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O38 COX-2 expression in oral squamous cell carcinomas and premalignant mucosa lesions
Oral and Symposium abstracts, Friday 18 May
Epigenetic changes have been implicated in the pathogenesis of solid tumors, including head and neck squamous cell carcinoma (HNSCC). Prior efforts have primarily examined regional promoter hypermethylation as a silencer of tumor suppressor gene expression. To analyze the global state of methylation in the HNSCC genome, we utilize pyrosequencing of repetitive elements (LINEs) to compare the state of global methylation in HNSCC to normal aerodigestive mucosa. 137 samples (119 HNSCC tumors and 18 normal mucosal tissues) were digested to extract DNA and samples were subjected to bisulfite treatment. Treated DNA was amplified using PCR primers for the repetitive LINEs sequence and produced a heterogeneous sample of products, from many genomic loci. These products were pyrosequenced in order to quantitatively evaluate their global genomic methylation status. HNSC specimens showed global hypomethylation, with a mean level of genomic methylation of 46.5 percent methylated with a standard deviation of 8.8. Conversely, the normal upper airway mucosa had a global methylation level of 54.1 and a standard deviation of 4.8 (Mann-Whitney p value <0.001). The tumor specimens also showed an increasing degree of hypomethylation associated with advanced tumor stage (ANOVA p-value of 0.003). 67% of HNSCC’s are globally hypomethylated when evaluated against the minimum level of methylation in the normal mucosal specimens. Degree of global hypomethylation was associated with smoking history (p-value 0.01). Despite the presence and established role of regional promoter hypermethylation, HNSCC demonstrates global genomic hypomethylation. The association between hypomethylation and tumor stage suggests that while individual gene loci may demonstrate hypermethylation and gene silencing, methylation diminishes across the genome as a whole in head and neck tumors. The degree of global hypomethylation was affected by smoking status indicating a possible role of global hypomethylation in smoking-induced cancer. Keywords: hypomethylation, global methylome, smoking
was shown in the neoadjuvant group. In premalignant lesions only dysplasias and carcinoma in situ were positive for COX-2. COX-2 expression may be involved in oral carcinogenesis has a predictive as well as prognostic value in oral cancer. Further in vitro studies revealed an additive effect of celecoxib and cisplation on oral cancer cells. Prospective controlled trials dealing with adjuvant short term treatment of oral cancer patients with selective COX-2 inhibitors and RCT will be needed. Keywords: COX-2, neoadjuvant, premalignant, prognosis O39 Rare narrow amplicons in oral cancers and pre-cancers A. Snijders *, A. Bhattacharya, N. Dekker, R. Jordan, B. Schmidt, D. Albertson. University of California, United States Genomes of solid tumors are characterized by gains and losses of regions, which may contribute to tumorigenesis by altering gene expression. We have previously reported that genome wide scanning of oral squamous cell carcinoma by array comparative genomic hybridization (array CGH) revealed that ~40% of oral SCCs harbor narrow regions of gene amplification. The amplicons are recurrent, but relatively rare, occurring in 2 5% of cases. For many, the minimum common amplified regions are <3 Mb, facilitating identification of the driver genes. We have found genes involved in integrin signaling (TLN1), survival (YAP1, BIRC2), and adhesion and migration (TLN1, LAMA3, MMP7), as well as members of the hedgehog (GLI2) and notch (JAG1, RBPSUH, FJX1) pathways to be amplified and over-expressed. Here, we report that some of these and other narrow amplicons are found in ~20% of oral dysplasia. The amplicons were observed in all grades. These observations suggest that deregulation of genes mapping to these amplicons, and other members of the pathways in which they participate are involved in oral SCC development from the earliest precancerous stages. Keywords: array CGH, amplicon, cancer, dysplasia O40 Determination of the global gene expression profile of oral cancers using paraffin-embedded tissues
O38 COX-2 expression in oral squamous cell carcinomas and premalignant mucosa lesions M. Scheer *, U. Drebber, M. Kum, I. Ensmann, K. Petmecky, J.E. Z¨ oller. University of Cologne, Germany
A. Saleh1,2 *, R.B. Zain2 , H. Hussaini3 , M.T. Abraham4 , S. Hamid1 , S.-H. Teo1 , S.C. Cheong1 . 1 Cancer Research Initiatives Foundation (CARIF), Malaysia, 2 University Malaya, Malaysia, 3 National University of Malaysia, Malaysia, 4 Tengku Ampuan Rahimah Hospital, Malaysia
