Identification and functional validation of miR-190b-5p and miR-296-3p as novel therapeutic attenuators of liver fibrosis.

BACKGROUND & AIMS: Liver fibrosis and its end-stage form known as cirrhosis contributes to millions of deaths annually. The lack of robust anti-fibrotic molecules is in part attributed to absence of any functional screens to identify molecular regulators using patient-derived primary human hepatic myofibroblasts, which are key drivers of fibrosis. METHODS: Here, to identify robust regulators of fibrosis, we performed functional microRNA screenings in primary human hepatic myofibroblasts followed by in vivo validation in three independent mouse models of fibrosis (toxin, cholestasis and MASH). RESULTS: We identified miR-190b-5p and miR-296-3p as robust anti-fibrotic miRNAs that suppress liver fibrosis. Notably, the expression of miR-190b-5p and miR-296-3p was found significantly reduced in human livers with fibrosis. Mechanistically, we discovered hyaluronan synthase 2 (HAS2) and integrin alpha-6 (ITGA6) as novel targets of miR-190b-5p and miR-296-3p, respectively. Furthermore, we demonstrated that the anti-fibrotic properties of miR-190b-5p and miR-296-3p are, at least in part, dependent on HAS2 and ITGA6. Finally, we showed the anti-fibrotic function of both miRNAs in a human liver bud model, which mimics multiple features of human liver. CONCLUSIONS: Collectively, in our study we discovered miR-190b-5p and miR-296-3p as two novel anti-fibrotic miRNAs, and that HAS2 and ITGA6 contribute to miR-190b-5p- and miR-296-3p-mediated inhibition of liver fibrosis. These results provide a foundation for future research to explore the clinical utility of miR-190b-5p and miR-296-3p in liver injuries with fibrosis. IMPACT AND IMPLICATIONS: Liver fibrosis and cirrhosis contribute to millions of deaths world-wide and, till date, remain as unmet medical needs. In this study, we discovered two microRNAs, miR-190b-5p and miR-296-3p, which suppress liver fibrosis in preclinical mouse models and a human liver bud model. Our promising results encourage further studies that aim to develop both miRNAs for the treatment of liver fibrosis in patients.

MicroRNAs modulate SARS-CoV-2 infection of primary human hepatocytes by regulating the entry factors ACE2 and TMPRSS2.

BACKGROUND AND AIMS: Severe acute respiratory syndrome coronavirus (SARS-CoV-2) preferentially infects the respiratory tract; however, several studies have implicated a multi-organ involvement. Hepatic dysfunctions caused by SARS-CoV-2 infection have been increasingly recognized and described to correlate with disease severity. To elucidate molecular factors that could contribute towards hepatic infection, we concentrated on microRNAs (miRNAs), a class of small non-coding RNAs that modulate various cellular processes and which are reported to be differentially regulated during liver injury. We aimed to study the infection of primary human hepatocytes (PHH) with SARS-CoV-2 and to evaluate the potential of miRNAs for modulating viral infection. METHODS: We analysed liver autopsies from a coronavirus disease 19 (COVID-19)-positive cohort for the presence of viral RNA using Nanopore sequencing. PHH were used for the infection with SARS-CoV-2. The candidate miRNAs targeting angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) were identified using in silico approaches. To discover the potential regulatory mechanism, transfection experiments, qRT-PCRs, western blots and luciferase reporter assays were performed. RESULTS: We could detect SARS-CoV-2 RNA in COVID-19-positive liver autopsies. We show that PHH express ACE2 and TMPRSS2 and can be readily infected with SARS-CoV-2, resulting in robust replication. Transfection of selected miRNA mimics reduced SARS-CoV-2 receptor expression and SARS-CoV-2 burden in PHH. In silico and biochemical analyses supported a potential direct binding of miR-141-3p to the SARS-CoV-2 genome. CONCLUSION: We confirm that PHH are susceptible to SARS-CoV-2 infection and demonstrate selected miRNAs targeting SARS-CoV-2 entry factors and/or the viral genome reduce viral loads. These data provide novel insights into hepatic susceptibility to SARS-CoV-2 and associated dysfunctions in COVID-19.

