Showing papers by "Eppley Institute for Research in Cancer and Allied Diseases published in 2020"

Pancreatic ductal adenocarcinoma progression is restrained by stromal matrix

Abstract: Desmoplasia describes the deposition of extensive extracellular matrix and defines primary pancreatic ductal adenocarcinoma (PDA). The acellular component of this stroma has been implicated in PDA pathogenesis and is being targeted therapeutically in clinical trials. By analyzing the stromal content of PDA samples from numerous annotated PDA data sets and correlating stromal content with both anatomic site and clinical outcome, we found PDA metastases in the liver, the primary cause of mortality to have less stroma, have higher tumor cellularity than primary tumors. Experimentally manipulating stromal matrix with an anti-lysyl oxidase like-2 (anti-LOXL2) antibody in syngeneic orthotopic PDA mouse models significantly decreased matrix content, led to lower tissue stiffness, lower contrast retention on computed tomography, and accelerated tumor growth, resulting in diminished overall survival. These studies suggest an important protective role of stroma in PDA and urge caution in clinically deploying stromal depletion strategies.

Tumor-intrinsic CD47 signal regulates glycolysis and promotes colorectal cancer cell growth and metastasis.

Abstract: Rationale: CD47 plays a vital role in the immune escape of tumor cells, but its role in regulating immune-unrelated biological processes such as proliferation and metastasis remains unclear. We seek to explore the immune-independent functions of CD47 in colorectal cancer (CRC). Methods: The expression of CD47 in CRC was determined by immunohistochemistry. The biological effect of CD47 signaling on tumor cell proliferation and metastasis was evaluated in vitro and in vivo. RNA sequencing analysis was performed to identify pivotal signaling pathways modulated by CD47. The interaction between CD47 and ENO1 was verified by co-immunoprecipitation (co-IP). The effect of CD47 on glycolytic metabolites was analyzed by seahorse XF and targeted metabolomics. Results: The expression of CD47 was upregulated and correlated to poor prognosis in CRC patients. Functional assays revealed that CD47 promoted CRC cell growth and metastasis in vitro and in vivo. Our mechanistic investigations demonstrated that CD47 interacted with ENO1 and protected it from ubiquitin-mediated degradation, subsequently promoting glycolytic activity and phosphorylation of ERK in CRC cells. Inhibition of ENO1 diminished CD47-mediated cell growth and migration. Clinically, the combined expression of CD47 and ENO1 provided reliable predictive biomarkers for the prognosis of CRC patients. Conclusions: CD47 is overexpressed in CRC, and its expression is associated with poor prognosis. Through stabilizing ENO1, CD47 enhances the aerobic glycolysis and ERK activity in CRC cells, thereby promoting the progression of CRC. Our studies reveal an unconventional role of CD47, suggesting that targeting the CD47-ENO1 axis may provide a novel therapeutic avenue for CRC.

Squamous trans-differentiation of pancreatic cancer cells promotes stromal inflammation.

Abstract: A highly aggressive subset of pancreatic ductal adenocarcinomas undergo trans-differentiation into the squamous lineage during disease progression. Here, we investigated whether squamous trans-differentiation of human and mouse pancreatic cancer cells can influence the phenotype of non-neoplastic cells in the tumor microenvironment. Conditioned media experiments revealed that squamous pancreatic cancer cells secrete factors that recruit neutrophils and convert pancreatic stellate cells into cancer-associated fibroblasts (CAFs) that express inflammatory cytokines at high levels. We use gain- and loss-of-function approaches to show that squamous-subtype pancreatic tumor models become enriched with neutrophils and inflammatory CAFs in a p63-dependent manner. These effects occur, at least in part, through p63-mediated activation of enhancers at pro-inflammatory cytokine loci, which includes IL1A and CXCL1 as key targets. Taken together, our findings reveal enhanced tissue inflammation as a consequence of squamous trans-differentiation in pancreatic cancer, thus highlighting an instructive role of tumor cell lineage in reprogramming the stromal microenvironment.

The third model of Bax/Bak activation: a Bcl-2 family feud finally resolved?

