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Background and aims Transarterial chemoembolization (TACE) is a standard locoregional therapy for patients with hepatocellular carcinoma (HCC) patients with a variable overall response in efficacy. We aimed to identify key molecular signatures and related pathways leading to HCC resistance to TACE, with the hope of developing effective approaches in preselecting patients with survival benefit from TACE. Approach and results Four independent HCC cohorts with 680 patients were used. MicroRNA (miRNA) transcriptome analysis in patients with HCC revealed a 41-miRNA signature related to HCC recurrence after adjuvant TACE, and miR-125b was the top reduced miRNA in patients with HCC recurrence. Consistently, patients with HCC with low miR-125b expression in tumor had significantly shorter time to recurrence following adjuvant TACE in two independent cohorts. Loss of miR-125b in HCC noticeably activated the hypoxia inducible factor 1 alpha subunit (HIF1α)/pAKT loop in vitro and in vivo. miR-125b directly attenuated HIF1α translation through binding to HIF1A internal ribosome entry site region and targeting YB-1, and blocked an autocrine HIF1α/platelet-derived growth factor β (PDGFβ)/pAKT/HIF1α loop of HIF1α translation by targeting the PDGFβ receptor. The miR-125b-loss/HIF1α axis induced the expression of CD24 and erythropoietin (EPO) and enriched a TACE-resistant CD24-positive cancer stem cell population. Consistently, patients with high CD24 or EPO in HCC had poor prognosis following adjuvant TACE therapy. Additionally, in patients with HCC having TACE as their first-line therapy, high EPO in blood before TACE was also noticeably related to poor response to TACE. Conclusions MiR-125b loss activated the HIF1α/pAKT loop, contributing to HCC resistance to TACE and the key nodes in this axis hold the potential in assisting patients with HCC to choose TACE therapy.

UNLABELLED The cell fate determinant Numb is aberrantly expressed in cancer. Numb is alternatively spliced, with one isoform containing a long proline-rich region (PRR(L) ) compared to the other with a short PRR (PRR(S) ). Recently, PRR(L) was reported to enhance proliferation of breast and lung cancer cells. However, the importance of Numb alternative splicing in hepatocellular carcinoma (HCC) remains unexplored. We report here that Numb PRR(L) expression is increased in HCC and associated with early recurrence and reduced overall survival after surgery. In a panel of HCC cell lines, PRR(L) generally promotes and PRR(S) suppresses proliferation, migration, invasion, and colony formation. Knockdown of PRR(S) leads to increased Akt phosphorylation and c-Myc expression, and Akt inhibition or c-Myc silencing dampens the proliferative impact of Numb PRR(S) knockdown. In the cell models explored in this study, alternative splicing of Numb PRR isoforms is coordinately regulated by the splicing factor RNA-binding Fox domain containing 2 (RbFox2) and the kinase serine/arginine protein-specific kinase 2 (SRPK2). Knockdown of the former causes accumulation of PRR(L) , while SRPK2 knockdown causes accumulation of PRR(S) . The subcellular location of SRPK2 is regulated by the molecular chaperone heat shock protein 90, and heat shock protein 90 inhibition or knockdown phenocopies SRPK2 knockdown in promoting accumulation of Numb PRR(S) . Finally, HCC cell lines that predominantly express PRR(L) are differentially sensitive to heat shock protein 90 inhibition. CONCLUSION Alternative splicing of Numb may provide a useful prognostic biomarker in HCC and is pharmacologically tractable.

Intrahepatic cholangiocellular carcinoma (ICC) is the second most common type of primary liver cancer. However, its tumor heterogeneity and molecular characteristics are largely unknown. In this study, we conducted transcriptomic profiling of 23 ICC and combined hepatocellular cholangiocarcinoma tumor specimens from Asian patients using Affymetrix messenger RNA (mRNA) and NanoString microRNA microarrays to search for unique gene signatures linked to tumor subtypes and patient prognosis. We validated the signatures in an additional 68 ICC cases derived from Caucasian patients. We found that both mRNA and microRNA expression profiles could independently classify Asian ICC cases into two main subgroups, one of which shared gene expression signatures with previously identified hepatocellular carcinoma (HCC) with stem cell gene expression traits. ICC-specific gene signatures could predict survival in Asian HCC cases and independently in Caucasian ICC cases. Integrative analyses of the ICC-specific mRNA and microRNA expression profiles revealed that a common signaling pathway linking miR-200c signaling to epithelial-mesenchymal transition (EMT) was preferentially activated in ICC with stem cell gene expression traits. Inactivation of miR-200c resulted in an induction of EMT, whereas activation of miR-200c led to a reduction of EMT including a reduced cell migration and invasion in ICC cells. We also found that miR-200c and neural cell adhesion molecule 1 (NCAM1) expression were negatively correlated and their expression levels were predictive of survival in ICC samples. NCAM1, a known hepatic stem/progenitor cell marker, was experimentally demonstrated to be a direct target of miR-200c. Conclusion: Our results indicate that ICC and HCC share common stem-like molecular characteristics and poor prognosis. We suggest that the specific components of EMT may be exploited as critical biomarkers and clinically relevant therapeutic targets for an aggressive form of stem cell-like ICC. (HEPATOLOGY 2012;56:1792–1803)