Clinical and ABCB11 profiles in Korean infants with progressive familial intrahepatic cholestasis

Liver Transplantation for Pediatric Hepatocellular Carcinoma: A Systematic Review

Simple Summary

Hepatocellular carcinoma is a type of primary liver cancer and the second most common type of liver cancer in children. Although partial hepatectomy can be curative, many children present with tumors that are not amenable to resection and thus the only potentially curative option is liver transplantation. In this systematic review, we have pooled the data from the worldwide literature and showed that survival after liver transplantation for pediatric hepatocellular carcinoma is favorable and many children do well even if their tumors exceed certain potentially restrictive criteria originally developed to select adults with hepatocellular carcinoma for liver transplantation.

Abstract

Liver transplantation (LT) is the only potentially curative option for children with unresectable hepatocellular carcinoma (HCC). We performed a systematic review of the MEDLINE, Scopus, Cochrane Library, and Web of Science databases (end-of-search date: 31 July 2020). Our outcomes were overall survival (OS) and disease-free survival (DFS). We evaluated the effect of clinically relevant variables on outcomes using the Kaplan–Meier method and log-rank test. Sixty-seven studies reporting on 245 children undergoing LT for HCC were included. DFS data were available for 150 patients and the 1-, 3-, and 5-year DFS rates were 92.3%, 89.1%, and 84.5%, respectively. Sixty of the two hundred and thirty-eight patients (25.2%) died over a mean follow up of 46.8 ± 47.4 months. OS data were available for 222 patients and the 1-, 3-, and 5-year OS rates were 87.9%, 78.8%, and 74.3%, respectively. Although no difference was observed between children transplanted within vs. beyond Milan criteria (p = 0.15), superior OS was observed in children transplanted within vs. beyond UCSF criteria (p = 0.02). LT can yield favorable outcomes for pediatric HCC beyond Milan but not beyond UCSF criteria. Further research is required to determine appropriate LT selection criteria for pediatric HCC.

The molecular landscape of progressive familial intrahepatic cholestasis in Turkey: Defining the molecular profiles and expanding the variant spectrum

Progressive familial intrahepatic cholestasis (PFIC) is a rare genetically heterogeneous group of autosomal recessive liver disorders that manifests as intrahepatic cholestasis during the neonatal period. ATP8B1, ABCB11, and ABCB4 genes are responsible for PFIC type 1, PFIC type 2, and PFIC type 3, respectively. To determine the underlying molecular etiology of PFIC, 80 patients from 77 families were investigated. The molecular genetic diagnosis was applied by using next-generation sequencing (NGS) and revealed 29 different variants from 32 patients. In this study, we evaluated these variants according to mechanisms, clinical sub-groups, and genotype-phenotype correlation.

Phenotypic and Molecular Characteristics of Children with Progressive Familial Intrahepatic Cholestasis in South China

PURPOSE

Progressive familial intrahepatic cholestasis (PFIC) is a rare genetic autosomal recessive disease caused by mutations in ATP8B1, ABCB11 or ABCB4. Mutational analysis of these genes is a reliable approach to identify the disorder.

METHODS

We collected and analyzed relevant data related to clinical diagnosis, biological investigation, and molecular determination in nine children carrying these gene mutations, who were from unrelated families in South China.

RESULTS

Of the nine patients (five males, four females) with PFIC, one case of PFIC1, four cases of PFIC2, and four cases of PFIC3 were diagnosed. Except in patient no. 8, jaundice and severe pruritus were the major clinical signs in all forms. γ-glutamyl transpeptidase was low in patients with PFIC1/PFIC2, and remained mildly elevated in patients with PFIC3. We identified 15 different mutations, including nine novel mutations (p.R470HfsX8, p.Q794X and p.I1170T of ABCB11 gene mutations, p.G319R, p.A1047P, p.G1074R, p.T830NfsX11, p.A1047PfsX8 and p.N1048TfsX of ABCB4 gene mutations) and six known mutations (p.G446R and p.F529del of ATP8B1 gene mutations, p.A588V, p.G1004D and p.R1057X of ABCB11 gene mutations, p.P479L of ABCB4 gene mutations). The results showed that compared with other regions, these three types of PFIC genes had different mutational spectrum in China.

CONCLUSION

The study expands the genotypic spectrum of PFIC. We identified nine novel mutations of PFIC and our findings could help in the diagnosis and treatment of this disease.

