Embryonic mammary signature subsets are activated in Brca1-/- and basal-like breast cancers

Introduction: Cancer is often suggested to result from development gone awry. Links between normal embryonic development and cancer biology have been postulated, but no defined genetic basis has been established. We recently published the first transcriptomic analysis of embryonic mammary cell populations. Embryonic mammary epithelial cells are an immature progenitor cell population, lacking differentiation markers, which is reflected in their very distinct genetic profiles when compared with those of their postnatal descendents. Methods: We defined an embryonic mammary epithelial signature that incorporates the most highly expressed genes from embryonic mammary epithelium when compared with the postnatal mammary epithelial cells. We looked for activation of the embryonic mammary epithelial signature in mouse mammary tumors that formed in mice in which Brca1 had been conditionally deleted from the mammary epithelium and in human breast cancers to determine whether any genetic links exist between embryonic mammary cells and breast cancers. Results: Small subsets of the embryonic mammary epithelial signature were consistently activated in mouse Brca1-/- tumors and human basal-like breast cancers, which encoded predominantly transcriptional regulators, cellcycle, and actin cytoskeleton components. Other embryonic gene subsets were found activated in non-basal-like tumor subtypes and repressed in basal-like tumors, including regulators of neuronal differentiation, transcription, and cell biosynthesis. Several embryonic genes showed significant upregulation in estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and/or grade 3 breast cancers. Among them, the transcription factor, SOX11, a progenitor cell and lineage regulator of nonmammary cell types, is found highly expressed in some Brca1-/- mammary tumors. By using RNA interference to silence SOX11 expression in breast cancer cells, we found evidence that SOX11 regulates breast cancer cell proliferation and cell survival. Conclusions: Specific subsets of embryonic mammary genes, rather than the entire embryonic development transcriptomic program, are activated in tumorigenesis. Genes involved in embryonic mammary development are consistently upregulated in some breast cancers and warrant further investigation, potentially in drug-discovery research endeavors

Función de la proteína mediadora de respuesta a colapsinas 2 (CRMP-2) en cáncer de pulmón no microcítico

Los microtúbulos desarrollan una función importante en procesos celulares tan cruciales como la división celular, la adhesión a sustrato, la migración o el transporte de proteínas y orgánulos. Durante la mitosis, los microtúbulos constituyen el huso mitótico. Debido a su intervención en la división celular, los microtúbulos son dianas moleculares de primera magnitud en las terapias frente al cáncer. En los últimos años se ha descubierto que es esencial la colaboración de las Proteínas Asociadas a Microtúbulos (MAPs) para que los microtúbulos puedan realizar su función correctamente. La familia de las proteínas de respuesta a colapsina o CRMPs constituye un ejemplo de este tipo de moléculas. La proteína mediadora de respuesta a colapsina tipo 2 (CRMP-2) es una proteína adaptadora de tubulina que interacciona con los heterodímeros de tubulina para unirlos a los microtúbulos crecientes, de modo dependiente de su estado de fosforilación. A pesar de su interacción con tubulina, CRMP-2 ha sido descrita fundamentalmente en tejido nervioso. Pensamos que debido a su participación en la dinámica de los microtúbulos, CRMP-2 puede presentar una expresión o regulación diferencial en las células transformadas con respecto a células primarias y con ello contribuir a la progresión tumoral. En concreto en este estudio nos propusimos estudiar la función de CRMP-2 en el contexto de carcinoma pulmonar y nos planteamos los siguientes objetivos: 1- Estudiar la expresión de CRMP-2 en células primarias de epitelio bronquial, células inmortalizadas y células transformadas de pulmón y comparar los niveles de expresión y fosforilación de esta proteína en células normales y transformadas, así como su localización subcelular y co-localización con tubulina. 2- Analizar si las variaciones en el estado de fosforilación de CRMP-2 pueden contribuir a la adquisición de propiedades características de tumores agresivos: mayor proliferación y capacidad de migración. 3- Estudiar la participación de CRMP-2 en la mitosis y evaluar si las alteraciones en su grado de fosforilación afectan a la correcta división de las células tumorales

Función de la proteína mediadora de respuesta a colapsinas 2 (CRMP-2) en cáncer de pulmón no microcítico