MicroRNA-342-3p is a potent tumour suppressor in hepatocellular carcinoma.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is a cancer with multiple aetiologies and widespread prevalence. Largely refractory to current treatments, HCC is the fourth leading cause of cancer-related deaths worldwide. MicroRNAs (miRNAs) are important regulators in HCCs. We aimed to identify tumour suppressor miRNAs during tumour regression in a conditional c-MYC-driven mouse model (LT2/MYC) of HCC, and to evaluate their therapeutic potential for HCC treatment. METHODS: We performed miRNA expression profiling of developed and regressing LT2/MYC tumours and in-depth in vitro gain- and loss-of-function analyses. The effect of adeno-associated virus (AAV) vector-mediated miR-342-3p treatment was evaluated in 3 HCC mouse models. RESULTS: We identified miR-342-3p as a tumour suppressor miRNA in HCC, with increased expression in regressing tumours. Forced miR-342-3p expression in hepatoma cells showed significantly decreased cell proliferation, migration, and colony formation. In vivo administration of AAV-miR-342-3p led to significant attenuation of tumour development and increased overall survival. We identified monocarboxylic acid transporter 1 (MCT1) as a bona fide target of miR-342-3p in HCC. We show that the tumour suppressor role of miR-342-3p is executed partly by modulating the lactate transport function of MCT1. Importantly, we find miR-342-3p downregulated in tumours from patients with HCC compared with matched non-tumour tissues, inversely correlating with MCT1 expression. We observed similar findings in TCGA-LIHC data. CONCLUSIONS: In our study, we identified and validated miR-342-3p as a tumour suppressor miRNA in HCC. We demonstrated its therapeutic efficacy in significantly attenuating tumour development, and prolonging survival, in different HCC mouse models. Identification of miR-342-3p as an effective tumour suppressor opens a therapeutic avenue for miRNA-mediated attenuation of HCC development. LAY SUMMARY: Hepatocellular carcinoma (HCC), the most common type of liver cancer, affects diverse populations and has a global impact, being the fourth leading cause of cancer deaths worldwide. There are currently no systemic therapies for HCC that can significantly prolong long-term survival. Thus, novel effective treatment options are urgently required. To understand the molecular basis of tumour regression, we compared tumours and regressing liver tumours in mice. We show that a small non-coding miRNA, miR-342-3p, is a tumour suppressor in HCC. Expression of miR-342-3p is low in tumours and high in regressing tumours. When miR-342-3p is delivered to mouse livers with HCC, it can significantly slow down liver tumour development and improve survival. Our study highlights the promising therapeutic potential of miR-342-3p intervention in HCC.

Therapeutic HNF4A mRNA attenuates liver fibrosis in a preclinical model.

BACKGROUND & AIMS: Therapeutic targeting of injuries that require transient restoration of proteins by mRNA delivery is an attractive approach that, until recently, has remained poorly explored. In this study, we examined the therapeutic utility of mRNA delivery for liver fibrosis and cirrhosis. Specifically, we aimed to demonstrate the therapeutic efficacy of human hepatocyte nuclear factor alpha (HNF4A) mRNA in mouse models of fibrosis and cirrhosis. METHODS: We investigated restoration of hepatocyte functions by HNF4A mRNA transfection in vitro, and analyzed the attenuation of liver fibrosis and cirrhosis in multiple mouse models, by delivering hepatocyte-targeted biodegradable lipid nanoparticles (LNPs) encapsulating HNF4A mRNA. To identify potential mechanisms of action, we performed microarray-based gene expression profiling, single-cell RNA sequencing, and chromatin immunoprecipitation. We used primary liver cells and human liver buds for additional functional validation. RESULTS: Expression of HNF4A mRNA led to restoration of the metabolic activity of fibrotic primary murine and human hepatocytes in vitro. Repeated in vivo delivery of LNP-encapsulated HNF4A mRNA induced a robust inhibition of fibrogenesis in 4 independent mouse models of hepatotoxin- and cholestasis-induced liver fibrosis. Mechanistically, we discovered that paraoxonase 1 is a direct target of HNF4A and it contributes to HNF4A-mediated attenuation of liver fibrosis via modulation of liver macrophages and hepatic stellate cells. CONCLUSION: Collectively, our findings provide the first direct preclinical evidence of the applicability of HNF4A mRNA therapeutics for the treatment of fibrosis in the liver. LAY SUMMARY: Liver fibrosis and cirrhosis remain unmet medical needs and contribute to high mortality worldwide. Herein, we take advantage of a promising therapeutic approach to treat liver fibrosis and cirrhosis. We demonstrate that restoration of a key gene, HNF4A, via mRNA encapsulated in lipid nanoparticles decreased injury in multiple mouse models of fibrosis and cirrhosis. Our study provides proof-of-concept that mRNA therapy is a promising strategy for reversing liver fibrosis and cirrhosis.

