Cisplatin-induced expression of Gb3 enables verotoxin-1 treatment of cisplatin resistance in malignant pleural mesothelioma cells

Abstract

BACKGROUND: A major problem with cisplatin treatment is the development of acquired-drug resistance of the tumour cells. Verotoxin-1 (VT-1) exerts its cytotoxicity by targeting the membrane glycolipid globotriasosylceramide (Gb3), a molecule associated with drug resistance. Cisplatin-and VT-1-induced apoptosis involves mitogen-activated protein kinase (MAPK) activation, and deactivation of MAPKs is associated with cisplatin resistance. This study aimed to investigate whether a sub-toxic concentration of VT-1 could enhance cisplatin-induced apoptosis and overcome acquired-cisplatin resistance in cultured cancer cell lines. METHOD: P31 and H1299 cells with corresponding cisplatin-resistant sub-lines (P31res/H1299res) were incubated with VT-1 and/or cisplatin followed by determination of Gb3 expression, cell viability, apoptosis, and signalling pathways. RESULTS: Cells from the resistant sub-lines had elevated Gb3 expression compared with the parental cell lines, and cisplatin further increased Gb3 expression, whereas VT-1 reduced the percentage of Gb3-expressing cells. Combination of cisplatin and sub-toxic concentrations of VT-1 led to a super-additive increase of cytotoxicity and TUNEL staining, especially in the cisplatin-resistant sublines. Blockade of Gb3 synthesis by a Gb3 synthesis inhibitor not only led to eradicated TUNEL staining of P31 cells, but also sensitised P31res cells to the induction of apoptosis by cisplatin alone. Cisplatin-and VT-1-induced apoptosis involved the MAPK pathways with increased C-Jun N-terminal kinase and MAPK kinase-3 and -6 phosphorylation. CONCLUSIONS: We show the presence of Gb3 in acquired-cisplatin resistance in P31res and H1299res cells. Cisplatin up-regulated Gb3 expression in all cells and thus sensitised the cells to VT-1-induced cytotoxicity. A strong super-additive effect of combined cisplatin and a sub-toxic concentration of VT-1 in cisplatin-resistant malignant pleural mesothelioma cells were observed, indicating a new potential clinical-treatment approach.

Targeting glucosylceramide synthase induction of cell surface globotriaosylceramide (Gb3) in acquired cisplatin-resistance of lung cancer and malignant pleural mesothelioma cells

“…PPMP, almost eradicated the induced cell surface Gb3-expression in resistant subline cells whereas cell surface MDR1 expression was reduced only in H1299 cells. It is noteworthy that silencing of Gb3 with PPMP augmented the sensitivity to cisplatin in cisplatin-resistant MPM subline cells possibly back to the cisplatin sensitivity of the parental cells as we previously demonstrated [27]. MDR1 expression was only decreased by cyclosporin in H1299.…”

“…Perhaps cell surface Gb3 reflects the functional resistance to cisplatin better than cell surface expression of MDR1. Therapy with GCS inhibitors reducing ceramide glycosylation or with Gb3 receptor-binding verotoxin-1 may overcome or reduce acquired cisplatin drug resistance in NSCLC and MPM [27].…”

“…The studies also suggested that cisplatin preferentially eradicates MPM cells with low Gb3 expression. The GCS activity inhibitor DL-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP), or a subtoxic concentration of the Gb3-receptor binding bacterial toxin verotoxin-1, resensitized Gb3-overexpressing cisplatin-resistant NSCLC and MPM subline cells to cisplatin [27].…”

Tumor-Specific Targeting of Pancreatic Cancer with Shiga Toxin B-Subunit

“…The pathophysiologic role of upregulated Gb 3 expression in tumors is still unclear (29,30). Recently published data show that cisplatin induces Gb 3 expression in cancer cells and that Gb 3 expression is linked to acquired cisplatin resistance (31). Moreover, increased Gb 3 levels were correlated to increased expression of multidrug resistant 1/permeability glycoprotein (MDR1/PgP), a glycoprotein involved in the biosynthesis of glycolipids such as Gb 3 (29).…”

Cisplatin Resistance in Malignant Pleural Mesothelioma

“…The MAPK pathway is involved in proapoptotic signalling of VT-1 in stressed cell systems and the pathway is also involved in cisplatin-induced apoptosis and induced cisplatin resistance (Salhia et al, 2002;Johansson et al, 2010). Targeting the MAPK signalling pathway could, therefore, be an additional way to reduce cisplatin-induced tumour cells resistance.…”