Showing papers by "Eppley Institute for Research in Cancer and Allied Diseases published in 2017"
Eppley Institute for Research in Cancer and Allied Diseases1, University of Nebraska Medical Center2, University of Nebraska–Lincoln3, University of Texas MD Anderson Cancer Center4, Cornell University5, University of Málaga6, Harvard University7, University of Texas at Dallas8, University of Colorado Denver9, Stony Brook University10, University of Michigan11
TL;DR: A widely prevalent mechanism of resistance to gemcitabine in pancreatic cancer is established, whereby increased glycolytic flux leads to glucose addiction in cancer cells and a corresponding increase in pyrimidine biosynthesis to enhance the intrinsic levels of deoxycytidine triphosphate (dCTP).
331 citations
TL;DR: This study used an organoid culture system to investigate how transcription and the enhancer landscape become altered during discrete stages of disease progression in a PDA mouse model, and revealed that the metastatic transition is accompanied by massive and recurrent alterations in enhancer activity.
311 citations
TL;DR: This work reports the development of a heterobifunctional small molecule proteolysis targeting chimera (PROTAC) capable of cereblon (CRBN) mediated proteasomal degradation of CDK9 in HCT116 cells, the first example of a PROTAC that selectively degradesCDK9.
159 citations
TL;DR: An under-appreciated property of SOX2, its levels in actively proliferating tumor cells appear to be optimized to maximize tumor growth - too little or too muchSOX2 dramatically alters tumor growth, which will help design strategies for more effectively treating some of the most deadly cancers.
Abstract: // Erin L. Wuebben 1 and Angie Rizzino 1,2 1 Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA 2 Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA Correspondence to: Angie Rizzino, email: // Keywords : SOX2, cancer, tumor progression, tumor-initiating cells, cancer stem cell markers Received : December 20, 2016 Accepted : March 16, 2017 Published : March 25, 2017 Abstract The pluripotency-associated transcription factor SOX2 is essential during mammalian embryogenesis and later in life, but SOX2 expression can also be highly detrimental. Over the past 10 years, SOX2 has been shown to be expressed in at least 25 different cancers. This review provides a comprehensive overview of the roles of SOX2 in cancer and focuses on two broad topics. The first delves into the expression and function of SOX2 in cancer focusing on the connection between SOX2 levels and tumor grade as well as patient survival. As part of this discussion, we address the developing connection between SOX2 expression and tumor drug resistance. We also call attention to an under-appreciated property of SOX2, its levels in actively proliferating tumor cells appear to be optimized to maximize tumor growth - too little or too much SOX2 dramatically alters tumor growth. The second topic of this review focuses on the exquisite array of molecular mechanisms that control the expression and transcriptional activity of SOX2. In addition to its complex regulation at the transcriptional level, SOX2 expression and activity are controlled carefully by microRNAs, long non-coding RNAs, and post-translational modifications. In the Conclusion and Future Perspectives section, we point out that there are still important unanswered questions. Addressing these questions is expected to lead to new insights into the functions of SOX2 in cancer, which will help design novels strategies for more effectively treating some of the most deadly cancers.
158 citations
TL;DR: The hypothesis that the improvement of inflammatory anemia by MMB results from inhibition of ACVR1-mediated hepcidin expression in the liver, which leads to increased mobilization of sequestered iron from cellular stores and subsequent stimulation of erythropoiesis, is supported.
138 citations
TL;DR: It is demonstrated that fatty acid biosynthesis pathway manipulation can help overcome the gemcitabine resistance in pancreatic cancer by regulating ER stress and stemness.
Abstract: Pancreatic adenocarcinoma is moderately responsive to gemcitabine-based chemotherapy, the most widely used single-agent therapy for pancreatic cancer. Although the prognosis in pancreatic cancer remains grim in part due to poor response to therapy, previous attempts at identifying and targeting the resistance mechanisms have not been very successful. By leveraging The Cancer Genome Atlas dataset, we identified lipid metabolism as the metabolic pathway that most significantly correlated with poor gemcitabine response in pancreatic cancer patients. Furthermore, we investigated the relationship between alterations in lipogenesis pathway and gemcitabine resistance by utilizing tissues from the genetically engineered mouse model and human pancreatic cancer patients. We observed a significant increase in fatty acid synthase (FASN) expression with increasing disease progression in spontaneous pancreatic cancer mouse model, and a correlation of high FASN expression with poor survival in patients and poor gemcitabine responsiveness in cell lines. We observed a synergistic effect of FASN inhibitors with gemcitabine in pancreatic cancer cells in culture and orthotopic implantation models. Combination of gemcitabine and the FASN inhibitor orlistat significantly diminished stemness, in part due to induction of endoplasmic reticulum (ER) stress that resulted in apoptosis. Moreover, direct induction of ER stress with thapsigargin caused a similar decrease in stemness and showed synergistic activity with gemcitabine. Our in vivo studies with orthotopic implantation models demonstrated a robust increase in gemcitabine responsiveness upon inhibition of fatty acid biosynthesis with orlistat. Altogether, we demonstrate that fatty acid biosynthesis pathway manipulation can help overcome the gemcitabine resistance in pancreatic cancer by regulating ER stress and stemness. Cancer Res; 77(20); 5503-17. ©2017 AACR.
