Transforming growth factor-beta, Smads, and cancer

Heavily Gd-Doped Non-Toxic Cerium Oxide Nanoparticles for MRI Labelling of Stem Cells

Recently, human mesenchymal stem cells (hMSc) have attracted a great deal of attention as potential therapeutic agents in the treatment of socially significant diseases. Despite substantial advances in stem-cell therapy, the biological mechanisms of hMSc action after transplantation remain unclear. The use of magnetic resonance imaging (MRI) as a non-invasive method for tracking stem cells in the body is very important for analysing their distribution in tissues and organs, as well as for ensuring control of their lifetime after injection. Herein, detailed experimental data are reported on the biocompatibility towards hMSc of heavily gadolinium-doped cerium oxide nanoparticles (Ce_0.8Gd_0.2O_2-x) synthesised using two synthetic protocols. The relaxivity of the nanoparticles was measured in a magnetic field range from 1 mT to 16.4 T. The relaxivity values (r₁ = 11 ± 1.2 mM^-1 s^-1 and r₁ = 7 ± 1.2 mM^-1 s^-1 in magnetic fields typical of 1.5 and 3 T MRI scanners, respectively) are considerably higher than those of the commercial Omniscan MRI contrast agent. The low toxicity of gadolinium-doped ceria nanoparticles to hMSc enables their use as an effective theranostic tool with improved MRI-contrasting properties.

Autophagy Regulation by Crosstalk between miRNAs and Ubiquitination System

MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules encoded by endogenous genes with ~22 nucleotides which are involved in the regulation of post-transcriptional gene expression. Ubiquitination and deubiquitination are common post-translational modifications in eukaryotic cells and important pathways in regulating protein degradation and signal transduction, in which E3 ubiquitin ligases and deubiquitinases (DUBs) play a decisive role. MiRNA and ubiquitination are involved in the regulation of most biological processes, including autophagy. Furthermore, in recent years, the direct interaction between miRNA and E3 ubiquitin ligases or deubiquitinases has attracted much attention, and the cross-talk between miRNA and ubiquitination system has been proved to play key regulatory roles in a variety of diseases. In this review, we summarized the advances in autophagy regulation by crosstalk between miRNA and E3 ubiquitin ligases or deubiquitinases.

Demethylzeylasteral (T-96) inhibits triple-negative breast cancer invasion by blocking the canonical and non-canonical TGF-β signaling pathways

Inflammation is one of the characteristic features during the development of human tumors. A pro-inflammatory cytokine that is known to promote inflammation during cancer development is the transforming growth factor-β (TGF-β). On the other hand, demethylzeylasteral (T-96) is a natural compound isolated from Tripterygium wilfordii Hook F, which has been reported to have various pharmacological properties including anti-inflammatory and immunosuppressive activities. We investigated the effects of T-96 on the highly metastatic breast cancer cell line, MDA-MB-231. Cell migration was assessed by scratch-wound migration assay, and the molecular mechanisms underlying the effects of T-96 were examined by qPCR and Western blot analyses. We also investigated the suppression effects of T-96 on the pulmonary metastasis in the 4T1 mouse model. T-96 inhibited TGF-β-induced migration and epithelial-mesenchymal transition both in vitro and in vivo. These results demonstrate that T-96 inhibited invasion of MDA-MB-231 and 4T1 cells via suppressing the canonical and non-canonical TGF-β signaling pathways.

