7. Neutron Capture Therapy

概要

TITLE:

7. Neutron Capture Therapy

AUTHOR(S):

CITATION:

7. Neutron Capture Therapy. KURNS Progress Report 2021, 2020: 173198

ISSUE DATE:
2021-08

URL:
http://hdl.handle.net/2433/264997
RIGHT:

CO7-1

Establichment of a novel mutation breeding using Boron Neutron Capture Reaction
(BNCR)

M.Kirihata, S. Segami11, Y. Hattori, T. Kinouchi,
M.Kirihata,
Y.
Kinashi2 S. Segami , Y. Hattori, T. Kinouchi,
Y. Kinashi2

ed seeds were sown in cell trays on May 31, 2020, germinated in a germination machine, grown outdoors, and
the germination rate was examined 20 days after sowing.

Research Center of BNCT, Osaka Prefecture University
Research Center of BNCT, Osaka Prefecture University
Institute of Environment, Agriculture and
Research Institute
of Environment, Agriculture and
Fisheries,
Fisheries, Osaka
Osaka Prefecture
Prefecture
22
KURNS
Research Reactor Institute, Kyoto University

1
1Research

INTRODUCTION: Boron Neutron Capture Reaction
(BNCR) is based on the nuclear reaction of 10B atom with
thermal/epithermal neutron already applied to cancer
treatment (BNCT) [1, 2]. As a new utilization method of
BNCR, the purpose of this study is to establish a novel
mutation breeding using BNCR.
This method uses the principle of inducing mutation by
an alpha particle and 7Li recoil nuclei high linear energy
transfer and short range when irradiated with neutrons
(low energy thermal neutrons (< 0.5 eV) can be absorbed
the 10B atoms, leading to generating high linier energy
transfer alpha particles (~ 150 keV/μm) and 7Li nuclei (~
175 keV/μm)) that are produced by BNCR of 10B selectively taken into the meristematic cell with thermal neutron. This principle is different from both chemical mutagens, such as EMS and MNU, and physical mutagens,
such as gamma rays and ion beams, used for mutation
breeding so far. In other words, the mutagenic effect depends on chemical and physical factors, such as 10B concentration, thermal neutron intensity, and irradiation time.
The germination rate is used as one of the traits to verify
the effect of mutagenesis[3]. In previous report, the seeds
were immersed into different concentrations (0, 10, 100,
200 ppm) of 10B-enriched p-boronophenylalanine (BPA)
for 16 h, re-dried seeds were irradiated with thermal
neutron for 90 minutes. The germination rate of these
irradiated seeds was investigated, and no BPA concentration-dependent effect on germination rate was observed.
In other words, in order to study the optimal treatment
conditions for mutagenesis, need to try a stronger process.
This time, new treatment conditions were investigated by
increasing the 10B concentration of the treatment solution
by using BPA as a fructose complex and by extending the
immersion time.
[4]

EXPERIMENTS: The experimental material used Oryza sativa L. cv. Nipponbare. The dry seeds were immersed into different concentrations (0, 10, 100 mM) of

RESULTS: The germination rate not decreased with
BPA-Fc concentrations. But the germination rate decreased with immersion time (Table 1). Although there
was a significant decrease in germination rate in the
strongest treatment, the 100 mM BPA-Fc for 48h condition, the germination rate was similar to the control 48 h
condition. Therefore, the decrease in germination rate in
48h immersing was not due to BNCR, but simply due to
the effect of longer immersion time. In this experiment,
we used BPA-Fc to increase the 10B concentration, but
again, we could not confirm any decrease in germination
rate due to the BNCR under the examined conditions. It
is unclear at this time whether the accumulation of 10B in
the meristematic cell of the seeds is not going well or
whether this method is less likely to cause a decrease in
germination rate. However, considering the solubility of
BPA, the concentration of 10B in BPA is considered to be
at the upper limit of the current conditions, and there may
be differences in the uptake by plant seeds depending on
the compound. Therefore, we are planning to study the
treatment with boron compounds other than BPA.
Table 1. The relationship each treatment conditions and germination rate.
Concentrations of BPA-Fc (mM)

Immersion time
(hour)

0
10 (100 ppm)
100 (1000 ppm)
0
10 (100 ppm)
100 (1000 ppm)

24

48

No. of No of seeds germination
seeds germinated rate (%)
40
80
80
40
80
80

28
72
66
23
55
45

70.0
90.0
82.5
57.5
68.8
56.3

10

* Numbers in ( ) indicate B concentrations.

REFERENCES:
[1] H. A. Soloway et al., Chem. Rev., 98 (1998),
1515-1562.
[2] B. Farhood, et al., Rep. Pract. Oncol. Radiother. 23
(2018), 462-473.
[3] Tanaka A. et al., Int. J. Radiat. Biol., 72, (1997),
121-127.
[4] H. R. Snyder, et al., J. Am. Chem. Soc. 80 (1958),
835-838.