The enzyme cyclooxygenase-2 (COX-2) is expressed primarily in pathologic states like inflammatory disorders and cancer mediating prostaglandin synthesis. The aim of our study was to investigate the prognostic relevance of COX-2 expression in oral squamous cell carcinomas. COX-2 immunostaining was analysed in 78 biopsies from patients with stage I-IV carcinomas who underwent preoperative radiochemotherapy (RCT) with 39.8 Gy and carboplatin. Additionally COX-2 status was assessed in 87 consecutive patients who were treated by curative intended surgery alone. Premalignant lesions from 42 patients with dysplasias and leukoplakias were analysed for COX-2 expression to. Prognostic impact of tumor size, grading, lymph node involvement, response to RCT in the neoadjuvant group, lymph node involvement as well as tumor free and overall survival were calculated according to Kaplan Meier analysis. COX-2 immunostaining was calculated by a semiquantitative grading system (0 zero reactivity to IV 75 100% positive tumor cells). The preliminary results showed a reduction for overall survival and tumor free survival for high COX-2 immunoreactivity (IIIIV). A slight influence of COX-2 expression and response to RCT
Introduction: Oral cancer is a common disease in Asia. However, our ability to deliver effective and targeted therapy remains limited by our lack of understanding of the molecular pathogenesis of oral carcinogenesis. One method to understand the nature of genes and gene products whose aberrant expression promote malignant transformation is by using microarrays. However, such studies have been limited by the availability of specimens with intact RNA and adequate clinical data to enable the identification and validation biomarkers either as predictive or therapeutic tools. Objective: We have determined the global gene expression profiles of oral squamous cell carcinoma (OSCC) of the buccal mucosa using formalin fixed paraffin-embedded specimens. Materials and Methods: Gene expression analyses using the DASL Assay were performed on 34 paraffin embedded tissues, of which 22 samples were OSCC of the buccal mucosa and 12 samples were normal surface epithelium of reactive lesions such as the fibroepithelial polyp from matched site. We used the Illumina Beadstudio Software to compare the expression profiles of normal and OSCC samples. We selected genes which were differentially expressed by at least two-fold (with the detection p-value <0.01) for further analysis.
Oral abstracts
O37 DNA global hypomethylation in squamous cell head and neck cancer associated with smoking I. Smith *, S. Mithani, J. Califano. Johns Hopkins, United States
65
Epigenetic changes have been implicated in the pathogenesis of solid tumors, including head and neck squamous cell carcinoma (HNSCC). Prior efforts have primarily examined regional promoter hypermethylation as a silencer of tumor suppressor gene expression. To analyze the global state of methylation in the HNSCC genome, we utilize pyrosequencing of repetitive elements (LINEs) to compare the state of global methylation in HNSCC to normal aerodigestive mucosa. 137 samples (119 HNSCC tumors and 18 normal mucosal tissues) were digested to extract DNA and samples were subjected to bisulfite treatment. Treated DNA was amplified using PCR primers for the repetitive LINEs sequence and produced a heterogeneous sample of products, from many genomic loci. These products were pyrosequenced in order to quantitatively evaluate their global genomic methylation status. HNSC specimens showed global hypomethylation, with a mean level of genomic methylation of 46.5 percent methylated with a standard deviation of 8.8. Conversely, the normal upper airway mucosa had a global methylation level of 54.1 and a standard deviation of 4.8 (Mann-Whitney p value <0.001). The tumor specimens also showed an increasing degree of hypomethylation associated with advanced tumor stage (ANOVA p-value of 0.003). 67% of HNSCC’s are globally hypomethylated when evaluated against the minimum level of methylation in the normal mucosal specimens. Degree of global hypomethylation was associated with smoking history (p-value 0.01). Despite the presence and established role of regional promoter hypermethylation, HNSCC demonstrates global genomic hypomethylation. The association between hypomethylation and tumor stage suggests that while individual gene loci may demonstrate hypermethylation and gene silencing, methylation diminishes across the genome as a whole in head and neck tumors. The degree of global hypomethylation was affected by smoking status indicating a possible role of global hypomethylation in smoking-induced cancer. Keywords: hypomethylation, global methylome, smoking
