Hubert de Verneuil

Increased incidence of HFE C282Y mutations in patients with iron overload and hepatocellular carcinoma developed in non-cirrhotic liver

BACKGROUND/AIMSnHistological and biochemical iron overload has been reported in non-tumoral liver of most patients presenting an hepatocellular carcinoma (HCC) developed in non-cirrhotic liver (NCL). The aim of our study was to investigate HFE mutations in patients with HCC in NCL.nnnMETHODSnThirty-five patients with HCC in NCL were included either retrospectively or prospectively. Clinical data, iron and viral status, and HFE gene mutations were compared between groups with (I+, n = 19) or without histological iron overload (I-, n = 16).nnnRESULTSnTwenty per cent of patients were HBV or HCV positive. Fifty-four per cent had hepatocytic iron overload at histology. Mean hepatic iron concentration was 100.2 +/- 14.6 micromol/g in I+ versus 23.2 +/- 2.1 micromol/g in I- (p<0.001). Among the 19 I+ patients, eight mutations were found: two C282Y/C282Y, three C282Y/WT, two C282Y/H63D and one H63D/H63D. None of these mutations was found in the I- group. There was no significant difference concerning the H63D heterozygous mutation between I+ or I- patients.nnnCONCLUSIONSnIn patients with HCC in NCL, HBV and HCV markers are rare (20%), and mild iron overload is frequent (54%). In patients with HCC in NCL and iron overload, C282Y mutations are frequent (36.8% of cases) and significantly increased (p<0.009) compared to HCC in NCL without iron overload; these mutations are mostly heterozygous. H63D heterozygosity is not associated with liver iron overload. Because of the small size of the series, HFE C282Y mutation should be investigated on a larger scale in patients with HCC in NCL with iron overload in order to confirm this association.

Porphyrias: Animal models and prospects for cellular and gene therapy

The rapid progress in the development of molecular technology has resulted in the identification of most of the genes of the heme biosynthesis pathway. Important problems in the pathogenesis and treatment of porphyrias now seem likely to be solved by the possibility of creating animal models and by the transfer of normal genes or cDNAs to target cells. Animal models of porphyrias naturally occur for erythropoietic protoporphyria and congenital erythropoietic porphyria, and different murine models have been or are being created for erythropoietic and hepatic porphyrias. The PBGD knock-out mouse will be useful for the understanding of nervous system dysfunction in acute porphyrias. Murine models of erythropoietic porphyrias are being used for bone-marrow transplantation experiments to study the features of erythropoietic and hepatic abnormalities. Gene transfer experiments have been startedin vitro to look at the feasibility of somatic gene therapy in erythropoietic porphyrias. In particular, we have documented sufficient gene transfer rate and metabolic correction in different CEP disease cells to indicate that this porphyria is a good candidate for treatment by gene therapy in hematopoietic stem cells. With the rapid advancement of methods that may allow more precise and/or efficient gene targeting, gene therapy will become a new therapeutic option for porphyrias.

Comprehensive functional annotation of 18 missense mutations found in suspected hemochromatosis type 4 patients

Hemochromatosis type 4 is a rare form of primary iron overload transmitted as an autosomal dominant trait caused by mutations in the gene encoding the iron transport protein ferroportin 1 (SLC40A1). SLC40A1 mutations fall into two functional categories (loss- versus gain-of-function) underlying two distinct clinical entities (hemochromatosis type 4A versus type 4B). However, the vast majority of SLC40A1 mutations are rare missense variations, with only a few showing strong evidence of causality. The present study reports the results of an integrated approach collecting genetic and phenotypic data from 44 suspected hemochromatosis type 4 patients, with comprehensive structural and functional annotations. Causality was demonstrated for 10 missense variants, showing a clear dichotomy between the two hemochromatosis type 4 subtypes. Two subgroups of loss-of-function mutations were distinguished: one impairing cell-surface expression and one altering only iron egress. Additionally, a new gain-of-function mutation was identified, and the degradation of ferroportin on hepcidin binding was shown to probably depend on the integrity of a large extracellular loop outside of the hepcidin-binding domain. Eight further missense variations, on the other hand, were shown to have no discernible effects at either protein or RNA level; these were found in apparently isolated patients and were associated with a less severe phenotype. The present findings illustrate the importance of combining in silico and biochemical approaches to fully distinguish pathogenic SLC40A1 mutations from benign variants. This has profound implications for patient management.

Novel point mutation in the uroporphyrinogen III synthase gene causes congenital erythropoietic porphyria of a Japanese family

The molecular basis of the uroporphyrinogen III synthase (UROIIIS) deficiency was investigated in a member of a Japanese family. This defect in heme biosynthesis is responsible for a rare autosomal recessive disease: congenital erythropoietic porphyria (CEP) or Günthers disease. The patient was homozygous for a novel missense mutation: a G to T transition of nucleotide 7 that predicted a valine to phenylalanine substitution at residue 3 (V3F). The parents were heterozygous for the same mutation. The loss of UROIIIS activity was verified by an in vitro assay system. The corresponding mutated protein was expressed in Escherichia coli and no residual activity was observed. Further studies are needed to determine whether the mutations of the UROIIIS gene (UROS) have a specific profile in Japan compared to European or American countries.

