title: RANK Ligand Modulation of Autophagy in Oral Squamous Cell Carcinoma Tumor Cells.
abstract: Autophagy is a cellular process to recycle nutrients and has been implicated in cancer treatment. Oral squamous cell carcinoma (OSCC) is the most common oral cancer which ranks 3% of cancers in men and 2% in women. In this study, immunohistochemical staining of OSCC tumor specimens from human subjects and an athymic mouse model demonstrated high levels of autophagy markers LC3-II and ATG5 expression. Further, we identified high levels LC3-II expression in OSCC tumor cell lines (SCC-1, SCC-12, and SCC-14a) compared to normal human epithelial (RWPE-1) cells. OSCC cells express high levels of RANK ligand (RANKL); however, a functional role in autophagy is unknown. Interestingly, RANKL stimulation significantly increased autophagosome-related gene expressions such as LC3, ATG5, BECN1, and PI3KC3 mRNA expression in OSCC cells. Further, Western blot analysis of total cell lysates demonstrated a dose-dependent increase in LC3-II and ATG5 expression in RANKL-stimulated cells. In addition, RANKL increased expression of LC3-I and LC3-II, essential for autophagosome formation. Confocal microscopy analysis of LC3-II and localization with lysosome further confirms autophagosome formation in response to RANKL treatment in OSCC cells. Collectively, our results indicate a novel function of RANKL to induce autophagosome formation, and could be a potential therapeutic target to control OSCC tumor progression.
authors.affiliation: Darby Children's Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425.
authors.forename: Yuvaraj
authors.initials: Y
authors.lastname: Sambandam
authors.affiliation: Department of Microbiology and Immunology and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, 29425.
authors.forename: Sashank
authors.initials: S
authors.lastname: Sakamuri
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, South Carolina, 29425.
authors.forename: Sundaravadivel
authors.initials: S
authors.lastname: Balasubramanian
authors.affiliation: Department of Microbiology and Immunology and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, 29425.
authors.forename: Azizul
authors.initials: A
authors.lastname: Haque
mesh_terms: D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D000071187:Autophagy-Related Protein 5 / Q000235:genetics / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D066298:In Vitro Techniques; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009062:Mouth Neoplasms / Q000378:metabolism*; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C502778:ATG5 protein, human; D000071187:Autophagy-Related Protein 5; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D053245:RANK Ligand
keywords: ATG5; AUTOPHAGOSOME; LC3; ORAL SQUAMOUS CELL CARCINOMA (OSCC); RANK LIGAND