Abstract: Bax and Bak, two functionally similar, pro-apoptotic proteins of the Bcl-2 family, are known as the gateway to apoptosis because of their requisite roles as effectors of mitochondrial outer membrane permeabilization (MOMP), a major step during mitochondria-dependent apoptosis. The mechanism of how cells turn Bax/Bak from inert molecules into fully active and lethal effectors had long been the focal point of a major debate centered around two competing, but not mutually exclusive, models: direct activation and indirect activation. After intensive research efforts for over two decades, it is now widely accepted that to initiate apoptosis, some of the BH3-only proteins, a subclass of the Bcl-2 family, directly engage Bax/Bak to trigger their conformational transformation and activation. However, a series of recent discoveries, using previously unavailable CRISPR-engineered cell systems, challenge the basic premise that undergirds the consensus and provide evidence for a novel and surprisingly simple model of Bax/Bak activation: the membrane (lipids)-mediated spontaneous model. This review will discuss the evidence, rationale, significance, and implications of this new model.

microRNAs Orchestrate Pathophysiology of Breast Cancer Brain Metastasis: Advances in Therapy

Abstract: Brain metastasis (BM) predominantly occurs in triple-negative (TN) and epidermal growth factor 2 (HER2)-positive breast cancer (BC) patients, and currently, there is an unmet need for the treatment of these patients. BM is a complex process that is regulated by the formation of a metastatic niche. A better understanding of the brain metastatic processes and the crosstalk between cancer cells and brain microenvironment is essential for designing a novel therapeutic approach. In this context, the aberrant expression of miRNA has been shown to be associated with BM. These non-coding RNAs/miRNAs regulate metastasis through modulating the formation of a metastatic niche and metabolic reprogramming via regulation of their target genes. However, the role of miRNA in breast cancer brain metastasis (BCBM) is poorly explored. Thus, identification and understanding of miRNAs in the pathobiology of BCBM may identify a novel candidate miRNA for the early diagnosis and prevention of this devastating process. In this review, we focus on understanding the role of candidate miRNAs in the regulation of BC brain metastatic processes as well as designing novel miRNA-based therapeutic strategies for BCBM.

Predicted Prognosis of Patients with Pancreatic Cancer by Machine Learning.

Abstract: Purpose: Pancreatic cancer remains a disease of high mortality despite advanced diagnostic techniques. Mucins (MUC) play crucial roles in carcinogenesis and tumor invasion in pancreatic cancers. MUC1 and MUC4 expression are related to the aggressive behavior of human neoplasms and a poor patient outcome. In contrast, MUC2 is a tumor suppressor, and we have previously reported that MUC2 is a favorable prognostic factor in pancreatic neoplasia. This study investigates whether the methylation status of three mucin genes from postoperative tissue specimens from patients with pancreatic neoplasms could serve as a predictive biomarker for outcome after surgery. Experimental Design: We evaluated the methylation status of MUC1, MUC2, and MUC4 promoter regions in pancreatic tissue samples from 191 patients with various pancreatic lesions using methylation-specific electrophoresis. Then, integrating these results and clinicopathologic features, we used support vector machine-, neural network-, and multinomial-based methods to develop a prognostic classifier. Results: Significant differences were identified between the positive- and negative-prediction classifiers of patients in 5-year overall survival (OS) in the cross-validation test. Multivariate analysis revealed that these prognostic classifiers were independent prognostic factors analyzed by not only neoplastic tissues but also nonneoplastic tissues. These classifiers had higher predictive accuracy for OS than tumor size, lymph node metastasis, distant metastasis, and age and can complement the prognostic value of the TNM staging system. Conclusions: Analysis of epigenetic changes in mucin genes may be of diagnostic utility and one of the prognostic predictors for patients with pancreatic ductal adenocarcinoma.

