Does this band make sense? Limits to expression based cancer studies

Area of Science:

• Molecular Biology
• Genomics
• Cancer Research

Background:

• Reverse transcriptase polymerase chain reaction (RT-PCR) is a common method for gene expression analysis in cancer research.
• RT-PCR is susceptible to amplification of pseudogenes and other similar genomic sequences, leading to inaccurate results.
• Commonly used housekeeping genes like GAPDH and beta-actin can be unreliable due to genomic sequence similarity.

Purpose of the Study:

• To highlight the limitations of RT-PCR in gene expression analysis for cancer research.
• To emphasize the need for stringent quality control measures in RT-PCR assays.
• To recommend alternative approaches for reliable gene expression analysis.

Main Methods:

• Analysis of potential genomic DNA contamination in RNA samples.
• Evaluation of primer design strategies for avoiding pseudogene amplification.
• Assessment of reverse transcriptase reaction specificity.

Main Results:

• Genomic DNA contamination, even in trace amounts, can lead to amplification of non-target sequences, including pseudogenes.
• Designing primers across multiple exons does not reliably prevent amplification of undesirable sequences.
• Template-specific reverse transcriptase reactions may lack the specificity to determine mRNA orientation.

Conclusions:

• Cancer researchers must test for intronless genomic sequences similar to target transcripts.
• Ensuring RNA samples are completely free of genomic DNA is crucial before performing RT-PCR.
• Avoid using GAPDH and beta-actin as loading controls for reliable RT-PCR or array results.