[Show abstract][Hide abstract] ABSTRACT: Tumour are characterised by a high content of cholesteryl esters (CEs) stored in lipid droplets purported to be due to a high rate of intracellular esterification of cholesterol. To verify whether and which pathways involved in CE accumulation are essential in tumour proliferation, the effect of CE deprivation, from both exogenous and endogenous sources, on CEM-CCRF cells was investigated. Cholesterol synthesis, esterification and content, low-density lipoprotein (LDL) binding and high-density lipoprotein (HDL)-CE uptake were evaluated in cultured in both conventional and delipidated bovine serum with or without oleic or linoleic acids, cholesteryl oleate, LDL and HDL. High content of CEs in lipid droplets in this cell line was due to esterification of both newly synthesised cholesterol and that obtained from hydrolysis of LDL; moreover, a significant amount of CE was derived from HDL-CE uptake. Cell proliferation was slightly affected by either acute or chronic treatment up to 400 μM with Sz-58035, an acyl-cholesteryl cholesterol esterification inhibitor (ACAT); although when the enzyme activity was continuously inhibited, CE content in lipid droplets was significantly higher than those in control cells. In these cells, analysis of intracellular and medium CEs revealed a profile reflecting the characteristics of bovine serum, suggesting a plasma origin of CE molecules. Cell proliferation arrest in delipidated medium was almost completely prevented in the first 72 h by LDL or HDL, although in subsequent cultures with LDL, it manifested an increasing mortality rate. This study suggests that high content of CEs in CEM-CCRF is mainly derived from plasma lipoproteins and that part of CEs stored in lipid droplets are obtained after being taken up from HDL. This route appears to be up-regulated according to cell requirements and involved in low levels of c-HDL during cancer. Moreover, the dependence of tumour cells on a source of lipoprotein provides a novel impetus in developing therapeutic strategies for use in the treatment of some tumours.
[Show abstract][Hide abstract] ABSTRACT: Scrapie is a prion disease for which no means of ante-mortem diagnosis is available. We recently found a relationship between
cell susceptibility to scrapie and altered cholesterol homeostasis. In brains and in skin fibroblasts and peripheral blood
mononuclear cells from healthy and scrapie-affected sheep carrying a scrapie-susceptible genotype, the levels of cholesterol
esters were consistently higher than in tissues and cultures derived from animals with a scrapie-resistant genotype. Here
we show that intracellular accumulation of cholesterol esters (CE) in fibroblasts derived from scrapie-susceptible sheep was
accompanied by parallel alterations in the expression level of acyl-coenzymeA: cholesterol-acyltransferase (ACAT1) and caveolin-1
(Cav-1) that are involved in the pathways leading to intracellular cholesterol esterification and trafficking. Comparative
analysis of cellular prion protein (PrPc) mRNA, showed an higher expression level in cells from animals carrying a susceptible
genotype, with or without Scrapie. These data suggest that CE accumulation in peripheral cells, together with the altered
expression of some proteins implicated in intracellular cholesterol homeostasis, might serve to identify a distinctive lipid
metabolic profile associated with increased susceptibility to develop prion disease following infection.
Central European Journal of Biology 01/2010; 5(1):31-37. DOI:10.2478/s11535-009-0076-3 · 0.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intracellular cholesterol metabolism was reported to modulate amyloid-beta (Abeta) generation in Alzheimer's disease (AD). Results presented herein demonstrated that, like brain cells, cultured skin fibroblasts from AD patients contained more cholesterol esters than fibroblasts from healthy subjects. Particularly, Oil Red-O, Nile Red, and filipin staining highlighted higher levels of neutral lipids which responded to inhibitors of acyl-coenzyme A:cholesterol acyl-transferase (ACAT-1), associated with an increase in free cholesterol. ACAT-1 mRNA levels increased significantly in AD fibroblasts, whereas those of sterol regulatory element binding protein-2, neutral cholesterol ester hydrolase, and ATP-binding cassette transporter member 1 were markedly down-regulated. Instead, mRNA levels of low-density lipoprotein receptor, hydroxy-methyl-glutaryl-coenzyme A reductase, caveolin-1, and amyloid-beta protein precursor (AbetaPP) were virtually unchanged. Notably, mRNA levels of both beta-site AbetaPP-cleaving enzyme 1 (BACE1) and neprilysin were significantly down-regulated. An increase in Abeta(40) and Abeta(42) immunostaining and a decrease in BACE1 active form were also found in AD versus control fibroblasts. Altogether, these findings support the hypothesis that the derangement of cholesterol homeostasis is a systemic alteration involving central but also peripheral cells of AD patients, and point to cholesterol ester levels in AD fibroblasts as an additional metabolic hallmark useful in the laboratory and clinical practice.
