Gururajanna B, Al-Katib A A, Li Y W, Aranha O, Vaitkevicius V K, Sarkar F H
Department of Pathology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Int J Mol Med. 1999 Nov;4(5):501-7. doi: 10.3892/ijmm.4.5.501.
Pancreatic cancer is the fifth leading cause of cancer related deaths in the United States. Despite many recent advances in the treatment modalities, the mortality rate still remains very high. Paclitaxel (Taxol) and Caffeine have been used for the treatment of this disease, however the molecular mechanisms of these agents are not fully understood, which may be partly responsible for the failure of these agents in the treatment of pancreatic cancer. Human pancreatic adenocarcinoma cell lines, HPAC and PANC-1 containing wild-type and mutant p53 respectively, were used to investigate the effects of Taxol and Caffeine on cell growth, and their effects on the modulation of cell cycle and apoptosis related genes. Protein extracts from these cells treated with 100 nM of Taxol or 4 mM of Caffeine were subjected to Western blot analysis for this study. Drug treated cells were also analyzed to calculate the number of cells undergoing apoptosis. Dose and time dependent growth inhibition was observed in both PANC-1 and HPAC cells when treated with either Taxol or Caffeine. Western blot analysis showed an up-regulation of p21WAF1 in both cell lines treated with either Taxol or Caffeine. Furthermore, down-regulation of cyclin B and cdk1 was observed in Taxol and Caffeine treated HPAC cells. However, the results were drastically different in PANC-1 cells where cyclin B was down regulated only by Caffeine treatment and the level of cdk1 protein was undetectable in this cell line. Moreover, up-regulation of p53 and down-regulation of Bcl-2 was observed only in HPAC cells treated with Taxol. Apoptotic cell death analysis showed increasing number of cells undergoing apoptosis between 24 and 48 h of Caffeine treatment, however only Taxol showed greater than 50% cells under-going apoptosis only in HPAC cells. The up-regulation of p21WAF1 and down-regulation of cyclin B and cdk1 suggest their possible roles in G2/M cell cycle arrest caused by both Taxol and Caffeine as reported earlier. From these results we conclude that the differential molecular changes observed in this study may determine the cellular effects of these agents on pancreatic adenocarcinoma cells and that the effects of chemotherapeutic agents may be determined by the endogenous status of p53 mutation and, in turn, may determine the therapeutic effects of these agents in the treatment of pancreatic cancer.
胰腺癌是美国癌症相关死亡的第五大主要原因。尽管近年来治疗方式有了许多进展，但死亡率仍然很高。紫杉醇（泰素）和咖啡因已被用于治疗这种疾病，然而这些药物的分子机制尚未完全了解，这可能部分是导致这些药物治疗胰腺癌失败的原因。分别含有野生型和突变型p53的人胰腺腺癌细胞系HPAC和PANC-1，被用于研究紫杉醇和咖啡因对细胞生长的影响，以及它们对细胞周期和凋亡相关基因调控的影响。用100 nM紫杉醇或4 mM咖啡因处理这些细胞后提取蛋白质提取物，用于本研究的蛋白质印迹分析。还对药物处理的细胞进行分析以计算发生凋亡的细胞数量。用紫杉醇或咖啡因处理时，在PANC-1和HPAC细胞中均观察到剂量和时间依赖性的生长抑制。蛋白质印迹分析显示，用紫杉醇或咖啡因处理的两种细胞系中p21WAF1均上调。此外，在紫杉醇和咖啡因处理的HPAC细胞中观察到细胞周期蛋白B和细胞周期蛋白依赖性激酶1（cdk1）下调。然而，在PANC-1细胞中结果截然不同，其中细胞周期蛋白B仅通过咖啡因处理下调，并且在该细胞系中未检测到cdk1蛋白水平。此外，仅在用紫杉醇处理的HPAC细胞中观察到p53上调和Bcl-2下调。凋亡细胞死亡分析显示，咖啡因处理24至48小时之间发生凋亡的细胞数量增加，然而只有紫杉醇在HPAC细胞中显示超过50%的细胞发生凋亡。如先前报道，p21WAF1上调以及细胞周期蛋白B和cdk1下调表明它们可能在紫杉醇和咖啡因引起的G2/M细胞周期阻滞中发挥作用。从这些结果我们得出结论，本研究中观察到的不同分子变化可能决定这些药物对胰腺腺癌细胞的细胞效应，并且化疗药物的效应可能由p53突变的内源性状态决定，进而可能决定这些药物在治疗胰腺癌中的疗效。
