Beta 2 adrenergic receptor and mu opioid receptor interact to potentiate the aggressiveness of human breast cancer cell by activating the glycogen synthase kinase 3 signaling.

BACKGROUND: Opioid and beta-adrenergic receptors are recently shown to cross talk via formation of receptor heterodimers to control the growth and proliferation of breast cancer cells. However, the underlying cell signaling mechanism remained unclear. METHODS: To determine the effect of the interaction of the two systems in breast cancer, we employed triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468, CRISPR or chemical inhibition or activation of beta-adrenergic receptors (B2AR) and mu-opioid receptors (MOR) gene, and PCR array technology and studied aggressive tumor phenotype and signaling cascades. RESULTS: We show here that in triple-negative breast cancer cells, the reduction in expression B2AR and MOR by genetic and pharmacological tools leads to a less aggressive phenotype of triple-negative breast cancer cells in vitro and in animal xenografts. Genomic analysis indicates the glycogen synthase kinase 3 (GSK3) pathway as a possible candidate messenger system involved in B2AR and MOR cross talk. GSK3 inactivation in MDA-MB-231 and MDA-MB-468 cells induced similar phenotypic changes as the inhibition of B2AR and/or MOR, while a GSK3 activation by wortmannin reversed the effects of B2AR and/or MOR knockdown on these cells. GSK3 inactivation also prevents B2AR agonist norepinephrine or MOR agonist DAMGO from affecting MDA-MB-231 and MDA-MB-468 cell proliferation. CONCLUSIONS: These data confirm a role of B2AR and MOR interaction in the control of breast cancer cell growth and identify a possible role of the GSK3 signaling system in mediation of these two receptors' cross talk. Screening for ligands targeting B2AR and MOR interaction and/or the GSK3 system may help to identify novel drugs for the prevention of triple-negative breast cancer cell growth and metastasis.

Beta 2 Adrenergic Receptor Antagonist Propranolol and Opioidergic Receptor Antagonist Naltrexone Produce Synergistic Effects on Breast Cancer Growth Prevention by Acting on Cancer Cells and Immune Environment in a Preclinical Model of Breast Cancer.

Cancer progression is known to be promoted by increased body stress caused by elevated beta-adrenergic and opioidergic nervous system activities. The effects of ß2-adrenergic blocker propranolol (PRO) and µ-opioid receptor antagonist naltrexone (NTX) were tested using a preclinical model of human breast cancer. These drugs, individually, and more potently when combined, inhibited the cell growth and progression of breast cancer cells in vitro in cultures, and in vivo in rat xenografts. The antitumor activities of these drugs were associated with direct cell intrinsic effects, including increased cell growth arrest, elevated levels of apoptotic proteins, and reduced production of epithelial-mesenchymal transition factors by the tumor cells, as well as effects on innate immune activation and reduced inflammatory cytokine levels in plasma. These data suggest that the combined treatments of PRO and NTX produce impressive antitumor effects in the preclinical breast cancer model, and thereby may provide a new combinatorial treatment strategy with more clinical treatment modalities.

ER Translocation of the MAPK Pathway Drives Therapy Resistance in BRAF-Mutant Melanoma.

