Silencing of BEX2 promotes colorectal cancer metastasis through Hedgehog signaling pathway

Colorectal cancer is one of the most common cancers worldwide with increasing incidence, the presence of metastasis is one of the major causes for poor outcome. BEX2 has been reported to be involved in tumor development in several types of cancer, but is poorly understood in metastatic colorectal cancer. Here we demonstrated that knockout of BEX2 resulted in the enhancement of the migratory and metastatic potential of colorectal cancer cells in vivo and in vitro, re-expression of BEX2 in knockout cells could reverse the migratory enhancement. Expression profile chip indicated that hedgehog signaling pathway was activated after knockout of BEX2, and hedgehog Signaling inhibitor GANT61 and GDC-0449 could somehow reverse the migratory enhancement of BEX2-/- colorectal cancer cells. We also demonstrated that it is the nucleus translocation of Zic2 after BEX2 silenced, that activated hedgehog signaling pathway, while knockdown Zic2 could also abrogated migratory enhancement of BEX2-/- cells. In summary, our findings suggest that BEX2 is a negative modulator of hedgehog signaling pathway by retaining Zic2 in the cytoplasm of colorectal cancer cells, thus to inhibit colorectal cancer cell migration and metastasis. Overall design: mRNA profiles of colorectal cancer cell DLD1 (WT) and BEX2 knocked out DLD1 cells (DLD1 KO1 and DLD1 KO2) were generated by deep sequencing, using Illumina Hiseq 3000.