Suppression of human breast tumors in NOD/SCID mice by CD44 shRNA gene therapy combined with doxorubicin treatment

Pham PV, Vu NB, Duong TT, Nguyen TT, Truong NH, Phan NLC, Vuong TG, Pham VQ, Nguyen HM, Nguyen KT, Nguyen NT, Nguyen KG, Khat LT, Le DV, Truong KD, Phan NK

Published Date May 2012 Volume 2012:5 Pages 77 – 84

DOI: http://dx.doi.org/10.2147/OTT.S30609

Phuc Van Pham¹, Ngoc Bich Vu¹, Thuy Thanh Duong¹, Tam Thanh Nguyen¹, Nhung Hai Truong¹, Nhan Lu Chinh Phan¹, Tue Gia Vuong¹, Viet Quoc Pham¹, Hoang Minh Nguyen¹, Kha The Nguyen¹, Nhung Thi Nguyen¹, Khue Gia Nguyen¹, Lam Tan Khat¹, Dong Van Le², Kiet Dinh Truong¹, Ngoc Kim Phan<sup>1

1</sup>Laboratory of Stem Cell Research and Application, University of Science, Vietnam National University, HCM City, ²Military Medical University, Ha Noi, Vietnam

Background: Breast cancer stem cells with a CD44⁺CD24^– phenotype are the origin of breast tumors. Strong CD44 expression in this population indicates its important role in maintaining the stem cell phenotype. Previous studies show that CD44 down-regulation causes CD44⁺CD24^– breast cancer stem cells to differentiate into non-stem cells that are sensitive to antitumor drugs and lose many characteristics of the original cells. In this study, we determined tumor suppression in non-obese severe combined immunodeficiency mice using CD44 shRNA therapy combined with doxorubicin treatment.
Methods: Tumor-bearing non-obese severe combined immunodeficiency mice were established by injection of CD44⁺CD24^– cells. To track CD44⁺CD24^– cells, green fluorescence protein was stably transduced using a lentiviral vector prior to injection into mice. The amount of CD44 shRNA lentiviral vector used for transduction was based on CD44 down-regulation by in vitro CD44 shRNA transduction. Mice were treated with direct injection of CD44 shRNA lentiviral vector into tumors followed by doxorubicin administration after 48 hours. The effect was evaluated by changes in the size and weight of tumors compared with that of the control.
Results: The combination of CD44 down-regulation and doxorubicin strongly suppressed tumor growth with significant differences in tumor sizes and weights compared with that of CD44 down-regulation or doxorubicin treatment alone. In the combination of CD44 down-regulation and doxorubicin group, the tumor weight was significantly decreased by 4.38-fold compared with that of the control group.
Conclusion: These results support a new strategy for breast cancer treatment by combining gene therapy with chemotherapy.

Keywords: breast cancer, breast cancer stem cells, CD44, doxorubicin, gene therapy