Proton Therapy, Magnetic Nanoparticles and Hyperthermia as Combined Treatment for Pancreatic BxPC3 Tumor Cells

We present an investigation of the effects on BxPC3 pancreatic cancer cells of proton therapy combined with hyperthermia, assisted by magnetic fluid hyperthermia performed with the use of magnetic nanoparticles. The cells' response to the combined treatment has been evaluated by means of the clonogenic survival assay and the estimation of DNA Double Strand Breaks (DSBs). The Reactive Oxygen Species (ROS) production, the tumor cell invasion and the cell cycle variations have also been studied. The experimental results have shown that the combination of proton therapy, MNPs administration and hyperthermia gives a clonogenic survival that is much smaller than the single irradiation treatment at all doses, thus suggesting a new effective combined therapy for the pancreatic tumor. Importantly, the effect of the therapies used here is synergistic. Moreover, after proton irradiation, the hyperthermia treatment was able to increase the number of DSBs, even though just at 6 h after the treatment. Noticeably, the magnetic nanoparticles' presence induces radiosensitization effects, and hyperthermia increases the production of ROS, which contributes to cytotoxic cellular effects and to a wide variety of lesions including DNA damage. The present study indicates a new way for clinical translation of combined therapies, also in the vision of an increasing number of hospitals that will use the proton therapy technique in the near future for different kinds of radio-resistant cancers.

Decommissioning procedure and induced activation levels, calculations and measurements in an 18 MeV medical cyclotron

The present article describes the decommissioning of a self-shielded 18 MeV medical cyclotron IBA Cyclone 18/9 after 14 years of operation. A Monte Carlo simulation of the possible nuclear reactions was performed in order to plan the decommissioning activities. During the cyclotron dismantling, the activities of the cyclotron components, concrete wall and floor samples were measured. Residual activities were analysed by means of an HPGe detector and liquid scintillation counting, and compared with simulation data. Dosimetry of the staff involved in the decommissioning procedure was monitored by individual TL dosimeters and/or digital dosimeter. The cyclotron component analysis confirmed the presence of gamma and pure beta emitters,²²Na,⁵⁴Mn,⁶⁰Co,⁶⁵Zn,²⁰⁷Bi,⁵⁵Fe,⁶³Ni at different values of specific activity, depending on the positioning of the sample point and on the alloy of the sampled part. In these components the presence of gamma and pure beta emitters was measured 5 years after the shutdown at levels far above clearance limits as defined by the 'Recommended radiological protection criteria for the recycling of metals from the dismantling of nuclear installations' (RP89) guidelines. The simulation, carried out by FLUKA Code (version 2020.0.5) on the cyclotron components, provided good agreement with measurements, with a maximum discrepancy of the same order as the uncertainties. Four engineers of the cyclotron maintenance staff were involved in the dismounting of the hottest components and rigging of the cyclotron in the deposit 6 months after shutdown and two engineers were involved during the drilling phase 3.5 years after shutdown. The measured dose from external exposure of the involved staff was lower than 100μSv person^-1during the first phase and lower than 20μSv person^-1during the final drilling phase. Measured doses from intake were negligible. In conclusion, the decommissioning of the 18 MeV cyclotron does not represent a risk for the involved staff, but, due to the presence of long-lived radioisotopes, the cyclotron components are to be treated as low level radioactive waste, and stored in an authorised storage area for at least 25 years after shutdown.

Metallobiochemistry of ultratrace levels of bismuth in the rat II. Interaction of 205+206Bi3+ with tissue, intracellular and molecular components

BACKGROUND

Knowledge on Bi metabolism in laboratory animals refers to studies at "extreme" exposures, i.e. pharmacologically relevant high-doses (mg kg^-1 b.w.) in relation to its medical use, or infinitesimal doses (pg kg^-1b.w.) concerning radiobiology protection and radiotherapeutic purposes. There are no specific studies on metabolic patterns of environmental exposure doses (ultratrace level, μg kg^-1 b.w.), becoming in this context Bi a "heavy metal fallen into oblivion". We previously reported the results of the metabolic fate of ultratrace levels of Bi in the blood of rats [1]. In reference to the same study here we report the results of the retention and tissue binding of Bi with intracellular and molecular components.

METHODS

Animals were intraperitoneally injected with 0.8 μg Bi kg^-1 b.w. as ^205+206Bi(NO)₃, alone or in combination with ⁵⁹Fe for the radiolabeling of iron proteins. The use of ^205+206Bi radiotracer allowed the determination of Bi down to pg fg^-1 in biological fluids, tissues, subcellular fractions, and biochemical components isolated by differential centrifugation, size exclusion chromatography, solvent extraction, precipitation, immunoprecipitation and dialysis.

MAIN FINDINGS

At 24 h post injection the kidney contained by far the highest Bi concentration (10 ng g^-1 wt.w.) followed by the thymus, spleen, liver, thyroid, trachea, femur, lung, adrenal gland, stomach, duodenum and pancreas (0.1 to 1.3 ng g^-1 wt.w.). Brain and testis showed smaller but consistently significant concentrations of the element (0.03 ng g^-1 wt.w). Urine was the predominant route of excretion. Intracellularly, liver, kidney, spleen, testis, and brain cytosols displayed the highest percentages (35%-58%) of Bi of homogenates. Liver and testis nuclei were the organelles with the highest Bi content (24 % and 27 %). However, when the recovered Bi of the liver was recorded as percent of total recovered Bi divided by percent of total recovered protein the lysosomes showed the highest relative specific activity than in other fractions. In the brain subcellular fractions Bi was incorporated by neuro-structures with the protein and not lipidic fraction of the myelin retaining 18 % of Bi of the total homogenate. After the liver intra-subcellular fractionation: (i) 65 % of the nuclear Bi was associated with the protein fraction of the nuclear membranes and 35 % with the bulk chromatin bound to non-histone and DNA fractions; (ii) about 50 % of the mitochondrial Bi was associated with inner and outer membranes being the other half recovered in the intramitochondrial matrix; (iii) in microsomes Bi showed a high affinity (close to 90 %) for the membranous components (rough and smooth membranes); (iv) In the liver cytosol three pools of Bi-binding proteins (molecular size > 300 kDa, 70 kDa and 10 kDa) were observed with ferritin and metallothionein-like protein identified as Bi-binding biomolecules. Three similar protein pools were also observed in the kidney cytosol. However, the amount of Bi, calculated in percent of the total cytosolic Bi, were significantly different compared to the corresponding pools of the liver cytosol.

CONCLUSIONS

At the best of our knowledge the present paper represents the first in vivo study, on the basis of an environmental toxicology approach, aiming at describing retention and binding of Bi in the rat at tissue, intracellular and molecular levels.

