Exposure to ultraviolet (UV) radiation is associated with approximately 65% of melanoma
cases, and 90% of non-melanoma skin cancers (NMSC), including basal cell carcinoma
(BCC) and squamous cell carcinoma (SCC). While the incidence of most other malignancies
has either stabilized or declined, that of NMSC has increased and is developing even in younger
age groups. NMSCs account for nearly 15,000 deaths, 3.5 million new cases, and more than 3
billion dollars a year in medical costs in the United States alone, representing a major public
health concern. As sun protection efforts have not been proven effective, targeted chemoprevention
strategies are much needed. Skin carcinogenesis by DNA damage is considered a predominant
paradigm for UV toxicity. Exposure to UV radiation can activate various oncogenes
while inactivating tumor suppressor genes, resulting in inappropriate survival and proliferation
of keratinocytes that harbor these damages. Moreover, increasing evidence demonstrate that
inflammatory responses by the immune cells within the tumor microenvironment also
contribute significantly to skin tumorigenesis. Initiation and progression of skin carcinogenesis
mediated by UV radiation involve complex pathways, including those of apoptosis, proliferation,
autophagy, DNA repair, checkpoint signaling, metabolism, and inflammation. In this review,
we highlight the recent advances in two of these key molecular processes that result
in UV-mediated skin carcinogenesis. In particular, we discuss 1) pathways that regulate DNA
damage repair and 2) the regulation of the inflammatory process its crosstalk with DNA repair
potentially leading to non-melanoma skin carcinogenesis.