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In Vitro Hypoxic Preconditioning of Bone Marrow Stromal Cells Triggers ERK-Mediated Signaling and Growth of L363 Myeloma Cells
Georgiana Grigore, Mihaela Zlei, Dragos Peptanariu, Iuliu Ivanov, Didona Ungureanu, Eugen Carasevici
Abstract: Multiple myeloma (MM) remains incurable, therefore the nature of events linked to disease progression still needs to be deciphered. Objective: We sought to investigate whether hypoxia [low oxygen (O2) pressure] and bone marrow (BM) stroma, well-documented factors with substantial role in tumor maintenance, can functionally mimic myeloma microenvironment in vitro. Materials and methods: L363 MM cells were cultured for 24/72 hours under different settings. Normoxia (21% O2), extreme (1.5% O2) and moderate (6.2% O2) hypoxia and BM stromal cells were tested for their impact on L363 cell viability, proliferation and intracellular phospho(p)-ERK expression, either individually, or in combination. All parameters under study were analyzed by flow cytometry and compared to standard L363 cultures (no stroma, no hypoxia). Results: When used as independent factors, neither hypoxia, nor the presence of BM stroma significantly affected the viability, proliferation or expression level of p-ERK in L363 cell cultures (24 hours). Nevertheless, when combined, the viability of L363 cells was restored to the levels recorded in paired standard cultures, proliferation significantly accelerated (p=0.0083), and p-ERK expression significantly augmented (p=0.014). This last effect was observed only when moderate hypoxia was used in combination with BM stroma. Our findings suggest that hypoxic preconditioning activate the bone marrow stroma and consequently enhance L363 cell growth through ERK-mediated intracellular signaling. Conclusion: Suitable combination of culture settings provided substantial growth benefits to MM cells in our study. Hypoxic conditions bring about an indirect magnifying growth signal to L363 cells by promoting a stimulatory stromal microenvironment.
Keywords: multiple myeloma,microenvironment,hypoxia,bone marrow stroma
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Grigore G, Zlei M, Peptanariu D, Ivanov I, Ungureanu D, Carasevici E. In Vitro Hypoxic Preconditioning of Bone Marrow Stromal Cells Triggers ERK-Mediated Signaling and Growth of L363 Myeloma Cells. Rev Romana Med Lab. 2011;19(1):75-84
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