Metallobiochemistry of ultratrace levels of bismuth in the rat I. Metabolic patterns of 205+206Bi3+ in the blood

BACKGROUND

The number of the applications of bismuth (Bi) is rapidly and remarkably increasing, enhancing the chance to increase the levels to which humans are normally daily exposed. The interest to Bi comes also from the potential of Bi-based nanoparticles (BiNPs) for industrial and biomedical purposes. Like other metal-based NPs used in nanomedicine, BiNPs may release ultratrace amounts of Bi ions when injected. The metabolic fate and toxicity of these ions still needs to be evaluated. At present, knowledge of Bi metabolism in laboratory animals refers almost solely to studies under unnatural "extreme" exposures, i.e. pharmacologically relevant high-doses (up to thousand mg kg^-1) in relation to its medical use, or infinitesimal-doses (pg kg^-1 as non-carrier-added Bi radioisotopes) for radiobiology protection, diagnostic and radiotherapeutic purposes. No specific study exists on the "metabolic patterns" in animal models exposed to levels of Bi, i.e. at "environmental dose exposure" that reflect the human daily exposure (μg kg^-1).

METHODOLOGY

Rats were intraperitoneally injected with 0.8 μg Bi kg^-1 bw as ^205+206Bi(NO)₃ alone or in combination with ⁵⁹Fe for radiolabelling of iron proteins. The use of ^205+206Bi radiotracers allowed the detection and measurement down to pg fg^-1 of the element in the blood biochemical compartments and protein fractions as isolated by differential centrifugation, size exclusion- and ion exchange chromatography, electrophoresis, solvent extraction, precipitation and dialysis.

RESULTS

24 h after the administration, the blood concentration of Bi was 0.18 ng mL^-1, with a repartition plasma/red blod cells (RBC) in a ratio of 2:1. Elution profiles of plasma from gel filtration on Sephadex G-150 showed four pools of Bi-binder proteins with different molecular sizes (> 300 kDa, 160 kDa, 70 kDa and < 6.5 kDa). In the 70 kDa fraction transferrin and albumin were identified as biomolecule carriers for Bi. In red blood cells, Bi was distributed between cytosol and membranes (ghosts) in a ratio of about 5:1. In the cytosol, low molecular components (LMWC) and the hemoglobin associated the Bi in a ratio of about 1.8:1. In the hemoglobin molecule, Bi was bound to the beta polypeptide chain of the globin. In the ghosts, Bi was detected at more than one site of the protein fraction, with no binding with lipids. Dialysis experiments and the consistently high recovery (80-90 %) of ²⁰⁶Bi from chromatography of ²⁰⁶Bi-containing biocomponents suggest that Bi was firmly complexed at physiological pH with a low degree of breaking during the applications of experimental protocols for the isolation of the ²⁰⁶Bi-biocomplexes. These latter were sensitive to acid buffer pH 5, and to the presence of complexing agents in the dialysis fluid.

CONCLUSIONS

On the basis of an environmental biochemical toxicology approach, we have undertaken a study on the metabolic patterns of Bi³⁺ ions in rats at tissue, subcellular and molecular level with the identification of cellular Bi-binding components. As a first part of the study the present work reports the results concerned with the metabolic fate of ultratrace levels of ^205+206Bi(NO)₃ in the blood.

Genotoxicity and Immunotoxicity of Titanium Dioxide-Embedded Mesoporous Silica Nanoparticles (TiO2@MSN) in Primary Peripheral Human Blood Mononuclear Cells (PBMC)

Background: TiO₂ nanoparticles (TiO₂ NPs) are the nanomaterial most produced as an ultraviolet (UV) filter. However, TiO₂ is a semiconductor and, in nanoparticle size, is a strong photocatalyst, raising concerns about photomutagenesis. Mesoporous silica nanoparticles (MSN) were synthetized incorporating TiO₂ NPs (TiO₂@MSN) to develop a cosmetic UV filter. The aim of this study was to assess the toxicity of TiO₂@MSN, compared with bare MSN and commercial TiO₂ NPs, based on several biomarkers. Materials and Methods: Human peripheral blood mononuclear cells (PBMC) were exposed to TiO₂@MSN, bare MSN (network) or commercial TiO₂ NPs for comparison. Exposed PBMC were characterized for cell viability/apoptosis, reactive oxygen species (ROS), nuclear morphology, and cytokines secretion. Results: All the nanoparticles induced apoptosis, but only TiO₂ NPs (alone or assembled into MSN) led to ROS and micronuclei. However, TiO₂@MSN showed lower ROS and cytotoxicity with respect to the P25. Exposure to TiO₂@MSN induced Th2-skewed and pro-fibrotic responses. Conclusions: Geno-cytotoxicity data indicate that TiO₂@MSN are safer than P25 and MSN. Cytokine responses induced by TiO₂@MSN are imputable to both the TiO₂ NPs and MSN, and, therefore, considered of low immunotoxicological relevance. This analytical assessment might provide hints for NPs modification and deep purification to reduce the risk of health effects in the settings of their large-scale manufacturing and everyday usage by consumers.

Hadron Therapy, Magnetic Nanoparticles and Hyperthermia: A Promising Combined Tool for Pancreatic Cancer Treatment

A combination of carbon ions/photons irradiation and hyperthermia as a novel therapeutic approach for the in-vitro treatment of pancreatic cancer BxPC3 cells is presented. The radiation doses used are 0–2 Gy for carbon ions and 0–7 Gy for 6 MV photons. Hyperthermia is realized via a standard heating bath, assisted by magnetic fluid hyperthermia (MFH) that utilizes magnetic nanoparticles (MNPs) exposed to an alternating magnetic field of amplitude 19.5 mTesla and frequency 109.8 kHz. Starting from 37 °C, the temperature is gradually increased and the sample is kept at 42 °C for 30 min. For MFH, MNPs with a mean diameter of 19 nm and specific absorption rate of 110 ± 30 W/g_Fe3o₄ coated with a biocompatible ligand to ensure stability in physiological media are used. Irradiation diminishes the clonogenic survival at an extent that depends on the radiation type, and its decrease is amplified both by the MNPs cellular uptake and the hyperthermia protocol. Significant increases in DNA double-strand breaks at 6 h are observed in samples exposed to MNP uptake, treated with 0.75 Gy carbon-ion irradiation and hyperthermia. The proposed experimental protocol, based on the combination of hadron irradiation and hyperthermia, represents a first step towards an innovative clinical option for pancreatic cancer.

On the production of 52gMn by deuteron irradiation on natural chromium and its radionuclidic purity

The positron emitter ^52gMn is used for the Positron Emission Tomography - PET imaging.In this work we investigate the nuclear reactions for production of ^52gMn and ⁵⁴Mn induced by deuteron beams on natural chromium targets at energies up to E_d = 28 MeV using the stacked-foils activation technique. We calculate the thick target yields for ^52gMn and for the radionuclidic impurity ⁵⁴Mn, and we compare the radionuclidic purity of ^52gMn with that achievable in proton activation of Cr. The cross-sections of the reactions ^natCr(d,pxn)⁵¹Cr and ^natCr(d,x)⁴⁸V are also presented.

