Molecular mechanisms of inactivation of TGF-beta receptors during carcinogenesis

A novel GPI-anchored dominant-negative TGF-β receptor II renders T cells unresponsive to TGF-β signaling

Transforming growth factor β (TGF-β) is a pleiotropic cytokine expressed by a wide range of cell types and is known for hampering the effectiveness of cancer immune cell therapeutic approaches. We have designed a novel construct containing the extracellular domain of the TGF-β receptor II linked to a glycosylphosphatidylinositol (GPI) anchor (GPI-ecto-TβRII) lacking the transmembrane and cytoplasmic signaling domain of TGF-β receptor II (TβRII). T cells transduced with lentivirus expressing the GPI-ecto-TβRII construct show 5 to 15 times higher membrane expression compared with a previously established dominant-negative receptor carrying a truncated signaling domain. GPI-ecto-TβRII expression renders T cells unresponsive to TGF-β-induced signaling seen by a lack of SMAD phosphorylation upon exogeneous TGF-β treatment. Transduced T cells continue to express high levels of IFNγ and granulocyte-macrophage colony-stimulating factor (GM-CSF), among other cytokines, in the presence of TGF-β while cytokine expression in untransduced T cells is being markedly suppressed. Furthermore, T cells expressing GPI-ecto-TβRII constructs have been shown to efficiently capture and inactivate TGF-β from their environment. These results indicate the potential benefits of GPI-ecto-TβRII expressing cytotoxic T cells (CTLs) in future cell therapies.

Transforming Growth Factor-Beta (TGF-β) Signaling in Cancer-A Betrayal Within

A ubiquitously expressed cytokine, transforming growth factor-beta (TGF-β) plays a significant role in various ongoing cellular mechanisms. The gain or loss-of-function of TGF-β and its downstream mediators could lead to a plethora of diseases includes tumorigenesis. Specifically, at the early onset of malignancy TGF-β act as tumour suppressor and plays a key role in clearing malignant cells by reducing the cellular proliferation and differentiation thus triggers the process of apoptosis. Subsequently, TGF-β at an advanced stage of malignancy promotes tumorigenesis by augmenting cellular transformation, epithelial-mesenchymal-transition invasion, and metastasis. Besides playing the dual roles, depending upon the stage of malignancy, TGF-β also regulates cell fate through immune and stroma components. This oscillatory role of TGF-β to fight against cancer or act as a traitor to collaborate and crosstalk with other tumorigenic signaling pathways and its betrayal within the cell depends upon the cellular context. Therefore, the current review highlights and understands the dual role of TGF-β under different cellular conditions and its crosstalk with other signaling pathways in modulating cell fate.

SMAD4 is critical in suppression of BRAF-V600E serrated tumorigenesis

BRAF-driven colorectal cancer is among the poorest prognosis subtypes of colon cancer. Previous studies suggest that BRAF-mutant serrated cancers frequently exhibit Microsatellite Instability (MSI) and elevated levels of WNT signaling. The loss of tumor-suppressor Smad4 in oncogenic BRAF-V600E mouse models promotes rapid serrated tumor development and progression, and SMAD4 mutations co-occur in human patient tumors with BRAF-V600E mutations. This study assesses the role of SMAD4 in early-stage serrated tumorigenesis. SMAD4 loss promotes microsatellite stable (MSS) serrated tumors in an oncogenic BRAF-V600E context, providing a model for MSS serrated cancers. Inactivation of Msh2 in these mice accelerated tumor formation, and whole-exome sequencing of both MSS and MSI serrated tumors derived from these mouse models revealed that all serrated tumors developed oncogenic WNT mutations, predominantly in the WNT-effector gene Ctnnb1 (β-catenin). Mouse models mimicking the oncogenic β-catenin mutation show that the combination of three oncogenic mutations (Ctnnb1, Braf, and Smad4) are critical to drive rapid serrated dysplasia formation. Re-analysis of human tumor data reveals BRAF-V600E mutations co-occur with oncogenic mutations in both WNT and SMAD4/TGFβ pathways. These findings identify SMAD4 as a critical factor in early-stage serrated cancers and helps broaden the knowledge of this rare but aggressive subset of colorectal cancer.

TGF Beta Induces Vitamin D Receptor and Modulates Mitochondrial Activity of Human Pancreatic Cancer Cells

The inflammatory cytokine TGFβ is both a tumor suppressor during cancer initiation and a promoter of metastasis along cancer progression. Inflammation and cancer are strictly linked, and cancer onset often correlates with the insufficiency of vitamin D, known for its anti-inflammatory properties. In this study, we investigated the interplay between TGFβ and vitamin D in two models of human pancreatic cancer, and we analyzed the metabolic effects of a prolonged TGFβ treatment mimicking the inflammatory environment of pancreatic cancer in vivo. We confirmed the induction of the vitamin D receptor previously described in epithelial cells, but the inhibitory effects of vitamin D on epithelial-mesenchymal transition (EMT) were lost when the hormone was given after a long treatment with TGFβ. Moreover, we detected an ROS-mediated toxicity of the acute treatment with TGFβ, whereas a chronic exposure to low doses had a protumorigenic effect. In fact, it boosted the mitochondrial respiration and cancer cell migration without ROS production and cytotoxicity. Our observations shed some light on the multifaceted role of TGFβ in tumor progression, revealing that a sustained exposure to TGFβ at low doses results in an irreversibly increased EMT associated with a metabolic modulation which favors the formation of metastasis.

E3 Ubiquitin Ligases: Key Regulators of TGFβ Signaling in Cancer Progression

Transforming growth factor β (TGFβ) is a secreted growth and differentiation factor that influences vital cellular processes like proliferation, adhesion, motility, and apoptosis. Regulation of the TGFβ signaling pathway is of key importance to maintain tissue homeostasis. Perturbation of this signaling pathway has been implicated in a plethora of diseases, including cancer. The effect of TGFβ is dependent on cellular context, and TGFβ can perform both anti- and pro-oncogenic roles. TGFβ acts by binding to specific cell surface TGFβ type I and type II transmembrane receptors that are endowed with serine/threonine kinase activity. Upon ligand-induced receptor phosphorylation, SMAD proteins and other intracellular effectors become activated and mediate biological responses. The levels, localization, and function of TGFβ signaling mediators, regulators, and effectors are highly dynamic and regulated by a myriad of post-translational modifications. One such crucial modification is ubiquitination. The ubiquitin modification is also a mechanism by which crosstalk with other signaling pathways is achieved. Crucial effector components of the ubiquitination cascade include the very diverse family of E3 ubiquitin ligases. This review summarizes the diverse roles of E3 ligases that act on TGFβ receptor and intracellular signaling components. E3 ligases regulate TGFβ signaling both positively and negatively by regulating degradation of receptors and various signaling intermediates. We also highlight the function of E3 ligases in connection with TGFβ's dual role during tumorigenesis. We conclude with a perspective on the emerging possibility of defining E3 ligases as drug targets and how they may be used to selectively target TGFβ-induced pro-oncogenic responses.

Network-based Transcriptome-wide Expression Study for Postmenopausal Osteoporosis

PURPOSE

Menopause is a crucial physiological transition during a woman's life, and it occurs with growing risks of health issues like osteoporosis. To identify postmenopausal osteoporosis-related genes, we performed transcriptome-wide expression analyses for human peripheral blood monocytes (PBMs) using Affymetrix 1.0 ST arrays in 40 Caucasian postmenopausal women with discordant bone mineral density (BMD) levels.

