{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:09:04Z","timestamp":1785431344475,"version":"3.56.0"},"reference-count":31,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T00:00:00Z","timestamp":1781827200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Medical Research Agency (ABM), Poland","award":["ABM KPOD.07.07-IW.07-0108\/24-00"],"award-info":[{"award-number":["ABM KPOD.07.07-IW.07-0108\/24-00"]}]},{"award":["ABM KPOD.07.07-IW.07-0108\/24-00"],"award-info":[{"award-number":["ABM KPOD.07.07-IW.07-0108\/24-00"]}],"id":[{"id":"https:\/\/ror.org\/026nedj88","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>The failure of therapy in muscle invasive bladder cancer (MIBC) is primarily attributed to tumor heterogeneity and therapy resistance. We propose a novel approach targeting interleukin-13 receptor subunit alpha 2 (IL-13R\u03b12), which is expressed on bladder cancer (BC) cells but absent in normal urothelial cells. We investigated the therapeutic effects of WPD101a immunotoxin (IL-13-DT390) on IL-13R\u03b12-expressing BC cells in relation to BC cell phenotype and functional characteristics in vitro using both 2-dimensional (2D) and 3-dimensional (3D) models. Cell phenotype and IL-13R\u03b12 expression were assessed using flow cytometry, immunofluorescence, and Western blot analysis. The biological effects of WPD101a were evaluated by measuring cell viability and proliferation using the MTT, sulforhodamine B (SRB), CellTiter-Glo and Live\/Dead assays. Apoptosis was assessed using Annexin V\/propidium iodide (PI) staining, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis of CASP genes expression. We found that the reference BC cell lines TCC-SUP, JMSU-1 and UM-UC-3 express IL-13R\u03b12 at various level in contrast to RT-4, HCV-29 and 5637 cells. Cells expressing IL-13R\u03b12 were sensitive to WPD101a at lower concentrations in the 2D model (0.1 ng\/mL) compared to the 3D model (1.0 ng\/mL). IL-13R\u03b12-negative cells remain resistant to the immunotoxin. WPD101a induces apoptosis in BC cells expressing IL-13R\u03b12 as confirmed by the presence of apoptotic cells, increase the proportion of cells in the subG1 phase, and by the effector CASP3, CASP7, and initiator CASP8, CASP9 genes expression. This study confirmed receptor-dependent cytotoxic effects of WPD101a and the ability and specificity to inhibit growth and apoptosis induction in MIBC cells expressing IL-13R\u03b12.<\/jats:p>","DOI":"10.3390\/ijms27125566","type":"journal-article","created":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T03:09:17Z","timestamp":1782270557000},"page":"5566","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Immunotoxin WPD101a as a Potential Drug Candidate for Targeted Therapy in Muscle Invasive Bladder Cancer Expressing IL-13R\u03b12\u2014In Vitro Study"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6590-4420","authenticated-orcid":false,"given":"Aleksandra","family":"Klimczak","sequence":"first","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4545-8843","authenticated-orcid":false,"given":"Agnieszka","family":"Krawczenko","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandra","family":"Stamnitz","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2757-5571","authenticated-orcid":false,"given":"Aleksandra","family":"Bielawska-Pohl","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4481-8991","authenticated-orcid":false,"given":"Paulina","family":"Piotrowska","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hanna","family":"Grzelenska","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aleksandra","family":"Wypychowska","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alicja","family":"Kisielewicz","sequence":"additional","affiliation":[{"name":"Laboratory of Biology of Stem and Neoplastic Cells, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcin","family":"Mielecki","sequence":"additional","affiliation":[{"name":"WPD Pharmaceuticals, 02-089 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5201-2402","authenticated-orcid":false,"given":"Radoslaw","family":"Borowski","sequence":"additional","affiliation":[{"name":"WPD Pharmaceuticals, 02-089 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariusz","family":"Olejniczak","sequence":"additional","affiliation":[{"name":"WPD Pharmaceuticals, 02-089 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3565-8860","authenticated-orcid":false,"given":"Beata","family":"Pajak-Tarnacka","sequence":"additional","affiliation":[{"name":"WPD Pharmaceuticals, 02-089 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/j.euo.2023.02.008","article-title":"A Systematic Review of Oncological Outcomes Associated with Bladder-sparing Strategies in Patients Achieving Complete Clinical Response to Initial Systemic Treatment for Localized Muscle-invasive Bladder Cancer","volume":"6","author":"Lenfant","year":"2023","journal-title":"Eur. 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