Hepatocellular carcinoma: updates in pathogenesis, detection and treatment

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and the second most common cause of cancer mortality worldwide [1]. The prognosis of HCC patients is very poor. The rates of HCC incidence and mortality are almost equivalent [2] and have increased across most countries over the past three decades [3]. HCC development is closely associated with the presence of chronic liver disease and cirrhosis, albeit the risk factors underlying this condition vary geographically. Hepatitis B virus (HBV) infection and aflatoxin B1 exposure are predominant risk factors in Asia and Africa, while hepatitis C virus (HCV) infection and alcohol consumption are the main risk factors in Europe, the USA and Japan [3,4,5]. Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent liver disease worldwide, and approximately 60% of biopsied NAFLD patients have non-alcoholic steatohepatitis (NASH) [3]. Importantly, patients with NASH are at high risk of developing HCC even without presenting established cirrhosis [6]. With widespread HBV vaccination and the advent of direct-acting antiviral drugs for HCV infection, NAFLD and associated conditions such as diabetes and obesity are emerging as major global risk factors for HCC. In view of the dismal prognosis of HCC patients, implementing preventive strategies would be an ideal approach to quell the incidence of the disease. Obvious interventions include advocating HBV vaccination in endemic regions, achieving HCV eradication with direct-acting antivirals, promoting healthy nutrition and weight reduction, improving diabetes control, and avoiding excessive alcohol consumption. Still, the implementation of these measures is not always feasible

NO sensitizes rat hepatocytes to proliferation by modifying S-adenosylmethionine levels

BACKGROUND & AIMS: Liver regeneration is a fundamental response of this organ to injury. Hepatocyte proliferation is triggered by growth factors, such as hepatocyte growth factor. However, hepatocytes need to be primed to react to mitogenic signals. It is known that nitrous oxide (NO), generated after partial hepatectomy, plays an important role in hepatocyte growth. Nevertheless, the molecular mechanisms behind this priming event are not completely known. S-adenosylmethionine (AdoMet) synthesis by methionine adenosyltransferase is the first step in methionine metabolism, and NO regulates hepatocyte S-adenosylmethionine levels through specific inhibition of this enzyme. We have studied the modulation of hepatocyte growth factor-induced proliferation by NO through the regulation of S-adenosylmethionine levels. METHODS: Studies were conducted in cultured rat hepatocytes isolated by collagenase perfusion, which triggers NO synthesis. RESULTS: The mitogenic response to hepatocyte growth factor was blunted when inducible NO synthase was inhibited; this process was overcome by the addition of an NO donor. This effect was dependent on methionine concentration in culture medium and intracellular S-adenosylmethionine levels. Accordingly, we found that S-adenosylmethionine inhibits hepatocyte growth factor-induced cyclin D1 and D2 expression, activator protein 1 induction, and hepatocyte proliferation. CONCLUSIONS: Together our findings indicate that NO may switch hepatocytes into a hepatocyte growth factor-responsive state through the down-regulation of S-adenosylmethionine levels

Correlation Between The Ibopamine Provocative Test And The Diurnal Tension Curve In Glaucoma Patients