METHODS

We performed multiscale embedded gene coexpression network analysis (MEGENA) to study functionally orchestrating clusters of differentially expressed genes in the form of functional networks. Gene sets net correlations analysis (GSNCA) was applied to assess how the coexpression structure of a predefined gene set differs in high and low BMD groups. Bayesian network (BN) analysis was used to identify important regulation patterns between potential risk genes for osteoporosis. A small interfering ribonucleic acid (siRNA)-based gene silencing in vitro experiment was performed to validate the findings from BN analysis.

RESULT

MEGENA showed that the "T cell receptor signaling pathway" and the "osteoclast differentiation pathway" were significantly enriched in the identified compact network, which is significantly correlated with BMD variation. GSNCA revealed that the coexpression structure of the "Signaling by TGF-beta receptor complex pathway" is significantly different between the 2 BMD discordant groups; the hub genes in the postmenopausal low and high BMD group are FURIN and SMAD3 respectively. With siRNA in vitro experiments, we confirmed the regulation relationship of TGFBR2-SMAD7 and TGFBR1-SMURF2.

MAIN CONCLUSION

The present study suggests that biological signals involved in monocyte recruitment, monocyte/macrophage lineage development, osteoclast formation, and osteoclast differentiation might function together in PBMs that contribute to the pathogenesis of postmenopausal osteoporosis.

Transforming growth factor beta receptor II (TGFBR2) promoter region polymorphism in Brazilian breast cancer patients: association with susceptibility, clinicopathological features, and interaction with TGFB1 haplotypes

PURPOSE

Transforming growth factor beta (TGFβ) has paradoxical effects in breast cancer (BC), inhibiting initial tumors while promoting aggressive ones. A polymorphism on TGFBR2 promoter region (G-875A, rs3087465) increases TGFβ type II receptor expression and is protective against cancer. Previously, we have shown that TGFB1 variants have subtype-specific roles in BC. This work sought to investigate the association between TGFBR2 and susceptibility and clinicopathological features in BC subgroups.

METHODS

TGFBR2 G-875A was analyzed through PCR-RFLP in 388 BC patients and 405 neoplasia-free women. Case-control analyses as well as interaction with TGFB1 haplotypes previously associated with BC were tested through age-adjusted logistic regression. Correlations between G-875A and clinicopathological parameters were assessed through Kendall's Tau-b test. All statistical tests were two-tailed (α = 0.05).

RESULTS

TGFBR2 G-875A was protective against BC in additive, genotypic, and dominant models. In subgroup-stratified analyses, these effects were greater in hormonal receptor-positive and luminal-A tumors, but were not significant in other subgroups. Logistic models including TGFB1 variants showed that in luminal-A tumors, G-875A retained its significance while TGFB1 haplotype showed a trend towards significance; otherwise, in HER2⁺ tumors TGFB1 variants remained significant while TGFBR2 showed a trend for association. There was no interaction between these genes. In correlation analyses, G-875A positively correlated with histopathological grade in total sample, and a trend towards significance was observed in triple-negative BCs.

CONCLUSION

These results indicate that G-875A is a protective factor against BC, especially from luminal-A subtype, but may promote anaplasia in established tumors, consistent with TGFβ signaling roles in BC.

GDF15 induced apoptosis and cytotoxicity in A549 cells depends on TGFBR2 expression

GDF15 plays a paradoxical role during carcinogenesis; it inhibits tumour growth in the early stages and promotes tumour cell proliferation in the late stages of cancer. Besides, GDF15 can induce apoptosis in some cancer cells including A549 but not in some others. Moreover, as a potential receptor for GDF15, TGFBR2 is inactivated during carcinogenesis in many types of cancers, and it is not present in cells with no GDF15 induced apoptosis. Thus, we tested whether GDF15 overexpression and/or TGFBR2 silencing can affect the GDF15 induced apoptosis in A549 cells. The full and mature forms of GDF15 were cloned and overexpressed in A549 cells. The TGFBR2 was silenced using specific siRNA and confirmed by real-time PCR. Results indicated that overexpression of full and mature forms of GDF15 as well as TGFBR2 knocked down reduced A549 cell viability in 24 and 48 hours. Flow cytometric analysis of annexin V/PI indicated induction of apoptosis in A549 cells by overexpression of GDF15 or silencing TGFBR2. Interestingly, the silencing of TGFBR2 inhibited the GDF15 induced cytotoxicity and apoptosis in A549 cells. Overexpression of GDF15 activated caspase-9 and caspase-3 and inhibited ERK1/2 and p38 phosphorylation in A549 cells. TGFBR2 knocked down inhibited GDF15 effects on caspases, ERK1/2, and p38MAPK activation. Our results indicated that the effect of GDF15 on apoptosis and activation of MAPK in A549 cells depends on TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression. SIGNIFICANCE OF THE STUDY: GDF15 plays a tumour suppressor or promotor roles during carcinogenesis. The expression of GDF15 induced cytotoxicity, apoptosis, and inhibition of MAPK in A549 cells. All these effects were blocked by silencing TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression.

Human Marfan and Marfan-like Syndrome associated mutations lead to altered trafficking of the Type II TGFβ receptor in Caenorhabditis elegans

The transforming growth factor-β (TGFβ) family plays an important role in many developmental processes and when mutated often contributes to various diseases. Marfan syndrome is a genetic disease with an occurrence of approximately 1 in 5,000. The disease is caused by mutations in fibrillin, which lead to an increase in TGFβ ligand activity, resulting in abnormalities of connective tissues which can be life-threatening. Mutations in other components of TGFβ signaling (receptors, Smads, Schnurri) lead to similar diseases with attenuated phenotypes relative to Marfan syndrome. In particular, mutations in TGFβ receptors, most of which are clustered at the C-terminal end, result in Marfan-like (MFS-like) syndromes. Even though it was assumed that many of these receptor mutations would reduce or eliminate signaling, in many cases signaling is active. From our previous studies on receptor trafficking in C. elegans, we noticed that many of these receptor mutations that lead to Marfan-like syndromes overlap with mutations that cause mis-trafficking of the receptor, suggesting a link between Marfan-like syndromes and TGFβ receptor trafficking. To test this hypothesis, we introduced three of these key MFS and MFS-like mutations into the C. elegans TGFβ receptor and asked if receptor trafficking is altered. We find that in every case studied, mutated receptors mislocalize to the apical surface rather than basolateral surface of the polarized intestinal cells. Further, we find that these mutations result in longer animals, a phenotype due to over-stimulation of the nematode TGFβ pathway and, importantly, indicating that function of the receptor is not abrogated in these mutants. Our nematode models of Marfan syndrome suggest that MFS and MFS-like mutations in the type II receptor lead to mis-trafficking of the receptor and possibly provides an explanation for the disease, a phenomenon which might also occur in some cancers that possess the same mutations within the type II receptor (e.g. colon cancer).

Identification of target gene and prognostic evaluation for lung adenocarcinoma using gene expression meta-analysis, network analysis and neural network algorithms

BACKGROUND

Lung adenocarcinoma (LUAD) is a heterogeneous disease with poor survival in the advanced stage and a high incidence rate in the world. Novel drug targets are urgently required to improve patient treatment. Therefore, we aimed to identify therapeutic targets for LUAD based on protein-protein and protein-drug interaction network analysis with neural network algorithms using mRNA expression profiles.

