Abstract: Multidrug resistance (MDR) is the main obstacle for cancer to cure, failure of chemotherapy and relapse. Cancer stem cells (CSCs) are driven force for tumorigenesis, the evolution of metastasis and recurrence, and the most fundamental reason for cancer drug-resistance. The primary drug resistance mechanism including: ABC transporters strengthening CSCs drug resistance, high level expression of the anti-apoptotic genes, DNA repair capacity enhancement and hypoxic niches, and so on. To study CSCs biological characteristics and clarify the resistance molecular mechanisms, and to develop a targeted therapy for CSCs, and then to overcome and reverse the multidrug resistance of CSC, will enhance cancer cure rate and reduce the relapse rate.

Key words: Neoplastic stem cells, Chemotherapy, adjuvant, Drug tolerance