Treatment of aqueous wastes by means of Thermophilic Aerobic Membrane Reactor (TAMR) and nanofiltration (NF): process auditing of a full-scale plant

This work focuses on the Thermophilic Aerobic Membrane Reactor (TAMR) process. The research was carried out on a full-scale facility where, all along a 12-year period, daily monitoring and process audit tests were conducted for the process analysis and optimization. The plant treated -light and high-strength aqueous wastes and two different configurations were adopted: (1) thermophilic biological reactor + ultrafiltration (TAMR) and (2) TAMR + nanofiltration (TAMR + NF). In the latter case, the average chemical oxygen demand removal yield was equal to 89% and an effective denitrification (nitrogen oxides removal equal to 96%) was achieved by reducing the dissolved oxygen concentration in the bioreactor. Low specific sludge production was observed. Poor sludge settling properties were measured by a lab-scale settling test; respirometric tests (nitrogen uptake rate and ammonia uptake rate) showed the presence of denitrification and the inhibition of nitrification. Hydrodynamic tests revealed the presence of a significant dead space, thus showing room for improving the overall process performance. Finally, the rheological properties of the sludge were measured as a function of the biomass concentration, pH, temperature, and aeration scheme.

Excitation function and yield for the 103Rh(d,2n)103Pd nuclear reaction: Optimization of the production of palladium-103

Deuteron-induced nuclear reactions for the generation of ¹⁰³Pd were investigated using the stacked-foil activation technique on rhodium targets at deuteron energies up to E_d=33MeV. The excitation functions of the reactions ¹⁰³Rh(d,xn)^101,103Pd, ¹⁰³Rh(d,x)^{100g,cum,101m,g,102m,g}Rh and ¹⁰³Rh(d,2p)¹⁰³Ru have been measured, and the Thick-Target Yield for ¹⁰³Pd has been calculated.

CyclinD-CDK4/6 complexes phosphorylate CDC25A and regulate its stability

The phosphatase CDC25A is a key regulator of cell cycle progression by dephosphorylating and activating cyclin-CDK complexes. CDC25A is an unstable protein expressed from G1 until mitosis. CDC25A overexpression, which can be caused by stabilization of the protein, accelerates the G1/S and G2/M transitions, leading to genomic instability and promoting tumorigenesis. Thus, controlling CDC25A protein levels by regulating its stability is a critical mechanism for timing cell cycle progression and to maintain genomic integrity. Herein, we show that CDC25A is phosphorylated on Ser40 throughout the cell cycle and that this phosphorylation is established during the progression from G1 to S phase. We demonstrate that CyclinD-CDK4/CDK6 complexes mediate the phosphorylation of CDC25A on Ser40 during G1 and that these complexes directly phosphorylate this residue in vitro. Importantly, we also find that CyclinD1-CDK4 decreases CDC25A stability in a ßTrCP-dependent manner and that Ser40 and Ser88 phosphorylations contribute to this regulation. Thus our results identify cyclinD-CDK4/6 complexes as novel regulators of CDC25A stability during G1 phase, generating a negative feedback loop allowing control of the G1/S transition.

Phytotoxicity of ionic, micro- and nano-sized iron in three plant species

Potential environmental impacts of engineered nanoparticles (ENPs) can be understood taking into consideration phytotoxicity. We reported on the effects of ionic (FeCl3), micro- and nano-sized zerovalent iron (nZVI) about the development of three macrophytes: Lepidium sativum, Sinapis alba and Sorghum saccharatum. Four toxicity indicators (seed germination, seedling elongation, germination index and biomass) were assessed following exposure to each iron concentration interval: 1.29-1570mg/L (FeCl3), 1.71-10.78mg/L (micro-sized iron) and 4.81-33,560mg/L (nano-iron). Exposure effects were also observed by optical and transmission electron microscopy. Results showed that no significant phytotoxicity effects could be detected for both micro- and nano-sized zerovalent irons, including field nanoremediation concentrations. Biostimulation effects such as an increased seedling length and biomass production were detected at the highest exposure concentrations. Ionic iron showed slight toxicity effects only at 1570mg/L and, therefore, no median effect concentrations were determined. By microscopy, ENPs were not found in palisade cells or xylem. Apparently, aggregates of nZVI were found inside S. alba and S. saccharatum, although false positives during sample preparation cannot be excluded. Macroscopically, black spots and coatings were detected on roots of all species especially at the most concentrated treatments.

The metallobiochemistry of ultratrace levels of platinum group elements in the rat

The use of platinum, palladium and rhodium (Platinum Group Elements - PGEs) and the possibility of exposure to their ultratrace levels is increasing. In fact, the exponential development of metallic PGE-based nanoparticles (<100 nm in size) opens extraordinary perspectives in the areas of electrocatalysts and catalytic converters, magnetic nanopowders, polymer membranes, cancer therapy, coatings, plastics, nanofibres and textiles. Like other metal-based nanoparticles, exposure to PGEs nanoparticles may result in a release of ultratrace amounts of Pt, Pd, Rh ions in the body whose metabolic fate and toxicity still need to be evaluated. Furthermore, PGEs can act as allergic sensitizers by acting as haptens and inducing both type I and IV allergic reactions. In this work we studied the in vivo metabolic patterns of ultratrace levels of potent allergens and sensitizers PGE halogenated salts. (191)Pt, (103)Pd and (101m)Rh radioisotopes were prepared via cyclotron irradiation and used for radiolabelling Na2(191)PtCl4, Na2(103)PdCl4 and Na2(101m)RhCl6 salts. These anionic chlorocomplexes were intraperitoneally injected into rats (114 ng Pt kg(-1) bodyweight; 24 ng Pd kg(-1) b.w.; 16 ng Rh kg(-1) b.w.). At 16 h post-exposure, PGEs were poorly but significantly retained in all tissues analysed. Kidneys, spleen, adrenal gland, liver, pancreas and small intestine were the organs with the highest Pt, Pd, Rh concentrations. In the blood 30-35% of (103)Pd and (191)Pt and 10% of (101m)Rh were recovered in the plasma, mainly bound to albumin and to a less extent to transferrin. The hepatic and renal intracellular distribution showed the highest recovery of (191)Pt, (103)Pd and (101m)Rh in the nuclear fraction (liver) and in the cytosol (kidney). Chromatographic separation and ultrafiltration experiments on kidney and liver cytosols showed the strong ability of biochemical macromolecules to bind (191)Pt, (103)Pd and (101m)Rh, and being responsible for the retention of the three elements in the body. The link to macromolecules is the basis for the sensitizing capacity of PGEs.

