The Effects of Tetrandrine (TT) and Polyvinylpyridine-N-Oxide (PVNO) on Gene Expression of Type Ⅰand Type ⅢCollagens during Experimental Silicosis

In the screening tests of drugs for silicosis in our laboratory, we found that TT, a type of alkaloid isolated from Stephania tetrandra, could inhibit the development of experimental silicosis of rats and the synthesis of collagen in rat lung. Chest X-rays of silicotic patients treaied with TT for 1-3 years showed obvious changes. The silicotic nodules became smallel and shadows became clearer. PVNO was proved to have anti-silicotic effect on animal and clinically. This presentation reports the effect of them on collagen mRNA.Dot blot results showed that 1 (Ⅰ) and 1 (Ⅲ) mRNA levels increased significantly at 60 and 120 days after the rats were exposed to silica dust. The mRNA levels went down at 1 and 3 months after treated by TT and PVNO. In situ hybridization observation revealed that the silver grains of Type Ⅰand Type Ⅲ collagen were scattered within the fibroblasts in cellular nodules and in thickened interstitium of silicosis tissue. The amounts of mRNA silver grains decreased in the lung tissue treated by TT and PVNO. It was suggested that TT and PVNO may inhibil the gene expression of collagen during silicosis

Ceruloplasmin or Fibronectin Synergism with Quartz Dust on Stimulating Collagen Gene Transcription in Human 2BS Fibroblast

Human α1(Ⅰ), α2(Ⅰ) and α1(Ⅲ) cDNA probes and RNA dot hybridization were employed to quantitate collagen mRNA changes after adding silica dust into the media of human 2BS fibroblasts. At all dosages used (100, 200, 500 and 1000μg), the α1(Ⅰ), α2(Ⅰ)and α1(Ⅲ) mRNA levels increased one day after dusting. At the same dosage of silica (100μg), α1(Ⅲ) mRNA increased earlier than type Ⅰ collagen mRNA did. The type Ⅰ and type Ⅲ collagen mRNA contents in the experimental groups were higher than those in control on days 3, 5, 7 and 9. The effect of ceruloplasmin (Cp) and fibronectin (Fn) on collagen mRNA synthesis was also studied, after adding silica dust, Cp or Fn into the media of human 2BS fibroblast. The results showed that Cp and Fn have stimulating effect on collagen mRNA production. When both Cp and silica dust were added into cell culture media, the collagen mRNA level was increased more than those of adding either Cp or silica dust alone. Similar situations were found for Fn. Cp (or Fn) synergism with silica dust on stimulating transcription of human collagen gene was suggested

Role of dNTPs in Mutagenesis

The induced mutation frequency by alkylating mutagen glycldyl methacrylate (GMA) and N-methyl-N'- nitro- N-nitrosoguanidine (MNNG) was investigated with or without perturbation of deoxyribenucleoside triphosphate (dNTP)pools; the influence of short treatment at different concentrations of GMA or MNNG on dNTP pools was also explored. The results indicated that the induced mutation frequency increased greatly at high dosages of mutagen (GMA~ 64 μg/ml, MNNG~ 8 μg/ml) and the perturbation on dNTP pools was carried out before the treatment of mutagen; the short treatment with mutagen could induce distinct fluctuations of dNTP pools, but different mutagen might have different effects on dNTP pools.According to the results of the present study and other reports in literature, we conclude that dNTP pools may be the targets of alkylating mutagens and the fluctuations of dNTP pools are closely associated with mutagenesis

p53 Gene Mutations in Asbestos Associated Cancers

The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancerl adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein mpitive. Seven cases were found to have mutations by PCRSSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be opitive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8)were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%,4/5). ffequencing analysis on two specimens revealed two hotspot mutations. In codon 234,TAC for tyrooin was mutated to AAC fOr aspar8gine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. ln conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.