A Systematic Review on the Implications of O-linked Glycan Branching and Truncating Enzymes on Cancer Progression and Metastasis

Abstract: Glycosylation is the most commonly occurring post-translational modifications, and is believed to modify over 50% of all proteins. The process of glycan modification is directed by different glycosyltransferases, depending on the cell in which it is expressed. These small carbohydrate molecules consist of multiple glycan families that facilitate cell–cell interactions, protein interactions, and downstream signaling. An alteration of several types of O-glycan core structures have been implicated in multiple cancers, largely due to differential glycosyltransferase expression or activity. Consequently, aberrant O-linked glycosylation has been extensively demonstrated to affect biological function and protein integrity that directly result in cancer growth and progression of several diseases. Herein, we provide a comprehensive review of several initiating enzymes involved in the synthesis of O-linked glycosylation that significantly contribute to a number of different cancers.

BAX-dependent mitochondrial pathway mediates the crosstalk between ferroptosis and apoptosis

Abstract: Ferroptosis is considered a distinctive form of cell death compared to other types of death such as apoptosis. It is known to result from iron-dependent accumulation of lipid peroxides rather than caspase activation. However, we reported recently that ferroptosis interplays with apoptosis. In this study, we investigated a possible mechanism of this interplay between ferroptosis and apoptosis. Results from our studies reveal that combined treatment of the ferroptotic agent erastin and the apoptotic agent TRAIL effectively disrupted mitochondrial membrane potential (ΔΨm) and subsequently promoted caspase activation. The alterations of mitochondrial membrane potential are probably due to an increase in oligomerization of BAX and its accumulation at the mitochondria during treatment with erastin and TRAIL. Interestingly, the combined treatment-promoted apoptosis was effectively inhibited in BAX-deficient HCT116 cells, but not BAK-deficient cells. These results indicate that the BAX-associated mitochondria-dependent pathway plays a pivotal role in erastin-enhanced TRAIL-induced apoptosis.

Kinesin Kif2C in regulation of DNA double strand break dynamics and repair

Abstract: DNA can be damaged in many ways, and a double strand break is one of the most dangerous. This occurs when both strands of the double helix snap at the same time, leaving two broken ends. When cells detect this kind of damage, they race to get it fixed as quickly as possible. Fixing these double strand breaks is thought to involve the broken ends being moved to 'repair centers’ in the nucleus of the cell, but it was unclear how the broken ends were moved. One possibility was that the cells transport the broken ends along protein filaments called microtubules. Cells can assemble these track-like filaments on-demand to carry cargo attached to molecular motors called kinesins. However, this type of transport happens outside of the cell’s nucleus, and while there are different kinesin proteins localized inside the nucleus, their roles are largely unknown. In an effort to understand how broken DNA ends are repaired, Zhu, Paydar et al. conducted experiments that simulated double strand breaks and examined the proteins that responded. The first set of experiments involved mixing cut pieces of DNA with extracts taken from frog eggs or human cells. Zhu, Paydar et al. found that one kinesin called Kif2C stuck to the DNA fragments, and attached to many proteins known to play a role in DNA damage repair. Kif2C had previously been shown to help separate the chromosomes during cell division. To find out more about its potential role in DNA repair, Zhu, Paydar et al. then used a laser to create breaks in the DNA of living human cells and tracked Kif2C movement. The kinesin arrived within 60 seconds of the DNA damage and appeared to transport the cut DNA ends to 'repair centers'. Getting rid of Kif2C, or blocking its activity, had dire effects on the cells' abilities to mobilize and repair breaks to its DNA. Without the molecular motor, fewer double strand breaks were repaired, and so DNA damage started to build up. Defects in double strand break repair happen in many human diseases, including cancer. Many cancer treatments damage the DNA of cancer cells, sometimes in combination with drugs that stop cells from building and using their microtubule transport systems. Understanding the new role of Kif2C in DNA damage repair could therefore help optimize these treatment combinations.

Image-guided tumor surgery: The emerging role of nanotechnology.

