YAP and its paralog protein TAZ are downstream effectors of the Hippo pathway.,Both are amplified in many human cancers and promote cell proliferation and epithelial-mesenchymal transition.,Little is known about the status of the Hippo pathway in cutaneous melanoma.,We profiled Hippo pathway component expression in a panel of human melanoma cell lines and melanocytic lesions, and characterized the capacity of YAP and TAZ to control melanoma cell behavior.,YAP and TAZ immuno-staining in human samples revealed mixed cytoplasmic and nuclear staining for both proteins in benign nevi and superficial spreading melanoma.,TAZ was expressed at higher levels than YAP1/2 in all cell lines and in those with high invasive potential.,Stable YAP or TAZ knockdown dramatically reduced the expression of the classical Hippo target CCN2/connective-tissue growth factor (CTGF), as well as anchorage-independent growth, capacity to invade Matrigel, and ability form lung metastases in mice following tail-vein injection.,YAP knockdown also reduced invasion in a model of skin reconstruct.,Inversely, YAP overexpression increased melanoma cell invasiveness, associated with increased TEA domain-dependent transcription and CCN2/CTGF expression.,Together, these results demonstrate that both YAP and TAZ contribute to the invasive and metastatic capacity of melanoma cells and may represent worthy targets for therapeutic intervention.
Treatment of uveal (intraocular) melanoma is aimed at prolonging life, if possible conserving the eye and useful vision.,About 50% of patients develop fatal metastatic disease despite successful eradication of the primary intraocular tumour.,The effect of ocular treatment on survival is unknown, because the same survival data from case series can be interpreted in different ways.,Treatment is therefore based on intuition and varies greatly between centres.,Randomised trials of treatment vs non-treatment of asymptomatic tumours are desirable but would be controversial, difficult, expensive and possibly inconclusive.,Strategies for coping with uncertainty are needed to avoid unethical care.