Cardioprotection and Suppression of Fibrosis by Diverse Cancer and Non-Cancer Cell Lines in a Murine Model of Duchenne Muscular Dystrophy.

The dynamic relationship between heart failure and cancer poses a dual challenge. While cardiac remodeling can promote cancer growth and metastasis, tumor development can ameliorate cardiac dysfunction and suppress fibrosis. However, the precise mechanism through which cancer influences the heart and fibrosis is yet to be uncovered. To further explore the interaction between heart failure and cancer, we used the MDX mouse model, which suffers from cardiac fibrosis and cardiac dysfunction. A previous study from our lab demonstrated that tumor growth improves cardiac dysfunction and dampens fibrosis in the heart and diaphragm muscles of MDX mice. We used breast Polyoma middle T (PyMT) and Lewis lung carcinoma (LLC) cancer cell lines that developed into large tumors. To explore whether the aggressiveness of the cancer cell line is crucial for the beneficial phenotype, we employed a PyMT breast cancer cell line lacking integrin ß1, representing a less aggressive cell line compared to the original PyMT cells. In addition, we examined immortalized and primary MEF cells. The injection of integrin ß1 KO PyMT cancer cells and Mouse Embryo Fibroblasts cells (MEF) resulted in the improvement of cardiac function and decreased fibrosis in the heart, diaphragm, and skeletal muscles of MDX mice. Collectively, our data demonstrate that the cancer line aggressiveness as well as primary MEF cells are sufficient to impose the beneficial phenotype. These discoveries present potential novel clinical therapeutic approaches with beneficial outcome for patients with fibrotic diseases and cardiac dysfunction that do not require tumor growth.

Tumor Growth Ameliorates Cardiac Dysfunction and Suppresses Fibrosis in a Mouse Model for Duchenne Muscular Dystrophy.

The interplay between heart failure and cancer represents a double-edged sword. Whereas cardiac remodeling promotes cancer progression, tumor growth suppresses cardiac hypertrophy and reduces fibrosis deposition. Whether these two opposing interactions are connected awaits to be determined. In addition, it is not known whether cancer affects solely the heart, or if other organs are affected as well. To explore the dual interaction between heart failure and cancer, we studied the human genetic disease Duchenne Muscular Dystrophy (DMD) using the MDX mouse model. We analyzed fibrosis and cardiac function as well as molecular parameters by multiple methods in the heart, diaphragm, lungs, skeletal muscles, and tumors derived from MDX and control mice. Surprisingly, cardiac dysfunction in MDX mice failed to promote murine cancer cell growth. In contrast, tumor-bearing MDX mice displayed reduced fibrosis in the heart and skeletal and diaphragm muscles, resulting in improved cardiac function. The latter is at least partially mediated via M2 macrophage recruitment to the heart and diaphragm muscles. Collectively, our data support the notion that the effect of heart failure on tumor promotion is independent of the improved cardiac function in tumor-bearing mice. Reduced fibrosis in tumor-bearing MDX mice stems from the suppression of new fibrosis synthesis and the removal of existing fibrosis. These findings offer potential therapeutic strategies for DMD patients, fibrotic diseases, and cardiac dysfunction.

Heart Failure Promotes Cancer Progression in an Integrin ß1-Dependent Manner.

Heart failure and cancer are currently the deadliest diseases in the Western world, posing the most pressing clinical challenges that remain unmet today. Both conditions share similar risk factors, including age, genetics, lifestyle, chronic inflammation, stress, and more. Furthermore, medications that are being used to counteract cancer frequently result in cardiotoxicity and the spontaneous emergence of heart failure. Thus, heart failure and cancer display an intimate connection and share similarities. Recent studies show that cardiac remodeling and heart failure promote cancer progression and metastasis. Using three different mouse models for heart failure revealed that the communication between the remodeled heart and the tumor is facilitated through multiple secreted factors. Among these factors, Periostin was consistently found to be elevated in all models and was shown to be required in vitro. Yet, whether Periostin is necessary for tumor promotion in vivo is unknown. Towards this end, we examined tumor promotion in mice lacking Periostin following transverse aortic constriction (TAC). Despite the loss of Periostin, tumor growth was promoted in the TAC-operated mice. This likely occurred due to increased levels of various cytokines and growth factors in Periostin KO mice. Many of these factors are potential ligands of Integrin receptors. Therefore, we next studied the role of Integrin receptors in the tumor-promotion phenotype following heart failure. We generated cancer cells with an Integrin ß1 loss of function mutation and examined tumor growth in the presence and absence of heart failure. Integrin ß1 KO cancer cells fail to display cardiac-remodeling-dependent tumor-promotion. Interestingly, a previous study showed that renal cell carcinoma cells (Renca) fail to be promoted following a myocardial infarction. Consistently, we show that Renca cells do not respond to secreted factors derived from the failing heart both in vitro and in vivo. Interestingly, Renca cells display low basal mRNA levels of Integrin ß1 which may explain the inability of heart failure to promote their growth. The findings may have significant clinical relevance to cardio-oncology patients who suffer from cancers with high levels of Integrin ß1. Chemotherapy leading to cardiotoxicity in these patients may generate a vicious cycle with poor prognosis.

Early Cardiac Remodeling Promotes Tumor Growth and Metastasis.

BACKGROUND: Recent evidence suggests that cancer and cardiovascular diseases are associated. Chemotherapy drugs are known to result in cardiotoxicity, and studies have shown that heart failure and stress correlate with poor cancer prognosis. However, whether cardiac remodeling in the absence of heart failure is sufficient to promote cancer is unknown. METHODS: To investigate the effect of early cardiac remodeling on tumor growth and metastasis colonization, we used transverse aortic constriction (TAC), a model for pressure overload-induced cardiac hypertrophy, and followed it by cancer cell implantation. RESULTS: TAC-operated mice developed larger primary tumors with a higher proliferation rate and displayed more metastatic lesions compared with controls. Serum derived from TAC-operated mice potentiated cancer cell proliferation in vitro, suggesting the existence of secreted tumor-promoting factors. Using RNA-sequencing data, we identified elevated mRNA levels of periostin in the hearts of TAC-operated mice. Periostin levels were also found to be high in the serum after TAC. Depletion of periostin from the serum abrogated the proliferation of cancer cells; conversely, the addition of periostin enhanced cancer cell proliferation in vitro. This is the first study to show that early cardiac remodeling nurtures tumor growth and metastasis and therefore promotes cancer progression. CONCLUSIONS: Our study highlights the importance of early diagnosis and treatment of cardiac remodeling because it may attenuate cancer progression and improve cancer outcome.

Teaching During the COVID-19 Pandemic: The Experience of the Faculty of Medicine at the Technion-Israel Institute of Technology.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic forced drastic changes in all layers of life. Social distancing and lockdown drove the educational system to uncharted territories at an accelerated pace, leaving educators little time to adjust. OBJECTIVES: To describe changes in teaching during the first phase of the COVID-19 pandemic. METHODS: We described the steps implemented at the Technion-Israel Institute of Technology Faculty of Medicine during the initial 4 months of the COVID-19 pandemic to preserve teaching and the academic ecosystem. RESULTS: Several established methodologies, such as the flipped classroom and active learning, demonstrated effectiveness. In addition, we used creative methods to teach clinical medicine during the ban on bedside teaching and modified community engagement activities to meet COVID-19 induced community needs. CONCLUSIONS: The challenges and the lessons learned from teaching during the COVID-19 pandemic prompted us to adjust our teaching methods and curriculum using multiple online teaching methods and promoting self-learning. It also provided invaluable insights on our pedagogy and the teaching of medicine in the future with emphasis on students and faculty being part of the changes and adjustments in curriculum and teaching methods. However, personal interactions are essential to medical school education, as are laboratories, group simulations, and bedside teaching.

Heparanase is required for activation and function of macrophages.

The emerging role of heparanase in tumor initiation, growth, metastasis, and chemoresistance is well recognized and is encouraging the development of heparanase inhibitors as anticancer drugs. Unlike the function of heparanase in cancer cells, very little attention has been given to heparanase contributed by cells composing the tumor microenvironment. Here we used a genetic approach and examined the behavior and function of macrophages isolated from wild-type (WT) and heparanase-knockout (Hpa-KO) mice. Hpa-KO macrophages express lower levels of cytokines (e.g., TNFα, IL1-ß) and exhibit lower motility and phagocytic capacities. Intriguingly, inoculation of control monocytes together with Lewis lung carcinoma (LLC) cells into Hpa-KO mice resulted in nearly complete inhibition of tumor growth. In striking contrast, inoculating LLC cells together with monocytes isolated from Hpa-KO mice did not affect tumor growth, indicating that heparanase is critically required for activation and function of macrophages. Mechanistically, we describe a linear cascade by which heparanase activates Erk, p38, and JNK signaling in macrophages, leading to increased c-Fos levels and induction of cytokine expression in a manner that apparently does not require heparanase enzymatic activity. These results identify heparanase as a key mediator of macrophage activation and function in tumorigenesis and cross-talk with the tumor microenvironment.

