{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T02:42:14Z","timestamp":1790908934937,"version":"4.1.0"},"reference-count":48,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,6]],"date-time":"2026-01-06T00:00:00Z","timestamp":1767657600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000869","name":"Susan G. Komen for the Cure","doi-asserted-by":"publisher","award":["SAC220219"],"award-info":[{"award-number":["SAC220219"]}],"id":[{"id":"10.13039\/100000869","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Winship Invest$ Winter 2022 grant"},{"name":"Emory University"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomolecules"],"abstract":"<jats:p>Cyclin-dependent kinase 4\/6 inhibitors (CDK4\/6i) have transformed the treatment landscape for estrogen receptor-positive (ER+) breast cancer, yet resistance remains a major clinical challenge. Although CDK4\/6i induce G1 arrest and therapy-induced senescence (TIS), the exact nature of this senescent state and its contribution to resistance are not well understood. To explore this, we developed palbociclib- (2PR, 9PR, TPR) and abemaciclib- (2AR, 9AR, TAR) resistant ER+ breast cancer sublines through prolonged drug exposure over six months. Resistant cells demonstrated distinct phenotypic alterations, including cellular senescence, reduced mitochondrial membrane potential, and impaired glycolytic activity. Cytokine profiling and enzyme-linked immunosorbent assay (ELISA) validation revealed a non-canonical senescence-associated secretory phenotype (SASP) characterized by elevated growth\/differentiation factor 15 (GDF-15) and serpin E1 (plasminogen activator inhibitor-1, PAI-1) and absence of classical pro-inflammatory interleukins, including IL-1\u03b1 and IL-6. IL-8 levels were significantly elevated, but no association with epithelial\u2013mesenchymal transition (EMT) was observed. Resistant cells preserved their epithelial morphology, showed no upregulation of EMT markers, and lacked aldehyde dehydrogenase 1-positive (ALDH1+) stem-like populations. Additionally, Regulated upon Activation, Normal T-cell Expressed, and Secreted (RANTES) was strongly upregulated in palbociclib-resistant cells. Together, these findings identify a distinct, non-canonical senescence phenotype associated with CDK4\/6i resistance and may provide a foundation for identifying new vulnerabilities in resistant ER+ breast cancers through targeting SASP-related signaling.<\/jats:p>","DOI":"10.3390\/biom16010093","type":"journal-article","created":{"date-parts":[[2026,1,6]],"date-time":"2026-01-06T09:40:29Z","timestamp":1767692429000},"page":"93","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Non-Canonical Senescence Phenotype in Resistance to CDK4\/6 Inhibitors in ER-Positive Breast Cancer"],"prefix":"10.3390","volume":"16","author":[{"given":"Aynura","family":"Mammadova","sequence":"first","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Gu","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ling","family":"Ruan","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8861-9980","authenticated-orcid":false,"given":"Sunil S.","family":"Badve","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA"},{"name":"Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9927-4893","authenticated-orcid":false,"given":"Yesim","family":"G\u00f6kmen-Polar","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA"},{"name":"Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1038\/s41571-023-00840-4","article-title":"The CDK4\/6 inhibitor revolution\u2014A game-changing era for breast cancer treatment","volume":"21","author":"Morrison","year":"2024","journal-title":"Nat. Rev. Clin. Oncol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1186\/s13058-022-01510-6","article-title":"Cellular mechanisms underlying response and resistance to CDK4\/6 inhibitors in the treatment of hormone receptor-positive breast cancer","volume":"24","author":"Watt","year":"2022","journal-title":"Breast Cancer Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1001\/jamaoncol.2019.4782","article-title":"The Effect of Abemaciclib Plus Fulvestrant on Overall Survival in Hormone Receptor-Positive, ERBB2-Negative Breast Cancer That Progressed on Endocrine Therapy-MONARCH 2: A Randomized Clinical Trial","volume":"6","author":"Sledge","year":"2020","journal-title":"JAMA