Another twist in the transforming growth factor beta-induced cell-cycle arrest chronicle

Discovering biomarkers for hormone-dependent tumors: in silico study on signaling pathways implicated in cell cycle and cytoskeleton regulation

Malignancies dependent on hormone homeostasis include breast, ovary, cervical, prostate, testis and uterine tumors. Hormones are involved in signal transduction which orchestrate processes, such as apoptosis, proliferation, cell cycle or cytoskeleton organization. Currently, there is a need for novel biomarkers which would help to diagnose cancers efficiently. In this study, the genes implicated in signaling that is important in hormone-sensitive carcinogenesis were investigated regarding their prognostic significance. Data of seven cancer cohorts were collected from FireBrowse. 54 gene sets implicated in specific pathways were browsed through MSig database. Profiling was assessed via Monocle3, while gene ontology through PANTHER. For confirmation, correlation analysis was performed using WGCNA. Protein-protein networks were visualized via Cytoscape and impact of genes on survival, as well as cell cycle or cytoskeleton-related prognostic signatures, was tested. Several differences in expression profile were identified, some of them allowed to distinguish histology. Functional annotation revealed that various regulation of cell cycle, adhesion, migration, apoptosis and angiogenesis underlie these differences. Clinical traits, such as histological type or cancer staging, were found during evaluation of module-trait relationships. Of modules, the TopHubs (COL6A3, TNR, GTF2A1, NKX3-1) interacted directly with, e.g., PDGFB, ITGA10, SP1 or AKT3. Among TopHubs and interacting proteins, many showed an impact on hazard ratio and affected the cell cycle or cytoskeleton-related prognostic signatures, e.g., COL1A1 or PDGFB. In conclusion, this study laid the foundation for further hormone-sensitive carcinogenesis research through identification of genes which prove that crosstalk between cell cycle and cytoskeleton exists, opening avenues for future therapeutic strategies.

Regulation of p27 and Cdk2 Expression in Different Adipose Tissue Depots in Aging and Obesity

Aging usually comes associated with increased visceral fat accumulation, reaching even an obesity state, and favoring its associated comorbidities. One of the processes involved in aging is cellular senescence, which is highly dependent on the activity of the regulators of the cell cycle. The aim of this study was to analyze the changes in the expression of p27 and cdk2 in different adipose tissue depots during aging, as well as their regulation by obesity in mice. Changes in the expression of p27 and CDK2 in visceral and subcutaneous white adipose tissue (WAT) biopsies were also analyzed in a human cohort of obesity and type 2 diabetes. p27, but not cdk2, exhibits a lower expression in subcutaneous than in visceral WAT in mice and humans. p27 is drastically downregulated by aging in subcutaneous WAT (scWAT), but not in gonadal WAT, of female mice. Obesity upregulates p27 and cdk2 expression in scWAT, but not in other fat depots of aged mice. In humans, a significant upregulation of p27 was observed in visceral WAT of subjects with obesity. Taken together, these results show a differential adipose depot-dependent regulation of p27 and cdk2 in aging and obesity, suggesting that p27 and cdk2 could contribute to the adipose-tissue depot’s metabolic differences. Further studies are necessary to fully corroborate this hypothesis.

EMP2 induces cytostasis and apoptosis via the TGFβ/SMAD/SP1 axis and recruitment of P2RX7 in urinary bladder urothelial carcinoma

PURPOSE

Urinary bladder urothelial carcinoma (UBUC) is a common malignant disease, and its high recurrence rates impose a heavy clinical burden. The objective of this study was to identify signaling pathways downstream of epithelial membrane protein 2 (EMP2), which induces cytostasis and apoptosis in UBUC.

METHODS

A series of in vitro and in vivo assays using different UBUC-derived cell lines and mouse xenograft models were performed, respectively. In addition, primary UBUC specimens were evaluated by immunohistochemistry.

