In vitro and in vivo investigation of the inhibitory effects of Sinoporphyrin sodium-mediated Sonodynamic therapy on human oral squamous cell carcinoma

Objective: Sonodynamic therapy (SDT) is an innovative, non-invasive approach to cancer treatment, by using low-intensity ultrasound to trigger the activation of sonosensitizers localized within cancerous cells. This current study aimed to explore the therapeutic efficacy of a new sonosensitizer, Sinoporphyrin Sodium (DVDMS), under ultrasound irradiation, against oral squamous cell carcinoma (OSCC)-derived SCC-154 cells, both in vitro and in vivo.

Methods: Fluorescence spectra, cytotoxicity assessments, uptake mechanisms, and subcellular distributions of DVDMS within the SCC-154 cell line were detected. Additionally, the study comprehensively assessed the antitumor effect, oxidative stress responses, apoptosis, apoptosis-related proteins, autophagic processes, and ultrastructural changes in SCC-154 cells, both in vitro and in vivo, subsequent to treatment with low-intensity ultrasound (at 1.0 MHz, 1 W/cm² in vitro and 3 W/cm² in vivo) in conjunction with DVDMS also being examined.

Results: The findings indicate that SCC-154 cells exhibit heightened sensitivity to DVDMS compared to SAS and HSC-3 cell lines. Within SCC-154 cells, DVDMS primarily localizes within the mitochondria and lysosomes. DVDMS-based SDT significantly increased the intracellular levels of reactive oxygen species (ROS), induced morphological changes such as mitochondrial swelling and formation of autolysosomes, and exhibited a notable dose-dependent reduction in cell viability in vitro. Also, DVDMS-SDT demonstrated significant inhibition of xenograft growth without discernible adverse effects. Mechanistically, DVDMS-SDT upregulated Bax expression while downregulating Bcl-2 expression, which led to the Bax/Bcl-2 ratio and induced autophagy.

Conclusion: DVDMS-SDT triggers mitochondrial-dependent apoptosis in SCC-154 cells, unlike 5-ALA and protoporphyrin IX (PpIX). Also, the combination of DVDMS with ultrasound stimulation induces autophagy, with the onset of autophagic processes preceding apoptosis.