UV radiation increases carcinogenic risks for oral tissues compared to skin

Area of Science:

• Photobiology
• Dermatology
• Oral Medicine

Background:

• Ultraviolet (UV) radiation (290-400 nm) exposure is common orally via outdoor activities and indoor UV-emitting devices.
• The World Health Organization classifies UV radiation as a human carcinogen, prompting investigation into oral tissue risks.
• Understanding UV-induced DNA damage and repair mechanisms in oral tissues is crucial for risk assessment.

Purpose of the Study:

• To compare the carcinogenic risk of oral tissues versus skin tissue when exposed to UVB (290-320 nm) radiation.
• To quantify DNA damage (cyclobutane pyrimidine dimers - CPD), CPD repair rates, and apoptosis in engineered oral and skin tissues.
• To assess the differential susceptibility of oral tissues to UV-induced damage compared to skin.

Main Methods:

• Utilized 3D-engineered human skin (EpiDerm™), gingival (EpiGingival™), and oral (EpiOral™) tissue models.
• Exposed tissues to increasing doses of erythemally weighted UV radiation.
• Developed a tri-labeling fluorescent assay to simultaneously quantify DNA, CPD, and apoptotic cells, enabling measurement of DNA repair rates and cell death.

Main Results:

• Significantly lower DNA repair rates were observed in oral tissues compared to skin tissues.
• The number of apoptotic (dead) cells was significantly lower in UV-exposed oral tissues relative to skin.
• Initial DNA damage levels and subsequent cellular responses indicate differential UV sensitivity between oral and skin tissues.

Conclusions:

• Oral tissues exhibit reduced DNA repair capacity and lower apoptotic responses following UVB exposure compared to skin.
• These findings suggest that oral tissues are at a significantly higher carcinogenic risk from UVB radiation than skin tissues.
• Further research is warranted to elucidate mechanisms and develop protective strategies against oral UV carcinogenesis.