miRNA Signature of Hepatocellular Carcinoma Vascularization: How the Controls Can Influence the Signature.

Background: miRNA deregulation and vascular modifications constitute promising predictors in the study of hepatocellular carcinoma (HCC). In the literature, the relative miRNA abundance in HCC is usually determined using as control non-matched tumoral tissue, healthy liver, or cirrhotic liver. However, a common standard RNA control for the normalization toward the tissue gene expression was not settled yet.

Aim: To assess the differences existing in the quantitative miRNA gene expression in HCC on tissue according to two different liver controls.

Methods: A wide array of miRNAs was analyzed on 22 HCCs arisen in cirrhotic and non-cirrhotic livers by means of microfluidic cards. Control samples included total RNA extracted from healthy and cirrhotic livers. Immunohistochemistry for CD34 and Nestin was performed to assess the pattern of intratumoral vascular modifications.

Results: Six miRNAs were deregulated in HCCs using either controls: miR-532, miR-34a, miR-93, miR-149#, miR-7f-2#, and miR-30a-5p. Notably, the miRNA expression changed significantly between HCCs arisen in cirrhotic and non-cirrhotic livers, according to the control used for normalization. Different miRNA profiles were found also in HCCs with different vascular patterns, according to the control used for normalization.

Conclusions: Our data confirm that the choice of the methodology, and particularly the control used for normalization, represents the main concern in miRNA evaluation, particularly in a heterogeneous model such as liver pathology. Still we observed the deregulation of some common miRNAs as promising in HCC cancerogenesis and progression. A standardized control will be a crucial achievement to compare miRNA expression among different laboratories.