Interferon-α 2b reduces phosphorylation and activity of MEK and ERK through a Ras/Raf-independent mechanism

Abstract

Summary Interferon (IFN)-α affects the growth, differentiation and function of various cell types by transducing regulatory signals through the Janus tyrosine kinase/signal transducers of activation and transcription (Jak/STAT) pathway. The signalling pathways employing the mitogenactivated ERK-activating kinase (MEK) and the extracellular-regulated kinase (ERK) are critical in growth factors signalling. Engagement of the receptors, and subsequent stimulation of Ras and Raf, initiates a phosphorylative cascade leading to activation of several proteins among which MEK and ERK play a central role in routing signals critical in controlling cell development, activation and proliferation. We demonstrate here that 24-48 h following treatment of transformed T-and monocytoid cell lines with recombinant human IFN-α2b both the phosphorylation and activity of MEK1 and its substrates ERK1/2 were reduced. In contrast, the activities of the upstream molecules Ras and Raf-1 were not affected. No effect on MEK/ERK activity was observed upon short-term exposure (1-30 min) to IFN. The anti-proliferative effect of IFN-α was increased by the addition in the culture medium of a specific inhibitor of MEK, namely PD98059. In conclusion, our results indicate that IFN-α regulates the activity of the MEK/ERK pathway and consequently modulates cellular proliferation through a Ras/Raf-independent mechanism. Targeting the MEK/ERK pathway may strengthen the IFN-mediated anti-cancer effect.

Phagocytosis of Apoptotic Cells by Macrophages Induces Novel Signaling Events Leading to Cytokine-Independent Survival and Inhibition of Proliferation: Activation of Akt and Inhibition of Extracellular Signal-Regulated Kinases 1 and 2

“…Indeed, for many agents it is the duration and intensity of ERK1/2 activation that seem to determine the effect on cell proliferation, with transient low-magnitude activation favoring proliferation and sustained high-magnitude stimulation favoring antiproliferation (38,39,41). The two most prominent groups of antiproliferative agents that inhibit ERK1/2 are 1) agents that raise intracellular cAMP (42,43) and 2) members of the IFN family, especially IFN-␣ (44,45). Elevated intracellular cAMP is unlikely to explain the effect of apoptotic uptake because cAMP has been shown to enhance, rather than inhibit, ERK activity in BM M (46), as opposed to other cell types.…”

Fluoxetine regulates cell growth inhibition of interferon-α

“…Lamin A was purchased from BD Biosciences (San Jose, CA, USA). 6 ) were harvested from 10-cm culture dishes, washed with phosphate-buffered saline (PBS), suspended in 200 µl of ice-cold 70% ethanol and incubated on ice for a least 1 h. After cells were washed and exposed to RNase A at 37˚C for 30 min, these cells were then suspended in propidium iodide (PI) (Sigma-Aldrich, St. Louis, MO, USA) in PBS. DNA was analyzed via flow cytometry (FACSCalibur; BD Biosciences) to evaluate the cell cycle by measuring the percentage of subG1, G0/G1-, S-and G2/M-phase after treatment with IFN-α and/or fluoxetine after 24 h.…”

“…Alternatively, IFN-α activates its receptors and induces antiproliferative signaling via the STAT by cross-talking with the extracellular signal-regulated kinase (ERK) pathway; it further leads to the slowing down of G1/S transition without apoptosis in human hepatocellular carcinoma cells (HCC) (5). Conversely, IFN-α reduces activation of ERK in haematological malignancies (6). IFN-α also exerts growth inhibition of human T-cell leukaemia line Jurkat through p38a and p38b (7).…”

Antiproliferative Activity of Recombinant Human Interferon Alpha2b on Estrogen Positive Human Breast Cancer McF-7 Cell Line

“…Inhibition of protein will decrease the activity of cyclindependent kinase (CDK-2 and CDK-4) and lower protein expression of cyclin D and E which involve in cell proliferation. The Inhibition also increases p21 Waf1 and p27 kip1 as an inhibitor of cell division and decreases protein phosphorylation RB / p105 (Romerio et al, 2000;Romerio and Zella, 2002;Steelman, 2004). The antiproliferative activity of rhIFNα2b also occurs by apoptosis mechanism.…”