Expression Patterns of Thymosin beta 4 and Cancer Stem Cell Marker CD133 in Ovarian Cancers

Thymosin beta 4 (T beta 4), a small acidic actin binding peptide, is overexpressed in a side population of cancer stem cells and CD133-positive colorectal cancer stem cells. In order to understand the relationship between T beta 4 and CD133, we studied the expression patterns of T beta 4 and CD133 in ovarian cancers. The expression patterns of T beta 4 and CD133 were studied in normal ovaries, primary ovarian cancers, metastatic ovarian cancers, primary stomach cancers, and normal stomachs by Western blot and immunohistochemistry. Expression patterns and co-localization of T beta 4 and CD133 were examined by immunofluorescence and confocal laser-scanning microscopy. T beta 4 is overexpressed in primary ovarian cancers, but not in primary stomach cancers, when compared with normal controls. However, T beta 4 levels in metastatic stomach cancers to the ovary are significantly upregulated compared with levels in normal stomachs and primary stomach cancers. These results suggest that T beta 4 levels are related to tumorigenesis in ovarian cancers and metastasis in stomach cancers. The expression of T beta 4 in normal ovaries and normal stomachs was weak, but was co-localized with CD133 expression. T beta 4 expression was also co-localized with CD133 expression in primary ovarian carcinomas, metastatic ovarian cancers from stomach cancers and primary stomach cancers. These data suggest that T beta 4 expression is strongly related to CD133 expression and is a characteristic of stem cells or cancer stem cells.