Prevalence and clinical features of heterozygous carriers of autosomal recessive hypercholesterolemia in Sardinia

OBJECTIVE

Autosomal recessive hypercholesterolemia (ARH) is a lipid disorder caused by mutations in a specific adaptor protein for the LDL receptor. ARH is rare except in Sardinia where three alleles (ARH1, ARH2 and ARH3) explain most of cases. The prevalence of ARH heterozygotes in Sardinia is not well determined as well as inconclusive data are available on the effect of the ARH carrier status on LDL cholesterol (LDL-C) and coronary risk.

METHODS

3410 Sardinians (986 blood donors, 1709 with hypertension and 715 with myocardial infarction (MI)) were screened for ARH alleles. For comparison purposes, lipid data of 60 ARH heterozygous carriers and 60 non-carriers identified within 24 ARH families were also considered.

RESULTS

In the whole study cohort, no ARH homozygotes were found, but 15 ARH1 (0.44%) and 9 ARH2 (0.26%) heterozygous carriers were identified. The frequency of ARH alleles in blood donors was 0.0030, not different from that in hypertensive subjects (0.0032). ARH alleles tended to be more common in MI patients (0.0049), but no association between ARH carrier status and MI risk was detected after controlling for conventional risk factors. ARH carriers and non-carriers showed similar LDL-C levels. This result was confirmed when ARH carriers and non-carriers identified throughout family-based and population-based screenings were combined and compared (141.0+/-41 mg/dl vs. 137.0+/-41 mg/dl, respectively; p=0.19).

CONCLUSIONS

These data indicate that the frequency of ARH heterozygotes in Sardinia is approximately 1:143 individuals, thus making this condition one of the most common in the Sardinian population. However, ARH carrier status does not influence LDL-C concentration and coronary risk, thus suggesting that ARH can be regarded as a truly recessive disorder.

Severe HDL deficiency due to novel defects in the ABCA1 transporter

OBJECTIVES

The objective was the identification and functional characterization of mutations in the ABCA1 gene in four patients with severe HDL deficiency.

SUBJECTS

Patients were referred to the clinic because of almost complete HDL deficiency.

METHODS

The ABCA1 gene was sequenced directly. The analysis of the ABCA1 protein, ABCA1 mRNA and ABCA1-mediated cholesterol efflux was performed in cultured fibroblasts. Intracellular localization of ABCA1 mutants was investigated in transfected HEK293 cells.

RESULTS

Two patients were homozygous for mutations in the coding region of the ABCA1 gene, resulting in an amino acid substitution (p.A1046D) and a truncated protein (p.I74YFsX76). The third patient was homozygous for a splice site mutation in intron 35 (c.4773 + 1g>a), resulting in an in-frame deletion of 25 amino acids (del p.D1567_K1591) in ABCA1. These patients had clinical manifestations of accumulation of cholesterol in the reticulo-endothelial system. The fourth patient, with preclinical atherosclerosis, was a compound heterozygote for two missense mutations (p.R587W/p.W1699C). ABCA1-mediated cholesterol efflux was abolished in fibroblasts from patients with p.A1046D and del p.D1567_K1591 mutants and in fibroblasts homozygous for p.R587W. A reduced ABCA1 protein content was observed in these cells, suggesting an increased intracellular degradation. The mutant p.W1699C was largely retained in the endoplasmic reticulum, when expressed in HEK293 cells.

CONCLUSIONS

The homozygotes for mutations which abolish ABCA1 function showed overt signs of involvement of the reticulo-endothelial system. This was not the case in the compound heterozygote for missense mutations, suggesting that this patient retains some residual ABCA1 function that reduces cholesterol accumulation in the reticulo-endothelial system.

