Overexpression of CC3/TIP30 is associated with HER-2/neu status in breast cancer.

PURPOSE: The human CC3/TIP30 gene is a putative metastasis suppressor gene, based on the results of experimental studies using lung, colon and melanoma cell lines. However, there is very little evidence from studies on clinical material, in support of such a role for the gene. In this study, we evaluated the expression of CC3/TIP30 in human breast cancer tissue and investigated the possible associations with the clinicopathological parameters. METHODS: Total RNA and proteins were extracted from the frozen breast tumor and matched normal tissues. Evaluation of CC3/TIP30 expression was assessed by reverse transcription (RT)-PCR and reverse phase protein array. Immunohistochemistry of CC3/TIP30 on breast tissue microarrays was also analyzed. RESULTS: We have found that CC3/TIP30 expression is significantly associated with positive HER-2/neu status at both mRNA (P=0.023) and protein (P=0.016) levels. Immunohistochemical analysis on tissue microarrays also shows a positive correlation between CC3 expression and HER-2/neu status (P=0.0028). CONCLUSION: Our findings suggest a potential link between the expression of CC3/TIP30 gene and the HER-2/neu oncogene-mediated signal pathway.These findings could not have been predicted from previous experimental studies, and suggest that CC3/TIP30 may play a complex role in breast cancer.

Tissue microarray study for classification of breast tumors.

Clinical and pathological heterogeneity of breast cancer hinders selection of appropriate treatment for individual cases. Molecular profiling at gene or protein levels may elucidate the biological variance of tumors and provide a new classification system that correlates better with biological, clinical and prognostic parameters. We studied the immunohistochemical profile of a panel of seven important biomarkers using tumor tissue arrays. The tumor samples were then classified with a monothetic (binary variables) clustering algorithm. Two distinct groups of tumors are characterized by the estrogen receptor (ER) status and tumor grade (p = 0.0026). Four biomarkers, c-erbB2, Cox-2, p53 and VEGF, were significantly overexpressed in tumors with the ER-negative (ER-) phenotype. Eight subsets of tumors were further identified according to the expression status of VEGF, c-erbB2 and p53. The malignant potential of the ER-/VEGF+ subgroup was associated with the strong correlations of Cox-2 and c-erbB2 with VEGF. Our results indicate that this molecular classification system, based on the statistical analysis of immunohistochemical profiling, is a useful approach for tumor grouping. Some of these subgroups have a relative genetic homogeneity that may allow further study of specific genetically-controlled metabolic pathways. This approach may hold great promise in rationalizing the application of different therapeutic strategies for different subgroups of breast tumors.

Proteomics of breast cancer: enhanced expression of cytokeratin19 in human epidermal growth factor receptor type 2 positive breast tumors.

The human epidermal growth factor receptor, type 2 (HER-2/neu or c-erbB-2) is a 185 kDa transmembrane protein that is phosphorylated upon ligand binding and dimerization with members of the HER/c-erbB family and regulates cell growth and differentiation. Its overexpression is strongly associated with advanced disease, metastasis and poor clinical outcome. To better understand the mechanisms underlying the poor prognosis of breast tumors with HER-2/neu-positive status, parallel proteomic analyses were performed on estrogen receptor-negative and node-positive breast tumors with or without overexpression of the HER-2/neu oncogene, using laser capture microdissection and two-dimensional gel electrophoresis. The differentially expressed proteins were identified by peptide mass fingerprinting using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Cytokeratin 19 (CK19), one of the identified proteins, was highly expressed in the HER-2/neu-positive breast tumors when compared with HER-2/neu-negative breast tumors. The enhanced overexpression of CK19 in HER-2/neu-positive tumors was further analyzed using semiquantitative reverse-transcription polymerase chain reaction, Western blotting and reverse-phase protein arrays. Immunohistochemical staining of sections from a breast tumor tissue microarray of 97 tumors showed moderate to strong staining against anti-CK19 antibody in 20 (5 with moderate and 15 with strong staining) of the 26 HER-2/neu-positive tumors (76.9%) and in 22 (12 with moderate and 10 with strong staining) of 52 HER-2/neu-negative tumors (48%) (p = 0.002). Our results indicate that CK19, an intermediate fragment of the cytoskeleton, and other proteins showing differential expression, are likely to be intricately involved in intra- and intercellular molecular events driving the more aggressive tumor proliferation, invasion and metastasis associated with HER-2/neu-positive tumors.