[Show abstract][Hide abstract] ABSTRACT: Our studies on the role of cholesterol homeostasis in the pathogenesis of scrapie revealed abnormal accumulation of cholesterol esters in ex vivo peripheral blood mononuclear cells (PBMCs) and skin fibroblasts from healthy and scrapie-affected sheep carrying a scrapie-susceptible genotype compared to sheep with a resistant genotype. Similar alterations were observed in mouse neuroblastoma N2a cell lines persistently infected with mouse-adapted 22L and RML strains of scrapie that showed up to threefold-higher cholesterol ester levels than parental N2a cells. We now report that proteinase K-resistant prion protein (PrPres)-producing cell populations of subclones from scrapie-infected cell lines were characterized by higher cholesterol ester levels than clone populations not producing PrPres. Treatments with a number of drugs known to interfere with different steps of cholesterol metabolism strongly reduced the accumulation of cholesterol esters in ex vivo PBMCs and skin fibroblasts from scrapie-affected sheep but had significantly less or no effect in their respective scrapie-resistant or uninfected counterparts. In scrapie-infected N2a cells, inhibition of cholesterol esters was associated with selective antiprion activity. Effective antiprion concentrations of cholesterol modulators (50% effective concentration [EC(50)] range, 1.4 to 40 microM) were comparable to those of antiprion reference compounds (EC(50) range, 0.6 to 10 microM). These data confirm our hypothesis that abnormal accumulation of cholesterol esters may represent a biological marker of susceptibility to prion infection/replication and a novel molecular target of potential clinical importance.
[Show abstract][Hide abstract] ABSTRACT: The authors have previously shown that the growth of cultured fibroblasts obtained from primary pterygia was associated with an increase in cholesterol esterification, suggesting that alterations of cholesterol homeostasis may be involved in the development and progression of this disorder. This investigation was conducted to determine whether antiproliferative agents such as pioglitazone (PIO) and everolimus (EVE) may inhibit proteins involved in the cholesterol ester cycle and the proliferation of pterygium fibroblasts (PF).
Quiescent normal conjunctival fibroblasts and PFs were treated with or without inhibitors of cell proliferation (PIO and EVE) or with inhibitors of cholesterol esterification-progesterone (Pg) and Sandoz compound (SaH)-and then were stimulated to growth by 10% fetal calf serum (FCS). Cell proliferation was assessed by counting cells. Trypan blue uptake was used to determine cell viability. mRNA and protein levels were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively.
PIO and EVE significantly abolished the increase in cholesterol esters, acyl-coenzyme A cholesterol acyltransferase (ACAT1), and multidrug resistance protein (MDR1) mRNA observed in growing cells. Each inhibitor upregulated ATP-binding cassette-A1 (ABCA1), neutral cholesterol ester hydrolase (NCEH) mRNA, and caveolin-1 expression in a manner similar to that of specific inhibitors of cholesterol esterification such as Pg and SaH.
Intracellular modifications of cholesterol homeostasis may be relevant to pterygium development. Moreover, antiproliferative agents such as PIO and EVE may represent a potential topical medication in the prevention and inhibition of pterygium growth at an early stage, probably by modulation of cholesterol ester metabolism.
