Abstract
Stromal cell monolayers have been an important means of studying the regulation of hematopoiesis, because they produce cytokines. Cytosine arabinoside, vincristine, daunorubicin, and doxorubicin are common drugs for hematological cancer therapy, and they may have some effects on bone marrow stroma during chemotherapy. The aim of this study was to elucidate interactions between the bone marrow stromal microenvironment and leukemic cells after drug treatment. We tested the hypothesis that human HS-5 stromal cells, pretreated with anticancer drugs, affected the growth of leukemic K562 cells by changing the cytokines in the culture microenvironment. Thereafter, proliferation of K562 cells increased nearly 2.5-fold compared the co-cultivation with drugs-pretreated HS-5 stromal cells and drugs-untreated HS-5 stromal cells. The results indicated that co-cultivation with HS-5 stromal cells pretreated with drugs caused significant K562 cell proliferation. Cytokines in the microenvironment were detected via the RayBio((R))Human Cytokine Antibody Array Membrane. The levels of the cytokines CKbeta, IL-12, IL-13, IGFBP-2, MCP-1, MCP-3, MCP-4, MDC, MIP-1beta and MIP-1delta were decreased, with a particularly marked decrease in MIP-3alpha. In co-culture medium, there was a 20-fold decrease in MIP-3alpha in daunorubicin-pretreated HS-5 cells and at least a 3-fold decrease in Ara-C-pretreated cells. This indicated a significant effect of anticancer drugs on the stromal cell line. Using phosphorylated Erk and pRb proteins as cell proliferation markers, we found that phosphorylation of these markers in K562 cells was inhibited during co-cultivation with drug-pretreated stromal cells in MIP-3alpha-supplemented medium and restored by MIP-3alpha antibody supplement. In conclusion, anticancer drug pretreatment suppresses the negative control exerted by HS-5 cells on leukemic cell proliferation, via modulation of cytokines in the microenvironment, especially at the level of MIP-3alpha.