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Open AccessArticle

Simulated Microgravity Influences VEGF, MAPK, and PAM Signaling in Prostate Cancer Cells

Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark
Clinic for Plastic, Aesthetic and Hand Surgery, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
Department of Ophthalmology, Aarhus University Hospital, 8200 Aarhus N, Denmark
Research Group “Magdeburger Arbeitsgemeinschaft für Forschung unter Raumfahrt-und Schwerelosigkeitsbedingungen” (MARS), Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
Diabetes and Hormone Diseases—Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, 8200 Aarhus N, Denmark
Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
Institute for Pathology, University of Regensburg, 95053 Regensburg, Germany
Department of Microgravity and Translational Regenerative Medicine, Otto von Guericke University, Pfälzer Platz, 39106 Magdeburg, Germany
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2020, 21(4), 1263; (registering DOI)
Received: 23 November 2019 / Revised: 31 January 2020 / Accepted: 11 February 2020 / Published: 13 February 2020
Prostate cancer is one of the leading causes of cancer mortality in men worldwide. An unusual but unique environment for studying tumor cell processes is provided by microgravity, either in space or simulated by ground-based devices like a random positioning machine (RPM). In this study, prostate adenocarcinoma-derived PC-3 cells were cultivated on an RPM for time periods of 3 and 5 days. We investigated the genes associated with the cytoskeleton, focal adhesions, extracellular matrix, growth, survival, angiogenesis, and metastasis. The gene expression of signaling factors of the vascular endothelial growth factor (VEGF), mitogen-activated protein kinase (MAPK), and PI3K/AKT/mTOR (PAM) pathways was investigated using qPCR. We performed immunofluorescence to study the cytoskeleton, histological staining to examine the morphology, and a time-resolved immunofluorometric assay to analyze the cell culture supernatants. When PC-3 cells were exposed to simulated microgravity (s-µg), some cells remained growing as adherent cells (AD), while most cells detached from the cell culture flask bottom and formed multicellular spheroids (MCS). After 3-day RPM exposure, PC-3 cells revealed significant downregulation of the VEGF, SRC1, AKT, MTOR, and COL1A1 gene expression in MCS, whereas FLT1, RAF1, MEK1, ERK1, FAK1, RICTOR, ACTB, TUBB, and TLN1 mRNAs were not significantly changed. ERK2 and TLN1 were elevated in AD, and FLK1, LAMA3, COL4A5, FN1, VCL, CDH1, and NGAL mRNAs were significantly upregulated in AD and MCS after 3 days. After a 5-day culture in s-µg, the PC-3 cells showed significant downregulations of VEGF mRNA in AD and MCS, and FN1, CDH1, and LAMA3 in AD and SCR1 in MCS. In addition, we measured significant upregulations in FLT1, AKT, ERK1, ERK2, LCN2, COL1A1, TUBB, and VCL mRNAs in AD and MCS, and increases in FLK1, FN1, and COL4A5 in MCS as well as LAMB2, CDH1, RAF1, MEK1, SRC1, and MTOR mRNAs in AD. FAK1 and RICTOR were not altered by s-µg. In parallel, the secretion rate of VEGFA and NGAL proteins decreased. Cytoskeletal alterations (F-actin) were visible, as well as a deposition of collagen in the MCS. In conclusion, RPM-exposure of PC-3 cells induced changes in their morphology, cytoskeleton, and extracellular matrix protein synthesis, as well as in their focal adhesion complex and growth behavior. The significant upregulation of genes belonging to the PAM pathway indicated their involvement in the cellular changes occurring in microgravity.
Keywords: microgravity; prostate cancer; VEGF signaling; cytoskeleton; focal adhesion; extracellular matrix microgravity; prostate cancer; VEGF signaling; cytoskeleton; focal adhesion; extracellular matrix
MDPI and ACS Style

Hybel, T.E.; Dietrichs, D.; Sahana, J.; Corydon, T.J.; Nassef, M.Z.; Wehland, M.; Krüger, M.; Magnusson, N.E.; Bauer, J.; Utpatel, K.; Infanger, M.; Grimm, D.; Kopp, S. Simulated Microgravity Influences VEGF, MAPK, and PAM Signaling in Prostate Cancer Cells. Int. J. Mol. Sci. 2020, 21, 1263.

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