Physiological Stress-Induced Drug Resistance and its Reversal
Abstract
Physiological stress conditions associated with solid tumors play a role in chemotherapeutic resistance. Treatment with hypoxia or chemical stress agents causes EMT6 mouse mammary tumor cells to develop resistance to teniposide and etoposide a topoisomerase II inhibitor. We have shown that prostaglandin Al can fully reverse stress-induced resistance to teniposide or etoposide and the PGAl can reverse this resistance when given either prior to or after the stress. PGA1 could also block activation of the transcription factor NF-kB as measured by gel shift assays or a luciferase reporter gene. To test whether NF-kB was directly involved in stress-induced resistance an inducible promoter plasmid system containing a mutant lkB gene (which was non-phosphorylatable) was introduced into EMT6 cells as a dominant negative mutant. Expression of the dominant negative mutant prevented the stress activation of NF-kB and reverted the resistant phenotype to a drug sensitive phenotype. These results imply that NF-kB directly mediates both chemical and physiological stress-induced drug resistance in cancer cells and suggest that agents like PGAl which prevent NF-kB activation may improve the efficacy of topoisomerase II inhibitors.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2004
- Accession Number
- ADA474449
Entities
People
- Katherine Kennedy
Organizations
- George Washington University