Phosphorylation status at Smad3 linker region modulates transforming growth factor-ß-induced epithelial-mesenchymal transition and cancer progression.

Smad3, a major transcription factor in transforming growth factor-ß (TGF-ß) signaling, plays critical roles in both tumor-suppressive and pro-oncogenic functions. Upon TGF-ß stimulation, the C-terminal tail of Smad3 undergoes phosphorylation that is essential for canonical TGF-ß signaling. The Smad3 linker region contains serine/threonine phosphorylation sites and can be phosphorylated by intracellular kinases, such as the MAPK family, cyclin-dependent kinase (CDK) family and glycogen synthase kinase-3ß (GSK-3ß). Previous reports based on cell culture studies by us and others showed that mutation of Smad3 linker phosphorylation sites dramatically intensifies TGF-ß responses as well as growth-inhibitory function and epithelial-mesenchymal transition (EMT), suggesting that Smad3 linker phosphorylation suppresses TGF-ß transcriptional activities. However, recent discoveries of Smad3-interacting molecules that preferentially bind phosphorylated Smad3 linker serine/threonine residues have shown a multitude of signal transductions that either enhance or suppress TGF-ß responses associated with Smad3 turnover or cancer progression. This review aims at providing new insight into the perplexing mechanisms of TGF-ß signaling affected by Smad3 linker phosphorylation and further attempts to gain insight into elimination and protection of TGF-ß-mediated oncogenic and growth-suppressive signals, respectively.

Galangin enhances TGF-ß1-mediated growth inhibition by suppressing phosphorylation of threonine 179 residue in Smad3 linker region.

Smad3 linker phosphorylation is a candidate target for several kinases that play important roles in cancer cell initiation, proliferation and progression. Also, Smad3 is an essential intracellular mediator of TGF-ß1-induced transcriptional responses during carcinogenesis. Therefore, it is highly advantageous to identify and develop inhibitors targeting Smad3 linker phosphorylation for the treatment of cancers. Galangin (3,5,7-trihydroxyflavone) has been known to be an active flavonoid showing a cytotoxic effect on several cancer cells. However, the mechanism of action of galangin in various cancers remains unclear, and there has been no report concerning regulation of Smad3 phosphorylation by galangin. In the present study, we show that galangin significantly induced apoptosis and inhibited cell proliferation in the presence of TGF-ß1 in both human prostate and pancreatic cancer cell lines. Particularly, galangin effectively inhibits phosphorylation of the Thr-179 site at Smad3 linker region through suppression of CDK4 phosphorylation. Thus, galangin can be a promising candidate as a selective inhibitor to suppress phosphorylation of Smad3 linker region.

Novel oral transforming growth factor-ß signaling inhibitor EW-7197 eradicates CML-initiating cells.

Recent strategies for treating CML patients have focused on investigating new combinations of tyrosine kinase inhibitors (TKIs) as well as identifying novel translational research agents that can eradicate CML leukemia-initiating cells (CML-LICs). However, little is known about the therapeutic benefits such CML-LIC targeting therapies might bring to CML patients. In this study, we investigated the therapeutic potential of EW-7197, an orally bioavailable transforming growth factor-ß signaling inhibitor which has recently been approved as an Investigational New Drug (NIH, USA), to suppress CML-LICs in vivo. Compared to TKI treatment alone, administration of TKI plus EW-7197 to CML-affected mice significantly delayed disease relapse and prolonged survival. Notably, combined treatment with EW-7197 plus TKI was effective in eliminating CML-LICs even if they expressed the TKI-resistant T315I mutant BCR-ABL1 oncogene. Collectively, these results indicate that EW-7197 may be a promising candidate for a new therapeutic that can greatly benefit CML patients by working in combination with TKIs to eradicate CML-LICs.

Tm4sf19 deficiency inhibits osteoclast multinucleation and prevents bone loss.

