MicroRNA Expression Profile Separates Squamous Cell Carcinoma by Mode of Differentiation

Squamous cell carcinoma (SCC) is a non-melanoma skin cancer with several risk factors including age and sun exposure. The degree of histological differentiation is considered an independent predictor of recurrence, metastasis, and survival. MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in regulating gene expression, culminating in the initiation and progression of multiple tumors. The aim of this study was to determine changes in miRNA expression as a result of the mode of differentiation in SCC.

We analyzed 29 SCC samples that were separated by mode of differentiation into well (n=4), moderate (n=20) and poor (n=5). Of the 29 samples, five had matched normal tissues, which were used as controls. Total RNA was extracted using the RNeasy FFPE kit, and miRNAs were quantified using Qiagen MiRCURY LNA miRNA PCR Assays. Ten miRNAs (hsa-miR-21, hsa-miR-146b-3p, hsa-miR-155-5p, hsa-miR-451a, hsa-miR-196-5p, hsa-miR-221-5p, hsa-miR-375, hsa-miR-205-5p, hsa-let-7d-5p and hsa-miR-491-5p) that have been previously differentiated in cancer, were quantified. A fold regulation above 1 indicated upregulation and below 1, downregulation.

Hierarchical clustering showed that the miRNA expression profile in the moderately differentiated group was similar to the well-differentiated group. The miRNA with the greatest upregulation in the moderate group was hsa-miR-375, while in the well group, hsa-miR-491-5p showed the greatest downregulation.

In conclusion, this study observed that the well and moderate groups had similar microRNA expression patterns compared to the poorly differentiated group. MicroRNA expression profiling may be used to better understand the factors underpinning mode of differentiation in SCC.