Hyaluronic Acid-Targeted Stimuli-Sensitive Nanomicelles Co-Encapsulating Paclitaxel and Ritonavir to Overcome Multi-Drug Resistance in Metastatic Breast Cancer and Triple-Negative Breast Cancer Cells.

Active targeting and overcoming multi-drug resistance (MDR) can be some of the important attributes of targeted therapy for metastatic breast cancer (MBC) and triple-negative breast cancer (TNBC) treatment. In this study, we constructed a hyaluronic acid (HA)-decorated mixed nanomicelles-encapsulating chemotherapeutic agent paclitaxel (PTX) and P-glycoprotein inhibitor ritonavir (RTV). HA was conjugated to poly (lactide) co-(glycolide) (PLGA) polymer by disulfide bonds (HA-ss-PLGA). HA is a natural ligand for CD44 receptors overexpressed in breast cancer cells. Disulfide bonds undergo rapid reduction in the presence of glutathione, present in breast cancer cells. The addition of RTV can inhibit the P-gp and CYP3A4-mediated metabolism of PTX, thus aiding in reversing MDR and sensitizing the cells toward PTX. An in vitro uptake and cytotoxicity study in MBC MCF-7 and TNBC MDA-MB-231 cell lines demonstrated the effective uptake of the nanomicelles and drug PTX compared to non-neoplastic breast epithelium MCF-12A cells. Interestingly, in vitro potency determination showed a reduction in mitochondrial membrane potential and reactive oxygen species in breast cancer cell lines, indicating effective apoptosis of cancer cells. Thus, stimuli-sensitive nanomicelles along with HA targeting and RTV addition can effectively serve as a chemotherapeutic drug delivery agent for MBC and TNBC.

Growth differentiation factor 11 attenuates liver fibrosis via expansion of liver progenitor cells.

OBJECTIVE: Liver fibrosis and cirrhosis resulting from chronic liver injury represent a major healthcare burden worldwide. Growth differentiation factor (GDF) 11 has been recently investigated for its role in rejuvenation of ageing organs, but its role in chronic liver diseases has remained unknown. Here, we investigated the expression and function of GDF11 in liver fibrosis, a common feature of most chronic liver diseases. DESIGN: We analysed the expression of GDF11 in patients with liver fibrosis, in a mouse model of liver fibrosis and in hepatic stellate cells (HSCs) as well as in other liver cell types. The functional relevance of GDF11 in toxin-induced and cholestasis-induced mouse models of liver fibrosis was examined by in vivo modulation of Gdf11 expression using adeno-associated virus (AAV) vectors. The effect of GDF11 on leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5)+ liver progenitor cells was studied in mouse and human liver organoid culture. Furthermore, in vivo depletion of LGR5+ cells was induced by injecting AAV vectors expressing diptheria toxin A under the transcriptional control of Lgr5 promoter. RESULTS: We showed that the expression of GDF11 is upregulated in patients with liver fibrosis and in experimentally induced murine liver fibrosis models. Furthermore, we found that therapeutic application of GDF11 mounts a protective response against fibrosis by increasing the number of LGR5+ progenitor cells in the liver. CONCLUSION: Collectively, our findings uncover a protective role of GDF11 during liver fibrosis and suggest a potential application of GDF11 for the treatment of chronic liver disease.

c-di-AMP Accumulation Impairs Muropeptide Synthesis in Listeria monocytogenes.

