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Proteomic Study of Oral Cancer Stem-Like Cells and Bone Marrow Cell Treatment for Sjögren's Syndrome

  • Author(s): Misuno, Kaori
  • Advisor(s): Hu, Shen
  • et al.
Abstract

Cancer stem cells (CSCs) are a small subset of cancer cells which have stem cell-like characteristics of self-renewal and differentiation [1, 2]. They have been identified from cultured cells based on the use of stem cell markers and also by their ability to form sphererogenic cellular aggregates in cell culture [3]. The presence of CSCs has been reported in oral squamous cell carcinoma (OSCC), however little is known about the underlying molecular events in the oral CSCs. Therefore, the objective of my first study is to isolate oral CSCs from cultured oral cancer cells and to identify activated signaling pathways and target proteins in oral CSCs using a quantitative proteomic approach. We have successfully isolated CSCs from UM1 cells using sphere formation assay, and confirmed the over-expression of stem cell markers including OCT4, SOX2, CD44, and SOX9. Quantitative proteomic analysis of CSCs and non-stem cells (NSCs) was performed using tandem mass tagging (TMT) and LC-MS/MS. In total, more than 900 proteins were quantified and ~ 350 proteins were differentially expressed (>1.2 fold change) between CSCs and NSCs, including transcription factors, stem cell markers, G proteins, and regulatory proteins involved in stem cell renewal/differentiation. In particular, we found CREB-binding proteins and phosphorylated CREB-1 were significantly over-expressed in the CSCs, suggesting CREB pathway is activated in the oral CSCs.

In the second study we conducted a quantitative proteomic analysis of the submandibular tissues from non-obese diabetic mice (NOD) treated with bone marrow cell extract (BMCE). NOD mice are often used as an animal model for studying Sjögren's syndrome (SS) which is a systemic autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands, in particular the salivary and lachrymal glands [4]. Currently, there are no treatments that completely reverse the symptoms in the SS patients. However, cell-based therapy has emerged as a promising approach to treat salivary gland dysfunction in SS mouse models, although little is known the underlying molecular mechanisms [5]. Therefore, my second study was focused on understanding the proteomic changes in the salivary glands of NOD mice associated with BMCE treatment. Using TMT labeling and LC-MS/MS, we found the up-regulation of salivary gland proteins and stem cell markers as well as the down-regulation of proteins involved in apoptosis and inflammation. These results suggest that BMCE stimulates the regeneration of salivary gland cells and suppresses the inflammation and apoptotic activity in salivary glands of NOD mice

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