To investigate clinical significance and function of microRNA-106b (miR-106b) in retinoblastoma tissues and cells.

We detected miR-106b expression in 51 samples of thyroid cancer and the adjacent non-tumor tissues using qRT-PCR. The expression of miR-106b was altered by corresponding vectors in thyroid cancer cells, and then BrdU cell proliferation and flow cytometry assay were performed to examine the proliferation and apoptosis of thyroid cancer cells.

The expression of miR-106b in thyroid cancer tissues was significantly lower than that in normal tumor-adjacent tissues (0.36±0.029 vs 0.98±0.034, P=0.004) . MiR-106b expression in tumor tissues was significantly associated with tumor size and tumor number. MiR-106b was obviously inhibited by miR-106b inhibitor in PTC-1 cells (0.96±0.025 vs 0.29±0.032, P=0.001) , and inhibition of miR-106b resulted in significantly increased proliferation (89.33±5.67 vs 136.67±10.33, P=0.03) and decreased apoptosis (16.33±3.20 vs 7.67±2.45, P=0.04) . On the contrast, over-expression of miR-106b using miR-106b mimics led to significantly decreased proliferation (98.00±4.65 vs 76.33±2.87, P=0.03) and increased apoptosis (22.54±2.13 vs 32.45±4.34, P=0.04) .

Decreased expression of miR-106b is correlated with the adverse clinicopathological features of thyroid cancer. MiR-106b can inhibit cell proliferation and apoptosis of thyroid cancer cells, suggesting miR-106b plays a suppressive role in development and progression of thyroid cancer.

MicroRNA-106b; Thyroid cancer; Apoptosis; Proliferation