Intertwining of Activin A and TGFβ Signaling: Dual Roles in Cancer Progression and Cancer Cell Invasion

Dysregulation of RUNX2/Activin-A Axis upon miR-376c Downregulation Promotes Lymph Node Metastasis in Head and Neck Squamous Cell Carcinoma

Epigenetic correlates of the head and neck cancer may illuminate its pathogenic roots. Through a gene set enrichment analysis, we found that the oncogenic transcription factor RUNX2 is widely upregulated in the head and neck squamous cell carcinoma (HNSCC) with lymph node metastasis, where it also predicts poor prognosis in patients with HNSCC. Enforced expression of ectopic RUNX2 promoted the metastatic capabilities of HNSCC, whereas RUNX2 silencing inhibited these features. Mechanistic investigations showed that manipulating levels of activin A (INHBA) could rescue or compromise the RUNX2-mediated metastatic capabilities of HNSCC cells. Furthermore, we found that miR-376c-3p encoded within the 3'-untranslated region of RUNX2 played a pivotal role in regulating RUNX2 expression in highly metastatic HNSCC cells, where it was downregulated commonly. Restoring miR-376c expression in this setting suppressed expression of RUNX2/INHBA axis along with metastatic capability. Clinically, we observed an inverse relationship between miR-376c-3p expression and the RUNX2/INHBA axis in HNSCC specimens. In summary, our results defined a novel pathway in which dysregulation of the RUNX2/INHBA axis due to miR-376c downregulation fosters lymph node metastasis in HNSCC. Cancer Res; 76(24); 7140-50. ©2016 AACR.

The Expression of Human Cytomegalovirus MicroRNA MiR-UL148D during Latent Infection in Primary Myeloid Cells Inhibits Activin A-triggered Secretion of IL-6

The successful establishment and maintenance of human cytomegalovirus (HCMV) latency is dependent on the expression of a subset of viral genes. Whilst the exact spectrum and functions of these genes are far from clear, inroads have been made for protein-coding genes. In contrast, little is known about the expression of non-coding RNAs. Here we show that HCMV encoded miRNAs are expressed de novo during latent infection of primary myeloid cells. Furthermore, we demonstrate that miR-UL148D, one of the most highly expressed viral miRNAs during latent infection, directly targets the cellular receptor ACVR1B of the activin signalling axis. Consistent with this, we observed upregulation of ACVR1B expression during latent infection with a miR-UL148D deletion virus (ΔmiR-UL148D). Importantly, we observed that monocytes latently infected with ΔmiR-UL148D are more responsive to activin A stimulation, as demonstrated by their increased secretion of IL-6. Collectively, our data indicates miR-UL148D inhibits ACVR1B expression in latently infected cells to limit proinflammatory cytokine secretion, perhaps as an immune evasion strategy or to postpone cytokine-induced reactivation until conditions are more favourable. This is the first demonstration of an HCMV miRNA function during latency in primary myeloid cells, implicating that small RNA species may contribute significantly to latent infection.

SYNJ2BP inhibits tumor growth and metastasis by activating DLL4 pathway in hepatocellular carcinoma

BACKGROUND

Synaptojanin 2 Binding Protein (SYNJ2BP) is essential to cell proliferation. Previous studies show that SYNJ2BP participates in sprouting angiogenesis, which plays an important part in several abnormal conditions including cancer. However, the activity of SYNJ2BP in hepatocellular carcinoma (HCC) has not been elucidated yet.

METHODS

Firstly, real-time PCR and western blotting (WB) were adopted to evaluate SYNJ2BP expressions in HCC tissues and HCC cell lines. Secondly, we did follow-up and prognostic study to explore the association of SYNJ2BP expression and HCC patients prognosis. Thirdly, we induced or silenced SYNJ2BP expression on selected HCC cell lines and explored the function of SYNJ2BP in vitro and in vivo. Lastly, we conducted Cignal Finder Cancer 10-Pathway Reporter Array in combination with loss- and gain-of-function assay to investigate potential mechanisms.

RESULTS

Through various techniques we found that SYNJ2BP was decreased in HCC tissues and HCC cell lines. The subsequent analysis showed that low expression of SYNJ2BP was associated with tumor size, tumor nodule number, vascular invasion, TNM stage and BCLC stage, and was an independent risk factor for survival of HCC. Later, the in vitro experiments demonstrated that SYNJ2BP inhibited HCC cells invasion, migration and proliferation, also the in vivo testing revealed that SYNJ2BP inhibited tumor growth and metastasis. Finally, we also uncovered that SYNJ2BP inhibited HCC growth and metastasis through activating DLL4-mediated Notch signaling pathway.

