title: The heme oxygenase-1 protein is overexpressed in human renal cancer cells following activation of the Ras-Raf-ERK pathway and mediates anti-apoptotic signal.
abstract: The stress-inducible cytoprotective enzyme heme oxygenase-1 (HO-1) may play a critical role in the growth and metastasis of tumors. We demonstrated that overexpressed HO-1 promotes the survival of renal cancer cells by inhibiting cellular apoptosis; we also showed that the proto-oncogene H-Ras becomes activated in these cells under stress following treatment with immunosuppressive agents. However, it is not known if there is an association between Ras activation and HO-1 overexpression. Here, we examined if the activation of H-Ras pathway could induce HO-1, and promote the survival of renal cancer cells (786-0 and Caki-1). In co-transfection assays, using HO-1 promoter-luciferase construct, we found that the activated H-Ras, H-Ras(12V), promoted HO-1 transcriptional activation. The inhibition of endogenous H-Ras by specific dominant-negative mutant/siRNA markedly ablated the HO-1 promoter activity. Active H-Ras increased HO-1 mRNA and protein expression. Moreover, transfection with effector domain mutant constructs of active H-Ras showed that H-Ras-induced HO-1 overexpression was primarily mediated through the Raf signaling pathway. Using pharmacological inhibitor, we observed that ERK is a critical intermediary molecule for Ras-Raf-induced HO-1 expression. Activation of H-Ras and ERK promoted nuclear translocation of the transcription factor Nrf2 for its binding to the specific sequence of HO-1 promoter. The knockdown of Nrf2 significantly inhibited H-Ras-induced HO-1 transcription. Finally, by FACS analysis using Annexin-V staining, we demonstrated that the H-Ras-ERK-induced and HO-1-mediated pathway could protect renal cancer cells from apoptosis. Thus, targeting the Ras-Raf-ERK pathway for HO-1 overexpression may serve as novel therapeutics for the treatment of renal cancer.
authors.affiliation: Division of Nephrology, Children's Hospital Boston, Boston, Massachusetts 02115, USA.
authors.forename: Pallavi
authors.initials: P
authors.lastname: Banerjee
authors.forename: Aninda
authors.initials: A
authors.lastname: Basu
authors.forename: Dipak
authors.initials: D
authors.lastname: Datta
authors.forename: Martin
authors.initials: M
authors.lastname: Gasser
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Waaga-Gasser
authors.forename: Soumitro
authors.initials: S
authors.lastname: Pal
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007680:Kidney Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport; D000090063:Proto-Oncogene Mas; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: C000715470:MAS1 protein, human; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)