Identification and analysis of a novel dimerization domain shared by various members of c-Jun N-terminal kinase (JNK) scaffold proteins.

Mitogen-activated protein kinases (MAPKs) form a kinase tier module in which MAPK, MAP2K, and MAP3K are held by scaffold proteins. The scaffold proteins serve as a protein platform for selective and spatial kinase activation. The precise mechanism by which the scaffold proteins function has not yet been fully explained. WDR62 is a novel scaffold protein of the c-Jun N-terminal kinase (JNK) pathway. Recessive mutations within WDR62 result in severe cerebral cortical malformations. One of the WDR62 mutant proteins found in a patient with microcephaly encodes a C-terminal truncated protein that fails to associate efficiently with JNK and MKK7ß1. The present article shows that the WDR62 C-terminal region harbors a novel dimerization domain composed of a putative loop-helix domain that is necessary and sufficient for WDR62 dimerization and is critical for its scaffolding function. The loop-helix domain is highly conserved between orthologues and is also shared by the JNK scaffold protein, JNKBP1/MAPKBP1. Based on the high sequence conservation of the loop-helix domain, our article shows that MAPKBP1 homodimerizes and heterodimerizes with WDR62. Endogenous WDR62 and MAPKBP1 co-localize to stress granules following arsenite treatment, but not during mitosis. This study proposes another layer of complexity, in which coordinated activation of signaling pathways is mediated by the association between the different JNK scaffold proteins depending on their biological function.

The bZIP repressor proteins, c-Jun dimerization protein 2 and activating transcription factor 3, recruit multiple HDAC members to the ATF3 promoter.

JDP2, is a basic leucine zipper (bZIP) protein displaying a high degree of homology with the stress inducible transcription factor, ATF3. Both proteins bind to cAMP and TPA response elements and repress transcription by multiple mechanisms. Histone deacetylases (HDACs) play a key role in gene inactivation by deacetylating lysine residues on histones. Here we describe the association of JDP2 and ATF3 with HDACs 1, 2-6 and 10. Association of HDAC3 and HDAC6 with JDP2 and ATF3 occurs via direct protein-protein interactions. Only part of the N-terminal bZIP motif of JDP2 and ATF3 basic domain is necessary and sufficient for the interaction with HDACs in a manner that is independent of coiled-coil dimerization. Class I HDACs associate with the bZIP repressors via the DAC conserved domain whereas the Class IIb HDAC6 associates through its C-terminal unique binder of ubiquitin Zn finger domain. Both JDP2 and ATF3 are known to bind and repress the ATF3 promoter. MEF cells treated with histone deacetylase inhibitor, trichostatin A (TSA) display enhanced ATF3 transcription. ATF3 enhanced transcription is significantly reduced in MEF cells lacking both ATF3 and JDP2. Collectively, we propose that the recruitment of multiple HDAC members to JDP2 and ATF3 is part of their transcription repression mechanism.

Tumor Progression Reverses Cardiac Hypertrophy and Fibrosis in a Tetracycline-Regulated ATF3 Transgenic Mouse Model.

Cardiovascular diseases (CVD) and cancer are the top deadly diseases in the world. Both CVD and cancer have common risk factors; therefore, with the advances in treatment and life span, both diseases may occur simultaneously in patients. It is becoming evident that CVD and cancer are highly connected, establishing a novel discipline known as cardio-oncology. This includes the cardiomyocyte death following any anti-tumor therapy known as cardiotoxicity as well the intricate interplay between heart failure and cancer. Recent studies, using various mouse models, showed that heart failure promotes tumor growth and metastasis spread. Indeed, patients with heart failure were found to be at higher risk of developing malignant diseases. While the effect of heart failure on cancer is well established, little is known regarding the effect of tumors on heart failure. A recent study from our lab has demonstrated that tumor growth and metastasis ameliorate cardiac remodeling in a pressure-overload mouse model. Nevertheless, this study was inconclusive regarding whether tumor growth solely suppresses cardiac remodeling or is able to reverse existing heart failure outcomes as well. Here, we used a regulable transgenic mouse model for cardiac hypertrophy and fibrosis. Cancer cell implantation suppressed cardiac dysfunction and fibrosis as shown using echocardiography, qRT-PCR and fibrosis staining. In addition, tumor growth resulted in an M1 to M2 macrophage switch, which is correlated with cardiac repair. Macrophage depletion using clodronate liposomes completely abrogated the tumors' beneficial effect. This study highly suggests that harnessing tumor paradigms may lead to the development of novel therapeutic strategies for CVDs and fibrosis.

