Differential effects of proton pump inhibitors and vonoprazan on vascular endothelial growth factor expression in cancer cells.

Proton pump inhibitors (PPIs) are potent inhibitors of gastric acid secretion, used as first-line agents in treating peptic ulcers. However, we have previously reported that PPIs may diminish the therapeutic effect of anti-vascular endothelial growth factor (VEGF) drugs in patients with cancer. In this study, we explored the effects of vonoprazan, a novel gastric acid secretion inhibitor used for the treatment of peptic ulcers, on the secretion of VEGF in cancer cells and attempted to propose it as an alternative PPI for cancer chemotherapy. The effects of PPI and vonoprazan on VEGF expression in cancer cells were compared by real-time reverse transcription-polymerase chain reaction and ELISA. The interaction of vonoprazan and PPIs with transcriptional regulators by docking simulation analysis. In various cancer cell lines, including the human colorectal cancer cell line (LS174T), PPI increased VEGF messenger RNA expression and VEGF protein secretion, while this effect was not observed with vonoprazan. Molecular docking simulation analysis showed that vonoprazan had a lower binding affinity for estrogen receptor alpha (ER-α), one of the transcriptional regulators of VEGF, compared to PPI. Although the PPI-induced increase in VEGF expression was counteracted by pharmacological ER-α inhibition, the effect of vonoprazan on VEGF expression was unchanged. Vonoprazan does not affect VEGF expression in cancer cells, which suggests that vonoprazan might be an alternative to PPIs, with no interference with the therapeutic effects of anti-VEGF cancer chemotherapy.

I.p.-injected cationic liposomes are retained and accumulate in peritoneally disseminated tumors.

Intraperitoneal (i.p) chemotherapy is an attractive approach to treat peritoneally disseminated cancers by delivering therapeutic agents directly to the peritoneal cavity where some disseminated tumors are located. Cationic liposomes (CLs) have been used as a viable delivery carrier for i.p. chemotherapy to improve the peritoneal retention of anticancer agents. However, there are no reports on the fate of CLs following i.p. administration to the peritoneal cavity in the presence of disseminated tumors. We prepared a tumor xenograft murine model of peritoneally disseminated gastric cancer by i.p. inoculation of human gastric cancer cells and followed the fate of either CLs or PEGylated CLs (PEG-CLs) after i.p. injection in the model. I.p.-injected CLs were retained in peritoneal cavity for at least 3 days post-injection as a result of clustering with ascites fluid proteins, mainly albumin, while i.p. PEG-CLs was rapidly cleared from the peritoneal cavity to the circulation within 3 h post-injection. Importantly, i.p. CLs efficiently accumulated in the targeted disseminated tumor cells, but not in other abdominal organs including liver, spleen, and kidney. The tumor selectivity upon i.p. administration of CLs may be associated with the lymphatic drainage system. A lipoplex formulation composed of CLs with short hairpin RNA (shRNA) against luciferase, a model therapeutic agent, suppressed luciferase activity in peritoneally disseminated tumors by 80%, with no cytokine secretion in serum. This suggests that i.p. CLs can efficiently deliver a therapeutic agent to peritoneally disseminated tumors with few systemic adverse events. These results suggest that i.p. treatment with CLs or non-PEGylated lipoplexes may be a promising approach for the treatment of peritoneally disseminated cancers through their ability to selectively deliver therapeutic agents to i.p. target sites with minimal systemic adverse events.