The human BLM gene is a member of the Escherichia coli recQ helicase family, which includes the Saccharomyces cerevisiae SGS1 and human WRN genes. Defects in BLM are responsible for the human disease Bloom's syndrome, which is characterized in part by genomic instability and a high incidence of cancer. Here we describe the cloning of rad12 ؉ , which is the fission yeast homolog of BLM and is identical to the recently reported rhq1؉ gene. We showed that rad12 null cells are sensitive to DNA damage induced by UV light and ␥ radiation, as well as to the DNA synthesis inhibitor hydroxyurea. Overexpression of the wild-type rad12 ؉ gene also leads to sensitivity to these agents and to defects associated with the loss of the S-phase and G 2 -phase checkpoint control. We showed genetically and biochemically that rad12 ؉ acts upstream from rad9 ؉ , one of the fission yeast G 2 checkpoint control genes, in regulating exit from the S-phase checkpoint. The physical chromosome segregation defects seen in rad12 null cells combined with the checkpoint regulation defect seen in the rad12 ؉ overproducer implicate rad12 ؉ as a key coupler of chromosomal integrity with cell cycle progression.The fission yeast Schizosaccharomyces pombe undergoes a dose-dependent G 2 delay in response to DNA damage caused by radiation (1, 27). Cells remain arrested at this G 2 checkpoint while DNA damage is repaired, then enter mitosis and resume progression through the cell cycle. Six checkpoint rad genes have been identified in S. pombe: rad1 ϩ , rad3ϩ , rad26 ϩ , and hus1 ϩ (1, 2, 9, 27). Mutations in any of these genes result in almost identical phenotypes. The mutant strains are all sensitive to radiation and to agents which transiently inhibit DNA replication, and all lack the G 2 checkpoint, preventing mitotic entry in the presence of such damage (1, 2, 9, 27). While little is known about G 2 checkpoint genes in humans, homologs of S. pombe rad3 ϩ (4, 5) and rad9 ϩ (19) have recently been isolated. Recent studies have implicated cell cycle gene mutations in causing cancer. It is likely that mutations in genes regulating the G 1 and G 2 checkpoints also have the potential to increase cancer susceptibility.The phenomenon of genomic instability has been firmly established as a crucial step in the genesis of cancer (14,31,33). While genomic instability is seen as a step in the progression of cancer cells, there are also several genetic diseases that lead to genomic instability and, ultimately, to cancer. Among these diseases is the rare autosomal recessive disorder Bloom's syndrome (12). The defective gene in Bloom's syndrome, BLM, encodes a putative DNA helicase that is homologous to the Escherichia coli RecQ and Saccharomyces cerevisiae Sgs1 helicases (11,34). While the BLM and SGS1 proteins contain centrally located helicase domains that are homologous to RecQ, they are much larger than RecQ and show homology, both 5Ј and 3Ј, to the helicase core (26, 35, 37).We describe here the cloning of the fission yeast rad12 ϩ gene, which encodes a helic...

Lung cancer is currently the most frequent cause of cancer death in North America. Hepatocyte growth factor (HGF) and its receptor Met are frequently over-expressed in non-small-cell lung carcinomas (NSCLC), but their potential role in tumor progression is not clearly known. To assess the role of HGF/Met signaling in lung carcinomas, we have examined the expression, activation status, and function of Met in NSCLC cell lines (n = 7), established from primary tumors or pleural fluids of cancer patients. We observed Met expression in three NSCLC cell lines, two of which exhibited constitutive tyrosine-phosphorylation of Met, and Met kinase activity. In addition, the observed constitutive activation of Met was sustained under anchorage-independent conditions, and correlated with phosphatidyl inositol 3-kinase-dependent cell survival. Immunoreactive HGF-like protein was secreted by two Met-positive and two Met-negative NSCLC cell lines. However HGF activity, as determined by the ability to induce cell scattering and tyrosine-phosphorylation of Met in reporter cell lines, was detected in conditioned medium from only one Met-negative NSCLC cell line: none of the conditioned media from Met-expressing NSCLC cell lines showed detectable HGF activity. Thus, constitutive activation of Met in NSCLC cell lines may occur at least in part through intracrine, or HGF-independent mechanisms. Interestingly, additional paracrine stimulation with exogenous recombinant HGF was required for DNA synthesis and correlated with increased activation of ERK1/2 in all Met-positive NSCLC cell lines, regardless of the basal activation status of Met. These findings indicate that a medium level of constitutive activation of Met occurs in some NSCLC cell lines, and correlates with survival of detached carcinoma cells; whereas additional paracrine stimulation by recombinant HGF is required for DNA synthesis. Thus constitutive and paracrine activation of Met may provide complementary signals that promote survival and proliferation, respectively, during tumor progression of NSCLC.

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Little research has examined potential risk factors for direct versus indirect self-injury among adolescents. To address this limitation, 541 clinically referred adolescents were assessed using the interRAI Child and Youth Mental Health Assessment. Logistic regression analyses revealed that older females who experienced heightened depressive symptoms and neighborhood violence were at increased risk for direct self-injury, specifically nonsuicidal and suicidal self-injury. Additionally, adolescents who experienced higher levels of caregiver distress were at greater risk of suicidal self-injury. In contrast, older adolescents who experienced heightened aggressive behavior were at increased risk for one form of indirect self-injury, substance use. Findings suggest that nonsuicidal self-injury, suicidal self-injury, and substance use are associated with differential risk factors. Implications for targeted prevention strategies are discussed.

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Previous research linking school disruption with mental health problems has largely relied on assessments of academic achievement to measure school disruption. Early disruptive classroom behaviour (e.g., conflict with school staff, negative attitudes toward school), however, may precipitate poor academic performance and may stem from emerging mental health concerns, particularly among young children. To address this gap in the literature, 912 clinically referred children and youth (ages 4–18 years old) were assessed using the interRAI Child and Youth Mental Health (ChYMH) assessment utilizing a cross-sectional study design. The ChYMH assessment evaluates school disruption independently of academic achievement, and includes a comprehensive assessment of the child’s mental health functioning, needs, and preferences. A logistic regression analysis revealed that various provisional mental health diagnoses (i.e., attention-deficit/hyperactivity disorder, disruptive behaviour, mood disorders, and, to a lesser extent, anxiety) were associated with disruption in the classroom. Implications for school-based care planning are discussed.

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