Autophagy and ER stress participated in the inhibition of MPPa‐PDT on tumor growth, but the molecular links between them remain undefined. We just explore the molecular mechanism between them in vitro and vivo. CCK‐8 assay and flow cytometer were used to detect the cytotoxicity and mode of cell death after MPPa‐PDT. Furthermore, the role of autophagy was verified in MPPa‐PDT. Confocal microscopy was used to show the intracellular distribution of MPPa. ER stress markers and PERK signaling pathway were detected by western blot. While in vivo, tumor histology and immunohistochemistry were performed to show the effect of MPPa‐PDT in mice. After MPPa‐PDT, cells viability decreased in dose‐dependent manner. Besides, the cell apoptosis increased along with the increasing of Beclin‐1and LC3B II but declining of P62. When pretreated with 3‐MA, LC3B II formation and the cytotoxicity declined. MPPa‐PDT caused increasing of ER stress markers (GRP78, CHOP) as MPPa accumulated in ER. However, pretreatment with ER stress inhibitor 4PBA, the expression of GRP78 and LC3B II was blocked but the PERK signaling pathway activated and the expression of P62 increased. In vivo, the tumor growth was significantly inhibited by MPPa‐PDT. Besides, the appearance of ER stress and autophagy was further demonstrated by immunohistochemistry. Our findings demonstrate that autophagy mediated by MPPa‐PDT was regulated by ER stress, via PERK signaling pathway, to kill MDA‐MB‐231 cells in vitro and vivo.

Photodynamic therapy is a clinically used, minimally invasive therapeutic procedure that involves the application of photosensitizers which can locate in target cells and so be irradiated at a corresponding wavelength. Laser light irradiation activation of photosensitizers generates free reactive oxygen species, which induces selective cytotoxic activity in target cells. Within recent years, aloe-emodin as a photosensitizer has been successfully applied in photodynamic therapy applications. Angiogenesis plays an important role in tumor growth and metastasis; thus, the development of a novel target treatment for angiogenesis is essential in order to improve treatment therapeutics for cancer treatment. An essential step in angiogenesis involves the formation of tube-like structures during matrix degradation, rearrangement, and apoptosis of endothelial cells. In the present study, we investigated the mechanisms of photocytotoxicity induced by aloe-emodin in human umbilical vein endothelial cells. Analysis of cell proliferation results noted a significant decrease in cultured cells which received various concentrations of aloe-emodin and photodynamic therapy–induced light doses. Additionally, mitochondrial mechanisms of apoptotic cell death were observed in aloe-emodin photodynamic therapy–treated cells, as tube formation assays noted angiogenesis suppression after treatment. The capacity of migration and invasion of human umbilical vein endothelial cells was measured using the transwell assay and demonstrated that aloe-emodin photodynamic therapy significantly inhibited the migration and invasion of human umbilical vein endothelial cells. The expression of p38, extracellular signal-regulated kinase, the c-Jun N-terminal kinases, and vascular endothelial growth factor suggested that the cellular metastasis was related to mitogen-activated protein kinase signal pathway. Furthermore, disorganization of F action cytoskeleton components was observed after aloe-emodin photodynamic therapy. Overall, the findings from this study suggest that aloe-emodin photodynamic therapy inhibited angiogenesis and cellular metastasis in human umbilical vein endothelial cells by activating the mitogen-activated protein kinase apoptotic signaling cell death pathway.

Gastric carcinoma (GC) has high incidence and mortality rates in China. Surgery and chemotherapy are the main treatments. Photodynamic therapy (PDT) has become a new treatment modality, appearing in recent experimental studies and clinical trials in various tumors. This study explores the combined effect of gene transfection with PDT on GC cells using aloe emodin (AE)–encapsulated nanoliposomes, which acted as gene carrier as well as one photosensitizer (PS). AE‐encapsulated nanoliposomes (nano‐AE) were prepared by reverse evaporation method. Electron microscopy and nano‐ZS90 analyzer were used to detect its morphology, size, and wavelength. Western blot was used to detect the expression of the caspase‐3 after transfection. MTT assay and flow cytometry were employed to determine the cytotoxic and apoptotic rates, respectively. Hoechst 33342 staining was adopted to detect the morphological changes in death gastric cancer cells. Cellular reactive oxygen species (ROS) contents were measured by DCFH‐DA staining. Outcomes demonstrated that the nano‐AE has good properties as gene delivery carriers as well as a PS. The group in which the recombinant plasmid of r‐caspase‐3 was transfected had higher protein expression of the caspase‐3 than controls, meanwhile the proliferation rates of the transfected cells were inhibited by the nano‐AE‐mediated PDT in an energy‐dependent manner. In addition, in the transfected cells, the death rate increased to 77.3% as assessed 12 h after PDT (6.4 J/cm2). Hochest 33342 staining also revealed that the death rate increased significantly in the transfected group compared with other groups. Compared to control groups, the production of ROS in nano‐AE PDT group had quadrupled in SGC‐7901 cells as early as 1 h after PDT, while it is similar to the group of nano‐AE transfection and PDT. Nano‐AE‐mediated r‐caspase‐3 gene transfection coupled with PDT could inhibit the proliferation rate and increase the apoptotic rate remarkably in human gastric cancer cells.

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Photodynamic therapy (PDT) is a promising treatment in cancer therapy, with a photosensitizer activated by visible light. Aloe‐emodin (AE) is a promising photosensitive agent. In this study, the photosensitizing effects and possible mechanisms of AE‐PDT in MG63 cells were evaluated. The efficiency of AE‐PDT was analyzed by MTT assay. The mode of cell death was investigated by Hoechst 33,342 staining and flow cytometer. The intracellular distribution of AE was detected with confocal microscopy. The formation of reactive oxygen species (ROS) was detected by DCFH‐DA. The mitochondrial membrane potential (MMP) was measured by Rhodamine 123. The expression of proteins including cytochrome c, caspase‐3, ‐9, and ‐12, CHOP and GRP78 was detected by western blot. Apoptosis is the primary mode of cell death in our study, which occurs in a manner of depending on AE concentration and irradiation dose. Confocal microscopy showed that AE was primarily localized on the mitochondria and endoplasmic reticulum (ER) of MG63 cells. AE‐PDT resulted in rapid increases of intracellular ROS production, which reached a peak at 2 h, followed by declining of mitochondrial membrane potential, releasing of cytochrome c from mitochondria into the cytoplasm, and up‐regulation of caspase‐3, ‐9, and ‐12, CHOP and GRP78. These results suggest that death of MG63 cells induced by AE‐PDT is triggered by ROS. Meanwhile, Mitochondria and ER serve as the subcellular targets, which are responsible for AE‐PDT‐induced death of MG63 cells.