A novel point mutation in congenital erythropoietic porphyria in two members of Japanese family

The molecular basis of the uroporphyrinogen III synthase (UROIIIS) deficiency was investigated in two members of a Japanese family. This defect in heme biosynthesis is responsible for a rare autosomal recessive disease: congenital erythropoietic porphyria (CEP) or Günthers disease. The first patient was homoallelic for a novel missense mutation: a T to C transition of nucleotide 634 that predicted a serine to proline substitution at residue 212 (S212P). The second patient appeared heteroallelic, carrying the same missense mutation and a nonsense mutation: a C to T change at nucleotide 745, resulting in a premature stop at codon 249, instead of a glutamine (Q249X). The corresponding mutated proteins were expressed inEscherichia coli and no residual activity was observed. A family study was also performed to determine the carrier status.

Resveratrol and capsaicin used together as food complements reduce tumor growth and rescue full efficiency of low dose gemcitabine in a pancreatic cancer model

Pancreatic adenocarcinoma, highly resistant to all current anti-cancer treatments, necessitates new approaches promoting cell death. We hypothesized that combined actions of several Bioactive Food Components (BFCs) might provide specific lethal effect towards tumor cells, sparing healthy cells. Human tumor pancreatic cell lines were tested inxa0vitro for sensitivity to resveratrol, capsaicin, piceatannol, and sulforaphane cytotoxic effects. Combination of two or three components showed striking synergetic effect with gemcitabine inxa0vitro. Each BFC used alone did not affect pancreatic tumor growth in a preclinical inxa0vivo model, whereas couples of BFCs had anti-tumor activity. In addition, tumor toxicity was similar using gemcitabine alone or a combination of BFCs and two thirds of gemcitabine dose. Moreover, BFCs enhanced fibrotic response as compared to gemcitabine treatment alone. Reactive oxygen species (ROS) and apoptosis increases were observed, while cell cycle was very mildly affected. This study raises the possibility to use BFCs as beneficial food complements in the therapy of pancreatic adenocarcinoma, especially for patients unable to receive full doses of chemotherapy.

Preventing Pluripotent Cell Teratoma in Regenerative Medicine Applied to Hematology Disorders

Iatrogenic tumorigenesis is a major limitation for the use of human induced pluripotent stem cells (hiPSCs) in hematology. The teratoma risk comes from the persistence of hiPSCs in differentiated cell populations. Our goal was to evaluate the best system to purge residual hiPSCs before graft without compromising hematopoietic repopulation capability. Teratoma risk after systemic injection of hiPSCs expressing the reporter gene luciferase was assessed for the first time. Teratoma formation in immune‐deficient mice was tracked by in vivo bioimaging. We observed that systemic injection of hiPSCs produced multisite teratoma as soon as 5 weeks after injection. To eliminate hiPSCs before grafting, we tested the embryonic‐specific expression of suicide genes under the control of the pmiR‐302/367 promoter. This promoter was highly active in hiPSCs but not in differentiated cells. The gene/prodrug inducible Caspase‐9 (iCaspase‐9)/AP20187 was more efficient and rapid than thymidine kinase/ganciclovir, fully specific, and without bystander effect. We observed that iCaspase‐9‐expressing hiPSCs died in a dose‐dependent manner with AP20187, without reaching full eradication in vitro. Unexpectedly, nonspecific toxicity of AP20187 on iCaspase‐9‐negative hiPSCs and on CD34+ cells was evidenced in vitro. This toxic effect strongly impaired CD34+‐derived human hematopoiesis in adoptive transfers. Survivin inhibition is an alternative to the suicide gene approach because hiPSCs fully rely on survivin for survival. Survivin inhibitor YM155 was more efficient than AP20187/iCaspase‐9 for killing hiPSCs, without toxicity on CD34+ cells, in vitro and in adoptive transfers. hiPSC purge by survivin inhibitor fully eradicated teratoma formation in immune‐deficient mice. This will be useful to improve the safety management for hiPSC‐based medicine. Stem Cells Translational Medicine 2017;6:382–393

