Sorafenib Response in Hepatocellular Carcinoma: MicroRNAs as Tuning Forks Shruthi Kanthajea, Ankita Makola, and Anuradha Chakrabortia*, a Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, India-160012 *Corresponding author Email: superoxide14@gmail.com Running title: miRNAs as regulators of sorafenib response in HCC Abstract: Hepatocellular carcinoma (HCC), the primary liver malignancy attributes towards the second foremost cause of cancer related mortality. The targeted chemotherapeutic agent, sorafenib is known to exhibit a statistically significant but limited overall survival advantage in advanced HCC. However, the individual patient response towards sorafenib varies drastically with most of them demonstrating stable disease (SD), few with partial response (PR) and very rare complete response (CR). Progressive disease (PD) despite the treatment has also been demonstrated in many patients indicating drug resistance. These varied responses have been linked with the modulation of several signaling pathways, intracellularly. Notably, the regulation of these pathways through diverse operating biomolecules including microRNAs (miRNAs) is studied recently. miRNAs are tiny, non-coding RNA molecules that regulate the expression of several target genes. Besides, miRNAs are known to have an evident role in HCC carcinogenesis to progression. Interestingly, miRNAs have also been identified to play This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/hepr.12991 This article is protected by copyright. All rights reserved. differential roles in terms of sorafenib response in HCC such as biomarkers, functional modulation of cellular response to sorafenib, hence, they are also being therapeutically evaluated. This review outlines the role of the reported miRNAs in different aspects of sorafenib response in HCC. Keywords: Hepatocellular carcinoma, microRNAs, resistance, sorafenib. Introduction: Hepatocellular carcinoma (HCC) is the prime cause of cancer related mortality next only to lung cancer and has mortality to incidence ratio of 0.95 indicating poor survival rates1. The disease is manageable in its initial stages with different curative treatment modalities including surgical resection, transplantation, loco-regional therapies like radio frequency ablation (RFA) or transarterial chemoembolization (TACE)2. However, HCC is typically asymptomatic in nature and when diagnosed, patients mostly present at advanced stages with poor hepatic reserve, hence are not suitable candidates for these therapies3. Conventional chemotherapy also exhibits limited survival benefit in case of metastatic HCC providing palliative care. Sorafenib is the only targeted therapy which shows a moderate survival benefit over supportive care during advanced stages of HCC4. However, different patients exhibit varied responses towards sorafenib and thus biomarkers to predict these responses as well as underlying mechanisms are the focus of research lately. A glance into the mechanistic aspect reveals the modulation of various signaling pathways which might be regulated by several biomolecules including microRNAs (miRNAs). Deregulation i.e. either up or down-regulation of various miRNAs has been reported in several in vitro, in vivo, and on patient studies demonstrating to be responsible for varied This article is protected by copyright. All rights reserved. sorafenib response. In this review, we summarize the role of miRNAs as biomarkers, regulatory molecules, and their therapeutic potential for sorafenib response in HCC. Micro RNAs (miRNAs): miRNAs are the small, non-coding, single stranded, evolutionarily conserved RNA molecules of 18-25 nucleotides, which regulate the expression of target genes. miRNAs have come a long way, from the first miRNA (lin-4) discovered in C. elegans5. They are expressed in different classes of life including viruses, bacteria, plants, and mammals6,7. In humans, miRNAs account for around 5% of the genome transcribing in 1,881 distinct miRNA molecules identified to date, regulating 30 – 80% of genes8-10. The generation of mature miRNA comprises of two steps, involving the synthesis of primary miRNA (pri-miRNA) which is cleaved inside the nucleus leading to the formation of precursor miRNA (pre-miRNA). This pre-miRNA is transported to the cytosol to generate mature miRNA which incorporates into RNA-induced silencing complex (RISC), negatively regulating the expression of its target mRNA. The silencing mechanism followed depends on the extent of complementarity between the miRNA and mRNA target which may lead to either degradation of target or