Implications For Tumor Development Research Articles

A correlation study of adhesion G protein-coupled receptors as potential therapeutic targets for breast cancer.

Adhesion G protein-coupled receptors (aGPCRs), a distinctive subset of the G protein-coupled receptor (GPCR) superfamily, play crucial roles in various physiological and pathological processes, with implications in tumor development. Despite the global prevalence of breast cancer (BRCA), specific aGPCRs as potential drug targets or biomarkers remain underexplored. UALCAN, GEPIA, Kaplan-Meier Plotter, MethSurv, cBiopportal, String, GeneMANIA, DAVID, Timer, Metascape, and qPCR were applied in this work. Our analysis revealed significantly increased transcriptional levels of ADGRB2, ADGRC1, ADGRC2, ADGRC3, ADGRE1, ADGRF2, ADGRF4, and ADGRL1 in BRCA primary tumors. Further analysis indicated a significant correlation between the expressions of certain aGPCRs and the pathological stage of BRCA. High expression of ADGRA1, ADGRF2, ADGRF4, ADGRG1, ADGRG2, ADGRG4, ADGRG6, and ADGRG7 was significantly correlated with poor overall survival (OS) in BRCA patients. Additionally, high expression of ADGRF2 and ADGRF4 indicated inferior recurrence-free survival (RFS) in BRCA patients. The RT-qPCR experiments also confirmed that the mRNA levels of ADGRF2 and ADGRF4 were higher in BRCA cells and tissues. Functional analysis highlighted the diverse roles of aGPCRs, encompassing GPCR signaling andmetabolic energy reserves. Moreover, aGPCRs may exert influence or actively participate in the development of BRCA through their impact on immune status. aGPCRs, particularly ADGRF2 and ADGRF4, hold promise as immunotherapeutic targets and prognostic biomarkers in BRCA.

Abscopal Effect, Extracellular Vesicles and Their Immunotherapeutic Potential in Cancer Treatment.

The communication between tumor cells and the microenvironment plays a fundamental role in the development, growth and further immune escape of the tumor. This communication is partially regulated by extracellular vesicles which can direct the behavior of surrounding cells. In recent years, it has been proposed that this feature could be applied as a potential treatment against cancer, since several studies have shown that tumors treated with radiotherapy can elicit a strong enough immune response to eliminate distant metastasis; this phenomenon is called the abscopal effect. The mechanism behind this effect may include the release of extracellular vesicles loaded with damage-associated molecular patterns and tumor-derived antigens which activates an antigen-specific immune response. This review will focus on the recent discoveries in cancer cell communications via extracellular vesicles and their implication in tumor development, as well as their potential use as an immunotherapeutic treatment against cancer.