RESULTS

Exogenous expression of EMP2 in J82 UBUC cells significantly decreased DNA replication and altered the expression levels of several TGFβ signaling-related proteins. EMP2 knockdown in BFTC905 UBUC cells resulted in opposite effects. EMP2-dysregulated cell cycle progression was found to be mediated by the TGFβ/TGFBR1/SP1 family member SMAD. EMP2 or purinergic receptor P2X7 (P2RX7) gene expression upregulation induced apoptosis via both intrinsic and extrinsic pathways. In 242 UBUC patient samples, P2RX7 protein levels were found to be significantly and positively correlated with EMP2 protein levels. Low P2RX7 levels conferred poor disease-specific and metastasis-free survival rates, and significantly decreased apoptotic cell rates. EMP2 was found to physically interact with P2RX7. In the presence of a P2RX7 agonist, BzATP, overexpression of both EMP2 and P2RX7 significantly increased apoptotic cell rates compared to overexpression of EMP2 or P2RX7 alone.

CONCLUSIONS

EMP2 induces cytostasis via the TGFβ/SMAD/SP1 axis and recruits P2RX7 to enhance apoptosis in UBUC. Our data provide new insights that may be employed for the design of UBUC targeting therapies.

TGFB3 downregulation causing chordomagenesis and its tumor suppression role maintained by Smad7

Chordoma is a rare bone tumor arising from notochordal remnants, but the underlying mechanism remains elusive. By integrated mRNA and microRNA analyses, we found significant downregulation of TGFB3 along with upregulation of its inhibitor, miR-29 family in chordoma comparing with notochord. Somatic copy number gains of miR-29 loci in chordoma highlighted a mechanism of inactivation of TGFB3 signaling in tumor formation. In zebrafish, knockout and knockdown homologous tgfb3 resulted in a chordoma-like neoplasm. On the other hand, Smad7 negative feedback regulation of transforming growth factor-β (TGF-β) signaling is retentive in chordoma cell UM-Chor1 despite its disruption in most cancer cells (e.g. A549). Therefore, contrary to other cancers, exogenous TGF-β activated Smad7 by downregulating miR-182 and inhibited cell migration and invasion in UM-Chor1. Meanwhile, TGF-β decreased chordoma characteristic protein Brachyury. Altogether, downregulation of TGFB3 causes chordomagenesis, showing a feasible target for therapies. The retention of Smad7 negative regulation may maintain the suppressor role of TGF-β in chordoma.

Computational modeling of transforming growth factor β and activin a receptor complex formation in the context of promiscuous signaling regulation

The Transforming growth factor-beta (TGFβ) superfamily is a group of multipotent growth factors that control proliferation, quiescence and differentiation. Aberrant signal transduction and downstream target activation contribute to tumorigenesis and targeted therapy has therefore been considered a promising avenue. Using various modeling pipelines, we analyzed the structure-function relationship between ligand and receptor molecules of the TGFβ family. We further simulated the molecular docking of Galunisertib, a small molecule inhibitor targeting TGFβ signaling in cancer, which is currently undergoing FDA-approved clinical trials. We found that proprotein dimers of Activin isoforms differ at intrachain disulfide bonds, which support prior evidence of varying pro-domain stability and isoform preference. Further, mature proteins possess flexibility around conserved cystine knots to functionally interact with receptors or regulatory molecules in similar but distinct ways to TGFβ. We show that all Activin isoforms are capable of assuming a closed- or open-dimer state, revealing structural promiscuity of their open forms for receptor binding. We propose the first structural landscape for Activin receptor complexes containing a type I receptor (ACVR1B), which shares a pre-helix extension with TGFβ type I receptor (TGFβR1). Here, we artificially demonstrate that Activin can bind TGFβR1 in a TGFβ-like manner and that TGFβ1 can form signaling complexes with ACVR1B. Interestingly, Galunisertib was found to form stable inhibitory structures within the homologous kinase domains of both TGFβR1 and ACVR1B, thus halting receptor-promiscuous signaling. Overall, these observations highlight the challenges of specific TGFβ cascade targeting in the context of cancer therapies.Communicated by Ramaswamy H. Sarma.