Functional analysis of two novel splice site mutations of APOB gene in familial hypobetalipoproteinemia

Familial hypobetalipoproteinemia (FHBL) is a co-dominant disorder characterized by reduced plasma levels of low density lipoprotein cholesterol (LDL-C) and its protein constituent apolipoprotein B (apoB), which may be due to mutations in APOB gene, mostly located in the coding region of this gene. We report two novel APOB gene mutations involving the acceptor splice site of intron 11 (c.1471-1G>A) and of intron 23 (c.3697-1G>C), respectively, which were identified in two patients with heterozygous FHBL associated with severe fatty liver disease. The effects of these mutations on APOB pre-mRNA splicing were assessed in COS-1 cells expressing the mutant APOB minigenes. The c.1471-1G>A APOB minigene generated two abnormal mRNAs. In one mRNA the entire intron 11 was retained; in the other mRNA exon 11 joined to exon 12, in which the first nucleotide was deleted due to the activation of a novel acceptor splice site. The predicted products of these mRNAs are truncated proteins of 546 and 474 amino acids, designated apoB-12.03 and apoB-10.45, respectively. The c.3697-1G>C APOB minigene generated a single abnormal mRNA in which exon 23 joined to exon 25, with the complete skipping of exon 24. This abnormal mRNA is predicted to encode a truncated protein of 1220 amino acids, designated apoB-26.89. These splice site mutations cause the formation of short truncated apoBs, which are not secreted into the plasma as lipoprotein constituents. This secretion defect is the major cause of severe fatty liver observed in carriers of these mutations.

Effects of a phytosterol-enriched dairy product on lipids, sterols and 8-isoprostane in hypercholesterolemic patients: a multicenter Italian study

BACKGROUND AND AIMS

Plant sterols, added to several food sources, lower serum cholesterol concentrations. Plant sterol-induced cholesterol lowering is paralleled by a mild decrease in plasma levels of the antioxidant beta-carotene, the amount of this decrease being considered clinically non-significant. Whether the effect on lipid profile of daily consumption of plant sterol-enriched low-fat fermented milk (FM) is paralleled by a concomitant variation in a reliable marker of the oxidative burden like plasma isoprostane levels is unresolved.

METHODS AND RESULTS

The effect of plant sterol consumption on plasma lipid and isoprostane levels of hypercholesterolemic patients was evaluated in a multicenter, randomized double blind study. Hypercholesterolemic patients consumed a FM daily for 6 weeks. Subjects were randomized to receive either 1.6g of plant sterol-enriched FM (n=60) or control FM product (n=56). After 6 weeks of plant sterol-enriched FM consumption, LDL cholesterol was reduced from 166.2+/-2.0 to 147.4+/-2.8 mg/dL (p=0.01). A significant reduction was observed for total cholesterol (from 263.5+/-2.6 to 231.0+/-3.2mg/dL, p=0.01). There was greater LDL cholesterol lowering among hypercholesterolemic patients with higher LDL cholesterol at baseline. We found a reduction of plasma 8-isoprostane in patients taking plant sterol-enriched FM (from 43.07+/-1.78 to 38.04+/-1.14 pg/ml, p=0.018) but not in patients taking the control product (from 42.56+/-2.12 to 43.19+/-2.0 pg/ml, p=NS). Campesterol and beta-sitosterol levels were not influenced by phytosterol consumption.

CONCLUSIONS

Daily consumption of low-fat plant sterol dairy product favourably changes lipid profile by reducing LDL-cholesterol, and may also have an anti-oxidative effect through a reduction of plasma isoprostanes.

Effect of statins on fibroblasts from human nasal polyps and turbinates

BACKGROUND

Statins are serum cholesterol-lowering agents used for the prevention and treatment of atherosclerotic vascular disease. There is, however, growing evidence that statins have immunomodulatory and anti-inflammatory activities and may prove invaluable in the treatment of immunological and inflammatory disorders.

OBJECTIVE

On these basis we evaluated the effect of statins on the proliferation of fibroblasts derived from human nasal polyps and turbinates and determined their ability to modulate airway remodelling.

METHODS

Fluvastatin (0.01-0.1-1 microM), Atorvastatin (0.1-1-10 microM) and Simvastatin (0.1-1-10 microM) were tested on cultured fibroblasts derived from human nasal polyps and turbinates stimulated or not with Fibroblast Growth Factor beta (10 ng/ml). All cultures were treated with 3H-Thymidine (1 microCi/ml) to test cell proliferation.

RESULTS

Our results show that proliferation of turbinate-derived fibroblasts is significantly inhibited by the three statins. Fluvastatin is already effective at the lowest dose (0.01 microM), whereas Atorvastatin and Simvastatin act at the plasmatic peak concentration (1 microM). No significant effect was found on fibroblasts derived from nasal polyps, except for Simvastatin which was effective after 144 hours of stimulation.

