Key tumor suppressor genes inactivated by "greater promoter" methylation and somatic mutations in head and neck cancer

Tumor suppressor genes (TSGs) are commonly inactivated by somatic mutation and/or promoter methylation; yet, recent high-throughput genomic studies have not identified key TSGs inactivated by both mechanisms. We pursued an integrated molecular analysis based on methylation binding domain sequencing (MBD-seq), 450K Methylation arrays, whole exome sequencing, and whole genome gene expression arrays in primary head and neck squamous cell carcinoma (HNSCC) tumors and matched uvulopalatopharyngoplasty tissue samples (UPPPs). We uncovered 186 downregulated genes harboring cancer specific promoter methylation including PAX1 and PAX5 and we identified 10 key tumor suppressor genes (GABRB3, HOXC12, PARP15, SLCO4C1, CDKN2A, PAX1, PIK3AP1, HOXC6, PLCB1, and ZIC4) inactivated by both promoter methylation and/or somatic mutation. Among the novel tumor suppressor genes discovered with dual mechanisms of inactivation, we found a high frequency of genomic and epigenomic alterations in the PAX gene family of transcription factors, which selectively impact canonical NOTCH and TP53 pathways to determine cell fate, cell survival, and genome maintenance. Our results highlight the importance of assessing TSGs at the genomic and epigenomic level to identify key pathways in HNSCC, deregulated by simultaneous promoter methylation and somatic mutations.

Transcervical ultrasonography is feasible to visualize and evaluate base of tongue cancers

Background

Base of tongue (BOT) is a difficult subsite to examine clinically and radiographically. Yet, anatomic delineation of the primary tumor site, its extension to adjacent sites or across midline, and endophytic vs. exophytic extent are important characteristics for staging and treatment planning. We hypothesized that ultrasound could be used to visualize and describe BOT tumors.

Methods

Transcervical ultrasound was performed using a standardized protocol in cases and controls. Cases had suspected or confirmed BOT malignancy. Controls were healthy individuals without known malignancy.

Results

100% of BOT tumors were visualized. On ultrasound BOT tumors were hypoechoic (90.9%) with irregular margins (95.5%). Ultrasound could be used to characterize adjacent site involvement, midline extent, and endophytic extent, and visualize the lingual artery. No tumors were suspected for controls.

Conclusions

Ultrasonography can be used to transcervically visualize BOT tumors and provides clinically relevant characteristics that may not otherwise be appreciable.

Clusterin is a gene-specific target of microRNA-21 in head and neck squamous cell carcinoma

PURPOSE

MicroRNA-21 (miRNA-21) has proto-oncogenic properties, although no miRNA-21-specific targets have been found in head and neck squamous cell carcinoma (HNSCC). Further study of miRNA-21 and its specific targets is essential to understanding HNSCC biology.

EXPERIMENTAL DESIGN

miRNA expression profiles of 10 HNSCCs and 10 normal mucosa samples were investigated using a custom miRNA microarray. Thirteen HNSCCs and five normal mucosa primary tissue specimens underwent mRNA expression microarray analysis. To identify miRNA-21 downstream targets, oral keratinocyte cells were subjected to microarray analysis after miRNA-21 transient transfection. miRNA and mRNA expression were validated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in a separate cohort of 16 HNSCCs and 15 normal mucosal samples. Microarray and bioinformatics analyses were integrated to identify potential gene targets. In vitro assays looked at the function and interaction of miRNA-21 and its specific gene targets.

RESULTS

miRNA-21 was upregulated in HNSCCs and stimulated cell growth. Integrated analyses identified Clusterin (CLU) as a potential miRNA-21 gene target. CLU was downregulated after forced expression of miRNA-21 in normal and HNSCC cell lines. The activity of a luciferase construct containing the 3'-untranslated region (UTR) of CLU was repressed by the ectopic expression of miRNA-21. CLU was also downregulated in primary HNSCCs and correlated with miRNA-21 overexpression. CLU variant 1 (CLU-1) was the predominant splice variant in HNSCCs and showed growth suppression function that was reversed by miRNA-21 overexpression.

CONCLUSIONS

CLU is a specific, functional target of oncogenic miRNA-21 in HNSCCs. CLU-1 isoform is the predominant growth-suppressive variant targeted by miRNA-21.

DNA copy number variations characterize benign and malignant thyroid tumors

CONTEXT

Fine-needle aspiration (FNA) is the best diagnostic tool for preoperative evaluation of thyroid nodules but is often inconclusive as a guide for surgical management.

OBJECTIVE

Our hypothesis was that thyroid tumor subtypes may show characteristic DNA copy number variation (CNV) patterns, which may further improve the preoperative classification.

DESIGN

Our study cohorts included benign follicular adenomas (FAs), classic papillary thyroid carcinomas (PTCs), and follicular variant PTCs (FVPTCs), the three subtypes most commonly associated with inconclusive preoperative cytopathology.

SETTING

Tissue and FNA samples were obtained at an academic tertiary referral center.

PATIENTS

Cases were identified that underwent partial or complete thyroidectomy for malignant or indeterminate thyroid lesions between 2000 and 2008 and had adequate snap-frozen tissue.

INTERVENTIONS

Pairs of tumor tissue and matching normal thyroid tissue-derived DNA were compared using 550K single-nucleotide polymorphism arrays.

MAIN OUTCOME MEASURE

Statistically significant differences in CNV patterns between tumor subtypes were identified.

RESULTS

Segmental amplifications in chromosomes (Ch) 7 and 12 were more common in FAs than in PTCs or FVPTCs. Additionally, a subset of FAs and FVPTCs showed deletions in Ch22. We identified the 5 CNV-associated genes best at discriminating between FAs and PTCs/FVPTCs, which correctly classified 90% of cases. These 5 Ch12 genes were validated by quantitative genomic PCR and gene expression array analyses on the same patient cohort. The 5-gene signature was then successfully validated against an independent test cohort of benign and malignant tumor samples. Finally, we performed a feasibility study on matched FA-derived intraoperative FNA samples and were able to correctly identify FAs harboring the Ch12 amplification signature, whereas FAs without amplification showed a normal Ch12 signature.

CONCLUSIONS

Thyroid tumor subtypes possess characteristic genomic profiles that may further our understanding of structural genetic changes in thyroid tumor subtypes and may lead to the development of new diagnostic biomarkers in FNA samples.

Objective assessment in residency-based training for transoral robotic surgery

OBJECTIVES/HYPOTHESIS

To develop a robotic surgery training regimen integrating objective skill assessment for otolaryngology and head and neck surgery trainees consisting of training modules of increasing complexity leading up to procedure-specific training. In particular, we investigated applications of such a training approach for surgical extirpation of oropharyngeal tumors via a transoral approach using the da Vinci robotic system.

