ELECTROPORATION OF PANCREATIC ADENOCARCINOMA CELL LINES ENHANCES THE ANTI-TUMOR EFFECT OF BLEOMYCIN

Background Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive tumor for which no effective therapeutic treatments are available so far. Recent evidence suggests that electroporation (EPN) can be used in vivo to increase the uptake of chemotherapeutic agents by tumour cells, thus leading to enhanced response rate. Methods Cell lines: We defined the optimal parameters for electrical pulses and concentration of drugs (bleomycin and cisplatin) by in vitro analysis of two PDAC cell lines PANC1 and MiaPaCa-2. Cell lines received eight pulses of 100 µs at 1kV/cm electric field strength. The cytotoxicity of bleomycin and cisplatin on pulsed cells was determined using the optimal permeabilization conditions, and the half maximal inhibitory concentration (IC50) values were calculated by MTS assay. Animal Model: We used 10, five-month old, male New Zealand White rabbits, animals underwent pancreas and duodenum (gut) electroporation in open surgery (8 pulses at 1000 V/cm of 100 µs of duration were delivered at 5 KHz using linear needle configuration electrodes.) The animals were sacrificed 24 hours, 72 hours, 15 days, 30 days after surgery. The pancreas was removed and treated for the morphological and histological analysis. Results Cell lines: The optimal electric conditions was defined as 1 kV/cm, eight pulsed of 100µs duration. Using these optimized parameters for EPN, cell lines showed enhanced sensitivity to both bleomycin and cisplatin. After EPN, the IC50 of bleomycin was reduced 45 and 13 times for PANC1 and MiaPaCa2, respectively. The IC50 value for cisplatin was reduced by factors ranging from 2.3-1.4 in the cell lines after EPN. Animal Model: At short term (24 h post electroporation treatment), morpho-histological analysis of non- pathological rabbit pancreas showed necrosis in the treated areas and acute inflammatory cells infiltration was also present; After 30 days serum levels of pancreas enzymes were not significantly modified after the electroporation procedure and the treated areas showed mild inflammation as a result of transient and reversible modification. Conclusions We have optimized a protocol for EPN in vitro showing that bleomycin rather than cisplatin may be effective in vivo as part of EPN treatment. The delivery of electric pulse through needles inserted into the pancreas of rabbits elicits a local reversible inflammatory response but the blood values of pancreatic enzymes are not significantly increased over 30 days of observation. Our data suggest that EPN with the use of chemotherapic agents can be safely applied to non resectable pancreas cancer for local tumour control.