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論文

Medical application of radiohalogenated peptides; Synthesis and ${it in vitro}$ evaluation of F(${it p}$-$$^{131}$$I)KCCYSL for targeting HER2

佐々木 一郎; 渡辺 茂樹; 大島 康宏; 須郷 由美; 山田 圭一*; 花岡 宏史*; 石岡 典子

Peptide Science 2015, p.243 - 246, 2016/03

Radioisotope labeled peptides with high affinity to receptors overexpressing on the surface of tumor cells are promising for applications in nuclear medicine such as diagnostic radiography and radiotherapy. Radiohalogens such as $$^{131}$$I and $$^{211}$$At are useful for clinical imaging and therapeutic applications, and it can be introduced at the ${it para}$ position of phenylalanine residue via electrophilic destannylation. KCCYSL (Lys$$^{1}$$-Cys$$^{2}$$-Cys$$^{3}$$-Tyr$$^{4}$$-Ser$$^{5}$$-Leu$$^{6}$$) is a hexapeptide containing disulfide bond. Previous study revealed that KCCYSL has potential as tumor imaging and therapeutic agent targeting tumor cells overexpressing the human epidermal growth factor receptor type 2 (HER2). In this study, we report synthesis and ${it in vitro}$ evaluation of radiohalogenated KCCYSL derivatives. Precursor peptides, Boc-F(${it p}$-SnBu$$_{3}$$)K(Boc)C(Trt)C(Trt)Y($$^{t}$$Bu)S($$^{t}$$Bu)L-OH and Boc-F(${it p}$-SnBu$$_{3}$$)GS($$^{t}$$Bu)GK(Boc)C(Trt)C(Trt)Y($$^{t}$$Bu)S($$^{t}$$Bu)L-OH, were synthesized by the Fmoc solid phase peptide synthesis. Then, precursor peptides were radioiodinated via electrophilic destannylation, and they were deprotected to obtain F(${it p}$-$$^{131}$$I)KCCYSL and F(${it p}$-$$^{131}$$I)GSGKCCYSL in radiochemical yield 15% and 17%, respectively. ${it In vitro}$ assays of the radioiodinated peptides for HER2 and stability in serum are being undertaken.

論文

Development of a widely usable amino acid tracer; $$^{76}$$Br-$$alpha$$-methyl-phenylalanine for tumor PET imaging

花岡 宏史*; 大島 康宏; 鈴木 結利花*; 山口 藍子*; 渡辺 茂樹; 上原 知也*; 永森 收志*; 金井 好克*; 石岡 典子; 対馬 義人*; et al.

Journal of Nuclear Medicine, 56(5), p.791 - 797, 2015/05

https://doi.org/10.2967/jnumed.114.152215
 被引用回数：18 パーセンタイル：62.62(Radiology, Nuclear Medicine & Medical Imaging)

Radiolabeled amino acids are superior PET tracers for imaging of malignant tumors, and amino acids labeled with $$^{76}$$Br, an attractive positron emitter due to its relatively long half-life (t$$_{1/2}$$=16.2 h), could potentially be widely usable tumor imaging tracer. In this study, in consideration of stability and tumor specificity, 2-$$^{76}$$Br-bromo-$$alpha$$-methyl-L-phenylalanine (2-$$^{76}$$Br-BAMP) and 4-$$^{76}$$Br-bromo-$$alpha$$-methyl-L-phenylalanine (4-$$^{76}$$Br-BAMP) were designed and their potential as a tumor imaging agent was evaluated. No-carrier-added $$^{76}$$Br and $$^{77}$$Br, the latter of which is suitable radiobromine for basic studies due to its longer half-life (t$$_{1/2}$$ = 57.1 h), were produced. Both $$^{77}$$Br-BAMPs were stable in the plasma and in the murine body. In biodistribution studies, 2-$$^{77}$$Br-BAMP showed more rapid blood clearance and lower renal accumulation than did 4-$$^{77}$$Br-BAMP. More than 90% of injected radioactivity was excreted in the urine by 6 h post-injection of 2-$$^{77}$$Br-BAMP. High tumor accumulation of 2-$$^{77}$$Br-BAMP was observed in tumor-bearing mice and PET imaging with 2-$$^{76}$$Br-BAMP enabled clear visualization of the tumor. These findings suggest that 2-$$^{76}$$Br-BAMP would constitute a potential new PET tracer for tumor imaging and may eventually enable the wider use of amino acid tracers.