Los microtúbulos desarrollan una función importante en procesos celulares tan cruciales como la división celular, la adhesión a sustrato, la migración o el transporte de proteínas y orgánulos. Durante la mitosis, los microtúbulos constituyen el huso mitótico. Debido a su intervención en la división celular, los microtúbulos son dianas moleculares de primera magnitud en las terapias frente al cáncer. En los últimos años se ha descubierto que es esencial la colaboración de las Proteínas Asociadas a Microtúbulos (MAPs) para que los microtúbulos puedan realizar su función correctamente. La familia de las proteínas de respuesta a colapsina o CRMPs constituye un ejemplo de este tipo de moléculas. La proteína mediadora de respuesta a colapsina tipo 2 (CRMP-2) es una proteína adaptadora de tubulina que interacciona con los heterodímeros de tubulina para unirlos a los microtúbulos crecientes, de modo dependiente de su estado de fosforilación. A pesar de su interacción con tubulina, CRMP-2 ha sido descrita fundamentalmente en tejido nervioso. Pensamos que debido a su participación en la dinámica de los microtúbulos, CRMP-2 puede presentar una expresión o regulación diferencial en las células transformadas con respecto a células primarias y con ello contribuir a la progresión tumoral. En concreto en este estudio nos propusimos estudiar la función de CRMP-2 en el contexto de carcinoma pulmonar y nos planteamos los siguientes objetivos: 1- Estudiar la expresión de CRMP-2 en células primarias de epitelio bronquial, células inmortalizadas y células transformadas de pulmón y comparar los niveles de expresión y fosforilación de esta proteína en células normales y transformadas, así como su localización subcelular y co-localización con tubulina. 2- Analizar si las variaciones en el estado de fosforilación de CRMP-2 pueden contribuir a la adquisición de propiedades características de tumores agresivos: mayor proliferación y capacidad de migración. 3- Estudiar la participación de CRMP-2 en la mitosis y evaluar si las alteraciones en su grado de fosforilación afectan a la correcta división de las células tumorales

Sox11 regulates mammary tumour-initiating and metastatic capacity in Brca1-deficient mouse mammary tumour cells

Little is known about the role of Sox11 in the regulation of mammary progenitor cells. Sox11 is expressed by mammary bud epithelial cells during embryonic mammary gland development and is not detected in mammary epithelial cells after birth. As Sox11 is an oncofetal gene, we investigated the effects of reducing Sox11 levels in embryonic mammary progenitor cells and found that Sox11 regulates proliferative state, stem cell activity and lineage marker expression. We also investigated the effect of reducing Sox11 levels in two transplantable Brca1-deficient oestrogen receptor-negative mouse mammary tumour cell lines, to assess whether Sox11 regulates similar functions in tumour progenitor cells. When Sox11 levels were reduced in one Brca1-deficient mammary tumour cell line that expressed both epithelial and mesenchymal markers, similar effects on proliferation, stem cell activity and expression of lineage markers to those seen in the embryonic mammary progenitor cells were observed. Orthotopic grafting of mammary tumour cells with reduced Sox11 levels led to alterations in tumour-initiating capacity, latency, expression of lineage markers and metastatic burden. Our results support a model in which tumours expressing higher levels of Sox11 have more stem and tumour-initiating cells, and are less proliferative, whereas tumours expressing lower levels of Sox11 become more proliferative and capable of morphogenetic/metastatic growth, similar to what occurs during embryonic mammary developmental progression

All-trans-retinoic acid inhibits collapsin response mediator protein-2 transcriptional activity during SH-SY5Y neuroblastoma cell differentiation

Neurons are highly polarized cells composed of two structurally and functionally distinct parts, the axon and the dendrite. The establishment of this asymmetric structure is a tightly regulated process. In fact, alterations in the proteins involved in the configuration of the microtubule lattice are frequent in neuro-oncologic diseases. One of these cytoplasmic mediators is the protein known as collapsin response mediator protein-2, which interacts with and promotes tubulin polymerization. In this study, we investigated collapsin response mediator protein-2 transcriptional regulation during all-trans-retinoic acid-induced differentiation of SH-SY5Y neuroblastoma cells. All-trans-retinoic acid is considered to be a potential preventive and therapeutic agent, and has been extensively used to differentiate neuroblastoma cells in vitro. Therefore, we first demonstrated that collapsin response mediator protein-2 mRNA levels are downregulated during the differentiation process. After completion of deletion construct analysis and mutagenesis and mobility shift assays, we concluded that collapsin response mediator protein-2 basal promoter activity is regulated by the transcription factors AP-2 and Pax-3, whereas E2F, Sp1 and NeuroD1 seem not to participate in its regulation. Furthermore, we finally established that reduced expression of collapsin response mediator protein-2 after all-trans-retinoic acid exposure is associated with impaired Pax-3 and AP-2 binding to their consensus sequences in the collapsin response mediator protein-2 promoter. Decreased attachment of AP-2 is a consequence of its accumulation in the cytoplasm. On the other hand, Pax-3 shows lower binding due to all-trans-retinoic acid-mediated transcriptional repression. Unraveling the molecular mechanisms behind the action of all-trans-retinoic acid on neuroblastoma cells may well offer new perspectives for its clinical application

A Sox2-Sox9 signalling axis maintains human breast luminal progenitor and breast cancer stem cells

Increased cancer stem cell content during development of resistance to tamoxifen in breast cancer is driven by multiple signals, including Sox2-dependent activation of Wnt signalling. Here, we show that Sox2 increases and estrogen reduces the expression of the transcription factor Sox9. Gain and loss of function assays indicate that Sox9 is implicated in the maintenance of human breast luminal progenitor cells. CRISPR/Cas knockout of Sox9 reduces growth of tamoxifen-resistant breast tumours in vivo. Mechanistically, Sox9 acts downstream of Sox2 to control luminal progenitor cell content and is required for expression of the cancer stem cell marker ALDH1A3 and Wnt signalling activity. Sox9 is elevated in breast cancer patients after endocrine therapy failure. This new regulatory axis highlights the relevance of SOX family transcription factors as potential therapeutic targets in breast cancer