STUDY DESIGN

Prospective blinded data collection and objective evaluation (Objective Structured Assessment of Technical Skills [OSATS]) of three distinct phases using the da Vinci robotic surgical system in an academic university medical engineering/computer science laboratory setting.

METHODS

Between September 2010 and July 2011, eight otolaryngology-head and neck surgery residents and four staff experts from an academic hospital participated in three distinct phases of robotic surgery training involving 1) robotic platform operational skills, 2) set up of the patient side system, and 3) a complete ex vivo surgical extirpation of an oropharyngeal tumor located in the base of tongue. Trainees performed multiple (four) approximately equally spaced training sessions in each stage of the training. In addition to trainees, baseline performance data were obtained for the experts. Each surgical stage was documented with motion and event data captured from the application programming interfaces of the da Vinci system, as well as separate video cameras as appropriate. All data were assessed using automated skill measures of task efficiency and correlated with structured assessment (OSATS and similar Likert scale) from three experts to assess expert and trainee differences and compute automated and expert assessed learning curves.

RESULTS

Our data show that such training results in an improved didactic robotic knowledge base and improved clinical efficiency with respect to the set up and console manipulation. Experts (e.g., average OSATS, 25; standard deviation [SD], 3.1; module 1, suturing) and trainees (average OSATS, 15.9; SD, 3.9; week 1) are well separated at the beginning of the training, and the separation reduces significantly (expert average OSATS, 27.6; SD, 2.7; trainee average OSATS, 24.2; SD, 6.8; module 3) at the conclusion of the training. Learning curves in each of the three stages show diminishing differences between the experts and trainees, which is also consistent with expert assessment. Subjective assessment by experts verified the clinical utility of the module 3 surgical environment, and a survey of trainees consistently rated the curriculum as very useful in progression to human operating room assistance.

CONCLUSIONS

Structured curricular robotic surgery training with objective assessment promises to reduce the overhead for mentors, allow detailed assessment of human-machine interface skills, and create customized training models for individualized training. This preliminary study verifies the utility of such training in improving human-machine operations skills (module 1), and operating room and surgical skills (modules 2 and 3). In contrast to current coarse measures of total operating time and subjective assessment of error for short mass training sessions, these methods may allow individual tasks to be removed from the trainee regimen when skill levels are within the standard deviation of the experts for these tasks, which can greatly enhance overall efficiency of the training regimen and allow time for additional and more complex training to be incorporated in the same time frame.

Abstract 723: Detection of TIMP3 promoter hypermethylation in salivary rinse as an independent predictor of local recurrence-free survival in head and neck cancer

Objective: To validate a panel of methylation-based salivary rinse biomarkers (P16, CCNA1, DCC, TIMP3, MGMT, DAPK, and MINT31) previously shown to be independently associated with poor overall survival and local recurrence in a larger, separate cohort of patients with head and neck squamous cell carcinoma (HNSCC). Methods: One hundred ninety-seven patients were included. All pre-treatment saliva DNA samples were evaluated for the methylation status of the gene promoters by quantitative methylation-specific PCR. The main outcome measures were overall survival, local recurrence-free survival and disease-free survival. Results: In univariate analyses, the detection of hypermethylation of CCNA1, MGMT, and MINT31 was significantly associated with poor overall survival; the detection of hypermethylation of TIMP3 was significantly associated with local recurrence-free survival; and the detection of hypermethylation of MINT31 was significantly associated with poor disease-free survival. In multivariate analyses, detection of hypermethylation at any single marker was not predictive of overall survival in patients with HNSCC; detection of hypermethylation of TIMP3 in salivary rinse had an independent, significant association with local recurrence-free survival (Hazard Ratio, 2.51, 95% CI, 1.10 to 5.68); and none of the studied markers was significantly associated with disease-free survival. Conclusions: The detection of promoter hypermethylation of the seven genes in salivary rinse as an independent prognostic indicator of overall survival in patients with HNSCC was not validated. Detection of promoter hypermethylation of TIMP3 in pretreatment salivary rinse is independently associated with local recurrence-free survival in patients with HNSCC and may be a valuable salivary rinse biomarker for HNSCC recurrence. Such a test could potentially refine our ability to identify HNSCC patients at a high risk for recurrence.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 723. doi:1538-7445.AM2012-723

Abstract B30: Exogenous miR-128 Enforced HNSCC Inhibits Proliferation

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease with complex molecular abnormalities. There are more than 65,000 Americans diagnosed with head and neck cancer and 25,000 die from this disease. microRNAs are 22~nucleotide-long endogenously expressed, highly conserved noncoding RNAs with important regulatory functions in proliferation, apoptosis, and metastasis. miR-128 a brain-enriched microRNA most commonly in gliomas that have shown to function as a tumor suppressor which decreases cell proliferation and cell invasiveness in prostate cancer. miR-128 has been shown to target BMI-1 in squamous cell carcinoma; however we believe miR-128 functions by targeting multiple targets in HNSCC.

Methods: We established HNSCC cell lines that stably expressed individual members of the miR-128 using a lentiviral delivery system. The levels of miR-128 and their targeted proteins were analyzed by qRT-PCR and Western blot. miR-128 affinity was elucidated by MTT, colony formation, flow cytometry, and a tumor xenograft model.

Results: Enforced transfection of miR-128 in HNSCC (JHU-22) expression was stable in vitro and in vivo. We identified five specific targets of miR-128 (BMI-1, BAG2, BAX, H3f3b, and Paip2). BMI-1 and H3f3b were shown to be a more dominant targeted of miR-128. Overexpression of miR-128, lead to the down regulation of these targets including decrease cell viability (30%), decrease of proliferation (55%), and significantly reduced solid tumor formation in tumor xenografts models.

Conclusions: miR-128 exhibits anti-proliferative effects and phenotypic alteration in HNSCC by targeting multiple predicted conserved targets activity function in apoptosis, cell cycle, transcription, and translation. Therefore, screening for differentially expressed targets of miR-128 help elucidate the possible mechanisms underlining the function of miR-128.Our results indicate that miR-128 has the potential to serve as a therapeutic approach.

Citation Format: Belinda Hauser, Yubin Hao, Joseph Califano, Xinbin Gu. Exogenous miR-128 Enforced HNSCC Inhibits Proliferation [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr B30.

Abstract B40: micro-RNA-128 regulated gene expression in head and neck squamous cell carcinoma

Purpose: Each year in the United States there are more than 65,000 Americans diagnosed with head and neck cancer and 25,000 die from this disease. Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease with complex molecular abnormalities. African Americans have an incidence approximately twice higher than Caucasian men. The overexpression of BMI1 polycomb ring finger oncogene (BMI-1) and epidermal growth factor receptor (EGFR) in HNSCC cases has been shown to be an indicator of poor prognosis and survival in HNSCC. MicroRNAs are a class of posttranslational regulators of gene expression and have been shown to regulate a number of biological processes. In this study, we investigate that mechanism of microRNA-128 (miR-128) involved the regulation of BMI-1 and EGFR gene expressions in HNSCC.

