical properties and are hence not suitable for in vivo studies. Herein, we conducted an NMR-based fragment screening to identify additional chemical matter and, using a structure-based approach, we merged a fragment hit with the previously reported sulfonamide series. Compounds in this series can disrupt the WDR5-MYC interaction in cells, and as a consequence, we observed a reduction of MYC localization to chromatin.

Blocking Myc to Treat Cancer: Reflecting on Two Decades of Omomyc

First designed and published in 1998 as a laboratory tool to study Myc perturbation, Omomyc has come a long way in the past 22 years. This dominant negative has contributed to our understanding of Myc biology when expressed, first, in normal and cancer cells, and later in genetically-engineered mice, and has shown remarkable anti-cancer properties in a wide range of tumor types. The recently described therapeutic effect of purified Omomyc mini-protein—following the surprising discovery of its cell-penetrating capacity—constitutes a paradigm shift. Now, much more than a proof of concept, the most characterized Myc inhibitor to date is advancing in its drug development pipeline, pushing Myc inhibition into the clinic.

Multi-Omics Analysis Identifies MGA as a Negative Regulator of the MYC Pathway in Lung Adenocarcinoma

Genomic analysis of lung adenocarcinomas has revealed that the MGA gene, which encodes a heterodimeric partner of the MYC-interacting protein MAX, is significantly mutated or deleted in lung adenocarcinomas. Most of the mutations are loss of function for MGA, suggesting that MGA may act as a tumor suppressor. Here, we characterize both the molecular and cellular role of MGA in lung adenocarcinomas and illustrate its functional relevance in the MYC pathway. Although MGA and MYC interact with the same binding partner, MAX, and recognize the same E-box DNA motif, we show that the molecular function of MGA appears to be antagonistic to that of MYC. Using mass spectrometry-based affinity proteomics, we demonstrate that MGA interacts with a noncanonical PCGF6-PRC1 complex containing MAX and E2F6 that is involved in gene repression, while MYC is not part of this MGA complex, in agreement with previous studies describing the interactomes of E2F6 and PCGF6. Chromatin immunoprecipitation-sequencing and RNA sequencing assays show that MGA binds to and represses genes that are bound and activated by MYC. In addition, we show that, as opposed to the MYC oncoprotein, MGA acts as a negative regulator for cancer cell proliferation. Our study defines a novel MYC/MAX/MGA pathway, in which MYC and MGA play opposite roles in protein interaction, transcriptional regulation, and cellular proliferation. IMPLICATIONS: This study expands the range of key cancer-associated genes whose dysregulation is functionally equivalent to MYC activation and places MYC within a linear pathway analogous to cell-cycle or receptor tyrosine kinase/RAS/RAF pathways in lung adenocarcinomas.

Perturbation of phosphoglycerate kinase 1 (PGK1) only marginally affects glycolysis in cancer cells

Phosphoglycerate kinase 1 (PGK1) plays important roles in glycolysis, yet its forward reaction kinetics are unknown, and its role especially in regulating cancer cell glycolysis is unclear. Here, we developed an enzyme assay to measure the kinetic parameters of the PGK1-catalyzed forward reaction. The K_m values for 1,3-bisphosphoglyceric acid (1,3-BPG, the forward reaction substrate) were 4.36 μm (yeast PGK1) and 6.86 μm (human PKG1). The K_m values for 3-phosphoglycerate (3-PG, the reverse reaction substrate and a serine precursor) were 146 μm (yeast PGK1) and 186 μm (human PGK1). The V _max of the forward reaction was about 3.5- and 5.8-fold higher than that of the reverse reaction for the human and yeast enzymes, respectively. Consistently, the intracellular steady-state concentrations of 3-PG were between 180 and 550 μm in cancer cells, providing a basis for glycolysis to shuttle 3-PG to the serine synthesis pathway. Using siRNA-mediated PGK1-specific knockdown in five cancer cell lines derived from different tissues, along with titration of PGK1 in a cell-free glycolysis system, we found that the perturbation of PGK1 had no effect or only marginal effects on the glucose consumption and lactate generation. The PGK1 knockdown increased the concentrations of fructose 1,6-bisphosphate, dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, and 1,3-BPG in nearly equal proportions, controlled by the kinetic and thermodynamic states of glycolysis. We conclude that perturbation of PGK1 in cancer cells insignificantly affects the conversion of glucose to lactate in glycolysis.

Surface-Initiated Atom Transfer Polymerized Anionic Corona on Gold Nanoparticles for Anti-Cancer Therapy

Surface initiated atom transfer radical polymerization (SI-ATRP) documented a simple but efficient technique to grow a dense polymer layer on any surface. Gold nanoparticles (AuNPs) give a broad surface to immobilize sulfhyryl group-containing initiators for SI-ATRP; in addition, AuNPs are the major nanoparticulate carriers for delivery of anti-cancer therapeutics, since they are biocompatible and bioinert. In this work, AuNPs with a disulfide initiator were polymerized with sulfoethyl methacrylate by SI-ATRP to decorate the particles with anionic corona, and branched polyethyeleneimine (PEI) and siRNA were sequentially layered onto the anionic corona of AuNP by electrostatic interaction. The in vitro anti-cancer effect confirmed that AuNP with anionic corona showed higher degrees of apoptosis as well as suppression of the oncogene expression in a siRNA dose-dependent manner. The in vivo study of tumor-bearing nude mice revealed that mice treated with c-Myc siRNA-incorporated AuNPs showed dramatically decreased tumor size in comparison to those with free siRNA for 4 weeks. Furthermore, histological examination and gene expression study revealed that the decorated AuNP significantly suppressed c-Myc expression. Thus, we envision that the layer-by-layer assembly on the anionic brushes can be potentially used to incorporate nucleic acids onto metallic particles with high transfection efficiency.

Knockdown of ectodysplasin-A receptor-associated adaptor protein exerts a tumor-suppressive effect in tongue squamous cell carcinoma cells

Tongue squamous cell carcinoma (TSCC) is a common malignancy in oral cancer with a high mortality and morbidity. The ectodysplasin-A receptor-associated adaptor protein (EDARADD) is a death domain-containing adaptor protein that interacts with the TNF family ligand ectodysplasin A receptor. It is known that EDARADD has an effect on the development of ectodermal derivative tissues, such as hair and teeth. EDARADD expression is also associated with the development of melanoma. However, the role of EDARADD in TSCC remains unknown. The aim of the present investigation was to explore whether EDARADD plays a role in the biological function of TSCC. Immunohistochemistry was used to measure the expression of EDARADD in TSCC tissues and adjacent normal tissue. EDARADD was knocked down in a TSCC cell line in vitro using a specific lentivirus. The expression level of the EDARADD gene and the efficacy of gene knockdown were evaluated by reverse transcription-quantitative PCR, while EDARADD protein expression and the expression levels of Bcl-2, MYC and NF-κBp65 were determined by western blotting. Additionally, MTT assays, colony formation assays and apoptosis assays were carried out to examine the effect of EDARADD knockdown on the TSCC cells. A previous study showed that the majority of the TSCC tissues that were tested had high EDARADD expression. The expression of EDARADD both at mRNA and protein levels was significantly lower (P<0.01) after the gene was knocked down in the CAL27 cells compared with the level in control cells. Downregulation of EDARADD expression inhibited colony formation and proliferation and induced apoptosis of CAL27 cells when compared to control cells (P<0.01). Taken together, these results suggested that EDARADD may be actively involved in the progression of TSCC and that EDARADD may be a novel therapeutic target for the treatment of TSCC.