論文

Synthesis and ${{it in vitro}}$ evaluation of $$^{64}$$Cu-labeled peptide for tumor imaging

須郷 由美; 佐々木 一郎; 渡辺 茂樹; 大島 康宏; 石岡 典子

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 100, 2015/03

https://doi.org/10.11484/jaea-review-2014-050

MARSGL peptide (H-Met-Ala-Arg-Ser-Gly-Leu-OH) has high affinity to the human epidermal growth factor receptor 2 (HER2) overexpressing in various tumor cells. Copper-64 ($$^{64}$$Cu) is a useful radionuclide in nuclear medicine, and can be produced by the cyclotron. In this study, we designed and synthesized $$^{64}$$Cu-labeled MARSGL peptide conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) as a novel positron emission tomography (PET) imaging probe for HER2 overexpressing tumors. The formation of $$^{64}$$Cu-DOTA-MARSGL was determined by TLC and HPLC compared with a non-radioactive preparation. It was confirmed that $$^{64}$$Cu-DOTA-MARSGL was obtained in high radiochemical yield more than 94%. We also examined a stability of $$^{64}$$Cu-DOTA-MARSGL ${it in vitro}$. The chromatogram was not changed after incubation in physiological saline at 37$$^{circ}$$C overnight. In order to evaluate the usefulness as a PET imaging probe, further ${it in vitro}$ studies on the stability in human or mice plasma and the cellular uptake are in progress.

論文

${{it In vitro}}$ studies on cellular binding and stability of $$^{64}$$Cu-labeled peptide for tumor imaging

須郷 由美; 大島 康宏; 佐々木 一郎; 石岡 典子

Peptide Science 2014, p.303 - 306, 2015/03

In the previous study, we have designed and synthesized $$^{64}$$Cu-DOTA-MARSGL as a novel positron emission tomography (PET) imaging probe for the human epidermal growth factor receptor 2 (HER2) overexpressing tumors. In order to evaluate the usefulness as a PET imaging probe, further ${{it in vitro}}$ studies on the cellular binding and the stability in human or murine plasma were carried out in this work. In the cellular binding assay, it was observed that the radioactivity bound to the cells was dependent on the HER2 expression level. This result suggests the HER2 specificity of $$^{64}$$Cu-DOTA-MARSGL. It was also confirmed that $$^{64}$$Cu-DOTA-MARSGL had high stability in saline, while it had low stability in plasma. The degradation product was analyzed by LC/MS using a non-radioactive preparation. The main peak in the chromatogram after incubation in plasma was assigned to Cu-DOTA-MA, which was formed by an endogenous peptidase. To increase the resistance to the peptidase, a modification of the structure is in progress.

論文

Exploring of peptides with affinity to HER2 from random peptide libraries using radioisotope; Random hexapeptide libraries with fixed amino acid sequence at 1 and 2 positions

佐々木 一郎; 花岡 宏史*; 山田 圭一*; 渡辺 茂樹; 須郷 由美; 大島 康宏; 鈴木 博元; 石岡 典子

Peptide Science 2014, p.257 - 260, 2015/03

We have sought to establish drug discovery system using radioisotope (RI) labeled peptides which have high affinity to target proteins overexpressed in cancers. Of the target proteins, we chose the human epidermal growth factor receptor type 2 (HER2), a membrane protein overexpressed in various cancers to evaluate the drug discovery system. Three series of random hexapeptide libraries introduced a radioiodinated D-tyrosine (y(3-$$^{131}$$I)) to $$N$$-terminal were designed and binding assay with HER2-expressed cell lines were conducted in this study. First, we synthesized a series of random hexapeptide libraries with fixed amino acid sequence at 1 and 2 positions, y(3-$$^{131}$$I)X$$^{1}$$X$$^{2}$$X$$^{3}$$X$$^{4}$$X$$^{5}$$X$$^{6}$$. Non-radioactive random peptide libraries, yXXXXXX, were prepared by Fmoc-SPPS with an automatic peptide synthesizer. Radioiodinated y(3-$$^{131}$$I)XXXXXX were subsequently synthesized in 30-50% radiochemical yield. Binding assay using HER2-overexpressed cell line showed that high affinity (38-50% dose, n=6) was obtained with yIIXXXX, while other random peptide libraries were yielded low affinity (approximately 1% dose), which indicated that the system using RI labeled random peptide libraries have potential to discover peptide drug for cancer therapy. Preparation of other random hexapeptide libraries are being undertaken.

