Most deaths in breast cancer patients are attributed to metastasis, and lung metastasis is associated with a particularly poor prognosis; therefore it is imperative to identify potential target for intervention. The transforming growth factor-β (TGF-β) pathway plays a vital role in breast cancer metastasis, in which Smad3 is the key mediator and performs specific functions by binding with different cofactors. However, Smad3 cofactors involved in lung metastasis have not yet been identified. This study first establishes the interactome of Smad3 in breast cancer cells and identifies ZNF8 as a novel Smad3 cofactor. Furthermore, the results reveal that ZNF8 is closely associated with breast cancer lung metastasis prognosis, and specifically facilitates TGF-β pathway-mediated breast cancer lung metastasis by participating in multiple processes. Mechanistically, ZNF8 binds with Smad3 to enhance the H3K4me3 modification and promote the expression of lung metastasis signature genes by recruiting SMYD3. SMYD3 inhibition by BCI121 effectively prevents ZNF8-mediated lung metastasis. Overall, the study identifies a novel cofactor of TGF-β/Smad3 that promotes lung metastasis in breast cancer and introduces potential therapeutic strategies for the early management of breast cancer lung metastasis.

Activin A and hepatic stellate cells (HSCs) are involved in tissue repair and fibrosis in liver injury. This study investigated the impact of activin A on HSC activation and migration. A microfluidic D4-chip was used for examining the cell migration of mouse hepatic stellate cell line MHSteC. The analysis of differentially expressed genes revealed that activin βA (Inhba), activin receptor type 1A (Acvr1a) and type 2A (Acvr2a) mRNAs were more significantly expressed in human HSCs than in the hepatocytes. Moreover, activin A promoted MHSteC proliferation and induced MHSteC migration. Furthermore, the MHSteCs treated with activin A exhibited increased levels of migration-related proteins, N-cadherin, Vimentin, α-SMA, MMP2 and MMP9, but a decreased level of E-cadherin. Additionally, activin A treatment significantly increased the p-Smad3 levels and p-Smad3/Smad3 ratio in the MHSteCs, and the Smad3 inhibitor SIS3 attenuated activin A-induced MHSteC proliferation and migration. Simultaneously, activin A increased the calcium levels in the MHSteCs, and the migratory effects of activin A on MHSteCs were weakened by the intracellular calcium ion-chelating agent BAPTA-AM. These data indicate that activin A can promote MHSteC activation and migration through the canonical Smad3 signaling and calcium signaling.

Obesity and fatty liver diseases-metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH)-affect over one-third of the global population and are exacerbated in individuals with reduced functional aldehyde dehydrogenase 2 (ALDH2), observed in approximately 560 million people. Current treatment to prevent disease progression to cancer remains inadequate, requiring innovative approaches. We observe that Aldh2-/- and Aldh2-/-Sptbn1+/- mice develop phenotypes of human metabolic syndrome (MetS) and MASH with accumulation of endogenous aldehydes such as 4-hydroxynonenal (4-HNE). Mechanistic studies demonstrate aberrant transforming growth factor β (TGF-β) signaling through 4-HNE modification of the SMAD3 adaptor SPTBN1 (β2-spectrin) to pro-fibrotic and pro-oncogenic phenotypes, which is restored to normal SMAD3 signaling by targeting SPTBN1 with small interfering RNA (siRNA). Significantly, therapeutic inhibition of SPTBN1 blocks MASH and fibrosis in a human model and, additionally, improves glucose handling in Aldh2-/- and Aldh2-/-Sptbn1+/- mice. This study identifies SPTBN1 as a critical regulator of the functional phenotype of toxic aldehyde-induced MASH and a potential therapeutic target.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a long-term, progressive, and irreversible pulmonary interstitial disease. The activation of Smad family member 2 (Smad2) and Smad3 transcription factors by transforming growth factor β-1 (TGF-β1) is a critical event in the pathogenesis of IPF. However, there is still a lack of understanding regarding the molecular mechanisms governing Smad2 and Smad3 proteins. Ubiquitin-specific protease 7 (USP7) is a deubiquitinase that plays a vital role in regulating protein stability within cells. However, its regulation of the TGF-β signaling pathway and its significance in IPF remain undiscovered. This study aims to clarify the function of USP7 in the TGF-β signaling pathway, while simultaneously exploring the specific molecular mechanisms involved. Additionally, this study seeks to evaluate the therapeutic potential of targeted USP7 inhibitors in IPF, thereby providing novel insights for the diagnosis and management of IPF.
METHODS: We first detected the expression of USP7 in lung tissues of mice with Bleomycin (BLM)-induced pulmonary fibrosis and in Beas-2B cells treated with or without TGF-β1 through Western blot analysis. Subsequently, we explored the influence of USP7 on fibrotic processes and the TGF-β1 signaling pathway, utilizing in vitro and in vivo studies. Finally, we assessed the effectiveness of USP7-specific inhibitors in an IPF murine model.
RESULTS: In the present study, USP7 was found to de-ubiquitinate Smad2 and Smad3, consequently increasing their stability and promoting the TGF-β1-induced production of profibrotic proteins including α-smooth muscle actin (α-SMA) and fibronectin 1 (FN-1). Inhibition or knockdown of USP7 resulted in decreased levels of Smad2 and Smad3 proteins, leading to reduced expression of FN-1, Collagen Type I Alpha 1 Chain (Col1A1), and α-SMA induced by TGF-β1 in human pulmonary epithelial cells. These findings demonstrate that overexpression of USP7 reduces Smad2/3 ubiquitination, whereas inhibition or knockdown of USP7 enhances their ubiquitination. USP7 is abundantly expressed in IPF lungs. The expressions of USP7, Smad2, and Smad3 were upregulated in bleomycin-induced lung injury. The USP7 inhibitor P22077 reduced the expression of FN-1 and type I collagen as well as Smad2/3 and collagen deposition in lung tissue in a model of pulmonary fibrosis induced by bleomycin.
CONCLUSIONS: This study demonstrates that USP7 promotes TGF-β1 signaling by stabilizing Smad2 and Smad3. The contribution of USP7 to the progression of IPF indicates it may be a viable treatment target.