A216 EXAMINING THE EFFECTS OF GLYPHOSATE EXPOSURE ON THE GUT BACTERIOME AND INFLAMMATION IN A MURINE MODEL OF COLITIS

Abstract Background Canada has the highest incidence of inflammatory bowel disease in the world, which is expected to rise unabated for the next 30 years. Coincidently, Canada is one of the most prolific users of the herbicide glyphosate (tradename Roundup®), with over 25 million kilograms purchased annually. Previous studies examining the effects of glyphosate on the gut bacteriome have used high levels of glyphosate (ranging from 2.5mg – 25mg/kg bw/day) and have yielded conflicting results. Our goal is to examine the effects of dietary levels of glyphosate on the gut microbiome and inflammation in an animal model of colitis. Two environmentally relevant doses were explored: (1) the acceptable daily intake currently set by the Environmental Protection Agency (EPA) (1.75mg/kg bw/day) and (2) North American dose, calculated by a registered dietician using literature values of glyphosate found within food products (0.1mg/kg bw/day.) Aims 1) To determine if glyphosate exposure influences intestinal permeability 2) To determine if glyphosate exposure influences intestinal inflammation 3) To determine if glyphosate exposure influences colitis onset and severity. We hypothesized that exposure to glyphosate leads to bacterial dysbiosis, increased intestinal permeability and increased severity of colitis in Mucin 2 deficient mice (Muc2-/-mice). Methods Upon weaning, Muc2-/- mice were exposed to glyphosate through their drinking water. Animals were monitored weekly for clinical signs of colitis, including rectal prolapse. Following 12-week glyphosate exposure, intestinal permeability was measured using the FITC-dextran permeability assay. Intestinal inflammation was measured using qPCR and markers relevant to our animal model including REGIIIγ, RELM-β and CLEC-2. Results Exposure to glyphosate at physiologically relevant levels does not increase intestinal permeability in Muc2-/-mice, with all groups showing equal levels of FITC-dextran present within their serum. Animals exposed to the EPA dose of glyphosate exhibited earlier onset of colitis symptoms with animals receiving higher clinical scores and displaying an increased rate of rectal prolapse. Animals exposed to the EPA dose also showed a significant increase in CLEC-2 expression. CLEC-2 is a C-type lectin-like receptor expressed by immune cells and platelets and has been implicated in tumor metastasis. Additionally, overexpression of CLEC-2 has been shown to promote pathogen adherence to mammalian cells. Conclusions Exposure to glyphosate at levels deemed safe by the EPA increases colitis onset and severity in Muc2-/- deficient animals. Additionally, EPA level glyphosate exposure upregulates CLEC-2 expression which may have implications for tumor development and increased enteropathogenic infections. Funding Agencies CCCCrowdfunding, NSERC

Ontogeny of Tumor-Associated Macrophages.

Tumor-associated macrophages (TAM) represent the main immune cell population of the tumor microenvironment in most cancer. For decades, TAM have been the focus of intense investigation to understand how they modulate the tumor microenvironment and their implication in therapy failure. One consensus is that TAM are considered to exclusively originate from circulating monocyte precursors released from the bone marrow, fitting the original dogma of tissue-resident macrophage ontogeny. A second consensus proposed that TAM harbor either a classically activated M1 or alternatively activated M2 polarization profile, with almost opposite anti- and pro-tumoral activity respectively. These fundamental pillars are now revised in face of the latest discoveries on macrophage biology. Embryonic-derived macrophages were recently characterized as major contributors to the pool of tissue-resident macrophages in many tissues. Their turnover with macrophages derived from precursors of adult hematopoiesis seems to follow a regulation at the subtissular level. This has shed light on an ever more complex macrophage diversity in the tumor microenvironment than once thought and raise the question of their respective implication in tumor development compared to classical monocyte-derived macrophages. These recent advances highlight that TAM have actually not fully revealed their usefulness and deserve to be reconsidered. Understanding the link between TAM ontogeny and their various functions in tumor growth and interaction with the immune system represents one of the future challenges for cancer therapy.

Imaging biomarker phenotyping system (iBiopsy) to accelerate hepatocellular carcinoma (HCC) drug development.

e15671 Background: Current drug therapies in HCC remain limited because of substantial genomic, cellular and molecular heterogeneity of the liver tumor microenvironment (TME). This heterogeneity has implications for tumor development, immune response and cellular invasion and is compounded by multiple molecular pathways related to the various HCC etiologies. In this context, it is challenging to find biomarkers that are predictive of therapeutic response or outcome. A systems biology approach leveraging the iBiopsy phenotyping platform to automatically detect HCC and TME subtypes using non-invasive medical imaging could help identify specific disease pathways and accelerate HCC drug development. Methods: In this retrospective study, 50 patients with primary HCC were used to extract voxel level image signatures from the segmented livers on CT scans. The automatic classification of liver signatures was obtained by Log Linear Local density peak clustering computed using Wasserstein’s optimal transport distance between Gray Level Co-occurrence matrices of local luminance tiles of the Liver. Through this hypothesis-free clustering, phenotypes representative of tumor and tumor environment were identified and further correlated with clinical data. Results: Nine classes of statistically significantly distant clusters were identified on the 50 patients. Preliminary correlation analysis on individual patient showed that up to 3 clusters were specific to the tumor and characterized phenotype heterogeneity within the tumor. Notably, specific clusters at the tumor front-line and surrounding adjacent non-tumoral tissue were also identified. Conclusions: Preliminary results show that a multiplicity of phenotypes representative of a complex heterogeneous lesion and tissue microenvironment that might have prognostic and predictive value can be identified. This support the use of a non-invasive phenotypic approach for the subtyping of HCC that can be used for the identification of a multiplicity of important biological pathways that can be specifically targeted to treat HCC.

