ABSTRACT
[ ABSTRACT] AIM:To explore the effect of sterol regulatory element-binding protein 2 ( SREBP-2) on tunicamy-cin-induced endoplasmic reticulum stress ( ERS) in chondrocytes.METHODS:After isolation of human normal chondro-cytes and osteoarthritis ( OA) chondrocytes, the normal cells were cultured and treated with tunicamycin and SREBP-2 siR-NA.After 24 h treatment, fluorescent quantitative RT-PCR ( RT-qPCR) was applied to quantify microRNA-185 ( miR-185) levels.The cell apoptotic rate was determined by flow cytometry.The expression of SREBP-2 and ERS-related pro-teins, C/EBP homologous protein (CHOP), phosphorylated eukaryotic initiation factor-2α(p-eIF2α) and activating tran-scription factor 4 (ATF4), and the expression of apoptosis-related proteins, Bcl-2, Bax and caspase-3, were determined by Western blot.The caspase-3 activity kit was used to determine the caspase-3 activity.RESULTS: Compared with hu-man normal chondrocytes, both SREBP-2 up-regulation and miR-185 down-regulation were observed in OA chondrocytes (P<0.05).SREBP-2 siRNA transfection enhanced tunicamycin-inhibited miR-185 level (P<0.05).miR-185 overex-pression reduced tunicamycin-induced SREBP-2 expression ( P <0.05 ) .OA control group and tunicamycin treatment group consistently resulted in ERS and cell apoptosis with concomitant enhancement of CHOP, p-eIF2αand ATF4 proteins, increases in Bax and caspase-3 proteins, and reduction of Bcl-2 (P<0.05).However, SREBP-2 silencing significantly re-versed these effects ( P<0.05) .The apoptotic rates were consistent with the expression tendency of apoptosis-related pro-teins (P<0.05).SREBP-2 siRNA transfection markedly down-regulated tunicamycin-induced caspase-3 activity, which was notably blocked by miR-185 inhibition (P<0.05).CONCLUSION:SREBP-2 silencing may inhibit tunicamycin-in-duced ERS and cell apoptosis via up-regulating miR-185 expression.
ABSTRACT
OBJECTIVE: The deregulation of microRNA‑185 (miR‑185) has been showed to be associated with many cancers and act as a tumor suppressor in many types of human malignancies. We hence tried to find out its role in human colorectal cancer (CRC). MATERIALS AND METHODS: miR‑185 expression was investigated by real‑time quantitative polymerase chain reaction. We carried out transfections to overexpress or knockdown of miR‑185 by mimics or inhibitor, respectively. Functional study like cell counting kit‑8 assay was performed to evaluate the proliferation. For addressing the impact of miR‑185 on Wnt/β‑catenin signaling, we further applied luciferase reporter assay and Western blotting for specific proteins in this pathway. RESULTS: miR‑185 was decreased in CRC cell lines when compared with corresponding control cell line. We also proved that its overexpression in LoVo cells could remarkably suppress cell proliferation whereas knocked it down in SW480 cells has the opposite effect in vitro. Mechanically, we demonstrated that miR‑185 could suppress the Wnt/β‑catenin signaling and modulate the transcription and translation level of downstream molecules of this pathway, including MYC and CCND1. CONCLUSION: Taken together, these results suggested that miR‑185 exerts its tumor suppressor activities probably through a negative modulation of the Wnt/β‑catenin pathway.
ABSTRACT
PURPOSE: Gastrokine 1 plays an important role in gastric mucosal defense. Additionally, the Gastrokine 1-miR-185-DNMT1 axis has been shown to suppress gastric carcinogenesis through regulation of epigenetic alteration. Here, we investigated the effects of Gastrokine 1 on DNA methylation and gastritis. MATERIALS AND METHODS: Expression of Gastrokine 1, DNMT1, EZH2, and c-Myc proteins, and the presence of Helicobacter pylori CagA protein were determined in 55 non-neoplastic gastric mucosal tissue samples by western blot analysis. The CpG island methylation phenotype was also examined using six markers (p16, hMLH1, CDH1, MINT1, MINT2 and MINT31) by methylation-specific polymerase chain reaction. Histological gastritis was assessed according to the updated Sydney classification system. RESULTS: Reduced Gastrokine 1 expression was found in 20 of the 55 (36.4%) gastric mucosal tissue samples and was closely associated with miR-185 expression. The Gastrokine 1 expression level was inversely correlated with that of DNMT1, EZH2, and c-Myc, and closely associated with the degree of gastritis. The H. pylori CagA protein was detected in 26 of the 55 (47.3%) gastric mucosal tissues and was positively associated with the expression of DNMT1, EZH2, and c-Myc. In addition, 30 (54.5%) and 23 (41.9%) of the gastric mucosal tissues could be classified as CpG island methylation phenotype-low and CpG island methylation phenotype-high, respectively. Reduced expression of Gastrokine 1 and miR-185, and increased expression of DNMT1, EZH2, and c-Myc were detected in the CpG island methylation phenotype-high gastric mucosa. CONCLUSIONS: Gastrokine 1 has a crucial role in gastric inflammation and DNA methylation in gastric mucosa.