Sodium caseinate induces expression and secretion of murine multipotent myeloid cell line 32D macrophage colony-stimulating factor

Evidence that sodium caseinate (CasNa) is capable of inhibiting proliferation of hematopoietic precursor cell line 32D and inducing its differentiation into macrophage cells has recently been published. Taking into consideration that hematopoiesis is regulated by growth factors and that macrophage colony-stimulating factor (M-CSF) is a well-known growth factor that induces differentiation of macrophages, in this work we evaluated whether CasNa is capable of inducing expression and secretion of M-CSF in 32D cells. We cultured 32D cells in presence and absence of CasNa and compared their proliferation and viability. RNA was extracted from cell lysates to evaluate expression of the gene for M-CSF and its receptor. Cultured conditioned media was used to evaluate presence of M-CSF. Our results showed that CasNa inhibited proliferation of 32D cells and that conditioned media (CM) of these cultures contained M-CSF-like activity. Presence of M-CSF in CM was detected by inhibiting M-CSF activity with anti-M-CSF and presence of this growth factor was confirmed by ELISA assay. We also provided evidence that CasNa induced expression of mRNA for M-CSF in 32D cells as well as increased expression of mRNA for its receptor. CasNa inhibits proliferation of 32D cells and induces expression of the gene for M-CSF and that of its receptor. It also induces secretion of the bioactive form of M-CSF.