Mechanisms of drug-resistance and apoptosis in oral carcinoma cells

我们研究了抗癌药物对口腔鳞癌细胞凋亡的诱导作用和多药耐药-1 （MDR1）基因的转录调控。SCCKN细胞对各种抗癌药物高度敏感，而SCCTF细胞对这些试剂的敏感性最低。培霉素诱导SCCKN和SCCTF细胞凋亡呈剂量依赖性，浓度分别为1 μM和10 μM时效果最大。1 μM培霉素可诱导SCCKN细胞凋亡，但对SCCTF细胞无诱导作用。RT-PCR结果显示，MDR1 mRNA在SCCTF细胞中高表达，而在SCCKN细胞中低表达。在用Hoechst 33342处理后评估MDR1蛋白的外排作用，SCCKN细胞出现强烈的染色，而SCCTF细胞的染色非常弱。使用MDR1启动子区域（一种dna蛋白）进行电泳迁移迁移试验。蛋白质磷酸化和去磷酸化已被认为是细胞功能的关键机制。核仁蛋白是一种大量表达的核仁磷酸化蛋白，主要位于核仁中。培养细胞核仁蛋白的染色模式与pp1δ相似。通过免疫细胞化学和免疫沉淀证实了核仁中的核蛋白与PP1δ结合。方法。从对照细胞中获得的蛋白质中检测到一个主要的条带，110 kDa。在冈田酸诱导的凋亡细胞中，110 kDa蛋白的表达水平下降，而在冈田酸诱导的凋亡细胞中，该蛋白的表达水平增加了80 kDa。我们的研究结果表明，PP1δ直接与核仁中的核仁蛋白结合，核仁蛋白在细胞凋亡过程中被切割。

We examined the effects of anticancer drugs on induction of apoptosis and the transcriptional regulation of the multidrug resistance-1 (MDR1) gene in' oral squamous carcinoma cells. SCCKN cells were shown to be highly sensitive to various anticancer drugs, whereas SCCTF cells were minimally sensitive to these reagents. Peplomycin induced apoptosis in both SCCKN and SCCTF Cells in a dose-dependent fashion with the maximal effect at concentrations of 1 μM and 10 μM, respectively. Apoptosis was induced in SCCKN cells treated with 1 μM peplomycin, but not in SCCTF cells. RT-PCR revealed that MDR1 mRNA was highly expressed in SCCTF cells while it was under the limit of detection in SCCKN cells. After treatment with Hoechst 33342 to assess efflux action of MDR1 protein, intense staining occurred in SCCKN cells, whereas the staining was very weak in SCCTF cells. With an electrophoretic mobility shift assay using the MDR1 promoter region, a DNA-protein. Protein phosphorylation and dephosphorylation has been recognized as a key mechanism in cell function. Nucleolin is an abundantly expressed nucleolar phosphoprotein and is located mainly in the nucleolus. The staining pattern of nucleolin in cultured cells is similar to that of PP 1δ. Nucleolin was demonstrated to bind to PP1δ in nucleolus by using immunocytochemical and immunoprecipitation. methods. A major band, 110 kDa, was detected in the proteins obtained from the control cells. The level of the 110 kDa protein decreased in the apoptotic cells, whereas an additional band, 80 kDa, appeared and the level of this protein increased in the proteins prepared from okadaic acid-induced apoptotic cells. Our results indicate that PP1δ directly binds to nucleolin in the nucleolus and that nucleolin is cleaved during apoptosis.