| Lung carcinomas are now the leading cause of cancer mortality worldwide among both men and women. In china, this neoplasm has become the most fatal malignant disease, with its incidence keeping rising in the last two decades. There are three strategies to reduce the rate of mortality of lung cancer: prevention, early detection and advances in treatment. To date, early detection, especially molecular diagnosis represents the most promising strategy. With the understanding of the genetic basis of lung carcinogenesis, there raises the hope that molecular markers could be of great use to detect lung cancer at the earliest stages of this disease. It is clearly important to develop effective molecular diagnostic methods to enable early detection and therapeutic intervention in lung cancer.In the present study, IFISH (interphase fluorescence in situ hybridization) was applied to analyze the molecular cytogenetic alterations in sputum cells from lung cancer patients and cells from two SV40 L-T immortalized human bronchial epithelial cell lines M and Y, while spectral karyotyping (SKY) was performed on the same immortalized cells. Besides the genetic abnormalities, epigenetic alterations of aberrant methylation was detected by methylation-specific PCR (MSP) and methylation-sensitive arbitrarily primed PCR (MS-AP-PCR) were used to analyze p16 promoter hypermethylation and genomic aberrant methylation in the clinical samples from lung cancer patients. Our data showed:1. Gene deletion and chromosomal numerical alterations in sputum cells.1). Using the specific centromeric probes of chromosome 1, 3, 6, 7, 8, 9, 10, 11,12, 15, 17, 18, X and Y, chromosomal alterations were detected in 45 sputum samples from lung cancer patients. Gain of Chromosome copy number was frequently observed with chromosome 1, 3, 7, 8 and X, while loss was the most frequent abnormality of chromosome 9, 15 and 17. As to chromosome 6, 10, 11, 12, 18 and Y, both gain and loss were detected with the similar frequencies. There were a number of chromosomal alterations involving several chromosomes in a single case, and more than one kind of alteration happened to the same chromosome, implicating the malfunction of mitotic regulations at chromosomal level during lung carcinogenesis.2). Detection of chromosomal numerical alterations (gain and loss) was more sensitive and specific than traditional cytological analysis. Among those studied chromosomes, chromosome 17 and 18 were the most frequently altered ones in sputum cells (83.7% and 83.9% respectively), followed by chromosome 7, 8, 9, 10, 11, 12 and X. As potential biomarkers for lung cancer detection, combination of any two of those chromosomes could have positive results with the frequencies more than 80%.3). Deletion of exon 1, 5, 6-7 of FHJT was frequently observed in sputum cells, and the frequency of at least one exon deletion was 76% (19/25), mostly in the form of relative deletion.4). The modified method of interphase fluorescence in situ hybridization (IFISH) performed on sputum cells in this study was proved to be of high efficiency and accuracy, with the lower background and higher penetrability of the probes.Chromosomal numerical abnormalities were frequently observed in sputum cells from lung cancer patients, indicating the potential as biomarkers to assist the diagnosis of this neoplasm. The modified IFISH technique established in this study provided an effective approach to analyzing molecular cytogenetics of lung cancer with sputum specimens.2. Molecular cytogenetic abnormalities in cells from SV40 L-T immortalized human bronchial epithelial cell lines M and Y.1). Chromosomal alterations of 3p detected by FISH.a. In the early passages of cell line M, total deletions of chromosome 3pl2, 3pl3, 3pl4, 3p21, 3p22-23 and 3p24 were observed with a variety of frequencies; with the passaging of the cells, more and more relative deletions were detected. Translocations of chromosome 3pl4 and 3p24 were observed in the cells of early passages. Translocations o... |
PDF Full Text Request