Resistance to BRAF and MEK inhibitors (BRAFi + MEKi) in BRAF-mutant tumors occurs through heterogeneous mechanisms, including ERK reactivation and autophagy. Little is known about the mechanisms by which ERK reactivation or autophagy is induced by BRAFi + MEKi. Here, we report that in BRAF-mutant melanoma cells, BRAFi + MEKi induced SEC61-dependent endoplasmic reticulum (ER) translocation of the MAPK pathway via GRP78 and KSR2. Inhibition of ER translocation prevented ERK reactivation and autophagy. Following ER translocation, ERK exited the ER and was rephosphorylated by PERK. Reactivated ERK phosphorylated ATF4, which activated cytoprotective autophagy. Upregulation of GRP78 and phosphorylation of ATF4 were detected in tumors of patients resistant to BRAFi + MEKi. ER translocation of the MAPK pathway was demonstrated in therapy-resistant patient-derived xenografts. Expression of a dominant-negative ATF4 mutant conferred sensitivity to BRAFi + MEKi in vivo. This mechanism reconciles two major targeted therapy resistance pathways and identifies druggable targets, whose inhibition would likely enhance the response to BRAFi + MEKi. SIGNIFICANCE: ERK reactivation and autophagy are considered distinct resistance pathways to BRAF + MEK inhibition (BRAFi + MEKi) in BRAF V600E cancers. Here, we report BRAFi + MEKi-induced ER translocation of the MAPK pathway is necessary for ERK reactivation, which drives autophagy. The ER translocation mechanism is a major druggable driver of resistance to targeted therapy.This article is highlighted in the In This Issue feature, p. 305.

Induction of Telomere Dysfunction Prolongs Disease Control of Therapy-Resistant Melanoma.

Purpose: Telomerase promoter mutations are highly prevalent in human tumors including melanoma. A subset of patients with metastatic melanoma often fail multiple therapies, and there is an unmet and urgent need to prolong disease control for those patients.Experimental Design: Numerous preclinical therapy-resistant models of human and mouse melanoma were used to test the efficacy of a telomerase-directed nucleoside, 6-thio-2'-deoxyguanosine (6-thio-dG). Integrated transcriptomics and proteomics approaches were used to identify genes and proteins that were significantly downregulated by 6-thio-dG.Results: We demonstrated the superior efficacy of 6-thio-dG both in vitro and in vivo that results in telomere dysfunction, leading to apoptosis and cell death in various preclinical models of therapy-resistant melanoma cells. 6-thio-dG concomitantly induces telomere dysfunction and inhibits the expression level of AXL.Conclusions: In summary, this study shows that indirectly targeting aberrant telomerase in melanoma cells with 6-thio-dG is a viable therapeutic approach in prolonging disease control and overcoming therapy resistance. Clin Cancer Res; 24(19); 4771-84. ©2018 AACR See related commentary by Teh and Aplin, p. 4629.

Impact of epigenetics in aging and age related neurodegenerative diseases.

Epigenetics involves multiple processes such as DNA methylation, histone code modifications, and noncoding RNAs to regulate gene expression. In recent years the implications of epigenetic mechanisms have emerged in the field of neuroscience especially in brain development, memory, learning, and various cognition processes. Epigenetics also plays a pivotal role during the aging process of the brain which has led to various age-related neurodegenerative diseases. This manuscript portrays the findings of various epigenetic mechanisms that play a critical role and their implications in aging as well as  age-related neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and Huntington's disease.

Hypothalamic beta-endorphin neurons suppress preneoplastic and neoplastic lesions development in 1,2-dimethylhydrazine induced rat colon cancer model.

In recent years, experimental studies demonstrated negative impacts of impaired body stress response on colonic pathologies. In this study, we tested if reducing body stress response by the use of ß-endorphin (BEP) neuronal transplants in the hypothalamus suppresses pre-neoplastic and neoplastic lesions. Colon cancer was induced by injecting 1,2-dimethylhydrazine (DMH) for sixteen weeks in Sprague Dawley rats with BEP neuron transplants or control neuron transplants, and their colonic histopathologies, colon tissue levels of pro-inflammatory cytokines and epithelial-mesenchymal transition (EMT) proteins and splenic levels of cytotoxic proteins were measured. Our results revealed that DMH induced tumors in colon at 100% incidence in control rats but failed to induce colonic tumors in 70% of animal with BEP neuronal transplants. The mean volume of tumor at the colon was smaller in BEP neurons transplanted rats than those in controls. Histopathologies of colon tissues revealed that BEP neurons transplanted animals had lesser tissue lesions such as aberrant crypt foci (ACF) and adenocarcinoma development in the colon than those in control groups. Immunohistochemical and western blot analyses identified reduced expression of Ki-67, TNF-α and NF-κB nuclear translocation in colonic tissues of BEP neurons transplanted rats than those in controls. BEP neurons transplanted rats also showed reduced expressions of transcription factors linked to EMT like Snail, Twist, and N-cadherin, but increased the levels of an epithelial cell marker E-cadherin in colon tissue. Furthermore, splenic NK cells cytolytic proteins such as perforin, granzyme B and IFN-γ levels in BEP neurons transplanted rats were higher than those in control rats. These data suggest that BEP neuron transplants suppress the growth and progression of colonic tumors possibly by decreasing inflammatory mileu and EMT via activation of innate immune responses.

