Differential induction of reactive oxygen species through Erk1/2 and Nox-1 by FK228 for selective apoptosis of oncogenic H-Ras-expressing human urinary bladder cancer J82 cells

Shambhunath Choudhary, University of Tennessee - Knoxville
Kusum Rathore, University of Tennessee - Knoxville
Hwa-Chain Robert Wang, University of Tennessee - Knoxville

Abstract

More than 35% of human urinary bladder cancers involve oncogenic H-Ras activation. The goal of this study was to investigate the role of the ERK pathway in mediating apoptotic signals induced by oncogenic H-Ras, FK228 treatment, and exogenous H(2) O(2) treatment to increase Nox-1 elevation, leading to production of intracellular reactive oxygen species (ROS) for inducing apoptosis in human bladder cancer J82 cells. Our study revealed that FK228 combined with exogenous H(2)O(2) cooperatively induced activation of Mek1/2 and Erk1/2 to increase Nox-1 elevation, intracellular ROS production, caspase activation, and cell death. Expression of oncogenic H-Ras significantly increased these FK228- and exogenous H(2)O(2)-induced effects. Oncogenic H-Ras-increased cell susceptibility to FK228 could be alternately achieved by additional treatment with exogenous H(2)O(2). Hence, combined use of FK228 with ROS-generating agents may apply to therapeutic strategies to preferentially kill malignant cells with or without oncogenic H-Ras activation.

CONCLUSION: Oncogenic H-Ras expression and FK228 treatment synergistically induced the ERK pathway, resulting in differentially increased Nox-1 elevation, ROS production, and GSH depletion, leading to differential caspase activation and cell death in oncogenic H-Ras-expressing J82 versus parental cells.