Anand Ghanekar

Identification of Driver Genes in Hepatocellular Carcinoma by Exome Sequencing

Genetic alterations in specific driver genes lead to disruption of cellular pathways and are critical events in the instigation and progression of hepatocellular carcinoma (HCC). As a prerequisite for individualized cancer treatment, we sought to characterize the landscape of recurrent somatic mutations in HCC. We performed whole‐exome sequencing on 87 HCCs and matched normal adjacent tissues to an average coverage of 59×. The overall mutation rate was roughly two mutations per Mb, with a median of 45 nonsynonymous mutations that altered the amino acid sequence (range, 2‐381). We found recurrent mutations in several genes with high transcript levels: TP53 (18%); CTNNB1 (10%); KEAP1 (8%); C16orf62 (8%); MLL4 (7%); and RAC2 (5%). Significantly affected gene families include the nucleotide‐binding domain and leucine‐rich repeat‐containing family, calcium channel subunits, and histone methyltransferases. In particular, the MLL family of methyltransferases for histone H3 lysine 4 were mutated in 20% of tumors. Conclusion: The NFE2L2‐KEAP1 and MLL pathways are recurrently mutated in multiple cohorts of HCC. (Hepatology 2013;58:1693–1702)

The Fgl2/fibroleukin prothrombinase contributes to immunologically mediated thrombosis in experimental and human viral hepatitis

Fibrin deposition and thrombosis within the microvasculature is now appreciated to play a pivotal role in the hepatocellular injury observed in experimental and human viral hepatitis. Importantly, the pathways by which fibrin generation is elicited in viral hepatitis may be mechanistically distinct from the classical pathways of coagulation induced by mechanical trauma or bacterial lipopolysaccharide (LPS). In the setting of murine hepatitis virus strain-3 (MHV-3) infection, a member of the Coronaviridae, activated endothelial cells and macrophages express distinct cell-surface procoagulants, including a novel prothrombinase, Fgl2/fibroleukin, which are important for both the initiation and localization of fibrin deposition. To assess the role of Fgl2/fibroleukin in murine viral hepatitis we generated a Fgl2/fibroleukin-deficient mouse. Peritoneal macrophages isolated from Fgl2/fibroleukin-/- mice did not generate a procoagulant response when infected with MHV-3. Fibrin deposition and liver necrosis were markedly reduced, and survival was increased in mice infected with MHV-3. To address the relevance of Fgl2/fibroleukin in human chronic viral hepatitis we studied patients with minimal and marked chronic hepatitis B. We detected robust expression of Fgl2/fibroleukin mRNA transcripts and protein in liver tissue isolated from patients with marked chronic hepatitis B. Fibrin deposition was strongly associated with Fgl2/fibroleukin expression. Collectively, these data indicate a critical role for Fgl2/fibroleukin in the pathophysiology of experimental and human viral hepatitis.

Versican 3′-untranslated region (3′-UTR) functions as a ceRNA in inducing the development of hepatocellular carcinoma by regulating miRNA activity

This study was designed to explore the role of versican in the development of hepatocellular carcinoma (HCC). Ectopic expression of the versican 3′‐untranslated region (3′‐UTR) was studied as a competitive endogenous RNA for regulating miRNA functions. We used this approach to modulate the expression of versican and its related proteins in 3′‐UTR transgenic mice and in the liver cancer cell line HepG2, stably transfected with the 3′‐UTR or a control vector. We demonstrated that transgenic mice expressing the versican 3′‐UTR developed HCC and increased expression of versican isoforms V0 and V1. HepG2 cells transfected with versican 3′‐UTR displayed increased proliferation, survival, migration, invasion, colony formation, and enhanced endothelial cell growth, but decreased apoptosis. We found that versican 3′‐UTR could bind to miRNAs miR‐133a, miR‐199a*, miR‐144, and miR‐431 and also interacted with CD34 and fibronectin. As a consequence, expression of versican, CD34, and fibronectin was up‐regulated by ectopic transfection of the versican 3′‐UTR, which was confirmed in HepG2 cells and in transgenic mice as compared with wild‐type controls. Transfection with siRNAs targeting the versican 3′‐UTR abolished the effects of the 3′‐UTR. Taken together, these results demonstrate that versican V0 and V1 isoforms play important roles in HCC development and that versican mRNAs compete with endogenous RNAs in regulating miRNA functions.—Fang, L., Du, W. W., Yang, X., Chen, K., Ghanekar, A., Levy, G., Yang, W., Yee, A. J., Lu, W.‐Y., Xuan, J. W., Gao, Z., Xie, F., He, C., Deng, Z., Yang, B. B. Versican 3′‐untranslated region (3′‐UTR) functions as a ceRNA in inducing the development of hepatocellular carcinoma by regulating miRNA activity. FASEB J. 27, 907–919 (2013). www.fasebj.org