CONCLUSIONS

These drugs show a remarkable antiprolhferative effect and their different outcome depending on the different kind of fibroblasts in vitro is prompting news in the studies about statin use for the treatment of chronic inflammatory diseases.

Correlation between Progetto Cuore risk score and early cardiovascular damage in never treated subjects

Background

Global cardiovascular risk is a new approach which allows the physicians to quantitate the prognosis of the patients. It is therefore possible that a score, based on the major cardiovascular risk factors, is correlated with some degree of cardiovascular anatomic damage. Since this hypothesis has been demonstrated with the Framingham risk score, we decided to verify it using another score (Progetto Cuore risk score), which is probably more precise in a european low-risk population, such as the italian one.

Methods

We studied 84 italian caucasian subjects (50 males and 34 females) with elevated blood pressure and/or dyslipidemia plus other possible cardiovascular risk factors.

The subjects have never been treated for these reasons. The following evaluations were performed: history, clinical and laboratory determinations, echocardiogram, carotid echodoppler.

Results

The recruited people were on the whole characterized by a low cardiovascular risk, as confirmed by the low scores of the Progetto Cuore. Simple linear regression analysis showed significant associations between some parameters of early cardiovascular damage (left ventricular mass, intima-media thickness, and an integrated measure of both the carotid wall thickness and the presence of a plaque, called Carotid score) and some predictors. The highest significance was found between the cardiovascular structural results and the Progetto Cuore score. In a multivariate regression analysis our model, which included factors potentially linked to the cardiovascular anatomic changes, demonstrated that the Carotid score was significantly associated with age, sex and pulse pressure; intima-media thickness with the same factors and, in addition, with the body mass index; left ventricular mass with sex, pulse pressure and body mass index.

Conclusion

Our paper confirms previous studies about the association between a comprehensive risk score and signs of early cardiovascular damage. A temporally limited exposure to cardiovascular risk factors, in particular to blood pressure, is already able to induce significant changes in both the heart structure and the vascular wall. Also in a european low-risk population the use of a cardiovascular risk score program, such as the Progetto Cuore in Italy, allows a quite precise estimation of the possible cardiovascular damage.

Hypertriglyceridaemia and low plasma HDL in a patient with apolipoprotein A-V deficiency due to a novel mutation in the APOA5 gene

APOA5 encodes a novel apolipoprotein (apo A-V) which appears to be a modulator of plasma triglyceride (TG). In apoA5 knock out mice plasma TG level increases almost fourfold, whereas in human APOA5 transgenic mice it decreases by 70%. Some SNPs in the APOA5 gene have been associated with variations in plasma TG in humans. In addition, hypertriglyceridaemic (HTG) patients have been identified who carried rare nonsense mutations in the APOA5 gene (Q139X and Q148X), predicted to result in apo A-V deficiency. In this study we report a 17-year-old male with high TG and low high density lipoprotein cholesterol (HDL-C), who at the age of two had been found to have severe HTG and eruptive xanthomas suggesting a chylomicronaemia syndrome. Plasma postheparin LPL activity, however, was normal and no mutations were found in LPL and APOC2 genes. The sequence of APOA5 gene revealed that the patient was homozygous for a point mutation (c.289 C>T) in exon 4, converting glutamine codon at position 97 into a termination codon (Q97X). Apo A-V was not detected in patient's plasma, indicating that he had complete apo A-V deficiency. The administration of a low-fat and low-oligosaccharide diet, either alone or supplemented with omega-3 fatty acids, started early in life, reduced plasma TG to a great extent but had a negligible effect on plasma HDL-C. Loss of function mutations of APOA5 gene may be the cause of severe HTG in patients without mutations in LPL and APOC2 genes.

Beta-sitosterolaemia: a new nonsense mutation in the ABCG5 gene

BACKGROUND

Sitosterolaemia is a rare autosomal recessive disorder characterised by elevated plasma levels of plant sterols and cholesterol. Sitosterolaemia is caused by gene mutations in either of two ATP-binding cassette (ABC) half transporters, ABCG5 and ABCG8. The plasma sterol profile and genetic analysis of a 10-year-old girl who had tuberous xanthomas is the subject of this report.

