Turturro Francesco, Von Burton Gary, Friday Ellen
Department of Medicine, Feist-Weiller Cancer Center, Louisiana State University Health Science Center, Shreveport, Louisiana 71103, USA.
Clin Cancer Res. 2007 Jun 15;13(12):3724-30. doi: 10.1158/1078-0432.CCR-07-0244.
We studied the hyperglycemia-induced expression of thioredoxin-interacting protein (TXNIP) expression and its relevance on the cytotoxic activity of paclitaxel in mammary epithelial-derived cell lines.
Nontumorigenic cells (MCF10A); tumorigenic, nonmetastatic cells (MCF-7/T47D); and tumorigenic, metastatic cells (MDA-MB-231/MDA-MB-435s) were grown either in 5 or 20 mmol/L glucose chronically. Semiquantitative reverse transcription-PCR was used to assess TXNIP RNA expression in response to glucose. Reactive oxygen species were detected by CM-H2DCFDA (5-6-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate) and measured for mean fluorescence intensity with flow cytometry. Thioredoxin activity was assayed by the insulin disulfide-reducing assay. Proliferation was evaluated using CellTiter96 reagent with 490-nm absorption. Obtained absorbance values were used to calculate the paclitaxel IC(50) in 5 or 20 mmol/L glucose using the Chou's dose-effect equation.
We show that hyperglycemia by itself affects the level of TXNIP RNA in breast cancer-derived cells. TXNIP RNA level differs between nontumorigenic/nonmetastatic, tumorigenic cells (low TXNIP level), and metastatic cells (high TXNIP level). The differences in TXNIP RNA level, in reactive oxygen species level, and in thioredoxin activity are all related. We further show that hyperglycemia is a favorable condition in increasing the paclitaxel cytotoxicity by causing IC(50) 3-fold decrease in metastatic breast cancer-derived MDA-MB-231 cells. The increased paclitaxel cytotoxicity is associated with an additive effect on the hyperglycemia-mediated TXNIP expression more evident in conditions of hyperglycemia than normoglycemia.
Our study opens a new perspective on the relevance of metabolic conditions of hyperglycemia in the biology and treatment of cancer, particularly in view of the epidemic of diabetes.
我们研究了高血糖诱导的硫氧还蛋白相互作用蛋白（TXNIP）表达及其与紫杉醇在乳腺上皮来源细胞系中细胞毒性活性的相关性。
非致瘤性细胞（MCF10A）；致瘤性、非转移性细胞（MCF-7/T47D）；以及致瘤性、转移性细胞（MDA-MB-231/MDA-MB-435s）长期在5或20 mmol/L葡萄糖中培养。采用半定量逆转录聚合酶链反应评估TXNIP RNA表达对葡萄糖的反应。用CM-H2DCFDA（5-6-氯甲基-2',7'-二氯二氢荧光素二乙酸酯）检测活性氧，并通过流式细胞术测量平均荧光强度。通过胰岛素二硫键还原试验测定硫氧还蛋白活性。使用CellTiter96试剂在490 nm吸光度下评估细胞增殖。获得的吸光度值用于使用Chou剂量效应方程计算5或20 mmol/L葡萄糖中的紫杉醇IC(50)。
我们表明，高血糖本身会影响乳腺癌来源细胞中TXNIP RNA的水平。TXNIP RNA水平在非致瘤性/非转移性、致瘤性细胞（低TXNIP水平）和转移性细胞（高TXNIP水平）之间存在差异。TXNIP RNA水平、活性氧水平和硫氧还蛋白活性的差异均相关。我们进一步表明，高血糖是增加紫杉醇细胞毒性的有利条件，可使转移性乳腺癌来源的MDA-MB-231细胞的IC(50)降低3倍。紫杉醇细胞毒性增加与高血糖介导的TXNIP表达的相加效应相关，在高血糖条件下比正常血糖条件下更明显。
我们的研究为高血糖代谢状况在癌症生物学和治疗中的相关性开辟了新的视角，特别是鉴于糖尿病的流行。
