Expression of nicotinic acetylcholine receptor subunit genes in non-small-cell lung cancer reveals differences between smokers and nonsmokers.

Nicotine and its derivatives, by binding to nicotinic acetylcholine receptors (nAChR) on bronchial epithelial cells, can regulate cellular proliferation and apoptosis via activating the Akt pathway. Delineation of nAChR subtypes in non-small-cell lung cancers (NSCLC) may provide information for prevention or therapeutic targeting. Expression of nAChR subunit genes in 66 resected primary NSCLCs, 7 histologically non-involved lung tissues, 13 NSCLC cell lines, and 6 human bronchial epithelial cell lines (HBEC) was analyzed with quantitative PCR and microarray analysis. Five nonmalignant HBECs were exposed to nicotine in vitro to study the variation of nAChR subunit gene expression with nicotine exposure and removal. NSCLCs from nonsmokers showed higher expression of nAChR alpha6 (P < 0.001) and beta3 (P = 0.007) subunit genes than those from smokers, adjusted for gender. In addition, nAChR alpha4 (P < 0.001) and beta4 (P = 0.029) subunit gene expression showed significant difference between NSCLCs and normal lung. Using Affymetrix GeneChip U133 Sets, 65 differentially expressed genes associated with NSCLC nonsmoking nAChR alpha6beta3 phenotype were identified, which gave high sensitivity and specificity of prediction. nAChR alpha1, alpha5, and alpha7 showed significant reversible changes in expression levels in HBECs upon nicotine exposure. We conclude that between NSCLCs from smokers and nonsmokers, different nAChR subunit gene expression patterns were found, and a 65-gene expression signature was associated with nonsmoking nAChR alpha6beta3 expression. Finally, nicotine exposure in HBECs resulted in reversible differences in nAChR subunit gene expression. These results further implicate nicotine in bronchial carcinogenesis and suggest targeting nAChRs for prevention and therapy in lung cancer.

Video-assisted thoracoscopic talc pleurodesis is effective for maintenance of peritoneal dialysis in acute hydrothorax complicating peritoneal dialysis.

BACKGROUND: Acute, massive, unilateral hydrothorax is an uncommon but well-recognized complication of peritoneal dialysis. Its clinical course and treatment outcome after a recently advocated technique of video-assisted thoracoscopic (VATS) talc pleurodesis remains unclear. METHODS AND RESULTS: Between July 1998 and March 2002, among 475 CAPD patients in two regional hospitals in Hong Kong, nine patients (three men, six women, mean age 53+/-12 years) developed acute hydrothorax due to pleuroperitoneal communication (R=8, L=1) within 5.8+/-4.2 months (median, 5.2 m; range, 2 days to 11.6 months) of commencing peritoneal dialysis. Analysis of simultaneously obtained peritoneal and pleural fluid in all subjects only showed concordance in protein content (consistently<4 g/l), while fluid glucose and lactate dehydrogenase levels were not comparable. The methylene blue test was negative (n=4). Radionuclide scan (n=6) and contrast CT peritoneography (CTP, n=3) detected pleuroperitoneal communication in half and one-third of the patients, respectively. All patients underwent pleurodesis achieved by talc insufflation into the pleural cavity under VATS guidance. All patients were successfully returned to peritoneal dialysis. After a mean follow-up of 18.8+/-12.5 months, hydrothorax recurred in one patient (at 7 months after pleurodesis), who was successfully treated by repeating the procedure. CONCLUSIONS: Hydrothorax complicating CAPD is more commonly right-sided, and tends to occur within the first year of starting peritoneal dialysis. Isotope scan and CTP are insensitive in diagnosing pleuroperitoneal communication. A low pleural fluid protein content is the most consistent biochemical finding. VATS talc pleurodesis is a safe and reliable treatment of choice that allows sustained continuation of CAPD with low recurrence rate.