A Unified Approach to Targeting the Lysosome's Degradative and Growth Signaling Roles.

Lysosomes serve dual roles in cancer metabolism, executing catabolic programs (i.e., autophagy and macropinocytosis) while promoting mTORC1-dependent anabolism. Antimalarial compounds such as chloroquine or quinacrine have been used as lysosomal inhibitors, but fail to inhibit mTOR signaling. Further, the molecular target of these agents has not been identified. We report a screen of novel dimeric antimalarials that identifies dimeric quinacrines (DQ) as potent anticancer compounds, which concurrently inhibit mTOR and autophagy. Central nitrogen methylation of the DQ linker enhances lysosomal localization and potency. An in situ photoaffinity pulldown identified palmitoyl-protein thioesterase 1 (PPT1) as the molecular target of DQ661. PPT1 inhibition concurrently impairs mTOR and lysosomal catabolism through the rapid accumulation of palmitoylated proteins. DQ661 inhibits the in vivo tumor growth of melanoma, pancreatic cancer, and colorectal cancer mouse models and can be safely combined with chemotherapy. Thus, lysosome-directed PPT1 inhibitors represent a new approach to concurrently targeting mTORC1 and lysosomal catabolism in cancer.Significance: This study identifies chemical features of dimeric compounds that increase their lysosomal specificity, and a new molecular target for these compounds, reclassifying these compounds as targeted therapies. Targeting PPT1 blocks mTOR signaling in a manner distinct from catalytic inhibitors, while concurrently inhibiting autophagy, thereby providing a new strategy for cancer therapy. Cancer Discov; 7(11); 1266-83. ©2017 AACR.See related commentary by Towers and Thorburn, p. 1218This article is highlighted in the In This Issue feature, p. 1201.

Epigenetic Modifications in Neurological Diseases: Natural Products as Epigenetic Modulators a Treatment Strategy.

Epigenetic modifications, including DNA methylation, covalent histone modifications, and small noncoding RNAs, play a key role in regulating the gene expression. This regulatory mechanism is important in cellular differentiation and development. Recent advances in the field of epigenetics extended the role of epigenetic mechanisms in controlling key biological processes such as genome imprinting and X-chromosome inactivation. Aberrant epigenetic modifications are associated with the development of many diseases. The role of epigenetic modifications in various neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington disease, epilepsy, and multiple sclerosis is rapidly emerging. The use of epigenetic modifying drugs to treat these diseases has been the interest in recent years. A number of natural products having diverse mechanism of action are used for drug discovery. For many years, natural compounds have been used to treat various neurodegenerative diseases, but the use of such compounds as epigenetic modulators to reverse or treat neurological diseases are not well studied. In this chapter, we mainly focus on how various epigenetic modifications play a key role in neurodegenerative diseases, their mechanism of action, and how it acts as a potential therapeutic target for epigenetic drugs to treat these diseases will be discussed.

Methods for Studying Autophagy Within the Tumor Microenvironment.

Defective autophagy has been linked with many pathologies, including cancer, diabetes, infectious disease, myopathies, heart, liver, lung, and neurodegenerative disease. Autophagy has therefore become an important target in drug discovery. Recent advances have identified new ways to monitor autophagy in vitro and in vivo. Many assays rely on visualizing autophagy-related intracellular markers such as microtubule-associated protein light chain 3 (LC3) II, which have posed issues with in vivo and clinical translation of the in vitro assays. Here, we present an overview of current in vitro and in vivo methodologies to measure autophagy with a special focus on the tumor microenvironment.