論文

D体アミノ酸を利用した新規PET診断薬の開発

大島 康宏; 対馬 義人*

放射線と産業, (136), p.9 - 12, 2014/06

http://ci.nii.ac.jp/naid/40020125201

3-[$$^{18}$$F]フルオロ$$alpha$$メチルLチロシン(L-[$$^{18}$$F]FAMT)は、癌特異性が非常に高く、L-[$$^{18}$$F]FAMT-PETによる癌の正確な診断が可能である。しかし、L-[$$^{18}$$F]FAMTには高度な腎集積・滞留が認められ、体内クリアランス遅延により生ずる癌-正常組織間のコントラスト低下によって、癌と正常組織の境界は分かりづらい。我々は癌をより明瞭に把握できるようにするため、D体アミノ酸の正常組織集積が少なく、腎臓から尿中排泄されやすい特徴に着目し、3-[$$^{18}$$F]フルオロ$$alpha$$メチルDチロシン(D-[$$^{18}$$F]FAMT)を新たに合成して、その有用性を検討した。$$^{20}$$Ne(d,$$alpha$$)$$^{18}$$F反応により製造した$$^{18}$$F$$_{2}$$ガスを酢酸-酢酸カリウム溶液中に吹き込み、CH$$_{3}$$COO$$^{18}$$Fとした後、$$alpha$$メチルDチロシンと反応させてD-[$$^{18}$$F]FAMTを合成した。担癌マウスにおける体内分布を検討した結果、D-[$$^{18}$$F]FAMTはL-[$$^{18}$$F]FAMTに比べ、正常組織集積が少なく、素早く血中から消失した。特に腎集積・滞留は、D-[$$^{18}$$F]FAMTで顕著な低下が認められた。D-[$$^{18}$$F]FAMTの癌への集積量はL-[$$^{18}$$F]FAMTに比べ低かったものの、D-[$$^{18}$$F]FAMTは正常組織に比べ、癌に十分な集積・滞留を示した。小動物用PET撮像装置によるPET撮像を行った結果、D-[$$^{18}$$F]FAMTによってL-[$$^{18}$$F]FAMTよりも癌を明瞭にイメージングすることができた。以上より、D-[$$^{18}$$F]FAMTの新規PET診断薬としての有用性が示唆された。

論文

Prognostic significance of amino-acid transporter expression (LAT1, ASCT2, and xCT) in surgically resected tongue cancer

豊田 実*; 解良 恭一*; 大島 康宏; 石岡 典子; 紫野 正人*; 坂倉 浩一*; 高安 幸弘*; 高橋 克昌*; 富永 英之*; 織内 昇*; et al.

British Journal of Cancer, 110(10), p.2506 - 2513, 2014/05

https://doi.org/10.1038/bjc.2014.178
 被引用回数：106 パーセンタイル：95.14(Oncology)

Amino-acid transporters are necessary for the tumor cell growth and survival, and play a crucial role in the development of cancer. But, it remains unclear about the prognostic significance of L-type amino acid transporter 1 (LAT1), System ASC amino acid transporter 2 (ASCT2) and xCT expression in patients with tongue cancer. We conducted the clinicopathological study to investigate the protein expression of these amino acid transporters in tongue cancer. Eighty-five patients with surgically resected tongue cancer were evaluated. Tumor sections were stained by immunohistochemistry for LAT1, ASCT2, xCT, CD98, Ki-67, CD34 and p53. The expression of LAT1 and ASCT2 was significantly associated with disease staging, lymph node metastasis, lymphatic permeation, vascular invasion, CD98 expression and cell proliferation (Ki-67). xCT expression indicated a significant association with advanced stage and tumor factor, correlated with CD98. By univariate analysis, both LAT1 and ASCT2 had a significant relationship with prognosis. Multivariate analysis confirmed that LAT1 were independent prognostic factors for predicting poor prognosis. These results suggest that LAT1 and ASCT2 can serve as a significant prognostic factor for predicting worse outcome after surgical treatment and may play an important role in the development and pathogenesis for tongue cancer.

論文

Biological significance of fluorine-18-$$alpha$$-methyltyrosine (FAMT) uptake on PET in patients with oesophageal cancer

鈴木 茂正*; 解良 恭一*; 大島 康宏; 石岡 典子; 宗田 真*; 横堀 武彦*; 宮崎 達也*; 織内 昇*; 富永 英之*; 金井 好克*; et al.