Endothelial Induction of fgl2 Contributes to Thrombosis during Acute Vascular Xenograft Rejection

Thrombosis is a prominent feature of acute vascular rejection (AVR), the current barrier to survival of pig-to-primate xenografts. Fibrinogen-like protein 2 (fgl2/fibroleukin) is an inducible prothrombinase that plays an important role in the pathogenesis of fibrin deposition during viral hepatitis and cytokine-induced fetal loss. We hypothesized that induction of fgl2 on the vascular endothelium of xenografts contributes to thrombosis associated with AVR. We first examined fgl2 as a source of procoagulant activity in the pig-to-primate combination. The porcine fgl2 (pfgl2) was cloned and its chromosomal locus was identified. Recombinant pfgl2 protein expressed in vitro was detected on the cell surface and generated thrombin from human prothrombin. Studies of pig-to-baboon kidney xenografts undergoing AVR in vivo revealed induction of pfgl2 expression on graft vascular endothelial cells (ECs). Cultured porcine ECs activated by human TNF-α in vitro demonstrated induction of pfgl2 expression and enhanced activation of human prothrombin. The availability of gene-targeted fgl2-deficient mice allowed the contribution of fgl2 to the pathogenesis of AVR to be directly examined in vivo. Hearts heterotopically transplanted from fgl2+/+ and fgl2+/− mice into Lewis rats developed AVR with intravascular thrombosis associated with induction of fgl2 in graft vascular ECs. In contrast, xenografts from fgl2−/− mice were devoid of thrombosis. These observations collectively suggest that induction of fgl2 on the vascular endothelium plays a role in the pathogenesis of AVR-associated thrombosis. Manipulation of fgl2, in combination with other interventions, may yield novel strategies by which to overcome AVR and extend xenograft survival.

Directed differentiation of cholangiocytes from human pluripotent stem cells

Although bile duct disorders are well-recognized causes of liver disease, the molecular and cellular events leading to biliary dysfunction are poorly understood. To enable modeling and drug discovery for biliary disease, we describe a protocol that achieves efficient differentiation of biliary epithelial cells (cholangiocytes) from human pluripotent stem cells (hPSCs) through delivery of developmentally relevant cues, including NOTCH signaling. Using three-dimensional culture, the protocol yields cystic and/or ductal structures that express mature biliary markers, including apical sodium-dependent bile acid transporter, secretin receptor, cilia and cystic fibrosis transmembrane conductance regulator (CFTR). We demonstrate that hPSC-derived cholangiocytes possess epithelial functions, including rhodamine efflux and CFTR-mediated fluid secretion. Furthermore, we show that functionally impaired hPSC-derived cholangiocytes from cystic fibrosis patients are rescued by CFTR correctors. These findings demonstrate that mature cholangiocytes can be differentiated from hPSCs and used for studies of biliary development and disease.

A graft to body weight ratio less than 0.8 does not exclude adult‐to‐adult right‐lobe living donor liver transplantation

