Details

Autor(en) / Beteiligte

• Huang, Pengyun

Titel

Photodynamic Action of Purpurin 18 on Breast Cancer: In Vitro and In Vivo Efficacies and Action Mechanisms

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2019

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Photodynamic therapy (PDT) as a promising treatment for solid tumors, has been proved to be efficient in clinical application. Photosensitizer, as the key element in PDT, could preferentially accumulate in tumor sites. After activation with specific light, photosensitizer could generate singlet oxygen and other reactive oxygen species (ROS) to induce cell death of tumor cells. In the process of PDT, there are two major types of cell death (apoptosis and necrosis) that depends on cell genotype, subcellular location of photosensitizer, and PDT dose.To date, many photosensitizers derived from traditional Chinese Medicine (TCM) have been used in PDT and show efficient antitumor activities. Purpurin 18 (pu 18) is a derivative of a natural photosensitizer, Pheophorbide A, which is isolated from traditional Chinese herb Scutellaria barbata D. Don (半枝蓮) and silkworm (蠶沙). In this study, we investigated the photodynamic effects of pu 18 on the breast cancer using both in vitro and in vivo models and further analyzed its action mechanisms.The in vitro study results indicated that on MCF-7 2D cell culture, in dark, the pu 18 didn’t show any toxicity under 1 μM, while significant photo-cytotoxicity could be observed after pu 18 treatment in low concentration upon light irradiation. PDT treatment could obviously increase intracellular ROS level in MCF-7 cells. Subcellular observation demonstrated that pu 18 mainly located on mitochondria and endoplasmic reticulum (ER). Mitochondrial membrane potential (MMP) measurement showed that MMP in PDT was dissipated with decreased red fluorescence. What’s more, the higher green fluorescence of Fura-2 after PDT illustrated the elevated intracellular calcium level. The lower DNA content and the double staining of both Annexin V-FITC/PI staining and Hochest 33342/PI staining confirmed cell apoptosis after PDT treatment. For 3D MCF-7 spheroid, the spheroids possessed the highest fluorescence at 16 h post incubation (hpi). After PDT treatment, peripheral cells of spheroids were chipped off and the growth of spheroids was inhibited. For 4T1 mouse breast cancer cells, pu 18 mainly distributed on lysosomes and could also destroy MMP and eventually induced the apoptosis of 2D 4T1 cells. Light-activated pu 18 could also induce the destruction of 3D 4T1 cell spheroids.The in vivo study was conducted by using subcutaneous 4T1 breast cancer animal model. The results demonstrated that pu 18 was metabolized or cleared within 8 hours and rarely accumulated in tumor after systematic administered via tail vein injection. But pu 18 could remain in tumor for more than 4 days by directly intratumoral injection. And PDT treatment could significantly inhibit the tumor growth in vivo, indicating a good photodynamic efficiency of pu 18 on breast cancer animal model, without influencing function of major organs. The PDT treatment could largely prolong the survival time of mice with breast cancer and inhibit the metastasis of 4T1 cells to lung.