Oncol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"101103","DOI":"10.1016\/j.drup.2024.101103","article-title":"Mechanisms of sensitivity and resistance to CDK4\/CDK6 inhibitors in hormone receptor-positive breast cancer treatment","volume":"76","author":"Glaviano","year":"2024","journal-title":"Drug Resist. Updates"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1038\/s41568-022-00450-9","article-title":"Exploiting senescence for the treatment of cancer","volume":"22","author":"Wang","year":"2022","journal-title":"Nat. Rev. Cancer"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"5165","DOI":"10.1038\/s41388-020-1354-9","article-title":"Senescence as a therapeutically relevant response to CDK4\/6 inhibitors","volume":"39","author":"Wagner","year":"2020","journal-title":"Oncogene"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e108946","DOI":"10.15252\/embj.2021108946","article-title":"Pharmacological CDK4\/6 inhibition reveals a p53-dependent senescent state with restricted toxicity","volume":"41","author":"Wang","year":"2022","journal-title":"EMBO J."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2655","DOI":"10.1080\/15384101.2018.1554781","article-title":"Rapamycin, proliferation and geroconversion to senescence","volume":"17","author":"Blagosklonny","year":"2018","journal-title":"Cell Cycle"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4062","DOI":"10.1016\/j.molcel.2023.10.016","article-title":"CDK4\/6 inhibitor-mediated cell overgrowth triggers osmotic and replication stress to promote senescence","volume":"83","author":"Crozier","year":"2023","journal-title":"Mol. Cell"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1080\/15384101.2020.1859195","article-title":"Sustained mTORC1 activity during palbociclib-induced growth arrest triggers senescence in ER+ breast cancer cells","volume":"20","author":"Maskey","year":"2021","journal-title":"Cell Cycle"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Zhou, F.H., Downton, T., Freelander, A., Hurwitz, J., Caldon, C.E., and Lim, E. (2023). CDK4\/6 inhibitor resistance in estrogen receptor positive breast cancer, a 2023 perspective. Front. Cell Dev. Biol., 11.","DOI":"10.3389\/fcell.2023.1148792"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"908","DOI":"10.1158\/1535-7163.MCT-17-0537","article-title":"Combined Inhibition of mTOR and CDK4\/6 Is Required for Optimal Blockade of E2F Function and Long-term Growth Inhibition in Estrogen Receptor-positive Breast Cancer","volume":"17","author":"Michaloglou","year":"2018","journal-title":"Mol. Cancer Ther."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"619","DOI":"10.1038\/s41571-022-00668-4","article-title":"Senescence and cancer\u2014Role and therapeutic opportunities","volume":"19","author":"Schmitt","year":"2022","journal-title":"Nat. Rev. Clin. Oncol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2853","DOI":"10.1371\/journal.pbio.0060301","article-title":"Senescence-associated secretory phenotypes reveal cell-nonautonomous functions of oncogenic RAS and the p53 tumor suppressor","volume":"6","author":"Coppe","year":"2008","journal-title":"PLoS Biol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1186\/s41232-022-00197-8","article-title":"The roles and mechanisms of senescence-associated secretory phenotype (SASP): Can it be controlled by senolysis?","volume":"42","author":"Ohtani","year":"2022","journal-title":"Inflamm. Regen."},{"key":"ref_16","first-page":"273","article-title":"Therapy-induced senescent tumor cells in cancer relapse","volume":"3","author":"Song","year":"2023","journal-title":"J. Natl. Cancer Cent."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1016\/j.cmet.2015.11.011","article-title":"Mitochondrial Dysfunction Induces Senescence with a Distinct Secretory Phenotype","volume":"23","author":"Wiley","year":"2016","journal-title":"Cell Metab."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e158447","DOI":"10.1172\/JCI158447","article-title":"Mitochondrial dysfunction in cell senescence and aging","volume":"132","author":"Miwa","year":"2022","journal-title":"J. Clin. Investig."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1186","DOI":"10.1111\/febs.16361","article-title":"Cellular senescence: All roads lead to mitochondria","volume":"290","author":"Martini","year":"2023","journal-title":"FEBS J."