Proteomic analysis of cholangiocarcinoma cell line

Cholangiocarcinoma (CCA), a malignant tumor derived from bile duct epithelium, occurs with a higher incidence in tropical countries, such as Thailand. Distinguishing CCA from hepatocellular carcinoma (HCC) of the liver often requires the use of histochemistry, so molecular markers for diagnosis and prognosis are still required. In this study, the two-dimensional (2-D) protein map of a Thai human bile duct epithelial carcinoma cell line (HuCCA-1) has been compared to human hepatocellular carcinoma cell lines (HepG2 and HCC-S102) and a human breast epithelial cancer cell line (MCF-7). Our results show that HuCCA-1 expressed a unique pattern of proteins. Forty-three major proteins were identified by matching to the map of MCF-7, and by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and electrospray ionization-tandem MS (ESI-MS/MS). Cytokeratins CK8 and CK18 were overexpressed in both HuCCA-1 and HCC, while CK7 and CK19 were only expressed in HuCCA-1. Four specific proteins with MW/pI 57.2/5.21 (U1, vimentin), 42.2/6.20 (U2), 43.2/6.20 (U3, EF-TU), and 42.2/6.40 (U4, unidentified) were absent from HepG2. U2 showed high expression in HuCCA-1, while U1 and U4 showed high expression in HCC-S102. U2 could be separated in 2 proteins, U2/1 (alpha-enolase) and U2/2 (not identified) by using IPG pH 4-7. Galectin-3 showed high expression level in HuCCA-1 by 1-DE immunodetection, and gave only one spot with MW 32.9 kDa and pI 8.29 on 2-DE immunoblotting, Thus, certain proteins, namely CK7, CK19, U2/2 and galectin-3, may be good markers useful for differential diagnosis of cholangiocarcinoma compared to hepatocellular carcinoma.     

Metabolic alteration of HepG2 in scaffold-based 3-D culture: proteomic approach

3-D cell culture models are important in cancer biology since they provide improved understanding of tumor microenvironment. We have established a 3-D culture model using HepG2 in natural collagen-based scaffold to mimic the development of small avascular tumor in vivo. Morphological characterization showed that HepG2 colonies grew within the interior of the scaffold and showed enhanced extracellular matrix deposition. High levels of cell proliferation in the outermost regions of the scaffold created a hypoxic microenvironment in the 3-D culture system, as indicated by hypoxia-inducible factor-1α stabilization, detectable by Western blotting and immunohistochemistry. Proteomic studies showed decreased expression of several mitochondrial proteins and increased expression of proteins in anaerobic glycolysis under 3-D culture compared to monolayer culture. Creatine kinase was also upregulated in 3-D culture, indicating its possible role as an important energy buffer system under hypoxic microenvironment. Increased levels of proteins in nucleotide metabolism may relate to cellular energy. Thus, our results suggest that HepG2 cells under 3-D culture adapt their energy metabolism in response to hypoxic conditions. Metabolic alterations in the 3-D culture model may relate to physiological changes relevant to development of small avascular tumor in vivo and their study may improve future therapeutic strategies.     

Detection of cathepsin B up-regulation in neoplastic thyroid tissues by proteomic analysis

Nodular or multinodular goiter is the most common non-neoplastic thyroid disease and may be difficult to distinguish from true neoplastic thyroid diseases using microscopic criteria. We have used two-dimensional gel electrophoresis to study the protein patterns of thyroid tissues including normal thyroid, multinodular goiter, diffuse hyperplasia, follicular adenoma, follicular carcinoma and papillary carcinoma. Specific proteins, in the region of molecular mass 15-30 kDa and isoelectric point 4.5-6.5, were identified by electrospray tandem mass spectrometry and protein sequencing. The most distinctive protein found is cathepsin B, which could be detected as four spots, with differential expression in different thyroid diseases. In particular, two of these cathepsin B spots CB2 and CB3 are strongly up-regulated in neoplastic diseases, compared to non-neoplastic diseases. In addition, overexpression of ATP synthase D chain and prohibitin were observed in papillary carcinoma, which should allow it to be differentiated from follicular carcinoma. Changes in expression of other proteins were also observed in disease states compared to normal tissues, namely translationally controlled tumor protein, thioredoxin peroxidase 1, glutathione-S-transferase P, DJ-1 protein, superoxide dismutase (Cu, Zn), and heat shock protein 27, but these changes are less characteristic, so they do not allow the differentiation between neoplastic and non-neoplastic tissues. Thus, the proteomic approach is a useful diagnostic tool for studying diseases involving the thyroid nodule.     

