| Popis: |
Liver disease has continued to rise in the United States and often progresses to late-stage hepatocellular carcinoma (HCC). With limited therapeutic options for patients with HCC, a better understanding of molecular signatures that contribute to disease progression are necessary. miR-122 is a conserved and liver-specific miRNA that maintains metabolic homeostasis, suppresses tumor development, and promotes HCV replication. Loss of miR-122 promotes a loss of hepatic phenotype, a gain of malignancy-associated features, and poor patient prognosis in hepatocellular carcinoma (HCC) patients. Recent in vivo work in the miR-122 knockout (KO) mice have established miR-122 as a bona fide tumor suppressor. We hypothesize that miR-122 targets in mice and humans contribute to the malignant phenotype, maintain liver homeostasis, and have therapeutic potential. However, the miR-122 regulatory network of direct targets had not been previously mapped. To biochemically map the miR-122-Ago landscape in mice and humans, we performed Argonaute cross-linking and immunoprecipitation (Ago-CLIP) sequencing in miR-122 knockout and control mouse livers, as well as in matched human hepatocellular carcinoma (HCC) and benign liver tissue. We identified ~965 miR-122 targets conserved in both mice and humans. A majority of these targets were dysregulated in the livers of miR-122 KO mice and tumors of patients with low levels of miR-122 obtained from Liver and Hepatocellular Carcinoma (LIHC) of The Cancer Genome Atlas (TCGA). Therefore, in this dissertation, we focused on mapping and characterizing select key targets in hopes of extracting their therapeutic potential in liver disease. We found that miR-122 is associated in the regulation of pathways such as Hippo Signaling, Wnt/β-catenin pathway, Pentose Phosphate Pathway, and RNA metabolism, all indicative of a malignant phenotype.Collectively showing that performing Ago-CLIP in matching tissues that differentially express miRNAs is an effective strategy to identify novel targets for therapeutic investigation. We also found that this can be expanded on when focusing on targets conserved among species. In summary, our analysis identified critical targets involved in liver homeostasis and revealed a miR-122 target-signature predictive in human liver disease and HCC. |
