Variability of neoplastic parameters in colon tumours, and its significance in diagnostic practice

Arginase activity in carcinoma of the gallbladder: a pilot study

Carcinoma of the gallbladder is the third most common cancer of the gastrointestinal tract. Recent studies have shown increased arginase activity in various malignancies. The main aim of this study was to evaluate whether arginase activity increases in carcinoma of the gallbladder. The arginase activity was evaluated in serum and gallbladder tissue in 22 patients with histologically proven carcinoma of the gallbladder and 20 patients with cholecystitis using spectrophotometry and western blot assay. The Student's t-test, analysis of variance, and Student-Newman-Keuls test were used for comparison of data and for statistical significance. The mean tissue arginase and serum arginase activity (118.64+/-17.45 and 15.91+/-1.91, respectively) in cases of carcinoma of the gallbladder were significantly higher in comparison with cholecystitis (86.37+/-4.45 and 12.73+/-0.72, respectively). Subgroup analysis showed stage III gallbladder carcinoma had the maximum tissue arginase activity (142.00+/-21.68 U/g of tissue) followed by stage II (124.15+/-19.88) and stage I (108.46+/-6.73). This significant rise in mean tissue arginase and serum arginase activity in patients with gallbladder cancer probably supports an association between arginase activity and the malignancy.

Glass fibers covered with sol-gel glass as a new support for affinity chromatography columns: a review

The search for mechanical supports for biochemically active compounds serving as immunochemical sensors has been the goal of many studies. A new compound in the form of gel fiberglass (GFG) membranes was recently developed as an example of such supports. In this review, these membranes were analyzed with respect to their use for cancer detection. The membranes are prepared from glass fibers covered with oxysilane to provide a sol-gel glass matrix. Derivatization of the support eliminates nonspecific adsorption. A thin layer of protein trapped in the gel glass during its preparation is deposited on the surface of a lattice of glass fibers. The major innovation of the membrane is its large area. External agents percolating through such a membrane contact a maximal number of molecules of the compounds trapped in the sol-gel glass. As a result, this membrane is highly effective. Each GFG column is built from a series of 20 to 30 membranes. The preparation of such columns is relatively simple, requiring only several hours. The capacity of GFG columns is high: the total amount of tumor-associated antigens (TAA) isolated by these columns from the blood of colon cancer patients reached 50% of the total protein and amounted to up to 9-12 mg/ml of serum. The main components of the isolated TAA were the soluble p66 and p51 proteins. A determination of their concentration by HPLC can be used for early cancer detection. Thus, the described method allows the easy and highly effective isolation of TAA and can be used for different goals, including cancer diagnosis. GFG supports have great potential for the isolation of various macromolecules utilizing specific ligands.

Oxygen free radical generating mechanisms in the colon: do the semiquinones of vitamin K play a role in the aetiology of colon cancer?

It is proposed that bile acids (deoxycholic acid), the K vitamins, iron(II) complexes and oxygen interact to induce an oncogenic effect in the colon by the generation of free radicals. In the relatively low oxidising/reducing conditions of the colonic lumen the K vitamins exist in the reduced form; however, if absorbed into the mucosa they have the capacity to be chemically oxidised and to enter into a redox cycle yielding oxygen radicals. The semiquinone radical of K(1) (phylloquinone) has been stabilised in bile acid mixed micelles and investigated by electron paramagnetic resonance spectroscopy and quantum chemical calculations. The estimated half-life of the radical was about 30 min which confirms a remarkably high stability in aqueous micellar solution. A model is presented in which the reduced K vitamins may initiate superoxide radical, O2(-*) generation leading to Fe(II) mediated Fenton reactions in the stem colon cells.

Gel fiberglass membranes for affinity chromatography columns and their application to cancer detection

The development of mechanical supports for biochemically active compounds serving as immunochemical sensors has been the goal of many studies. A new compound in the form of gel fiberglass (GFG) membranes was recently developed as an example of such supports. These membranes prepared from glass fibers covered with oxysilanes to create a matrix 'gel fiberglass' (R. Zusman, USA Patent #08/112,087, 1993) were used to prepare affinity chromatography columns for the isolation of soluble p53 protein from the serum of cancer patients. A thin layer of protein, trapped in gel glass during its preparation, was deposited on a lattice of glass fibers. Derivatization of the support eliminated nonspecific adsorption of proteins. Under such conditions, external agents percolating through a membrane may contact a maximum number of protein molecules trapped in the gel glass. The membranes are very stable, and can be stored in dry conditions for several months at room temperature. Affinity chromatography columns were prepared from the GFG membranes and used to isolate various proteins, including tumor-associated antigens (TAA). The capacity of the columns was calculated as the amount of protein (mg ml(-1)) isolated from TAA-containing solution, and amounted to up to 9 mg ml(-1) of serum in colon cancer patients. The cytoplasmic p53 protein was one of the main components of TAA isolated in our experiments. Its concentration was determined by HPLC. This protein was isolated from the serum of cancer patients in the highest concentration yet reported, up to 5 mg ml(-1). The described method allows an easy and highly effective isolation of TAA and can be used for important goals including cancer diagnosis.

Activation of adenomatous polyposis coli (APC) gene expression by the DNA-alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine requires p53

Development of colon cancer is a multistep process frequently involving mutations in both the APC and p53 tumor suppressor genes. In this study we treated the HCT-116 colon cancer cell line with alkylating agents including N-methyl-N'-nitro-N-nitrosoguanidine (MNNG),which is known to cause colon cancer in animals, and examined the expression of both APC and p53 genes. Exposure of cells with MNNG caused an 8-12-fold increase in the level of APC mRNA and protein. APC induction was shown to result from increased nuclear transcription of the APC gene and correlated with a concomitant increase in the p53 protein level after MNNG treatment. A necessary role for p53 in APC gene regulation is supported by the failure of MNNG to induce APC expression in cell lines either expressing very low levels of p53 (HeLa cells) or no p53 (K562 erythroleukemia cells). The overexpression of wild-type p53 gene into HCT-116 cells mimicked the effect of MNNG-induced expression of APC mRNA. A direct causal role for p53 in APC gene regulation was further evaluated by transfecting the wild-type p53 gene into K562 cells and observing a 5-fold increase in the APC gene expression. These results support a model featuring a direct link between p53 and APC in response to alkylation-induced DNA damage and suggest a novel role for p53 in a stress-response pathway involving APC.

Arginase activity determination. A marker of large bowel mucosa proliferation

Arginase activity of the intestinal mucosa was tested as a proliferative marker in the adenoma-carcinoma sequence. The enzyme activity was determined by an end-point colorimetric method with L-arginine as substrate. Arginase activity was evaluated in 430 biopsy samples of large bowel mucosa, polyps and cancer tissue. The activities (U/g protein, mean +/- SE; n) were: normal mucosa 83.2 +/- 7.3; 25, adenomas 199.4 +/- 19.1; 40, carcinomas 1269.7 +/- 174.9; 40, inflammatory bowel disease 1210.7 +/- 247.1; 34. The arginase activity differs significantly in the adenoma-carcinoma sequence according to the Duncan's test (p < 0.05).