Correlation between miR-126 expression and DNA hypomethylation of CD4+ T cells in rheumatoid arthritis patients.

It has been known that the occurrence of rheumatoid arthritis (RA) was closely correlated with DNA hypomethylation in CD4+ T cells, in which DNA methyltransferase plays a certain role. This study therefore investigated the effect of miR-126 on CD4+ T cell subgroup in RA patients and the alternation of DNA hypomethylation, in an attempt to provide new sights into the pathogenesis and treatment of RA. CD4+ T cells separated from RA patients were transfected with miRNA (miR)-126 expression vector or miR-126 inhibitor expression vector. The expression levels of CD11a, CD70 and DNMT1 mRNA were examined by real-time PCR. Protein levels of CD11a and CD70 were tested by flow cytometry while DNMT1 protein level was quantified by Western blotting. DNA was modified by sodium bisulfite and was sequenced for the methylation status of promoters of CD11a and CD70 genes. Both mRNA and protein expressions of CD11a and CD70 genes in CD4+ T cells were elevated by miR-126 transfection, along with decreased DNMT1 protein level but not mRNA level. The methylation degree of promoters of both CD11a and CD70 genes were significantly depressed after miR-126 transfection. The transfection by miR-126 inhibitor effectively reversed such effects. In RA patients, elevated miR-126 may promote the expression of CD11a and CD70 via the induction of hypomethylation of gene promoters by depressing DNMTI1 protein levels.

MicroRNA-522 reverses drug resistance of doxorubicin-induced HT29 colon cancer cell by targeting ABCB5.

MicroRNAs (miRNAs) are small non-coding RNAs, which are important in the development of multidrug resistance in cancer by regulating gene expression at the post­transcriptional level. The present study investigated the functional effects of miR­522 in chemoresistant colon cancer cells. The results demonstrated that miR­522 was significantly downregulated in doxorubicin (DOX) resistant colon cell line, HT29/DOX, compared with the parental HT29 colon cancer cell line. Overexpression of miR­522 in the HT29/DOX cells partially restored DOX sensitivity. miRNA target prediction algorithms suggested that ABCB5 was a target gene for miR­522. A fluorescent reporter assay confirmed that miR­522 was able to specifically bind to the predicted site of the ABCB5 mRNA 3'­untranslated region. When miR­522 was overexpressed in the HT29/DOX cells, the protein expression levels of ABCB5 were downregulated. Furthermore, knockdown of ABCB5 significantly increased the growth inhibition rate of the HT29/DOX cells, compared with the control group. These results suggested that miR­522 may affect the sensitivity of colon cancer cell lines to DOX treatment by targeting ABCB5.

Upregulation of miR-195 increases the sensitivity of breast cancer cells to Adriamycin treatment through inhibition of Raf-1.

Chemotherapy is an important option for the treatment of advanced breast cancer, but multidrug resistance is one of the major obstacles in the clinical control of breast cancer. The present study investigated the effects of the miR­195-led gene pathway in the sensitization of breast cancer cells to treatment with the chemotherapeutic drug Adriamycin. Breast cancer cell lines and tissue specimens (obtained from chemotherapy-sensitive or resistant patients) as well as a normal breast cell line were used to assess expression of miR-195, Raf-1, Bcl-2 and P-glycoprotein mRNA and/or mRNA. miR-195 mimics, inhibitor and Raf-1 siRNA were used to transfect breast cancer MCF-7 and MCF-7/ADR cells (an Adriamycin-resistant MCF-7 subline) for cell viability, apoptosis and gene expression analysis. The data showed that miR-195 expression was low in breast cancer cells and multidrug-resistant breast cancer tissues, which was associated with reduced Raf-1 expression in vitro and ex vivo. Induction of miR-195 expression promoted tumor cell apoptosis and inhibited breast cancer cell viability, but induced the sensitivity of breast cancer cells to Adriamycin treatment and was associated with inhibition of Raf-1 expression in breast cancer cells. Moreover, knockdown of Raf-1 expression had similar effects of miR-195 mimics on breast cancer cells, both of which were able to suppress Bcl-2 and P-glycoprotein expression in breast cancer cells. The data from the current study demonstrated that expression of miR-195 was inversely associated with Raf-1 expression in breast cancer cell lines and tissue specimens, and that Raf-1 is the target gene of miR-195. Thus, expression of miR-195 or knockdown of Raf-1 can similarly reduce tumor cell survival but increase apoptosis through downregulation of Raf-1 and Bcl-2 and P-glycoprotein expression. In conclusion, this gene pathway mediated the sensitivity of breast cancer cells to Adriamycin treatment.

CYP2E1 polymorphisms and colorectal cancer risk: a HuGE systematic review and meta-analysis.

Studies investigating the associations between Cytochrome P4502E1 (CYP2E1) polymorphisms and colorectal cancer (CRC) risk report conflicting results. We conducted a meta-analysis to assess the association between CYP2E1 gene Rsa I/Pst I, Dral T/A and 96-bp insertion polymorphisms and CRC susceptibility. Two investigators independently searched the Medline, Embase, CNKI, Wanfang, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95 % confidence intervals (95 % CIs) for CYP2E1 polymorphisms and CRC were calculated in a fixed-effect model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate. Ultimately, 12, 5, and 4 studies were found to be eligible for meta-analyses of Rsa I/Pst I, Dral T/A, and 96-bp insertion polymorphisms, respectively. Our analysis suggested that the variant genotype of Rsa I/Pst I were associated with a significantly increased CRC risk (c2/c2 vs. c1/c1, OR = 1.36, 95 % CI = 1.04-1.77; recessive model, OR = 1.35, 95 % CI = 1.04-1.75). Moreover, similar results were observed between CYP2E1 96-bp insertion polymorphism and CRC risk (dominant model, OR = 1.25, 95 % CI = 1.07-1.45), while no association was observed between CYP2E1 Dral T/A polymorphism and CRC susceptibility in any genetic model. No publication bias was found in the present study. This meta-analysis shows that CYP2E1 Rsa I/Pst I and 96-bp insertion polymorphisms may be associated with CRC risk. The CYP2E1 Dral T/A polymorphism was not detected to be related to the risk for CRC.