Czyzyk, T. A. | bioRxiv Science

bioRxiv2025

A caspase-1-cathepsin AND-gate probe for selectiveimaging of inflammasome activation

Caspase-1 is a key mediator of the inflammasome pathway, which is associated with several inflammatory disorders including obesity, diabetes mellitus (DM), cardiovascular diseases (CVDs), cancers and chronic respiratory diseases. Although substrate-based probes can be used to visualize the activity of caspase-1, none are selective enough for use as imaging agents. Here, we report the design and synthesis of a AND-gate substrate probe (Cas1-Cat-Cy7) that requires processing by both caspase-1 and cathepsins to produce a signal. Because both enzymes are only found together and active at the site of inflammasome activation, the resulting probe can be used to image caspase-1 mediated inflammation. We demonstrate that the probe produces selective signals in ex vivo biochemical and cellular assays and in a mouse model of acute inflammation.

biochemistry↗

bioRxiv2024

Loss of the predicted cell adhesion molecule MPZL3 promotes EMT and chemoresistance in ovarian cancer

Myelin protein zero-like 3 (MPZL3) is an Immunoglobulin-containing transmembrane protein with predicted cell adhesion molecule function. Loss of 11q23, where the MPZL3 gene resides, is frequently observed in cancer, and MPZL3 copy number alterations are frequently detected in tumor specimens. Yet the role and consequences of altered MPZL3 expression have not been explored in tumor development and progression. We addressed this in ovarian cancer, where both MPZL3 amplification and deletions are observed in respective subsets of high-grade serous specimens. While high and low MPZL3 expressing populations were similarly observed in primary ovarian tumors from an independent patient cohort, metastatic omental tumors largely displayed decreased MPZL3 expression, suggesting that MPZL3 loss is associated with metastatic progression. MPZL3 knock-down leads to strong upregulation of vimentin and an EMT gene signature that is associated with poor patient outcomes. Moreover, MPZL3 is necessary for homotypic cancer cell adhesion, and decreasing MPZL3 expression enhances invasion and clearance of mesothelial cell monolayers. In addition, MPZL3 loss abrogated cell cycle progression and proliferation. This was associated with increased resistance to Cisplatin and Olaparib and reduced DNA damage and apoptosis in response to these agents. Enhanced Cisplatin resistance was further validated in vivo. These data demonstrate for the first time that MPZL3 acts as an adhesion molecule and that MPZL3 loss results in EMT, decreased proliferation, and drug resistance in ovarian cancer. Our study suggests that decreased MPZL3 expression is a phenotype of ovarian cancer tumor progression and metastasis and may contribute to treatment failure in advanced-stage patients.

cancer biology↗