120 citations
TL;DR: MUC5AC is a valuable diagnostic biomarker, either alone or in combination with CA19-9, to differentiate PC from CP and benign controls and significantly improved the diagnostic accuracy for differentiating resectable cases from controls.
102 citations
TL;DR: These studies indicated that while both deacetylation and sulfation of HA individually decrease CD44 interaction, both chemical modifications are required to minimize interaction with CD44+ cells.
Abstract: CD44 is a widely-distributed type I transmembrane glycoprotein that binds hyaluronic acid (HA) in most cell types, including primary tumor cells and cancer-initiating cells and has roles in cell migration, cell-cell, and cell-matrix adhesion. HA-derived conjugates and nanoparticles that target the CD44 receptor on cells have been reported for targeted delivery of therapeutics and imaging agents. Altering crucial interactions of HA with CD44 active sites holds significant importance in modulating targeting ability of hyaluronic acid to other cancer types that do not express the CD44 receptor or minimizing the interaction with CD44+ cells that are not target cells. The approach adopted here was deacetylation of the N-acetyl group and selective sulfation on the C6-OH on the HA polymer, which form critical interactions with the CD44 active site. Major interactions identified by molecular modeling were confirmed to be hydrogen bonding of the C6-OH with Tyr109 and hydrophobic interaction of the N-acetyl group with Tyr46, 83 and Ile 92. Modified HA was synthesized and characterized and its interactions were assessed by in vitro and molecular modeling approaches. In vitro techniques included flow cytometry and fluorescence polarization, while in silico approaches included docking and binding calculations by a MM-PBSA approach. These studies indicated that while both deacetylation and sulfation of HA individually decrease CD44 interaction, both chemical modifications are required to minimize interaction with CD44+ cells. The results of this study represent the first step to effective retargeting of HA-derived NPs for imaging and drug delivery.
98 citations
TL;DR: Current understanding of the consequences of DNA polymerase mutations in cancers and the mechanisms of their mutator effects are summarized and likely explanations for a high recurrence of some but not other polymerase variants are discussed.
76 citations
TL;DR: The studies suggest that targeting anaplerotic glutamine metabolism may serve as an important therapeutic target in PDAC and suggest that GOT1 plays an important role in energy metabolism and ROS balance in chronic acidosis stress.
68 citations
TL;DR: Findings suggest that the TCR repertoire is a key determinant of the tumor microenvironment in DLBCL treated with conventional frontline therapy and highly dominant T-cell clonal expansions within the TME are associated with poor outcome.
Abstract: Purpose: To investigate the relationship between the intra-tumoral T-cell receptor (TCR) repertoire and the tumor microenvironment (TME) in de novo diffuse large B-cell lymphoma (DLBCL) and the impact of TCR on survival.Experimental Design: We performed high-throughput unbiased TCRβ sequencing on a population-based cohort of 92 patients with DLBCL treated with conventional (i.e., non-checkpoint blockade) frontline "R-CHOP" therapy. Key immune checkpoint genes within the TME were digitally quantified by nanoString. The primary endpoints were 4-year overall survival (OS) and progression-free survival (PFS).Results: The TCR repertoire within DLBCL nodes was abnormally narrow relative to non-diseased nodal tissues (P < 0.0001). In DLBCL, a highly dominant single T-cell clone was associated with inferior 4-year OS rate of 60.0% [95% confidence interval (CI), 31.7%-79.6%], compared with 79.8% in patients with a low dominant clone (95% CI, 66.7%-88.5%; P = 0.005). A highly dominant clone also predicted inferior 4-year PFS rate of 46.6% (95% CI, 22.5%-76.6%) versus 72.6% (95% CI, 58.8%-82.4%, P = 0.008) for a low dominant clone. In keeping, clonal expansions were most pronounced in the EBV+ DLBCL subtype that is known to express immunogenic viral antigens and is associated with particularly poor outcome. Increased T-cell diversity was associated with significantly elevated PD-1, PD-L1, and PD-L2 immune checkpoint molecules.Conclusions: Put together, these findings suggest that the TCR repertoire is a key determinant of the TME. Highly dominant T-cell clonal expansions within the TME are associated with poor outcome in DLBCL treated with conventional frontline therapy. Clin Cancer Res; 23(7); 1820-8. ©2016 AACR.
TL;DR: Based on its ability to provide self-sufficiency in growth signals that are also capable of overriding intrinsic cell death programs, persistently active STAT5 can serve as a potent oncoprotein that contributes to the genesis of breast cancer.