RESULTS

A comprehensive meta-analysis of selective non-small cell lung cancer (NSCLC) mRNA expression profile datasets from Gene Expression Omnibus were used to identify potential biomarkers and the molecular mechanisms related to the prognosis of NSCLC patients. Using the Network Analyst tool, based on combined effect size (ES) methods, we recognized 6566 differentially expressed genes (DEGs), which included 3036 downregulated and 3530 upregulated genes linked to NSCLC patient survival. ClueGO, a Cytoscape plugin, was exploited to complete the function and pathway enrichment analysis, which disclosed "regulated exocytosis", "purine nucleotide binding", "pathways in cancer", and "cell cycle" between exceptionally supplemented terms. Enrichr, a web tool examination, demonstrated "early growth response protein 1 (EGR-1)", "hepatocyte nuclear factor 4α (HNF4A)", "mitogen-activated protein kinase 14 (MAP3K14)", and "cyclin-dependent kinase 1 (CDK1)" to be among the most prevalent TFs and kinases associated with NSCLC. Our meta-analysis identified that MAPK1 and aurora kinase (AURKA) are the most obvious class of hub nodes. Furthermore, protein-drug interaction network and neural network algorithms identified candidate drugs such as phosphothreonine and 4-(4-methylpiperazin-1-yl)-n-[5-(2-thienylacetyl)-1,5-dihydropyrrolo[3,4-c]pyrazol-3-yl] benzamide and for the targets MAPK1 and AURKA, respectively.

CONCLUSION

Our study has identified novel candidate biomarkers, pathways, transcription factors (TFs), and kinases associated with NSCLC prognosis, as well as drug candidates, which may assist treatment strategy for NSCLC patients.

Galangin enhances TGF-β1-mediated growth inhibition by suppressing phosphorylation of threonine 179 residue in Smad3 linker region

Smad3 linker phosphorylation is a candidate target for several kinases that play important roles in cancer cell initiation, proliferation and progression. Also, Smad3 is an essential intracellular mediator of TGF-β1-induced transcriptional responses during carcinogenesis. Therefore, it is highly advantageous to identify and develop inhibitors targeting Smad3 linker phosphorylation for the treatment of cancers. Galangin (3,5,7-trihydroxyflavone) has been known to be an active flavonoid showing a cytotoxic effect on several cancer cells. However, the mechanism of action of galangin in various cancers remains unclear, and there has been no report concerning regulation of Smad3 phosphorylation by galangin. In the present study, we show that galangin significantly induced apoptosis and inhibited cell proliferation in the presence of TGF-β1 in both human prostate and pancreatic cancer cell lines. Particularly, galangin effectively inhibits phosphorylation of the Thr-179 site at Smad3 linker region through suppression of CDK4 phosphorylation. Thus, galangin can be a promising candidate as a selective inhibitor to suppress phosphorylation of Smad3 linker region.

Inhibition of Epithelial-Mesenchymal Transition and Metastasis by Combined TGFbeta Knockdown and Metformin Treatment in a Canine Mammary Cancer Xenograft Model

Epithelial mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties, generating metastases. Transforming growth factor beta (TGF-β) is associated with this malignancy by having the ability to induce EMT. Metformin, has been shown to inhibit EMT in breast cancer cells. Based on this evidence we hypothesize that treatment with metformin and the silencing of TGF-β, inhibits the EMT in cancer cells. Canine metastatic mammary tumor cell line CF41 was stably transduced with a shRNA-lentivirus, reducing expression level of TGF-β1. This was combined with metformin treatment, to look at effects on cell migration and the expression of EMT markers. For in vivo study, unmodified or TGF-β1sh cells were injected in the inguinal region of nude athymic female mice followed by metformin treatment. The mice's lungs were collected and metastatic nodules were subsequently assessed for EMT markers expression. The migration rate was lower in TGF-β1sh cells and when combined with metformin treatment. Metformin treatment reduced N-cadherin and increased E-cadherin expression in both CF41 and TGF-β1sh cells. Was demonstrated that metformin treatment reduced the number of lung metastases in animals bearing TGF-β1sh tumors. This paralleled a decreased N-cadherin and vimentin expression, and increased E-cadherin and claudin-7 expression in lung metastases. This study confirms the benefits of TGF-β1 silencing in addition to metformin as potential therapeutic agents for breast cancer patients, by blocking EMT process. To the best of our knowledge, we are the first to report metformin treatment in cells with TGF-β1 silencing and their effect on EMT.

The Role of TGF-β in Epithelial Malignancy and its Relevance to the Pathogenesis of Oral Cancer (Part II)

The role of transforming growth factor-β (TGF-β) in epithelial malignancy is complex, but it is becoming clear that, in the early stages of carcinogenesis, the protein acts as a potent tumor suppressor, while later, TGF-β can function to advance tumor progression. We review the evidence to show that the pro-oncogenic functions of TGF-β are associated with (1) a partial loss of response to the ligand, (2) defects of components of the TGF-β signal transduction pathway, (3) over-expression and/or activation of the latent complex, (4) epithelial-mesenchymal transition, and (5) recruitment of signaling pathways which act in concert with TGF-β to facilitate the metastatic phenotype. These changes are viewed in the context of what is known about the pathogenesis of oral cancer and whether this knowledge can be translated into the development of new therapeutic modalities.

A dual prognostic role for the TGFβ receptors in human breast cancer

The transforming growth factor-β (TGFβ) plays a dual role in breast cancer, acting as a tumor suppressor in early carcinomas while promoting tumor metastasis in more advanced breast carcinoma. As a result, the prognostic role of TGFβ and its signaling components in breast cancer remains unclear. Here we evaluated the expression levels of TGFβ signaling receptors TβRII and TβRI using human breast cancer tissue microarrays and a large publicly available gene profiling database in relation to various clinicopathological parameters. Our results indicate that breast cancer tissues express lower TβRII and TβRI protein levels compared with normal breast tissue. In contrast to TβRI expression, TβRII mRNA expression levels were also significantly downregulated in invasive breast cancer compared with normal breast tissue (4.18-fold downregulation, P=9.3×10^-115). Interestingly, within the cancer cases analyzed, our results revealed a direct correlation between high TβRII and TβRI expression levels and classic poor prognostic clinicopathological parameters, including larger tumor size, advanced tumor stage, and poorly differentiated tumors. Next, we examined TGFβ receptors' expression in relation to breast cancer molecular subtypes. Importantly, our results revealed that whereas expression of TGFβ receptors in luminal A and triple-negative breast cancer showed no correlation with patient outcome, their expression in luminal B and HER2 subtypes showed significant association with favorable patient outcome. Together, these results indicate that although TGFβ receptors are downregulated in breast cancer, their expression in tumors is an indicator of aggressive breast cancer phenotype. Moreover, the relation between TGFβ pathway and patient outcome is breast cancer subtype dependent.

EZH2 promotes progression of small cell lung cancer by suppressing the TGF-β-Smad-ASCL1 pathway

Transforming growth factor-β (TGF-β) induces apoptosis in many types of cancer cells and acts as a tumor suppressor. We performed a functional analysis of TGF-β signaling to identify a molecular mechanism that regulated survival in small cell lung cancer cells. Here, we found low expression of TGF-β type II receptor (TβRII) in most small cell lung cancer cells and tissues compared to normal lung epithelial cells and normal lung tissues, respectively. When wild-type TβRII was overexpressed in small cell lung cancer cells, TGF-β suppressed cell growth in vitro and tumor formation in vivo through induction of apoptosis. Components of polycomb repressive complex 2, including enhancer of zeste 2 (EZH2), were highly expressed in small cell lung cancer cells; this led to epigenetic silencing of TβRII expression and suppression of TGF-β-mediated apoptosis. Achaete-scute family bHLH transcription factor 1 (ASCL1; also known as ASH1), a Smad-dependent target of TGF-β, was found to induce survival in small cell lung cancer cells. Thus, EZH2 promoted small cell lung cancer progression by suppressing the TGF-β-Smad-ASCL1 pathway.

