Mesenchymal stem cells within tumor stroma promote breast tumor growth and hormone independence Free

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Adult human mesenchymal stem cells enhance breast cancer tumorigenesis and promote hormone independence
 Adult human mesenchymal stem cells have been shown to home to sites of breast cancer and to integrate into the tumor stroma. While this has been described to influence breast cancer metastasis, here we demonstrated the effect of adult human mesenchymal stem cells on primary tumor growth and the progression of breast tumors to hormone independence. Bone-marrow-derived mesenchymal stem cells mixed with the estrogen receptor positive, hormone-dependent breast carcinoma cell line MCF-7 enhance primary tumor growth as well as promote hormone-independent tumor growth of subcutaneous injections in immunocompromised mice. Our studies have also shown an increased expression of the chemokine Stromal Derived Factor 1 (SDF-1) in these mixed cell tumors as compared to the MCF-7 only tumors. We hypothesize that it is this increase in SDF-1 provided by MSCs that acts in a paracrine fashion on the breast cancer cells which leads to a shift to hormone independent growth while still remaining estrogen sensitive. Taken together, our data reveals the relationship between tumor microenvironment and tumor growth and progression to hormone-independence through the release of stromal factors. This tumor stroma-cell interaction may provide a novel target for the treatment of hormone independent endocrine resistant breast carcinoma.