Downregulation of TSPAN13 by miR-369-3p inhibits cell proliferation in papillary thyroid cancer (PTC).

Previous studies demonstrated dysregulation of different microRNAs in thyroid cancer. Tetraspanins (TSPANs) are cell surface proteins with critical roles in many cellular processes, and implications in tumor development. Here we investigated the role of miR-369-3p in papillary thyroid cancer (PTC) and its association with TSPAN13. miR-369-3p and the TSPAN13 gene expression profiles of 513 thyroid cancer and 59 normal thyroid tissues were downloaded from the Cancer Genome Atlas database. Thyroid cancer tissues were classified according to the histological type, grouped based on low and high median miR-369-3p and TSPAN13 expression, and analyzed in relation to overall survival (OS) of patients. Human PTC cell lines (TPC-1 and GLAG-66) and human embryonic kidney 293T (HEK293T) cells were used for in vitro analysis. Transfection experiments were performed with synthetic miRNA mimics for miR-369-3p and small interfering RNAs for TSPAN13. Relative expression of miR-369-3p and TSPAN13 mRNA was determined by RT-qPCR. Protein levels of TSPAN13 were determined by western blotting. Cell proliferation (CCK-8 assay), colony formation, and apoptosis (flow cytometry) were analyzed in transfected cells. Binding sites of miR-369-3p in TSPAN13 mRNA were determined by bioinformatics analysis and dual luciferase reporter assay. miR-369-3p was downregulated and TSPAN13 upregulated in PTC, follicular thyroid cancer, and tall cell variant tissues. Both low expression of miR-369-3p and high expression of TSPAN13 were associated with shorter OS in thyroid cancer patients. Overexpression of miR-369-3p significantly suppressed proliferation and promoted apoptosis in PTC cells. TSPAN13 was a direct target of miR-369-3p, and silencing of TSPAN13 phenocopied the effect of miR-369-3p mimics in PTC cells. Overall, the downregulation of miR-369-3p and consequent upregulation of its target TSPAN13 appear to be involved in pathophysiology of PTC.

The Energetics and Physiological Impact of Cohesin Extrusion

Cohesin extrusion is thought to play a central role in establishing the architecture of mammalian genomes. However, extrusion has not been visualized invivo, and thus, its functional impact and energetics are unknown. Using ultra-deep Hi-C, we show that loop domains form by a process that requires cohesin ATPases. Once formed, however, loops and compartments are maintained for hours without energy input. Strikingly, without ATP, we observe the emergence of hundreds of CTCF-independent loops that link regulatory DNA.We also identify architectural "stripes," where a loop anchor interacts with entire domains at highfrequency. Stripes often tether super-enhancers to cognate promoters, and in B cells, they facilitate Igh transcription and recombination. Stripe anchors represent major hotspots for topoisomerase-mediated lesions, which promote chromosomal translocations and cancer. In plasmacytomas, stripes can deregulate Igh-translocated oncogenes. We propose that higher organisms have coopted cohesin extrusion to enhance transcription and recombination, with implications for tumor development.

Urokinase Type Plasminogen Activator and the Molecular Mechanisms of its Regulation in Cancer.