},{"key":"ref_20","first-page":"3486","article-title":"MCF7\/LCC9: An antiestrogen-resistant MCF-7 variant in which acquired resistance to the steroidal antiestrogen ICI 182,780 confers an early cross-resistance to the nonsteroidal antiestrogen tamoxifen","volume":"57","author":"Brunner","year":"1997","journal-title":"Cancer Res."},{"key":"ref_21","first-page":"3229","article-title":"MCF7\/LCC2: A 4-hydroxytamoxifen resistant human breast cancer variant that retains sensitivity to the steroidal antiestrogen ICI 182,780","volume":"53","author":"Brunner","year":"1993","journal-title":"Cancer Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e46078","DOI":"10.15252\/embr.201846078","article-title":"Splicing factor ESRP1 controls ER-positive breast cancer by altering metabolic pathways","volume":"20","author":"Neelamraju","year":"2019","journal-title":"EMBO Rep."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1146\/annurev-pathol-121808-102144","article-title":"The senescence-associated secretory phenotype: The dark side of tumor suppression","volume":"5","author":"Coppe","year":"2010","journal-title":"Annu. Rev. Pathol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/j.semcancer.2021.03.021","article-title":"Biological functions of therapy-induced senescence in cancer","volume":"81","author":"Fitsiou","year":"2022","journal-title":"Semin. Cancer Biol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"4253","DOI":"10.1038\/s41467-023-39817-3","article-title":"Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment","volume":"14","author":"Haake","year":"2023","journal-title":"Nat. Commun."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"979","DOI":"10.1038\/ncb3397","article-title":"NOTCH1 mediates a switch between two distinct secretomes during senescence","volume":"18","author":"Hoare","year":"2016","journal-title":"Nat. Cell Biol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1007\/978-3-319-89512-3_15","article-title":"Notch and Senescence","volume":"1066","author":"Hoare","year":"2018","journal-title":"Adv. Exp. Med. Biol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"820","DOI":"10.1016\/j.tcb.2017.07.004","article-title":"Spatial and Temporal Control of Senescence","volume":"27","author":"Ito","year":"2017","journal-title":"Trends Cell Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1840","DOI":"10.1038\/s41467-018-04283-9","article-title":"NOTCH-mediated non-cell autonomous regulation of chromatin structure during senescence","volume":"9","author":"Parry","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1083\/jcb.201206006","article-title":"p53-dependent release of Alarmin HMGB1 is a central mediator of senescent phenotypes","volume":"201","author":"Davalos","year":"2013","journal-title":"J. Cell Biol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1111\/hiv.12390","article-title":"High frequency of mitochondrial DNA mutations in HIV-infected treatment-experienced individuals","volume":"18","author":"Li","year":"2017","journal-title":"HIV Med."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Basisty, N., Kale, A., Jeon, O.H., Kuehnemann, C., Payne, T., Rao, C., Holtz, A., Shah, S., Sharma, V., and Ferrucci, L. (2020). A proteomic atlas of senescence-associated secretomes for aging biomarker development. PLoS Biol., 18.","DOI":"10.1371\/journal.pbio.3000599"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Kaur, G., and Roy, B. (2024). Decoding Tumor Angiogenesis for Therapeutic Advancements: Mechanistic Insights. Biomedicines, 12.","DOI":"10.3390\/biomedicines12040827"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"877","DOI":"10.1038\/ncb1448","article-title":"Plasminogen activator inhibitor-1 is a critical downstream target of p53 in the induction of replicative senescence","volume":"8","author":"Kortlever","year":"2006","journal-title":"Nat. Cell Biol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1825","DOI":"10.1016\/j.ejca.2013.01.007","article-title":"Ten-year analysis of the prospective multicentre Chemo-N0 trial validates American Society of Clinical Oncology (ASCO)-recommended biomarkers uPA and PAI-1 for therapy decision making in node-negative breast cancer patients","volume":"49","author":"Harbeck","year":"2013","journal-title":"Eur. J. Cancer"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5287","DOI":"10.1200\/JCO.2007.14.2364","article-title":"American Society of Clinical Oncology 2007 update of recommendations for the use of tumor markers in breast cancer","volume":"25","author":"Harris","year":"2007","journal-title":"J. Clin. Oncol."