B-enriched p-boronophenylalanine-fructose complex
(BPA-Fc) for 24 h or 48 h. The samples were washed
with water and re-dried. The seeds in 2-mL tubes were
irradiated with thermal neutron for 90 minutes in the
Kyoto University Research Reactor (KUR). The irradiat10

R2015
- 173 -

Development of antibody-tagged boron compounds using Fc-binding peptide
for on-demand receptor target in boron neutron capture therapy
Z33-BSH-antibody complex

I. Nakase1,2, A. Aoki1,2, Y. Sakai3, S. Hirase1,2, M. Ishimura3, T. Takatani-Nakase4,5, Y. Hattori3, and M. Kirihata3

O
S

Receptor
recognition
and binding

1

INTRODUCTION: Boron Neutron Capture Therapy
(BNCT) is a radiation therapeutic method for cancer
therapy. Cancer cellular uptake of boron-10 (10B) atoms
induces the cell death by the generation of alpha particles
and recoiling lithium-7 (7Li) nuclei when irradiated with
low-energy thermal neutrons. Current BNCT technology
shows effective therapeutic benefits in refractory cancers
such as brain tumor and head and neck cancer. However,
improvement of insufficient cancer targeting and cellular
uptake efficacy of boron compounds, and expansion of
disease coverage in BNCT are strongly desired. In this
research, we aimed to develop antibody-based drug delivery technology for BNCT using Z33 peptide [1],
which shows specific interaction recognition with the Fc
of human IgG antibody, for on-demand receptor target. In
addition, we found that macropinocytosis induction during the antibody-based drug delivery is important for the
biological activity in BNCT in vitro assay.
EXPERIMENTS: Z33 peptides were synthesized via
Fmoc solid-phase synthesis methods. For preparation of
dodecaborate-Z33 peptide conjugate, Z33 peptides was
subjected to react with bismaleimide ethane and then to
react with mercaptoundecahydrododecaborate (BSH).
RESULTS: We designed Z33 peptide-conjugated boron
compounds (Z33-BSH), and we examined the cell membrane accumulation and cellular uptake of Z33-BSH with
or without complex of cetuximab antibody, which specifically target epidermal growth factor receptor (EGFR).
As a result, in A431 cells (highly expressing EGFR),
complex of cetuximab antibody (100 nM) with Z33-BSH
(200 nM) highly enhanced their accumulation on the

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CONH

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EGF

!

!

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Graduate School of Science, Osaka Prefecture University, Japan
2
NanoSquare Research Institute, Osaka Prefecture University, Japan
3
Research Center of BNCT, Osaka Prefecture University,
Japan
4
School of Pharmacy and Pharmaceutical Sciences,
Mukogawa Women’s University, Japan
5
Institute for Bioscience, Mukogawa Women’s University,
Japan

-GGC-amide

Z33

!

CO7-2

EGFR
activation

Thermal neutron
irradiation

Cancer cellkilling activity

Figure 1. Schematic representation of the receptor targeted delivery of boron compounds. Z33-BSH-antibody
recognizes the targeted receptors on cancer cells. EGFR
activation induces macropinocytotic cellular uptake of
the BSH, leading to increased efficacy of the cancer
cell-killing activity after thermal neutron irradiation.
cancer cell plasma membranes. However, only their attachment on plasma membranes with very low cellular
uptake were observed. Macropinocytosis (accompanied
by actin reorganization, ruffling of plasma membrane,
and engulfment of large volumes of extracellular fluid)
[2] is considered to be important cellular uptake pathway,
and activation of EGFR leads to macropinocytosis induction. Therefore, we next checked effects of treatment of
EGF on their cellular uptake. As our results, co-treatment
of EGF with cetuximab antibody/Z33-BSH complex significantly increased their cellular uptake, and in the
thermal neutron irradiation experiment under the same
conditions, the cell killing effect of cetuximab antibody/Z33-BSH complex was enhanced through
macropinocytosis induction by EGFR activation [3].
CONCLUSION: In this research, we developed antibody-based receptor target system and found importance
of macropinocytosis induction in BNCT. These results
provide fundamental knowledge for the further development of receptor target system in BNCT.
REFERENCES:
[1] A.C. Braisted, J.A. Wells, Proc. Natl. Acad. Sci. USA,
93 (1996) 5688-5692.
[2] J.A. Swanson, Nat. Rev. Mol. Cell Biol., 9 (2008)
639-649.
[3] I. Nakase, et al. ACS Omega, 5 (2020) 22731-22738.

R2016
- 174 -

CO7-3

Development of cyclic RGD-functionalized closo-dodecaborate albumin conjugates
for boron neutron capture therapy

Hiroyuki Nakamura1,2, Kai Nishimura2, Kazuki Kawai2,
Satoshi Okada1,2, Takushi Tanaka3, Minoru Suzuki3⇑
1Laboratory

for Chemistry and Life Science, Institute of
Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
2School of Life Science and Technology, Tokyo Institute of
Technology, Yokohama, Japan
3Institute for Integrated Radiation and Nuclear Science,
Kyoto University, Osaka 590-0494, Japan
INTRODUCTION: Boron Neutron Capture Therapy
(BNCT) is an expecting cancer therapy for the treatment
of harsh and un-operatable malignant tumors. ...

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