Abstract A29: Involvement of JAK-STAT signaling in human pancreatic adenocarcinoma cell lines and suitability for targeted therapy
Authors: Fest Jesse , Fuhler Gwenny M. , Koetsveld Peter M. van , Peppelenbosch Maikel P. , Eijck Casper HJ van 
Published: December 2016

Background: Pancreatic ductal adenocarcinoma is a highly lethal disease and for the past few decades no new advances in treatment have been made. A new potential target for therapy may be the STAT-JAK signaling pathway. This pathway plays a critical role in the regulation of cell survival, proliferation and migration. Recently, high levels of pSTAT3 expression have been associated with a poor outcome in pancreatic cancer. Therefore our main goal was to study the role of the JAK-STAT pathway in various human pancreatic cancer cell lines and its suitability for targeted therapy.

Methods: Protein levels of phosphorylated STAT1 and STAT3 were determined in eight human pancreatic adenocarcinoma cell lines. A JAK1/3-inhibitor (Tofacitinib) was used to inhibit pSTAT1 and pSTAT3 at clinically relevant doses. Its effect on proliferation and migration was evaluated by means of an MTT assay, total DNA levels and a scratch assay. Photomicrographs were taken and compared at starting time point and after eight hours. To study the effect of STAT3 levels on drug-resistance for Gemcitabine, MTT assays were performed in the presence of Tofacitinib.

Results: Levels of phosphorylated STAT1 and STAT3 varied widely amongst the eight cell lines. In five cell lines both STATs were activated. Inhibition with Tofacitinib (200ng/mL) was shown for both, ranging from 26.5% to 77.8% for pSTAT1 and 8.1% to 67.3% for pSTAT3 respectively. No significant effect on proliferation was observed after treatment with 100ng/mL, 200ng/mL and 400ng/mL Tofacitinib for 24, 48 and 72 hours by MTT assay or 200ng/mL Tofacitinib for 24 and 72 hours by DNA measurements. Migration was significantly reduced by Tofacitinib treatment (200ng/mL) in three cell lines: BxPC3 (44.0%, p = 0.0443 ), MIA PaCa2 (62.5%, p = 0.0224 ) and PANC1 (52.4 %, p = 0.0336) when treated with Tofacitinib (200ng/mL), but levels of inhibition did not correspond to STAT1/3 phosphorylation levels in these cell lines. No effect on drug-resistance for Gemcitabine was observed after combined treatment with Tofacitinib.

Conclusion: Contrary to recent publications, suggesting that the JAK-STAT pathway may be involved in the tumor biology of pancreatic cancer, we show no effect of divergent STAT activity levels on cellular behavior in pancreatic cell lines and susceptibility of cells to Tofacitinib. Thus, while STAT1 and STAT3 activity levels vary considerably between tumors, our data suggest that these STATs do not provide a target for precision medicine.

Citation Format: Jesse Fest, Gwenny M. Fuhler, Peter M. van Koetsveld, Maikel P. Peppelenbosch, Casper HJ van Eijck.{Authors}. Involvement of JAK-STAT signaling in human pancreatic adenocarcinoma cell lines and suitability for targeted therapy. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A29.