Epigenetic Profiling of Cancer Stem Cells (CSC) in Head and Neck Squamous Cell Carcinoma (HNSCC)
HH Zhang, A Stone, SA Schichman, BR Smoller, JY Suen, CY Fan. John L. McClellan Memorial Veterans Hospital and UAMS, Little Rock, AR; John L. McClellan Memorial Veterans Hospital, Little Rock, AR; University of Arkansas for Medical Sciences, Little Rock, AR
Background: A small population of pluripotent CSCs with strong self-renewal capacity will survive most forms of chemoradiation therapies. Current chemoradiation therapy regimens for HNSCC may selectively kill the differentiated cancer cells, producing tumor regression while sparing a very small population of cancer stem cells, leading to tumor regrowth and relapse. Molecular characteristics for HNSCC CSCs are poorly understood, which prohibits design of more effective anticancer therapies, specifically targeting the CSCs.
Design: CSCs were isolated in 5 HNSCC lines (HEp2, MDA1986, SQ-20B, T409, TU167) using CD44 fluorescent antibody with flowcytometric sorting. Total RNA was extracted from both CD44+ CSCs and CD44- non-SC from 5 HNSCC lines for stemness genes (CD44, BMI-1, TERT, SALL4 and ABCG) expression. Genomic DNA was extracted from both CD44+ CSCs and CD44- non-SC from 5 HNSCC lines for epigenetic profiling using Illumina BeadArray (Human Methylation27), representing a total of 14,956 genes and for pathway analysis using ArrayTrack software.
Results: CD44+ CSCs expressed significantly higher levels of majority of stemness genes in all 5 HNSCC lines. With methylation of at least twice as much in CD44+ CSCs in most of the 5 HNSCC lines, we selected 22 genes that may be functionally very significant in head and neck CSCs. Cluster analysis using these 22 genes showed that CD44+ CSCs were epigenetically distinct from the CD44- Non-SCs in HNSCC. By ArrayTrack analysis, we further identified a group of 10 among 22 genes that are common in their metal ion binding capability. The difference in methylation pattern of these 10 genes in CSCs is statistically very significant (p = 0.0009) as compared to that seen in the non-SCs.
Conclusions: A small population of CD44+ CSCs was present in HNSCC that possess a unique epigenetic signature. The 10 genes identified by methylation microarray and ArrayTrack may be functionally significant in maintaining the stem cell property and thus could represent novel molecular targets for design and development of more effective anticancer therapies aiming specifically at these CSCs.
Category: Head & Neck
Tuesday, March 23, 2010 8:45 AM
Platform Session: Section G, Tuesday Morning