Zebrafish play an important role in melanoma research

Dr Maria Flores

Zebrafish are an unlikely hero in the field of cancer research. They grow to 6.4cm, live for around 5 years, produce 300-500 eggs per spawning and have had their gene codes completely mapped. Zebrafish have even flown in space. Their dark and light stripes make them a particularly useful tool for melanoma studies – the fourth most common cancer in New Zealand. With the aid of a grant from the Cancer Research Trust, Dr Maria Flores (University of Auckland School of Medical Sciences) and Dr Graham Stevens (University of Auckland School of Medicine) will use Zebrafish to unravel some of the mysteries surrounding melanoma.

The name melanoma is derived from skin cells called melanocytes. These are the cells that make melanin, which gives skin its colour. When you spend time in the sun, the melanocytes make more melanin and your skin tans. But if the skin receives too much ultraviolet light, the melanocytes can grow abnormally and may develop into a melanoma.

Many cancers respond well to treatment and do not come back once all the cancer cells are eliminated. However, melanoma is very resistant to current treatments and often recurs, even when treatment has appeared successful. Why this should happen is a puzzle.

A current theory is that there are melanoma stem cells which hide from treatment and then start off a new melanoma. Dr Flores comments that “if we can understand what controls normal melanocytes, we will increase our knowledge of melanoma initiation. This in turn may lead to more accurate diagnosis and new treatments that target both the melanoma cells and melanoma stem cells”. This is where the ability of Zebrafish to regenerate damaged tail fins is very useful.

If a small part of the Zebrafish tail fin is removed under anaesthetic, both the fin and the stripes grow back in one to two weeks. Previous research has shown that the pigmented melanocytes of the regenerated dark stripe actually develop from non pigmented stem cells. By studying the regenerated melanocytes, Dr Flores hopes to discover key steps in the process. These can then be applied to developing better treatments for melanoma.

“Non-scientists are often surprised at the key role the humble little Zebrafish plays in cancer research, but they really are a tremendous help. The Zebrafish Research facility at the University of Auckland is world class and we are also studying blood and gut stem cells using Zebrafish. We are grateful to the Cancer Research Trust for the funding that will allow us to pursue a cure for this devastating disease,” stated Dr Flores.

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