British Journal of Cancer, 110(8), p.1985 - 1991, 2014/04

https://doi.org/10.1038/bjc.2014.142
 被引用回数：24 パーセンタイル：60.43(Oncology)

Fluorine-18-$$alpha$$-methyltyrosine (FAMT) as an amino acid tracer for positron emission tomography (PET) is useful for detecting human neoplasms. FAMT is accumulated in tumor cells solely via L-type amino acid transporter 1 (LAT1). This study was conducted to investigate the biological significance of FAMT uptake in patients with esophageal cancer. From April 2008 to December 2011, 42 patients with esophageal cancer underwent both FAMT PET and FDG PET before surgical treatment. The immunohistochemical analysis of LAT1, CD98, Ki-67, CD34, p53, p-Akt and p-mTOR was performed on the primary lesions. ${it In vitro}$ experiments were performed to examine the mechanism of FAMT uptake using LAT1 inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH). High uptake of FAMT was significantly associated with advanced stage, lymph node metastasis and the expression of LAT1, CD98, Ki-67 and CD34. LAT1 expression yielded a statistically significant correlation with CD98 expression, cell proliferation, angiogenesis and glucose metabolism. ${it In vitro}$ experiments revealed that FAMT was specifically transported by LAT1. The uptake of FAMT within tumor cells is determined by the LAT1 expression and correlated with cell proliferation and angiogenesis in esophageal cancer. The present experiments also confirmed the presence of LAT1 as an underlying mechanism of FAMT accumulation.

論文

Synthesis and ${it in vitro}$ Evaluation of $$^{64}$$Cu-labeled peptide for tumor imaging

須郷 由美; 佐々木 一郎; 渡辺 茂樹; 大島 康宏; 石岡 典子

Peptide Science 2013, p.355 - 358, 2014/03

HER2 is a member of the epidermal growth factor receptor family, which is overexpressed on the surface of tumor cells. H-Met-Ala-Arg-Ser-Gly-Leu-OH (MARSGL) is a linear peptide having high affinity to HER2 overexpressing in various cancer cells. In the previous study, we have synthesized a novel radioiodinated MARSGL via electrophilic destannylation in high radiochemical yield. $$^{64}$$Cu is an attractive radionuclide for positron emission tomography imaging as well as radiotherapy due to its half-life of 12.7 h and decay characteristics of both $$beta$$$$^{+}$$ and $$beta$$$$^{-}$$. 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) is a macrocyclic ligand for various metal ions. In this study, we designed and synthesized $$^{64}$$Cu-labeled MARSGL peptide conjugated with DOTA as an imaging probe for HER2 overexpressing tumors. In order to evaluate the usefulness of $$^{64}$$Cu-DOTA-MARSGL peptide as a PET imaging probe,${it in vitro}$ studies were also performed.

論文

Clinical significance of L-type amino acid transporter 1 expression as a prognostic marker and potential of new targeting therapy in biliary tract cancer

解良 恭一*; 須納瀬 豊*; 大島 康宏; 石岡 典子; 荒川 和久*; 小川 哲史*; 砂長 則明*; 清水 公裕*; 富永 英之*; 織内 昇*; et al.

BMC Cancer, 13, p.482_1 - 482_12, 2013/10

https://doi.org/10.1186/1471-2407-13-482
 被引用回数：74 パーセンタイル：88.89(Oncology)

The expression of L-type amino acid transporter 1 (LAT1) has been described to play essential roles in tumor growth and survival. However, it remains unclear about the clinicopathological significance of LAT1 expression in biliary tract cancer. This study was conducted to determine clinical significance of LAT1 expression and investigate whether LAT1 could be a new therapeutic target for biliary tract cancer. A total of 139 consecutive patients with resected pathologic stage I-IV biliary tract adenocarcinoma were retrospectively reviewed. Tumor sections were stained by immunohistochemistry for LAT1, CD98, Ki-67, microvessel density determined by CD34 and p53. Further, anti-tumor activity of LAT inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) was investigated using cholangiocarcinoma cell line. The expression of LAT1 was recognized in 64% of total patients, and closely correlated with CD98 expression, lymphatic metastases, cell proliferation and angiogenesis, and was a significant indicator for predicting poor outcome after surgery. Experiments showed that BCH significantly suppressed the tumor growth and BCH yielded an additive therapeutic efficacy to gemcitabine and 5-FU. A cooperative high expression of LAT1 with CD98 is a promising pathological marker to predict the outcome in biliary tract adenocarcinoma. Inhibition of LAT1 may be an effective targeted therapy for this distressing disease.

論文

Biological evaluation of 3-[$$^{18}$$F]fluoro-$$alpha$$-methyl-D-tyrosine (D-[$$^{18}$$F]FAMT) as a novel amino acid tracer for positron emission tomography

大島 康宏; 花岡 宏史*; 富永 英之*; 金井 好克*; 解良 恭一*; 山口 藍子*; 永森 收志*; 織内 昇*; 対馬 義人*; 遠藤 啓吾*; et al.

