TGF-β Family Signaling in Tumor Suppression and Cancer Progression

Pak1 maintains epidermal stem cells by regulating Langerhans cells and is required for skin carcinogenesis

Pak1 (serine/threonine p21-activated kinases) was previously reported to have oncogenic activity in several cancers. However, its roles in the cancer microenvironment are poorly understood. We demonstrated that Pak1 expression in Langerhans cells (LCs) is essential for the maintenance of epidermal stem cells and skin tumor development. We found that PAK1 is localized in LCs by immunohistochemistry. Furthermore, the number of LCs significantly decreased in MSM/Ms Pak1 homozygous knockout mice (MSM/Ms-Pak1^-/-). F₁ hybrid (FVB/N×MSM/Ms) Pak1 heterozygous knockout mice (F₁-Pak1^+/-) had increased numbers of Th17 cells in the skin. Therefore, Pak1 knockdown cells were prepared using LC-derived XS52 cells (XS52-Pak1KD) and co-cultured with keratinocyte-derived C5N cells. As a result, XS52-Pak1KD cell supernatants promoted C5N cell proliferation. We then carried out DMBA/TPA skin carcinogenesis experiments using F₁-Pak1^+/- mice. Of note, F₁-Pak1^+/- mice exhibited stronger resistance to skin tumors than control mice. F₁-Pak1^+/- mice had fewer epidermal stem cells in the skin bulge. Our study suggested that Pak1 regulates the epidermal stem cell number by changing the properties of LCs and functions in skin carcinogenesis. We clarified a novel role of Pak1 in regulating LCs as a potential therapeutic target in skin immune disease and carcinogenesis.

FOXF2 deficiency accelerates the visceral metastasis of basal-like breast cancer by unrestrictedly increasing TGF-β and miR-182-5p

The mesenchymal transcription factor forkhead box F2 (FOXF2) is a critical regulator of embryogenesis and tissue homeostasis. Our previous studies demonstrated that FOXF2 is ectopically expressed in basal-like breast cancer (BLBC) cells and that FOXF2 deficiency promotes the epithelial-mesenchymal transition and aggressiveness of BLBC cells. In this study, we found that FOXF2 controls transforming growth factor-beta (TGF-β)/SMAD signaling pathway activation through transrepression of TGF-β-coding genes in BLBC cells. FOXF2-deficient BLBC cells adopt a myofibroblast-/cancer-associated fibroblast (CAF)-like phenotype, and tend to metastasize to visceral organs by increasing autocrine TGF-β signaling and conferring aggressiveness to neighboring cells by increasing paracrine TGF-β signaling. In turn, TGF-β silences FOXF2 expression through upregulating miR-182-5p, a posttranscriptional regulator of FOXF2 and inducer of metastasis. In addition to mediating a reciprocal repression loop between FOXF2 and TGF-β through direct transrepression by SMAD3, miR-182-5p forms a reciprocal repression loop with FOXF2 that directly transrepresses MIR182 expression. Therefore, FOXF2 deficiency accelerates the visceral metastasis of BLBC through unrestricted increases in autocrine and paracrine TGF-β signaling, and miR-182-5p expression. Our findings provide novel mechanisms underlying the roles of TGF-β, miR-182-5p, and FOXF2 in accelerating BLBC dissemination and metastasis, and may facilitate the development of therapeutic strategies for aggressive BLBC.

Circular RNA cESRP1 sensitises small cell lung cancer cells to chemotherapy by sponging miR-93-5p to inhibit TGF-β signalling

Circular RNAs (circRNAs) are novel RNA molecules that play important roles in chemoresistance in different cancers, including breast and gastric cancers. However, whether circRNAs are involved in the response to chemotherapy in small cell lung cancer (SCLC) remains largely unknown. In this study, we observed that cESRP1 (circular RNA epithelial splicing regulatory protein-1) expression was significantly downregulated in the chemoresistant cells compared with the parental chemosensitive cells. cESRP1 enhanced drug sensitivity by repressing miR-93-5p in SCLC. Cytoplasmic cESRP1 could directly bind to miR-93-5p and inhibit the posttranscriptional repression mediated by miR-93-5p, thereby upregulating the expression of the miR-93-5p downstream targets Smad7/p21(CDKN1A) and forming a negative feedback loop to regulate transforming growth factor-β (TGF-β) mediated epithelial-mesenchymal transition. Furthermore, cESRP1 overexpression and TGF-β pathway inhibition both altered tumour responsiveness to chemotherapy in an acquired chemoresistant patient-derived xenograft model. Importantly, cESRP1 expression was downregulated in SCLC patient tissues and was associated with survival. Our findings reveal, for the first time, that cESRP1 plays crucial a role in SCLC chemosensitivity by sponging miR-93-5p to inhibit the TGF-β pathway, suggesting that cESRP1 may serve as a valuable prognostic biomarker and a potential therapeutic target in SCLC patients.

Research Progress on Long Non-coding RNAs and Drug Resistance of Breast Cancer

Breast cancer, as the foremost cause of women's death in the world, is highly metastatic and mutable. Resistance to drugs for chemotherapies, endocrine therapies, and targeted therapies is an important factor that impacts the prognosis of breast cancer. Long non-coding ribonucleic acids (LncRNAs) are crucial regulators of intracellular gene expressions. Some researchers have suggested that expression level of several types of LncRNAs were closely related to the prognosis of patients with breast cancer. LncRNAs significantly impact biological processes such as drug transport, detoxication, apoptosis, epithelial to mesenchymal transition (EMT), and autophagy by regulating intracellular signaling pathways such as multi-drug resistance gene 1 (MDR1), nuclear factor erythroid 2-related factor 2 (NRF2), phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), transforming growth factor-β (TGF-β), BRCA1/2, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This paper will summarize research progress on correlations between LncRNA and drug resistance of breast cancer. It will particularly expound molecular mechanisms through which LncRNAs regulate drug resistance of breast cancer. It will further discuss the feasibility as molecular markers for forecasting drug resistance of breast cancer and may be becoming new targets for treating breast cancer in the future.

Inducers, Attractors and Modulators of CD4+ Treg Cells in Non-Small-Cell Lung Cancer

Lung cancer is the leading cause of cancer-associated deaths worldwide, with non-small cell-lung cancer (NSCLC) accounting for approximately 80% of cases. Immune escape has been demonstrated to play a key role in the initiation and progression of NSCLC, although the underlying mechanisms are diverse and their puzzling nature is far from being understood. As a critical participant in immune escape, the CD4⁺ T cell subset of regulatory T (Treg) cells, with their immunosuppressive functions, has been implicated in the occurrence of many types of cancers. Additionally, therapies based on Treg blockade have benefited a portion of cancer patients, including those with NSCLC. Accumulating literature has noted high Treg infiltration in NSCLC tumor tissues, bone marrow, lymph nodes and/or blood; moreover, the tumor milieu is involved in regulating the proliferation, differentiation, recruitment and suppressive functions of Treg cells. Multifarious mechanisms by which CD4⁺ Treg cells are generated, attracted and modulated in the NSCLC milieu will be discussed in this review.

TrkB-Induced Inhibition of R-SMAD/SMAD4 Activation is Essential for TGF-β-Mediated Tumor Suppressor Activity

TrkB-mediated activation of the IL6/JAK2/STAT3 signaling pathway is associated with the induction of the epithelial–mesenchymal transition (EMT) program and the acquisition of metastatic potential by tumors. Conversely, the transforming of growth factor-β (TGF-β) is implicated in tumor suppression through the canonical SMAD-dependent signaling pathway. Hence, TrkB could play a role in disrupting the potent TGF-β-mediated growth inhibition, a concept that has not been fully explored. Here, we identified TrkB to be a crucial regulator of the TGF-β signaling pathway as it inhibits the TGF-β-mediated tumor suppression and the activation of TrkB kinase. We further show that the interactions between TrkB and SMADs inhibit TGF-β-mediated R-SMAD/SMAD4 complex formation and suppress TGF-β-induced nuclear translocation and target gene expression. Additionally, the knockdown of TrkB restored the tumor inhibitory activity of TGF-β signaling. These observations suggest that interactions between TrkB and SMADs are critical for the inhibition of TGF-β tumor suppressor activity in cancer cells.

Tim-4 in Health and Disease: Friend or Foe?

