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The online version of this article (doi:10.1186/1475-2867-12-21) contains supplementary material, which is available to authorized users.
A retraction note to this article can be found online at http://dx.doi.org/10.1186/1475-2867-13-96.
An erratum to this article is available at http://dx.doi.org/10.1186/1475-2867-13-96.
There are no competing interests financial or non-financial (political, personal, religious, ideological, academic, intellectual, commercial or any other) to declare in relation to this manuscript.
NJ was jointly responsible for the concept, design and completion of all laboratory studies, IH assisted in the laboratory studies. JE and OE participated in the coordination of the study and helped to draft its manuscript. MES was jointly responsible for the concept, design, coordination of the study and also helped to draft its manuscript. All authors read and approved the final manuscript.
The outcome of chemotherapy in breast cancer is strongly influenced by multidrug resistance (MDR). Several surrogate markers of chemoresistance have been identified including - CD24 (cluster differentiation 24) expression, stem cell growth factor (SCF), B-cell lymphocyte protein 2 (Bcl-2) and annexin V. The present study aimed to examine the expression of CD24 in the sensitive breast cancer cell line MCF-7 (Michigan Foudation-7) and MCF-7/adriamycin resistant (MCF-7/AdrRes) cells, and, if minimal effective doses of the anthracycline drug adriamycin (0.579 μM and 88.2 μM) would be enhanced by the antibody to SCF (anti-SCF).
CD24 expression was analysed by flow cytometry. Both Bcl-2 and annexin V protein expression were quantitatively assessed by the enzyme-linked immunosorbent assay (ELISA).
In MCF-7/AdrRes cells the expression of CD24 was significantly higher compared to MCF-7 cells, 86.6% and 16.3% (p < 0.001), respectively. Bcl-2 expression was significantly increased in the presence of adriamycin and SCF (p < 0.038) and decreased in the presence of adriamycin and anti-SCF. When adriamycin, anti-SCF and SCF were combined or when adriamycin was used alone the decrease in Bcl-2 expression was insignificantly altered. In the presence of both adriamycin and SCF the expression of annexin V was decreased. However, it was significantly increased in the presence of adriamycin and anti-SCF (p < 0.042), as well as adriamycin, anti-SCF and SCF combined.
In MCF-7 cells the effect of adriamycin alone or with either SCF, anti-SCF or anti-SCF or SCF combined, did not significantly alter the expression of Bcl-2. However, in the presence of both adriamycin and SCF the expression of annexin V was decreased, but was significantly increased in the presence of adriamycin and anti-SCF (p < 0.001), adriamycin, anti-SCF and SCF combined and adriamycin alone. Our results demonstrate that anti-SCF with low dose of adriamycin reduces Bcl-2 expression in MCF-7/AdrRes cells and increases annexin V expression in both MCF7/AdrRes and MCF-7 cells.
Adding anti-SCF to the chemotherapeutic regime of adriamycin may strongly enhance its chemotherapeutic effect in the treatment of patients with breast cancer.