The Complex Network between MYC Oncogene and microRNAs in Gastric Cancer: An Overview

Despite the advancements in cancer treatments, gastric cancer is still one of the leading causes of death worldwide. In this context, it is of great interest to discover new and more effective ways of treating this disease. Accumulated evidences have demonstrated the amplification of 8q24.21 region in gastric tumors. Furthermore, this is the region where the widely known MYC oncogene and different microRNAs are located. MYC deregulation is key in tumorigenesis in various types of tissues, once it is associated with cell proliferation, survival, and drug resistance. microRNAs are a class of noncoding RNAs that negatively regulate the protein translation, and which deregulation is related with gastric cancer development. However, little is understood about the interactions between microRNAs and MYC. Here, we overview the MYC role and its relationship with the microRNAs network in gastric cancer aiming to identify potential targets useful to be used in clinic, not only as biomarkers, but also as molecules for development of promising therapies.

Regulation of B-cell function by NF-kappaB c-Rel in health and disease

B cells mediate humoral immune response and contribute to the regulation of cellular immune response. Members of the Nuclear Factor kappaB (NF-κB) family of transcription factors play a major role in regulating B-cell functions. NF-κB subunit c-Rel is predominantly expressed in lymphocytes, and in B cells, it is required for survival, proliferation, and antibody production. Dysregulation of c-Rel expression and activation alters B-cell homeostasis and is associated with B-cell lymphomas and autoimmune pathologies. Based on its essential roles, c-Rel may serve as a potential prognostic and therapeutic target. This review summarizes the current understanding of the multifaceted role of c-Rel in B cells and B-cell diseases.

Myc-mediated SDHA acetylation triggers epigenetic regulation of gene expression and tumorigenesis

The transcriptional role of cMyc (or Myc) in tumorigenesis is well appreciated; however, it remains to be fully established how extensively Myc is involved in the epigenetic regulation of gene expression. Here, we show that by deactivating succinate dehydrogenase complex subunit A (SDHA) via acetylation, Myc triggers a regulatory cascade in cancer cells that leads to H3K4me3 activation and gene expression. We find that Myc facilitates the acetylation-dependent deactivation of SDHA by activating the SKP2-mediated degradation of SIRT3 deacetylase. We further demonstrate that Myc inhibition of SDH-complex activity leads to cellular succinate accumulation, which triggers H3K4me3 activation and tumour-specific gene expression. We demonstrate that acetylated SDHA at Lys 335 contributes to tumour growth in vitro and in vivo, and we confirm increased tumorigenesis in clinical samples. This study illustrates a link between acetylation-dependent SDHA deactivation and Myc-driven epigenetic regulation of gene expression, which is critical for cancer progression.

Structure and dynamics at N- and C-terminal regions of intrinsically disordered human c-Myc PEST degron reveal a pH-induced transition

We investigated the structure and Brownian rotational motion of the PEST region (201-268) from human c-Myc oncoprotein, whose overexpression/dysregulation is associated with various types of cancer. The 77-residue PEST fragment revealed a large Stokes radius (~3.1 nm) and CD spectrum highlighting abundance of disordered structure. Changes in structure/dynamics at two specific sites in PEST degron were observed using time-resolved fluorescence spectroscopy by labeling Cys⁹ near N-terminal with dansyl probe and inserting a Trp⁷⁰ near C-terminal (PEST M1). Trp in PEST M1 at pH 3 was inaccessible to quencher, showed hindered segmental motion and slow global rotation (~30 ns) in contrast to N-terminal where the dansyl probe was free, exposed with fast global rotation (~5 ns). Remarkably, this large monomeric structure at acidic pH was retained irrespective of ionic strength (0.03-0.25 M) and partially so in presence of 6 M Gdn.HCl. With gradual increase in pH, a structural transition (~pH 4.8) into a more exposed and freely rotating Trp was noticeable. Interestingly, the induced structure at C-terminal also influenced the dynamics of dansyl probe near N-terminal, which otherwise remained unstructured at pH > 5. FRET measurements confirmed a 11 Å decrease in distance between dansyl and indole at pH 4 compared to pH 9, coinciding with enhanced ANS binding and increase in strand/helix population in both PEST fragments. The protonation of glutamate/aspartate residues in C-terminal region of PEST is implicated in this disorder-order transition. This may have a bearing on the role of PEST in endocytic trafficking of eukaryotic proteins.

Targeting Cell Metabolism as Cancer Therapy

Significance: Cancer cells exhibit altered metabolic pathways to keep up with biosynthetic and reduction-oxidation needs during tumor proliferation and metastasis. The common induction of metabolic pathways during cancer progression, regardless of cancer histio- or genotype, makes cancer metabolism an attractive target for therapeutic exploitation. Recent Advances: Emerging data suggest that these altered pathways may even result in resistance to anticancer therapies. Identifying specific metabolic dependencies that are unique to cancer cells has proved challenging in this field, limiting the therapeutic window for many candidate drug approaches. Critical Issues: Cancer cells display significant metabolic flexibility in nutrient-limited environments, hampering the longevity of suppressing cancer metabolism through any singular approach. Combinatorial "synthetic lethal" approaches may have a better chance for success and promising strategies are reviewed here. The dynamism of the immune system adds a level of complexity, as various immune populations in the tumor microenvironment often share metabolic pathways with cancer, with successive alterations during immune activation and quiescence. Decoding the reprogramming of metabolic pathways within cancer cells and stem cells, as well as examining metabolic symbiosis between components of the tumor microenvironment, would be essential to further meaningful drug development within the tumor's metabolic ecosystem. Future Directions: In this article, we examine evidence for the therapeutic potential of targeting metabolic alterations in cancer, and we discuss the drawbacks and successes that have stimulated this field.

RIG-I aggravates interstitial fibrosis via c-Myc-mediated fibroblast activation in UUO mice

Abstract

Progressive tubulointerstitial fibrosis is the common final outcome for all kidney diseases evolving into chronic kidney disease (CKD), whereas molecular mechanisms driving fibrogenesis remain elusive. Retinoic acid-inducible gene-I (RIG-I), an intracellular pattern recognition receptor, is originally identified participating in immune response by recognizing virus RNA. Here, we revealed for the first time that RIG-I was induced in unilateral ureteral obstruction (UUO) and folic acid (FA) renal fibrosis models and moderate-degree renal fibrosis patients. Besides, we found RIG-I was mainly located in renal tubular epithelial cells and promoted the production and release of inflammatory cytokines, such as interleukin (IL)-1β and IL-6 through activation of NF-κB. Inflammatory cytokines released by tubular epithelial cells activated c-Myc-mediated TGF-β/Smad signaling in fibroblasts, which in turn aggravated interstitial fibrosis by promoting fibroblast activation and production of extracellular matrix components (ECM). Deficiency of RIG-I attenuated renal fibrosis by the regulation of inflammatory responses, c-Myc expression, and fibroblast activation. Besides, gene silencing of RIG-I reduced inflammatory cytokines in cultured tubular epithelial cells treated with Angiotensin II. Knockdown of c-Myc or c-Myc inhibitor blocked IL-1β-induced fibroblast activation. Collectively, our study demonstrates that RIG-I plays a significant role in the progress of renal fibrosis via regulating c-Myc-mediated fibroblast activation.