inhibition at the translational level8,11. miRNAs have an evident role in several biological activities and pathological conditions including cancer12. Literature suggests, miRNA expression profiles vary significantly between non-tumor and tumor tissues, and are documented in various cancers13,14. However, the complex expression patterns of miRNAs specific to tissue type or differentiation state poses difficulties in the classification of miRNAs as oncogenes or tumor suppressors15. Additionally, multiple targets can be regulated by a single miRNA and single target gene can be modulated by several miRNAs16. Further, the modulated miRNA profiles as a cause or This article is protected by copyright. All rights reserved. consequence of cancer or an indirect effect of other altered cellular mechanisms are not always explicable17. Further, miRNAs are secreted from the host cells as a means of cell to cell communication18. Several studies have demonstrated that miRNAs are highly stable in body fluids (blood, saliva, urine, breast milk etc). These secreted miRNAs are often packed into exosomes/microvesicles, bound by high-density lipoprotein (HDL) or AGO2 protein. All these packed structures protect miRNAs from degradation and establish stability19,20. These circulating miRNAs are also differentially expressed in healthy and diseased states signifying their prominence in the field of biomarkers21, 22. Similarly, miRNAs affect drug response directly or indirectly by regulating the expression of genes involved in drug transportation, metabolism, and downstream signaling pathways. Further, single nucleotide polymorphisms (SNPs) in miRNA encoding genes may be responsible for inter-individual differences in drug response23. In the next section, the role of miRNAs in different aspects of sorafenib response in HCC is discussed. Sorafenib in HCC: Sorafenib is an oral multikinase inhibitor originally demonstrated to target Raf-1, wt BRAF, V599E mutant BRAF, VEGFR-2/3, Flt3, PDGFR-β, and c-KIT inhibiting both proliferation as well as angiogenesis24. Studies have also reported that RAF independent signaling pathways, particularly apoptotic and cell cycle progression pathways can also be targeted by sorafenib25,26. Till now, sorafenib has been established as an FDA approved treatment alternative for advanced stages of renal cell carcinoma (2005), HCC (2007), and thyroid cancer (2013)27-29. The applicability of sorafenib was recognized by two global placebo controlled clinical trials: sorafenib hepatocellular carcinoma assessment randomized protocol This article is protected by copyright. All rights reserved. (SHARP) and Asia-Pacific (AP) which demonstrated 2.8 months and 2.3 months of absolute enhancement in survival over placebo respectively28, 30. Further, the outcome of sorafenib has been assessed for a broader population, in a worldwide, non-interventional study of patients with unresectable HCC, global investigation of therapeutic decisions in hepatocellular carcinoma and of its treatment with sorafenib (GIDEON) which involved >3000 patients from around 39 countries. The preliminary results of this study indicated that Child-Pugh class A (CP-A) cirrhotic patients treated with sorafenib had similar outcomes to that of the SHARP trial, and second interim analysis established that both CP-A, as well as CP-B patients had similar sorafenib safety profiles31,32. However, the individual patient response towards sorafenib varies drastically as reported in SHARP trials; 2% of patients had a partial response (PR), 71% had stable disease (SD) and according to AP trials; 3.3% had PR, 54% had SD, and 46% had progressive disease (PD)28,30. This implies that appreciably higher number of patients treated with sorafenib experience HCC progression and complete response (CR) is very rare33-35. One of the explanations for these varied responses may be genetic heterogeneity of HCC patients36. Many other mechanisms also account for this observed response such as switching to compensatory pathways, epithelial-mesenchymal transition (EMT), tumor stem cells, hindering pro-apoptotic signals, tumor microenvironment etc37. Interestingly, different biomolecules including miRNAs have been studied recently for their role in the regulation of these mechanisms. Next sections of the review summarize the global miRNA profiling studies, miRNAs as sorafenib response biomarkers, the mechanistic aspect, and therapeutic potential of miRNAs for sorafenib response in HCC. miRNA profiling studies: Advances in high throughput techniques have improved our understanding of transcriptome status