guanosine-5--o-(3-thiotriphosphate) and Liver-Neoplasms

To make clear whether CD147 (EMMPRIN) expression in pathological tumor samples with a fine-needle aspiration biopsy is useful for pathological diagnosis of early hepatocellular carcinoma (HCC).. Twenty-two patients (15 men and 7 women; median age 68 years, range 56-81 years) underwent a liver tissue biopsy in order to make a diagnosis of HCC. Paraffin-embedded liver biopsy tissue samples from 22 patients were stained with anti-CD147 antibody, murine monoclonal antibody 12C3 (MAb12C3) for immunohistochemical analysis. An immunohistochemical analysis of CD147 was performed and the degree of staining compared between tumor and non-tumor tissue. In addition, the degree of staining within tumor tissue was compared according to a number of clinicopathological variables.. The degree of staining of CD147 was significantly higher in tumor tissues than non-tumor tissues, even in tumors less than 15 mm in diameter. The expression of this protein was significantly elevated in HCC tissue specimens from patients with a low value of serum AST and gamma-GTP.. CD147 serves potentially as a pathological target for cancer detection of early HCC.

Topics: Aged; Aged, 80 and over; Aspartate Aminotransferases; Basigin; Biomarkers, Tumor; Biopsy, Needle; Carcinoma, Hepatocellular; Female; Gene Expression Regulation, Neoplastic; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Liver; Liver Neoplasms; Male; Middle Aged

Alterations in the expression and activity of guanine nucleotide regulatory proteins (G proteins) have been linked to the growth of several human tumors. We hypothesized that the expression and activity of G proteins are altered in human hepatocellular carcinoma (HCC). The expression of Gi and Gs proteins was determined in six human tumors and six normal controls (adjacent nonneoplastic liver) by Western blotting using specific antisera raised against the alpha subunit of G proteins Gi1, Gi1-2, Gi3, and Gs. Differences in G-protein expression were quantified by densitometry and expressed as percentage change from normal controls. The expression of Gi alpha1 was significantly increased in 80% of tumors (Gi alpha1, 284% +/- 77%; P < .05 percent of normal tissue), whereas Gi alpha1-2 and Gi alpha3 expression was increased in 67% of tumors (Gi alpha1-2, 218% +/- 21%; Gi alpha3, 154% +/- 6%; P < .05 percent of normal tissue). The functional activity of Gi alpha proteins as determined by pertussis toxin-catalyzed adenosine diphosphate (ADP)-ribosylation was also significantly increased in these tumors. In contrast, Gs alpha-protein expression was significantly reduced in all tumors examined (74% +/- 8% of normal tissue, P < .05). The functional activity of Gs alpha, as determined by adenylyl cyclase (AC) activity, was significantly decreased in tumor as compared to normal liver under both basal and agonist stimulated (guanosine triphosphate gamma S and forskolin) conditions. In summary, these data show for the first time a significant alteration in G-protein expression and functional activity in human HCC tissue. These alterations indicate a down-regulation of the AC-linked enzyme effector system in HCC that may be of critical importance to the formation and progression of human hepatocellular carcinoma.

Topics: Adenosine Diphosphate Ribose; Adenylate Cyclase Toxin; Adenylyl Cyclases; Aged; Blotting, Western; Carcinoma, Hepatocellular; Colforsin; Densitometry; Female; GTP-Binding Protein alpha Subunits, Gi-Go; GTP-Binding Protein alpha Subunits, Gs; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Liver; Liver Neoplasms; Male; Middle Aged; Pertussis Toxin; Reference Values; Virulence Factors, Bordetella

We developed a sensitive fluorometric assay to study in vitro fusion between early endosomes isolated from the human hepatoma, Hep G2. Biochemical characterization of this assay showed that fusion between endosomal vesicles was dependent on physiologic temperature, cytosol, and ATP. Fusion was inhibited by pretreatment of vesicles and cytosol with either 1 mM N-ethylmaleimide or 20 microM GTP gamma S. Neither 3 mM ethylene glycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid nor 1 mM CaCl2 significantly affected fusion. In addition, ATP gamma S neither inhibited fusion at 50 microM nor supported fusion at 5 mM. To further our understanding of the factors regulating fusion, inhibitors of endoprotease activity and phosphotyrosine phosphatase activity were assayed for their effect on fusion. The dipeptide inhibitor of endoprotease activity, Cbz-gly-phe-amide, inhibited fusion 70% at 3 mM whereas a dipeptide analogue, Cbz-gly-gly-amide, was without effect. Furthermore, orthovanadate, an inhibitor of phosphotyrosine phosphatase activity, stimulated fusion twofold at 0.5 mM. These results suggest that both tyrosine dephosphorylation and endoprotease activity contribute to the regulation of endosome fusion.

Topics: Animals; Carcinoma, Hepatocellular; Cell Fusion; Dipeptides; Endopeptidases; Enzyme-Linked Immunosorbent Assay; Ethylmaleimide; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Liver Neoplasms; Membrane Fusion; Mice; Organelles; Phosphoprotein Phosphatases; Protease Inhibitors; Rats; Tumor Cells, Cultured