Annals of Nuclear Medicine, 27(4), p.314 - 324, 2013/05

https://doi.org/10.1007/s12149-013-0687-7
 被引用回数：15 パーセンタイル：50.05(Radiology, Nuclear Medicine & Medical Imaging)

Since D-amino acid is not distributed much in the non-target organs and is rapidly excreted in the urine, radiotracer using D-amino acid would allow clear PET image of the tumor early after administration. In this study, we prepared 3-[$$^{18}$$F]fluoro-$$alpha$$-methyl-D-tyrosine (D-[$$^{18}$$F]FAMT) and evaluated its usefulness. In biodistribution studies, D-[$$^{18}$$F]FAMT showed rapid clearance from the blood, marked accumulation and retention in the tumor and low accumulation in non-target organs. The amount of D-[$$^{18}$$F]FAMT in the tumor was also lowered, tumor-to-blood ratio and tumor-to-muscle ratio of D-[$$^{18}$$F]FAMT were similar to those of correspondign L-isomer, 3-[$$^{18}$$F]fluoro-$$alpha$$-methyl-L-tyrosine (L-[$$^{18}$$F]FAMT), at every timepoint. Consequently, PET imaging with D-[$$^{18}$$F]FAMT could not show clear image of the tumor early after the administration. However, D-[$$^{18}$$F]FAMT enabled higher tumor-to-background contrast than L-[$$^{18}$$F]FAMT. In conclusions, D-[$$^{18}$$F]FAMT showed rapid blood clearance, low accumulation in non-target organs, and tumor-selective image compared with L-[$$^{18}$$F]FAMT. Thus, D-[$$^{18}$$F]FAMT could potentially serve as a novel PET tracer for imaging malignant tumors.

論文

Synthesis of radioiodinated antitumor cyclic peptide, [$$^{125}$$I]-sansalvamide A derivative

渡邉 茂樹; 山田 圭一*; 津久井 匠隆*; 花岡 宏史*; 大島 康宏; 山口 藍子*; 奥 浩之*; 石岡 典子

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 88, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

Sansalvamide A (SA), a penta cyclic peptide isolated marine fungus, is a lead compound of anti-cancer reagent because the peptide has cytotoxicity against various cancer cell lines. Halogenated SA derivatives (SA-X, X = Cl, Br, I) was prepared and remarkable cytotocity against malignant human breast cancer. In this study, a radiohalogenated SA derivative [$$^{125}$$I]SA-I was prepared to conduct in vivo evaluation of SA derivatives. Synthetic scheme of [$$^{125}$$I]SA-I are as follows: an iodinated linear peptide, Boc-F(p-I)LLVL-OMe, was prepared by the conventional solid phase peptide synthesis. After preparation of stannylated peptide, Boc-F(p-SnBu$$_{3}$$)LLVL-OMe, $$^{125}$$I was labeled with electrophilic destannylation in the presence of oxidizing reagent. After deprotection of N- and C-termius, [$$^{125}$$I]SA-I was obtained successfully by macrocyclization in liquid phase. Overall labeled yield was 7%. To our best knowledge, this report is the first on the synthesis of radiolabeled SA derivative. In vivo evaluation of the SA derivative using [$$^{125}$$I]SA-I is being undertaken.

論文

Development of a $$^{76}$$Br-labeled amino acid derivative for PET imaging of tumor

花岡 宏史*; 渡邉 茂樹; 富永 英之*; 大島 康宏; 渡辺 智; 山田 圭一*; 飯田 靖彦*; 石岡 典子; 遠藤 啓吾*

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 89, 2013/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2012-046.pdf

近年、がんに対する特異性が高いPET薬剤として、$$^{11}$$Cや$$^{18}$$Fで標識したアミノ酸誘導体が開発され、臨床応用されるようになってきた。しかしながら$$^{11}$$Cや$$^{18}$$Fは半減期が非常に短いため、それぞれの病院で製造・合成する必要があり、限られた施設でしか使えないのが現状である。一方、$$^{76}$$Brは、半減期が16.1時間とポジトロン放出核種としては比較的長く、またハロゲン核種であるため母体化合物との結合にキレート剤等が必要ないことから、アミノ酸のような低分子化合物に対しても応用可能である。そこで本研究では、広く臨床使用することが可能な、新規がん診断用PETイメージング薬剤として$$^{76}$$Br標識アミノ酸誘導体の開発を計画した。基礎検討には半減期が長い放射性臭素である$$^{77}$$Br(半減期57時間)を用いて行うこととした。Br標識アミノ酸としては、$$alpha$$メチルフェニルアラニン($$alpha$$-Me-Phe)のパラ位にBrを導入したBr-$$alpha$$-Me-Pheを設計した。$$^{77}$$Br-$$alpha$$-Me-Pheは標識率25-40%で合成することができた。$$^{77}$$Br-$$alpha$$-Me-Pheを担癌マウスに投与したところ、腫瘍への高い集積性を示し、投与3時間後の腫瘍対血液比は3.94、腫瘍対筋肉比は3.95であった。$$^{76}$$Br-$$alpha$$-Me-Pheを担癌マウスに投与してPET撮像を行ったところ、腫瘍を明瞭に描出することができた。以上の結果から、$$^{76}$$Br-$$alpha$$-Me-Pheの新規がんイメージング薬剤としての有用性が示唆された。