CONCLUSIONS

Collectively, our data provide evidence that SYNJ2BP may act as a tumor suppressor during HCC development and could serve as a potential therapeutic target.

BAFF and APRIL from Activin A-Treated Dendritic Cells Upregulate the Antitumor Efficacy of Dendritic Cells In Vivo

The members of the TGFβ superfamily play a key role in regulating developmental and homeostasis programs by controlling differentiation, proliferation, polarization, and survival of different cell types. Although the role of TGFβ1 in inflammation and immunity is well evident, the contribution of other TGFβ family cytokines in the modulation of the antitumor immune response remains less documented. Here we show that activin A triggers SMAD2 and ERK1/2 pathways in dendritic cells (DC) expressing type I and II activin receptors, and upregulates production of the TNFα family cytokines BAFF (TALL-1, TNFSF13B) and APRIL (TALL-2, TNFSF13A), which is blocked by SMAD2 and ERK1/2 inhibitors, respectively. BAFF and APRIL derived from activin A-treated DCs upregulate proliferation and survival of T cells expressing the corresponding receptors, BAFF-R and TACI. In vivo, activin A-stimulated DCs demonstrate a significantly increased ability to induce tumor-specific CTLs and inhibit the growth of melanoma and lung carcinoma, which relies on DC-derived BAFF and APRIL, as knockdown of the BAFF and APRIL gene expression in activin A-treated DCs blocks augmentation of their antitumor potential. Although systemic administration of activin A, BAFF, or APRIL for the therapeutic purposes is not likely due to the pluripotent effects on malignant and nonmalignant cells, our data open a novel opportunity for improving the efficacy of DC vaccines. In fact, a significant augmentation of the antitumor activity of DC pretreated with activin A and the proven role of DC-derived BAFF and APRIL in the induction of antitumor immunity in vivo support this direction. Cancer Res; 76(17); 4959-69. ©2016 AACR.

An integrated cell line-based discovery strategy identified follistatin and kallikrein 6 as serum biomarker candidates of breast carcinoma

Secreted proteins constitute a relevant source of putative cancer biomarkers. Here, we compared the secretome of a series of four genetically-related breast cancer cell lines as a model of aggressiveness using quantitative mass spectrometry. 537 proteins (59.5% of the total identified proteins) predicted to be released or shed from cells were identified. Using a scoring system based on i) iTRAQ value, ii) breast cancer tissue mRNA expression levels, and iii) immunohistochemical staining (public database), a short list of 10 candidate proteins was selected. Using specific ELISA assays, the expression level of the top five proteins was measured in a verification set of 56 patients. The four significantly differentially expressed proteins were then validated in a second independent set of 353 patients. Finally, follistatin (FST) and kallikrein 6 (KLK6) in serum were significantly higher (p-value < 0.0001) in invasive breast cancer patients compared with non-cancerous controls. Using specific cut-off values, FST distinguished breast cancer samples from healthy controls with a sensitivity of 65% and an accuracy of 68%, whereas KLK6 achieved a sensitivity of 55% and an accuracy of 61%. Therefore, we concluded that FST and KLK6 may have significance in breast cancer detection.

BIOLOGICAL SIGNIFICANCE

Discovery of new serum biomarkers that exhibit increased sensitivity and specificity compared to current biomarkers appears to be an essential field of research in cancer. Most biological markers show insufficient diagnostic sensitivity for early breast cancer detection and, for the majority of them, their concentrations are elevated only in metastatic forms of the disease. It is therefore essential to identify clinically reliable biomarkers and develop effective approaches for cancer diagnosis. One promising approach in this field is the study of secreted proteins through proteomic analysis of in vitro progression breast cancer models. Here we have shown that FST and KLK6 are elevated in breast cancer patient serum compared to healthy controls. We expect that our discovery strategy will help to identify cancer-specific and body-fluid-accessible biomarkers.

Increased expression of the long noncoding RNA CRNDE-h indicates a poor prognosis in colorectal cancer, and is positively correlated with IRX5 mRNA expression

Background

The long noncoding RNA (lncRNA) colorectal neoplasia differentially expressed – h (CRNDE-h) plays important roles in the early stages of human development and cancer progression. We investigated the expression and clinical significance of lncRNA CRNDE-h in colorectal cancer (CRC).

Methods

The expression level of lncRNA CRNDE-h was analyzed in 142 CRC tissues and 142 paired adjacent nontumorous tissues, along with 21 inflammatory bowel diseases, 69 hyperplastic polyp, and 73 colorectal adenoma samples, using quantitative real-time polymerase chain reaction. The association between lncRNA CRNDE-h, and Iroquois homeobox protein 5 (IRX5) mRNA was examined in the same 142 CRC tissues.