[Show abstract][Hide abstract] ABSTRACT: The effects of ageing on the metabolism of cholesterol were examined in three different organs (liver, aorta and brain) of 6-, 12- and 24-month-old male Sprague-Dawley rats. Ageing was associated with a significant increase in intracellular cholesterol esters in all three organs. Steady state mRNA levels of multidrug resistance protein (MDR) and acylCoA:cholesterol acyl transferase (ACAT), enzymes involved in cholesterol import and esterification, were also increased. By contrast, expression of mRNA for neutral cholesterol ester hydrolase (nCEH) and caveolin-1, proteins involved in cholesterol ester hydrolysis and export, were significantly reduced. Dietary restriction is the only intervention shown to extend lifespan and retard age-related declines in function in mammals. To further explore the possible correlation between changes in cholesterol esterification and ageing, we analysed cholesterol metabolism in liver, aorta, and brain of aged rats exposed to two dietary restriction regimens: intermittent (alternate-day) fasting (IF) and food intake restriction (60% of ad libitum feeding). Both dietary regimens attenuated the age-related changes in cholesterol esters and in the expression of genes involved in cholesterol metabolism. These results provide evidence that distinctive age-associated changes in intracellular cholesterol metabolism occur in rats. Furthermore, these modifications can be partially reversed by dietary restriction, a condition known to affect the ageing process. Age-related changes in cholesterol metabolism may play a role in triggering and/or aggravating senescence-related disorders characterized by altered cholesterol homeostasis.
Mechanisms of Ageing and Development 06/2005; 126(6-7):648-54. DOI:10.1016/j.mad.2004.11.010 · 3.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of the study was to assess response rate, clinical outcome, organ/function preservation and toxicity in head and neck cancer patients treated with induction chemotherapy followed by concomitant chemoradiotherapy and, when necessary, limited surgery. The study design was a phase II non-randomized trial in hospitalized patients setting. The treatment plan consisted of 3 cycles of induction chemotherapy with cisplatin, fluorouracil (5-FU), leucovorin and interferon alpha2b (PFL-IFN) followed by 7 cycles of 5-FU, hydroxyurea and concomitant radiation for 5 days (FHX) for a total radiation dose of 70 Gy. Surgical resection was performed, when necessary, with the intent to spare organ/function. Seventeen patients were treated at one institution. Three patients had stage III and 14 patients stage IV disease. Twelve patients were analyzed for response to PFL-IFN: 2/12 (16.7%) patients achieved a CR and 10/12 (83.3%) achieved a PR for an ORR of 100%. FHX was administered on protocol to 10 patients: 4 patients (40%) had CR, 3 (30%) had PR >/=70% for an ORR of 70%, 1 patient (10%) had SD and 2 patients (20%) had PD. As for local therapy, of the 8 eligible patients who completed chemoradiotherapy, the 3 patients with CR were submitted to random biopsies, results of which were histologically negative, 3 patients with PR >/=70% underwent conservative organ-preserving surgery, and 1 patient with PR >70% refused surgery, whereas the patient with SD underwent salvage surgery, preserving voice. Thus, organ preservation was achieved in all 8 patients at the completion of all therapy: 4 patients had no surgical procedure and 4 patients only conservative surgery. Overall, after completion of all therapy, 5/8 (62.5%) patients were rendered disease-free. The median overall survival time was 23 months, the median duration of response was 6 months and the median time to progression was 9 months. Both induction chemotherapy and concomitant chemoradiotherapy resulted in significant toxicity, which consisted mainly of mucositis and thrombocytopenia. In conclusion, PFL-IFN was very active, producing high ORRs and, followed by FHX, resulted in high overall survival rates permitting an optimal organ preservation, at the cost of a severe toxicity.
