{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T14:45:35Z","timestamp":1785422735405,"version":"3.56.0"},"reference-count":35,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T00:00:00Z","timestamp":1779321600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Shandong Provincial Medical and Health Science and Technology Project","award":["202302041350"],"award-info":[{"award-number":["202302041350"]}]},{"DOI":"10.13039\/501100007129","name":"Shandong Provincial Natural Science Foundation","doi-asserted-by":"crossref","award":["ZR2024MH222"],"award-info":[{"award-number":["ZR2024MH222"]}],"id":[{"id":"10.13039\/501100007129","id-type":"DOI","asserted-by":"crossref"}]},{"award":["ZR2024MH222"],"award-info":[{"award-number":["ZR2024MH222"]}],"id":[{"id":"https:\/\/ror.org\/04aqat463","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Postgraduate Scientific Research Innovation Fund Project","award":["2024YJSCX014"],"award-info":[{"award-number":["2024YJSCX014"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Differentiation therapy holds significant potential for the treatment of multiple myeloma (MM). We previously identified that the aminopeptidase N (APN) inhibitor Bestatin promotes MM cell differentiation. Herein, we elucidate the underlying molecular mechanisms of this process. Utilizing MM1.S, U266, and RPMI-8226 cell lines, a combination of CCK-8 assays, flow cytometry, Wright\u2013Giemsa staining, Western blotting, qRT-PCR, ELISA, APN enzymatic activity analysis, SA-\u03b2-gal staining, and bioinformatic analyses revealed elevated APN expression across all cell types. Bestatin treatment induced MM cell differentiation in a concentration-dependent manner, which was accompanied by the upregulation of the differentiation marker CD49e, increased immunoglobulin light chain secretion, elevated cellular senescence, and a concomitant suppression of cell proliferation and APN enzymatic activity. Mechanistically, Bestatin exerts its effects by downregulating the CD79B\/BTK signaling pathway, thereby activating the downstream transcription factor STAT3. Consistent with this axis, direct inhibition of CD79B\/BTK alone was sufficient to induce differentiation, while blockade of STAT3 completely abrogated the differentiation-promoting effect of Bestatin. The APN-neutralizing antibody (WM15) yielded consistent results with Bestatin, further validating this regulatory axis. Furthermore, both the CD79B\/BTK inhibitor Ibrutinib and the STAT3 agonist GCDA potentiated the cytotoxicity of the clinical MM drug Ixazomib. Bestatin itself synergized with Ixazomib and enhanced the anti-proliferative effect of IL-6. In summary, our findings establish that the APN inhibitor Bestatin induces MM cell differentiation via the CD79B\/BTK-STAT3 signaling axis. Targeting this pathway represents a promising strategy to enhance the efficacy of Ixazomib, providing a compelling rationale for novel combination therapies in MM.<\/jats:p>","DOI":"10.3390\/cells15100949","type":"journal-article","created":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T15:05:08Z","timestamp":1779721508000},"page":"949","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["APN Inhibitor Bestatin Induces MM Cell Differentiation Through the CD79B\/BTK\/STAT3 Pathway"],"prefix":"10.3390","volume":"15","author":[{"given":"Xiaoke","family":"Wang","sequence":"first","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunyan","family":"Fang","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shanyu","family":"Li","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huakai","family":"Zeng","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junyi","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinwei","family":"Duan","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoyi","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenyan","family":"Jiang","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuejian","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Shandong Second Medical University, Weifang 261000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"6202","DOI":"10.1182\/blood-2010-06-292243","article-title":"Integrin \u03b27-mediated regulation of multiple myeloma cell adhesion, migration, and invasion","volume":"117","author":"Neri","year":"2011","journal-title":"Blood"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"10050","DOI":"10.1038\/s41467-025-65267-0","article-title":"T(SCM)-predominant allogeneic anti-BCMA CAR-T therapy for relapsed\/refractory multiple myeloma: Preclinical characterization and interim results from a phase 1 trial","volume":"16","author":"Tseng","year":"2025","journal-title":"Nat. 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