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 in pancreatic cancer cell lines induced by 5-fluorouracil (5-Fu), and in circulating tumor cells (CTCs) in peripheral blood of patients previously untreated with advanced pancreatic cancer. Furthermore, the goal was to test the relationship of dynamic of CTCs with the effects of the first cycle of chemotherapy. To accomplish this study, CD45 antibody coated beads were used to discard white blood cells in peripheral blood. This was done in combination with CA19-9-Alexa488 and CK8/18-Alexa594 immunofluorescence staining to identify CTCs in circulation from 41 advanced pancreatic cancer patients, before and after chemotherapy. The PL45 pancreatic cancer cell line was incubated with 20 µmol/L 5-Fu for 12 and 24 hours to induce apoptosis, and the expression patterns of CA19-9 and CK8/18 were measured, and the extent of apoptosis was evaluated. Subsequently, apoptotic cells and CTCs were measured. Of 41 patients with stage III and Ⅳ pancreatic cancer, 80.5% were detected with more than two CTCs in 7.5 mL peripheral blood before any therapy and the median number of CTCs was 16.8±16.0 (0-59). After 7 days by the first cycle of 5-Fu chemotherapy, only 29.3% (12/41) of these patients were detected more than two CTCs in 7.5 mL peripheral blood and the median number of CTCs was 3.8±7.8 (0-40) (P=0.000). And no CTCs were detected in 20 healthy donors from 7.5 mL peripheral blood (P=0.000). Apoptotic CTCs were detected after advanced pancreatic patients were administered the first cycle of chemotherapy. Punctate, granular, and bubble-like morphologies with CA19-9 and CK8/18 staining were found and may reflect apoptosis in pancreatic cancer cells and CTCs. Apoptotic CTCs may indicate the efficacy of chemotherapy in pancreatic cancer patients. However, further studies are required to follow up these findings.