Study of tobacco habits and alterations in enzymatic antioxidant system in oral cancer.
OBJECTIVE
Tobacco is a major etiological factor for oral cancer development, accounting 30-40% of all cancer cases in India. Tobacco consumption generates free radicals and causes oxidative damages. In order to counteract these lethal effects, normal living cells have multiple antioxidant defense systems in a cascade manner. Thus, it seems that studying biological parameters, like antioxidant enzyme system, may be helpful in risk assessment and early diagnosis of oral cancer. Therefore, we analyzed erythrocytic and tissue antioxidant enzyme activities in terms of glutathione-S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and plasma thiol levels.


METHODS
Study included healthy controls with no habit of tobacco (NHT, n = 25), controls with habit of tobacco (WHT, n = 31) and oral cancer patients (n = 52). All the parameters were analyzed with highly sensitive and specific spectrophotometric methods.


RESULTS
Erythrocytic SOD and plasma thiol levels were significantly lower (p = 0.03), while GPx and CAT levels were higher (p = 0.017) in WHT as compared to NHT. No significant changes in GST and GR levels were observed between NHT and WHT. GST, GR, SOD and CAT activities were significantly higher (p = 0.05, p < 0.001, p = 0.003 and p < 0.001, respectively) while GPx and thiol levels were lower (p = 0.035 and p < 0.001, respectively) in oral cancer as compared to WHT. Odds ratio for erythrocytic GR, SOD, CAT and plasma thiol showed significantly higher risk of oral cancer development in WHT. Mean levels of SOD and CAT were increased, while GPx and thiol were decreased with the increase in habit duration in oral cancer. GST, GR and SOD activities were significantly higher (p = 0.0001, p = 0.005 and p = 0.005, respectively), while, CAT and thiol levels were lower (p = 0.0001 and p = 0.015, respectively) in malignant tissues as compared to adjacent normal tissues.


CONCLUSIONS
The data revealed that evaluation of antioxidant enzyme activities and thiol levels in WHT can be helpful to identify individuals at a higher risk of oral cancer development
Patel
Beena P
BP
Biochemistry Research Division, The Gujarat Cancer & Research Institute, Asarwa, Ahmedabad, India. gcriad1@sancharnet.in
Rawal
Upendra M
UM
Shah
Pankaj M
PM
Prajapati
Jayesh A
JA
Rawal
Rakesh M
RM
Dave
Tina K
TK
Patel
Prabhudas S
PS
D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000201:enzymology; D002374:Catalase / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000201:enzymology; D009062:Mouth Neoplasms / Q000175:diagnosis* / Q000201:enzymology*; D009367:Neoplasm Staging; D011230:Precancerous Conditions / Q000175:diagnosis / Q000378:metabolism*; D012680:Sensitivity and Specificity; D012907:Smoking; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D013438:Sulfhydryl Compounds; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005982:Glutathione Transferase