Smad3 mutant mice develop colon cancer with overexpression of COX-2

Abstract

Colon cancer is the second most common cause of cancer-associated mortality in human populations. The aim of the present study was to identify the role of cyclooxygenase-2 (COX-2) in Smad3 mutant mice, which are known to develop colon cancer. Homozygous Smad3 (-/-) mutant mice were generated from inbred and hybrid Smad3 mouse strains by intercrossing the appropriate heterozygotes. Immunohistochemistry with COX-2 antibody was performed throughout this experiment and the data was validated and cross-checked with reverse transcription-polymerase chain reaction (RT-PCR). Homozygous mutant Smad3 mice were generated and the overexpression pattern of COX-2 was identified by immunohistochemistry and validated with RT-PCR. The results of the present study demonstrated a link between the Smad3 mutant mice, colon cancer and COX-2. In addition, the overexpression pattern of COX-2 in Smad3 mutant mice that develop colon cancer was identified.

Keywords: Smad3; colon cancer; cyclooxygenase-2; p53.

Figure 1.

The expression pattern of Smad3 in normal and homozygous mutant Smad3 (−/−) mice was identified by whole-mount in situ hybridization of embryos at day 11.5 (A) Whole mount in situ hybridization of control E11.5 embryo taken from a healthy mouse. (B) Whole mount in situ hybridization of homozygous mutant Smad3 mouse E11.5 embryo. (C) Whole mount in situ hybridization of control colon taken from a healthy mouse. (D) Whole mount in situ hybridization of homozygous mutant Smad3 mouse colon. Representative images from three replicate experiments are presented here.

Figure 2.

Immunohistochemistry with anti-COX-2 antibodies. (A) Few COX-2-positive cells were noted in the control tissue section. (B) COX-2 overexpression was observed in homozygous mutant Smad3 mouse tissue. Positive cells are indicated by brown staining. Representative images from three replicate experiments are presented here. Magnification, ×20. COX-2, cyclooxygenase-2.

Figure 3.

Reverse transcription-polymerase chain reaction analysis. Overexpression profile of COX-2 with Smad3, P53 (along with the control β-actin) in the control and homozygous mutant Smad3 mice. Representative blots from three replicate experiments are presented here. COX-2, cyclooxygenase-2.