論文

Involvement of Connexin43 hemichannel in ATP release after $$gamma$$-irradiation

大島 康宏; 月本 光俊*; 原田 均*; 小島 周二*

Journal of Radiation Research, 53(4), p.551 - 557, 2012/07

https://doi.org/10.1093/jrr/rrs014
 被引用回数：42 パーセンタイル：82.81(Biology)

We have recently reported that $$gamma$$-irradiation induces ATP release from B16 melanoma cells, which is dependent on P2X$$_{7}$$ receptor. However, the mechanism of ATP release caused by irradiation remains unclear. We here show the involvement of Cx43 in P2X$$_{7}$$ receptor-dependent ATP release after 0.5 Gy $$gamma$$-irradiation. Inhibitors of gap junction hemichannels and an inhibitory peptide for Cx43 (gap26), but not an inhibitory peptide for pannexin1 (Panx1), significantly blocked $$gamma$$-irradiation-induced ATP release from B16 melanoma cells. We confirmed high expression of Cx43 mRNA in B16 melanoma cells. These results suggest involvement of Cx43 in the radiation-induced ATP release. We found that tyrosine phosphorylation after 0.5 Gy $$gamma$$-irradiation was significantly blocked by P2X$$_{7}$$ receptor antagonist, but not gap26, suggesting that tyrosine phosphorylation is a downstream event from P2X$$_{7}$$ receptor. Since tyrosine kinase inhibitor significantly suppressed radiation-induced ATP release, tyrosine phosphorylation appears to play an important role in the Cx43-mediated ATP release downstream of P2X$$_{7}$$ receptor. In conclusion, the Cx43 hemichannel, which lies downstream of P2X$$_{7}$$ receptor, is involved in ATP release in response to radiation.

論文

Predicting cetuximab accumulation in ${it KRAS}$ wild-type and ${it KRAS}$ mutant colorectal cancer using $$^{64}$$Cu-labeled cetuximab positron emission tomography

Achmad, A.*; 花岡 宏史*; 吉岡 弘樹*; 山元 進司*; 富永 英之*; 荒木 拓也*; 大島 康宏; 織内 昇*; 遠藤 啓吾*

Cancer Science, 103(3), p.600 - 605, 2012/03

https://doi.org/10.1111/j.1349-7006.2011.02166.x
 被引用回数：25 パーセンタイル：55.86(Oncology)

Overexpression of epidermal growth factor receptor (EGFR) is common in colorectal cancer. However, cetuximab, an EGFR-targeting drug, is useful only for a subset of patients and no single predictor other than V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (${it KRAS}$) mutation status has been established. In this study, we investigated cetuximab accumulation in colorectal tumors using $$^{111}$$In-DOTA-cetuximab, and evaluated the potential of positron emission tomography (PET) imaging of $$^{64}$$Cu-DOTA-cetuximab. We found that ${it KRAS}$ wild-type tumors had significantly higher $$^{111}$$In-DOTA-cetuximab accumulation than ${it KRAS}$ mutant tumors. Based on ${it KRAS}$ mutation status, a strong correlation was found between $$^{111}$$In-DOTA-cetuximab tumor uptake and EGFR expression level. Significant correlation was also found between tumor uptake of $$^{111}$$In-DOTA-cetuximab and $$^{64}$$Cu-DOTA-cetuximab. PET imaging with $$^{64}$$Cu-DOTA-cetuximab effectively visualized cetuximab accumulation in colorectal tumors with a wide variety of EGFR expression levels and different ${it KRAS}$ mutation status as commonly encountered in the clinical setting. Our findings suggest that this radioimmunoimaging can be clinically translated as an in vivo tool to predict cetuximab accumulation in colorectal cancer patients prior to cetuximab therapy.

