A study of the relationship between p53 mutation and smoking in human non-small cell lung cancer

Abstracts

I Lung

Cancer

A study of the relationship between p53 mutation and smoking in human non-small cell hmg cancer Li Jin-han, Bi X.J. and Peng Z.H. Deportment of Oncology, Nan Fang Hospital. First Military Medical University. Guangzhou, China A study was undertaken from 1992 to 1993 to explore the relationship between ~53 mutation and cigarette smoking in human primary nonsmall cell lung cancer (NSCLC). A group consisting of 43 males and 9 females, with an age range of 30 to 71 years (median, 55). comprised 30 squamous cell carcinomas and 22 adenocarcinomas. The detection of ~53 mutations of all resected NSCLC specimens was performed using immunohistochemical techniques. One patient with adenocarcinoma had a mutated allele of ~53. Polymerase chain reaction--single strand conformation polymorphism (PCR-SSCP) analysis showed the ~53 mutation to be in the region between exons 5, 6, 7 and 8. Sequence determination revealed that codonhad been changed from AGA to ACA. Thirty-seven of the 52 lung cancer patients were self-reported smokers, suggesting that lung cancer was probably associated with smoking. Among the 25 patients with a ~53 mutation, smokers accounted for 17 cases (68%), which was not significantly different (P > 0.05) from the 20 smokers (74%) identified fmm the remaining 27 lung cancer cases showing no mutation in the ~53 gene. These results suggest that the ~53 mutation may not be correlated with smoking. Point mutations of Ha-ras and Ki-ras oncogenes in sputum specimens from lung cancer patients He Liig, Chen Jia-kun, Yi Fei, Wu Zhong-liang and Du Ying-xiu. Institute For Chemical Carcinogenesis, Guangzhou Medical College. Guangzhou. China Point mutations in rails(Ha-, Ki- and N-ras) genes can be found in lung zancer. Mutations of Ki-ras genes are most frequently found in lung ddenocarcinomas (30%). Because oncogene mutation may take place before cell malignant transformation, we used SpUNm from lung cancer patients as specimens to evaluate the early diagnostic value of Ha- and Ki-ras mutations for lung cancer and developed a simple, rapid and nonradioactive method to detect point mutations in the 12th codon of Ha-ras and Ki-ras genes. DNA was extracted from digested sputum and amplified by the polymerase chain reaction (PCR), and then digested with specific restriction enzymes (HpaII) to detect either endogenous (in Ha-ras gene) or primer-mediated (in Ki-ras gene) restriction fragment length polymorphisms (RFLPs). Fifty sputum specimens from lung cancer patients (20 adenocarcinomas, 12 squamous cell carcinomas, 16 small cell carcinomas and 2 large cell carcinomas) were examined for Ha-ras and Ki-ras gene mutations in codon 12. Neither Ha-ras nor Ki-ras gene mutations were detected in sputum from lung cancer patients who had small cell and large cell carcinomas; whereas, Ha-ras gene mutations were detected in 10% of the Sputum fmm adenocarcinoma patients and in 8.3% from squamous cell carcinoma patients. Additionally, 20% of the sputum from adenocarcinoma patients contained mutations in codon 12 of the Ki-ras gene, but none of the sputum samples from squamous cell carcinoma patients had this mutation. The simple method developed by us and used in this study is especially suitable for analyzing small size samples where only a fraction of the biological material may carry the mutated oncogenes. We also determined that point mutations in codon 12 of the Ha-ras and Ki-ras genes are more frequently found in sputum specimens of adenocarcinomas patients than in patients with other kinds of lung cancer. These results suggest that mutations of the ras genes in sputum may be indicative of early stages of lung cancer. Induction of DNA-protein crosslink in rat lung and blood ceIIs by the carcinogen nickel Lei Yi-xiong’, Zhang Qiao” and Zhuang Zhi-xiong”. “Department of Hygiene, Guangzhou Medical College, Guongzhou. China, and “Research Unit of Genotoxicology, Sun Yat-sen Vniversiry of Medical Sciences, Gaangzhou. China