was shown in the neoadjuvant group. In premalignant lesions only dysplasias and carcinoma in situ were positive for COX-2. COX-2 expression may be involved in oral carcinogenesis has a predictive as well as prognostic value in oral cancer. Further in vitro studies revealed an additive effect of celecoxib and cisplation on oral cancer cells. Prospective controlled trials dealing with adjuvant short term treatment of oral cancer patients with selective COX-2 inhibitors and RCT will be needed. Keywords: COX-2, neoadjuvant, premalignant, prognosis O39 Rare narrow amplicons in oral cancers and pre-cancers A. Snijders *, A. Bhattacharya, N. Dekker, R. Jordan, B. Schmidt, D. Albertson. University of California, United States Genomes of solid tumors are characterized by gains and losses of regions, which may contribute to tumorigenesis by altering gene expression. We have previously reported that genome wide scanning of oral squamous cell carcinoma by array comparative genomic hybridization (array CGH) revealed that ~40% of oral SCCs harbor narrow regions of gene amplification. The amplicons are recurrent, but relatively rare, occurring in 2 5% of cases. For many, the minimum common amplified regions are <3 Mb, facilitating identification of the driver genes. We have found genes involved in integrin signaling (TLN1), survival (YAP1, BIRC2), and adhesion and migration (TLN1, LAMA3, MMP7), as well as members of the hedgehog (GLI2) and notch (JAG1, RBPSUH, FJX1) pathways to be amplified and over-expressed. Here, we report that some of these and other narrow amplicons are found in ~20% of oral dysplasia. The amplicons were observed in all grades. These observations suggest that deregulation of genes mapping to these amplicons, and other members of the pathways in which they participate are involved in oral SCC development from the earliest precancerous stages. Keywords: array CGH, amplicon, cancer, dysplasia O40 Determination of the global gene expression profile of oral cancers using paraffin-embedded tissues
O38 COX-2 expression in oral squamous cell carcinomas and premalignant mucosa lesions M. Scheer *, U. Drebber, M. Kum, I. Ensmann, K. Petmecky, J.E. Z¨ oller. University of Cologne, Germany
A. Saleh1,2 *, R.B. Zain2 , H. Hussaini3 , M.T. Abraham4 , S. Hamid1 , S.-H. Teo1 , S.C. Cheong1 . 1 Cancer Research Initiatives Foundation (CARIF), Malaysia, 2 University Malaya, Malaysia, 3 National University of Malaysia, Malaysia, 4 Tengku Ampuan Rahimah Hospital, Malaysia
The enzyme cyclooxygenase-2 (COX-2) is expressed primarily in pathologic states like inflammatory disorders and cancer mediating prostaglandin synthesis. The aim of our study was to investigate the prognostic relevance of COX-2 expression in oral squamous cell carcinomas. COX-2 immunostaining was analysed in 78 biopsies from patients with stage I-IV carcinomas who underwent preoperative radiochemotherapy (RCT) with 39.8 Gy and carboplatin. Additionally COX-2 status was assessed in 87 consecutive patients who were treated by curative intended surgery alone. Premalignant lesions from 42 patients with dysplasias and leukoplakias were analysed for COX-2 expression to. Prognostic impact of tumor size, grading, lymph node involvement, response to RCT in the neoadjuvant group, lymph node involvement as well as tumor free and overall survival were calculated according to Kaplan Meier analysis. COX-2 immunostaining was calculated by a semiquantitative grading system (0 zero reactivity to IV 75 100% positive tumor cells). The preliminary results showed a reduction for overall survival and tumor free survival for high COX-2 immunoreactivity (IIIIV). A slight influence of COX-2 expression and response to RCT
Introduction: Oral cancer is a common disease in Asia. However, our ability to deliver effective and targeted therapy remains limited by our lack of understanding of the molecular pathogenesis of oral carcinogenesis. One method to understand the nature of genes and gene products whose aberrant expression promote malignant transformation is by using microarrays. However, such studies have been limited by the availability of specimens with intact RNA and adequate clinical data to enable the identification and validation biomarkers either as predictive or therapeutic tools. Objective: We have determined the global gene expression profiles of oral squamous cell carcinoma (OSCC) of the buccal mucosa using formalin fixed paraffin-embedded specimens. Materials and Methods: Gene expression analyses using the DASL Assay were performed on 34 paraffin embedded tissues, of which 22 samples were OSCC of the buccal mucosa and 12 samples were normal surface epithelium of reactive lesions such as the fibroepithelial polyp from matched site. We used the Illumina Beadstudio Software to compare the expression profiles of normal and OSCC samples. We selected genes which were differentially expressed by at least two-fold (with the detection p-value <0.01) for further analysis.
Oral abstracts
O37 DNA global hypomethylation in squamous cell head and neck cancer associated with smoking I. Smith *, S. Mithani, J. Califano. Johns Hopkins, United States
65