Beta-endorphin cell therapy for cancer prevention.

ß-Endorphin (BEP)-producing neuron in the hypothalamus plays a key role in bringing the stress axis to a state of homeostasis and maintaining body immune defense system. Long-term delivery of BEP to obtain beneficial effect on chemoprevention is challenging, as the peptides rapidly develop tolerance. Using rats as animal models, we show here that transplantation of BEP neurons into the hypothalamus suppressed carcinogens- and hormone-induced cancers in various tissues and prevented growth and metastasis of established tumors via activation of innate immune functions. In addition, we show that intracerebroventricular administration of nanosphere-attached dibutyryl cyclic adenosine monophosphate (dbcAMP) increased the number of BEP neurons in the hypothalamus, reduced the stress response, enhanced the innate immune function, and prevented tumor cell growth, progression, and metastasis. BEP neuronal supplementation did not produce any deleterious effects on general health but was beneficial in suppressing age-induced alterations in physical activity, metabolic, and immune functions. We conclude that the neuroimmune system has significant control over cancer growth and progression, and that activation of the neuroimmune system via BEP neuronal supplementation/induction may have therapeutic value for cancer prevention and improvement of general health.

Fetal alcohol exposure disrupts metabolic signaling in hypothalamic proopiomelanocortin neurons via a circadian mechanism in male mice.

Early-life ethanol feeding (ELAF) alters the metabolic function of proopiomelanocortin (POMC)-producing neurons and the circadian expression of clock regulatory genes in the hypothalamus. We investigated whether the circadian mechanisms control the action of ELAF on metabolic signaling genes in POMC neurons. Gene expression measurements of Pomc and a selected group of metabolic signaling genes, Stat3, Sirt1, Pgc1-α, and Asb4 in laser-captured microdissected POMC neurons in the hypothalamus of POMC-enhanced green fluorescent protein mice showed circadian oscillations under light/dark and constant darkness conditions. Ethanol programmed these neurons such that the adult expression of Pomc, Stat3, Sirt, and Asb4 gene transcripts became arrhythmic. In addition, ELAF dampened the circadian peak of gene expression of Bmal1, Per1, and Per2 in POMC neurons. We crossed Per2 mutant mice with transgenic POMC-enhanced green fluorescent protein mice to determine the role of circadian mechanism in ELAF-altered metabolic signaling in POMC neurons. We found that ELAF failed to alter arrhythmic expression of most circadian genes, with the exception of the Bmal1 gene and metabolic signaling regulating genes in Per2 mutant mice. Comparison of the ELAF effects on the circadian blood glucose in wild-type and Per2 mutant mice revealed that ELAF dampened the circadian peak of glucose, whereas the Per2 mutation shifted the circadian cycle and prevented the ELAF dampening of the glucose peak. These data suggest the possibility that the Per2 gene mutation may regulate the ethanol actions on Pomc and the metabolic signaling genes in POMC neurons in the hypothalamus by blocking circadian mechanisms.

Protective effects of hypothalamic beta-endorphin neurons against alcohol-induced liver injuries and liver cancers in rat animal models.

