Suppression of CIP4/Par6 attenuates TGF-β1-induced epithelial-mesenchymal transition in NRK-52E cells

FOXN2, identified as a novel biomarker in serum, modulates the transforming growth factor-beta signaling pathway through its interaction with partitioning defective 6 homolog alpha, contributing to the pathogenesis of gastric cancer

BACKGROUND AND OBJECTIVE

Dysregulated expression of Forkhead Box N2 (FOXN2) has been detected in various cancer types. However, the underlying mechanisms by which FOXN2 contributes to the onset and progression of gastric cancer (GC) remain largely unexplored. This study aimed to elucidate the potential role of FOXN2 within GC, its downstream molecular mechanisms, and its feasibility as a novel serum biomarker for GC.

METHODS

Tissue samples from GC patients and corresponding non-cancerous tissues were collected. Peripheral blood samples were obtained from GC patients and healthy controls. The expression of FOXN2 was determined using quantitative real-time PCR, western blotting, and immunohistochemistry. The expression of FOXN2 in GC cells was modulated by transfection with small interfering RNA (siRNA) or the pcDNA 3.1 expression vector. Cell proliferation was assessed using the Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine incorporation assays. The migratory and invasive capacities of cells were evaluated by Transwell assays, apoptosis rates were measured by flow cytometry, and the expression of proliferative, apoptotic, and epithelial-mesenchymal transition (EMT) markers were assessed by western blot analysis.

RESULTS

FOXN2 was found to be overexpressed in the serum, tissues, and cells of GC, correlating with distant metastasis and TNM staging. FOXN2 demonstrated diagnostic value in differentiating GC patients from healthy individuals, with higher levels of FOXN2 being indicative of poorer survival rates. Silencing FOXN2 in vitro inhibited the proliferation, invasion, migration, and EMT of GC cells, while promoting apoptosis. FOXN2 was shown to regulate the transforming growth factor-beta (TGFβ) receptor signaling pathway in GC cells via its interaction with Partitioning Defective 6 Homolog Alpha (PARD6A).

CONCLUSION

In summary, our data suggest that FOXN2 acts as an oncogenic factor in GC, modulating the TGFβ pathway by binding to PARD6A, thereby influencing gastric carcinogenesis. This study underscores the functional significance of FOXN2 as a potential serum biomarker and therapeutic target in GC.

Hyperosmotic stress induces epithelial-mesenchymal transition through rearrangements of focal adhesions in tubular epithelial cells

Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is a hallmark of renal tubulointerstitial fibrosis and is associated with chronic renal injury as well as acute renal injury. As one of the incidences and risk factors for acute renal injury, increasing the osmolality in the proximal tubular fluid by administration of intravenous mannitol has been reported, but the detailed mechanisms remain unclear. Hyperosmotic conditions caused by mannitol in the tubular tissue may generate not only osmotic but also mechanical stresses, which are known to be able to induce EMT in epithelial cells, thereby contributing to renal injury. Herein, we investigate the effect of hyperosmolarity on EMT in tubular epithelial cells. Normal rat kidney (NRK)-52E cells were exposed to mannitol-induced hyperosmotic stress. Consequently, the hyperosmotic stress led to a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker, α-smooth muscle actin (α-SMA), which indicates an initiation of EMT in NKR-52E cells. The hyperosmotic condition also induced time-dependent disassembly and rearrangements of focal adhesions (FAs) concomitant with changes in actin cytoskeleton. Moreover, prevention of FAs rearrangements by cotreatment with Y-27632, a Rho-associated protein kinase inhibitor, could abolish the effects of hyperosmotic mannitol treatment, thus attenuating the expression of α-SMA to the level in nontreated cells. These results suggest that hyperosmotic stress may induce EMT through FAs rearrangement in proximal tubular epithelial cells.