Methods: We generated stably expressing exogenous miRNA-128 in HNSCC of the Larynx (JHU-22) using lentivirus infection, performed colony formation assays to determine cell growth and proliferation, QRT-PCR to analyze gene expression, and western blot analysis to evaluate protein expression.

Results: The transfected JHU-22miR-128 cell line stably expressed exogenous miR-128 in vitro and in vivo tumor xenografts. Compared with the control vector cells, the cell growth and proliferation decreased significantly in JHU-22miR-128 cells and JHU-22miR-128 tumor xenografts. However, the level of BMI-1proteins was decreased more than EGFR in transfected JHU-22miR-128 cells.

Conclusion: miR-128 is able to significantly inhibit BMI-1protein expression, partially affects EGFR protein expression. miR-128 has a putative target site within the mRNA 3′UTR of Bmi-1 and EGFR. Therefore, miR-128 regulates the proliferative pathway in HNSCC. MiR −128 have potential to serve as a therapeutic approach to specifically target EGFR in HNSCC.

This work was supported in part by grants P20 CA118770 from National Cancer Institute.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B40.

NID2 and HOXA9 promoter hypermethylation as biomarkers for prevention and early detection in oral cavity squamous cell carcinoma tissues and saliva

Differentially methylated oral squamous cell carcinoma (OSCC) biomarkers, identified in vitro and validated in well-characterized surgical specimens, have shown poor clinical correlation in cohorts with different risk profiles. To overcome this lack of relevance, we used the HumanMethylation27 BeadChip, publicly available methylation and expression array data, and quantitative methylation specific PCR to uncover differential methylation in OSCC clinical samples with heterogeneous risk profiles. A two stage design consisting of discovery and prevalence screens was used to identify differential promoter methylation and deregulated pathways in patients diagnosed with OSCC and head and neck squamous cell carcinoma. Promoter methylation of KIF1A (κ = 0.64), HOXA9 (κ = 0.60), NID2 (κ = 0.60), and EDNRB (κ = 0.60) had a moderate to substantial agreement with clinical diagnosis in the discovery screen. HOXA9 had 68% sensitivity, 100% specificity, and a 0.81 Area Under the Curve (AUC). NID2 had 71% sensitivity, 100% specificity, and a 0.79 AUC. In the prevalence screen, HOXA9 (κ = 0.82) and NID2 (κ = 0.80) had an almost perfect agreement with histologic diagnosis. HOXA9 had 85% sensitivity, 97% specificity, and a 0.95 AUC. NID2 had 87% sensitivity, 95% specificity, and a 0.91 AUC. A HOXA9 and NID2 gene panel had 94% sensitivity, 97% specificity, and a 0.97 AUC. In saliva, from OSCC cases and controls, HOXA9 had 75% sensitivity, 53% specificity, and a 0.75 AUC. NID2 had 87% sensitivity, 21% specificity, and a 0.73 AUC. This phase I Biomarker Development Trial identified a panel of differentially methylated genes in normal and OSCC clinical samples from patients with heterogeneous risk profiles. This panel may be useful for early detection and cancer prevention studies.

Global oral health inequalities in incidence and outcomes for oral cancer: causes and solutions

The mouth and oropharynx are among the ten most common sites affected by cancer worldwide, but global incidence varies widely. Five-year survival rates exceed 50% in only the best treatment centers. Causes are predominantly lifestyle-related: Tobacco, areca nut, alcohol, poor diet, viral infections, and pollution are all important etiological factors. Oral cancer is a disease of the poor and dispossessed, and reducing social inequalities requires national policies co-ordinated with wider health and social initiatives - the common risk factor approach: control of the environment; safe water; adequate food; public and professional education about early signs and symptoms; early diagnosis and intervention; evidence-based treatments appropriate to available resources; and thoughtful rehabilitation and palliative care. Reductions in inequalities, both within and between countries, are more likely to accrue from the application of existing knowledge in a whole-of-society approach. Basic research aimed at determining individual predisposition and acquired genetic determinants of carcinogenesis and tumor progression, thus allowing for targeted therapies, should be pursued opportunistically.

Abstract 152: MicroRNAs in head and neck squamous cell carcinoma

Background: The accumulating evidence indicates that microRNAs play a key role in tumor development and progression. The aim of this study is to assess the role and function of microRNAs in head and neck squamous cell carcinoma.

Method and Results: We investigated expression profiles of microRNA in head and neck squamous cell carcinoma by using a miRNA microarray platform. Profiles from tumor samples (n=10) and nontumor tissues (n=10) were compared. We identified 24 differentially expressed miRNAs, of which 1 was significantly downregulated, while the other 23 were upregulated in tumor tissues. Mir-21 was most notably upregulated in tumor tissues (P=0.0002), and mir-375 was a potential tumor suppressive microRNA that was significantly downregulated in tumors (P=0.0002). Expression profiles of these two microRNAs were validated by qRT-PCR with separate clinical samples (16 tumors and 15 normal tissues). In vitro assays confirmed that mir-21 stimulated cell growth and mir-375 had a tumor suppressive role. Next, to assess downstream target genes, cells were subjected to microarray analysis after transient transfection with each microRNA or its negative control. We also conducted a bioinformatics search (TargetScan, PicTar, miRanda). By combining these data, we identified potential target genes including YWHAZ (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide) for mir-375 and BNC2 (Basonuclin 2) for mir-21. These potential target genes were downregulated after forced expression of mir-375 or mir-21. The activities of a luciferase reporter containing these microRNA's binding sequences at the 3’ untranslated region (UTR) of some potential target mRNAs were repressed by the ectopic expression of miR-375 or miR-21, suggesting that some of these candidates are specific targets of these microRNAs.

Conclusions: Mir-21 is a potential oncogenic microRNA, and miR-375 is a potential tumor-suppressive microRNA in head and neck squamous carcinoma. Further investigation including pathway analysis of these microRNAs may lead to the detection of therapeutic targets of head and neck cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 152. doi:10.1158/1538-7445.AM2011-152

Abstract 3949: Micro-RNA regulated EGFR expression in head and neck squamous cell carcinoma