BACKGROUND: Multinucleation is a hallmark of osteoclast formation and has a unique ability to resorb bone matrix. During osteoclast differentiation, the cytoskeleton reorganization results in the generation of actin belts and eventual bone resorption. Tetraspanins are involved in adhesion, migration and fusion in various cells. However, its function in osteoclast is still unclear. In this study, we identified Tm4sf19, a member of the tetraspanin family, as a regulator of osteoclast function. MATERIALS AND METHODS: We investigate the effect of Tm4sf19 deficiency on osteoclast differentiation using bone marrow-derived macrophages obtained from wild type (WT), Tm4sf19 knockout (KO) and Tm4sf19 LELΔ mice lacking the large extracellular loop (LEL). We analyzed bone mass of young and aged WT, KO and LELΔ mice by µCT analysis. The effects of Tm4sf19 LEL-Fc fusion protein were accessed in osteoclast differentiation and osteoporosis animal model. RESULTS: We found that deficiency of Tm4sf19 inhibited osteoclast function and LEL of Tm4sf19 was responsible for its function in osteoclasts in vitro. KO and LELΔ mice exhibited higher trabecular bone mass compared to WT mice. We found that Tm4sf19 interacts with integrin αvß3 through LEL, and that this binding is important for cytoskeletal rearrangements in osteoclast by regulating signaling downstream of integrin αvß3. Treatment with LEL-Fc fusion protein inhibited osteoclast function in vitro and administration of LEL-Fc prevented bone loss in an osteoporosis mouse model in vivo. CONCLUSION: We suggest that Tm4sf19 regulates osteoclast function and that LEL-Fc may be a promising drug to target bone destructive diseases caused by osteoclast hyper-differentiation.

Combination treatment of T1-44, a PRMT5 inhibitor with Vactosertib, an inhibitor of TGF-ß signaling, inhibits invasion and prolongs survival in a mouse model of pancreatic tumors.

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal type of cancer and the third leading cause of cancer death with the lowest 5-year survival rate. Heterogeneity, difficulty in diagnosis, and rapid metastatic progression are the causes of high mortality in pancreatic cancer. Recent studies have shown that Protein arginine methyltransferase 5 (PRMT5) is overexpressed in pancreatic cancers, and these patients have a worse prognosis. Recently, PRMT5 as an anti-cancer target has gained considerable interest. In this study, we investigated whether inhibition of PRMT5 activity was synergistic with blockade of TGF-ß1 signaling, which plays an important role in the construction of the desmoplastic matrix in pancreatic cancer and induces therapeutic vulnerability. Compared with T1-44, a selective inhibitor of PRMT5 activity, the combination of T1-44 with the TGF-ß1 signaling inhibitor Vactosertib significantly reduced tumor size and surrounding tissue invasion and significantly improved long-term survival. RNA sequencing analysis of mouse tumors revealed that the combination of T1-44 and Vactosertib significantly altered the expression of genes involved in cancer progression, such as cell migration, extracellular matrix, and apoptotic processes. In particular, the expression of Btg2, known as a tumor suppressor factor in various cancers, was markedly induced by combination treatment. Ectopic overexpression of Btg2 inhibited the EMT response, blocking cell migration, and promoted cancer cell death. These data demonstrate that the combination therapy of T1-44 with Vactosertib is synergistic for pancreatic cancer, suggesting that this novel combination therapy has value in the treatment strategy of patients with pancreatic cancer.

Smad3 linker phosphorylation attenuates Smad3 transcriptional activity and TGF-ß1/Smad3-induced epithelial-mesenchymal transition in renal epithelial cells.

Transforming growth factor-ß1 (TGF-ß1) has a distinct role in renal fibrosis associated with epithelial-mesenchymal transition (EMT) of the renal tubules and synthesis of extracellular matrix. Smad3 plays an essential role in fibrosis initiated by EMT. Phosphorylation of Smad3 in the C-terminal SSXS motif by type I TGF-ß receptor kinase is essential for mediating TGF-ß response. Smad3 activity is also regulated by phosphorylation in the linker region. However, the functional role of Smad3 linker phosphorylation is not well characterized. We now show that Smad3 EPSM mutant, which mutated the four phosphorylation sites in the linker region, markedly enhanced TGF-ß1-induced EMT of Smad3-deficient primary renal tubular epithelial cells, whereas Smad3 3S-A mutant, which mutated the C-terminal phosphorylation sites, was unable to induce EMT in response to TGF-ß1. Furthermore, immunoblotting and RT-PCR analysis showed a marked induction of fibrogenic gene expression with a significant reduction in E-cadherin in HK2 human renal epithelial cells expressing Smad3 EPSM. TGF-ß1 could not induce the expression of α-SMA, vimentin, fibronectin and PAI-1 or reduce the expression of E-cadherin in HK2 cells expressing Smad3 3S-A in response to TGF-ß1. Our results suggest that Smad3 linker phosphorylation has a negative regulatory role on Smad3 transcriptional activity and TGF-ß1/Smad3-induced renal EMT. Elucidation of mechanism regulating the Smad3 linker phosphorylation can provide a new strategy to control renal fibrosis.

Degradation of DRAK1 by CUL3/SPOP E3 Ubiquitin ligase promotes tumor growth of paclitaxel-resistant cervical cancer cells.

Despite favorable responses to initial chemotherapy, drug resistance is a major cause limiting chemotherapeutic efficacy in many advanced cancers. However, mechanisms that drive drug-specific resistance in chemotherapy for patients with advanced cancers are still unclear. Here, we report a unique role of death-associated protein kinase-related apoptosis-inducing kinase 1 (DRAK1) associated with paclitaxel resistance in cervical cancer cells. Interestingly, DRAK1 protein level was markedly decreased in paclitaxel-resistant cervical cancer cells without affecting its mRNA expression, which resulted in an increase in tumor necrosis factor receptor-associated factor 6 (TRAF6) expression, as well as an activation of TRAF6-mediated nuclear factor-kappa B (NF-κB) signaling cascade, thereby promoting tumor progression. DRAK1 depletion markedly increased the chemotherapeutic IC50 values of paclitaxel in cervical cancer cells. Ectopic expression of DRAK1 inhibited growth of paclitaxel-resistant cervical cancer cells in vitro and in vivo. Furthermore, DRAK1 was markedly underexpressed in chemoresistant cervical cancer patient tissues compared with chemosensitive samples. We found that DRAK1 protein was destabilized through K48-linked polyubiquitination promoted by the Cullin scaffold protein 3 (CUL3) / speckle-type POZ (poxvirus and zinc finger protein) protein (SPOP) E3 ubiquitin ligase in paclitaxel-resistant cells. Collectively, these findings suggest that DRAK1 may serve as a potential predictive biomarker for overcoming paclitaxel resistance in cervical cancer.

ESRP1-regulated isoform switching of LRRFIP2 determines metastasis of gastric cancer.

Although accumulating evidence indicates that alternative splicing is aberrantly altered in many cancers, the functional mechanism remains to be elucidated. Here, we show that epithelial and mesenchymal isoform switches of leucine-rich repeat Fli-I-interacting protein 2 (LRRFIP2) regulated by epithelial splicing regulatory protein 1 (ESRP1) correlate with metastatic potential of gastric cancer cells. We found that expression of the splicing variants of LRRFIP2 was closely correlated with that of ESRP1. Surprisingly, ectopic expression of the mesenchymal isoform of LRRFIP2 (variant 3) dramatically increased liver metastasis of gastric cancer cells, whereas deletion of exon 7 of LRRFIP2 by the CRISPR/Cas9 system caused an isoform switch, leading to marked suppression of liver metastasis. Mechanistically, the epithelial LRRFIP2 isoform (variant 2) inhibited the oncogenic function of coactivator-associated arginine methyltransferase 1 (CARM1) through interaction. Taken together, our data reveals a mechanism of LRRFIP2 isoform switches in gastric cancer with important implication for cancer metastasis.