Urokinase type plasminogen activator (uPA) is a 53-kDa serine protease initially synthesized as a catalytically inactive single chain polypeptide. Inactive-uPA is subject to proteolytic cleavage, which results in the two-chain active protein. uPA plays key roles in the enhancement of cell malignancy during tumor progression. The main objective of this review was to analyze and describe the main molecular mechanisms involved in the regulation of uPA expression in cancer Methods: Searching literature to evaluate and define the relevant information regarding to the state of the arts on uPA functionality and regulation in cancer, including intracellular signaling regulation, tumor progression, invasion, epigenetic mechanism, and finally uPA as therapeutic target in cancer. uPA expression is dysregulated in tumor cells, which results in increased cellular invasion capacities reflecting changes in uPA activity and expression during tumor progression. In this review we discuss the main aspects of uPA, from its capacity to activate plasminogen to plasmin, to the main intracellular signal transduction mechanisms as well as the epigenetic mechanisms involved in the regulation of uPA expression, including regulation by microRNAs. As well as, the current therapeutic methodologies targeting uPA for cancer treatment are described. Although, uPA is dysregulate in tumor progression, its expression is finely regulated at both enzymatic activity and at protein expression as well, which allow cancer cells efficiently survive, proliferate, and spread into neighbouring tissues and distant organs. Moreover, since uPA implications in tumor development and cancer cell invasion and metastasis, it is an attractive target for cancer chemotherapies.

Inhibition of Lysyl Oxidases Impairs Migration and Angiogenic Properties of Tumor-Associated Pericytes.

Pericytes are important cellular components of the tumor microenviroment with established roles in angiogenesis and metastasis. These two cancer hallmarks are modulated by enzymes of the LOX family, but thus far, information about LOX relevance in tumor-associated pericytes is lacking. Here, we performed a comparative characterization of normal and tumoral pericytes and report for the first time the modulatory effects of LOX enzymes on activated pericyte properties. Tumoral pericytes isolated from childhood ependymoma and neuroblastoma specimens displayed angiogenic properties in vitro and expressed typical markers, including CD146, NG2, and PDGFRβ. Expression of all LOX family members could be detected in both normal and tumor-associated pericytes. In most pericyte samples, LOXL3 was the family member displaying the highest transcript levels. Inhibition of LOX/LOXL activity with the inhibitor β-aminopropionitrile (βAPN) significantly reduced migration of pericytes, while proliferation rates were kept unaltered. Formation of tube-like structures in vitro by pericytes was also significantly impaired upon inhibition of LOX/LOXL activity with βAPN, which induced more prominent effects in tumor-associated pericytes. These findings reveal a novel involvement of the LOX family of enzymes in migration and angiogenic properties of pericytes, with implications in tumor development and in therapeutic targeting tumor microenvironment constituents.

Systemic treatment for hepatocellular carcinoma: Still unmet expectations.

Many patients with hepatocellular carcinoma (HCC) are diagnosed in an advanced stage, so they cannot be offered the option of curative treatments. The results of systemic chemotherapy are unsatisfactory and this has led to molecular targeted approaches. HCC develops in chronically damaged tissue due to cirrhosis in most patients. Several different cell types and molecules constitute a unique microenvironment in the liver, which has significant implications in tumor development and invasion. This, together with genome instability, contributes to a significant heterogeneity which is further enhanced by the molecular differences of the underlying causes. New classifications based on genetic characteristics of the tissue microenvironment have been proposed and key carcinogenic signaling pathways have been described. Tumor and adjacent tissue profiling seem biologically promising, but have not yet been translated into clinical settings. The encouraging first results with molecular - genetic signatures should be validated and clinically applicable. A more personalized approach to modern management of HCC is urgently needed.

Anti-bevacizumab idiotype antibody vaccination is effective in inducing vascular endothelial growth factor-binding response, impairing tumor outgrowth.

