Verotoxins induce apoptosis in human renal tubular epithelium derived cells

Abstract

Apoptosis mediated by verotoxins (VTs) has been identified in a renal carcinoma cell line, ACHN cells, which are an in vitro model of renal tubular epithelial cells. ACHN cells express the renal tubular marker CD24 as well as globotriaosyl ceramide/CD77, the receptor for VTs. VT binding to the ACHN cell surface was confirmed by positive staining with antibodies to the VTs. Treatment of ACHN cells with VTs induced prompt growth inhibition and cell death, and fragmentation of the genomic DNA in cells, typical of apoptosis, was observed. The expression of apoptotic antigen 7A6 detected by APO2.7 antibody in ACHN cells further supports the occurrence of apoptosis as a result of VT treatment. Cycloheximide enhanced VT-mediated apoptosis of ACHN cells, suggesting a strong correlation between the inhibition of protein synthesis and VT-mediated apoptosis. Moreover, tumor necrosis factor-alpha had a synergistic effect on VT-mediated apoptosis in ACHN cells. Considering the above evidence together with the clinical evidence showing the presence of apoptosis in the renal epithelium of a HUS patient, our results suggest a VT-induced apoptotic mechanism in normal renal tubular epithelium that may contribute to the pathogenesis of hemolytic uremic syndrome.

Verotoxin (Shiga Toxin) Sensitizes Renal Epithelial Cells to Increased Heme Toxicity

“…Moreover, VT also led to exacerbation of hemininduced injury in microvascular endothelial cells ( Figure 3C). Although VT caused apoptosis of ACHN cells, in agreement with an earlier report (10), the mechanism of heme-induced cytotoxicity is not well understood. Cell death due to oxidative injury as well as oxidative stress-independent hemin toxicity has been described (21).…”

“…Cells were detached with 0.025% trypsin-EDTA and used through passages 5 to 7. ACHN (8,10,32) and HMVEC (11,12,33) have been previously shown to express Gb3 on their surface and to be sensitive to VT-induced cytotoxicity.…”

“…Cultured mammalian cells differ markedly in their susceptibility to verotoxin (VT) cytotoxicity (6). For example, in renal tubular epithelial (10) and microvascular endothelial cells (11,12), VT induces programmed cell death, whereas other tissues exhibit toxinmediated cell activation (13,14). Ex vivo studies on renal biopsy and autopsy samples from children with acute Escherichia coli-induced HUS revealed evidence of apoptosis, predominantly in tubules (9,15,16) as well as necrotic injury, in both renal parenchyma and the gut (17).…”

Characterization of a Shiga‐Toxin 1‐Resistant Stock of Vero Cells

“…For example, the reason Stx is also called verotoxin is that it was first discovered as a novel cytotoxin toward Vero cells, which were derived from the kidneys of African green monkeys and express Gb3Cer (14). Burkitt's cell lines, such as Daudi (18) and renal-carcinoma-derived ACHN cells (34,35), have also been reported to express Gb3Cer and to be highly sensitive to Stx.…”

Study on induction of apoptosis on HeLa and Vero cells by recombinant shiga toxin and its subunits

“…In addition to having a direct effect on protein synthesis, protein toxins can also induce DNA cleavage and cause apoptosis-like changes in cells (Jones et al 2000;Suzuki et al 2000). Accumulated evidence suggests that Stx also induces apoptosis in several cell lines including Vero (Inward et al 1995), Burkitt's lymphoma (Mangeney et al 1993), ACHN; human renal tubular epithelium-derived cell (Taguchi et al 1998) and astrocytoma , although the precise mechanisms of Stx-induced apoptotic signal pathways remain unclear (Nicholson 1999). Moreover, cell type specificity for the apoptotic signaling pathway has been demonstrated (Jones et al 2000).…”