Pedersen Inge Søkilde, Thomassen Mads, Tan Qihua, Kruse Torben, Thorlacius-Ussing Ole, Garne Jens Peter, Krarup Henrik Bygum
Molecular Diagnostics, Clinical Biochemistry, Aalborg University, Aalborg, Denmark.
Clinical Cancer Research Center, Aalborg University Hospital, Aalborg, Denmark.
Mol Med. 2018 Nov 16;24(1):57. doi: 10.1186/s10020-018-0058-x.
Gene expression profiles of normal and tumor tissue reflect both differences in biological processes taking place in vivo and differences in response to stress during surgery and sample handling. The effect of cold (room temperature) ischemia in the time interval between surgical removal of the specimen and freezing is described in a few studies. However, not much is known about the effect of warm (body temperature) ischemia during surgery.
Three women with primary operable breast cancer underwent in situ biopsies from normal breast and tumor tissue prior to radical mastectomy. Ex vivo biopsies from normal and tumor tissue were collected immediately after surgical excision. The putative effects on gene expression of malignancy (tumor versus normal), surgical manipulation (post- versus pre-surgical) and interaction between the two (differences in effect of surgical manipulation on tumor and normal samples) were investigated simultaneously by Generalized Estimating Equation (GEE) analysis in this self-matched study.
Gene set enrichment analysis (GSEA) demonstrates a marked difference in effect of surgical manipulation on tumor compared to normal tissue. Interestingly, a large proportion of pathways affected by ischemia especially in tumor tissue are pathways considered to be specifically up regulated in tumor tissue compared to normal.
The results of this study suggest that a large contribution to this differential expression originates from altered response to stress in tumor cells rather than merely representing in vivo differences. It is important to bear this in mind when using gene-expression analysis to deduce biological function, and when collecting material for gene expression profiling.
正常组织和肿瘤组织的基因表达谱既反映了体内发生的生物学过程差异，也反映了手术及样本处理过程中对应激反应的差异。少数研究描述了标本手术切除至冷冻期间冷（室温）缺血的影响。然而，关于手术期间热（体温）缺血的影响，人们了解得并不多。
三名患有原发性可手术乳腺癌的女性在根治性乳房切除术前，对正常乳腺和肿瘤组织进行了原位活检。手术切除后立即收集正常组织和肿瘤组织的离体活检样本。在这项自我匹配研究中，通过广义估计方程（GEE）分析同时研究了恶性肿瘤（肿瘤与正常组织）、手术操作（术后与术前）及其两者之间的相互作用（手术操作对肿瘤和正常样本影响的差异）对基因表达的假定影响。
基因集富集分析（GSEA）表明，与正常组织相比，手术操作对肿瘤的影响存在显著差异。有趣的是，与正常组织相比，受缺血影响的很大一部分通路，尤其是肿瘤组织中的通路，被认为在肿瘤组织中特异性上调。
本研究结果表明，这种差异表达的很大一部分源于肿瘤细胞对应激反应的改变，而不仅仅代表体内差异。在利用基因表达分析推断生物学功能以及收集用于基因表达谱分析的材料时，牢记这一点很重要。
