BackgroundSessile serrated adenomas/polyps (SSA/Ps) may account for 20–30% of colon cancers. Although large SSA/Ps are generally recognized phenotypically, small (<1 cm) or dysplastic SSA/Ps are difficult to differentiate from hyperplastic or small adenomatous polyps by endoscopy and histopathology. Our aim was to define the comprehensive gene expression phenotype of SSA/Ps to better define this cancer precursor.ResultsRNA sequencing was performed on 5′ capped RNA from seven SSA/Ps collected from patients with the serrated polyposis syndrome (SPS) versus eight controls. Highly expressed genes were analyzed by qPCR in additional SSA/Ps, adenomas and controls. The cellular localization and level of gene products were examined by immunohistochemistry in syndromic and sporadic SSA/Ps, adenomatous and hyperplastic polyps and controls. We identified 1,294 differentially expressed annotated genes, with 106 increased ≥10-fold, in SSA/Ps compared to controls. Comparing these genes with an array dataset for adenomatous polyps identified 30 protein coding genes uniquely expressed ≥10-fold in SSA/Ps. Biological pathways altered in SSA/Ps included mucosal integrity, cell adhesion, and cell development. Marked increased expression of MUC17, the cell junction protein genes VSIG1 and GJB5, and the antiapoptotic gene REG4 were found in SSA/Ps, relative to controls and adenomas, were verified by qPCR analysis of additional SSA/Ps (n = 21) and adenomas (n = 10). Immunohistochemical staining of syndromic (n≥11) and sporadic SSA/Ps (n≥17), adenomatous (n≥13) and hyperplastic (n≥10) polyps plus controls (n≥16) identified unique expression patterns for VSIG1 and MUC17 in SSA/Ps.ConclusionA subset of genes and pathways are uniquely increased in SSA/Ps, compared to adenomatous polyps, thus supporting the concept that cancer develops by different pathways in these phenotypically distinct polyps with markedly different gene expression profiles. Immunostaining for a subset of these genes differentiates both syndromic and sporadic SSA/Ps from adenomatous and hyperplastic polyps.

SUMMARYSquamous cell carcinoma (SCC) of the lung is the second most common subtype of lung cancer. With limited treatment options, the 5-year survival rate of SCC is only 15%. Although genomic alterations in SCC have been characterized, identifying the alterations that drive SCC is critical for improving treatment strategies. Mouse models of SCC are currently limited. Using lentiviral delivery of Sox2 specifically to the mouse lung, we tested the ability of Sox2 to promote tumorigenesis in multiple tumor suppressor backgrounds. Expression of Sox2, frequently amplified in human SCC, specifically cooperates with loss of Lkb1 to promote squamous lung tumors. Mouse tumors exhibit characteristic histopathology and biomarker expression similar to human SCC. They also mimic human SCCs by activation of therapeutically relevant pathways including STAT and mTOR. This model may be utilized to test the contribution of additional driver alterations in SCC, as well as for preclinical drug discovery.

Halorespiration is a bacterial respiratory process in which haloorganic compounds act as terminal electron acceptors. This process is controlled at transcriptional level by CprK, a member of the ubiquitous CRP-FNR family. Here we present the crystal structures of oxidized CprK in presence of the ligand orthochlorophenolacetic acid and of reduced CprK in absence of this ligand. These structures reveal that highly specific binding of chlorinated, rather than the corresponding non-chlorinated, phenolic compounds in the NH 2 -terminal ␤-barrels causes reorientation of these domains with respect to the central ␣-helix at the dimer interface. Unexpectedly, the COOH-terminal DNA-binding domains dimerize in the non-DNA binding state. We postulate the ligand-induced conformational change allows formation of interdomain contacts that disrupt the DNA domain dimer interface and leads to repositioning of the helixturn-helix motifs. These structures provide a structural framework for further studies on transcriptional control by CRP-FNR homologs in general and of halorespiration regulation by CprK in particular.Past and present industrial and agricultural activities have led to the ever increasing presence of haloorganic compounds such as chlorophenols and chlorinated ethenes in the environment (1). Due to both toxicity and recalcitrant nature, increasing amounts of these xenobiotics threaten the integrity of the environment and human health (2). In recent years, it has emerged that several haloorganic compounds are also naturally produced (3) and that several species of strictly anaerobic bacteria are able to conserve energy via the reductive dehalogenation of these compounds by respiratory metabolism (4, 5). In view of their favorable degrading capacities, e.g. high dehalogenation rate and low residual concentration of the contaminant, it has been anticipated that halorespiring microorganisms should be of utmost significance for efficient biological remediation of halogenated hydrocarbons in anoxic environments (6, 7). The versatile, strictly anaerobic Gram-positive bacterium Desulfitobacterium dehalogenans and the closely related Desulfitobacterium hafniense have the capacity of degrading ortho-chlorophenol. Both have been used as model organisms in halorespiration studies, representing one of the most significant groups of halorespiring isolates (8). In these organisms, proteins involved in halorespiration are encoded by the cpr (chlorophenol reductive dehalogenase) operon, of which multiple copies are present within the genome. This potentially allows for reductive dehalogenation of a wide range of haloorganic compounds by the use of a series of paralogous enzymes (9).The cpr operon is transcriptionally regulated by CprK, a member of the CRP-FNR family of regulators that is ubiquitous in bacteria (10). Recent in vivo and in vitro studies reveal that CprK binds 3-chloro-4-hydroxyphenylacetate (CHPA) 2 with micromolar affinity promoting a tight interaction with a specific DNA sequence in the promoter region of the cprencod...

Desulfomonile, Desulfitobacterium, and Dehalobacter are anaerobic microbes that can derive energy from the reductive dehalogenation of chlorinated organic compounds, many of which are environmental pollutants. There is very little information about how anaerobic dehalorespiration is regulated. An open reading frame within the Desulfitobacterium dehalogenans chlorophenol reductase (cpr) gene cluster (cprK) was proposed to be a transcriptional regulatory protein (Smidt, H., van Leest, M., van der Oost, J., and deVos, W. M. (2000) J. Bacteriol. 182, 5683-5691). We have cloned, actively overexpressed in Escherichia coli, and purified to homogeneity the D. dehalogenans CprK. The results of electrophoretic mobility shift assays, DNA footprinting studies, and promoter-lac fusion experiments indicate that CprK is a transcriptional activator of the cpr gene cluster. CprK binds 3-chloro-4-hydroxyphenylacetate (CHPA) with high affinity (K d ‫؍‬ 3.5 M, determined by isothermal titration calorimetry), which promotes its specific interaction with a DNA sequence (TTAAT-N4-ACTAA) located upstream of the ؊35 and ؊10 promoter regions of several cpr genes and activates transcription of these genes. Binding to the upstream "box" sequence increases the affinity of CprK for CHPA by ϳ10-fold (K d ‫؍‬ 0.4 M, determined by electrophoretic mobility shift assays). Chlorophenylacetate, which lacks the ortho-hydroxy group, and hydroxyphenylacetate, lacking the chlorine group, do not activate transcription or promote DNA binding, even at millimolar concentrations, at least 1000-fold higher than the K d value for CHPA. Lacking metals, CprK is oxygen-sensitive. Oxidation by diamide, which converts thiols to the disulfide, inactivates CprK, and reduction of the oxidized protein by dithiothreitol fully restores DNA binding, indicating that CprK is redox-regulated and is active only when reduced. This is the first reported characterization of a transcriptional regulator of anaerobic dehalorespiration.