MATERIALS AND METHODS

Genomic DNA was isolated from white blood cells from the proband, her family and a control group of healthy people. All exons of ABCG5 and ABCG8 were sequenced. Plasma cholesterol and triglycerides were measured by routine methods. All other plasma sterols were measured by Gas Chromatography coupled to Mass Spectrometry.

RESULTS

The proband was found to be homozygous for a single nucleotide mutation in exon 10 of the ABCG5 gene, consisting of a C to T transition at nucleotide 1336 of the coding sequence, which results in the premature termination of the ABCG5 protein at amino acid 446 (Arg446X). Her mother and brother were also homozygous for the same mutation and all had elevated plasma beta-sitosterol levels. The father was heterozygous and showed normal beta-sitosterol levels. This mutation was not found in healthy normolipidaemic subjects.

CONCLUSIONS

We describe a novel nonsense mutation in exon 10 of the ABCG5 gene in a 10-year-old girl showing clinical and biochemical features of sitosterolaemia. This family study broadens the spectrum of the ABCG5/ABCG8 mutations causing sitosterolaemia and helps highlight the correlations between such gene mutations, biochemical phenotype and the development of cardiovascular disease.

Effect of ezetimibe coadministered with statins in genotype-confirmed heterozygous FH patients

We investigated the effect of statins and statins plus ezetimibe in 65 FH heterozygotes carrying LDLR-defective or LDLR-negative mutations as well as the effect of ezetimibe monotherapy in 50 hypercholesterolemic (HCH) patients intolerant to statins. PCSK9 and NPC1L1 genes were analysed to assess the role of genetic variants in response to therapy. In FH patients combined therapy reduced LDL-C by 57%, irrespective of the type of LDLR mutation. The additional decrease of plasma LDL-C induced by ezetimibe showed wide inter-individual variability (from -39% to -4.7%) and was negatively correlated with percent LDL-C decrease due to statin alone (r=-0.713, P<0.001). The variable response to statins was not due to PCSK9 gene variants associated with statin hyper-sensitivity. The highest response to ezetimibe was observed in a carrier of R174H substitution in NPC1L1, which had been found to be associated with high cholesterol absorption. In HCH patients, ezetimibe monotherapy induced a variable decrease of plasma LDL-C (from -47.7% to -13.4%). To investigate this variability, we sequenced NPC1L1 gene in patients with the highest and the lowest response to ezetimibe. This analysis showed a higher prevalence of the G allele of the c.816 C>G polymorphism (L272L) in hyper-responders, an observation confirmed also in FH patients hyper-responders to ezetimibe. In both FH and HCH patients, the G allele carriers tended to have a higher LDL-C reduction in response to ezetimibe. These observations suggest that in FH heterozygotes LDL-C reduction following combined therapy reflects a complex interplay between hepatic synthesis and intestinal absorption of cholesterol.

Transmission parameters of highly pathogenic avian influenza (H7N1) among industrial poultry farms in northern Italy in 1999–2000

We estimated between-farm transmission parameters of the highly pathogenic avian-influenza (HPAI) epidemic that struck the poultry industry of northern Italy (including turkeys, layer hens, broilers, gamebirds, and waterfowl) from December 1999 through April 2000. We estimated the average number of susceptible farms that were infected with HPAI virus by each infectious farm during a day (beta) with a generalised linear model (GLM). The HPAI's reproductive ratios (R(h); the average number of new infected farms (IFs) that were caused by an infectious farm) were calculated separately for the regions of Lombardy and Veneto, where 382 out of 413 (92.5%) of IFs were located. In both regions, R(h) decreased to approximately 1 during the second month of the epidemic (showing that its containment had been initiated). Subsequently, during the last two months of the epidemic, beta and R(h) were reduced to 0.04/day and 0.6, respectively, in Veneto and to 0.07/day and 0.8 in Lombardy. The reduction of the susceptible population through strict control measures, including pre-emptive slaughter of at-risk poultry flocks, was implemented to a greatest extent in Veneto and this might have been associated with a more rapid control of the epidemic in this region than in Lombardy.