Tumors require blood supply and, to overcome this restriction, induce angiogenesis. Vascular endothelial growth factor (VEGF) plays an important role in this process, which explains the great number of antiangiogenic therapies targeting VEGF. The research and development of targeted therapy has led to the approval of bevacizumab, a humanized anti‐VEGF monoclonal antibody (mAb), in clinical settings. However, side effects have been reported, usually as a consequence of bolus‐dose administration of the antibody. This limitation could be circumvented through the use of anti‐idiotype (Id) antibodies. In the present study, we evaluated the efficacy of an active VEGF‐binding immune response generated by an anti‐bevacizumab idiotype mAb, 10.D7. The 10.D7 anti‐Id mAb vaccination led to detectable levels of VEGF‐binding anti‐anti‐Id antibodies. In order to examine whether this humoral immune response could have implications for tumor development, 10.D7‐immunized mice were challenged with B16‐F10 tumor cells. Mice immunized with 10.D7 anti‐Id mAb revealed reduced tumor growth when compared to control groups. Histological analyses of tumor sections from 10.D7‐immunized mice showed increased necrotic areas, decreased CD31‐positive vascular density and reduced CD68‐positive cell infiltration. Our results encourage further therapeutic studies, particularly if one considers that the anti‐Id therapeutic vaccination maintains stable levels of VEGF‐binding antibodies, which might be useful in the control of tumor relapse.

P5.03 - Control of cell fate by the mammalian target of rapamycin (mTOR) under stress depends on eIF2α serine 51 phosphorylation

ABSTRACT The mammalian/mechanist target of rapamycin (mTOR) plays an essential role in cell growth and metabolism by regulating protein and RNA stability, transcription as well as mRNA translation. Phosphorylation of the a subunit of translation initiation factor eIF2 at serine 51 (eIF2aS51P) is a key regulator of mRNA translation and an important determinant of cell fate under stress. Some studies have provided evidence for a cross-talk between mTOR and eIF2aS51P under stress through poorly defined mechanisms. Herein, we demonstrate that genetic as well as pharmacological inhibition of mTOR complex 2 (mTORC2) induces eIF2aS51P via the activation of the endoplasmic reticulum (ER)-resident kinase PERK/PEK as a result of Akt inactivation. Analysis of the functional interplay between eIF2aS51P and mTOR in tuberous sclerosis complex (TSC)-deficient cells showed that mTORC2 inactivation induces the PERK-eIF2aS51P arm to substitute for the loss of Akt and promote survival in response to ER stress (see Figure above). On the other hand, TSC-deficient cells decrease PERK activity and increase the activity of the double-stranded RNA-activated protein kinase PKR to promote death via eIF2aS51P, JNK activation and increased autophagy in response to oxidative stress (see attached Figure). The balance between PERK inactivation and PKR activation in TSC-mutant cells under oxidative stress is controlled by mTORC1 and ribosomal S6 kinase 1, 2 (S6K1, 2) activity. Impaired eIF2aS51P accelerates TSC-mutant tumor initiation in mice, which is associated with an impaired production of reactive oxygen species (ROS) compared to eIF2aS51P-proficient TSC-mutant tumors. Our study reveals that eIF2aS51P acts as a double-edged sword downstream of mTOR to promote either survival or death in response to distinct forms of stress with implications in tumor development and treatment with chemotherapeutic drugs. Download : Download full-size image P5.03 FIGURES .

Immunopathology of Central Nervous System Tumors

The central nervous system (CNS) is characterized by unique immune biology. Distinct mechanisms of CNS immune surveillance and activation have important implications in tumor development as CNS tumors are known to evade anti-tumoral immunity, and may also contribute to immunosuppression. Multiple cell-surface and secreted mediators, expressed in both CNS tumor cells and responding immune cells, have been shown to influence the immune response to CNS tumors. In this review we provide an overview of CNS tumor immune escape and immunosuppression, highlighting the cellular and molecular features associated with both CNS tumors cells and responding immune cells. In this context, we discuss of the role of the M1 and M2 tumor associated macrophage phenotypes, myeloid derived suppressor cells, regulatory T-cells, as well as many immunomodulatory cytokines. Additionally, recent insights into the STAT-3 intracellular signaling pathway and the presence of active human CMV infection in the context of CNS tumor development are discussed.