including miRNAs and their target genes expression profile. These profiling studies of This article is protected by copyright. All rights reserved. tumor samples have shown to serve as signature profiles for particular cancer, different stages of cancer or response to treatment. Several miRNA profiling studies have been performed in HCC cell lines, in vivo and on patients of HCC to elucidate the role of miRNAs in response to sorafenib. Initially, Zhou et al., conducted expression profiling of 754 miRNAs in HepG2 cells treated with two different concentrations of sorafenib and found 12 significantly up-regulated along with 2 downregulated miRNAs38. He et al., and Tang et al., performed miRNA microarray (754 miRNAs) in parental and sorafenib resistant Huh7 cell lines. They found that 16 miRNAs were significantly higher and 8 miRNAs were lower in Huh7-SR cells39,40. Further, in another study, miRNA PCR array for 940 human miRNAs in Huh7 and PLC/PRF/5 (parental and sorafenib resistant) cell lines was performed. The authors found that 31 miRNAs were elevated and 30 were alleviated in resistant cells41. 14 miRNAs were found to be commonly deregulated in at least 2 studies (miR-30a-3p, miR-219-1-3p, miR-548c-5p, miR-664, miR1260, miR-1274a, miR-1290, miR-1291, miR-222, miR-10a, miR-34a, miR-195, miR-7, and miR-548b-5p). Out of 14 miRNAs, 12 miRNAs were found to be deregulated in the same direction in at least two studies. There are two in vivo studies on miRNA profiling till now in relation to sorafenib therapy for HCC. One study was conducted to understand the mechanistic basis of sorafenib resistance in vivo and miRNA profiling was performed as a part of the study in orthotopic mouse models of HCC with sorafenib resistance. They have listed the deregulated miRNAs under four major pathways: axonal guidance, EMT, STAT3, and Wnt signaling42. Another study was done in ACI rats with primary HCC and lung metastasis after sorafenib treatment, revealed that miR-383 and miR-34 were up-regulated and miR-122 as well as one novel miRNA was down-regulated43. This is the only study where the miRNAs were mapped to rat miRNA This article is protected by copyright. All rights reserved. rather than human miRNA database. The details of above deregulated miRNAs can be found in table 1. Further, Vaira et al., analyzed miRNA expression in tissue samples isolated from HCC patients pre-treatment of sorafenib and performed a follow up for the response. A total of 700 mature miRNAs were analyzed using miRNA microarray and found 35 miRNAs associated with time to progression (TTP) and progression free survival (PFS), while 25 miRNAs were associated with overall survival (OS)44. Oberhag et al., also performed miRNA expression profiling of 818 miRNAs in FEPE liver biopsy samples of 19 HCC patients treated with sorafenib. However, they did not observe any statistically significant results in their small cohort of subjects45. Comparing all in vitro, in vivo and on patient miRNA profiling studies, miR-34a was found to be up-regulated in at least 3 studies38,41,43 and miR-122 was down-regulated in two studies41,43 during sorafenib resistance. Further miR-1290 was found to be differentially regulated in at least 4 studies38,40-42, however, the direction of deregulation observed was not the same. miRNAs play a central role as regulatory molecules, thus miRNA expression signatures can be extremely useful in predicting and understanding drug response when carried out in large cohorts. miRNAs as biomarkers: Tissue biomarkers are of particular significance as they can be very specific to the disease of interest and carry contextual information pertaining to the disease46. miRNAs as tissue biomarkers have been assessed in two different studies in the context of sorafenib response in HCC. A study was conducted on fine needle aspiration biopsy (FNAB) samples from 20 This article is protected by copyright. All rights reserved. HCC patients before the treatment of sorafenib for 14 commonly deregulated miRNAs in HCC. The follow-up study unveiled that an elevated expression of miR-224 was coupled with increased PFS and OS47. Similarly, in another study performed in liver biopsy samples of HCC patients collected prior to sorafenib treatment, demonstrated increased levels of miR425-3p predictive of extended TTP and PFS44. Although tissue biomarkers have ameliorated diagnosis and also survival of cancer patients to a great extent, it is limited by its invasiveness and burdensome procedures48. Previously, it was discovered that miRNAs are secreted extracellularly into the bloodstream and these