14 Suppl.

I (1996)

S235-S245

Nickel(II) compounds are common environmental contaminants and human carcinogens. Like many other environmental agents and carcinogens such as UV light, y-radiation. alkylating agents, formaldehyde and benzo(a)pyrene, exposure to nickel(I1) is accompanied by formation of DNA-protein crosslinks (DPC). which are thought to be important genotoxic lesions because of their relative persistence in the cells. Because they are poorly repaired, DNA-protein complexes may be present during DNA replication and possibly cause a loss of important genetic material such as inactivation of Nmor suppressor genes. A number of epidemiological and experimental shldies have shown that nickel compounds cause lung cancer in both humans and animals. In order to investigate the relationship between lung cancer and DPC induced by nickel compounds, and in an attempt to develop biomarkers for nickel exposure, we have used a rapid, simple and sensitive ‘?postlabelling assay to detect the formation of DPC in white blood cells (WBC) and lung cells from male Sprague-Dawley rats given nickel chloride (NiCl,) intraperitoneally (i.p.). DNA was iodinated with NalzJI using chloramine T. The iodine was reduced by the addition of flmercaptoethanol, and the DNA-protein complexes (with tyrosine labeled by iodination) were isolated by repeated precipitation with ethanol. The results show that 20 hr after rats were treated with NiCI,, DPCs were found in WBC and lung cells. Compared to the control group, rats injected with 10, 20 and 30 mglkg NiCI, showed increases of DPC in WBC of 236, 367, and 262%. respectively; in the lung the increases of DPC were 159, 192, and 144X, respectively. The fortnation of DPC in WBC and lung cells was also observed following multiple treaanent of rats (1 control group and 1 treated group) with NiCl, (10 mg/kg, i.p. x 3 weeks). A 247% increase of DPC was seen in WRC and a 146% increase was seen in lung cells of the treated group. DPCs found in rat lungs after NiCl, treatment are possibly related to the carcinogenic@ of nickel compounds. In addition, the DPC in lung cells and WBC may be used as biomarkers to quantitatively represent exposure to NiCI, and genotoxic lesions induced by exposure to Ni. In our DPC-induction studies, WBC were shown to be more sensitive than lung cells in responding to nickel; there also was a significant correlation in DPC between the two cell types, indicating that measuring DPCs in WBC may he a good surrogate for investigating human exposure of target tissues to environmental carcinogens or mutagens. An analysis of seven metals in hmg cancer tissues in Guangzhou, China population Zhong Sai-xian, Chai Cheng-keng, Zhao Zhen-xin and Chen Chengzhang. Department of Environmental Health, Sun Yat-sen University of Medical Science, Guangzhou. China The role of metals in the development of cancer has been a matter of concern in recent years. We analyzed 7 metal elements (Mn, Mg, Zn, Cd, Cr. Ni, Cu) contained in the lungs of 10 lung cancer patients and 10 normal subjects (control group) from the Guangzhou population, using an atomic absorption spectrometer. From the data, it can he seen that, of the 7 metals measured in the observed group, 3 metals (Mn, Mg, Zn) were significantly increased in lung tissue when compared with those in the control group (P < 0.05). The values obtained in lung tissue of lung cancer patients was about 2-fold higher than those of controls. We believe that some metals might play an important role in the pathogenesis of lung cancer and that the sources of these elements in our bodies might be quite different. Some of them, for example, Mn, Cd and Ni, might arise from atmospheric pollution while others, such as Zn and Cu may be related to our dietary habits. Natural killer (NK) cell roll-2 in patients with Zhang Qiu-Wang. Yang Shu-xia and Liang Xi-rue. Guangrhou Medical

activity assessment and NK cell activation by hmg cancer Ying. Cheng Xiang-yang, Fang Xiang, MO Department ofMicrobiology and Immunology. College, Guangzhou. China