Emerging cytokine networks in colorectal cancer

Cytokine networks are crucial aspects of tumour immunology, particularly for colorectal cancer (CRC), in which inflammation and antitumour immunity are key determinants of disease progression. In this Review, we highlight new insights into the functions of well-known cytokines in CRC, describe recently discovered roles for a growing number of novel players, and emphasize the complexity and therapeutic implications of the cytokine milieu. We also discuss how cancer mutations and epigenetic adaptations influence the oncogenic potential of cytokines, a relatively unexplored area that could yield crucial insights into tumour immunology and facilitate the effective application of cytokine-modulatory therapies for CRC.

Protein deregulation associated with breast cancer metastasis

Breast cancer is one of the most prevalent malignancies worldwide. It consists of a group of tumor cells that have the ability to grow uncontrollably, overcome replicative senescence (tumor progression) and metastasize within the body. Metastases are processes that consist of an array of complex gene dysregulation events. Although these processes are still not fully understood, the dysregulation of a number of key proteins must take place if the tumor cells are to disseminate and metastasize. It is now widely accepted that future effective and innovative treatments of cancer metastasis will have to encompass all the major components of malignant transformation. For this reason, much research is now being carried out into the mechanisms that govern the malignant transformation processes. Recent research has identified key genes involved in the development of metastases, as well as their mechanisms of action. A detailed understanding of the encoded proteins and their interrelationship generates the possibility of developing novel therapeutic approaches. This review will focus on a select group of proteins, often deregulated in breast cancer metastasis, which have shown therapeutic promise, notably, EMT, E-cadherin, Osteopontin, PEA3, Transforming Growth Factor Beta (TGF-β) and Ran.

The anticancer effect of (1S,2S,3E,7E,11E)-3,7,11, 15-cembratetraen-17,2-olide(LS-1) through the activation of TGF-β signaling in SNU-C5/5-FU, fluorouracil-resistant human colon cancer cells

The anticancer effect of (1S,2S,3E,7E,11E)-3,7,11,15-cembratetraen-17,2-olide (LS-1) from Lobophytum sp. has been already reported in HT-29 human colorectal cancer cells. In this study, we examined the effect of LS-1 on the apoptosis induction of SNU-C5/5-FU, fluorouracil-resistant human colon cancer cells. Furthermore, we investigated whether the apoptosis-induction effect of LS-1 could arise from the activation of the TGF-β pathway. In SNU-C5/5-FU treated with LS-1 of 7.1 μM (IC50), we could observe the various apoptotic characteristics, such as the increase of apoptotic bodies, the increase of the sub-G1 hypodiploid cell population, the decrease of the Bcl-2 level, the increase of procaspase-9 cleavage, the increase of procaspase-3 cleavage and the increase of poly(ADP-ribose) polymerase cleavage. Interestingly, the apoptosis-induction effect of LS-1 was also accompanied by the increase of Smad-3 phosphorylation and the downregulation of c-Myc in SNU-C5/5-FU. LS-1 also increased the nuclear localization of phospho-Smad-3 and Smad-4. We examined whether LS-1 could downregulate the expression of carcinoembryonic antigen (CEA), a direct inhibitor of TGF-β signaling. LS-1 decreased the CEA level, as well as the direct interaction between CEA and TGF-βR1 in the apoptosis-induction condition of SNU-C5/5-FU. To examine whether LS-1 can induce apoptosis via the activation of TGF-β signaling, the SNU-C5/5-FU cells were treated with LS-1 in the presence or absence of SB525334, a TGF-βRI kinase inhibitor. SB525334 inhibited the effect of LS-1 on the apoptosis induction. These findings provide evidence demonstrating that the apoptosis-induction effect of LS-1 results from the activation of the TGF-β pathway via the downregulation of CEA in SNU-C5/5-FU.

Epigenetic regulation of inflammatory cytokines and associated genes in human malignancies

Inflammation is a multifaceted defense response of immune system against infection. Chronic inflammation has been implicated as an imminent threat for major human malignancies and is directly linked to various steps involved in tumorigenesis. Inflammatory cytokines, interleukins, interferons, transforming growth factors, chemokines, and adhesion molecules have been associated with chronic inflammation. Numerous cytokines are reported to be aberrantly regulated by different epigenetic mechanisms like DNA methylation and histone modifications in tumor tissues, contributing to pathogenesis of tumor in multiple ways. Some of these cytokines also work as epigenetic regulators of other crucial genes in tumor biology, either directly or indirectly. Such regulations are reported in lung, breast, cervical, gastric, colorectal, pancreatic, prostate, and head and neck cancers. Epigenetics of inflammatory mediators in cancer is currently subject of extensive research. These investigations may help in understanding cancer biology and to develop effective therapeutic strategies. The purpose of this paper is to have a brief view of the aberrant regulation of inflammatory cytokines in human malignancies.

Cytoplasmic DRAK1 overexpressed in head and neck cancers inhibits TGF-β1 tumor suppressor activity by binding to Smad3 to interrupt its complex formation with Smad4

Head and neck squamous cell carcinoma (HNSCC) is an extremely aggressive cancer with a poor prognosis and low patient survival. Because chemotherapy for advanced HNSCC is often ineffective, discovering new therapeutic targets that are important for HNSCC development and progression and elucidating their molecular mechanisms are required. In the present study, we describe the role of DRAK1 (death-associated protein kinase-related apoptosis-inducing kinase 1) as a novel negative regulator of the transforming growth factor-β (TGF-β) tumor suppressor signaling pathway for the first time in human HNSCC cells. DRAK1 was significantly overexpressed in primary human HNSCCs and in HNSCC cell lines. Through gain- and loss-of-function experiments, we demonstrated that the DRAK1 expression level regulated TGF-β1-induced transcriptional activity and expression of the tumor suppressor gene p21(Waf1/Cip1). DRAK1 depletion enhanced TGF-β1-induced growth inhibition in vitro and suppressed tumorigenicity in xenograft models in vivo. Mechanistically, DRAK1 was predominantly localized in the cytoplasm and bound to Smad3, thereby interrupting Smad3/Smad4 complex formation, which is the core process for the induction of tumor suppressor genes by TGF-β1. Thus, our findings suggest that cytoplasmic DRAK1 increases tumorigenic potential through inhibition of TGF-β1-mediated tumor suppressor activity in HNSCC cells and may be a potential therapeutic target for HNSCCs.

A TALEN-based specific transcript knock-down of PIWIL2 suppresses cell growth in HepG2 tumor cell

OBJECTIVES

PIWIL2 is widely expressed in various tumours and implicated in playing a role in tumourigenesis. For a more thorough study of PIWIL2 functions in tumour cells, we aimed to establish PIWIL2-specific transcript knock-down/knockout HepG2 cell lines using transcription activator-like effector nuclease (TALEN) technology. Furthermore, we proposed to use the cell models to explore PIWIL2 functions in TGF-β signalling in HepG2 cells. HepG2s are human hepatocellular carcinoma cells.