Treatment of dextran sodium sulfate-induced experimental colitis by adoptive transfer of peritoneal cells

The adoptive transfer of the natural regulatory B cells and macrophages should be a useful treatment for inflammation and autoimmune disease. However, it is usually difficult to isolate these cells from the tissues and expand them. Here, we investigated the feasibility of adoptively transferring peritoneal cells (PCs) as a treatment for DSS-induced colitis. We found that peritoneal cavity can provide an easily accessible site for harvesting enough number of PCs, namely, two-dose PCs for the treatment from a mouse in one operation. Adoptive therapy of these cells from healthy mice or those with disease is effectively in reducing the disease activity score. The natural B cells and macrophages of the infused PCs can selectively migrate to lesion sites and regulate the expression of Stat3, NF−κB, Smad3 and Smad7. Additionally, PCs exert dual activity of IL-10 and TGF-β secreted spontaneously by both peritoneal B cells and macrophages, which in turn enhance the induction of regulatory B cells and Macrophages in microenvironment of inflammation. Moreover, PCs can re-establish immunological tolerance in the OVA-immunized mice. Thus, our findings provide a new strategy for colitis therapy and could be of importance in additional exploration of other inflammation and autoimmune diseases therapy.

Pin1 plays a critical role as a molecular switch in canonical BMP signaling

Pin1 is a peptidyl prolyl cis-trans isomerase that specifically binds to the phosphoserine-proline or phosphothreonine-proline motifs of numerous proteins. Previously, we reported that Pin1 deficiency resulted in defects in osteoblast differentiation during early bone development. In this study, we found that adult Pin1-deficient mice developed osteoporotic phenotypes compared to age-matched controls. Since BMP2 stored in the bone matrix plays a critical role in adult bone maintenance, we suspected that BMP R-Smads (Smad1 and Smad5) could be critical targets for Pin1 action. Pin1 specifically binds to the phosphorylated linker region of Smad1, which leads to structural modification and stabilization of the Smad1 protein. In this process, Pin1-mediated conformational modification of Smad1 directly suppresses the Smurf1 interaction with Smad1, thereby promoting sustained activation of the Smad1 molecule. Our data demonstrate that post-phosphorylational prolyl isomerization of Smad1 is a converging signal to stabilize the Smad1 molecule against the ubiquitination process mediated by Smurf1. Therefore, Pin1 is a critical molecular switch in the determination of Smad1 fate, opposing the death signal transmitted to the Smad1 linker region by phosphorylation cascades after its nuclear localization and transcriptional activation. Thus, Pin1 could be developed as a major therapeutic target in many skeletal diseases.

Role of the epithelial-mesenchymal transition and its effects on embryonic stem cells

The epithelial–mesenchymal transition (EMT) is important for embryonic development and the formation of various tissues or organs. However, EMT dysfunction in normal cells leads to diseases, such as cancer or fibrosis. During the EMT, epithelial cells are converted into more invasive and active mesenchymal cells. E-box-binding proteins, including Snail, ZEB and helix–loop–helix family members, serve as EMT-activating transcription factors. These transcription factors repress the expression of epithelial markers, for example, E-cadherin, rearrange the cytoskeleton and promote the expression of mesenchymal markers, such as vimentin, fibronectin and other EMT-activating transcription factors. Signaling pathways that induce EMT, including transforming growth factor-β, Wnt/glycogen synthase kinase-3β, Notch and receptor tyrosine kinase signaling pathways, interact with each other for the regulation of this process. Although the mechanism(s) underlying EMT in cancer or embryonic development have been identified, the mechanism(s) in embryonic stem cells (ESCs) remain unclear. In this review, we describe the underlying mechanisms of important EMT factors, indicating a precise role for EMT in ESCs, and characterize the relationship between EMT and ESCs.

Molecular aspects of development and regulation of endometriosis

Endometriosis is a common and painful condition affecting women of reproductive age. While the underlying pathophysiology is still largely unknown, much advancement has been made in understanding the progression of the disease. In recent years, a great deal of research has focused on non-invasive diagnostic tools, such as biomarkers, as well as identification of potential therapeutic targets. In this article, we will review the etiology and cellular mechanisms associated with endometriosis as well as the current diagnostic tools and therapies. We will then discuss the more recent genomic and proteomic studies and how these data may guide development of novel diagnostics and therapeutics. The current diagnostic tools are invasive and current therapies primarily treat the symptoms of endometriosis. Optimally, the advancement of "-omic" data will facilitate the development of non-invasive diagnostic biomarkers as well as therapeutics that target the pathophysiology of the disease and halt, or even reverse, progression. However, the amount of data generated by these types of studies is vast and bioinformatics analysis, such as we present here, will be critical to identification of appropriate targets for further study.

