Thymosin β4 was upregulated in recurred colorectal cancers

Recurrent cancers usually metastasise to other organs and have a very poor prognosis. Recurrence and metastatic spread have been proposed to depend on cancer stem cells, which express CD133.1 The expression of the actin-binding protein, thymosin β4 (Tβ4), has been reported to be elevated in a side population of small cells known as cancer stem cells in the breast cancer cell lines MCF7 and MDA-MB231.2 A recent study has also shown that colorectal cancer cells (CR-CSCs) from different patients that were sorted by CD133 had higher Tβ4 levels than normal colorectal cancer cells. Additionally, a lentiviral strategy to downregulate Tβ4 expression in CR-CSCs lowered the capacity of the cells to grow and migrate in culture, and reduced the tumour size and aggressiveness of CR-CSCs in xenografted mice.3 We have previously reported that Tβ4 levels in metastatic stomach cancers to the ovary were significantly upregulated compared with levels in normal stomachs and primary stomach cancers. Furthermore, Tβ4 expression was colocalised with CD133 expression in primary ovarian carcinomas, metastatic ovarian cancers from stomach cancers, and primary stomach cancers, suggesting that Tβ4 expression is strongly related to CD133 expression and is a characteristic of stem cells or cancer stem cells.4 In the present study, we compared the expression patterns of Tβ4 and CD133 in primary and recurrent colorectal cancer cells from the same patient. We obtained the paraffin-embedded primary and recurrent colorectal cancers of 10 patients. Tβ4 and CD133 expression …