T-cell immunoglobulin and mucin domain containing 4 (Tim-4) is a phosphatidylserine receptor and is selectively expressed on antigen presenting cells. Recently, Tim-4 was reported to be expressed on iNKT cells, B1 cells, and tumor cells, suggesting it has multiple biological functions. In this review, we mainly summarize the expression and regulation of Tim-4 in immune cells including T cells, macrophages, dendritic cells, NKT cells, B cells, and mast cells. The expression of Tim-4 in these cells implies that Tim-4 might participate in immune related diseases. Emerging evidence emphasizes a substantial role for Tim-4 in maintaining homeostasis by regulating various immune responses, including viral infection, allergy, autoimmunity, and tumor immunity. Here, we collectively evaluated the role of Tim-4 in health and diseases. This summary will be extremely useful to fully understand the function of Tim-4 in the pathogenesis of immune related diseases, which would provide novel clues for the diagnosis and treatment of diseases.

Integrated Analysis of the Functions and Prognostic Values of RNA Binding Proteins in Lung Squamous Cell Carcinoma

Lung cancer is the leading cause of cancer-related deaths worldwide. Dysregulation of RNA binding proteins (RBPs) has been found in a variety of cancers and is related to oncogenesis and progression. However, the functions of RBPs in lung squamous cell carcinoma (LUSC) remain unclear. In this study, we obtained gene expression data and corresponding clinical information for LUSC from The Cancer Genome Atlas (TCGA) database, identified aberrantly expressed RBPs between tumors and normal tissue, and conducted a series of bioinformatics analyses to explore the expression and prognostic value of these RBPs. A total of 300 aberrantly expressed RBPs were obtained, comprising 59 downregulated and 241 upregulated RBPs. Functional enrichment analysis indicated that the differentially expressed RBPs were mainly associated with mRNA metabolic processes, RNA processing, RNA modification, regulation of translation, the TGF-beta signaling pathway, and the Toll-like receptor signaling pathway. Nine RBP genes (A1CF, EIF2B5, LSM1, LSM7, MBNL2, RSRC1, TRMU, TTF2, and ZCCHC5) were identified as prognosis-associated hub genes by univariate, least absolute shrinkage and selection operator (LASSO), Kaplan–Meier survival, and multivariate Cox regression analyses, and were used to construct the prognostic model. Further analysis demonstrated that high risk scores for patients were significantly related to poor overall survival according to the model. The area under the time-dependent receiver operator characteristic curve of the prognostic model was 0.712 at 3 years and 0.696 at 5 years. We also developed a nomogram based on nine RBP genes, with internal validation in the TCGA cohort, which showed a favorable predictive efficacy for prognosis in LUSC. Our results provide novel insights into the pathogenesis of LUSC. The nine-RBP gene signature showed predictive value for LUSC prognosis, with potential applications in clinical decision-making and individualized treatment.

Interleukin-33-nuclear factor-κB-CCL2 signaling pathway promotes progression of esophageal squamous cell carcinoma by directing regulatory T cells

Esophageal cancer is currently one of the most fatal cancers. However, there is no effective treatment. Increasing evidence suggests that interleukin (IL)‐33 has a significant role in tumor progression and metastasis. Currently, the underlying cellular and molecular mechanism of IL‐33 in promoting esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, we investigated whether IL‐33 could induce the epithelial‐mesenchymal transition (EMT) in ESCC. Interleukin‐33 expression was examined in ESCC and corresponding adjacent normal tissues by immunohistochemistry and quantitative real‐time PCR experiments. Elevated IL‐33 levels were observed in ESCC tissues. Further in vitro experiments were undertaken to elucidate the effect of IL‐33 on migration and invasion in KYSE‐450 and Eca‐109 esophageal cancer cells. Knockdown of IL‐33 decreased the metastasis and invasion capacity in esophageal cancer cells, whereas IL‐33 overexpression showed the opposite effect. We then screened CCL2 which is a downstream molecule of IL‐33, and proved that IL‐33 could promote tumor development and metastasis by recruiting regulatory T cells (Tregs) through CCL2, and IL‐33 regulated the expression of CCL2 through transforming growth factor‐β in Treg cells. Knockdown of IL‐33 decreased the development of human ESCC xenografts in BALB/c nude mice. Collectively, we found that the IL‐33/nuclear factor‐κB/CCL2 pathway played an essential role in human ESCC progress. Hence, IL‐33 should be considered as an effective therapy target for ESCC.

Anti-TGF-β attenuates tumor growth via polarization of tumor associated neutrophils towards an anti-tumor phenotype in colorectal cancer

Tumor associated neutrophils (TANs) play important roles in the progress of CRC. Since tumor microenvironments could influence the phenotypes of TANs, altering the tumor microenvironment to polarize the phenotype of TANs may be a new strategy for tumor treatment. This study aims to investigate the effect of anti-TGF-β on the polarization of TANs from a pro-tumor phenotype towards an anti-tumor phenotype in CRC. In this work, CRC patients had more infiltration of TANs and higher expression of TGF-β in CRC tissue when compared with the controls. In vitro, SW480 cells were co-cultured with primed neutrophils, which simulated the TANs in the tumor microenvironment, and TGF-β was blocked by anti-TGF-β (1D11) in order to polarize TANs. Anti-TGF-β treatment increased the cytotoxicity of TANs and decreased the metastatic chemoattractants secreted by TANs, and ultimately increased the apoptosis of CRC cells significantly while remarkably suppressing the migration of tumor cells. The changes of signaling pathways in the TANs and tumor cells were explored. The results showed that anti-TGF-β attenuated CRC may be partly mediated by suppression of PI3K/AKT signaling pathways in TANs and partly mediated by suppression of TGF-β/Smad signaling pathways in tumor cells. Furthermore, the tumor in the mice treated with 1D11 was obviously smaller and had reverse tumorigenesis compared with the controls, while neutrophil depletion reduced the anti-tumor effect of 1D11. Our data suggest that anti-TGF-β attenuates tumor growth via the polarization of TANs to an anti-tumor phenotype in CRC, which provides new strategies for CRC treatment.

Gene Prioritization through Consensus Strategy, Enrichment Methodologies Analysis, and Networking for Osteosarcoma Pathogenesis

Osteosarcoma is the most common subtype of primary bone cancer, affecting mostly adolescents. In recent years, several studies have focused on elucidating the molecular mechanisms of this sarcoma; however, its molecular etiology has still not been determined with precision. Therefore, we applied a consensus strategy with the use of several bioinformatics tools to prioritize genes involved in its pathogenesis. Subsequently, we assessed the physical interactions of the previously selected genes and applied a communality analysis to this protein–protein interaction network. The consensus strategy prioritized a total list of 553 genes. Our enrichment analysis validates several studies that describe the signaling pathways PI3K/AKT and MAPK/ERK as pathogenic. The gene ontology described TP53 as a principal signal transducer that chiefly mediates processes associated with cell cycle and DNA damage response It is interesting to note that the communality analysis clusters several members involved in metastasis events, such as MMP2 and MMP9, and genes associated with DNA repair complexes, like ATM, ATR, CHEK1, and RAD51. In this study, we have identified well-known pathogenic genes for osteosarcoma and prioritized genes that need to be further explored.

Propofol Inhibits Cell Proliferation, Migration, and Invasion via mir-410-3p/Transforming Growth Factor-β Receptor Type 2 (TGFBR2) Axis in Glioma

BACKGROUND Propofol is a common intravenous anesthetic used to induce and maintain anesthesia. Numerous studies have reported that propofol plays an anti-tumor role in diverse human cancers, including glioma. In this research, we explored the roles of propofol and its related molecular mechanisms in glioma. MATERIAL AND METHODS U251 and A172 cells were exposed to different doses of propofol for 24 h. Cell proliferation, migration, and invasion in glioma were evaluated using MTT assay and Transwell assay, respectively. The levels of microRNA-410-3p (miR-410-3p) and transforming growth factor-ß receptor type 2 (TGFBR2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay and Western blot assay, respectively. The association between miR-410-3p and TGFBR2 was predicted by TargetScan and confirmed by dual-luciferase reporter assay. RESULTS Propofol inhibited the proliferation, migration, and invasion of glioma cells in a concentration-dependent way. miR-410-3p was induced and TGFBR2 was inhibited by different concentrations of propofol treatment. Moreover, TGFBR2 was confirmed to be a target gene of miR-410-3p and TGFBR2 was inversely modulated by miR-410-3p in glioma cells. Depletion of miR-410-3p reversed the inhibition of propofol treatment on U251 and A172 cell growth and metastasis, but the effects were further abolished by knocking down the expression of TGFBR2. CONCLUSIONS Propofol can suppress cell growth and metastasis by regulating the miR-410-3p/TGFBR2 axis in glioma.