Insights Into the Somatic Mutation Burden of Hepatoblastomas From Brazilian Patients

Hepatoblastoma is a very rare embryonal liver cancer supposed to arise from the impairment of hepatocyte differentiation during embryogenesis. In this study, we investigated by exome sequencing the burden of somatic mutations in a cohort of 10 hepatoblastomas, including a congenital case. Our data disclosed a low mutational background and pointed out to a novel set of candidate genes for hepatoblastoma biology, which were shown to impact gene expression levels. Only three recurrently mutated genes were detected: CTNNB1 and two novel candidates, CX3CL1 and CEP164. A relevant finding was the identification of a recurrent mutation (A235G) in two hepatoblastomas at the CX3CL1 gene; evaluation of RNA and protein expression revealed upregulation of CX3CL1 in tumors. The analysis was replicated in two independents cohorts, substantiating that an activation of the CX3CL1/CX3CR1 pathway occurs in hepatoblastomas. In inflammatory regions of hepatoblastomas, CX3CL1/CX3CR1 were not detected in the infiltrated lymphocytes, in which they should be expressed in normal conditions, whereas necrotic regions exhibited negative labeling in tumor cells, but strongly positive infiltrated lymphocytes. Altogether, these data suggested that CX3CL1/CX3CR1 upregulation may be a common feature of hepatoblastomas, potentially related to chemotherapy response and progression. In addition, three mutational signatures were identified in hepatoblastomas, two of them with predominance of either the COSMIC signatures 1 and 6, found in all cancer types, or the COSMIC signature 29, mostly related to tobacco chewing habit; a third novel mutational signature presented an unspecific pattern with an increase of C>A mutations. Overall, we present here novel candidate genes for hepatoblastoma, with evidence that CX3CL1/CX3CR1 chemokine signaling pathway is likely involved with progression, besides reporting specific mutational signatures.

The Role of the Sodium-taurocholate Co-transporting Polypeptide (NTCP) and Bile Salt Export Pump (BSEP) in Related Liver Disease

BACKGROUND

Sodium Taurocholate Co-transporting Polypeptide (NTCP) and Bile Salt Export Pump (BSEP) play significant roles as membrane transporters because of their presence in the enterohepatic circulation of bile salts. They have emerged as promising drug targets in related liver disease.

METHODS

We reviewed the literature published over the last 20 years with a focus on NTCP and BSEP.

RESULTS

This review summarizes the current perception about structure, function, genetic variation, and regulation of NTCP and BSEP, highlights the effects of their defects in some hepatic disorders, and discusses the application prospect of new transcriptional activators in liver diseases.

CONCLUSION

NTCP and BSEP are important proteins for transportation and homeostasis maintenance of bile acids. Further research is needed to develop new models for determining the structure-function relationship of bile acid transporters and screening for substrates and inhibitors, as well as to gain more information about the regulatory genetic mechanisms involved in the processes of liver injury.

D, F. E, M.R. F, M. M, S.M.B. T. In-silico Evaluation of Rare Codons and their Positions in the Structure of ATP8b1 Gene

BACKGROUND

Progressive familial intrahepatic cholestases (PFIC) are a spectrum of autosomal progressive liver diseases developing to end-stage liver disease. ATP8B1 deficiency caused by mutations in ATP8B1 gene encoding a P-type ATPase leads to PFIC1. The gene for PFIC1 has been mapped on a 19-cM region of 18q21-q22, and a gene defect in ATP8B1 can cause deregulations in bile salt transporters through decreased expression and/or activity of FXR. Point mutations are the most common, with the majority being missense or nonsense mutations. In addition, approximately 15% of disease-causing ATP8B1 mutations are annotated as splicing disrupting alteration given that they are located at exon-intron borders.

OBJECTIVE

Here, we describe the hidden layer of computational biology information of rare codons in ATP8B1, which can help us for drug design.

METHODS

Some rare codons in different locations of ATP8b1 gene were identified using several web servers and by in-silico modelling of ATP8b1 in Phyre2 and I-TASSER server, some rare codons were evaluated.

RESULTS

Some of these rare codons were located at special positions which seem to have a critical role in proper folding of ATP8b1 protein. Structural analysis showed that some of rare codons are related to mutations in ATP8B1 that are responsible for PFIC1 disease, which may have a critical role in ensuring the correct folding.

CONCLUSION

Investigation of such hidden information can enhance our understanding of ATP8b1 folding. Moreover, studies of these rare codons help us to clarify their role in rational design of new and effective drugs.

