Original article
Transcriptional Profiling by Sequencing of Oropharyngeal Cancer

https://doi.org/10.1016/j.mayocp.2011.10.008Get rights and content

Abstract

Objective

To compare full transcriptome expression levels of matched tumor and normal samples from patients with oropharyngeal carcinoma stratified by known tumor etiologic factors.

Patients and Methods

Full transcriptome sequencing was analyzed for 10 matched tumor and normal tissue samples from patients with previously untreated oropharyngeal carcinoma. Transcriptomes were analyzed using massively parallel messenger RNA sequencing and validated using the NanoString nCounter system. Global gene expression levels were compared in samples grouped by smoking status and human papillomavirus status. This study was completed between June 10, 2010, and June 30, 2011.

Results

Global gene expression analysis indicated tumor tissue from former smokers grouped more closely to the never smokers than the current smokers. Pathway analysis revealed alterations in the expression of genes involved in the p53 DNA damage-repair pathway, including CHEK2 and ATR, which display patterns of increased expression that is associated with human papillomavirus–negative current smokers rather than former or never smokers.

Conclusion

These findings support the application of messenger RNA sequencing technology as an important clinical tool for more accurately stratifying patients based on individual tumor biology with the goal of improving our understanding of tumor prognosis and treatment response, ultimately leading to individualized patient care strategies.

Section snippets

Collection and Processing of Tissues

After institutional review board approval, oropharyngeal tumor samples were obtained from patients undergoing surgical treatment of OPSCC at Mayo Clinic, Rochester, MN. After achieving negative surgical margins, adjacent normal mucosal tissue was collected from the oropharynx. All tissue was snap-frozen in liquid nitrogen for storage. Samples were evaluated by frozen sectioning, with a fresh blade between samples, and preparation of hematoxylin-eosin slides. The slides for each sample were

Measurement of Gene Expression in OPSCC and Patient-Matched Normal Tissue by RNA Transcriptional Sequencing

We constructed mRNA-Seq libraries from poly A+ selected transcripts, and each library was sequenced on a single lane of the Illumina GAIIx machine. Using paired-end, 51-bp sequencing, we were able to obtain a mean of 63 million reads per transcriptome. We then compared mRNA-seq analysis for 10 patient-matched samples representing primary SCC and normal tissue (Table 1). One of the sequenced samples was excluded because of incomplete smoking history. The remaining 9 tumor and normal paired

Discussion

In this report we used total transcriptome sequencing analysis to characterize a group of oropharyngeal tumors and patient-matched normal tissues. Oropharyngeal tumors display a wide range of behavior, including differences in patterns of invasion, tendency for metastasis, and widely varying treatment responses. Clinicians' inability to accurately predict tumor behavior leads to widely varying treatment strategies, often resulting in significant morbidity and even mortality. Increasing evidence

Conclusion

Transcriptional profiling by mRNA-seq allowed us to identify unique patterns of global gene regulation that correlated with patient exposure to known oncogenic risk factors. Specific gene targets involved in the p53 DNA damage-repair pathway, including CHEK2 and ATR, were analyzed and displayed patterns of increased expression associated with HPV-negative current smokers when compared with past smokers or nonsmokers. Identification and validation of these and related gene targets will serve as

Acknowledgments

We thank Charles Beatty, MD, chair of otorhinolaryngology, Mayo Clinic, Rochester, MN, for his ongoing support of this work, and the Stoll Foundation for postdoctoral fellowship support.

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For editorial comment, see page 211

Grant Support: This work was supported by internal funding from the Mayo Foundation for Medical Education and Research. The efforts of Todd M. Smith and N. Eric Olson were supported by award 2R44HG005297 from the National Human Genome Research Institute.

Potential Competing Interests: Todd M. Smith and N. Eric Olson are employed by Geospiza, a PerkinElmer company. The authors have no financial interests to disclose.

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