BACKGROUND: Recently, retrograde tracing has provided evidence for an influence of hypothalamic ß-endorphin (BEP) neurons on the liver, but functions of these neurons are not known. We evaluated the effect of BEP neuronal activation on alcohol-induced liver injury and hepatocellular cancer. METHODS: Male rats received either BEP neuron transplants or control transplants in the hypothalamus and were randomly assigned to feeding alcohol-containing liquid diet or control liquid diet for 8 weeks or to treatment of a carcinogen diethylnitrosamine (DEN). Liver tissues of these animals were analyzed histochemically and biochemically for tissue injuries or cancer. RESULTS: Alcohol feeding increased liver weight and induced several histopathological changes such as prominent microvesicular steatosis and hepatic fibrosis. Alcohol feeding also increased the levels of triglyceride, hepatic stellate cell (HSC) activation factors, and catecholamines in the liver and endotoxin levels in the plasma. However, these effects of alcohol on the liver were reduced in animals with BEP neuron transplants. BEP neuron transplants also suppressed carcinogen-induced liver histopathologies such as extensive fibrosis, large focus of inflammatory infiltration, hepatocellular carcinoma (HCC), collagen deposition, numbers of preneoplastic foci, levels of HSC activation factors and catecholamines, as well as inflammatory milieu and increased the levels of natural killer cell cytotoxic factors in the liver. CONCLUSIONS: These findings are the first evidence for a role of hypothalamic BEP neurons in influencing liver functions. Additionally, the data identify that BEP neuron transplantation prevents hepatocellular injury and HCC formation possibly via influencing the immune function.

Alcohol exposure in utero increases susceptibility to prostate tumorigenesis in rat offspring.

BACKGROUND: Prenatal alcohol exposure has been shown to increase offspring susceptibility to some chemical carcinogens. Whether prenatal exposure to alcohol makes the offspring more susceptible to the development of prostate cancer is not known. Therefore, we determined whether any functional abnormalities and increased cancer susceptibility exist in the prostate of fetal alcohol-exposed male rats during the adult period. METHODS: Pregnant rats were fed with a liquid diet containing alcohol (alcohol-fed [AF]), or pair-fed with isocaloric liquid diet (PF) or ad libitum fed with rat chow (ad lib-fed). Male offspring of these rats were given N-Nitroso-N-methylurea and testosterone to induce prostate neoplasia or left untreated. Around 6 to 8 months of age, the prostates of these animals were processed for determination of biochemical changes and histopathologies. RESULTS: Prostates of noncarcinogen treated animals that were alcohol exposed during the prenatal period demonstrated inflammatory cell infiltration and epithelial atypia and increased number of proliferative cells in the ventral lobe of this gland, but the prostate of control animal showed normal cytoarchitecture. In addition, prenatal alcohol-exposed rats showed decreased levels of cell-cell adhesion marker and increased estrogenic activity in the ventral prostate. Prenatally ethanol (EtOH)-exposed rats, when treated with carcinogen and testosterone, showed histological evidence for high-grade prostatic intraepithelial neoplasia (PIN) primarily in the ventral prostate, whereas control animals showed only low-grade PIN. Prenatally EtOH-exposed rats treated with carcinogen and testosterone also showed increased number of proliferative cells and androgen receptor with concomitant decreased levels of tumor suppressor proteins in the ventral prostate. CONCLUSIONS: These results suggest for the first time that prenatal EtOH exposures induce histophysiological changes in the prostate as well as it increases the susceptibility of the prostate to develop neoplasia during adulthood.

Opiate antagonist prevents µ- and δ-opiate receptor dimerization to facilitate ability of agonist to control ethanol-altered natural killer cell functions and mammary tumor growth.

In the natural killer (NK) cells, δ-opiate receptor (DOR) and µ-opioid receptor (MOR) interact in a feedback manner to regulate cytolytic function with an unknown mechanism. Using RNK16 cells, a rat NK cell line, we show that MOR and DOR monomer and dimer proteins existed in these cells and that chronic treatment with a receptor antagonist reduced protein levels of the targeted receptor but increased levels of opposing receptor monomer and homodimer. The opposing receptor-enhancing effects of MOR and DOR antagonists were abolished following receptor gene knockdown by siRNA. Ethanol treatment increased MOR and DOR heterodimers while it decreased the cellular levels of MOR and DOR monomers and homodimers. The opioid receptor homodimerization was associated with an increased receptor binding, and heterodimerization was associated with a decreased receptor binding and the production of cytotoxic factors. Similarly, in vivo, opioid receptor dimerization, ligand binding of receptors, and cell function in immune cells were promoted by chronic treatment with an opiate antagonist but suppressed by chronic ethanol feeding. Additionally, a combined treatment of an MOR antagonist and a DOR agonist was able to reverse the immune suppressive effect of ethanol and reduce the growth and progression of mammary tumors in rats. These data identify a role of receptor dimerization in the mechanism of DOR and MOR feedback interaction in NK cells, and they further elucidate the potential for the use of a combined opioid antagonist and agonist therapy for the treatment of immune incompetence and cancer and alcohol-related diseases.

