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

J Biol Chem. 2011 Sep 23;286(38):33580-90. doi: 10.1074/jbc.M111.248401. Epub 2011 Jul 31.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis*
  • Cell Line, Tumor
  • Cell Nucleus / metabolism
  • Enzyme Activation
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Neoplastic
  • Heme Oxygenase-1 / genetics
  • Heme Oxygenase-1 / metabolism*
  • Humans
  • Kidney Neoplasms / enzymology*
  • Kidney Neoplasms / genetics
  • Kidney Neoplasms / pathology*
  • NF-E2-Related Factor 2 / metabolism
  • Promoter Regions, Genetic / genetics
  • Protein Transport
  • Proto-Oncogene Mas
  • Proto-Oncogene Proteins c-raf / metabolism*
  • Proto-Oncogene Proteins p21(ras) / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Signal Transduction
  • Transcription, Genetic
  • Transcriptional Activation

Substances

  • MAS1 protein, human
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • Proto-Oncogene Mas
  • RNA, Messenger
  • HMOX1 protein, human
  • Heme Oxygenase-1
  • Proto-Oncogene Proteins c-raf
  • Extracellular Signal-Regulated MAP Kinases
  • HRAS protein, human
  • Proto-Oncogene Proteins p21(ras)