Low expression of CIP4 in predicting worse overall survival: A potential biomarker for laryngeal cancer

Previous reports indicate that Cdc42-interacting protein-4 (CIP4) has previously been reported to plays an important role in the progression of various cancers. However, its correlation with laryngeal cancer (LC) remains unreported. Data from TCGA and GEO databases were used to evaluate the role of CIP4 in LC. Based on GEO and TCGA datasets, we analyzed the differences in CIP4 expression between normal and tumor samples. The Wilcoxon signed-rank test was used to analyze the relationship between clinical features and CIP4. Cox regression and the Kaplan-Meier analyses were used to identify the clinical characteristics associated with the overall survival. Also, the GEPIA database was used to confirm the relationship between CIP4 and overall survival. Lastly, Gene Set Enrichment Analysis (GSEA) was performed based on the TCGA dataset. CIP4 expression in LC was significantly associated with gender and tumor stage (p-values<0.05). Similar to GEPIA validation, Kaplan-Meier survival analysis demonstrated that LC with CIP4-low exhibited a worse prognosis than that with CIP4-high. Univariate analysis revealed that CIP4-high significantly correlated with better overall survival (HR: 0.522, 95% CI: 0.293–0.830, P = 0.026). Besides, multivariate analysis revealed that CIP4 remained independently associated with the overall survival (HR: 0.61, 95% CI: 0.326–0.912, P = 0.012). GSEA showed that the p53, WNT signaling, TGF-β signaling pathways, etc. were enriched in a phenotype high CIP4 expression. In summary, the CIP4 gene is a potential prognostic molecular marker for patients diagnosed with laryngeal cancer. Moreover, the p53, WNT signaling, and TGF-β signaling pathways are potentially associated with CIP4 in LC.

RepSox effectively promotes the induced differentiation of sheep fibroblasts into adipocytes via the inhibition of the TGF‑β1/Smad pathway

Previous reports have demonstrated that RepSox can function as a replacement for cMyc and Sox2 in the reprogramming of cells into induced pluripotent stem cells (iPSCs), as well as increasing the levels of bone morphogenetic protein (BMP)-3 and inducing the phosphorylation of Smad1 in mouse embryonic stem cells. In the present study, it was demonstrated that RepSox caused the visible morphological transformation of sheep fibroblasts; however, no significant alterations in cell proliferation, apoptosis or chromosome aberrations were observed. Moreover, RepSox increased the plasticity of long-term cryopreserved sheep fibroblasts, and further promoted differentiation into adipocytes. RepSox treatment led to a notable decrease in the expression of components of the transforming growth factor (TGF)-β signaling pathway, particularly Smad2/3 phosphorylation. RepSox also activated the BMP pathway, promoted the reprogramming of cells from fibroblasts into adipocytes and induced mesenchymal-epithelial transition. It is worth noting that RepSox notably increased the expression of octamer-binding transcription factor 4 and L-Myc, whereas Sox2 and Nanog expression were not detected. The results of high-throughput RNA sequencing revealed that the levels of differentially expressed genes (DEGs) involved in various metabolic processes were markedly upregulated in the RepSox-treated fibroblasts, while the DEGs in the majority of signaling pathways were markedly downregulated. On the whole, the present study demonstrates that RepSox can promote the plasticity of sheep fibroblasts and facilitates the differentiation of adipocytes via increasing BMP expression and inhibiting the activation of the TGF-β signaling pathway.

Lefty-1 inhibits renal epithelial-mesenchymal transition by antagonizing the TGF-β/Smad signaling pathway