Uptake from water, internal distribution and bioaccumulation of selenium in Scenedesmus obliquus, Unio mancus and Rattus norvegicus: part A

The (75)Se internal bioavailability was investigated in microalgae, mussels and rats as biological experimental models. The (75)Se accumulation from freshwater to microalgae [Scenedesmus obliquus (Turpin) Kützing], from freshwater to mussels (Unio mancus Lamark) and, finally, per os to rats (Rattus norvegicus Berkenhout) was followed using (75)Se-labelled selenite looking at (75)Se uptake, retention, intracellular distribution and binding with cellular biocomplexes. After exposure to 10, 50 and 500 μg Se L(-1), the microalgae showed an inhibitory effect on population growth only at the highest concentration. Mussels exposed to 105 μg Se L(-1) showed an accumulation of the element with time in all tissues. Intracellularly, Se was present in all subcellular fractions, especially in the cytosol. Rats were treated via oral administration with 5 μg Se rat(-1). After 24 h, liver and kidney showed the highest Se concentration.

Uptake from water, internal distribution and bioaccumulation of selenium in Scenedesmus obliquus, Unio mancus and Rattus norvegicus: part B

(75)Se-selenite transfer was investigated in a phytoplankton-mussel-rat food chain model consisting of Scenedesmus obliquus (Turpin) Kützing, Unio mancus Lamark and Rattus norvegicus Berkenhout. (75)Se-metabolized forms were investigated in order to identify potential critical steps in the food chain, as well as its relative bioavailability looking also at intracellular, cellular and organ partitioning. Tissue and intracellular distribution of (75)Se in mussels fed with (75)Se-S. obliquus was different compared to those exposed only to inorganic (75)Se-selenite. The intracellular distribution of (75)Se in the hepatopancreas and mantle of mussels fed (75)Se-microalgae was similar to hepatic and renal distributions in rats, suggesting that their stomach dissociated larger (75)Se-containing molecules. The (75)Se partitioned from water (culture medium) to microalgae showing a bioconcentration factor of 435. The bottleneck in the trophic transfer of (75)Se occurred between S. obliquus-U. mancus. From microalgae to mussels and subsequently to rats no bioaccumulation was verified.

Excitation functions and yields for cyclotron production of radiorhenium via deuteron irradiation: natW(d,xn)181,182(A+B),183,184(m+g),186gRe nuclear reactions and tests on the production of 186gRe using enriched 186W

Excitation functions, thin- and thick-target yields for the 181−186gRe and 187W radionuclides were measured by the activation stacked-foil thecnique on natural tungsten foils for deuteron energies up to 18.0 MeV. These cross sections were validated by comparing the experimental results for thick-target yields with those calculated by integration of the thin-target yields. It was found that the maximum 186gRe content by irradiation of natural tungsten is about 55%, a higher value compared with the one found for proton beam, but not sufficient to use natural tungsten for medical purposes yet. Thus, in order to have a higher specific activity A S of 186gRe, the use of enriched 186W target is necessary. Therefore the irradiation of a thick target of enriched 186W by accelerated deuterons was studied and the results for the production of 186gRe were compared with those obtained from the irradiation of the same target by accelerated protons. It was found that the deuteron irradiation is preferable for three reasons: larger yield, less contamination by tantalum radioisotopes and smaller required amount of the target, which simplify the separation of the 186gRe from the target itself.

Mitochondrial energetic and AKT status mediate metabolic effects and apoptosis of metformin in human leukemic cells

Previous reports demonstrate that metformin, an anti-diabetic drug, can decrease the risk of cancer and inhibit cancer cell growth. However, its mechanism in cancer cells is still unknown. Metformin significantly blocks cell cycle and inhibits cell proliferation and colony formation of leukemic cells. However, the apoptotic response to metformin varies. Furthermore, daily treatment with metformin induces apoptosis and reduces tumor growth in vivo. While metformin induces early and transient activation of AMPK, inhibition of AMPKα1/2 does not abrogate anti-proliferative or pro-apoptotic effects of metformin. Metformin decreases electron transport chain complex I activity, oxygen consumption and mitochondrial ATP synthesis, while stimulating glycolysis for ATP and lactate production, pentose phosphate pathway for purine biosynthesis, fatty acid metabolism, as well as anaplerotic and mitochondrial gene expression. Importantly, leukemic cells with high basal AKT phosphorylation, glucose consumption or glycolysis exhibit a markedly reduced induction of the Pasteur effect in response to metformin and are resistant to metformin-induced apoptosis. Accordingly, glucose starvation or treatment with deoxyglucose or an AKT inhibitor induces sensitivity to metformin. Overall, metformin elicits reprogramming of intermediary metabolism leading to inhibition of cell proliferation in all leukemic cells and apoptosis only in leukemic cells responding to metformin with AKT phosphorylation and a strong Pasteur effect.

Estimates of cancer burden in Liguria

Aims and background

The regional health care system of Liguria caters for a resident population which is among the oldest in Europe. One population-based cancer registry is present in the region, providing incidence and survival data for the Genoa province (covering 55% of the regional population). This paper will estimate the incidence, prevalence and mortality in the Liguria region for cancers of the lung, breast, prostate, colon-rectum, stomach and uterine cervix and melanoma of the skin in 1970—2015.

Methods

The estimated figures were obtained by applying the MIAMOD method. Starting from mortality and survival data, incidence and prevalence were derived using a statistical back-calculation approach. Survival was modeled on the basis of published data from the Italian cancer registries. The MIAMOD method was applied also to estimate the colorectal cancer incidence, mortality and prevalence rates in the Ligurian provinces in the period 1988—2015.

Results

In 2012 about 1,500 new cases of breast cancer were expected in Ligurian women. The estimates for the other cancer sites were considerably lower, ranging from 839 (colon-rectum) to 54 (cervix). In men about 1,400 new cases were estimated for prostate cancer, while the incidence for the other sites ranged from 1,118 (colon-rectum) to 208 (skin melanoma). The breast cancer prevalence rate was more than 10 times the incidence rate in women, and the lung cancer prevalence rate was more than double the incidence rate in both sexes. Mortality rates were highest for lung cancer in men and breast cancer in women; the lowest rates were estimated for melanoma and cancer of the uterine cervix.

Conclusion

In Liguria a large portion of the health expenditure has been devoted to diagnostic and therapeutic resources. This may have contributed to the reduction of mortality rates and to the improvement of cancer survival. This phenomenon, added to population aging, will inflate the cancer prevalence. One of the major challenges for the Liguria region is to face the increasing demand for oncology services.