MATERIALS AND METHODS

We established PIWIL2 knock-down or knock-out cell lines in HepG2 using TALEN technology. Next, we sought to use the cell line models to investigate effects of full length PIWIL2-specific transcripts in cell proliferation induced by TGF-β.

RESULTS

First, we established PIWIL2-specific transcript mono-allele and bi-allele knockout HepG2 cell lines. By using the cell line models, we found that specific transcript knockdown of full length PIWIL2 can suppress cell proliferation, while ectopic expression of PIWIL2 enhanced proliferation of HepG2 by suppressing the TGF-β pathway. Furthermore, we demonstrated that PIWIL2 can interact with HSP90 to prevent formation of HSP90-TβR complexes, which promote degradation of TβRs.

CONCLUSIONS

Taken together, our study revealed critical negative regulation of TGF-β signalling by PIWIL2 in HepG2 tumour cells, and provided an effective strategy to study specific gene transcript functions in cells.

Restoring TGFβ1 pathway-related microRNAs: possible impact in metastatic prostate cancer development

In developed countries, prostate cancer (PC) is the neoplasia more frequently diagnosed in men. The signaling pathway induced by the transforming growth factor β1 (TGFβ1) has an important role in cell growth, differentiation, and development, the downregulation of this pathway being associated with cancer development. In PC, the activation of this signaling pathway is lost, resulting in favoring of tumor growth, proliferation, and evasion of apoptosis. Several studies have shown that microRNAs (miRNAs), small non-coding RNA, are closely associated with the development, invasion, and metastasis, suggesting that they have a critical role in cancer development. Recently, Smad proteins, the signal transducers of the TGFβ1 signaling pathway, were found to regulate miRNA expression, through both transcriptional and posttranscriptional mechanisms. In this review, we summarize the mechanisms underlying Smad-mediated regulation of miRNA biogenesis and the effects on cancer development, particularly in PC. We identify that TGFβ1-related miR-143, miR-145, miR-146a, and miR-199a may have a key role in the development of prostate cancer metastasis and the restoration of their expression may be a promising therapeutic strategy for PC treatment.

A reciprocal role of prostate cancer on stromal DNA damage

DNA damage found in prostate cancer-associated fibroblasts (CAF) promotes tumor progression. In the absence of somatic mutations in CAF, epigenetic changes dictate how stromal coevolution is mediated in tumors. Seventy percent of prostate cancer patients lose expression of transforming growth factor-beta type II receptor (TGFBR2) in the stromal compartment (n=77, P-value=0.0001), similar to the rate of glutathione S-transferase P1 (GSTP1) silencing. Xenografting of human prostate cancer epithelia, LNCaP, resulted in the epigenetic Tgfbr2 silencing of host mouse prostatic fibroblasts. Stromal Tgfbr2 promoter hypermethylation, initiated by LNCaP cells, was found to be dependent on interleukin 6 expression, based on neutralizing antibody studies. We further found that pharmacologic and transgenic knockout of TGF-β responsiveness in prostatic fibroblasts induced Gstp1 promoter methylation. It is known that TGF-β promotes DNA stability, however, the mechanism is not well understood. Both prostatic human CAF and mouse transgenic knockout of Tgbr2 had elevated DNA methyltransferase I (DNMT1) activity and histone H3 lysine 9 trimethylation (H3K9me3) to suggest greater promoter methylation. Interestingly, the conditional knockout of Tgfbr2 in mouse prostatic fibroblasts, in modeling epigenetic silencing of Tgfbr2, had greater epigenetic gene silencing of multiple DNA damage repair and oxidative stress response genes, based on promoter methylation array analysis. Homologous gene silencing was validated by reverse transcriptase (RT)-PCR in mouse and human prostatic CAF. Not surprisingly, DNA damage repair gene silencing in the prostatic stromal cells corresponded with the presence of DNA damage. Restoring the expression of the epigenetically silenced genes in wild-type fibroblasts with radiation-induced DNA damage reduced tumor progression. Tumor progression was inhibited even when epigenetic silencing was reversed in the Tgfbr2-knockout prostatic fibroblasts. Taken together, fibroblastic epigenetic changes causative of DNA damage, initiated by association with cancer epithelia, is a dominant mediator of tumor progression over TGF-β responsiveness.

Improvement of a predictive model of castration-resistant prostate cancer: functional genetic variants in TGFβ1 signaling pathway modulation

Prostate cancer (PC) is the most frequently diagnosed cancer in men. The acquisition of castration-resistant (CR) phenotype is associated with the activation of signaling pathways mediated by growth factors. The TGFβ1 and its receptors have an important role in tumor progression, being the pro-apoptotic function modulated by the expression of TGFBR2. A single nucleotide polymorphism -875 G > A in TGFBR2 gene has been described, which may influence the expression levels of the receptor. Our purpose was to investigate the potential role of TGFBR2-875G>A in PC risk and in the response to androgen deprivation therapy (ADT). TGFBR2-875G>A polymorphism was studied by allelic discrimination using real-time polymerase chain reaction (PCR) in 891 patients with PC and 874 controls. A follow-up study was undertaken to evaluate response to ADT. The TGFBR2 and SMAD7 mRNA expression were analyzed by a quantitative real-time PCR. We found that TGFBR2-875GG homozygous patients present lower expression levels of TGFBR2 mRNA (AA/AG: 2(-ΔΔCT) =1.5, P=0.016). GG genotype was also associated with higher Gleason grade (OR=1.51, P=0.019) and increased risk of an early relapse after ADT (HR=1.47, P=0.024). The concordance (c) index analysis showed that the definition of profiles that contains information regarding tumor characteristics associated with genetic information present an increased capacity to predict the risk for CR development (c-index model 1: 0.683 vs model 2: 0.736 vs model 3: 0.746 vs model 4: 0.759). The TGFBR2-875G>A contribution to an early relapse in ADT patients, due to changes in mRNA expression, supports the involvement of TGFβ1 pathway in CRPC. Furthermore, according to our results, we hypothesize the potential benefits of the association of genetic information in predictive models of CR development.

Distinct roles of Kaposi's sarcoma-associated herpesvirus-encoded viral interferon regulatory factors in inflammatory response and cancer

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent associated with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). Similar to other herpesviruses, KSHV has two life cycles, latency and lytic replication. In latency, the KSHV genome persists as a circular episome in the nucleus of the host cell and only a few viral genes are expressed. In this review, we focus on oncogenic, antiapoptotic, and immunomodulating properties of KSHV-encoded homologues of cellular interferon regulatory factors (IRFs)--viral IRF1 (vIRF1) to vIRF4--and their possible role in the KSHV-mediated antiviral response, apoptosis, and oncogenicity.