International Journal of Oncology 07/2000; 16(6):1227-33. DOI:10.3892/ijo.16.6.1227 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We planned to conduct a trial of induction chemotherapy followed by concomitant chemoradiotherapy with the goal of organ-function preservation in advanced head and neck cancer patients with the response rate and local control of disease as primary endpoints and the assessment of toxicity as secondary endpoint. The overall treatment plan consisted of 3 cycles, each q. 28 days, of induction chemotherapy with cisplatin, 5-FU, leucovorin and interferon alpha2b (PFL-IFN), followed by response evaluation and local therapy with concomitant chemoradiotherapy with 5-FU, hydroxyurea and concomitant radiotherapy (FHX). The evaluation of clinical response was performed during the 2nd week after the 3rd cycle of induction chemotherapy and FHX was initiated 28 days after the 3rd cycle of induction chemotherapy. Hydroxyurea was administered orally at doses of 1 g every 12 h x 11, 5-FU was administered on days 1 through 5 at 800 mg/m2/d for 5 days. Daily fraction of radiotherapy were administered at 2.0 Gy on days 1 through 5. FHX cycles were repeated every 14 days until completion of radiotherapy. Total radiotherapy doses consisted of 70 Gy. Seventeen patients (mean age 56.53 years, range 40-73, male/female 15/2, site: oral cavity 6, 35.29%; oropharynx 3, 17.6%; hypopharynx 3, 17.65%; larynx 2, 11.76%; paranasal sinuses 2, 11.76%; salivary glands 1, 5.88%; ECOG PS 0/1: 10/7, stage: III/IV 3/14) were enrolled from January 1998 to August 1998. All 17 patients initiated induction chemotherapy on this protocol. Twelve patients were analyzed for response (5 patients were not evaluable): 2/12 (16.7%) patients achieved a CR and 10/12 (83.3%) achieved a PR for an ORR of 100%. Concomitant chemoradiotherapy was administered on protocol to 10 patients: 4 patients (40%) had CR, 3 patients (30%) had PR >/=70% for an ORR of 70%, 1 patient (10%) had SD and 2 patients (20%) had PD. As for local therapy, according to treatment plan, of the 8 eligible patients who completed chemoradiotherapy, the 4 patients with CR were submitted to random biopsies, which resulted histologically negative, the 3 patients with PR >/=70% underwent conservative organ-preserving surgery, the patient with SD underwent salvage surgery, preserving voice. Thus, organ-preservation was achieved in all 8 patients at the completion of all therapy: 4 patients had no surgical procedure and 3 patients only conservative surgery. Overall, after completion of all therapy, 6/8 (75%) patients were rendered disease-free. Both induction chemotherapy and concomitant chemoradiotherapy resulted in significant toxicity, which consisted mainly of mucositis and thrombocytopenia. In conclusion, in the present study we have achieved a good clinical response and an optimal organ preservation, at the cost of a severe toxicity.
[Show abstract][Hide abstract] ABSTRACT: We carried out an open, randomized, phase III, multicenter clinical trial to compare, in neo-adjuvant setting, the clinical response and toxicity of the combination chemotherapy cisplatin + 5-FU with the same combination plus s.c. recombinant interleukin-2 (rIL-2) in patients with advanced (stage III IV) head and neck squamous-cell carcinoma (HNSCC). Regimen A was the classical Al Sarraf treatment: 100 mg/m2 cisplatin i.v. on day 1 plus 1000 mg m(-2) day(-1) 5-FU on days 1-5 as a continuous infusion. Regimen B was the same as regimen A plus 4.5 MIU/day rIL-2 s.c. on days 8-12 and 15-19. Treatment was repeated every 3 weeks for three cycles. A total of 33 patients were enrolled in the study; 30 were evaluable for toxicity and 28 for response. Seventeen patients were assigned to group A and 16 were assigned to group B. Three patients (20%) of group A and 4 (31%) of group B had a complete response, 9 patients (60%) of group A and 6 (46%) of group B had a partial response, with an overall response rate of 12 patients (80%) for group A and 10 patients (77%) for group B. Two patients (13%) of group A and 3 patients (23%) group B had stable disease; 1 patient (7%) of group A had progressive disease. Thus, there was not a statistically significant difference in response rate between the two groups and therefore there was no benefit from the addition of immunotherapy with rIL-2 to the standard chemotherapy. Both regimens were well tolerated. There were 2 toxic deaths (6.7%), 1 from hematological causes in group A and I from cardiac causes in group B. Myelosuppression and gastrointestinal toxicity, mainly nausea/vomiting and stomatitis, were the most frequent toxicities. The calculated number of patients for the sample has not yet been reached; however, the projection of our present results suggests that it is highly improbable that a clinically significant difference between the two treatment groups will be observed even if the calculated patient sample size is achieved.
