Abstract 587: MicroRNA expression in saliva in locally advanced oral and oropharyngeal squamous cell carcinoma
Authors: Fabyane Oliveira Teixeira Garcia, Vivian Marinelli Constantino, Milena Perez Mak, Gilberto de Castro-Jr, Fatima S. Pasini
Journal: Cancer Research (2015)

Abstract Background: Oral cavity/oropharynx squamous cell carcinoma (OSCC) is a common cancer in the developing world. Most patients (pts) present with inoperable locally advanced disease, which yields low cure and disease-free survival rates. Concurrent high-dose cisplatin chemoradiation (CRT) is the standard treatment for such pts in our institution. Although this regimen provides high response rates, marked toxicity is observed and relapses are frequent. In light of that, candidate markers for appropriate patient selection are needed to improve OSCC outcomes. There is evidence that miRNAs (miRs) play a key role in resistance to chemotherapy and radiotherapy. However, the role of miRNAs in chemoresistance in OSCC remains poorly elucidated. In the present study we analyzed the expression of miRNAs in the saliva of unresectable locally advanced OSCC pts either before or after CRT. Our goal was to identify miRNAs related to long-term response to CRT with concurrent cisplatin, and also to verify whether circulating miRs are contained within exosomes or circulating free in the saliva. Patients/methods: A total of 33 OSCC pts were included in three groups: (1) treatment-naïve (N = 16), (2) after treatment failure (disease progression after CRT - N = 7), and (3) disease-free pts for at least 2 years (N = 10). We also studied saliva of eight healthy volunteers. Following a review of studies in the literature that microRNAs associated with chemoradiotherapy in squamous cell carcinoma, the miR-21-5p, miR-15a-5p, miR-200b-3p and miR-296-5p were chosen to be analyzed by qRT-PCR, using LNA™ primers set (Exiqon). The spike-in Sp6 miRNA was added to saliva samples to control of variation in RNA recovery and the miR-16-5p was for normalization of sample-to-sample RNA variation. The Mann-Whitney U and Kruskal Wallis tests were used to compare the sample groups. Results: The miR-296-5p expression was below the detection level in almost all saliva samples and was excluded from further analyses. As compared to the healthy volunteers group, both samples from pts in groups 1 and 3 showed an increased expression of miR-21-5p, miR-15a-5p, miR-200b-3p. Significant reduction of the expression of miR-21-5p and miR-200b-3p (p = 0.01 and 0.08) was observed in group 2 patients, as compared to group 1. Furthermore, the expression of these two miRNAs was higher in group 3 pts compared to group 2 (p = 0.01). Transmission electron microscopic preliminary data of isolated microvesicles exhibited round vesicles measuring 30-60 nm in diameter, compatible with the size of exosomes. Conclusion: Changes in the abundance of circulating miR-21-5p and miR-200b-3p, previously reported as crucial modulators of stemness and Head and Neck SCC progression, may be associated with long-term response to cisplatin-based CRT. Supported by Fundação de Amparo a Pesquisa (FAPESP 2013/25397-0). Citation Format: Fabyane Oliveira Teixeira Garcia, Vivian Marinelli Constantino, Milena Perez Mak, Gilberto de Castro-Jr, Fatima S. Pasini. MicroRNA expression in saliva in locally advanced oral and oropharyngeal squamous cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 587. doi:10.1158/1538-7445.AM2015-587