Purpose: Each year in the United States there are more than 65,000 Americans diagnosed with head and neck cancer and 25,000 die from this disease. Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease with complex molecular abnormalities, including overexpression of epidermal growth factor receptor (EGFR). The overexpression of EGFR is seen in 80-90% of HNSCC cases and has been shown to be an indicator of poor prognosis and survival in oral cancer patients. The molecular mechanism of EGFR gene expression is poorly understood in HNSCC. MicroRNAs are a new class of posttranslational regulators of gene expression and are a useful target in understanding EGFR gene expression in HNSCC. We hypothesize that microRNAs may play an important role in EGFR gene overexpression during HNSCC processes. Design Methods: We generated stably expressing exogenous miRNA-7 or miRNA-128 in cell lines (JHU-06,-011,-013,-019, -022, and -029 using lentivirus infection, performed colony formation assays to determine cell growth and proliferation, QRT-PCR to analyze gene expression, and Western blot analysis to evaluate protein expression. Results: We found that the miR-7 and -128 transfection efficiency were quite different in these six cell lines. The transfected cell lines stably expressed exogenous miR-7 or -128. Compared with the control cells, the levels of EGFR protein and cell viability were significantly lower in miR-7, -128 transfected HNSCC cell lines. CONCLUSION: We successfully constructed the stably expressing exogenous miR-7, -128 HNSCC cell lines and validated that miR-7,-128 can down-regulate EGFR expression by specifically targeting the EGFR mRNA 3’UTR. MiR-7 and miR-128 have potential to serve as a therapeutic approach to specifically target EGFR in HNSCC. This work was supported in part by grants P20 CA118770 from National Cancer Institute.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3949. doi:10.1158/1538-7445.AM2011-3949

Abstract 5001: BORIS and MageA expression correlate positively in melanoma

Cancer Testis Antigens (CTAs) are proteins that are normally expressed only in the male germ cells. These proteins are not expressed in other normal somatic tissues but are aberrantly upregulated in a variety of cancers like lung and melanoma. The expression of CTA genes is known to be regulated by promoter methylation. Using an integrative epigenetic screening approach, we have previously shown that CTAs are upregulated in non-small cell lung cancer and head and neck squamous cell carcinoma by promoter hypomethylation. Although it is now well accepted that CTAs are regulated by promoter methylation, the regulatory mechanisms of these genes remains unclear. Transcription factor BORIS (Brother Of the Regulator of Imprinted Sites) or CTCFL has been implicated in the regulation of two CTAs, mageA1 and NY-ESO-1. In the present study, we analyzed the expression of BORIS in a cohort of 16 melanoma tissues using quantitative reverse-transcription PCR. BORIS expression was detected in ∼70% of the tissues analyzed. Taking into account the evidence that BORIS regulates the expression of at least two CTAs, we also analyzed the expression of four CTAs, mageA1, mageA2, mageA3 and mageA4, in these tissues to assess the correlation between BORIS and CTA gene expression. We found that expression of mageA1, A2 and A3 correlated significantly with that of BORIS. We also analyzed two publicly available melanoma gene expression datasets and found that BORIS expression correlated with all four mageA genes analyzed. In our cohort as well as in the published gene expression datasets, the expression of the mageA genes tightly correlate with each other. Analysis of the methylation status of the mageA genes in our cohort showed that the methylation levels of mageA1, A2 and A3 genes also correlated with each other significantly. These observations support the phenomenon of coordinated CTA expression in solid tumors. We also found inverse correlation between the methylation and expression levels of these genes in some of the tissues analyzed. These results indicate that coordinated transcriptional regulation of the mageA genes may occur via promoter methylation dependent as well as independent mechanisms. Given the role of BORIS in the derepression of mageA1 gene via promoter demethylation, we also evaluated the correlation between BORIS expression and CTA promoter demethylation. We found that BORIS expression and mageA gene demethylation correlated in a subset of the tissues analyzed. The association between expression of BORIS and the mageA genes supports a role for BORIS as an effector in the upregulation of these genes. Also, the coordinated expression of the mageA genes suggests a common transcriptional mechanism for their regulation and our study presents evidence that implicates BORIS as a common regulator of the CTAs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5001. doi:10.1158/1538-7445.AM2011-5001

Abstract 125: Exogenous MiR-125b inhibits head and neck squamous cell carcinoma growth by suppressing Bcl-2 expression

PURPOSE: Head and neck squamous cell cancer (HNSCC) is one of top ten cancers in the United States. The overall 5-year survival rate of HNSCC has not improved in the past two decades. B-cell lymphoma 2 (Bcl-2), an oncogene, is a key regulator of the apoptosis to promote cell proliferation and apoptosis arrest. Therefore, targeting Bcl-2 is an attractive strategy for restoring a normal apoptotic process and inhibiting cancer cell growth in HNSCC. MicroRNAs (miRNAs) are a class of ∼22-nucleotide-long, endogenously expressed, highly conserved of noncoding RNAs with important regulatory functions in proliferation, apoptosis and metastasis. In this study, we screened eight cancer-associated miRNAs levels (mir-21, -124, -125b, -147, -200a, -200b, -200c and -429) in twenty five human tissue specimens and four cell lines, including twenty HNSCC specimens and five normal controls, and three HNSCC cell lines (JHU-13, -22 and -29) and one transformed oral keratinocytes cell line (OKF-6). Based on the screening data, we further investigated the mechanism of miRNA-125b (miR-125b) regulated Bcl-2 expression and the therapeutic potential of exogenous miR-125b in a miR-125b stable transfected HNSCC cell line. Design Methods: The miRNA expression level was determined by quantitative RT-PCR. A stable expressed exogenous miR-125b HNSCC cell line (JHU-22miR125b) was generated by using lentivirus transfection. Colony formation and MTT assayed cell growth and cell viability and Western blot was used to analyze protein expression. Results: The expression levels of mir-124 and mir-125b were significant lower in both tumor tissue and tumor cell lines than control, and mir-21 was significant higher in tumors. Thus, mir-125b was selected as a candidate for further study. The level of miR-125b in the transfected cell lines (JHU-22miR125b) was increased more than five times compared with the control cells (Transfected with vector only, JHU-22vector). The levels of Bcl-2 protein and cell viability were significantly lower in JHU-22miR125b than JHU-22 vector. CONCLUSION: Bcl-2 is a direct target in miR-125b regulated Bcl-2 expression. Exogenous miR-125b suppresses the proliferation and growth of cultured HNSCC cells. The effect of exogenous miR-125b on inhibition of HNSCC growth via suppressing Bcl-2 expression will be further validated in tumor xanografts. This work was supported in part by grants P20 CA118770 from National Cancer Institute.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 125. doi:10.1158/1538-7445.AM2011-125

High-risk human papillomavirus in nasopharyngeal carcinoma

BACKGROUND

Human papillomavirus (HPV), a cause of oropharyngeal carcinoma, has also been implicated as an etiologic agent in nasopharyngeal carcinomas.

METHODS

We performed p16 immunohistochemistry and in situ hybridization for Epstein-Barr virus (EBV) and HPV on 45 carcinomas of the nasopharynx.

RESULTS

Thirty-four (76%) carcinomas were EBV-positive/HPV-negative, 7 (16%) were EBV-negative/HPV-negative, and 4 (9%) were EBV-negative/HPV-positive. HPV was more likely to be detected in carcinomas from white patients than non-white patients (16% vs 0%; p = .03). Of the 3 patients with HPV-positive carcinomas and available staging information, all were found to have extension into the oropharynx. All HPV-positive carcinomas were p16 positive, but none of the HPV-negative carcinomas were p16 positive (p < .001).