Many centers require a minimal graft to body weight ratio (GBWR) ≥ 0.8 as an arbitrary threshold to proceed with right‐lobe living donor liver transplantation (RL‐LDLT), and there is often hesitancy about transplanting lower volume living donor (LD) liver grafts into sicker patients. The data supporting this dogma, based on the early experience with RL‐LDLT at Asian centers, are weak. To determine the effect of LD liver volume in the modern era, we investigated the impact of GBWR on the outcome of RL‐LDLT with a GBWR as low as 0.6 at the University of Toronto. Between April 2000 and September 2008, 271 adult‐to‐adult RL‐LDLT procedures and 614 deceased donor liver transplants were performed. Twenty‐two living donor liver transplantation (LDLT) cases with a GBWR of 0.59 to 0.79 (group A) were compared with 249 LDLT cases with a GBWR ≥ 0.8 (group B) and with 66 full‐graft deceased donor liver transplants (group C), who were matched 3:1 according to donor and recipient age, Model for End‐Stage Liver Disease score, and presence of hepatitis C and hepatocellular carcinoma with the low‐GBWR group. Portal vein shunts were not used. Markers of reperfusion injury [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)], graft function (international normalized ratio and bilirubin), complications graded by the Clavien score, and graft and patient survival were compared. As expected, LD recipients had a significantly shorter cold ischemia time (94 ± 43 minutes for A, 96 ± 57 minutes for B, and 453 ± 152 minutes for C, P = 0.0001). However, the peak AST, peak ALT, absolute decrease in the international normalized ratio, day 7 bilirubin level, postoperative creatinine clearance, complication rate graded by the Clavien score, and median hospital stay were similar in all groups. The rate of biliary complications was higher with LD grafts than deceased donor grafts (19% for A versus 10% for B and 0% for C, P = 0.2). Patient survival was similar in all groups at 1, 3, and 5 years (91% for A versus 89% for B and 93% for C at 1 year, 87% for A versus 81% for B and 89% for C at 3 years, and 83% for A versus 81% for B and 87% for C at 5 years, P = 0.63). A Cox proportional regression analysis revealed only hepatitis C virus as a risk factor for poorer graft survival and not GBWR as a continuous or categorical variable. In conclusion, we found no evidence of inferior outcomes with smaller size grafts versus larger size LD grafts or full‐size deceased donor grafts. Further studies are warranted to examine the factors affecting the function of smaller grafts for living liver donation and thereby define the safe lower limits for transplantation. Liver Transpl 15:1776–1782, 2009.

Targeted Deletion of Fgl-2/Fibroleukin in the Donor Modulates Immunologic Response and Acute Vascular Rejection in Cardiac Xenografts

Background—Xenografts ultimately fail as a result of acute vascular rejection (AVR), a process characterized by intravascular thrombosis, fibrin deposition, and endothelial cell activation. Methods and Results—We studied whether targeted deletion of Fgl-2, an inducible endothelial cell procoagulant, (Fgl-2−/−) in the donor prevents AVR in a mouse-to-rat cardiac xenotransplantation model. By 3 days after transplant, Fgl-2+/+ grafts developed typical features of AVR associated with increased levels of donor Fgl-2 mRNA. Grafts from Fgl-2−/− mice had reduced fibrin deposition but developed cellular rejection. Treatment with a short course of cobra venom factor and maintenance cyclosporine resulted in long-term acceptance of both Fgl-2+/+ and Fgl-2−/− grafts. On withdrawal of cyclosporine, Fgl-2+/+ grafts developed features of AVR; in contrast, Fgl-2−/− grafts again developed acute cellular rejection. Rejecting Fgl-2+/+ hearts stained positively for IgG, IgM, C3, and C5b-9, whereas rejecting Fgl-2−/− hearts had minimal Ig and complement deposition despite xenoantibodies in the serum. Furthermore, serum containing xenoantibodies failed to stain Fgl-2−/− long-term treated hearts but did stain wild-type heart tissues. Treatment of Fgl-2−/− xenografts with mycophenolate mofetil and tacrolimus, a clinically relevant immune suppression protocol, led to long-term graft acceptance. Conclusions—Deletion of Fgl-2 ameliorates AVR by downregulation of xenoantigens and may facilitate successful clinical heart xenotransplantation.

Radiotherapy as a bridge to liver transplantation for hepatocellular carcinoma

About 20% of the patients with advanced hepatocellular carcinoma (HCC) who are listed for liver transplantation (LT) are eventually delisted as a result of local tumor progression. Herein, we report our experience with conformal radiotherapy (CRT) as a novel bridge to LT. From July 2006 to August 2008, CRT was delivered in five or six fractions to patients with HCC listed for LT in whom either prior local therapies had failed or those not suitable for standard local therapies because of poor liver function or anatomic issues. Radiotherapy (RT) volumes and doses were individualized to spare the uninvolved liver with the goal of stabilizing the most aggressive HCC(s) in an attempt to reduce the chance of delisting as a result of tumor progression. Ten patients with tumor diameters ranging from 25 to 108 mm were treated. Eight out of 10 tumors were beyond Milan criteria. The median age was 55 (range 36–64). Seventy percent of the patients were male subjects. The median medical MELD score was 11 (range 9–17). The median irradiated HCC volume was 79 cc (range 15–798 cc). The median RT delivered dose was 33 Gy (range 8.5–54 Gy), in one to six fractions. The median dose to the uninvolved liver was 13.3 Gy (range 1.8–16.5). Nine patients completed their CRT as planned and one patient was transplanted after the first fraction. The treatment was well tolerated: Grade 1 nausea was reported in three patients, the platelet count decreased from 154 to 98 in one patient, and there were no other complications. No treated tumors progressed during or after the treatment. Two tumors remained stable; the rest had 10–50% regression, which was sustained on follow‐up imaging.  The median follow up was 14 months (range 3–20). Local tumor control was achieved in all treated tumors.Two patients were delisted as a result of cancer progression outside the treated field (one in the context of systemic metastases; yet another with progression of other untreated HCC in the liver). Three patients are still waiting for transplantation. Five patients underwent LT with no complications attributable to the CRT. Explant pathology, available for five patients, showed tumor necrosis and fibrosis with sparing of the untreated parenchyma. All transplanted patients treated with CRT are cancer‐free. CRT is a safe and efficacious local bridging therapy for patients with advanced HCC who are on the waiting list for LT. Further studies are warranted to compare the effectiveness of CRT to other local treatment regimens for HCC.