論文

Preparation and biological evaluation of 3-[$$^{76}$$Br]bromo-$$alpha$$-methyl-L-tyrosine, a novel tyrosine analog for PET imaging of tumors

大島 康宏; 花岡 宏史*; 渡邉 茂樹; 須郷 由美; 渡辺 智; 富永 英之*; 織内 昇*; 遠藤 啓吾*; 石岡 典子

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 91, 2012/01

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2011-043.pdf

3-[$$^{18}$$F]Fluoro-$$alpha$$-methyl-L-tyrosine ([$$^{18}$$F]FAMT) is a useful amino acid tracer for PET imaging of malignant tumors. FAMT analogs labeled with $$^{76}$$Br, a positron emitter with a long half-life (t$$_{1/2}$$=16.1 h), could be widely used as tracers for tumor imaging. In this study, 3-[$$^{76}$$Br]bromo-$$alpha$$-methyl-L-tyrosine ([$$^{76}$$Br]BAMT) was designed, and its usefulness was evaluated as a novel PET tracer for imaging malignant tumors. In this study, both [$$^{76}$$Br]BAMT and [$$^{77}$$Br]BAMT were prepared. [$$^{77}$$Br]BAMT was stable in vitro, but was catabolized after administration in mice. Cellular accumulation and retention of [$$^{77}$$Br]BAMT using LS180 colon adenocarcinoma cells were significantly higher than those of [$$^{18}$$F]FAMT. In biodistribution studies using LS180 tumor-bearing mice, the tumor accumulation of [$$^{77}$$Br]BAMT was higher than that of [$$^{18}$$F]FAMT. However, some level of debromination was seen, and this debromination caused more retention of radioactivity in the blood and organs than was seen with [$$^{18}$$F]FAMT. PET imaging with [$$^{76}$$Br]BAMT enabled clear visualization of the tumor. In conclusion, although an improvement in stability is still needed, $$^{76}$$Br-labeled FAMT analogs could potentially serve as PET tracers for the imaging of malignant tumors.

論文

Induction of extracellular ATP mediates increase in intracellular thioredoxin in RAW264.7 cells exposed to low-dose $$gamma$$-rays

大島 康宏; 北見 彰啓*; 河野 鮎美*; 月本 光俊*; 小島 周二*

Free Radical Biology & Medicine, 51(6), p.1240 - 1248, 2011/09

https://doi.org/10.1016/j.freeradbiomed.2011.06.014
 被引用回数：21 パーセンタイル：47.65(Biochemistry & Molecular Biology)

Extracellular ATP, which is released in response to various stresses, regulates the expression of intracellular antioxidants through activation of P2 receptors. We have recently found that low-dose $$gamma$$-rays induce ATP release from the exposed cells. However, it is not yet clear whether or not the radiation-induced extracellular ATP modulates the cellular redox balance. Here, we investigated whether or not $$gamma$$-ray irradiation-induced release of extracellular ATP contributes to the induction of cellular antioxidant thioredoxin-1 (Trx-1), using mouse macrophage-like RAW264.7 cells. Irradiation with $$gamma$$-rays or exogenously added ATP increased expression of Trx-1, and in both cases the increase was blocked by pretreatment with an ecto-nucleotidase, apyrase. Then, involvement of ATP-dependent reactive oxygen species (ROS) generation in the increase of antioxidant capacity was examined. ATP stimulation promoted generation of intracellular ROS and also increased Trx-1 expression. The increase of Trx-1 expression was significantly suppressed by pre-treatment of the cells with antioxidants. In conclusion, the $$gamma$$-ray irradiation-induced release of extracellular ATP may, at least in part, contribute to production of ROS via purinergic signaling, leading to promotion of intracellular antioxidants as an adaptive response to an oxidative stress.

論文

Preparation and biological evaluation of 3-[$$^{76}$$Br]bromo-$$alpha$$-methyl-L-tyrosine, a novel tyrosine analog for positron emission tomography imaging of tumors

大島 康宏; 花岡 宏史*; 渡邉 茂樹; 須郷 由美; 渡辺 智; 富永 英之*; 織内 昇*; 遠藤 啓吾*; 石岡 典子

Nuclear Medicine and Biology, 38(6), p.857 - 865, 2011/08

https://doi.org/10.1016/j.nucmedbio.2011.02.001
 被引用回数：14 パーセンタイル：47.34(Radiology, Nuclear Medicine & Medical Imaging)

