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Elazezy M, Schwentesius S, Stegat L, Wikman H, Werner S, Mansour WY, Failla AV, Peine S, Müller V, Thiery JP, Ebrahimi Warkiani M, Pantel K, Joosse SA. Emerging Insights into Keratin 16 Expression during Metastatic Progression of Breast Cancer. Cancers (Basel) 2021; 13:cancers13153869. [PMID: 34359774 PMCID: PMC8345379 DOI: 10.3390/cancers13153869] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/25/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary The mechanisms leading to tumor metastasis remain poorly understood, and therefore, phenotyping of circulating tumor cells from cancer patients may contribute to translating these mechanisms. In in silico analysis, high expression of keratin 16 was associated with higher tumor aggressiveness. According to our results, keratin 16 is a metastasis-associated protein that promotes EMT and acts as a positive regulator of cellular motility by reorganizing the actin cytoskeleton, which is the driving force behind disrupting intercellular adhesion and directional migration. In metastatic breast cancer patients, circulating tumor cells expressing keratin 16 were associated with shorter relapse-free survival. This is an important issue for future research to determine the exact function of keratin 16 in tumor dissemination and metastasis development by analyzing keratin 16 status in disseminating tumor cells. Furthermore, gaining a better knowledge of keratin 16’s biology would give crucial mechanistic insights that might lead to a unique treatment option. Abstract Keratins are the main identification markers of circulating tumor cells (CTCs); however, whether their deregulation is associated with the metastatic process is largely unknown. Previously we have shown by in silico analysis that keratin 16 (KRT16) mRNA upregulation might be associated with more aggressive cancer. Therefore, in this study, we investigated the biological role and the clinical relevance of K16 in metastatic breast cancer. By performing RT-qPCR, western blot, and immunocytochemistry, we investigated the expression patterns of K16 in metastatic breast cancer cell lines and evaluated the clinical relevance of K16 expression in CTCs of 20 metastatic breast cancer patients. High K16 protein expression was associated with an intermediate mesenchymal phenotype. Functional studies showed that K16 has a regulatory effect on EMT and overexpression of K16 significantly enhanced cell motility (p < 0.001). In metastatic breast cancer patients, 64.7% of the detected CTCs expressed K16, which was associated with shorter relapse-free survival (p = 0.0042). Our findings imply that K16 is a metastasis-associated protein that promotes EMT and acts as a positive regulator of cellular motility. Furthermore, determining K16 status in CTCs provides prognostic information that helps to identify patients whose tumors are more prone to metastasize.
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Affiliation(s)
- Maha Elazezy
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Sandra Schwentesius
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Luisa Stegat
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Harriet Wikman
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Stefan Werner
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Wael Y. Mansour
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Antonio Virgilio Failla
- UKE Microscopy Imaging Facility (UMIF), University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Sven Peine
- Department of Transfusion Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Volkmar Müller
- Department of Gynecology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
| | - Jean Paul Thiery
- Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou 510320, China;
| | | | - Klaus Pantel
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
| | - Simon A. Joosse
- Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; (M.E.); (S.S.); (L.S.); (H.W.); (S.W.); (K.P.)
- Correspondence: ; Tel.: +49-(0)-40-7410-51970
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