No abstract

Malignancy involving the pleura is the third leading cause of pleural effusions, with an annual incidence of Ͼ 150,000 cases in the United States (1, 2). Adenocarcinomas account for ‫ف‬ 70% of all malignant pleural effusions (MPEs), with lung adenocarcinomas being the most frequent underlying malignancy (3). The appearance of a MPE is an ominous prognostic sign for patients with cancer, because the presence of the MPE indicates that the tumor is incurable by surgery and life expectancy is short (1). In addition, the presence of the pleural effusion can cause dyspnea that severely compromises the quality of the patient's life (4, 5). Pleurodesis, the iatrogenic induction of pleural fibrosis to obliterate the pleural cavity, is commonly used to prevent symptomatic re-accumulation of pleural effusions; however, this therapy is often ineffective and is associated with significant It is generally believed that disruption of the endothelialmesothelial barrier, increased capillary permeability, tumorinduced angiogenesis, and lymphatic obstruction are responsible for the exudation of increased amounts of fluid into the pleural cavity (1, 7). However, the specific mechanisms underlying pleural fluid accumulation are poorly defined because studies of MPE pathogenesis are limited by a lack of animal models that reproduce the pathobiology of human MPE. Although mouse models that require immunocompromised mice for propagation of human cancer cells mice have provided insights into the biological behavior of tumor cells in the pleural cavity (7-9), these models are not ideal because the host is immunocompromised, and, therefore, the host immune response is attenuated or missing. The immune response against tumor may be an important component in the development of MPE because host inflammatory cells may contribute to or regulate the production of mediators that affect pathogenesis (10).Nuclear factor (NF)-B is a ubiquitous family of transcription regulatory proteins that affects a variety of cellular functions and influences tumor biology and host-tumor interactions. NF-B is activated by a number of tumor-promoting agents and is involved in the production of proteins that enhance cell survival and proliferation (11). High basal NF-B activation is present in lung adenocarcinoma cells and human lung cancer, and inhibition of NF-B sensitizes tumor cells to apoptosis and the effects of chemotherapeutic agents (11)(12)(13)(14)(15).Lewis lung cancer (LLC) cells are derived from a spontaneously arising lung adenocarcinoma in C57B/6 mice. These cells are characterized by short doubling times in vitro and in vivo and aggressive biological behavior. They can be propagated in wild-type C57B/6 mice, giving rise to lung adenocarcinomas (16)(17)(18). In these studies, we have developed and characterized a new murine model of MPE after instillation of lung adenocarcinoma cells in the pleural space of immunocompetent mice. We used this model to investigate whether the NF-B pathway in tumor cells is linked to MPE formation and progression of pl...

Conditional gene knockout animals are valuable tools for studying the mechanisms underlying cell and developmental biology. We developed a conditional knockout strategy by spatiotemporally manipulating the expression of an RNA-guided DNA endonuclease, CRISPR-Cas9, in Caenorhabditis elegans somatic cell lineages. We showed that this somatic CRISPR-Cas9 technology provides a quick and efficient approach to generate conditional knockouts in various cell types at different developmental stages. Furthermore, we demonstrated that this method outperforms our recently developed somatic TALEN technique and enables the one-step generation of multiple conditional knockouts. By combining these techniques with live-cell imaging, we showed that an essential embryonic gene, Coronin, which is associated with human neurobehavioral dysfunction, regulates actin organization and cell morphology during C. elegans postembryonic neuroblast migration and neuritogenesis. We propose that the somatic CRISPR-Cas9 platform is uniquely suited for conditional gene editing-based biomedical research.