Integrative genomic analysis of temozolomide resistance in diffuse large B-cell lymphoma

PURPOSE

Despite advances, there is an urgent need for effective therapeutics for relapsed diffuse large B-cell lymphoma, particularly in elderly patients and primary central nervous system (CNS) lymphoma. Temozolomide (TMZ), an oral DNA-alkylating agent routinely used in the therapy of glioblastoma multiforme, is active in patients with primary CNS lymphoma but the response rates are low. The mechanisms contributing to TMZ resistance are unknown.

EXPERIMENTAL DESIGN

We undertook an unbiased and genome-wide approach to understand the genomic methylation and gene expression profiling differences associated with TMZ resistance in diffuse large B-cell lymphoma cell lines and identify mechanisms to overcome TMZ resistance.

RESULTS

TMZ was cytotoxic in a subset of diffuse large B-cell lymphoma cell lines, independent of MGMT promoter methylation or protein expression. Using Connectivity Map (CMAP), we identified several compounds capable of reversing the gene expression signature associated with TMZ resistance. The demethylating agent decitabine (DAC) is identified by CMAP as capable of reprogramming gene expression to overcome TMZ resistance. Treatment with DAC led to increased expression of SMAD1, a transcription factor involved in TGF-β/bone morphogenetic protein (BMP) signaling, previously shown to be epigenetically silenced in resistant diffuse large B-cell lymphoma. In vitro and in vivo treatment with a combination of DAC and TMZ had greater antilymphoma activity than either drug alone, with complete responses in TMZ-resistant diffuse large B-cell lymphoma murine xenograft models.

CONCLUSIONS

Integrative genome-wide methylation and gene expression analysis identified novel genes associated with TMZ resistance and demonstrate potent synergy between DAC and TMZ. The evidence from cell line and murine experiments supports prospective investigation of TMZ in combination with demethylating agents in diffuse large B-cell lymphoma.

The impact of TGF-β1 on the mRNA expression of TβR I, TβR II, Smad4 and the invasiveness of the JEG-3 placental choriocarcinoma cell line

Human choriocarcinoma is one of the most aggressive malignant tumors characterized by early hematogenous spread to lung and brain tissues, and may be a cause of death in patients. Choriocarcinoma may occur following pregnancy and during implantation; however, trophoblastic invasion in human pregnancy is tightly regulated. The transforming growth factor-beta 1 (TGF-β1) has been suggested to play a role in controlling this process. In this study, we investigated the impact of TGF-β1 on invasion, as well as its sites of action in the TGF-β1/Smad pathway using a JEG-3 choriocarcinoma cell line. Following the treatment of cells with different doses of TGF-β1, cell invasion was observed. We also detected the expression of TGF-β receptor type I (TβR I) and TGF-β receptor type II (TβR II), Smad4, matrix metalloprotease (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)-1 in JEG-3 cells. Our data demonstrated that TGF-β1 promoted the invasive capability of JEG-3 cells depending on the downregulation of TβR I, TβR II, Smad4 and the upregulation of MMP-9 and TIMP-1. These observations suggest that TGF-β1 may play a critical role in the initiation of the trophoblastic invasion process.

Resveratrol selectively induces DNA Damage, independent of Smad4 expression, in its efficacy against human head and neck squamous cell carcinoma

PURPOSE

Alterations in Smad4 signaling and its loss cause genomic instability and head and neck squamous cell carcinoma (HNSCC), suggesting that agents that target both Smad4-dependent and -independent pathways could control HNSCC.