Long-Term In Vitro Expansion of Epithelial Stem Cells Enabled by Pharmacological Inhibition of PAK1-ROCK-Myosin II and TGF-β Signaling

Despite substantial self-renewal capability in vivo, epithelial stem and progenitor cells located in various tissues expand for a few passages in vitro in feeder-free condition before they succumb to growth arrest. Here, we describe the EpiX method, which utilizes small molecules that inhibit PAK1-ROCK-Myosin II and TGF-β signaling to achieve over one trillion-fold expansion of human epithelial stem and progenitor cells from skin, airway, mammary, and prostate glands in the absence of feeder cells. Transcriptomic and epigenomic studies show that this condition helps epithelial cells to overcome stresses for continuous proliferation. EpiX-expanded basal epithelial cells differentiate into mature epithelial cells consistent with their tissue origins. Whole-genome sequencing reveals that the cells retain remarkable genome integrity after extensive in vitro expansion without acquiring tumorigenicity. EpiX technology provides a solution to exploit the potential of tissue-resident epithelial stem and progenitor cells for regenerative medicine.

Current status and future prospects of transforming growth factor-β as a potential prognostic and therapeutic target in the treatment of breast cancer

The transforming growth factor-β (TGF-β) signaling pathway is one of the important pathways involved in the cancer cell proliferation, invasion, migration, angiogenesis, apoptosis, as well as in metastasis by agitation or invasion of metastasis-related factors, including matrix metalloproteinase (MMP), epithelial-to-mesenchymal transition (EMT), tumor microenvironment (TME), cancer stem cells (CSCs), and cell adhesion molecules (CAMs). These data suggest its potential value as a therapeutic object in the treatment of malignancies including breast cancer. Several pharmacological approaches have been established to suppress TGF-β pathway; such as vaccines, small molecular inhibitors, antisense oligonucleotides, and monoclonal antibodies. Some of these are now approved by the US Food and Drug Administration for targeting the TGF-β signaling pathway. This study attempts to summarize the current data about the functions of TGF-β in cancer cells, and their probable application in the cancer therapy with a specific emphasis on recent preclinical and clinical research in the treatment of breast cancer and its prognostic value.

Epstein-Barr virus BARF1-induced NFκB/miR-146a/SMAD4 alterations in stomach cancer cells

Epstein-Barr virus (EBV)-encoded BamHI-A rightward frame 1 (BARF1) is a putative viral oncogene in EBV-infected stomach cancer. The aim of the present study was to investigate BARF1-induced cellular protein and microRNA alterations. In this study, BARF1-expressing stomach cancer cells showed a high rate of proliferation, high levels of NFκB, and miR-146a upregulation, which was reversed by NFκB knockdown. During BARF1-induced NFκB upregulation, hCSF1 receptor level was unchanged. Knockdown of BARF1 in the naturally EBV-infected YCCEL1 stomach cancer cells suppressed cell proliferation, and downregulated NFκB and miR-146a. SMAD4 was identified as a miR-146a target and was downregulated in BARF1-expressing cells, whereas SMAD4 expression was restored by anti-miR-146a. Knockdown of BARF1 in YCCEL1 cells upregulated SMAD4, and this effect was reversed by miR-146a overexpression. Transfection of BARF1-expressing cells with pCEP4-SMAD4 abolished the cell proliferating effect of BARF1. In stomach cancer tissues, miR-146a was expressed at higher levels, and more frequent NFκB nuclear positivity immunohistochemically, but not of SMAD4 nuclear loss was found in the EBV-positive group compared with the EBV-negative group. In conclusion, EBV-encoded BARF1 promotes cell proliferation in stomach cancer by upregulating NFκB and miR-146a and downregulating SMAD4, thereby contributing to EBV-induced stomach cancer progression.

The chemokine CXCL9 exacerbates chemotherapy-induced acute intestinal damage through inhibition of mucosal restitution

PURPOSE

Acute intestinal damage induced by chemotherapeutic agent is often a dose-limiting factor in clinical cancer therapy. The aim of this study was to investigate the effect of chemokine CXCL9 on the intestinal damage after chemotherapy and explore the therapeutic potential of anti-CXCL9 agents.