GEMOX as first-line chemotherapy in advanced pancreatic cancer (APC): A monoinstitutional experience

15179

Background: To date, gemcitabine (GEM) remains the cornerstone of chemotherapy (CHT) for APC. According to GERCOR and GISCAD phase III trials the combination of GEM and oxaliplatin (GEMOX) has proven superior to GEM alone in terms of response rate (RR), time to progression (TTP) and clinical benefit rate (CBR). Methods: We conducted a retrospective analysis on 19 patients (pts) affected with histologically-confirmed APC, in order to determine the impact of GEMOX as first-line chemotherapy in terms of objective responses (OR) and TTP, using the Kaplan-Meier method. Among the 19 pts considered there were 15 males and 4 females (median age at diagnosis of 60.84 yrs; ECOG 0–2). The staging, according to AJCC criteria, was: IIB in 1 case, III in 5 cases and IV in the 13 remaning cases. The only metastatic site was the liver (in 13/19 pts). Ten of the 19 pts underwent surgical treatment prior to CHT: 2 radically resected (R0) subsequently treated with GEMOX after recurrence, 4 with positive margins (R1) and 4 surgically palliated. All pts received GEM 1000 mg/m2/d1 + oxaliplatin 100 mg/m2/d2 every 2 weeks. The median number of cycles was 5.89. Results: Among the 19 pts, 3 had a partial response (PR, 15.69%), 6 had stable disease (SD, 31.57%); no complete response was observed and 10 pts had progressive disease (PD, 52.63%). The overall disease control rate (DCR: PR + SD) was 47.37% while the OR were 15.69%. The median survival observed was 9.03 months (95% C.I. 5.15–12.91) and the median TTP was 6.13 months (95% C.I. 2.81–9.46). The main toxicities were: leucopenia, piastrinopenia, diarrhoea, nausea, fever and peripheral neuropathy; 3 pts discontinued the treatment due to grade 3–4 neurotoxicity. Conclusions: In our experience GEMOX gives an improved control of APC in terms of OR and TTP, with acceptable toxicity. The OS is in accordance to literature as well as the other data.

No significant financial relationships to disclose.

Molecular diagnosis of hypobetalipoproteinemia: an ENID review

Primary hypobetalipoproteinemia (HBL) includes a group of genetic disorders: abetalipoproteinemia (ABL) and chylomicron retention disease (CRD), with a recessive transmission, and familial hypobetalipoproteinemia (FHBL) with a co-dominant transmission. ABL and CRD are rare disorders due to mutations in the MTP and SARA2 genes, respectively. Heterozygous FHBL is much more frequent. FHBL subjects often have fatty liver and, less frequently, intestinal fat malabsorption. FHBL may be linked or not to the APOB gene. Most mutations in APOB gene cause the formation of truncated forms of apoB which may or may be not secreted into the plasma. Truncated apoBs with a size below that of apoB-30 are not detectable in plasma; they are more frequent in patients with the most severe phenotype. Only a single amino acid substitution (R463W) has been reported as the cause of FHBL. Approximately 50% of FHBL subjects are carriers of pathogenic mutations in APOB gene; therefore, a large proportion of FHBL subjects have no apoB gene mutations or are carriers of rare amino acid substitutions in apoB with unknown effect. In some kindred FHBL is linked to a locus on chromosome 3 (3p21) but the candidate gene is unknown. Recently a FHBL plasma lipid phenotype was observed in carriers of mutations of the PCSK9 gene causing loss of function of the encoded protein, a proprotein convertase which regulates LDL-receptor number in the liver. Inactivation of this enzyme is associated with an increased LDL uptake and hypobetalipoproteinemia. HBL carriers of PCSK9 mutations do not develop fatty liver disease.

Abnormal apolipoprotein B pre-mRNA splicing in patients with familial hypobetalipoproteinaemia

BACKGROUND

Familial hypobetalipoproteinaemia (FHBL) is a codominant disorder characterised by fatty liver and reduced plasma levels of low-density lipoprotein (LDL) and its protein constituent apolipoprotein B (apoB). FHBL is linked to the APOB gene in some but not all known cases. In a group of 59 patients with FHBL genotyped for APOB gene mutations, we found three novel splice-site mutations: c.904+4A-->G in intron 8, c.3843-2A-->G in intron 24 and c.4217-1G-->T in intron 25.

OBJECTIVE

To assess the effects of these mutations on apoB pre-mRNA splicing.

METHODS

ApoB mRNA was analysed in the liver of one proband and in cells expressing APOB minigenes harbouring the mutations found in the other probands.

