https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:14360 Wed 11 Apr 2018 17:15:26 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:21727 EL by protein phosphatase 2A (PP2A). However, melanoma cells are largely resistant to ER stress-induced apoptosis, suggesting that Bim activation is suppressed in melanoma cells undergoing ER stress. We show here that ER stress reduces PP2A activity leading to increased ERK activation and subsequent phosphorylation and proteasomal degradation of Bim_EL. Despite sustained upregulation of Bim at the transcriptional level, the Bim_EL protein expression was downregulated after an initial increase in melanoma cells subjected to pharmacological ER stress. This was mediated by increased activity of ERK, whereas the phosphatase activity of PP2A was reduced by ER stress in melanoma cells. The increase in ERK activation was, at least in part, due to reduced dephosphorylation by PP2A, which was associated with downregulation of the PP2A catalytic C subunit. Notably, instead of direct dephosphorylation of Bim_EL, PP2A inhibited its phosphorylation indirectly through dephosphorylation of ERK in melanoma cells. Taken together, these results identify downregualtion of PP2A activity as an important protective mechanism of melanoma cells against ER stress-induced apoptosis.]]> Wed 11 Apr 2018 17:12:53 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:14354 V600E melanoma cells by induction of necrosis. Cotreatment with the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) or panobinostat (LBH589) and the BRAF inhibitor PLX4720 activated the caspase cascade, but caspases appeared dispensable for killing, in that inhibition of caspases did not invariably block induction of cell death. The majority of dying cells acquired propidium iodide positivity instantly when they became positive for Annexin V, suggesting induction of necrosis. This was supported by caspase-independent release of high-mobility group protein B1, and further consolidated by rupture of the plasma membrane and loss of nuclear and cytoplasmic contents, as manifested by transmission electron microscopic analysis. Of note, neither the necrosis inhibitor necrostatin-1 nor the small interference RNA (siRNA) knockdown of receptor-interacting protein kinase 3 (RIPK3) inhibited cell death, suggesting that RIPK1 and RIPK3 do not contribute to induction of necrosis by combinations of HDAC and BRAF inhibitors in BRAF^V600E melanoma cells. Significantly, SAHA and the clinically available BRAF inhibitor vemurafenib cooperatively inhibited BRAF^V600E melanoma xenograft growth in a mouse model even when caspase-3 was inhibited. Taken together, these results indicate that cotreatment with HDAC and BRAF inhibitors can bypass canonical cell death pathways to kill melanoma cells, which may be of therapeutic advantage in the treatment of melanoma.]]> Wed 11 Apr 2018 17:05:48 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:9452 Wed 11 Apr 2018 14:22:54 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17254 V600E melanoma cells with the mutant BRAF inhibitor PLX4720 or exposure of either BRAF^V600E or wild-type BRAF melanoma cells to the MEK inhibitor U0126 resulted in the upregulation of miR-768-3p and inhibition of nascent protein synthesis. This inhibition was partially blocked in cells cointroduced with anti-miR-768-3p. Significantly, miR-768-3p was similarly downregulated, which was inversely associated with the expression levels of eIF4E in fresh melanoma isolates. Taken together, these results identify downregulation of miR-768-3p and subsequent upregulation of eIF4E as an important mechanism in addition to phosphorylation of eIF4E responsible for MEK/ERK-mediated enhancement of protein synthesis in melanoma.]]> Wed 11 Apr 2018 13:07:32 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17258 Wed 11 Apr 2018 11:05:43 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17266 Wed 11 Apr 2018 10:51:24 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:29220 Thu 08 Aug 2024 13:08:51 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30753 Thu 03 Feb 2022 12:21:59 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3484 Sat 24 Mar 2018 10:57:58 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3483 Sat 24 Mar 2018 10:57:58 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:13255 Sat 24 Mar 2018 08:16:00 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:13256 Sat 24 Mar 2018 08:15:59 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:13253 Sat 24 Mar 2018 08:15:58 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:10550 Sat 24 Mar 2018 08:10:18 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:21445 Sat 24 Mar 2018 08:05:44 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17459 V600E is known to promote the stabilizing phosphorylation of the anti-apoptotic protein Mcl-1, implicated in melanoma survival and chemoresistance. We now show that B-RAF^V600E signaling also induces the transcription of Mcl-1 in melanocytes and melanoma. We demonstrate that activation of STAT3 serine-727 and tyrosine-705 phosphorylations is promoted by B-RAF^V600E activity and that the Mcl-1 promoter is dependent on a STAT consensus-site for B-RAF-mediated activation. Consequently, suppression of STAT3 activity disrupted B-RAF^V600E-mediated induction of Mcl-1 and reduced melanoma cell survival. We propose that STAT3 has a central role in the survival and contributes to chemoresistance of B-RAF^V600E melanoma.]]> Sat 24 Mar 2018 08:04:13 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17503 Sat 24 Mar 2018 08:04:05 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20568 Sat 24 Mar 2018 08:02:38 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17732 Sat 24 Mar 2018 07:57:44 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20120 Sat 24 Mar 2018 07:51:46 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24136 Sat 24 Mar 2018 07:16:32 AEDT ]]>