Elevated thymosin β15 expression is associated with progression and metastasis of non-small cell lung cancer

Thymosin beta 15 (T beta 15) is a small protein that comprises 44 amino acid residues. T beta 15 is upregulated in malignant human prostate and breast tumors. The expression of T beta 15 correlates with the metastatic potential of mouse lung cancer and human breast carcinoma cells. However, the correlation of T beta 15 expression with human lung cancer remains unclear. Using immunohistochemistry and in situ hybridization, we analyzed the expression of T beta 15 in tumors and tumor-adjacent tissues obtained from 76 patients with non-small cell lung cancer (NSCLC). The relationship between T beta 15 expression and clinicopathological factors was investigated. Our findings showed that in NSCLC, T beta 15 protein and mRNA were mainly expressed in the cytoplasm, and their expression correlated with stage (p=0.018 for both), differentiation (p=0.013 and 0.006, respectively), and lymph node metastasis (p=0.001 and 0.009, respectively). T beta 15 expression was examined in PG-BE1 and PG-LH7 lung cancer cells. We found that both T beta 15 protein and mRNA were highly expressed in BE1 cells as compared to LH7 cells. After transfecting the PG-LH7 cells with the pEGFP-T beta 15 plasmid in order to increase T beta 15 expression, the migration ability of the cells was enhanced. These findings suggest that increased T beta 15 expression correlates with the progression and metastasis of NSCLC.