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Melzer, C., von der Ohe, J., Otterbein, H., Ungefroren, H., and Hass, R. (2019). Changes in uPA, PAI-1, and TGF-beta Production during Breast Cancer Cell Interaction with Human Mesenchymal Stroma\/Stem-Like Cells (MSC). Int. J. Mol. Sci., 20.","DOI":"10.3390\/ijms20112630"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1186\/s13058-014-0428-4","article-title":"uPA and PAI-1 as biomarkers in breast cancer: Validated for clinical use in level-of-evidence-1 studies","volume":"16","author":"Duffy","year":"2014","journal-title":"Breast Cancer Res."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2107","DOI":"10.1158\/1055-9965.EPI-06-0351","article-title":"Prognostic value of PAI1 in invasive breast cancer: Evidence that tumor-specific factors are more important than genetic variation in regulating PAI1 expression","volume":"15","author":"Sternlicht","year":"2006","journal-title":"Cancer Epidemiol. Biomark. Prev."},{"key":"ref_40","first-page":"1153","article-title":"Plasma plasminogen activator inhibitor-1 (PAI-1) levels in breast cancer\u2014Relationship with clinical outcome","volume":"34","author":"Ferroni","year":"2014","journal-title":"Anticancer Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"118324","DOI":"10.1016\/j.biopha.2025.118324","article-title":"Cellular senescence as a prognostic marker for predicting breast cancer progression in 2D and 3D organoid models","volume":"189","author":"Niro","year":"2025","journal-title":"Biomed. Pharmacother."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/s10522-024-10164-0","article-title":"GDF15\/MIC-1: A stress-induced immunosuppressive factor which promotes the aging process","volume":"26","author":"Salminen","year":"2024","journal-title":"Biogerontology"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1097\/CAD.0000000000001434","article-title":"Growth differentiation factor 15 is required for triple-negative breast cancer cell growth and chemoresistance","volume":"34","author":"He","year":"2023","journal-title":"Anticancer Drugs"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1508","DOI":"10.18632\/oncotarget.13649","article-title":"GDF15 contributes to radioresistance and cancer stemness of head and neck cancer by regulating cellular reactive oxygen species via a SMAD-associated signaling pathway","volume":"8","author":"Li","year":"2017","journal-title":"Oncotarget"},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Bellio, C., Emperador, M., Castellano, P., Gris-Oliver, A., Canals, F., Sanchez-Pla, A., Zamora, E., Arribas, J., Saura, C., and Serra, V. (2022). GDF15 Is an Eribulin Response Biomarker also Required for Survival of DTP Breast Cancer Cells. Cancers, 14.","DOI":"10.3390\/cancers14102562"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1038\/s41556-018-0249-2","article-title":"The dynamic nature of senescence in cancer","volume":"21","author":"Lee","year":"2019","journal-title":"Nat. Cell Biol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1038\/nature25167","article-title":"Senescence-associated reprogramming promotes cancer stemness","volume":"553","author":"Milanovic","year":"2018","journal-title":"Nature"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"112533","DOI":"10.1016\/j.celrep.2023.112533","article-title":"Resistance to mesenchymal reprogramming sustains clonal propagation in metastatic breast cancer","volume":"42","author":"Saini","year":"2023","journal-title":"Cell Rep."}],"container-title":["Biomolecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/1\/93\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T05:17:56Z","timestamp":1767849476000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/1\/93"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,6]]},"references-count":48,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["biom16010093"],"URL":"https:\/\/doi.org\/10.3390\/biom16010093","relation":{},"ISSN":["2218-273X"],"issn-type":[{"value":"2218-273X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,6]]}}}