Transforming Growth Factor-β Receptor Type Research Articles

TFAP2C-mediated upregulation of TGFBR1 promotes lung tumorigenesis and epithelial-mesenchymal transition.

TFAP2C (transcription factor-activating enhancer-binding protein 2C) expression has been positively correlated with poor prognosis in patients with certain types of cancer, but the mechanisms underlying TFAP2C-mediated tumorigenesis in non-small-cell lung cancer (NSCLC) are still unknown. We previously performed a microarray analysis to identify TFAP2C regulation genes, and TGFBR1 (transforming growth factor-β receptor type 1) was found to be upregulated by TFAP2C. We observed that TFAP2C or TGFBR1 overexpression led to oncogenic properties, such as cell viability, proliferation and cell cycle progression. TGFBR1 upregulation induced by TFAP2C also promoted cell motility and migration, leading to malignant development. We also found that PAK1 (p21 protein (Cdc42/Rac)-activated kinase 1) signaling was involved in TFAP2C/TGFBR1-induced tumorigenesis. These results were confirmed by an in vivo xenograft model and patient tissue samples. This study shows that TFAP2C promoted tumor progression by upregulation of TGFBR1 and consequent activation of PAK1 signaling.

MicroRNA-101 protects cardiac fibroblasts from hypoxia-induced apoptosis via inhibition of the TGF-β signaling pathway

Cardiac fibroblasts (CFs) are the most numerous cells in the heart and are recognized primarily for their ability to maintain both the structural integrity and the physiological functions of the heart. The transforming growth factor beta (TGF-β) signaling pathway is reportedly involved in the modulation of CF functions, including apoptosis. Recent studies have indicated that microRNA-101 (miR-101) attenuates the TGF-β signaling pathway, either by inhibiting the expression of TGFβ1 or by targeting transforming growth factor-β receptor type I (TGFβRI). The present study aimed to determine whether miR-101 protects CFs from hypoxia-induced apoptosis and to investigate the mechanisms underlying its protective effects. The CCK-8 test, electron microscopy and TUNEL assay results demonstrated that miR-101a/b significantly inhibited hypoxia-induced CF apoptosis. The results of Western blotting, quantitative RT-PCR and immunofluorescence assays indicated that miR-101a dramatically inhibited the hypoxia-induced up-regulation of both TGFβRI and p-Smad 3 but not TGFβ1 in CFs. Additionally, miR-101a significantly reversed the hypoxia-induced up-regulation of Bax and Caspase-3, the down-regulation of Bcl-2 and the activation of Caspase-3 in CFs. Moreover, miR-101a markedly inhibited the intracellular Ca2+ ([Ca2+]i) overload caused by hypoxia. Taken together, our results suggest that miR-101a protects CFs against hypoxia-induced apoptosis by inhibiting the TGF-β signaling pathway, which may be a potential therapeutic target for heart injury.

Expression and significance of transforming growth factor-β receptor type II and DPC4/Smad4 in non-small cell lung cancer.

The aim of the present study was to investigate the expression levels of transforming growth factor-β (TGF-β) receptor type II (TβRII) and DPC4/Smad4 in the TGF-β signaling pathway and the importance of these expression levels in non-small cell lung cancer (NSCLC). The mRNA and protein expression levels of TβRII and DPC4/Smad4 were detected by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively, in NSCLC and control nonlesional lung tissues of 60 patients. The protein expression levels of DPC4/Smad4 were detected by immunohistochemistry in paraffin-embedded samples of NSCLC. In addition, the correlations among the expression levels of TβRII and DPC4/Smad4 and their association with the clinical and pathological features of NSCLC were analyzed. The expression levels of TβRII and DPC4/Smad4 in NSCLC tissues were significantly lower when compared with the control nonlesional lung tissues (P<0.05). In addition, the expression of TβRII and DPC4/Smad4 in poorly-differentiated NSCLC tissues was significantly lower compared with moderately- or well-differentiated NSCLC tissues (P<0.05). The expression levels of TβRII and DPC4/Smad4 were significantly lower in NSCLC tissues with metastatic lymph nodes compared with tissue without metastatic lymph nodes (P<0.05). Thus, the expression levels were demonstrated to significantly correlate with the clinical and pathological stages, and subsequently were shown to be associated with the occurrence and progression of NSCLC. In conclusion, TβRII and DPC4/Smad4 may play an important role in the tumorigenesis, differentiation and progression of NSCLC via the TGF-β signaling pathway.