RESULTS

In the liver of the c.3843-2A-->G carrier, an apoB mRNA devoid of exon 25 was identified, predicted to encode a truncated peptide of 1260 amino acids. The analysis of minigene transcripts in COS-1 cells showed that the c.904+4A-->G mutation caused the formation of an mRNA devoid of exon 8, predicted to encode a short apoB of 247 amino acids. The minigene harbouring the c.4217-1G-->T mutation in intron 25 generated an mRNA in which exon 25 joined to a partially deleted exon 26, resulting from the activation of an acceptor site in exon 26; this mRNA is predicted to encode a truncated protein of 1380 amino acids. All these truncated apoBs were not secreted as constituents of plasma lipoproteins.

CONCLUSION

These findings demonstrate the pathogenic effect of rare splice-site mutations of the APOB gene found in FHBL.

Additive effect of mutations in LDLR and PCSK9 genes on the phenotype of familial hypercholesterolemia

Patients homozygous or compound heterozygous for LDLR mutations or double heterozygous for LDLR and apo B R3500Q mutation have higher LDL-C levels, more extensive xanthomatosis and more severe premature coronary disease (pCAD) than simple heterozygotes for mutations in either these genes or for missense mutations in PCSK9 gene. It is not known whether combined mutations in LDLR and PKCS9 are associated with such a severe phenotype. We sequenced Apo B and PCSK9 genes in two patients with the clinical diagnosis of homozygous FH who were heterozygous for LDLR gene mutations. Proband Z.P. (LDL-C 13.39 mmol/L and pCAD) was heterozygous for an LDLR mutation (p.E228K) inherited from her father (LDL-C 8.07 mmol/L) and a PCSK9 mutation (p.R496W) from her mother (LDL-C 5.58 mmol/L). Proband L.R. and her sister (LDL-C 11.51 and 10.47 mmol/L, xanthomatosis and carotid atherosclerosis) were heterozygous for an LDLR mutation (p.Y419X) inherited from their mother (LDL-C 6.54 mmol/L) and a PCSK9 mutation (p.N425S) probably from their deceased father. The LDL-C levels in double heterozygotes of these two families were 56 and 44% higher than those found in simple heterozygotes for the two LDLR mutations, respectively. The two PCSK9 mutations are novel and were not found in 110 controls and 80 patients with co-dominant hypercholesterolemia. These observations indicate that rare missense mutations of PCSK9 may worsen the clinical phenotype of patients carrying LDLR mutations.

APOA5 and triglyceride metabolism, lesson from human APOA5 deficiency

PURPOSE OF REVIEW

In this review we compare the phenotype and lipoprotein abnormalities of some patients who were found to carry mutations in the APOA5 gene predicted to result in apolipoprotein A-V deficiency.

RECENT FINDINGS

The sequencing of the APOA5 gene in patients with primary hypertriglyceridemia, in whom mutations of the LPL and APOC2 genes had been excluded, led to the identification of four families with two different mutations in this gene predicted to result in truncated apolipoprotein A-V. The first mutation (Q148X) was found in a homozygous state in a child with severe type V hyperlipidemia, some clinical manifestations of chylomicronemia syndrome and a slight reduction in plasma postheparin lipoprotein lipase activity. Carriers of a different mutation (Q139X) were recently reported. Four Q139X heterozygotes had type V hyperlipidemia and markedly reduced plasma postheparin lipoprotein lipase activity. The hypertriglyceridemic Q139X heterozygote had other factors that could have contributed to hypertriglyceridemia. ApoB-100 kinetic studies in hypertriglyceridemic Q139X heterozygotes revealed an impairment of very low-density lipoprotein catabolism.

SUMMARY

Mutations in the APOA5 gene, leading to truncated apolipoprotein A-V devoid of lipid-binding domains located in the carboxy-terminal end of the protein, if present in the homozygous state, are expected to cause severe type V hyperlipidemia in patients with no mutations in LPL or APOC2 genes. If present in the heterozygous state, these mutations predispose to hypertriglyceridemia in combination with other genetic factors or pathological conditions.