Adiponectin receptor expression in gastric carcinoma: implications in tumor development and progression

Adiponectin, an adipocyte-secreted endogenous insulin sensitizer, appears to play an important role in progression of several malignancies. Expression of adiponectin receptors--AdipoR1 and AdipoR2--has been documented in gastric cancer (GC) cell lines, but its role in GCs is still controversial. We investigated expression level of 2 adiponectin receptors and correlated their expression with prognosis in GC patients. We immunohistochemically evaluated AdipoR1 and AdipoR2 expression in 59 non-neoplastic gastric mucosas, 48 gastric adenomas, 250 GCs, and 58 lymph nodes involved by metastatic GC and assessed its association with clinicopathologic characteristics. Expression rates of both receptors increased stepwise in non-neoplastic gastric mucosa, gastric adenoma, intestinal-type GC, and metastatic GC (p < 0.001). AdipoR1 and AdipoR2 expression was observed in 85 (34.0 %) and 118 (47.2 %) GC cases, respectively. Expression rates were higher in intestinal-type GC than in diffuse-type GC (p < 0.001 and 0.016, respectively). AdipoR1 and AdipoR2 expression was more frequent in advanced GC than in early GC (p < 0.001, each) and was associated with lymphatic invasion (p = 0.046 and 0.001, respectively). AdipoR2 expression was associated with poor overall and disease-free survival (p = 0.001 and 0.007, respectively). AdipoR1 expression was associated with poor disease-free survival for intestinal-type GC patients (p = 0.046). In multivariate analysis, AdipoR2 was an independent prognostic factor for intestinal-type GC (p = 0.017). Adiponectin receptor expression is related to GC development and progression, especially intestinal-type GC. Thus, adiponectin receptor expression can serve as a prognostic marker in GC patients.

Design and Synthesis of 3‐Carbamoylbenzoic Acid Derivatives as Inhibitors of Human Apurinic/Apyrimidinic Endonuclease 1 (APE1)

Apurinic/apyrimidinic (AP) endonuclease 1 (APE1) is a multifaceted protein with an essential role in the base excision repair (BER) pathway. Its implication in tumor development, progression, and resistance has been confirmed in multiple cancers, making it a viable target for intensive investigation. In this work, we designed and synthesized different classes of small-molecule inhibitors of the catalytic endonuclease function of APE1 that contain a 3-carbamoylbenzoic acid scaffold. Further structural modifications were made with the aim of increasing the activity and cytotoxicity of these inhibitors. Several of our compounds were shown to inhibit the catalytic endonuclease function of APE1 with potencies in the low-micromolar range in vitro, and therefore represent novel classes of APE1 inhibitors worthy of further development.

Integrative genomics: Liver regeneration and hepatocellular carcinoma

Numerous genome wide profiles of gene expression changes in human hepatocellular carcinoma (HCC), compared to normal liver tissue, have been reported. Hierarchical clustering of these data reveal distinct patterns, which underscore conservation between human disease and mouse models of HCC, as well as suggest specific classification of subtypes within the heterogeneous disease of HCC. Global profiling of gene expression in mouse liver, challenged by partial hepatectomy to regenerate, reveals alterations in gene expression that occur in response to acute injury, inflammation, and re-entry into cell cycle. When we integrated datasets of gene expression changes in mouse models of HCC and those that are altered at specific times of liver regeneration, we saw shared, conserved alterations in gene expression within specific biological pathways, both up-regulated, for example, cell cycle, cell death, and cellular development, or down-regulated, for example, vitamin and mineral metabolism, lipid metabolism, and molecular transport. Additional molecular mechanisms shared by liver regeneration and HCC, as yet undiscovered, may have important implications in tumor development and recurrence. These comparisons may offer a way to judge how liver resection, in the treatment of HCC, introduces challenges to care of the disease. Further, uncovering the pathways conserved in inflammatory response, hypertrophy, proliferation, and architectural remodeling of the liver, which are shared in liver regeneration and HCC, versus those specific to tumor development and progression in HCC, may reveal new biomarkers or potential therapeutic targets in HCC.

