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.

Probing tumor phenotypes using stable and regulated synthetic microRNA precursors.

RNA interference is a powerful method for suppressing gene expression in mammalian cells. Stable knock-down can be achieved by continuous expression of synthetic short hairpin RNAs, typically from RNA polymerase III promoters. But primary microRNA transcripts, which are endogenous triggers of RNA interference, are normally synthesized by RNA polymerase II. Here we show that RNA polymerase II promoters expressing rationally designed primary microRNA-based short hairpin RNAs produce potent, stable and regulatable gene knock-down in cultured cells and in animals, even when present at a single copy in the genome. Most notably, by tightly regulating Trp53 knock-down using tetracycline-based systems, we show that cultured mouse fibroblasts can be switched between proliferative and senescent states and that tumors induced by Trp53 suppression and cooperating oncogenes regress upon re-expression of Trp53. In practice, this primary microRNA-based short hairpin RNA vector system is markedly similar to cDNA overexpression systems and is a powerful tool for studying gene function in cells and animals.

An epigenetic switch regulates the ontogeny of AXL-positive/EGFR-TKi-resistant cells by modulating miR-335 expression.

Despite current advancements in research and therapeutics, lung cancer remains the leading cause of cancer-related mortality worldwide. This is mainly due to the resistance that patients develop against chemotherapeutic agents over the course of treatment. In the context of non-small cell lung cancers (NSCLC) harboring EGFR-oncogenic mutations, augmented levels of AXL and GAS6 have been found to drive resistance to EGFR tyrosine kinase inhibitors such as Erlotinib and Osimertinib in certain tumors with mesenchymal-like features. By studying the ontogeny of AXL-positive cells, we have identified a novel non-genetic mechanism of drug resistance based on cell-state transition. We demonstrate that AXL-positive cells are already present as a subpopulation of cancer cells in Erlotinib-naïve tumors and tumor-derived cell lines and that the expression of AXL is regulated through a stochastic mechanism centered on the epigenetic regulation of miR-335. The existence of a cell-intrinsic program through which AXL-positive/Erlotinib-resistant cells emerge infers the need of treating tumors harboring EGFR-oncogenic mutations upfront with combinatorial treatments targeting both AXL-negative and AXL-positive cancer cells.

Sleep disruption impairs haematopoietic stem cell transplantation in mice.

Many of the factors affecting the success of haematopoietic cell transplantation are still unknown. Here we show in mice that donor sleep deprivation reduces the ability of its haematopoietic stem cells (HSCs) to engraft and reconstitute the blood and bone marrow of an irradiated recipient by more than 50%. We demonstrate that sleep deprivation downregulates the expression of microRNA (miR)-19b, a negative regulator of the suppressor of cytokine signalling (SOCS) genes, which inhibit HSC migration and homing. Accordingly, HSCs from sleep-deprived mice have higher levels of SOCS genes expression, lower migration capacity in vitro and reduced homing to the bone marrow in vivo. Recovery of sleep after sleep deprivation restored the reconstitution potential of the HSCs. Taken together, this study provides insights into cellular and molecular mechanisms underlying the effects of sleep deprivation on HSCs, emphasizing the potentially critical role of donor sleep in the success of bone marrow transplantation.

Role of microRNA221 in regulating normal mammary epithelial hierarchy and breast cancer stem-like cells.

Increasing evidence suggests that lineage specific subpopulations and stem-like cells exist in normal and malignant breast tissues. Epigenetic mechanisms maintaining this hierarchical homeostasis remain to be investigated. In this study, we found the level of microRNA221 (miR-221) was higher in stem-like and myoepithelial cells than in luminal cells isolated from normal and malignant breast tissue. In normal breast cells, over-expression of miR-221 generated more myoepithelial cells whereas knock-down of miR-221 increased luminal cells. Over-expression of miR-221 stimulated stem-like cells in luminal type of cancer and the miR-221 level was correlated with clinical outcome in breast cancer patients. Epithelial-mesenchymal transition (EMT) was induced by overexpression of miR-221 in normal and breast cancer cells. The EMT related gene ATXN1 was found to be a miR-221 target gene regulating breast cell hierarchy. In conclusion, we propose that miR-221 contributes to lineage homeostasis of normal and malignant breast epithelium.

MicroRNA100 inhibits self-renewal of breast cancer stem-like cells and breast tumor development.

miRNAs are essential for self-renewal and differentiation of normal and malignant stem cells by regulating the expression of key stem cell regulatory genes. Here, we report evidence implicating the miR100 in self-renewal of cancer stem-like cells (CSC). We found that miR100 expression levels relate to the cellular differentiation state, with lowest expression in cells displaying stem cell markers. Utilizing a tetracycline-inducible lentivirus to elevate expression of miR100 in human cells, we found that increasing miR100 levels decreased the production of breast CSCs. This effect was correlated with an inhibition of cancer cell proliferation in vitro and in mouse tumor xenografts due to attenuated expression of the CSC regulatory genes SMARCA5, SMARCD1, and BMPR2. Furthermore, miR100 induction in breast CSCs immediately upon their orthotopic implantation or intracardiac injection completely blocked tumor growth and metastasis formation. Clinically, we observed a significant association between miR100 expression in breast cancer specimens and patient survival. Our results suggest that miR100 is required to direct CSC self-renewal and differentiation.

