Ionizing Radiation Deregulates the MicroRNA Expression Profile in Differentiated Thyroid Cells

Area of Science:

• Molecular Biology
• Oncology
• Radiation Biology

Background:

• Ionizing radiation (IR) is a known risk factor for papillary thyroid cancer.
• IR is reported to deregulate microRNA expression, a key factor in thyroid carcinogenesis.

Purpose of the Study:

• Investigate IR's impact on microRNA expression in normal thyroid cells (FRTL-5 CL2).
• Assess IR's effect on thyroid cancer cell radiosensitivity, particularly in anaplastic thyroid carcinoma (8505c).

Main Methods:

• Global microRNA profiling of irradiated FRTL-5 CL2 cells (5 Gy X-ray).
• Validation of specific microRNAs (e.g., miR-10b-5p, miR-199a-3p) using qRT-PCR, Western blot, and luciferase assays.
• Assessment of DNA repair (e.g., γH2AX, ATM/ATR activation) and radiosensitivity (MTT assays).

Main Results:

• IR significantly altered miR-10b-5p and miR-199a-3p expression in FRTL-5 CL2 cells.
• Both microRNAs negatively impacted DNA repair efficiency, reducing ATM/ATR activation and increasing γH2AX.
• Overexpression of miR-10b-5p decreased viability in irradiated thyroid cancer cells (8505c).

Conclusions:

• IR deregulates microRNA expression, affecting DNA double-strand break repair in thyroid cells.
• miR-10b-5p overexpression shows potential as a therapeutic strategy to enhance anaplastic thyroid cancer radiosensitivity.