Hiporfin‐Mediated Photodynamic Therapy in Preclinical Treatment of Osteosarcoma

Abstract

This study was carried out to investigate the anti-tumor effect and mechanism of hiporfin-mediated photodynamic therapy (hiporfin-PDT) in osteosarcoma. We found that hiporfin accumulated mainly in the cytoplasm of osteosarcoma cells in a time and concentration-dependent manner. Hiporfin-PDT inhibited the proliferation, induced apoptosis and produced cell cycle arrest at G2M in osteosarcoma cell lines. Hiporfin-PDT increased the expression of cleaved-caspase-3, cleaved PARP-1, Bax and RIP1 while it decreased the expression of Bcl-2; in addition, low concentration of hiporfin increased LC3 conversion. Furthermore, cell death caused by hiporfin-PDT could be rescued by Nec-1 but not by Z-VAD-FMK. Production of reactive oxygen species was increased after hiporfin-PDT. In vivo studies showed a significant decrease in tumor volume and weight after hiporfin-PDT in all three tumor mouse models investigated (subcutaneous and orthotopic). Histological analysis showed widespread cell apoptosis and necrosis after treatment. Immunohistochemistry also showed upregulation of cleaved-caspase-3 and downregulation of Bcl-2 after hiporfin-PDT. These results indicate that hiporfin-PDT exhibits a killing effect in osteosarcoma both in vitro and in vivo, which is associated with apoptosis and necroptosis, while autophagy plays a protective role. All these findings shed light on a potential future clinical use for hiporfin in the treatment of osteosarcoma.

A review and outlook in the treatment of osteosarcoma and other deep tumors with photodynamic therapy: from basic to deep

“…In Li's research, DCFH-DA was employed to detect the level of ROS in MG-63, which caused the endoplasmic reticulum stress in mitochondrial pathway [34]. This is consistent with other conclusion of PDT on OS treatment [14, 35, 36]. However, because of the high level of metabolism, the oxygen pressure in OS tissue is lower that that in benign tumor and normal tissues, which remarkably limits the anti-tumor effect in OS PDT[37].…”

“…Sun's research showed that hiporfin-PDT had an anti-tumor effect to the OS cells, inducing apoptosis and cell cycle arrest at G2/M in vitro [14]. The second generation of PSs includes meso-tetrahydroxyphenyl chlorine (mTHPC), δ-aminolevulinic acid (ALA), and the phthalocyanines.…”

“…Today, researches on PDT in OS are largely stagnant in terms of preclinical studies. Common PSs are limited to acridine orange [55, 56], 5-ALA [57, 58], mTHPC [15], hiporfin [14], hypericin [59], and methylene blue [60] in most of OS researches. Studies of PDT in OS are summarized in Figure 3, indicating a shortage of PDT researches in OS.…”

“…In the Hiporfin-mediated PDT of OS, the PSs concentration-dependent cell cycle arrest at G2M was observed in the combination of PSs and irradiation, while no cell cycle alternation in the groups of single PSs or irradiation [14]. In the meantime, Lee proved that the G2M cell cycle arrest induced by PDT in OS was conducted in a p53-independent manner.…”

Cell apoptosis, autophagy and necroptosis in osteosarcoma treatment

“…Interestingly, the combination of a heat shock protein inhibitor with low dose SHK enhanced cell apoptosis, while high-dose SHK induced necroptosis in MM cells [142]. Moreover, hiporfin-mediated photodynamic therapy in the preclinical treatment of osteosarcoma demonstrated that cell death caused by hiporfin-PDT could be rescued by Nec-1, but not by Z-VAD-FMK [143]. Additionally, RIP3 expression induced death profile changes in U2OS osteosarcoma cells after 5-aminolevulic acid (5-ALA)-mediated photodynamic therapy (PDT), suggesting that autophagy was likely to play a protective role against PDT-induced cell death and allow better survival for RIP3-U2OS cells [144].…”