Mitochondrial superoxide mediates doxorubicin-induced keratinocyte apoptosis through oxidative modification of ERK and Bcl-2 ubiquitination

Abstract

Massive apoptosis of keratinocytes has been implicated in the pathogenesis of chemotherapy-induced skin toxicities, but the underlying mechanisms of action are not well understood. The present study investigated the apoptotic effect of doxorubicin (DOX) on HaCaT keratinocytes and determined the underlying mechanisms. Treatment of the cells with DOX induced reactive oxygen species (ROS) generation and a concomitant increase in apoptotic cell death through the mitochondrial death pathway independent of p53. Electron spin resonance and flow cytometry studies showed that superoxide is the primary oxidative species induced by DOX and responsible for the death inducing effect. Ectopic expression of mitochondrial superoxide scavenging enzyme (MnSOD) or treatment with MnSOD mimetic (MnTBAP) inhibited DOX-induced superoxide generation and apoptosis. The mechanism by which superoxide mediates the apoptotic effect of DOX was shown to involve downregulation of Bcl-2 through ubiquitin-proteasomal degradation. Superoxide induces dephosphorylation of Bcl-2 through MAP kinase ERK1/2 inactivation which promotes ubiquitination of Bcl-2. We also provide evidence for the oxidative modification of ERK1/2 through cysteine sulfenic acid formation. These findings indicate a novel pathway for redox regulation of apoptosis regulatory proteins which could be important in the understanding of chemotherapy-induced toxicities and development of preventive treatment strategies which are currently lacking.

Ctip2 is a dynamic regulator of epidermal proliferation and differentiation by integrating EGFR and Notch signaling

“…A recent study has reported Ctip2 SUMOylation and ubiquitination in thymocytes (Zhang et al, 2012). In addition, ubiquitination and proteosomal degradation of anti-apoptotic Bcl2 protein has been observed in human dermal papilla cells and in keratinocytes (Luanpitpong et al, 2012;Luanpitpong et al, 2011). In this respect, Ctip2 may be similar to the transcription factor DNp63, which is also expressed predominantly in basal layer of epidermis, and is downregulated in differentiating keratinocytes by SUMO-conjugation and proteasomal degradation in response to high calcium (Vivo et al, 2009).…”

Dual Role of Mitophagy in Cancer Drug Resistance

“…Doxorubicin, a DNAdamaging agent, is believed to cause toxicity by inducing mitochondrial dysfunction and enhancing superoxide formation (33,34). Our previous study found that expression of BNIP3L, a regulator of mitophagy, significantly increased in colorectal cancer stem cells after doxorubicin treatment (5).…”

Coating doxorubicin‐loaded nanocapsules with alginate enhances therapeutic efficacy against Leishmania in hamsters by inducing Th1‐type immune responses

“…DOX has been shown to induce apoptosis in the Leishmania parasite (Singh and Dey, 2007;Luanpitpong et al, 2012) and, recently, was found to activate immune functions of macrophages and NK cells (Hussner et al, 2012). Immunointervention with antimonials, amphotericin B and DOX is known to improve VL (Murray et al, 2003a;Mukherjee et al, 2004), but toxicity remains a major concern.…”