Overexpression of MAGEA4 oncogene has been demonstrated in different malignancies; however, little is known about its exact mechanism for overexpression. TWIST1, as a bHLH transcription factor, activates a cell migration-invasion program involved in both embryonic and tumor development. Since MAGEA4 overexpression was statistically correlated to TWIST1, we aimed to elucidate the probable regulatory role of TWIST1 on MAGEA4 expression in KYSE30 cells.
Methods: Expression pattern of MAGEA4 and TWIST1 was analyzed in 55 ESCC patients using relative comparative real-time PCR. In silico analysis of the MAGEA4 gene was performed. Methylation status of MAGEA4 promoter was determined by quantitative methylation specific PCR (qMSP). Using a retroviral system, KYSE30 cells were transduced to ectopically express TWIST1, followed by qRT-PCR, Western blot analysis, chromatin immunoprecipitation (ChIP), and luciferase assays to elucidate the regulatory role of TWIST1 on MAGEA4 gene expression.
Results: Concomitant overexpression of MAGEA4 and TWIST1 was detected in ESCC in significant correlation with each other in different clinicopathological indices of poor prognosis (P < 0.05). The TWIST1-expressing cells showed significantly higher MAGEA4 expression compared to control cells. ChIP and luciferase assays results confirmed indirect binding of TWIST1 to the E-boxes of MAGEA4 promoter sequence and revealed a novel regulatory role of TWIST1 in MAGEA4 upregulation.
Conclusion: Since MAGEA4 is a highly expressed oncogene in a variety of malignancies in significant correlation with tumor cell invasiveness and aggressiveness, our finding may help understand one regulatory mechanism of increased expression in tumor cells. © 2016 Wiley Periodicals, Inc.
Keywords: E-box; MAGEA4; TWIST1; cancer testis antigens; esophageal squamous cell carcinoma.
© 2016 Wiley Periodicals, Inc.