The embryonic transcription factor brachyury confers chordoma chemoresistance via upregulating CA9

Being a rare malignant bone tumor on the axial skeleton, chordoma is locally invasive and has a high rate of recurrence. Despite extensive studies, the mechanisms of chordoma recurrence after surgical intervention, as well as resistance to radiation and chemotherapy, remain elusive. In this study, primary chordoma cell lines PCH1 and PCH2 were established and characterized by chordoma specific markers. We found that the embryonic transcription factor Brachyury inhibits Paclitaxel induced apoptosis in different cells, including PCH1 and U2OS cells. T gene regulated genes were identified in PCH1 and U2OS using microarray. After comparing gene regulated by Brachyury in different cells and the chromatin immunoprecipitation assay, we identified carbonic anhydrase IX (CA9) as a common target gene of Brachyury. Besides, immunohistochemical staining of CA9 and Brachyury in chordoma tissues revealed that their expression levels were positively correlated. We further showed that CA9 is responsible for Paclitaxel resistance in PCH1 cell. Our data suggest that CA9 plays a role in Brachyury mediated Paclitaxel resistance and serves as a potential target for chordoma treatment.