Submitted by Orman Language School team:

Sherif Mohamed Helal
Mohamed Hassan Ali
Shaymaa Hassan Ali
Heba Ramadan

Sponsor and Project Supervisor:

Dr. Hassan Ali Hussein
Researcher
National Research Center
Department of Human Genetics
Dokki, Giza - Egypt

Download this report for print

Abstract

In the present study, we performed an analysis in search of genetic changes due to smoking. We selected 10 normal nonsmoking persons as control and 10 smoking persons as cases for the study. We recorded their medical history, the duration of smoking, and the number of cigarettes smoked per day. In our results we found that the breakage of chromosomes was higher in smokers than nonsmokers, and we expected that there is a linkage between this breakage and Cancer.

Introduction

Smoking, is inhalation and exhalation of fumes of burning tobaco. Leaves of the tobaco plant are smoked in various ways. After a drying and curing process, they may be rolled into cigars, or shredded for insertion into smoking pipes. Cigarettes are made of finely shredded tobaco rolled in lightweight paper, and this is the most popular method of smoking.

As recently as the 1940’s, smoking was considered harmless. Since then, laboratory and clinical research has proved that cigarette smoke contains around 4000 chemicals, some of which are potentially dangerous for humans. All such studies found increased mortality among smokers, both from cancer and other causes.

(Sandler, et al 1993) reported in his conclusion: cigarette smoking is associated with increased risk for Leukemia and may lead to leukemia of specific morphologic and chromosomal types.

(Sanchez – Cespes, et al 2001) reported that their data demonstrate that widespread chromosomal abnormalities were frequent in lung adenocarcinoma from smokers whereas these abnormalities were infrequent in such tumors arising in nonsmokers.

These observations support the notion that lung cancers in smokers arise through genetic alterations distinct from the common events observed in tumors from smokers.

The American Cancer Society estimates that cigarettes are responsible for about 419,000 deaths in the United States each year. Chief among cancers caused by smoking is lung cancer, which accounts for 30 percent of all U.S. cancer deaths. Smoking accounts for 87 percent of the deaths from lung cancer. The risk of dying of lung cancer are 22 times higher for male smokers and 12 times higher for female smokers than for nonsmokers. Additionally, smokers are at increased risk of cancer of the larynx, oral cavity, eusophagus, bladder, kidney, and pancreas.

Smoking also causes a fivefold increase in the risk of dying from chronic bronchitis and emphysema, and twofold increase in deaths from diseases of the tract and coronary arteries.

Partial metaphase with chromosomal breakage

Partial karyotype showing chromosome breake in 2p

Aim of this Work

To evaluate the effect of smoking on chromosomes.

Material and Methods

Peripheral blood sample (Leukocyte) from each of the cases and its control, microculture and macroculture was set up by the method of Arakki and Spartes (1963). Slides were stained by G-bonding according to the method described by Seabright (1971): 12 – 25 metaphases of each analyzed under the microscope, any structural or numerical anomalies recorded then photographed and karyotyped according to ISCN (1985).

We visited the Human Genetic Laboratory at the National Research Centre, Dokki – Giza for watching the procedures of culture technique, and examination of samples under the microscope and photography.

Results

Chromosomal studies were performed on 10 cases (smokers), and 10 controls nonsmokers, we recorded the results which reveals that:

Chromosomes breakage were studied in the smokers, where different types of chromosome breakage which affect chromosomes numbers 1p, 2p, 8q, 9p, 11p and the breakage represented 18%.

• In the control group the breakage represented 0.2%.
• We did not notice any numerical abnormalities in both.

Discussion

Chromosomes breaks which affect certain chromosomes may affect the chromosomes permanently as a chromosome is a DNA coiled around histone and non-histone proteins. So, the effect of hazardous chemicals affects the chromosome (DNA), causing changes in the genetic material. Such changes may cause cancer.

The etiology of lung tumors arising in nonsmokers remains unclear. Although mutation in the K-ras and p53 genes have been reported to be significantly higher in smoking-related lung carcinomas. Sanchez et al (2001) found allelic losses or gains at chromosomal arms 3p, 6p, 9p, 16p, 17p, and 19p were present significantly more often in adenocarcinomas from smokers than from nonsmokers. His results are similar to the results of this study.

Sandler at (1993) reported that cigarette smoking is associated with increased risk for leukemia and may lead to leukemias of specific morphologic and chromosomal types.

Conclusions

Cigarette smoking may be a risk for leukemia.

Cigarette smoking may have an effect on chromosomes to induce chromosomal breakage, which may lead to cancer.

Such effects of cigarette smoking should be made known to the public in order to avoid its hazards in order to decrease the risk of cancer.

Acknowledgment

We would like to express our thanks, and deepest gratitude to Dr. Hassan Ali Hussein, Researcher, National Research Center, Department of Human Genetics, Dokki, Giza - Egypt for his suggestions, guidance and valuable help while working in this project, and for dedicating so much of his valuable time to it.

The Project Reviewers

Brad Roscoe, Robert Young, Short Allerton