CONCLUSION

HPV can be detected in a subset of carcinomas involving the nasopharynx, but many of these may represent extension from an oropharyngeal primary. P16 immunohistochemistry is a reliable marker for separating EBV-related and HPV-related carcinomas of Waldheyer's ring.

Enforced expression of miR-101 inhibits prostate cancer cell growth by modulating the COX-2 pathway in vivo

It is commonly agreed that there is an association of chronic inflammation with tumorigenesis. COX-2, a key regulator of inflammation-producing prostaglandins, promotes cell proliferation and growth; thus, overexpression of COX-2 is often found in tumor tissues. Therefore, a better understanding of the regulatory mechanism(s) of COX-2 could lead to novel targeted cancer therapies. In this study, we investigated the mechanism of microRNA-101 (miR-101)-regulated COX-2 expression and the therapeutic potential of exogenous miR-101 for COX-2-associated cancer. A stably expressing exogenous miR-101 prostate cancer cell line (BPH1(CmiR101)) was generated by using lentiviral transduction as a tool for in vitro and in vivo studies. We found that miR-101 inhibited COX-2 posttranscriptional expression by directly binding to the 3'-untranslated region (3'-UTR) of COX-2 mRNA. The regulatory function of miR-101 was also confirmed by using antisense DNA. As a result, exogenous miR-101 is able to effectively suppress the growth of cultured prostate cancer cells and prostate tumor xenografts. The average tumor weight was significantly lower in the BPH1(CmiR101) group (0.22 g) than the BPH1(Cvec) group (0.46 g). Expression levels of the cell growth regulators, such as cyclin proteins, PCNA (proliferating cell nuclear antigen), EGFR (epidermal growth factor receptor), were also studied. In conclusion, COX-2 is a direct target in miR-101 regulation of posttranscription. Exogenous miR-101 suppresses the proliferation and growth of prostate cancer cells in vitro and in vivo. These data suggest that exogenous miR-101 may provide a new cancer therapy by directly inhibiting COX-2 expression.

Salvianolic acid B inhibits growth of head and neck squamous cell carcinoma in vitro and in vivo via cyclooxygenase-2 and apoptotic pathways

Overexpression of cyclooxygenase-2 (COX-2) in oral mucosa has been associated with increased risk of head and neck squamous cell carcinoma (HNSCC). Celecoxib is a nonsteroidal anti-inflammatory drug, which inhibits COX-2 but not COX-1. This selective COX-2 inhibitor holds promise as a cancer preventive agent. Concerns about cardiotoxicity of celecoxib, limits its use in long-term chemoprevention and therapy. Salvianolic acid B (Sal-B) is a leading bioactive component of Salvia miltiorrhiza Bge, which is used for treating neoplastic and chronic inflammatory diseases in China. The purpose of this study was to investigate the mechanisms by which Sal-B inhibits HNSCC growth. Sal-B was isolated from S. miltiorrhiza Bge by solvent extraction followed by 2 chromatographic steps. Pharmacological activity of Sal-B was assessed in HNSCC and other cell lines by estimating COX-2 expression, cell viability and caspase-dependent apoptosis. Sal-B inhibited growth of HNSCC JHU-022 and JHU-013 cells with IC(50) of 18 and 50 microM, respectively. Nude mice with HNSCC solid tumor xenografts were treated with Sal-B (80 mg/kg/day) or celecoxib (5 mg/kg/day) for 25 days to investigate in vivo effects of the COX-2 inhibitors. Tumor volumes in Sal-B treated group were significantly lower than those in celecoxib treated or untreated control groups (p < 0.05). Sal-B inhibited COX-2 expression in cultured HNSCC cells and in HNSCC cells isolated from tumor xenografts. Sal-B also caused dose-dependent inhibition of prostaglandin E(2) synthesis, either with or without lipopolysaccharide stimulation. Taken together, Sal-B shows promise as a COX-2 targeted anticancer agent for HNSCC prevention and treatment.

Coordinated activation of candidate proto-oncogenes and cancer testes antigens via promoter demethylation in head and neck cancer and lung cancer

Background

Epigenetic alterations have been implicated in the pathogenesis of solid tumors, however, proto-oncogenes activated by promoter demethylation have been sporadically reported. We used an integrative method to analyze expression in primary head and neck squamous cell carcinoma (HNSCC) and pharmacologically demethylated cell lines to identify aberrantly demethylated and expressed candidate proto-oncogenes and cancer testes antigens in HNSCC.

Methodology/Principal Findings

We noted coordinated promoter demethylation and simultaneous transcriptional upregulation of proto-oncogene candidates with promoter homology, and phylogenetic footprinting of these promoters demonstrated potential recognition sites for the transcription factor BORIS. Aberrant BORIS expression correlated with upregulation of candidate proto-oncogenes in multiple human malignancies including primary non-small cell lung cancers and HNSCC, induced coordinated proto-oncogene specific promoter demethylation and expression in non-tumorigenic cells, and transformed NIH3T3 cells.

Conclusions/Significance

Coordinated, epigenetic unmasking of multiple genes with growth promoting activity occurs in aerodigestive cancers, and BORIS is implicated in the coordinated promoter demethylation and reactivation of epigenetically silenced genes in human cancers.

Clinical and molecular characteristics of squamous cell carcinomas from Fanconi anemia patients

Fanconi anemia is a recessively inherited disease that is characterized by congenital abnormalities, bone marrow failure, and a predisposition to develop cancer, particularly squamous cell carcinomas (SCCs) in the head and neck and anogenital regions. Previous studies of Fanconi anemia SCCs, mainly from US patients, revealed the presence of high-risk human papillomavirus (HPV) DNA in 21 (84%) of 25 tumors analyzed. We examined a panel of 21 SCCs mainly from European Fanconi anemia patients (n = 19 FA patients; 16 head and neck squamous cell carcinomas [HNSCCs], 2 esophageal SCCs, and 3 anogenital SCCs) for their clinical and molecular characteristics, including patterns of allelic loss, TP53 mutations, and the presence of HPV DNA by GP5+/6+ polymerase chain reaction. HPV DNA was detected in only two (10%) of 21 tumors (both anogenital SCCs) but in none of the 16 HNSCCs. Of the 18 tumors analyzed, 10 contained a TP53 mutation. The patterns of allelic loss were comparable to those generally found in sporadic SCCs. Our data show that HPV does not play a major role in squamous cell carcinogenesis in this cohort of Fanconi anemia patients and that the Fanconi anemia SCCs are genetically similar to sporadic SCCs despite having a different etiology.

