Changes in circulating microRNAs after radiochemotherapy in head and neck cancer patients.

Isolde Summerer,Simone Moertl,Julia Hess,Verena Zangen,Michael J Atkinson,Adriana Pitea,Horst Zitzelsberger,Maximilian Niyazi,Kristian Unger,Claus Belka

doi:10.1186/1748-717x-8-296

Abstract

IntroductionCirculating microRNAs (miRNAs) are easily accessible and have already proven to be useful as prognostic markers in cancer patients. However, their origin and function in the circulation is still under discussion. In the present study we analyzed changes in the miRNAs in blood plasma of head and neck squamous cell carcinoma (HNSCC) patients in response to radiochemotherapy and compared them to the changes in a cell culture model of primary HNSCC cells undergoing simulated anti-cancer therapy.Materials and methodsMiRNA-profiles were analyzed by qRT-PCR arrays in paired blood plasma samples of HNSCC patients before therapy and after two days of treatment. Candidate miRNAs were validated by single qRT-PCR assays. An in vitro radiochemotherapy model using primary HNSCC cell cultures was established to test the possible tumor origin of the circulating miRNAs. Microarray analysis was performed on primary HNSCC cell cultures followed by validation of deregulated miRNAs via qRT-PCR.ResultsUnsupervised clustering of the expression profiles using the six most regulated miRNAs (miR-425-5p, miR-21-5p, miR-106b-5p, miR-590-5p, miR-574-3p, miR-885-3p) significantly (p = 0.012) separated plasma samples collected prior to treatment from plasma samples collected after two days of radiochemotherapy. MiRNA profiling of primary HNSCC cell cultures treated in vitro with radiochemotherapy revealed differentially expressed miRNAs that were also observed to be therapy-responsive in blood plasma of the patients (miR-425-5p, miR-21-5p, miR-106b-5p, miR-93-5p) and are therefore likely to stem from the tumor. Of these candidate marker miRNAs we were able to validate by qRT-PCR a deregulation of eight plasma miRNAs as well as miR-425-5p and miR-93-5p in primary HNSCC cultures after radiochemotherapy.ConclusionChanges in the abundance of circulating miRNAs during radiochemotherapy reflect the therapy response of primary HNSCC cells after an in vitro treatment. Therefore, the responsive miRNAs (miR-425-5p, miR-93-5p) may represent novel biomarkers for therapy monitoring. The prognostic value of this exciting observation requires confirmation using an independent patient cohort that includes clinical follow-up data.

Highlights

Circulating microRNAs are accessible and have already proven to be useful as prognostic markers in cancer patients
Unsupervised clustering of the expression profiles using the six most regulated miRNAs significantly (p = 0.012) separated plasma samples collected prior to treatment from plasma samples collected after two days of radiochemotherapy
MiRNA profiling of primary head and neck squamous cell carcinoma (HNSCC) cell cultures treated in vitro with radiochemotherapy revealed differentially expressed miRNAs that were observed to be therapy-responsive in blood plasma of the patients and are likely to stem from the tumor

Summary

Introduction

Circulating microRNAs (miRNAs) are accessible and have already proven to be useful as prognostic markers in cancer patients. Their origin and function in the circulation is still under discussion. Surgical treatment of head and neck squamous cell carcinoma (HNSCC) is limited by the complex anatomy of the tumors and the associated risk of morbidity. Fundamental cellular processes including development, apoptosis [5], cell cycle control, proliferation [6] and DNA-damage repair [7] are influenced by miRNAs. During the last decade alterations in miRNA expression have been associated with a number of human diseases, including cancer (reviewed in [8]). The well described ‘onco-miR’ miR-21 has already been identified as a valuable plasma biomarker with high prognostic power in esophageal squamous cell carcinoma [13] and gastric cancer [14]

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Discussion

Conclusion