Asbestos exposure affects poly(ADP-ribose) polymerase-1 activity: role in asbestos-induced carcinogenesis.

Asbestos is known to induce malignant mesothelioma (MM) and other asbestos-related diseases. It is directly genotoxic by inducing DNA strand breaks and cytotoxic by promoting apoptosis in lung target cells. Poly(ADP-ribose) polymerase-1 (PARP1) is a nuclear zinc-finger protein with a function as a DNA damage sensor. To determine whether PARP1 is involved in asbestos-induced carcinogenesis, PARP1 expression and activity as well as DNA damage and repair were evaluated in circulating cells of asbestos-exposed subjects, MM patients and age-matched controls. PARP1 expression and activity were also evaluated in pleural biopsies of MM patients and compared with normal tissue. Accumulation of the pre-mutagenic 8-hydroxy-2'-deoxyguanosine and elevated PARP1 expression were found both in asbestos-exposed subjects and MM patients. Although PARP1 was highly expressed, its activity was relatively low. Low DNA repair efficiency was observed in lymphocytes from MM patients. High expression of PARP1 associated with low PARP activity was also found in MM biopsies. To mimic PARP1 dysfunction, PARP1 expression and activity were induced in immortalised mesothelial cells by their exposure to asbestos in the presence of a PARP1 inhibitor, which resulted in transformation of the cells. We propose that exposure to asbestos inhibits the PARP1 activity possibly resulting in higher DNA instability, thus causing malignant transformation.

Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk.

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2'-deoxyguanosine (80HdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFbeta) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 80HdG in DNA. Elevated levels of 80HdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [> 60(ff/cm3) x years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

Relationship of job satisfaction, psychological distress and stress-related biological parameters among healthy nurses: a longitudinal study.

OBJECTIVE: To examine the relationship between job satisfaction, psychological distress, psychosocial processes and stress-related biological factors, and to evaluate whether over time changes of work satisfaction could affect the immunological-inflammatory status of workers. METHODS: One hundred and one nurses were enrolled at the Clinic of Occupational Medicine, Polytechnic University of Marche, Ancona, Italy. Perceived job satisfaction, psychological distress, and social support were assessed every 4 mo over a 1-yr period using 4 self-reported questionnaires. T lymphocytes CD3, CD4(+), CD8(+), CD8(+)-CD57(+), B lymphocyte CD19(+), NK cells CD56(+), and NK cell activity were determined. RESULTS: Job satisfaction was associated with reduced psychological distress and was characterized by low cell numbers of CD8(+) suppressor T cells, CD8(+)-CD57(+) activated T cells, CD56(+) NK cells and low IL-6 levels. Over time changes in psychological parameters were related to changes in the immunological-inflammatory variables. Subjects who increased their job satisfaction showed a reduced psychological stress associated with reduced number of CD8(+)-CD57(+) activated T cells and inflammatory cytokines. CONCLUSIONS: Job (dis)satisfaction is related with psychological mechanisms in stress affecting cellular immune function.