TL;DR: MUC1-mediated nucleotide metabolism plays a key role in facilitating radiation resistance in pancreatic cancer and is targeted effectively through glycolytic inhibition.
Abstract: Purpose:MUC1, an oncogene overexpressed in multiple solid tumors, including pancreatic cancer, reduces overall survival and imparts resistance to radiation and chemotherapies. We previously identified that MUC1 facilitates growth-promoting metabolic alterations in pancreatic cancer cells. The present study investigates the role of MUC1-mediated metabolism in radiation resistance of pancreatic cancer by utilizing cell lines and in vivo models.Experimental Design: We used MUC1-knockdown and -overexpressed cell line models for evaluating the role of MUC1-mediated metabolism in radiation resistance through in vitro cytotoxicity, clonogenicity, DNA damage response, and metabolomic evaluations. We also investigated whether inhibition of glycolysis could revert MUC1-mediated metabolic alterations and radiation resistance by using in vitro and in vivo models.Results: MUC1 expression diminished radiation-induced cytotoxicity and DNA damage in pancreatic cancer cells by enhancing glycolysis, pentose phosphate pathway, and nucleotide biosynthesis. Such metabolic reprogramming resulted in high nucleotide pools and radiation resistance in in vitro models. Pretreatment with the glycolysis inhibitor 3-bromopyruvate abrogated MUC1-mediated radiation resistance both in vitro and in vivo, by reducing glucose flux into nucleotide biosynthetic pathways and enhancing DNA damage, which could again be reversed by pretreatment with nucleoside pools.Conclusions: MUC1-mediated nucleotide metabolism plays a key role in facilitating radiation resistance in pancreatic cancer and targeted effectively through glycolytic inhibition. Clin Cancer Res; 23(19); 5881-91. ©2017 AACR.
TL;DR: Findings indicate a significant role of MUC16 in tumorigenesis and metastasis of lung cancer cells possibly via regulation of TSPYL5 through the JAK2/STAT3/GR axis.
Abstract: Purpose: MUC16, a tumor biomarker and cell surface-associated mucin, is overexpressed in various cancers; however, its role in lung cancer pathogenesis is unknown. Here, we have explored the mechanistic role of MUC16 in lung cancer.Experimental Design: To identify the functional role of MUC16, stable knockdown was carried in lung cancer cells with two different shRNAs. Clinical significance of MUC16 was evaluated in lung cancer patient tissues using IHC. We have generated genetically engineered mouse model (KrasG12D; AdCre) to evaluate the preclinical significance of MUC16.Results: MUC16 was overexpressed (P = 0.03) in lung cancer as compared with normal tissues. MUC16 knockdown (KD) in lung cancer cell lines decreased the in vitro growth rate (P < 0.05), migration (P < 0.001), and in vivo tumor growth (P = 0.007), whereas overexpression of MUC16-carboxyl terminal (MUC16-Cter) resulted in increased growth rate (P < 0.001). Transcriptome analysis of MUC16 KD showed a downregulation (P = 0.005) of TSPYL5 gene, which encodes for a testis-specific Y-like protein. Rescue studies via overexpression of MUC16-Cter in MUC16 KD cells showed activation of signaling proteins, such as JAK2 (Y1007/1008), STAT3 (Y705), and glucocorticoid receptor (GR), which constitutes an important axis for the regulation of TSPYL5 for oncogenic process. Further, inhibition of STAT3 (Y705) led to decreased GR and TSPYL5, suggesting that MUC16 regulates TSPYL5 through the JAK2/STAT3/GR axis. Also, MUC16 overexpression induced cisplatin and gemcitabine resistance by downregulation of p53.Conclusions: Our findings indicate a significant role of MUC16 in tumorigenesis and metastasis of lung cancer cells possibly via regulation of TSPYL5 through the JAK2/STAT3/GR axis. Clin Cancer Res; 23(14); 3906-17. ©2017 AACR.
TL;DR: Studies demonstrating that abrogation of MUC4 expression reduces proliferation and metastasis of PC cells and enhances sensitivity to therapeutic agents affirm its utility as a therapeutic target, and emerging evidence supports the suitability of M UC4 as a potential immunotherapy target.
Abstract: Introduction: Pancreatic cancer (PC) is characterized by mucin overexpression. MUC4 is the most differentially overexpressed membrane-bound mucin that plays a functional role in disease progression and therapy resistance.Area covered: We describe the clinicopathological significance of MUC4, summarize mechanisms contributing to its deregulated expression, review preclinical studies aimed at inhibiting MUC4, and discuss how MUC4 overexpression provides opportunities for developing targeted therapies. Finally, we discuss the challenges for developing MUC4-based therapeutics, and identify areas where efforts should be directed to effectively exploit MUC4 as a therapeutic target for PC.Expert opinion: Studies demonstrating that abrogation of MUC4 expression reduces proliferation and metastasis of PC cells and enhances sensitivity to therapeutic agents affirm its utility as a therapeutic target. Emerging evidence also supports the suitability of MUC4 as a potential immunotherapy target. However, these ...
