Nicotine induces the fragile histidine triad methylation in human esophageal squamous epithelial cells

Abstract

The fragile histidine triad (FHIT) gene has been proposed to have an important role in very early carcinogenesis. Methylation of the FHIT gene is associated with transcriptional inactivation in esophageal squamous cell carcinoma, and FHIT inactivation has been linked to smoking-related carcinogenesis. In this study, we confirmed methylation of the FHIT gene in human esophageal squamous epithelial cells (HEECs) and examined whether nicotine induced alteration of FHIT. Methylation status in the promoter region of the FHIT gene and p16 INK4A gene was determined by methylation-specific PCR in HEECs exposed to nicotine under various conditions. Methylation status of the FHIT gene was confirmed by DNA-sequencing analysis. The development of human cancer is generally considered a multistep process involving multiple genetic or epigenetic changes. Epigenetic changes such as aberrant DNA methylation are an alternative way to inactivate tumor suppressor genes (TSGs) and may have important roles in the development of esophageal cancer 1,2 DNA methylation patterns are established and maintained by 3 DNA methyltransferases (DNMTs): DNMT1, DNMT3a and DNMT3b. 3,4 DNMT1 has traditionally been regarded as a maintenance methyltransferase that specifically copies DNA methylation patterns after DNA replication. 5 In contrast, DNMT3a and DNMT3b are implicated primarily in de novo methylation. 6,7 Recent studies have localized the fragile histidine triad (FHIT) gene at 3p14.2, 8 considered a candidate TSG. FHIT is inactivated during the development of precancerous lesions of various types. 9,10 We have previously confirmed promoter methylation of the TSG p16 11 and FHIT 12 in esophageal squamous cell carcinoma (ESCC) cell lines established at our department. 13 Pekarsky et al. suggested that FHIT inactivation occurs very early in the development of carcinogen-induced tumors. Carcinogens from cigarette smoke and other sources cause deletions in the FHIT locus, leading to the loss of Fhit protein expression. Then, cells lacking FHIT expression presumably acquire growth advantages, proliferate, alter p16, p53, or other genes, and form precancerous lesions. 14 Therefore, inactivation of FHIT may be a downstream effect of defects in DNA repair machinery. Such inactivation may be a very early event in carcinogenesis, even preceding alteration of p16 INK4A . 14,15 The etiology of ESCC is strongly linked to the inactivation of FHIT or p16, as well as to cigarette smoking. 16,17 Considerable information on molecular abnormalities potentially related to cigarette smoking is now available. For example, FHIT gene abnormalities have been associated with a history of smoking in patients with malignant tumors, 18 and tobacco smoking has been linked to promoter methylation in p16 10 or FHIT. 14 Nicotine is the major addictive agent in tobacco, 19 and addicted individuals continue to smoke and use tobacco products to maintain plasma nicotine levels. Although studied extensively, nicotine has not been proven to be carcinogenic. However, researchers ha...

Modifiable Risk Factors for Colorectal Neoplasms and Hyperplastic Polyps

“…Morimoto et al (15) and Shrubsole et al (16) (30) and that tobacco smoking is associated with hypermethylation of TSG in nonsmall cell lung cancer (31). Chan et al (32) We found ten studies (1,5,7,10,12,13,16,29,33,34) regarding the association between ethanol consumption and colon polyps where all polyps were diagnosed by full colonoscopy.…”

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone Induces Retinoic Acid Receptor β Hypermethylation through DNA Methyltransferase 1 Accumulation in Esophageal Squamous Epithelial Cells

“…Tobacco contains more than 60 carcinogens (Hoffmann et al, 1990;Hecht et al, 2006) and tobacco exposure is known to induce genetic and epigenetic changes in esophageal squamous and lung cancer cells (Hecht et al, 1999;Soma et al, 2006;Liu et al, 2007;Lin et al, 2010;Huang et al, 2011). NNK is a key ingredient of tobacco smoke carcinogens.…”

Transgenerational Effects of Maternal Nicotine Exposure During Gestation and Lactation on the Respiratory System

“…This may result in changes in the genetic "program" that controls lung development, maintenance of lung structure and aging of lung tissue, which may render the lungs more prone to disease. Since nicotine is associated with DNA methylation [35], it is possible that it may change the program that is maintaining homeostasis in the developing lung in the long term and in this way contribute to the adult onset of diseases. In addition, a product of nicotine metabolism is nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) which induces DNA damage which is associated with an increase in mutational events [36].…”