We have sequenced the genomes of 110 small cell lung cancers (SCLC), one of the deadliest human cancers. In nearly all the tumours analysed we found bi-allelic inactivation of TP53 and RB1, sometimes by complex genomic rearrangements. Two tumours with wild-type RB1 had evidence of chromothripsis leading to overexpression of cyclin D1 (encoded by the CCND1 gene), revealing an alternative mechanism of Rb1 deregulation. Thus, loss of the tumour suppressors TP53 and RB1 is obligatory in SCLC. We discovered somatic genomic rearrangements of TP73 that create an oncogenic version of this gene, TP73Δex2/3. In rare cases, SCLC tumours exhibited kinase gene mutations, providing a possible therapeutic opportunity for individual patients. Finally, we observed inactivating mutations in NOTCH family genes in 25% of human SCLC. Accordingly, activation of Notch signalling in a pre-clinical SCLC mouse model strikingly reduced the number of tumours and extended the survival of the mutant mice. Furthermore, neuroendocrine gene expression was abrogated by Notch activity in SCLC cells. This first comprehensive study of somatic genome alterations in SCLC uncovers several key biological processes and identifies candidate therapeutic targets in this highly lethal form of cancer.

Goblet cell hyperplasia and mucous hypersecretion contribute to the pathogenesis of chronic pulmonary diseases including cystic fibrosis, asthma, and chronic obstructive pulmonary disease. In the present work, mouse SAM pointed domain-containing ETS transcription factor (SPDEF) mRNA and protein were detected in subsets of epithelial cells lining the trachea, bronchi, and tracheal glands. SPDEF interacted with the C-terminal domain of thyroid transcription factor 1, activating transcription of genes expressed selectively in airway epithelial cells, including Sftpa, Scgb1a1, Foxj1, and Sox17. Expression of Spdef in the respiratory epithelium of adult transgenic mice caused goblet cell hyperplasia, inducing both acidic and neutral mucins in vivo, and stainined for both acidic and neutral mucins in vivo. SPDEF expression was increased at sites of goblet cell hyperplasia caused by IL-13 and dust mite allergen in a process that was dependent upon STAT-6. SPDEF was induced following intratracheal allergen exposure and after Th2 cytokine stimulation and was sufficient to cause goblet cell differentiation of Clara cells in vivo.

Small-cell lung carcinoma (SCLC) is a neuroendocrine subtype of lung cancer. Although SCLC patients often initially respond to therapy, tumors nearly always recur, resulting in a 5-year survival rate of less than 10%. A mouse model has been developed based on the fact that the RB and p53 tumor suppressor genes are mutated in more than 90% of human SCLCs. Emerging evidence in patients and mouse models suggests that p130, a gene related to RB, may act as a tumor suppressor in SCLC cells. To test this idea, we used conditional mutant mice to delete p130 in combination with Rb and p53 in adult lung epithelial cells. We found that loss of p130 resulted in increased proliferation and significant acceleration of SCLC development in this triple-knockout mouse model. The histopathologic features of the triple-mutant mouse tumors closely resembled that of human SCLC. Genome-wide expression profiling experiments further showed that Rb/p53/p130-mutant mouse tumors were similar to human SCLC. These findings indicate that p130 plays a key tumor suppressor role in SCLC. Rb/p53/p130-mutant mice provide a novel preclinical mouse model to identify novel therapeutic targets against SCLC. Cancer Res; 70(10); 3877-83. ©2010 AACR.

Since the lung is repeatedly subjected to injury by pathogens and toxicants, maintenance of pulmonary homeostasis requires rapid repair of its epithelial surfaces. Ciliated bronchiolar epithelial cells, previously considered as terminally differentiated, underwent squamous cell metaplasia within hours after bronchiolar injury with naphthalene. Expression of transcription factors active in morphogenesis and differentiation of the embryonic lung, including ␤-catenin, Foxa2, Foxj1, and Sox family members (Sox17 and Sox2), was dynamically regulated during repair and redifferentiation of the bronchiolar epithelium after naphthalene injury. Squamous cells derived from ciliated cells spread beneath injured Clara cells within 6-12 h after injury, maintaining the integrity of the epithelium. Dynamic changes in cell shape and gene expression, indicating cell plasticity, accompanied the transition from squamous to cuboidal to columnar cell types as differentiation-specific cell markers typical of the mature airway were restored. Similar dynamic changes in the expression of these transcription factors occurred in ciliated and Clara cells during regeneration of the lung after unilateral pneumonectomy. Taken together, these findings demonstrate that ciliated epithelial cells spread and transdifferentiate into distinct epithelial cell types to repair the airway epithelium. Keywords: naphthalene; lung injury; transcription; pneumonectomy; bronchioleThe respiratory tract has an extensive cell surface that is directly exposed to inhaled gases, particles, and pathogens. A complex epithelium lines the airways, mediating gas exchange, mucociliary clearance, host defense, and surfactant homeostasis to maintain lung sterility and stability. While the adult lung is not mitotically active, respiratory epithelial cells can proliferate rapidly after injury to maintain lung structure and function.Models in which relatively rare subsets of nonciliated respiratory epithelial cells located in unique environments play critical roles in lung repair have been proposed (1-5). Krause and coworkers have provided evidence that extrapulmonary, bone marrow-derived cells migrate to the lung, contributing to the repair of the respiratory epithelium after injury (6). From a stochastic view, however, models in which rare progenitor cells account for the rapid and extensive repair of the lung are not compatible with the observed short period of proliferation and rapid restoration of epithelial surfaces that is observed after catastrophic injury caused by infection or toxicants. Rather, the remarkable repair capacity of the lung is more consistent with a model in (Received in original form August 30, 2005 and in final form September 30, 2005) This study was supported by NIH HL56387 (J.A.W.) and HL61646 (J