Abstract
BackgroundHumans and dogs are affected by squamous cell carcinomas of the oral cavity (OSCC) in a considerably high frequency. The high mobility group A2 (HMGA2) protein was found to be highly expressed in human OSCC and its expression was suggested to act as a useful predictive and prognostic tool in clinical management of oral carcinomas. Herein the expression of HMGA2 and its sister gene HMGA1 were analysed within human and canine OSCC samples. Additionally, the HMGA negatively regulating miRNAs of the let-7 family as well as the let-7 regulating gene Lin28 were also comparatively analysed. Deregulations of either one of these members could affect the progression of human and canine OSCC.MethodsExpression levels of HMGA1, HMGA2, Lin28, let-7a and mir-98 were analysed via relative qPCR in primary human and canine OSCC, thereof derived cell lines and non-neoplastic samples. Additionally, comparative HMGA2 protein expression was analysed by immunohistochemistry.ResultsIn both species, a significant up-regulation of the HMGA2 gene was found within the neoplastic samples while HMGA1 expression did not show significant deregulations. Comparative analyses showed down-regulation of mir-98 in human samples and up-regulation of let-7a and mir-98 in canine neoplastic samples. HMGA2 immunostainings showed higher intensities within the invasive front of the tumours than in the centre of the tumour in both species.ConclusionsHMGA2 could potentially serve as tumour marker in both species while HMGA1 might play a minor role in OSCC progression. Comparative studies indicate an inverse correlation of HMGA2 and mir-98 expression in human samples whereas in dogs no such characteristic could be found.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-694) contains supplementary material, which is available to authorized users.
Highlights
Humans and dogs are affected by squamous cell carcinomas of the oral cavity (OSCC) in a considerably high frequency
In our study we investigated the expression levels of HMGA1, high mobility group A2 (HMGA2), Lin28, let-7 a and mir-98 via relative real time PCR in human and canine non-neoplastic and tumour tissue samples and human and canine cell lines which derived from primary OSCCs
The characterised high HMGA2 expression in the neoplastic samples of both species, affirms the findings by Miyazawa et al [11] reporting HMGA2 over-expression of 84-315-fold in analysed carcinoma tissues when compared to non neoplastic tissues [11]
Summary
Humans and dogs are affected by squamous cell carcinomas of the oral cavity (OSCC) in a considerably high frequency. Men develop twice as frequent oral cancer than women and more than 95% of the carcinomas are of the squamous cell type. Male dogs have a 2.4 times higher risk of developing oropharyngeal malignancies compared to female dogs and the tumours are staged to those in humans but only 17-25% of the carcinomas are of the squamous cell type [3]. Surgery and radiation are the most common treatment modalities resulting in estimated overall 5-years survival rates for cancers of the oral cavity/ pharynx and larynx between 58.3% and 64.5% [4,5,6]
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