Key messages

• RIG-I was constantly elevated in kidneys from renal fibrotic mice.

• RIG-I facilitated inflammatory cytokine production in tubular epithelial cells.

• RIG-I aggravated renal fibrosis via c-Myc-mediated TGF-β/Smad activation.

Targeting BET Proteins With a PROTAC Molecule Elicits Potent Anticancer Activity in HCC Cells

Background and Aim: Bromodomain and extraterminal domain (BET) family proteins are epigenetic regulators involved in human malignances. Targeting BET proteins for degradation using proteolysis-targeting chimera (PROTAC) recently has drawn increasing attention in the field of cancer therapeutics. BET proteins have been found to be overexpressed in HCC cells and tumor tissues. However, the biological activity of BET-PROTACs in hepatocellular carcinoma (HCC) remains unclear. In this study, we investigated anti-HCC activity of BETd-260, a BET-PROTAC molecule using in vitro and in vivo models. Methods: BETd-260-mediated anti-HCC activity was investigated by cell viability, apoptosis assays. Efficacy was examined with a cell lines-derived HCC xenograft model in mice. Anticancer mechanism was investigated by RT-PCR, western blotting and immunohistochemical staining. Results: BETd-260 potently suppressed cell viability and robustly induced apoptosis in HCC cells. BETd-260 reciprocally modulated the expression of several apoptotic genes in HCC cells, i.e., suppressing the expression of anti-apoptotic Mcl-1, Bcl-2, c-Myc, and X-linked inhibitor of apoptosis (XIAP), whereas increasing the expression of pro-apoptotic Bad. BETd-260 treatment led to disruption of mitochondrial membrane integrity, and triggered apoptosis via intrinsic signaling in HCC cells. BETd-260 triggered apoptosis in HCC xenograft tissue and profoundly inhibited the growth of HCC xenograft tumors in mice. Conclusion: Our data suggest that pharmacological targeting of BET for degradation may be a novel therapeutic strategy for the treatment of HCC.

Topologies of G-quadruplex: Biological functions and regulation by ligands

G-Quadruplex (G4) is one of the higher-order structures occurring in guanine-rich sequences of nucleic acids, and plays critical roles in biological processes. The G4-forming sequences can generate three kinds of topologies, i.e., parallel, anti-parallel, and hybrid, and these polymorphic structures have an important influence on G4-related biological functions. In this review, we highlight variety of structures generated by G4s containing various sequences and under diverse conditions. We also discuss the G4 ligands which induce specific topologies and/or conversion between different topologies.

Crosstalk between NLRP12 and JNK during Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a leading cause of cancer-related death, is initiated and promoted by chronic inflammation. Inflammatory mediators are transcriptionally regulated by several inflammatory signaling pathways, including nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK). cJun N-terminal kinase (JNK), a member of the MAPK family, plays a central role in HCC pathogenesis. Pathogen-associated molecular patterns (PAMPs) activate JNK and other MAPK upon recognition by toll-like receptors (TLRs). Apart from TLRs, PAMPs are sensed by several other pattern recognition receptors, including cytosolic NOD-like receptors (NLRs). In a recent study, we demonstrated that the NLR member NLRP12 plays a critical role in suppressing HCC via negative regulation of the JNK pathway. This article briefly reviews the crosstalk between NLRP12 and JNK that occurs during HCC.

Increased O-GlcNAcylation of c-Myc Promotes Pre-B Cell Proliferation

O-linked β-N-acetylglucosamine (O-GlcNAc) modification regulates the activity of hundreds of nucleocytoplasmic proteins involved in a wide variety of cellular processes, such as gene expression, signaling, and cell growth; however, the mechanism underlying the regulation of B cell development and function by O-GlcNAcylation remains largely unknown. Here, we demonstrate that changes in cellular O-GlcNAc levels significantly affected the growth of pre-B cells, which rapidly proliferate to allow expansion of functional clones that express successfully rearranged heavy chains at the pro-B stage during early B cell development. In our study, the overall O-GlcNAc levels in these proliferative pre-B cells, which are linked to the glucose uptake rate, were highly induced when compared with those in pro-B cells. Thus, pharmacologically, genetically, or nutritionally, inhibition of O-GlcNAcylation in pre-B cells markedly downregulated c-Myc expression, resulting in cell cycle arrest via blockade of cyclin expression. Importantly, the population of B cells after the pro-B cell stage in mouse bone marrow was severely impaired by the administration of an O-GlcNAc inhibitor. These results strongly suggest that O-GlcNAcylation-dependent expression of c-Myc represents a new regulatory component of pre-B cell proliferation, as well as a potential therapeutic target for the treatment of pre-B cell-derived leukemia.

Up-regulation of RNA Binding Proteins Contributes to Folate Deficiency-Induced Neural Crest Cells Dysfunction

Folate deficiency has long been associated with the abnormal development of the neural crest cells (NCCs) and neural tube defects (NTDs). RNA binding proteins (RBPs) also play important roles in the normal neural crest development and neural tube formation. Nevertheless, the causative mechanism by which folate status influences human NCCs development and the RBPs functions remains unknown. In this study, we differentiated H9 human embryonic stem cells into neural crest cells (H9-NCCs) and then constructed three folic acid (FA) deficiency (FAD) H9-NCCs models in vitro. Decreased viability, impaired migration and promoted apoptosis of H9-NCCs were observed in three FAD H9-NCCs models. In addition, we showed that three RBPs, namely, hnRNPC, LARP6 and RCAN2, were up-regulated both in the FAD H9-NCC models in vitro and in the FAD mouse model in vivo. Knocking down of these three RBPs increased the H9-NCC viability and RCAN2 knockdown further promoted H9-NCC migration under FAD conditions. In normal culture condition, overexpression of RCAN2 and HnRNPC did not affect viabilities and migration of H9-NCCs while overexpression of LARP6 reduced the H9-NCC viability. Our findings demonstrate important regulatory effects of RBPs underlying FAD-induced impaired function of NCCs.

Dances with Cells

Like all of us, cells proceed through stages of life. In this whimsical review, aspects of several such stages, including birth, growth, aging, death, and "afterlife," are considered, with a special emphasis on cells of the immune system. Discussed along the way are asymmetric division of activated, naive cluster of differentiation 8+ T cells, c-Myc and polyamines in lymphocyte function and aging, cell survival after induction of cell death pathways, cell death consequences, and clearance of dead cells from surrounding tissues. This is offered in memory of the unique and wonderful Dr. Eli Sercarz.