PD-1 Blockade Reinvigorates Bone Marrow CD8+ T Cells from Patients with Multiple Myeloma in the Presence of TGFβ Inhibitors

PURPOSE

Immune-checkpoint inhibitors have shown therapeutic efficacy in various malignant diseases. However, anti-programmed death (PD)-1 therapy has not shown clinical efficacy in multiple myeloma.

EXPERIMENTAL DESIGN

Bone marrow (BM) mononuclear cells were obtained from 77 newly diagnosed multiple myeloma patients. We examined the expression of immune-checkpoint receptors in BM CD8⁺ T cells and their functional restoration by ex vivo treatment with anti-PD-1 and TGFβ inhibitors.

RESULTS

We confirmed the upregulation of PD-1 and PD-L1 expression in CD8⁺ T cells and myeloma cells, respectively, from the BM of multiple myeloma patients. PD-1-expressing CD8⁺ T cells from the BM of multiple myeloma patients coexpressed other checkpoint inhibitory receptors and exhibited a terminally differentiated phenotype. These results were also observed in BM CD8⁺ T cells specific to myeloma antigens NY-ESO-1 and HM1.24. BM CD8⁺ T cells from multiple myeloma patients exhibited reduced proliferation and cytokine production upon T-cell receptor stimulation. However, anti-PD-1 did not increase the proliferation of BM CD8⁺ T cells from multiple myeloma patients, indicating that T-cell exhaustion in multiple myeloma is hardly reversed by PD-1 blockade alone. Intriguingly, anti-PD-1 significantly increased the proliferation of BM CD8⁺ T cells from multiple myeloma patients in the presence of inhibitors of TGFβ, which was overexpressed by myeloma cells.

CONCLUSIONS

Our findings indicate that combined blockade of PD-1 and TGFβ may be useful for the treatment of multiple myeloma.

On-Target Anti-TGF-β Therapies Are Not Succeeding in Clinical Cancer Treatments: What Are Remaining Challenges?

Metastasis is the leading cause of death for cancer patients. During cancer progression, the initial detachment of cells from the primary tumor and the later colonization of a secondary organ are characterized as limiting steps for metastasis. Epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are opposite dynamic multistep processes that enable these critical events in metastasis by altering the phenotype of cancer cells and improving their ability to migrate, invade and seed at distant organs. Among the molecular pathways that promote tumorigenesis in late-stage cancers, transforming growth factor-β (TGF-β) is described as an EMT master inducer by controlling different genes and proteins related to cytoskeleton assembly, cell-cell attachment and extracellular matrix remodeling. Still, despite the successful outcomes of different TGF-β pharmacological inhibitors in cell culture (in vitro) and animal models (in vivo), results in cancer clinical trials are poor or inconsistent at least, highlighting the existence of crucial components in human cancers that have not been properly explored. Here we review most recent findings to provide perspectives bridging the gap between on-target anti-TGF-β therapies in vitro and in pre-clinical models and the poor clinical outcomes in treating cancer patients. Specifically, we focus on (i) the dual roles of TGF-β signaling in cancer metastasis; (ii) dynamic signaling; (iii) functional differences of TGF-β free in solution vs. in exosomes; (iv) the regulatory effects of tumor microenvironment (TME) - particularly by cancer-associated fibroblasts - on TGF-β signaling pathway. Clearly identifying and establishing those missing links may provide strategies to revitalize and clinically improve the efficacy of TGF-β targeted therapies.

Tumor-associated macrophages regulate gastric cancer cell invasion and metastasis through TGFβ2/NF-κB/Kindlin-2 axis

Objective

Recent studies have shown that tumor-associated macrophages (TAMs) play an important role in cancer invasion and metastasis. Our previous studies have reported that TAMs promote the invasion and metastasis of gastric cancer (GC) cells through the Kindlin-2 pathway. However, the mechanism needs to be clarified.

Methods

THP-1 monocytes were induced by PMA/interleukin (IL)-4/IL-13 to establish an efficient TAM model in vitro and M2 macrophages were isolated via flow cytometry. A dual luciferase reporter system and chromatin immunoprecipitation (ChIP) assay were used to investigate the mechanism of transforming growth factor β2 (TGFβ2) regulating Kindlin-2 expression. Immunohistochemistry was used to study the relationships among TAM infiltration in human GC tissues, Kindlin-2 protein expression, clinicopathological parameters and prognosis in human GC tissues. A nude mouse oncogenesis model was used to verify the invasion and metastasis mechanisms in vivo.

Results

We found that Kindlin-2 expression was upregulated at both mRNA and protein levels in GC cells cocultured with TAMs, associated with higher invasion rate. Kindlin-2 knockdown reduced the invasion rate of GC cells under coculture condition. TGFβ2 secreted by TAMs regulated the expression of Kindlin-2 through the transcription factor NF-кB. TAMs thus participated in the progression of GC through the TGFβ2/NF-κB/Kindlin-2 axis. Kindlin-2 expression and TAM infiltration were significantly positively correlated with TNM stage, and patients with high Kindlin-2 expression had significantly poorer overall survival than patients with low Kindlin-2 expression. Furthermore, Kindlin-2 promoted the invasion of GC cells in vivo.

Conclusions

This study elucidates the mechanism of TAMs participating in GC cell invasion and metastasis through the TGFβ2/NF-κB/Kindlin-2 axis, providing a possibility for new treatment options and approaches.

Structural biology of betaglycan and endoglin, membrane-bound co-receptors of the TGF-beta family

Betaglycan and endoglin, membrane-bound co-receptors of the TGF-β family, are required to mediate the signaling of a select subset of TGF-β family ligands, TGF-β2 and InhA, and BMP-9 and BMP-10, respectively. Previous biochemical and biophysical methods suggested alternative modes of ligand binding might be responsible for these co-receptors to selectively recognize and potentiate the functions of their ligands, yet the molecular details were lacking. Recent progress determining structures of betaglycan and endoglin, both alone and as bound to their cognate ligands, is presented herein. The structures reveal relatively minor, but very significant structural differences that lead to entirely different modes of ligand binding. The different modes of binding nonetheless share certain commonalities, such as multivalency, which imparts the co-receptors with very high affinity for their cognate ligands, but at the same time provides a mechanism for release by stepwise binding of the signaling receptors, both of which are essential for their functions.

Long Noncoding RNA loc285194 Expression in Human Papillomavirus-Positive and -Negative Cervical Squamous Cell Carcinoma, C33A, and SiHa Cells and Transforming Growth Factor-β1

Background

This study aimed to investigate the expression of long noncoding RNA (lncRNA) loc285194 in cervical squamous cell carcinoma (CSCC) biopsies that were positive and negative for human papillomavirus (HPV) and in human CSCC cell lines SiHa and C33A and to investigate the overexpression of lncRNA loc285194.

Material/Methods

Cervical biopsy tissue and plasma samples from 66 patients with histologically confirmed CSCC, that were HPV16-positive (N=22), HPV18-positive (N=27), and HPV-negative (N=17), and healthy controls (N=20) and human CSCC cell lines SiHa (HPV16-positive) and C33A (HPV-negative) were studied. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to measure the expression of lncRNA loc285194 in cervical biopsies and plasma. Enzyme-linked immunosorbent assay (ELISA) and Western blot were used to measure levels of transforming growth factor-β1 (TGF-β1). A lncRNA loc285194 expression vector was constructed and transfected into SiHa and C33A cells that underwent a transwell assay for cell migration.

Results

Expression of lncRNA loc285194 was downregulated in HPV-positive and HPV-negative tissue samples and plasma from patients with CSCC and distinguished between patients and healthy controls. Plasma levels of loc285194 and TGF-β1 were significantly correlated with the presence of CSCC. In SiHa and C33A cells, TGF-β1 expression was downregulated, and cell migration was inhibited following lncRNA loc285194 overexpression. Although lncRNA loc285194 expression was not affected by TGF-β1 treatment, its effects on cell migration were reduced by TGF-β1.

Conclusions

The expression of lncRNA loc285194 inhibited the migration of CSCC cells in vitro through the inactivation of TGF-β1.

TGFβ induces stemness through non-canonical AKT-FOXO3a axis in oral squamous cell carcinoma

Background

FOXO3a has been widely regarded as a tumor suppressor. It also plays a paradoxical role in regulating the cancer stem cells (CSCs), responsible for tumor-initiation, chemo-resistance, and recurrence in various solid tumors, including oral squamous cell carcinoma (OSCC). This study aims to uncover the role of FOXO3a and its importance for a non-canonical pathway of TGFβ in regulating the OSCC stemness.