circulating miRNAs possess outstanding stability, raising possibilities of their potential as diagnostic biomarkers49. Yamamoto et al., were the first to demonstrate the deregulation of miRNAs in HCC patient’s sera50. Lately, several studies have established the differential levels of circulating miRNAs in different aspects of HCC including sorafenib response. Nishida et al., conducted a study to clarify the role of 179 known secretory miRNAs in the sera of HCC patients to predict the early response to sorafenib treatment. They found that the patients with PR had the highest and those with PD had the lowest levels of two miRNAs (miR-181a-5p and miR-339-5p)51. Further, Yoon et al., performed a study to identify pretreatment circulatory miRNA levels of miR-21, miR-18a, miR-221, miR-139-5p, miR-224, and miR-10b-3p in association with positive radiological responses in sorafenib treated HCC patients (n=24). It was found that miR-10b-3p was up-regulated in HCC patients with significantly shorter survival after the treatment of sorafenib. However, this study did not find a significant association of any miRNAs with the non-responders and responders for sorafenib52. Similarly, in another study, the expression of miR-423-5p was estimated in the sera of 39 HCC patients before and after the treatment of sorafenib. An increased expression of miR-423-5p was observed after sorafenib treatment and 75 % of these patients recorded an This article is protected by copyright. All rights reserved. SD or PR53. The list of miRNAs as biomarkers for sorafenib response in HCC can be seen in table 2. Thus, miRNAs as circulating biomarkers is an upcoming area of research in the field of diagnosis and prognosis of cancer. Further, the above studies bring out the fact they could also be used to predict and monitor the efficacy of anticancer treatments. miRNAs influencing sorafenib response and their mechanism of action: Several experimental evidences suggest the regulatory role of different miRNAs in the modulation of drug response related genes and drug target genes 54. This section summarizes the different signaling pathways affecting sorafenib response in HCC and the influence of different miRNAs on the same (Figure 2). miRNAs increasing sorafenib sensitivity: Various studies have reported different miRNAs and the mechanism by which they increase the sensitivity of HCC cells to sorafenib. Of all miRNAs, miR-122, the highest expressed miRNA in normal liver, is most studied in this perspective55. miR-122 is significantly decreased in sorafenib resistant HCC cells and over-expression of the same can enhance sorafenib sensitivity41. The mechanisms include, negative regulation of insulin like growth factor 1 receptor (IGF-1R), serum response factor (SRF), and disintegrin and metalloproteinase domain-containing protein 10 (ADAM10)48,56, inhibition of stemness via regulating glycolysis through targeting pyruvate dehydrogenase kinase 4 (PDK4)57, targeting solute carrier family 7 member 1 (SLC7a1), a transporter of arginine thereby increasing intracellular arginine levels resulting in apoptosis58, and increasing the apoptosis specifically in hepatitis B virus (HBV) infected HCC cells by targeting polypeptide Nacetylgalactosaminyltransferase 10 (GALNT10)59. Similarly, miR-34a is a negative regulator This article is protected by copyright. All rights reserved. of neurogenic locus notch homolog protein 1 precursor (NOTCH-1) signaling pathway and may be involved in increasing sorafenib sensitivity. Notch-1 signaling pathway promotes cell survival and impedes apoptotic signals and increased expression of the same is said to reduce sorafenib activity60. Additionally, the same miRNA was demonstrated to target B-cell lymphoma 2 (BCL2) and sensitize human HCC cells to sorafenib treatment61. Further, certain miRNAs like miR-27b, miR-193b, and let-7 are known to modulate different pathways involved in apoptosis thereby increasing sorafenib sensitivity. miR-27b regulates P53 dependent apoptosis62, let-7 negatively regulates B-cell lymphoma-extra large (BCL-XL) expression63 and miR-193b is known to target anti- apoptotic protein myeloid leukemia cell differentiation protein (MCL1)64. Interestingly, miR-193b is specifically demonstrated to sensitize HBV infected HCC cells to sorafenib and full length hepatitis C virus (HCV) is shown to increase its expression64,65. Moreover, miR-486 and miR-367-3p regulate cell proliferation and invasion via targeting CITRON, Claudin10 (CLDN10) and androgen receptor signals thus increasing the efficacy of sorafenib66,67. Apart from these mechanisms few