Cyclic di-AMP (c-di-AMP) is an essential and ubiquitous second messenger among bacteria. c-di-AMP regulates many cellular pathways through direct binding to several molecular targets in bacterial cells. c-di-AMP depletion is well known to destabilize the bacterial cell wall, resulting in increased bacteriolysis and enhanced susceptibility to cell wall targeting antibiotics. Using the human pathogen Listeria monocytogenes as a model, we found that c-di-AMP accumulation also impaired cell envelope integrity. An L. monocytogenes mutant deleted for c-di-AMP phosphodiesterases (pdeA pgpH mutant) exhibited a 4-fold increase in c-di-AMP levels and several cell wall defects. For instance, the pdeA pgpH mutant was defective for the synthesis of peptidoglycan muropeptides and was susceptible to cell wall-targeting antimicrobials. Among different muropeptide precursors, we found that the pdeA pgpH strain was particularly impaired in the synthesis of d-Ala-d-Ala, which is required to complete the pentapeptide stem associated with UDP-N-acetylmuramic acid (MurNAc). This was consistent with an increased sensitivity to d-cycloserine, which inhibits the d-alanine branch of peptidoglycan synthesis. Finally, upon examining d-Ala:d-Ala ligase (Ddl), which catalyzes the conversion of d-Ala to d-Ala-d-Ala, we found that its activity was activated by K+ Based on previous reports that c-di-AMP inhibits K+ uptake, we propose that c-di-AMP accumulation impairs peptidoglycan synthesis, partially through the deprivation of cytoplasmic K+ levels, which are required for cell wall-synthetic enzymes.IMPORTANCE The bacterial second messenger c-di-AMP is produced by a large number of bacteria and conditionally essential to many species. Conversely, c-di-AMP accumulation is also toxic to bacterial physiology and pathogenesis, but its mechanisms are largely undefined. We found that in Listeria monocytogenes, elevated c-di-AMP levels diminished muropeptide synthesis and increased susceptibility to cell wall-targeting antimicrobials. Cell wall defects might be an important mechanism for attenuated virulence in bacteria with high c-di-AMP levels.

Hepatocyte-specific suppression of microRNA-221-3p mitigates liver fibrosis.

BACKGROUND & AIMS: Fibrosis, a cardinal feature of a dysfunctional liver, significantly contributes to the ever-increasing mortality due to end-stage chronic liver diseases. The crosstalk between hepatocytes and hepatic stellate cells (HSCs) plays a key role in the progression of fibrosis. Although ample efforts have been devoted to elucidate the functions of HSCs during liver fibrosis, the regulatory functions of hepatocytes remain elusive. METHODS: Using an unbiased functional microRNA (miRNA) screening, we investigated the ability of hepatocytes to regulate fibrosis by fine-tuning gene expression via miRNA modulation. The in vivo functional analyses were performed by inhibiting miRNA in hepatocytes using adeno-associated virus in carbon-tetrachloride- and 3,5-di-diethoxycarbonyl-1,4-dihydrocollidine-induced liver fibrosis. RESULTS: Blocking miRNA-221-3p function in hepatocytes during chronic liver injury facilitated recovery of the liver and faster resolution of the deposited extracellular matrix. Furthermore, we demonstrate that reduced secretion of C-C motif chemokine ligand 2, as a result of post-transcriptional regulation of GNAI2 (G protein alpha inhibiting activity polypeptide 2) by miRNA-221-3p, mitigates liver fibrosis. CONCLUSIONS: Collectively, miRNA modulation in hepatocytes, an easy-to-target cell type in the liver, may serve as a potential therapeutic approach for liver fibrosis. LAY SUMMARY: Liver fibrosis majorly contributes to mortality resulting from various liver diseases. We discovered a small RNA known as miRNA-221-3p, whose downregulation in hepatocytes results in reduced liver fibrosis. Thus, inhibition of miRNA-221-3p may serve as one of the therapeutic approaches for treatment of liver fibrosis.

Concise review: cell therapies for hereditary metabolic liver diseases-concepts, clinical results, and future developments.

The concept of cell-based therapies for inherited metabolic liver diseases has been introduced for now more than 40 years in animal experiments, but controlled clinical data in humans are still not available. In the era of dynamic developments in stem cell science, the "right" cell for transplantation is considered as an important key for successful treatment. Do we aim to transplant mature hepatocytes or do we consider the liver as a stem/progenitor-driven organ and replenish the diseased liver with genetically normal stem/progenitor cells? Although conflicting results from cell tracing and transplantation experiments have recently emerged about the existence and role of stem/progenitor cells in the liver, their overall contribution to parenchymal cell homeostasis and tissue repair is limited. Accordingly, engraftment and repopulation efficacies of extrahepatic and liver-derived stem/progenitor cell types are considered to be lower compared to mature hepatocytes. On the basis of these results, we will discuss the current clinical cell transplantation programs for inherited metabolic liver diseases and future developments in liver cell therapy.

MicroRNA-199a-5p inhibition enhances the liver repopulation ability of human embryonic stem cell-derived hepatic cells.

