Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
Department of Nuclear Medicine, Changhai Hospital, Shanghai 200433, China.
Bioorg Med Chem. 2019 Mar 1;27(5):785-789. doi: 10.1016/j.bmc.2019.01.014. Epub 2019 Jan 17.
Carbonic anhydrase IX (CA IX) is the first carbonic anhydrase found to be associated with cancer that is over-expressed in a variety of human solid tumors. As a surrogate marker for hypoxia, the expression of CA IX is strongly upregulated in hypoxic tumors by hypoxia and hypoxia-inducible factor 1a (HIF-1a). In our pursuit of a CA IX-specific PET probe, we designed and synthesized a peptide-based CA IX imaging probe by the efficient click reaction of 1,3-dipolar cycloaddition of terminal alkynes and organic azides. The probe F-CA IX-P1-4-10 was obtained with a radiochemical yield of 35-45% (n = 5) and radiochemical purity of >99% in 70-80 min (HPLC purification time included). F-CA IX-P1-4-10 had good stability in phosphate buffered saline (PBS), but about 51% peptide degradation was detected in new-born calf serum (NBCS) after incubation. Preliminary microPET/CT experiments demonstrated a specific uptake of F-CA IX-P1-4-10 in HT29 tumor and the uptake of F-CA IX-P1-4-10 was blocked by peptide CA IX-P1-4-10-Yne pretreatment. Immunohistochemical staining and western blotting studies confirmed the HT29 tumor was CA IX-positive which further proved tumor accumulation of F-CA IX-P1-4-10 was correlated with CA IX expression. The results suggest that F-CA IX-P1-4-10 is a promising PET tracer for the specific imaging of CA IX-expressing tumors at the molecular level.
碳酸酐酶 9（CA9）是第一种被发现与癌症相关的碳酸酐酶，在多种人类实体肿瘤中过度表达。作为缺氧的替代标志物，CA9 的表达在缺氧肿瘤中通过缺氧和缺氧诱导因子 1a（HIF-1a）强烈上调。在我们追求 CA9 特异性 PET 探针的过程中，我们通过端炔和有机叠氮化物的 1,3-偶极环加成的有效点击反应设计并合成了一种基于肽的 CA9 成像探针。探针 F-CA IX-P1-4-10 的放射性化学产率为 35-45%（n=5），放射性化学纯度大于 99%，在 70-80min（包括 HPLC 纯化时间）内获得。F-CA IX-P1-4-10 在磷酸盐缓冲盐水（PBS）中稳定性良好，但在新牛血清（NBCS）孵育后检测到约 51%的肽降解。初步的 microPET/CT 实验表明，F-CA IX-P1-4-10 在 HT29 肿瘤中有特异性摄取，并且 F-CA IX-P1-4-10 的摄取可通过肽 CA IX-P1-4-10-Yne 预处理阻断。免疫组织化学染色和 Western blot 研究证实 HT29 肿瘤为 CA9 阳性，这进一步证明 F-CA IX-P1-4-10 的肿瘤积累与 CA9 表达相关。结果表明，F-CA IX-P1-4-10 是一种很有前途的 PET 示踪剂，可用于在分子水平上特异性成像 CA9 表达的肿瘤。
