Abstract
Six well characterized human medulloblastoma cell lines (D283 Med, Daoy, D341 Med, D384 Med, D425 Med, and D458 Med) were examined for the expression of O6-methylguanine-DNA methyltransferase (MGMT) by activity and Western and Northern blot analysis. High levels of MGMT activity were present in D283 Med, Daoy, D341 Med, and D384 Med (1.36, 0.80, 1.68, and 1.62 pmol/mg of protein, respectively), but negligible MGMT activity was detected in D425 Med and D458 Med (0.06 and 0.05 pmol/mg of protein, respectively), which were derived separately at different times from the same patient. The presence of MGMT protein and its transcript was demonstrated in D283 Med, Daoy, D341 Med, and D384 Med, but both the protein and the mRNA were undetectable in D425 Med and D458 Med. Nevertheless, all six cell lines contained an apparently unaltered MGMT gene, as determined by Southern blot analysis. The absence of MGMT activity in D425 Med and D458 Med is likely due to the absence of the protein, resulting from a lack of transcription of the MGMT gene. The varying levels of expression of MGMT in medulloblastoma cells found in this study should provide a molecular basis for drug design and selection in chemotherapy of this tumor.
Footnotes
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↵1 This work was supported by NIH Grants CA 11898, CA 32672, NS 20023, CA 44640, CA 31721, CA 14799, CA 36888, and CA 23099, American Cancer Society Grant CH 403B, and Bristol-Myers Research Grant 100-R18, by the United States Department of Energy under contract DEACO5-840R21400 with Martin Marietta Energy Systems, Inc., and by the American Lebanese Syrian Associated Charities. M. A. v. W. is a recipient of NIH Postdoctoral Fellowship CA 09346.
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↵2 To whom requests for reprints should be addressed, at P. O. Box 3156, Department of Pathology, Duke University Medical Center, Durham, NC 27710.
- Received April 3, 1991.
- Accepted December 16, 1991.
- ©1992 American Association for Cancer Research.
Volume 52, Issue 5
