Nuclear localization of MUC1 extracellular domain in breast, head and neck, and colon cancer.

BACKGROUND: The glycoprotein MUC1 is overexpressed and underglycosylated in cancer cells. MUC1 is translated as a single polypeptide that undergoes autocleavage into 2 subunits (the extracellular domain and the cytoplasmic tail), and forms a stable heterodimer at the apical membrane of normal epithelial cells. The MUC1 cytoplasmic tail localizes to the cytoplasm of transformed cells and is targeted to the nucleus. AIMS: To study the expression of the MUC1 extracellular subunit in cell nuclei of neoplastic breast, head and neck, and colon samples. MATERIALS AND METHODS: 330 primary tumor samples were analyzed: 166 invasive breast carcinomas, 127 head and neck tumors, and 47 colon tumors; 10 benign breast disease (BBD) and 40 normal specimens were also included. A standard immunohistochemical method with antigen retrieval was performed. Nuclear fractions from tissue homogenates and breast cancer cell lines (ZR-75, MDA-MB-231, MCF7, and T47D) were obtained and analyzed by Western blotting (WB). The anti-MUC1 extracellular subunit monoclonal antibody HMFG1 was used for immunohistochemistry. RESULTS: 37/166 breast cancer specimens, 5/127 head and neck cancer specimens, 2/47 colon cancer samples, and 3/10 BBD samples showed immunohistochemical staining at the nuclear level. No nuclear reaction was detected in normal samples. By WB, breast and colon cancer purified nuclear fractions showed reactivity at 200 kDa in 3/30 breast and 3/20 colon cancer samples as well as purified nuclear fractions obtained from breast cancer cell lines. CONCLUSIONS: This study shows that the MUC1 extracellular domain might be translocated to the cell nucleus in breast, head and neck, and colon cancer as well as BBD.

Humoral immune response against tumoral mucin 1 (MUC1) in breast cancer patients.

The aim of this study was to elucidate whether the IgG humoral immune response to breast cancer cells is directed to the aberrant mucin-1 (MUC1) associated to this type of cancer. To this aim, an adaptation of immunohistochemistry (IHC) was performed on samples of 45 breast cancer tissues, 12 benign disease tissues, and 31 normal tissues, incubated with matched serum samples from the same patients. Each serum sample was also incubated, with a modified immunocytochemistry (ICC), with MCF7 cells. In both techniques, serum was employed instead of the primary antibody. In the case of IHC, the reactivity with sera diminished when added after previous incubation of the tumor/tissue with an anti-MUC1 mAb; the reduction in reactivity was: from 93% to 44% in breast cancer tissues, and from 100% to 67% in benign disease tissues. The reactivity of normal samples (36%) remained unchanged. In the case of ICC, the reactivity with sera decreased after incubation with anti-MUC1 mAb from 71% to 16% in breast cancer tissues, from 83% to 0% in benign disease tissues, and from 52% to 10% in normal serum samples. These results were confirmed employing siRNA MUC1 transient gene knockdown. By Western blot analysis -after immunoprecipitation (IP) of the circulating MUC1- and ELISA, the TF antigen was detected in circulating MUC1 in all breast cancer and benign samples while Tn was detected in 38% of the samples.
The existence of IgG autoantibodies against aberrantly glycosylated MUC1 may have a protective role and may contribute to a better prognosis in some patients. Enhancement of this natural immune response may constitute an alternative therapeutic strategy.

Invasive breast cancer in Argentine women: association between risk and prognostic factors with antigens of a peptidic and carbohydrate nature.

OBJECTIVE: In breast cancer, several tumor markers have been identified. The marker most extensively associated with breast cancer is MUC1. The objective of the study was to analyze prognostic and risk factors in relation to tumor markers in order to clarify breast cancer biology. A total of 349 primary tumor samples and lymph nodes from breast cancer patients were studied. Risk and prognostic factors were considered. An immunohistochemical approach was applied and an extensive statistical analysis was performed, including frequency analysis and analysis of variance. Correlation among variables was performed with principal component analysis. RESULTS: All the antigens showed an increased expression according to tumor size increment; moreover, sialyl Lewis x expression showed a significant increase in relation to disease stage, whereas Tn and TF presented a positive tendency. Vascular invasion was related to sialyl Lewis x expression and number of metastatic lymph nodes. Taking into account risk factors, when a patient had at least one child, Lewis antigens diminished their expression. In relation to breastfeeding, sialyl Lewis x expression diminished, although its apical expression increased. CONCLUSION: Associations between MUC1 and carbohydrate antigens and risk and prognostic factors show the complexity of the cellular biological behavior that these antigens modulate in breast cancer.

Comparative immunohistochemical study of MUC1 and carbohydrate antigens in breast benign disease and normal mammary gland.

The aim was to compare the expression of MUC1 and carbohydrate antigens in 124 tissue samples; 42 fibroadenoma (FA), 23 nonproliferative benign diseases (NPF), 25 usual epithelial hyperplasia (UEH), 7 atypical ductal hyperplasia (ADH), and 27 breast normal tissues. An immunohistochemical approach was adopted, using the following antibodies: reactive with MUC1 variable number of tandem repeats (C595, HMFG2, and SM3 monoclonal antibodies), anti-MUC1-cytoplasmic tail polyclonal antibody (CT33), and anti-carbohydrate antigens (sialyl Lewis x, Lewis x, Lewis y, Tn, and Thomsen-Friedenreich epitopes). Positive area of reaction, intensity, and pattern of expression were considered. A reactivity index was calculated as intensity (I) x 100+percentage of positive area (A). Statistical analysis comprised frequency analysis, P < 0.05, analysis of variance, and multiple correlation with principal component analysis. All samples expressed MUC1, detected by at least one anti-MUC1 antibody whereas Lewis x was the carbohydrate antigen most frequently found in all groups whereas variable number of tandem repeats MUC1 and Lewis x showed the highest correlation: 93% of normal samples, 62.5% of NPF, 87% of FA, 85% of UEH, and finally 80% of ADH. Although principal component analysis using reactivity indexes explained only 39% of data variability, normal samples appeared grouped and separated from benign breast diseases, which remained spread. Thomsen-Friedenreich was the only antigen that showed an increased tendency for positive expression and intensity from NPF through FA, UEH to ADH, whereas it was not detected in normals. With respect to the pattern of expression, an apical pattern was predominantly found in all the groups.

