Koul H, Kennington L, Honeyman T, Jonassen J, Menon M, Scheid C
Department of Surgery, University of Massachusetts Medical School, Worcester, USA.
Kidney Int. 1996 Nov;50(5):1525-30. doi: 10.1038/ki.1996.467.
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.
近期对LLC-PK1细胞的研究表明，草酸（一种简单的二羧酸）可作为这些肾上皮细胞的促有丝分裂原。暴露于草酸会启动DNA合成，诱导早期生长反应基因之一c-myc的表达，并刺激LLC-PK1细胞静止培养物的增殖。本研究探讨了c-myc原癌基因的表达对于这种促有丝分裂反应是否必不可少。具体而言，我们确定用c-myc反义寡核苷酸预处理是否会阻断草酸对LLC-PK1细胞的增殖作用。在有和没有c-myc反义寡核苷酸的情况下，将LLC-PK1细胞的静止培养物暴露于草酸，并评估草酸对c-myc蛋白表达（Myc）、DNA合成和细胞生长的影响。单独将细胞暴露于草酸会在两小时内增加Myc的表达。用c-myc反义寡核苷酸预处理可消除这种反应。此外，用c-myc反义寡核苷酸而非无义寡核苷酸预处理细胞可阻断草酸诱导的DNA合成起始。暴露于c-myc反义寡核苷酸也会阻断对草酸的细胞数量增加（在暴露72小时后测量）。这些发现表明，c-myc基因表达对于草酸在LLC-PK1细胞中的促有丝分裂作用至关重要。
