COMET ASSAY DEMONSTRATES A HIGHER ULTRAVIOLET-B SENSITIVITY TO DNA-DAMAGE IN DYSPLASTIC NEVUS CELLS THAN IN COMMON MELANOCYTIC NEVUS CELLS AND FORESKIN MELANOCYTES
Kc. Noz et al., COMET ASSAY DEMONSTRATES A HIGHER ULTRAVIOLET-B SENSITIVITY TO DNA-DAMAGE IN DYSPLASTIC NEVUS CELLS THAN IN COMMON MELANOCYTIC NEVUS CELLS AND FORESKIN MELANOCYTES, Journal of investigative dermatology, 106(6), 1996, pp. 1198-1202
We used the single cell gel electrophoresis assay (comet assay) to stu
dy ultraviolet B (UVB)-induced DNA damage in pigment cells, This assay
detects DNA damage, mainly DNA strand breaks and alkali labile sites
in the DNA molecule, We studied the effect of biologically relevant do
ses (comparable to 2-3 MED (minimal erythemal dose) for in vivo irradi
ated full-thickness skin) of monochromatic UVB light of 302 nm on cult
ured melanocytes derived from foreskin, common melanocytic nevi, and d
ysplastic nevi. We were able to demonstrate a linear dose-response rel
ationship between UV dose and the migration coefficient of the comet t
ail in all three types of pigment cells, Nevus cells originating from
dysplastic nevi showed the highest sensitivity to UVB irradiation: 65%
higher induction of DNA damage compared to the induction in foreskin
melanocytes. Common melanocytic nevus cells were most resistant and sh
owed a 30% lower induction of DNA damage in comparison to foreskin mel
anocytes. Differences in chromatin structure and cell cycle profile ma
y influence the results of the comet assay, Control experiments with x
-ray irradiation, which is well known to produce direct DNA strand bre
aks via radical formation, revealed only small differences between the
three types of melanocytic cells, It is unlikely, therefore, that int
rinsic nuclear characteristics may account for the observed difference
s.