Bone marrow ‐ mesenchymal stem cells impact on the U937 cells in the presence of staphylococcal enterotoxin B (SEB)

The growing resistance against conventional chemotherapy in acute myeloid leukemia (AML) is a noticeable clinical concern. Therefore, many researchers are looking for novel substances to overcome drug resistance in cancer. Staphylococcal enterotoxin B (SEB) is a superantigen (SAg) and a promising compound which has lethal effects on malignant cells. In this unprecedented study, SEB was used against U937 cells in a co‐culture system in the presence of human bone marrow‐mesenchymal stem cells (hBM‐MSCs). The effects of hBM‐MSCs on the proliferation and survival of U937 cell line with SEB was assessed using MTT assay and AnnexinV/PI flowcytometry, respectively. Moreover, the expression of IL‐6, IL‐10, TGF‐β, and inhibitor of nuclear factor kappa‐B kinase (IKKb) was evaluated by real‐time PCR technique. The same experiments were also carried out using hBM‐MSCs‐conditioned medium (hBM‐MSCs‐CM). The results showed that SEB reduced the proliferation and survival of U937 cell line, but hBM‐MSCs or hBM‐MSCs‐CM suppressed the effects of SEB. Furthermore, real‐timePCR demonstrated that SEB could decrease the expression of IL‐6, IL‐10, and TGF‐β in hBM‐MSCs (P < .05), while the production of IKKb was increased in comparison with the control group. These findings help us to have a broader understanding ofthe usage of SEB in the treatment of haematological malignancies, especially if it is targeted against hBM‐MSCs to disrupt their supportive effects on malignant cells.