MiR-454-3p regulates the activity of lung cancer cells and its effect on the expression of CBX7 protein / 中国医师杂志

Objective:To explore the regulation of miR-454-3p on the activity of lung cancer cells and the expression of CBX7 protein.Methods:Normal lung epithelial cells 293T cells and human lung cancer cell line A549 cells were cultured in vitro. Lung cancer cells (A549 cells) were divided into three groups: blank group, miR-NC group and miR-454-3p group. Cell counting kit-8 (CCK-8) method was used to detect the proliferation of the three groups; Transwell was used to detect the invasion number of the three groups; flow cytometry was used to detect the apoptosis rate; Western blot was used to detect the protein expression of CBX7 in lung cancer cells. Results:Compared with normal lung epithelial 293T cells, the expression of miR-454-3p mRNA in lung cancer A549 cells was significantly reduced, with significant difference ( P<0.05). There was no significant difference in the expression of CBX7 protein between the blank group and the miR-NC group ( P>0.05); The protein expression of CBX7 in miR-454-3p group was significantly higher than that in blank group and miR-NC group (all P<0.05). The results of CCK-8 showed that the A value of miR-454-3p group was significantly lower than that of blank group and miR-NC group (all P<0.05); there was no significant difference in the A value of lung cancer cells between blank group and miR-NC group ( P>0.05). The results of Transwell chamber experiment showed that the number of invasion cells in miR-454-3p group was significantly reduced compared with blank group and miR-NC group, and the invasive ability of lung cancer cells decreased significantly (all P<0.05); there was no significant change in the invasive ability of lung cancer cells between the blank group and miR-NC group ( P>0.05). The results of flow cytometry showed that there was no significant difference in the apoptosis rate between the blank group and miR-NC group ( P>0.05); compared with the blank group and miR-NC group, the apoptosis rate of lung cancer cells in miR-454-3p group increased significantly (all P<0.05). Conclusions:miR-454-3p is under-expressed in lung cancer cells. Overexpression of miR-454-3p can effectively regulate the biological activity of lung cancer cells, inhibit the proliferation and invasion of lung cancer cells, and promote cell apoptosis. Its mechanism may be related to the promotion of CBX7 protein expression by miR-454-3p.

Deubiquitinating Enzyme USP29 Regulates the Protein Stability of CBX6 / 中国生物化学与分子生物学报

Polycomb group (PcG) proteins are transcriptional repressors that control cell fate and the development of embryo, and they elicit function mainly in the form of polycomb repressive complex (PRC). Chromobox protein homolog 6 (CBX6) is one of the core protein subunits of PRC1, which plays an important role in gene expression regulation, cell renewal and differentiation, tumorigenesis and development, and stem cell maintenance. In this study, CBX6 was found to be degraded through a ubiquitin-proteasome dependent pathway. Then the gene expression library containing 92 deubiquitinating enzymes (DUB) was used to screen DUB targeting CBX6 and results found that ubiquitin-specific protease 29 (USP29) could obviously stabilize CBX6 protein level and extend its half-life (P < 0.05). Immunoprecipitation experiments found that CBX6 interacted with USP29 through its C-terminal domains; Further studies found that USP29 regulated the protein stability of CBX6 by deubiquitination in an enzymatic-activity dependent manner. Cell proliferation assay also found that USP29 inhibited the proliferation of MCF7 cells (P<0.0001). Taken together, through screening, this study found that USP29 could stabilize CBX6 protein level through deubiquitinating CBX6 and inhibit the cell proliferation of MCF7.

lncRNA KCNQ1OT1 reverses the effect of sevoflurane on hepatocellular carcinoma progression via regulating the miR-29a-3p/CBX3 axis