BACKGROUND & AIMS: Current hepatic differentiation protocols for human embryonic stem cells (ESCs) require substantial improvements. MicroRNAs (miRNAs) have been reported to regulate hepatocyte cell fate during liver development, but their utility to improve hepatocyte differentiation from ESCs remains to be investigated. Therefore, our aim was to identify and to analyse hepatogenic miRNAs for their potential to improve hepatocyte differentiation from ESCs. METHODS: By miRNA profiling and in vitro screening, we identified miR-199a-5p among several potential hepatogenic miRNAs. Transplantation studies of miR-199a-5p-inhibited hepatocyte-like cells (HLCs) in the liver of immunodeficient fumarylacetoacetate hydrolase knockout mice (Fah(-/-)/Rag2(-/-)/Il2rg(-/-)) were performed to assess their in vivo liver repopulation potential. For target determination, western blot and luciferase reporter assay were carried out. RESULTS: miRNA profiling revealed 20 conserved candidate hepatogenic miRNAs. By miRNA screening, only miR-199a-5p inhibition in HLCs was found to be able to enhance the in vitro hepatic differentiation of mouse as well as human ESCs. miR-199a-5p inhibition in human ESCs-derived HLCs enhanced their engraftment and repopulation capacity in the liver of Fah(-/-)/Rag2(-/-)/Il2rg(-/-) mice. Furthermore, we identified SMARCA4 and MST1 as novel targets of miR-199a-5p that may contribute to the improved hepatocyte generation and in vivo liver repopulation. CONCLUSIONS: Our findings demonstrate that miR-199a-5p inhibition in ES-derived HLCs leads to improved hepatocyte differentiation. Upon transplantation, HLCs were able to engraft and repopulate the liver of Fah(-/-)/Rag2(-/-)/Il2rg(-/-) mice. Thus, our findings suggest that miRNA modulation may serve as a promising approach to generate more mature HLCs from stem cell sources for the treatment of liver diseases.

The degree of liver injury determines the role of p21 in liver regeneration and hepatocarcinogenesis in mice.

UNLABELLED: Hepatocellular carcinoma (HCC) frequently arises in the context of chronic injury that promotes DNA damage and chromosomal aberrations. The cyclin-dependent kinase inhibitor p21 is an important transcriptional target of several tumor suppressors, which promotes cell cycle arrest in response to many stimuli. The aim of this study was to further delineate the role of p21 in the liver during moderate and severe injury and to specify its role in the initiation and progression of HCC. Deletion of p21 led to continuous hepatocyte proliferation in mice with severe injury allowing animal survival but also facilitated rapid tumor development, suggesting that control of compensatory proliferation by high levels of p21 is critical to the prevention of tumor development. Unexpectedly, however, liver regeneration and hepatocarcinogenesis was impaired in p21-deficient mice with moderate injury. Mechanistically, loss of p21 was compensated by activation of Sestrin2, which impaired mitogenic mammalian target of rapamycin (mTOR) signaling and activated cytoprotective Nrf2 signaling. CONCLUSION: The degree of liver injury and the strength of p21 activation determine its effects on liver regeneration and tumor development in the liver. Moreover, our data uncover a molecular link in the complex mTOR, Nrf2, and p53/p21-signaling network through activation of Sestrin2, which regulates hepatocyte proliferation and tumor development in mice with liver injury.

MicroRNA-221 overexpression accelerates hepatocyte proliferation during liver regeneration.

UNLABELLED: The tightly controlled replication of hepatocytes in liver regeneration and uncontrolled proliferation of tumor cells in hepatocellular carcinoma (HCC) are often modulated by common regulatory pathways. Several microRNAs (miRNAs) are involved in HCC progression by modulating posttranscriptional expression of multiple target genes. miR-221, which is frequently up-regulated in HCCs, delays fulminant liver failure in mice by inhibiting apoptosis, indicating a pleiotropic role of miR-221 in hepatocytes. Here, we hypothesize that modulation of miR-221 targets in primary hepatocytes enhances proliferation, providing novel clues for enhanced liver regeneration. We demonstrate that miR-221 enhances proliferation of in vitro cultivated primary hepatocytes. Furthermore, applying two-thirds partial hepatectomy as a surgically induced liver regeneration model we show that adeno-associated virus-mediated overexpression of miR-221 in the mouse liver also accelerates hepatocyte proliferation in vivo. miR-221 overexpression leads to rapid S-phase entry of hepatocytes during liver regeneration. In addition to the known targets p27 and p57, we identify Aryl hydrocarbon nuclear translocator (Arnt) messenger RNA (mRNA) as a novel target of miR-221, which contributes to the pro-proliferative activity of miR-221. CONCLUSION: miR-221 overexpression accelerates hepatocyte proliferation. Pharmacological intervention targeting miR-221 may thus be therapeutically beneficial in liver failure by preventing apoptosis and by inducing liver regeneration.