Transforming growth factor beta receptor 2 (TGFBR2) changes sialylation in the microsatellite unstable (MSI) Colorectal cancer cell line HCT116

Aberrant glycosylation is a common feature of many malignancies including colorectal cancers (CRCs). About 15% of CRC show the microsatellite instability (MSI) phenotype that is associated with a high frequency of biallelic frameshift mutations in the A10 coding mononucleotide microsatellite of the transforming growth factor beta receptor 2 (TGFBR2) gene. If and how impaired TGFBR2 signaling in MSI CRC cells affects cell surface glycan pattern is largely unexplored. Here, we used the TGFBR2-deficient MSI colon carcinoma cell line HCT116 as a model system. Stable clones conferring doxycycline (dox)-inducible expression of a single copy wildtype TGFBR2 transgene were generated by recombinase-mediated cassette exchange (RMCE). In two independent clones, dox-inducible expression of wildtype TGFBR2 protein and reconstitution of its signaling function was shown. Metabolic labeling experiments using the tritiated sialic acid precursor N-acetyl-D-mannosamine (ManNAc) revealed a significant decline (∼30%) of its incorporation into newly synthesized sialoglycoproteins in a TGFBR2-dependent manner. In particular, we detected a significant decrease of sialylated ß1-integrin upon reconstituted TGFBR2 signaling which did not influence ß1-integrin protein turnover. Notably, TGFBR2 reconstitution did not affect the transcript levels of any of the known human sialyltransferases when examined by real-time RT- PCR analysis. These results suggest that reconstituted TGFBR2 signaling in an isogenic MSI cell line model system can modulate sialylation of cell surface proteins like ß1-integrin. Moreover, our model system will be suitable to uncover the underlying molecular mechanisms of altered MSI tumor glycobiology.

The Dual Role of TGFβ in Human Cancer: From Tumor Suppression to Cancer Metastasis

The transforming growth factor-beta (TGFβ) superfamily encompasses widespread and evolutionarily conserved polypeptide growth factors that regulate and orchestrate growth and differentiation in all cell types and tissues. While they regulate asymmetric cell division and cell fate determination during early development and embryogenesis, TGFβ family members play a major regulatory role in hormonal and immune responses, cell growth, cell death and cell immortalization, bone formation, tissue remodeling and repair, and erythropoiesis throughout adult life. The biological and physiological functions of TGFβ, the founding member of this family, and its receptors are of central importance to human diseases, particularly cancer. By regulating cell growth, death, and immortalization, TGFβ signaling pathways exert tumor suppressor effects in normal cells and early carcinomas. Thus, it is not surprising that a high number of human tumors arise due to mutations or deletions in the genes coding for the various TGFβ signaling components. As tumors develop and progress, these protective and cytostatic effects of TGFβ are often lost. TGFβ signaling then switches to promote cancer progression, invasion, and tumor metastasis. The molecular mechanisms underlying this dual role of TGFβ in human cancer will be discussed in depth in this paper, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the prometastatic arm of the TGFβ signaling pathway without affecting its tumor suppressive effects.

TGF-β - an excellent servant but a bad master

The transforming growth factor (TGF-β) family of growth factors controls an immense number of cellular responses and figures prominently in development and homeostasis of most human tissues. Work over the past decades has revealed significant insight into the TGF-β signal transduction network, such as activation of serine/threonine receptors through ligand binding, activation of SMAD proteins through phosphorylation, regulation of target genes expression in association with DNA-binding partners and regulation of SMAD activity and degradation. Disruption of the TGF-β pathway has been implicated in many human diseases, including solid and hematopoietic tumors. As a potent inhibitor of cell proliferation, TGF-β acts as a tumor suppressor; however in tumor cells, TGF-β looses anti-proliferative response and become an oncogenic factor. This article reviews current understanding of TGF-β signaling and different mechanisms that lead to its impairment in various solid tumors and hematological malignancies.

The prognostic significance of growth factors and growth factor receptors in gastric adenocarcinoma

We evaluated growth factors/receptors expression in gastric adenocarcinoma. Immunohistochemistry was used to evaluate epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), VEGF-D, VEGF receptor (VEGFR)-2, VEGFR-3, transforming growth factor (TGF)-α, TGF-β1, and TGF-β-RII in tissue microarrays of adenocarcinoma, dysplasia, metaplasia, and gastritis. In adenocarcinoma, the expression rates of EGFR, VEGF, VEGF-D, VEGFR-2, VEGFR-3, TGF-α, TGF-β1, and TGF-β-RII were 2.0%, 0%, 10.7%, 4.4%, 11.2%, 26.3%, 9.4%, and 19.5%, respectively. VEGF-D, TGF-α, TGF-β1, and TGF-β-RII expression rate were higher in adenocarcinoma than in other groups. TGF-β-RII expression was correlated with VEGFR-3, VEGF-D, and TGF-α expression in adenocarcinomas. Tumor location, histologic type, stage, lymphatic invasion, perineural invasion, angioinvasion, VEGF-D, and VEGFR-2 expressions were associated with patient survival in a log rank test and advanced stage and positive expression of VEGF-D were poor prognostic factors using Cox analysis. VEGF-D expression may be of prognostic value in gastric adenocarcinoma, whereas EGFR and TGF family expression may only have a minor influence.

Molecular pathways: targeting the TGF-β pathway for cancer therapy

TGF-β is a ubiquitous cytokine that plays an active role in many cellular processes. Nearly every cell type has the ability to secrete TGF-β, as well as the ability to respond to TGF-β via the presence of TGF-β receptors on the cell surface. Consequently, gain or loss of function of the TGF-β pathway and its components are known to lead to a variety of diseases, including cancer. In epithelial cells, TGF-β functions as a tumor suppressor, where it inhibits proliferation, induces apoptosis, and mediates differentiation. Conversely, in other contexts, TGF-β promotes tumor progression through increasing tumor cell invasion and metastasis. Thus, TGF-β can have opposing roles, likely dependent, in part, on whether the cancer is early or late stage. The effects of TGF-β on tumor suppression and promotion are not limited to the tumor cell itself; rather, these effects can also be mediated through the stroma and the immune system. The dichotomous role of TGF-β in cancer highlights our need to understand the contextual effects of this cytokine to better guide patient selection for the use of anti-TGF-β therapies currently in clinical trials.

Transcription factor Dlx2 protects from TGFβ-induced cell-cycle arrest and apoptosis

Acquiring resistance against transforming growth factor β (TGFβ)-induced growth inhibition at early stages of carcinogenesis and shifting to TGFβ's tumour-promoting functions at later stages is a pre-requisite for malignant tumour progression and metastasis. We have identified the transcription factor distal-less homeobox 2 (Dlx2) to exert critical functions during this switch. Dlx2 counteracts TGFβ-induced cell-cycle arrest and apoptosis in mammary epithelial cells by at least two molecular mechanisms: Dlx2 acts as a direct transcriptional repressor of TGFβ receptor II (TGFβRII) gene expression and reduces canonical, Smad-dependent TGFβ signalling and expression of the cell-cycle inhibitor p21(CIP1) and increases expression of the mitogenic transcription factor c-Myc. On the other hand, Dlx2 directly induces the expression of the epidermal growth factor (EGF) family member betacellulin, which promotes cell survival by stimulating EGF receptor signalling. Finally, Dlx2 expression supports experimental tumour growth and metastasis of B16 melanoma cells and correlates with tumour malignancy in a variety of human cancer types. These results establish Dlx2 as one critical player in shifting TGFβ from its tumour suppressive to its tumour-promoting functions.

TGF-beta biology in mammary development and breast cancer

Transforming growth factor-β1 (TGF-β) was first implicated in mammary epithelial development by Daniel and Silberstein in 1987 and in breast cancer cells and hormone resistance by Lippman and colleagues in 1988. TGF-β is critically important for mammary morphogenesis and secretory function through specific regulation of epithelial proliferation, apoptosis, and extracellular matrix. Differential TGF-β effects on distinct cell types are compounded by regulation at multiple levels and the influence of context on cellular responses. Studies using controlled expression and conditional-deletion mouse models underscore the complexity of TGF-β biology across the cycle of mammary development and differentiation. Early loss of TGF-β growth regulation in breast cancer evolves into fundamental deregulation that mediates cell interactions and phenotypes driving invasive disease. Two outstanding issues are to understand the mechanisms of biological control in situ and the circumstances by which TGF-β regulation is subverted in neoplastic progression.