Sevoflurane (SEVO) is widely applied as an anesthetic, which exerts antitumor capacity in various cancers, including hepatocellular carcinoma (HCC). Previous studies indicated that long non-coding RNA KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) was upregulated, while microRNA-29a-3p (miR-29a-3p) was downregulated in HCC. Thus, we aimed to explore the roles of KCNQ1OT1 and miR-29a-3p in HCC cells exposed to SEVO. Cell proliferation, apoptosis, migration, and invasion were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, and transwell assays, respectively. The levels of genes were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Furthermore, the interaction between miR-29a-3p and KCNQ1OT1 or chromebox protein homolog 3 (CBX3) was predicted by Starbase or Targetscan, and then confirmed by dual-luciferase reporter assay. We found that the levels of KCNQ1OT1 and CBX3 were decreased, while miR-29a-3p was increased in SEVO-treated HCC cells. KCNQ1OT1 overexpression weakened the inhibitory effects of SEVO on HCC cell proliferation, apoptosis, migration, and invasion. Interestingly, KCNQ1OT1 bound to miR-29a-3p, and miR-29a-3p targeted CBX3. KCNQ1OT1 upregulated CBX3 level by repressing miR-29a-3p expression. Furthermore, KCNQ1OT1 exerted tumor promotion in HCC cells via suppressing miR-29a-3p to regulate CBX3 expression. Collectively, our findings demonstrated that KCNQ1OT1 regulated the antitumor effects of SEVO on HCC cells through modulating the miR-29a-3p/CBX3 axis, providing a theoretical basis for the treatment of HCC.

The CBX family of proteins in transcriptional repression and memory

For mammals to develop properly, master regulatory genes must be repressed appropriately in a heritable manner. This review concerns the Polycomb Repressive Complex 1 (PRC1) family and the relationshipbetween the establishment of repression and memory of the repressed state. The primary focus is on the CBXfamily of proteins in PRC1 complexes and their role in both chromatin compaction and phase separation.These two activities are linked and might contribute to both repression and memory.

Polycomb chromobox Cbx2 enhances antiviral innate immunity by promoting Jmjd3-mediated demethylation of H3K27 at the Ifnb promoter

Polycomb chromobox (CBX) proteins regulate gene transcription by maintaining chromatin states, which guide a variety of biological processes. Now, epigenetic regulation of innate immune response is an emerging field. However, the role of CBX proteins in innate immunity remains unclear. We confirmed that the expression of CBX family proteins, especially Cbx2, was decreased in macrophages upon viral infection, and then we investigated the role of Cbx2 in the antiviral immune response. Silencing or knockdown of Cbx2 in macrophages inhibited virus-induced production of IFN-β. Furthermore, heterozygous Cbx2 knockout were susceptible to VSV challenge. Mechanistically, Cbx2 binds to and recruits Jmjd3 to the Ifnb promoter, leading to demethylation of H3K27me3 and increased transcription of IFN-β. Together, our study reveals a non-traditional function of a Cbx protein and adds new insight into the epigenetic regulation of antiviral innate immunity.

Clinical Significance of Expression of CBX3 in Colorectal Cancer and its Possible Mechanism / 胃肠病学

Background:CBX3 is a member of heterochromatin protein family. Recent studies indicated that CBX3 was closely related to lung cancer,osteosarcoma,gastric cancer. Aims:To investigate the expression and clinical significance of CBX3 in colorectal cancer,and explore the potential mechanism. Methods:Thirty colorectal cancer patients from June 2011 to June 2012 at Shanghai Renji Hospital were enrolled. Real-time quantitative PCR and immunohistochemistry were used to determine mRNA and protein expressions of CBX3 in colorectal cancer tissues and corresponding paracancerous tissues, respectively. Human colorectal cancer cell line RKO was transfected with overexpressed plasmid or siRNA of CBX3. Cell proliferation was measured by CCK-8 assay,Western blotting was implemented to determine the protein expressions of CBX3 and p53. Results:The mRNA and protein expressions of CBX3 were significantly increased in colorectal cancer tissues than in corresponding paracancerous tissues. Increased protein expression of CBX3 was closely correlated with tumor size (P ＝ 0. 025 ),lymph node metastasis (P ＝ 0. 013 )and TNM staging (P ＝ 0. 020 ). After intervention with overexpressed plasmid of CBX3,the mRNA and protein expressions of CBX3 were efficiently upregulated in RKO cells, cell proliferation and protein expression of p53 were significantly increased. Meanwhile,the mRNA and protein expressions of CBX3 were efficiently downregulated in RKO cells after knockdown of CBX3,resulting in significantly decreased cell proliferation and protein expression of p53. Conclusions:CBX3 may promote the proliferation of colorectal cancer cells via influencing the expression of p53,thus promoting the progression of colorectal cancer. This indicates that CBX3 has the potential to be a new target for diagnosis and therapy of colorectal cancer.