Fukushima fallout at Milano, Italy

The radionuclides (131)I, (137)Cs and (134)Cs were observed in the Milano region (45°) of Italy early after the nuclear accident in Fukushima, Japan. Increased atmospheric radioactivity was observed on an air filter taken on 30 March 2011, while the maximum activity of 467 μBq m(-3) for (131)I was recorded at April 3-4, 2011. The first evidence of Fukushima fallout was confirmed with (131)I and (137)Cs measured in precipitation at two sampling sites at Milano on 28 March, 2011, with the concentrations of (131)I and (137)Cs in the rainwater equal to 0.89 Bq L(-1) and 0.12 Bq L(-1), respectively. A sample of dry deposition that was collected 9 days after the first rainfall event of 27-28 March, 2011 showed that the dry deposition was more effective in the case of (137)Cs than it was for (131)I, probably because iodine was mainly in gaseous form whereas caesium was rapidly bound to aerosols and thus highly subject to dry deposition. The relatively high observed values of (137)Cs in grass, soil and fresh goat and cow milk samples were probably from Chernobyl fallout and global fallout from past nuclear tests rather than from the Fukushima accident. Finally, a dose assessment for the region of investigation showed clearly that the detected activities in all environmental samples were very far below levels of concern.

The short form of RON is expressed in acute myeloid leukemia and sensitizes leukemic cells to cMET inhibitors

Several receptor tyrosine kinases (TKs) are involved in the pathogenesis of acute myeloid leukemia (AML). Here, we have assessed the expression of the Recepteur d'Origine Nantais (RON) in leukemic cell lines and samples from AML patients. In a series of 86 AML patients, we show that both the full length and/or the short form (sf) of RON are expressed in 51% and 43% of cases, respectively. Interestingly, sfRON is not expressed in normal CD34+ hematopoietic cells and induces part of its oncogenic signaling through interaction with the Src kinase Lyn. sfRON-mediated signaling in leukemic cells also involves mTORC1, the proapoptotic bcl2-family member, BAD, but not the phosphatidylinositol 3-kinase/Akt pathway. Furthermore, the expression of sfRON was specifically downregulated by 5-azacytidine (AZA). Conversely, AZA could induce the expression of sfRON in sfRON-negative leukemic cells suggesting that the activity of this drug in AML and myelodysplastic syndromes could involve modulation of TKs. cMET/RON inhibitors exhibited an antileukemic activity exclusively in AML samples and cell lines expressing sfRON. These results might support clinical trials evaluating cMET/RON inhibitors in AML patients expressing sfRON.

Tracking of airborne radionuclides from the damaged Fukushima Dai-ichi nuclear reactors by European networks

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

Colonic mast cells in controls and slow transit constipation patients

BACKGROUND

There is recent evidence that mast cells may play important roles in the gut, especially concerning visceral hypersensitivity and motor activity. However, most data are only available for clinical conditions characterised by diarrhoea, where MC have chiefly investigated in the mucosal layer of the colon and there is almost no information concerning constipation.

AIM

To investigate mast cells distribution in all colonic layers in controls and severely constipated patients.

METHODS

Full-thickness specimens from colons of patients undergoing surgery for slow transit constipation (n=29), compared with controls, were obtained and the number of mast cells (evaluated by specific monoclonal antibodies) counted as a whole and in single colonic segments (caecum, ascending, transverse, descending and sigmoid).

RESULTS

Compared with controls, constipated patients revealed significantly higher number of mast cells, both as overall number and in single colonic segments. The distribution of mast cells resulted fairly homogeneous in the various segment of the large bowel, in both controls and patients, and no significant difference in the percentage of degranulated cells was found between groups.

CONCLUSIONS

Colonic mast cells display a homogeneous distribution within the viscus. This cell population is shown to increase in severely constipated patients, which might represent a mechanism trying to compensate for the impaired propulsive activity of these patients.

Excitation functions and yields for cyclotron production of radiorhenium via nat W(p,ߙxn)181-186gRe nuclear reactions and tests on the production of 186gRe using enriched 186W

Excitation functions and thin-target yields for the 181-186gRe radionuclides have been measured by the stacked-foil activation technique on tungsten foils of natural isotopic composition for different proton energies up to 22.0 MeV. A further check on the cross sections was done by irradiation of thick-targets and comparing the irradiated thick-target yields with those calculated by analytical integration from the thin-target yields. The production of 186gRe was also studied by the irradiation of thick-target of enriched 186W with a 13.6±0.2 MeV proton beam. The results for 186W(p,ߙn)186gRe were compared also to those calculated by the EMPIRE II code (version 2.19), due to 186gRe extensive applications in nuclear medicine for metabolic radiotherapy of tumours. It was found that the maximum percentage of 186gRe by irradiation of natural tungsten is about 20% only, which confirms the conclusion that high radionuclidic purity and specific activity of 186gRe necessitate the use of highly enriched 186W target.

G2/M checkpoint stringency is a key parameter in the sensitivity of AML cells to genotoxic stress

Acute myeloid leukemia (AML) cells exposed to genotoxic agents arrest their cell cycle at the G2/M checkpoint and are inherently chemoresistant. To understand the mechanism of this chemoresistance, we compared the ability of immature CD34+ versus mature CD34- AML cell lines (KG1a and U937, respectively) to recover from a DNA damage-induced cell cycle checkpoint in G2. Here, we report that KG1a cells have a more stringent G2/M checkpoint response than U937 cells. We show that in both cell types, the CDC25B phosphatase participates in the G2/M checkpoint recovery and that its expression is upregulated. Furthermore, we show that CHK1 inhibition by UCN-01 in immature KG1a cells allows checkpoint exit and induces sensitivity to genotoxic agents. Similarly, UCN-01 treatment potentializes genotoxic-induced inhibition of colony formation efficiency of primary leukemic cells from AML patients. Altogether, our results demonstrate that checkpoint stringency varies during the maturation process and indicate that targeting checkpoint mechanisms might represent an attractive therapeutic opportunity for chemoresistant immature AML cells.

A crosstalk between the Wnt and the adhesion-dependent signaling pathways governs the chemosensitivity of acute myeloid leukemia

Relapses following chemotherapy are a major hindrance to patients' survival in acute myeloid leukemia (AML). To investigate the role of the hematopoietic niche in the chemoresistance of leukemic cells, we examined two pathways: one mediated by adhesion molecules/integrins, and the other by soluble factors of the morphogen Wnt pathway. In our study, both the adhesion of leukemic blasts to fibronectin and the addition of Wnt antagonists induced, independently, resistance of AML cells to daunorubicin in a cell survival assay. Using pharmacological inhibitors and siRNA, we showed that both resistance pathways required the activity of the glycogen synthase kinase 3beta (GSK3beta). Moreover, the AML cell protection downstream of GSK3beta was mediated by NF-kappaB. A link between the adhesion and the Wnt pathway was found, as adhesion of U937 on human osteoblasts, a component of the hematopoietic niche, triggered the secretion of the Wnt antagonist sFRP-1 and supported resistance to daunorubicin. The osteoblast-conditioned medium could also confer chemoresistance to U937 cells cultured in suspension, and this cell protective effect was abrogated after depletion of sFRP-1. In the context of this potential double in vivo resistance, modulators of the common signal GSK3beta and of its target NF-kappaB could represent important novel therapeutic tools.