Methods

We identified FOXO3a expression in OSCC tissues and cell lines using immunohistochemistry and western blot. The correlation between FOXO3a and stemness was evaluated. Stable cell lines with differential expression of FOXO3a were constructed using lentiviruses. The effects of FOXO3a on stem-cell like properties in OSCC was further evaluated in vitro and in vivo. We also explored the effect of TGFβ on FOXO3a with respect to its expression and function.

Findings

Our findings suggest that FOXO3a was widely expressed and negatively correlated with the stemness in OSCC. This regulation can be abolished by TGFβ through phosphorylation, nuclear exclusion, and degradation in the non-Smad pathway. We also observed that non-Smad AKT-FOXO3a axis is essential to regulate stemness of CSCs by TGFβ.

Interpretation

TGFβ induces stemness through non-canonical AKT-FOXO3a axis in OSCC. Our study provides a foundation to understand the mechanism of CSCs and a possible therapeutic target to eliminate CSCs.

The Outcome of TGFβ Antagonism in Metastatic Breast Cancer Models In Vivo Reflects a Complex Balance between Tumor-Suppressive and Proprogression Activities of TGFβ

PURPOSE

TGFβs are overexpressed in many advanced cancers and promote cancer progression through mechanisms that include suppression of immunosurveillance. Multiple strategies to antagonize the TGFβ pathway are in early-phase oncology trials. However, TGFβs also have tumor-suppressive activities early in tumorigenesis, and the extent to which these might be retained in advanced disease has not been fully explored.

EXPERIMENTAL DESIGN

A panel of 12 immunocompetent mouse allograft models of metastatic breast cancer was tested for the effect of neutralizing anti-TGFβ antibodies on lung metastatic burden. Extensive correlative biology analyses were performed to assess potential predictive biomarkers and probe underlying mechanisms.

RESULTS

Heterogeneous responses to anti-TGFβ treatment were observed, with 5 of 12 models (42%) showing suppression of metastasis, 4 of 12 (33%) showing no response, and 3 of 12 (25%) showing an undesirable stimulation (up to 9-fold) of metastasis. Inhibition of metastasis was immune-dependent, whereas stimulation of metastasis was immune-independent and targeted the tumor cell compartment, potentially affecting the cancer stem cell. Thus, the integrated outcome of TGFβ antagonism depends on a complex balance between enhancing effective antitumor immunity and disrupting persistent tumor-suppressive effects of TGFβ on the tumor cell. Applying transcriptomic signatures derived from treatment-naïve mouse primary tumors to human breast cancer datasets suggested that patients with breast cancer with high-grade, estrogen receptor-negative disease are most likely to benefit from anti-TGFβ therapy.

CONCLUSIONS

Contrary to dogma, tumor-suppressive responses to TGFβ are retained in some advanced metastatic tumors. Safe deployment of TGFβ antagonists in the clinic will require good predictive biomarkers.

The Roles of TIF1γ in Cancer

Transcriptional intermediary factor 1 γ (TIF1γ), also known as TRIM33, RFG7, PTC7, or Ectodermin, is an E3 ubiquitin-ligase family member with a ring-box-coiled-coil region. It can regulate TGF-β/Smad signaling in two different ways in different cellular contexts. On one hand, TIF1γ can monoubiquitinate Smad4 to inhibit the formation of Smad2/3/4 nuclear complexes. On the other hand, TIF1γ can function as a cofactor of phosphorylated (p)-Smad2/3, competing with Smad4 to inhibit the formation of the Smad2/3/4 complex. In addition, TIF1γ has been reported to play a role in transcription elongation, cellular differentiation, embryonic development, and mitosis. As transforming growth factor-β (TGF-β) superfamily signaling plays an important role in the occurrence and development of cancer, and TIF1γ was reported to be involved in the regulation of TGF-β superfamily signaling, studies on TIF1γ during the last decade have focused on its role in the development of cancer. However, TIF1γ can function either as a tumor suppressor or promoter in different cellular contexts, yet there are few reviews focusing on the roles of TIF1γ in cancer. Hence, in this paper we systematically review and discuss the roles of TIF1γ in cancer. Firstly, we review the biological features, the regulatory mechanisms and the related signaling pathways of TIF1γ. Next, we illustrate the roles of TIF1γ in different tumors. We then provide a tentative hypothesis that explains the dual roles of TIF1 γ in cancer. Finally, we provide our viewpoint regarding the future developments of cancer research focusing on TIF1γ, especially in relation to the effects of TIF1γ on tumoral immunity.

Rictor ablation in BMSCs inhibits bone metastasis of TM40D cells by attenuating osteolytic destruction and CAF formation

The mTOR complex 2 (mTORC2) is recognized as a promising target for breast cancer treatment. As mTORC2-specific inhibitors do not yet exist, studies into the role of mTORC2 in cancer are performed by deleting Rictor or by RNAi-mediated Rictor silencing. The purpose of this study was to explore the effects of Rictor ablation in bone mesenchymal stromal cells (BMSCs) on bone metastasis of breast cancer. First, female mice with the genotype of Prx1-Cre;Rictor^f/f (hereafter RiCKO) or Rictor^f/f (as control) were injected intratibially with cells of the breast cancer cell line (TM40D) at 4 months of age. Three weeks later, osteolytic bone destruction was detected in metastatic legs by X-ray and micro-CT. We found that Rictor ablation in BMSCs inhibited TM40D-induced osteolytic bone destruction and resulted in greater bone volume maintenance in vivo. Lower CTX-I serum level, a decreased number of TRAP+ osteoclasts and lower Cathepsin-K expression observed at the tumor-bone interface indicated that osteoclastogenesis was inhibited in RiCKO mice. Additionally, co-culture experiments confirmed that Rictor deletion in BMSCs diminished osteoclast differentiation partly via down regulation of RANKL expression. Furthermore, Rictor deficiency was found to reduce the transition of BMSCs to CAFs coupled with decreased secretion of cytokines (IL-6, RANKL, TGFβ), which resulted in lower chemotaxis and less proliferation in TM40D cells. These results suggest that Rictor ablation in BMSCs plays dual roles in breast cancer bone metastasis: (1) repression of osteolytic bone destruction; (2) inhibition of tumor growth.

Transforming Growth Factor-Beta (TGFβ) Signaling Pathway in Cholangiocarcinoma

Cholangiocarcinoma is a deadly cancer worldwide, associated with a poor prognosis and limited therapeutic options. Although cholangiocarcinoma accounts for less than 15% of liver primary cancer, its silent nature restricts early diagnosis and prevents efficient treatment. Therefore, it is of clinical relevance to better understand the molecular basis of cholangiocarcinoma, including the signaling pathways that contribute to tumor onset and progression. In this review, we discuss the genetic, molecular, and environmental factors that promote cholangiocarcinoma, emphasizing the role of the transforming growth factor β (TGFβ) signaling pathway in the progression of this cancer. We provide an overview of the physiological functions of TGFβ signaling in preserving liver homeostasis and describe how advanced cholangiocarcinoma benefits from the tumor-promoting effects of TGFβ. Moreover, we report the importance of noncoding RNAs as effector molecules downstream of TGFβ during cholangiocarcinoma progression, and conclude by highlighting the need for identifying novel and clinically relevant biomarkers for a better management of patients with cholangiocarcinoma.

Transforming growth factor beta 1 polymorphisms and haplotypes associated with breast cancer susceptibility: A case-control study in Tunisian women

Variable association of transforming growth factor beta 1 (TGFβ1) in breast cancer (BC) pathogenesis was documented, and the contribution of specific TGFB1 polymorphisms to the progression of BC and associated features remains poorly understood. We investigated the contribution of TGFB1 rs1800469, rs1800470, rs1800471, and rs1800472 variants and 4-locus TGFB1 haplotypes on BC susceptibility, and pathological presentation of BC subtypes. Study subjects comprised 430 female BC cases, and 498 cancer-free control women. BC-associated pathological parameters were also evaluated for correlation with TGFB1 variants. Results obtained showed that the minor allele frequency (MAF) of rs1800471 (+74G>C) was higher seen in BC cases than in control subjects, and was associated with increased risk of BC. Significant differences in rs1800471 and rs1800469 (-509C>T) genotype distribution were noted between BC cases and controls, which persisted after controlling for key covariates. TGFB1 rs1800472 was positively, while rs1800470 was negatively associated with triple negativity, while rs1800470 positively correlated with menarche, but negatively with tumor size and molecular type, and rs1800469 correlated positively with menstrual irregularity, distant metastasis, nodal status, and hormonotherapy. Heterogeneity in LD pattern was noted between the tested TGFB1 variants. Four-locus (rs1800472-rs1800471-rs1800470-rs1800469) Haploview analysis identified haplotype TGCT to be negatively associated, and haplotypes CGTT and CCCC to be positively associated with BC. This association of CGTT and CCCC, but not TGCT, with BC remained significant after controlling for key covariates. In conclusion, TGFB1 alleles and specific genotypes, and 4-locus TGFB1 haplotypes influence BC susceptibility, suggesting dual association imparted by specific SNP, consistent with dual role for TGFB1 in BC pathogenesis.

