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Differences in in vitro photodynamic sensitivity among head and neck cancers
V Boonkitticharoen1, B Kulapaditharom, S Punnachaiya
1Department of Radiology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
Abstract:
This study was conducted to address the question of how cancers of different histologies of the head and neck region responded to photodynamic therapy (PDT). Five human cancer cell lines were investigated: two squamous cell carcinoma lines (pharynx and tongue), mucoepidermoid carcinoma (submaxillary gland), rhabdomyosarcoma (embryonic) and adenocarcinoma (colon). The cell lines were treated with haematoporphyrin derivative (HpD) at doses of 0.78-25Mug ml(-1), with excitation of the absorbed drug by a 'black light' source (340-380 nm). An MTT assay demonstrated different PDT responses among the various cell types. On the basis of LD(50), the sensitivity of the different cell lines was ranked as follows: adenocarcinoma> squamous cell carcinoma> rhabdomyosarcoma> mucoepidermoid carcinoma. The magnitude of the LD(50) was suggested by a drug uptake study to be governed in part by cellular levels of sensitizer and in part by intrinsic cell sensitivity. This study provided information that may help to identify the histological types of head and neck cancers that would respond favourably to PDT.
Insights
Photodynamic therapy (PDT) effectiveness varies by cancer type. Adenocarcinoma showed the highest sensitivity, while mucoepidermoid carcinoma was least sensitive to PDT treatment.
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.