Metastasis Risk Assessment Using BAG2 Expression by Cancer-Associated Fibroblast and Tumor Cells in Patients with Breast Cancer.

Few studies have examined the role of BAG2 in malignancies. We investigated the prognostic value of BAG2-expression in cancer-associated fibroblasts (CAFs) and tumor cells in predicting metastasis-free survival in patients with breast cancer. Tissue-microarray was constructed using human breast cancer tissues obtained by surgical resection between 1992 and 2015. BAG2 expression was evaluated by immunohistochemistry in CAFs or the tumor cells. BAG2 expression in the CAFs and cytoplasm of tumor cells was classified as positive and negative, and low and high, respectively. BAG2-CAF was evaluated in 310 patients and was positive in 67 (21.6%) patients. Kaplan-Meier plots showed that distant metastasis-free survival (DMFS) was lesser in patients with BAG2(+) CAF than in patients with BAG2(-) CAF (p = 0.039). Additionally, we classified the 310 patients into two groups: 109 in either BAG2-high or BAG2(+) CAF and 201 in BAG2-low and BAG2(-) CAF. DMFS was significantly reduced in patients with either BAG2-high or BAG2(+) CAF than in the patients of the other group (p = 0.005). Multivariable analysis demonstrated that DMFS was prolonged in patients with BAG2(-) CAF or BAG2-low. Evaluation of BAG2 expression on both CAFs and tumor cells could help in determining the risk of metastasis in breast cancer.

Tetraarsenic hexoxide enhances generation of mitochondrial ROS to promote pyroptosis by inducing the activation of caspase-3/GSDME in triple-negative breast cancer cells.

Although tetraarsenic hexoxide is known to exert an anti-tumor effect by inducing apoptosis in various cancer cells, its effect on other forms of regulated cell death remains unclear. Here, we show that tetraarsenic hexoxide induces the pyroptotic cell death through activation of mitochondrial reactive oxygen species (ROS)-mediated caspase-3/gasdermin E (GSDME) pathway, thereby suppressing tumor growth and metastasis of triple-negative breast cancer (TNBC) cells. Interestingly, tetraarsenic hexoxide-treated TNBC cells exhibited specific pyroptotic characteristics, including cell swelling, balloon-like bubbling, and LDH releases through pore formation in the plasma membrane, eventually suppressing tumor formation and lung metastasis of TNBC cells. Mechanistically, tetraarsenic hexoxide markedly enhanced the production of mitochondrial ROS by inhibiting phosphorylation of mitochondrial STAT3, subsequently inducing caspase-3-dependent cleavage of GSDME, which consequently promoted pyroptotic cell death in TNBC cells. Collectively, our findings highlight tetraarsenic hexoxide-induced pyroptosis as a new therapeutic strategy that may inhibit cancer progression of TNBC cells.

Expression of TGF-beta signaling factors in invasive breast cancers: relationships with age at diagnosis and tumor characteristics.

