Activation of c-myc gene mediates the mitogenic effects of oxalate in LLC-PK1 cells, a line of renal epithelial cells.
Recent studies on LLC-PK1 cells demonstrated that oxalate, a simple dicarboxylic acid, acts as a mitogen for these renal epithelial cells. Exposure to oxalate initiates DNA synthesis, induces the expression of one of the early growth response genes c-myc and stimulates proliferation of quiescent cultures of LLC-PK1 cells. The present studies examined the possibility that expression of the c-myc protooncogene is obligatory for this mitogenic response. Specifically we determined whether pretreatment with c-myc antisense oligonucleotides would block the proliferative effects of oxalate in LLC-PK1 cells. Quiescent cultures of LLC-PK1 cells were exposed to oxalate in the presence and absence of c-myc antisense and the effects of oxalate on c-myc protein expression (Myc), DNA synthesis and cell growth were assessed. Exposure of cells to oxalate alone increased the expression of Myc within two hours. Pretreatment with c-myc antisense abolished this response. Further, pretreatment of cells with c-myc antisense but not nonsense oligonucleotides blocked the oxalate-induced initiation of DNA synthesis. Increases in cell number in response to oxalate (measured after 72 hr exposure) were also blocked by exposure to c-myc antisense. These findings suggest that c-myc gene expression is critical for the mitogenic effects of oxalate in LLC-PK1 cells.
Department of Surgery, University of Massachusetts Medical School, Worcester, USA.
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Koul
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Kennington
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Honeyman
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Jonassen
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Menon
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Scheid
D000818:Animals; D015152:Blotting, Northern; D002452:Cell Count; D016895:Culture Media, Serum-Free; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D016259:Genes, myc / Q000502:physiology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018374:LLC-PK1 Cells; D008934:Mitogens / Q000494:pharmacology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010070:Oxalates / Q000494:pharmacology*; D019815:Oxalic Acid; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis* / Q000235:genetics; D013552:Swine; D013936:Thymidine / Q000378:metabolism
D016895:Culture Media, Serum-Free; D008934:Mitogens; D016376:Oligonucleotides, Antisense; D010070:Oxalates; D016271:Proto-Oncogene Proteins c-myc; D019815:Oxalic Acid; D013936:Thymidine