Cancer Immunology and Immunotherapy 12/1998; 47(3):149-56. DOI:10.1007/s002620050515 · 3.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aims of the present open, randomized, single-blind (patient), single institution, phase II study were: i) to compare the therapeutic effectiveness and toxicity of two dosages and schedules of ifosfamide (IFO) in combination with cisplatin (CDDP) mainly in the neo-adjuvant setting of patients (pts) with locally advanced (stage III-IV) head and neck squamous cell cancer (HNSCC) (primary endpoint); ii) to assess the quality of life (QL) of pts included in the study before and after treatment (secondary endpoint). From July 1996 to June 1997, 28 pts, all males (mean age 56.79 years, range 37-72), hospitalized in the Department of Medical Oncology, University of Cagliari, were enrolled in the study. Twenty pts (M/F 20/0, mean age 53.6, range 37-71 years; stage III 1 pt, stage IV 19 pts) were evaluable for response and all 28 pts enrolled were evaluable for toxicity. Arm A: IFO 2.2 g/m2 i.v. as a 4 h infusion on days 1-5, Mesna 600 mg i.v. as push injection at 0 h, 4 h, 8 h on days 1-5, CDDP 20 mg i.v. as a 60 min infusion on days 1-5. The regimen was repeated every 28 days for 2 cycles. Fifteen pts (11 of whom were evaluable) were enrolled in this Arm. Arm B: IFO 1.5 g/m2 i.v. as a 4 h infusion on days 1-5, Mesna 600 mg i.v. as push injection at 0 h, 4 h, 8 h on days 1-5, CDDP 20 mg i.v. as a 60 min infusion on days 1-5. The regimen was repeated every 28 days for 3 cycles. Thirteen pts (9 of whom were evaluable) were enrolled in this Arm. The two Arms were well-balanced for sex, age, site of primary, ECOG PS and clinical stage. After completion of 2 (Arm A) or 3 (Arm B) cycles of chemotherapy, the pts were assessed for response. All evaluable pts received treatment as planned. Six pts (54.5%) of Arm A and 4 pts (44.5%) of Arm B had partial response (PR) with an overall response rate (ORR) of 54.5% and 44.5%, respectively: it is worth noting that all (100%) pts who had PR in Arm B achieved a high-grade PR, i.e. >/=70%, whereas only one pt (16.7%) who had PR in Arm A achieved a high-grade PR. Three pts (27.3%) in Arm A and 2 pts (22.2%) in Arm B had stable disease (SD); 2 pts (18.2%) in Arm A and 3 pts (33.3%) in Arm B had progressive disease (PD). The actual dose intensity was over 80% of the projected dose intensity for both drugs and for both Arms. Over a total of 59 cycles administered, the total number of episodes of toxicity was 24 for Arm A and 17 for Arm B. Three pts out of 28 evaluable for toxicity (10.8%) died for Grade 5 hematological toxicity: all pts were included in Arm A. In Arm A, 2 pts (13.3%) experienced hematological Grade 3 toxicity and 2 pts (13.3%) hematological Grade 4 toxicity. In Arm B no pt experienced Grade 3-4 hematological toxicity. No Grade 3-4 toxicity of any other type was found in either Arm. The QL evaluation, using the Cella's FACT-G scale supplemented with disease-specific scale (FACT-H&N scale), did not show significant beneficial effect of neo-adjuvant chemotherapy treatment.