Current status of biomarkers in head and neck cancer

As our understanding of HNSCC increases so has biomarker development. HPV16 integration is a significant marker of favorable prognosis and response to therapy for HNSCC. EGFR-amplification and overexpression is a poor-prognostic indicator. For premalignant lesions, LOH of 3p&9p21 loci confers an elevated risk of malignant transformation. As molecular targets are identified, these will be candidates for biomarkers for detection, diagnosis, prognosis, and therapy. Validation of these biomarkers requires demonstration of independence of significance beyond known biomarkers.

Genome-wide promoter analysis uncovers portions of the cancer methylome

DNA methylation has a role in mediating epigenetic silencing of CpG island genes in cancer and other diseases. Identification of all gene promoters methylated in cancer cells "the cancer methylome" would greatly advance our understanding of gene regulatory networks in tumorigenesis. We previously described a new method of identifying methylated tumor suppressor genes based on pharmacologic unmasking of the promoter region and detection of re-expression on microarray analysis. In this study, we modified and greatly improved the selection of candidates based on new promoter structure algorithm and microarray data generated from 20 cancer cell lines of 5 major cancer types. We identified a set of 200 candidate genes that cluster throughout the genome of which 25 were previously reported as harboring cancer-specific promoter methylation. The remaining 175 genes were tested for promoter methylation by bisulfite sequencing or methylation-specific PCR (MSP). Eighty-two of 175 (47%) genes were found to be methylated in cell lines, and 53 of these 82 genes (65%) were methylated in primary tumor tissues. From these 53 genes, cancer-specific methylation was identified in 28 genes (28 of 53; 53%). Furthermore, we tested 8 of the 28 newly identified cancer-specific methylated genes with quantitative MSP in a panel of 300 primary tumors representing 13 types of cancer. We found cancer-specific methylation of at least one gene with high frequency in all cancer types. Identification of a large number of genes with cancer-specific methylation provides new targets for diagnostic and therapeutic intervention, and opens fertile avenues for basic research in tumor biology.

Visualizing head and neck tumors in vivo using near-infrared fluorescent transferrin conjugate

Transferrin receptor (TfR) is overexpressed in human head and neck squamous cell carcinomas (HNSCCs). This study was carried out to investigate the feasibility of imaging HNSCC by targeting TfR using near-infrared fluorescent transferrin conjugate (TfNIR). Western blot analysis of four HNSCC cell lines revealed overexpression of TfR in all four lines compared with that in normal keratinocytes (OKFL). Immunocytochemistry further confirmed the expression of TfR and endocytosis of TfNIR in JHU-013 culture cells. Following intravenous administration of TfNIR (200 microL, 0.625 microg/microL), fluorescent signal was preferentially accumulated in JHU-013 tumor xenografts grown in the lower back (n=14) and oral base tissues (n=4) of nude mice. The signal in tumors was clearly detectable as early as 10 minutes and reached the maximum at 90 to 120 minutes postinjection. The background showed an increase, followed by a decrease at a much faster pace than tumor signal. A high fluorescent ratio of the tumor to muscle was obtained (from 1.42 to 4.15 among tumors), usually achieved within 6 hours, and correlated with the tumor size (r=.74, p=.002). Our results indicate that TfR is a promising target and that Tf(NIR)-based optical imaging is potentially useful for noninvasive detection of early HNSCC in the clinic.

Membrane trafficking of AQP5 and cAMP dependent phosphorylation in bronchial epithelium

Phosphorylation pathway has been identified as an important step in membrane trafficking for AQP5. We generated stably transfected BEAS-2B human bronchial epithelial cells with various over-expression constructs on permeable support. In stable cells with wild-type AQP5 and S156A (AQP5 mutant targeting PKA consensus sequence), AQP5 expression was predominantly polarized to the apical membrane, whereas stable cells with N185D (AQP5 mutant targeting second NPA motif), mainly localized to the cytoplasm. Treatment with H89 and/or chlorophenylthio-cAMP (cpt-cAMP) did not affect membrane expression of AQP5 in any of three stable cells. In cells with wild-type AQP5 and N185D, AQP5s were phosphorylated by PKA, while phosphorylation of AQP5 was not detected in cells with S156A. These results indicate that, in AQP5, serine156 may be phosphorylated by PKA, but membrane expression of AQP5 may not be regulated by PKA phosphorylation. We conclude that AQP5 membrane targeting can include more than one mechanism besides cAMP dependent phosphorylation.

Positive correlation of tissue inhibitor of metalloproteinase-3 and death-associated protein kinase hypermethylation in head and neck squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

Promoter hypermethylation of tumor suppressor genes is common in head and neck cancer as well as other primary cancers resulting in epigenetic gene silencing. Tissue inhibitor of metalloproteinase-3 (TIMP-3) has been shown to have promoter hypermethylation in several solid tumors, but has not been identified in head and neck squamous cell carcinoma (HNSCC). Our objective was to determine if TIMP-3 promoter was hypermethylated in HNSCC, if there was any correlation with death associated protein kinase (DAPK), a tumor suppressor whose promoter has been hypermethylated at high levels in HNSCC, and if any clinical factors influence hypermethylation of either of these genes.

STUDY DESIGN

Prospective study.

METHODS

Tumor samples from 124 patients with HNSCC were evaluated for promoter hypermethylation for TIMP-3 and DAPK using quantitative methylation specific polymerase chain reaction (qMSP). We compared both TIMP-3 and DAPK hypermethylation in HNSCC with each other as well as with other clinical variables.

RESULTS

We found that TIMP-3 was hypermethylated in approximately 71.8% of the tumor samples and DAPK was hypermethylated in 74.2%. The presence of TIMP-3 and DAPK promoter hypermethylation was significantly higher than in control specimens. More importantly, TIMP-3 and DAPK hypermethylations in these samples were highly correlated with a concordance of 78% (P < .001). DAPK was also correlated with current alcohol consumption (P < .028), but neither TIMP-3 nor DAPK hypermethylation was significantly correlated with other clinical variables or with survival.

CONCLUSION

TIMP-3 promoter hypermethylation is elevated in HNSCC and is highly correlated with DAPK hypermethylation, implying a functional relationship between these genes.

Microsatellite analysis of recurrent vestibular schwannoma (acoustic neuroma) following stereotactic radiosurgery

HYPOTHESIS

Genetic and immunohistochemical studies may provide insight into the mechanisms of vestibular schwannoma (VS) recurrence following radiation therapy.

BACKGROUND

Stereotactic radiation therapy is an increasingly common alternative to microsurgical resection for the primary management of sporadic VS. The molecular mechanisms associated with recurrent vestibular schwannoma (VS) following radiation therapy are not known.

METHODS

Primary or irradiated VS tumors were fresh-frozen at the time of surgical resection and microdissected to undergo DNA extraction. Lymphocytic control DNA was isolated from blood obtained by venipuncture. Paired normal and tumor DNA specimens were analyzed for allelic loss by PCR amplification of polymorphic dinucleotide repeat sequences. Immunohistochemical studies were performed on paraffin-embedded, irradiated surgical specimens.