METHODS

In vitro cell proliferation assay was performed with a non-tumorigenic human epithelial cell line MCF10A. Multiple pathway analysis was carried out to explore the pathway that mediated the effect of CXCL9, and the corresponding downstream effector was identified with enzyme-linked immunosorbent assays. Chemotherapy-induced mouse model of intestinal mucositis was prepared by a single injection of the chemotherapeutic agent 5-fluorouracil (5-FU). In vivo expression of cxcl9 and its receptor cxcr3 in intestinal mucosa after chemotherapy was determined by quantitative real-time PCR. Therapeutic treatment with anti-CXCL9 antibodies was investigated to confirm the hypothesis that CXCL9 can contribute to the intestinal epithelium damage induced by chemotherapy.

RESULTS

CXCL9 inhibited the proliferation of MCF10A cells by activating phosphorylation of p70 ribosomal S6 kinase (p70S6K), which further promotes the secretion of transforming growth factor beta (TGF-β) as the downstream effector. A blockade of phospho-p70S6K with inhibitor abolished the effect of CXCL9 on MCF10A cells and reduced the secretion of TGF-β. The expression levels of cxcl9 and cxcr3 were significantly up-regulated in intestinal mucosa after 5-FU injection. Neutralizing elevated CXCL9 with anti-CXCR9 antibodies successfully enhanced reconstitution of intestinal mucosa and improved the survival rate of mice that received high-dose chemotherapy.

CONCLUSIONS

CXCL9 inhibits the proliferation of epithelial cells via phosphorylation of p70S6K, resulting in the excretion of TGF-β as downstream mediator. CXCL9/CXCR3 interaction can exacerbate chemotherapeutic agent-induced intestinal damage, and anti-CXCL9 agents are potential novel therapeutic candidates for promoting mucosal restitution.

Endocrine and developmental effects in Atlantic salmon (Salmo salar) exposed to perfluorooctane sulfonic or perfluorooctane carboxylic acids

In this study, we have investigated the effect of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) on endocrine signalling, growth and development in Atlantic salmon (Salmo salar) embryos and larvae. Expression of genes related to the hypothalamic-pituitary-thyroid (HPT) axis, growth-hormone/insulin-like growth factor (GH/IGF) axis and the steroid hormone axis were used as indicators of endocrine disruption. We also studied bone development in larvae, both by observing skeletal structure formation and by investigating expression of genes involved in ossification process. Atlantic salmon embryos, kept in plastic tanks at 5-7°C, were exposed to 100 μg/L PFOA or PFOS from egg stage for a period of 52 days, followed by one-week recovery period. Sampling was performed at day 21, 35, 49 and 56 representing age 549, 597, 679 and 721 dd (dd or day degrees = number of days × temperature in degree Celsius:°C). Note that day 56 or 721 dd is the end of the 1-week recovery period. Larvae were divided into designated head and body regions for the purpose of gene expression analysis, except for genes that regulate ossification that were analyzed in whole larvae. Expression of thyroid receptor α and β (TRα and TRβ), thyroid-stimulating hormone β (TSHβ), T(4) outer-ring deiodinase (T(4)ORD), growth hormone (GH), insulin-like growth factor-I and II (IGF-I and II), insulin-like growth factor I receptor (IGF-IR), and estrogen receptor α and β (ERα and ERβ) were investigated using quantitative PCR. Both PFOS and PFOA exposure produced non-significant alterations in larvae weight (except after the recovery period when a decrease was observed), while larvae length was unaffected. PFOS and PFOA exposure produced body- and head region-specific alterations in expression of all the investigated gene transcripts. Expression of IGF-I and IGF-IR paralleled that of GH, indicating that perturbation of GH expression is a possible end point for disruption of the GH-IGF axis. We did not observe developmental changes related to angiogenesis, ossification and chondrogenesis after exposure to PFOS and PFOA. Transcriptional abnormalities may serve as indicators of chronic exposure, although the concrete mechanisms causing the observed effects remain ambiguous. The implications of these findings for the complete lifecycle, including other developmental and/or reproductive damage, are areas of future study.

