Early stage melanomas grow superficially in a radial manner and can be treated by surgery. By contrast, advanced stage melanomas grow vertically, gaining the ability to invade other tissues and metastasize to distant organs, and are usually highly resistant to chemotherapy and radiation.
Understanding the molecular differences between radial and vertical growth melanomas might provide new targets for the development of drugs to treat individuals with advanced stage melanoma. In a study that appears online on in advance of publication in the March print issue of the Journal of Clinical Investigation, Jack Arbiser and colleagues from Emory University, Atlanta, show that overexpression of Akt in a radial growth human melanoma cell line endows the tumor cells with the ability to grow when transplanted into immunocompromised mice. This ability to grow invasively was associated with increased production of reactive oxygen. This study therefore indicates that overexpression of Akt alone can convert a radial growth melanoma cell line into a highly invasive tumor cell line, leading the authors to suggest that Akt and the pathways that generate reactive oxygen might provide targets for the development of drugs to treat individuals with advanced stage melanoma. (Source: Journal of Clinical Investigation : Emory University School of Medicine : March 2007.)