The transforming growth factor beta (TGF-beta) pathway can play either a tumor-suppressing or a tumor-promoting role in human breast carcinogenesis. In order to determine whether expression of TGF-beta signaling factors varies by age at onset and breast tumor characteristics that have prognostic significance, we undertook a study of 623 women with invasive breast carcinoma enrolled in a population-based case-control study conducted in Poland from 2000 to 2003. TGF-beta signaling factors were analyzed by immunohistochemistry in tumor tissue microarrays. We found that most tumors expressed extracellular-TGF-beta1 (78%), TGF-beta2 (91%), TGF-beta3 (93%), TGF-betaR2 (72%), and phospho-SMAD2 (61%), whereas intracellular-TGF-beta1 was expressed in 32% of tumors. Expression of TGF-beta ligands (beta1, beta2, and beta3) was associated with prognostically favorable pathological features including small size, and low grade, and these associations were similar for ER-positive and negative tumors. On the contrary, expression of the receptor TGF-betaR2 was primarily associated with small tumor size among ER-negative tumors, while expression of the transcription factor phospho-SMAD2 was associated with positive nodal status among ER-negative tumors. The greater frequency of expression of phospho-SMAD2 in cancers associated with lymph node metastases is consistent with a pro-progression role for TGF-beta. In addition, expression of extracellular-TGF-beta1 (P = 0.005), TGF-betaR2 (P = 8.2E-11), and phospho-SMAD2 (P = 1.3E-8) was strongly associated with earlier age at onset, independent of ER status. Our data provide evidence that TGF-beta signaling patterns vary by age and pathologic features of prognostic significance including ER expression. These results warrant analysis in studies of clinical outcomes accounting for age, ER status and treatment.

The lysophospholipase D enzyme Gdpd3 is required to maintain chronic myelogenous leukaemia stem cells.

Although advanced lipidomics technology facilitates quantitation of intracellular lipid components, little is known about the regulation of lipid metabolism in cancer cells. Here, we show that disruption of the Gdpd3 gene encoding a lysophospholipase D enzyme significantly decreased self-renewal capacity in murine chronic myelogenous leukaemia (CML) stem cells in vivo. Sophisticated lipidomics analyses revealed that Gdpd3 deficiency reduced levels of certain lysophosphatidic acids (LPAs) and lipid mediators in CML cells. Loss of Gdpd3 also activated AKT/mTORC1 signalling and cell cycle progression while suppressing Foxo3a/ß-catenin interaction within CML stem cell nuclei. Strikingly, CML stem cells carrying a hypomorphic mutation of Lgr4/Gpr48, which encodes a leucine-rich repeat (LRR)-containing G-protein coupled receptor (GPCR) acting downstream of Gdpd3, displayed inadequate disease-initiating capacity in vivo. Our data showing that lysophospholipid metabolism is required for CML stem cell maintenance in vivo establish a new, biologically significant mechanism of cancer recurrence that is independent of oncogene addiction.

Inhibition of TGF-ß signalling in combination with nal-IRI plus 5-Fluorouracil/Leucovorin suppresses invasion and prolongs survival in pancreatic tumour mouse models.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies. TGF-ß is strongly expressed in both the epithelial and stromal compartments of PDAC, and dysregulation of TGF-ß signalling is a frequent molecular disturbance in PDAC progression and metastasis. In this study, we investigated whether blockade of TGF-ß signalling synergizes with nal-IRI/5-FU/LV, a chemotherapy regimen for malignant pancreatic cancer, in an orthotopic pancreatic tumour mouse model. Compared to nal-IRI/5-FU/LV treatment, combining nal-IRI/5-FU/LV with vactosertib, a TGF-ß signalling inhibitor, significantly improved long-term survival rates and effectively suppressed invasion to surrounding tissues. Through RNA-sequencing analysis, we identified that the combination treatment results in robust abrogation of tumour-promoting gene signatures and positive enrichment of tumour-suppressing and apoptotic gene signatures. Particularly, the expression of tumour-suppressing gene Ccdc80 was induced by vactosertib and further induced by vactosertib in combination with nal-IRI/5-FU/LV. Ectopic expression of CCDC80 suppressed migration and colony formation concomitant with decreased expression of epithelial-to-mesenchymal transition (EMT) markers in pancreatic cancer cells. Collectively, these results indicate that combination treatment of vactosertib with nal-IRI/5-FU/LV improves overall survival rates in a mouse model of pancreatic cancer by suppressing invasion through CCDC80. Therefore, combination therapy of nal-IRI/5-FU/LV with vactosertib could provide clinical benefits to pancreatic cancer patients.

