Role of miR‐155‐5p expression and its involvement in apoptosis‐related factors in thyroid follicular carcinoma

What is known and objective Thyroid follicular carcinoma is a malignant tumor from thyroid follicular epithelium, which is prone to involve capsular and vascular invasion. The present study was conducted in order to detect the expression of microRNA‐155‐5p (miR‐155‐5p) in thyroid follicular carcinoma with an attempt to analyze its involvement in apoptosis‐related factors. Methods Forty‐five patients with thyroid follicular carcinoma made up the observation group and 45 patients with thyroid follicular adenoma were included into the control group. Tissues of thyroid follicular carcinoma and thyroid follicular adenoma were obtained from the patients, and analysed for expression of miR‐155‐5p by real‐time fluorescence quantitative PCR (qPCR). The expression of cysteine‐containing aspartic acid protein hydrolase‐3 (Caspase‐3) in thyroid follicular carcinoma was detected with the use of Western Blot analyses. Immunohistochemical method was used to detect the expression of B‐cell lymphoma protein‐2 (Bcl‐2) in thyroid follicular carcinoma. Results There was significant difference in the expression of miR‐155‐5p between the two groups (Observation vs Control: 1.46 ± 0.42 vs 0.98 ± 0.33 P  < .05). The expression of miR‐155‐5p was significantly different in the maximum diameter of tumor, vascular invasion and neural invasion (maximum diameter of tumor <4 cm vs ≥4 cm: 1.36 ± 0.40 vs 1.68 ± 0.32, vascular invasion N vs Y: 1.35 ± 0.42 vs 1.69 ± 0.39, Neural invasion N vs Y: 1.35 ± 0.38 vs 1.70 ± 0.31 P  < .05). However, there was no significant difference in the expression of miR‐155‐5p in terms of different gender, age and group with or without lymph node metastasis ( P  > .05). Based on survival analysis, patients with high expression of miR‐155‐5p experienced short survival time (median survival time was 45 months, P  < .05). There was a negative correlation between miR‐155‐5p and Caspase‐3 ( r  = −.50, P  < .05). In addition, positive correlation was observed between miR‐155‐5p and Bcl‐2 ( r  = .55, P  < .05). What is new and conclusion There was increased expression of miR‐155‐5p in thyroid follicular carcinoma. The abnormal expression of miR‐155‐5p may be an independent prognostic factor for thyroid follicular carcinoma associated with cell apoptosis.