Results

We found that lncRNA CRNDE-h level was elevated in the CRC and adenoma groups compared with the other groups (all at P<0.001). In CRC, upregulation of lncRNA CRNDE-h was significantly correlated with large tumor size, positive regional lymph node metastasis, and distant metastasis (all at P<0.05). Area under the curve for lncRNA CRNDE-h showed diagnostic capability for distinguishing CRC from other groups. Patients with CRC with high lncRNA CRNDE-h expression level had poorer overall survival than those with low lncRNA CRNDE-h expression (log-rank test, P<0.001). Further, multivariable Cox regression analysis suggested that increased expression of lncRNA CRNDE-h was an independent prognostic indicator for CRC (hazard ratio [HR]=2.173; 95% confidence interval [CI], 1.282–3.684, P=0.004). Furthermore, lncRNA CRNDE-h expression was positively correlated with IRX5 mRNA in CRC tissues.

Conclusions

Our data offers convincing evidence for the first time that lncRNA CRNDE-h is associated with adverse clinical characteristics and poor prognosis, which suggests that it might play an important role in CRC development and progression and might have clinical potential as a useful prognostic predictor.

Activins in reproductive biology and beyond

BACKGROUND

Activins are members of the pleiotrophic family of the transforming growth factor-beta (TGF-β) superfamily of cytokines, initially isolated for their capacity to induce the release of FSH from pituitary extracts. Subsequent research has demonstrated that activins are involved in multiple biological functions including the control of inflammation, fibrosis, developmental biology and tumourigenesis. This review summarizes the current knowledge on the roles of activin in reproductive and developmental biology. It also discusses interesting advances in the field of modulating the bioactivity of activins as a therapeutic target, which would undoubtedly be beneficial for patients with reproductive pathology.

METHODS

A comprehensive literature search was carried out using PUBMED and Google Scholar databases to identify studies in the English language which have contributed to the advancement of the field of activin biology, since its initial isolation in 1987 until July 2015. 'Activin', 'testis', 'ovary', 'embryonic development' and 'therapeutic targets' were used as the keywords in combination with other search phrases relevant to the topic of activin biology.

RESULTS

Activins, which are dimers of inhibin β subunits, act via a classical TGF-β signalling pathway. The bioactivity of activin is regulated by two endogenous inhibitors, inhibin and follistatin. Activin is a major regulator of testicular and ovarian development. In the ovary, activin A promotes oocyte maturation and regulates granulosa cell steroidogenesis. It is also essential in endometrial repair following menstruation, decidualization and maintaining pregnancy. Dysregulation of the activin-follistatin-inhibin system leads to disorders of female reproduction and pregnancy, including polycystic ovary syndrome, ectopic pregnancy, miscarriage, fetal growth restriction, gestational diabetes, pre-eclampsia and pre-term birth. Moreover, a rise in serum activin A, accompanied by elevated FSH, is characteristic of female reproductive aging. In the male, activin A is an autocrine and paracrine modulator of germ cell development and Sertoli cell proliferation. Disruption of normal activin signalling is characteristic of many tumours affecting reproductive organs, including endometrial carcinoma, cervical cancer, testicular and ovarian cancer as well as prostate cancer. While activin A and B aid the progression of many tumours of the reproductive organs, activin C acts as a tumour suppressor. Activins are important in embryonic induction, morphogenesis of branched glandular organs, development of limbs and nervous system, craniofacial and dental development and morphogenesis of the Wolffian duct.

CONCLUSIONS

The field of activin biology has advanced considerably since its initial discovery as an FSH stimulating agent. Now, activin is well known as a growth factor and cytokine that regulates many aspects of reproductive biology, developmental biology and also inflammation and immunological mechanisms. Current research provides evidence for novel roles of activins in maintaining the structure and function of reproductive and other organ systems. The fact that activin A is elevated both locally as well as systemically in major disorders of the reproductive system makes it an important biomarker. Given the established role of activin A as a pro-inflammatory and pro-fibrotic agent, studies of its involvement in disorders of reproduction resulting from these processes should be examined. Follistatin, as a key regulator of the biological actions of activin, should be evaluated as a therapeutic agent in conditions where activin A overexpression is established as a contributing factor.

