Requirement of de novo protein synthesis for aminopterin-induced apoptosis in a mouse myeloma cell line.
Cells synthesize nucleotides through de novo and salvage pathways that require the activities of dihydrofolate reductase (DHFR) and hypoxanthine-guanine phosphoribosyltransfease (HGPRT), respectively. Aminopterin, an inhibitor of dihydrofolate reductase, has been demonstrated to allow HGPRT(-) cells to be negatively selected. However, the pathway by which aminopterin leads to cell death remains to be clarified. In this study, we characterized features of cellular responses induced by aminopterin treatment in P3-X63-Ag8.653, a mouse HGPRT(-) myeloma cell line. Upon treatment with aminopterin, the cells readily underwent an apoptotic process, as assessed by DNA fragmentation assay and electron microscopic analysis. Aminopterin-induced apoptosis was drastically reduced by addition of actinomycin D and cycloheximide, indicating that active RNA and protein synthesis is required for the apoptotic effect of aminopterin. Interestingly, the induction of c-myc gene expression preceded the activity of DNA fragmentation in aminopterin-treated cells. Taken together, these results suggest that cells deficient in the salvage pathway of purine biosynthesis are susceptible to aminopterin-induced apoptosis that requires de novo synthesis of proapoptotic factors, including Myc oncoprotein.
Chung
Y H
YH
Department of Microbiology, College of Medicine, Hanyang University, Haengdang-dong 17, Seongdong-ku, 133-791, Seoul, South Korea. chungyh@email.hanyang.ac.kr
Youn
J
J
Choi
Y
Y
Paik
D J
DJ
Cho
Y J
YJ
D000630:Aminopterin / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis; D003513:Cycloheximide / Q000494:pharmacology; D053938:DNA Fragmentation; D003609:Dactinomycin / Q000494:pharmacology; D016259:Genes, myc; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D051379:Mice; D009101:Multiple Myeloma; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012313:RNA / Q000096:biosynthesis; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D003609:Dactinomycin; D012313:RNA; D003513:Cycloheximide; D007041:Hypoxanthine Phosphoribosyltransferase; D000630:Aminopterin