Abstract. Pancreatic cancer is a solid malignancy with a high mortality rate, on account of the high incidence of metastasis at the time of detection. The aggressiveness of pancreatic cancer may be partly driven by cancer stem cells (CSCs), which are characterized by the ability to self-renew and recapitulate tumors in the ectopic setting. However, although a number of drugs targeting CSCs are currently under clinical investigation, few effective drugs have been developed. The present study demonstrated that thalidomide inhibited cell proliferation and metastasis in pancreatic cancer cell lines through the inhibition of epithelial mesenchymal transition. The effect of thalidomide was more pronounced in cluster of differentiation 133 (CD133) + SW1990 cells than in Capan-2 cells, in which CD133 expression was almost undetectable. The results revealed that CD133 is likely to serve a role in the antitumor effect of thalidomide and indicated that thalidomide could be developed as a CSC-specific adjuvant chemotherapy in pancreatic cancer.
IntroductionPancreatic cancer is a disease with a high mortality rate that is characterized by the early metastasis to local and distant organs; the majority of patients present with unresectable disease at the time of initial diagnosis (1). Therefore, patients with pancreatic cancer have a poor prognosis, with an overall 5-year survival rate of <5% in the United States between 1975 and 2008 (2). No significant advances in the treatment of pancreatic cancer have been made in >10 years, largely due to of the resistance of the disease to conventional chemotherapy and radiation therapy (3-6). The involvement of cancer stem cells (CSC; also termed tumor-initiating cells) in the development of chemotherapy resistance has been reported in a number of types of malignancy (7-9). CSCs are a phenotypically distinct population of cells that are functionally defined by their ability to form tumors, self-renew and differentiate, as well as their resistance to chemotherapy (10,11). Therefore, the development of novel chemotherapeutic agents that are effective against CSCs is urgently required.Thalidomide is a non-barbiturate sedative and hypnotic drug with anti-angiogenic and immunomodulatory properties (12). Thalidomide is currently used in the treatment of various types of malignant tumor, including prostate cancer (13), glioblastoma (14), glioma (15), renal cell carcinoma (16) and advanced breast cancer (17). The mechanism of action of thalidomide includes the inhibition of vascular endothelial growth factor, basic fibroblast growth factor and tumor necrosis factor-α, the inhibition of angiogenesis, and the stimulation of natural killer cells (12). However, to the best of our knowledge, the use of thalidomide in the treatment of pancreatic cancer has not been assessed and the potential mechanism of thalidomide-mediated inhibition of tumor cell viability remains to be elucidated. In the present study, the effect of thalidomide on pancreatic cancer cells was examined, alongside its mechanism of ...