miRNAs also exploit other cellular pathways to increase sorafenib sensitivity. miR-3383p sensitizes HCC cells to sorafenib in vitro and in mice models possibly by directly targeting hypoxia inducing factor α (HIF1α) and hence increasing the cell death68. Likewise, up-regulation of miR-137 targets adenine nucleotide translocator 2 (ANT2) in HCC enhancing sorafenib sensitivity and alters cancer initiating cell phenotypes69. Further, sorafenib can also alter the expression of certain miRNAs. Sorafenib slows down macrophage driven HCC growth by alleviating the expression of miR-101 resulting in the reduced tumor growth factor β (TGF-β) and mannose receptor c type 1, CD206 release in M2 cells and up-regulation of dual specificity protein phophatase 1 (DUSP1) expression70. Sorafenib elevates miR-423-5p which further increases the effectivity of sorafenib by This article is protected by copyright. All rights reserved. inducing autophagy and decreasing cell proliferation53. miR-1274a is up-regulated in HCC cells treated with sorafenib, and it targets ADAM9 gene and hence increases antitumor immunity and sorafenib activity38. Sorafenib also increases cellular expression of miR-125a inhibiting cell proliferation by suppressing sirtuin-7, a NAD(+)-dependent deacetylase71. miRNAs decreasing sorafenib sensitivity: In contrast to above studies, there are several miRNAs which act conversely and decrease sorafenib sensitivity. PI3K/ AKT pathway is the most studied compensatory pathway, activation of which has been linked to sorafenib resistance. Various miRNAs like miR-21, miR-153, miR-10a-5p, miR-216a, miR-217, miR-93, and miR-494 are reported to target phosphatase and tensin homolog, PTEN, thereby accelerating PI3K/AKT pathway and influencing autophagy positively resulting in sorafenib resistance39,40,72-75. Besides, few of these miRNAs like, miR-93 also targets cyclin dependent kinase 1A (CDKN1A) inhibiting apoptosis74 and miR-216/217a also acts as a positive feedback regulator of TGF-β pathway75. Further, miR-379 is known to increase the expression of multi drug resistant protein (MRP2) thereby influencing the drug transport which may be one of the reasons of sorafenib resistance76. miR-181 targets ras association domain containing protein1 (RASSF1) of MAPK pathway and reduces the sensitivity of sorafenib77. From the above studies it is clear that through modulation of several cellular mechanisms miRNAs may serve to increase/decrease the efficacy of sorafenib. This suggests that some of these miRNA may hold a therapeutic potential to boost sorafenib response in HCC patients. Therapeutic potential of miRNAs: There are no studies to our knowledge which have tested the therapeutic potential of miRNAs in relation to sorafenib response in HCC, clinically. However, there are few reports in which This article is protected by copyright. All rights reserved. miRNAs have been modulated directly (in vivo) or indirectly (in vitro/in vivo) to increase the efficacy of sorafenib. In this regard, Tang et al., used AD5-lncRNA encoding antisense regions for 6 miRNAs (miR-21, miR-216a, miR-153, miR-494, miR-217, and miR-10a-5p). This was the first attempt to target multiple miRNAs and this enhanced the effect of sorafenib in animal models reducing tumor weight by 43.6%40. In another study, miR-122 packaged in exosomes of miR122 treated adipose tissue derived mesenchymal stem cells (MSCs), increased chemosensitivity of sorafenib in vitro and in vivo78. Further, anti-miR-21 oligonucleotides tested in animal models, significantly reduced tumor size by 51.5% and combinational therapy of sorafenib with the same resulted in a further reduction of tumor size by 74.5%39. Additionally, miR-27b encapsulated in liposomes was found to enhance drug response in HCC for both doxorubicin and sorafenib in vivo62. Further, certain nutrients and chemicals have been shown to enhance the expression of certain miRNAs which in turn can increase the sorafenib response. Rhamnetin, a flavonoid from sea buckthorn, acts as a promising sensitizer of sorafenib and overcomes multi drug resistance in HCC by regulating miR-34 and NOTCH1 expression60. Chemical compounds such as PD407824 (wee1-kinase inhibitor) and ellipticine (DNA topoisomerase inhibitor) were used in Hep3B cells to enhance miR-122 and increase sorafenib sensitivity58. Similarly, matrine (alkaloid in chinese medicine) along with sorafenib via suppressing miR-21 leads to enhanced cytopathic effects against HCC cells72. Conclusion: Sorafenib remains the primary choice of targeted therapy for the management of advanced HCC. Hence, understanding