Inhibition of NADPH oxidase activity promotes differentiation of B16 melanoma cells.
The activity of NADPH oxidase is increased in malignant skin keratinocytes. We demonstrated that inhibition of NADPH oxidase activity by diphenyleneiodonium (DPI) suppressed free radical production, inhibited cell growth and promoted cell differentiation of B16 melanoma cells, as indicated by cell morphology, increased production of melanin, and increased expression of microphthalmia-associated transcription factor (MITF). siRNA to NADPH oxidase subunit Rac1 or p47 induced the expression of MITF, verifying that the pro-differentiation effects are due to the inhibition of NADPH oxidase. Biochemical studies suggest that ERK plays a positive role whereas PKCalpha plays a negative role during this differentiation event. In addition, the protein levels of the tumor suppressor p53 were suppressed by DPI, suggesting that p53 is activated by oxidative stress and may negatively regulate differentiation in melanoma cells. Taken together, these results suggest that inhibiting NADPH oxidase activity promotes cell differentiation of B16 melanoma cells.
Zhao
Yunfeng
Y
Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center-Shreveport, Shreveport, LA 71130, USA. yzhao1@lsuhsc.edu
Liu
Jianfeng
J
McMartin
Kenneth E
KE
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002454:Cell Differentiation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D008543:Melanins / Q000378:metabolism; D008546:Melanoma, Experimental; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor / Q000096:biosynthesis; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D008543:Melanins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D019255:NADPH Oxidases; D048049:Extracellular Signal-Regulated MAP Kinases