Xiaochang Xue

A novel NF-κB/YY1/microRNA-10a regulatory circuit in fibroblast-like synoviocytes regulates inflammation in rheumatoid arthritis

The main etiopathogenesis of rheumatoid arthritis (RA) is overexpressed inflammatory cytokines and tissue injury mediated by persistent NF-κB activation. MicroRNAs widely participate in the regulation of target gene expression and play important roles in various diseases. Here, we explored the mechanisms of microRNAs in RA. We found that microRNA (miR)-10a was downregulated in the fibroblast-like synoviocytes (FLSs) of RA patients compared with osteoarthritis (OA) controls, and this downregulation could be triggered by TNF-α and IL-1β in an NF-κB-dependent manner through promoting the expression of the YingYang 1 (YY1) transcription factor. Downregulated miR-10a could accelerate IκB degradation and NF-κB activation by targeting IRAK4, TAK1 and BTRC. This miR-10a-mediated NF-κB activation then significantly promoted the production of various inflammatory cytokines, including TNF-α, IL-1β, IL-6, IL-8, and MCP-1, and matrix metalloproteinase (MMP)-1 and MMP-13. In addition, transfection of a miR-10a inhibitor accelerated the proliferation and migration of FLSs. Collectively, our data demonstrates the existence of a novel NF-κB/YY1/miR-10a/NF-κB regulatory circuit that promotes the excessive secretion of NF-κB-mediated inflammatory cytokines and the proliferation and migration of RA FLSs. Thus, miR-10a acts as a switch to control this regulatory circuit and may serve as a diagnostic and therapeutic target for RA treatment.

FOXP3 inhibits NF-κB activity and hence COX2 expression in gastric cancer cells

Gastric cancer remains the main cause of cancer related deaths all over the world, and upregulated COX2 is a key player in its development. The mechanism as to how COX2 is regulated during the gastric cancer development is largely unknown. In this study, we found that the expression of COX2 was closely correlated with NF-κB activity. Strikingly, NF-κB activity was not absolutely consistent with its nuclear localization. Especially, in some cancer cell lines, such as MKN28, there were abundant nuclear localized NF-κB, while NF-κB luciferase activity in this cell line was relatively low. Furthermore, FOXP3 was found to be abundantly expressed in these cells. When the nuclear localized NF-κB expression was adjusted with the expression of FOXP3, it then correlated well with NF-κB activity. Molecularly, increased FOXP3 expression can interact with NF-κB and thus repress its activity. Knockdown of FOXP3 could increase NF-κB activity, COX2 expression, and cell migration. Taken together, our study revealed that function of FOXP3 as a negative regulator of NF-κB activity and thus plays a tumor suppressor role by reducing cell metastasis.

FOXP3 suppresses breast cancer metastasis through downregulation of CD44

Forkhead box protein 3 (FOXP3) plays an important role in breast cancer as an X‐linked tumor suppressor gene. However, the biological functions and significance of FOXP3 in breast cancer metastasis remain unclear. Here, we find that, clinically, nuclear FOXP3 expression is inversely correlated with breast cancer metastasis. Moreover, we demonstrate that FOXP3 significantly inhibits adhesion, invasion and metastasis of breast cancer cells in vivo and in vitro. In addition, the adhesion molecule CD44 is found to be suppressed by FOXP3 through transcriptome sequence analysis (RNA‐seq). A luciferase reporter assay, chromatin immunoprecipitation and electrophoretic mobility shift assay identify CD44 as a direct target of FOXP3. The expression of CD44 is downregulated by FOXP3 in breast cancer cells. Importantly, anti‐CD44 antibody reverses the FOXP3 siRNA‐induced effects on the breast cancer cells in vitro and FOXP3 expression level in the nucleus of breast cancer cells is inversely correlated with CD44 expression level in clinic breast cancer tissues. Taken together, the results from the present study suggest that FOXP3 is a suppressor of breast cancer metastasis. FOXP3 directly binds to the promoter of CD44 and inhibits its protein expression, thereby suppressing adhesion and invasion of human breast cancer cells. This finding highlights the therapeutic potential of FOXP3‐CD44 signaling to inhibit breast cancer metastasis.

Loss of ERα induces amoeboid-like migration of breast cancer cells by downregulating vinculin

Oestrogen receptor alpha (ERα) is a well-known target of endocrine therapy for ERα-positive breast cancer. ERα-negative cells, which are enriched during endocrine therapy, are associated with metastatic relapse. Here we determine that loss of ERα in the invasive front and in lymph node metastasis in human breast cancer is significantly correlated with lymphatic metastasis. Using in vivo and in vitro experiments, we demonstrate that ERα inhibits breast cancer metastasis. Furthermore, we find that ERα is a novel regulator of vinculin expression in breast cancer. Notably, ERα suppresses the amoeboid-like movement of breast cancer cells by upregulating vinculin in 3D matrix, which in turn promotes cell–cell and cell–matrix adhesion and inhibits the formation of amoeboid-like protrusions. A positive association between ERα and vinculin expression is found in human breast cancer tissues. The results show that ERα inhibits breast cancer metastasis and suggest that ERα suppresses cell amoeboid-like movement by upregulating vinculin.

Stable plastid transformation for high-level recombinant protein expression: promises and challenges.

Plants are a promising expression system for the production of recombinant proteins. However, low protein productivity remains a major obstacle that limits extensive commercialization of whole plant and plant cell bioproduction platform. Plastid genetic engineering offers several advantages, including high levels of transgenic expression, transgenic containment via maternal inheritance, and multigene expression in a single transformation event. In recent years, the development of optimized expression strategies has given a huge boost to the exploitation of plastids in molecular farming. The driving forces behind the high expression level of plastid bioreactors include codon optimization, promoters and UTRs, genotypic modifications, endogenous enhancer and regulatory elements, posttranslational modification, and proteolysis. Exciting progress of the high expression level has been made with the plastid-based production of two particularly important classes of pharmaceuticals: vaccine antigens, therapeutic proteins, and antibiotics and enzymes. Approaches to overcome and solve the associated challenges of this culture system that include low transformation frequencies, the formation of inclusion bodies, and purification of recombinant proteins will also be discussed.

The discoidin domain receptor 2/annexin A2/matrix metalloproteinase 13 loop promotes joint destruction in arthritis through promoting migration and invasion of fibroblast-like synoviocytes.

Discoidin domain receptor 2 (DDR‐2)/matrix metalloproteinase (MMP) signaling is an important pathway involved in cartilage destruction in rheumatoid arthritis (RA). However, the molecular mechanisms of this pathway have not been clearly identified. This study was undertaken to screen key molecules involved in this pathway and evaluate their biologic functions in synovium invasion of RA.

Therapeutic Effects of PADRE-BAFF Autovaccine on Rat Adjuvant Arthritis

B cell activating factor (BAFF) is a cytokine of tumor necrosis factor family mainly produced by monocytes and dendritic cells. BAFF can regulate the proliferation, differentiation, and survival of B lymphocytes by binding with BAFF-R on B cell membrane. Accumulating evidences showed that BAFF played crucial roles and was overexpressed in various autoimmune diseases such as systemic lupus erythematous (SLE) and rheumatoid arthritis (RA). This suggests that BAFF may be a therapeutic target for these diseases. In the present study, we developed a BAFF therapeutic vaccine by coupling a T helper cell epitope AKFVAAWTLKAA (PADRE) to the N terminus of BAFF extracellular domains (PADRE-BAFF) and expressed this fusion protein in Escherichia coli. The purified vaccine can induce high titer of neutralizing BAFF antibodies and ameliorate the syndrome of complete Freunds adjuvant (CFA) induced rheumatoid arthritis in rats. Our data indicated that the BAFF autovaccine may be a useful candidate for the treatment of some autoimmune diseases associated with high level of BAFF.

Impact of AhR, CYP1A1 and GSTM1 Genetic Polymorphisms on TP53 R273G Mutations in Individuals Exposed to Polycyclic Aromatic Hydrocarbons

