Faithful cell-cycle progression is tightly controlled by the ubiquitin-proteasome system. Here we identify a human Cullin 3-based E3 ligase (Cul3) which is essential for mitotic division. In a complex with the substrate-specific adaptors KLHL9 and KLHL13, Cul3 is required for correct chromosome alignment in metaphase, proper midzone and midbody formation, and completion of cytokinesis. This Cul3-based E3 ligase removes components of the chromosomal passenger complex from mitotic chromosomes and allows their accumulation on the central spindle during anaphase. Aurora B directly binds to the substrate-recognition domain of KLHL9 and KLHL13 in vitro, and coimmunoprecipitates with the Cul3 complex during mitosis. Moreover, Aurora B is ubiquitylated in a Cul3-dependent manner in vivo, and by reconstituted Cul3/KLHL9/KLHL13 ligase in vitro. We thus propose that the Cul3/KLHL9/KLHL13 E3 ligase controls the dynamic behavior of Aurora B on mitotic chromosomes, and thereby coordinates faithful mitotic progression and completion of cytokinesis.

Autoantibodies, a hallmark of both autoimmunity and cancer, represent an easily accessible surrogate for measuring adaptive immune responses to cancer. Sera can now be assayed for reactivity against thousands of proteins using microarrays, but there is no agreed-upon standard to analyze results. We developed a set of tailored quality control and normalization procedures based on ELISA validation to allow patient comparisons and determination of individual cutoffs for specificity and sensitivity. Sera from 60 patients with pancreatic cancer, 51 patients with ovarian cancer, and 53 age-matched healthy donors were used to assess the binding of IgG antibodies against a panel of >8000 human antigens using protein microarrays and fluorescence detection. The resulting data interpretation led to the definition and ranking of proteins with preferred recognition by the sera from cancer patients in comparison with healthy donors, both by frequency and strength of signal. We found that 202 proteins were preferentially immunogenic in ovarian cancer sera compared to 29 in pancreatic cancer, with few overlaps. Correlates of autoantibody signatures with known tumor expression of corresponding antigens, functional pathways, clinical stage, and outcome were examined. Serological analysis of arrays displaying the complete human proteome (seromics) represents a new era in cancer immunology, opening the way to defining the repertoire of the humoral immune response to cancer. serum antibody | biomarkers | protein microarrays | serology | autoantigen

NY-ESO-1 is a cancer testis antigen expressed in various malignancies and testicular germ cells. Because of its capacity to induce specific humoral and cellular immunity in patients with NY-ESO-1-positive carcinomas, it represents a promising target for cancer immunotherapy. In breast cancer, NY-ESO-1-mRNA was reported in up to 42%, but protein expression has not been determined to larger extent. In the present tissue microarray-based study, primary breast cancers (n 5 1,444), in situ lesion (n 5 148), recurrences (n 5 88), lymph node (n 5 525) and distant metastases (n 5 91) were studied for NY-ESO-1 expression by immunohistochemistry. NY-ESO-1-protein expression was compared with mRNA expression by real-time PCR. NY-ESO-1-protein was detected in 3.1% (4/128) in situ lesions and in 2.1% (28/1355) invasive breast cancer. There were 1.8% (9/493) NY-ESO-1-positive lymph node and 5.1% (4/78) positive distant metastases. NY-ESO-1 was more frequently expressed in grade 3 (4.9%) than in grade 2 (0.8%) and grade 1 (0.5%) carcinomas (p < 0.0001). Presence of tumor-infiltrating CD81 T-cells correlated with NY-ESO-1 (p < 0.0001) on the tissue microarray. On randomly selected large sections, 4 out of 9 NY-ESO-1-positive tumors displayed a brisk infiltrate of CD79a1 plasmocytes/B-cells, but none of 10 NY-ESO-1-negative tumors (p < 0.05). NY-ESO-1-mRNA expression was detected in frozen samples of NY-ESO-1-protein positive (n 5 6) and negative breast cancers (n 5 8) and in normal testis. Comparison between mRNA and protein expression revealed that only breast cancers with NY-ESO-1-mRNA levels comparable or higher than testis expressed NY-ESO-1-protein. These findings suggest that NY-ESO-1-positive breast cancers represent a small subset of poorly differentiated tumors with evidence of cellular and humoral immune response. ' 2007 Wiley-Liss, Inc.

