Epidermal Keratinocyte Depletion during Five Weeks of Radiotherapy is Associated with DNA Double-Strand Break Foci, Cell Growth Arrest and Apoptosis: Evidence of Increasing Radioresponsiveness and Lack of Repopulation; the Number of Melanocytes Remains Unchanged

Hyperbaric oxygen enhances X-ray induced ferroptosis in oral squamous cell carcinoma cells

OBJECTIVE

The objective of this study was to investigate the combined effect of X-ray radiation (IR) and hyperbaric oxygen (HBO) on oral squamous cell carcinoma (OSCC) cells and to explore the possible molecular mechanism.

METHODS

The OSCC cells were treated with or without IR, together with or without HBO co-exposure. Cells were transfected with specific plasmids using Lipofectamine 2000. The cell varieties, apoptosis markers, and ferroptosis markers were determined by using appropriate method. OSCC xenograft mice model was categorized into several subgroups according to the specific treatement. GPX4 expressions were determined by immunohistochemistry (IHC) in OSCC tissues and were tested by ELISA in serums from OSCC patients.

RESULTS

The co-exposure of IR and HBO significantly strengthened the cytotoxicity of IR on SCC15-S cells in ferroptosis-dependent manner. The regulated GPX4/ferroptosis mediated the HBO function on re-sensitizing the radio-resistant OSCC cells to IR. In xenograft mice, co-exposure of IR and HBO can significantly reduce the tumor under IR activation compared with IR alone. Clinical data indicated that high GPX4 levels were associated with poor chemo-radiotherapy outcome.

CONCLUSIONS

HBO could re-sensitize radio-resistant OSCC cells through GPX4/ferroptosis regulation. These results provide a potential therapeutic strategy for clinical radio-resistance.

IGF-I and Hyaluronic Acid Mitigate the Negative Effect of Irradiation on Human Skin Keratinocytes

Simple Summary

Patients undergoing radiation therapy for the treatment of various types of cancer often experience side effects such as radiation dermatitis. A gold standard treatment is still lacking. The objective of the present study was to find novel therapeutic strategies for the regeneration and repair of damaged skin areas after irradiation. An in vitro 2D and 3D primary keratinocyte model was used to test the effect of insulin-like growth factor I (IGF-I), keratinocyte growth factor (KGF), platelet lysate (PL), hyaluronic acid (HA), and adipose-derived stem cell (ADSC) conditioned medium on the functional abilities (viability, migration) and the gene expression of irradiated keratinocytes. Hyaluronic acid and IGF-I effectively reduced the irradiation damage of primary keratinocytes by stimulating viability and migration and reducing cell apoptosis and necrosis. These findings indicate that the negative effects of irradiation on keratinocytes located in the patient’s skin can be counterbalanced with HA and IGF-I treatment.

Abstract

Ionizing radiation has become an integral part of modern cancer therapy regimens. Various side effects, such as radiation dermatitis, affect patients in acute and chronic forms and decrease therapy compliance significantly. In this study, primary keratinocytes were irradiated in a 2-dimensional (2D) culture as well as on a 3-dimensional (3D) collagen-elastin matrix with doses of 2 and 5 Gy. The effect of different concentrations of IGF-I, KGF, platelet lysate (PL), high and low molecular weight hyaluronic acid (H-HA, L-HA), and adipose-derived stem cell (ADSC) conditioned medium was analyzed in respect to cell viability (WST-8), wound closure (migration), and the gene expression (quantitative real-time PCR) of 2D cultures. The 3D culture was evaluated by WST-8. A mixture of H-HA and L-HA, as well as IGF-I, could significantly stimulate the keratinocyte viability and migration which were severely reduced by irradiation. The MKI67and IL6 gene expression of irradiated keratinocytes was significantly higher after H-HA/L-HA treatment. The stimulating effects of H-HA/L-HA and IGF-I were able to be confirmed in 3D culture. A positive influence on cell viability, migration, and gene expression was achieved after the treatment with H-L-HA and IGF-I. These results open the possibility of a novel therapeutic method for both the prevention and the treatment of radiation dermatitis.