RESULTS

Using 16 polymorphic microsatellite markers, 20 of 26 non-irradiated VS demonstrated loss of heterozygosity (LOH) in at least one locus of chromosome 22q. In contrast, none of the four irradiated recurrent VS demonstrated LOH on chromosome 22q (p = 0.008). No allelic loss was seen in either the primary or irradiated VS utilizing markers mapping to chromosome 10. Deletions on chromosome 10 are seen in both benign and higher-grade meningiomas and intracranial malignancies associated with radiotherapy. Immunohistochemical studies were performed to detect the protein product of the NF2 gene, merlin, in the four irradiated VS. NF2 staining was not observed.

CONCLUSION

This study represents the first microsatellite and immunohistochemical analysis of recurrent VS following radiation therapy. Our preliminary observations suggest an alternative mechanism of NF2 inactivation that may correlate with radioresistance in VS.

Downregulation of RAD17 in head and neck cancer

BACKGROUND

DNA repair genes play a critical role in maintaining genome stability and have been implicated in tumorigenesis. Head and neck squamous cell carcinoma (HNSCC) often shows chromosomal instability. We examined the expression of human RAD17, a DNA damage cell cycle checkpoint gene, in primary head and neck cancer tissue.

METHODS

Significance analysis of microarrays was applied to expression array results examining more than 12,000 genes in 7 samples of primary HNSCC and 6 samples of normal control oral epithelial tissue. Additional confirmation was performed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) in these samples and western blot with an additional 12 primary HNSCC and 7 normal samples, followed by loss of heterozygosity (LOH) analysis and quantitative PCR at the RAD17 locus.

RESULTS

Multiple checkpoint and DNA repair genes were downregulated in primary head and neck tumor tissue compared with normal control epithelial tissue, including hRAD17. Its Z-score and fold change were -2.5 and 0.39, respectively. The results of normalized, quantitative RT-PCR showed decreased expression of hRAD17 mRNA in tumor tissue (mean value 0.2166) when compared with normal tissue (mean value 0.3957, p < .05). Western blot demonstrated undetectable expression of hRAD17 protein in primary tumor tissue (0/12), while there was strong expression of hRAD17 protein in normal oral mucosal tissue (6/7). To determine possible mechanisms of inactivation, the hRAD17 locus at 5q13 was analyzed using microsatellite markers, showing 70% LOH in 30 primary HNSCCs. Quantitative PCR showed that RAD17 DNA copy number was decreased in the majority of head and neck tumor tissue samples.

CONCLUSION

Loss of hRAD17 expression occurs frequently in HNSCC, is often due to genomic deletion, and may facilitate genomic instability in HNSCC.

Increased plasma DNA integrity index in head and neck cancer patients

Analysis of the length of circulating DNA in plasma has been reported as a marker for solid tumor detection. We assessed the sensitivity and specificity of increased plasma DNA length to identify patients with head and neck squamous cell carcinoma (HNSCC) and monitor posttreatment disease status. Fifty-eight HNSCC patients with paired pre- and postoperative plasma and 47 plasma samples from control subjects were analyzed using quantitative PCR to determine plasma DNA integrity index. We found that the mean DNA integrity index was significantly greater in the plasma from HNSCC patients, 0.24 (95% CI: 0.11, 0.38), when compared to plasma from the control subjects, -2.24 (95% CI: -2.92, -1.56), p < 0.0001 using multivariate analysis. The optimal sensitivity (the value for which sensitivity equals specificity) was found at a plasma DNA integrity index of 0.82: sensitivity, 84.5%; specificity, 83%. However, there was no significant difference noted between pre- and postoperative DNA integrity index in plasma samples from HNSCC patients. This study shows that DNA integrity index in the plasma of the patients with HNSCC is increased in comparison with that in the plasma from non-HNSCC control subjects. Lack of normalization of plasma DNA integrity index after surgical resection implies the persistence of a population of cells with an altered pattern of DNA degradation despite removal of malignancy.

Phosphodiesterase-5 inhibition augments endogenous antitumor immunity by reducing myeloid-derived suppressor cell function

Phosphodiesterase-5 (PDE5) inhibitors (sildenafil, tadalafil, and vardenafil) are agents currently in clinical use for nonmalignant conditions. We report the use of PDE5 inhibitors as modulators of the antitumor immune response. In several mouse tumor models, PDE5 inhibition reverses tumor-induced immunosuppressive mechanisms and enables a measurable antitumor immune response to be generated that substantially delays tumor progression. In particular, sildenafil, down-regulates arginase 1 and nitric oxide synthase-2 expression, thereby reducing the suppressive machinery of CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) recruited by growing tumors. By removing these tumor escape mechanisms, sildenafil enhances intratumoral T cell infiltration and activation, reduces tumor outgrowth, and improves the antitumor efficacy of adoptive T cell therapy. Sildenafil also restores in vitro T cell proliferation of peripheral blood mononuclear cells from multiple myeloma and head and neck cancer patients. In light of the recent data that enzymes mediating MDSC-dependent immunosuppression in mice are active also in humans, these findings demonstrate a potentially novel use of PDE5 inhibitors as adjuncts to tumor-specific immune therapy.

An oligonucleotide microarray for high-throughput sequencing of the mitochondrial genome

Previously we developed an oligonucleotide sequencing microarray (MitoChip) as an array-based sequencing platform for rapid and high-throughput analysis of mitochondrial DNA. The first generation MitoChip, however, was not tiled with probes for the noncoding D-loop region, a site frequently mutated in human cancers. Here we report the development of a second-generation MitoChip (v2.0) with oligonucleotide probes to sequence the entire mitochondrial genome. In addition, the MitoChip v2.0 contains redundant tiling of sequences for 500 of the most common haplotypes including single-nucleotide changes, insertions, and deletions. Sequencing results from 14 primary head and neck tumor tissues demonstrated that the v2.0 MitoChips detected a larger number of variants than the original version. Multiple coding region variants detected only in the second generation MitoChips, but not the earlier chip version, were further confirmed with conventional sequencing. Moreover, 31 variations in noncoding region were identified using MitoChips v2.0. Replicate experiments demonstrated >99.99% reproducibility in the second generation MitoChip. In seven head and neck cancer samples with matched lymphocyte DNA, the MitoChip v2.0 detected at least one cancer-associated mitochondrial mutation in four (57%) samples. These results indicate that the second generation MitoChip is a high-throughput platform for identification of mitochondrial DNA mutations in primary tumors.

