Linders Daan G J, Bijlstra Okker D, Fallert Laura C, Dekker-Ensink N Geeske, March Taryn L, Pool Martin, Walker Ethan, Straight Brian, Basilion James P, Bogyo Matthew, Burggraaf Jacobus, Hilling Denise E, Vahrmeijer Alexander L, Kuppen Peter J K, Crobach A Stijn L P
Department of Surgery, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands.
Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands.
Mol Imaging Biol. 2024 Dec;26(6):1057-1067. doi: 10.1007/s11307-024-01955-5. Epub 2024 Sep 27.
Cysteine cathepsins are proteases that play a role in normal cellular physiology and neoplastic transformation. Elevated expression and enzymatic activity of cathepsins in breast cancer (BCa) indicates their potential as a target for tumor imaging. In particular cathepsin B (CTSB), L (CTSL), and S (CTSS) are used as targets for near-infrared (NIR) fluorescence imaging (FI), a technique that allows real-time intraoperative tumor visualization and resection margin assessment. Therefore, this immunohistochemical study explores CTSB, CTSL, and CTSS expression levels in a large breast cancer patient cohort, to investigate in which BCa patients the use of cathepsin-targeted NIR FI may have added value.
Protein expression was analyzed in tumor tissue microarrays (TMA) of BCa patients using immunohistochemistry and quantified as a total immunostaining score (TIS), ranging from 0-12. In total, the tissues of 557 BCa patients were included in the TMA.
CTSB, CTSL, and CTSS were successfully scored in respectively 340, 373 and 252 tumors. All tumors showed CTSB, CTSL, and/or CTSS expression to some extent (TIS > 0). CTSB, CTSL, and CTSS expression was scored as high (TIS > 6) in respectively 28%, 80%, and 18% of tumors. In 89% of the tumors scored for all three cathepsins, the expression level of one or more of these proteases was scored as high (TIS > 6). Tumors showed significantly higher cathepsin expression levels with advancing Bloom-Richardson grade (p < 0.05). Cathepsin expression was highest in estrogen receptor (ER)-negative, human epidermal growth factor receptor 2(HER2)-positive and triple-negative (TN) tumors. There was no significant difference in cathepsin expression between tumors that were treated with neoadjuvant systemic therapy and tumors that were not.
The expression of at least one of the cysteine cathepsins B, L and S in all breast tumor tissues tested suggests that cathepsin-activatable imaging agents with broad reactivity for these three proteases will likely be effective in the vast majority of breast cancer patients, regardless of molecular subtype and treatment status. Patients with high grade ER-negative, HER2-positive, or TN tumors might show higher imaging signals.
半胱氨酸组织蛋白酶是一类蛋白酶，在正常细胞生理和肿瘤转化过程中发挥作用。乳腺癌（BCa）中组织蛋白酶的表达升高和酶活性增加表明其有望成为肿瘤成像的靶点。尤其是组织蛋白酶B（CTSB）、L（CTSL）和S（CTSS）被用作近红外（NIR）荧光成像（FI）的靶点，该技术可实现术中实时肿瘤可视化及切缘评估。因此，本免疫组织化学研究探讨了大量乳腺癌患者队列中CTSB、CTSL和CTSS的表达水平，以研究在哪些BCa患者中使用以组织蛋白酶为靶点的NIR FI可能具有附加价值。
使用免疫组织化学方法分析BCa患者肿瘤组织微阵列（TMA）中的蛋白表达，并将其量化为总免疫染色评分（TIS），范围为0至12分。TMA共纳入了557例BCa患者的组织。
分别在340、373和252个肿瘤中成功对CTSB、CTSL和CTSS进行了评分。所有肿瘤均在一定程度上显示出CTSB、CTSL和/或CTSS的表达（TIS>0）。CTSB、CTSL和CTSS的表达在分别28%、80%和18%的肿瘤中被评为高表达（TIS>6）。在对所有三种组织蛋白酶进行评分的肿瘤中，89%的肿瘤中一种或多种这些蛋白酶的表达水平被评为高表达（TIS>6）。随着Bloom-Richardson分级的升高，肿瘤的组织蛋白酶表达水平显著升高（p<0.05）。组织蛋白酶在雌激素受体（ER）阴性、人表皮生长因子受体2（HER2）阳性和三阴性（TN）肿瘤中表达最高。接受新辅助全身治疗的肿瘤与未接受新辅助全身治疗的肿瘤之间，组织蛋白酶表达无显著差异。
在所有检测的乳腺肿瘤组织中，半胱氨酸组织蛋白酶B、L和S中至少有一种的表达表明，对这三种蛋白酶具有广泛反应性的组织蛋白酶可激活成像剂可能对绝大多数乳腺癌患者有效，无论其分子亚型和治疗状态如何。ER阴性、HER2阳性或TN的高级别肿瘤患者可能显示出更高的成像信号。
