Source
Apoptosis Research Group and Genomic Research Centre, School of Medical Science, Griffith University, Southport, Queensland, Australia. l.dong@griffith.edu.au
Abstract
PURPOSE:
Vitamin E analogues are potent novel anticancer drugs. The purpose of this study was to elucidate the cellular target by which these agents, represented by alpha-tocopoheryl succinate (alpha-TOS), suppress tumors in vivo, with the focus on the mitochondrial complex II (CII).
EXPERIMENTAL DESIGN:
Chinese hamster lung fibroblasts with functional, dysfunctional, and reconstituted CII were transformed using H-Ras. The cells were then used to form xenografts in immunocompromized mice, and response of the cells and the tumors to alpha-TOS was studied.
RESULTS:
The CII-functional and CII-reconstituted cells, unlike their CII-dysfunctional counterparts, responded to alpha-TOS by reactive oxygen species generation and apoptosis execution. Tumors derived from these cell lines reciprocated their responses to alpha-TOS. Thus, growth of CII-functional and CII-reconstituted tumors was strongly suppressed by the agent, and this was accompanied by high level of apoptosis induction in the tumor cells. On the other hand, alpha-TOS did not inhibit the CII-dysfunctional tumors.
CONCLUSIONS:
We document in this report a novel paradigm, according to which the mitochondrial CII, which rarely mutates in human neoplasias, is a plausible target for anticancer drugs from the group of vitamin E analogues, providing support for their testing in clinical trials.