5-Aza-2'-deoxycytidine inhibits retinoblastoma cell by reactivating epigenetically silenced RASSF1A gene

AIM: To investigate the effect of 5-Aza-2’-deoxycytidine(5-Aza-CdR),a DNA methyltransferase(DNMT) inhibitor,on the growth and survival of the Chinese retinoblastoma(RB) cell line HXO-RB44. ·METHODS: The DNA methylation status of the Ras association domain family(RASSF1A) promoter in the presence of 5-Aza-CdR at different concentrations was analyzed by methylation-specific polymerase chain reaction(MSP). RASSF1A mRNA and protein levels were measured by semiquantitative RT-PCR and immunohistochemistry staining,respectively,when cells were treated with 5.0μmol/L of 5-Aza-CdR. The effect of 5.0μmol/L 5-Aza-CdR on the proliferation and viability of HXO-RB44 cells was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay and flow cytometry. ·RESULTS: 5-Aza-CdR efficiently induced cell cycle arrest at G0 /G1 and apoptotic death in HXO-RB44 cells. MSP analysis showed that unmethylated RASSF1A DNA increased and methylated RASSF1A decreased in a dose-dependent manner in a range of 0.5-5.0μmol/L 5-Aza-CdR. Accordingly,RASSF1A expression was reactivated at both mRNA and protein levels. Incubation time of 5-Aza-CdR treatment also functioned as a factor for the demethylation status of RASSF1A promoter DNA,with a plateau on day four. 5-Aza-CdR at 5.0μmol/L completely demethylated the RASSF1A promoter in HXORB44 cells on day four,and as a result,RASSF1A expression increased significantly from day 4 to day 7.·CONCLUSION: 5-Aza-CdR inhibits the growth of the HXO-RB44 RB cell line and induces apoptosis by demethylating the RASSF1A gene.

Choroidal thickness in pregnant women : a cross-sectional study

AIM: To investigate choroidal thickness in pregnant women and compare the measurements with those of normal nonpregnant women. METHODS: Using enhanced depth imaging optical coherence tomography (EDI-OCT), choroidal thickness was measured at the fovea and at 1 mm and 3 mm superior, inferior, temporal, and nasal to the fovea in both healthy pregnant women and nonpregnant women. Pearson correlation analysis was performed to evaluate the relationships between subfoveal choroidal thickness (SFCT) and the demographic and ocular parameters. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using fixed-effects model when Meta analyses were conducted. RESULTS: Comparison of choroidal thickness between the groups showed that it was significantly greater in healthy pregnant women's eyes than in normal nonpregnant women's eyes at all locations except at 3 mm superior and 3 mm temporal from the fovea (P<0.05). The mean SFCT was 344.13 +/- 50.94 mu m in healthy pregnant women's eyes and 315.03 +/- 60.57 mu m in normal nonpregnant women's eyes, with a statistically significant difference (P=0.008). Pearson correlation analysis showed that age and axial length were significantly related to SFCT in healthy pregnant women, normal nonpregnant women, and all subjects. The results of our cross-sectional study were consistent with the results of the further Meta analysis, with a pooled weighted mean difference (WMD) of 33.66 mu m (95% CI: 26.16 to 41.15) for SFCT. CONCLUSION: Our results, along with the comprehensive Meta-analysis, suggest that choroidal thickness in healthy pregnant women is greater than that in normal nonpregnant women.

Emerging roles of lncRNAs in the post-transcriptional regulation in cancer

Accumulating evidence indicates that long non-coding RNAs(lncRNAs)can play a pivotal role in regulation of diverse cellular processes.In particular,lncRNAs can serve as master gene regulators at transcriptional and posttranscriptional levels,leading to tumorigenesis.In this review,we discuss latest developments in lncRNA-meditated gene expression at the post-transcriptional level,including gene splicing,mRNA stability,protein stability and nuclear trafficking.

The functions of N6-methyladenosine modification in lncRNAs

Increasing evidence indicates that mRNAs are often subject to posttranscriptional modifications.Among them,N6-methyladenosine(m6A),which has been shown to play key roles in RNA splicing,stability,nuclear export,and translation,is the most abundant modification of RNA.Extensive studies of m6A modification of mRNAs have been carried out,while little is known about m6A modification of long non-coding RNAs(lncRNAs).Recently,several studies reported m6A modification of lncRNAs.In this review,we focus on these m6A-modified lncRNAs and discuss possible functions of m6A modification.

M6A modification of circNSUN2 promotes colorectal liver metastasis

Circular RNAs(circRNAs)are playing emerging role in the pathogenesis of cancers,but the mechanisms still unknown.In the recent issue of the Nature Communications,Chen and colleagues have demonstrated that YTHDC1 facilitates N6-methyladenosine modified circNSUN2 cytoplasmic export and the circNSUN2/IGF2BP2/HMGA2 complex stabilizes HMGA2 to promote colorectal liver metastasis.These discoveries not only expand our understanding of circRNAs biology in tumor,but also demonstrate that m6A modification plays a key role for circRNAs in RNA metabolism.Therefore,these findings indicate that circRNAs may be a new approach for therapeutic target of cancers.