MSC and breast tumor cells

MARTINEZ LM; LABOVSKY V; FERNÁNDEZ VALLONE VB; BORDENAVE RH; FELDMAN L; CHASSEING NA

Philadelphia, PA, EEUU

Congreso; Metastasis and the Tumor Microenvironment; 2010

Over the last years, there has been a high interest in the role of bone marrow(BM) mesenchymal stem cells(MSC) in cancer progression. MSC have the plasticity to give rise to a variety of mesenchymal cells such as osteocytes, chondrocytes, adipocytes and fibroblasts.The nature of the relationship between BM-MSC and breast cancer cells (BCC) appears dual. Primary and metastatic tumor attract BM-MSC into the tumor microenvironment where they in part become  tumor associated fibroblasts, modifying tumor cell proliferation, survival, migration, angiogenesis and having immunomodulatory property. MSC may promote BC metastasis through the facilitation of epithelial-mesenchymal transition. In BM the MSC attract BCC and contribute to microenvironment that induces osteolysis, tumor growth, and survival. Whether MSC induce or inhibit tumor growth is a field of oppositive observations that is related by the complexity of their interaction with BCC, bone cells and a large range of soluble factors and extracellular matrix components that MSC and the other cells produce. It is known the importance of OPG, RANKL, TRAIL and M-CSF in the progression of BC, osteoclastogenesis and bone resorption. So, this study was performed to investigate the production of OPG, RANKL, TRAIL and M-CSF in conditioned mediums(CM, days 7 and 14) from CFU-F cultures(1CFU-F=1MSC) of BM from untreated advanced BC patients (BCP, without bone  metastasis) and healthy volunteers(HV). Also, we evaluated the effect of these CM over the proliferation and apoptosis of  2 human BC cell lines: MDA-MB231 and MCF-7. Methodology: soluble factors were quantified by ELISA in CM(days 7 and 14) of CFU-F cultures from BM-BCP and HV. Proliferation assay: after 48hs of arrest without FBS, MDA-MB231 and MCF-7 were incubated for 48hs with only 100% or 50% of these CM of CFU-F cultures from BM-BCP and HV with or without 10% FBS. We analyzed proliferation by performing MTS assay. Apoptosis: after 48hs of arrest without FBS, MDA-MB231 and MCF-7 were incubated for 24hs with or without 50% of these CM of CFU-F cultures from BM-BCP and HV in rhTRAIL(50ng/ml) presence or not. We analyzed apoptosis by flow cytometry with Anexin-V and confirmed the results by Tunel. Results: data showed values of soluble RANKL and TRAIL<31.25pg/ml in the CM of both days, independent of the type of group. However, in previous study we found higher membrane RANKL expression/MSC from BM-BCP compared to HV values (+++vs.++). The levels of M-CSF in the CM of both days were similar between BCP and HV. In contrast, we found significant difference            in the OPG value in 14 day CM between both groups, X± ES(pg/ml) were: BCP=177±40 vs. HV=1,422±264, p<0,05. We have not observed proliferation effect by any of the treatments over any of the lines. We neither observed direct apoptosis effect by these CM, but we did observe an anti-apoptotic effect by the presence of OPG in MDA-MB231 when rhTRAIL was added. Moreover, early apoptosis was significantly lower in cells treated with 14 day CM of CFU-F from BM-HV respect to CM of CFU-F from BM-BCP(p=0.0362), but MCF-7 cells did not respond even to TRAIL apoptotic effect. Conclusion: results showed that  pure CM of CFU-F cultures(days 7 and 14) from BM-BCP and HV did not modified the  proliferation potential and apoptosis of MDA-MB231 and MCF-7.  It is possible that BCC need a direct interaction with MSC to modified its behavior. However, we  found an anti-apoptotic effect by the presence of OPG in MDA-MB231 when rhTRAIL was added. The low anti-apoptotic effect of BCP-CM(day14) compared to HV-CM may be explained by the fact that probably at advanced stages of BC development the most important function of MSC is to regulate the osteoclastogenesis and bone resorption processes.