ROS-Sp1 axis is involved in thermochemotherapy-enhanced sensitivity of pancreatic cancer cells to gemcitabine

Gemcitabine (GEM)-based chemotherapy represents the first choice for locally unresectable advanced pancreatic cancer, while the benefit is limited due to acquired chemoresistance or drug delivery insufficiency. Hyperthermia treatment potentially improves the clinical efficacy of GEM. However, the underlying mechanism is incompletely revealed. Our study aims to investigate the effect and involved mechanism of thermochemotherapy on cell survival. Pancreatic cancer cells PANC-1 and ASPC-1 were either treated with GEM or thermochemotherapy, then cell viability, apoptosis, migration, invasion, reactive oxygen species (ROS) production, and Sp1 expression were evaluated. The results showed that GEM dose and time-dependently affected cell viability, and 30 μM GEM achieved favorable effect in suppressing cancer cell growth. Meanwhile, hyperthermia preconditioning (43°C for 60 min) 24 h before GEM treatment yielded superior effect than other treatment sequence. GEM caused significant cell apoptosis and proapoptotic genes of both cancer cells, and thermochemotherapy further promoted apoptosis and genes transcription, accompanied by excessive ROS production. Thermochemotherapy was superior to GEM in suppressing cell migration and invasion of pancreatic cancer cells. Meanwhile, GEM significantly reduced Sp1 mRNA and protein and its downstream gene Cox-2, and thermochemotherapy further suppressed their expressions. ROS elimination with N-acetyl-l-cysteine notably neutralizes the suppressive effect of GEM and thermochemotherapy on cell growth and expressions of Sp1 and Cox-2. In conclusion, thermochemotherapy inhibited pancreatic cell viability, migration and invasion, and promoted cell apoptosis by inducing excessive ROS production, which subsequently suppressed Sp1 expression and the downstream Cox-2.