Abstract Background The occurrence and progression of various solid tumors are associated with the melanoma-associated antigen A (MAGE-A) family. Although it was demonstrated that demethylation at the promoter region usually causes the over-expression of the MAGE-A family, there has been very few research about the detailed mechanisms of how the genetic modification of promoter region promotes MAGE-A expression.Methods A new non-coding RNA (ncRNA) with the ability of binding with melanoma-associated antigen-A6 (MAGE-A6) promoter region was discovered. The expression consistency between MAGE-A6 and this novel ncRNA in different MAGE-A6 highly expressed malignant cell lines was analyzed by RT-qPCR. The full length of this ncRNA was acquired through RACE and were subsequently named as MAGEA6-DT1. Then up- and down-regulation of MAGEA6-DT1 in human malignant melanoma cells were achieved by lentivirus transduction and siRNA transfection respectively and the transcription and expression of MAGE-A6 was detected by RT-qPCR and Western Blot for verifying MAGE-A6 expression regulating function of MAGEA6-DT1. The exact binding site of MAGEA6-DT1 in MAGE-A6 promoter region was analyzed by dual-luciferase reporter system assay after MAGEA6-DT1 transfection in 293T cells. Moreover, by DNA methylation analysis, we tested whether MAGEA6-DT1 has the ability of MAGE-A6 expression regulation by manipulating its promoter region’s methylation. Finally, RNA pull-down assay was performed to identify the functional binding partner of MAGEA6-DT1.Results MAGEA6-DT1 was identified as a long non-coding RNA (lncRNA) with the length of 771 nucleotides and was abnormally expressed in consistency with MAGE-A6 among various cancer cell lines. Manipulation of MAGEA6-DT1 expression level would positively regulates MAGE-A6 expression. Specific binding site of MAGEA6-DT1 located near the enhancer of MAGE-A6, and its function was revealed to demethylate DNA near its binding site, probably with the assistance of relevant binding partners.Conclusion MAGEA6-DT1, as a lncRNA abnormally expressed in different malignant cell lines, could positively regulate MAGE-A6 expression via specifically combining with and subsequently demethylating MAGE-A6 enhancer. This function may be assisted by some of its binding protein such as DNA (cytosine-5)-methyltransferase 1 (DNMT1).

Esophageal carcinoma (EC) is the sixth most deadly of all cancers. It is among the most malignant cancers due to its highly aggressive nature and low survival rate. The incidence of EC is high in Asia, particularly in Southern areas including China, Iran and Japan. There is a large body of evidence to suggest an association between the melanoma antigen gene (MAGE) family and the initiation of cancer; however, there is no clear evidence to suggest an association between EC and MAGE. Discovery of the chemical and physiological processes relevant to the occurrence of EC is vital for clinicians to diagnose and treat this highly aggressive cancer. The present study focused on the association of EC with the expression of MAGE family member A6 (MAGEA6) at the mRNA and protein levels using gene chip, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. The expression of MAGEA6 in human esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) tissue samples were compared with those in paracancerous tissue. The result of the gene chip assay revealed that as the generation grew, there was a significant increase in MAGEA6 transcription in the esophageal epithelial cell line, SHEE Different ESC cell lines also exhibited a significantly higher transcription of MAGEA6 compared with the HaCaT cell line, as determined via reverse transcription-quantitative PCR. An higher positive rate of MAGEA6 expression in ESCC and EAC tissues was also revealed when compared with paracancerous tissues, as determined via immunohistochemistry. The results indicated that MAGEA6 is highly transcribed and expressed in the development of EC and may therefore serve as a novel biomarker for the diagnosis or treatment of EC.