3-[$$^{18}$$F]fluoro-$$alpha$$-methyl-L-tyrosine ([$$^{18}$$F]FAMT) is a useful amino acid tracer for positron emission tomography (PET) imaging of malignant tumors. FAMT analogs labeled with $$^{76}$$Br, a positron emitter with a long half-life ($$t$$$$_{1/2}$$=16.1 h), could be widely used as tracers for tumor imaging. In this study, 3-[$$^{76}$$Br]bromo-$$alpha$$-methyl-L-tyrosine ([$$^{76}$$Br]BAMT) was designed, and its usefulness was evaluated as a novel PET tracer for imaging malignant tumors. In this study, both [$$^{76}$$Br]BAMT and [$$^{77}$$Br]BAMT were prepared. [$$^{77}$$Br]BAMT was stable in vitro, but was catabolized after administration in mice. Cellular accumulation and retention of [$$^{77}$$Br]BAMT using LS180 colon adenocarcinoma cells were significantly higher than those of [$$^{18}$$F]FAMT. In biodistribution studies using LS180 tumor-bearing mice, the tumor accumulation of [$$^{77}$$Br]BAMT was higher than that of [$$^{18}$$F]FAMT. However, some level of debromination was seen, and this debromination caused more retention of radioactivity in the blood and organs than was seen with [$$^{18}$$F]FAMT. PET imaging with [$$^{76}$$Br]BAMT enabled clear visualization of the tumor. In conclusion, although an improvement in stability is still needed, $$^{76}$$Br-labeled FAMT analogs could potentially serve as PET tracers for the imaging of malignant tumors.

口頭

新規がん診断用PETイメージング薬剤$$^{76}$$Br標識アミノ酸誘導体の開発

花岡 宏史*; 渡邉 茂樹; 富永 英之*; 大島 康宏; 津久井 匠隆; 渡辺 智; 山田 圭一*; 飯田 靖彦*; 織内 昇*; 樋口 徹也*; et al.

no journal, , 

$$^{11}$$Cや$$^{18}$$Fで標識したアミノ酸誘導体は、がん診断用のPET薬剤として、臨床使用されているものも少なくない。しかしながら$$^{11}$$Cや$$^{18}$$Fは短半減期であるため、それぞれの病院で製造する必要があり、限られた施設でしか使えないのが現状である。一方で$$^{76}$$Brは半減期が16.1時間とポジトロン放出核種としては比較的長く、また$$^{18}$$Fと同じハロゲン核種であるため、$$^{18}$$F標識アミノ酸製剤と同様の分子設計を行うことができるという利点を有する。そこで本研究では、広く臨床使用することが可能な、新規がん診断用PETイメージング薬剤として$$^{76}$$Br標識アミノ酸誘導体を開発することを計画した。基礎的検討には半減期が長い放射性臭素である$$^{77}$$Br(半減期57時間)を用いて行うこととした。Br標識アミノ酸としては、$$alpha$$-メチルフェニルアラニンのパラ位にBrを導入したp-Bromo-$$alpha$$-methyl-Pheを設計した。$$^{77}$$Br標識Phe誘導体は標識率25$$sim$$40%で合成することができた。ノーマルマウスにおける体内動態を検討した結果、膵臓に高い集積が認められたことから、本化合物はアミノ酸トランスポーターに認識されていることが示唆された。一方で腎臓に対しても高い集積がみられた。担癌マウスに投与したところ、腫瘍への高い集積性を示し、投与3時間後の腫瘍血液比は3.94、腫瘍筋肉比は3.51となった。以上の結果から、Br標識Phe誘導体は、新規がんイメージング剤として有用である可能性が示された。

口頭

Development of $$^{76}$$Br-labeled amino acid derivative for PET imaging of tumor

花岡 宏史*; 渡邉 茂樹; 大島 康宏; 織内 昇*; 石岡 典子; 遠藤 啓吾*

no journal, , 

Positron emission tomography (PET) with $$^{18}$$F-fluorodeoxyglucose (FDG) is widely used for imaging of tumor. However, FDG accumulates not only in the tumor but also in the inflammation or the benign region. Recently, radiolabeled amino acid derivatives, more specific tracer for malignant tumors than FDG, have received attention, and are becoming to use in clinical phase. In this study, amino acid derivative labeled with Br-76 ($$^{76}$$Br; half-life = 16.1 h), an attractive positron emitter, was prepared and evaluated as a potential PET tracer for imaging tumors. Alpha-methyl phenylalanine ($$alpha$$-Me-Phe) was selected as the mother compound and $$^{76/77}$$Br was attached to para position of $$alpha$$-Me-Phe. Biodistribution studies of $$^{77}$$Br-$$alpha$$-Me-Phe in nude mice bearing colorectal cancer cell line, LS-180, showed a marked accumulation in the tumor at 3 h after injection, and resulting in high tumor-to-blood and tumor-to-muscle ratios of 3.94 and 3.51, respectively. $$^{76}$$Br-$$alpha$$-Me-Phe PET showed a clear image of the tumor, which was almost same with $$^{18}$$F-labeled amino acid derivative. These findings indicated that $$^{76}$$Br-$$alpha$$-Me-Phe would be a potential tracer for imaging tumor.

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