TGF-β signaling in intervertebral disc health and disease

OBJECTIVE

This paper aims to provide a comprehensive review of the changing role of transforming growth factor-β (TGF-β) signaling in intervertebral disc (IVD) health and disease.

METHODS

A comprehensive literature search was performed using PubMed terms 'TGF-β' and 'IVD'.

RESULTS

TGF-β signaling is necessary for the development and growth of IVD, and can play a protective role in the restoration of IVD tissues by stimulating matrix synthesis, inhibiting matrix catabolism, inflammatory response and cell loss. However, excessive activation of TGF-β signaling is detrimental to the IVD, and inhibition of the aberrant TGF-β signaling can delay IVD degeneration.

CONCLUSIONS

Activation of TGF-β signaling has a promising treatment prospect for IVD degeneration, while excessive activation of TGF-β signaling may contribute to the progression of IVD degeneration. Studies aimed at elucidating the changing role of TGF-β signaling in IVD at different pathophysiological stages and its specific molecular mechanisms are needed, and these studies will contribute to safe and effective TGF-β signaling-based treatments for IVD degeneration.

An autocrine ActivinB mechanism drives TGFβ/Activin signaling in Group 3 medulloblastoma

Medulloblastoma (MB) is a pediatric tumor of the cerebellum divided into four groups. Group 3 is of bad prognosis and remains poorly characterized. While the current treatment involving surgery, radiotherapy, and chemotherapy often fails, no alternative therapy is yet available. Few recurrent genomic alterations that can be therapeutically targeted have been identified. Amplifications of receptors of the TGFβ/Activin pathway occur at very low frequency in Group 3 MB. However, neither their functional relevance nor activation of the downstream signaling pathway has been studied. We showed that this pathway is activated in Group 3 MB with some samples showing a very strong activation. Beside genetic alterations, we demonstrated that an ActivinB autocrine stimulation is responsible for pathway activation in a subset of Group 3 MB characterized by high PMEPA1 levels. Importantly, Galunisertib, a kinase inhibitor of the cognate receptors currently tested in clinical trials for Glioblastoma patients, showed efficacy on orthotopically grafted MB‐PDX. Our data demonstrate that the TGFβ/Activin pathway is active in a subset of Group 3 MB and can be therapeutically targeted.

Integrin αvβ6 mediates epithelial-mesenchymal transition in human bronchial epithelial cells induced by lipopolysaccharides of Pseudomonas aeruginosa via TGF-β1-Smad2/3 signaling pathway

Lower respiratory tract infection due to Pseudomonas aeruginosa has become increasingly challenging, resulting in a worse morbidity and mortality. Airway remodeling is a common phenomenon in this process, to which epithelial-mesenchymal transition (EMT) may contribute as an important promoter. Previous studies showed that epithelium-specific integrin αvβ6-mediated EMT was involved in pulmonary fibrosis via transforming growth factor-β1 (TGF-β1) signaling, but whether integrin αvβ6 plays a role in the P. aeruginosa-associated airway remodeling remains unknown. BEAS-2B cells were incubated with lipopolysaccharide (LPS) from P. aeruginosa in the presence or the absence of integrin αvβ6-blocking antibodies. Morphologic changes were observed by an inverted microscopy. The EMT markers were detected using Western blotting and immunofluorescence. The activation of TGF-β1-Smad2/3 signaling pathway was assessed. Furthermore, matrix metalloproteinase (MMP)-2 and -9 in the medium were measured using ELISA. P. aeruginosa's LPS decreased the expression of the epithelial marker E-cadherin and promoted the mesenchymal markers, vimentin and α-smooth muscle actin in BEAS-2B cells. The expression of integrin αvβ6 was significantly increased during EMT process. Blocking integrin αvβ6 could attenuate P. aeruginosa's LPS-induced EMT markers' expression via TGF-β1-Smad2/3 signaling pathway. Furthermore, blocking integrin αvβ6 could prevent morphologic changes and oversecretion of MMP-2 and -9. Integrin αvβ6 mediates epithelial-mesenchymal transition in human bronchial epithelial cells induced by lipopolysaccharides of P. aeruginosa via TGF-β1-Smad2/3 signaling pathway and might be a promising therapeutic target for P. aeruginosa-associated airway remodeling.

Activation of Slit2/Robo1 Signaling Promotes Tumor Metastasis in Colorectal Carcinoma through Activation of the TGF-β/Smads Pathway

Slit2 (slit guidance ligand 2), a ligand of the Roundabout1 (Robo1) transmembrane receptor, is often overexpressed in colorectal carcinomas (CRCs). In this study, we performed data mining in the Metabolic gEne RApid Visualizer (MERAV) database and found that Slit2 and TGF-β1 (Transforming growth factor-β1) are highly expressed in carcinomas relative to those in tumor-free tissues from healthy volunteers or wild type mice. Furthermore, expression of Slit2 and TGF-β1 in CRCs increases with pathological stages. Serum levels of Slit2 in patients with CRC and in ApcMin/+ mice with spontaneous intestinal adenoma were significantly increased compared with those in healthy controls. Specific blockage of Slit2 binding to Robo1 inactivated TGF-β/Smads signaling and inhibited tumor cell migration and metastasis, which can be partially restored by treatment with TGF-β1. However, specific inhibition of TGF-β1/Smads signaling reduced CRC tumor cell migration and invasion without affecting cell proliferation. This study suggests that activation of Slit2/Robo1 signaling in CRC induces tumor metastasis partially through activation of the TGF-β/Smads pathway.

Long non-coding RNA-neighboring enhancer of FOXA2 inhibits the migration and invasion of small cell lung carcinoma cells by downregulating transforming growth factor-β1

Long non-coding RNA-neighboring enhancer of FOXA2 (lncRNA-NEF) is a recently identified tumor suppressor in hepatocellular carcinoma. The present study aimed to investigate the role of lncRNA-NEF in small cell lung carcinoma (SCLC). Expression levels of lncRNA-NEF in the lung biopsy tissues and plasma samples from patients with SCLC and from healthy controls were detected using reverse transcription-quantitative polymerase chain reaction. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic value of lncRNA-NEF as a marker of SCLC. The association between plasma levels of lncRNA-NEF and the clinical data of patients was analyzed using the χ² test. An lncRNA-NEF expression vector was prepared and transfected into SCLC cells, and cellular migration and invasion were detected using Transwell migration and invasion assays, respectively. The expression of transforming growth factor β1 (TGF-β1) was detected using western blotting. The results demonstrated that the expression level of lncRNA-NEF was lower in patients with SCLC compared with that in healthy controls. The expression level of lncRNA-NEF in the plasma was associated with distant tumor metastasis. lncRNA-NEF overexpression inhibited SCLC cell migration and invasion, resulting in TGF-β1 downregulation, while treatment with exogenous TGF-β1 reduced the inhibitory effects of lncRNA-NEF overexpression on migration and invasion. Therefore, it was concluded that lncRNA-NEF inhibited the migration and invasion of SCLC cells, which was potentially associated with the downregulation of TGF-β1.

