Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29, Yoshida Shimoadachi-Cho, Sakyo-Ku, Kyoto, 606-8501, Japan.
Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, 54 Kawahara-Cho, Shogoin, Sakyo-Ku, Kyoto, 606-8507, Japan.
Ann Nucl Med. 2024 Oct;38(10):847-851. doi: 10.1007/s12149-024-01959-9. Epub 2024 Jul 8.
Prostate-specific membrane antigen (PSMA) is a well-known biomarker of prostate cancer. Previously, our group reported that the succinimidyl-cystatin-urea-glutamate (SCUE) moiety has a high affinity for PSMA. In this study, we developed the novel technetium-99m-labeled PSMA-targeting probe "[Tc]Tc-(Ham-SCUE)" based on a hydroxamamide chelate with a bivalent SCUE and evaluated its potential as a SPECT imaging probe for the diagnosis of PSMA-expressing prostate cancer.
Ham-SCUE was synthesized by a one-step reaction with Ham-Mal and cysteine-urea-glutamine. Then, Ham-SCUE was reacted with [Tc]NaTcO for 10 min at room temperature to obtain [Tc]Tc-(Ham-SCUE). [Tc]Tc-(Ham-SCUE) was added to LNCaP (high PSMA expression) cells or PC3 (low PSMA expression) cells, and their radioactivity was measured 60 min after administration. The blocking study was performed by co-incubation of LNCaP cells with various concentrations of 2-PMPA (a PSMA inhibitor) for 15 min before adding [Tc]Tc-(Ham-SCUE). The biodistribution of [Tc]Tc-(Ham-SCUE) in LNCaP/PC3 dual xenografted C.B.-17/Icr scid/scid Jcl mice was evaluated for 120 min after intravenous injection. The blocking study was performed by pretreatment of mice with 2-PMPA (10 mg/kg weight).
[Tc]Tc-(Ham-SCUE) was acquired at radiochemical yields of 56% with a radiochemical purity of over 95%. The cellular uptake level of [Tc]Tc-(Ham-SCUE) by LNCaP cells was significantly higher than that by PC3 cells (LNCaP: 11.12 ± 0.71 vs. PC3: 1.40 ± 0.13%uptake/mg protein, p < 0.01), and the uptake was significantly suppressed by pretreatment with 2-PMPA (2.56 ± 0.37%uptake/mg protein, p < 0.05). IC of 2-PMPA was 245 ± 47 nM. In the in vivo study, the radioactivity of LNCaP tumor tissue was significantly higher than that of PC3 tumor tissue at 120 min after the administration of [Tc]Tc-(Ham-SCUE) (LNCaP: 9.97 ± 2.79, PC3: 1.16 ± 0.23%ID/g, p < 0.01), and was suppressed by pretreatment with 2-PMPA (2.50 ± 0.45%ID/g, p < 0.01).
[Tc]Tc-(Ham-SCUE) has the potential to be a SPECT imaging agent for diagnosing high PSMA-expressing prostate cancer.
前列腺特异性膜抗原（PSMA）是前列腺癌的一种著名生物标志物。此前，我们小组报道称，琥珀酰亚胺基半胱氨酸-脲-谷氨酸（SCUE）部分对 PSMA 具有高亲和力。在这项研究中，我们基于具有双价 SCUE 的羟酰胺螯合物开发了新型锝-99m 标记的 PSMA 靶向探针[Tc]Tc-（Ham-SCUE），并评估了其作为用于诊断 PSMA 表达型前列腺癌的 SPECT 成像探针的潜力。
Ham-SCUE 通过 Ham-Mal 和半胱氨酸-脲-谷氨酰胺的一步反应合成。然后，Ham-SCUE 在室温下与[Tc]NaTcO 反应 10 分钟，得到[Tc]Tc-（Ham-SCUE）。将[Tc]Tc-（Ham-SCUE）添加到 LNCaP（高 PSMA 表达）细胞或 PC3（低 PSMA 表达）细胞中，并在给药后 60 分钟测量其放射性。通过在添加[Tc]Tc-（Ham-SCUE）之前将 LNCaP 细胞与各种浓度的 2-PMPA（PSMA 抑制剂）共孵育 15 分钟来进行阻断研究。通过在静脉注射后 120 分钟评估 LNCaP/PC3 双异种移植 C.B.-17/Icr scid/scid Jcl 小鼠中[Tc]Tc-（Ham-SCUE）的生物分布来进行阻断研究。通过用 2-PMPA（10mg/kg 体重）预处理小鼠来进行阻断研究。
[Tc]Tc-（Ham-SCUE）的放射化学收率为 56%，放射化学纯度超过 95%。LNCaP 细胞摄取[Tc]Tc-（Ham-SCUE）的水平明显高于 PC3 细胞（LNCaP：11.12±0.71 与 PC3：1.40±0.13%摄取/mg 蛋白，p<0.01），并且用 2-PMPA 预处理可显著抑制摄取（2.56±0.37%摄取/mg 蛋白，p<0.05）。2-PMPA 的 IC 为 245±47nM。在体内研究中，在给予[Tc]Tc-（Ham-SCUE）后 120 分钟，LNCaP 肿瘤组织的放射性明显高于 PC3 肿瘤组织（LNCaP：9.97±2.79，PC3：1.16±0.23%ID/g，p<0.01），并且用 2-PMPA 预处理可显著抑制摄取（2.50±0.45%ID/g，p<0.01）。
[Tc]Tc-（Ham-SCUE）有可能成为用于诊断高 PSMA 表达型前列腺癌的 SPECT 成像剂。
