Journal of Cancer Research and Therapeutics

: 2007  |  Volume : 3  |  Issue : 3  |  Page : 167--168

Serum total glutathione-s-transferase levels in oral cancer

Krishnananda Prabhu, Gopalakrishna P Bhat 
 Department of Biochemistry, Kasturba Medical College, Manipal - 576 104, Karnataka, India

Correspondence Address:
Krishnananda Prabhu
Department of Biochemistry, Kasturba Medical College, Manipal


We conducted a study wherein serum total glutathione-s-transferase levels were measured in patients (n = 27) with various stages of biopsy proven oral cancer (squamous cell carcinoma) and age and sex matched healthy human volunteers (n=10). In all patients with oral cancer, serum total glutathione-s-transferase was measured before the onset of treatment. There was a significant increase in serum total glutathione-s-transferse levels in patients with stage IV oral cancer as compared to stage II (P = 0.001) and stage III (P = 0.002) oral cancer. This shows that alterations in serum total Glutathione-s-transferase levels may have a role in cancer progression.

How to cite this article:
Prabhu K, Bhat GP. Serum total glutathione-s-transferase levels in oral cancer.J Can Res Ther 2007;3:167-168

How to cite this URL:
Prabhu K, Bhat GP. Serum total glutathione-s-transferase levels in oral cancer. J Can Res Ther [serial online] 2007 [cited 2022 Jul 6 ];3:167-168
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Oral cancer accounts for about 8% of all malignant growths. Men particularly over 40 years are affected twice as often as women. The exact cause is unclear but smoking, alcohol, tobacco chewing, poor oral hygiene, chronic irritation etc are implicated. Reactive oxygen species (ROS) like superoxide, hydrogen peroxide etc. have been implicated in many diseases including cancer. ROS have been known to play an important role in initiation and progression of multi-step carcinogenesis. [1] Alterations in circulating antioxidants and free radical scavengers like glutathione-s-trnasferase (GST) have been linked with various epithelial malignancies including oral cancer. [1],[2],[3],[4],[5],[6],[7],[8],[9] In this study, we evaluated the levels of serum total GST in oral cancer patients and healthy controls.


Reduced glutathione C 10 H 17 O 6 S and 1-chloro-2, 4, dinitro benzene (CDNB) were purchased from Sigma Chemical Company. All other reagents used were of Reagent grade. Deionized water was used throughout the study.

Permission for the study was granted by the Institutional Ethics Committee. Informed consent was taken from controls (healthy volunteers, n = 10) and patients (n = 27). The age of the subjects (n =37) was 56.41.67 yrs [Table 1]. All the patients were admitted for radiotherapy. In cases blood was withdrawn just before initiation of treatment.

Serum total GST levels were measured in biopsy proven cases of oral cancer (n=27) with biopsy showing moderate to well differentiated squamous cell carcinoma.


Serum GST was estimated by CDNB method. [10],[11],[12]


a. Phosphate Buffer: 0.1M, pH-6.5 prepared with deionized water and stored in brown bottle in refrigerator.

b. CDNB: 20 mM in 95% ethanol, stored in brown bottle in fridge.

c. GSH: 20mM in deionized water freshly prepared just before the assay.

d. Serum: Blood was collected without any anticoagulant and allowed to clot for 1h. Clotted sample was centrifuged at 3500 rpm 30 min at 4C (in cold centrifuge). Serum was separated and stored at 4C until use and assayed on the same day.


GST was estimated in 1ml of incubation mixture containing 850 l of 0.1 M phosphate buffer pH 6.5 and CDNB reagent (20 mM) 50 l, preincubated at 37C for 10 min. Reaction was started by adding 50 l of 20 mM GSH and 50 l of serum. Reaction was followed at 1 min interval for 5 min by measuring absorption at 340 nm. Simultaneously, blank was run by substituting deoinized water for serum. Then O.D change/min was calculated. GST was estimated by using the molar extinction coefficient [9.6 mM -1 cm -1 ] of GST. [11]



Statistical analysis

Kruskal Wallis test was used to analyze the results and it showed a significant difference ( P = 0.001). In case of significant difference, pair-wise comparison between control and various stages were done by Mann- Whitney Test adjusting a for the number of pairs to be compared. (significance at the level: 0.05/6 = 0.0083)

 Results and Discussion

Comparison of serum total GST between control and cancer patients using Kruskal Wallis showed a significant difference ( P = 0.001). However, the paired comparison between control and various groups by Mann Whitney did not show a significant difference.