Aberrant NFATc1 signaling counteracts TGFβ-mediated growth arrest and apoptosis induction in pancreatic cancer progression

Given its aggressive tumor biology and its exceptional therapy resistance, pancreatic ductal adenocarcinoma (PDAC) remains a major challenge in cancer medicine and is characterized by a 5-year survival rate of <8%. At the cellular level, PDAC is largely driven by the activation of signaling pathways that eventually converge in altered, tumor-promoting transcription programs. In this study, we sought to determine the interplay between transforming growth factor β (TGFβ) signaling and activation of the inflammatory transcription factor nuclear factor of activated T cells (NFATc1) in the regulation of transcriptional programs throughout PDAC progression. Genome-wide transcriptome analysis and functional studies performed in primary PDAC cells and transgenic mice linked nuclear NFATc1 expression with pro-proliferative and anti-apoptotic gene signatures. Consistently, NFATc1 depletion resulted in downregulation of target genes associated with poor PDAC outcome and delayed pancreatic carcinogenesis in vivo. In contrast to previous reports and consistent with a concept of retained tumor suppressive TGFβ activity, even in established PDAC, TGFβ treatment reduced PDAC cell proliferation and promoted apoptosis even in the presence of oncogenic NFATc1. However, combined TGFβ treatment and NFATc1 depletion resulted in a tremendous abrogation of tumor-promoting gene signatures and functions. Chromatin studies implied that TGFβ-dependent regulators compete with NFATc1 for the transcriptional control of jointly regulated target genes associated with an unfavorable PDAC prognosis. Together, our findings suggest opposing consequences of TGFβ and NFATc1 activity in the regulation of pro-tumorigenic transcription programs in PDAC and emphasize the strong context-dependency of key transcription programs in the progression of this devastating disease.

Identification of Cancer Drivers at CTCF Insulators in 1,962 Whole Genomes

Recent studies have shown that mutations at non-coding elements, such as promoters and enhancers, can act as cancer drivers. However, an important class of non-coding elements, namely CTCF insulators, has been overlooked in the previous driver analyses. We used insulator annotations from CTCF and cohesin ChIA-PET and analyzed somatic mutations in 1,962 whole genomes from 21 cancer types. Using the heterogeneous patterns of transcription-factor-motif disruption, functional impact, and recurrence of mutations, we developed a computational method that revealed 21 insulators showing signals of positive selection. In particular, mutations in an insulator in multiple cancer types, including 16% of melanoma samples, are associated with TGFB1 up-regulation. Using CRISPR-Cas9, we find that alterations at two of the most frequently mutated regions in this insulator increase cell growth by 40%-50%, supporting the role of this boundary element as a cancer driver. Thus, our study reveals several CTCF insulators as putative cancer drivers.

Prosaposin is a biomarker of mesenchymal glioblastoma and regulates mesenchymal transition through the TGF-β1/Smad signaling pathway

Mesenchymal glioblastoma (GBM) is the most aggressive subtype of GBM. Our previous study found that neurotrophic factor prosaposin (PSAP) is highly expressed and secreted in glioma and can promote the growth of glioma. The role of PSAP in mesenchymal GBM is still unclear. In this study, bioinformatic analysis, western blotting and RT-qPCR were used to detect the expression of PSAP in different GBM subtypes. Human glioma cell lines and patient-derived glioma stem cells were studied in vitro and in vivo, revealing that mesenchymal GBM expressed and secreted the highest level of PSAP among four subtypes of GBM, and PSAP could promote GBM invasion and epithelial-mesenchymal transition (EMT)-like processes in vivo and in vitro. Bioinformatic analysis and western blotting showed that PSAP mainly played a regulatory role in GBM invasion and EMT-like processes via the TGF-β1/Smad signaling pathway. In conclusion, the overexpression and secretion of PSAP may be an important factor causing the high invasiveness of mesenchymal GBM. PSAP is therefore a potential target for the treatment of mesenchymal GBM. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hepatic progenitor cell activation is induced by the depletion of the gut microbiome in mice

The homeostasis of the gut microbiome is crucial for human health and for liver function. However, it has not been established whether the gut microbiome influence hepatic progenitor cells (HPCs). HPCs are capable of self‐renewal and differentiate into hepatocytes and cholangiocytes; however, HPCs are normally quiescent and are rare in adults. After sustained liver damage, a ductular reaction occurs, and the number of HPCs is substantially increased. Here, we administered five broad‐spectrum antibiotics for 14 days to deplete the gut microbiomes of male C57BL/6 mice, and we measured the plasma aminotransferases and other biochemical indices. The expression levels of two HPC markers, SRY‐related high mobility group‐box gene 9 (Sox9) and cytokeratin (CK), were also measured. The plasma aminotransferase activities were not affected, but the triglyceride, lactate dehydrogenase, low‐density lipoprotein, and high‐density lipoprotein concentrations were significantly altered; this suggests that liver function is affected by the composition of the gut microbiome. The mRNA expression of Sox9 was significantly higher in the treated mice than it was in the control mice (p < 0.0001), and a substantial expression of Sox9 and CK was observed around the bile ducts. The mRNA expression levels of proinflammatory factors (interleukin [IL]‐1β, IL‐6, tumor necrosis factor [TNF]‐α, and TNF‐like weak inducer of apoptosis [Tweak]) were also significantly higher in the antibiotic‐treated mice than the levels in the control mice. These data imply that the depletion of the gut microbiome leads to liver damage, negatively impacts the hepatic metabolism and function, and activates HPCs. However, the underlying mechanisms remain to be determined.

Treg-mediated acquired resistance to immune checkpoint inhibitors

T Regulatory cells (Tregs) act as a double-edged sword by regulating immune homeostasis (protective role) and inhibiting immune responses in different disease settings (pathological role). They contribute to cancer development and progression by suppressing T effector cell (Teff) functions. Decreased ratios of intratumoral CD8⁺ T cells to Tregs have been associated with poor prognosis in most cancer types. Targeting immune checkpoints (ICs), such as cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death-1 (PD-1), by immune checkpoint inhibitors (ICIs) in cancer patients has been beneficial in inducing anti-tumor immune responses and improving clinical outcomes. However, response rates remain relatively low, ranging from 15 to 40% depending on cancer type. Additionally, a significant proportion of patients who initially demonstrates a clinical response can acquire resistance overtime. This acquired resistance could occur due to the emergence of compensatory mechanisms within the tumor microenvironment (TME) to evade the anti-tumor effects of ICIs. In this review, we describe the immunosuppressive role of Tregs in the TME, the effects of currently approved ICIs on Treg phenotype and function, and the mechanisms of acquired resistance to ICIs mediated by Tregs within the TME, such as the over-expression of ICs, the up-regulation of immunosuppressive molecules, and apoptotic Treg-induced immunosuppression. We also describe potential therapeutic strategies to target Tregs in combination with ICIs aiming to overcome such resistance and improve clinical outcomes. Elucidating the Treg-mediated acquired resistance mechanisms should benefit the designing of well-targeted therapeutic strategies to overcome resistance and maximize the therapeutic efficacy in cancer patients.

Modulation of cancer cell signaling by long noncoding RNAs

Cellular signaling pathways play a very important role in almost all molecular processes in the cell, and are generally composed of a complex set of cascades in which enzymes and proteins play a key role. These signaling pathways include different types of cellular signaling classified based on their receptors and effector proteins such as enzyme-linked receptors, cytokine receptors, and G-protein-coupled receptors each of which is subdivided into different classes. Signaling pathways are tightly controlled by different mechanisms mostly thorough inhibiting/activating their receptors or effector proteins. In the last two decades, our knowledge of molecular biology has changed dramatically and today we know that more than 85% of the human genome expresses noncoding RNAs most of which are crucial in the cellular and molecular mechanisms of cells. One of these noncoding RNAs are long noncoding RNAs (lncRNA) containing more than 200 nucleotides. LncRNAs participate in the progression of cancer growth through several mechanism including signaling pathways. In this review, we summarize some of the most important of lncRNAs and their effect on important signaling pathways.

Reduced USP33 expression in gastric cancer decreases inhibitory effects of Slit2-Robo1 signalling on cell migration and EMT

OBJECTIVES

Gastric cancer (GC) is one of the most common cancers in the world, causing a large number of deaths every year. The Slit-Robo signalling pathway, initially discovered for its critical role in neuronal guidance, has recently been shown to modulate tumour invasion and metastasis in several human cancers. However, the role of Slit-Robo signalling and the molecular mechanisms underlying its role in the pathogenesis of gastric cancer remains to be elucidated.

MATERIALS AND METHODS

Slit2, Robo1 and USP33 expressions were analysed in datasets obtained from the Oncomine database and measured in human gastric cancer specimens. The function of Slit2-Robo1-USP33 signalling on gastric cancer cells migration and epithelial-mesenchymal transition (EMT) was studied both in vitro and in vivo. The mechanism of the interaction between Robo1 and USP33 was explored by co-IP and ubiquitination protein analysis.