Purpose: To correlate the ibopamine provocative test with the diurnal tension curve (highest intraocular pressure-IOP and range) in glaucoma. Methods: This is a prospective case series including glaucoma patients from the Federal University of Goiás, Glaucoma Service. Two 2% ibopamine eyedrops were instilled into one or both eyes of each patient, 5 minutes apart. Intraocular pressure was checked before and 30 and 45 minutes after the second ibopamine instillation. Thereafter, the diurnal tension curve of each patient was assessed with five independent measurements (atevery 2:30 hours), from 8:00 o'clock AM to 6:00 o'clock PM. Pearson's correlation coefficient was used to test the linear relation between the intraocular pressure after the ibopamine instillation with the highest intraocular pressure value and the intraocular pressure range in the diurnal curve. Results: Thirty-one eyes from 22 patients were included. There was a significant correlation between the intraocular pressure 30 and 45 minutes after ibopamine instillation and the highest intraocular pressure assessed in the diurnal curve (r=0.356, p=0.04 and r=0.429, p=0.01, respectively). However, no correlation between IOP after the use of ibopamine and the diurnal intraocular pressure range at 30 (r=0.046, p=0.8) and 45 minutes (r=0.109, p=0.5) was observed. Conclusion: The ibopamine provocative test shows a significant corellation with the highest intraocular pressure in the diurnal tension curve in glaucoma patients. However, no correlation was observed with the intraocular pressure range.694477480Armaly, M.F., Water-drinking test. I. Characteristics of the ocular pressure response and the effect of age (1970) Arch Ophthalmol, 83 (2), pp. 169-175Winder, A.F., Siddiqui, A.A., Donovan, H.C., Ocular hypertension and systemic responses to the water-drinking test (1978) Br J Ophthalmol, 62 (6), pp. 414-419Spaeth, G.L., Effects of topical dexamethasone on intraocular pressure and the water drinking test (1966) Arch Ophthalmol, 76 (6), pp. 772-783Harris, L.S., Galin, M.A., Cycloplegic provocative testing (1969) Arch Ophthalmol, 81 (3), pp. 356-358Marchini, G., Babighian, S., Tosi, R., Perfetti, S., Bonomi, L., Comparative study of the effects of 2% ibopamine, 10% phenylephrine, and 1% tropicamide on the anterior segment (2003) Invest Ophthalmol Vis Sci, 44 (1), pp. 281-289McLaren, J.W., Herman, D.C., Brubaker, R.F., Nau, C.B., Wayman, L.L., Ciarniello, M.G., Effect of ibopamine on aqueous humor production in normotensive humans (2003) Invest Ophthalmol Vis Sci, 44 (11), pp. 4853-4858Virno, M., Taverniti, L., De Gregorio, F., Sedran, L., Longo, F., Increase in aqueous humor production following D1 receptors activation by means of ibopamine (1996) Int Ophthalmol, 20 (1-3), pp. 141-146Magacho, L., Lima, F.E., Costa, M.L., Fayad, F.A., Guimaraes, N.L., Avila, M.P., Ibopamine provocative test and glaucoma: Consideration of factors that may influence the examination (2004) Curr Eye Res, 28 (3), pp. 189-193De Gregorio, F., Pecori Giraldi, J., Pannarale, L., Saccucci, S., Virno, M., Ibopamine in glaucoma diagnostics: A new pharmacological provocative test (1996) Int Ophthalmol, 20 (1-3), pp. 151-155Brogliatti, B., Boles Carenini, A., Bogetto, C., Vadala, G., Grignolo, F.M., Boles Carenini, B., Ibopamine test in healthy and glaucomautous eyes: Tonometric and pupillographic study (2000) Acta Ophthalmol Scand Suppl, 78 (232), pp. 13-14Lima, F.E., Guimarães, N.L.D., Santos, L.M., Costa, L.P., Ávila, M.P., Ibopamina tópica na propedêutica do glaucoma (2002) Rev Bras Oftalmol, 61 (2), pp. 109-113Kitazawa, Y., Horie, T., Diurnal variation of intraocular pressure in primary open-angle glaucoma (1975) Am J Ophthalmol, 79 (4), pp. 557-566Sacca, S.C., Rolando, M., Marletta, A., Macri, A., Cerqueti, P., Ciurlo, G., Fluctuations of intraocular pressure during the day in open-angle glaucoma, normal-tension glaucoma and normal subjects (1998) Ophthalmologica, 212 (2), pp. 115-119David, R., Zangwill, L., Briscoe, D., Dagan, M., Yagev, R., Yassur, Y., Diurnal intraocular pressure variations: An analysis of 690 diurnal curves (1992) Br J Ophthalmol, 76 (5), pp. 280-283Zeimer, R.C., Wilensky, J.T., Gieser, D.K., Viana, M.A., Association between intraocular pressure peaks and progression of visual field loss (1991) Ophthalmology, 98 (1), pp. 64-69. , Comment in: Ophthalmology. 1991;98(9):1323Asrani, S., Zeimer, R., Wilensky, J., Gieser, D., Vitale, S., Lindenmuth, K., Large diurnal fluctuations in intraocular pressure are an independent risk factor in patients with glaucoma (2000) J Glaucoma, 9 (2), pp. 134-142. , Comment in: J Glaucoma. 2000;9(6):487-8Anderson, D.R., Patella, V.M., (1999) Automated Static Perimetry, , 2nd ed. St. Louis, Missouri: Year Book MosbyThe relationship between control of intraocular pressure and visual field deterioration (2000) Am J Ophthalmol, 130 (4), pp. 429-440. , The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 7. Comment in: Am J Ophthalmol. 2000;130(4):490-1Armaly, M.F., The visual field defect and ocular pressure level in open angle glaucoma (1969) Invest Ophthalmol, 8 (1), pp. 105-124The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma (1998) Am J Ophthalmol, 126 (4), pp. 498-505. , Collaborative Normal-Tension Glaucoma Study Group. Comment in: Am J Ophthalmol. 1998;126 (4):578-81Am J Ophthalmol. 1999;128(6):776-7Am J Ophthalmol. 1999;127 (5):623-5Am J Ophthalmol. 1999;127(5):625-6Ziai, N., Dolan, J.W., Kacere, R.D., Brubaker, R.F., The effects on aqueous dynamics of PhXA41, a new prostaglandin F2 alpha analogue, after topical application in normal and ocular hypertensive human eyes (1993) Arch Ophthalmol, 111 (10), pp. 1351-135

