| Lung cancer is one of the most common malignant tumor all over the world, the morbility and mortality increase fast. From the statistics of WHO, there is 1352132 new cases and 1178918 deaths. The morbility in developed countries is higher than developing countries. In our country the morbility of lung cancer increased quickly. The number of cases is 269650 in man and 126718 in woman. The clinical symptoms in natural course appear later, yet the conventional radiotherapy, chemotherapy and operation cannot decrease the case fatality. Therefore, an important step is to discover, diagnose and treat in earlier period , which may base on the clarity of the mechanism of lung cancer .The research methods of the mechanism are as follows: research of the the population, experimental animal models, and the malignant transformation cell models. The research of malignant transformation cell models can use 3 different type cells, including fibroblast , embryo-lung cell and human bronchial epithelial cell. But most of lung cancer origin from human bronchial epithelial cell.Benzo[a]pyrene is a well-known carcinogen which can induce lung cancer. It exsits everywhere. In food processing, Benzo[a]pyrene could form as a by-product when the temperature is higher than 180℃.In current studies, a crop of genes and proteins were screened, and then dynamic expression of several genes were observed, but most of the research objects are malignant cell or tissue, may not be the crucial genes. We think if we want to solve the problem, we have to search for the crucial period in malignant processing first, and then explain the feature of the alteration and mechanism.In our experiment, models of malignant transformation of BEAS-2B cell in several periods induced by B(a)P were established, and the different expressed genes in different periods of the processing in cell malignant transformation was analyzed by microarray, providing evidence for seeking the crucial period.Methods:(1).BEAS-2B cells were reacted with B(a)P at the concentration of 100nmol for 24 hours, including a DMSO control group, then with conventional culture. The characteristics of the cellular biology were observed and the malignant transformation of cells were identified through observing the serum resistance, anchorage independent growth and nude mice tumorigenesis assay(BALB/B-nu/nu).Then the malignant transformation model of cells at different phases were established.(2).RNAs from 1,5,10,20,30 passages of BaP-induced BEAS-2B and the same of the control group were extracted for reversed transcription cDNA probes. The mixed probes were hybridized with Affymetrix genechip human genome U133 plus 2.0. Different gene expression profiles were obtained by GCOS software. And the genes of differential expression were screened.Results:(1).Established the BaP-induced malignant transformation models of BEAS-2B cell at different phases.(2).Each group cells in 10th generation didn't show the serum resistance. To experimental group cells in 20th generation, the multiplication time, the serum resistance were increased.(3).The experimental group cells were formed small cell colonies in soft agar in 25th generation. The anchorage independent growth was appeared in 30th generation experimental group cells.(4).Gene expression profile at different phases of malignant transformation were observed, we found significantly different expressing characteristic.Conclusions:(1).Established the BaP-induced malignant transformation models of BEAS-2B at different phases.(2).The characteristics of malignant transformed cells of BEAS-2B induced by BaP: the serum resistance were obviously increased in 20th generation of experimental group; and were formed small cell colonies in soft agar in 25th generation. The anchorage independent growth was appeared in 30th generation experimental group cells.(3).We found significantly different expressing characteristic in different passage ,and the hypothetical genes account for a great propotion. Several tumor relevant genes express different in 5 passage ,but it is more significant in 10 or 20 passage, suggest that this period may be crucial phase in cancerazation.,the 10th generation may be the early phase of cancerilization.
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