Molecular Analysis of Mutations in the PD-L1 and PD-1 Genes in Squamous Cell Carcinoma of the Cervix

Abstract

 Background: Understanding the type, frequency, and location of mutations in the programmed death receptor-1 ligand (PD-L1) and programmed death receptor-1 (PD-1) genes in cervical cancer is essential for advancing our knowledge of the underlying mechanisms of gene mutation in the disease. This understanding is crucial for developing targeted therapies, improving early detection techniques, and providing individualized treatment plans for those affected by cervical cancer. This study aimed to determine mutations in PD-L1 and PD-1 genes in Squamous Cell Carcinoma of the Cervix.

Methods: This retrospective study employed a total of twenty formalin-fixed, paraffin-embedded tissue blocks of cervical cancer. The Nucleic Acid Amplification Technique was used, including DNA extraction and Polymerase Chain Reaction for DNA sequencing. The amplified fragments were sequenced using a genetic analyzer 3130xl sequencer. Kapelan Bio-Imaging Solutions software version  2.7.2 was used to measure the length of the PD-L1 and PD-1 isoforms. Data were presented as simple frequency and percentage using an Excel spreadsheet.

Results: The photomicrograph of the benign cervical cancer showed rounded to oval structures with layers of stratified squamous epithelial cells with distinct nuclei and no signs of dysplasia. In contrast, the photomicrograph of the malignant cervical cancer tissue showed dysplasia, nuclear polymorphism, increased nucleo-cytoplasmic ratio, and disorganized tissue architecture. Single nucleotide polymorphisms (SNPs) and functional mutation occurred along PD-L1 and PD1 genes respectively.  Transversion mutation occurred in 37.5% of SNPs along the PD-L1 gene, while transition mutation  occurred in 62.5% of SNPs along the PD-L1 gene. Missense mutation recorded 100% occurrence in the
PD-L1 gene, while the PD-1 gene had 80% silent mutation and 20% missense mutation respectively.

Conclusion: Mutations were found in both PD-L1 and PD-1 genes in cervical cancer cells, with a greater number of mutations in the PD-L1 gene compared to the PD-1 gene, providing potential therapeutic  targets for PD-1/PD-L1 inhibitors. As PD-1/PD-L1 blockade therapy is expected to become a prominent  cancer immunotherapy technique soon, targeting PD-1 or PD-L1 in cancer immunotherapy may effectively induce long-lasting anticancer immune responses with reduced toxicity in various cancers, particularly cervical cancer.