Expression of beta-catenin by acute myeloid leukemia cells predicts enhanced clonogenic capacities and poor prognosis

Activation of the Wnt/beta-catenin pathway has recently been shown to be crucial to the establishment of leukemic stem cells in chronic myeloid leukemia. We sought to determine whether beta-catenin was correlated to clonogenic capacity also in the acute myeloid leukemia (AML) setting. Eighty-two patients were retrospectively evaluated for beta-catenin expression by Western blot. beta-Catenin was expressed (although at various protein levels) in 61% of patients, and was undetectable in the remaining cases. In our cohort, beta-catenin expression was correlated with the clonogenic proliferation of AML-colony forming cells (AML-CFC or CFU-L) in methylcellulose in the presence of 5637-conditioned medium, and more strikingly with self-renewing of leukemic cells, as assessed in vitro by a re-plating assay. In survival analyses, beta-catenin appeared as a new independent prognostic factor predicting poor event-free survival and shortened overall survival (both with P<0.05). Furthermore, variations in beta-catenin protein levels were dependent on post-transcriptional mechanisms involving the Wnt/beta-catenin pathway only in leukemic cells. Indeed, beta-catenin negative leukemic cells were found to increase beta-catenin in response to Wnt3a agonist in contrast to normal counterparts. Altogether, our data pave the way to the evaluation of Wnt pathway inhibition as a new rationale for eradicating the clonogenic pool of AML cells.

Integrin function and signaling as pharmacological targets in cardiovascular diseases and in cancer

The microenvironment is now considered as an important source of potential therapeutic targets in diverse pathologies. In cardiovascular diseases and in cancer, common processes involving stromal remodeling, cell invasion, and angiogenesis can promote progression of the pathology. At each step of the pathogenesis, cell adhesion needs to be modulated to allow adaptation of cell survival/motility/proliferation functions to the microenvironment. Among adhesion receptors, integrins, responsible for cell/matrix or cell/cell interactions, play a key role in the cellular responses. Moreover, their engagement conditions the sensitivity to apoptosis induced by therapeutic drugs. Targeting of the extracellular side of integrins in order to modulate their adhesive functions is under development and has reached clinical indications. However, improvement of oral availability and of cell signaling control is required in the future. Targeting of the extracellular or the intracellular key proteins involved in integrin-dependent signaling pathway seems promising. Yet, although some common key enzyme inhibitors are under development, a better knowledge of the specificity of integrin activation and interaction with partners upon pathogenesis is of major importance in envisaging the antagonism of integrin-linked signals as a therapeutic tool alone or in association with other therapies.

The p42/p44 mitogen-activated protein kinase activation triggers p27Kip1 degradation independently of CDK2/cyclin E in NIH 3T3 cells

The p42/p44 mitogen-activated protein (MAP) kinase is stimulated by various mitogenic stimuli, and its sustained activation is necessary for cell cycle G(1) progression and G(1)/S transition. G(1) progression and G(1)/S transition also depend on sequential cyclin-dependent kinase (CDK) activation. Here, we demonstrate that MAP kinase inhibition leads to accumulation of the CDK inhibitor p27(Kip1) in NIH 3T3 cells. Blocking the proteasome-dependent degradation of p27(Kip1) impaired this accumulation, suggesting that MAP kinase does not act on p27(Kip1) protein synthesis. In the absence of extracellular signals (growth factors or cell adhesion), genetic activation of MAP kinase decreased the expression of p27(Kip1) as assessed by cotransfection experiments and by immunofluorescence detection. Importantly, MAP kinase activation also decreased the expression of a p27(Kip1) mutant, which cannot be phosphorylated by CDK2, suggesting that MAP kinase-dependent p27(Kip1) regulation is CDK2-independent. Accordingly, expression of dominant-negative CDK2 did not impair the down-regulation of p27(Kip1) induced by MAP kinase activation. These data demonstrate that the MAP kinase pathway regulates p27(Kip1) expression in fibroblasts essentially through a degradation mechanism, independently of p27(Kip1) phosphorylation by CDK2. This strengthens the role of this CDK inhibitor as a key effector of G(1) growth arrest, whose expression can be controlled by extracellular stimuli-dependent signaling pathways.

Increased glucose-dependent insulinotropic polypeptide (GIP) secretion in acromegaly

OBJECTIVE

Acromegaly is often associated with fasting and postprandial hyperinsulinemia, and the mechanisms involved are only partly understood. Hypersecretion of incretins such as glucose-dependent insulinotropic polypeptide (GIP) could play a role in determining hyperinsulinemia in acromegaly, but the available data are inconsistent. The aim of this study was to characterize the fasting and postprandial pattern of plasma GIP and insulin in a group of acromegalic patients.

DESIGN AND METHODS

Eleven non-diabetic patients with newly diagnosed acromegaly and 11 sex- and age-matched healthy subjects were studied. Blood samples were taken at regular intervals in fasting conditions and for 3 h after a standard solid-liquid meal for growth hormone (GH), GIP and insulin measurements.

RESULTS

Not only insulin, but also fasting and postprandial GIP levels were significantly higher in the patients with acromegaly than the healthy subjects (P<0.01). In the former group fasting GIP levels and the integrated GIP response to the meal correlated significantly with GH basal levels (r=0.83, P<0.01 and r=0.65, P<0.05, respectively). Moreover, multivariate linear regression analysis showed that the presence of acromegalic status was associated with higher fasting and postprandial GIP levels independently of sex, age, fasting and postprandial plasma glucose and insulin levels, and the occurrence of normal or impaired glucose tolerance.

CONCLUSION

This study provides evidence that in patients with acromegaly fasting and postprandial GIP levels are abnormally high. GIP hypersecretion in turn might play a role in the pathogenesis of hyperinsulinemia that characterizes acromegaly.

Retrovirus-mediated transfer of a suicide gene into lens epithelial cells in vitro and in an experimental model of posterior capsule opacification

PURPOSE

The most common complication of cataract surgery is the development of posterior capsule opacification (PCO). Hyperplasia of the lens epithelium is one of the main cellular events following phacoemulsification and was found to be an important feature contributing to opacification of the posterior capsule. We investigated the feasibility of killing the residual lens epithelial cells by retroviral-mediated transfer of the herpes simplex virus-thymidine kinase (HSV-tk) gene, a well-studied suicide gene, into rabbit lens epithelial cells followed by ganciclovir (GCV) treatment.

METHODS

The capacity of retroviral vectors to transfer genes into rabbit lens epithelial cells was determined either in vitro (culture of rabbit lens epithelial cells) or in vivo (experimental model of PCO in rabbits) using cDNA encoding the beta-galactosidase (LacZ) reporter gene. To evaluate the efficiency of suicide gene therapy (infection with retroviral vectors encoding the HSV-tk gene followed by GCV treatment) we determined the sensitivity of HSV-tk infected lens epithelial cells to different concentrations of GCV in vitro. Then, in an experimental model of PCO, rabbits were treated with HSV-tk retroviral vectors at the end of the surgery and they received repeated intracameral and intravitreal injections of GCV at the concentration determined by the in vitro experiments.

