Telomerase inhibition regulates EMT mechanism in breast cancer stem cells

Backround: CSCs having the common features of high telomerase activity and high migration and invasion capabilities play a vital role as the initiators of metastasis. Small molecule BIBR1532 has been shown to target cancer cells by inhibiting telomerase. Recent studies have suggested that telomerase activity is associated with epithelial mesenchymal transition (EMT). EMT program, which causes epithelial cells to acquire a mesenchymal morphology, is known to play a significant role in cancer metastasis. Methods: The hypothesis of our study was that suppression of telomerase in breast cancer and cancer stem cells would interrupt EMT mechanism. Cytotoxicity of BIBR1532 was evaluated using WST-1 assay in all cell lines and the effects of BIBR1532 on apoptosis were investigated with Annexin V. Migration rate of the cells was examined by wound healing assay and sphere forming capacities were observed by hanging drop test. Finally, the expression of 84 EMT-related genes was analyzed by real-time qPCR. Results: The IC50 values for the MDA-MB-231 and breast epithelial stem cells of BIBR1532 were analyzed as 18.04 and 38.71 mu l at 72 h, respectively. Interestingly, apoptosis was only induced in stem cells. In hanging drop test, sphere areas were reduced in stem cells treated with BIBR1532. In wound healing assay, BIBR1532 decreased the migration rate of stem cells. Together with this, expression of EMT-related genes were regulated in stem cells towards a epithelial phenotype. Conclusion: Our obtained results indicated that telomerase inhibition affects the EMT mechanism. The targeted elimination of breast cancer stem cells by a telomerase inhibitor in cancer treatment may limit the mobility and stemness of cancer cells interrupting the EMT mechanism, thus may prevent metastasis.