New Way to Diagnose Tumor at an Early Stage

The specific imaging of a potential tumor biomarker through a probe can detect many cancer types at an early stage, according to a study published in Angewandte Chemie International Edition.

As survival rates differ greatly between cancer patients treated at early or late stages, early detection of tumors is of great importance to cancer therapy.

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‘Early detection of tumor is possible through Cathepsin B (CTSB)-initiated intracellular self-assembly of small-molecule PA imaging probes into nanoparticles.’

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Cathepsin B (CTSB) is considered as a potential biomarker for the early diagnosis of cancers due to its increased expression in the early stage of many cancer types. As a result, the effective and precise monitoring of CTSB activity offers a way out.

Taking this into account, a research team from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences used photoacoustic (PA) imaging for CTSB in tumor detection in a new study.

PA imaging is a new type of non-invasive and non-ionizing biomedical imaging method, which has a huge potential in biomedical research and disease diagnosis due to its excellent tissue-penetrating depth and high spatial resolution.

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Using the self-assembly signal enhancement of PA imaging probe, they designed a CTSB-activatable near-infrared PA probe Val-Cit-Cys(SEt)-Lys(Cypate)-CBT (Cypate-CBT).

When Cypate-CBT enters CTSB-overexpressing tumor cells, its disulfide bond is reduced by intracellular glutathione, and its specific cleavage substrate Val-Cit is cleaved by CTSB to produce Cypate-CBT-Cleaved, which undergoes an intermolecular CBT-Cys click reaction to yield Cypate-CBT-Dimer.

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The Cypate-CBT-Dimer then self-assembles into near-infrared nanoparticles Cypate-CBT-NPs.

This approach effectively increases local probe concentration, prolongs the retention time, and enhances the PA signal of the probe for CTSB activity imaging.

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Brain tumors are the abnormal growth of brain cells that may be benign or metastatic. Brain tumors account for about 2.4% of all the tumor diagnosesandare most challenging due to their critically delicate location.

They also found that compared with unmodified Cypate, the newly designed probe showed a 4.9-fold and 4.7-fold PA signal enhancement in CTSB-overexpressing MDA-MB-231 cancer cells or tumors, respectively.

Source-Medindia