Low Levels of GSTA1 Expression Are Required for Caco-2 Cell Proliferation

Abstract

The colonic epithelium continuously regenerates with transitions through various cellular phases including proliferation, differentiation and cell death via apoptosis. Human colonic adenocarcinoma (Caco-2) cells in culture undergo spontaneous differentiation into mature enterocytes in association with progressive increases in expression of glutathione S-transferase alpha-1 (GSTA1). We hypothesize that GSTA1 plays a functional role in controlling proliferation, differentiation and apoptosis in Caco-2 cells. We demonstrate increased GSTA1 levels associated with decreased proliferation and increased expression of differentiation markers alkaline phosphatase, villin, dipeptidyl peptidase-4 and E-cadherin in postconfluent Caco-2 cells. Results of MTS assays, BrdU incorporation and flow cytometry indicate that forced expression of GSTA1 significantly reduces cellular proliferation and siRNA-mediated down-regulation of GSTA1 significantly increases cells in S-phase and associated cell proliferation. Sodium butyrate (NaB) at a concentration of 1 mM reduces Caco-2 cell proliferation, increases differentiation and increases GSTA1 activity 4-fold by 72 hours. In contrast, 10 mM NaB causes significant toxicity in preconfluent cells via apoptosis through caspase-3 activation with reduced GSTA1 activity. However, GSTA1 down-regulation by siRNA does not alter NaB-induced differentiation or apoptosis in Caco-2 cells. While 10 mM NaB causes GSTA1-JNK complex dissociation, phosphorylation of JNK is not altered. These findings suggest that GSTA1 levels may play a role in modulating enterocyte proliferation but do not influence differentiation or apoptosis.

Glutathione S-transferase A1 mediates nicotine-induced lung cancer cell metastasis by promoting epithelial-mesenchymal transition

“…Previous studies have demonstrated that GSTA1 overexpression protects tumor cells from doxorubicin and reactive oxygen species-induced apoptosis (31)(32)(33)(34). GSTA1 also serves a role in regulating the proliferation of Caco-2 cells (35). Recently, it has been demonstrated that GSTA1 promotes the proliferation of lung cancer cells (15).…”

Glutathione S-transferase A1 suppresses tumor progression and indicates better prognosis of human primary hepatocellular carcinoma

“…Eight isoforms of cytosolic-soluble GSTs have been recognized in humans, including α, κ, μ, π, σ, θ, ζ, and ω 3,4 . Glutathione S-transferase α1 (GSTA1, Gene ID: 2938) has shown both stimulatory [5][6][7][8] and inhibitory effects [9][10][11][12] on tumorigenesis. The association between genetic polymorphism of GSTA1 and susceptibility to cancer has been discussed in previous studies [13][14][15] , but…”

Genetically Modified Caco-2 Cells With Improved Cytochrome P450 Metabolic Capacity

“…ALP1 and VIL1 are established markers for enterocyte differentiation and have been used previously to assess Caco-2 differentiation. 17,35,36 Their expression was significantly higher already before differentiation in the modified sublines than in wild-type Caco-2 cells, and increased 1.5-to 4-fold in all cell types during differentiation in culture. The enhanced expression of ALP1 and VIL1 suggests that introduction of chimeric NRs can stimulate Caco-2 differentiation toward an enterocytic phenotype.…”