Tumor immunomodulation mechanism after carbon ion beam irradiation on pancreatic cancer cells

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K19806
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Radiation science
• Research Institution: Gunma University
• Principal Investigator: Okamoto Masahiko 群馬大学, 医学部附属病院, 講師 (10451725)
• Research Collaborator: Murata Hiroto
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 放射線治療 / 重粒子線治療

Outline of Final Research Achievements

The expression of PD-L1 after irradiation (X-ray /carbon ion beam) was verified using pancreatic cancer cells, gastric cancer cells, head and neck squamous cell carcinoma cells, malignant melanoma cells, and lung cancer cells. No increase in PD-L1 expression was observed even after the conditions such as the time course were changed. But the irradiation dose-dependent increase of PD-L1 was confirmed at the human osteosarcoma cell line U2OS by Western blot and flow cytometry. In certain carcinomas, it is speculated that radiation enhances the expression of PD-L1, which contributes to the acquisition of resistance to radiation therapy.

Free Research Field

放射線治療

Academic Significance and Societal Importance of the Research Achievements

今回の研究の当初の目的であった膵癌細胞では放射線によるPD-L1の発現増加は確認されなかったが、特定の癌腫（骨肉腫細胞）においては放射線照射によりPD-L1の発現が亢進されることが確認された。PD-L1の発現亢進は腫瘍免疫の抑制に繋がり、治療抵抗性の一因となり得る。即ち放射線治療と免疫チェックポイント治療の併用により、放射線治療抵抗性である骨肉腫等に対して、より強い治療効果が得られる可能性が示唆された。