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Esophageal squamous cell carcinoma (ESCC), the major histologic subtype of esophageal cancer, is a devastating disease characterized by distinctly high incidences and mortality rates. However, there remains limited understanding of molecular events leading to development and progression of the disease, which are of paramount importance to defining biomarkers for diagnosis, prognosis, and personalized treatment. By high-throughout transcriptome sequence profiling of nontumor and ESCC clinical samples, we identified a subset of significantly differentially expressed genes involved in integrin signaling. The Rab25 gene implicated in endocytic recycling of integrins was the only gene in this group significantly downregulated, and its downregulation was confirmed as a frequent event in a second larger cohort of ESCC tumor specimens by quantitative real-time PCR and immunohistochemical analyses. Reduced expression of Rab25 correlated with decreased overall survival and was also documented in ESCC cell lines compared with pooled normal tissues. Demethylation treatment and bisulfite genomic sequencing analyses revealed that downregulation of Rab25 expression in both ESCC cell lines and clinical samples was associated with promoter hypermethylation. Functional studies using lentiviral-based overexpression and suppression systems lent direct support of Rab25 to function as an important tumor suppressor with both anti-invasive and -angiogenic abilities, through a deregulated FAK--Raf--MEK1/2--ERK signaling pathway. Further characterization of Rab25 may provide a prognostic biomarker for ESCC outcome prediction and a novel therapeutic target in ESCC treatment. [ABSTRACT FROM AUTHOR]

Esophageal squamous cell carcinoma (ESCC), the major histologic subtype of esophageal cancer, is a devastating disease characterized by distinctly high incidences and mortality rates. However, there remains limited understanding of molecular events leading to development and progression of the disease, which are of paramount importance to defining biomarkers for diagnosis, prognosis, and personalized treatment. By high-throughout transcriptome sequence profiling of nontumor and ESCC clinical samples, we identified a subset of significantly differentially expressed genes involved in integrin signaling. The Rab25 gene implicated in endocytic recycling of integrins was the only gene in this group significantly downregulated, and its downregulation was confirmed as a frequent event in a second larger cohort of ESCC tumor specimens by quantitative real-time PCR and immunohistochemical analyses. Reduced expression of Rab25 correlated with decreased overall survival and was also documented in ESCC cell lines compared with pooled normal tissues. Demethylation treatment and bisulfite genomic sequencing analyses revealed that downregulation of Rab25 expression in both ESCC cell lines and clinical samples was associated with promoter hypermethylation. Functional studies using lentiviral-based overexpression and suppression systems lent direct support of Rab25 to function as an important tumor suppressor with both anti-invasive and -angiogenic abilities, through a deregulated FAK-Raf-MEK1/2-ERK signaling pathway. Further characterization of Rab25 may provide a prognostic biomarker for ESCC outcome prediction and a novel therapeutic target in ESCC treatment., (©2012 AACR.)

Background & Aims: Esophageal squamous cell carcinoma (ESCC) is the most commonly observed histologic subtype of esophageal cancer. ESCC is believed to develop via accumulation of numerous genetic alterations, including inactivation of tumor suppressor genes and activation of oncogenes. We searched for transcripts that were altered in human ESCC samples compared with nontumor tissues., Methods: We performed integrative transcriptome sequencing (RNA-Seq) analysis using ESCC samples from 3 patients and adjacent nontumor tissues to identify transcripts that were altered in ESCC tissue. We performed molecular and functional studies of the transcripts identified and investigated the mechanisms of alteration., Results: We identified protein tyrosine kinase 6 (PTK6) as a transcript that was significantly down-regulated in ESCC tissues and cell lines compared with nontumor tissues or immortalized normal esophageal cell lines. The promoter of the PTK6 gene was inactivated in ESCC tissues at least in part via hypermethylation and histone deacetylation. Knockdown of PTK6 in KYSE30 ESCC cells using small hairpin RNAs increased their ability to form foci, migrate, and invade extracellular matrix in culture and form tumors in nude mice. Overexpression of PTK6 in these cells reduced their proliferation in culture and tumor formation in mice. PTK6 reduced phosphorylation of Akt and glycogen synthase kinase (GSK)3β, leading to activation of β-catenin., Conclusions: PTK6 was identified as a transcript that is down-regulated in human ESCC tissues via epigenetic modification at the PTK6 locus. Its product appears to regulate cell proliferation by reducing phosphorylation of Akt and GSK3β, leading to activation of β-catenin. Reduced levels of PTK6 promote growth of xenograft tumors in mice; it might be developed as a marker of ESCC., (Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Few studies have compared CTX-M encoding plasmids identified in different ecological sources. This study aimed to analyze and compare the molecular epidemiology of plasmids encoding CTX-M-14 among strains from humans and animals. The CTX-M-14 encoding plasmids in 160 Escherichia coli isolates from animal faecal (14 pigs, 16 chickens, 12 cats, 8 cattle, 5 dogs and 3 rodents), human faecal (45 adults and 20 children) and human urine (37 adults) sources in 2002-2010 were characterized by molecular methods. The replicon types of the CTX-M-14 encoding plasmids were IncFII (n=61), I1-Iγ (n=24), other F types (n=23), B/O (n=10), K (n=6), N (n=3), A/C (n=1), HI1 (n=1), HI2 (n=1) and nontypeable (n=30). The genetic environment, ISEcp1 -bla(CTX-M-14) - IS903 was found in 89.7% (52/58), 87.7% (57/65) and 86.5% (32/37) of the animal faecal, human faecal and human urine isolates, respectively. Subtyping of the 61 IncFII incompatibility group plasmids by replicon sequence typing, plasmid PCR-restriction fragment length polymorphism and marker genes (yac, malB, eitA/eitC and parB/A) profiles showed that 31% (18/58), 30.6% (20/65) and 37.8% (14/37) of the plasmids originating from animal faecal, human faecal and human urine isolates, respectively, were pHK01-like. These 52 pHK01-like plasmids originated from diverse human (20 faecal isolates from 2002, 2007 to 2008, 14 urinary isolates from 2004) and animal (all faecal, 1 cattle, 1 chicken, 5 pigs, 9 cats, 1 dog, 1 rodent from 2008 to 2010) sources. In conclusion, this study highlights the importance of the IncFII group, pHK01-like plasmids in the dissemination of CTX-M-14 among isolates from diverse sources., (Copyright © 2012 Elsevier B.V. All rights reserved.)