Abstract

Biomarkers are biological characteristic to measure and evaluate normal and pathological states. To define expression-based molecular biomarkers, high-quality tissue samples are a prerequisite for the preparation of standard RNA. It is already known that RIN number defines the RNA quality, however its relation with A_260/280 ratio and Ct value is not defined clearly; therefore, understanding an association will provide a reliable method for describing RNA quality. Multiple cryopreserved human tumor tissue types from ACTREC Biorepository and TMH-INTTR were analyzed for the effect of storage time on RNA quality. The RNA from tumor samples were isolated and analyzed by RIN, A_260/280 ratio, and Ct value to establish inter-relationships. Around 50% samples had a RIN of ≥ 6.9 and A_260/280 ≤ 2.04; 27% had a RIN ≥ 5 and A_260/280 ≤ 2.08, and remaining 23% displayed RIN < 5 and A_260/280 > 2.08. However, the RNA quality has no association with the storage period of tissue samples. Moreover, all samples which had A_260/280 ≤ 2.08 showed acceptable Ct values of 17–24. The data clearly suggests that the A_260/280 ratio is able to predict RNA quality. To the best of our knowledge, this is the first Indian report analyzing the labile nucleic acid-RNA quality from different cancer tissue types cryopreserved for diverse time periods. In conclusion, RIN and A_260/280 ratio can help in predicting the quality of RNA independently; however, both together provide better assurance for further downstream processing.

Graphic abstract

中文翻译：

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建立RIN和A260 / 280之间的相关性，以及对冷冻保存的癌症生物样本中影响RNA质量的因素进行多变量评估。

摘要

生物标志物是测量和评估正常和病理状态的生物学特征。要定义基于表达的分子生物标记，高质量的组织样品是制备标准RNA的前提。众所周知，RIN数决定了RNA的质量，但是与A _260/280比值和Ct值的关系尚不清楚。因此，了解关联将提供描述RNA质量的可靠方法。分析了来自ACTREC Biorepository和TMH-INTTR的多种冷冻保存的人类肿瘤组织类型的保存时间对RNA质量的影响。分离肿瘤样品中的RNA，并通过RIN，A _260/280比率和Ct值进行分析，以建立相互关系。大约50％的样品的RIN≥6.9，A_{260/280≤2.04}  ；27％的RIN≥5并且A _{260/280≤2.08}  ，其余23％的RIN <5和A _260/280  > 2.08。但是，RNA的质量与组织样本的保存期限无关。此外，所有A _{260/280≤2.08的}样品 均显示出可接受的17-24的Ct值。数据清楚地表明A _260/280的比率能够预测RNA的质量。据我们所知，这是第一份印度报告，分析了在不同时间段内冷冻保存的不同癌症组织类型的不稳定核酸-RNA的质量。总之，RIN和A _260/280比率可以帮助独立预测RNA的质量；但是，两者共同为进一步的下游处理提供了更好的保证。

图形摘要