What Is the Main Idea?

Serum biomarkers can be detected by analyzing blood samples. In the open-access research article “Screening of Serum miRNAs as Diagnostic Biomarkers for Lung Cancer Using the Minimal-Redundancy-Maximal-Relevance Algorithm and Random Forest Classifier Based on a Public Database”, published in the journal Public Health Genomics, the authors describe an approach for screening serum miRNAs to see whether they are useful as diagnostic biomarkers for lung cancer.

What Else Can You Learn?

In this blog post, RNAs (particularly microRNAs) and their roles in the body are discussed, along with how serum biomarkers can aid the early diagnosis of lung cancer.

What Is a Serum Biomarker?

The term “biomarker” is short for “biological marker”. Biomarkers are measurable characteristics, such as molecules in your blood or changes in your genes, that indicate what is going on in the body. They can indicate that your body is working normally, the development or progress of a disease or condition, or the effects of a treatment. Serum biomarkers are biomarkers that can be detected by analyzing blood samples that are taken from patients (sometimes called “liquid biopsies”). Whole blood is made up of red blood cells, white blood cells, platelets, and clotting factors in a liquid called plasma. Serum is the liquid that you have left if all the cells and clotting factors are removed from the blood.

What Are the Advantages of Serum Biomarkers?

Because serum biomarkers can be easily obtained from samples taken during a standard blood test, it is relatively cheap to obtain large enough samples for analysis. In addition, the healthcare practitioners that take the samples do not need any specialist expertise. For these reasons, studies are underway to investigate how serum biomarkers can be used to diagnose a wide range of conditions, including cancer.

What Did the Research Article Investigate?

Lung cancer is one of the most common types of cancer, accounting for nearly one in six deaths worldwide in 2020. It can start in any part of the lungs or the airways that lead to the lungs from the windpipe (trachea), and is difficult to detect in its early stages. Like many other types of cancer, patients with lung cancer have better outcomes if their tumors are detected early. In this study, the authors investigated whether molecules found in blood serum called microRNAs have potential as biomarkers for the diagnosis of lung cancer and tested a method to identify them more efficiently. They screened 416 microRNAs and identified 5 that were present at different levels in people with lung cancer compared with people without lung cancer.

What Are microRNAs?

Your genes are short sections of DNA (deoxyribonucleic acid) that carry the genetic information for the growth, development, and function of your body. Each gene carries the code for a protein or an RNA (ribonucleic acid). Proteins do most of the work in cells and have lots of different functions in the body, including structural roles, catalyzing reactions (enzymes), and acting as signaling molecules. There are several different types of RNA, each with different functions, and they play important roles in normal cells and the development of disease.

Messenger RNAs are single-stranded copies of genes that are made when a gene is switched on (expressed). In a cell, long strings of double-stranded DNA are coiled up as chromosomes in a part of the cell called the nucleus (the cell’s command center). Chromosomes are too big to move out of the nucleus to the place in the cell where proteins are made, but a messenger RNA copy of a gene is small enough. In other words, messenger RNA carries the message of which protein should be made from the chromosome to the cell’s protein-making machinery.

MicroRNAs are much smaller than messenger RNAs. They do not code for proteins but instead play important roles in regulating genes. They can inhibit (silence) gene expression by binding to complementary sequences in messenger RNA molecules, stopping their “messages” from being read and preventing the proteins they code for from being made. Some microRNAs also activate signaling pathways inside cells, turning processes on or off.

Why Do microRNAs Have Potential as Serum Biomarkers?

MicroRNAs are present in body fluids such as urine, saliva, and blood. In addition, unlike some types of molecule that are relatively “unstable” and break down quickly, microRNAs that circulate in the blood are very stable. As a result, collecting samples is relatively cheap and easy, and microRNAs can also be easily detected and quantified in diagnostic laboratories.

How Are microRNAs Involved in Cancer?

MicroRNAs are involved in different types of cancer in a variety of ways. They may be expressed at abnormally high or low levels, affecting whether or not cells start to divide and multiply, or can enable cells to avoid processes that would normally cause cell death (this process is called “apoptosis”; it maintains the balance of cells in the body and removes cells that have become damaged). If microRNAs are expressed at different levels in cancer cells compared with normal cells, they could be used to indicate the presence of cancer in the body and aid earlier diagnosis. Different levels of particular microRNAs can also indicate the likely prognosis of patients with some types of cancer, and one particular microRNA (miR-506) has been shown to promote the apoptosis of cervical cancer cells.

What’s the Take-Home Message?

Over the last decade, biomarker testing has become a crucial part of optimizing the diagnosis and treatment of lung cancer. MicroRNAs in serum are biomarkers that are easy to collect and analyze, and show promise for screening to diagnose lung cancer at an early stage in the future.

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