Abstract 4009: The expression of PD-L1 on human and murine pancreatic ductal adenocarcinoma is enhanced by anticancer agents via the JAK/STAT pathway
Authors: Doi Toshifumi , Ishikawa Takeshi , Yasuda Tomoyo , Okayama Tetsuya , Oka Kaname , Sakamoto Naoyuki , Naito Yuji , Itoh Yoshito 
Published: July 2016

Abstract
Background:
Pancreatic ductal adenocarcinoma(PDA) is the fourth most common cause of cancer-related death in Japan. Recently, new standard chemotherapies for PDA have been developed, but they are still largely unsatisfactory. Therefore, development of new treatment options has been required to improve the outcomes of patients with PDA. To break through this situation, blocking one of inhibitory immune checkpoints, Programmed death-1 (PD-1) /Programmed death-ligand 1 (PD-L1) pathway is considered to be a hopeful candidate for new treatment strategies for PDA.
In this context, for the future combination therapy of anticancer agents and immune check point inhibitors, we investigated how anticancer agents influence the expression of PD-L1 on pancreatic cancer cell lines. Additionally we analyzed the molecular mechanism by which PD-L1 expression on the pancreatic cancer cell lines are regulated.
Methods:
Human PDA cell lines MIA PaCA-2, AsPC-1 and murine PDA cell line Pan02 were used in this study. These cells were adjusted to 1.0 × 105 / ml and incubated with anticancer agents (i.e. gemcitabine, paclitaxel and 5-fluorouracil) at 37°C for 24-72h. Then, the expression level of PD-L1 was determined using qRT-PCR and flow cytometry.
For the blocking experiment of the JAK/STAT pathway, AG490 was used as a blocking agent. After 48h incubation of AsPC-1 cells at 37°C, cells were treated with various concentration of AG490 for 1h. Cells were stimulated with 5-fluorouracil, paclitaxel and gemcitabine, and then incubated in the presence or absence of AG490 for an additional 6-48h. The expression of PD-L1 was analyzed using qRT-PCR and flow cytometry. Stat1 and phospho-Stat1 protein were analyzed by western blotting.
Results:
In AsPC-1, MIA PaCA-2 and Pan02, the expression of PD-L1 was enhanced with all three anticancer agents in a concentration dependent manner.
The phosphorylation of STAT1 and the increase of total STAT1 was observed in AsPC-1 when stimulated by each anticancer agents. After the treatment of JAK/STAT inhibitor, the phosphorylation of STAT1 was attenuated, and the PD-L1 upregulation induced by anticancer agents was cancelled in a concentration dependent manner.
Conclusion:
The stimulation of anticancer agents leads to an enhancement of PD-L1 expression on PDA cell lines. The JAK/STAT pathway is reported to be involved in IFN-γ mediated PD-L1 upregulation in lung cancer and hepatocellular carcinoma cell lines. In the present study, the phosphorylation of Stat1 and the expression of total Stat1 were enhanced after the anticancer agents treatment. Moreover, JAK/STAT inhibitor attenuated anticancer agents-induced PD-L1 expression. Taken together, the JAK/STAT pathway may be responsible for the anticancer agents mediated PD-L1 transcription.
Citation Format: Toshifumi Doi, Takeshi Ishikawa, Tomoyo Yasuda, Tetsuya Okayama, Kaname Oka, Naoyuki Sakamoto, Yuji Naito, Yoshito Itoh. The expression of PD-L1 on human and murine pancreatic ductal adenocarcinoma is enhanced by anticancer agents via the JAK/STAT pathway. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4009.