Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 14, 2017; 23(42): 7551-7562
Published online Nov 14, 2017. doi: 10.3748/wjg.v23.i42.7551
Combined treatment of pancreatic cancer xenograft with 90Y-ITGA6B4-mediated radioimmunotherapy and PI3K/mTOR inhibitor
Winn Aung, Atsushi B Tsuji, Hitomi Sudo, Aya Sugyo, Yoshinori Ukai, Katsushi Kouda, Yoshikazu Kurosawa, Takako Furukawa, Tsuneo Saga, Tatsuya Higashi
Winn Aung, Atsushi B Tsuji, Hitomi Sudo, Aya Sugyo, Tatsuya Higashi, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology (QST-NIRS), Chiba 263-8555, Japan
Yoshinori Ukai, Katsushi Kouda, Perseus Proteomics Inc., Tokyo 153-0041, Japan
Yoshikazu Kurosawa, Innovation Center for Advanced Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
Takako Furukawa, Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya 461-8673, Japan
Tsuneo Saga, Department of Diagnostic Radiology, Kyoto University Hospital, Kyoto 606-8507, Japan
Author contributions: Aung W designed the research, performed the majority of experiments, analyzed the data and wrote the manuscript; Ukai K, Kouda K and Kurozawa Y provided the anti-integrin α6β4 antibody; Sudo H perfomed the antibody radiolabeling; Sugyo A participated in the animal experiments; Tsuji AB, Higashi T, Furukawa T and Tsuneo S coordinated the research and helped for the manuscript preparation; all authors revised and endorsed the final draft.
Supported by (partially) a Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Culture, Sports, Science and Technology, Japan, No. 17K10460 to Aung W.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of National Institute of Radiological Sciences.
Conflict-of-interest statement: The authors declare no potential conflicts of interest relevant to this article.
Data sharing statement: All relevant data were presented in the manuscript. Further information is available from the corresponding author at
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Winn Aung, MBBS, PhD, Senior Researcher, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Telephone: +81-43-3823706 Fax: +81-43-2060818
Received: June 23, 2017
Peer-review started: June 26, 2017
First decision: July 13, 2017
Revised: July 31, 2017
Accepted: September 9, 2017
Article in press: September 9, 2017
Published online: November 14, 2017

To investigate the therapeutic effect of combined integrin α6β4-targeted radioimmunotherapy (RIT) and PI3K/mTOR inhibitor BEZ235 in a pancreatic cancer model.


Phosphorylation of Akt, mTOR, the downstream effectors eukaryotic initiation factor 4E binding protein 1 (4EBP1) and S6 ribosomal protein (S6) were evaluated in BxPC-3 human pancreatic cancer cells treated with Yttrium-90 (90Y) labeled anti-integrin α6β4 antibody (ITGA6B4) and BEZ235 by western blotting. The cytotoxic effect of BEZ235 was investigated using a colony formation assay. Therapeutic efficacy enhancement by oral BEZ235 administration was assessed using mice bearing BxPC-3 xenograft tumors. Tumor volume measurements and immunohistochemical analyses (cell proliferation marker Ki-67, DNA damage marker p-H2AX and p-4EBP1 staining) of tumors were performed for evaluation of combined treatment with 90Y-ITGA6B4 plus BEZ235, or each arm alone.


We found that phosphorylation of Akt (p-Akt), 4EBP1 (p-4EBP1) and S6 (p-S6) was inhibited by BEZ235. Colony formation in BxPC-3 cells was additively suppressed by the combination of 90Y-ITGA6B4 and BEZ235. Pretreatment with BEZ235 before 90Y-ITGA6B4 exposure resulted in significant reduction of cells plating efficiency (PE) (0.54 ± 0.11 vs 2.81 ± 0.14 with 185 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01; 0.39 ± 0.08 vs 1.88 ± 0.09 with 370 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01) when 5 × 103 cells per dish were plated. In vivo, the combined treatment with 90Y-ITGA6B4 plus BEZ235 enhanced the inhibition of tumor growth and statistically significant differences of relative tumor volume were observed for 27 d after the treatment start date when compared with the 90Y-ITGA6B4 single injection treatment (1.03 ± 0.38 vs 1.5 ± 0.15 at Day 27, P < 0.05), and for 41 d when compared with the BEZ235 treatment alone (1.8 ± 0.7 vs 3.14 ± 1.19 at Day 41, P < 0.05). Tumors from treatment groups showed reduction in volumes, decreased Ki-67-positive cells, increased p-H2AX-positive cells and decreased p-4EBP1 expression.


The therapeutic efficacy of 90Y-ITGA6B4-RIT can be improved by combining with dual PI3K and mTOR inhibitor, BEZ235, in a pancreatic cancer model suggesting potential clinical application.

Keywords: Radioimmunotherapy, Pancreatic cancer, Anti-integrin α6β4 antibody, Yttrium-90, NVP-BEZ235

Core tip: We examined whether the therapeutic effect of 90Y-labeled anti-α6β4 integrin antibody (ITGA6B4)-mediated radioimmunotherapy (RIT) is improved by dual PI3K/mTOR inhibitor BEZ235 in the treatment of pancreatic cancer xenograft. There is no report about the combined therapeutic effects of RIT and BEZ235 in cancer treatment, though BEZ235 has been tested for its anticancer and potential radiosensitizing effect. Our studies (in vitro/in vivo) and results suggest for the first time that it is possible to improve the therapeutic efficacy by combining 90Y-ITGA6B4-RIT and BEZ235 and this combination can be a potential encouraging treatment modality in the future.