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

Thymosin β15 (Tβ15) is a small protein that comprises 44 amino acid residues. Tβ15 is upregulated in malignant human prostate and breast tumors. The expression of Tβ15 correlates with the metastatic potential of mouse lung cancer and human breast carcinoma cells. However, the correlation of Tβ15 expression with human lung cancer remains unclear. Using immunohistochemistry and in situ hybridization, we analyzed the expression of Tβ15 in tumors and tumor-adjacent tissues obtained from 76 patients with non-small cell lung cancer (NSCLC). The relationship between Tβ15 expression and clinicopathological factors was investigated. Our findings showed that in NSCLC, Tβ15 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). Tβ15 expression was examined in PG-BE1 and PG-LH7 lung cancer cells. We found that both Tβ15 protein and mRNA were highly expressed in BE1 cells as compared to LH7 cells. After transfecting the PG-LH7 cells with the pEGFP-Tpβ15 plasmid in order to increase Tβ15 expression, the migration ability of the cells was enhanced. These findings suggest that increased Tβ15 expression correlates with the progression and metastasis of NSCLC.