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Involvement of p16CDKN2A in cell cycle delays after low dose UV irradiation
A Milligan1, B G Gabrielli, J M Clark
1Queensland Cancer Fund Cancer Unit, Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Herston, Australia.
Abstract:
Ultraviolet (UV) radiation contributes to the aetiology of melanoma, but the precise mechanistic details are still unclear. The CDKN2A gene which is associated with familial and sporadic melanoma, encodes a tumour suppressor, p16. We have previously shown that in response to low doses of UV radiation the level of p16 increases, and that this correlates with a G2 delay. Here we report that in melanoma cell lines which do not express p16, or express a mutant p16, no G2 delay is observed in response to UV. The loss of functional p16 also correlates with an increase in DNA damage as judged by increased numbers of bi- and multinuclear cells and cells containing 1-2 micronuclei following UV irradiation. This work provides a further link between UV radiation, CDKN2A and melanoma, suggesting that the functional inactivation of CDKN2A disrupts a p16-dependent G2 cell cycle checkpoint, thus contributing to the development of this neoplasm.
Insights
Functional inactivation of the CDKN2A gene, which produces the tumor suppressor p16, disrupts a cell cycle checkpoint. This disruption by UV radiation contributes to melanoma development, especially when p16 is lost.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Ultraviolet (UV) radiation is a known factor in melanoma development.
- The CDKN2A gene, encoding the p16 tumor suppressor, is frequently altered in melanoma.
- Previous work linked p16 levels to UV-induced G2 cell cycle delay.
Purpose of the Study:
- To investigate the role of functional p16 in the cellular response to UV radiation.
- To determine if loss of p16 function affects DNA damage accumulation after UV exposure.
Main Methods:
- Utilized melanoma cell lines with varying p16 expression (functional, non-expressing, mutant).
- Exposed cells to UV radiation and assessed for G2 cell cycle delay.
- Quantified DNA damage markers, including bi- and multinuclear cells and micronuclei.
Main Results:
- Melanoma cells lacking functional p16 did not exhibit a UV-induced G2 delay.
- Loss of p16 function correlated with increased DNA damage post-UV irradiation.
- Identified bi- and multinuclear cells and micronuclei as indicators of DNA damage.
Conclusions:
- Functional p16 is essential for the G2 cell cycle checkpoint response to UV radiation.
- Inactivation of CDKN2A and subsequent loss of p16 function contribute to melanoma pathogenesis by impairing DNA damage response.
- This study reinforces the link between UV, CDKN2A, and melanoma etiology.