ROS are tumorogenic by virtue of their ability to increase cell proliferation, survival, cellular migration and also by inducing DNA damage leading to genetic lesions that initiate tumorogenicity and sustain subsequent tumor progression. As shown by earlier studies, loss of antioxidant capacity of cell in early dysplasias can trigger initiation and progression of cancer. [13] Our results showed a decrease in serum total GST in early cancer than the control [Table 2] which may have triggered the initiation and progression of cancer. Many studies also showed progressive increase of GST with advancing cancer and has been associated with poor prognosis and development of drug resistance. [14],[15] In our study there was an increase in serum total GST in later stages of cancer. This enhanced antioxidant capacity made the tumor tissues less susceptible to oxidative stress conferring specific growth advantage. [16]


1Ahmed MI, Fayed ST, Hossein H, Tash FM. Lipid peroxidation and antioxidant status in human cervical carcinoma. Dis Markers 1999;15:283-91.
2Nagini S, Manoharan S, Ramachandran CR. Lipid peroxidation and antioxidants in oral squamous cell carcinoma. Clin Chim Acta 1998;273:95-8.
3Grignon DJ, Abdel-Malak M, Mertens WC, Sakr WA, Shepherd RR. Glutathione S-transferase expression in renal cell carcinoma: A new marker of differentiation. Mod Pathol 1994;7:186-9.
4Cao W, Zuo J, Meng Y, Wei Q, Shi ZH, Ju LM, et al. Anticancer drug resistance of HeLa cells transfected with rat glutathione S-transferase pi gene. Biomed Envion Sci 2003;16:157-62.
5Prabhu K, Bhat PG, Vasudevan DM. Can serum glutathione-s- transferase levels in carcinoma cervix be a predictor of radiation response? Indian J Clin Biochem 2005;20:95-7.
6Sabitha KE, Shyamaladevi CS. Oxidant and antioxidant activity changes in patients with oral cancer and treated with radiotherapy. Oral Oncol 1999;35:273-7.
7Rawal RM, Patel DD, Pate BP, Patel MM, Wadhwa MK, Patel PS, et al. Assessment of glutathione-s- transferase and glutathione reductase in patients with sqamous cell carcinoma of buccal mucosa. Int J Cancer 1999;83:727-31.
8Kobayashi Y. A study on diagnosis of oral squamous cell carcinoma (oral SCC) by glutathione S-transferase-pi (GST-pi). Kokubyo Gakkai Zasshi 1999;66:45-6.
9Townsend DM, Tew KD, Tapiero H. The importance of glutathione in human disease. Biomed Pharmacother 2003;57:145-55.
10Beutler E. Red cell metabolism. A manual of biochemical methods, 3 rd ed. Grune and Startron, Inc: London; 1984. p. 8-78.
11Habig WH, Pabst MJ, Jakoby WB. Glutathione-S-transferases: The first enzymatic step in mercapturic acid formation. J Biol Chem 1974;249:7130-9.
12Harvey JW, Beutler E. Binding of heme by glutathione-S-transferases - A possible role of erythrocyte enzyme. Blood 1982;60:1227-30.
13Herszenyi L, Hritz I, Pregun I, Sipos F, Juhasz M, Molnar B, et al. Alterations of glutathione-s-transferase and matrix metalloproteinase-9 expression are early events in esophageal carcinogenesis. World J Gastroenterol 2007;13:676-82.
14Hirata S, Odajima T, Kohama G, Ishigaki S, Niitsu Y. Significance of glutathione-s-transferase-pi as a tumor marker in patients with oral cancer. Cancer 1992;70:2381-7.
15Tew KD. TLK-286: A novel glutathione-s-transferase-activated prodrug. Expert Opin Investig Drugs 2005;14:1047-54.
16Kolanjiappan K, Ramachandran CR, Manoharan S. Biochemical changes in tumor tissues of oral cancer patients. Clin Biochem 2003;36:61-5.