Identification of EGFR Gene Exon 21 and 20 Mutations Based on the Method of PCR Sequencing in Paraffin Biopsy of Lung Cancer

Background and aim: One of the causes of cancerous tumours is mutations that occur in essential genes, such as genes that control cell growth and division. EGFR is an intermembrane protein that plays a role in cell growth, proliferation and differentiation with its tyrosine kinase activity.
Considering the increasing prevalence of lung cancer and the identification of EGFR gene mutations as one of its causes, designing a non-invasive and quantitative method with early detection power to investigate and identify biomarkers related to lung cancer can play a significant role in determining this cancer. We designed a more accurate and cost-effective molecular system to detect exon 20 and 21 mutations to identify responses to targeted drug therapy and monitor cancer treatment, considering the predictive value of this gene and screening in patients.
Materials and methods: In this research, 20 positive paraffin biopsy samples of lung cancer were used. Since the samples used are embedded in paraffin, we must first deparaffinize the samples and then perform the steps. We used Hexadecane to deparaffinize the samples. After deparaffinization of the tissue for extraction, it was necessary to digest the tissue, which was performed with Proteinase k.
In the next step we used PZP kit for DNA extraction. As a last step we performed quantitative and qualitative analysis on them to confirm the presence of DNA, and PCR-Sequencing of exon 20 and 21 was performed.
Results: During the research conducted on lung cancer tissue, in general, out of 20 samples examined from exon 20 and 21, 9 of our samples mutations with rs 1151171 were observed, all of which were in exon 20, where Nucleobase G was changed to A, and in exon 21 No mutations were observed in our samples. The sequencing PCR method identified the mutation in exons 20 and 21.
Conclusion: For people with lung cancer, their treatment methods include chemotherapy, which has various drugs available for chemotherapy, and their effect is on the growth of cells. Before chemotherapy, the patient's tissue must be examined for the presence or absence of mutations. Examine the EGFR gene so that they can prescribe a suitable drug for chemotherapy. According to the results, a point mutation in exon 20 of the EGFR gene is related to cancer progression and the response to drug therapy.