Effects of SDF-1/CXCR7 on the Migration, Invasion and Epithelial-Mesenchymal Transition of Gastric Cancer Cells

CXC chemokine receptor 7 ameliorates renal fibrosis by inhibiting β-catenin signaling and epithelial-to-mesenchymal transition in tubular epithelial cells

Renal fibrosis is a common feature of various chronic kidney diseases. However, the underlying mechanism remains poorly understood. The CXC chemokine receptor (CXCR) family plays a role in renal fibrosis; however, the detailed mechanisms have not been elucidated. In this study, we investigated the potential role of CXCR7 in mediating renal fibrosis. CXCR7 expression is decreased in unilateral ischemia-reperfusion injury (UIRI) and unilateral ureteral obstruction mouse models. Furthermore, CXCR7 was specifically expressed primarily in the Lotus Tetragonolobus Lectin-expressing segment of tubules, was slightly expressed in the peanut agglutinin-expressing segment, and was barely expressed in the Dolichos biflorus agglutinin-expressing segment. Administration of pFlag-CXCR7, an overexpression plasmid for CXCR7, significantly inhibited the activation of β-catenin signaling and protected against the progression of epithelial-to-mesenchymal transition (EMT) and renal fibrosis in a UIRI mouse model. Using cultured HKC-8 cells, we found that CXCR7 significantly downregulated the expression of active β-catenin and fibrosis-related markers, including fibronectin, Collagen I, and α-SMA. Furthermore, CXCR7 significantly attenuated TGF-β1-induced changes in β-catenin signaling, EMT and fibrosis. These results suggest that CXCR7 plays a crucial role in inhibiting the activation of β-catenin signaling and the progression of EMT and renal fibrosis. Thus, CXCR7 could be a novel therapeutic target for renal fibrosis.

CXCR7 promotes pulmonary vascular remodeling via targeting p38/MMP2 pathway in pulmonary arterial hypertension

Background

A hallmark feature of pulmonary arterial hypertension (PAH) is the excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) in the pulmonary arteries. The exact role of C-X-C motif chemokine ligand 12 (CXCL12)/chemokine receptor type 7 (CXCR7) in the PASMCs remains unknown. This study was conducted to investigate CXCR7's role in p38/MMP2 pathway and its effect on PASMCs.

Methods

In this study, we examined the expression profile of CXCL12/CXCR7 in both hypoxic rats and PASMCs. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to measure the level of proliferation in PASMCs. Enzyme-linked immunosorbent assay (ELISA) and western blotting assays were applied to investigate the protein expression of the related molecules.

Results

We found that a high level of CXCR7 was correlated with remodeled pulmonary arterioles in hypoxic rats. Moreover, CXCR7 protein levels were significantly increased by the induction of CXCL12, indicating that the CXCL12-CXCR7 axis participates in PAH. During hypoxia-PAH, CXCR7 inhibition reduces right ventricular systolic pressure (RVSP), the Fulton index, and pulmonary arteriosclerosis remodeling. Further study indicated inhibition CXCR7 reduced PASMCs by downregulating MMP2, via p38 MAPK pathway. It was additionally found that CXCL12/CXCR7 stimulated the phosphorylation of the p38 MAPK pathway, which was a contributing factor to the decrease in MMP2 expression following preconditioning with SB203580, which inhibited p38 MAPK.

Conclusions

In summary, these findings suggest that CXCL12/CXCR7 plays a critical role in PAH, the therapy of which can be developed further by targeting its potential targets.

miR-99b/let-7e/miR-125a cluster suppresses pancreatic cancer through regulation of NR6A1

This experiment investigates how the miR-99b/let-7e/miR-125a cluster regulates the mechanism of NR6A1 involved in the invasive and metastatic effects of pancreatic cancer (PCa). Bioinformatics prediction and dual luciferase reporter gene assay were applied to verify the targeted relationship between miR-99b/let-7e/miR-125a and NR6A1. ASPC1 cells underwent transfection with lentiviruses to overexpress miR-99b/let-7e/miR-125a (individual or together) to explore functions of miR-99b/let-7e/miR-125a cluster governing NR6A1 in PCa. The detection of tumorigenesis was verified by tumor formation assay in nude mice in vivo, and mouse models of liver metastasis of PCa observed cell metastasis of PCa. MiR-99b/let-7e/miR-125a cluster was screened for differential expression in PCa. NR6A1 was confirmed as a target gene of the miR-99b/let-7e/miR-125a cluster. Findings demonstrated that overexpression of the miR-99b/let-7e/miR-125a cluster inhibited cell invasion, metastasis, proliferation, and tumorigenesis in PCa. Conversely, overexpressed NR6A1, a crucial gene in the miR-99b/let-7e/miR-125a cluster, promoted cell invasion, migration, and proliferation in PCa. Moreover, the overexpression of the miR-99b/let-7e/miR-125a cluster inhibited liver metastases and tumor formation. Thus, the study concludes that the miR-99b/let-7e/miR-125a cluster impedes the invasion and metastasis of PCa cells via targeting the NR6A1 gene.

Carbon-ion beam irradiation in combination with cisplatin effectively suppresses xenografted malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare aggressive cancer. This study investigated the growth-inhibitory effects of the combination of carbon ion beam irradiation (IR) and cisplatin (CDDP) on MPM xenografts. Carbon-ion beam IR at 15 Gy effectively inhibited tumor growth and decreased the tumor volume more than 90% after 9 weeks. However, tumor regrowth was observed after 17 weeks. The combination of carbon-ion beam IR (15 Gy) and CDDP significantly suppressed tumor growth after 9 weeks, with tumor regression being observed for more than 18 weeks. In contrast, X-ray IR (30 Gy) alone or in combination with CDDP effectively suppressed tumor growth and decreased the tumor volume after 11 weeks, but tumor growth was observed after 15 weeks. Carbon-ion beam IR at 25 Gy resulted in complete tumor regression without tumor regrowth in the 20-week follow-up period. Histopathological analysis revealed that combination of carbon-ion beam IR and CDDP exerted effective cytotoxic effects on MPM xenograft tumor cells and significantly promoted tumor cell necrosis, cavitation, and fibrosis when compared with individual treatment with carbon-ion beam, X-ray IR, or CDDP. Immunohistochemical analysis revealed that the expression levels of tumor cell migration and invasion-related proteins such as CXCL12, MMP2 and MMP9 were not significantly affected upon low dose (15 Gy) carbon-ion beam IR alone or in combination with CDDP but were markedly upregulated upon treatment with CDDP alone relative to control. However, IR with a high dose (25 Gy) carbon-ion beam inhibited tumor growth without upregulating these proteins. In conclusion, the combination of IR with a low dose (15 Gy) carbon ion beam and CDDP effectively suppressed MPM tumor in vivo without significantly upregulating CXCL12, MMP2 and MMP9, suggesting that combination therapy of carbon ion beam IR and chemotherapy is a promising therapeutic strategy for MPM.