Detection of apoptotic circulating tumor cells in advanced pancreatic cancer following 5-fluorouracil chemotherapy

The objective of the present study was to evaluate CA19-9 and CK8/18 expression patterns induced by 5-fluorouracil (5-FU) in pancreatic cancer cell lines and in circulating tumor cells (CTCs) in the peripheral blood of patients previously untreated for advanced pancreatic cancer. Furthermore, the goal was to analyze the effects of first cycle chemotherapy on CTCs. This was done in combination with CA19-9-Alexa Fluor 488 and CK8/18-Alexa Fluor 594 immunofluorescence staining to identify CTCs in circulation from 41 advanced pancreatic cancer patients, before and after chemotherapy. The PL45 and PANC-1 pancreatic cancer cell lines were incubated with 20 mu mol/L 5-FU for 12 and 24 h to induce apoptosis, and the expression patterns of CA19-9 and CK8/18 were measured. 80.5% (33/41) of the patients had more than two CTCs in 7.5 mL peripheral blood before any therapy, and the mean number of CTCs was 16.8 +/- 16.0 (0-59). After seven days of the first cycle of 5-FU chemotherapy, only 29.3% (12/41) of these patients were found to have more than 2 CTCs in 7.5 mL peripheral blood, and the mean number of CTCs was 3.8 +/- 6.8 (0-40) (p < 0.01). No CTCs were detected in 20 healthy donors (p < 0.01). Punctate, granular and bubble-like morphologies with CA19-9 and CK8/18 staining were found, which may reflect apoptosis in pancreatic cancer cells and CTCs. The presence of apoptotic CTCs may indicate the efficacy of chemotherapy in pancreatic cancer patients. However, further studies are required to follow up these findings.