Overexpression of mir-224-3p in extrahepatic cholangiocarcinoma associated with increased dose of I131 radiotherapy: An in vitro study

Cholangiocarcinoma (CCA) affects the biliary tract, constituting a heterogeneous tumor, being the second most common type of primary liver cancer, a rare tumor type, representing approximately 3% of gastrointestinal neoplasms. Metabolic radiotherapy with Iodine-131 (131 I) is associated with cell death by apoptosis in CCA. The exposure of cells to hypoxia causes genetic and biological changes, allowing adaptation to the microenvironment. In this process, there are a series of genes regulated by hypoxia involved in multiple biological and pathological processes, such as proliferation, metabolism, angiogenesis and cell migration. In this context, MicroRNAs (miRNAs) play important roles in carcinogenesis, acting as oncogenes or tumor suppressors, in this case, the hypoxia-induced transcription factor (HIF), whose expression in primary tumor cell lines is regulated by miR-224-3p. There is also reference to its association with hepatocarcinoma. To analyze the effect of 131 I radiotherapy on miR-224-3p expression in intra (HuCCT-1) and extra-hepatic (TFK-1) CCA cell lines. Human cell lines of CCA (TFK-1 and HuCCT-1) and cholangiocytes (H69) were cultured and submitted to irradiation with 131 I at different doses (1, 20 and 60 Gy) after 2h, 48h and 12 days. Analysis of the expression of miRNAs was performed by real-time polymerase chain reaction. An alpha error of 5% was admitted. In HuCCT-1 cells, underexpression of miR-224-3p was noted under all conditions analyzed relative to control. It was also observed an increase in the expression of miR-224-3p when using the dose of 60Gy in 2h (0.31), 48h (0.39) and 12 days (0.61; P=0.001). In TFK-1 cells, overexpression of miR-224-3p was observed associated with increased dose after 2h (1Gy= 2.28, 20Gy= 3.78 and 60Gy= 5.89; P=0.001). 48 hours after irradiation with 131 I, the expression levels of this miRNA continued to be overexpressed, however, a decrease was observed at all doses (1Gy= 1.53, 20Gy= 1.41 and 60Gy= 2.91; P=0, 0001) compared to cells treated at 2 hours. miR-224-3p, a tumor suppressor in several carcinogenic pathways, has overexpression associated with an increased dose of 131 I radiotherapy in extrahepatic CCA cells.