Evaluation of tubulin β-3 as a novel senescence-associated gene in melanocytic malignant transformation.

Malignant melanoma might develop from melanocytic nevi in which the growth-arrested state has been broken. We analyzed the gene expression of young and senescent human melanocytes in culture and compared the gene expression data with a dataset from nevi and melanomas. A concordant altered gene expression was identified in 84 genes when comparing the growth-arrested samples with proliferating samples. TUBB3, which encodes the microtubule protein tubulin β-3, showed a decreased expression in senescent melanocytes and nevi and was selected for further studies. Depletion of tubulin β-3 caused accumulation of cells in the G2/M phase and decreased proliferation and migration. Immunohistochemical assessment of tubulin β-3 in benign lesions revealed strong staining in the superficial part of the intradermal components, which faded with depth. In contrast, primary melanomas exhibited staining without gradient in a disordered pattern and strong staining of the invasive front. Our results describe an approach to find clinically useful diagnostic biomarkers to more precisely identify cutaneous malignant melanoma and present tubulin β-3 as a candidate marker.