C-MYC, BCL2 and BCL6 Translocation in B-cell Non-Hodgkin Lymphoma Cases

C-MYC, BCL2 and BCL6 genes are the most commonly oncogenes involved in B-Cell lymphomas. Translocations of these oncogenes are associated with an aggressive clinical course. This study aims to elucidate the patterns of BCL6, BCL2 and C-MYC gene aberrations among Malaysian B-cell Non-Hodgkin Lymphoma (NHL) using fluorescence in situ hybridization (FISH). Eighty-one B-cell NHL tissue blocks were retrieved between the year 2011 to 2015 and investigated using immunohistochemistry and interphase FISH dual colour break-apart probes of BCL2, BCL6, C-MYC and IgH. A significant difference was detected between the nodal and extranodal sites in all the BCL2 (p=0.01), C-MYC (p=0.03) and IgH (p=0.006) cases except for BCL6 (p=0.2). Our study showed that BCL6 had the highest gene translocation while BCL2/BCL6 had the most mixed aberrations of gain copies and translocation, however no mixed aberrations of gain copies and translocation was found in C-MYC. None of the mixed gain copies and translocation was found in any of the germinal centre B-cell (GCB) subtype of Diffuse Large B-cell Lymphoma, however, five were found in BCL6 and IgH gene in the non-GCB subtype; while mixed gain copies and translocation cases of BCL2 gene was found in the Follicular Lymphoma cases only. The study found interesting findings of BCL2, C-MYC and IgH gene aberrations between nodal and extranodal sites. This information might benefit future study in predicting prognosis and determine effective therapeutic strategies in the multi-ethnic populations of Malaysia as well as the Asian population.

Phosphoenolpyruvate from Glycolysis and PEPCK Regulate Cancer Cell Fate by Altering Cytosolic Ca2

Changes in phosphoenolpyruvate (PEP) concentrations secondary to variations in glucose availability can regulate calcium signaling in T cells as this metabolite potently inhibits the sarcoplasmic reticulum Ca2+/ATPase pump (SERCA). This regulation is critical to assert immune activation in the tumor as T cells and cancer cells compete for available nutrients. We examined here whether cytosolic calcium and the activation of downstream effector pathways important for tumor biology are influenced by the presence of glucose and/or cataplerosis through the phosphoenolpyruvate carboxykinase (PEPCK) pathway, as both are hypothesized to feed the PEP pool. Our data demonstrate that cellular PEP parallels extracellular glucose in two human colon carcinoma cell lines, HCT-116 and SW480. PEP correlated with cytosolic calcium and NFAT activity, together with transcriptional up-regulation of canonical targets PTGS2 and IL6 that was fully prevented by CsA pre-treatment. Similarly, loading the metabolite directly into the cell increased cytosolic calcium and NFAT activity. PEP-stirred cytosolic calcium was also responsible for the calmodulin (CaM) dependent phosphorylation of c-Myc at Ser62, resulting in increased activity, probably through enhanced stabilization of the protein. Protein expression of several c-Myc targets also correlated with PEP levels. Finally, the participation of PEPCK in this axis was interrogated as it should directly contribute to PEP through cataplerosis from TCA cycle intermediates, especially in glucose starvation conditions. Inhibition of PEPCK activity showed the expected regulation of PEP and calcium levels and consequential downstream modulation of NFAT and c-Myc activities. Collectively, these results suggest that glucose and PEPCK can regulate NFAT and c-Myc activities through their influence on the PEP/Ca2+ axis, advancing a role for PEP as a second messenger communicating metabolism, calcium cell signaling, and tumor biology.

Structures of 1:1 and 2:1 complexes of BMVC and MYC promoter G-quadruplex reveal a mechanism of ligand conformation adjustment for G4-recognition

BMVC is the first fluorescent probe designed to detect G-quadruplexes (G4s) in vivo. The MYC oncogene promoter forms a G4 (MycG4) which acts as a transcription silencer. Here, we report the high-affinity and specific binding of BMVC to MycG4 with unusual slow-exchange rates on the NMR timescale. We also show that BMVC represses MYC in cancer cells. We determined the solution structures of the 1:1 and 2:1 BMVC-MycG4 complexes. BMVC first binds the 5'-end of MycG4 to form a 1:1 complex with a well-defined structure. At higher ratio, BMVC also binds the 3'-end to form a second complex. In both complexes, the crescent-shaped BMVC recruits a flanking DNA residue to form a BMVC-base plane stacking over the external G-tetrad. Remarkably, BMVC adjusts its conformation to a contracted form to match the G-tetrad for an optimal stacking interaction. This is the first structural example showing the importance of ligand conformational adjustment in G4 recognition. BMVC binds the more accessible 5'-end with higher affinity, whereas sequence specificity is present at the weaker-binding 3'-site. Our structures provide insights into specific recognition of MycG4 by BMVC and useful information for design of G4-targeted anticancer drugs and fluorescent probes.

High mobility group AT-hook 2 and c-MYC as potential prognostic factors in pancreatic ductal adenocarcinoma

The present study investigated if c-MYC and high mobility group AT-hook 2 (HMGA2) expression was associated with prognosis of patients with pancreatic ductal adenocarcinoma (PDAC). A total of 102 patients undergoing surgery for PDAC were retrospectively reviewed. Immunohistochemistry was used to detect c-MYC and HMGA2 protein expression in PDAC and peritumoral tissue samples. Expression of c-MYC and HMGA2 was associated with clinicopathological characteristics and prognoses of patients with PDAC using multivariate analysis. HMGA2 and c-MYC protein expression was significantly higher in PDAC tissues compared with peritumoral tissue (P<0.001). HMGA2 and c-MYC expression was also significantly higher in patients with PDAC who had lymph node metastasis, invasion of regional tissues and tumor node metastasis (TNM) stage III or IV disease compared with those who had no lymph node metastasis, no invasion of regional tissues and TNM stage I or II disease (P<0.001). Multivariate logistic regression analysis was used to identify TNM stage (P=0.007) and invasion (P=0.003) as significant independent predictors of c-MYC expression (model AUC=0.8201), and lymph node metastasis (P=0.002) and invasion (P=0.003) as significant independent predictors of HMGA2 expression (model AUC=0.7638). Cox multivariate analysis showed that expression of c-MYC (P=0.019) and HMGA2 (P<0.001), TNM stage (P=0.014) and lymph node metastasis (P=0.032) were associated with reduced overall survival time. HMGA2 and c-MYC may be important biological markers and potential therapeutic targets involved in the tumorigenesis, metastasis, invasion and prognosis of PDAC.

Exploring the role of circadian clock gene and association with cancer pathophysiology

Most of the processes that occur in the mind and body follow natural rhythms. Those with a cycle length of about one day are called circadian rhythms. These rhythms are driven by a system of self-sustained clocks and are entrained by environmental cues such as light-dark cycles as well as food intake. In mammals, the circadian clock system is hierarchically organized such that the master clock in the suprachiasmatic nuclei of the hypothalamus integrates environmental information and synchronizes the phase of oscillators in peripheral tissues.The circadian system is responsible for regulating a variety of physiological and behavioral processes, including feeding behavior and energy metabolism. Studies revealed that the circadian clock system consists primarily of a set of clock genes. Several genes control the biological clock, including BMAL1, CLOCK (positive regulators), CRY1, CRY2, PER1, PER2, and PER3 (negative regulators) as indicators of the peripheral clock.Circadian has increasingly become an important area of medical research, with hundreds of studies pointing to the body's internal clocks as a factor in both health and disease. Thousands of biochemical processes from sleep and wakefulness to DNA repair are scheduled and dictated by these internal clocks. Cancer is an example of health problems where chronotherapy can be used to improve outcomes and deliver a higher quality of care to patients.In this article, we will discuss knowledge about molecular mechanisms of the circadian clock and the role of clocks in physiology and pathophysiology of concerns.

