Expression of Metallothionein after Administration of Aspirin, Vitamin C or Zinc Supplement in the DMH Induced Colon Carcinoma in Rat

Document Type: Research Articles

Authors

1 Department of Clinical Biochemistry, Christian Medical College, Vellore, Tamil Nadu, India.

2 Department of Neuropathology, Christian Medical College,Vellore, Tamil Nadu, India.

3 Department of G.I. Sciences,Christian Medical College Vellore,Tamil Nadu, India.

4 Department of General Surgery, Christian Medical College,Vellore, Tamil Nadu, India.

Abstract

Background: Chemoprevention refers to the use of specificnatural or synthetic chemical agents to suppress the
development and progression to carcinoma. The purpose of this study was to assess the effect of aspirin, vitamin C
or zinc on the metallothionein (MT) mRNA gene expression as well as MT protein content byimmunohistochemistry
andradioimmunoassay (RIA) in 1, 2-dimethyl hydrazine (DMH) induced cancerous colonic tissuein rats. Methods:
Rats were randomly divided into three groups, group 1 (aspirin), group 2 (vitamin C) group 3 (zinc), each of which
was further sub divided into two groups and given subcutaneous injections of DMH (30 mg/kg body weight) twice a
week for 3 months and sacrificed at either 4 months (A-precancer model) or at 6 months (B-cancer model).The control
groups were administered 0.5 ml saline subcutaneously. All the 3 groups were simultaneouslyadministered aspirin,
vitamin Cor zinc supplement respectively from the beginning till the end of the study. Results: It was observed that
rats co-treated with aspirin, vitamin C or zinc resulted in a significant increase in the colonic MT mRNA expression in
the precancer and cancer model as compared to the saline only controls. MT protein expression showed a 60%, 64%
and 78% immunopositivity in the co-treated groups respectively.The mean MT content in the precancer and the cancer
model was restored to near normal levels in all the three co-treated groups. Conclusion: These results suggest that
co-administration of aspirin, vitamin C or zinc resulted in a significant increase in MT mRNA gene expression, MT
protein expression and MT protein content which could possibly be one of the reasons for a chemo protective effect
against progression to colonic cancer in a chemically induced DMH model in rat.Zinc supplement had a greater effect
on metallothionein expression than aspirin or vitamin C.

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