Cytokine-based
cancer therapies have attracted a great deal of attention in recent years. Unfortunately, resistance to treatment limits the efficacy of these
therapeutics. Therefore, the aim of our study was to explore the mechanism of IL-2-based
therapy for
hepatocellular carcinoma in an attempt to increase the efficiency of this treatment option.
METHODS: HepG2 cells were treated with
IL-2. Then,
siRNA against TZA was used to transfected into HepG2 cells. Cellular apoptosis was measured via MTT assay, TUNEL assay and
caspase-3 activity. Cellular proliferation was evaluated via EdU assay and western blotting. Cellular migration was detected via Transwell assay. Mitochondrial function was monitored by mitochondrial potential analysis, ROS staining, immunofluorescence and western blotting. Pathway blocker and activator were used to establish the role of JNK/
F-actin/mitochondrial fission signaling pathway in HepG2 cells stress response.
RESULTS: Our study found that
IL-2 treatment significantly reduced the viability, mobility and proliferation of HepG2 cells in vitro. We also demonstrated that
IL-2 treatment was accompanied by an increase in the expression of transcriptional co-activator with PDZ-binding motif (TAZ). Interestingly, genetic ablation of TAZ in the presence of
IL-2 further promoted apoptosis, inhibited mobility, and arrested proliferation in HepG2 cells. At the molecular level,
IL-2 administration activated excessive mitochondrial fission via the JNK/
F-actin pathway; these effects were further enhanced by TAZ deletion. Mechanistically, TAZ knockdown further increased the expression of mitochondrial fission-related
proteins such as Drp1, Mff and Fis. The augmented mitochondrial fission stimulated ROS overproduction, mediated redox imbalance, interrupted mitochondrial energy generation, reduced mitochondrial membrane potential, promoted leakage of the pro-apoptotic molecule cyt-c into the nucleus, and initiated caspase-9-related mitochondrial death. Further, we demonstrated that the anti-proliferative and anti-metastatic effects of
IL-2 in HepG2 cells were enhanced by TAZ deletion, suggesting that
IL-2 sensitizes HepG2 cells to IL-2-based
cytokine therapy. However, JNK/
F-actin pathway blockade could abrogate the inhibitory effects of TAZ deletion on HepG2 migration, proliferation and survival.
CONCLUSIONS: Taken together, our data indicate that the anti-
tumor effects of IL-2-based
therapies may be enhanced by TAZ deletion in a JNK/
F-actin pathway-dependent manner. This finding provides a novel combinatorial therapeutic approach for treating
hepatocellular carcinoma that might significantly increase the efficacy of
cytokine-based
therapies in a clinical setting.