Phosphatase and tensin homolog deleted on chromosome ten (Pten) in stromal fibroblasts suppresses epithelial mammary tumors, but the underlying molecular mechanisms remain unknown. Using proteomic and expression profiling, we show that Pten loss from mammary stromal fibroblasts activates an oncogenic secretome that orchestrates the transcriptional reprogramming of other cell types in the microenvironment. Downregulation of miR-320 and upregulation of one of its direct targets, ETS2, are critical events in Pten-deleted stromal fibroblasts responsible for inducing this oncogenic secretome, which in turn promotes tumor angiogenesis and tumor cell invasion. Expression of the Pten-miR-320-Ets2 regulated secretome distinguished human normal breast stroma from tumor stroma and robustly correlated with recurrence in breast cancer patients. This work reveals miR-320 as a critical component of the Pten tumor suppressor axis that acts in stromal fibroblasts to reprogram the tumor microenvironment and curtail tumor progression.

Breast carcinoma (BC) has been extensively profiled by high-throughput technologies for over a decade, and broadly speaking, these studies can be grouped into those that seek to identify patient subtypes (studies of heterogeneity) or those that seek to identify gene signatures with prognostic or predictive capacity. The sheer number of reported signatures has led to speculation that everything is prognostic in BC. Here, we show that this ubiquity is an apparition caused by a poor understanding of the interrelatedness between subtype and the molecular determinants of prognosis. Our approach constructively shows how to avoid confounding due to a patient's subtype, clinicopathological profile, or treatment profile. The approach identifies patients who are predicted to have good outcome at time of diagnosis by all available clinical and molecular markers but who experience a distant metastasis within 5 years. These inherently difficult patients (~7% of BC) are prioritized for investigations of intratumoral heterogeneity.

IntroductionCT10 regulator of kinase (Crk) adaptor proteins (CrkI, CrkII and CrkL) play a role in integrating signals for migration and invasion of highly malignant breast cancer cell lines. This has important implications, as elevated CrkI/II protein levels were observed in a small cohort of breast cancer patients, which identified a potential role for Crk proteins in breast cancer progression. Numerous in vitro studies identified a role for Crk proteins in cell motility, but little is known about how Crk proteins contribute to breast cancer progression in vivo.MethodsThe clinical significance of Crk proteins in human breast cancer was assessed by analyzing published breast cancer datasets using a gene expression signature that was generated following CrkII over-expression and by examining Crk protein expression in tissue microarrays of breast tumors (n = 254). Stable knockdown of Crk (CrkI/CrkII/CrkL) proteins was accomplished using a short hairpin RNA (shRNA)-mediated approach in two basal breast cancer cell lines, MDA-231 1833TR and SUM1315, where the former have a high affinity to form bone metastases. Both in vitro assays (cell migration, invasion, soft agar growth) and in vivo experiments (intra-cardiac, tibial and mammary fat pad injections) were performed to assess the functional significance of Crk proteins in breast cancer.ResultsA gene signature derived following CrkII over-expression correlated significantly with basal breast cancers and with high grade and poor outcome in general. Moreover, elevated Crk immunostaining on tissue microarrays revealed a significant association with highly proliferative tumors within the basal subtype. RNAi-mediated knockdown of all three Crk proteins in metastatic basal breast cancer cells established a continued requirement for Crk in cell migration and invasion in vitro and metastatic growth in vivo. Furthermore, Crk ablation suppressed anchorage independent growth and in vivo orthotopic tumor growth. This was associated with diminished cell proliferation and was rescued by expression of non-shRNA targeted CrkI/II. Perturbations in tumor progression correlated with altered integrin signaling, including decreased cell spreading, diminished p130Cas phosphorylation, and Cdc42 activation.ConclusionsThese data highlight the physiological importance of Crk proteins in regulating growth of aggressive basal breast cancer cells and identify Crk-dependent signaling networks as promising therapeutic targets.

Thoracic radiotherapy may produce the morbidity-associated lung responses of alveolitis or fibrosing alveolitis in treated cancer patients. The genetic factors that influence a patient's likelihood of developing alveolitis and the relationship of this inflammatory response to the development of fibrosis are largely unknown. Herein we use genetic mapping to identify radiation-induced lung response susceptibility loci in reciprocal backcross mice bred from C3H/HeJ (alveolitis response) and C57BL/6J ( fibrosing alveolitis/fibrosis response) strains. Mice were treated with 18-Gy whole thorax irradiation and their survival, lung histopathology, and bronchoalveolar lavage cell types were recorded. A genome-wide scan was completed using 139 markers. The C3H/HeJ alveolitis response included mast cell infiltration and increased neutrophil numbers in the lavage compared with the level in the C57BL/6J strain, which developed fibrosis. In backcross mice, posttreatment survival was dictated by the development of an alveolitis response with increased mast cell, bronchoalveolar lavage total cell, and neutrophil numbers. Fibrosis was measured only in a subset of mice developing alveolitis and, in these mice, was associated with neutrophil count. Genotyping revealed coinheritance of C3H alleles (chromosomes 2, 4, 19, and X) and C57BL/6J alleles (chromosomes 1, 7, 9, and 17) to result in higher fibrosis scores in backcross mice. Mice that inherited C57BL/6J alleles at the putative alveolitis susceptibility loci were spared this response and lived to the end of the experiment. In this animal model, independent loci control the development of alveolitis from fibrosis, whereas fibrosing alveolitis occurs with the coinheritance of these factors.