Non-equilibrium atmospheric pressure plasma (NEAPP) has attracted attention in cancer therapy. We explored the indirect effect of NEAPP through plasma-activated medium (PAM) on pancreatic cancer cells in vitro and in vivo. In this study, four pancreatic cancer cell lines were used and the antitumor effects of PAM treatment were evaluated using a cell proliferation assay. To explore functional mechanisms, morphological change and caspase-3/7 activation in cells were also assessed. Furthermore, reactive oxygen species (ROS) generation in cells was examined and N-acetyl cysteine (NAC), an intracellular ROS scavenger, was tested. Finally, the antitumor effect of local injection of PAM was investigated in a mouse xenograft model. We found that PAM treatment had lethal effect on pancreatic cancer cells. Typical morphological findings suggestive of apoptosis such as vacuolization of cell membranes, small and round cells and aggregation of cell nuclei, were observed in the PAM treated cells. Caspase-3/7 activation was detected in accordance with the observed morphological changes. Additionally, ROS uptake was observed in all cell lines tested, while the antitumor effects of PAM were completely inhibited with NAC. In the mouse xenograft model, the calculated tumor volume on day 28 in the PAM treatment group was significantly smaller compared with the control group [28±22 vs. 89±38 (mm3 ± SD), p=0.0031]. These results show that PAM treatment of pancreatic cancer might be a promising therapeutic strategy.

Liver metastasis remains a serious problem in the management of gastric cancer (GC). Our aims were to identify through transcriptome analysis a molecule that mediates hepatic metastasis in GC, and to evaluate its potential as a diagnostic marker and a therapeutic target. The effects of knocking out a relevant molecule using genome editing were evaluated in vitro experiments and in mouse xenograft models. Expression levels of candidate molecule in 300 pairs of gastric tissues were determined to assess whether differentially expressed genes predicted hepatic recurrence, metastasis, or both. Transcriptome data identified the overexpression of synaptotagmin VII (SYT7) in GC tissues with hepatic metastasis. Its expression in the GC cell lines was high, particularly in those that exhibited a differentiated phenotype, and positively correlated with the expression of SNAI1 and TGFB3, and inversely with RGS2. SYT7 knockout inhibited the proliferation of GC cells, indicated by increased apoptosis with activated caspase and loss of mitochondria membrane potential, G2/M cell-cycle arrest and attenuated cell migration, invasion, and adhesion. The tumorigenicity of SYT7-knockout cells was moderately reduced in a mouse model of subcutaneous metastasis in which the levels of BCL2 and HIF1A were decreased and was more strikingly attenuated in a model of hepatic metastasis. The SYT7 levels in the primary GC tissues were significantly associated with hepatic recurrence, metastasis, and adverse prognosis. SYT7 represents a tool for prediction and monitoring of hepatic metastasis from GC as well as being a promising therapeutic target.

Plasma-activated liquids may represent a novel therapeutic method for the treatment of peritoneal metastases in gastric cancer.

Our study demonstrated the antitumor effects of PAL in vitro and in vivo. Intraperitoneal administration of PAL may be a novel therapeutic option for peritoneal metastases.

Lysyl oxidase (LOX) family genes, particularly lysyl oxidase-like protein 2 (LOXL2), have been implicated in carcinogenesis, metastasis, and the epithelial-to-mesenchymal transition (EMT) in various cancers. This study aimed to explore the clinical implications of LOXL2 expression in pancreatic cancer (PC) in the context of EMT status. LOX family mRNA expression was measured in PC cell lines, and LOXL2 protein levels were examined in surgical specimens resected from 170 patients with PC. Higher LOXL2 expression was observed in cell lines from mesenchymal type PC than in those from epithelial type PC. A significant correlation between LOXL2 expression and the EMT status defined based on the expression of E-cadherin and vimentin was observed in surgical specimens (P < 0.01). The disease-free survival and overall survival rates among patients with low LOXL2 expression were significantly better than those among patients with high LOXL2 expression (P < 0.001). According to the multivariate analysis, high LOXL2 expression (P = 0.03) was a significant independent prognostic factor for patients with PC. Additionally, LOX inhibition significantly decreased PC cell proliferation, migration, and invasion in vitro. In conclusion, LOXL2 expression is potentially associated with PC progression, and LOXL2 expression represents a biomarker for predicting the prognosis of patients with PC who have undergone complete resection.