Triple configuration coexistence in 44 S

The neutron-rich N=28 nucleus S44 was studied using the two-proton knockout reaction from Ar46 at intermediate beam energy. We report the observation of four new excited states, one of which is a strongly prolate deformed 4 + state, as indicated by a shell-model calculation. Its deformation originates in a neutron configuration which is fundamentally different from the "intruder" configuration responsible for the ground-state deformation. Consequently, we do not have three coexisting shapes in S44, but three coexisting configurations, corresponding to zero-, one-, and two-neutron particle-hole excitations. � 2011 American Physical Society

L-methionine availability regulates expression of the methionine adenosyltransferase 2A gene in human hepatocarcinoma cells: role of S-adenosylmethionine

In mammals, methionine adenosyltransferase (MAT), the enzyme responsible for S-adenosylmethionine (AdoMet) synthesis, is encoded by two genes, MAT1A and MAT2A. In liver, MAT1A expression is associated with high AdoMet levels and a differentiated phenotype, whereas MAT2A expression is associated with lower AdoMet levels and a dedifferentiated phenotype. In the current study, we examined regulation of MAT2A gene expression by l-methionine availability using HepG2 cells. In l-methionine-deficient cells, MAT2A gene expression is rapidly induced, and methionine adenosyltransferase activity is increased. Restoration of l-methionine rapidly down-regulates MAT2A mRNA levels; for this effect, l-methionine needs to be converted into AdoMet. This novel action of AdoMet is not mediated through a methyl transfer reaction. MAT2A gene expression was also regulated by 5'-methylthioadenosine, but this was dependent on 5'-methylthioadenosine conversion to methionine through the salvage pathway. The transcription rate of the MAT2A gene remained unchanged during l-methionine starvation; however, its mRNA half-life was significantly increased (from 100 min to more than 3 h). The effect of l-methionine withdrawal on MAT2A mRNA stabilization requires both gene transcription and protein synthesis. We conclude that MAT2A gene expression is modulated as an adaptive response of the cell to l-methionine availability through its conversion to AdoMet

Structure of Full-Length SMC and Rearrangements Required for Chromosome Organization.

Multi-subunit SMC complexes control chromosome superstructure and promote chromosome disjunction, conceivably by actively translocating along DNA double helices. SMC subunits comprise an ABC ATPase "head" and a "hinge" dimerization domain connected by a 49 nm coiled-coil "arm." The heads undergo ATP-dependent engagement and disengagement to drive SMC action on the chromosome. Here, we elucidate the architecture of prokaryotic Smc dimers by high-throughput cysteine cross-linking and crystallography. Co-alignment of the Smc arms tightly closes the interarm space and misaligns the Smc head domains at the end of the rod by close apposition of their ABC signature motifs. Sandwiching of ATP molecules between Smc heads requires them to substantially tilt and translate relative to each other, thereby opening up the Smc arms. We show that this mechanochemical gating reaction regulates chromosome targeting and propose a mechanism for DNA translocation based on the merging of DNA loops upon closure of Smc arms

Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma

BACKGROUND & AIMS: Of the 2 genes (MAT1A, MAT2A) encoding methionine adenosyltransferase, the enzyme that synthesizes S-adenosylmethionine, MAT1A, is expressed in liver, whereas MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. Here, we identified the beta subunit as a regulator of proliferation in human hepatoma cell lines. The beta subunit has been cloned and shown to lower the K(m) of methionine adenosyltransferase II alpha2 (the MAT2A product) for methionine and to render the enzyme more susceptible to S-adenosylmethionine inhibition. METHODS: Methionine adenosyltransferase II alpha2 and beta subunit expression was analyzed in human and rat liver and hepatoma cell lines and their interaction studied in HuH7 cells. beta Subunit expression was up- and down-regulated in human hepatoma cell lines and the effect on DNA synthesis determined. RESULTS: We found that beta subunit is expressed in rat extrahepatic tissues but not in normal liver. In human liver, beta subunit expression associates with cirrhosis and hepatoma. beta Subunit is expressed in most (HepG2, PLC, and Hep3B) but not all (HuH7) hepatoma cell lines. Transfection of beta subunit reduced S-adenosylmethionine content and stimulated DNA synthesis in HuH7 cells, whereas down-regulation of beta subunit expression diminished DNA synthesis in HepG2. The interaction between methionine adenosyltransferase II alpha2 and beta subunit was demonstrated in HuH7 cells. CONCLUSIONS: Our findings indicate that beta subunit associates with cirrhosis and cancer providing a proliferative advantage in hepatoma cells through its interaction with methionine adenosyltransferase II alpha2 and down-regulation of S-adenosylmethionine levels

S-adenosylmethionine and methylthioadenosine are antiapoptotic in cultured rat hepatocytes but proapoptotic in human hepatoma cells

S-adenosylmethionine (AdoMet) is an essential compound in cellular transmethylation reactions and a precursor of polyamine and glutathione synthesis in the liver. In liver injury, the synthesis of AdoMet is impaired and its availability limited. AdoMet administration attenuates experimental liver damage, improves survival of alcoholic patients with cirrhosis, and prevents experimental hepatocarcinogenesis. Apoptosis contributes to different liver injuries, many of which are protected by AdoMet. The mechanism of AdoMet's hepatoprotective and chemopreventive effects are largely unknown. The effect of AdoMet on okadaic acid (OA)-induced apoptosis was evaluated using primary cultures of rat hepatocytes and human hepatoma cell lines. AdoMet protected rat hepatocytes from OA-induced apoptosis dose dependently. It attenuated mitochondrial cytochrome c release, caspase 3 activation, and poly(ADP-ribose) polymerase cleavage. These effects were independent from AdoMet-dependent glutathione synthesis, and mimicked by 5'-methylthioadenosine (MTA), which is derived from AdoMet. Interestingly, AdoMet and MTA did not protect HuH7 cells from OA-induced apoptosis; conversely both compounds behaved as proapoptotic agents. AdoMet's proapoptotic effect was dose dependent and observed also in HepG2 cells. In conclusion, AdoMet exerts opposing effects on apoptosis in normal versus transformed hepatocytes that could be mediated through its conversion to MTA. These effects may participate in the hepatoprotective and chemopreventive properties of this safe and well-tolerated drug

Importance of a deficiency in S-adenosyl-L-methionine synthesis in the pathogenesis of liver injury

One of the features of liver cirrhosis is an abnormal metabolism of methionine--a characteristic that was described more than a half a century ago. Thus, after an oral load of methionine, the rate of clearance of this amino acid from the blood is markedly impaired in cirrhotic patients compared with that in control subjects. Almost 15 y ago we observed that the failure to metabolize methionine in cirrhosis was due to an abnormally low activity of the enzyme methionine adenosyltransferase (EC 2.5.1.6). This enzyme converts methionine, in the presence of ATP, to S-adenosyl-L-methionine (SAMe), the main biological methyl donor. Since then, it has been suspected that a deficiency in hepatic SAMe may contribute to the pathogenesis of the liver in cirrhosis. The studies reviewed here are consistent with this hypothesis

GARBAN: genomic analysis and rapid biological annotation of cDNA microarray and proteomic data

Genomic Analysis and Rapid Biological ANnotation (GARBAN) is a new tool that provides an integrated framework to analyze simultaneously and compare multiple data sets derived from microarray or proteomic experiments. It carries out automated classifications of genes or proteins according to the criteria of the Gene Ontology Consortium at a level of depth defined by the user. Additionally, it performs clustering analysis of all sets based on functional categories or on differential expression levels. GARBAN also provides graphical representations of the biological pathways in which all the genes/proteins participate. AVAILABILITY: http://garban.tecnun.es