Abstract: Surgical resection is a mainstay treatment for solid tumors. Yet, methods to distinguish malignant from healthy tissue are primarily limited to tactile and visual cues as well as the surgeon's experience. As a result, there is a possibility that a positive surgical margin (PSM) or the presence of residual tumor left behind after resection may occur. It is well-documented that PSMs can negatively impact treatment outcomes and survival, as well as pose an economic burden. Therefore, surgical tumor imaging techniques have emerged as a promising method to decrease PSM rates. Nanoparticles (NPs) have unique characteristics to serve as optical contrast agents during image-guided surgery (IGS). Recently, there has been tremendous growth in the volume and types of NPs used for IGS, including clinical trials. Herein, we describe the most recent contributions of nanotechnology for surgical tumor identification. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Venetoclax causes metabolic reprogramming independent of BCL-2 inhibition

Abstract: BH3-mimetics are a new class of anti-cancer drugs that inhibit anti-apoptotic Bcl-2 proteins. In doing so, BH3-mimetics sensitise to cell death. Venetoclax is a potent, BCL-2 selective BH3-mimetic that is clinically approved for use in chronic lymphocytic leukaemia. Venetoclax has also been shown to inhibit mitochondrial metabolism, this is consistent with a proposed role for BCL-2 in metabolic regulation. We used venetoclax to understand BCL-2 metabolic function. Similar to others, we found that venetoclax inhibited mitochondrial respiration. In addition, we also found that venetoclax impairs TCA cycle activity leading to activation of reductive carboxylation. Importantly, the metabolic effects of venetoclax were independent of cell death because they were also observed in apoptosis-resistant BAX/BAK-deficient cells. However, unlike venetoclax treatment, inhibiting BCL-2 expression had no effect on mitochondrial respiration. Unexpectedly, we found that venetoclax also inhibited mitochondrial respiration and the TCA cycle in BCL-2 deficient cells and in cells lacking all anti-apoptotic BCL-2 family members. Investigating the basis of this off-target effect, we found that venetoclax-induced metabolic reprogramming was dependent upon the integrated stress response and ATF4 transcription factor. These data demonstrate that venetoclax affects cellular metabolism independent of BCL-2 inhibition. This off-target metabolic effect has potential to modulate venetoclax cytotoxicity.

Secretory Mucin 5AC Promotes Neoplastic Progression by Augmenting KLF4-Mediated Pancreatic Cancer Cell Stemness

Abstract: Secreted mucin 5AC (MUC5AC) is the most abundantly overexpressed member of the mucin family during early pancreatic intraepithelial neoplasia stage I (PanIN-I) of pancreatic cancer. To comprehend the contribution of Muc5ac in pancreatic cancer pathology, we genetically ablated it in an autochthonous murine model (KrasG12D; Pdx-1cre, KC), which mirrors the early stages of pancreatic cancer development. Neoplastic onset and the PanIN lesion progression were significantly delayed in Muc5ac knockout (KrasG12D; Pdx-1 cre; Muc5ac-/-, KCM) animals with a 50% reduction in PanIN-2 and 70% reduction in PanIN-3 lesions compared with KC at 50 weeks of age. High-throughput RNA-sequencing analysis from pancreatic tissues of KCM animals revealed a significant decrease in cancer stem cell (CSC) markers Aldh1a1, Klf4, EpCAM, and CD133. Furthermore, the silencing of MUC5AC in human pancreatic cancer cells reduced their tumorigenic propensity, as indicated by a significant decline in tumor formation frequency by limiting dilution assay upon subcutaneous administration. The contribution of MUC5AC in CSC maintenance was corroborated by a significant decrease in tumor burden upon orthotopic implantation of MUC5AC-depleted pancreatic cancer cells. Mechanistically, MUC5AC potentiated oncogenic signaling through integrin αvβ5, pSrc (Y416), and pSTAT3 (Y705). Phosphorylated STAT3, in turn, upregulated Klf4 expression, thereby enriching the self-renewing CSC population. A strong positive correlation of Muc5ac with Klf4 and pSTAT3 in the PanIN lesions of KC mouse pancreas reinforces the crucial involvement of MUC5AC in bolstering the CSC-associated tumorigenic properties of Kras-induced metaplastic cells, which leads to pancreatic cancer onset and progression. SIGNIFICANCE: This study elucidates that de novo expression of MUC5AC promotes cancer cell stemness during Kras-driven pancreatic tumorigenesis and can be targeted for development of a novel therapeutic regimen.