Myc controls a distinct transcriptional program in fetal thymic epithelial cells that determines thymus growth

Interactions between thymic epithelial cells (TEC) and developing thymocytes are essential for T cell development, but molecular insights on TEC and thymus homeostasis are still lacking. Here we identify distinct transcriptional programs of TEC that account for their age-specific properties, including proliferation rates, engraftability and function. Further analyses identify Myc as a regulator of fetal thymus development to support the rapid increase of thymus size during fetal life. Enforced Myc expression in TEC induces the prolonged maintenance of a fetal-specific transcriptional program, which in turn extends the growth phase of the thymus and enhances thymic output; meanwhile, inducible expression of Myc in adult TEC similarly promotes thymic growth. Mechanistically, this Myc function is associated with enhanced ribosomal biogenesis in TEC. Our study thus identifies age-specific transcriptional programs in TEC, and establishes that Myc controls thymus size.

Tylophorine-based compounds are therapeutic in rheumatoid arthritis by targeting the caprin-1 ribonucleoprotein complex and inhibiting expression of associated c-Myc and HIF-1α

Interruption of the Warburg effect - the observation that un-stimulated macrophages reprogram their core metabolism from oxidative phosphorylation toward aerobic glycolysis to become pro-inflammatory M1 macrophages upon stimulation - is an emerging strategy for the treatment of cancer and anti-inflammatory diseases such as rheumatoid arthritis. We studied this process with view to the discovery of novel therapeutics, and found that tylophorine-based compounds targeted a ribonucleoprotein complex containing caprin-1 and mRNAs of c-Myc and HIF-1α in LPS/IFN-γ stimulated Raw264.7 cells, diminished the protein levels of c-Myc and HIF-1α, and consequently downregulated their targeted genes that are associated with the Warburg effect, as well as the pro-inflammatory iNOS and COX2. The tylophorine-based compound DBQ 33b significantly meliorated the severity and incidence of type II collagen-monoclonal antibody-induced rheumatoid arthritis and diminished gene expressions of c-Myc, HIF-1α, iNOS, COX2, TNFα, and IL-17A in vivo. Moreover, pharmacological inhibition of either c-Myc or HIF-1α exhibited similar effects as the tylophorine-based compound DBQ 33b, even though inhibition of c-Myc reversed the induction of iNOS and COX2 in LPS/IFN-γ stimulated Raw264.7 cells to a lesser degree. Therefore, simultaneous inhibition of both c-Myc and HIF-1α is efficacious for anti-inflammation in vitro and in vivo and merits further study.

19 F NMR Spectroscopy Tagging and Paramagnetic Relaxation Enhancement-Based Conformation Analysis of Intrinsically Disordered Protein Complexes

The combination of ¹⁹ F NMR spectroscopy tagging and paramagnetic relaxation enhancement (PRE) NMR spectroscopy experiments was evaluated as a versatile method to probe protein-protein interactions and conformational changes of intrinsically disordered proteins upon complex formation. The feasibility of the approach is illustrated with an application to the Myc-Max protein complex; this is an oncogenic transcription factor that binds enhancer box DNA fragments. The single cysteine residue of Myc was tagged with highly fluorinated [¹⁹ F]3,5-bis(trifluoromethyl)benzyl bromide. Structural dynamics of the protein complex were monitored through intermolecular PREs between ¹⁹ F-Myc and paramagnetic (1-oxyl-2,2,5,5-tetramethyl-Δ3-pyrroline-3-methyl)methanethiosulfonate (MTSL)-tagged) Max. The ¹⁹ F R₂ relaxation rates obtained with three differently MTSL-tagged Max mutants revealed novel insights into the differential structural dynamics of Myc-Max bound to DNA and the tumour suppressor breast cancer antigen 1. Given its ease of implementation, fruitful applications of this strategy to structural biology and inhibitor screening can be envisaged.

Quantitative Subcellular Proteomics of the Orbitofrontal Cortex of Schizophrenia Patients

Schizophrenia is a chronic disease characterized by the impairment of mental functions with a marked social dysfunction. A quantitative proteomic approach using iTRAQ labeling and SRM, applied to the characterization of mitochondria (MIT), crude nuclear fraction (NUC), and cytoplasm (CYT), can allow the observation of dynamic changes in cell compartments providing valuable insights concerning schizophrenia physiopathology. Mass spectrometry analyses of the orbitofrontal cortex from 12 schizophrenia patients and 8 healthy controls identified 655 protein groups in the MIT fraction, 1500 in NUC, and 1591 in CYT. We found 166 groups of proteins dysregulated among all enriched cellular fractions. Through the quantitative proteomic analysis, we detect as the main biological pathways those related to calcium and glutamate imbalance, cell signaling disruption of CREB activation, axon guidance, and proteins involved in the activation of NF-kB signaling along with the increase of complement protein C3. Based on our data analysis, we suggest the activation of NF-kB as a possible pathway that links the deregulation of glutamate, calcium, apoptosis, and the activation of the immune system in schizophrenia patients. All MS data are available in the ProteomeXchange Repository under the identifier PXD015356 and PXD014350.

Myc Is Required for Adaptive β-Cell Replication in Young Mice but Is Not Sufficient in One-Year-Old Mice Fed With a High-Fat Diet

Failure to expand pancreatic β-cells in response to metabolic stress leads to excessive workload resulting in β-cell dysfunction, dedifferentiation, death, and development of type 2 diabetes. In this study, we demonstrate that induction of Myc is required for increased pancreatic β-cell replication and expansion during metabolic stress-induced insulin resistance with short-term high-fat diet (HFD) in young mice. β-Cell-specific Myc knockout mice fail to expand adaptively and show impaired glucose tolerance and β-cell dysfunction. Mechanistically, PKCζ, ERK1/2, mTOR, and PP2A are key regulators of the Myc response in this setting. DNA methylation analysis shows hypomethylation of cell cycle genes that are Myc targets in islets from young mice fed with a short-term HFD. Importantly, DNA hypomethylation of Myc response elements does not occur in islets from 1-year-old mice fed with a short-term HFD, impairing both Myc recruitment to cell cycle regulatory genes and β-cell replication. We conclude that Myc is required for metabolic stress-mediated β-cell expansion in young mice, but with aging, Myc upregulation is not sufficient to induce β-cell replication by, at least partially, an epigenetically mediated resistance to Myc action.

β-carotene Inhibits Expression of c-Myc and Cyclin E in Helicobacter pylori-infected Gastric Epithelial Cells

Background

Helicobacter pylori infection is a major risk factor in the development of gastric cancer. H. pylori infection of gastric epithelial cells increases the levels of reactive oxygen species (ROS), activates oncogenes, and leads to β-catenin-mediated hyper-proliferation. β-Carotene reduces ROS levels, inhibits oxidant-mediated activation of inflammatory signaling and exhibits anticancer properties. The present study was carried out to determine if β-carotene inhibits H. pylori-induced cell proliferation and the expression of oncogenes c-myc and cyclin E by reducing the levels of β-catenin and phosphorylated glycogen synthase kinase 3β (p-GSK3β).

