In:
Cell Communication and Signaling, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2011-12)
Abstract:
Phorbol ester (TPA) treatment of human U937 myeloid leukemia cells is associated with increasing adherence and monocyte-like maturation whereby the role of β 2 integrin-mediated attachment for subsequent growth properties and the differentiation program remains unclear. Here, stably-transfected U937 cells with a pMTH1 vector containing the β 2 integrin gene of CD11b in antisense orientation (asCD11b-U937) demonstrated a significantly reduced proliferative capacity in contrast to control vector transfectants (pMTH1-U937) or wild-type U937 cells. Phorbol ester exposure induced adherence and growth arrest in more than 90% of pMTH1-U937 and wild-type U937 cells after 72 h. In contrast, TPA-treated asCD11b-U937 failed to attach and the proliferation continued in more than 30% of the cells. Moreover, increased apoptosis appeared in asCD11b-U937 after TPA induction in contrast to pMTH1-U937 cells. In addition, non-specific inhibition of adherence on an agarose surface demonstrated internucleosomal DNA fragmentation in both, pMTH1-U937 and asCD11b-U937 after TPA treatment indicating a functional relationship between abolished adherence, regulation of proliferation and induction of apoptosis. Western blot analysis revealed differences in the expression levels and altered phosphorylation patterns of Pyk-2, pp60src and p42/p44 MAP kinases between pMTH1-U937 and asCD11b-U937 following TPA exposure which was also substantiated by Pyk-2 immunoprecipitation. These findings suggested that induced adherence predominantly mediated by a functional CD11b/CD18 integrin in U937 cells is involved in the activation of downstream signaling kinases and contributes to cell cycle regulation and apoptosis during monocytic maturation.
Type of Medium:
Online Resource
ISSN:
1478-811X
DOI:
10.1186/1478-811X-9-20
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2011
detail.hit.zdb_id:
2126315-2
SSG:
12
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