Destablilization of TRAF6 by DRAK1 Suppresses Tumor Growth and Metastasis in Cervical Cancer Cells.

The adaptor protein TNF receptor-associated factor 6 (TRAF6) is a key mediator in inflammation. However, the molecular mechanisms controlling its activity and stability in cancer progression remain unclear. Here we show that death-associated protein kinase-related apoptosis-inducing kinase 1 (DRAK1) inhibits the proinflammatory signaling pathway by targeting TRAF6 for degradation, thereby suppressing inflammatory signaling-mediated tumor growth and metastasis in advanced cervical cancer cells. DRAK1 bound directly to the TRAF domain of TRAF6, preventing its autoubiquitination by interfering with homo-oligomerization, eventually leading to autophagy-mediated degradation of TRAF6. Depletion of DRAK1 in cervical cancer cells resulted in markedly increased levels of TRAF6 protein, promoting activation of the IL1ß signaling-associated pathway and proinflammatory cytokine production. DRAK1 was specifically underexpressed in metastatic cervical cancers and inversely correlated with TRAF6 expression in mouse xenograft model tumor tissues and human cervical tumor tissues. Collectively, our findings highlight DRAK1 as a novel antagonist of inflammation targeting TRAF6 for degradation that limits inflammatory signaling-mediated progression of advanced cervical cancer. SIGNIFICANCE: Serine/threonine kinase DRAK1 serves a unique role as a novel negative regulator of the inflammatory signaling mediator TRAF6 in cervical cancer progression.

Smad3 is key to TGF-beta-mediated epithelial-to-mesenchymal transition, fibrosis, tumor suppression and metastasis.

Smads2 and 3 transduce signals of TGF-beta from the cell surface to the nucleus. We used mice with a targeted deletion of Smad3 to study the specific contributions of this signaling pathway to pathogenic effects of TGF-beta. Focusing on models involving epithelial-to-mesenchymal transition (EMT), including injury to the lens and retina of the eye and to the kidney, we have found that loss of Smad3 blocks EMT and attenuates development of fibrotic sequelae. Smad3 also plays a critical role in both the tumor suppressor and pro-metastatic effects of TGF-beta in carcinogenesis. These observations suggest that development of small molecule inhibitors of Smad3 might have clinical application in treatment of fibrotic diseases as well as late stage cancers.

Transforming growth factor-beta can suppress tumorigenesis through effects on the putative cancer stem or early progenitor cell and committed progeny in a breast cancer xenograft model.

The transforming growth factor-beta (TGF-beta) pathway has tumor-suppressor activity in many epithelial tissues. Because TGF-beta is a potent inhibitor of epithelial cell proliferation, it has been widely assumed that this property underlies the tumor-suppressor effect. Here, we have used a xenograft model of breast cancer to show that endogenous TGF-beta has the potential to suppress tumorigenesis through a novel mechanism, involving effects at two distinct levels in the hierarchy of cellular progeny that make up the epithelial component of the tumor. First, TGF-beta reduces the size of the putative cancer stem or early progenitor cell population, and second it promotes differentiation of a more committed, but highly proliferative, progenitor cell population to an intrinsically less proliferative state. We further show that reduced expression of the type II TGF-beta receptor correlates with loss of luminal differentiation in a clinical breast cancer cohort, suggesting that this mechanism may be clinically relevant. At a molecular level, the induction of differentiation by TGF-beta involves down-regulation of Id1, and forced overexpression of Id1 can promote tumorigenesis despite persistence of the antiproliferative effect of TGF-beta. These data suggest new roles for the TGF-beta pathway in regulating tumor cell dynamics that are independent of direct effects on proliferation.

High A20 expression negatively impacts survival in patients with breast cancer.

