ABSTRACT
Objective: To study the role of pancreatic cancer stem cells in radiotherapy resistance of pancreatic cancer. Methods: CD133+ pancreatic cancer stem cells were obtained by using magnetic cell sorting. MTT and flow cytometry were used to observe the proliferation activity and apoptosis of different cell subsets of pancreatic cancer after radiation treatment. Then flow cytometry, Western blot and qRT-PCR were used to observe the expression changes of CD133 in pancreatic cancer cells after radiation treatment. Finally, the cell cycle distribution of different subgroup cells was observed by flow cytometry. Results: Compared with unselected cells and CD133- cells, CD133+ stem cells had the highest survival rate and the lowest apoptosis rate after radiation treatment. The proportion of CD133+ stem cells increased and the expressions of CD133 protein and RNA increased in pancreatic cancer cells. CD133+ stem cells had the highest ratio of G0/G1 phase compared with unsorted cells and CD133- cells, and the difference was statistically significant. Conclusion: CD133+ pancreatic cancer stem cells are one of the important causes of radiotherapy resistance in pancreatic cancer cells, and the increased proportion of G0/G1 phase may be one of the mechanisms.
ABSTRACT
Objective:To evaluate the effect and possible mechanism of B-cell-specific moloney murine leukemia virus insertion site 1(BMI-1) on the radiosensitivity of pancreatic cancer SW1990 cell line.Methods:According to our previous study results, 4 Gy X-ray and down-regulation of BMI-1 expression were adopted as intervention conditions. The effect on the proliferation of SW1990 cells was assessed by clony formation assay. The effect on cell apoptosis and cell cycle was evaluated by flow cytometry. The effect upon the epithelial-mesenchymal transition (EMT) was determined by Western blot.Results:Clony formation assay and flow cytometry found that the lowest cell proliferation ability and the highest apoptotic rate were obtained after BMI-1 down-regulation and 4 Gy X-ray compared with other groups (all P<0.05). Flow cytometry revealed that the proportion of G 0/G 1 phase was significantly decreased, whereas the G 2/M phase was remarkably increased in pancreatic cancer stem cells treated with 4 Gy X-ray compared with the control group (both P<0.05). Nevertheless, opposite results were obtained after down-regulation of BMI-1 expression. Western blot showed that the expression of E-cadherin was up-regulated, whereas that of Vimentin was down-regulated following 4 Gy X-ray (both P<0.05). Conclusion:Downregulation of BMI-1 expression can enhance the radiosensitivity of pancreatic cancer SW1990 cells, and its mechanism may be related to cell cycle and EMT.