Novel Interaction In Epithelial-Mesenchymal Transition (EMT) Pathway Of Esophageal Squamous Cell Carcinoma

TWIST1 is a highly conserved bHLH transcription factor. It activates a cell migration-invasionprogram called epithelial mesenchymal transition (EMT). As a potent oncogene, TWIST1 allowsepithelial cells to convert to a mesenchymal fate while avoiding cell death. MAGEA4 is a germ-linegene belongs to a large group of cancer testis antigens (CTAs). Aberrant expression of MAGEA4 isfrequently observed in a large variety of tumors and relatively little is known about the mechanisms ofthis process. Since MAGEA4 and TWIST1 have oncogenic roles in tumorigenesis, progression, andaggressiveness of esophageal squamous cell carcinoma (ESCC), our aim in this study was to elucidatethe possible linkage between these genes in the disease. Expression of TWIST1 and MAGEA4mRNA was analyzed in 40 ESCC patients. ESCC cell line, KYSE30, was transducted with preparedretroviral particles containing TWIST1. Gene expression analysis was performed on stabletransducted cells using Real-time PCR and western blotting. Chromatin immunoprecipitation (CHIP)was also carried out to confirm functional study. TWIST1 and MAGEA4 were overexpressed inmajority of ESCC samples in significant correlation with each other as well as lymph node metastasisand stage of tumor progression. Enforced expression of TWIST1 using retroviral particles upregulatedMAGEA4 expression in KYSE-30 cells nearly 6 folds in comparison with control cells.CHIP analysis showed significant attachment of TWIST1 protein to the MAGEA4 promoter sequencein transducted cells compared to the control. MAGEA4 is a highly expressed CTA in majority ofESCC correlating with different indices of poor prognosis. This study proposes new mechanism forregulation of MAGEA4 expression in cancer cells. Regulatory role of TWIST1 on MAGEA4 mayhighlight the probable crosstalk between EMT process and CTAs expression in ESCC and reveal thepossible coordination of these proteins in aggressiveness and metastasis of the disease.

Keywords:

TWIST1 , MAGEA4 , Cancer testis antigens , Esophageal squamous cell carcinoma