BACKGROUND: A20 protein has ubiquitin-editing activities and acts as a key regulator of inflammation and immunity. Previously, our group showed that A20 promotes tumor metastasis through multi-monoubiquitylation of SNAIL1 in basal-like breast cancer. Here, we investigated survival outcomes in patients with breast cancer according to A20 expression. PATIENTS AND METHODS: We retrospectively collected tumor samples from patients with breast cancer. Immunohistochemistry (IHC) with an A20-specific antibody was performed, and survival outcomes were analyzed. RESULTS: A20 expression was evaluated in 442 patients. High A20 expression was associated with advanced anatomical stage and young age. High A20 expression showed significantly inferior recurrence-free-survival and overall-survival (P<0.001 and P<0.001, respectively). Multivariate analysis showed that A20 was an independent prognostic marker for RFS (HRs: 2.324, 95% CIs: 1.446-3.736) and OS (HRs: 2.629, 95% CIs: 1.585-4.361). In human epidermal growth factor receptor 2 (HER2)-positive and triple negative breast cancer (TNBC) subtypes, high A20 levels were associated with poor OS. CONCLUSION: We found that A20 expression is a poor prognostic marker in breast cancer. The prognostic impact of A20 was pronounced in aggressive tumors, such as HER2-positive and TNBC subtypes. Our findings suggested that A20 may be a valuable target in patients with aggressive breast cancer.

RNF208, an estrogen-inducible E3 ligase, targets soluble Vimentin to suppress metastasis in triple-negative breast cancers.

The development of triple-negative breast cancer (TNBC) negatively impacts both quality of life and survival in a high percentage of patients. Here, we show that RING finger protein 208 (RNF208) decreases the stability of soluble Vimentin protein through a polyubiquitin-mediated proteasomal degradation pathway, thereby suppressing metastasis of TNBC cells. RNF208 was significantly lower in TNBC than the luminal type, and low expression of RNF208 was strongly associated with poor clinical outcomes. Furthermore, RNF208 was induced by 17ß-estradiol (E2) treatment in an estrogen receptor alpha (ΕRα)-dependent manner. Overexpression of RNF208 suppresses tumor formation and lung metastasis of TNBC cells. Mechanistically, RNF208 specifically polyubiquitinated the Lys97 residue within the head domain of Vimentin through interaction with the Ser39 residue of phosphorylated Vimentin, which exists as a soluble form, eventually facilitating proteasomal degradation of Vimentin. Collectively, our findings define RNF208 as a negative regulator of soluble Vimentin and a prognostic biomarker for TNBC cells.

Trps1 regulates proliferation and apoptosis of chondrocytes through Stat3 signaling.

Mutations in the TRPS1 gene lead to the tricho-rhino-phalangeal syndrome, which is characterized by skeletal defects and abnormal hair development. The TRPS1 gene encodes an atypical member of the GATA-type family of transcription factors. Here we show that mice with a disrupted Trps1 gene develop a chondrodysplasia characterized by diminished chondrocyte proliferation and decreased apoptosis in growth plates. Our analyses revealed that Trps1 is a repressor of Stat3 expression, which in turn controls chondrocyte proliferation and survival by regulating the expression of cyclin D1 and Bcl2. Our conclusion is supported (i) by siRNA-mediated depletion of Stat3 in Trps1-deficient chondrocytes, which normalized the expression of cyclin D1 and Bcl2, (ii) by overexpression of Trps1 in ATDC5 chondrocytes, which diminished Stat3 levels and increased proliferation and apoptosis, and (iii) by mutational analysis of the GATA-binding sites in the Stat3 gene, which revealed that their integrity is critical for the direct association with Trps1 and for Trps1-mediated repression of Stat3. Altogether our findings identify Trps1 as a novel regulator of chondrocytes proliferation and survival through the control of Stat3 expression.

Erratum: Identification of Epithelial-Mesenchymal Transition-related Target Genes Induced by the Mutation of Smad3 Linker Phosphorylation.

[This corrects the article on p. 1 in vol. 23, PMID: 29629343.].