Melanocytes and Keratinocytes Respond Differently to UV

Spring is on the way, and with it — more sunshine, and more reminders to wear sunscreen. There is a good reason to wear sunscreen: it protects against melanoma, the incidence of which has been increasing in recent years, making it a key public health concern.

A group of researchers from the University of New Mexico have been using Lifeline Cell Technology® products to study melanoma, and came across some very interesting findings.

Previous studies have demonstrated that exposure to arsenic can increase melanoma risk, yet in some parts of the world where the soil contains arsenic, such as Taiwan and Bangladesh, the population is resistant to ultraviolet radiation (UVR)-induced melanoma.  

• The researchers reasoned that there must be different mechanisms at work, and that the melanin pigment present in melanocytes could be changing the cellular response to arsenic and UVR.
• The group ultimately wanted to determine the similarities and differences between arsenic- and UVR-induced DNA damage in melanocytes (which contain melanin), and keratinocytes, skin cells that do not contain melanin¹.

To do this, the researchers used cells from Lifeline Cell Technology®. Specifically, they used normal human neonatal epidermal keratinocytes, and normal human neonatal epidermal melanocytes.

• It is very important to have normal primary cells when studying DNA damage, because the primary cells’ DNA is unaltered.
• Furthermore, the group used Lifelin®e DermaLife culture medium (DermaLife K optimized for keratinocytes, DermaLife Ma optimized for melanocytes) to culture their cells. DermaLife contains no phenol red indicator; it is clear and does not contain any components that block or absorb UV light. This aspect of the cell medium was crucial for this particular study – when exposing cells to UVR, it is important to ensure that the cell is receiving the entire UVR dose, and that the surrounding medium is absorbing as little as possible.

The researchers found that melanocytes are more resistant to UVR-mediated DNA damage than keratinocytes. They also found that both melanocytes and keratinocytes are sensitive to arsenic. However, if there is enough DNA damage generated by UVR in either cell type, then both are susceptible to arsenic-mediated DNA repair inhibition. Improper DNA repair can trigger cancer.

These results show that people who do not have as much melanin in their skin and who are exposed to arsenic could experience a double-whammy of cancer-causing agents: UVR, which damages DNA, and arsenic, which doesn’t allow DNA to be repaired.

At Lifeline Cell Technology®, we carry melanocytes from both highly-pigmented donors and less-pigmented donors. Such cells would be extremely useful in characterizing melanoma onset and development in different populations, especially given these results showing that melanoma incidence is related to the amount of melanin produced.

Are you involved in any interesting research using Lifeline Cell Technology® products?  Let us know what you’re working on, and we may feature your project in this blog.

Reference:

[1] Cooper KL, et al. Melanocytes and keratinocytes have distinct and shared responses to ultraviolet radiation and arsenic. Toxicol Lett: 2014, 224(3): 407-415.