Neonatal Cholestasis: A Pandora's Box

Neonatal cholestasis (NC) is a diagnostic dilemma frequently countered in a neonatal care unit. Early diagnosis is vital for achieving an optimal patient outcome as many causes of cholestasis such as biliary atresia are time-sensitive and amenable to treatment if analyzed and treated early. Nonetheless, it is not generally simple to analyze these cases right on time as some of them are regularly missed due to the presence of pigmented stools, lack of newborn metabolic screening, and named as instances of prolonged jaundice. In this manner, we prescribe to explore all reasons for prolonged jaundice stretching out past 14 days in neonates. Besides, we suggest that stool card ought to be a piece of release rundown for all newborn children being released from the nursery. This is of most extreme significance in the nation like India where guaranteeing customary follow-up is as yet a tough assignment. These stool cards will help in the early determination of patients with NC particularly biliary atresia and guarantee their auspicious cure. Another reason which needs exceptional say is parenteral nutrition–associated liver illness, as the proportion of preterm babies is getting greater and greater with better neonatal care. These extreme preterm infants are in the requirement for prolonged (>14 days) total parenteral nourishment because of which they are at high hazard for NC contrasted with their more developed peers. In this survey, we will give an understanding of clinical approach, differential diagnosis, and clinical review of NC.

Functional analysis of the correlation between ABCB11 gene mutation and primary intrahepatic stone

The adenosine 5'‑triphosphate binding cassette subfamily B member (ABCB)11 gene is involved in bile transport, and mutations in this gene are associated with cholestasis and cholelithiasis. Therefore, the aim of the present study was to investigate the association between ABCB11 gene mutation and primary intrahepatic stone (PIS)s and to investigate the mechanism through which ABCB11 gene mutations affect the expression of the corresponding protein. Mutations of the ABCB11 gene in 443 PIS patients and 560 healthy participants were detected by exon sequencing. The expression levels of ABCB11 mRNA and bile salt export pump (BSEP) protein in the liver tissues of patients with PISs were measured by quantitative polymerase chain reaction and western blot analysis. The mutant plasmids constructed by site‑directed mutagenesis of the human BSEP gene were transfected into human embryonic kidney 293 (293) cells and Madin‑Darby canine kidney (MDCK) cells, and the expression and distribution of rs118109635 of BSEP was measured. There were two significant mutations in the ABCB11 gene of the PIS patients compared with the healthy population; a missense mutation, rs118109635 (P=0.025), and a synonymous mutation, rs497692 (P=0.006). The two mutations were associated with the occurrence of preoperative jaundice (P=0.026, and P=0.011, respectively). The expression levels of BSEP in PIS patients with the missense mutation rs118109635 was decreased, whereas its mRNA expression levels remained unchanged. In PIS patients with the synonymous mutation rs497692, the expression levels of ABCB11 were decreased at both the mRNA and protein level. It was also found that mutation A865V reduced the expression levels of BSEP in 293 cells at the cellular level; its distribution in MDCK cell membranes was decreased, whereas its mRNA levels remained unchanged. The mutated loci at rs118109635 and rs497692 of the ABCB11 gene were correlated with PISs, causing a decreased expression of BSEP and reduced distribution of the protein in the cell membrane. Therefore, mutations at rs118109635 and rs497692 of the ABCB11 gene may be risk factors for PISs.

Clinical phenotype and molecular analysis of a homozygous ABCB11 mutation responsible for progressive infantile cholestasis

The bile salt export pump (BSEP) plays an important role in biliary secretion. Mutations in ABCB11, the gene encoding BSEP, induce progressive familial intrahepatic cholestasis type 2 (PFIC2), which presents with severe jaundice and liver dysfunction. A less severe phenotype, called benign recurrent intrahepatic cholestasis type 2, is also known. About 200 missense mutations in ABCB11 have been reported. However, the phenotype-genotype correlation has not been clarified. Furthermore, the frequencies of ABCB11 mutations differ between Asian and European populations. We report a patient with PFIC2 carrying a homozygous ABCB11 mutation c.386G>A (p.C129Y) that is most frequently reported in Japan. The pathogenicity of BSEP^C129Y has not been investigated. In this study, we performed the molecular analysis of this ABCB11 mutation using cells expressing BSEP^C129Y. We found that trafficking of BSEP^C129Y to the plasma membrane was impaired and that the expression of BSEP^C129Y on the cell surface was significantly lower than that in the control. The amount of bile acids transported via BSEP^C129Y was also significantly lower than that via BSEP^WT. The transport activity of BSEP^C129Y may be conserved because the amount of membrane BSEP^C129Y corresponded to the uptake of taurocholate into membrane vesicles. In conclusion, we demonstrated that c.386G>A (p.C129Y) in ABCB11 was a causative mutation correlating with the phenotype of patients with PFIC2, impairment of biliary excretion from hepatocytes, and the absence of canalicular BSEP expression in liver histological assessments. Mutational analysis in ABCB11 could facilitate the elucidation of the molecular mechanisms underlying the development of intrahepatic cholestasis.