Epigenetic regulation of LINC01270 in breast cancer progression by mediating LAMA2 promoter methylation and MAPK signaling pathway.

Application of long non-coding RNAs (lncRNAs) for modulation of breast cancer (BC) has attracted much attention. Here, we probed into the role and underlying mechanism of long intergenic non-coding RNA 01270 (LINC01270) in BC. With the help of bioinformatics tools, we identified laminin subunit alpha 2 (LAMA2) as a BC-related differentially expressed gene to discern the effect of LAMA2 in BC cells. LAMA2 was initially poorly expressed while LINC01270 was highly expressed in BC. BC cells were subsequently treated with sh-LINC01270 or/and sh-LAMA2 for exploration of their regulatory mechanism in BC, which unfolded that LINC01270 inhibition up-regulated LAMA2 and inactivated the MAPK signaling pathway to suppress malignant characteristics of BC cells. Functional assays demonstrated that LINC01270 bound to DNMT1, DNMT3a, and DNMT3b promoted the methylation of CpG islands in LAMA2 promoter and inhibited the LAMA2 expression. Moreover, our data suggested that LAMA2 suppressed MAPK signaling pathway to inhibit BC cell malignant characteristics. The in vitro results were re-produced with the help of the in vivo experimentations. In conclusion, LINC01270 silencing inhibited the methylation of LAMA2 promoter to suppress the activation of MAPK signaling pathway, which subsequently restrained the BC progression. 1, Overexpression of LAMA2 inhibits malignant features of BC cells. 2, LINC01270 promotes LAMA2 promoter methylation by recruiting DNMTs to the LAMA2 promoter region. 3, 5-aza-dc reverses the promotion of LAMA2 promoter methylation by LINC01270. 4, LAMA2 inhibits malignant features of BC cells by suppressing the activation of MAPK signaling pathway.

Effects of 5-Aza-dC combined with chemotherapy regimens on the apoptosis of lung adenocarcinoma cells / 中国综合临床

Objective:To investigate the effect of different chemotherapy drugs combined with DNA methylase inhibitor 5-Aza-2'-deoxycytidine (5-Aza-dC) on the apoptosis of lung adenocarcinoma cells.Methods:In the prospective randomized controlled study, lung adenocarcinoma A549 cells were treated with cisplatin plus paclitaxel (TP) or gemcitabine (GP) with or without 5-Aza-dC. According to different drug intervention methods, they were divided into control group, cisplatin combined with paclitaxel (TP) group, cisplatin combined with gemcitabine (GP) group, and 5-Aza-dC combined with TP group, 5-Aza-dC combined with GP group. CCK-8 assay was used to detect the proliferation of A549 cells. Transwell migration and invasion assay were used to detect the effect that each group of drugs on the migration and invasion ability of A549 cells. Quantitative Real-time Polymerase Chain Reaction was used to evaluate the effect of each treatment on the expression of apoptotic genes. One-way analysis of variance was used to compare the degree of cell proliferation in different drug treatment groups, and LSD- t method was used for pairwise comparison within groups. Results:The inhibition rates of lung adenocarcinoma cells in the TP regimen at different time points at 24, 48, and 72 h were as follows (20.00±4.23) %, (35.00±2.80) %, and (56.00±3.11) %. The inhibition rate of 5-Aza-dC combined with TP regimen on lung adenocarcinoma cells was significantly increased, at different time points of 24, 48 and 72 h, respectively (38.00±3.80) %, (50.00±3.25) %, (93.00±4.33) %. The inhibition rates of cells at different time points at 24, 48, and 72 h in the GP regimen were (33.00±5.10) %, (54.00±3.80) %, and (74.00±2.82) %, respectively; while 5-Aza-dC combined with GP regimen could significantly reduce the rate of cell growth, the inhibition rates of cells at 24, 48, and 72 h different time points were as follows (54.00±3.00) %, (67.00±5.30) %, and (95.00±1.13) %. The inhibitory effect of the same drug on lung adenocarcinoma cells increased with time (TP group: F=35.93, P<0.001; 5-Aza-dC combined with TP group: F=97.33, P<0.001; GP group: F =41.73, P<0.001; 5-Aza-dC combined with GP group: F=79.00, P<0.001), and at different time points, the differences were statistically different (all P<0.05). 5-Aza-dC combined with TP and GP chemotherapy regimens can inhibit the migration and invasion of lung adenocarcinoma cell A549, and the inhibitory effect is stronger than that of TP or GP regimens alone. The expression of Caspase 8 was significantly elevated ( t=5.87, P=0.004) in cells treated with 5-Aza-dC combined with GP when compared with GP regimen alone. The expression of Caspase 8 ( t=3.94, P=0.017), Caspase 6 ( t=5.81, P=0.004) and BBC3 (BCL-2 binding component 3) ( t=6.53, P=0.003) were increased when drugged with 5-Aza-dC combined TP regimen compared with TP regimen alone. Conclusion:5-Aza-dC might serve as a chemotherapeutic sensitizer to increase the sensitivity of lung adenocarcinoma cells.

RNA methylation and cancer treatment.

To this date, over 100 different types of RNA modification have been identified. Methylation of different RNA species has emerged as a critical regulator of transcript expression. RNA methylation and its related downstream signaling pathways are involved in plethora biological processes, including cell differentiation, sex determination and stress response, and others. It is catalyzed by the RNA methyltransferases, is demethylated by the demethylases (FTO and ALKBH5) and read by methylation binding protein (YTHDF1 and IGF2BP1). Increasing evidence indicates that this process closely connected to cancer cell proliferation, cellular stress, metastasis, immune response. And RNA methylation related protein has been becoming a promising targets of cancer therapy. This review outlines the relationship between different types of RNA methylation and cancer, and some FTO inhibitors in cancer treatment.