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Updated: Jun 5, 2025
Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material
Published on: August 1, 2018
Enhancing negative control selection: A comparative analysis of random and targeted sampling techniques for obtaining
Komal Mehta1, Archana Sharma1, Anurag Mehta2
1Biorepository, Department of Research, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi 110085, India.
Abstract:
Molecular profiling is a crucial aspect of cancer therapy selection, underscoring the necessity for representative sampling of both tumor and normal tissues. While much attention has been given to representative tumor sampling, there has been a notable lack of exploration into the issue of poor RNA quality in normal breast tissue processing. Normal breast tissue from the same patient is often used as a negative control for most "-omics" experiments. RNA extracted from normal breast tissues frequently contains nucleic acids from surrounding adipocytes, endothelial cells, and immune cells, leading to a low representation of ductal elements and skewed results. Therefore, ensuring a complete representation of breast glandular tissue is imperative. The study aimed to investigate the variations in RNA enrichment between a random sampling technique and a targeted sampling approach when visually selecting normal breast tissue sections as negative controls for "-omics" experiments. Fifteen female breast cancer subjects who underwent Modified Radical Mastectomy were selected for the study. Normal Breast tissue was visually examined, and samples were collected from random fat pockets (random sampling) and fibromuscular grey-white streak areas (targeted sampling). RNA was isolated, followed by spectrophotometric analysis, agarose gel electrophoresis and Agilent Tape station analysis. Histopathological assessments and a gene expression study for housekeeping genes were performed on both subsets. Tissues collected through targeted sampling exhibited significantly higher RNA quality than those obtained via random sampling. Histopathological analysis revealed cellular areas abundant in terminal ductular units within the targeted samples, and a final validation qPCR showed that the targeted samples were the most representative of normal breast glandular tissue. The comparative analysis of the two sampling methods clearly indicates that the targeted approach, with its superior accuracy and reliability, is the more practical choice for obtaining representative normal breast glandular tissue for "-omics" experiments.
Insights
Targeted sampling of normal breast tissue yields higher RNA quality and better representation of glandular elements compared to random sampling. This improved method is crucial for accurate "-omics" experiments in cancer research.
Area of Science:
- Oncology
- Molecular Biology
- Genomics
Background:
- Molecular profiling guides cancer therapy selection, requiring representative tumor and normal tissue samples.
- Normal breast tissue is vital as a negative control in -omics experiments but often yields poor RNA quality due to contamination from non-ductal cells.
- Ensuring accurate representation of breast glandular tissue is critical for reliable -omics data.
Purpose of the Study:
- To investigate RNA enrichment variations between random and targeted sampling of normal breast tissue for -omics studies.
- To compare the quality and representativeness of normal breast tissue samples obtained through different sampling techniques.
Main Methods:
- Normal breast tissue samples were collected from 15 female breast cancer patients undergoing mastectomy.
- Two sampling methods were employed: random sampling from fat pockets and targeted sampling from fibromuscular areas.
- RNA isolation, quality assessment (spectrophotometry, gel electrophoresis, Agilent Tape station), histopathology, and qPCR for housekeeping genes were performed.
Main Results:
- Targeted sampling demonstrated significantly higher RNA quality compared to random sampling.
- Histopathological analysis confirmed targeted samples were rich in terminal ductular units, representing glandular tissue.
- qPCR validated targeted samples as the most representative of normal breast glandular tissue.
Conclusions:
- Targeted sampling of normal breast tissue provides superior RNA quality and glandular representation over random sampling.
- This method enhances the accuracy and reliability of -omics experiments by ensuring representative negative controls.
- The targeted approach is recommended for obtaining high-quality normal breast tissue for -omics research.