SIRT1–NOX4 signaling axis regulates cancer cachexia

Abstract: Approximately one third of cancer patients die due to complexities related to cachexia. However, the mechanisms of cachexia and the potential therapeutic interventions remain poorly studied. We observed a significant positive correlation between SIRT1 expression and muscle fiber cross-sectional area in pancreatic cancer patients. Rescuing Sirt1 expression by exogenous expression or pharmacological agents reverted cancer cell-induced myotube wasting in culture conditions and mouse models. RNA-seq and follow-up analyses showed cancer cell-mediated SIRT1 loss induced NF-κB signaling in cachectic muscles that enhanced the expression of FOXO transcription factors and NADPH oxidase 4 (Nox4), a key regulator of reactive oxygen species production. Additionally, we observed a negative correlation between NOX4 expression and skeletal muscle fiber cross-sectional area in pancreatic cancer patients. Knocking out Nox4 in skeletal muscles or pharmacological blockade of Nox4 activity abrogated tumor-induced cachexia in mice. Thus, we conclude that targeting the Sirt1-Nox4 axis in muscles is an effective therapeutic intervention for mitigating pancreatic cancer-induced cachexia.

Sulfation modulates the targeting properties of hyaluronic acid to P-selectin and CD44.

Abstract: Many targeting strategies can be employed to direct nanoparticles to tumors for imaging and therapy. However, tumors display a dynamic, heterogeneous microenvironment that undergoes spatiotemporal changes, including the expression of targetable cell-surface biomarkers. Here, we develop a nanoparticle system to effectively target two receptors overexpressed in the microenvironment of aggressive tumors. Hyaluronic acid (HA) was regioselectivity modified using a multi-step synthetic approach to alter binding specificities for CD44 and P-selectin to tumor cell interaction. The dual-targeting strategy utilizes sulfate modifications on HA that targets P-selectin, in addition to native targeting of CD44, which exploits spatiotemporal alterations in the expression patterns of these two receptors in cancer sites. Using biophysical characterization and in vitro studies, we demonstrate that modified HA nanoparticles effectively targets both P-selectin+ and CD44+ cells, which lays the groundwork for future in vivo biomedical applications.

Genomic and Epigenomic Landscaping Defines New Therapeutic Targets for Adenosquamous Carcinoma of the Pancreas.

Abstract: Adenosquamous cancer of the pancreas (ASCP) is a subtype of pancreatic cancer that has a worse prognosis and greater metastatic potential than the more common pancreatic ductal adenocarcinoma (PDAC) subtype. To distinguish the genomic landscape of ASCP and identify actionable targets for this lethal cancer, we applied DNA content flow cytometry to a series of 15 tumor samples including five patient-derived xenografts (PDX). We interrogated purified sorted tumor fractions from these samples with whole-genome copy-number variant (CNV), whole-exome sequencing, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analyses. These identified a variety of somatic genomic lesions targeting chromatin regulators in ASCP genomes that were superimposed on well-characterized genomic lesions including mutations in TP53 (87%) and KRAS (73%), amplification of MYC (47%), and homozygous deletion of CDKN2A (40%) that are common in PDACs. Furthermore, a comparison of ATAC-seq profiles of three ASCP and three PDAC genomes using flow-sorted PDX models identified genes with accessible chromatin unique to the ASCP genomes, including the lysine methyltransferase SMYD2 and the pancreatic cancer stem cell regulator RORC in all three ASCPs, and a FGFR1-ERLIN2 fusion associated with focal CNVs in both genes in a single ASCP. Finally, we demonstrate significant activity of a pan FGFR inhibitor against organoids derived from the FGFR1-ERLIN2 fusion-positive ASCP PDX model. Our results suggest that the genomic and epigenomic landscape of ASCP provide new strategies for targeting this aggressive subtype of pancreatic cancer. SIGNIFICANCE: These data provide a unique description of the ASCP genomic and epigenomic landscape and identify candidate therapeutic targets for this dismal cancer.