Developmental effects related to angiogenesis and osteogenic differentiation in Salmon larvae continuously exposed to dioxin-like 3,3',4,4'-tetrachlorobiphenyl (congener 77)

We have studied the effects of dioxin-like 3,3',4,4'-tetrachlorobiphenyl (PCB-77) on developmental effects related to angiogenesis and osteogenesis during early life-stages of salmon. Larvae were kept at 6°C and continuously exposed to waterborne PCB-77 (1 or 10 ng/L) initiated at the egg stage or 416-day degrees (dd) and throughout yolk-sac stage (716 dd) and for a total duration of 50 days (or 300 dd). Gene transcription analysis was performed on whole larvae total RNA at 548, 632, 674 and 716 dd using real-time PCR. Bone morphogenetic protein (bmp2 and bmp4), transforming growth factor β (TGF-β), estrogen receptors (ERα and ERβ), runx2, sox9 and collagen type 2 alpha 1 (col2a1) and vascular endothelial growth factor (VEGF) genes were studied. Effect on VEGF gene transcription was related to observation of heart rate, arrhythmia and anemia, demonstrating effects on vascular system development. Alizarine-red staining and quantification of ossified bone structures showed that PCB-77 produced concentration-dependent increases in the rate of osteogenic tissue formation. PCB-77 produced increases in col2a1 and runx2 transcription with subsequent induction of chondrogenesis and osteogenesis, respectively. The transcription of TGF-β gene was associated with ERβ transcription. Transcripts of AhR gene battery were differentially modulated by PCB-77 and these effects were dependent on concentration and larval age. Evidence of vascular system disruption by PCB-77 was observed as cardiac edema, anemia and arrhythmia in exposed individuals and as decreased level of VEGF gene transcription at early age. In general, our data indicate that PCB-77 produced developmental effects related to angiogenesis and osteogenic differentiation and disruption of vascular system development.

Transcriptome profile and cytogenetic analysis of immortalized neuronally restricted progenitor cells derived from the porcine olfactory bulb

Recently, we established and phenotypically characterized an immortalized porcine olfactory bulb neuroblast cell line, OBGF400 (1). To facilitate the future application of these cells in studies of neurological dysfunctions and neuronal pathogen interactions, a comprehensive knowledge of their genomic variability and overall gene expression capacity was pursued. Accordingly, the OBGF400 cells were subjected to karyotyping and more extensive transcriptome analyses. Cytogenetic characterization of these cells revealed a genetic mosaicism of neuronal hyperdiploidy. A direct comparison of the OBGF400 cell transcriptome pattern, generated by utilizing the Affymetrix GeneChip(R) Porcine Genome Array, to that of a non-neural, porcine epithelial cell line facilitated the identification of 831 probe sets preferentially hybridized by the neuroblast transcripts. Subsequent functional annotation of these OBGF400 RNAs using the Database for Annotation, Visualization and Integrated Discovery 2008 enabled their allocation to the corresponding gene ontology biological process term, thereby assisting the recognition of key elements involved in the regulation of neuronal signal transduction and neurogenesis.

Regulation of Epithelial-Mesenchymal Transition in Palatal Fusion

During palatal fusion, the midline epithelial seam between the palatal shelves degrades to achieve mesenchymal confluence. Morphological and molecular evidence support the theory that the epithelial-mesenchymal transition is one mechanism that regulates palatal fusion. It appears that transforming growth factor (TGF)-β signaling plays a role in palatal EMT. TGFβ3 is the main inducer in palatal fusion and activates both Smad-dependent and -independent signaling pathways, including the key EMT transcription factors, Lef1, Twist, and Snail1, in the MEE prior to the palatal EMT program. The roles and interactions among these transcription factors will be discussed.

Fitting a xenobiotic receptor into cell homeostasis: how the dioxin receptor interacts with TGFbeta signaling