TL;DR: Hepatic transcription of JAK2/ARHGEF1 pathway components was upregulated in liver cirrhosis dependent on aetiology, severity and complications of human liver Cirrhosis and might be a new approach to treat cir rhosis with portal hypertension.
Abstract: Objective Angiotensin II (AngII) activates via angiotensin-II-type-I receptor (AT1R) Janus-kinase-2 (JAK2)/Arhgef1 pathway and subsequently RHOA/Rho-kinase (ROCK), which induces experimental and probably human liver fibrosis. This study investigated the relationship of JAK2 to experimental and human portal hypertension. Design The mRNA and protein levels of JAK2/ARHGEF1 signalling components were analysed in 49 human liver samples and correlated with clinical parameters of portal hypertension in these patients. Correspondingly, liver fibrosis (bile duct ligation (BDL), carbon tetrachloride (CCl 4 )) was induced in floxed- Jak2 knock-out mice with SM22-promotor (SM22 Cre+ - Jak2 f/f ). Transcription and contraction of primary myofibroblasts from healthy and fibrotic mice and rats were analysed. In two different cirrhosis models (BDL, CCl 4 ) in rats, the acute haemodynamic effect of the JAK2 inhibitor AG490 was assessed using microsphere technique and isolated liver perfusion experiments. Results Hepatic transcription of JAK2/ARHGEF1 pathway components was upregulated in liver cirrhosis dependent on aetiology, severity and complications of human liver cirrhosis (Model for End-stage Liver disease (MELD) score, Child score as well as ascites, high-risk varices, spontaneous bacterial peritonitis). SM22 Cre+ -
Jak2 f/f mice lacking Jak2 developed less fibrosis and lower portal pressure (PP) than SM22 Cre− - Jak2 f/f upon fibrosis induction. Myofibroblasts from SM22 Cre+ - Jak2 f/f mice expressed less collagen and profibrotic markers upon activation. AG490 relaxed activated hepatic stellate cells in vitro. In cirrhotic rats, AG490 decreased hepatic vascular resistance and consequently the PP in vivo and in situ. Conclusions Hepatic JAK2/ARHGEF1/ROCK expression is associated with portal hypertension and decompensation in human cirrhosis. The deletion of Jak2 in myofibroblasts attenuated experimental fibrosis and acute inhibition of JAK2 decreased PP. Thus, JAK2 inhibitors, already in clinical use for other indications, might be a new approach to treat cirrhosis with portal hypertension.
TL;DR: It is shown that R-spondin 1 (RSPO1)/LGR5 directly activates TGFβ signaling cooperatively with T GFβ type II receptor in colon cancer cells, enhancing TGF β-mediated growth inhibition and stress-induced apoptosis.
Abstract: Leucine-rich repeat containing G-protein-coupled receptor 5 (LGR5), an intestinal stem cell marker, is known to exhibit tumor suppressor activity in colon cancer, the mechanism of which is not understood. Here we show that R-spondin 1 (RSPO1)/LGR5 directly activates TGFβ signaling cooperatively with TGFβ type II receptor in colon cancer cells, enhancing TGFβ-mediated growth inhibition and stress-induced apoptosis. Knockdown of LGR5 attenuated downstream TGFβ signaling and increased cell proliferation, survival, and metastasis in an orthotopic model of colon cancer in vivo Upon RSPO1 stimulation, LGR5 formed complexes with TGFβ receptors. Studies of patient specimens indicate that LGR5 expression was reduced in advanced stages and positively correlated with markers of TGFβ activation in colon cancer. Our study uncovers a novel cross-talk between LGR5 and TGFβ signaling in colon cancer and identifies LGR5 as a new modulator of TGFβ signaling able to suppress colon cancer metastasis. Cancer Res; 77(23); 6589-602. ©2017 AACR.
TL;DR: A novel signaling axis that regulates JAK2 in normal and malignant HSPCs is revealed and new therapeutic strategies for treating CBLmut myeloid malignancies are suggested.