RESULTS

The mRNA and protein levels of Slit2 and Robo1 are lower in GC tissues relative to those in adjacent healthy tissues. Importantly, Slit2 inhibits GC cell migration and suppresses EMT process in a Robo-dependent manner. The inhibitory function of Slit2-Robo1 is mediated by ubiquitin-specific protease 33 (USP33) via deubiquitinating and stabilizing Robo1. USP33 expression is decreased in GC tissues, and reduced USP33 level is correlated with poor patient survival.

CONCLUSIONS

Our study reveals the inhibitory function of Slit-Robo signalling in GC and uncovers a role of USP33 in suppressing cancer cell migration and EMT by enhancing Slit2-Robo1 signalling. USP33 represents a feasible choice as a prognostic biomarker for GC.

LncRNA NEF inhibits migration and invasion of HPV-negative cervical squamous cell carcinoma by inhibiting TGF-β pathway

LncRNA NEF was a recently identified tumor suppressor lncRNA in hepatocellular carcinoma. Our study aimed to explore the role of NEF in cervical squamous cell carcinoma (CSCC) patients. In the present study, expression of NEF in tumor tissue (cervical biopsies for healthy control) and serum of human papillomaviruses (HPV)-negative and HPV-positive CSCC patients as well as healthy controls was detected by qRT-PCR. Diagnostic and prognostic values of NEF for CSCC were evaluated by ROC curve and survival curve analysis, respectively. NEF expression vector was transfected into CSCC cells and the effects on cell migration and invasion as well as TGF-β1 expression were investigated by Transwell migration assay, Transwell invasion assay, and Western blot, respectively. We found that expression of NEF in cervical tissues (tumor tissues for CSCC patients) and serum was significantly down-regulated in HPV-negative CSCC patients than in healthy controls and HPV positive patients, but no significant differences were found between healthy controls and HPV positive patients. Low serum levels of NEF distinguished HPV-negative CSCC patients from healthy controls and indicated poor survival. NEF overexpression inhibited the migration and invasion of HPV-negative but not HPV-positive CSCC cells. NEF overexpression down-regulated TGF-β1 in HPV-negative CSCC cells but not in HPV-positive CSCC cells. TGF-β1 treatment reduced the effects of NEF overexpression on cell migration and invasion. Therefore, we conclude that lncRNA NEF may inhibit the migration and invasion of HPV-negative cervical squamous cell carcinoma by inhibiting TGF-β pathway.

Long Non-Coding RNA AWPPH Promotes Postoperative Distant Recurrence in Resected Non-Small Cell Lung Cancer by Upregulating Transforming Growth Factor beta 1 (TGF-β1)

Background

Postoperative recurrence of cancers is responsible for a large portion of deaths in cancer patients. Our study investigated the involvement of lncRNA AWPPH in recurrence of resected non-small cell lung cancer (NSCLC).

Material/Methods

A total of 128 patients were followed up for 3 years. Blood was extracted from each patient on the day of discharge, the day of the diagnosis of recurrence, or at the end of follow-up. Blood from 30 healthy controls was used as a control group. Patient were divided into 3 groups – a non-recurrence group (NR, n=54), a local recurrence group (LR, n=42), and a distant recurrence (DR, n=32) group – according to the follow-up results. Blood AWPPP was detected by qRT-PCR. AWPPH expression vectors were transfected into cells of human NSCLC cell lines. Cell migration and invasion were detected by Transwell migration and invasion assay, respectively. TGF-β1 expression was detected by Western blot analysis.

Results

Blood AWPPH levels were the highest in the DR group, followed by the LR and NR groups. The lowest blood AWPPH levels were observed in the control group. Blood AWPPH levels increased significantly in the DR group but not in the NR and LR groups during follow-up. Blood AWPPH levels were positively correlated with TGF-β1 mRNA levels in the DR group but not in the NR and LR groups during follow-up. AWPPH overexpression promoted cell migration and invasion and upregulated TGF-β1 expression.

Conclusions

lncRNA AWPPH can promote postoperative distant recurrence in resected NSCLC by upregulating TGF-β1.

MiR-9 promotes synovial sarcoma cell migration and invasion by directly targeting CDH1

BACKGROUND

Invasion and metastasis of synovial sarcoma is the leading cause of death in patients. Epithelial mesenchymal transition (EMT) accelerates tumor cell invasion and metastasis. MiR-9 promotes tumor metastasis by inducing EMT. However, the role of miR-9 in synovial sarcoma is still not clear.

METHODS

Overexpression or knockdown of miR-9 in human synovial sarcoma (HSS) cell lines was carried out by miR-9 mimics or miR-9 inhibitors transfection. Cell proliferation, apoptosis, migration and invasion were detected using MTS and colony formation assays, flow cytometry, wound healing and transwell assays, respectively. Luciferase reporter assay was applied to study the interaction between miR-9 and CDH1. Nude mice xenograft model was established, and immunohistochemistry staining assessed Ki-67 level. The related mRNA and protein expression levels were evaluated by qRT-PCR and Western blotting.

RESULTS

The bioinformatics analyses and luciferase reporter assay showed that miR-9 can target CDH1 3'-UTR. Moreover, miR-9 could induce EMT of HSS cells via targeting CDH1. The negative regulation of miR-9 on CDH1 expression was also confirmed in a mouse xenograft model of synovial sarcoma. Furthermore, miR-9 was observed to induce HSS cell proliferation, migration and invasion and inhibit apoptosis. MAPK/ERK and Wnt/β-catenin signal pathways were activated by the miR-9 overexpression in HSS cells, and then further enhancing tumorigenesis of HSS, which was further confirmed in the mouse model.

CONCLUSION

MiR-9 induces EMT by targeting CDH1, and activates MAPK/ERK and Wnt/β-catenin signal pathways, thus promoting HSS tumorigenesis.

SMAD3 silencing enhances DNA damage in radiation therapy by interacting with MRE11-RAD50-NBS1 complex in glioma

Radiotherapy is the major treatment modality for malignant glioma. However, the treatment response of radiotherapy is suboptimal due to resistance. Here we aimed to explore the effect and mechanism of Mothers against decapentaplegic homologue (SMAD3) silencing in sensitizing malignant glioma to radiotherapy. Clonogenic assay was used to evaluate the sensitivity of glioma cells to increasing doses of radiation. Glioma cells were transfected with small-interfering RNAs (siRNAs) specific to SMAD3. Overexpression of SMAD3 was achieved by transfecting expression plasmid encoding SMAD3 cDNA. Changes in MRE11-RAD50-NBS1 mRNA and protein levels were assessed through qPCR analysis and western blot analysis, respectively. Chromatin immunoprecipitation (ChIP) was used to confirm the interaction between SMAD3 and MRE11-RAD50-NBS1 (MRN) complex. Silencing of SMAD3 increased sensitivity of glioma cells to radiotherapy. MRE11, RAD50 and NBS1 were overexpressed in response to radiotherapy, which was attenuated by SMAD3 silencing while boosted by SMAD3 overexpression. ChIP analysis confirmed the interaction of SMAD3 with MRE11, RAD50 and NBS1 under radiotherapy, which was inhibited by SMAD3 silencing. SMAD3 silencing is an effective strategy for sensitizing glioma to radiotherapy, which is mediated by the interaction of SMAD3 with the MRN complex.

Cancer-associated fibroblasts: how do they contribute to metastasis?

Cancer-associated fibroblasts (CAFs) are activated fibroblasts in the tumor microenvironment. They are one of the most prominent cell types in the stroma and produce large amounts of extracellular matrix molecules, chemokines, cytokines and growth factors. Importantly, CAFs promote cancer progression and metastasis by multiple pathways. This, together with their genetic stability, makes them an interesting target for cancer therapy. However, CAF heterogeneity and limited knowledge about the function of the different CAF subpopulations in vivo, are currently major obstacles for identifying specific molecular targets that are of value for cancer treatment. In this review, we discuss recent major findings on CAF development and their metastasis-promoting functions, as well as open questions to be addressed in order to establish successful cancer therapies targeting CAFs.

