CD44 promotes Kras-dependent lung adenocarcinoma.

Kras-induced non-small-cell lung adenocarcinoma is the major subtype of lung cancers and is associated with poor prognosis. Using a lung cancer mouse model that expresses a cre-mediated KrasG12D mutant, we identified a critical role for the cell surface molecule CD44 in mediating cell proliferation downstream of oncogenic Kras signaling. The deletion of CD44 attenuates lung adenocarcinoma formation and prolongs the survival of these mice. Mechanistically, CD44 is required for the activation of Kras-mediated signaling through the mitogen-activated protein kinase (MAPK) pathway and thus promotes tumor cell proliferation. Together, these results reveal an unrecognized role for CD44 in oncogenic Kras-induced lung adenocarcinoma and suggest that targeting CD44 could be an effective strategy for halting Kras-dependent carcinomas.

Mouse models of human non-small-cell lung cancer: raising the bar.

Lung cancer is a devastating disease that presents a challenge to basic research to provide new steps toward therapeutic advances. The cell-type-specific responses to oncogenic mutations that initiate and regulate lung cancer remain poorly defined. A better understanding of the relevant signaling pathways and mechanisms that control therapeutic outcome could also provide new insight. Improved conditional mouse models are now available as tools to improve the understanding of the cellular and molecular origins of adenocarcinoma. These models have already proven their utility in proof-of-principle experiments with new technologies including genomics and imaging. Integrated thinking to apply technological advances while using the appropriate mouse model is likely to facilitate discoveries that will significantly improve lung cancer detection and intervention.

[Advances in the molecular diagnosis of infectious and parasitic diseases]. / Avances en el diagnóstico molecular de las enfermedades infecciosas y parasitarias.

During the last decade molecular diagnostic techniques have moved from the research laboratory into the clinical microbiology laboratory. The application of molecular biology for the diagnosis of infections and parasitic diseases by the detection of nucleic acids has steadily grown, and it is very probably that, while they may not displace the traditional diagnostic laboratory, they will be common place in the not to distant future. A detailed description of the principal molecular diagnostic techniques that are currently being used or that have a potential use for the diagnosis, evaluation of disease progression or response to therapy of selected infectious and parasitic diseases, is presented. Emphasis is placed on the rational use of these techniques in regional reference laboratories or highly specialized hospitals; the importance of selecting and implanting those diagnostic techniques with the highest cost-benefit ratio; and finally, the need to train human resources which are highly qualified in the theory and practice of molecular biology.

[The usefulness of the polymerase chain reaction (PCR) in research and clinical diagnosis in pediatrics]. / Utilidad de la reacción en cadena con polimerasa (PCR) en la investigación y el diagnóstico clinico en pediatría.

Recent advances in molecular biology for the first time make possible the widespread application of this science for the diagnosis and clinical investigation of pediatric disease. One very important discovery has been the development of the polymerase chain reaction. This technique allows for the exponential amplification of specific DNA sequences producing quantities sufficient for the molecular diagnosis of a wide variety of diseases. We review some of the fundamental aspects of this technique as well as some of its most promising applications in the field of pediatrics.

Subcellular fractionation of prohormone processing products in the bag cell neurons.

Multiple biologically active peptides arising from a common prohormone are sorted into distinct classes of dense core vesicles within the bag cell neurons of Aplysia californica. In this study, pulse-chase analysis, combined with subcellular fractionation on Percoll gradients, are used to define the location of the prohormone processing events within the secretory pathway. Initial cleavage of the prohormone occurs in a light cellular compartment associated with the Golgi apparatus. The amino-terminal processing intermediate then accumulates in a denser compartment containing small dense cores enclosed in membranous sacs, as well as larger immature vesicles. After 4 h, amino-terminal products are found primarily in a much denser compartment which consists of large and small dense core vesicles. These large and small vesicles can be separated from each other using Percoll gradient centrifugation and are found to be enriched in amino- and carboxy-terminal products, respectively. Lastly, membrane association experiments suggest differential binding to membranes, or integral membrane proteins, as a possible mechanism for sorting of amino- and carboxy-terminal products.

Dale's hypothesis revisited: different neuropeptides derived from a common prohormone are targeted to different processes.

In the bag cells of Aplysia californica, the prohormone of egg-laying hormone is processed by means of endoproteolytic cleavage into two sets of peptides. The amino-terminal region of the prohormone gives rise to the bag cell peptides (alpha, beta, and gamma). These serve an autocrine function; they are autoexcitatory on the bag cells and also act locally to alter the firing patterns of neurons in the abdominal ganglion. The carboxyl-terminal portion of the prohormone gives rise to the egg-laying hormone. This peptide acts as a hormone on nearby neurons and by means of the circulation on peripheral tissues to bring about egg-laying. We have previously reported that the first cleavage of the prohormone, which occurs in the trans-Golgi network, results in two intermediates that are sorted into distinct vesicle classes prior to further processing. Here we show that these distinct vesicles are localized to separate processes, thus spatially segregating autocrine and hormonal release sites. The findings of segregation indicate that neurons need not always release the same set of chemical messengers from all of their endings.

Modulation of ionic currents in Aplysia motor neuron B15 by serotonin, neuropeptides, and second messengers.

Both 5-HT and the 9 amino acid neuropeptide SCPb modulate 3 ionic currents in B15, enhancing a voltage-dependent inward sodium current, decreasing an outward potassium current and increasing an inward rectifying potassium current. In contrast, FMRFamide decreases a voltage-dependent inward sodium current and increases an outward potassium current. We have also investigated the roles of several second-messenger systems that may be mediating the effects of these modulators. Bath application of membrane permeable analogs of cAMP enhance the voltage-dependent inward sodium current and both 5-HT and SCPb increase cAMP levels in B15, suggesting that cAMP may be mediating part of the observed effects of these transmitters on B15. Experiments with phorbol ester, a protein kinase inhibitor, and a phospholipase inhibitor suggest that the phospholipase C/protein kinase C cascade may decrease an outward potassium current. Thus, 5-HT and SCPb may activate multiple second-messenger systems to modulate 3 ionic currents in B15. Additional studies suggest that a cascade involving arachidonic acid may be involved in mediating part of the FMRFamide responses in B15. These studies are beginning to define molecular mechanisms whereby a neuron differentially modulates multiple ionic currents in response to distinct chemical messengers.