Detection Of Related Genetic Alterations In Lung Cancer Among Yunnan Tin Miners And Study On An Animal Model Of Lung Cancer With Yunnan Tin Mineral Dust In F344 Rats

Objectives:To set up an animal model of lung cancer with Yunnan Tin Mineral dust in F344 rats. To compare the different expressions of Sp-B, FHIT and HnRNP in lung cancer among Gejiu District tin miners and non-miners in other regions.To detect loss of exon 3,4,5 and 8 of FHIT gene in a lung cancer cell line of Yunnan Tin miners and lung cancer samples. To explore pathologic and molecular alterations in various stages of malignant transformation in the animal models.To investigate the early behavior of molecules in carcinogenesis and development of lung cancer. To examine correlation between fibrosis induced by mineral dust and lung cancer in Yunnan Tin miners. To support extended experimentation and theoretical evidence for prevention, therapy ,and early diagnosis of lung cancer in Yunnan Tin Miners.Methods :1. Induced lung cancer in F344 rats was examined : The rats were divided into four groups: one experiment group and three control groups.Following the intratracheal instillation of Yunnan Tin Mineral dust in the rates once per week,they were put to death in batches periodically. The morphological process and tumor formation were dynamically observed under LM and TEM.2. Polymerase chain reaction (PCR) technique was used to detect the presence or absence of the exon 3,4,5, and 8 of FHIT gene in a lung cancer cell line of Yunnan Tin miner and lung cancer samples from Yunnan Tin miners in Gejiu District and non-miners in other regions.HnRNP, FFflT and SP-B protein expression were detected in paraffin-embedded human lung by immunohistochemical method. The number of SP-B positive expression cell and extent of fibrosis was quantitatively analyzed using image analysis system.3.MDM2, P21~ras, P53, HnRNP, and FHIT protein was investigated in F344 rat models developed by the intratracheal instillation of Yunnan Tin Mineral dust by the methods of immunohistochemistry . Immunohistochemistry detection of cytokeratin of High MW and low MW were used for tumour classification .Pollak steining was used to appraise the development of fibrosis of lung in the rats.Results:1. Bronchoavleolar inflammation occurred in the early stage after using the intratracheal instillation of Yunnan Tin Mineral dust in F344 rats.Along with reduction inflammation, collagen fibrils increase at alveolar interstices. Simple hyperplasia, papillary hyperplasia and metaplasia of the epithelial cells in alveolar and bronchi were observed, followed by atypical adenomatous hyperplasia and Squamous dysplasia . Lung cancer was induced In the end.(Among a total 14 cases of lung cancer were 9 cases of adenocarcinoma,2 of squamous cell carcinoma and 3 of mixed carcinoma.No lung cancer occurred in control groups.) Significant hyperplasia of fibrous tissue and local fibrosis was exhibited in the area of deposited mineral dust.2. Loss of Exons 3 and Exon 8 was detected in a lung cancer cell line of Yunnan Tin miners. Lung cancer samples from Yunnan Tin miners and non-miners exhibited loss of heterozygosity of FHIT gene among exons 3,4,5 and 8.FHIT gene delection and loss of FHIT protein expression in lung cancer of Yunnan Tin miners was 68.2% and 70.6% respectively. There was a significant difference in loss of heterozygosity of FHIT gene between lung cancer(squamous carcinoma or adenocarcinoma) and normal tissue.The positive expression rate of HnRNP A2/B1 gradually increased from normal tissue,to adjacent tissue, to lung cancer tissue.Strong positiveexpression of HnRNP A2/B1 was observed in lung cancer both in Yunnan tin miners and non-miners,the positive rate equalling 100%. 3.The number of type IIalveolar epithelial adjacent carcinoma in Gejiu District miners was much higher than that in non-miners of other regions and normal lung tissue(P<0.01). The rate of the deposited mineral dust and fibrosis of lung cancer in Gejiu miners was significantly higher than that of non-miners .The proliferating type II alveolar epithelial cell positively correlated with extent of fibrosis of lung cancer (rs=0.961).4. Overexpression of MDM2, P21ras, P53 and HnRNP and loss of FHIT protein was detected in the early stage of F344 rat lung canceration with Yunnan tin Mineral dust. Two squamous metaplasias were found in alveoli that express cytokeratin of High MW.The greater the mineral dust deposit, the more serious the alveolar fibrosis. Conclusions:1. Intratracheal instillation of Yunnan tin Mineral dust in F344 rats induced preinvasive bronchial lesions and early lung cancers. Such carcinoma exhibited similar pathomorphologic change to that found in human lung cancer of Yunnan Tin Miners.2. Excessive expression of MDM2, P21ras,P53, and HnRNP and decrease or loss of FHIT expression was an early molecular event in the developing process of induced lung cancer by Yunnan Tin MineraldustThis could be an invaluable biologic marker to predict one risk of lung cancer.3. Type II alveolar epithelial cells may be an origin of adenocarcinoma of induced lung cancer by Yunnan Tin Mineral dust in F344 rats. They may be one of the origin cells of some periphera squamous cell lung carcinomas.4. Abnormality of FHIT gene was a commen genetic alteration in lung cancer of Yunnan tin miners.The high rate of loss expression of FHIT and overexpression of HnRNP A2/B1 was examined in preneoplastic lesions and early stage of lung cancer.Detection and analysis of FHIT and HnRNP A2/B1 could be used as an early screening target of lung cancer.5. Instillation of mineral dust in F344 rat lungs caused collagen fibrils increase at alveolar interstices and type II alveolar epithelial cell damage following repair and hyperplasia. The proliferation of II -AT and fibrosis of lung may be mutually conditional. Lung fibrosis caused oncogenic development in the presence of tin mineral dust, perhaps leading to increase incidence of lung cancer. The correlation of Lung fibrosis with carcinogenesis of lung cancer is worthy of further study.