The role of transforming growth factor-beta in suppression of hepatic metastasis from colon cancer

BACKGROUND

The role of transforming growth factor-beta (TGF-beta) in the development of hepatic metastasis from colon cancer is not clearly elucidated. The aim of this study was to determine the role of TGF-beta in the development of such metastasis.

METHODS

Two human colon cancer cell lines were utilized: FET-alpha cells (intact TGF-beta inhibitory response), and CBS cells (defects in TGF-beta inhibitory response caused by a deficiency in type II receptor activity). The ability of these cell lines to metastasize was analysed in an orthotopic colon cancer mouse model.

RESULTS

FET-alpha cells did not metastasize to the liver, but showed lung metastasis in 10% of the animals, whereas CBS cells gave rise to metastasis in 65%. Following the elimination of TGF-beta activity by transfection and overexpression of dominant negative type II receptor, FET-alpha cells demonstrated liver and lung metastasis in 70% of the animals. Similarly, after the restoration of type II receptor activity by ectopic expression, CBS cells formed metastasis in fewer (10%) animals.

CONCLUSIONS

The results of our study demonstrate for the first time that TGF-beta displays selective metastasis suppressor activity. These abnormal pathways can serve as selective targets for future development of targeted therapies.

TGF-beta signaling and the role of inhibitory Smads in non-small cell lung cancer

The signaling pathway mediated by transforming growth factor-beta (TGF-beta) participates in various biologic processes, including cell growth, differentiation, angiogenesis, apoptosis, and extracellular matrix remodeling. In the context of cancer, TGF-beta signaling can inhibit tumor growth in early-stage tumors. However, in late-stage tumors, the very same pathway promotes tumor invasiveness and metastasis. This paradoxical effect is mediated through similar to mothers against decapentaplegic or Smad protein dependent and independent mechanisms and provides an opportunity for targeted cancer therapy. This review summarizes the molecular process of TGF-beta signaling and the changes in inhibitory Smads that contribute to lung cancer progression. We also present current approaches for rational therapies that target the TGF-beta signaling pathway in cancer.

Tgf-beta signaling pathway in lung adenocarcinoma invasion

The histologic distinction between bronchioloalveolar carcinoma and other adenocarcinomas is tissue invasion. The clinical importance of lung adenocarcinoma invasion is supported by several recent studies indicating that the risk of death in nonmucinous bronchioloalveolar carcinoma is significantly lower than that of pure invasive tumors and in tumors with greater than 0.5 cm of fibrosis or linear invasion. Using microarray gene expression profiling of human tumors, dysregulation of transforming growth factor-beta signaling was identified as an important mediator of tumor invasion. Subsequent studies showed that the CC chemokine regulated on activation, normal T cell expressed, and presumably secreted was up-regulated in invasive tumors and was required for invasion in cells with repressed levels of the transforming growth factor-beta type II receptor. Taken together, these studies illustrate how information gained from global expression profiling of tumors can be used to identify key pathways and genes mediating tumor growth, invasion, and metastasis.

Transforming growth factor beta (TGF-beta) and inflammation in cancer

The transforming growth factor beta (TGF-beta) has been studied with regard to the regulation of cell behavior for over three decades. A large body of research has been devoted to the regulation of epithelial cell and derivative carcinoma cell populations in vitro and in vivo. TGF-beta has been shown to inhibit epithelial cell cycle progression and promote apoptosis that together significantly contribute to the tumor suppressive role for TGF-beta during carcinoma initiation and progression. TGF-beta is also able to promote an epithelial to mesenchymal transition that has been associated with increased tumor cell motility, invasion and metastasis. However, it has now been shown that loss of carcinoma cell responsiveness to TGF-beta stimulation can also promote metastasis. Interestingly, enhanced metastasis in the absence of a carcinoma cell response to TGF-beta stimulation has been shown to involve increased chemokine production resulting in recruitment of pro-metastatic myeloid derived suppressor cell (MDSC) populations to the tumor microenvironment at the leading invasive edge. When present, MDSCs enhance angiogenesis, promote immune tolerance and provide matrix degrading enzymes that promote tumor progression and metastasis. Further, the recruitment of MDSC populations in this context likely enhances the classic role for TGF-beta in immune suppression since the MDSCs are an abundant source of TGF-beta production. Importantly, it is now clear that carcinoma-immune cell cross-talk initiated by TGF-beta signaling within the carcinoma cell is a significant determinant worth consideration when designing therapeutic strategies to manage tumor progression and metastasis.

Molecular signatures reveal circadian clocks may orchestrate the homeorhetic response to lactation

Genes associated with lactation evolved more slowly than other genes in the mammalian genome. Higher conservation of milk and mammary genes suggest that species variation in milk composition is due in part to the environment and that we must look deeper into the genome for regulation of lactation. At the onset of lactation, metabolic changes are coordinated among multiple tissues through the endocrine system to accommodate the increased demand for nutrients and energy while allowing the animal to remain in homeostasis. This process is known as homeorhesis. Homeorhetic adaptation to lactation has been extensively described; however how these adaptations are orchestrated among multiple tissues remains elusive. To develop a clearer picture of how gene expression is coordinated across multiple tissues during the pregnancy to lactation transition, total RNA was isolated from mammary, liver and adipose tissues collected from rat dams (n = 5) on day 20 of pregnancy and day 1 of lactation, and gene expression was measured using Affymetrix GeneChips. Two types of gene expression analysis were performed. Genes that were differentially expressed between days within a tissue were identified with linear regression, and univariate regression was used to identify genes commonly up-regulated and down-regulated across all tissues. Gene set enrichment analysis showed genes commonly up regulated among the three tissues enriched gene ontologies primary metabolic processes, macromolecular complex assembly and negative regulation of apoptosis ontologies. Genes enriched in transcription regulator activity showed the common up regulation of 2 core molecular clock genes, ARNTL and CLOCK. Commonly down regulated genes enriched Rhythmic process and included: NR1D1, DBP, BHLHB2, OPN4, and HTR7, which regulate intracellular circadian rhythms. Changes in mammary, liver and adipose transcriptomes at the onset of lactation illustrate the complexity of homeorhetic adaptations and suggest that these changes are coordinated through molecular clocks.

Dysfunctional transforming growth factor-beta receptor II accelerates prostate tumorigenesis in the TRAMP mouse model

The contribution of a dysfunctional transforming growth factor-beta type II receptor (TGF beta RII) to prostate cancer initiation and progression was investigated in an in vivo mouse model. Transgenic mice harboring the dominant-negative mutant TGF-beta type II receptor (DNTGF beta RII) in mouse epithelial cell were crossed with the TRAMP prostate cancer transgenic mouse to characterize the in vivo consequences of inactivated TGF-beta signaling on prostate tumor initiation and progression. Histopathologic diagnosis of prostate specimens from the TRAMP+/DNTGF beta RII double transgenic mice revealed the appearance of early malignant changes and subsequently highly aggressive prostate tumors at a younger age, compared with littermates TRAMP+/Wt TGF beta RII mice. Immunohistochemical and Western blotting analysis revealed significantly increased proliferative and apoptotic activities, as well as vascularity and macrophage infiltration that correlated with an elevated vascular endothelial growth factor and MCP-1 protein levels in prostates from TRAMP+/DNTGF beta RII+ mice. An epithelial-mesenchymal transition (EMT) effect was also detected in prostates of TRAMP+/DNTGF beta RII mice, as documented by the loss of epithelial markers (E-cadherin and beta-catenin) and up-regulation of mesenchymal markers (N-cadherin) and EMT-transcription factor Snail. A significant increase in the androgen receptor mRNA and protein levels was associated with the early onset of prostate tumorigenesis in TRAMP+/DNTGF beta RII mice. Our results indicate that in vivo disruption of TGF-beta signaling accelerates the pathologic malignant changes in the prostate by altering the kinetics of prostate growth and inducing EMT. The study also suggests that a dysfunctional TGF beta RII augments androgen receptor expression and promotes inflammation in early stage tumor growth, thus conferring a significant contribution by TGF-beta to prostate cancer progression.

