Cytotoxic Effect of Protoporphyrin IX to Human Leukemia U937 Cells under Ultrasonic Irradiation

Abstract

Background: Sonodynamic therapy (SDT) is an alternative strategy that manages malignancies via the generation of cytotoxic factors during ultrasound-activated sono-sensitive agents. However, the detailed mechanisms are not clear. This study was to identify the cytotoxic effects of ultrasound-activated protoporphyrin IX (PpIX) on U937 cells. Methods: Flow cytometry was performed to detect the time course for PpIX uptake in U937 cells. Sub-cellular localization of PpIX in U937 cells was visualized by inverted confocal laser scanning microscope. Following PpIX-mediated SDT treatment, cell viability was evaluated by the 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide (MTT) assay; nuclear damage was observed under fluorescent microscope; DNA fragmentation and mitochondrial membrane potential disruption were measured by flow cytometry. The role of reactive oxygen species (ROS) in SDT-induced cell death was also evaluated. Results: We observed that PpIX is mainly localized in the mitochondria, with a maximal uptake within 2 h. Compared with PpIX or ultrasound alone, PpIX plus ultrasound treatment significantly declined cell viability, caused more serious damage of cell morphology, DNA and mitochondria. In the combined treatment group, the intracellular ROS was greatly higher than in other groups; ROS scavenger N-acetylcysteine could effectively rescue the loss of mitochondria membrane potential and cell viability induced by SDT. Conclusion: Taken together, these findings primarily indicated that fatal damage could be induced by PpIX-mediated SDT in U937 cells, and the intracellular ROS was involved during this process.

Fra-1 is upregulated in lung cancer tissues and inhibits the apoptosis of lung cancer cells by the P53 signaling pathway

“…Cell apoptosis is closely related with a reduction in ΔΨm and an increase in intracellular ROS and Ca 2+ concentrations (33)(34)(35)(36)(37)(38). In this study, we found that overexpression of Fra-1 in lung cancer H460 cells, led to an increase in ΔΨm and a decrease in intracellular ROS and Ca 2+ concentrations.…”

An in vitro study on sonodynamic treatment of human colon cancer cells using sinoporphyrin sodium as sonosensitizer

“…SDT is a promising non-invasive anticancer therapeutic approach and relies on the cytotoxicity induced by the combination of a chemical sonosensitizer and ultrasound [17,[25][26][27]. In comparison with PDT, it offers the benefit of treating deep-seated tumors owing to the high penetration capability of ultrasound.…”

CD90 is upregulated in gastric cancer tissues and inhibits gastric cancer cell apoptosis by modulating the expression level of SPARC protein

“…Mitochondrial calcium buffering is important during continuous calcium-induced calcium release in submandibular acinar cells, directly modulates agonist-induced calcium signals, and can functionally interact with calcium stores to regulate cytosolic calcium signals. When mitochondrial membranes are damaged, mitochondria lose their calcium buffering capability and mitochondria-related proteins, such as cytochrome c and Smac/DIABLO, are released from the mitochondria into the cytosol, resulting in cellular apoptosis (21)(22)(23)(24)(25).…”