{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T17:53:23Z","timestamp":1769104403299,"version":"3.49.0"},"reference-count":46,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2023,11,9]],"date-time":"2023-11-09T00:00:00Z","timestamp":1699488000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Cathepsins (Caths) are lysosomal proteases that participate in various physiological and pathological processes. Accumulating evidence suggests that caths play a multifaceted role in cancer progression and radiotherapy resistance responses. Their proteolytic activity influences the tumor\u2019s response to radiation by affecting oxygenation, nutrient availability, and immune cell infiltration within the tumor microenvironment. Cathepsin-mediated DNA repair mechanisms can promote radioresistance in cancer cells, limiting the efficacy of radiotherapy. Additionally, caths have been associated with the activation of prosurvival signaling pathways, such as PI3K\/Akt and NF-\u03baB, which can confer resistance to radiation-induced cell death. However, the effectiveness of radiotherapy can be limited by intrinsic or acquired resistance mechanisms in cancer cells. In this study, the regulation and expression of cathepsin B (cath B) in the colon carcinoma cell line (caco-2) before and after exposure to radiation were investigated. Cells were exposed to escalating ionizing radiation doses (2 Gy, 4 Gy, 6 Gy, 8 Gy, and 10 Gy). Analysis of protein expression, in vitro labeling using activity-based probes DCG04, and cath B pull-down revealed a radiation-induced up-regulation of cathepsin B in a dose-independent manner. Proteolytic inhibition of cathepsin B by cathepsin B specific inhibitor CA074 has increased the cytotoxic effect and cell death due to ionizing irradiation treatment in caco-2 cells. Similar results were also obtained after cathepsin B knockout by CRISPR CAS9. Furthermore, upon exposure to radiation treatment, the inhibition of cath B led to a significant upregulation in the expression of the proapoptotic protein BAX, while it induced a significant reduction in the expression of the antiapoptotic protein BCL-2. These results showed that cathepsin B could contribute to ionizing radiation resistance, and the abolishment of cathepsin B, either by inhibition of its proteolytic activity or expression, has increased the caco-2 cells susceptibility to ionizing irradiation.<\/jats:p>","DOI":"10.3390\/ijms242216146","type":"journal-article","created":{"date-parts":[[2023,11,10]],"date-time":"2023-11-10T01:17:51Z","timestamp":1699579071000},"page":"16146","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["The Significance of Cathepsin B in Mediating Radiation Resistance in Colon Carcinoma Cell Line (Caco-2)"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-7929-5365","authenticated-orcid":false,"given":"Ramadan F.","family":"Abdelaziz","sequence":"first","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"},{"name":"Division of Human Health, International Atomic Energy Agency, Wagramer Str. 5, 1400 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmed M.","family":"Hussein","sequence":"additional","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4183-5517","authenticated-orcid":false,"given":"Mohamed H.","family":"Kotob","sequence":"additional","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christina","family":"Weiss","sequence":"additional","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Krzysztof","family":"Chelminski","sequence":"additional","affiliation":[{"name":"Division of Human Health, International Atomic Energy Agency, Wagramer Str. 5, 1400 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0910-4573","authenticated-orcid":false,"given":"Christian R.","family":"Studenik","sequence":"additional","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6693-4530","authenticated-orcid":false,"given":"Mohammed","family":"Aufy","sequence":"additional","affiliation":[{"name":"Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,11,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1016\/j.bbapap.2011.10.002","article-title":"Cysteine cathepsins: From structure, function and regulation to new frontiers","volume":"1824","author":"Turk","year":"2012","journal-title":"Biochim. 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