Low concentrations of 5-aza-2′-deoxycytidine induce breast cancer stem cell differentiation by triggering tumor suppressor gene expression

Nhan Lu-Chinh Phan, Ngu Van Trinh, Phuc Van Pham

Laboratory of Stem Cell Research and Application, University of Science, Vietnam National University, Ho Chi Minh City, Vietnam

Background: Breast cancer stem cells (BCSCs) are considered the cause of tumor growth, multidrug resistance, metastasis, and recurrence. Therefore, differentiation therapy to reduce self-renewal of BCSCs is a promising approach. We have examined the effects of 5-aza-2′-deoxycytidine (DAC) on BCSC differentiation.
Materials and methods: BCSCs were treated with a range of DAC concentrations from 0.625 to 100 µM. The differentiation status of DAC-treated BCSCs was graded by changes in cell proliferation, CD44+CD24- phenotype, expression of tumor suppressor genes, including BRCA1, BRCA2, p15, p16, p53, and PTEN, and antitumor drug resistance.
Results: DAC treatment caused significant BCSC differentiation. BCSCs showed a 15%–23% reduction in proliferation capacity, 3.0%–21.3% decrease in the expression of BCSC marker CD44+/CD24-, activation of p53 expression, and increased p15, p16, BRCA1, and BRCA2 expression. Concentrations of DAC ranging from 0.625 to 40 µM efficiently induce cell cycle arrest in S-phase. ABCG2, highly expressed in BCSCs, also decreased with DAC exposure. Of particular note, drug-sensitivity of BCSCs to doxorubicin, verapamil, and tamoxifen also increased 1.5-, 2.0-, and 3.7-fold, respectively, after pretreatment with DAC.
Conclusion: DAC reduced breast cancer cell survival and induced differentiation through reexpression of tumor suppressor genes. These results indicate the potential of DAC in targeting specific chemotherapy-resistant cells within a tumor.

Keywords: breast cancer, breast cancer stem cells, differentiation, epigenetics, 5-aza-2′-deoxycytidine

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