Tobacco smoking and regression of
low-grade cervical abnormalities
Cancer Science, June 9, 2010 [Epub ahead of print]
Matsumoto K, Oki A, Furuta R, Maeda H, Yasugi T, Takatsuka N, Hirai Y, Mitsuhashi A, Fujii T, Iwasaka T, Yaegashi N, Watanabe Y, Nagai Y, Kitagawa T, Yoshikawa H; for the Japan HPV And Cervical Cancer (JHACC) Study Group.
The role of tobacco smoking in the multistage carcinogenesis at the cervix is not fully understood because of a paucity of prospective data. To assess the relationship between smoking and spontaneous regression of cervical precursor lesions, a total of 516 women with low-grade squamous intraepithelial lesion (LSIL) were monitored by cytology and colposcopy every 4 months. Probability of LSIL regression within 2 years was analyzed in relation to smoking behaviors, with regression defined as at least two consecutive negative Pap smears and normal colposcopy.
Women's age, initial biopsy results, and human papillomavirus (HPV) genotypes were included in the multivariate models for adjustments. Our study subjects included 258 never-smokers and 258 smokers (179 current and 79 former smokers).
During a mean follow-up time of 39.8 months, 320 lesions regressed to normal cytology. Probability of regression within 2 years was significantly lower in smokers than in never-smokers (55.0%vs 68.8%, P = 0.004). The risk of LSIL persistence increased with smoking intensity and duration and with younger age at starting smoking (P = 0.003, P < 0.001, and P = 0.03, respectively). Smokers had twice as high a risk of persistent HPV infection compared to never-smokers (odds ratio, 2.50; 95% confidence interval, 1.30-4.81; P = 0.006). In young women, passive smoking since childhood reduced probability of regression within 2 years (56.7%vs 85.9%, P < 0.001). Further adjustments for a wide range of cervical cancer risk factors did not change the findings.
In conclusion, tobacco smoking may interfere with regression of cervical precursor lesions. Childhood exposure to second-hand smoke may increase a risk of persistent cervical abnormalities among young women.
PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/20626752
Cholinergic signaling through nicotinic acetylcholine receptors stimulates the proliferation of cervical cancer cells: an explanation for the molecular role of tobacco smoking in cervical carcinogenesis?
International Journal of Cancer. March 1, 2009, Volume 124(5), Pages 1090-1096.
Calleja-Macias IE, Kalantari M, Bernard HU.
Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA.
We have analyzed the expression of mRNAs encoding nicotinic acetylcholine receptors (nAChRs) in CaSki, SiHa and HeLa cell lines, which are derived from two squamous and one adenocarcinoma of the cervix, respectively. We detected with reverse transcription-polymerase chain reaction mRNAs for ten of the 16 nAChR subunits, namely strong signals for alpha-5, alpha-7, alpha-9, beta-1 and epsilon, and weak signals for alpha-4, beta-2, beta-4, gamma and delta. We confirmed the translation of alpha-5 and beta-1, corresponding to the two strongest RNA signals, in SiHa and HeLa cells by Western blotting, and the localization of these proteins to the plasma membrane by immunofluorescence.
The beta-1 subunit was detected membrane-associated in normal and neoplastic squamous epithelia of the cervix in situ, but appeared to be absent from the underlying mesenchyme and even from adjacent columnar epithelia. These observations suggest that normal and neoplastic cervical squamous epithelial cells express several combinations of the pentameric nAChRs. We also measured that the proliferation of SiHa and HeLa cells is stimulated by nicotine. This indicates that cholinergic signaling under normal physiological conditions and stimulated by nicotine in tobacco users affects epithelial homeostasis and neoplastic progression at the cervix in a way similar to the known effects on epithelia of the mouth, the airways and the lung.
Since tobacco smoking is established as a risk factor in cervical carcinogenesis, and since nicotine and its derivatives become concentrated in cervical mucus, nAChR-dependent signaling is apparently an important molecular cofactor of human papillomavirus-dependent cervical carcinogenesis.
PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/19048619
Gene expression profiles in HPV-immortalized human cervical cells treated with the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.
Chemioco-Biological Interactions, February 12, 2009, Volume 177(3), Pages 173-180. Epub 2008 Nov 6.
Prokopczyk B, Sinha I, Trushin N, Freeman WM, El-Bayoumy K.
Department of Pharmacology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA. firstname.lastname@example.org
Human papillomavirus (HPV) infection is an established etiological factor for cervical cancer. Epidemiological studies suggest that smoking in combination with HPV infection plays a significant role in the etiology of this disease. We have previously shown that the tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is present in human cervical mucus. Here, we hypothesized that treatment of HPV-16-immortalized human ectocervical cells (Ecto1/E6E7) with NNK would alter the expression of genes involved in cellular transformation.