[Treatment of colorectal cancer liver metastases]

Liver is the main target for colorectal cancer (CRC) metastases. About 50% of all patients affected by CRC develop liver metastases. Surgery remains the only potentially curative strategy and indications to surgery and resectability criteria are now less restrictive than before so that a more aggressive attitude in the treatment of metastatic lesions is the rule. However surgery is not possible in the majority of patients. For non resectable patients two options are available: local treatment strategies (Radio-frequency ablation and Cryosurgery: alone or in combination with surgery) and chemotherapy. High rates of objective response achieved with Fluoropyrimidines, Oxaliplatin (OHP) and Irinotecan (CPT-11) based chemo-therapy, enable initially unresectable patients to undergo surgery, with a 5-year survival rate comparable to that observed for primary resectable patients. Therefore chemotherapy has not only a palliative aim, but becomes a fundamental moment of a combined medical and surgical treatment with curative purpose. After surgery two-thirds of patients will relapse in first two years, so that adjuvant therapy has been investigated to reduce recurrence rates, mainly testing hepatic arterial infusion (HAI) schedules. So far no randomized trials have been published on the role of systemic intravenous adjuvant chemo-therapy. Finally we report the results of our monoinstitutional experience, suggesting a possible role of systemic adjuvant chemotherapy in reducing recurrence rates after liver metastasectomy. Probably in the next years new targeted drugs and locoregional therapies will contribute to further improve prognosis of such patients, in a neoadjuvant, adjuvant and palliative setting.

Autosomal recessive hypercholesterolemia (ARH) and homozygous familial hypercholesterolemia (FH): a phenotypic comparison

Autosomal recessive hypercholesterolemia (ARH) is a rare disorder, due to complete loss of function of an adaptor protein (ARH protein) required for receptor-mediated hepatic uptake of LDL. ARH is a phenocopy of homozygous familial hypercholesterolemia (HoFH) due to mutations in LDL receptor (LDLR) gene; however, previous studies suggested that ARH phenotype is less severe than that of HoFH. To test this hypothesis we compared 42 HoFH and 42 ARH patients. LDLR and ARH genes were analysed by Southern blotting and sequencing. LDLR activity was measured in cultured fibroblasts. In ARH plasma LDL cholestrol (LDL-C) level (14.25+/-2.29 mmol/L) was lower than in receptor-negative HoFH (21.38+/-3.56 mmol/L) but similar to that found in receptor-defective HoFH (15.52+/-2.39 mmol/L). The risk of coronary artery disease (CAD) was 9-fold lower in ARH patients. No ARH patients </=20 years of age were found to have CAD as opposed to 43% of HoFH. The CAD prevalence was or tended to be lower in ARH also in the 21-40 (45% versus 86%) and 41-60 (78% versus 100%) age groups. Heterozygous ARH carriers showed higher level of LDL-C (+17%) than non-carrier family members. In conclusion the clinical phenotype of ARH is milder than that of receptor-negative HoFH and resembles that observed in receptor-defective HoFH.

Adaptor Protein ARH Is Recruited to the Plasma Membrane by Low Density Lipoprotein (LDL) Binding and Modulates Endocytosis of the LDL/LDL Receptor Complex in Hepatocytes

ARH is a newly discovered adaptor protein required for the efficient activity of low density lipoprotein receptor (LDLR) in selected tissues. Individuals lacking ARH have severe hypercholesterolemia due to an impaired hepatic clearance of LDL. It has been demonstrated that ARH is required for the efficient internalization of the LDL-LDLR complex and to stabilize the association of the receptor with LDL in Epstein-Barr virus-immortalized B lymphocytes. However, little information is available on the role of ARH in liver cells. Here we provide evidence that ARH is codistributed with LDLR on the basolateral area in confluent HepG2-polarized cells. This distribution is not modified by the overexpression of LDLR. Conversely, the activation of the LDLR-mediated endocytosis, but not the binding of LDL to LDLR, promotes a significant colocalization of ARH with LDL-LDLR complex that peaked at 2 min at 37 degrees C. To further assess the role of ARH in LDL-LDLR complex internalization, we depleted ARH protein using the RNA interference technique. Twenty-four hours after transfection with ARH-specific RNA interference, ARH protein was depleted in HepG2 cells by more than 70%. Quantitative immunofluorescence analysis revealed that the depletion of ARH caused about 80% reduction in LDL internalization. Moreover, our findings indicate that ARH is associated with other proteins of the endocytic machinery. We suggest that ARH is an endocytic sorting adaptor that actively participates in the internalization of the LDL-LDLR complex, possibly enhancing the efficiency of its packaging into the endocytic vesicles.