Epithelial-mesenchymal transition (EMT) is a biological process in which tubular epithelial cells lose their phenotypes, and new mesenchymal feature are obtained. In particular, type II EMT possibly contributes to renal tissue fibrogenesis. Recent studies indicate that Lefty-1, a novel member of the TGF-β superfamily with pleiotropical and biological regulation characteristics on TGF-β and other signaling pathways, is considered to have potential fibrotic effects. However, its role in EMT, which is often a long-term consequence of renal tubulointerstitial fibrosis, remains unknown. In this study, we found that Lefty-1 alleviates EMT induction through antagonizing TGF-β/Smad pathway in vivo and in vitro. In unilateral ureteral obstruction (UUO) model mice, administration of adenovirus-mediated overexpression of Lefty-1 (Ad-Lefty-1) significantly reduced TGF-β1/Smad expression and alleviated the phenotypic transition of epithelial cells to mesenchymal cells and extracellular matrix (ECM) accumulation. In high glucose-induced rat renal tubular duct epithelial cell line (NRK-52E), EMT and ECM synthesis were alleviated with Lefty-1 treatment, which significantly inhibited TGF-β1/Smad pathway activation in UUO mice and high glucose-treated NRK-52E cells. Thus, Lefty-1 can alleviate EMT and renal interstitial fibrosis in vivo and in vitro through antagonizing the TGF-β/Smad pathway, and Lefty-1 might have a potential novel therapeutic effect on fibrotic kidney diseases.

Par6 regulates cell cycle progression through enhancement of Akt/PI3K/GSK-3β signaling pathway activation in glioma

As the key factor of the polarity protein complex, Par6 not only regulates polarization processes, but also plays important roles in tumor metastasis and progression in many epithelium malignancy tumors. Here, we showed that Par6 is an essential component in glioma tumorigenesis. Our results indicated the aberrant expression of Par6 in malignant glioma tissues and cell lines. We found that the regulation of Par6 expression induces cell proliferation and tumor growth in vivo and in vitro. Additionally, RNA-seq revealed the effects of Par6 were associated with cyclin D1-regulated cell cycle progression in glioma cells. Moreover, our results demonstrated that the regulation of Par6 can enhance the activation of Akt/PI3K signaling pathway, and subsequently upregulate the expression level of GSK-3β protein, which then regulate cyclin D1-mediated cell cycle regulation. Furthermore, we found that TGF-β-induced the upregulation of Par6 expression may be involved in this process. The pathological analysis confirmed the correlation between Par6 expression and the prognosis in human glioma tissues, suggesting the regulation of Par6 expression regulates glioma tumorigenesis and progression. Thus, our findings showed that Par6 might be a potential biomarker for the diagnosis and providing a therapeutic strategy for the treatment of malignant glioma.

[Role of TGF-β1/ILK/FSP1 signaling pathway in cyclosporin A-induced epithelialmesenchymal transition in cultured renal tubular epithelial cells]

OBJECTIVE

To explore the role of transforming growth factor-β1/integrin-linked kinase/fibroblast-specific protein 1 (TGF- β1/ILK/FSP1) signaling pathway in cyclosporine A (CsA)-induced renal tubular epithelial cell transdifferentiation.

METHODS

Rat renal tubular epithelial NRK-52E cells were induced with 1 mg/L CsA, treated with TGF-β1 inhibitor (SB431542, 10 μmol/L), or transfected with the ILK-RNAi lentiviral expression vector (ILKshRNA) or a negative control vector before CsA induction. The expressions of TGF-β1, ILK and FSP-1 mRNAs and proteins in the cells were detected using real-time PCR and Western blotting. The positive cells for α-SMA expression were detected by immunohistochemistry.

RESULTS

Compared with the blank control cells, the cells treated with CsA showed significantly increased levels of TGF-β1, ILK and FSP-1 mRNAs and proteins (P < 0.05). The expressions of TGF-β1, ILK and FSP-1 were significantly lower in TGF-β1 inhibitor group than in CsA group (P < 0.05). The levels of ILK and FSP-1 were significantly decreased after shRNA-mediated ILK silencing (P < 0.05). The number of positive cells for α-SMA was significantly lower in cells treated with SB431542 and in cells with ILK silencing than in the cells treated with CsA alone (P < 0.05).

CONCLUSIONS

The activation of TGF-β1/ILK/FSP-1 signaling pathway is an important mechanism for CsA-induced transdifferentiation in rat renal tubular epithelial cells. ILK participates in CsA-induced epithelialmesenchymal transition of renal tubular epithelial cells.