MUC1 oncoprotein mitigates ER stress via CDA-mediated reprogramming of pyrimidine metabolism.

Abstract: The Mucin 1 (MUC1) protein is overexpressed in various cancers and mediates chemotherapy resistance. However, the mechanism is not fully understood. Given that most chemotherapeutic drugs disrupt ER homeostasis as part of their toxicity, and MUC1 expression is regulated by proteins involved in ER homeostasis, we investigated the link between MUC1 and ER homeostasis. MUC1 knockdown in pancreatic cancer cells enhanced unfolded protein response (UPR) signaling and cell death upon ER stress induction. Transcriptomic analysis revealed alterations in the pyrimidine metabolic pathway and cytidine deaminase (CDA). ChIP and CDA activity assays showed that MUC1 occupied CDA gene promoter upon ER stress induction correlating with increased CDA expression and activity in MUC1-expressing cells as compared with MUC1 knockdown cells. Inhibition of either the CDA or pyrimidine metabolic pathway diminished survival in MUC1-expressing cancer cells upon ER stress induction. Metabolomic analysis demonstrated that MUC1-mediated CDA activity corresponded to deoxycytidine to deoxyuridine metabolic reprogramming upon ER stress induction. The resulting increase in deoxyuridine mitigated ER stress-induced cytotoxicity. In addition, given (1) the established roles of MUC1 in protecting cells against reactive oxygen species (ROS) insults, (2) ER stress-generated ROS further promote ER stress and (3) the emerging anti-oxidant property of deoxyuridine, we further investigated if MUC1 regulated ER stress by a deoxyuridine-mediated modulation of ROS levels. We observed that deoxyuridine could abrogate ROS-induced ER stress to promote cancer cell survival. Taken together, our findings demonstrate a novel MUC1-CDA axis of the adaptive UPR that provides survival advantage upon ER stress induction.

Sildenafil Potentiates the Therapeutic Efficacy of Docetaxel in Advanced Prostate Cancer by Stimulating NO-cGMP Signaling

Abstract: Purpose: Docetaxel plays an indispensable role in the management of advanced prostate cancer. However, more than half of patients do not respond to docetaxel, and those good responders frequently experience significant cumulative toxicity, which limits its dose duration and intensity. Hence, a second agent that could increase the initial efficacy of docetaxel and maintain tolerability at biologically effective doses may improve outcomes for patients. Experimental Design: We determined phosphodiesterase 5 (PDE5) expression levels in human and genetically engineered mouse (GEM) prostate tissues and tumor-derived cell lines. Furthermore, we investigated the therapeutic benefits and underlying mechanism of PDE5 inhibitor sildenafil in combination with docetaxel using in vitro, Pten conditional knockout (cKO), derived tumoroid and xenograft prostate cancer models. Results: PDE5 expression was higher in both human and mouse prostate tumors and cancer cell lines compared with normal tissues/cells. In GEM prostate-derived cell lines, PDE5 expression increased from normal prostate (wild-type) epithelial cells to androgen-dependent and castrated prostate-derived cell lines. The addition of physiologically achievable concentrations of sildenafil enhanced docetaxel-induced prostate cancer cell growth inhibition and apoptosis in vitro, reduced murine 3D tumoroid growth, and in vivo tumorigenicity as compared with docetaxel alone. Furthermore, sildenafil enhanced docetaxel-induced NO and cGMP levels thereby augmenting antitumor activity. Conclusions: Our results demonstrate that sildenafil9s addition could sensitize docetaxel chemotherapy in prostate cancer cells at much lesser concentration than needed for inducing cell death. Thus, the combinatorial treatment of sildenafil and docetaxel may improve anticancer efficacy and reduce chemotherapy-induced side-effects among patients with advanced prostate cancer.

Global analysis of human glycosyltransferases reveals novel targets for pancreatic cancer pathogenesis.