[Show abstract][Hide abstract] ABSTRACT: A single-institution, prospective, open crossover study was performed to compare the effectiveness and tolerability of transdermal fentanyl (TTS-F) vs intravenous (i.v.) ondansetron (OND), both combined with i.v. DEX, in the prevention of acute nausea and vomiting (N&V), and TTS-F vs metoclopramide (M), both combined with intramuscular (i.m.) DEX, in the prevention of delayed N&V in patients with advanced stage head and neck squamous cell carcinoma receiving high-dose (> or = 100 mg/m2) cisplatin. This is the first report on the clinical use of TTS-F in this setting. PATIENTS AND METHODS: All patients were adequately informed of the study characteristics and gave their written informed consent before study entry. The antiemetic treatment for acute N&V consisted of A) OND 8 mg plus DEX 20 mg (i.v.) or B) TTS-F 75 micrograms/h plus DEX 20 mg i.v. For prevention of delayed N&V, patients receiving TTS-F for acute N&V were given TTS-F at the same dosage (75 micrograms/h) on days 2-5, whereas patients receiving OND for acute N&V were treated with M 20 mg orally every 6 h on days 2-5, starting 24 h after CDDP. All patients received DEX 8 mg i.m. every 12 h on days 2 and 3, 4 mg i.m. every 12 h on days 4 and 5, starting 24 h after CDDP. From November 1997 to April 1998, 15 consecutive patients entered the study and were assigned to one of the two alternative treatments for acute N&V. All of them were evaluable. Twelve patients were evaluable for delayed N&V. Seven patients were assigned to Group 1 starting with treatment A (OND + DEX) and 8 patients were assigned to Group 2 starting with treatment B (TTS-F + DEX). In the prevention of acute N&V, the overall efficacy of OND + DEX was statistically significantly higher than that of TTS-F + DEX in achieving Complete Response (CR) and Major Efficacy (ME = CR + Major Response, MaR). As for delayed N&V, the overall efficacy of M + DEX, both in achieving CR and ME, although higher, was statistically not significantly different from that of TTS-F + DEX. Unfortunately, due to the small number of patients included in the study, the sophisticated criteria for evaluating response in antiemetic research, such as the persistence of efficacy, the response after crossing-over, did not make it possible for us to draw additional conclusions, although the trend was in favor of "standard" treatments, particularly in acute N&V. The 'response to treatment A (OND + DEX) in the prevention of acute N&V was in the same range as the response to treatment A (M + DEX) for delayed N&V. The response to treatment B (TTS-F) for acute N&V was lower than the response to the same treatment for delayed N&V. The TTS-F treatment was well-tolerated with no significant side-effects including the well-known opioid-related symptoms. Our study confirms that the currently available standard antiemetic treatments both for acute and delayed N&V must be considered by far the most effective ones for clinical use.
Anticancer research 19(4C):3495-502. · 1.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Controversies exist regarding the classification of the emetogenic potential of chemotherapeutic agents such as taxanes, gemcitabine and irinotecan and the antiemetic prophylaxis for acute emesis to be administered. Instead, no prophylaxis for delayed emesis has been suggested. A prospective, observational study was carried out in 103 Italian oncological centers to evaluate the prescriptions of antiemetics and the incidence of nausea and vomiting in patients submitted to these chemotherapy agents. Two hundred and nine patients treated with taxanes, 300 with gemcitabine and 93 with irinotecan were evaluated. For the prophylaxis of acute emesis a 5-HT3 antagonist alone or in combination with a corticosteroid was administered to 86.6% of patients receiving taxanes, to 59.3% of those receiving gemcitabine and to 96.8% of those submitted to irinotecan. 20% to 40% of patients received antiemetic prophylaxis for delayed emesis. In taxane-treated patients the incidence of acute vomiting and nausea was 6.2% and 27.3%, respectively, while in gemcitabine- and irinotecan-treated patients it was 6.0/33.4% and 17.9/58.9%, respectively. In conclusion, the study showed that almost all patients received prophylaxis for acute emesis and that there is overprescription of 5-HT3 antagonists. The incidence of acute emesis is low; therefore, randomized clinical trials are necessary to verify the utility of prophylaxis and to find the best antiemetic treatment.
