Quantitative proteomic analysis of sphere-forming stem-like oral cancer cells

Abstract

IntroductionThe purpose of this study is to identify target proteins that may play important functional roles in oral cancer stem-like cells (CSCs) using mass spectrometry-based quantitative proteomics.MethodsSphere-formation assays were performed on highly invasive UM1 and lowly invasive UM2 oral cancer cell lines, which were derived from the same tongue squamous cell carcinoma, to enrich CSCs. Quantitative proteomic analysis of CSC-like and non-CSC UM1 cells was carried out using tandem mass tagging and two-dimensional liquid chromatography with Orbitrap mass spectrometry.ResultsCSC-like cancer cells were found to be present in the highly invasive UM1 cell line but absent in the lowly invasive UM2 cell line. Stem cell markers SOX2, OCT4, SOX9 and CD44 were up-regulated, whereas HIF-1 alpha and PGK-1 were down-regulated in CSC-like UM1 cells versus non-CSC UM1 cells. Quantitative proteomic analysis indicated that many proteins in cell cycle, metabolism, G protein signal transduction, translational elongation, development, and RNA splicing pathways were differentially expressed between the two cell phenotypes. Both CREB-1-binding protein (CBP) and phosphorylated CREB-1 were found to be significantly over-expressed in CSC-like UM1 cells.ConclusionsCSC-like cells can be enriched from the highly invasive UM1 oral cancer cell line but not from the lowly invasive UM2 oral cancer cell line. There are significant proteomic alterations between CSC-like and non-CSC UM1 cells. In particular, CBP and phosphorylated CREB-1 were significantly up-regulated in CSC-like UM1 cells versus non-CSC UM1 cells, suggesting that the CREB pathway is activated in the CSC-like cells.

Promotion of cell proliferation by the proto‐oncogene DEK enhances oral squamous cell carcinogenesis through field cancerization

“…ELP3 is induced by Wnt signaling and promotes SOX9 translation, which is necessary for maintenance of intestinal cancer stem cells , and SOX9 is upregulated in stem cell population in tongue SCC cells . Furthermore, ELP3 maintains genomic stability and regulates DNA replication and DNA repair by directly interacting with PCNA, which may also recruit the elongator complex to modulate chromatin structure during DNA replication or in response to DNA damage .…”

Cancer stem cells and oral cancer: insights into molecular mechanisms and therapeutic approaches

“…As such, tumor spheres extracted from OSCC cells show higher stem-like features. They show greater volume of expression of pluripotent transcription agents such as Lin28, Nanog, KLF4, Oct4, and Sox2 in comparison to the respective adherent mono-layer cells [26,60,70,71]. Moreover, influential expression of CSC specific markers, including CD44 and ALDH1 is expressed by oral tumor sphere-forming cells [60,61,72].…”

Current Cancer Stem Cell Biomarkers in Tongue Squamous Cell Carcinoma

“…CSCs were reported to be enriched in the highly invasive UM1 cell line which is strongly positive for CD44 expression but were not present in the less invasive UM2 cell line (Misuno et al 2013). In a recent study, where 4-Nitroquinoline 1-oxide was used to induce tongue cancer in mice, CD44 expression along with CD133 was found to be slightly overexpressed in dysplasia group compared to normal rats (Lim et al 2014).…”

“…On the other hand, sphereforming CSCs of UM1 cells were strongly positive for several stem cell factors including SOX2 and OCT4. Along with those markers, many proteins in cell cycle, metabolism, G protein signal transduction, translational elongation, development, and RNA splicing pathways were differentially expressed among the two cell phenotypes, which might be associated with elevated levels of stem cell factors like SOX2 and OCT4 (Misuno et al 2013).…”