CO(2) pneumoperitoneum induces in vitro hypoxic response culminating in apoptosis of human neuroblastoma cells

The ablative role of minimally invasive surgery (MIS) in neuroblastoma (NB) is still controversial due to the possible CO₂ pneumoperitoneum side-effects on tumor aggressiveness. It is known that CO₂ produces hypoxic condition with changes in tumor microenvironment influencing cell functions. Here we investigated whether CO₂ exposure affects the transcription factor HIF-1α and the apoptotic signalling pathway in SH-SY5Y NB cells. SH-SY5Y cells were exposed to a pressure of 15 mmHg CO₂ (100%) for 4 h (T0) and then moved to normal condition for 24 h (T₂₄). In control and CO₂ -exposed cells, we analyzed the mRNA levels and DNA binding activity of HIF-1α. We also evaluated the proliferative activity and cell viability as well as caspase-9/3 cleavage and nuclear fragmentation. A significant increase in HIF- 1α activation was observed in SH-SY5Y cells exposed to CO₂ compared to control cells. CO₂ treatment also decreased the proliferation rate and the percentage of viable cells. In addition, the expression and cleavage of caspase-9 and -3 were significantly increased in NB cells exposed to CO₂. These data correlated with apoptotic feature observed in CO₂ -treated NB cells. Our findings show that CO₂ -induced hypoxic condition exerts cytotoxic effects on NB cells by eliciting mitochondrial apoptotic pathway and thereby improving the understanding of the possible clinical impact of CO₂ pneumoperitoneum on NB behaviour.