Leucine supplementation accelerates connective tissue repair of injured tibialis anterior muscle.

This study investigated the effect of leucine supplementation on the skeletal muscle regenerative process, focusing on the remodeling of connective tissue of the fast twitch muscle tibialis anterior (TA). Young male Wistar rats were supplemented with leucine (1.35 g/kg per day); then, TA muscles from the left hind limb were cryolesioned and examined after 10 days. Although leucine supplementation induced increased protein synthesis, it was not sufficient to promote an increase in the cross-sectional area (CSA) of regenerating myofibers (p > 0.05) from TA muscles. However, leucine supplementation reduced the amount of collagen and the activation of phosphorylated transforming growth factor-β receptor type I (TβR-I) and Smad2/3 in regenerating muscles (p < 0.05). Leucine also reduced neonatal myosin heavy chain (MyHC-n) (p < 0.05), increased adult MyHC-II expression (p < 0.05) and prevented the decrease in maximum tetanic strength in regenerating TA muscles (p < 0.05). Our results suggest that leucine supplementation accelerates connective tissue repair and consequent function of regenerating TA through the attenuation of TβR-I and Smad2/3 activation. Therefore, future studies are warranted to investigate leucine supplementation as a nutritional strategy to prevent or attenuate muscle fibrosis in patients with several muscle diseases.

Expression Profile of MicroRNA-200 Family in Hepatocellular Carcinoma With Bile Duct Tumor Thrombus

The aim of this study was to assess the role of the miR-200 family in the pathogenesis of hepatocellular carcinoma with bile duct tumor thrombus (HCC-BDTT). Hepatocellular carcinoma with bile duct tumor thrombus is a challenging condition because of its rarity and dismal prognosis. Epithelial-to-mesenchymal transition (EMT) is considered a critical step in the progression and metastasis of HCC and is regulated by the microRNA-200 (miR-200) family. Thirty patients with HCC-BDTT were enrolled and 1240 patients with conventional HCC (cHCC) served as clinicopathologic controls. Sixty age- and sex-matched cHCC patients were selected to compare the miR-200 family expression profile and immunohistochemical characteristics. Gain- and loss-of-function studies of the miR-200 family were conducted using the hepatoma cell lines. Although the mean size of HCC-BDTT was smaller than that of cHCC, the former had a higher incidence of vascular invasion and a poorer long-term survival. The expressions of miR-200c and miR-141 were downregulated in HCC-BDTT (4.5- and 4.8-fold decrease, respectively). Downregulation of both miR-200c and miR-141 independently predicted disease-free survival. The HCC-BDTT, but not cHCC, exhibited overexpression of ZEB1, Twist, transforming growth factor-β receptor type II, and vimentin, and aberrant E-cadherin expression, indicating EMT. The HCC-BDTT demonstrated increased expression in IL-6 and stemness factor Bmi1, but reduced level of metastasis-suppressive protein, insulin-like growth factor-binding protein 4. The invasive ability of the highly aggressive Mahlavu cell was attenuated by pre-miR-200c+141, whereas the invasive ability of the less aggressive Huh7 cell was enhanced by anti-miR-200c+141. Simultaneous silencing of miR-200c and miR-141 was likely to be responsible for the development of HCC-BDTT via ZEB1-directed EMT activation and Sec23a-mediated secretome.

Functional proteomics, human genetics and cancer biology of GIPC family members.

