The Effect of Endothelial Cells on UVB-induced DNA Damage and Transformation of Keratinocytes In 3D Polycaprolactone Scaffold Co-culture System.

Nitric oxide ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow> <mml:mo>·</mml:mo></mml:msup> </mml:math> ) plays an important role in the regulation of redox balance in keratinocytes post-UVB exposure. Since endothelial cells releases <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow> <mml:mo>·</mml:mo></mml:msup> </mml:math> for a prolonged time post-UVB, we determined whether human umbilical vein endothelial cells (HUVEC) could have an effect on UVB-induced DNA damage and transformation of their adjacent keratinocytes (HaCaT) using a 3D cell co-culturing system. Our data show that the levels of DNA breaks and/or cyclobutane pyrimidine dimer (CPD) along with γH2AX are higher in the co-cultured than in the mono-cultured keratinocytes post-UVB. The <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow> <mml:mo>·</mml:mo></mml:msup> </mml:math> level in the co-cultured cells is increased approximately 3-fold more than in mono-cultured HaCaT cells within 1-hour post-UVB but then is reduced quickly in co-cultured HaCaT cells comparing to mono-cultured cells from 6 to 24 h post-UVB. However, the peroxynitrite (ONOO- ) level is higher in the co-cultured than in the mono-cultured HaCaT cells in whole period post-UVB. Furthermore, while expression level of inducible nitric oxide synthase (iNOS) is increased, the ratio of coupled/uncoupled eNOS is reduced in co-cultured HaCaT cells compared to mono-cultured HaCaT cells. Finally, the co-cultured cells have a significantly increased transformation efficiency after repeating UVB exposure compared to mono-culture HaCaT cells. Our results suggest that endothelial cells could enhance <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow> <mml:mo>·</mml:mo></mml:msup> </mml:math> /ONOO- imbalance and promote transformation of adjacent keratinocytes.