Transcriptional inhibition of connexin 43 BY EWS-FLI1: Implication in tumor development of ewing's sarcoma

Transcriptional inhibition of connexin 43 BY EWS-FLI1: Implication in tumor development of ewing's sarcoma

Analysis of immunoexpression of common cancer stem cell markers in ameloblastoma

Recent studies have established that, in benign tumors, a large number of cancer stem cells are present, which have great implications in tumor development. However, in ameloblastoma, a highly aggressive, locally invasive tumor with a high recurrence rate, whether or not cancer stem-like cells are present remains undetermined. Therefore, in this study we analyzed the protein expression of three candidate stem cell markers in ameloblastoma. Immunohistochemical staining for cancer stem cell (CSC) markers (CD133, CD44 and ABCG2) and for the proliferation marker Ki-67 was performed using 23 ameloblastoma cases. In all 23 samples, CD133, CD44 and ABCG2 were expressed. Nine (39.13%) cases showed high expression and 14 cases (60.87%) showed low expression for CD133. Twelve of the 23 cases (52.17%) showed high expression and 11 cases (47.83%) showed low expression for both CD44 and ABCG2, respectively. Ki-67 was mainly expressed in peripheral ameloblast-like cells, suggesting that these cells have a higher degree of differentiation and, therefore, are less likely to contain cancer stem-like cells. On the other hand, cells positive for CSC markers situated at the close proximity to peripheral cells were devoid of Ki-67 and may have the potential to be cancer stem-like cells. After analyzing the correlation between expression of three CSC markers with clinicopathological factors and Ki-67 expression, only CD44 expression was correlated with tumor recurrence (P=0.0391). In conclusion, this study showed various expression patterns of different types of cancer stem cell markers and the presence of candidate CSC-like cells in ameloblastoma, which are possibly involved in cell proliferation, tumor progression and recurrence.

Homeobox gene Dlx-2 is implicated in metabolic stress-induced necrosis

BackgroundIn contrast to tumor-suppressive apoptosis and autophagic cell death, necrosis promotes tumor progression by releasing the pro-inflammatory and tumor-promoting cytokine high mobility group box 1 (HMGB1), and its presence in tumor patients is associated with poor prognosis. Thus, necrosis has important clinical implications in tumor development; however, its molecular mechanism remains poorly understood.ResultsIn the present study, we show that Distal-less 2 (Dlx-2), a homeobox gene of the Dlx family that is involved in embryonic development, is induced in cancer cell lines dependently of reactive oxygen species (ROS) in response to glucose deprivation (GD), one of the metabolic stresses occurring in solid tumors. Increased Dlx-2 expression was also detected in the inner regions, which experience metabolic stress, of human tumors and of a multicellular tumor spheroid, an in vitro model of solid tumors. Dlx-2 short hairpin RNA (shRNA) inhibited metabolic stress-induced increase in propidium iodide-positive cell population and HMGB1 and lactate dehydrogenase (LDH) release, indicating the important role(s) of Dlx-2 in metabolic stress-induced necrosis. Dlx-2 shRNA appeared to exert its anti-necrotic effects by preventing metabolic stress-induced increases in mitochondrial ROS, which are responsible for triggering necrosis.ConclusionsThese results suggest that Dlx-2 may be involved in tumor progression via the regulation of metabolic stress-induced necrosis.

A SUMOylation motif in Aurora-A: implications for spindle dynamics and oncogenesis

Aurora-A is a serine/threonine kinase that plays critical roles in centrosome maturation, spindle dynamics, and chromosome orientation and it is frequently over-expressed in human cancers. In this work, we show that Aurora-A interacts with the SUMO-conjugating enzyme UBC9 and co-localizes with SUMO1 in mitotic cells. Aurora-A can be SUMOylated in vitro and in vivo. Mutation of the highly conserved SUMOylation residue lysine 249 significantly disrupts Aurora-A SUMOylation and mitotic defects characterized by defective and multipolar spindles ensue. The Aurora-AK249R mutant has normal kinase activity but displays altered dynamics at the mitotic spindle. In addition, ectopic expression of the Aurora-AK249R mutant results in a significant increase in susceptibility to malignant transformation induced by the Ras oncogene. These data suggest that modification by SUMO residues may control Aurora-A function at the spindle and that deficiency of SUMOylation of this kinase may have important implications for tumor development.