Abstract: Janus kinase 2 (JAK2) is a central kinase in hematopoietic stem/progenitor cells (HSPCs), and its uncontrolled activation is a prominent oncogenic driver of hematopoietic neoplasms. However, molecular mechanisms underlying the regulation of JAK2 have remained elusive. Here we report that the Casitas B-cell lymphoma (CBL) family E3 ubiquitin ligases down-regulate JAK2 stability and signaling via the adaptor protein LNK/SH2B3. We demonstrated that depletion of CBL/CBL-B or LNK abrogated JAK2 ubiquitination, extended JAK2 half-life, and enhanced JAK2 signaling and cell growth in human cell lines as well as primary murine HSPCs. Built on these findings, we showed that JAK inhibitor (JAKi) significantly reduced aberrant HSPCs and mitigated leukemia development in a mouse model of aggressive myeloid leukemia driven by loss of Cbl and Cbl-b Importantly, primary human CBL mutated (CBLmut ) leukemias exhibited increased JAK2 protein levels and signaling and were hypersensitive to JAKi. Loss-of-function mutations in CBL E3 ubiquitin ligases are found in a wide range of myeloid malignancies, which are diseases without effective treatment options. Hence, our studies reveal a novel signaling axis that regulates JAK2 in normal and malignant HSPCs and suggest new therapeutic strategies for treating CBLmut myeloid malignancies.
TL;DR: An increase in autocrine IGF1/AKT signaling is identified as a common survival mechanism in dormant cancer cells and the pharmacological inhibition of IGF-1R reduces residual disease burden and cancer recurrence, suggesting that this molecular pathway is crucial for the survival of cancer cells in the absence of the primary oncogenic drivers.
TL;DR: The human primosome is a 340-kilodalton complex of primase (DNA-dependent RNA polymerase) and DNA polymerase α, which initiates genome replication by synthesizing chimeric RNA-DNA primers for DNA polymerases δ and ε.
Abstract: The human primosome is a 340-kilodalton complex of primase (DNA-dependent RNA polymerase) and DNA polymerase α, which initiates genome replication by synthesizing chimeric RNA-DNA primers for DNA polymerases δ and ϵ. Accumulated biochemical and structural data reveal the complex mechanism of concerted primer synthesis by two catalytic centers. First, primase generates an RNA primer through three steps: initiation, consisting of dinucleotide synthesis from two nucleotide triphosphates; elongation, resulting in dinucleotide extension; and termination, owing to primase inhibition by a mature 9-mer primer. Then Polα, which works equally well on DNA:RNA and DNA:DNA double helices, intramolecularly catches the template primed by a 9mer RNA and extends the primer with dNTPs. All primosome transactions are highly coordinated by autoregulation through the alternating activation/inhibition of the catalytic centers. This coordination is mediated by the small C-terminal domain of the primase accessory subunit, which forms a tight complex with the template:primer, shuttles between the primase and DNA polymerase active sites, and determines their access to the substrate.
TL;DR: This study investigates 11 mucin expressing cancers for DNA mutations, mRNA expression, copy number, methylation, and the impacts these genomic features may have on patient survival by utilizing The Cancer Genome Atlas dataset.
Abstract: // Ryan J. King 1 , Fang Yu 2 and Pankaj K. Singh 1, 3, 4, 5 1 The Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA 2 Department of Biostatistics, University of Nebraska Medical Center, Omaha, Nebraska, USA 3 Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA 4 Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA 5 Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA Correspondence to: Pankaj K. Singh email: pankaj.singh@unmc.edu Keywords: mucins, MUC1, cancer genetics, genetic alterations, cancer genetic profiles Received: March 06, 2017 Accepted: May 02, 2017 Published: May 17, 2017 ABSTRACT The significance of mucins in cancers has led to the development of novel biomarkers and therapeutic agents against cancers. Despite significant advances in the understanding of mucins, systemic investigations into the role of mucins in cancer biology focusing particularly on the histological subtypes and stages, along with other variables, are yet to be carried out to discover potential novel functions and cancer-specific roles. Here, we investigated 11 mucin expressing cancers for DNA mutations, mRNA expression, copy number, methylation, and the impacts these genomic features may have on patient survival by utilizing The Cancer Genome Atlas dataset. We demonstrate that mucin DNA mutations have a significant rate, pattern, and impact on cancer patient survival depending on the tissue of origin. This includes a frequent T112P mutation in MUC1 that is seen in half of the pancreatic MUC1 mutations, as well as being present in other cancers. We also observed a very frequent MUC4 mutation at H4205, which correlated with survival outcomes in patients. Furthermore, we observed significant alterations in mucin mRNA expression in multiple tumor types. Our results demonstrate de novo expression of certain mucins in cancer tissues, including MUC21 in colorectal cancers. We observed a general decrease in promoter methylation for mucins, which correlated with decreased expression of many genes, such as MUC15 in kidney cancers. Lastly, several mucin gene loci demonstrated copy number increase in multiple histological subtypes. Thus, our study presents a comprehensive analysis of genomic alterations in mucins and their corresponding roles in cancer progression.
TL;DR: Findings show that macrophage JAK2 deficiency improves systemic insulin sensitivity and reduces inflammation in VAT and liver in response to metabolic stress.