Pulmonary fibrosis (PF) is a chronic, progressive and irreversible interstitial lung disease characterized by unremitting pulmonary myofibroblasts activation, extracellular matrix (ECM) deposition and inflammatory recruitment. PF has no curable medication yet. In this study we investigated the molecular pathogenesis and potential therapeutic targets of PF and discovered drug lead compounds for PF therapy. A murine PF model was established in mice by intratracheal instillation of bleomycin (BLM, 5 mg/kg). We showed that the protein level of pulmonary protein phosphatase magnesium-dependent 1A (PPM1A, also known as PP2Cα) was significantly downregulated in PF patients and BLM-induced PF mice. We demonstrated that TRIM47 promoted ubiquitination and decreased PPM1A protein in PF progression. By screening the lab in-house compound library, we discovered otilonium bromide (OB, clinically used for treating irritable bowel syndrome) as a PPM1A enzymatic activator with an EC50 value of 4.23 μM. Treatment with OB (2.5, 5 mg·kg-1·d-1, i.p., for 20 days) significantly ameliorated PF-like pathology in mice. We constructed PF mice with PPM1A-specific knockdown in the lung tissues, and determined that by targeting PPM1A, OB treatment suppressed ECM deposition through TGF-β/SMAD3 pathway in fibroblasts, repressed inflammatory responses through NF-κB/NLRP3 pathway in alveolar epithelial cells, and blunted the crosstalk between inflammation in alveolar epithelial cells and ECM deposition in fibroblasts. Together, our results demonstrate that pulmonary PPM1A activation is a promising therapeutic strategy for PF and highlighted the potential of OB in the treatment of the disease.

Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on the monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of the target molecules IL-1β, IL-37, caspase-1, and Smad3 were measured in THP-1 macrophages stimulated with MSU, atorvastatin, or rosuvastatin using a real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1β or Smad3 siRNA in THP-1 macrophages was used to verify the pharmaceutical effect of statins in uric-acid-induced inflammation. Results: Serum IL-37 levels in gout patients were significantly higher than in controls (p < 0.001) and was associated with the serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and the transition of IL-37 from the cytoplasm to the nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1β in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1β expression but augmented translocation of IL-37 from the cytoplasm to the nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from the cytoplasm to the nucleus in THP-1 macrophages transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusions: This study revealed that statins inhibit the MSU-induced inflammatory response through phosphorylated Smad3-mediated IL-37 expression in THP-1 macrophages.

Fibroblast growth factor 21 (FGF21), a well-known regulator of metabolic disorders, exhibits the potential to prevent renal fibrosis by negatively regulating the transforming growth factor β (TGF-β)/Smad3 signaling pathway. Gemigliptin and other dipeptidyl peptidase-4 inhibitors are frequently used for the management of patients with type 2 diabetes. However, the protective effect of gemigliptin against renal fibrosis, particularly its potential to upregulate the expression of FGF21, remains incompletely understood. This study assessed the renoprotective effects of gemigliptin against TGF-β-induced renal fibrosis by enhancing the expression of FGF21 in the cultured human proximal tubular epithelial cell line HK-2. Treatment with FGF21 effectively prevented TGF-β-induced renal fibrosis by attenuating the TGF-β/Smad3 signaling pathway. Similarly, gemigliptin exhibited protective effects against TGF-β-induced renal fibrosis by mitigating TGF-β/Smad3 signaling through the upregulation of FGF21 expression. However, the protective effects of gemigliptin were blocked when FGF21 expression was knocked down in TGF-β-treated HK-2 cells. These results indicate that gemegliptin has the potential to exhibit protective effects against TGF-β-induced renal fibrosis by elevating FGF21 expression levels in cultured human proximal tubular epithelial cells.

Pulmonary fibrosis is a chronic and irreversible progressive lung disease caused by various factors, such as age and environmental pollution. With countries stepping into an aging society and the seriousness of environmental pollution caused by global industrialization, the incidence of pulmonary fibrosis is annually increasing. However, no effective drug is available for pulmonary fibrosis treatment. C-phycocyanin (C-PC), extracted from blue-green algae, has good water solubility and antioxidation. This study elucidated that C-PC reinforces autophagy to block pulmonary fibrogenesis by inhibiting long noncoding RNA (lncRNA) biogenesis in vivo and in vitro. Cleavage under targets and release using nuclease (CUT & RUN)-PCR, co-immunoprecipitation (Co-IP), and nuclear-cytoplasmic separation experiments clarified that C-PC blocked the nuclear translocation of activating transcription factor 3 (ATF3) to prevent the binding between ATF3 and transcription factor Smad3, thereby hindering lncIAPF transcription. Human antigen R (HuR) truncation experiment and RNA binding protein immunoprecipitation (RIP) were then performed to identify the binding domain with lncIAPF in the 244-322 aa of HuR. lncIAPF exerted its profibrogenic function through the binding protein HuR, a negative regulator of autophagy. In summary, C-PC promoted autophagy via down-regulating the lncIAPF-HuR-mediated signal pathway to alleviate pulmonary fibrosis, showing its potential as a drug for treating pulmonary fibrosis. Exploring how C-PC interacts with biological molecules will help us understand the mechanism of this drug and provide valuable target genes to design new drugs.

Tendon injury is a prevalent orthopedic disease that currently lacks effective treatment. Galangin (GLN) is a vital flavonoid found abundantly in galangal and is known for its natural activity. This study aimed to investigate the GLN-mediated molecular mechanism of tendon-derived stem cells (TDSCs) in tendon repair. The TDSCs were characterized using alkaline phosphatase staining, alizarin red S staining, oil red O staining, and flow cytometry. The effect of GLN treatment on collagen deposition was evaluated using Sirius red staining and quantitative (q)PCR, while a Western bot was used to assess protein levels and analyze pathways. Results showed that GLN treatment not only increased the collagen deposition but also elevated the mRNA expression and protein levels of multiple tendon markers like collagen type I alpha 1 (COL1A1), decorin (DCN) and tenomodulin (TNMD) in TDSCs. Moreover, GLN was also found to upregulate the protein levels of transforming growth factor β1 (TGF-β1) and p-Smad3 to activate the TGF-β1/Smad3 signaling pathway, while GLN mediated collagen deposition in TDSCs was reversed by LY3200882, a TGF-β receptor inhibitor. The study concluded that GLN-mediated TDSCs enhanced tendon repair by activating the TGF-β1/Smad3 signaling pathway, suggesting a novel therapeutic option in treating tendon repair.

The features of the participation of Smad3 in the functioning of neural stem cells (NSC), neuronal committed precursors (NCP), and neuroglial elements were studied in vitro. It was found that this intracellular signaling molecule enhances the clonogenic and proliferative activities of NCP and inhibits specialization of neuronal precursors. At the same time, Smad3 does not participate in the realization of the growth potential of NSC. With regard to the secretory function (production of neurotrophic growth factors) of neuroglial cells, the stimulating role of Smad3-mediated signaling was shown. These results indicate the promise of studying the possibility of using Smad3 as a fundamentally new target for neuroregenerative agents.