OBJECTIVETo investigate the expression of thymosin beta10 (Tbeta10) and related changes of actin filament organization in human tumor cell lines with different metastatic potential.

METHODSFour groups of nine human tumor cell lines with different metastatic potential were analyzed for the expression of Tbeta10 mRNA detected by northern-blot and its peptide by immunohistochemical staining. The filamentous actin (F-actin) was stained with TRITC-phalloidin to detect changes in actin organization.

RESULTSIn comparison with the non and/or weakly metastatic counterparts, Tbeta10 was upregulated in highly metastatic human lung cancer, malignant melanoma and breast cancer cell lines. TRITC-phalloidin staining revealed less actin bundles and a fuzzy network of shorter filaments in the highly metastatic tumor cells, while in the non and/or weakly metastatic cancer cell lines, there were thick and orderly arranged actin filaments.

CONCLUSIONSTbeta10 levels correlate positively with the metastatic phenotype in human tumors currently examined. The increased metastatic potential of tumor cells is accompanied by the loss of F-actin and poorly organized actin skeleton. There is a consistent correlation between the elevated Tbeta10 expression and the disrupted actin skeleton.