GIPC1, GIPC2 and GIPC3 consist of GIPC homology 1 (GH1) domain, PDZ domain and GH2 domain. The regions around the GH1 and GH2 domains of GIPC1 are involved in dimerization and interaction with myosin VI (MYO6), respectively. The PDZ domain of GIPC1 is involved in interactions with transmembrane proteins [IGF1R, NTRK1, ADRB1, DRD2, TGFβR3 (transforming growth factorβ receptor type III), SDC4, SEMA4C, LRP1, NRP1, GLUT1, integrin α5 and VANGL2], cytosolic signaling regulators (APPL1 and RGS19) and viral proteins (HBc and HPV-18 E6). GIPC1 is an adaptor protein with dimerizing ability that loads PDZ ligands as cargoes for MYO6-dependent endosomal trafficking. GIPC1 is required for cell-surface expression of IGF1R and TGFβR3. GIPC1 is also required for integrin recycling during cell migration, angiogenesis and cytokinesis. On early endosomes, GIPC1 assembles receptor tyrosine kinases (RTKs) and APPL1 for activation of PI3K–AKT signaling, and G protein-coupled receptors (GPCRs) and RGS19 for attenuation of inhibitory Gα signaling. GIPC1 upregulation in breast, ovarian and pancreatic cancers promotes tumor proliferation and invasion, whereas GIPC1 downregulation in cervical cancer with human papillomavirus type 18 infection leads to resistance to cytostatic transforming growth factorβ signaling. GIPC2 is downregulated in acute lymphocytic leukemia owing to epigenetic silencing, while Gipc2 is upregulated in estrogen-induced mammary tumors. Somatic mutations of GIPC2 occur in malignant melanoma, and colorectal and ovarian cancers. Germ-line mutations of the GIPC3 or MYO6 gene cause nonsyndromic hearing loss. As GIPC proteins are involved in trafficking, signaling and recycling of RTKs, GPCRs, integrins and other transmembrane proteins, dysregulation of GIPCs results in human pathologies, such as cancer and hereditary deafness.

CD44 Deficiency Contributes to Enhanced Experimental Autoimmune Encephalomyelitis: A Role in Immune Cells and Vascular Cells of the Blood–Brain Barrier

Adhesion molecule CD44 is expressed by multiple cell types and is implicated in various cellular and immunological processes. In this study, we examined the effect of global CD44 deficiency on myelin oligodendrocyte glycoprotein peptide (MOG)-induced experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. Compared to C57BL/6 wild-type mice, CD44-deficient mice presented with greater disease severity, increased immune cell numbers in the central nervous system, and increased anti-MOG antibody and proinflammatory cytokine production, especially those associated with T helper 17 (Th17) cells. Further, decreased numbers of peripheral CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) were observed in CD44-knockout mice throughout the disease course. CD44-knockout CD4 T cells exhibited reduced transforming growth factor-β receptor type I (TGF-β RI) expression that did not impart a defect in Treg polarization invitro, but did correlate with enhanced Th17 polarization invitro. Further, EAE in bone marrow-chimeric animals suggested CD44 expression on both circulating and noncirculating cells limited disease severity. Endothelial expression of CD44 limited T-cell adhesion to and transmigration through murine endothelial monolayers invitro. Importantly, we also identified increased permeability of the blood-brain barrier invivo in CD44-deficient mice before and following immunization. These data suggest that CD44 has multiple protective roles in EAE, with effects on cytokine production, T-cell differentiation, T-cell-endothelial cell interactions, and blood-brain barrier integrity.

Signal transduction pathway analysis in desmoid‐type fibromatosis: Transforming growth factor–β, COX2 and sex steroid receptors

Despite reports of sex steroid receptor and COX2 expression in desmoid-type fibromatosis, responses to single agent therapy with anti-estrogens and non-steroidal anti-inflammatory drugs are unpredictable. Perhaps combination pharmacotherapy might be more effective in desmoid tumors that co-express these targets. Clearly, further understanding of the signaling pathways deregulated in desmoid tumors is essential for the development of targeted molecular therapy. Transforming growth factor-β (TGFβ) and bone morphogenetic proteins (BMP) are important regulators of fibroblast proliferation and matrix deposition, but little is known about the TGFβ superfamily in fibromatosis. A tissue microarray representing 27 desmoid tumors was constructed; 14 samples of healing scar and six samples of normal fibrous tissue were included for comparison. Expression of selected receptors and activated downstream transcription factors of TGFβ family signaling pathways, β-catenin, sex steroid hormone receptors and COX2 were assessed using immunohistochemistry; patterns of co-expression were explored via correlational statistical analyses. In addition to β-catenin, immunoreactivity for phosphorylated SMAD2/3 (indicative of active TGFβ signaling) and COX2 was significantly increased in desmoid tumors compared with healing scar and quiescent fibrous tissue. Low levels of phosphorylated SMAD1/5/8 were detected in only a minority of cases. Transforming growth factor-β receptor type 1 and androgen receptor were expressed in both desmoid tumors and scar, but not in fibrous tissue. Estrogen receptor-β was present in all cases studied. Transforming growth factor-β signaling appears to be activated in desmoid-type fibromatosis and phosphorylated SMAD2/3 and COX2 immunoreactivity might be of diagnostic utility in these tumors. Given the frequency of androgen receptor, estrogen receptor-β and COX2 co-expression in desmoid tumors, further assessment of the efficacy of combination pharmacotherapy using hormonal agonists/antagonists together with COX2 inhibitors should be considered.

