[Frontiers in Bioscience E3, 240-249, January 1, 2011]

DNA methyltransferase inhibitor CDA-2 synergizes with high-dose thiotepa and paclitaxel in killing breast cancer stem cells

Zhihao Lu1, Jun Jia1, Lijun Di1, Guohong Song1, Yanhua Yuan1, Bo Ma1, Jing Yu1, Yulin Zhu1, Xiaoli Wang1, Xinna Zhou1, Jun Ren1

1Department of Medical Oncology, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education, China), Peking University School of Oncology, Beijing Cancer Hospital and Institute, China


1. Abstract
2. Introduction
3. Material and Methods
3.1. Cell lines and Cell culture.
3.2. ATP Bioluminescence Assay
3.3. Detection the Activity of Hh Pathway by RT-PCR Method
3.4. Statistical Analysis
4. Results
4.1. CD44+/ CD24-/low CSCs in MCF-7 and MDA-MB-231 Cell Lines
4.2. CDA-2 Inhibiting Proliferation of CD44+/CD24-/low CSCs
4.3. CDA-2 Down-regulating Activity of SHH Pathway
4.4. Higher Concentration Thiotepa and Paclitaxel Except for Anthracycline Inhibiting the Proliferation of CSCs
4.5. CDA-2 Synergized the Activity of Thiotepa and Paclitaxel to Inhibit Proliferation of CSCs
5. Discussion
6. Acknowledgement
7. References


It has been suggested that breast cancer stem cells (CSCs), which characterized by CD44+CD24-/low, may result in treatment failure in patients with breast cancer. It is possible therefore that that inhibiting such subpopulation might subsequently improve clinical outcome. In the present study, we found that the CD44+/CD24-/low CSCs, isolated from both human breast cell line MCF-7 and MDA-MB-231, were more resistant to thiotepa, paclitaxel and anthracycline, when compared with the non-breast cancer stem cell subset from the same cell lines, whereas the chemosensitivities were remarkably reversed by higher concentration of thiotepa and paclitaxel except for adriamycin. The percentage of CSCs was significantly decreased with an addition of DNA methyltransferase inhibitor CDA-2 and the expression of Smo, Shh, and Gli-1 of Hedgehog signaling pathway in CSCs was decreased. Of important findings, combination of thiotepa or paclitaxel with CDA-2 could significantly inhibit the proliferation of CSCs regardless of their dosages. These results unveiled that the selection of cytotoxic agents and increasing their dosage might be of great importance in the respect of eliminating CSCs. DNA methyltransferase inhibitor CDA-2 exhibited a synergistic effect with cytotoxic drugs, which might provide a conceptually new therapeutic strategy.