As our knowledge on the mechanisms that control cell function increases, more complex signaling pathways and quite intricate cross-talks among regulatory proteins are discovered. Establishing accurate interactions between cellular networks is essential for a healthy cell and different alterations in signaling are known to underline human disease. Transforming growth factor beta (TGFbeta) is an extracellular cytokine that regulates such critical cellular responses as proliferation, apoptosis, differentiation, angiogenesis and migration, and it is assumed that the latency-associated protein LTBP-1 plays a relevant role in TGFbeta targeting and activation in the extracellular matrix (ECM). The dioxin receptor (AhR) is a unique intracellular protein long studied because of its critical role in xenobiotic-induced toxicity and carcinogenesis. Yet, a large set of studies performed in cellular systems and in vivo animal models have suggested important xenobiotic-independent functions for AhR in cell proliferation, differentiation and migration and in tissue homeostasis. Remarkably, AhR activity converges with TGFbeta-dependent signaling through LTBP-1 since cells lacking AhR expression have phenotypic alterations that can be explained, at least in part, by the coordinated regulation of both proteins. Here, we will discuss the existence of functional interactions between AhR and TGFbeta signaling. We will focus on regulatory and functional aspects by analyzing how AhR status determines TGFbeta activity and by proposing a mechanism through which LTBP-1, a novel AhR target gene, mediates such effects. We will integrate ECM proteases in the AhR-LTBP-1-TGFbeta axis and suggest a model that could help explain some in vivo phenotypes associated to AhR deficiency.

Increased longevity of hematopoiesis in continuous bone marrow cultures and adipocytogenesis in marrow stromal cells derived from Smad3(-/-) mice

OBJECTIVE

To determine the role of Smad3 in modulating hematopoiesis, continuous bone marrow cultures were established from Smad-/- mice, and the longevity of hematopoiesis and extent of adipogenesis in the supportive hematopoietic microenvironment were compared to those from cultures of control, Smad3+/+ or heterozygous Smad3+/- mice.

MATERIALS AND METHODS

Long-term bone marrow cultures (LTBMCs) were established from Smad3+/+, Smad3+/-, or Smad3-/- mice. On a weekly basis, the number of cobblestone islands, number of nonadherent cells, confluence of the adherent cells, or CFU-GEMM colonies was determined. Bone marrow stromal cell lines were established and cobblestone island production on these cell lines determined in the presence of nonadherent cells from week-42 Smad3-/- or week-4 C57BL/6J LTBMCs.

RESULTS

Initial proliferative capacity of the LTBMCs was similar in all groups through week 20, at which time there was an increase in cobblestone islands and production of nonadherent cells and CFU-GEMM colonies in the Smad3-/- group. By week 28, only the Smad3-/- LTBMCs had significantly maintained increased production of these parameters. Maintenance of cobblestone islands indicative of the most primitive hematopoietic progenitor cells persisted past 45 weeks in Smad3-/- cultures. The Smad3-/- stromal cell line also demonstrated increased support of cobblestone island production when incubated with nonadherent cells from week-42 Smad3-/- or week-4 C57BL/6J LTBMCs. Evaluation of adipocytogenesis in stromal cells showed significantly greater accumulation of adipocytes in lines from Smad3-/- than from Smad3+/+ mice.

CONCLUSIONS

These data provide evidence for a significant effect of deletion of the Smad3 signaling pathway in increased hematopoiesis in LTBMCs and support the negative regulatory influence of TGFbeta signaling on adipocytogenesis and long-term hematopoiesis in vitro.

Glypican-1 antisense transfection modulates TGF-β-dependent signaling in Colo-357 pancreatic cancer cells

The heparan sulfate proteoglycan glypican-1 is essential as a co-receptor for heparin binding growth factors, such as HB-EGF and FGF-2, in pancreatic cancer cells. In the present study, the role of glypican-1 in the regulation of TGF-beta signaling was investigated. Colo-357 pancreatic cancer cells were stably transfected with a full-length glypican-1 antisense construct. Cell growth was determined by MTT and soft agar assays. TGF-beta1 induced p21 expression and Smad2 phosphorylation were analyzed by immunoblotting. PAI-1 promoter activity was determined by luciferase assays. Down-regulation of glypican-1 expression by stable transfection of a full-length glypican-1 antisense construct resulted in decreased anchorage-dependent and -independent cell growth in Colo-357 pancreatic cancer cells and attenuated TGF-beta1 induced cell growth inhibition, Smad2 phosphorylation, and PAI-1 promoter activity. There was, however, no significant difference in TGF-beta1 induced p21 expression and Smad2 nuclear translocation. In conclusion, glypican-1 is required for efficient TGF-beta1 signaling in pancreatic cancer cells.