Activin A induces erythroid gene expressions and inhibits mitogenic cytokine‐mediated K562 colony formation by activating p38 MAPK

Abstract

Activin A, a member of the transforming growth factor (TGF)-beta superfamily, is involved in the regulation of erythroid differentiation. Previous studies have shown that activin A inhibited the colony-forming activity of mouse Friend erythroleukemia cells, however, the mechanism remains unknown. First, we show herein that activin A induced the expression and activated the promoters of alpha-globin and zeta-globin in K562 cells, confirming that activin A induces erythroid differentiation in K562 cells. The p38 mitogen activated protein kinase (MAPK) inhibitor, SB203580, inhibited and the extracellular signal regulated kinase (ERK) inhibitor, PD98059, enhanced the expression and promoter activities of alpha-globin and zeta-globin by activin A, indicating that p38 MAPK and ERK are crucial for activin A-induced erythroid genes expression. Second, SB203580 inhibited the inhibitory effect of activin A on the colony-forming activity of K562 cells using the methylcellulose colony assay, indicating that activin A inhibits K562 colony formation by activating p38 MAPK. In addition, mitogenic cytokines SCF, IL-3, and GM-CSF induced colony formation of K562 cells that could be inhibited by PD98059 or enhanced by SB203580, respectively, indicating that these mitogenic cytokines induce K562 colony formation by activating ERK and inactivating p38 MAPK. Furthermore, activin A reduced the induction effect of these mitogenic cytokines on K562 colony formation in a dose-dependent manner. The inhibition of p38 MAPK reverted the inhibitory effect of activin A on mitogenic cytokine-mediated K562 colony formation. We conclude that activin A can regulate the same pathway via p38 MAPK to coordinate cell proliferation and differentiation of K562 cells.

c‐Jun blocks cell differentiation but not growth inhibition or apoptosis of chronic myelogenous leukemia cells induced by STI571 and by histone deacetylase inhibitors

“…To examine the transcriptional activity of a-globin and z-globin genes, we used transient transfection of K562 cells with reporter constructs expressing the luciferase gene under the control of a-globin or z-globin promoters, pHS40-a590Luc or pHS40-z597Luc (Huang et al, 2006). The relative luciferase activities of the reporters activated under STI571 treatment were referenced to the reporter activity under untreated control (normalized as 1).…”

“…Reporter plasmids containing pHS40-a590 Luc or pHS40-z597 Luc (1 mg, Huang et al, 2006) and pRL-TK internal control vector (0.05 mg) were cotransfected with or without pCMV-c-Jun (1 mg), pCMV-TAM-67 (1 mg) or its control vector (1 mg). For STI571 treatment, 1 mM STI571 was added to the culture medium at 5 h post-transfection.…”

“…Total cell extracts were prepared as described (Huang et al, 2006). Protein lysate (50 mg) was resolved using SDS-polyacrylamide gel electrophoresis (PAGE), transferred to PVDF membranes (Millipore, Bedford, MA), then probed with primary antibodies.…”

Cell-Cell Communication Networks Propose a Modulation of the Hematopoietic Stem Cell Niche by Invading Breast Carcinoma Cells

“…Overall, cell-cell communication networks presented MSC as a crucial part of the HSC niche, since the factors provided from MSC to HSPC (INHBA/Inhibin-βA, CSF1/M-CSF, CXCL12/SDF-1) are reported to affect key features that regulate the stem cell pool such as proliferation, differentiation, mobilization and homing of HSPC [9,16,18,21,[44][45][46][47][48][49].…”

“…INHBB/Inhibin-βB, CSF1/M-CSF, PDGFB/PDGF-BB and PLAU/uPA were directed from BCC to HSPC (Figure 2). All those signals have the potential to modulate the physiological differentiation and proliferation of HSPC or are associated with the induction of myeloproliferative disease [44][45][46][47][50][51][52][53][54]. Moreover, M-CSF is reported to induce tumor associated macrophages [55].…”