Modulation of cyclic AMP levels and differentiation by adenosine analogs in mouse erythroleukemia cells

Abstract

Friend virus-transformed mouse erythroleukemia (MEL) cells can be induced to undergo erythroid differentiation by a variety of compounds, including dimethyl sulfoxide (DMSO) and the adenosine analog xylosyladenine. The present studies have monitored the effects of the stable adenosine receptor ligand N6-phenylisopropyladenosine (PIA) on induction of MEL cell differentiation. PIA has been previously shown to stimulate adenylate cyclase activity in rat hepatic and mouse Leydig 1-10 cells as well as inhibit adenylate cyclase in adipocytes. In the present study, PIA was ineffective as an inducer of the differentiated MEL cell phenotype. However, the results demonstrate that PIA inhibits the induction of MEL cell differentiation by DMSO and xylosyladenine. The extent of this inhibition as determined by benzidine staining, induction of globin RNA, and loss of self-renewal capacity was dependent on PIA concentration. The results also demonstrate that PIA induces a rapid and sustained increase in cyclic AMP (cAMP) levels. Furthermore, there was a highly significant correlation between cAMP levels and inhibition of xylosyladenine-induced differentiation (r = 0.962, P less than 0.0005). This relationship is further supported by the demonstration that prostaglandins E1 and E2 increase MEL cell cAMP levels and inhibit induction of the differentiated MEL cell phenotype. Moreover, PIA inhibited induction of MEL cell differentiation by butyric acid, diazepam, hypoxanthine, and the aminonucleoside analog of puromycin. These results suggest that cAMP may act as a negative regulatory signal in the induction of MEL cell differentiation.

cAMP-induced NF-κB (p50/relB) binding to a c-myb intronic enhancer correlates with c-myb up-regulation and inhibition of erythroleukemia cell differentiation

“…Forskolin has been shown to increase the intracellular cAMP concentration 4100-fold in MEL cells (Moudry and Porzig, 1990). Previous workers showed inhibition of DMSO-induced hemoglobin production in MEL cells treated with 1 mM dibutyryl-cAMP or with cAMP-elevating agents like theophylline, phenylisopropyl-adenosine, prostaglandin E 1 or E 2 , with a strong correlation between the cAMP levels achieved and the degree of inhibition of hemoglobin production observed (Sherman et al, 1986(Sherman et al, , 1988. However, the mechanism of this inhibition was not further investigated.…”

“…Paradoxically, MEL cell dierentiation is inhibited when the cells are treated with cAMPanalogues or phorbol esters which activate A-kinase or protein kinase C, respectively (Yamasaki et al, 1977;Mignotte et al, 1990;Sherman et al, 1986Sherman et al, , 1988. These ®ndings suggest that cAMP analogues and phorbol esters induce immediate and prolonged signals which are not compatible with the ®ne changes in gene expression required for dierentiation.…”

G-protein-coupled receptors in normal human erythroid progenitor cells

“…Instead, as model systems, many authors have used virus-transformed erythroleukaemic cell lines of murine or human origin that can be chemically induced to differentiate along the erythroid pathway. Most of these studies have focussed on the expression of single receptor types and the role of cAMP or of protein kinase C (PKC) in erythroid cell development (Sytkowski and Kessler 1984;Sherman et al 1988;Yumoto et al 1990; Moudry and Porzig 1990;Melloni et al 1990;Chakravarthy et al 1992;Pilz et al 1992;MSki et al 1992). It seems clear from this work that both protein kinase A (PKA) and PKC (and the respective signalling pathways) are somehow involved in the regulation of erythroleukaemic cell proliferation and differentiation.…”

Purinergic signalling and cancer

“…P2X7 receptor-mediated pore formation was described in THP-1 cells [506]. Adenosine, via cAMP, was shown to inhibit differentiation (and therefore increase proliferation) of mouse erythroleukaemic MEL cells [507].…”