Abstract: Several reports have shown the role of glycosylation in pancreatic cancer (PC), but a global systematic screening of specific glycosyltransferases (glycoTs) in its progression remains unknown. We demonstrate a rigorous top-down approach using TCGA-based RNA-Seq analysis, multi-step validation using RT-qPCR, immunoblots and immunohistochemistry. We identified six unique glycoTs (B3GNT3, B4GALNT3, FUT3, FUT6, GCNT3 and MGAT3) in PC pathogenesis and studied their function using CRISPR/Cas9-based KD systems. Serial metastatic in vitro models using T3M4 and HPAF/CD18, generated in house, exhibited decreases in B3GNT3, FUT3 and GCNT3 expression on increasing metastatic potential. Immunohistochemistry identified clinical significance for GCNT3, B4GALNT3 and MGAT3 in PC. Furthermore, the effects of B3GNT3, FUT3, GCNT3 and MGAT3 were shown on proliferation, migration, EMT and stem cell markers in CD18 cell line. Talniflumate, GCNT3 inhibitor, reduced colony formation and migration in T3M4 and CD18 cells. Moreover, we found that loss of GCNT3 suppresses PC progression and metastasis by downregulating cell cycle genes and β-catenin/MUC4 axis. For GCNT3, proteomics revealed downregulation of MUC5AC, MUC1, MUC5B including many other proteins. Collectively, we demonstrate a critical role of O- and N-linked glycoTs in PC progression and delineate the mechanism encompassing the role of GCNT3 in PC.

The Multifaceted Roles of the Tumor Susceptibility Gene 101 (TSG101) in Normal Development and Disease.

Abstract: The multidomain protein encoded by the Tumor Susceptibility Gene 101 (TSG101) is ubiquitously expressed and is suggested to function in diverse intracellular processes. In this review, we provide a succinct overview of the main structural features of the protein and their suggested roles in molecular and cellular functions. We then summarize, in more detail, key findings from studies using genetically engineered animal models that demonstrate essential functions of TSG101 in cell proliferation and survival, normal tissue homeostasis, and tumorigenesis. Despite studies on cell lines that provide insight into the molecular underpinnings by which TSG101 might function as a negative growth regulator, a biologically significant role of TSG101 as a tumor suppressor has yet to be confirmed using genuine in vivo cancer models. More recent observations from several cancer research teams suggest that TSG101 might function as an oncoprotein. A potential role of post-translational mechanisms that control the expression of the TSG101 protein in cancer is being discussed. In the final section of the review, we summarize critical issues that need to be addressed to gain a better understanding of biologically significant roles of TSG101 in cancer.

DNA polymerase δ proofreads errors made by DNA polymerase ε

Abstract: During eukaryotic replication, DNA polymerases e (Pole) and δ (Polδ) synthesize the leading and lagging strands, respectively. In a long-known contradiction to this model, defects in the fidelity of Pole have a much weaker impact on mutagenesis than analogous Polδ defects. It has been previously proposed that Polδ contributes more to mutation avoidance because it proofreads mismatches created by Pole in addition to its own errors. However, direct evidence for this model was missing. We show that, in yeast, the mutation rate increases synergistically when a Pole nucleotide selectivity defect is combined with a Polδ proofreading defect, demonstrating extrinsic proofreading of Pole errors by Polδ. In contrast, combining Polδ nucleotide selectivity and Pole proofreading defects produces no synergy, indicating that Pole cannot correct errors made by Polδ. We further show that Polδ can remove errors made by exonuclease-deficient Pole in vitro. These findings illustrate the complexity of the one-strand-one-polymerase model where synthesis appears to be largely divided, but Polδ proofreading operates on both strands.

Metabolic Subtyping for Novel Personalized Therapies Against Pancreatic Cancer

Abstract: Through metabolic subtyping, metabolic vulnerabilities can be exploited for developing efficacious treatments. A glycolytic subtype indicates poor survival in patients with pancreatic cancer, whereas a cholesterogenic subtype correlates with better outcomes potentially due to more energy expenditure. Personalized medicine holds great promise for improving therapy outcomes by optimally targeting metabolic pathways.See related article by Karasinska et al., p. 135.