Tumor Growth Ameliorates Cardiac Dysfunction.

Heart failure and cancer are the deadliest diseases worldwide. Murine models for cardiac remodeling and heart failure demonstrate that cardiac dysfunction promotes cancer progression and metastasis spread. Yet, no information is available on whether and how tumor progression affects cardiac remodeling. Here, we examined cardiac remodeling following transverse aortic constriction (TAC) in the presence or absence of proliferating cancer cells. We show that tumor-bearing mice, of two different cancer cell lines, display reduced cardiac hypertrophy, lower fibrosis and improved cardiac contractile function following pressure overload induced by TAC surgery. Integrative analysis of qRT-PCR, flow cytometry and immunofluorescence identified tumor-dependent M1-to-M2 polarization in the cardiac macrophage population as a mediator of the beneficial tumor effect on the heart. Importantly, tumor-bearing mice lacking functional macrophages fail to improve cardiac function and display sustained fibrosis.

Phosphorylation of JDP2 on threonine-148 by the c-Jun N-terminal kinase targets it for proteosomal degradation.

JDP2 (c-Jun dimerization protein 2) is a member of the basic leucine zipper family of transcription factors that is ubiquitously expressed in all examined cell types. JDP2 is phosphorylated on Thr148 by JNK (c-Jun N-terminal kinase) and p38 kinase, although the functional role of its phosphorylation is unknown. In the present paper we show that the JDP2 protein level is dramatically reduced in response to serum stimulation, anisomycin treatment, ultraviolet light irradiation and cycloheximide treatment, all of which activate the JNK pathway. In addition, endogenous and overexpressed JDP2 are phosphorylated in response to these stimuli. Replacement of Thr148 with an alanine residue stabilizes ectopically expressed JDP2 in the presence of the stimuli; conversely, substitution with glutamic acid destabilizes it. Serum-induced phosphorylation and degradation of JDP2 are specific to JNK activation since a JNK inhibitor (SP600125) abolishes these effects, whereas p38 and MEK inhibitors (SB203580 and UO126) have no effect. In the presence of cycloheximide, JDP2 is rapidly phosphorylated and degraded due to the combined effects of protein synthesis inhibition and activation of JNK. Pre-treatment of cells with SP600125 prior to cycloheximide treatment significantly prolongs the half-life of JDP2 that is found mainly in the unphosphorylated form. Lastly, the proteasome inhibitor (MG132) rescues JDP2 degradation following cycloheximide treatment and increases the expression of the JDP2 phospho-mimetic T148E mutant. Collectively, these results suggest that phosphorylation of JDP2 on thr148 by JNK targets it to the proteasome for degradation.

Docking interactions of the JNK scaffold protein WDR62.

JNK (c-Jun N-terminal kinase) is part of a MAPK (mitogen-activated protein kinase) signalling cascade. Scaffold proteins simultaneously associate with various components of the MAPK signalling pathway and play a crucial role in signal transmission and MAPK regulation. WDR62 (WD repeat domain 62) is a JNK scaffold protein. Recessive mutations within WDR62 result in severe cerebral cortical malformation. In the present study we demonstrate the association of WDR62 with endogenous and overexpressed proteins of both JNK2 and the JNK2-activating kinase MKK7 (MAPK kinase 7). Association of WDR62 with JNK2 and MKK7 occurs via direct protein-protein interactions. We mapped the docking domain of WDR62 responsible for the association with JNK. WDR62 interacts with all JNK isoforms through a D domain motif located at the C-terminus. A WDR62 mutant lacking the putative JNK-binding domain fails to activate and recruit JNK to cellular granules. Furthermore, a synthetic peptide composed of the WDR62 docking domain inhibits JNK2 activity in vitro. WDR62 association with JNK2 requires both the JNK CD and ED domains, and the binding requisite is distinct from that of the previously described JNK2 association with JIP1 (JNK-interacting protein 1). Next, we characterized the association between WDR62 and MKK7. WDR62 associates directly with the MKK7ß1 isoform independently of JNK binding, but fails to interact with MKK7α1. Furthermore, MKK7ß1 recruits a protein phosphatase that dephosphorylates WDR62. Interestingly, a premature termination mutation in WDR62 that results in severe brain developmental defects does not abrogate WDR62 association with either JNK or MKK7. Therefore such mutations represent a loss of WDR62 function independent of JNK signalling.