RESULTS

Infection efficiency using LacZ retroviral vectors was about 29% in vitro and 10% in vivo. After infection of the HSV-tk cDNA in vitro, the cell killing effect of GCV was evaluated. A significant enhancement (four- to five-fold) of the cell sensitivity to GCV was shown in FLY-DFGtk as compared with mock infected (P < 0.01) cells even without selection of the HSV-tk positive cells. The GCV concentration leading to 50% reduction in cell number (IC50) was 50 microg/ml. In vivo infection with a HSV-tk vector led to the tk gene transfer into lens epithelial cells. Despite this local HSV-tk gene expression, we could not prevent capsule opacification.

CONCLUSIONS

Lens epithelial cells were successfully infected both in vitro and in vivo by beta-galactosidase and HSV-tk genes via retroviral vectors. In vitro infected lens epithelial cells displayed a strong sensitivity to GCV treatment. In vivo, we could not prevent capsule opacification in the rabbit model, very likely due to the limited level of the HSV-tk gene expression. However, our results suggest that virus-mediated suicide gene therapy might be a feasible treatment strategy to prevent capsule opacification with a more powerful vector.

Adenovirus-mediated suicide gene transduction: feasibility in lens epithelium and in prevention of posterior capsule opacification in rabbits

The most common complication of cataract surgery is the development of posterior capsule opacification (PCO). Hyperplasia of the lens epithelium is one of the main cellular events following phacoemulsification, and has been found to be an important feature contributing to opacification of the posterior capsule. Adenoviral vector-mediated transfer is a suitable method for transducing the herpes simplex virus thymidine kinase gene (HSV-tk) into proliferating cells, allowing for the selective killing of these cells by ganciclovir (GCV) treatment. To determine the potential of gene transduction for lens epithelial cells, we studied the transduction of rabbit lens epithelial cells with adenoviral vectors containing either the Escherichia coli beta-galactosidase (lacZ) gene or the HSV-tk gene in vitro and in vivo in an experimental model of PCO. The efficiency of lacZ gene transfer in rabbit lens epithelial cells was at least 95% both in vitro and in vivo. In vivo transduction with HSV-tk adenoviral vector followed by GCV treatment significantly inhibited the development of PCO (p<0.001). These results suggest that adenoviral vector-mediated transfer of HSV-tk into the proliferating lens epithelial cells is feasible and may provide a novel therapeutic strategy for PCO.

Phosphorylation of the myristoylated protein kinase C substrate MARCKS by the cyclin E-cyclin-dependent kinase 2 complex in vitro

The myristoylated alanine-rich C-kinase substrate (MARCKS) purified from brain was recently characterized as a proline-directed kinase(s) substrate in vivo [Taniguchi, Manenti, Suzuki and Titani (1994) J. Biol. Chem. 269, 18299-18302]. Here we have investigated the phosphorylation of MARCKS by various cyclin-dependent kinases (Cdks) in vitro. We established that Cdk2, Cdk4 and, to a smaller extent, Cdk1 that have been immunoprecipitated from cellular extracts phosphorylate MARCKS. Comparison of MARCKS phosphorylation by protein kinase C (PKC) and by the purified cyclin E-Cdk2 complex suggested that two residues were phosphorylated by Cdk2 under these conditions. To identify these sites, Cdk2-phosphorylated MARCKS was digested with lysyl endoprotease and analysed by electrospray MS. Comparison with the digests obtained from the unphosphorylated protein demonstrated that two peptides, Gly12-Lys30 and Ala138-Lys152, were phosphorylated by cyclin E-Cdk2. The identity of these peptides was confirmed by automatic Edman degradation. On the basis of the consensus phosphorylation sequence described for Cdk2, and on MS/MS analysis of the Ala138-Lys152 peptide, we concluded that Ser27, one of the phosphorylation sites identified in vivo, and Thr150 were the Cdk2 targets in vitro. None of the other sites described in vivo were phosphorylated in these conditions. Interestingly, a preliminary phosphorylation of MARCKS by PKC improved the initial rate of phosphorylation by Cdk2 without modifying the number of sites concerned. In contrast, phosphorylation of MARCKS by Cdk2 did not significantly affect further phosphorylation by PKC.

Flavonoids and the inhibition of PKC and PI 3-kinase

Flavonoids provide a large number of interesting natural compounds that are consumed daily and exhibit more or less potent and selective effects on some signaling enzymes as well as on the growth and proliferation of certain malignant cells in vitro. Among the identified signal transducers, phosphoinositide 3-kinase (PI 3-kinase) and protein kinase C (PKC) are now considered key players in many cellular responses including cell multiplication, apoptosis, and transformation. Despite their lack of strict specificity, some flavonoids provide valuable bases for the design of analogues that could be used to specifically block particular isoforms of PI 3-kinase or PKC and their downstream-dependent cellular responses.

Regulation by transforming growth factor-beta 1 of G1 cyclin-dependent kinases in human retinal epithelial cells

Transforming growth factor beta (TGFbeta) is a potent inhibitor of epithelial cell proliferation, delaying or arresting cell cycle progression in mid-late G1. In long-term life span cells this growth inhibitory action has been attributed to regulatory events on both the levels and activities of G1 cyclin-dependent kinases (CDKs). CDK inhibitors have been shown to play important role in the TGFbeta-induced inhibition of G1 CDKs. In this work, we have investigated the effect of TGFbeta1 on both cell proliferation and G1 CDK activities in primary cultures of human retinal pigment epithelial (RPE) cells. We show that TGFbeta1 exerts a partial inhibitory effect on RPE cell proliferation by causing a significant increase of the RPE cell number in G1. TGFbeta1 induces an up-regulation of the CDK inhibitor p15(INK4B)with its subsequent association to CDK4, and a decline in CDK4 protein level. In parallel, we have observed a decline of p27(KIP1)associated to CDK4 and a significant increase of the inhibitor associated to CDK2. Finally, we show that TGFbeta1 reduces both CDK4 and CDK2 enzymatic activities. The fact that TGFbeta exerts only partial inhibitions on G1 CDKs and cell cycle progression in RPE cells suggests a propensity of these cells to escape from the anti-proliferative action of the cytokine, a phenomenon which could be reinforced during the development of proliferative vitreoretinopathy.

[Adverse effects of drugs in intensive care units: analysis of the administration of electrolyte solutions and antibiotics]

The aims of this study were: 1) to verify the incidence of adverse occurrences (AOs) with medication related to the time of electrolyte solutions infusion and the frequency of doses of antibiotics prescribed and administered to the patients; 2) to characterize the nature of those occurrences. The study was developed in two ICUs of a general hospital of São Paulo City. The population was composed by 51 patients that were in the ICUs in August of 1996. Sixty percent of the patients were older than 60 years, 58.8% were women, 49.1% remained in ICU from 1 to 4 days and 41.2% went to the Intermediate Care Units after ICU. Regarding the incidence of AOs related to the time of administration of the electrolyte solutions and the frequency of doses of antibiotics the non execution of the patient's medical prescriptions was verified in 76.3% and 38.8% respectively. The largest frequency of irregularities with the electrolyte solutions (60.2%) was the infusion faster than the prescribed time followed by the reduction of the number of doses of antibiotics administered. Taking these into consideration we have to invest in preventive measures to reduce those occurrences.

