Intrinsic resistance of pancreatic cancer cell lines towards 5-fluorouracil

AIM: To investigate whether the pancreatic cancer cells possess the intrinsic or acquired resistance to 5-fluorouracil(5-FU). METHODS: The cytotoxic effects of 5-FU on AsPC-1, Capan-1, Mia-PaCa-2, Panc-1 and T3M4 pancreatic cancer cells were assessed by the sulforhodamine B protein assay (SRB). RESULTS: The IC₅₀ of 5-FU in pancreatic cancer cell lines was exceedingly high. Panc-1 and Mia-PaCa-2 showed the highest resistance to 5-FU (IC ₅₀= 12 and 13μmol/L, respectively), and even in the most sensitive cell line, Capan-1, the IC₅₀ was still relatively high (473pmol/L). These IC₅₀ were even much higher (1-56 times) than plasma concentrations when 5-FU was given to patients at a standard dosage. CONCLUSION: Most of the pancreatic cancer cell lines are intrinsic resistant to 5-FU. These findings may represent one of the reasons why pancreatic cancer responds only poorly to 5-FU treatment in the clinical practice.