Cardiac Dysfunction Promotes Cancer Progression via Multiple Secreted Factors.

Heart failure and cancer are the leading cause of deaths worldwide. While heart failure and cancer have been considered separate diseases, it is becoming evident that they are highly connected and affect each other's outcomes. Recent studies using experimental mouse models have suggested that heart failure promotes tumor progression. The mouse models used involve major irreversible surgery. Here, we induced heart hypertrophy via expression of activating transcription factor 3 (ATF3) in cardiomyocytes, followed by cancer cells' implantation. Tumors developing in ATF3-transgenic mice grew larger and displayed a more highly metastatic phenotype compared with tumors in wild-type mice. To address whether ATF3 expression or the cardiac outcome are necessary for tumor progression, ATF3 expression was turned off after cardiac hypertrophy development followed by cancer cell implantation. The tumor promotion phenotype and the enhancement of metastatic properties were preserved, suggesting that the failing heart per se is sufficient to promote tumor progression. Serum derived from ATF3-transgenic mice enhanced cancer cell proliferation and increased cancer cell metastatic properties in vitro. Using a cytokine array panel, multiple factors responsible for promoting tumor cell proliferation and the metastatic phenotype were identified. Interestingly, the failing heart and the tumor separately and simultaneously contributed to higher levels of these factors in the serum as well as other tissues and organs. These data suggest the existence of intimate cross-talk between the hypertrophied heart and the tumor that is mediated by secreted factors, leading to cancer promotion and disease deterioration. SIGNIFICANCE: This work highlights the importance of early diagnosis and treatment of heart failure prior to reaching the irreversible stage that can exacerbate cancer progression.

Cardiac Remodeling in the Absence of Cardiac Contractile Dysfunction Is Sufficient to Promote Cancer Progression.

Cardiovascular diseases and cancer are the leading cause of death worldwide. The two diseases share high co-prevalence and affect each other's outcomes. Recent studies suggest that heart failure promotes cancer progression, although the question of whether cardiac remodeling in the absence of cardiac contractile dysfunction promotes cancer progression remains unanswered. Here, we aimed to examine whether mild cardiac remodeling can promote tumor growth. We used low-phenylephrine (PE)-dose-infused in mice, together with breast cancer cells (polyoma middle T, PyMT), implanted in the mammary fat pad. Although cardiac remodeling, hypertrophy and fibrosis gene hallmarks were identified, echocardiography indicated no apparent loss of cardiac function. Nevertheless, in PE-infused mouse models, PyMT-cell-derived tumors grew larger and displayed increased cell proliferation. Consistently, serum derived from PE-infused mice resulted in increased cancer cell proliferation in vitro. ELISA and gene expression analysis identified periostin, fibronectin and CTGF as cardiac- and tumor-secreted factors that are highly abundant in PE-infused mice serum as compared with non-infused mice. Collectively, a low dose of PE infusion without the deterioration of cardiac function is sufficient to promote cancer progression. Hence, early detection and treatment of hypertension in healthy and cancer patients would be beneficial for improved outcomes.

Induction of heparanase 2 (Hpa2) expression by stress is mediated by ATF3.

