Inhibition of nitric oxide-induced apoptosis by nicotine in oral epithelial cells

Abhijit G. Banerjee, Velliyur K. Gopalakrishnan, Jamboor K. Vishwanatha

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Development of oral cancer is clearly linked to the usage of smokeless tobacco. The molecular mechanisms involved in this process are however not well understood. Toward this goal, we investigated the effect of smokeless tobacco exposure on apoptosis of oral epithelial cells. Exposure of oral epithelial cells to smokeless tobacco extract (STE) induces apoptosis in a dose-dependent manner, until a threshold level of nicotine is achieved upon which apoptosis is inhibited. 1 mM of nicotine is able to inhibit apoptosis significantly induced by STE in these oral cells. Exposure of cells to nicotine alone has no effect on apoptosis, but nicotine inhibits apoptosis induced by other agents present in STE. In this study we show that, the anti-apoptotic action of nicotine is specifically associated with down-regulation of nitric oxide (NO) production. Using specific inducers of NO, we have demonstrated that inhibition of apoptosis by nicotine is through down-regulation of NO production. Further, we observed that nicotine clearly acts as a sink of NO radicals, shown using peroxynitrite generator (SIN-1) in conjunction or absence of radical scavengers. Nicotine thus causes most damage in transformed epithelial cells as depicted by accumulation of nitrotyrosine in a 3-NT ELISA assay. Inhibition of apoptosis is a hallmark in tumor progression and propels development of cancer. It may further result in functional loss of apoptotic effector mechanisms in the transformed cells. Thus, our data clearly indicates that inhibition of NO-induced apoptosis by nicotine may lead to tobacco-induced oral carcinogenesis, and implies careful development of modalities in tobacco cessation programs.

Original languageEnglish
Pages (from-to)113-121
Number of pages9
JournalMolecular and Cellular Biochemistry
Volume305
Issue number1-2
DOIs
StatePublished - 1 Nov 2007

Fingerprint

Nicotine
Smokeless Tobacco
Nitric Oxide
Epithelial Cells
Apoptosis
Tobacco
Down-Regulation
Tobacco Use Cessation
Inhibition (Psychology)
Peroxynitrous Acid
Mouth Neoplasms
Tumors
Assays
Neoplasms
Carcinogenesis
Enzyme-Linked Immunosorbent Assay

Keywords

  • 3-NT
  • Apoptosis
  • Fibroblasts
  • HCPC-1
  • Inhibition
  • Nicotine
  • Nitric oxide
  • Nitrotyrosination
  • Oral epithelial cells
  • Peroxynitrite radical
  • RPDL
  • Reactive oxygen species

Cite this

Banerjee, Abhijit G. ; Gopalakrishnan, Velliyur K. ; Vishwanatha, Jamboor K. / Inhibition of nitric oxide-induced apoptosis by nicotine in oral epithelial cells. In: Molecular and Cellular Biochemistry. 2007 ; Vol. 305, No. 1-2. pp. 113-121.
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Inhibition of nitric oxide-induced apoptosis by nicotine in oral epithelial cells. / Banerjee, Abhijit G.; Gopalakrishnan, Velliyur K.; Vishwanatha, Jamboor K.

In: Molecular and Cellular Biochemistry, Vol. 305, No. 1-2, 01.11.2007, p. 113-121.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Inhibition of nitric oxide-induced apoptosis by nicotine in oral epithelial cells

AU - Banerjee, Abhijit G.

AU - Gopalakrishnan, Velliyur K.

AU - Vishwanatha, Jamboor K.

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AB - Development of oral cancer is clearly linked to the usage of smokeless tobacco. The molecular mechanisms involved in this process are however not well understood. Toward this goal, we investigated the effect of smokeless tobacco exposure on apoptosis of oral epithelial cells. Exposure of oral epithelial cells to smokeless tobacco extract (STE) induces apoptosis in a dose-dependent manner, until a threshold level of nicotine is achieved upon which apoptosis is inhibited. 1 mM of nicotine is able to inhibit apoptosis significantly induced by STE in these oral cells. Exposure of cells to nicotine alone has no effect on apoptosis, but nicotine inhibits apoptosis induced by other agents present in STE. In this study we show that, the anti-apoptotic action of nicotine is specifically associated with down-regulation of nitric oxide (NO) production. Using specific inducers of NO, we have demonstrated that inhibition of apoptosis by nicotine is through down-regulation of NO production. Further, we observed that nicotine clearly acts as a sink of NO radicals, shown using peroxynitrite generator (SIN-1) in conjunction or absence of radical scavengers. Nicotine thus causes most damage in transformed epithelial cells as depicted by accumulation of nitrotyrosine in a 3-NT ELISA assay. Inhibition of apoptosis is a hallmark in tumor progression and propels development of cancer. It may further result in functional loss of apoptotic effector mechanisms in the transformed cells. Thus, our data clearly indicates that inhibition of NO-induced apoptosis by nicotine may lead to tobacco-induced oral carcinogenesis, and implies careful development of modalities in tobacco cessation programs.

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KW - Nitrotyrosination

KW - Oral epithelial cells

KW - Peroxynitrite radical

KW - RPDL

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EP - 121

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