Meningitis por Streptococcus pneumoniae en paciente pediátrico previamente inmunizado: reporte de un caso / Streptococcus pneumoniae meningitis in a previously immunized pediatric patient: report of a case

La meningitis bacteriana constituye una importante causa de morbimortalidad en el mundo y, a pesar de que la incidencia se ha reducido en los años posteriores a la inclusión de la vacuna antineumocócica en los calendarios de inmunizaciones, no se ha podido evitar el surgimiento de cepas emergentes. Presentamos el caso de una paciente de 5 años con inmunizaciones completas para la edad, con un cuadro clínico sugerente de meningoencefalitis, cuya evolución (con gran compromiso sistémico y pobre respuesta al tratamiento) nos hizo sospechar de la presencia de cepas emergentes y/o resistencia antimicrobiana, en el planteamiento de interrogantes respecto a estados de inmunodeficiencia o respuesta inadecuada a la vacunación, el impacto que realmente tiene la vacuna en nuestro país y la necesidad de realizar una más stricta vigilancia epidemiológica para la identificación de serotipos emergentes

Bacterial meningitis is an important cause of morbidity and mortality all over the world; and, in spite of a reduction in its incidence because of the introduction of an anti-pneumococcal vaccine in the immunization programs in many places, the occurrence of emerging strains has not been stopped. We present the case of a 5-year old girl with complete immunizations for her age, with a clinical condition suggesting meningoencephalitis, whose progress and outcome (significant systemic involvement and poor response to therapy) lead us to think in the possibility of emerging strains and/or resistance to antibacterial agents, and also to ask ourselves about an underlying immune deficiency or inadequate response to vaccination, the real impact of the vaccine in our country, and the need for performing more stringent epidemiological vigilance in order to identify emerging serotypes

A role for microRNAs in maintenance of mouse mammary epithelial progenitor cells.

microRNA (miRNA) expression profiles are often characteristic of specific cell types. The mouse mammary epithelial cell line, Comma-Dbeta, contains a population of self-renewing progenitor cells that can reconstitute the mammary gland. We purified this population and determined its miRNA signature. Several microRNAs, including miR-205 and miR-22, are highly expressed in mammary progenitor cells, while others, including let-7 and miR-93, are depleted. Let-7 sensors can be used to prospectively enrich self-renewing populations, and enforced let-7 expression induces loss of self-renewing cells from mixed cultures.

Características clínico epidemiológicas y pertinencia de la referencia de los pacientes derivados para hospitalización al Servicio de Emergencia del Instituto Nacional de Salud del Niño durante el año 2013 / Clinical and epidemiological characteristics and relevance of transference of patients referred for hospitalization to the Emergency Service at the National Institute of Child Health in during the year 2013

Objetivos: Describir las características clínicas y epidemiológicas de los pacientes transferidos a la Unidad de Emergencia del Instituto de Salud del Niño para su hospitalización durante el año 2013 y evaluar la pertinencia de su referencia. Material y Métodos: Diseño: Descriptivo. Prospectivo. Población: Pacientes menores de 18 años referidos para hospitalización a la Emergencia del INSN entre el 01 de Enero y el 31 de diciembre del 2013. Criterios de inclusión: Pacientes menores de 18 años referidos para hospitalización al INSN entre el 01 de Enero y el 31 de diciembre del 2013. Criterios de exclusión: Ninguno. Análisis de datos: Se utilizaron tablas de distribución de frecuencia, porcentajes, promedios, medidas de tendencia central, medianas, desviación estándar y tablas de 2x2; se utilizó SPSS v.15.0. Resultados: El número de pacientes estudiados fue 370, con edades entre 0.02 y 17.5 años. El motivo más frecuente de referencia fue manejo especializado (83.2 por ciento). El tiempo de estancia tuvo una media de 16.2 días. El 94 por ciento fueron referidos de centros nivel II la ecocardiografía fue el procedimiento diagnóstico más frecuente; 243 pacientes no tuvieron procedimiento diagnóstico alguno. 42.9 por ciento de referencias al servicio de emergencia fueron pertinentes. Conclusiones: El principal motivo de referencia fue necesidad de manejo especializado. No se especificó tipo de manejo, especialidad o procedimiento que requerían los pacientes. El 3 por ciento no consignó motivo de referencia. Más del 50 por ciento no requirieron procedimientos diagnósticos especializados. El 47 por ciento no requirió procedimientos terapéuticos especializados...

Objectives: To describe the clinical and epidemiological characteristics of patients transferred to the Emergency Unit of the Institute of Child Health for hospitalization during 2013 and assess the relevance al your reference. Material and Methods: Design: Descriptive, prospective. Population: Patients under 18 years old referred to the Emergency hospital lNSN between January and December, 2013. Inclusion criteria: Patients under age 18 referred for hospitalization to INSN between January, 1 and December, 31, 2013. Exclusion criteria: None. Data Analysis: Frequency distribution tables, percentages, averages. Measures of central tendency, medians, standard deviation and 2x2 tables were used: SPSS was used v.15.0. Results: The number of patients studied was 370. With ages between 0.02 and 17.5 years old. The most common reason was specialized management (83.2 per cent). The length of stay had a mean of 16.2 days. 94 per cent were referred to level II centers; Echocardiography was the most common diagnostic procedure; 243 patients did not have any diagnostic procedure. Also, 42.9 per cent of the references were relevant for emergency service. Conclusions: The main reason for the referral was need for specialized management. No type of management, specialty or procedure requiring patients was specified. Over 50 per cent did not require specialized diagnostic procedures. 47 per cent did not require specialized therapeutic procedures...