A Novel Prolyl Hydroxylase Inhibitor Protects Against Cell Death After Hypoxia

Abstract

Hypoxia-inducible factor 1 (HIF-1) is regulated by the oxygen-dependent hydroxylation of proline residues by prolyl hydroxylases (PHDs). We recently developed a novel PHD inhibitor, TM6008, that suppresses the activity of PHDs, inducing continuous HIF-1α activation. In this study, we investigated how TM6008 affects cell survival after hypoxic conditions capable of inducing HIF-1α expression and how TM6008 regulates PHDs and genes downstream of HIF-1α. After SHSY-5Y cells had been subjected to hypoxia, TM6008 was added to the cell culture medium under normoxic conditions. Apoptotic cell death was significantly augmented just after the hypoxic conditions, compared with cell death under normoxic conditions. Notably, when TM6008 was added to the media after the cells had been subjected to hypoxia, the expression level of HIF-1α increased and the number of cell deaths decreased, compared with the results for cells cultured in media without TM6008 after hypoxia, during the 7-day incubation period under normoxic conditions. Moreover, the protein expression levels of heme oxygenase 1, erythropoietin, and glucose transporter-3, which were genes downstream of HIF-1α, were elevated in media to which TM6008 had been added, compared with media without TM6008, during the 7-day incubation period under normoxic conditions. However, the protein expression levels of PHD2 and p53 which suppressed cell proliferation were suppressed in the media to which TM6008 had been added. Thus, TM6008, which suppresses the protein expressions of PHD2 and p53, might play an important role in cell survival after hypoxic conditions, with possible applications as a new compound for treatment after ischemic stroke.

Hypoxia and sterile inflammation in cystic fibrosis airways: mechanisms and potential therapies

“…A more suitable approach may be through a recently identified novel class of PHD inhibitor [129], which acts by preferential binding directly to the PHD active sites. One of these novel inhibitors, TM6008, was observed to reduce cell death after hypoxic exposure [130]. Therefore, TM6008 may have potential to reduce the IL-1α driven inflammation that is associated with necrotic cell death in hypoxic disease [27].…”

“…Therapies to prevent or alleviate inflammation driven by hypoxia are in early stages of trials, or have previously shown no significant clinical effect. However, these studies used relatively crude clinical endpoints and none have yet been investigated as interventions to prevent the onset of structural lung disease [105,106,110,119,130]. Currently, the majority of targets for therapy are involved in the initial activation of the inflammatory pathway, but there is little research into activators further downstream in the pathway (figure 3).…”

Hypoxia signalling manipulation for bone regeneration

“…Current hypoxia mimics are also nonspecific in that they act to modulate function of a large class of 2OG-dependent hydroxylases possibly leading to unwanted effects. This has led to the discovery of PHD2-specific inhibitors synthesised through three-dimensional enzymatic modelling (Refs 136, 137). These molecules have yet to be tested in the context of bone biology.…”

Recent Advances in Developing Inhibitors for Hypoxia-Inducible Factor Prolyl Hydroxylases and Their Therapeutic Implications

“…TM6008 has been shown to be efficacious in the treatment of inflammatory diseases, because PHD2 inhibition by TM6008 suppressed tumor necrosis factor-α mediated inflammation in macrophages [58]. A recent study further implicated TM6008 in enhancing cell survival after hypoxia by suppressing the protein expression of PHD2 and p53 [59].…”