MicroRNA93 regulates proliferation and differentiation of normal and malignant breast stem cells.

MicroRNAs (miRNAs) play important roles in normal cellular differentiation and oncogenesis. microRNA93 (mir-93), a member of the mir106b-25 cluster, located in intron 13 of the MCM7 gene, although frequently overexpressed in human malignancies may also function as a tumor suppressor gene. Using a series of breast cancer cell lines representing different stages of differentiation and mouse xenograft models, we demonstrate that mir-93 modulates the fate of breast cancer stem cells (BCSCs) by regulating their proliferation and differentiation states. In "claudin(low)" SUM159 cells, expression of mir-93 induces Mesenchymal-Epithelial Transition (MET) associated with downregulation of TGFß signaling and downregulates multiple stem cell regulatory genes, including JAK1, STAT3, AKT3, SOX4, EZH1, and HMGA2, resulting in cancer stem cell (CSC) depletion. Enforced expression of mir-93 completely blocks tumor development in mammary fat pads and development of metastases following intracardiac injection in mouse xenografts. The effect of mir-93 on the CSC population is dependent on the cellular differentiation state, with mir-93 expression increasing the CSC population in MCF7 cells that display a more differentiated "luminal" phenotype. mir-93 also regulates the proliferation and differentiation of normal breast stem cells isolated from reduction mammoplasties. These studies demonstrate that miRNAs can regulate the states and fates of normal and malignant mammary stem cells, findings which have important biological and clinical implications.

Breast cancer stem cells are regulated by mesenchymal stem cells through cytokine networks.

We have used in vitro and mouse xenograft models to examine the interaction between breast cancer stem cells (CSC) and bone marrow-derived mesenchymal stem cells (MSC). We show that both of these cell populations are organized in a cellular hierarchy in which primitive aldehyde dehydrogenase expressing mesenchymal cells regulate breast CSCs through cytokine loops involving IL6 and CXCL7. In NOD/SCID mice, labeled MSCs introduced into the tibia traffic to sites of growing breast tumor xenografts where they accelerated tumor growth by increasing the breast CSC population. With immunochemistry, we identified MSC-CSC niches in these tumor xenografts as well as in frozen sections from primary human breast cancers. Bone marrow-derived MSCs may accelerate human breast tumor growth by generating cytokine networks that regulate the CSC population.

Increased risk of adrenal insufficiency following etomidate exposure in critically injured patients.

BACKGROUND: Timely diagnosis and treatment of adrenal insufficiency (AI) dramatically reduces mortality in trauma patients. We sought to identify risk factors and populations with a high risk of developing AI. DESIGN: Retrospective registry study. SETTING: Academic level I trauma center. PATIENTS: All trauma patients in the intensive care unit who underwent cosyntropin stimulation testing (CST) for presumed AI from January 1, 2002, through December 31, 2004. INTERVENTIONS: Cosyntropin stimulation testing, in which response was defined as an increase of 9 mug/dL (248 nmol/L) or more in cortisol level. MAIN OUTCOME MEASURES: Risk factors for developing AI in critically ill trauma patients. RESULTS: In 137 patients, CST was performed; 83 (60.6%) were nonresponders and 54 (39.4%) were responders. Age, sex, race, trauma mechanism, Injury Severity Score, and Revised Trauma Score were not statistically different between the groups. Rates of sepsis/septic shock, mechanical ventilation, and mortality were also similar between the 2 groups. However, rates of hemorrhagic shock on admission (45 [54%] vs 16 [30%]), requirement of vasopressor support (65 [78%] vs 28 [52%]), and etomidate exposure (59 [71%] vs 28 [52%]) were all significantly higher in the nonresponder group (P < .01). The increased risk of AI remained after controlling for potential confounding covariates (age, mechanism, Injury Severity Score, and Revised Trauma Score). CONCLUSIONS: Exposure to etomidate is a modifiable risk factor for the development of AI in this sample of critically injured patients. The use of etomidate for procedural sedation and rapid-sequence intubation in this patient population should be reevaluated.