Tissue and serum MUC1 mucin detection in breast cancer patients.

Tumor MUC1 expression as well as levels of MUC1, MUC1 circulating immune complexes (MUC1-CIC) and free antibodies against MUC1 (IgG and IgM-MUC1) were evaluated in 70 breast cancer patients with different stages of disease. Controls included: 135 serum samples from healthy women, normal mammary tissue samples (n = 7) and benign breast disease specimens (n = 6). In all assays, pre- and post-vaccination serum samples from breast cancer patients belonging to a vaccination protocol developed at the Memorial Sloan Kettering Cancer Center (New York, USA) were included as controls. Serum MUC1 was measured through Cancer Associated Serum Antigen test and CA15-3 test. Employing ELISA, MUC1-CIC-IgG/M were measured with either C595 or SM3 monoclonal antibodies (MAb) as catchers and also free antibodies against MUC1 (IgG and IgM) using 100mer peptide as catcher. Employing multivariate statistical analysis, results were correlated with age, tumor type, stage of disease and grade of differentiation. By quantitative immunohistochemistry using three anti-MUC1 core protein MAbs (C595, HMFG2 and SM3), tumor MUC1 was detected in 60/70 (86%) breast cancer specimens which reacted with at least one of these MAbs. High MUCI serum levels were detected in 14/67 (21%); IgG and IgM anti-MUC1 antibodies were found elevated in 32 and 14%, respectively, while IgG-MUC1-CIC-measured with C595 in 42% and IgM-MUC1-CIC in 54%; finally, SM3 was positive in 43 and 18%, respectively. Results of these studies demonstrate that in a group of breast cancer patients, MUC1 was detected both in tissue specimens as well as free in serum samples; furthermore, MUC1 can also circulate complexed with IgG and IgM antibodies; thus an accurate measurement should include free and complexed forms. On the other hand, immunohistochemical studies on breast cancer tissues may contribute to reveal different MUC1 glycoforms.

Effect of sublethal cadmium on liver arginase activity of the toad Bufo arenarum

Se determinó la actividad de arginasa hepática en Bufo arenarum adulto luego de la administración de 2,8 y 5,0 mg Cd/Kg p.c., inyectados por tercios a lo largo de 26 días. La actividad específica de la enzima en los sapos inyectadod con Cd se redujo 37-55 por ciento con respecto a los controles. La reducción de la actividad podría ser considerada como respuesta bioquímica a cantidades subletales de Cd en una de las principales enzimas del ciclo de la urea

Effect of sublethal cadmium on liver arginase activity of the toad Bufo arenarum

Se determinó la actividad de arginasa hepática en Bufo arenarum adulto luego de la administración de 2,8 y 5,0 mg Cd/Kg p.c., inyectados por tercios a lo largo de 26 días. La actividad específica de la enzima en los sapos inyectadod con Cd se redujo 37-55 por ciento con respecto a los controles. La reducción de la actividad podría ser considerada como respuesta bioquímica a cantidades subletales de Cd en una de las principales enzimas del ciclo de la urea(AU)

Cross-reactivity of anti-10kD heat shock protein antibodies in leprosy and tuberculosis patients

The response to recombinant 10-KD heat shock protein (HSP of Mycobacterium leprae (rML10) was evaluated by indirect ELISA in sera from leprosy patients, household contacts, tuberculosis patients and healthy controls a leprosy-endemic area in tne North East of Argentina. Some technical parameters were a analyzed: within-assay and between-assay variability, dose-response curves and dectability indexed (specificity and sensitivity) of ELISA applied to measure anti-10kDa antibodies. High levels of these antibodies have already been reported in positive baciloscopy patients; herein we have also demonstrated that tuberculosis patients sera cross-react with this M. leprae antigen. This test seems to have a low sensificity for leporsy detection; it confirms that antibodies against highly conserved HSP antigens are important in the polycional response against mycobacterial epitopes in leprosy as well as in tuberculosis.

Cross-reactivity of anti-10kD heat shock protein antibodies in leprosy and tuberculosis patients

The response to recombinant 10-KD heat shock protein (HSP of Mycobacterium leprae (rML10) was evaluated by indirect ELISA in sera from leprosy patients, household contacts, tuberculosis patients and healthy controls a leprosy-endemic area in tne North East of Argentina. Some technical parameters were a analyzed: within-assay and between-assay variability, dose-response curves and dectability indexed (specificity and sensitivity) of ELISA applied to measure anti-10kDa antibodies. High levels of these antibodies have already been reported in positive baciloscopy patients; herein we have also demonstrated that tuberculosis patients sera cross-react with this M. leprae antigen. This test seems to have a low sensificity for leporsy detection; it confirms that antibodies against highly conserved HSP antigens are important in the polycional response against mycobacterial epitopes in leprosy as well as in tuberculosis. (AU)