Correlation study of GAPDH, Bcl-2, and Bax protein immunoexpression in patients with colorectal adenocarcinoma

Abstract

Introduction: Colorectal cancer (CRC) is the third and second most commonly diagnosed cancer worldwide in males and females, respectively. Despite prominent progress in diagnosis and treatment, the recurrence rates are still high. A tumour hypoxic environment leads to an increase in glycolytic metabolism. The crucial intermediate component of glycolysis, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), could play a significant role in cancer progression. An increased level of GAPDH has been described in oncogene-induced transformation and anti-apoptotic function. In other studies, GAPDH has been involved in apoptosis induction.

Aim: We examined colorectal adenocarcinoma samples to assess the immunoexpression of GAPDH protein. We also evaluated the correlation between the expression of GAPDH protein and apoptotic parameters including expression of Bcl2 and Bax.

Material and methods: Paraffin sections were incubated for 60 min with primary antibody against GAPDH, Bcl-2, and Bax.

Results: Results of our study have shown that GAPDH expression in colorectal cancer is upregulated. We revealed significant positive correlation between expression of this protein and grade and size of tumour, and regional lymph node involvement. In the case of apoptosis-associated proteins, e.g. Bcl-2 and Bax, we found negative correlations between expression of these proteins and grade and size of tumour, lymphovascular invasion, and regional lymph node involvement. Finally, we demonstrated that GAPDH up-regulation is connected with down-regulation in Bcl-2 and Bax.

Conclusions: Up-regulation of GAPDH protein and down-regulation of Bcl-2 and Bax may result in increased of cancer.

Keywords: Bcl-2 proteins; apoptosis; colorectal cancer; glycolysis; hypoxia.

Figure 1

Representative examples of GAPDH (A–C), Bcl-2 (D, E) and Bax (F, G) protein immunoreactivity in G2 adenocarcinoma