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

Abstract

BackgroundBreast 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.MethodsTumor-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.ResultsThe 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.ConclusionThese results support a new strategy for breast cancer treatment by combining gene therapy with chemotherapy.

Breast cancer stem cells: Multiple capacities in tumor metastasis

“…They identified and isolated a small subset of cells within primary breast cancer cells of which a few cancer cells were able to form palpable tumors in the mammary fat pad of non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Such cells express CD44 or CD44 with epithelial specific antigen (ESA), but not CD24, consistent with the phenotypic characteristics of mammary stem cells with multipotent differentiation ability [33, 34]. Nevertheless, although these results demonstrate the possibility that BCSCs originate from the normal mammary stem cells, it is generally accepted that further genomic profiling and comparison of the normal stem cells versus BCSCs should provide insightful information on the aggressive phenotype of BCSCs.…”

Taraxacum officinale dandelion extracts efficiently inhibited the breast cancer stem cell proliferation

“…The cells were transfected with green fluorescent protein (GFP) using a lentiviral vector, as per the previous protocol (Van Pham et al, 2012). The GFP-BCSCs were grown in cell culture medium (DMEMF12/10% FBS/1% antibiotic-antimycotic) and incubated at 37 o C in a humidified atmosphere with 5% CO2.…”

Cutaneous metastases of breast cancer during adjuvant chemotherapy correlates with increasing CD44+/CD24− and ALDH-1 expression: a case report and literature review

“…However, the latter study (19) also reported that patients with tumors containing high numbers of CD44 + /CD24 − cells more frequently developed bone metastases in the course of the disease. The molecular mechanisms underlying the roles of breast CSCs in chemoresistance have been reported in several studies (20,21) and proposed clinical implication for breast cancer therapeutics (22)(23)(24)(25). The occurrence of a fraction of breast CSCs with increased multidrug resistance (MDR) affinity clinically may be an additional mechanism for the positive selection of breast CSCs during chemotherapy (20).…”