Chronic shift-lag alters the circadian clock of NK cells and promotes lung cancer growth in rats.

Prolonged subjection to unstable work or lighting schedules, particularly in rotating shift-workers, is associated with an increased risk of immune-related diseases, including several cancers. Consequences of chronic circadian disruption may also extend to the innate immune system to promote cancer growth, as NK cell function is modulated by circadian mechanisms and plays a key role in lysis of tumor cells. To determine if NK cell function is disrupted by a model of human shift-work and jet-lag, Fischer (344) rats were exposed to either a standard 12:12 light-dark cycle or a chronic shift-lag paradigm consisting of 10 repeated 6-h photic advances occurring every 2 d, followed by 5-7 d of constant darkness. This model resulted in considerable circadian disruption, as assessed by circadian running-wheel activity. NK cells were enriched from control and shifted animals, and gene, protein, and cytolytic activity assays were performed. Chronic shift-lag altered the circadian expression of clock genes, Per2 and Bmal1, and cytolytic factors, perforin and granzyme B, as well as the cytokine, IFN-γ. These alterations were correlated with suppressed circadian expression of NK cytolytic activity. Further, chronic shift-lag attenuated NK cell cytolytic activity under stimulated in vivo conditions, and promoted lung tumor growth following i.v. injection of MADB106 tumor cells. Together, these findings suggest chronic circadian disruption promotes tumor growth by altering the circadian rhythms of NK cell function.

Regulation of cancer progression by ß-endorphin neuron.

It is becoming increasingly clear that stressful life events can affect cancer growth and metastasis by modulating nervous, endocrine, and immune systems. The purpose of this review is to briefly describe the process by which stress may potentiate carcinogenesis and how reducing body stress may prevent cancer growth and progression. The opioid peptide ß-endorphin plays a critical role in bringing the stress axis to a state of homeostasis. We have recently shown that enhancement of endogenous levels of ß-endorphin in the hypothalamus via ß-endorphin neuron transplantation suppresses stress response, promotes immune function, and reduces the incidence of cancer in rat models of prostate and breast cancers. The cancer-preventive effect of ß-endorphin is mediated through the suppression of sympathetic neuronal function, which results in increased peripheral natural killer cell and macrophage activities, elevated levels of anti-inflammatory cytokines, and reduced levels of inflammatory cytokines. ß-endorphin inhibition of tumor progression also involves alteration in the tumor microenvironment, possibly because of suppression of catecholamine and inflammatory cytokine production, which are known to alter DNA repair, cell-matrix attachments, angiogenic process, and epithelial-mesenchymal transition. Thus, ß-endorphin cell therapy may offer some therapeutic value in cancer prevention.

Transplantation of ß-endorphin neurons into the hypothalamus promotes immune function and restricts the growth and metastasis of mammary carcinoma.