Ionizing radiation induces a motile phenotype in human carcinoma cells in vitro through hyperactivation of the TGF-beta signaling pathway

Radiotherapy, a major treatment modality against cancer, can lead to secondary malignancies but it is uncertain as to whether tumor cells that survive ionizing radiation (IR) treatment undergo epithelial-mesenchymal transition (EMT) and eventually become invasive or metastatic. Here, we have tested the hypothesis that the application of IR (10 MeV photon beams, 2-20 Gy) to lung and pancreatic carcinoma cells induces a migratory/invasive phenotype in these cells by hyperactivation of TGF-β and/or activin signaling. In accordance with this assumption, IR induced gene expression patterns and migratory responses consistent with an EMT phenotype. Moreover, in A549 cells, IR triggered the synthesis and secretion of both TGF-β1 and activin A as well as activation of intracellular TGF-β/activin signaling as evidenced by Smad phosphorylation and transcriptional activation of a TGF-β-responsive reporter gene. These responses were sensitive to SB431542, an inhibitor of type I receptors for TGF-β and activin. Likewise, specific antibody-mediated neutralization of soluble TGF-β, or dominant-negative inhibition of the TGF-β receptors, but not the activin type I receptor, alleviated IR-induced cell migration. Moreover, the TGF-β-specific approaches also blocked IR-dependent TGF-β1 secretion, Smad phosphorylation, and reporter gene activity, collectively indicating that autocrine production of TGF-β(s) and subsequent activation of TGF-β rather than activin signaling drives these changes. IR strongly sensitized cells to further increase their migration in response to recombinant TGF-β1 and this was accompanied by upregulation of TGF-β receptor expression. Our data raise the possibility that hyperactivation of TGF-β signaling during radiotherapy contributes to EMT-associated changes like metastasis, cancer stem cell formation and chemoresistance of tumor cells.

Activin and TGFβ use diverging mitogenic signaling in advanced colon cancer

Background

Understanding cell signaling pathways that contribute to metastatic colon cancer is critical to risk stratification in the era of personalized therapeutics. Here, we dissect the unique involvement of mitogenic pathways in a TGFβ or activin-induced metastatic phenotype of colon cancer.

Method

Mitogenic signaling/growth factor receptor status and p21 localization were correlated in primary colon cancers and intestinal tumors from either AOM/DSS treated ACVR2A (activin receptor 2) −/− or wild type mice. Colon cancer cell lines (+/− SMAD4) were interrogated for ligand-induced PI3K and MEK/ERK pathway activation and downstream protein/phospho-isoform expression/association after knockdown and pharmacologic inhibition of pathway members. EMT was assessed using epithelial/mesenchymal markers and migration assays.

Results

In primary colon cancers, loss of nuclear p21 correlated with upstream activation of activin/PI3K while nuclear p21 expression was associated with TGFβ/MEK/ERK pathway activation. Activin, but not TGFβ, led to PI3K activation via interaction of ACVR1B and p85 independent of SMAD4, resulting in p21 downregulation. In contrast, TGFβ increased p21 via MEK/ERK pathway through a SMAD4-dependent mechanism. While activin induced EMT via PI3K, TGFβ induced EMT via MEK/ERK activation. In vivo, loss of ACVR2A resulted in loss of pAkt, consistent with activin-dependent PI3K signaling.

Conclusion

Although activin and TGFβ share growth suppressive SMAD signaling in colon cancer, they diverge in their SMAD4-independent pro-migratory signaling utilizing distinct mitogenic signaling pathways that affect EMT. p21 localization in colon cancer may determine a dominant activin versus TGFβ ligand signaling phenotype warranting further validation as a therapeutic biomarker prior to targeting TGFβ family receptors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0456-4) contains supplementary material, which is available to authorized users.

Overexpression of transforming growth factor type III receptor restores TGF-β1 sensitivity in human tongue squamous cell carcinoma cells

Down-expression of transforming growth factor type III receptor (TβRIII) in tong squamous cell carcinoma clinical specimens. Overexpression of TβRIII restores TGF-β1 sensitivity in human CAL-27 tong squamous cell carcinoma cell. TβRIII over-expression affects TGF-β1-mediated activation of p38 and CDKN2b in CAL-27 cells.

The transforming growth factor type III receptor (TβRIII), also known as β-glycan, is a multi-functional sensor that regulates growth, migration and apoptosis in most cancer cells. We hereby investigated the expression of TβRIII in clinical specimens of tongue squamous cell carcinoma (TSCC) and the underlying mechanism that TβRIII inhibits the growth of CAL-27 human oral squamous cells. The TSCC tissues showed a significant decrease in TβRIII protein expression as detected by immunohistochemistry (IHC) and western blot analysis. Transfection of TβRIII-containing plasmid DNA dramatically promoted TGF-β1 (10 ng/ml)-induced decrease in cell viability, apoptosis and cell arrest at the G₀-/G₁-phase. Moreover, transient overexpression of TβRIII enhanced the TGF-β1-induced cyclin-dependent kinase inhibitor 2b (CDKN2b) and p38 protein activity, but did not affect the activities of extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase 1/2 (JNK1/2) in CAL-27 cells. These results suggest overexpression of TβRIII receptor restored TGF-β1 sensitivity in CAL-27 cells, which may provide some new insights on exploiting this molecule therapeutically.