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dc.contributor.advisorIwakuma, Tomoo
dc.contributor.advisorAlbertini, David F.
dc.contributor.authorIyer, Swathi Venkatraman
dc.date.accessioned2017-05-08T02:35:23Z
dc.date.available2017-05-08T02:35:23Z
dc.date.issued2016-05-31
dc.date.submitted2016
dc.identifier.otherhttp://dissertations.umi.com/ku:14513
dc.identifier.urihttp://hdl.handle.net/1808/23986
dc.description.abstractOsteosarcoma (OS) is the second leading cause of cancer-related death in children and young adults. Despite advances in the treatment for OS, the survival rate of high-grade OS has reached a plateau and remains at 50-80% for the past three decades due to its highly metastatic and drug resistant nature. However, the crucial players that regulate malignant properties of OS and the underlying mechanisms are unclear. Towards this goal we attempted to identify factors whose knockdown could overcome cell death and proliferation arrest induced by anchorage-independence, serum-free conditions, leading to sphere formation. Thus, we screened a human whole-genome shRNA library using SJSA-1 OS cells harboring poor sphere forming potential. This screening led to the identification of an uncharacterized gene, namely “transmembrane and immunoglobulin domain containing 3 (TMIGD3)”. Our in vitro and in vivo experiments successfully revealed that downregulation of TMIGD3 using two independent shRNAs significantly increased sphere formation, cell migration, tumor formation, and metastases of multiple OS cells. Interestingly, overexpression of TMIGD3 isoform1 (i1) significantly suppressed cell proliferation, sphere formation and tumor formation, whereas its isoform 3 (i3) sharing the C-terminal region with i1 failed to do so. Since the N-terminal region consisting of 117 amino acids of TMIGD3 i1 is shared with the N-terminal region of adenosine A3 receptor (A3AR), we also overexpressed A3AR in OS cells and found that A3AR overexpression suppressed proliferation, migration, and tumor formation of OS cells as well. These results suggest that the N-terminal region plays a crucial role in the suppression of OS malignancy. We furthermore found that TMIGD3 downregulation, similar to A3AR knockdown led to an increase in the activity of NF-κB, a well-characterized downstream signaling of A3AR. Subsequent knockdown of NF-κB in cells downregulated for TMIGD3 abrogated their enhanced malignant properties. Analysis of human OS tissues revealed low expression of both TMIGD3 and A3AR when compared to normal bone and lung tissues. Additionally, we questioned the role of TMIGD3 in influencing stem-like properties of OS, since TMIGD3 knockdown in OS cells increased sphere formation, a hallmark of stem-like properties in vitro. We found that downregulation of TMIGD3 increased stem cell transcription factor expression, tumor initiation potential, and activity of aldehyde dehydrogenase (ALDH). These data suggest the potential role of TMIGD3 as a novel regulator of stem-like properties of OS. In summary, our study identified TMIGD3 i1 and A3AR as novel suppressors of OS malignancy and suggests that signaling regulated by TMIGD3 i1 and A3AR could serve as a potential targets for treatment of high grade OS.
dc.format.extent170 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectPhysiology
dc.subjectOncology
dc.subjectMolecular biology
dc.subjectadenosine A3 receptor
dc.subjectanchorage-independent
dc.subjectgenome-wide screening
dc.subjectNF-κB
dc.subjectOsteosarcoma
dc.subjectTMIGD3
dc.titleROLES OF TMIGD3 AND A3AR IN SUPPRESSION OF OSTEOSARCOMA MALIGNANCY
dc.typeDissertation
dc.contributor.cmtememberAnant, Shrikant
dc.contributor.cmtememberBehbod, Fariba
dc.contributor.cmtememberCalvet, James P
dc.thesis.degreeDisciplineMolecular & Integrative Physiology
dc.thesis.degreeLevelPh.D.
dc.identifier.orcid
dc.rights.accessrightsopenAccess


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