DNA Replication and How it Affects Cancer Research

By Talita Naveed

DNA replication is the most important and valuable process in the body; understanding it on a molecular level unlocks a plethora of developments in medical research. DNA, or Deoxyribonucleic Acid, is the molecule that carries the genetic information for the development and function of an organism (National Human Genome Research Institute, 2025). DNA is composed of two strands that wrap around into a double helix shape. In between the strands, which are made of deoxyribose and phosphate groups, there are four bases: Adenine, Guanine, Cytosine, and Thymine. The adjacent base pairs are complementary to one another and have many hydrogen bonds between them that provide structural strength. The sequence of bases encodes biological processes like protein synthesis.

The nature of DNA replication is semi-conservative, meaning that half of the new double helix comes from the original ‘parent’ molecule. Due to the antiparallel strands with opposing polarity, only one strand can be synthesized at a time, and that strand is bestowed the title of the leading strand (Mechanobiology Institute, University of Singapore, n.d.). The original DNA molecule is unwound by the enzyme DNA helicase. Simultaneously, on the other strand, another enzyme, DNA polymerase, synthesizes DNA using the other strand as a template. Once DNA helicase breaks the hydrogen bonds between the base pairs, free nucleotides in the nucleoplasm are attracted to the exposed complementary base pairs, and the adjacent nucleotides are joined together through a condensation reaction by DNA polymerase. DNA replication is a tedious process that requires lots of proteins due to the specific complementary nature of the bases, which also makes it very accurate.

But how does all of that relate to cancer? Cancer is caused by uncontrollable cell division, which can be triggered by random mutations in the DNA, and defects in DNA replication cause mutations. When errors take place in DNA replication, they can cause breaks in the DNA that make it more likely for chromosome fragments to rearrange themselves and activate genes which then lead to rapid and uncontrollable cell division (National Cancer Institute, 2019). The RepID protein is in charge of signaling to the other proteins to keep replication controlled. RepID signals to CRL4, an enzyme that binds to chromatin to stimulate the protein CDT1 to break down, stopping replication from happening more than once per division. If RepID does not work properly, then it cannot tell CRL4 and CDT1 to carry out their functions, and CDT1 builds up, resulting in excess replication. The birth of cancer genetically depends on the protein CDT1 building up. What happens if you take out CDT1 entirely? If CDT1 is removed, then DNA replication becomes completely unmonitored, and the chance of developing cancer increases by almost one hundred percent. The protein CDT1 forms through protein synthesis, which stems from a specific sequence of bases that encode the process of protein synthesis, as DNA encodes every instruction and process in your cells. The structure of DNA and the process of DNA replication in cell division are intertwined with the formation of cancer, which is why comprehending such basic processes is vital for cancer research and for finding ways to inhibit uncontrollable division.

Our bodies are sentient and contain naturally occurring chemicals (called growth factors) that control cell growth, as explained with RepID and CRL4. Just like RepID sets off a chain reaction by sending signals to other proteins, growth factors attach to receptors on cell surfaces and send signals inside the cell. Scientists have developed cancer growth blockers, which are drugs that block growth factors to prevent constant cell division by cancer cells. Ensuring that all the proteins and enzymes in your body function perfectly is an extremely difficult task, as many are in hard-to-reach places, so preventing signals from reaching cancer cells to eventually stop them is the idle approach. However, like all drugs, multiple nasty side effects can occur. If you must use drugs, then it ought to be worth the horrid side effects (Cancer Research UK, n.d.). Scientists could potentially go to the root of cancer cells and modify their DNA sequences to prevent the instructions for the cell cycle, causing the cancer cell to die off. Since a gene is a sequence of nucleotides in the DNA, gene therapy is a new innovative treatment for cancer cells that results in their death. By introducing new genes into the cancer cell or surrounding cells, cell division can be slowed or stopped completely. Boosting the immune system to target cancer cells is also another type of gene therapy called immunotherapy. If you occupy the binding sites on growth factors of cancer cells with a genetically modified gene that is complementary to it, then the cancer cell will not be able to continue dividing, which, in theory, would lead the cell to death (National Library of Medicine et al., n.d.).

Cancer is vicious, and attacking it at the root directly is one of the most cutting-edge developments in cancer research. Gene therapy might be the answer. Targeting cancer cells is extremely difficult since surrounding healthy cells must not be damaged in the process. Although new forms of radiotherapy and chemotherapy have been developed to have a less aggressive approach they don’t have the best chances, which is why understanding the genetics behind cancer and stopping the development right at the very beginning is most effective and important for the patient. Researching the multitude of ways cells can be killed just by modifying their DNA will result in a better approach to cancer treatments and therefore provide premium care for patients worldwide.

References

1. National human genome research institute. (2025). Deoxyribonucleic Acid (DNA). National Human Genome Research Institute. Retrieved February 2, 2025, https://www.genome.gov/genetics-glossary/Deoxyribonucleic-Acid-DNA

2. Mechanobiology institute, University of Singapore. (n.d.). genome regulation. Genome regulation. Retrieved February 2, 2025, https://www.mbi.nus.edu.sg/mbinfo/how-is-dna-replicated/

3. National cancer institute. (2019). Keeping DNA Replication in Check | Center for Cancer Research. Center for Cancer Research. Retrieved February 2, 2025, 

https://ccr.cancer.gov/news/milestones-2019/article/keeping-dna-replication-in-check

4. Cancer Research UK. (2024). Cancer growth blockers | Targeted cancer drugs. Cancer Research UK. Retrieved February 2, 2025, https://www.cancerresearchuk.org/about-cancer/treatment/targeted-cancer-drugs/types/cancer-growth-blockers

5. National Library of Medicine. (n.d.). Gene therapy: advances, challenges and perspectives. Gene therapy: advances, challenges and perspectives. Retrieved February 2, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC5823056/

Edited by Lamisa Chowdhury