Imaging Findings in a Child With Loeys-Dietz Syndrome

A 3-year-old boy being followed up for bilateral club foot underwent a routine thorax radiography that revealed aortic arch enlargement. Echocardiography showed sinus of Valsalva dilatation. Because of clinical features such as hypertelorism, bifid uvula, and prominent forehead, a genetic investigation was conducted that confirmed Loeys-Dietz syndrome (LDS) by identifying a heterozygous mutation in the gene encoding transforming growth factor-β receptor type 2 (TGFBR2). Whole-body magnetic resonance angiography was performed on a 1.5T machine. The magnetic resonance protocol included 3-dimensional contrast-enhanced angiographic sequences of the body and time-of-flight sequences of the brain. Whole-body magnetic resonance imaging demonstrated typical cardiovascular findings: Dilatation of the aorta at the level of sinus of Valsalva; tortuosity of the aortic arch, the 2 internal carotid arteries, the 2 vertebral arteries, and left subclavian artery; …

Transforming Growth Factor-β Receptor Type II Deletion Increases the Multiplicity and Growth of K-ras–induced Lung Cancers

Transforming growth factor-β (TGF-β) is a pluripotent regulator of epithelial growth and homeostasis and functions as a tumor suppressor in numerous malignancies. TGF-β signaling defects are common in many malignancies, including non–small cell lung cancer (NSCLC); however, the mechanisms by which defective TGF-β signaling promotes lung cancer growth and development are relatively unknown. We generated a novel NSCLC mouse model by simultaneously activating oncogenic KrasG12D expression and deleting TGF-β receptor type II (TGF-βRII) in airway epithelial cells. Genetic manipulation was targeted to the airway by K5Cre*PR, which uses a keratin 5 (K5) promoter to direct expression of an RU486-inducible, Cre recombinase-progesterone receptor fusion protein to epithelial cells. K5Cre*PR.lox-stop-lox-KrasG12D.TGF-βRII flox/flox mice treated with tracheal RU486 develop multifocal NSCLC beginning at approximately 32 weeks of age. Interestingly, these animals develop both thyroid transcription factor (TTF)-positive adenocarcinomas and K5-positive squamous cell carcinomas. TGF-βRII deletion increases tumor multiplicity from 3.2 ± 1.7 to 49 ± 10 tumors per animal and increases average tumor size from 0.71 to 1.04 mm, compared with tumors generated in K5Cre*PR.LSL-KrasG12D mice (P < 0.05 for both comparisons). In addition, K5Cre*PR.LSL-KrasG12D.TGFβRII flox/flox mice have both increased serum and bronchoalveolar lavage (BAL) TGF-β1 levels as well as increased BAL macrophages. Mechanistically, TGF-βRII deletion increases the multiplicity and growth of K-ras–induced lung cancers through mechanisms involving increased proliferation and increased inflammation.

Оn the role of pro-fibrous cytokines in the pathogenesis of localized scleroderma

The content and skin distribution of the transforming growth factor β 1 (TGF-β 1), transforming growth factor-β receptor type I receptor (TGF-βRI) and platelet-derived growth factor receptor a (PDGFR-α), which are key fibrosis mediators, were examined in ten patients with localized scleroderma and ten healthy volunteers by using the immunohistochemistry method. A reduced derma concentration of TGF-β 1+ cells (р = 0.007) and increased amount of TGF-βRI+ (р = 0.001) and PDGFR-α+ (р &lt; 0.001) cells was discovered in the patients vs. the control group. Te reduced amount of TGF-β 1 in the affected loci can be apparently explained by its reduced production by cells taking part in the immune inflammation. Increased expression of TGF-βRI receptors (р = 0.001) and PDGFR-α in the foci of localized scleroderma confirms their important role in the pathogenesis of the disease and activation of the fibrosis process in the skin.

