The Study Of Lung Cancer Model Induced By Urethane In Mice

Lung cancer is a malignancy that serious threat to human life and health, in recent years, theincidence and mortality rates are increasing every year. The animal model of lung cancer is very importantfor the research of pathogenesis and screening drug. However, in the common models of lung cancer, theincidence rate and the time of tumor formation of spontaneous and induced tumor are unstable and verydifferent from clinical oncology, while transplanted tumor grows too fast. Therefore, in order to study thepathogenesis and screen the treatment drugs of lung cancer, especially the screen of the characteristictraditional Chinese medicine, it is urgent to establish a lung cancer model that is similar to the biologicalcharacteristics of clinical lung cancer, stability and uniformity of tumorigenic, reproducibility well and highincidence rate of lung cancer.In our study, different doses of urethane, different strains of mice and different carcinogenicprograms were used to determined the best method of inducing lung cancer by comparing to thetumorigenesis rate and the average number of pulmonary nodules. The biochemical detection andhistopathological analysis were used to compare the similarity of urethane-induced lung cancer and clinicalhuman lung cancer. The use of the traditional Chinese medicine of cold and heat property further proofedthe Chinese medicine signs of lung cancer model. Meanwhile the experiments proposed a new pathogenicmechanism of lung cancer and provide a new concept and method for the clinical treatment of lung cancer.The C57BL/6mice were injected peritoneally with urethane twice weekly for five weeks toinduce lung cancer model, we overcame the gene resistance of C57BL/6mice to urethane and got a stableand uniform lung adenocarcinoma of100%carcinogenic rate in4months. The results of biochemical detection in tumor-bearing mice showed that the level of ColⅠ, MMP-9, TIMP-1, NGF, TrkA, BDNF,TrkB, TGF-β1, bFGF, Ins and Glut-4were significantly higher, while the level of LN and TC weresignificantly reduced, the differences were more significant with the extension of time compared to thenormal mice. The characteristics of urethane-induced lung cancer in mice accord with the clinical lungadenocarcinoma of interim differentiation, reflected in the complete structure of glandularsac, less invasive,full of tumor cells in cysts. The results of immunohistochemical were TTF-1（+）, CEA（+）, P63（－）.During the modelling by urethane, the model mice appeared gradually a Chinese medicine signs ofcongealing cold with blood stasis, such as chill, clump and lazy, cyanosis in tail and auricle, temperaturedrop, meanwhile, ATPase and LDH activity reduced, whole blood viscosity and erythrocytic aggregateindex increased, microcirculation disturbance and so on. The warm drug Aconitum carmichaili suppressedtumor progress throught reducing the signs and improving the abnormal levels of MMP-9, TIMP-1, NGF,BDNF, TGF-β1and LN in lung tissue. While cold drug Dandelion showed a increasing tendency to thesesigns and a trend to promote tumor progress.In order to confirm the tumor characteristics of prefering cold to heat, L02cells were treated by400μg/ml urethane to create a transformed cell line, and we found some malignant tumor cells qualities inthis transformed cell, for example, colony forming on soft agar, increased mitochondria in cell. The resultsof gelatin zymography and western blot showed that the MMP-9and TGF-β1in transformed cells weresignificantly higher than in normal cells. In addition, compared with the37℃, we found32℃culturecould increase the transformatiory rate of L02cells.In summary, urethane at dose of800mg/kg intraperitoneal injection, twice a week, for fiveconsecutive weeks, can be used to establish a model of lung cancer in mice, and this model is stable,uniform, and well reproducible. Higher consistency of the model with clinical lung adenocarcinoma, and showed a Chinese medicine signs of congealing cold with blood stasis, is very suitable for the screeningand evaluating of the anti-tumor chinese medicine, but also good for studying the causes of lung cancer andmaking the rational therapeutic schedule with chinese medicine.