TGF-beta receptor levels regulate the specificity of signaling pathway activation and biological effects of TGF-beta

TGF-beta is a pluripotent cytokine that mediates its effects through a receptor composed of TGF-beta receptor type II (TGFBR2) and type I (TGFBR1). The TGF-beta receptor can regulate Smad and nonSmad signaling pathways, which then ultimately dictate TGF-beta's biological effects. We postulated that control of the level of TGFBR2 is a mechanism for regulating the specificity of TGF-beta signaling pathway activation and TGF-beta's biological effects. We used a precisely regulatable TGFBR2 expression system to assess the effects of TGFBR2 expression levels on signaling and TGF-beta mediated apoptosis. We found Smad signaling and MAPK-ERK signaling activation levels correlate directly with TGFBR2 expression levels. Furthermore, p21 levels and TGF-beta induced apoptosis appear to depend on relatively high TGFBR2 expression and on the activation of the MAPK-ERK and Smad pathways. Thus, control of TGFBR2 expression and the differential activation of TGF-beta signaling pathways appears to be a mechanism for regulating the specificity of the biological effects of TGF-beta.

Expression and mutational analysis of TGF-beta/Smads signaling in human cervical cancers

OBJECTIVE

To define the molecular basis of TGF-beta1 function in cervical carcinogenesis, we explored the expression and mutational status of TGF-beta1, TGF-beta1 receptors, and Smads, the regulators of the TGF-beta1 signaling pathway, in human cervical cancers.

METHODS

Expression of TGF-beta1, TGF-beta1 receptors, and Smads transcripts were determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR), and sequence alteration was analyzed using RT-PCR-single-strand conformation polymorphism (SSCP) analysis. Genomic levels of TGF-beta1, TGF-beta1 receptors and Smads was also measured by quantitative genomic PCR.

RESULTS

Abnormal overexpression of TGF-beta1 and abnormal reduction of type II TGF-beta1 receptor were identified in 36% (18 of 50) and 20% (10 of 50) of cervical cancer tissues, respectively. 22% (11 of 50) in Smad2 and 14% (7 of 50) in Smad4 revealed tumor specific mRNA reduction less than a half of normal means. In addition, no evidence for sequence alterations of the gene was found by RT-PCR-SSCP analysis.

CONCLUSION

Our study demonstrates that disruption of TGF-beta/Smad signaling pathway exist in human cervical cancer, suggesting that abnormal expressions of the member of TGF-beta/Smad signaling pathway might contribute to the malignant progression of human cervical tumors via suppressing the tumor suppression function of TGF-beta1 1's tumor suppression function.

Effects of omega-3 fatty acids on components of the transforming growth factor beta-1 pathway: implication for dietary modification and prevention in ovarian cancer

OBJECTIVE

We previously demonstrated that omega-3 fatty acids (OM-3FAs) have definitive inhibitory effects on ovarian cancer cell lines. We sought to determine whether the inhibitory effects of OM-3FAs were mediated by the transforming growth factor (TGF)-beta1 signaling pathway.

STUDY DESIGN

Ovarian cancer cell lines were grown at 37 degrees C in 5% CO(2) and treated with OM-3FAs, omega-6 fatty acids, and control at different concentrations for 24-72 hours. Enzyme-linked immunosorbent assay (ELISA) assay and Western blot analysis were used to measure TGF-beta1, phosphorylated mothers against decapentaplegic (Smad)-3 and p21 protein levels.

RESULTS

An ELISA assay demonstrated that OM-3FA treatment increased TGF-beta1 in all 3 Hey cell lines (P < .05). In both SKOV-3 and OVCAR-3 cells, TGF-beta1 levels were not significantly increased. Western blots confirmed increases in TGF-beta1, Smad-3 and p21 protein levels in Hey and HeyC2 but not SKOV-3 and OVCAR-3 cells.

CONCLUSION

OM-3FAs increased the level of TGF-beta1, Smad-3, and p21 protein in ovarian cancer cells known to be more sensitive to their inhibitory effect.

Epigenetic Targeting of Transforming Growth Factor β Receptor II and Implications for Cancer Therapy

The transforming growth factor (TGF) β signaling pathway is involved in many cellular processes including proliferation, differentiation, adhesion, motility and apoptosis. The loss of TGFβ signaling occurs early in carcinogenesis and its loss contributes to tumor progression. The loss of TGFβ responsiveness frequently occurs at the level of the TGFβ type II receptor (TGFβRII) which has been identified as a tumor suppressor gene (TSG). In keeping with its TSG role, the loss of TGFβRII expression is frequently associated with high tumor grade and poor patient prognosis. Reintroduction of TGFβRII into tumor cell lines results in growth suppression. Mutational loss of TGFβRII has been characterized, particularly in a subset of colon cancers with DNA repair enzyme defects. However, the most frequent cause of TGFβRII silencing is through epigenetic mechanisms. Therefore, re-expression of TGFβRII by use of epigenetic therapies represents a potential therapeutic approach to utilizing the growth suppressive effects of the TGFβ signaling pathway. However, the restoration of TGFβ signaling in cancer treatment is challenging because in late stage disease, TGFβ is a pro-metastatic factor. This effect is associated with increased expression of the TGFβ ligand. In this Review, we discuss the mechanisms associated with TGFβRII silencing in cancer and the potential usefulness of histone deacetylase (HDAC) inhibitors in reversing this effect. The use of HDAC inhibitors may provide a unique opportunity to restore TGFβRII expression in tumors as their pleiotropic effects antagonize many of the cellular processes, which mediate the pro-metastatic effects associated with increased TGFβ expression.

Cross-talk between IFN-alpha and TGF-beta1 signaling pathways in preneoplastic rat liver

Interferon-gamma/transforming growth factor-beta (IFN-gamma/TGF-beta) pathways have opposite effects on diverse cellular functions. However, little is known about interactions between IFN-alpha/TGF-beta. In previous studies, we showed that IFN-alpha2b increases TGF-beta(1) production and secretion in hepatocytes from preneoplastic rat livers. Here, the interaction between IFN-alpha/TGF-beta(1) pathways was explored. We observed a positive cross-talk between IFN-alpha and TGF-beta(1) signaling, with activation of both pathways. p300 protein levels in hepatocytes from preneoplastic livers were enough to interact with both activated Stat1 and Smad2/3. Besides, Smad7 was not directly related with TGF-beta(1) and IFN-alpha signals. Interestingly, we reported the novel finding that the autocrine TGF-beta(1) up-regulates TGF-betaRII at protein and mRNA levels. In conclusion, the intracellular signals triggered by IFN-alpha2b and by autocrine TGF-beta(1) are integrated at the nuclear level, where activated Stat1 and Smad2/3 are capable of interact with p300, present in no restrictive cellular amounts.