A tiny tropical fish is giving scientists clues about how the most serious form of skin cancer develops.
Zebrafish genes are similar to humans'
A team from the University of Iowa and Northwestern University found embryos of zebrafish contain molecular cues that can stop tumours developing.
They say the study provides an avenue for finding out more about what fuels the growth of malignant melanomas.
The research, which has been welcomed by Cancer Research UK, is published in the journal Developmental Dynamics.
The researchers implanted zebrafish embryos with fluorescently tagged human skin cancer cells.
The cells were still moving around and dividing normally, but they did not form tumours, suggesting they were responding to something in the environment of the embryos.
The researchers say they now want to carry out further research to find out exactly what it is within the embryos which stops the cells forming tumours.
Dr Robert Cornell, an embryo specialist at the University of Iowa who worked on the study, said: "These cancer cells don't do what they do in other circumstances, such as when they are placed under a mouse's skin.
"The objective of our work is to use this very simple system to identify the exact component that can influence the behaviour of melanoma and other cancer types."
He said finding out why could lead to the development of new medications to tackle skin cancers.
"When we identify the crucial factor, whatever it may be, we can look for the equivalent in humans, or make a synthetic version."
Dr Julie Sharp, of Cancer Research UK, said: "Zebrafish provide scientists with a useful tool for learning more about cancer and how it develops.
"The researchers from Iowa have discovered that zebrafish embryos containing human skin cancer cells were able to send signals to the cancer cells - telling them to behave normally and stopping the cancer.
"This research is in its early days but it may provide useful insights into how this cancer develops and possible ways of stopping it."