BackgroundDeletions of chromosome 10q23, including the PTEN (phosphatase and tensin homolog) locus, are known to occur in breast cancer, but systematic analyses of its clinical relevance are lacking.MethodsWe thus analyzed a tissue microarray (TMA) with 2,197 breast cancers by fluorescence in-situ hybridization (FISH) using a PTEN-specific probe.ResultsPTEN deletions were detected in 19 % of no special type, 9 % of lobular, 4 % of tubular cancers and 46 % in carcinomas with medullary features. 98.7 % of deletions were heterozygous and only 1.3 % were homozygous. PTEN deletion was significantly linked to advanced tumor stage (p = 0.0054), high-grade (p < 0.0001), high tumor cell proliferation (Ki67 Labeling Index; p < 0.0001), and shortened overall survival (p = 0.0090). PTEN deletions were inversely associated with features of luminal type breast cancers (ER/PR positivity; p < 0.0001 each, and CCND1 amplification; p = 0.0020). PTEN deletions were also strongly linked to amplification of genes involved in the PTEN/AKT pathway such as MYC (p = 0.0430) and HER2 (p = 0.0065). Remarkably the combined analysis of MYC, HER2, CCND1 and PTEN aberrations suggested that aberrations of multiple PTEN/AKT pathway genes have a strong additive effect on breast cancer prognosis. While cancers with one of these aberrations behaved only marginally different from cancers with none, disease outcome was markedly worse in cancers with two or more aberrations as compared to those with only one aberration (p = 0.0002). In addition, the particularly poor prognosis of patients with HER2 amplification and PTEN deletions challenges the concept of PTEN deletions interfering with trastuzumab therapy.ConclusionPTEN deletion occurs in a relevant fraction of breast cancers, and is linked to aggressive tumor behavior. Reduced PTEN function cooperates with MYC and HER2 activation in conferring aggressive phenotype to cancer cells.

Introduction: Activated Leukocyte Cell Adhesion Molecule (ALCAM/CD166) gained increasing attention regarding tumorprogression and metastatic spread in breast cancer. The aim of this study was to examine ALCAM expression levels in primary breast cancer and distant metastases of the same patient within 29 autopsy cases to better understand the underlying mechanisms of metastases and the role of adhesion molecules in this process. Material and Methods: Paraffin-embedded tissue of the primary and distant metastases (N = 84) were collected and ALCAM immunohistochemistry was performed. Results: The primary tumor and all metastases showed a statistically normally distributed ALCAM expression. ALCAM expression level average differs between immunoreactive score (IRS) (mean) 4.16 (lung)-5.00 (adrenal gland). Of the metastatic ALCAM expression levels we obtained an intra-class correlation (ICC) of 80.9%, indicating a strong cluster effect of measurements in the same patient. ALCAM expression scores in metastatic sites and in the primary analyzed by hierarchical regression analysis showed that ALCAM expression in the primary is prognostic for ALCAM expression in all different sites of metastases (slope = 0.773, p < 0.001, r2 = 0.504). Conclusion: ALCAM expression in the primary is positively correlated to ALCAM expression in metastases within one single patient. This could show a tumorbiological context of ALCAM for the development of metastases in breast cancer.

Abstract. Activated leukocyte cell adhesion molecule (ALCAM) is a membranous cell adhesion protein that is often expressed in breast cancer. Data on the prognostic impact of ALCAM expression is highly controversial in this cancer. To evaluate the clinical impact of ALCAM expression in a sufficiently large patient cohort, we utilized a tissue microarray (TMA) containing more than 2,100 primary breast cancers with clinical follow-up data by immunohistochemistry. TMA spots containing normal breast epithelium showed moderate to strong membranous ALCAM staining. ALCAM staining was strong in 66.2%, moderate in 10.9%, weak in 11.1% and absent in 11.8% of 1,778 (80.9%) interpretable breast cancer tissue spots. Decreased ALCAM expression was significantly associated with advanced tumor size (p=0.0017), unfavorable tumor grade (p<0.0001), negative ER and PR status (p<0.0001 each) as well as high Ki67 labeling index (p<0.0001). Cancers with ACLAM expression loss had a significantly poorer overall (p<0.0001) and disease-specific survival (p= 0.0088). This association also held true in the subset of nodal positive cancers (p<0.0001). In conclusion, these data demonstrate that ALCAM is generally expressed in normal and cancerous breast epithelium and that a marked reduction of ALCAM expression characterizes a subset of breast cancer patients with adverse tumor characteristics and unfavorable clinical outcome.