ABSTRACT
Glycosaminoglycans (GAGs) and proteoglycans (PGs) are major components of the glycocalyx. The secreted GAG and CD44 ligand hyaluronic acid (HA), and the cell surface PG syndecan-1 (Sdc-1) modulate the expression and activity of cytokines, chemokines, growth factors, and adhesion molecules, acting as critical regulators of tumor cell behavior. Here, we studied the effect of Sdc-1 siRNA depletion and HA treatment on hallmark processes of cancer in breast cancer cell lines of different levels of aggressiveness. We analyzed HA synthesis, and parameters relevant to tumor progression, including the stem cell phenotype, Wnt signaling constituents, cell cycle progression and apoptosis, and angiogenic markers in luminal MCF-7 and triple-negative MDA-MB-231 cells. Sdc-1 knockdown enhanced HAS-2 synthesis and HA binding in MCF-7, but not in MDA-MB-231 cells. Sdc-1-depleted MDA-MB-231 cells showed a reduced CD24-/CD44+ population. Furthermore, Sdc-1 depletion was associated with survival signals in both cell lines, affecting cell cycle progression and apoptosis evasion. These changes were linked to the altered expression of KLF4, MSI2, and miR-10b and differential changes in Erk, Akt, and PTEN signaling. We conclude that Sdc-1 knockdown differentially affects HA metabolism in luminal and triple-negative breast cancer model cell lines and impacts the stem phenotype, cell survival, and angiogenic factors.
Subject(s)
Gene Expression Regulation, Neoplastic , Glycocalyx/metabolism , Hyaluronic Acid/metabolism , Syndecan-1/genetics , Triple Negative Breast Neoplasms/genetics , Wnt Signaling Pathway/genetics , Apoptosis/drug effects , Apoptosis/genetics , CD24 Antigen/genetics , CD24 Antigen/metabolism , Cell Cycle/drug effects , Cell Cycle/genetics , Cell Line, Tumor , Databases, Factual , Female , Glycocalyx/chemistry , Glycocalyx/drug effects , Humans , Hyaluronan Receptors/genetics , Hyaluronan Receptors/metabolism , Hyaluronan Synthases/genetics , Hyaluronan Synthases/metabolism , Hyaluronic Acid/pharmacology , Kruppel-Like Factor 4 , Kruppel-Like Transcription Factors/genetics , Kruppel-Like Transcription Factors/metabolism , MCF-7 Cells , MicroRNAs/genetics , MicroRNAs/metabolism , Mitogen-Activated Protein Kinase 1/genetics , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , PTEN Phosphohydrolase/genetics , PTEN Phosphohydrolase/metabolism , Protein Binding , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Survival Analysis , Syndecan-1/antagonists & inhibitors , Syndecan-1/metabolism , Triple Negative Breast Neoplasms/metabolism , Triple Negative Breast Neoplasms/mortality , Triple Negative Breast Neoplasms/pathologyABSTRACT
Vitreous alterations occur from early stages and continue through the normal aging, with gradual lamellae formation and the appearance of liquefied spaces, which eventually leads to complications, such as retinal tear, retinal detachment, and intravitreal hemorrhage. The aim of the present study was to investigate the expression of let-7 miRNA family in the vitreous and retina in newborn (1-3- day-old), young adult (2-month-old), and aging (12-month-old) rats, as well as their role as regulators of vitreous components. MicroRNAs are small, non-coding RNAs that post-transcriptionally regulate gene expression. Our results showed detection of all investigated let-7 isoforms (let-7a, let-7b, let-7c, let-7d, let-7e, let-7f and let-7i) in the retina and vitreous. Although most let-7 members were significantly upregulated in the vitreous during development, only let-7b, let-7c, and let-7e followed this same expression pattern in the retina. Let-7b and -7c increased in aging vitreous as well, and were expressed in vitro by Müller glial cells and their extracellular vesicles. Moreover, let-7 targeted hyaluronan synthase 2 (Has2) mRNA, a synthesizing enzyme of hyaluronan. These observations indicate that let-7 function is important during retina and vitreous development, and that isoforms of let-7 increased with aging, potentially modulating hyaluronan content.