title: Pretreatment with PKC inhibitor triggers TNF-alpha induced apoptosis in TNF-alpha-resistant B16 melanoma BL6 cells.
abstract: Tumor necrosis factor alpha (TNF-alpha) modulates various events through several different pathways. Many tumor cells are resistant to this cytokine. Pretreatment of these cells with actinomycin D enhances TNF-alpha-induced apoptosis. In the present study, we investigated the mechanism of this enhancement and whether or not the apoptosis of TNF-alpha-resistant cancer cells can be induced by the inhibition of Protein kinase C (PKC). When TNF-alpha was added after inhibition of PKC by H7, apoptosis was observed, and companied with the activation of nuclear factor kappa B (NF-kappaB). After the inhibition of protein kinase B (Akt) by LY294002 or p38 mitogen-activated protein kinase (p38MAPK) by SB203580, the addition of TNF-alpha did not cause apoptosis. However, after the inhibition of MAPK/extracellular signal-regulated kinase kinase 1/2 (MEK1/2) with U0126, apoptosis was observed when TNF-alpha was added. In the Western blotting analysis, phosphorylation of MEK1/2 occurred at 60 minutes after the addition of TNF-alpha. However, it was noted that after pretreatment with H7, a significant decrease in phosphorylated MEK1/2 was observed. The present findings suggest that MEK1/2 plays an important role in TNF-alpha-resistance in TNF-alpha-resistant B16 melanoma BL6 cells. Furthermore, it was found that MEK1/2 is more important than NF-kappaB, Akt, and p38MAPK in anti-apoptotic PKC signaling and that TNF-alpha-resistance can be overcome by inhibiting MEK1/2. These results suggest the possibility of development of a new anticancer drug treatment.
authors.affiliation: Department of Pharmacotheraphy, Kinki University, School of Pharmaceutical Sciences, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan. nishida@phar.kindai.ac.jp
authors.forename: Shozo
authors.initials: S
authors.lastname: Nishida
authors.forename: Shohei
authors.initials: S
authors.lastname: Yoshioka
authors.forename: Saori
authors.initials: S
authors.lastname: Kinoshita-Kimoto
authors.forename: Michiyo
authors.initials: M
authors.lastname: Kotani
authors.forename: Masanobu
authors.initials: M
authors.lastname: Tsubaki
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Fujii
authors.forename: Takanori T
authors.initials: TT
authors.lastname: Tomura
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Irimajiri
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002070:Butadienes / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008545:Melanoma / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D051379:Mice; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D002070:Butadienes; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D009570:Nitriles; D014409:Tumor Necrosis Factor-alpha; C113580:U 0126; D003609:Dactinomycin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases