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 I and At are useful for clinical imaging and therapeutic applications, and it can be introduced at the position of phenylalanine residue via electrophilic destannylation. KCCYSL (Lys-Cys-Cys-Tyr-Ser-Leu) 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 evaluation of radiohalogenated KCCYSL derivatives. Precursor peptides, Boc-F(-SnBu)K(Boc)C(Trt)C(Trt)Y(Bu)S(Bu)L-OH and Boc-F(-SnBu)GS(Bu)GK(Boc)C(Trt)C(Trt)Y(Bu)S(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(-I)KCCYSL and F(-I)GSGKCCYSL in radiochemical yield 15% and 17%, respectively. assays of the radioiodinated peptides for HER2 and stability in serum are being undertaken.
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
Radiolabeled amino acids are superior PET tracers for imaging of malignant tumors, and amino acids labeled with Br, an attractive positron emitter due to its relatively long half-life (t=16.2 h), could potentially be widely usable tumor imaging tracer. In this study, in consideration of stability and tumor specificity, 2-Br-bromo--methyl-L-phenylalanine (2-Br-BAMP) and 4-Br-bromo--methyl-L-phenylalanine (4-Br-BAMP) were designed and their potential as a tumor imaging agent was evaluated. No-carrier-added Br and Br, the latter of which is suitable radiobromine for basic studies due to its longer half-life (t = 57.1 h), were produced. Both Br-BAMPs were stable in the plasma and in the murine body. In biodistribution studies, 2-Br-BAMP showed more rapid blood clearance and lower renal accumulation than did 4-Br-BAMP. More than 90% of injected radioactivity was excreted in the urine by 6 h post-injection of 2-Br-BAMP. High tumor accumulation of 2-Br-BAMP was observed in tumor-bearing mice and PET imaging with 2-Br-BAMP enabled clear visualization of the tumor. These findings suggest that 2-Br-BAMP would constitute a potential new PET tracer for tumor imaging and may eventually enable the wider use of amino acid tracers.
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
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 (Cu) is a useful radionuclide in nuclear medicine, and can be produced by the cyclotron. In this study, we designed and synthesized 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 Cu-DOTA-MARSGL was determined by TLC and HPLC compared with a non-radioactive preparation. It was confirmed that Cu-DOTA-MARSGL was obtained in high radiochemical yield more than 94%. We also examined a stability of Cu-DOTA-MARSGL . The chromatogram was not changed after incubation in physiological saline at 37C overnight. In order to evaluate the usefulness as a PET imaging probe, further studies on the stability in human or mice plasma and the cellular uptake are in progress.
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 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 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 Cu-DOTA-MARSGL. It was also confirmed that 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.
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-I)) to -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-I)XXXXXX. Non-radioactive random peptide libraries, yXXXXXX, were prepared by Fmoc-SPPS with an automatic peptide synthesizer. Radioiodinated y(3-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.
大島 康宏; 対馬 義人*
放射線と産業, (136), p.9 - 12, 2014/06
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
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.
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
Fluorine-18--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. 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. 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.
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. 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 and . 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 Cu-labeled MARSGL peptide conjugated with DOTA as an imaging probe for HER2 overexpressing tumors. In order to evaluate the usefulness of Cu-DOTA-MARSGL peptide as a PET imaging probe, studies were also performed.
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
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.
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
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-[F]fluoro--methyl-D-tyrosine (D-[F]FAMT) and evaluated its usefulness. In biodistribution studies, D-[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-[F]FAMT in the tumor was also lowered, tumor-to-blood ratio and tumor-to-muscle ratio of D-[F]FAMT were similar to those of correspondign L-isomer, 3-[F]fluoro--methyl-L-tyrosine (L-[F]FAMT), at every timepoint. Consequently, PET imaging with D-[F]FAMT could not show clear image of the tumor early after the administration. However, D-[F]FAMT enabled higher tumor-to-background contrast than L-[F]FAMT. In conclusions, D-[F]FAMT showed rapid blood clearance, low accumulation in non-target organs, and tumor-selective image compared with L-[F]FAMT. Thus, D-[F]FAMT could potentially serve as a novel PET tracer for imaging malignant tumors.
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
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 [I]SA-I was prepared to conduct in vivo evaluation of SA derivatives. Synthetic scheme of [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)LLVL-OMe, I was labeled with electrophilic destannylation in the presence of oxidizing reagent. After deprotection of N- and C-termius, [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 [I]SA-I is being undertaken.
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
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
We have recently reported that -irradiation induces ATP release from B16 melanoma cells, which is dependent on P2X receptor. However, the mechanism of ATP release caused by irradiation remains unclear. We here show the involvement of Cx43 in P2X receptor-dependent ATP release after 0.5 Gy -irradiation. Inhibitors of gap junction hemichannels and an inhibitory peptide for Cx43 (gap26), but not an inhibitory peptide for pannexin1 (Panx1), significantly blocked -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 -irradiation was significantly blocked by P2X receptor antagonist, but not gap26, suggesting that tyrosine phosphorylation is a downstream event from P2X 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 receptor. In conclusion, the Cx43 hemichannel, which lies downstream of P2X receptor, is involved in ATP release in response to radiation.
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
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 () mutation status has been established. In this study, we investigated cetuximab accumulation in colorectal tumors using In-DOTA-cetuximab, and evaluated the potential of positron emission tomography (PET) imaging of Cu-DOTA-cetuximab. We found that wild-type tumors had significantly higher In-DOTA-cetuximab accumulation than mutant tumors. Based on mutation status, a strong correlation was found between In-DOTA-cetuximab tumor uptake and EGFR expression level. Significant correlation was also found between tumor uptake of In-DOTA-cetuximab and Cu-DOTA-cetuximab. PET imaging with Cu-DOTA-cetuximab effectively visualized cetuximab accumulation in colorectal tumors with a wide variety of EGFR expression levels and different 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.
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
3-[F]Fluoro--methyl-L-tyrosine ([F]FAMT) is a useful amino acid tracer for PET imaging of malignant tumors. FAMT analogs labeled with Br, a positron emitter with a long half-life (t=16.1 h), could be widely used as tracers for tumor imaging. In this study, 3-[Br]bromo--methyl-L-tyrosine ([Br]BAMT) was designed, and its usefulness was evaluated as a novel PET tracer for imaging malignant tumors. In this study, both [Br]BAMT and [Br]BAMT were prepared. [Br]BAMT was stable in vitro, but was catabolized after administration in mice. Cellular accumulation and retention of [Br]BAMT using LS180 colon adenocarcinoma cells were significantly higher than those of [F]FAMT. In biodistribution studies using LS180 tumor-bearing mice, the tumor accumulation of [Br]BAMT was higher than that of [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 [F]FAMT. PET imaging with [Br]BAMT enabled clear visualization of the tumor. In conclusion, although an improvement in stability is still needed, Br-labeled FAMT analogs could potentially serve as PET tracers for the imaging of malignant tumors.
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
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 -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 -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 -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 -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.
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
3-[F]fluoro--methyl-L-tyrosine ([F]FAMT) is a useful amino acid tracer for positron emission tomography (PET) imaging of malignant tumors. FAMT analogs labeled with Br, a positron emitter with a long half-life (=16.1 h), could be widely used as tracers for tumor imaging. In this study, 3-[Br]bromo--methyl-L-tyrosine ([Br]BAMT) was designed, and its usefulness was evaluated as a novel PET tracer for imaging malignant tumors. In this study, both [Br]BAMT and [Br]BAMT were prepared. [Br]BAMT was stable in vitro, but was catabolized after administration in mice. Cellular accumulation and retention of [Br]BAMT using LS180 colon adenocarcinoma cells were significantly higher than those of [F]FAMT. In biodistribution studies using LS180 tumor-bearing mice, the tumor accumulation of [Br]BAMT was higher than that of [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 [F]FAMT. PET imaging with [Br]BAMT enabled clear visualization of the tumor. In conclusion, although an improvement in stability is still needed, Br-labeled FAMT analogs could potentially serve as PET tracers for the imaging of malignant tumors.
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, ,
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 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 (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 (-Me-Phe) was selected as the mother compound and Br was attached to para position of -Me-Phe. Biodistribution studies of Br--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. Br--Me-Phe PET showed a clear image of the tumor, which was almost same with F-labeled amino acid derivative. These findings indicated that Br--Me-Phe would be a potential tracer for imaging tumor.