Generation of healthy mice from gene-corrected disease-specific induced pluripotent stem cells.

Using the murine model of tyrosinemia type 1 (fumarylacetoacetate hydrolase [FAH] deficiency; FAH⁻/⁻ mice) as a paradigm for orphan disorders, such as hereditary metabolic liver diseases, we evaluated fibroblast-derived FAH⁻/⁻-induced pluripotent stem cells (iPS cells) as targets for gene correction in combination with the tetraploid embryo complementation method. First, after characterizing the FAH⁻/⁻ iPS cell lines, we aggregated FAH⁻/⁻-iPS cells with tetraploid embryos and obtained entirely FAH⁻/⁻-iPS cell-derived mice that were viable and exhibited the phenotype of the founding FAH⁻/⁻ mice. Then, we transduced FAH cDNA into the FAH⁻/⁻-iPS cells using a third-generation lentiviral vector to generate gene-corrected iPS cells. We could not detect any chromosomal alterations in these cells by high-resolution array CGH analysis, and after their aggregation with tetraploid embryos, we obtained fully iPS cell-derived healthy mice with an astonishing high efficiency for full-term development of up to 63.3%. The gene correction was validated functionally by the long-term survival and expansion of FAH-positive cells of these mice after withdrawal of the rescuing drug NTBC (2-(2-nitro-4-fluoromethylbenzoyl)-1,3-cyclohexanedione). Furthermore, our results demonstrate that both a liver-specific promoter (transthyretin, TTR)-driven FAH transgene and a strong viral promoter (from spleen focus-forming virus, SFFV)-driven FAH transgene rescued the FAH-deficiency phenotypes in the mice derived from the respective gene-corrected iPS cells. In conclusion, our data demonstrate that a lentiviral gene repair strategy does not abrogate the full pluripotent potential of fibroblast-derived iPS cells, and genetic manipulation of iPS cells in combination with tetraploid embryo aggregation provides a practical and rapid approach to evaluate the efficacy of gene correction of human diseases in mouse models.

"The Good, the Bad, and the Ugly" - About Diverse Phenotypes of Hepatic Stellate Cells in the Liver.

Hepatic stellate cells (HSCs) and their activated derivatives, often referred to as myofibroblasts (MFs), play a key role in progression of chronic liver injuries leading to fibrosis, cirrhosis, and hepatocellular carcinoma. Until recently, MFs were considered a homogenous cell type majorly due to lack of techniques that allow complex molecular studies at a single-cell resolution. Recent technical advancements in genetic lineage-tracing models as well as the exponential growth of studies with single-cell transcriptome and proteome analyses have uncovered hidden heterogeneities among the HSC and MF populations in healthy states as well as chronic liver injuries at the various stages of tissue deformation. The identification of different phenotypes along the HSC/MF axis, which either maintain essential liver functions ("good" HSCs), emerge during fibrosis ("bad" HSCs), or even promote hepatocellular carcinoma ("ugly" HSCs), may lay the foundation for targeting a particular MF phenotype as potential treatment for chronic liver injuries.

MicroRNA miR-20a-5p targets CYCS to inhibit apoptosis in hepatocellular carcinoma.

Hepatocellular carcinoma is a primary liver cancer, characterised by diverse etiology, late diagnoses, and poor prognosis. Hepatocellular carcinoma is mostly resistant to current treatment options, therefore, identification of more effective druggable therapeutic targets is needed. We found microRNA miR-20a-5p is upregulated during mouse liver tumor progression and in human hepatocellular carcinoma patients. In this study, we elucidated the therapeutic potential of targeting oncogenic miR-20a-5p, in vivo, in a xenograft model and in two transgenic hepatocellular carcinoma mouse models via adeno-associated virus-mediated miR-20a-Tough-Decoy treatment. In vivo knockdown of miR-20a-5p attenuates tumor burden and prolongs survival in the two independent hepatocellular carcinoma mouse models. We identified and validated cytochrome c as a novel target of miR-20a-5p. Cytochrome c plays a key role in initiation of the apoptotic cascade and in the electron transport chain. We show for the first time, that miR-20a modulation affects both these key functions of cytochrome c during HCC development. Our study thus demonstrates the promising 'two birds with one stone' approach of therapeutic in vivo targeting of an oncogenic miRNA, whereby more than one key deregulated cellular process is affected, and unequivocally leads to more effective attenuation of HCC progression and significantly longer overall survival.