Differential expression of G1 cyclins and cyclin-dependent kinase inhibitors in normal and transformed melanocytes

PURPOSE

To investigate the levels of the different regulatory proteins involved in the G1 progression and G1/S transition in normal and transformed human choroidal melanocytes (CM).

METHODS

Three choroidal melanoma cell lines and three CM cultures were used. The purity of the CM cultures was assessed by different approaches, including morphologic study, specific immunostaining, cell proliferation behavior, and transforming growth factor-beta1 responsiveness. The cell cycle protein levels were evaluated by specific immunoblotting of total extracts obtained from the different cell lines.

RESULTS

Alterations were observed in the expression of cylins D1 and E in the transformed cells, whereas the amounts of the cyclin-dependent kinases (CDKs) CDK2 and CDK4 were almost identical in both cell types. Although the expression of cyclin H was slightly increased in transformed cells, neither the CDK7 level nor the CDK7 and cyclin H localizations were altered when compared with those in normal CM. The results suggest the absence of the CDK inhibitor (CKI) p21 in two of the three melanoma cell lines and, as a main feature, a striking underexpression of p27 in the three transformed cell lines. Finally, although the p16 level was almost the same in normal and transformed cells, a loss of p16-CDK4 interaction was observed in two of the three melanoma cell lines.

CONCLUSIONS

Deregulated expression of G1 cyclins and CKIs and alteration in the interaction of CKIs with CDKs may be implicated in the neoplastic transformation of human ocular melanocytes to malignant melanoma cells.

Overexpression of the myristoylated alanine-rich C kinase substrate in human choroidal melanoma cells affects cell proliferation

Reduced expression of the myristoylated alanine-rich C kinase substrate (MARCKS) has been described in various cell lines after oncogenic or chemical transformation, leading to the question of whether this protein may be involved in cell proliferation. Here we compare the expression of MARCKS in human tumor-derived choroidal melanoma cells (OCM-1) and in primary cultures of normal choroidal melanocytes. We found an important down-regulation of the protein in the melanoma cell line. Stable transfection of these cells with the cDNA coding for MARCKS led to the selection of several clones expressing variable levels of the protein. Proliferation experiments performed with four of these clones revealed that cell growth was reduced by 35-40% when compared with control cells. Upon serum starvation, cell proliferation was almost abolished when the expression level of MARCKS was high, whereas it was only partially reduced in the controls. MARCKS overexpression induced a higher percentage of cells in the G0-G1 phase of the cell cycle upon serum starvation, as well as the inhibition of colony formation in soft agar. Finally, the expression of the CDK inhibitor p27 was increased in the cells presenting a high level of MARCKS protein. Altogether, these data suggest that the expression of this protein kinase C substrate affects the proliferation and partially reverts the transformed phenotype of the OCM-1 cells.

G1 phase arrest by the phosphatidylinositol 3-kinase inhibitor LY 294002 is correlated to up-regulation of p27Kip1 and inhibition of G1 CDKs in choroidal melanoma cells

We have investigated the effect of the flavonoid derivative LY 294002, a potent and selective phosphatidylinositol 3-kinase inhibitor, on cell cycle progression in human choroidal melanoma cells. We demonstrate that LY 294002 induces a specific G1 block in asynchronously growing cells leading to an almost complete inhibition of cell proliferation after three days of treatment. When melanoma cells are released from a nocodazole-induced G2/M block, LY 294002 is shown to delay and greatly restrain the G1/S transition. The inhibitor is able to exert its action as long as it is added during the G1 progression and before the cells enter in S phase. We report that the LY 294002-induced G1 arrest is closely correlated to inhibition of CDK4 and CDK2 activities leading to the impairment of pRb phosphorylation which normally occurs during G1 progression. While the inhibition of CDK4 may be attributed at least in part to the decline in CDK4 protein level, CDK2 activity reduction is rather due to the up-regulation of the CDK inhibitor p27Kip1 and to its increased association to CDK2.

The major myristoylated PKC substrate (MARCKS) is involved in cell spreading, tyrosine phosphorylation of paxillin, and focal contact formation

The expression of the myristoylated PKC substrate MARCKS is reduced in tumor-derived choroidal melanoma cells (OCM-1). We transfected the OCM-1 cells with MARCKS cDNA and we selected clones with stable overexpression of the protein. Tyrosine phosphorylation of paxillin, a biochemical marker of focal contact formation, was conserved upon serum starvation when MARCKS was overexpressed, while it was almost abolished in the control cells. Immunofluorescent labelling of paxillin and vinculin, another component of focal contact, revealed that these structures were conserved upon serum starvation when MARCKS was overexpressed but not in the control cells. Furthermore, the cell morphology was affected by the ectopic expression of MARCKS, leading to increased spreading and formation of membrane processes. These data suggest the involvement of MARCKS in cell spreading and focal contact formation.

Relationship between flavonoid structure and inhibition of phosphatidylinositol 3-kinase: a comparison with tyrosine kinase and protein kinase C inhibition

Depending on their structure, flavonoids display more or less potent inhibitory effects on the growth and proliferation of certain malignant cells in vitro, and these effects are thought to be due to inhibition of various enzymes. We investigated the inhibitory action of fourteen flavonoids of different chemical classes on phosphatidylinositol 3-kinase alpha (PI 3-kinase alpha) activity, an enzyme recently shown to play an important role in signal transduction and cell transformation. Of the fourteen flavonoids tested, myricetin was the most potent PI 3-kinase inhibitor (IC50 = 1.8 microM), while luteolin and apigenin were also effective inhibitors, with IC50 values of 8 and 12 microM, respectively. Fisetin and quercetin, as previously reported, were also found to significantly inhibit PI 3-kinase activity. The same flavonoids were also analyzed for inhibition of epidermal growth factor receptor (EGF-R), intrinsic tyrosine kinase and bovine brain protein kinase C (PKC). At elevated doses, some of these flavonoids were found to also cause significant inhibition of PKC and tyrosine kinase activity of EGF-R. A structure-activity study indicated that the position, number and substitution of the hydroxyl group of the B ring, and saturation of the C2-C3 bond are important factors affecting flavonoid inhibition of PI 3-kinase. They may also play a significant role in specificity of inhibition and could help to provide a basis for the further design of specific inhibitors of this lipid kinase. Finally, possible relationships between the antitumoral properties of these flavonoids and their biological activities are discussed.