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Development","award":["10.13039\/501100014188"],"award-info":[{"award-number":["10.13039\/501100014188"]}]},{"name":"Encouragement Program for Technology Development","award":["2710018369"],"award-info":[{"award-number":["2710018369"]}]},{"name":"Encouragement Program for Technology Development","award":["RS-2024-00438316"],"award-info":[{"award-number":["RS-2024-00438316"]}]},{"name":"Encouragement Program for Technology Development","award":["10.13039\/501100003052"],"award-info":[{"award-number":["10.13039\/501100003052"]}]},{"name":"Encouragement Program for Technology Development","award":["10.13039\/501100003662"],"award-info":[{"award-number":["10.13039\/501100003662"]}]},{"name":"Encouragement Program for Technology Development","award":["RS-2024-00410585"],"award-info":[{"award-number":["RS-2024-00410585"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Secreted Frizzled-related protein 4 (SFRP4) has been identified as a patient-level biomarker of the stem-like subtype of gastric cancer (GC), which is associated with poor prognosis and resistance to chemotherapy. Although multiple studies have documented the clinical significance of SFRP4 in GC, its mechanistic role in the stem-like subtype remains incompletely understood. In this study, we elucidate how phosphorylation of SFRP4 by protein kinase A (PKA) converts it into a Wnt signaling agonist. We began with a phosphoproteomic database search to identify candidate kinases that phosphorylate SFRP4. Co-immunoprecipitation assays revealed a direct interaction between PKA and SFRP4, and in vitro kinase assays confirmed that PKA phosphorylates SFRP4 at key threonine residues. Phosphorylated SFRP4 then associates with \u03b2-catenin, augmenting Wnt-driven transcriptional activity. Importantly, pharmacological inhibition of PKA significantly reduced SFRP4 phosphorylation and suppressed stemness-associated phenotypes, such as sphere formation, migratory capacity, and chemoresistance, in gastric cancer cells. Collectively, our data demonstrate that PKA-mediated phosphorylation of SFRP4 enhances cancer stemness-related properties in GC through Wnt signaling. Furthermore, these results highlight the PKA\u2013SFRP4 axis as a promising therapeutic target in the stem-like subtype of GC.<\/jats:p>","DOI":"10.3390\/ijms26125572","type":"journal-article","created":{"date-parts":[[2025,6,11]],"date-time":"2025-06-11T03:44:58Z","timestamp":1749613498000},"page":"5572","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["PKA-Mediated Phosphorylation of SFRP4 Promotes Wnt\/\u03b2-Catenin Activation and Cancer Stemness in Gastric Cancer"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0465-6309","authenticated-orcid":false,"given":"Yoo-Lim","family":"Jhe","sequence":"first","affiliation":[{"name":"Department of Medical Science, Graduate School, Yonsei University, Seoul 03722, Republic of Korea"},{"name":"Department of Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"},{"name":"Brain Korea 21 FOUR Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-1651-7517","authenticated-orcid":false,"given":"Suji","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youjin","family":"Jung","sequence":"additional","affiliation":[{"name":"Department of Medical Science, Graduate School, Yonsei University, Seoul 03722, Republic of Korea"},{"name":"Department of Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"},{"name":"Brain Korea 21 FOUR Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jae-Ho","family":"Cheong","sequence":"additional","affiliation":[{"name":"Department of Medical Science, Graduate School, Yonsei University, Seoul 03722, Republic of Korea"},{"name":"Department of Surgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"},{"name":"Brain Korea 21 FOUR Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"},{"name":"Department of Biomedical Systems Informatics, Yonsei University College of Medicine, Seoul 03722, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,6,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"209","DOI":"10.3322\/caac.21660","article-title":"Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries","volume":"71","author":"Sung","year":"2021","journal-title":"CA Cancer J. Clin."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1038\/nrc3261","article-title":"Intra-tumour heterogeneity: A looking glass for cancer?","volume":"12","author":"Marusyk","year":"2012","journal-title":"Nat. Rev. Cancer"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"554","DOI":"10.1053\/j.gastro.2013.05.010","article-title":"Identification of molecular subtypes of gastric cancer with different responses to PI3-kinase inhibitors and 5-fluorouracil","volume":"145","author":"Lei","year":"2013","journal-title":"Gastroenterology"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1038\/nature13480","article-title":"Comprehensive molecular characterization of gastric adenocarcinoma","volume":"513","year":"2014","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1038\/nm.3850","article-title":"Molecular analysis of gastric cancer identifies subtypes associated with distinct clinical outcomes","volume":"21","author":"Cristescu","year":"2015","journal-title":"Nat. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"629","DOI":"10.1016\/S1470-2045(18)30108-6","article-title":"Predictive test for chemotherapy response in resectable gastric cancer: A multi-cohort, retrospective analysis","volume":"19","author":"Cheong","year":"2018","journal-title":"Lancet Oncol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"235","DOI":"10.5230\/jgc.2019.19.e25","article-title":"Clinical Implementation of Precision Medicine in Gastric Cancer","volume":"19","author":"Jeon","year":"2019","journal-title":"J. Gastric Cancer"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e2217826120","DOI":"10.1073\/pnas.2217826120","article-title":"PHGDH preserves one-carbon cycle to confer metabolic plasticity in chemoresistant gastric cancer during nutrient stress","volume":"120","author":"Yoon","year":"2023","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1277","DOI":"10.1038\/s12276-023-01037-6","article-title":"Author Correction: Clinical molecular subtyping reveals intrinsic mesenchymal reprogramming in gastric cancer cells","volume":"55","author":"Jang","year":"2023","journal-title":"Exp. Mol. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e1805","DOI":"10.1038\/cddis.2015.171","article-title":"Metabolic stress induces a Wnt-dependent cancer stem cell-like state transition","volume":"6","author":"Lee","year":"2015","journal-title":"Cell Death Dis."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"MacDonald, B.T., and He, X. (2012). Frizzled and LRP5\/6 receptors for Wnt\/beta-catenin signaling. Cold Spring Harb. Perspect. Biol., 4.","DOI":"10.1101\/cshperspect.a007880"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.neuron.2005.02.023","article-title":"Frizzled 5 signaling governs the neural potential of progenitors in the developing Xenopus retina","volume":"46","author":"Moore","year":"2005","journal-title":"Neuron"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1101\/gad.1642408","article-title":"Tcf3 is an integral component of the core regulatory circuitry of embryonic stem cells","volume":"22","author":"Cole","year":"2008","journal-title":"Genes. Dev."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"7479","DOI":"10.1128\/MCB.00368-06","article-title":"Repression of Nanog gene transcription by Tcf3 limits embryonic stem cell self-renewal","volume":"26","author":"Pereira","year":"2006","journal-title":"Mol. Cell Biol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1124","DOI":"10.1158\/2159-8290.CD-19-0074","article-title":"beta-Catenin Activation Promotes Immune Escape and Resistance to Anti-PD-1 Therapy in Hepatocellular Carcinoma","volume":"9","author":"Bresnahan","year":"2019","journal-title":"Cancer Discov."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1007\/s10565-019-09502-7","article-title":"Temozolomide induces activation of Wnt\/beta-catenin signaling in glioma cells via PI3K\/Akt pathway: Implications in glioma therapy","volume":"36","author":"Tomar","year":"2020","journal-title":"Cell Biol. Toxicol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1111\/pcmr.12330","article-title":"Wnt5A promotes an adaptive, senescent-like stress response, while continuing to drive invasion in melanoma cells","volume":"28","author":"Webster","year":"2015","journal-title":"Pigment. Cell Melanoma Res."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Martin-Orozco, E., Sanchez-Fernandez, A., Ortiz-Parra, I., and Ayala-San Nicolas, M. (2019). WNT Signaling in Tumors: The Way to Evade Drugs and Immunity. Front. Immunol., 10.","DOI":"10.3389\/fimmu.2019.02854"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/S0092-8674(00)80324-4","article-title":"The mouse Fused locus encodes Axin, an inhibitor of the Wnt signaling pathway that regulates embryonic axis formation","volume":"90","author":"Zeng","year":"1997","journal-title":"Cell"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7469","DOI":"10.1038\/sj.onc.1210054","article-title":"Function and biological roles of the Dickkopf family of Wnt modulators","volume":"25","author":"Niehrs","year":"2006","journal-title":"Oncogene"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4374","DOI":"10.1074\/jbc.275.6.4374","article-title":"Secreted frizzled-related protein-1 binds directly to Wingless and is a biphasic modulator of Wnt signaling","volume":"275","author":"Uren","year":"2000","journal-title":"J. Biol. Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.1016\/j.celrep.2019.07.023","article-title":"SFRPs Are Biphasic Modulators of Wnt-Signaling-Elicited Cancer Stem Cell Properties beyond Extracellular Control","volume":"28","author":"Liang","year":"2019","journal-title":"Cell Rep."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1038\/ng1330","article-title":"Epigenetic inactivation of SFRP genes allows constitutive WNT signaling in colorectal cancer","volume":"36","author":"Suzuki","year":"2004","journal-title":"Nat. Genet."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Jacob, F., Ukegjini, K., Nixdorf, S., Ford, C.E., Olivier, J., Caduff, R., Scurry, J.P., Guertler, R., Hornung, D., and Mueller, R. (2012). Loss of secreted frizzled-related protein 4 correlates with an aggressive phenotype and predicts poor outcome in ovarian cancer patients. