Membrane-targeted photodynamic mechanisms of methylene violet 3RAX in melanoma models
Thais Soares de Oliveira1, Mirella Boaro Kobal1, André Satoshi Ferreira1
1São Paulo State University (UNESP), School of Sciences, Humanities and Languages, Assis, SP 19806-900, Brazil.
Abstract:
Melanoma, while less prevalent than other skin cancers, remains the most lethal and aggressive type, posing significant treatment challenges. Photodynamic therapy (PDT) offers a promising, less invasive alternative to conventional therapies. In this study, we explored the potential of methylene violet 3RAX (MV), a phenazine-family photosensitizer, for PDT applications through in vitro assays and Langmuir monolayer studies, focusing on its interactions with cell lipid extract membranes derived from two melanoma lineages, A375 and SH-4. Our results demonstrate that MV is non-cytotoxic in the absence of light irradiation but exhibits concentration-dependent cytotoxicity upon photoactivation. Flow cytometry confirmed late apoptosis as the dominant cell death pathway under irradiation. Langmuir isotherms revealed that MV adsorbs onto anionic head groups of the lipid monolayers, particularly interacting with phosphate groups, promoting molecular organization. Upon irradiation, significant material loss to the subphase was observed, suggesting photooxidative interactions with lipid tail unsaturations, leading to hydroperoxidation, chain cleavage, and membrane destabilization. These findings highlight MV dual role as an effective photosensitizer and a molecular probe for membrane interactions, providing new insights into its mechanisms of action in PDT.
Insights
Methylene violet 3RAX (MV) shows promise for photodynamic therapy (PDT) against melanoma. Upon light activation, MV effectively induces cancer cell death via apoptosis and destabilizes cell membranes.
Area of Science:
- Biochemistry
- Photochemistry
- Dermatology
Background:
- Melanoma is an aggressive skin cancer with limited treatment options.
- Photodynamic therapy (PDT) presents a less invasive therapeutic approach.
- Phenazine dyes are being investigated as photosensitizers for PDT.
Purpose of the Study:
- To evaluate methylene violet 3RAX (MV) as a photosensitizer for melanoma PDT.
- To investigate MV's interaction with melanoma cell lipid membranes.
- To elucidate the mechanism of MV-induced cell death.
Main Methods:
- In vitro cytotoxicity assays with melanoma cell lines (A375, SH-4).
- Flow cytometry to determine cell death pathways.
- Langmuir monolayer studies to analyze MV-lipid interactions.
- Spectroscopic analysis to assess membrane damage.
Main Results:
- MV demonstrated light-dependent cytotoxicity against melanoma cells.
- Apoptosis was identified as the primary cell death mechanism.
- MV adsorbed to anionic lipid head groups, particularly phosphates.
- Photoactivation induced membrane destabilization via lipid peroxidation.
Conclusions:
- MV is a potent photosensitizer for melanoma PDT.
- MV's mechanism involves membrane interaction and photo-induced damage.
- MV acts as a molecular probe for studying membrane dynamics.