Activity of heparanase, endoglycosidase that cleaves heparan sulfate side chains in heparan sulfate proteoglycans, is highly implicated in tumor progression and metastasis. Heparanase inhibitors are therefore being evaluated clinically as anti-cancer therapeutics. Heparanase 2 (Hpa2) is a close homolog of heparanase that lacks HS-degrading activity and functions as an endogenous inhibitor of heparanase. As a result, Hpa2 appears to attenuate tumor growth but mechanisms that regulate Hpa2 expression and determine the ratio between heparanase and Hpa2 are largely unknown. We have recently reported that the expression of Hpa2 is induced by endoplasmic reticulum (ER) and proteotoxic stresses, but the mechanism(s) underlying Hpa2 gene regulation was obscure. Here we expand the notion that Hpa2 is regulated by conditions of stress. We report that while ER and hypoxia, each alone, resulted in a 3-7 fold increase in Hpa2 expression, combining ER stress and hypoxia resulted in a noticeable, over 40-fold increase in Hpa2 expression. A prominent induction of Hpa2 expression was also quantified in cells exposed to heat shock, proteotoxic stress, lysosomal stress, and chemotherapy (cisplatin), strongly implying that Hpa2 is regulated by conditions of stress. Furthermore, analyses of the Hpa2 gene promoter led to the identification of activating-transcription-factor 3 (ATF3) as a transcription factor that mediates Hpa2 induction by stress, thus revealing, for the first time, a molecular mechanism that underlies Hpa2 gene regulation. Induction of Hpa2 and ATF3 by conditions of stress that often accompany the rapid expansion of tumors is likely translated to improved survival of cancer patients.

Angiotensin II signaling up-regulates the immediate early transcription factor ATF3 in the left but not the right atrium.

The atria respond to various pathological stimuli including pressure and volume overload with remodeling and dilatation. Dilatation of the left atrium is associated with atrial fibrillation. The mechanisms involved in chamber-specific hypertrophy are largely unknown. Angiotensin II is hypothesized to take part in mediating this response. ATF3 is an immediate early gene found at the receiving end of multiple stress and growth stimuli. Here we characterize ATF3 as a direct target gene for angiotensin II. ATF3 expression is regulated by angiotensin receptor-mediated signaling in vivo and in vitro at the transcriptional level. ATF3 induction is mediated by cooperation between both the AT(1A) and AT2 receptor subtypes. While AT2R blocker (PD123319) efficiently blocks ATF3 induction in response to angiotensin II injection, it results in an increase in blood pressure indicating that the effect of angiotensin II on ATF3 is independent of its effect on blood pressure. In contrast to adrenergic stimulation that induces ATF3 in all heart chambers, ATF3 induction in response to angiotensin II occurs primarily in the left chambers. We hypothesize that the activation of differential signaling pathways accounts for the chamber-specific induction of ATF3 expression in response to angiotensin II stimulation. Angiotensin II injection rapidly activates the EGFR-dependent pathways including ERK and PI3K-AKT in the left but not the right atrium. EGF receptor inhibitor (Gefitinib/Iressa) as well as the AKT inhibitor (Triciribine) significantly abrogates ATF3 induction by angiotensin II in the left chambers. Collectively, our data strongly place ATF3 as a unique nuclear protein target in response to angiotensin II stimulation in the atria. The spatial expression of ATF3 may add to the understanding of the signaling pathways involved in cardiac response to neuro-hormonal stimulation, and in particular to the understanding of left atrial-generated pathology such as atrial fibrillation.

The ubiquitously expressed bZIP inhibitor, JDP2, suppresses the transcription of its homologue immediate early gene counterpart, ATF3.

JDP2 is a ubiquitously expressed bZIP repressor protein. JDP2 binds TPA response element and cyclic AMP response element located within various promoters. JDP2 displays a high degree of homology to the immediate early gene ATF3. ATF3 plays a crucial role in the cellular adaptive response to multiple stress insults as well as growth stimuli. We have identified ATF3 as a potential target gene for JDP2 repression. JDP2 regulates the ATF3 promoter potentially through binding to both the consensus ATF/CRE site and a non-consensus ATF3 auto-repression DNA-binding element. Expression of ATF3 protein in wild-type mouse embryo fibroblast (MEF) cells is below the detectable levels, whereas, JDP2 disrupted MEF cells display noticeable level of ATF3 protein. Following either serum or ER stress stimulation, ATF3 expression is potentiated in JDP2-KO fibroblast cells as compared with wild-type cells. Mice with either JDP2 over-expression or JDP2 disruption display undetectable level of ATF3 protein. However, ATF3 induction in response to either growth or stress signals is dependent on JDP2 expression level. ATF3 induction is attenuated in JDP2 over-expressing mice whereas is potentiated in JDP2-KO mice as compared with the corresponding wild-type mice. Collectively, the data presented strongly suggest that JDP2 plays a role in the determination of the ATF3 adaptive cellular threshold response to different stress insults and growth stimuli.

Increased risk of non-hematological cancer in young patients with aortic stenosis: a retrospective cohort study.

