Downmodulation of ERK activity inhibits the proliferation and induces the apoptosis of primary acute myelogenous leukemia blasts

Abstract

MAP kinase/ERK kinase (MEK)-extracellular signal-regulated kinase (ERK) kinases are frequently activated in acute myelogenous leukemia (AML), and can have prosurvival function. The purpose of this study was to induce downmodulation of MEK-ERK activation in AML primary blasts in order to detect the effect on cell cycle progression and on the apoptosis of leukemic cells. We investigated 14 cases of AML with high ERK 1/2 activity and four cases with undetectable or very low activity. After 24 h incubation of the AML blasts with high ERK activity using PD98059 (New England BioLabs, Beverly, MA, USA), a selective inhibitor of MEK1 phosphorylation, at concentrations of 20 and 40 lM, we observed a strong decrease in the levels of ERK1/2 activity. A significant decrease of blast cell proliferation compared with untreated controls was found. In contrast, the proliferation of blast cells that expressed low or undetectable levels of ERK activity was not inhibited. Timecourse analysis demonstrated that the downmodulation of MEK1/2, ERK1 and ERK2 dual-phosphorylation was evident even after 3 h of treatment with 20 and 40 lM. The cleavage of poly(ADP-ribose) polymerase (PARP), an early sign of apoptosis, appeared after 18 h of PD98059 treatment at concentrations of 20 and 40 lM in eight of the 14 cases. After 24 h of treatment, cleaved PARP appeared in all 14 cases. Time-course analysis of cell cycle progression and apoptosis showed that PD98059 induced a G1-phase accumulation with low or undetectable levels of apoptosis after 24 h incubation; after 48 and 72 h incubation, a significant increase of apoptosis was observed. Thus, the primary effect of ERK downmodulation was a cell cycle arrest followed by the apoptosis of a significant percentage of the leukemic blasts. The preclinical model of leukemia treatment reported in this paper makes further comment with regard to MEK1 inhibition as a useful antileukemic target, and encourages the conducting of in vivo studies and clinical investigations.

Orostachys japonicus induce p53‐dependent cell cycle arrest through the MAPK signaling pathway in OVCAR‐3 human ovarian cancer cells

“…The MAPKs families consist of three subfamilies, namely ERK, JNK and p38 (Romos, 2008; Zhang & Liu, 2002). Numerous studies have focused on ERK1/2 inhibition leading to cancer cell death (Lunghi et al., 2003; Wang et al., 2010; Wu, Wong, Khosravi, Minden, & Penn, 2004). Furthermore, p38 MAPK plays a role in cell cycle arrest by activating cell cycle checkpoints (Feng et al., 2015; Thornton & Rincon, 2009).…”

Multidrug resistance-associated protein 1 expression is under the control of the phosphoinositide 3 kinase/Akt signal transduction network in human acute myelogenous leukemia blasts

“…Indeed, it is well known that the Erk 1/2 pathway is up regulated in most cases of AML. 33 Controls were represented by Jurkat cells treated with 80 nM 4a-Phorbol 12-myristate 13-acetate (PMA), a powerful activator of the Erk 1/2 pathway (see Figure 4a). Five out of nine patients, who were positive for MRP1, also had activated Erk 1/2 (Table 2).…”

Quantitative single cell determination of ERK phosphorylation and regulation in relapsed and refractory primary acute myeloid leukemia

“…Previous studies using the MEK inhibitor PD98059 reported that inhibition of p-ERK was coupled with the induction of apoptosis. 5,22 We failed to demonstrate apoptosis induction after 24 h and even after extended incubation with 3 mM CI-1040. Only in a single sample, p-ERK inhibition was associated with induction of apoptosis.…”

“…p-ERK expression in refractory/relapsed AML samples MR Ricciardi et al with previous reports 5, 21,22 using Western blotting for analysis of p-ERK, we examined here, for the first time, clinical samples by FCM. FCM allows to better identify and quantify phosphoproteins in subpopulations of cells with undetectable or very low expression levels as compared to other methods, because of its ability to measure single cells and not just population averages.…”