Investigation of long non-coding RNA PCAT6 expression in head and neck cancer cell lines treated with radiation

Head and neck cancers (HNC) are squamous cell carcinomas originating from the mucosal surfaces of the upper respiratory and digestive systems and the epithelial tissues beneath them. They are among the most common types of cancer worldwide and are notable for their high mortality rates. Most HNC cases are diagnosed at advanced stages, which limits the effectiveness of treatment. Despite multimodal treatments such as surgery, radiotherapy, and chemotherapy, radiation resistance and treatment-related toxicity remain significant obstacles. This situation highlights the need for personalised treatment strategies based on molecular biomarkers to predict individual treatment responses. In recent years, it has been demonstrated that long non-coding RNAs (lncRNAs), which play a role in the epigenetic and transcriptional regulation of gene expression, have important roles in cancer biology. While some lncRNAs can increase cell proliferation, invasion, and metastatic capacity in an oncogenic manner, others have been shown to inhibit cell proliferation and trigger apoptosis through tumour-suppressing functions. In this study, the expression of the gene that codes lncRNA PCAT6, which has been reported to have an oncogenic effect in various types of cancer, and its response to radiation were investigated in HNC cells. The basal expression levels of PCAT6 were compared using the human hypopharyngeal squamous cell carcinoma cell line (FaDu) and the normal human oesophageal epithelial cell line (HET-1A). Subsequently, FaDu cells were exposed to radiation at doses of 0, 2, 4, and 6 Gy, and changes in PCAT6 expression were evaluated at time points of 0, 24, 48, and 72 hours. PCAT6 expression increased by 127% in the FaDu cell line compared to the HET-1A cell line. This finding suggests that PCAT6 may play an oncogenic role in HNC cells. In radiation-exposed FaDu cells, no clear expression pattern was observed; however, each dose showed significant expression changes at different time points. PCAT6 expression decreased in cells exposed to 2 and 4 Gy doses during the 48–72-hour time period; this suppression was most pronounced in cells exposed to the 4 Gy dose. In contrast, a re-increase in PCAT6 expression was detected in the 6 Gy group at 72 hours, suggesting the presence of radiation-resistant cell subpopulations and a potential association between PCAT6 and radiation resistance. In conclusion, this study demonstrates that PCAT6 plays an oncogenic role in head and neck cancer cells. Additionally, it was determined that PCAT6 expression varies depending on the radiation dose administered and exhibits a complex expression profile.