Linc-pint inhibits early stage pancreatic ductal adenocarcinoma growth through TGF-β pathway activation

Long intergenic non-protein coding RNA, p53 induced transcript (Linc-pint) is a newly identified long non-coding RNA, which has demonstrated antitumor activities in various types of cancer. The present study aimed to investigate the role of Linc-pint in pancreatic ductal adenocarcinoma (PDAC). Plasma samples from patients with PDAC, and PDAC and normal cell lines were used in the study. Gene expression was analyzed by reverse transcription-quantitative polymerase chain reaction. Western blotting was used to assess protein level. Transforming growth factor β1 (TGF-β1) plasma level was determined by ELISA. Cancer cell proliferation was measured in vitro with the Cell Counting Kit-8 assy. The results demonstrated that Linc-pint plasma levels were significantly lower in patients with stage 0–1 PDAC compared with healthy controls. In addition, Linc-pint downregulation effectively distinguished patients with PDAC from healthy controls. Linc-pint and TGF-β1 plasma levels were positively correlated in patients with PDAC but not in healthy controls. Furthermore, Linc-pint overexpression upregulated TGF-β1 expression in PDAC cells but not in normal pancreatic ductal cells; however, exogenous TGF-β1 exhibited no significant effects on Linc-pint expression. Linc-pint overexpression and TGF-β1 both inhibited PDAC cell proliferation, whereas treatment with a TGF-β inhibitor reduced their inhibitory effects on cell proliferation. In conclusion, results from the present study suggested that Linc-pint may inhibit early stage PDAC growth through TGF-β pathway activation.

Specificity, versatility, and control of TGF-β family signaling

Encoded in mammalian cells by 33 genes, the transforming growth factor-β (TGF-β) family of secreted, homodimeric and heterodimeric proteins controls the differentiation of most, if not all, cell lineages and many aspects of cell and tissue physiology in multicellular eukaryotes. Deregulation of TGF-β family signaling leads to developmental anomalies and disease, whereas enhanced TGF-β signaling contributes to cancer and fibrosis. Here, we review the fundamentals of the signaling mechanisms that are initiated upon TGF-β ligand binding to its cell surface receptors and the dependence of the signaling responses on input from and cooperation with other signaling pathways. We discuss how cells exquisitely control the functional presentation and activation of heteromeric receptor complexes of transmembrane, dual-specificity kinases and, thus, define their context-dependent responsiveness to ligands. We also introduce the mechanisms through which proteins called Smads act as intracellular effectors of ligand-induced gene expression responses and show that the specificity and impressive versatility of Smad signaling depend on cross-talk from other pathways. Last, we discuss how non-Smad signaling mechanisms, initiated by distinct ligand-activated receptor complexes, complement Smad signaling and thus contribute to cellular responses.

Opposing roles and potential antagonistic mechanism between TGF-β and BMP pathways: Implications for cancer progression

The transforming growth factor β (TGF-β) superfamily participates in tumour proliferation, apoptosis, differentiation, migration, invasion, immune evasion and extracellular matrix remodelling. Genetic deficiency in distinct components of TGF-β and BMP-induced signalling pathways or their excessive activation has been reported to regulate the development and progression of some cancers. As more in-depth studies about this superfamily have been conducted, more evidence suggests that the TGF-β and BMP pathways play an opposing role. The cross-talk of these 2 pathways has been widely studied in kidney disease and bone formation, and the opposing effects have also been observed in some cancers. However, the antagonistic mechanisms are still insufficiently investigated in cancer. In this review, we aim to display more evidences and possible mechanisms accounting for the antagonism between these 2 pathways, which might provide some clues for further study in cancer.

•

Describe the basics of TGF-β and BMP signalling

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Summarize the potential mechanisms accounting for the antagonism between TGF-β and BMP pathways

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Provide some evidence about the antagonistic effects between pathways observed in some cancers

POH1 contributes to hyperactivation of TGF-β signaling and facilitates hepatocellular carcinoma metastasis through deubiquitinating TGF-β receptors and caveolin-1

Background

Hyper-activation of TGF-β signaling is critically involved in progression of hepatocellular carcinoma (HCC). However, the events that contribute to the dysregulation of TGF-β pathway in HCC, especially at the post-translational level, are not well understood.

Methods

Associations of deubiquitinase POH1 with TGF-β signaling activity and the outcomes of HCC patients were examined by data mining of online HCC datasets, immunohistochemistry analyses using human HCC specimens, spearman correlation and survival analyses. The effects of POH1 on the ubiquitination and stability of the TGF-β receptors (TGFBR1 and TGFBR2) and the activation of downstream effectors were tested by western blotting. Primary mouse liver tissues from polyinosinic:polycytidylic acid (poly I:C)- treated Mx-Cre+, poh1^f/f mice and control mice were used to detect the TGF-β receptors. The metastatic-related capabilities of HCC cells were studied in vitro and in mice.

Findings

Here we show that POH1 is a critical regulator of TGF-β signaling and promotes tumor metastasis. Integrative analyses of HCC subgroups classified with unsupervised transcriptome clustering of the TGF-β response, metastatic potential and outcomes, reveal that POH1 expression positively correlates with activities of TGF-β signaling in tumors and with malignant disease progression. Functionally, POH1 intensifies TGF-β signaling delivery and, as a consequence, promotes HCC cell metastatic properties both in vitro and in vivo. The expression of the TGF-β receptors was severely downregulated in POH1-deficient mouse hepatocytes. Mechanistically, POH1 deubiquitinates the TGF-β receptors and CAV1, therefore negatively regulates lysosome pathway-mediated turnover of TGF-β receptors.

Conclusion

Our study highlights the pathological significance of aberrantly expressed POH1 in TGF-β signaling hyperactivation and aggressive progression in HCC.

PDZK1-interacting protein 1 (PDZK1IP1) traps Smad4 protein and suppresses transforming growth factor-β (TGF-β) signaling

Transforming growth factor (TGF)-β signaling in humans is stringently regulated to prevent excessive TGF-β signaling. In tumors, TGF-β signaling can both negatively and positively regulate tumorigenesis dependent on tumor type, but the reason for these opposite effects is unclear. TGF-β signaling is mainly mediated via the Smad-dependent pathway, and herein we found that PDZK1-interacting protein 1 (PDZK1IP1) interacts with Smad4. PDZK1IP1 inhibited both the TGF-β and the bone morphogenetic protein (BMP) pathways without affecting receptor-regulated Smad (R-Smad) phosphorylation. Rather than targeting R-Smad phosphorylation, PDZK1IP1 could interfere with TGF-β- and BMP-induced R-Smad/Smad4 complex formation. Of note, PDZK1IP1 retained Smad4 in the cytoplasm of TGF-β-stimulated cells. To pinpoint PDZK1IP1's functional domain, we created several PDZK1IP1 variants and found that its middle region, from Phe⁴⁰ to Ala⁴⁹, plays a key role in its Smad4-regulating activity. PDZK1IP1 knockdown enhanced the expression of the TGF-β target genes Smad7 and prostate transmembrane protein androgen-induced (TMEPAI) upon TGF-β stimulation. In contrast, PDZK1IP1 overexpression suppressed TGF-β-induced reporter activities, cell migration, and cell growth inhibition. In a xenograft tumor model in which TGF-β was previously shown to elicit tumor-promoting effects, PDZK1IP1 gain of function decreased tumor size and increased survival rates. Taken together, these findings indicate that PDZK1IP1 interacts with Smad4 and thereby suppresses the TGF-β signaling pathway.

TGF-β-induced alternative splicing of TAK1 promotes EMT and drug resistance

Transforming growth factor-β (TGF-β) is major inducer of epithelial to mesenchymal transition (EMT), which associates with cancer cell metastasis and resistance to chemotherapy and targeted drugs, through both transcriptional and non-transcriptional mechanisms. We previously reported that in cancer cells, heightened mitogenic signaling allows TGF-β-activated Smad3 to interact with poly(RC) binding protein 1 (PCBP1) and together they regulate many alternative splicing events that favors expression of protein isoforms essential for EMT, cytoskeletal rearrangement, and adherens junction signaling. Here, we show that the exclusion of TGF-β-activated kinase 1 (TAK1) variable exon 12 requires another RNA-binding protein, Fox-1 homolog 2 (Rbfox2), which binds intronic sequences in front of exon 12 independently of the Smad3-PCBP1 complex. Functionally, exon 12-excluded TAK1∆E12 and full length TAK1FL are distinct. The short isoform TAK1∆E12 is constitutively active and supports TGF-β-induced EMT and nuclear factor kappa B (NF-κB) signaling, whereas the full-length isoform TAK1FL promotes TGF-β-induced apoptosis. These observations offer a harmonious explanation for how a single TAK1 kinase can mediate the opposing responses of cell survival and apoptosis in response to TGF-β. They also reveal a propensity of the alternatively spliced TAK1 isoform TAK1∆E12 to cause drug resistance due to its activity in supporting EMT and NF-κB survival signaling.