Functional Transforming Growth Factor-β Receptor Type II Expression by CD4+ T Cells in Peyer's Patches Is Essential for Oral Tolerance Induction

Our previous studies have shown that Peyer's patches (PPs) play a key role in the induction of oral tolerance. Therefore, we hypothesized that PPs are an important site for Transforming Growth Factor (TGF)- β signaling and sought to prove that this tissue is of importance in oral tolerance induction. We found that expression of TGF-β type II receptor (TGFβRII) by CD4+ T cells increases and persists in the PPs of normal C57BL/6 mice after either high- or low-dose feeding of OVA when compared to mesenteric lymph nodes (MLNs) and spleen. Approximately one-third of these TGFβRII+ CD4+ T cells express the transcription factor Foxp3. Interestingly, the number of TGFβRII+ CD4+ T cells in PPs decreased when OVA-fed mice were orally challenged with OVA plus native cholera toxin (CT). In contrast, numbers of TGFβRII+ CD4+ T cells were increased in the intestinal lamina propria (iLP) of these challenged mice. Further, these PP CD4+ TGFβRII+ T cells upregulated Foxp3 within 2 hours after OVA plus CT challenge. Mice fed PBS and challenged with OVA plus CT did not reveal any changes in TGFβRII expression by CD4+ T cells. In order to test the functional property of TGFβRII in the induction of oral tolerance, CD4dnTGFβRII transgenic mice, in which TGFβRII signaling is abrogated from all CD4+ T cells, were employed. Importantly, these mice could not develop oral tolerance to OVA. Our studies show a critical, dose-independent, role for TGFβRII expression and function by CD4+ T cells in the gut-associated lymphoid tissues, further underlining the vital role of PPs in oral tolerance.

PBC: Animal Models of Cholangiopathies and Possible Endogenous Viral Infections.

Primary Biliary Cirrhosis (PBC) is considered an autoimmune disease characterized by immune-mediated destruction of the intrahepatic bile ducts and its characteristic serologic marker, the anti-mitochondrial antibody (AMA). Several factors were proposed to clarify the pathological and immunological mechanisms of PBC. Immunological reaction with a bacterial or a viral association was identified in the previous report, and it seems probable that PBC was thought to have such an etiology. The majority of patients with PBC was reported to have both RT-PCR and immunohistochemistry evidence of human betaretrovirus infection in lymph nodes or in 2008, the patient who developed PBC with high HIV viral load had an antiviral therapy and recovered. To understand the etiology of PBC associated with infection, several factors should be considered and especially animal models may be useful. In this paper, we introduce three typical animal models of PBC: the dominant-negative form of transforming growth factor-β receptor type II (dnTGFβRII) mouse, IL-2Rα −/− mouse and NOD.c3c4 mouse, are enumerated and described, and we discuss previous reports of viral infection associated with PBC and consider the etiology of PBC from our analysis of results in NOD.c3c4 mouse.

Lentiviral short hairpin RNA screen of human kinases and phosphatases to identify potential biomarkers in oral squamous cancer cells

Oral carcinoma is a serious public health problem and the leading cause of head and neck cancer mortality worldwide. Moreover, oral cancer patients often present symptoms at a late stage and show a high recurrence rate after treatment. Therefore, there is an urgent need to identify novel biomarkers for early diagnosis or clinical oral cancer therapy. In this study, we employed a subset of lentiviral short hairpin RNAs targeted against various kinases and phosphatases, designed by The RNAi Consortium, to screen systemically and in a high-throughput manner for potential growth regulators of oral cancer cells. The screen revealed a total of 50 candidate genes, for which more than 90% of growth inhibition in human oral squamous cancer HSC-3 cells was obtained. Furthermore, bioinformatic analysis of these candidate genes identified transforming growth factor-β receptor type II- and fms-related tyrosine kinase 3-related molecular pathways that are involved in NF-κB-mediated growth of HSC-3 cells. These candidate genes may be potential biomarkers for early diagnosis of oral cancer. In addition, these candidate genes represent potential targets for anticancer drug design helping to develop a personalized treatment to combat oral cancer.