The major 8p22 tumor suppressor DLC1 is frequently silenced by methylation in both endemic and sporadic nasopharyngeal, esophageal, and cervical carcinomas, and inhibits tumor cell colony formation

Identification of tumor suppressor genes (TSG) silenced by methylation uncovers mechanisms of tumorigenesis and identifies new epigenetic tumor markers for early cancer detection. Both nasopharyngeal carcinoma (NPC) and esophageal carcinoma are major tumors in Southern China and Southeast Asia. Through expression subtraction of NPC, we identified Deleted in Liver Cancer 1 (DLC1)/ARHGAP7 (NM_006094)--an 8p22 TSG as a major downregulated gene. Although expressed in all normal tissues, DLC1 was silenced or downregulated in 11/12 (91%) NPC, 6/15 (40%) esophageal, 5/8 (63%) cervical and 3/9 (33%) breast carcinoma cell lines. No genetic deletion of DLC1 was detected in NPC although a hemizygous deletion at 8p22-11 was found by 1-Mb array-CGH in some cell lines. We then located the functional DLC1 promoter by 5'-RACE and promoter activity assays. This promoter was frequently methylated in all downregulated cell lines and in a large collection of primary tumors including 89% (64/72) NPC (endemic and sporadic types), 51% (48/94) esophageal, 87% (7/8) cervical and 36% (5/14) breast carcinomas, but seldom in paired surgical marginal tissues and not in any normal epithelial tissue. The transcriptional silencing of DLC1 could be reversed by 5-aza-2'-deoxycytidine or genetic double knock-out of DNMT1 and DNMT3B. Furthermore, ectopic expression of DLC1 in NPC and esophageal carcinoma cells strongly inhibited their colony formation. We thus found frequent epigenetic silencing of DLC1 in NPC, esophageal and cervical carcinomas, and a high correlation of methylation with its downregulation, suggesting a predominant role of epigenetic inactivation. DLC1 appears to be a major TSG implicated in the pathogenesis of these tumors, and should be further tested as a molecular biomarker in patients with these cancers.

Prognostic implication of p53 mutations in HNSCC: Results of Intragroup margin study (E4393)

5504

Background: The role of p53 as a prognostic marker in head and neck squamous cell carcinoma (HNSCC) is controversial. The intent of this study was to evaluate rigorously the prognostic value of p53 genetic status. Methods: Tumor samples from 480 HNSCC patients treated surgically with curative intent were collected in a prospective multicenter study over 5 years. 57 cases were not analyzed due to technical or administrative factors. Mutation status was determined in the 423 remaining cases, using p53 chip (GP53 GeneChip from Affymetrix, Inc., Santa Clara, CA) which identifies mutations in exons 2 through 11. Indeterminate calls were investigated using Surveyor and/or DHPLC analysis and all mutations were confirmed with an automated fluorescent system or manual sequencing. Clinical follow-up was accomplished following Eastern Cooperative Oncology Group protocol. Results: Median follow-up of the 423 evaluable subjects was 5.4 years with all patients followed at least 3 years. Mutation of p53 gene was present in 224 (53%) cases. There we significantly fewer mutations in tumors arising in the oropharynx (chi-square p = 0.02). The presence of p53 mutation was significantly associated with decreased overall survival. Median survival for patients with tumors with p53 mutation was 3.1 years compared to 5.4 years fro WT tumors (HR = 1.4, 95% CI =1.1 to 1.8, p = 0.01 log-rank test). This proved to be independent of tumor site in multivariate analysis. When mutations were segregated according to their effect on biological function through alteration of key DNA binding domains a Cox regression analysis revealed a statistically significant linear effect of the more disruptive mutations on overall survival with a HR of 1.3 for comparison of each group to the one of lower risk (more vs. less disruptive mutation v. WT (p = 0.001 Wald test). Conclusions: This large prospective series shows a strong relationship between TP53 mutation and prognosis in HNSCC patients. Furthermore, the biological impact of specific mutations has a predictable graded relation to clinical outcome. The results set the stage for use of p53 genetic status in the design of future clinical trials and support the development of targeted therapy to restore wild-type p53 function.

No significant financial relationships to disclose.

Mitochondrial DNA content increase in response to cigarette smoking

An increase in mitochondrial DNA (mtDNA) content and decline in mitochondrial function occurs with aging and in response to DNA-damaging agents, including tobacco smoke. We did a cross-sectional study and quantified changes in mtDNA content in a population of individuals with varied smoking and alcohol exposure. Age, smoking history, ethanol intake, and other demographic data were characterized for 604 individuals participating in a screening study for smoking-related upper aerodigestive malignancy. Total DNA was extracted from exfoliated cells in saliva. DNA from a nuclear gene, beta-actin, and two mitochondrial genes, cytochrome c oxidase I and II (Cox I and Cox II), were quantified by real-time PCR. mtDNA content was correlated with age, exposure history, and other variables using multivariate regression analyses. A significant increase (P<0.001) in mtDNA content was noted in smokers (31% and 29% increase for Cox I and Cox II, respectively) and former smokers (31% and 34%) when compared with never smokers. This association persisted after adjustment for other significant factors including age, alcohol drinking, and income (P<0.001). Increased mtDNA content was positively associated with pack-years of smoking (P=0.02). Despite an average smoking cessation interval of 21 years in former smokers, tobacco cessation interval was not statistically significantly associated with mtDNA content. Smoking is associated with increased mtDNA content in a dose-dependent fashion. Mitochondrial DNA alterations in response to smoking persist for several decades after smoking cessation, consistent with long-term, smoking-related damage.

The role of positron emission tomography and computed tomography fusion in the management of early-stage and advanced-stage primary head and neck squamous cell carcinoma

OBJECTIVE

To evaluate the role of positron emission tomography and computed tomography (PET-CT) fusion in the management of early-stage and advanced-stage primary head and neck squamous cell cancer.

DESIGN

Retrospective analysis, with a blinded evaluation of clinical data and formation of a treatment plan.

SETTING

Single tertiary academic medical institution. Patients Thirty-six patients with previously untreated head and neck squamous cell carcinoma who underwent staging CT or magnetic resonance imaging of the neck prior to undergoing PET-CT as part of their initial diagnostic evaluation between July 2000 and January 2005.

MAIN OUTCOME MEASURES

Confirmation or alteration of the treatment plan with the addition of the PET-CT information compared with traditional clinical and radiological data alone for early-stage and advanced-stage disease. When available, histopathological results were correlated with the PET-CT findings.

RESULTS

Among the 36 patients, PET-CT provided additional information that confirmed the treatment plan in 25 patients (69%) and altered the treatment plan in 11 patients (31%). Six of 11 patients in the altered-treatment group had their tumors upstaged. Four of 8 patients with early-stage tumors had their treatment plan altered, compared with 7 of 28 patients with advanced-stage disease. Among 18 patients who underwent a surgical intervention for their primary tumor, PET-CT identified the primary tumor in all 18 patients and, based on histopathological findings, correctly staged the regional nodal disease in 9 of 16 patients who had their nodal disease addressed.

CONCLUSION

The use of PET-CT is important in the initial treatment planning of early-stage and advanced-stage head and neck squamous cell carcinoma.