Abstract: During obesity, macrophages can infiltrate metabolic tissues, and contribute to chronic low-grade inflammation, and mediate insulin resistance and diabetes. Recent studies have elucidated the metabolic role of JAK2, a key mediator downstream of various cytokines and growth factors. Our study addresses the essential role of macrophage JAK2 in the pathogenesis to obesity-associated inflammation and insulin resistance. During high-fat diet (HFD) feeding, macrophage-specific JAK2 knockout (M-JAK2−/−) mice gained less body weight compared to wildtype littermate control (M-JAK2+/+) mice and were protected from HFD-induced systemic insulin resistance. Histological analysis revealed smaller adipocytes and qPCR analysis showed upregulated expression of some adipogenesis markers in visceral adipose tissue (VAT) of HFD-fed M-JAK2−/− mice. There were decreased crown-like structures in VAT along with reduced mRNA expression of some macrophage markers and chemokines in liver and VAT of HFD-fed M-JAK2−/− mice. Peritoneal macrophages from M-JAK2−/− mice and Jak2 knockdown in macrophage cell line RAW 264.7 also showed lower levels of chemokine expression and reduced phosphorylated STAT3. However, leptin-dependent effects on augmenting chemokine expression in RAW 264.7 cells did not require JAK2. Collectively, our findings show that macrophage JAK2 deficiency improves systemic insulin sensitivity and reduces inflammation in VAT and liver in response to metabolic stress.
TL;DR: Reducing formation of depurinating estrogen‐DNA adducts can reduce the risk of developing a variety of types of human cancer, including breast cancer and prostate cancer.
Abstract: Endogenous estrogens become carcinogens when dangerous metabolites, the catechol estrogen quinones, are formed. In particular, the catechol estrogen-3,4-quinones can react with DNA to produce an excess of specific depurinating estrogen-DNA adducts. Loss of these adducts leaves apurinic sites in the DNA, generating subsequent cancer-initiating mutations. Unbalanced estrogen metabolism yields excessive catechol estrogen-3,4-quinones, increasing formation of depurinating estrogen-DNA adducts and the risk of initiating cancer. Evidence for this mechanism of cancer initiation comes from various types of studies. High levels of depurinating estrogen-DNA adducts have been observed in women with breast, ovarian or thyroid cancer, as well as in men with prostate cancer or non-Hodgkin lymphoma. Observation of high levels of depurinating estrogen-DNA adducts in high risk women before the presence of breast cancer indicates that adduct formation is a critical factor in breast cancer initiation. Formation of analogous depurinating dopamine-DNA adducts is hypothesized to initiate Parkinson's disease by affecting dopaminergic neurons. Two dietary supplements, N-acetylcysteine and resveratrol complement each other in reducing formation of catechol estrogen-3,4-quinones and inhibiting formation of estrogen-DNA adducts in cultured human and mouse breast epithelial cells. They also inhibit malignant transformation of these cells. In addition, formation of adducts was reduced in women who followed a Healthy Breast Protocol that includes N-acetylcysteine and resveratrol. When initiation of cancer is blocked, promotion, progression and development of the disease cannot occur. These results suggest that reducing formation of depurinating estrogen-DNA adducts can reduce the risk of developing a variety of types of human cancer.
TL;DR: It is demonstrated that cells with low SIRT1 levels can maintain their resistance and survival by increasing SIRT3 expression, and it is speculated that acetylated ZF5 cannot bind and sequester SP1 that is free, then, to increase Sirt3 transcription.
Abstract: Sirtuins are conserved NAD+ -dependent deacylases. SIRT1 is a nuclear and cytoplasmic sirtuin involved in the control of histones a transcription factors function. SIRT3 is a mitochondrial protein, which regulates mitochondrial function. Although, both SIRT1 and SIRT3 have been implicated in resistance to cellular stress, the link between these two sirtuins has not been studied so far. Here we aimed to unravel: i) the role of SIRT1-SIRT3 axis for cellular response to oxidative stress and DNA damage; ii) how mammalian cells modulate such SIRT1-SIRT3 axis and which mechanisms are involved. Therefore, we analyzed the response to different stress stimuli in WT or SIRT1-silenced cell lines. Our results demonstrate that SIRT1-silenced cells are more resistant to H2 O2 and etoposide treatment showing decreased ROS accumulation, γ-H2AX phosphorylation, caspase-3 activation and PARP cleavage. Interestingly, we observed that SIRT1-silenced cells show an increased SIRT3 expression. To explore such a connection, we carried out luciferase assays on SIRT3 promoter demonstrating that SIRT1-silencing increases SIRT3 promoter activity and that such an effect depends on the presence of SP1 and ZF5 recognition sequences on SIRT3 promoter. Afterwards, we performed co-immunoprecipitation assays demonstrating that SIRT1 binds and deacetylates the transcription inhibitor ZF5 and that there is a decreased interaction between SP1 and ZF5 in SIRT1-silenced cells. Therefore, we speculate that acetylated ZF5 cannot bind and sequester SP1 that is free, then, to increase SIRT3 transcription. In conclusion, we demonstrate that cells with low SIRT1 levels can maintain their resistance and survival by increasing SIRT3 expression. J. Cell. Physiol. 232: 1835-1844, 2017. © 2016 Wiley Periodicals, Inc.
