Susceptibility to DNA Damage as a Molecular Mechanism for Non-Syndromic Cleft Lip and Palate

<div><p>Non-syndromic cleft lip/palate (NSCL/P) is a complex, frequent congenital malformation, determined by the interplay between genetic and environmental factors during embryonic development. Previous findings have appointed an aetiological overlap between NSCL/P and cancer, and alterations in similar biological pathways may underpin both conditions. Here, using a combination of transcriptomic profiling and functional approaches, we report that NSCL/P dental pulp stem cells exhibit dysregulation of a co-expressed gene network mainly associated with DNA double-strand break repair and cell cycle control (p = 2.88×10<sup>−2</sup>–5.02×10<sup>−9</sup>). This network included important genes for these cellular processes, such as <i>BRCA1</i>, <i>RAD51</i>, and <i>MSH2</i>, which are predicted to be regulated by transcription factor E2F1. Functional assays support these findings, revealing that NSCL/P cells accumulate DNA double-strand breaks upon exposure to H<sub>2</sub>O<sub>2</sub>. Furthermore, we show that <i>E2f1</i>, <i>Brca1</i> and <i>Rad51</i> are co-expressed in the developing embryonic orofacial primordia, and may act as a molecular hub playing a role in lip and palate morphogenesis. In conclusion, we show for the first time that cellular defences against DNA damage may take part in determining the susceptibility to NSCL/P. These results are in accordance with the hypothesis of aetiological overlap between this malformation and cancer, and suggest a new pathogenic mechanism for the disease.</p></div>