BACKGROUND: We have previously reported an increased risk for non-hematological malignancies in young patients with moderate or severe aortic stenosis (AS). These findings were the result of a post-hoc analysis from a large echocardiography database and needed verification. Our aim was to determine, using a different study population, whether young patients with AS are at increased risk for cancer. METHODS: A large echocardiographic database was used to identify patients (age ≥ 20 years) with moderate or severe AS (study group) and patients without aortic stenosis (comparative group). The new occurrence of non-hematological malignancies was determined after the index date (first echo with moderate or severe AS or first recorded echo in the control group). RESULTS: The final study group included 7013 patients with AS and 98,884 without AS. During a median follow-up of 6.9 years (3.0-11.1) there were 10,705 new cases of non-hematological cancer. The crude incidence rate of cancer was higher in AS compared to non-AS patients (22.3 vs. 13.7 per 1000 patient-year, crude HR 1.58 (95%CI 1.46-1.71). After adjustment for relevant covariates, there was no difference between groups (HR 0.93, 95% CI 0.86-1.01). Only patients in the lowest age quartile (20-49.7 years), had an increased adjusted risk of cancer (HR 1.91, 95%CI 1.08-3.39). The HR for the risk of cancer associated with AS was inversely proportional to age (P < 0.001 for the interaction between AS and age). CONCLUSIONS: Young patients with moderate or severe AS may have an increased risk for cancer. Cancer surveillance should be considered for young patients with AS.

The AP-1 repressor protein, JDP2, potentiates hepatocellular carcinoma in mice.

BACKGROUND: The AP-1 transcription factor plays a major role in cell proliferation, apoptosis, differentiation and developmental processes. AP-1 proteins are primarily considered to be oncogenic. Gene disruption studies placed c-Jun as an oncogene at the early stage of a mouse model of hepatocellular carcinoma. Mice lacking c-Jun display reduced number and size of hepatic tumors attributed to elevated p53 expression and increased apoptosis. This suggests that c-Jun inhibition may serve as a therapeutic target for liver cancer. The c-Jun dimerization protein 2, JDP2 is an AP-1 repressor protein that potently inhibits AP-1 transcription. On the other hand, the JDP2 locus was found at a recurring viral integration site in T-cell lymphoma. We sought to examine the potential of JDP2 to inhibit c-Jun/AP-1 oncogenic activity in mice. Towards this end, we generated a tetracycline inducible transgenic mouse expressing JDP2 specifically in the liver. We used diethylnitrosamine (DEN) injection to initiate liver cancer in mice and assessed the extent of liver cancer in JDP2-transgenic and wild type control mice by biochemical and molecular biology techniques. RESULTS: JDP2-transgenic mice display normal liver function. JDP2-transgenic mice displayed potentiation of liver cancer, higher mortality and increased number and size of tumors. The expression of JDP2 at the promotion stage was found to be the most critical for enhancing liver cancer severity. CONCLUSIONS: This study suggests that JDP2 expression may play a critical role in liver cancer development by potentiating the compensatory proliferative response and increased inflammation in the DEN liver cancer model.

TRE-dependent transcription activation by JDP2-CHOP10 association.

The c-Jun dimerization protein 2, JDP2, is a member of the activating protein 1 (AP-1) family of transcription factors. Overexpression of JDP2 has been shown to result in repression of AP-1-dependent transcription and inhibition of cellular transformation. Other studies suggested that JDP2 may function as an oncogene. Here we describe the identification of CHOP10, a member of the CCAAT enhancer binding proteins, as a protein associating with JDP2. In contrast to the inhibition of transcription by JDP2, JDP2-CHOP complex strongly enhances transcription from promoters containing TPA response elements (TRE), but not from those containing cyclic AMP response elements (CRE). The association between JDP2 and CHOP10 involves the leucine zipper motifs of both proteins, whereas, the basic domain of CHOP10 contributes to the association of the JDP2-CHOP10 complex with the DNA. DNA binding of JDP2-CHOP complex is observed both in vitro and in vivo. Finally, overexpression of JDP2 results in increased cell viability following ER stress and counteracts CHOP10 pro-apoptotic activity. JDP2 expression may determine the threshold for cell sensitivity to ER stress. This is the first report describing TRE-dependent activation of transcription by JDP2 and thus may provide an explanation for the as yet unexplored oncogenic properties of JDP2.