2384 XRCC5, a Potential Biomarker for Malignant Transformation of Submucous Fibrosis
H.-W. YANG, and Y.-F. HUANG, Chung Shan Medical University, Taichung, Taiwan

Objectives: Oral submucous fibrosis is a high-risk condition of oral mucosa for malignant transformation. In this study, we compared the gene expression patterns in patients who had oral submucous fibrosis (OSF) to those who had squamous cell carcinoma (SCC) with existing OSF by microarray analysis in an attempt to identify potential candidate genes associated with malignant transformation of OSF.

Methods: Five (5) patients with clinically-evident OSF, 5 patients with SCC who also had existing OSF, and 4 normal volunteers who did not have a history of chewing betel quids were recruited. Specimens were obtained with an approved IRB protocol. Total RNA from OSF or SCC was isolated and hybridized to Human Oligo 1A (V2) Microarray (G4110B) chip against normal control pooled from the 4 healthy volunteers.

Results: All microarray hybridizations were performed in duplicate. We found 1015 genes that had expression ratio either > 1.5 or < 0.67 in at least 50% of the experiments. A hierarchical clustering analysis showed 4 major groups of genes that discriminate OSF from SCC. Among these genes, twenty-four known genes (23 up-regulated and 1 down-regulated in OSF) were differentially expressed consistently in all cases. The expression of the down-regulated gene, XRCC5/Ku80, was confirmed by quantitative RT-PCR. Immunhohistochemistry showed decreased staining of XRCC5/Ku80 in tumor nests in 6 of 7 cases of well differentiated oral SCC.

Conclusions: Our microarray analysis showed that OSF demonstrated a distinct but similar gene expression signature comparing to SCC. Among those, XRCC5/ku80 may serve as a potential biomarker to predict the malignant transformation of OSF.

Seq #240 - Premalignant Oral Lesions and Oral Cancer
3:30 PM-4:45 PM, Friday, March 23, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J

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