5-Aza-2'-deoxycytidine inhibiting metastasis to lungs of triple-negative breast cancer cells

Objective To investigate the effect of 5-Aza-2'-deoxycytidine (5-Aza-CdR) on metastasis to lungs of triple-negative breast cancer (TNBC) MDA-MB-231 cells and the mechanisms. Methods MDA-MB-231 cells were divided into two groups: control group and 5-Aza-CdR-treated group. The mRNA expression and promoter methylation status of breast cancer metastasis suppressor-1 (BRMS1 ) and CXC chemokine receptor-4 (CXCR4) in the MDA-MB-231 cells were evaluated by semi-quantitative reverse transcription-polymerase chain reaction ( SqRT-PCR) and methylation specific polymerase chain reaction (MSP) respectively. Then 2 x 105 cells were injected into each BALB/C nu/nu mouse (5 mice in each group) through lateral tail veins. Five weeks later, the metastasis of lungs was evaluated through the mRNA abundance of the target gene HPRT in the lungs tissue from the mice detected by fluorescent quantitative RT-PCR (FqRT-PCR). Results 5-Aza-CdR up-regulated the BRMS1 mRNA expression [0 versus 0. 390 ±0. 001 (relative integrated density value, IDV against GAPDH) ,P ＜0. 05] and demethylated the methylated CpG island B in promoter, while the CXCR4 mRNA expression (0. 580 ±0. 003 versus 0. 580 ±0. 010,P＞0. 05) and the status of unmethylated CXCR4 CpG island 1 in promoter had no significant change. The Ct values of HPRT and GAPDH in control and 5-Aza-CdR-treated groups were 24. 75 ± 1. 55,16. 19 ±0. 69 versus 27. 61 ± 1. 67, 17. 48 ±0. 96 respectively, 2-△△Ct =0. 34, and the inhibitory rate of metastasis was 66% . The mRNA abundance of the HPRT was lower and there were fewer metastases in the lungs of 5-Aza-CdR-treated group than in control group. Conclusion 5-Aza-CdR reactivated tumor metastasis suppressor gene BRMS1 and decreased the metastasis to lungs of TNBC MDA-MB-231 cells by demethylation mechanism. Key words: 5-Aza-CdR; Methylation; Breast carcinoma; Metastasis