Neurobehavioral stress has been shown to promote tumor growth and progression and dampen the immune system. In this study, we investigated whether inhibiting stress hormone production could inhibit the development of mammary carcinoma and metastasis in a rat model of breast carcinogenesis. To enhance ß-endorphin (BEP), the endogenous opioid polypeptide that boosts immune activity and decreases stress, we generated BEP neurons by in vitro differentiation from fetal neuronal stem cells and transplanted them into the hypothalami of rats subjected to breast carcinogenesis. BEP-transplanted rats displayed a reduction in mammary tumor incidence, growth, malignancy rate, and metastasis compared with cortical cells-transplanted rats. BEP neuron transplants also reduced inflammation and epithelial to mesenchymal transition in the tumor tissues. In addition, BEP neuron transplants increased peripheral natural killer (NK) cell and macrophage activities, elevated plasma levels of antiinflammatory cytokines, and reduced plasma levels of inflammatory cytokines. Antimetastatic effects along with stimulation of NK cells and macrophages could be reversed by treatment with the opiate antagonist naloxone, the ß-receptor agonist metaproterenol, or the nicotine acetylcholine receptor antagonist methyllycaconitine. Together, our findings establish a protective role for BEP against the growth and metastasis of mammary tumor cells by altering autonomic nervous system activities that enhance innate immune function.

A small oxazine compound as an anti-tumor agent: a novel pyranoside mimetic that binds to VEGF, HB-EGF, and TNF-α.

A novel pyranoside mimetic compound, DMBO (2-(2,6-difluorophenyl)-5-(4-methoxyphenyl)-1-oxa-3-azaspiro[5.5]undecane), was designed and synthesized. The sugar mimicking behavior of DMBO was addressed by its ability to bind several growth factors/cytokines such as vascular endothelial growth factor (VEGF), heparin-binding epidermal growth factor-like growth factor (HB-EGF), and tumor necrosis factor (TNF)-α as demonstrated by the recently developed surface plasmon resonance assay. DMBO exhibited strong anti-proliferation activity in vitro against tumor cells including a highly metastatic murine osteosarcoma cell line LM8G7 that secretes VEGF as well as two human ovarian cell lines, OVSAHO and SKOV-3, which secrete TNF-α and HB-EGF respectively. Furthermore, DMBO inhibited the metastatic activity to the mouse liver of LM8G7 cells injected from a lateral tail vein, and affected the heparan-degrading activity of LM8G7 cells. Here, we report that DMBO acts as a human heparanase inhibitor in vitro possibly as a substrate mimetic. DMBO also inhibited the migration and invasion of LM8G7 cells and angiogenic events such as endothelial cell proliferation, migration and capillary tube-like formation in vitro. More prominently, the administration of DMBO with heparin resulted in synergistic anti-tumor effects in mouse modelofosteosarcoma. These preclinical data shows the potential anti-cancer effects of DMBO.

Involvement of chondroitin sulfate E in the liver tumor focal formation of murine osteosarcoma cells.

Cell surface heparan sulfate plays a critical role in regulating the metastatic behavior of tumor cells, whereas the role of chondroitin sulfate/dermatan sulfate (CS/DS) has been little understood in this context. Here, we characterized CS/DS chains from the murine osteosarcoma cell line LM8G7, which forms tumor nodules in liver. Structural analysis of the CS/DS chains showed a higher proportion of GlcUA beta 1-3GalNAc(4,6-O-disulfate) (E-units) in LM8G7 (12%) than in its parental cell line LM8 (6%), which rarely forms tumors in the liver. Immunostaining with GD3G7, an antibody specific to E-units, confirmed the higher expression of the epitope in LM8G7 than LM8 cells. The tumor focal formation of LM8G7 cells in the liver in mice was effectively inhibited by the preadministration of CS-E (rich in E-unit) or the preincubation of the antibody GD3G7 with the tumor cells. CS-E or GD3G7 inhibited the adhesion of LM8G7 cells to a laminin-coated plate in vitro. In addition, the invasive ability of LM8G7 cells in vitro was also reduced by the addition of CS-E or the antibody. Further, CS-E or the antibody inhibited the proliferation of LM8G7 cells dose dependently. The binding of LM8G7 cells to VEGF in vitro was also significantly reduced by CS-E and GD3G7. Thus, the present study reveals the significance of highly sulfated CS/DS structures in the liver colonization of osteosarcoma cells and also provides a framework for the development of GAG-based anticancer molecules.