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DyeCycleViolet was used to set up the side population (SP) functional assay aimed at identifying subpopulations of malignant pleural mesothelioma (MPM) tumor cells with chemoresistance phenotype associated with ABCG2 transporter activity. Self-renewal, chemoresistance and tumorigenicity were tested for SP and non-side population (NSP) cells. Tumors were characterized by mesothelin, calretinin, N-cadherin, D2-40 and Wilms tumor 1 (WT1) immunohistochemistry. Surface expression of mesenchymal stem cell markers CD90, CD73 and CD105 was investigated in SP and NSP cells. We identified SP cells with self-renewal properties and increased chemoresistance in MPM cell lines and tumor-derived primary cell cultures. Compared with the non-SP fraction (NSP), the SP fraction led to the development of tumors including cells with mesothelium precursor phenotype characterized by mesenchymal morphology, being WT1 negative but cytoplasmic D2-40 positive and having a tendency of increased tumorigenicity. The same phenotypic shift was observed in patients with relapsing tumors after chemotherapy. Furthermore, the SP cells were enriched in CD105(-)(/low) expressing cells, which were small sized and had increased tumorigenicity compared with CD105(high) cells. Taken together, our results support the hypothesis that MPM CD105(-)(/low), chemoresistant small sized SP cells may constitute the cellular pool out of which recurrence develops. Further characterization of mechanisms of chemoresistance and self-renewal should lead to targets specific for this subpopulation in MPM patients.

NY-BR-1 was recently identified by autologous serological typing of the recombinant expression library in a breast cancer patient. Extensive reverse transcriptase-polymerase chain reaction analysis revealed the presence of NY-BR-1 in normal breast tissue and tumors derived thereof. Except normal testis, no other normal tissue or tumors showed NY-BR-1 expression. However, nothing is known about the expression of its actual antigen. In the present study, we describe the generation of 2 new monoclonal antibodies, NY-BR-1#2 and NY-BR-1#3, to NY-BR-1 for the analysis of its expression on a protein level employing recombinant NY-BR-1 protein for the immunization of BALB/c mice. In normal tissues, immunohistochemical testing demonstrates NY-BR-1 in a mostly focal fashion in the epithelia of ducts and acini of the mammary gland. No other tissue was immunopositive including testis. In tumors, homogenous staining can be seen in almost all ductal carcinomas in situ and/or the intraductal component of invasive carcinomas. Invasive carcinomas show a lower number of NY-BR-1-positive tumors. Initial higher numbers of NY-BR-1 mRNA-positive invasive carcinomas are most likely based on sample error owing to the contamination of tumor tissue with remnants of normal breast epithelium. Sweat gland carcinomas, which are related to breast cancer, are also positive in about one-third of the cases. These data indicate that NY-BR-1 is a differentiation antigen of the mammary gland that could be useful for diagnosis and/or immunotherapy of breast carcinomas.

No abstract

Antibody-based cancer immunotherapy relies on the identification and characterization of target antigens and the development of potent antibodies recognizing the target. Here we report the expression analysis and molecular characterization of the differentiation antigen NY-BR-1, which we previously identified by using the SEREX (serological analysis of recombinant cDNA expression libraries) method. Corroborating methodologies, including mRNA quantitation and immunoblotting show that NY-BR-1 is strongly expressed in >70% of 129 breast tumors. Application of a NY-BR-1 specific antibody demonstrated NY-BR-1 expression in primary and metastastic breast cancers. In contrast, most of the breast cancer cell lines tested, expressed only low NY-BR-1 levels. Importantly, confocal microscopy revealed that ectopically expressed NY-BR-1 localizes to the cytoplasm and the cell membrane. NY-BR-1 localization in breast cancer specimens was also confirmed by immunohistochemistry. Bioinformatic analysis and deletion mutagenesis further show that NY-BR-1 membrane localization is mediated by 2 cis-active membrane targeting domains. Biochemical surface labeling and FACS analysis of live cells further characterize NY-BR-1 as a transmembrane protein, which can be specifically recognized by the anti-NY-BR-1 antibody on the surface of vital cells. The strong expression of NY-BR-1 in breast tumors, its cytoplasmic and membrane localization and accessibility to an ectopically applied antibody now suggest to pursue NY-BR-1 as a potential target for antibody-based therapies in breast cancer patients. ' 2007 Wiley-Liss, Inc.