The Coagulation System Contributes to αVβ6 Integrin Expression and Liver Fibrosis Induced by Cholestasis

Chronic injury to intrahepatic bile duct epithelial cells (BDECs) elicits expression of various mediators, including the αVβ6 integrin, promoting liver fibrosis. We tested the hypothesis that tissue factor (TF)-dependent thrombin generation and protease activated receptor-1 (PAR-1) activation contribute to liver fibrosis induced by cholestasis via induction of αVβ6 expression. To test this hypothesis, mice deficient in either TF or PAR-1 were fed a diet containing 0.025% α-naphthylisothiocyanate (ANIT), a BDEC-selective toxicant. In genetically modified mice with a 50% reduction in liver TF activity fed an ANIT diet, coagulation cascade activation and liver fibrosis were reduced. Similarly, liver fibrosis was significantly reduced in PAR-1(-/-) mice fed an ANIT diet. Hepatic integrin β6 mRNA induction, expression of αVβ6 protein by intrahepatic BDECs, and SMAD2 phosphorylation were reduced by TF deficiency and PAR-1 deficiency in mice fed the ANIT diet. Treatment with either an anti-αVβ6 blocking antibody or soluble transforming growth factor-β receptor type II reduced liver fibrosis in mice fed the ANIT diet. PAR-1 activation enhanced transforming growth factor-β1-induced integrin β6 mRNA expression in both transformed human BDECs and primary rat BDECs. Interestingly, TF and PAR-1 mRNA levels were increased in livers from patients with cholestatic liver disease. These results indicate that a TF-PAR-1 pathway contributes to liver fibrosis induced by chronic cholestasis by increasing expression of the αVβ6 integrin, an important regulator of transforming growth factor-β1 activation.

Nonsense-mediated translational repression involves exon junction complex downstream of premature translation termination codon

Human transforming growth factor-β receptor type 2 (TGFβR2) mRNA harboring a premature translation termination codon (PTC) generated by frameshift mutation is targeted for nonsense-mediated translational repression (NMTR), rather than nonsense-mediated mRNA decay (NMD). Here we show that exon junction complex (EJC) downstream of a PTC plays an inhibitory role in translation of TGFβR2 mRNA. Translational repression by core EJC components occurs after formation of 80S ribosome complex, which is demonstrated using different types of internal ribosome entry sites (IRESes). Our findings implicate EJCs or core EJC components as negative regulators of translation.

Serum albumin induces osmotic swelling of rat retinal glial cells

Edema in the ischemic neural tissue develops by increased vascular permeability associated with extravasation of albumin, and by glial swelling. Here, we show that bovine serum albumin acutely administered to slices of the rat retina causes swelling of glial somata under hypoosmotic conditions. The effect of albumin was dose-dependent, with half-maximal and maximal effects at 10 nM and 1 μM, respectively, and was mediated by activation of transforming growth factor-β receptor type II, oxidative stress, and the production of arachidonic acid and prostaglandins. Albumin-induced glial swelling was prevented by glutamate and purinergic receptor agonists. The data suggest that serum albumin may induce glial swelling in the presence of osmotic gradients.

Abstract B115: The epithelial to mesenchymal transition is impaired in colon cancer cells with microsatellite instability