EXPERIMENTAL DESIGN

Resveratrol efficacy was evaluated against the HNSCC cells FaDu, Cal27, Det562, and Cal27-Smad4 for viability, DNA damage, cell-cycle progression, and apoptosis, as well as γ-H2AX expression, and focus formation (γ-H2AX and Brca1). Resveratrol efficacy was also examined in nude mice for FaDu xenograft growth. Xenografts were analyzed for γ-H2AX and cleaved caspase-3.

RESULTS

Resveratrol (5-50 μmol/L) suppressed viability and induced DNA damage in FaDu and Cal27 cells but not in normal human epidermal keratinocytes and human foreskin fibroblasts, showing its selectivity toward HNSCC cells; however, Det562 cells were resistant to resveratrol even at 100 μmol/L. Cal27 cells stably transfected with Smad4 showed similar resveratrol effects as parental Cal27, indicating that a lack of resveratrol effect in Det562 cells was independent of Smad4 status in these cells. Furthermore, resveratrol caused S-phase arrest and apoptotic death of FaDu and Cal27 cells together with induction of Brca1 and γ-H2AX foci. Resveratrol (50 mg/kg body weight) treatment also inhibited FaDu tumor growth in nude mice, and γ-H2AX and cleaved caspase-3 were strongly increased in xenografts from resveratrol-treated mice compared with controls.

CONCLUSION

Our findings for the first time showed antiproliferative, DNA damaging, and apoptotic effects of resveratrol in HNSCC cells independent of Smad4 status, both in vitro and in vivo, suggesting that more studies are needed to establish its potential usefulness against HNSCC.

Transforming growth factor-β regulation of proteoglycan synthesis in vascular smooth muscle: contribution to lipid binding and accelerated atherosclerosis in diabetes

Atherosclerosis is accelerated in the setting of diabetes, but the factors driving this phenomenon remain elusive. Hyperglycemia leads to elevated levels of transforming growth factor (TGF)-β and TGF-β has been implicated as a factor in atherosclerosis. Given the established association between hyperglycemia and elevated TGF-β, it is plausible that elevated TGF-β levels in diabetes play a pathogenic role in the development of accelerated atherosclerosis. TGF-β is a potent regulator of extracellular matrix synthesis, including many actions on proteoglycan synthesis that lead to increased binding to low-density lipoprotein and therefore potentially increased lipid retention in the vessel wall and accelerated atherosclerosis. TGF-β signals through the canonical TGF-β receptor I-mediated phosphorylation of Smad transcription factors and TGF-β signaling is also known to involve, positively and negatively, interactions with the mitogen-activated protein kinase pathways. The focus of the present review is on the effects of TGF-β on proteoglycan synthesis in vascular smooth muscle and particularly the signaling pathways through which TGF-β exerts its effects, because those pathways may be therapeutic targets for the prevention of pathological modifications in the proteoglycan component of the vessel wall in the vascular diseases of diabetes.

Transforming growth factor-beta (TGF-beta) and brain tumours

Since its discovery in the late 1970s considerable research has linked transforming growth factor-beta (TGF-beta) to several human diseases such as fibrosis, auto-immunity and cancer. TGF-beta acts initially as a growth inhibitory factor in early stages of tumour development. In contrast, as tumours evolve, they develop mechanisms to evade the growth-regulatory effects of TGF-beta, resulting in greater tumour invasiveness, increased metastatic potential and inhibition of surrounding immune responses. However, although extensively studied, the molecular mechanisms that trigger tumour cells to "switch" from TGF-beta-inhibited to TGF-beta-promoted are still not fully understood. Contradictory studies that demonstrate opposite cellular effects mediated by TGF-beta are abundant throughout the literature. This review summarizes the current molecular mechanisms involved in the tumour suppressive and tumour progressive characteristics of TGF-beta in brain tumours. Potential therapeutic agents that target TGF-beta and related proteins being evaluated against brain tumours is also discussed.