Living donor liver transplantation versus deceased donor liver transplantation for hepatocellular carcinoma: Comparable survival and recurrence

Several studies have reported higher rates of recurrent hepatocellular carcinoma (HCC) after living donor liver transplantation (LDLT) versus deceased donor liver transplantation (DDLT). It is unclear whether this difference is due to a specific biological effect unique to the LDLT procedure or to other factors such as patient selection. We compared the overall survival (OS) rates and the rates of HCC recurrence after LDLT and DDLT at our center. Between January 1996 and September 2009, 345 patients with HCC were identified: 287 (83%) had DDLT and 58 (17%) had LDLT. The OS rates were calculated with the Kaplan‐Meier method, whereas competing risks methods were used to determine the HCC recurrence rates. The LDLT and DDLT groups were similar with respect to most clinical parameters, but they had different median waiting times (3.1 versus 5.3 months, P = 0.003) and median follow‐up times (30 versus 38.1 months, P = 0.02). The type of transplant did not affect any of the measured cancer outcomes. The OS rates at 1, 3, and 5 years were equivalent: 91.3%, 75.2%, and 75.2%, respectively, for the LDLT group and 90.5%, 79.7%, and 74.6%, respectively, for DDLT (P = 0.62). The 1‐, 3‐, and 5‐year HCC recurrence rates were also similar: 8.8%, 10.7%, and 15.4%, respectively, for the LDLT group and 7.5%, 14.8%, and 17.0%, respectively, for the DDLT group (P = 0.54). A regression analysis identified microvascular invasion (but not the graft type) as a predictor of HCC recurrence. In conclusion, in well‐matched cohorts of LDLT and DDLT recipients, LDLT and DDLT provide similarly low recurrence rates and high survival rates for the treatment of HCC. Liver Transpl 18:315–322, 2012.

Thrombolytic protocol minimizes ischemic‐type biliary complications in liver transplantation from donation after circulatory death donors

Liver transplantation (LT) with donation after circulatory death (DCD) donors has been associated with a high rate of ischemic‐type biliary strictures (ITBSs) and inferior graft survival. To investigate the impact of an intraoperative tissue plasminogen activator (tPA) on outcomes following DCD LT, we conducted a retrospective analysis of DCD LT at the Toronto General Hospital (TGH) and the Ochsner Medical Center (OMC). Between 2009 and 2013, 85 DCD LTs were performed with an intraoperative tPA injection (n = 30 at TGH, n = 55 at OMC), and they were compared with 33 DCD LTs without a tPA. Donor and recipient characteristics were similar in the 2 groups. There was no significant difference in the intraoperative packed red blood cell transfusion requirement (3.2 ± 3.4 versus 3.1 ± 2.3 U, P = 0.74). Overall, biliary strictures occurred less commonly in the tPA‐treated group (16.5% versus 33.3%, P = 0.07) with a much lower rate of diffuse intrahepatic strictures (3.5% versus 21.2%, P = 0.005). After 1 and 3 years, the tPA group versus the non‐tPA group had superior patient survival (97.6% versus 87.0% and 92.7% versus 79.7%, P = 0.016) and graft survival (96.4% versus 69.7% and 90.2% versus 63.6%, P < 0.001). In conclusion, a tPA injection into the hepatic artery during DCD LT reduces ITBSs and improves graft and patient survival without increasing the risk for bleeding. Liver Transpl 21:321–328, 2015.