Thymidine Oligonucleotides
Thymidine oligonucleotides are DNA fragments, specifically
thymidine dinucleotides homologous to the sequence that
repeats in one third of the telomere (TTAGGG), which is
the most common substrate for the photoproducts of UV
irradiation. Application of these oligonucleotides triggers
the SOS-like response normally initiated to rescue cells
exposed to UV radiation, involving processes such as
melanogenesis, but it does so without any irradiation taking
place, thereby improving the skin’s capacity to repair DNA
damage without prior UV exposure.66
These oligonucleotides have been shown to reduce the
development of squamous and basal cell carcinomas in
mice by decreasing cyclooxygenase-2 expression, inhibiting
cell proliferation, increasing apoptosis, and significantly
reducing cyclobutane pyrimidine dimers and the expression
of 8-hydroxy-2′-deoxyguanosine.67
In short, topical application of oligonucleotides and
DNA repair enzymes increases the body’s endogenous
capacity for DNA repair, thereby enhancing protection
against UV radiation and reducing photocarcinogenesis.