Abstract 2357: Knockdown of neuropilin-1 in monocytes impaired lymphocyte migration and anti-tumor activity in a humanized mouse model
Authors: Kawaguchi Kosuke , Suzuki Eiji , Kii Isao , Kataoka Tatsuki R. , Hirata Masahiro , Haga Hironori , Hagiwara Masatoshi , Toi Masakazu 
Published: August 2015

Abstract
Background
Antibody therapy such as trastuzumab is imperative for HER2-positive breast cancer patients. Although its antitumor action is not completely understood, the role of immune cells in antibody therapy is indispensable. Neuropilin-1 (NRP1) in monocytes induces high in vitro anti-tumor activity. Here, we showed the role of NRP1 in monocytes in HER2-positive breast cancer, using a tumor-bearing NOD/Shi-SCID, IL-2Rγnull(NOG) mouse model.
Experimental procedures
A tumor-bearing NOG mouse was made using BT474-sGL containing transfected HER2-positive human breast cancer cell lines that secreted Gaussia luciferase (Gluc). Tumor volumes were measured, using Gluc relative light units (RLUs), in 5 treatment arms (Table). Each arm was allocated 5 NOG mice, randomized by body weight and RLUs. Cytokines released into culture supernatants were determined using human Bio- Plex Cytokine Assay Kits (Bio-Rad, Hercules, CA), according to the manufacturer's instructions. mRNA was measured using TAQMAN array (LifeTechnologies, Carlsbad, CA) gene expression studies, according to the manufacturer's instructions.
Results
Knockdown of NRP-1 in monocytes impaired anti-tumor activity: After 2 cycles of treatment, RLUs increased significantly from baseline in Arm E, compared with those in Arm D. There was no significant difference between Arms B and E.
Knockdown of NRP-1 in monocytes impaired migration activity: Staining for human-specific CD45 revealed that the tumor infiltrating lymphocytes of Arm E decreased compared with those of Arm D; CD45 mRNA was significantly lower in Arm E than in Arm D.
Chemokine secretion is regulated by NRP-1: Tumor chemokine (e.g., IP-10, MIP-1α, MIP-1β and RANTES) secretion was significantly decreased due to knockdown of NRP-1.
Conclusion
Our data suggest that NRP-1-expressing immune cells initiate anti-tumor activity via migration and chemokine secretion.
Summary of resultsArmHumanizedTrastuzumabNRP1 KD% change RLU (mean ± SEM)CD45 mRNA relative quantities (mean ± SEM)IP-10 pg/mL (mean ± SEM)MIP-1α pg/mL (mean ± SEM)MIP-1β pg/mL (mean ± SEM)RANTES pg/mL (mean ± SEM)ANoNoNo495 ± 76.00.75 ± 0.3822.2 ± 6.351.16 ± 0.013.51 ± 3.515.36 ± 2.68BNoYesNo49.6 ± 43.20.50 ± 0.2617.1 ± 13.91.20 ± 0.275.75 ± 5.757.87 ± 4.40CYesNoNo566 ± 145504 ± 2421361 ± 4538.31 ± 3.1582.9 ± 43.659.4 ± 42.6DYesYesNo-45.7 ± 12.91650 ± 4055880 ± 26006.43 ± 1.3767.0 ± 13.9171 ± 35.4EYesYesYes46.2 ± 15.4307 ± 121285 ± 73.21.60 ± 0.3010.7 ± 2.3229.7 ± 9.69p value of D vs. Ep &lt; 0.01p = 0.04p = 0.03p &lt; 0.01p &lt; 0.01p &lt; 0.01
Citation Format: Kosuke Kawaguchi, Eiji Suzuki, Isao Kii, Tatsuki R. Kataoka, Masahiro Hirata, Hironori Haga, Masatoshi Hagiwara, Masakazu Toi. Knockdown of neuropilin-1 in monocytes impaired lymphocyte migration and anti-tumor activity in a humanized mouse model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2357. doi:10.1158/1538-7445.AM2015-2357