Structure and expression of the cytosolic aldehyde dehydrogenase gene in cyclophosphamide-resistant murine leukemia L1210 cells.
These investigations were performed to clarify the molecular basis for the enhanced expression of cytosolic aldehyde dehydrogenase (ALDH-1) enzymatic activity in the cyclophosphamide-resistant L1210/CPA murine leukemia cell line, as compared to the parental L1210/O strain. Western immunoblot analysis was performed using a 15-fold greater quantity of cytosolic protein from the L1210/O as compared to the L1210/CPA cell line. Nevertheless, ALDH-1 immunoreactive protein could be detected only in the L1210/CPA cells. Northern analyses, performed using total cellular and polyadenylated RNA, again demonstrated ALDH-1-specific transcripts only in the L1210/CPA cell line. This transcript was identical in size to the ALDH-1 message expressed by normal murine hepatocytes. On Southern analysis, no evidence of gene amplification, gene rearrangement, or significant mutations of length was detected. These studies suggest that the ALDH-1 protein produced by the L1210/CPA cell line is structurally normal. Moreover, overexpression of the gene does not appear to have arisen as a result of an incremental process, such as gene amplification. Rather, a qualitative abnormality in the regulation of this gene appears to exist in the L1210/CPA cells, which distinguishes them from L1210/O cells and from normal murine lymphocytes.
Radin
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Division of Pharmacology and Experimental Therapeutics, Johns Hopkins Oncology Center, Baltimore, MD 21205.
Zhoa
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XL
Woo
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Colvin
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Hilton
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D000444:Aldehyde Dehydrogenase / Q000235:genetics*; D000818:Animals; D001711:Biotransformation; D003520:Cyclophosphamide / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004351:Drug Resistance; D015971:Gene Expression Regulation, Enzymologic; D015151:Immunoblotting; D007939:Leukemia L1210 / Q000201:enzymology / Q000235:genetics*; D051379:Mice; D014407:Tumor Cells, Cultured
D003520:Cyclophosphamide; D000444:Aldehyde Dehydrogenase