Photobiomodulation effect on p53 and yH2AX expression in epithelial cells exposed to chemotherapeutic drugs: an in vitro study

• Grant number: 21/15151-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2022
• End date: March 31, 2023
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Luciana Corrêa
• Grantee: Gabriela Melo da Costa Furlan
• Host Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Oral mucositis (OM) is an inflammatory condition derived from the cytotoxic effect of chemotherapy, mainly from 5-FU, melphalan, and methotrexate. After chemotherapy exposure, intense oxidative stress and DNA damage can occur. Photobiomodulation (PBM) is indicated for the prevention and treatment of OM, due to its properties of inflammatory modulation and repair improvement; however, the PBM effect under DNA damage is little known. The aim of this project is to verify if the PBM changes the expression of DNA repair proteins (yH2AX, and p53) in keratinocytes previously exposed to melphalan, 5-FU, and methotrexate. Keratinocytes lineage (HaCat) will be grown in vitro and grouped in accordance with the chemotherapy treatments. The PBM will be performed with diode laser, 660nm, 100mW, with three irradiation times: 6s (6J/cm2), 10s (11,1J/cm2) and 20s (22,2J/cm2). These doses were adapted from the OM protocols described in the literature. After 24h of PBM, immunofluorescence assays will be performed for p53, yH2AX, and PCNA. This later marker will signalize if the cells are activating the cell cycle after the different treatments, as well as improve the interpretation of the DNA damage and repair. The percentage of positive cells for each marker will be determined using manual cell counting. We hope that the results clarify the PBM's role in the DNA repair of non-neoplastic cells, improving the understanding of the PBM mechanism on the OM.(AU)