Methods

Gastric epithelial AGS cells were pre-treated with β-carotene (5 and 10 μM) for 2 hours prior to H. pylori infection and cultured for 6 hours (for determination of the levels of p-GSK3β, GSK3β, and β-catenin) and 24 hours (for determination of cell viability and protein levels of c-myc and cyclin E). Cell viability was determined by the MTT assay and protein levels were determined via western blot-based analysis.

Results

β-Carotene inhibited H. pylori-induced increases in the percentage of viable cells, phosphorylated GSK3β (p-GSK3β), and the levels of β-catenin, c-myc and cyclin E.

Conclusions

β-Carotene inhibits H. pylori-induced hyper-proliferation of gastric epithelial cells by suppressing β-catenin signaling and oncogene expression.

Expression and clinical significance of PD-L1 and c-Myc in non-small cell lung cancer

BACKGROUND

It is known that there are insufficient prognostic factors for non-small cell lung cancer (NSCLC). It was reported that PD-L1 was a prognostic factor for NSCLC,and c-Myc regulated the expression of PD-L1. Herein, we investigated c-Myc and PD-L1 expression and their association with overall survival (OS) in NSCLC.

METHODS

Formalin-fixed paraffin-embedded specimens were obtained from 128 patients with surgically resected primary NSCLC. Immunohistochemistry was used to assess the expression of PD-L1 and c-Myc in this study. Pearson's Chi squared test or Fisher's exact test was used to analyze the correlation of the expression of PD-L1 and c-Myc with clinicopathologic features. The relationship between OS and the expression of PD-L1 and c-Myc was evaluated by the Kaplan-Meier method and Cox proportional hazards model, respectively.

RESULTS

Positive expression of PD-L1 was detected in 59 patients (46.1%). Patients with negative expression of PD-L1 had remarkably longer OS than those with positive expression of PD-L1. The positive expression rate of c-Myc in NSCLC accounted for 58.6% (75/128) and its expression was significantly more frequent in males (p = 0.002) and patients with lymph node metastasis (p = 0.029). PD-L1 expression was positively correlated with c-Myc expression (r = 0.459, p < 0.001). The PD-L1 and c-Myc double-positive group had a worse prognosis than other subgroups (p < 0.05), and the PD-L1 and c-Myc double-negative group had a better OS than other subgroups (p < 0.05).

CONCLUSION

Conjoint analysis of the expression of PD-L1 and c-Myc was a better prognostic approach for NSCLC patients.

Comparative transcriptome analysis of the human endocervix and ectocervix during the proliferative and secretory phases of the menstrual cycle

Despite extensive studies suggesting increased susceptibility to HIV during the secretory phase of the menstrual cycle, the molecular mechanisms involved remain unclear. Our goal was to analyze transcriptomes of the endocervix and ectocervix during the proliferative and secretory phases using RNA sequencing to explore potential molecular signatures of susceptibility to HIV. We identified 202 differentially expressed genes (DEGs) between the proliferative and secretory phases of the cycle in the endocervix (adjusted p < 0.05). The biofunctions and pathways analysis of DEGs revealed that cellular assembly and epithelial barrier function in the proliferative phase and inflammatory response/cellular movement in the secretory phase were among the top biofunctions and pathways. The gene set enrichment analysis of ranked DEGs (score = log fold change/p value) in the endocervix and ectocervix revealed that (i) unstimulated/not activated immune cells gene sets positively correlated with the proliferative phase and negatively correlated with the secretory phase in both tissues, (ii) IFNγ and IFNα response gene sets positively correlated with the proliferative phase in the ectocervix, (iii) HIV restrictive Wnt/β-catenin signaling pathway negatively correlated with the secretory phase in the endocervix. Our data show menstrual cycle phase-associated changes in both endocervix and ectocervix, which may modulate susceptibility to HIV.

Upregulation of Myc promotes the evasion of NK cell‑mediated immunity through suppression of NKG2D ligands in K562 cells

c-Myc is a characteristic oncogene with dual functions in cell proliferation and apoptosis. Since the overexpression of the c-Myc proto-oncogene is a common event in the development and growth of various human types of cancer, the present study investigated whether oncogenic c-Myc can alter natural killer (NK) cell-mediated immunity through the expression of associated genes, using PCR, western blotting and flow cytometry assays. Furthermore, whether c-Myc could influence the expression levels of natural killer group 2 member D (NKG2D) ligands, which are well known NK activation molecules, as well as NK cell-mediated immunity, was investigated. c-Myc was inhibited by 10058-F4 treatment and small interfering RNA transfection. Upregulation of c-Myc was achieved by transfection with a pCMV6-myc vector. The inhibition of c-Myc increased MHC class I polyeptide-related sequence B and UL16 binding protein 1 expressions among NKG2D ligands, and the overexpression of c-Myc suppressed the expression of all NKG2D ligands, except MHC class I polyeptide-related sequence A. Furthermore, the alteration of c-Myc activity altered the susceptibility of K562 cells to NK cells. These results suggested that the overexpression of c-Myc may contribute to the immune escape of cancer cells and cell proliferation. Combined treatment with NK-based cancer immunotherapy and inhibition of c-Myc may achieve improved therapeutic results.

c-Myc promotes tubular cell apoptosis in ischemia-reperfusion-induced renal injury by negatively regulating c-FLIP and enhancing FasL/Fas-mediated apoptosis pathway

c-Myc plays an important role in cell proliferation, differentiation, and cell apoptosis. FasL/Fas pathway is a key regulator of cell apoptosis. This study was aimed to investigate the effects of c-Myc on the FasL/Fas pathway in ischemia-reperfusion (I/R)-induced renal injury. Rats were objected to bilateral renal ischemia for 60 min and reperfused for 24 or 48 h. NRK-52E cells were treated with hypoxia-reoxygenation (H/R) or FasL. Immunohistochemistry was used to identify the distribution of c-Myc. Cell apoptosis was assessed by TUNEL staining. Ad-c-Myc and recombinant pcDAN 3.0 were used to overexpress c-Myc and c-FLIP, respectively. ChIP assay and luciferase assay were used to detect the binding of c-Myc to c-FLIP promoter. In I/R rats, c-Myc was increased significantly and mainly located in renal tubular epithelial cells; meanwhile, c-FLIP was decreased, cleaved caspase-8, cleaved caspase-3 and TUNEL-positive staining cells were increased. Treatment of I/R rats with c-Myc inhibitor 10058-F4 significantly attenuated the decrease in c-FLIP, the increase in cleaved caspase-8, cleaved caspase-3, TUNEL-positive cells, Scr and BUN in I/R rats. In NRK-52E cells, hypoxia and reoxygen induced the increase in c-Myc and decrease in c-FLIP. ChIP and luciferase assay results indicated that c-Myc binds to the promoter region of c-FLIP gene. Overexpression of c-Myc markedly decreased c-FLIP. Overexpression of c-FLIP inhibited the increase in cleaved caspase-8 and caspase-3 induced by FasL. Data indicated that c-Myc is increased in kidneys of I/R rats and negatively regulates the expression of c-FLIP, then enhanced FasL-induced cell apoptosis in I/R stress.

