新鲜冷冻和福尔马林固定石蜡包埋胃黏液腺癌组织中miRNA表达谱的比较

目的通过miRNA芯片对比分析新鲜冷冻与福尔马林固定石蜡包埋的胃黏液腺癌组织中miRNAs的表达谱,初步探讨大量存档且有完整病理资料的福尔马林固定石蜡包埋样本能否很好的应用于miRNA的表达分析。方法选取6例2017年术前未行放、化疗的胃黏液腺癌患者手术切除同一组织的新鲜冷冻标本和福尔马林固定石蜡包埋样本,进行镜下形态学观察并提取总RNA、质检,然后芯片杂交、信号扫描、数据转换后进行对比、相关性及表达谱的主成分分析。结果新鲜冷冻标本中提取的总RNA质量相对较高,保存度比较完整,从福尔马林固定石蜡包埋组中提取的总RNA有不同程度的降解。芯片杂交后统计结果显示两组样本中miRNA的表达谱差异有显著性,以fold_change(差异倍数log2)的绝对值≥2为标准,分别有76个(P<0.05)和14个(P<0.01)miRNA呈差异表达,但配对标本之间均有较好的相关性。结论配对的新鲜冷冻与福尔马林固定石蜡包埋的胃黏液腺癌组织中miRNAs的表达谱差异有显著性,所以用福尔马林固定石蜡包埋组织分析miRNA基因的绝对表达值,结果可能不准确,能否反映全部miRNA基因的相对表达也需进一步的实验去证实。

Comparison of the miRNA expression profiles in fresh frozen and formalin-fixed paraffin embedded gastric mucinous carcinoma

Purpose To compare and analyze the expression profiles of miRNAs in freshly frozen and formalin-fixed paraffin embedded(FFPE)tissue samples by miRNA microarray,and to explore whether a large number of FFPE samples with complete data could be well applied to the expression analysis of miRNA.Methods Paired 6 cases of gastric mucinous carcinoma tissue were selected to the comparison of the miRNA expression profiles in fresh frozen and paired formalin-fixed paraffin embedded samples.All samples were obtained from patients who had not undergone radiation and chemotherapy before surgery in 2017.Then the proportion of tumor cells was checked by microscope,total RNA was extracted and miRNA chip hybridization was done.T test,correlation analysis and PCA was performed by staistical analysis.Results The total RNA extracted from the fresh frozen samples was of relatively high quality and the degree of preservation was relatively complete.The total RNA from FFPE samples showed degradation in some extent.The statistical results of microarray hybridization showed that there was a significant difference in the expression profile of miRNA between the two groups.Taking the absolute value of fold_change(multiple of difference log2)≥2 as the standard,76(P<0.05)and 14(P<0.01)miRNA were differentially expressed respectively,but there was a good correlation between the the paired samples.Conclusion There is a significant different expression of miRNA profiles between paired fresh frozen and FFPE gastric mucinous carcinoma tissue,so the absolute expression of miRNA analyzed using FFPE tissue may not be accurate,and whether it can reflect the relative expression of miRNA genes also needs to be confirmed by further experiments.