ERK activation increases nitroprusside induced apoptosis in  human melanoma  cells  irrespective of p53 status: Role of  superoxide dismutases

Abstract

Constitutive ERK activation, superoxide dismutases (SOD) and p53 mutations are implicated in modulating tumor apoptotic response. We now investigated whether human melanoma survival in response to sodium nitroprusside (SNP) is modulated by: (a) stable introduction of a DN-mutant p53; (b) pharmacologically inhibiting ERK activation with UO126; (c) addition of exogenous SOD. Nitroprusside releases nitric oxide (NO) when intact, or acts in a NO-independent manner via iron and residual cyanide after light exposure (lex-SNP). When tested at 300 μM in 72 h treatments by cytometric live-dead assays, intact SNP caused a 50% lethality versus a 30% lethality induced by lex-SNP. No protection from SNP toxicity was seen when inhibiting the PI3-kinase pathway with LY294002 or c-Jun NH 2 kinase signaling with SP600125. However, pretreatment with UO126 protected from SNP-mediated cell death including counteracting apoptosis-associated Bax expression and PARP cleavage, plus reversing loss of Cu,Zn-SOD. Moreover, addition of exogenous SOD also protected cells from SNP toxicity. In spite of the greater earlier effects of intact SNP, cells treated with single doses of either intact or lex-SNP, revealed about a 90% mortality in longer 120 h treatments, and these were also counteracted by UO126 or exogenous SOD. This report is the first to show that: constitutive ERK activation characteristic of cancer cells, increases a nitroprusside-induced apoptosis modulated by SOD.

ERK and cell death: Mechanisms of ERK‐induced cell death – apoptosis, autophagy and senescence

“…However, ERK activity has also been involved in activation of the extrinsic pathway by death receptor ligands such as TNF‐related apoptosis‐inducing ligand (TRAIL) [34,42–46], TNFα [47–49], Fas [50,51] or CD40 ligand [52,53]. Cell death induced by other death pathways that occur in response to zinc [54,55], oxidation [56–59], especially in response to ONOO − [60], H 2 O 2 [61–64] or NO treatment [65–67], toxic compounds such as cadmium, [17,68,69], benzo[a]pyrene [70], asbestos [71] or arsenic [17,72], also require ERK activity. Many death stimuli, such as estradiol [73] or its antagonist tamoxifen [74], interferon‐α [75], cephalosporin [76], the calcium mobilizer calcimycin [77], epidermal growth factor (EGF) deprivation [78], leptin [79], bufalin [11], bacterial infection [80,81], chelerythrine [82] and the dominant negative form of Rac and Cdc42 [83,84], are sensitive to inhibition of the Ras/Raf/ERK pathway (Table 1).…”

Genome-wide methylated CpG island profiles of melanoma cells reveal a melanoma coregulation network

“…While it is generally true that melanomas are caused by ultraviolet B induced lesions in melanocytes of the skin, the exact molecular events leading to melanoma production are yet unknown2. Over 90% of melanomas are independent of TP53 gene mutation3, suggesting pathways other than those involved in p53 mediated DNA repair or abrogation of apoptosis by p53 are generally not directly involved. Early events in melanoma induction involve epithelial-mesenchymal transition, and both protein coding and noncoding RNA genes are important4.…”

β-Lapachone suppresses the lung metastasis of melanoma via the MAPK signaling pathway

“…Western blot data showed that β-lapachone time- and dose-dependently induced pro-apoptotic proteins caspase-3, -8, and -9, PARP cleavage, and increased expression of Bax in B16F10 cells, whereas expression of anti-apoptotic proteins such as Bcl-2 and Bcl-xL was decreased in these cells (Fig 4). MAPKs including p38, ERK, and JNK, are implicated in regulating survival and cell death responses of tumor cells, and play critical roles in the regulation of cell proliferation, differentiation, and apoptosis [21–23]. Thus, we examined whether MAPKs are involved in β-lapachone-induced apoptosis.…”