Fazekas Judit, Grunt Thomas W, Jensen-Jarolim Erika, Singer Josef
Comparative Medicine, The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University of Vienna and University of Vienna, Vienna, Austria.
Institute of Pathophysiology and Allergy Research, Center of Physiology, Pathophysiology and Immunology, Medical University of Vienna, Vienna, Austria.
Oncotarget. 2017 May 23;8(21):35076-35087. doi: 10.18632/oncotarget.16623.
BACKGROUND/AIM: Cancer cell lines are indispensible surrogate models in cancer research, as they can be used off-the-shelf, expanded to the desired extent, easily modified and exchanged between research groups for affirmation, reproduction or follow-up experiments.As malignant cells are prone to genomic instability, phenotypical changes may occur after certain passages in culture. Thus, cell lines have to be regularly authenticated to ensure data quality. In between experiments these cell lines are often stored in liquid nitrogen for extended time periods.Although freezing of cells is a necessary evil, little research is performed on how long-term storage affects cancer cell lines. Therefore, this study investigated the effects of a 28-year long liquid nitrogen storage period on BT474 cells with regard to phenotypical changes, differences in cell-surface receptor expression as well as cytokine and gene expressional variations.
Two batches of BT474 cells, one frozen in 1986, the other directly purchased from ATCC were investigated by light microscopy, cell growth analysis, flow cytometry and cytokine as well as whole-transcriptome expression profiling.
The cell lines were morphologically indifferent and showed similar growth rates and similar cell-surface receptor expression. Transcriptome analysis revealed significant differences in only 26 of 40,716 investigated RefSeq transcripts with 4 of them being up-regulated and 22 down-regulated.
This study demonstrates that even after very long periods of storage in liquid nitrogen, cancer cell lines display only minimal changes in their gene expression profiles. However, also such minor changes should be carefully assessed before continuation of experiments, especially if phenotypic alterations can be additionally observed.
背景/目的：癌细胞系是癌症研究中不可或缺的替代模型，因为它们可以现成使用，能扩增到所需规模，易于修饰，且可在研究团队之间交换以进行验证、重复或后续实验。由于恶性细胞易于发生基因组不稳定，在培养一定代数后可能会出现表型变化。因此，必须定期对细胞系进行鉴定以确保数据质量。在实验间隙，这些细胞系常被长时间保存在液氮中。尽管细胞冻存是无奈之举，但关于长期保存如何影响癌细胞系的研究却很少。因此，本研究调查了28年液氮保存期对BT474细胞在表型变化、细胞表面受体表达差异以及细胞因子和基因表达变化方面的影响。
通过光学显微镜、细胞生长分析、流式细胞术以及细胞因子和全转录组表达谱分析，对1986年冻存的一批BT474细胞和直接从美国典型培养物保藏中心（ATCC）购买的另一批BT474细胞进行了研究。
这两批细胞系在形态上无差异，生长速率相似，细胞表面受体表达也相似。转录组分析显示，在40716个研究的RefSeq转录本中，只有26个存在显著差异，其中4个上调，22个下调。
本研究表明，即使在液氮中保存很长时间后，癌细胞系的基因表达谱变化也很小。然而，在继续实验之前，即使是这种微小的变化也应仔细评估，特别是如果还能观察到表型改变的话。