Repression of GCN5 expression or activity attenuates c-MYC expression in non-small cell lung cancer

Lung cancer causes the highest mortality in cancer-related deaths. As these cancers often become resistant to existing therapies, definition of novel molecular targets is needed. Epigenetic modifiers may provide such targets. Recent reports suggest that the histone acetyltransferase (HAT) module within the transcriptional coactivator SAGA complex plays a role in cancer, creating a new link between epigenetic regulators and this disease. GCN5 serves as a coactivator for MYC target genes, and here we investigate links between GCN5 and c-MYC in non-small cell lung cancer (NSCLC). Our data indicate that both GCN5 and c-MYC proteins are upregulated in mouse and human NSCLC cells compared to normal lung epithelial cells. This trend is observable only at the protein level, indicating that this upregulation occurs post-transcriptionally. Human NSCLC tissue data provided by The Cancer Genome Atlas (TCGA) indicates that GCN5 and c-MYC expression are positively associated with one another and with the expression of c-MYC target genes. Depletion of GCN5 in NSCLC cells reduces c-MYC expression, cell proliferation, and increases the population of necrotic cells. Similarly, inhibition of the GCN5 catalytic site using a commercially available probe reduces c-MYC expression, cell proliferation, and increases the percentage of cells undergoing apoptosis. Our findings suggest that GCN5 might provide a novel target for inhibition of NSCLC growth and progression.

Targeting snoRNAs as an emerging method of therapeutic development for cancer

The relevance of the dysregulation of snoRNAs in human cancer has been widely investigated and has challenged the view that snoRNAs merely function as house-keeping genes for the posttranscriptional modification of rRNAs. Accumulating evidence has shown the intimate connection between snoRNAs and proliferation, apoptosis, invasion and migration of tumor cells via manual intervention patterns of snoRNA expression. In this review, we focused on how snoRNAs are dysregulated and its regulation of the formation and development of cancer. We summarized the non-classical functions of snoRNAs in the context of their regulations of the signaling pathways involving PI3K-AKT and K-Ras and p53-dependant manner. Under these novel functions and characteristics, snoRNAs can act as potential and feasible biomarkers for diagnosis. Simultaneously, these promising therapeutic strategies should be considered to counteract the perturbations of snoRNAs.

Site-specific amino acid substitution in dodecameric peptides determines the stability and unfolding of c-MYC quadruplex promoting apoptosis in cancer cells

c-MYC proto-oncogene harbours a transcription-inhibitory quadruplex-forming scaffold (Pu27) upstream P₁ promoter providing anti-neoplastic therapeutic target. Previous reports showed the binding profile of human Cathelicidin peptide (LL37) and telomeric G-quadruplex. Here, we truncated the quadruplex-binding domain of LL37 to prepare a small library of peptides through site-specific amino acid substitution. We investigated the intracellular selectivity of peptides for Pu27 over other oncogenic quadruplexes and their role in c-MYC promoter repression by dual-luciferase assays. We analysed their thermodynamics of binding reactions with c-MYC quadruplex isomers (Pu27, Myc22, Pu19) by Isothermal Titration Calorimetry. We discussed how amino acid substitutions and peptide helicity enhanced/weakened their affinities for c-MYC quadruplexes and characterized specific non-covalent inter-residual interactions determining their selectivity. Solution NMR structure indicated that KR12C, the best peptide candidate, selectively stabilized the 5′-propeller loop of c-MYC quadruplex by arginine-driven electrostatic-interactions at the sugar-phosphate backbone while KR12A peptide destabilized the quadruplex inducing a single-stranded hairpin-like conformation. Chromatin immunoprecipitations envisaged that KR12C and KR12A depleted and enriched Sp1 and NM23-H2 (Nucleoside diphosphate kinase) occupancy at Pu27 respectively supporting their regulation in stabilizing and unfolding c-MYC quadruplex in MCF-7 cells. We deciphered that selective arresting of c-MYC transcription by KR12C triggered apoptotic-signalling pathway via VEGF-A-BCL-2 axis.

HOXA10 deteriorates gastric cancer through activating JAK1/STAT3 signaling pathway

Background: HOXA10 has been reported to be deregulated in many kinds of cancers including gastric cancer. But its role in gastric cancer progression is controversial. Therefore, the current study was performed to explore the role and mechanism of HOXA10 in gastric cancer.

Materials and methods: IHC and Western blotting assays were used to assess HOXA10 expression in gastric cancer tissues and cells. Lentivirus infection was used to alter HOXA10, STAT3 and JAK1 expression in gastric cancer NCI-N87 and MKN28 cells. MTT, cloning formation, flow cytometry and in vivo xenotransplantation experiments were carried out to assess cell proliferation, cloning formation, apoptosis and tumorigenesis.

Results: HOXA10 expression was obviously increased in gastric cancer tissues and cells when compared with the normal gastric tissue samples and cells. Upregulation of HOXA10 significantly enhanced cell proliferation, cloning formation and tumorigenesis abilities and reduced cell apoptosis in gastric cancer, and promoted the activation of JAK1/STAT3 signaling. In addition, we showed that the effects of HOXA10 on the promotion of cell viability and tumorigenesis and cell apoptosis repression were all weakened when JAK1 or STAT3 was downregulated.

Conclusion: This study demonstrates that HOXA10 functions as an oncogene in gastric cancer through activating JAK1/STAT3 signaling.

Associations among dietary seaweed intake, c-MYC rs6983267 polymorphism, and risk of colorectal cancer in a Korean population: a case-control study

PURPOSE

The effects of seaweed compounds have been studied in relation to colorectal cancer (CRC) based on their ability to modulate carcinogen metabolism in vivo and in vitro. However, no epidemiological studies on the interaction between edible seaweed and genetic variants relevant to CRC have been reported. This study examined the associations among dietary seaweed intake (gim, miyeok, and dashima), single-nucleotide polymorphisms (SNPs; rs6983267, rs7014346, and rs719725), and CRC risk in a Korean population.

METHODS

The participants comprised 923 CRC patients and 1846 controls who visited the National Cancer Center Korea. We used a Semiquantitative Food Frequency Questionnaire and genotyped SNPs using genomic DNA samples.

RESULTS

The intake of total seaweed, miyeok, and dashima showed a significant inverse association with CRC risk after adjusting for potential confounding factors (total seaweed odds ratio (OR) [95% CI] = 0.65 [0.50-0.85], P for trend < 0.001; miyeok = 0.82 [0.62-1.09], P for trend < 0.05; dashima = 0.58 [0.44-0.76], P for trend < 0.001, highest vs. lowest tertile). We confirmed that the homozygous T/T allele of rs6983267 c-MYC indicated an interaction between dietary seaweed intake and both overall CRC and rectal cancer (CRC OR [95% CI] = 0.52 [0.34-0.81], P for interaction = 0.015; rectal cancer = 0.45 [0.25-0.79], P for interaction = 0.007, T/T carriers with high total seaweed intake vs. T/T carriers with low total seaweed intake).