TL;DR: It is demonstrated that expression of GRM3, a metabotropic glutamate receptor mainly expressed in mammalian central nervous system, is significantly upregulated in majority of human colonic adenocarcinomas tested and colon cancer cell lines, and that GRM 3 is a promising molecular target for colon cancer treatment.
Abstract: Molecular targeting is an import strategy to treat advanced colon cancer. The current study demonstrates that expression of GRM3, a metabotropic glutamate receptor mainly expressed in mammalian central nervous system, is significantly upregulated in majority of human colonic adenocarcinomas tested and colon cancer cell lines. Knockdown of GRM3 expression or inhibition of GRM3 activation in colon cancer cells reduces cell survival and anchorage-independent growth in vitro and inhibits tumor growth in vivo. Mechanistically, GRM3 antagonizes TGFβ-mediated activation of protein kinase A and inhibition of Protein kinase B (AKT). In addition, TGFβ signaling increases GRM3 protein stability and knockdown of GRM3 enhances TGFβ-mediated tumor suppressor function. Further studies indicate that miR-487b-3p directly targets GRM3. Overexpression of miR-487b-3p mimics the effects of GRM3 knockdown and suppresses the tumorigenicity of colon cancer cells in vivo. Expression of miR-487b-3p is decreased in colon adenocarcinomas and inversely correlates with GRM3 expression. Taken together, these studies indicate that upregulation of GRM3 expression is a functionally important molecular event in colon cancer, and that GRM3 is a promising molecular target for colon cancer treatment. This is particularly interesting and important from a therapeutic standpoint because numerous metabotropic glutamate receptor antagonists are available, many of which have been found unsuitable for treatment of neuropsychiatric disorders for reasons such as inability to readily penetrate blood brain barriers. As GRM3 is upregulated in colon cancer, but rarely expressed in normal peripheral tissues, targeting GRM3 with such agents would not likely cause adverse neurological or peripheral side effects, making GRM3 an attractive and specific molecular target for colon cancer treatment.
TL;DR: It is shown for the first time that expression and activation of IRS-1, an IGF-1R adaptor protein, is decreased by TGFβ/Smad3 signaling, indicating that IRS- 1 could be a potential therapeutic target for colon cancer treatment.
Abstract: In this study, we have uncovered a novel crosstalk between TGFβ and IGF-1R signaling pathways. We show for the first time that expression and activation of IRS-1, an IGF-1R adaptor protein, is decreased by TGFβ/Smad3 signaling. Loss or attenuation of TGFβ activation leads to elevated expression and phosphorylation of IRS-1 in colon cancer cells, resulting in enhanced cell proliferation, decreased apoptosis and increased tumor growth in vitro and in vivo. Downregulation of IRS-1 expression reversed Smad3 knockdown-mediated oncogenic phenotypes, indicating that TGFβ/Smad3 signaling inhibits cell proliferation and increases apoptosis at least partially through the inhibition of IRS-1 expression and activation. Additionally, the TGFβ/Smad3/IRS-1 signaling axis regulates expression of cyclin D1 and XIAP, which may contribute to TGFβ/Smad3/IRS-1-mediated cell cycle progression and survival. Given that loss of TGFβ signaling occurs frequently in colon cancer, an important implication of our study is that IRS-1 could be a potential therapeutic target for colon cancer treatment.
TL;DR: It is suggested that MUC1 serves as a metabolic regulator in TNBC, facilitating the metabolic reprogramming of glutamine utilization that influences TNBC tumor growth.
Abstract: Background Mucin1 (MUC1), a glycoprotein associated with chemoresistance and an aggressive cancer phenotype, is aberrantly overexpressed in triple-negative breast cancer (TNBC). Recent studies suggest that MUC1 plays a role in modulating cancer cell metabolism and thereby supports tumor growth. Herein, we examined the role of MUC1 in metabolic reprogramming in TNBC. Methods MUC1 was stably overexpressed in MDA-MB-231 TNBC cells and stably knocked down in MDA-MB-468 cells. We performed liquid chromatography-coupled tandem mass spectrometry-assisted metabolomic analyses and physiological assays, which indicated significant alterations in the metabolism of TNBC cells due to MUC1 expression. Results Differential analyses identified significant differences in metabolic pathways implicated in cancer cell growth. In particular, MUC1 expression altered glutamine dependency of the cells, which can be attributed in part to the changes in the expression of genes that regulate glutamine metabolism, as observed by real-time PCR analysis. Furthermore, MUC1 expression altered the sensitivity of cells to transaminase inhibitor aminooxyacetate (AOA), potentially by altering glutamine metabolism. Conclusions Collectively, these results suggest that MUC1 serves as a metabolic regulator in TNBC, facilitating the metabolic reprogramming of glutamine utilization that influences TNBC tumor growth.