Xeroderma pigmentosum: clues to understanding cancer initiation

Abstract Xeroderma pigmentosum (XP) type C is a rare autosomal recessive disorder that occurs because of inactivation of the xeroderma pigmentosum group C (XPC) protein, which is an important DNA damage recognition protein involved in DNA nucleotide excision repair (NER). This defect, which prevents removal of a wide array of direct and indirect DNA lesions, is associated with a decrease in catalase activity. As a novel photoprotective approach, lentivirus-mediated catalase overexpression in XPC human keratinocytes results in a marked decrease in sunburn cell formation, caspase-3 activation, and p53 accumulation following UVB irradiation. While not correcting the gene defect, indirect gene therapy using antioxidant enzymes may be helpful in limiting photosensitivity in XP type C, as well as in other monogenic/polygenic photosensitive disorders characterized by reactive oxygen species (ROS) accumulation. Hypoxia-inducible factor-1 (HIF-1), a major transcription factor sensitive to oxygen levels, responds to various stress factors. As a common stressor of skin, UVB induces a biphasic HIF-1a variation through ROS generation in keratinocytes. HIF-1a has an important regulator effect on the expression of XPC protein and other NER genes, indicating indirect regulation of NER by ROS. The intrinsic genomic instability arising in XP type C provides a good opportunity to investigate the complex molecular mechanisms underlying the Warburg effect (the shift of mito-chondrial metabolism towards glycolysis). Overall, the monogenic disorder XP type C is a powerful tool for studying photoprotection and cancer.

Repurposing ciclopirox as a pharmacological chaperone in a model of congenital erythropoietic porphyria

The off-patent marketed antifungal ciclopirox improves symptoms in a mouse model of congenital erythropoietic porphyria. Drug repurposing helps iron out porphyria Porphyria is an inherited incurable disorder resulting from the buildup of heme precursors throughout the body. Urquiza et al. showed that ciclopirox, already approved as an antifungal, allosterically stabilized a mutated biosynthetic enzyme (uroporphyrinogen III synthase or UROIIIS) that leads to this condition. Oral ciclopirox administration increased UROIIIS activity and reduced clinical symptoms in a mouse model of porphyria. Further work will be needed to show whether ciclopirox is suitable for chronic treatment. The authors’ drug repurposing pipeline could potentially be co-opted to investigate therapies for other enzyme mutations that cause metabolic disease. Congenital erythropoietic porphyria is a rare autosomal recessive disease produced by deficient activity of uroporphyrinogen III synthase, the fourth enzyme in the heme biosynthetic pathway. The disease affects many organs, can be life-threatening, and currently lacks curative treatments. Inherited mutations most commonly reduce the enzyme’s stability, altering its homeostasis and ultimately blunting intracellular heme production. This results in uroporphyrin by-product accumulation in the body, aggravating associated pathological symptoms such as skin photosensitivity and disfiguring phototoxic cutaneous lesions. We demonstrated that the synthetic marketed antifungal ciclopirox binds to the enzyme, stabilizing it. Ciclopirox targeted the enzyme at an allosteric site distant from the active center and did not affect the enzyme’s catalytic role. The drug restored enzymatic activity in vitro and ex vivo and was able to alleviate most clinical symptoms of congenital erythropoietic porphyria in a genetic mouse model of the disease at subtoxic concentrations. Our findings establish a possible line of therapeutic intervention against congenital erythropoietic porphyria, which is potentially applicable to most of deleterious missense mutations causing this devastating disease.

61. Successful Gene Therapy of a Mouse Model of Congenital Erythropoietic Porphyria with an Erythroid-Specific Lentiviral Vector

Congenital erythropoietic porphyria (CEP) is a recessive autosomal disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. The severity of the disease, the lack of specific treatment except for allogenic bone marrow transplantation (BMT) and the knowledge of the molecular lesions are strong arguments towards gene therapy. We have recently developed a knock-in mouse model of CEP (Ged et al., Genomics, 2006) in order to evaluate the feasibility of gene therapy in haematopoietic stem cells (HSCs). This novel mouse model closely mimics the CEP disease in humans (porphyrins accumulation in urine, blood and spleen, erythrodontia, moderate photosensitivity, hepatosplenomegaly, and haemolytic anaemia). Here we develop a self-inactivating lentiviral vector containing human UROS cDNA driven by the human ankyrin-1/b-globin HS-40 chimeric erythroid promoter/enhancer. Murine HSCs from CEP donor mice were transduced by the erythroid-specific lentiviral vector and injected them into CEP recipient mice conditioned with high doses of busulfan. We observed a high transduction efficiency of HSCs (88 |[plusmn]| 14% PCR+ CFC, 20 weeks after BMT) resulting in an effective gene therapy of primary recipient CEP mice without any selectable system. A full restoration of enzymatic activity in BM, spleen and peripheral blood cells was obtained (2 fold increased UROS activity versus normal mice) resulting in skin photosensitivity correction and disappearance of splenomegaly. Furthermore, we observed a dramatic decrease of porphyrin accumulation in red blood cells (RBCs) and urines as well as a full correction of haemolytic anemia. In addition, a complete disappearance of fluorescent RBCs (fluorocytes) was observed by FACS. We are currently investigated the existence of a natural selective advantage of corrected cells in CEP mice. We demonstrate for the first time the high efficiency of HSCs gene therapy using a SIN erythroid-specific lentiviral vector in a murine model of CEP. This study forms the basis of gene therapy clinical trial for this severe congenital erythropoietic porphyria disease.