the mechanisms of soarfenib response and resistance is This article is protected by copyright. All rights reserved. important to improve the survival of HCC patients. miRNAs as a prominent family of gene regulators, are implicated to have a paramount role in various physiological and pathological conditions. Thus, critical comprehension of miRNAs and their target genes may improve our current understanding of several intricate mechanisms in carcinogenesis, metastasis, and specifically sorafenib response in HCC. However, as most of the existing reports are either in vitro or in vivo, further studies are required to be performed in patients, especially in large cohorts before miRNAs can become a part of therapeutics clinically. Acknowledgement: We acknowledge Indian council of medical research (ICMR), India for providing senior research fellowship (SRF) to SK and AM. 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This article is protected by copyright. All rights reserved. Figure 1: Signaling pathways involving microRNAs effecting sorafenib response in HCC. miRNAs increasing the senitivity of sorafenib; miRNAs decreasing the senitivity of sorafenib This article is protected by copyright. All rights reserved. S. No 1 Source Discription Method HepG2 cell Treated (0.05µM and 1µM) versus untreated MiRNA PCR array (Applied Biosystems) 2 Huh-7 Parental versus resistant 3 Huh-7 Parental versus and resistant PLC/PRF 5 4 CB17 SCID mouse model Control, sensitive and late resistant tumor 5 ACI rats Primary HCC tumors versus metastatic lung tumors Deregulated miRNAs miR-30a-3p, miR-194, miR-219-1-3p, miR-522, miR-548c-5p, miR-629, miR664, miR-1260, miR-1274a/b, miR1290, miR-1291 (↑); miR-222, miR548-5p (↓) MiRNA Let-7b/c, miR-10a/b-5p, miR-34a, miRPCR array 21, miR-30a-3p, miR-195, miR-216a, (Applied mir-219-1-3p, mir-223, miR-616, miRBiosystems) 664, miR-1260, miR-1274a, miR-1281 (↑); miR-17-5p, miR-18a, miR-133b, miR222, miR328, miR-548b-5p, miR-6755p, miR-1290 (↓) miRNA miR-502-3p, miR-10a, miR-195, miRmicroarray 105, miR-29a, miR-625, miR-10b, miR(Agilent 181a, mir-34a, miR-126, miR-361-3p, technologies) miR-22*, miR-34b, miR-186, miR1290, mir-151-5p, miR-22, miR-222, miR-582-5p, mir-423-5p, miR-224, miR-371-5p, miR-140-5p, miR-29a/b, mir-424, miR-1181, miR-455-3p, miR874, miR-96, miR-140-3p (↑); miR-101, miR-130b, miR-923_v12.0, miR-99b, miR-324-5p, miR-29b-1*, miR-1914*, miR-20a, miR-30a*, miR1207-5p, miR-188-5p, miR-93, miR122, miR-1225-5p, miR-20b, miR-17, miR-484, miR-483-5p, miR-18b, miR-7, miR-1202, miR-18a, miR-636, miR19b-1*, miR-421, miR-1229, miR-92a1*, miR-1288, miR-622, miR-431* (↓) miRNA miR-106a-5p, miR-141-3p, miR-143-3p, sequencing miR-181d-5p, miR-192-5p, miR-194-5p, (Hi-SeqmiR-199b-5p, miR-2467-3p, miR-323a2500 3p, miR-34c-5p, miR-3609, miR-362Illumina, 5p, miR-410-3p, miR-1292-5p, miRCA) 1290, miR-4421 miRNA deep sequencing miR-383-5p, miR-34a-5p (↑); (Hi-Seq miR-122-3p/5p, novel_miR_59(↓) 2000 BGI, China) Reference Zhou et al., FEBS letter, 201138 Tang et al., oncotarget, 201640 He et al., oncotarget, 201539 Xu et al., Cancer letters, 201641 Kuczynski et al., J Natl Cancer Inst, 201642 Shi et al., Tumor Biol, 201543 Table 1: miRNA global profiling studies in vitro and in vivo; [(↑): up-regulated; (↓): down-regulated)] This article is protected by copyright. All rights reserved. miRNA Up/downregulation Sample details Significance Reference miR-224 Up FNAB samples; n=20; samples collected before the treatment of sorafenib and followup Predictive of increased PFS and OS Gyongyosi et al., 2014 miR-425-3p Up Liver biopsy; Predictive of n=26(training set); extended TTP n=58 (validation set) ; and PFS samples collected before the treatment of sorafenib and followup Vaira et al., 2015 miR-181a-5p and miR-3395p Up(PR);down(PD) Serum; n=16;(training Predictive of set); n=53(validation PR and PD set); samples collected before the treatment of sorafenib and followup Nishida et al., 2017 miR-10b-3p up Serum; n=24; samples collected before the treatment of sorafenib and followup Predictive of shorter survival Yoon et al., 2017 miR-423-5p Up (after the treatment of sorafenib) Serum; n=39; samples collected before and after treatment of sorafenib and followup Predictive of SD or PR Stiuso et al., 2015 Table 2: miRNAs as biomarkers for sorafenib response in HCC [FNAB: fine needle aspiration biopsy; PFS: progression free survival; OS: overall survival; TTP: time to progression; PR: partial response; PD: progressive disease; SD: stable disease] This article is protected by copyright. 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