Ecto1/E6E7 cells were treated with water (vehicle control) alone or with 1 microM, 10 microM, and 100 microM of NNK in water for 12 weeks. The colony-forming efficiency increased following NNK treatment; the maximum effect was observed after 12 weeks with 100 microM NNK. Microarray analysis revealed that, independent of the dose of NNK, expression of 30 genes was significantly altered; 22 of these genes showed a dose-response pattern. Genes identified are categorized as immune response (LTB4R), RNA surveillance pathway (SMG1), metabolism (ALDH7A1), genes frequently expressed in later stages of neoplastic development (MT1F), DNA binding (HIST3H3 and CHD1L), and protein biosynthesis (UBA52). Selected genes were confirmed by qRT-PCR. Western blot analysis indicates that phosphorylation of histone 3 at serine 10, a marker of cellular transformation, was up-regulated in cells treated with NNK.
This is the first study showing that NNK can alter gene expression that may, in part, account for transformation of HPV-immortalized human cervical cells. The results support previous epidemiological observations that, in addition to HPV, tobacco smoking also plays an important role in the development of cervical cancer.
PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/19038236
Up-regulation of vascular endothelial growth
factor-C by nicotine in cervical cancer cell lines.
American Journal of Reproductive Immunology, March 2005, Volume 53(3), Pages 153-158.
Lane D, Gray EA, Mathur RS, Mathur SP.
Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC 29425, USA.
PROBLEM: Smoking and infection with human papilloma virus (HPV) are major risk factors for cervical cancer. Our earlier work shows that nicotine enhances cellular proliferation of cervical cancer cell lines by up-regulating epidermal growth factor (EGF) and its receptor EGF-R, which leads to increased insulin-like growth factor II in vitro. We found that the vascular endothelial growth factor (VEGF)-C, one of the five isoforms of VEGF, may be specifically involved in lymphogenic metastasis of cervical cancer. This has prompted us to study if in vitro nicotine treatment will up-regulate VEGF-C alongside EGF-R levels, while down regulating the anti-proliferative transforming growth factor (TGF)-beta levels in HPV positive cervical cancer cell lines.
METHOD OF STUDY: Cervical cancer cell lines CaSki, HeLa and ME-180, were cultured in serum free DMEM medium for 24-hr, and treated with 10 ng/mL nicotine in the medium supplemented with 10% fetal bovine serum. A group of untreated cells served as controls. The cells were cultured in chamber slides (for immunofluorescent antibody assay) as well as microtiter plate wells (for BrdU cell proliferation assay). The cellular levels of VEGF-C, TGF-beta, EGF-R and HPV-E6 (early protein 6) were measured by a semi-quantitative immunofluorescent antibody assay. The cell proliferation and immunofluorescent assay data were analyzed by a Student's t-test.
RESULTS: Cell proliferation was significantly increased after nicotine treatment in all the cell lines. The VEGF-C levels were significantly increased, while TGF-beta levels were decreased by nicotine in all the cell lines (P < 0.00001). EGF-R levels were also significantly increased after nicotine treatment in HeLa and ME-180, while HPV-E6 levels remained unchanged in all three.
CONCLUSIONS: Nicotine up regulates expression of cell proliferative VEGF-C and EGF-R, while down-regulating anti-proliferative TGF-beta. Our data suggest that nicotine in circulation and in cervical squamous epithelial cells may promote not only rapid tumor growth but its lympho-angiogenic spread (VEGF-C) as well. It appears that nicotine does not promote HPV spread in the cervical cancer cells.
PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/15727570
Effect of nicotine abuse on treatment results
in primary irradiated cervical cancer
[Article in German]
Geburtshilfe Frauenheilkd. June 1986, Volume 46(6), Pages 388-390.
Kucera H, Enzelsberger H, Eppel W, Weghaupt K.
In view of the fact that frequent occurrence of cervical carcinoma in smokers is referred in literature, the authors examined the effects of cigarette smoking on primary irradiation therapy results in cervical carcinoma. Whereas of 410 patients with cervical carcinoma of stage I and II, 260 (63.4%) attained the 5-year limit, out of 115 smokers only 62 survived (53.9%). In the advanced cases of stage III and IV, on the other hand, the rates of cure achieved in patients who were habitual smokers were significantly poorer. Of 626 non-smokers with cervical carcinoma in stages III and IV, 212 survived (33.9%), whereas of 153 smokers only 31 (20.3%) were cured (p less than 0.01).
The incidence of side effects of primary irradiation was also distinctly higher in smokers than in non-smokers. Reversible complications occurred in 17.5% of the smokers and in 15.5% of the non-smokers. Severe irreversible changes occurred in 28% of smokers but in only 15.2% of the comparative group of non-smokers (p less than 0.01).
The noxious effects of smoking not only impaired the biological effectiveness of ionising radiation but also increased the incidence of side effects owing to deterioration of the regenerative capacity of the tissue surrounding the tumour.
PubMed Link: http://www.ncbi.nlm.nih.gov/pubmed/3744008