5-Fluorouracil may enrich cancer stem cells in canine mammary tumor cells in vitro

Mammary gland carcinomas are the most common neoplasms in women and unsterilized female dogs. Owing to the existence of cancer stem cells (CSCs), chemotherapy is not able to cure these types of diseases completely. A number of studies have demonstrated that CSCs are resistant to chemotherapeutic drugs, but whether canine mammary tumor cells that have acquired resistance to 5-fluorouracil (5-FU) exhibited properties of CSCs remains unknown. The aim of the present study was to investigate whether 5-fluorouracil-resistant canine mammary tumor cells exhibited properties of CSCs. CSCs were analyzed using western blot assays, ultra-low attachment sphere cultures, flow cytometry and migration (wound healing and Transwell) assays. The results indicated that, compared with parental cells, proteins associated with the Wnt/β-catenin signaling pathway and aldehyde dehydrogenase 1 were overexpressed, the number and size of spheres in the 5-FU-resistant cells were increased, the ratio of CD44⁺/CD24^-/low cells was increased and the migratory ability was improved in vitro compared with the 5-FU-susceptible cells. In conclusion, stimulation with chemotherapeutic drugs including 5-FU is a good method for increasing the proportion of canine mammary tumor stem cells in vitro, which may provide further understanding of chemotherapeutic methods and CSCs.

Epigallocatechin-3-gallate promotes apoptosis and reversal of multidrug resistance in esophageal cancer cells

Evidence for demonstrating the role of the green tea component epigallocatechin-3-gallate (EGCG) in esophageal squamous cell carcinoma cells is limited. In this study, we investigated apoptosis induced by EGCG and the underlying molecular mechanisms in human esophageal squamous cell carcinoma cells. The growth-inhibitory effects of EGCG on esophageal cancer cell (Eca109 and Ec9706) were detected by MTT. Using flow cytometry, we determined the cellular apoptosis, bcl-2, bax and caspase-3 protein expression in Eca109 and Ec9706 cells following treatment with EGCG for 24h. After treatment of Eca109/ABCG2 (an esophageal cancer multidrug resistance cell line) cells with adriamycin (ADM) combined with EGCG for 24h, the cellular apoptosis, mitochondrial membrane potential, ADM concentration in cells and ABCG2 protein expression were detected by flow cytometry. EGCG inhibited the growth of Eca109 and Ec9706 cells in a dose- and time- dependent manner. EGCG induced apoptosis, decreased the bcl-2 protein expression and increased the expression of bax and caspase-3 protein. The rate of apoptosis and ADM concentration in the Eca109/ABCG2 cells following treatment with ADM and EGCG were higher than that with ADM treatment alone, although the mitochondrial membrane potential was significantly lower (P<0.01). EGCG reduced the ABCG2 expression of Eca109/ABCG2 cells. Our data indicated that EGCG inhibited cell growth and induced esophageal cancer cell apoptosis. It reduced the bcl-2 protein expression and increased the bax and caspase-3 protein expression. EGCG reversed multi-drug resistance by reducing ABCG2 expression and increasing the anticancer drug concentration in cancer cells.