CONCLUSIONS

This study provides evidence of the effect of dietary seaweed intake on CRC risk with respect to c-MYC gene variants.

Indenoisoquinoline Topoisomerase Inhibitors Strongly Bind and Stabilize the MYC Promoter G-Quadruplex and Downregulate MYC

MYC is one of the most important oncogenes and is overexpressed in the majority of cancers. G-Quadruplexes are noncanonical four-stranded DNA secondary structures that have emerged as attractive cancer-specific molecular targets for drug development. The G-quadruplex formed in the proximal promoter region of the MYC oncogene (MycG4) has been shown to be a transcriptional silencer that is amenable to small-molecule targeting for MYC suppression. Indenoisoquinolines are human topoisomerase I inhibitors in clinical testing with improved physicochemical and biological properties as compared to the clinically used camptothecin anticancer drugs topotecan and irinotecan. However, some indenoisoquinolines with potent anticancer activity do not exhibit strong topoisomerase I inhibition, suggesting a separate mechanism of action. Here, we report that anticancer indenoisoquinolines strongly bind and stabilize MycG4 and lower MYC expression levels in cancer cells, using various biochemical, biophysical, computer modeling, and cell-based methods. Significantly, a large number of active indenoisoquinolines cause strong MYC downregulation in cancer cells. Structure-activity relationships of MycG4 recognition by indenoisoquinolines are investigated. In addition, the analysis of indenoisoquinoline analogues for their MYC-inhibitory activity, topoisomerase I-inhibitory activity, and anticancer activity reveals a synergistic effect of MYC inhibition and topoisomerase I inhibition on anticancer activity. Therefore, this study uncovers a novel mechanism of action of indenoisoquinolines as a new family of drugs targeting the MYC promoter G-quadruplex for MYC suppression. Furthermore, the study suggests that dual targeting of MYC and topoisomerase I may serve as a novel strategy for anticancer drug development.

MYC deregulates TET1 and TET2 expression to control global DNA (hydroxy)methylation and gene expression to maintain a neoplastic phenotype in T-ALL

BACKGROUND

While aberrant DNA methylation is a characteristic feature of tumor cells, our knowledge of how these DNA methylation patterns are established and maintained is limited. DNA methyltransferases and ten-eleven translocation methylcytosine dioxygenases (TETs) function has been found altered in a variety of cancer types.

RESULTS

Here, we report that in T cell acute lymphoblastic leukemia (T-ALL) the MYC oncogene controls the expression of TET1 and TET2 to maintain 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) patterns, which is associated with tumor cell-specific gene expression. We found that cellular senescence and tumor regression upon MYC inactivation in T-ALL was associated with genome-wide changes in 5mC and 5hmC patterns. Correlating with the changes in DNA (hydroxy)methylation, we found that T-ALL overexpress TET1, while suppressing TET2 in a MYC-dependent fashion. Consequently, MYC inactivation led to an inverse expression pattern, decreasing TET1, while increasing TET2 levels. Knockdown of TET1 or ectopic expression of TET2 in T-ALL was associated with genome-wide changes in 5mC and 5hmC enrichment and decreased cell proliferation, suggesting a tumor promoting function of TET1, and a tumor suppressing role for TET2. Among the genes and pathways controlled by TET1, we found ribosomal biogenesis and translational control of protein synthesis highly enriched.

CONCLUSIONS

Our finding that MYC directly deregulates the expression of TET1 and TET2 in T-ALL provides novel evidence that MYC controls DNA (hydroxy)methylation in a genome-wide fashion. It reveals a coordinated interplay between the components of the DNA (de)methylating machinery that contribute to MYC-driven tumor maintenance, highlighting the potential of specific TET enzymes for therapeutic strategies.

RNA structural analysis of the MYC mRNA reveals conserved motifs that affect gene expression

The MYC gene encodes a human transcription factor and proto-oncogene that is dysregulated in over half of all known cancers. To better understand potential post-transcriptional regulatory features affecting MYC expression, we analyzed secondary structures in the MYC mRNA using a program that is optimized for finding small locally-folded motifs with a high propensity for function. This was accomplished by calculating folding metrics across the MYC sequence using a sliding analysis window and generating unique consensus base pairing models weighted by their lower-than-random predicted folding energy. A series of 30 motifs were identified, primarily in the 5' and 3' untranslated regions, which show evidence of structural conservation and compensating mutations across vertebrate MYC homologs. This analysis was able to recapitulate known elements found within an internal ribosomal entry site, as well as discover a novel element in the 3' UTR that is unusually stable and conserved. This novel motif was shown to affect MYC expression, potentially via the modulation of miRNA target accessibility or other trans-regulatory factors. In addition to providing basic insights into mechanisms that regulate MYC expression, this study provides numerous, potentially druggable RNA targets for the MYC gene, which is considered “undruggable” at the protein level.

Mebendazole induces apoptosis via C-MYC inactivation in malignant ascites cell line (AGP01)

The objective of study was to examine the role of MBZ on malignant ascites cells and the involvement of C-MYC. Comet assay was used to assess the genotoxic effects of MBZ in AGP01 cells and human lymphocytes; differential staining by ethidium bromide and acridine orange, caspase 3/7 and flow cytometry assay was done to access the mechanisms of apoptosis and cell cycle analysis of MBZ in AGP01 cells. C-MYC amplification, C-MYC mRNA and C-MYC protein expression were evaluated by FISH, RT-qPCR and Western blotting, respectively. In addition, cytotoxicity of MBZ was evaluated in AGP01 and AGP01 shRNA MYC by MTT. MBZ significantly increased the damage index and no produced in human lymphocytes. MBZ caused remarkable cell cycle arrest in G0/G1 and G2/M phases at 0.5μM and 1.0 μM, respectively and induced significantly apoptosis in higher concentrations. Additionally, MBZ (0.5 μM and 1.0 μM) increased caspase 3 and 7 activities. MBZ decreased signals, C-MYC mRNA and C-MYC protein expression in AGP01 cells. MBZ induced lower cell viability in AGP01 cells compared AGP01 shRNA MYC in the same concentration. Therefore, our results show the evidence of C-MYC gene as one of the pathways by which MBZ induces cell death in gastric cancer cells.

Plasma C-MYC level manifesting as an indicator in progression of breast cancer

Aim: To investigate whether plasma C-MYC level could be an indicator in clinical progression of breast cancer. Materials & methods: Plasma level of C-MYC expression was detected by quantitative real time PCR and the level of c-myc protein in breast cancer tissues was detected by immunohistochemistry. The expression level of C-MYC mRNA in supernatant of cancer cells culture was measured compared with the nonbreast cancer cells. Results: Plasma C-MYC level was significantly higher in patients with breast cancer than that in the controls, which associated with clinical stages, lymph node status, etc. Receiver operating characteristic curve analysis showed the sensitivity and specificity of plasma C-MYC level for diagnosis of breast cancer were 63.6 and 81.8%, respectively. The expression of c-myc protein in breast cancer tissues was associated with plasma C-MYC level, even C-MYC level in supernatant of cancer cells was elevated. Conclusion: Plasma C-MYC level might be a potential indicator in progression of breast cancer.