Cancer is a disease characterized by DNA mutations. These mutations, while sometimes small, can cause havoc in a cell’s regulatory systems. If a mutation occurs in the right protein at the right time, cancer is likely to result.
Many cancers have what is called a “gain of function” mutation. This means that a protein undergoes a mutation that increases its activity or obtains a wholly different function in rare cases. When this type of mutation occurs, it usually leads to unregulated activation of the mutated protein’s pathway. Researchers use this knowledge and decades of research to create drugs targeted at these critical gain of function mutations.
One common target for lung and other cancers is the BRAF signaling pathway. This pathway is named after the kinase BRAF and normally regulates cellular proliferation, growth, and differentiation. Systems like this are usually heavily regulated, so when a gain of function mutation occurs, it can lead to uncontrolled cell growth. If this mutation occurs in a cancer cell, cancer becomes “aggressive” and far more dangerous.
BRAF mutations occur in a variety of cancers, from lung cancer to skin cancer. Its relatively well-researched background has made it a common biomarker to test against. Biomarkers are biological indicators that can diagnose a patient or obtain their prognosis. The most common biomarker test is an immunohistochemistry test, which essentially stains a tissue sample for a particular protein. In a new study, a team from the Chang Gung Memorial Hospital in Taiwan designed a highly sensitive RT-qPCR (real-time quantitative PCR) test that could identify the common BRAF V600E mutation it could help improve the accuracy of current tests.
RT-qPCR is a sort of DNA scanning method. It uses a guide called a primer to read off and exponentially replicate the target gene so researchers can see something as small as a single mutation. In this case, the primers were designed to identify two common BRAF V600E DNA mutations. The team tested their RT-qPCR test on 306 lung cancer patients and found two patients positive for the mutation. These findings were confirmed using the standard immunohistochemical tests. They also confirmed this on 6 other cancer specimens, confirming that the RT-qPCR method could indeed identify BRAF V600E positive cancers.
While the RT-qPCR method outlined in this study didn’t outperform the immunohistochemical tests, it does a few things right. Immunohistochemical tests can sometimes give false readings due to off-target binding. It is also qualitative data (visual) rather than quantitative (numerical), which can cause bias in data analysis. A big issue is that a primer needs to be designed for each possible mutation, which would make this method quite hard for some of the more diverse mutations out there.
The study concludes, “In summary, a highly sensitive and BRAF V600E/K mutation-specific RT-qPCR was established for detection of BRAF V600E/K mutation and results found low incidence of the BRAF V600E mutation in the lung cancer population of southern Taiwan.”
Sources: Nature Scientific Reports, European Society for Medical Oncology
