Akt/PKB is a serine/threonine kinase that promotes tumor cell growth by phosphorylating transcription factors and cell cycle proteins. There is particular interest in finding tumor-specific substrates for Akt to understand how this protein functions in cancer and to provide new avenues for therapeutic targeting. Our laboratory sought to identify novel Akt substrates that are expressed in breast cancer. In this study, we determined that activated Akt is positively correlated with the protein expression of the transcription/translation factor Y-box binding protein-1 (YB-1) in primary breast cancer by screening tumor tissue microarrays. We therefore questioned whether Akt and YB-1 might be functionally linked. Herein, we illustrate that activated Akt binds to and phosphorylates the YB-1 cold shock domain at Ser102. We then addressed the functional significance of disrupting Ser102 by mutating it to Ala102. Following the stable expression of Flag:YB-1 and Flag:YB-1 (Ala102) in MCF-7 cells, we observed that disruption of the Akt phosphorylation site on YB-1 suppressed tumor cell growth in soft agar and in monolayer. This correlated with an inhibition of nuclear translocation by the YB-1(Ala102) mutant. In conclusion, YB-1 is a new Akt substrate and disruption of this specific site inhibits tumor cell growth.

Recent gene profiling studies have identified a new breast cancer subtype, the basal-like group, which expresses genes characteristic of basal epithelial cells and is associated with poor clinical outcomes. However, the genes responsible for the aggressive behavior observed in this group are largely unknown. Here we report that the small heat shock protein α-basic-crystallin (αB-crystallin) was commonly expressed in basal-like tumors and predicted poor survival in breast cancer patients independently of other prognostic markers. We also demonstrate that overexpression of αB-crystallin transformed immortalized human mammary epithelial cells (MECs). In 3D basement membrane culture, αB-crystallin overexpression induced luminal filling and other neoplastic-like changes in mammary acini, while silencing αB-crystallin by RNA interference inhibited these abnormalities. αB-Crystallin overexpression also induced EGF-and anchorage-independent growth, increased cell migration and invasion, and constitutively activated the MAPK kinase/ERK (MEK/ERK) pathway. Moreover, the transformed phenotype conferred by αB-crystallin was suppressed by MEK inhibitors. In addition, immortalized human MECs overexpressing αB-crystallin formed invasive mammary carcinomas in nude mice that recapitulated aspects of human basal-like breast tumors. Collectively, our results indicate that αB-crystallin is a novel oncoprotein expressed in basal-like breast carcinomas that independently predicts shorter survival. Our data also implicate the MEK/ERK pathway as a potential therapeutic target for these tumors.

Purpose: FOXA1, a forkhead family transcription factor, is essential for optimum expression of f50% of estrogen receptor a (ERa):estrogen responsive genes. FOXA1 is expressed in breast cancer cells. It segregates with genes that characterize the luminal subtypes in DNA microarray analyses. The utility of FOXA1 as a possible independent prognostic factor has not been determined in breast cancers. Materials and Methods: A tissue microarray comprising tumors from 438 patients with 15.4 years median follow-up was analyzed for FOXA1 expression by immunohistochemistry. Interpretable FOXA1 expression obtained in 404 patients was analyzed along with other prognostic factors like tumor grade, size, nodal status, ER, progesterone receptor (PR), and HER2/neu.Results: FOXA1expression (score >3) was seen in 300 of 404 breast cancers and it correlated with ER (P = 0.000001), PR (P = 0.00001), and luminal A subtype (P = 0.000001). Loss of expression was noted with worsening tumor grade (P = 0.001). Univariate analysis showed nodal status (P = 0.0000012), tumor size (P = 0.00001), FOXA1 (P = 0.0004), and ER (P = 0.012) to be predictors of breast cancer^specific survival. Multivariate analysis showed only nodal status (P = 0.001) and tumor size (P = 0.039) to be significant prognostic factors, whereas FOXA1 (P = 0.060) and ER (P = 0.131) were not significant. In luminal subtype A patient subgroup, FOXA1 expression was associated with better cancer-specific survival (P = 0.024) and in ER-positive subgroup, it was better predictor of cancer-specific survival (P = 0.009) than PR (P = 0.213). Conclusion: FOXA1 expression correlates with luminal subtype A breast cancer and it is significant predictor of cancer-specific survival in patients with ER-positive tumors. Prognostic ability of FOXA1 in these low-risk breast cancers may prove to be useful in clinical treatment decisions.Estrogen receptor (ER) expression is a good predictive and prognostic factor in breast cancer. However, not all ER-positive breast cancers behave alike. Knowing why and how some ER-positive breast cancers behave differently than others is important from both research and clinical viewpoint. A clinician will certainly be more pleased to know which patients with ER-positive breast cancers need to be treated aggressively and a research scientist would be interested in knowing the pathways involved in these different behaviors and if any of those can serve as therapeutic targets.Estrogen plays an important role in the growth, proliferation, and differentiation of mammary epithelium. ERa and ERh mediate the biological action of estrogen by functioning as estrogen-activated transcription factors (1, 2). ERa is expressed in 10% to 15% of luminal epithelial cells of normal breast and these cells are generally considered slowly proliferating and well-differentiated cell types (3). However, >50% of breast cancers express ERa at the time of initial diagnosis (1). These findings suggest a distinct role for ERa in the growth of normal, immortalized, and transforme...

Intraepithelial tumor-infiltrating T cells have been correlated with improved outcomes in ovarian carcinoma, however, it is not known whether there is an association with disease stage, histological subtype, or BRCA mutation/expression. Two case series of ovarian carcinomas were included in the study; a retrospective series of 500 patients, and 40 prospectively collected cases fully characterized for BRCA1 mutation status and expression. Intraepithelial immune cells were assessed as present or absent by immunohistochemical staining of tissue microarrays. In the retrospective case series, the presence of intraepithelial CD8 þ T-cells correlated with improved disease-specific survival (P ¼ 0.027), whereas intraepithelial CD3 þ T cells did not (P ¼ 0.49). For serous ovarian carcinomas, the presence of intraepithelial CD3 þ and CD8 þ T-cells correlated with improved disease-specific survival (P ¼ 0.0016 and Pr0.0001, respectively). The presence of intraepithelial CD8 þ T cells was not associated with improved survival in endometrioid or clear cell carcinomas. On multivariate analysis, disease stage and CD8 þ T cells were found to be independently predictive of improved disease-specific survival, whereas grade, age at surgery, and type of adjuvant treatment were not. In the prospective patient cohort, intraepithelial CD8 þ T-cells correlated with the presence of mutation or loss of expression of BRCA1 through promoter methylation (P ¼ 0.019). Intraepithelial CD8 þ tumor-infiltrating T-cells correlate with improved clinical outcomes for all stages of ovarian cancer; this association is restricted to the serous ovarian cancer subtype, and is an independent prognostic factor on multivariate analysis. The presence of intraepithelial CD8 þ T cells also significantly correlates with loss of BRCA1. rates to chemotherapy and the demonstrated improvements in median overall survival, fewer than 40% of patients with advanced disease survive to 5 years. 3 Many potential molecular prognostic factors in ovarian cancer have been investigated (eg HER2, TP53). 4 Most factors were identified in small studies and have not been reproduced or independently validated, precluding clinical utility. In addition, mutations of the BRCA1 and 2 tumor suppressor genes have been associated with improved clinical outcomes 5-7 but the biologic mechanisms underlying these findings are not well understood to date.The prognostic significance of the host immune response, as defined by the presence of tumor-infiltrating lymphocytes, has been studied in ovarian