8 / 2017-05-18 20:38:52

Chrysotile effects the expression of anti-oncogene P53 and P16 and oncogene C-jun and C-fos in wistar rats lung tissues

chrysotile; cancer; p53; p16; c-jun; c-fos

Chrysotile effects the expression of anti-oncogene P53 and P16 and oncogene C-jun and C-fos in wistar rats lung tissues
Yan Cui1, Jianjun Deng2, Yuchan Wang1, Gongli Hu1, Yuxin Zha1, Qingbi Zhang1,*
1 School of Public Health, Southwest Medical University, Luzhou 646000, Sichuan, P. R. China. 2 Department of Clinical Laboratory, 404 Hospital of Mianyang, Mianyang 621000, Sichuan, P. R. China. 3Key Laboratory of Solid Waste Treatment and the Resource Recycle, Southwest University of Science and Technology, Mianyang, Sichuan, 621010, P. R. China

Correspondence to: Professor Qingbi ZHANG, School of Public Health, Southwest Medical University, Luzhou 646000, Sichuan, P. R. China. Telephone: +86- 18113513199. Fax: +86-0830-3162283. E-mail: qingbizhang@126.com

Abstract
At least 107 000 people die each year from asbestos-related disease resulting from occupational exposure. Chrysotile is the most widely used form of asbestos worldwide. China is the world's largest consumer and second largest producer of chrysotile. Scientific evidences have shown that all types of asbestos, including chrysotile, can cause lung cancer and mesothelioma. To date, there are epidemiological investigations related to chrysotile exposure and evaluations of its effects in vitro. However, molecular mechanisms underlying the tumorigenic effects of chrysotile in vivo experimentation remained poorly understood.
In our study, Wistar rats were administered by intratracheal instillation for 0, 0.5, 2, or 8 mg/ml of chrysotile from Mangnai, Qinghai, China (the largest storage mining area in China) which dissolved in saline. 0.5ml each time, repeated once a month for 6 months. The lung tissues were analyzed at 1, 3 and 6 mouths for viscera coefficients and histopathological alterations. The mRNA and protein expression of P53, P16, C-Jun, and C-Fos were measured by western blotting and qRT-PCR.
Our results found that the rats in all exposure groups showed decreased in eating, drinking, and activity at 6 months, and IT-administered chrysotile lead to body weight grow slowly and lung viscera coefficients increase in a dose-dependent manner. Pictures of pathologic gross shows that the surfaces of lung tissues interspersed with white nodules, cavernous transformations and punctiform asbestos spots at 1 and 3 months, and the lung tissues shown up swollen or atrophied at 6 months. Bleeding, asbestos plaques, damaged alveolar structures and fibrosis were observed in HE stains lung sections.
In addition, levels of P53 protein at 3 and 6 months in the chrysotile exposed groups decreased significantly in a dose-dependent way. Levels of P53 mRNA at 6 months in chrysotile exposed groups were significantly lower than those in the negative control; otherwise, those at 3 and 6 months in the 8 mg/ml chrysotile exposed groups decreased significantly compared to other chrysotile exposed groups. At 3 months, levels of P16 protein and mRNA in the chrysotile exposed groups decreased significantly in a dose-dependent way; moreover, levels of P16 protein and mRNA at 6 months in the 8 mg/ml chrysotile exposed groups decreased significantly compared the other chrysotile exposed groups.
Levels of C-JUN protein at 3 months in the chrysotile exposed groups increased in dose-dependent way; in all groups exposed to chrysotile, those at 6 months were higher than the negative control; otherwise, those at 6 months in 2 and 8 mg/ml chrysotile exposed groups were significantly higher than those in 0.5 mg/ml chrysotile exposed group. Levels of C-jun mRNA at 3 and 6 months in 2 and 8 mg/ml chrysotile exposed groups increased significantly in a dose-dependent way. Likewise, levels of C-FOS protein at 1 and 3 months in the chrysotile exposed group increased significantly in a dose-dependent way; those at 6 months in the chrysotile exposed groups were significantly higher than the negative control; but the difference among chrysotile exposed groups was not significant. C-fos mRNA levels at 1 month in 8 mg/ml chrysotile exposed group were significantly higher than those in the negative control and the other chrysotile exposed groups; levels of c-fos mRNA at 3 months in the chrysotile exposed groups increased significantly in a dose-dependent way; in all groups exposed to chrysotile, levels of c-fos mRNA at 6 months were higher than for the negative control; otherwise, those at 6 months in 2 and 8 mg/ml chrysotile exposed groups were significantly higher than those in 0.5 mg/ml chrysotile exposed group.
The results indicate that, chrysotile can induce inactivation of the anti-oncogene P53 and P16, and activation of the proto-oncogenes C-JUN and C-FOS both in the mRNA and protein level in rats lung. In conclusion, chrysotile induced an imbalanced expression of cancer-related genes in rats lung tissue. These results contribute to our understanding of the carcinogenic mechanism of chrysotile.

Key words: chrysotile; cancer; p53; p16; c-jun; c-fos