[Show abstract][Hide abstract] ABSTRACT: Scrapie is an infective ovine neurodegenerative disease; the only identified component of the infectious agent being an aberrant isoform (PrPSc) of the cellular prion protein (PrPC). So far, no means for ante-mortem diagnosis are available for Scrapie as well as for any other mammal Transmissible Spongiform Encephalopaties. We recently found a strong relationship between cell susceptibility to scrapie-infection and intracellular cholesterol homeostasis alterations. In brain tissues as well as in ex vivo cultures of skin fibroblasts and PBMCs from healthy and scrapie-affected sheep carrying a scrapie-susceptible (ARQ/ARQ) genotype, the levels of cholesterol esters were consistently higher than in tissues and cultures derived from animals with a scrapie-resistant (ARR/ARR) genotype. Moreover, both uninfected and scrapie-affected ARQ/ARQ sheep showed abnormally low levels of high density lipoprotein-cholesterol (HDL-C) in their plasma, as compared to ARR/ARR animals. We now show that intracellular accumulation of cholesterol esters in fibroblasts derived from scrapie-susceptible sheep was accompanied by parallel alterations in the expression level of genes and gene products (ACAT1 and Cav-1) that are involved in the pathways leading to intracellular cholesterol esterification and trafficking. Comparative analysis of PrPc mRNA, showed an higher expression level in cells from animals carrying susceptible genotype, with or without Scrapie. Preliminary experiments also revealed the presence of PK-resistant PrP isoforms in the latter cultures. The data reported in the present paper suggest that accumulation of cholesterol esters in peripheral cells, together with the altered expression of some proteins implicated in intracellular cholesterol homeostasis, might serve to identify a distinctive lipid metabolic profile associated with increased susceptibility to develop prion disease following infection.
[Show abstract][Hide abstract] ABSTRACT: Background. Previous epidemiological and experimental studies indicated cholesterol as a central player in Alzheimer disease (AD). Here, we utilized skin fibroblasts and PBMC as possible ex vivo models for the study of dysfunctions of cholesterol homeostasis which may be related to AD development.
Methods. We analyzed cholesterol homeostasis using colorimetric, thin layer chromatography (TLC), and histologic technique in ex vivo cultures of skin fibroblasts and PBMCs from patients with probable AD and their first-degree relatives. Additionally, healthy age-matched individuals served as controls.
Findings. As compared to controls, skin fibroblasts and PBMCs from AD patients, displayed an evident alteration of cholesterol metabolism; namely an anomalous accumulation of cholesterol esters in their cytoplasm. No change in intracellular free cholesterol was observed. Cellular overloading of cholesterol esters was dramatically increased after specific growth stimulation of the different cell types. Cholesterol ester accumulation was negatively correlated to plasma levels of high density lipoprotein cholesterol (HDL-C) and positively correlated with severity of cognitive symptoms measured by Mini-Mental State Examination (MMSE). Inhibitors of cholesterol esterification, such as progesterone and SaH, as well as a potent inhibitor of cell proliferation, RAD, were able to prevent accumulation of cholesterol esters.
Interpretation. Changes of cholesterol esters in the peripheral compartment may be indicative of a systemic alteration of intracellular cholesterol homeostasis, which in turn might create a cellular milieu favourable to the production of ß-amyloid in the brain. Pathways that control cholesterol esterification might represent promising targets for novel diagnostic and therapeutic AD approaches.
[Show abstract][Hide abstract] ABSTRACT: Recent studies in both animal and cell models of Alzheimer's disease (AD) indicated that sub-cellular cholesterol distribution seems to regulate amyloid-beta (A[beta]) generation in the brain. In particular, cholesterol-esters (CE), rather than total cholesterol levels, appear directly correlated with A[beta] production. Here we observed that, similarly to brain cells, skin fibroblasts obtained from AD patients produce and accumulate more CE than skin fibroblasts from age-matched healthy controls do. AD fibroblasts also exhibited a 2 fold increase in the expression of ACAT1, in addition to lower levels of SREBP2, nCEH, Caveolin-1 and ABCA1 mRNA levels, all of which are involved in the CE cycle. HMGCoA-reductase and LDL-receptor mRNAs levels did not show statistically significant changes in AD, compared to non-AD, cells. Furthermore, although APP mRNA did not significantly vary, neprilysin (NEP), the most important enzyme in the proteolysis of A[beta], was expressed at very low levels in skin fibroblasts of sporadic AD patients. Our results contribute to the concept that AD may be the consequence of a basic and systemic defect in the CE cycle. Moreover, our results identify new possible targets for the diagnosis, prevention, and cure or, at least, amelioration of the symptoms of AD.