Abstract Colorectal cancers (CRC) displaying DNA microsatellite instability (MSI) are associated with a favorable natural history, but the molecular basis for this observation has not been defined. We sought to determine whether the epithelial-to-mesenchymal transition (EMT), a highly conserved process involved in embryogenesis as well as in tumor progression, invasion, and metastasis, is impaired in MSI-positive CRCs that characteristically have a mutant transforming growth factor-β receptor type II (TGFBR2) gene. The induction of EMT by TGF-β1 was analyzed by phase contrast microscopy, immunofluorescence, qRT-PCR, immunoblotting, and cellular migration and invasion assays in MSS (SW480 and HT29) and MSI (DLD1 and HCT116) colon cancer cell lines. Expression of epithelial (E-cadherin) and mesenchymal (vimentin and N-cadherin) markers was evaluated by immunohistochemistry and qRT-PCR in 129 human colorectal tumors. TGF-β1 induced changes in cellular morphology from an epithelial to a fibroblasticlike morphology, changes in gene and protein expression with a reduction in E-cadherin and induction of vimentin, and changes in motility and invasion consistent with the occurrence of EMT only in MSS colon cancer cells. These effects did not require Smad4 but depended upon the recruitment of ERK. Cells with MSI and mutant TGFBR2 failed to exhibit any of these changes in response to TGF-β1. However, tumor cells with MSI but wildtype TGFBR2 underwent EMT in response to TGF-β1, indicating that TGFBR2 genotype is a key determinant of the EMT response in tumors with MSI. In human colorectal tumors, expression of the EMT markers N-cadherin and vimentin was significantly associated with adverse clinicopathologic features and the absence of MSI. These findings define a unique genotype-phenotype relationship between TGFBR2 and EMT that may contribute to the improved prognosis consistently observed in colon cancers with MSI. Furthermore, these results suggest a potential rationale for the therapeutic inhibition of TGF-β signaling in MSS colorectal tumors. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B115.

Hyperinsulinemic hypoglycemia with nesidioblastosis: histologic features and growth factor expression

Hypoglycemia secondary to nesidioblastosis is rare in adults, and the pathogenesis of this condition is unknown. To determine factors leading to nesidioblastosis in adults, we analyzed 36 cases of nesidioblastosis including 27 cases of postgastric bypass nesidioblastosis and 9 cases of idiopathic nesidioblastosis in adults by immunohistochemistry using antibodies to insulin-like growth factor1, insulin-like growth factor2 (IGF2), insulin-like growth factor one receptor-α epidermal growth factor receptor, transforming growth factor-β1 and 2, and transforming growth factor-β receptor type 3. Fifty-two surgically excised pancreatic specimens from patients with benign exocrine tumors and no evidence of hypoglycemia were used as controls. There was increased IGF2, insulin-like growth factor receptor1 receptor-α and transforming growth factor-β receptor 3 expression in islets from nesidioblastosis patients compared to controls. Peliosis-type vascular ectasia was more common in nesidioblastosis patients compared to controls. These findings suggest that increased production of growth factors and growth factor receptors may contribute to the development of nesidioblastosis in adults.

Methylation Silencing of Transforming Growth Factor-β Receptor Type II in Rat Prostate Cancers

To identify methylation-silenced genes in prostate cancers, a microarray analysis for genes up-regulated by treatment with a demethylating agent, 5-aza-2'-deoxycytidine, was performed using three rat prostate cancer cell lines. Eight genes (Aebp1, Dysf, Gas6, LOC361288, Nnat, Ocm, RGD1308119, and Tgfbr2) were re-expressed at 16-fold or more, and their promoter CpG islands were shown to be densely methylated in the cancer cell lines. From the eight genes, Tgfbr2, a key mediator of transforming growth factor-beta (TGF-beta) signaling that has been strongly implicated in human and rat prostate carcinogenesis, was selected, and its silencing in primary samples was analyzed further. Tgfbr2 was methylated and markedly down-regulated in three of seven 3,2'-dimethyl-4-aminobiphenyl-induced invasive adenocarcinomas in the dorsolateral lobe of the rat prostate. In humans, marked down-regulation of TGFBR2 protein was observed in 12 of 20 high-grade prostatic intraepithelial neoplasia and 36 of 60 prostate cancers. DNA methylation of the human TGFBR2 promoter CpG islands repressed transcription, if present, but neither methylation nor mutation were detected in 27 human prostate cancers analyzed. Methylation silencing of rat Tgfbr2 was associated with histone H3 lysine 9 trimethylation, whereas decreased expression of human TGFBR2 was mainly due to decreased transcription activity, sometimes in concert with histone deacetylation and H3 lysine 27 trimethylation. The identification of methylation silencing of Tgfbr2 in rat prostate cancers, in accordance with TGFBR2 down-regulation in human prostate cancers, will enable us to analyze how aberrant methylation is induced in vivo and identify factors that promote and suppress the induction of aberrant methylation.