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0031885"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"336","DOI":"10.3892\/mmr.2021.11975","article-title":"Tumor suppressor role of sFRP-4 in hepatocellular carcinoma via the Wnt\/beta-catenin signaling pathway","volume":"23","author":"Wu","year":"2021","journal-title":"Mol. Med. Rep."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1007\/s10120-020-01143-8","article-title":"SFRP4 drives invasion in gastric cancer and is an early predictor of recurrence","volume":"24","author":"Busuttil","year":"2021","journal-title":"Gastric Cancer"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Vincent, K.M., and Postovit, L.M. (2017). A pan-cancer analysis of secreted Frizzled-related proteins: Re-examining their proposed tumour suppressive function. Sci. Rep., 7.","DOI":"10.1038\/srep42719"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"9063","DOI":"10.1128\/MCB.25.20.9063-9072.2005","article-title":"Phosphorylation of beta-catenin by cyclic AMP-dependent protein kinase stabilizes beta-catenin through inhibition of its ubiquitination","volume":"25","author":"Hino","year":"2005","journal-title":"Mol. Cell. Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1111\/j.1749-6632.2002.tb04324.x","article-title":"Dissecting the circuitry of protein kinase A and cAMP signaling in cancer genesis: Antisense, microarray, gene overexpression, and transcription factor decoy","volume":"968","author":"Nesterova","year":"2002","journal-title":"Ann. N. Y. Acad. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4223","DOI":"10.1093\/bioinformatics\/bty522","article-title":"Quokka: A comprehensive tool for rapid and accurate prediction of kinase family-specific phosphorylation sites in the human proteome","volume":"34","author":"Li","year":"2018","journal-title":"Bioinformatics"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.gpb.2020.01.001","article-title":"GPS 5.0: An Update on the Prediction of Kinase-specific Phosphorylation Sites in Proteins","volume":"18","author":"Wang","year":"2020","journal-title":"Genom. Proteom. Bioinform."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1039\/C1MB05340J","article-title":"Human Protein Reference Database and Human Proteinpedia as resources for phosphoproteome analysis","volume":"8","author":"Goel","year":"2012","journal-title":"Mol. Biosyst."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"5267","DOI":"10.1016\/S0021-9258(19)34116-X","article-title":"Inhibition of forskolin-induced neurite outgrowth and protein phosphorylation by a newly synthesized selective inhibitor of cyclic AMP-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), of PC12D pheochromocytoma cells","volume":"265","author":"Chijiwa","year":"1990","journal-title":"J. Biol. Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1038\/s41392-021-00701-5","article-title":"Wnt\/beta-catenin signaling in cancers and targeted therapies","volume":"6","author":"Yu","year":"2021","journal-title":"Signal Transduct. Target. Ther."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3288","DOI":"10.1038\/s41467-020-17139-y","article-title":"Integrated pharmaco-proteogenomics defines two subgroups in isocitrate dehydrogenase wild-type glioblastoma with prognostic and therapeutic opportunities","volume":"11","author":"Oh","year":"2020","journal-title":"Nat. Commun."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"913","DOI":"10.3390\/cancers3010913","article-title":"Protein kinase a in cancer","volume":"3","author":"Caretta","year":"2011","journal-title":"Cancers"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Riitano, G., Capozzi, A., Recalchi, S., Caissutti, D., Longo, A., Mattei, V., Conti, F., Misasi, R., Garofalo, T., and Sorice, M. (2022). Anti-beta2-GPI Antibodies Induce Endothelial Cell Expression of Tissue Factor by LRP6 Signal Transduction Pathway Involving Lipid Rafts. Cells, 11.","DOI":"10.3390\/cells11081288"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"6158","DOI":"10.1158\/1078-0432.CCR-20-1310","article-title":"Phase I and Biomarker Study of the Wnt Pathway Modulator DKN-01 in Combination with Gemcitabine\/Cisplatin in Advanced Biliary Tract Cancer","volume":"26","author":"Goyal","year":"2020","journal-title":"Clin. Cancer Res."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"460","DOI":"10.1111\/cpr.12270","article-title":"gamma-Tocotrienol reversal of epithelial-to-mesenchymal transition in human breast cancer cells is associated with inhibition of canonical Wnt signalling","volume":"49","author":"Ahmed","year":"2016","journal-title":"Cell Prolif."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/26\/12\/5572\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:49:47Z","timestamp":1760032187000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/26\/12\/5572"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,6,11]]},"references-count":39,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["ijms26125572"],"URL":"https:\/\/doi.org\/10.3390\/ijms26125572","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,6,11]]}}}