The tumor-suppressor gene p53 is altered by missense mutation in numerous human malignancies. However, the biochemical properties of p53 and the effect of mutation on these properties are unclear. A human DNA sequence was identified that binds specifically to wild-type human p53 protein in vitro. As few as 33 base pairs were sufficient to confer specific binding. Certain guanines within this 33-base pair region were critical, as methylation of these guanines or their substitution with thymine-abrogated binding. Human p53 proteins containing either of two missense mutations commonly found in human tumors were unable to bind significantly to this sequence. These data suggest that a function of p53 may be mediated by its ability to bind to specific DNA sequences in the human genome, and that this activity is altered by mutations that occur in human tumors.
An increased expression of lysosomal enzymes, cathepsin (Cat) D, Cat B and Cat L, was observed in various human tumours and after in vitro cell transformation. To establish possible co-ordination in their expression, all three cathepsins were determined in human breast tumours and in transformed human breast epithelial cells (HBEC). In breast carcinoma (n = 120) all three cathepsins, determined immunochemically and by enzymatic activity, were increased compared to normal breast tissues. The activities, correlated with the corresponding protein masses for Cat D (r = 0.77, p < 0.01), but not for Cat B and Cat L. Significant increase in Cat B activity was observed in stage II compared to stage I tumours, and Cat L activity in stage III compared to stage II tumours, but no significant correlation of cathepsin protein with tumour stage (TNM) was established. No significant correlation between Cat D and the cysteine cathepsins B and L was observed. Similarly, Cat D, Cat B and Cat L levels did not correlate in the in vitro system, e.g. in the five transformed HBEC, such as evolved after dimethylbenz(a)anthracene treatment and c-Has-ras oncogene transfection of diploid MCF-10F cell line (Calaf et al., 1993). Transformed cells showed increased anchorage-independent growth and invasive capability (MCF-10 < MCF-10FTras < D3 < D3-1 < D3-1Tras). The intracellular level of Cat D was not related to cell invasiveness, while total cellular Cat B and Cat L increased 13 fold and 4 fold, respectively, in the most invasive cell line, D3-1Tras compared to MCF-10F.(ABSTRACT TRUNCATED AT 250 WORDS)
Background: The complex between urokinase (uPA) and its type-1 inhibitor (PAI-1) is formed exclusively from the active forms of these components; thus, the complex concentration in a biological sample may reflect the ongoing degree of plasminogen activation. Our aim was to establish an ELISA for specific quantification of the uPA:PAI-1 complex in plasma of healthy donors and breast cancer patients. Methods: A kinetic sandwich format immunoassay was developed, validated, and applied to plasma from 19 advanced-stage breast cancer patients, 39 age-matched healthy women, and 31 men. Results: The assay detection limit was <2 ng/L, and the detection of complex in plasma was validated using immunoabsorption, competition, and recovery tests. Eighteen cancer patients had a measurable complex concentration (median, 68 ng/L; range, <16 to 8700 ng/L), whereas for healthy females and males the median signal values were below the detection limit (median, <16 ng/L; range, <16 to 200 ng/L; P <0.0001). For patient plasma, a comparison with total uPA and PAI-1 showed that the complex represented a variable, minor fraction of the uPA and PAI-1 concentrations of each sample. Conclusion: The reported ELISA enables detection of the uPA:PAI-1 complex in blood and, therefore, the evaluation of the complex as a prognostic marker in cancer.
Fatty acid synthase (FASN), is an enzyme capable of de novo fatty acid synthesis and highly expressed and activated in most human carcinomas. Fatty acid synthase is a multi-enzyme protein that catalyzes fatty acid synthesis and is not a single enzyme but a whole enzymatic system composed of two identical 272 KDa multifunctional polypeptides. Fatty-acid synthesis is now associated with clinically aggressive tumor behavior, tumor-cell growth and is associated with poor prognosis in prostate and breast cancer. Its inhibition is selectively cytotoxic to human cancer cells. Thus, FASN and fatty acid metabolism have become an important focus for the diagnostic and treatment of cancer. We have developed a panel of anti-human FASN Mab for application to several diagnostic platforms. Recombinant full length intact FASN protein (rFASN) was used to immunized C57BL/6 mice, sera were collected from pre- and post-immunized mice and tested by ELISA and Western blot on rFASN protein or rFASN immobilized on Western blot. Spleens from mice with the highest anti-FASN antibody titer was fused with a mouse myeloma cell line Sp2/0-Ag14 for hybridoma production. Among the panel of positive anti-FASN clones selected, two clones with isotype of IgG1kappa have shown strong reactivity to the rFASN and native FASN protein on Western analysis. Upon further Western analyses with cell lysates, we have demonstrated specific detection of FASN protein in human embryonic kidney cells (HEK), HEK cells overexpressing the rFASN protein, HOP-62 cells which express low levels of FASN and MALME cells, which express high levels of FASN. Additional biochemical characterization of these antibodies is ongoing, and includes epitope mapping and reactivity to various FASN protein fragments. These anti-FASN antibodies will be tested by IHC, ELISA to compare tissues expression levels of FAS by IHC or circulating levels of the FASN in both normal and cancer patients. With the increasing development of FAS inhibitors these antibodies will be tested as Companion Diagnostics and tested to see if the rise and fall of the FASN circulating levels correspond with cancer progression or therapy response. Citation Format: Walter P. Carney, Wendy Zhang, David Jarosz, Patrick Muraca, Sunny TAM. Diagnostic applications of fatty acid synthase monoclonal antibodies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4332. doi:10.1158/1538-7445.AM2014-4332
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