Abstract
Sonodynamic therapy (SDT) is an innovative modality for cancer treatment. But the biological effect of SDT on oral squamous cell carcinoma has not been studied. Our previous study has shown that endo-Protoporphyrin IX based SDT (ALA-SDT) could induce apoptosis in human tongue squamous carcinoma SAS cells through mitochondrial pathway. Herein, we investigated the effect of exo- Protoporphyrin based SDT (PpIX-SDT) on SAS cells in vitro and in vivo. We demonstrated that PpIX-SDT increased the ratio of cells in the G2/M phase and induced 3–4 times more cell apoptosis compared to sonocation alone. PpIX-SDT caused cell membrane damage prior to mitochondria damage and upregulated the expression of Fas and Fas L, while the effect was suppressed if cells were pre-treated with p53 inhibitor. Additionally, we examined the SDT-induced cell apoptosis in two cell lines with different p53 status. The increases of p53 expression and apoptosis rate in wild-type p53 SAS cells were found in the SDT group, while p53-mutated HSC-3 cells did not show such increase. Our data suggest that PpIX-SDT suppress the proliferation of SAS cells via arresting cell cycle at G2/M phase and activating the extrinsic Fas-mediated membrane receptor pathway to induce apoptosis, which is regulated by p53.
Highlights
Many in vitro and in vivo experiments had shown that sonodynamic therapy (SDT), i.e., LIU in combination with a sonosensitizer, could induce the death of tumor cells[10,11,12,13]
Some investigators hold the view that PpIX with ultrasound sonication mainly mediates mitochondria stress because the affinity of PpIX on the membrane of mitochondria[22], while other experiments showed that the induced cellular damage by PpIX-based Sonodynamic therapy (SDT) appears to be mostly cell membrane related[19,23] and is more effective than 5-Aminolevulinic acid (ALA)-based SDT24
We have previously evaluated the cytotoxic effect of endo-PpIX (ALA) and LIU on human tongue squamous carcinoma SAS cell lines[25,26,27], in which the enhancement of cell killing effect is partially through mitochondrion-mediated apoptosis signaling pathways
Summary
The SAS cells were divided into eight treatment groups: control (C), PpIX (Sigma Aldrich, St Louis, MO, USA) alone (P), sonication-1 min, 2 min, 3 min (U1, U2, U3), sonication-1 min, 2 min, 3 min plus PpIX (PU1, PU2, PU3). After adding 5 μL Alexa Fluor 488 Annexin V and 1 μL PI working solution to each cell suspension, the cells were incubated at room temperature for 15 min, 400 μL 1 × annexin-binding buffer was added and the solution was analyzed immediately using a FC500 flow cytometer (Beckman Coulter Ltd., CA, USA). To observe the apoptotic cells, the SAS cells were examined with a BX51 fluorescence microscope (Olympus, Tokyo, Japan) after Annexin V and PI double staining. Cell viability was presented as a percentage of living cells relative to the control group and is represented as the mean ± SD of six experiments. Differences were considered statistically significant if p < 0.05
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
