Expressão e regulação do gene VEGFA por microRNAs em cirrose hepática e carcinoma hepatocelular

Abstract

Hepatocellular carcinoma (HCC) is a primary liver tumor and the sixth most common type of cancer. Liver cirrhosis (LC) and viral hepatitis are their main risk factors. Injured tissues and development process tissues need new blood vessels, i. e., angiogenic process, that initiates by means of vascular endothelial growth factors secretion, that is translated by VEGFA gene and regulated by non-coding RNA, miRNA, that consists of a single strand of approximately 22 nucleotides and has the function of binding to mRNA strand, to inhibit protein translation. Objectives: To quantify VEGFA gene expression and 17 miRNAs predicted as its regulator in HCC and liver cirrhosis; to assess VEGFA gene expression in relation to miRNAs expression and quantify VEGFA protein expression in HCC and liver cirrhosis tissues. Patients and methods: Sixteen samples of HCC tissue, 23 samples of liver cirrhosis tissue and 12 samples of normal liver tissue were collected. Total RNA and proteins were isolated by mirVana PARIS kit. VEGFA gene mRNA quantification and 17 miRNAs predicted as regulators expression was performed by real time quantitative PCR. Customized plates, TaqMan miRNA custom plate, were used for miRNAs. Statistical analysis was performed by one sample t test, Wilcoxon tests and Mann-Whitney test. Results: VEGFA gene expression was found downregulated in HCC and there is negative correlation between gene expression and tumor extension. MicroRNA hsa-miR-637 has showed significance and was down-regulated on samples (mean 0.2003, p=0.0004) in LC, whereas miRNAs hsa-miR-15b (median 0.04015; p=0.0005), hsa-miR-125b (median 0.01876; p=0.0005), hsa-miR-423 (median 0.02650; p=0.0005), hsa-miR-424 (median 0.00462; p=0.0156), hsa-miR-494 (median 0.00877; p=0.0010), hsa-miR-497 (median 0.04487; p=0.0005), hsa-miR-612 (median 0.00679; p=0.0039) and hsamiR-637 (median 0.00166; p=0.0039) are down-regulated in HCC. Conclusions: VEGFA gene expression is down-regulated in HCC. MicroRNA hsa-miR-637 is down-regulated in LC. MicroRNAs hsa-miR-15b, hsa-miR-125b, hsa-miR-423, hsa-miR-424, hsa-miR-494, hsa-miR-497, hsa-miR-612 e hsa-miR-637 are down-regulated in HCC. VEGFA protein expression is low in HCC, corroborating to gene expression found in HCC.