Gene expression analysis has identified biologically relevant subclasses of breast cancer. However, most classification schemes do not robustly cluster all HER2+ breast cancers, in part due to limitations and bias of clustering techniques used. In this article, we propose an alternative approach that first separates the HER2+ tumors using a gene amplification signal for Her2/neu amplicon genes and then applies consensus ensemble clustering separately to the HER2+ and HER2À clusters to look for further substructure. We applied this procedure to a microarray data set of 286 early-stage breast cancers treated only with surgery and radiation and identified two basal and four luminal subtypes in the HER2À tumors, as well as two novel and robust HER2+ subtypes. HER2+ subtypes had median distant metastasis-free survival of 99 months [95% confidence interval (95% CI), 83-118 months] and 33 months (95% CI, 11-54 months), respectively, and recurrence rates of 11% and 58%, respectively. The low recurrence subtype had a strong relative overexpression of lymphocyte-associated genes and was also associated with a prominent lymphocytic infiltration on histologic analysis. These data suggest that early-stage HER2+ cancers associated with lymphocytic infiltration are a biologically distinct subtype with an improved natural history. [Cancer Res 2007;67(22):10669-76]

Hereditary breast cancers stem from germline mutations in susceptibility genes such as BRCA1, BRCA2 and PALB2, whose products function in the DNA damage response and redox regulation. Autophagy is an intracellular waste disposal and stress mitigation mechanism important for alleviating oxidative stress and DNA damage response activation; it can either suppress or promote cancer, but its role in breast cancer is unknown. Here we show that, similar to Brca1 and Brca2, ablation of Palb2 in mouse mammary gland resulted in tumor development with long latency and the tumors harbored mutations in Trp53. Interestingly, impaired autophagy, due to monoallelic loss of the essential autophagy gene Becn1, reduced Palb2-associated mammary tumorigenesis in Trp53-wild type but not conditionally null background. These results indicate that, in the face of DNA damage and oxidative stress elicited by PALB2 loss, p53 is a barrier to cancer development, whereas autophagy facilitates cell survival and tumorigenesis.

Purpose: Transforming growth factor-h (TGF-h) suppresses tumor development by inhibiting cellular proliferation, inducing differentiation and apoptosis, and maintaining genomic integrity. However, once tumor cells escape from the tumor-suppressive effects of TGF-h, they often constitutively overexpress and activateTGF-h, which may promote tumor progression by enhancing invasion, metastasis, and angiogenesis and by suppressing antitumor immunity. The purpose of this study was to test this hypothesis usingTGF-h pathway antagonists. Experimental Design: We examined the effects of selectiveTGF-h type I receptor kinase inhibitors, SD-093 and SD-208, on two murine mammary carcinoma cell lines (R3Tand 4T1) in vitro and in vivo. Results: Both agents blocked TGF-h-induced phosphorylation of the receptor-associated Smads, Smad2 and Smad3, in a dose-dependent manner, with IC 50 between 20 and 80 nmol/L. TGF-h failed to inhibit growth of these cell lines but stimulated epithelial-to-mesenchymal transdifferentiation, migration, and invasiveness into Matrigel in vitro. These effects were inhibited by SD-093, indicating that these processes are partly driven byTGF-h. Treatment of syngeneic R3T or 4T1tumor-bearing mice with orally given SD-208 inhibited primary tumor growth as well as the number and size of metastases. In contrast, SD-208 failed to inhibit R3T tumor growth or metastasis in athymic nude mice. Moreover, in vitro anti-4T1 cell cytotoxic T-cell responses of splenocytes from drug-treated animals were enhanced compared with cells from control animals. In addition, SD-208 treatment resulted in a decrease in tumor angiogenesis. Conclusion: TGF-h type I receptor kinase inhibitors hold promise as novel therapeutic agents for metastatic breast cancer.

Sixty cases of primary breast carcinoma have been studied using a monoclonal antibody, Ki67, which recognizes an antigen expressed by cells in G1, S, G2, and M phases of the cell cycle but not Go. A Ki67 score (positive cells/total tumour cells) was determined, and possible relationships between this index of cellular proliferation and a number of clinical and pathological parameters were investigated. There was a strong positive correlation between the Ki67 score and mitotic index (p less than 0.001), a weak negative correlation with age (p less than 0.02), and weak positive correlations with histological tumour grade (p less than 0.03), tumour necrosis (p less than 0.01), and cellular reaction (p less than 0.01). No relationship was noted between the Ki67 score and tumour size, nodal status, tumour oestrogen receptor levels, or menopausal status. The Ki67 score may prove to be an objective indicator of biological behaviour and thus be of clinical significance, particularly since it is not strongly related to other clinical and pathological parameters used in predicting outcome in breast carcinoma.