This study was to undertaken to investigate the impacts of AhR, CYP1A1, GSTM1 genetic polymorphisms on the R273G mutation in exon 8 of the tumor suppressor p53 gene (TP53) among polycyclic aromatic hydrocarbons (PAHs) exposed to coke-oven workers. One hundred thirteen workers exposed to PAH and 82 control workers were recruited. We genotyped for polymorphisms in the AhR, CYP1A1, GSTM1, and TP53 R273G mutation in blood by PCR methods, and determined the levels of 1-hydroxypyrene as PAH exposure marker in urine using the high pressure liquid chromatography assay. We found that the distribution of alcohol users and the urinary excretion of 1-OHP in the exposed workers were significantly higher than that of the control workers (p=0.004, p<0.001, respectively). Significant differences were observed in the p53 genotype distributions of smoking subjects (p=0.01, 95%CI: 1.23-6.01) and PAH exposure (p=0.008, 95%CI: 1.24-4.48), respectively. Further, significant differences were observed in the p53 exon 8 mutations for the genetic polymorphisms of Lys/Arg for AhR (p=0.02, 95%CI: 0.70-15.86), Val/Val for CYP1A1 (p=0.04, 95%CI: 0.98-19.09) and null for GSTM1 (p=0.02, 95%CI: 1.19-6.26), respectively. Our findings indicated that polymorphisms of PAH metabolic genes, such as AhR, CYP1A1, GSTM1 polymorphisms may interact with p53 genetic variants and may contribute to PAH related cancers.

Subchronic exposure of benzo(a)pyrene interferes with the expression of Bcl-2, Ki-67, C-myc and p53, Bax, Caspase-3 in sub-regions of cerebral cortex and hippocampus.

Benzo[a]pyrene [B(a)P], a representative substance of the polycyclic aromatic hydrocarbons, is an ubiquitous environmental contaminant. However, the mechanism of B(a)P neurotoxicity is still not clear. The aim of this study was to investigate the molecular mechanism by assay the expression of Bcl-2, C-myc, Ki-67 oncogene and p53, Bax, Caspase-3 proapoptotic gene in sub-regions of cerebral cortex and hippocampus in brain. Mice were administrated with subchronic intraperitoneal injection and oral gavage of B(a)P (2.5, 5, 10mg/kg body weight) for 13 weeks. We observed that B(a)P induced the significant increase in relative brain weights and the slight proliferation phenomenon in hippocampus in the experiment. Significant increase of C-myc, Ki-67 and p53, Bax, Caspase-3 and dramatic decrease of Bcl-2 protein levels were observed through immunohistochemical analysis. The relative higher interference of Bcl-2, C-myc, Ki-67 and p53, Bax, Caspase-3 proteins was observed in hippocampus sub-regions of dentate gyrus, cornu ammonis 3 and cornu ammonis 1. The relative lower interference of the examined genes was found in cerebral cortex sub-regions of frontal cortex, temporal cortex and parietal cortex. The results showed a region-difference manner with accompanying dose-dependent manner in brain hippocampus and cerebral cortex induced by B(a)P. These findings indicate that B(a)P-induced subchronic neural toxicity may occur through the enhancement in Bcl-2, C-myc, Ki-67 oncogenes and p53, Bax, Caspase-3 proapoptotic genes expression.

Disturbance of Bcl-2, Bax, Caspase-3, Ki-67 and C-myc expression in acute and subchronic exposure to benzo(a)pyrene in cervix.

Epidemiological studies have demonstrated that cigarette smoking is an important cofactor or an independent risk factor for the development of cervical cancer. Benzo(a)pyrene (BaP) is one of the most potent tobacco smoke carcinogens in tobacco smoke. BaP induced DNA damage and over expression in p53 cervical tissue of mice as demonstrated in our previous study. Here we present the findings of exposure to BaP on the expression of Bcl-2, C-myc, Ki-67, Caspase-3 and Bax genes in mouse cervix. Acute intraperitoneal administration of BaP (12.5, 25, 50, 100mg/kg body weight) to ICR female mice induced a significant increase in Bcl-2, C-myc, Ki-67 mRNA and protein level till 72h except in Bcl-2 at 24h with 12.5, 25, 50mg/kg as well as at 48h with 12.5mg/kg body weight post treatment. A significant increase was also seen in Caspase-3 and Bax mRNA and protein level with peak level at 24h and gradual decrease till 72h, however, the expression of caspase-3 increased while that of Bax decreased with increasing dose of Bap after 24h. In sub chronic intraperitoneal and oral gavage administration of BaP (2.5, 5, 10mg/kg body weight), similar significant increase was observed for all the examined genes as compared to the control and vehicle groups, however the expression of Bax decreased in a dose dependent manner. The findings of this study will help in further understanding the molecular mechanism of BaP induced carcinogenesis of cervical cancer.