Differences in in vitro photodynamic sensitivity among head and neck cancers

Area of Science:

• Oncology
• Photochemistry
• Cell Biology

Background:

• Photodynamic therapy (PDT) is a promising cancer treatment modality.
• Understanding differential responses of various cancer histologies to PDT is crucial for optimizing treatment strategies.
• Head and neck cancers exhibit diverse histological subtypes, potentially influencing PDT efficacy.

Purpose of the Study:

• To investigate the differential response of various head and neck cancer cell lines to photodynamic therapy (PDT).
• To establish a sensitivity ranking of different cancer histologies based on their response to PDT.
• To explore factors influencing PDT sensitivity, including drug uptake and intrinsic cellular properties.

Main Methods:

• Culturing of five human cancer cell lines: squamous cell carcinoma (pharynx, tongue), mucoepidermoid carcinoma, rhabdomyosarcoma, and adenocarcinoma.
• Treatment of cell lines with haematoporphyrin derivative (HpD) at varying concentrations.
• Excitation of HpD using a black light source (340-380 nm).
• Assessment of cell viability using the MTT assay to determine LD(50) values.

Main Results:

• Significant variations in PDT response were observed across the investigated cancer cell lines.
• Sensitivity ranking based on LD(50) was determined as: adenocarcinoma > squamous cell carcinoma > rhabdomyosarcoma > mucoepidermoid carcinoma.
• Drug uptake studies suggested that both cellular sensitizer levels and intrinsic cell sensitivity contribute to PDT response magnitude.

Conclusions:

• PDT exhibits differential efficacy across distinct head and neck cancer histologies.
• Adenocarcinoma and squamous cell carcinoma appear more responsive to HpD-mediated PDT compared to rhabdomyosarcoma and mucoepidermoid carcinoma.
• This research provides valuable insights for selecting appropriate histological subtypes of head and neck cancers for PDT treatment.