Turning cancer cells back to normal
cells causes cancer tumour cells to revert back to normal cells.
Dr Mary Hendrix and colleagues from Nothwestern University have already discovered that aggressive melanoma cells share many characteristics with embryonic stem cells - including using some of the same proteins to signal to their microenvironment. Now, in a lecture at the annual meeting of the American Association of Anatomists at Experimental Biology 2007 in Washington, US, Hendrix described a new technique to provide unique insights into how scientists can change human metastatic melanoma cells back to normal-like skin cells - by exposing the tumour cells to embryonic microenvironments. Malignant cells send and receive signals to their microenvironment that can promote tumour growth and metastasis. This echoes stem cell signals, which are used to determine what type of cell the stem cell will morph into. In order to understand these signals better, the team set out to observe if tumour cells could affect embryo development in zebrafish - a widely-used organism for genetic and developmental studies. They discovered that the cells secrete a protein called Nodal, which is not only critical for stem cells to maintain their ability to turn into different cell types but also appears to play a key role in tmour cell plasticity and progression. When the scientists inhibited Nodal, the melanoma cells reverted back to a more benign, less invasive cell without the ability new tumours. These findings from the zebrafish study were further confirmed in the human embryonic stem cell model and the chick embryo model - where inhibiting Nodal signalling led to the reversal of the melanoma cells to a more normal cell type. "This is a promising area of research," said Hendrix. "The discovery of a new signalising pathway in melanoma and other tumour cell types and the ability to inhibit Nodal and thus reverse the melanoma cell back toward a normal skin cell provides a previously unknown target for regulating tumour progression and metastasis." Nodal has been recently found in breast and testicular cancers and so this technique could also provide a new therapeutic target in those types of cancer.
