Increased expression of human calcium-activated chloride channel 1 gene is correlated with mucus overproduction in Chinese asthmatic airway.

Asthma is usually complicated with mucus overproduction in airway. Recently the increased expression of the human calcium-activated chloride channel 1 (CaCC1) was found to play an important role in mucus overproduction in the asthmatic airways. To investigate the relationship of Calcium-activated chloride channel 1 (CaCC1) and mucus overproduction in Chinese asthmatic airway, the expression of CaCC1, mucin 5AC (MUC5AC) and mucus in bronchial tissues were examined. Bronchial tissues were isolated from non-cancerous areas of lungs obtained following resection for lung neoplasm in West China Hospital from April to July in 2004. Six patients were diagnosed lung neoplasm with moderate asthma, and other ten were diagnosed lung neoplasm without asthma as the control subjects. The expression of CaCC1, MUC5AC and mucin in bronchial tissues was detected by reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridized with digoxigenin (DIG)-labeled RNA probe, immunohistochemical and Alcian blue-periodic acid Schiff (AB-PAS) staining, respectively. In RT-PCR, two expression patterns of CaCC1 mRNA were found, which were located in the 450 bp and 510 bp. With in situ hybridization, a stronger expression of CaCC1 mRNA was further detected throughout the bronchial tissues from patients with asthma than control subjects (P<0.01); Samples from asthmatics were showed a stronger staining for MUC5AC than those in control subjects (P<0.05); AB-PAS staining revealed more mucins and goblet cells in asthmatic bronchial epithelium and submucosal gland comparing to that in control subjects (P<0.05). The increased expression of CaCC1 in asthmatic airways was well correlated with the expression of MUC5AC protein, the percentage of goblet cells and the area of submucosal gland (P<0.01, P<0.01, P<0.05). These results suggest that the up-regulated gene expression of CaCC1 exists, which is complicated with mucus hyper-secretion in Chinese asthmatic airway.