TL;DR: The canonical role of K SR in cells is summarized, including its central role as a scaffold protein for the Raf/MEK/ERK kinase cascade, its regulation of various cellular pathways mediated through different binding partners, and the phenotypic consequences of KSR1 or KSR2 genetic inactivation.
Abstract: Many cancers, including those of the colon, lung, and pancreas, depend upon the signaling pathways induced by mutated and constitutively active Ras. The molecular scaffolds Kinase Suppressor of Ras 1 and 2 (KSR1 and KSR2) play potent roles in promoting Ras-mediated signaling through the Raf/MEK/ERK kinase cascade. Here we summarize the canonical role of KSR in cells, including its central role as a scaffold protein for the Raf/MEK/ERK kinase cascade, its regulation of various cellular pathways mediated through different binding partners, and the phenotypic consequences of KSR1 or KSR2 genetic inactivation. Mammalian KSR proteins have a demonstrated role in cellular and organismal energy balance with implications for cancer and obesity. Targeting KSR1 in cancer using small molecule inhibitors has potential for therapy with reduced toxicity to the patient. RNAi and small molecule screens using KSR1 as a reference standard have the potential to expose and target vulnerabilities in cancer. Interestingly, although KSR1 and KSR2 are similar in structure, KSR2 has a distinct physiological role in regulating energy balance. Although KSR proteins have been studied for two decades, additional analysis is required to elucidate both the regulation of these molecular scaffolds and their potent effect on the spatial and temporal control of ERK activation in health and disease.
TL;DR: Small molecule inhibitors that target the nucleotide-binding site of Rac1 are identified through in silico screening and functional studies indicate that both compounds reduced cell proliferation and migration in a dose-dependent manner in multiple pancreatic cancer cell lines.
Abstract: Aberrant activation of Rho GTPase Rac1 has been observed in various tumor types, including pancreatic cancer. Rac1 activates multiple signaling pathways that lead to uncontrolled proliferation, invasion and metastasis. Thus, inhibition of Rac1 activity is a viable therapeutic strategy for proliferative disorders such as cancer. Here we identified small molecule inhibitors that target the nucleotide-binding site of Rac1 through in silico screening. Follow up in vitro studies demonstrated that two compounds blocked active Rac1 from binding to its effector PAK1. Fluorescence polarization studies indicate that these compounds target the nucleotide-binding site of Rac1. In cells, both compounds blocked Rac1 binding to its effector PAK1 following EGF-induced Rac1 activation in a dose-dependent manner, while showing no inhibition of the closely related Cdc42 and RhoA activity. Furthermore, functional studies indicate that both compounds reduced cell proliferation and migration in a dose-dependent manner in multiple pancreatic cancer cell lines. Additionally, the two compounds suppressed the clonogenic survival of pancreatic cancer cells, while they had no effect on the survival of normal pancreatic ductal cells. These compounds do not share the core structure of the known Rac1 inhibitors and could serve as additional lead compounds to target pancreatic cancers with high Rac1 activity.
TL;DR: Interestingly, phosphatase 1 nuclear targeting subunit (PNUTS), an inhibitory regulator of PP1, is also recruited to DNA damage sites to promote NHEJ, suggesting that PNUTS and PP1 together fine-tune the dynamic phosphorylation of DNA-PKcs after DNA damage to mediate N HEJ.
Abstract: DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a key role in mediating non-homologous end joining (NHEJ), a major repair pathway for DNA double-strand breaks (DSBs). The activation, function and dynamics of DNA-PKcs is regulated largely by its reversible phosphorylation at numerous residues, many of which are targeted by DNA-PKcs itself. Interestingly, these DNA-PKcs phosphorylation sites function in a distinct, and sometimes opposing manner, suggesting that they are differentially regulated via complex actions of both kinases and phosphatases. In this study we identified several phosphatase subunits as potential DSB-associated proteins. In particular, protein phosphatase 1 (PP1) is recruited to a DSB-mimicking substrate in Xenopus egg extracts and sites of laser microirradiation in human cells. Depletion of PP1 impairs NHEJ in both Xenopus egg extracts and human cells. PP1 binds multiple motifs of DNA-PKcs, regulates DNA-PKcs phosphorylation, and is required for DNA-PKcs activation after DNA damage. Interestingly, phosphatase 1 nuclear targeting subunit (PNUTS), an inhibitory regulator of PP1, is also recruited to DNA damage sites to promote NHEJ. PNUTS associates with the DNA-PK complex and is required for DNA-PKcs phosphorylation at Ser-2056 and Thr-2609. Thus, PNUTS and PP1 together fine-tune the dynamic phosphorylation of DNA-PKcs after DNA damage to mediate NHEJ.