Role of curcuminoids in ameliorating oxidative modification in β-thalassemia/Hb E plasma proteome

Thalassemic patients often exhibit high levels of oxidative stress and iron overload, which can lead to hazardous complications. Curcuminoids, extracted from the spice turmeric, are known to have antioxidant and iron-chelating properties and have been proposed as a potential upstream therapy of thalassemia. Here we have applied proteomic techniques to study the protein profile and oxidative damage in the plasma of β-thalassemia/Hb E patients before and after treatment with curcuminoids. In this study, 10 β-thalassemia/Hb E patients were treated with 500 mg curcuminoids daily for 12 months. The plasma protein profile and protein carbonyl content were determined at baseline, 6 and 12 months using two-dimensional fluorescence difference gel electrophoresis and carbonyl immunoblotting, respectively. Other hematological, clinical, and biochemical parameters were also analyzed. Twenty-six spots, identified as coagulation factors and proteins involved in iron homeostasis, showed significantly decreased intensity in thalassemic plasma, compared to those of normal subjects. Treatment with curcuminoids up-regulated the plasma levels of these proteins and reduced their oxidative damage. Serum non-transferrin bound iron, platelet factor-3 like activity, oxidative stress parameters and antioxidant enzymes were also improved after curcuminoids treatment. This study is the first proteomic study of plasma in the thalassemic state and also shows the ameliorating role of curcuminoids towards oxidative stress and iron overload in the plasma proteome.     

Proteomic profiling of cholangiocarcinoma cell line treated with pomiferin from Derris malaccensis

Pomiferin, a prenylated isoflavonoid from Derris malaccensis with strong anti-fungal and anti-oxidant activities, showed cytotoxic activity towards human cholangiocarcinoma cells (HuCCA-1), with IC(50) of 0.9 microg/mL. Pomiferin caused apoptosis, detectable by DNA fragmentation. Two-dimensional PAGE showed increased expression of 12 proteins, namely glucose-regulated protein 75 (grp 75), calcyclin (S100A6), degraded cytokeratin 19, ATP synthase D, ribosomal protein P0, degraded cytokeratin 18 (two spots pI/MW 6.03/29.9 and pI/MW 4.66/21.5), cofilin, annexin A1, triose phosphate isomerase, peroxiredoxin-1, calgizzarin, and profilin. In contrast, cytokeratins (CK) 7, 18 and 19 were down-regulated, and were shown by 1-DE immunodetection to be degraded.     

Replication of Dengue Virus Type 2 in Aedes albopictus Cell Culture

The replication of type 2 dengue (D-2) virus in Aedes albopictus (Aal) mosquito cell cultures differed from that in vertebrate (LLC-MK2) rhesus monkey kidney cells. Virus readily replicated in Aal cells at either 30 or 37 C, but had no apparent effect on the host cell. Persistent infection was established with continual virus production for at least 6 months, although the virulence of progeny virus for both suckling mice and LLC-MK2 cells became attenuated. Density gradient analysis of infected Aal cell supernatant products indicated that only complete virus was released, in contrast to infected LLC-MK2 cells which also released incomplete virus. The surface antigens of the virus produced in Aal cells appeared to be considerably modified in that antiserum to vertebrate cell-produced D-2 virus did not block hemagglutination, whereas anti-Aal cell antiserum did. Virus infectivity could be neutralized by the antiserum to D-2 virus grown in vertebrate cells, however. Virus produced in LLC-MK2 cells did not demonstrate a similar host-cell modification. These results may reflect a difference in the mechanism by which D-2 virus matures in Aal cells.     

Synthesis of homo- and hetero-oligosaccharides by Thai rosewood β-glucosidase

-Glucosidase from Thai Rosewood (Dalbergia cochinchinensis Pierre) catalyzes the synthesis disaccharides and trisaccharides at 40–70% (w/w) glucose. Gentiobiose (1–6-diglucose) was the major disaccharide. The reaction was optimal at pH 5.0 and 60–65°C. When the reaction was performed in mixtures of glucose and fucose, a novel product was found, which was purified and characterized by NMR spectroscopy to be d-fucosyl (1–6)-d-glucose.