Differential HMGA expression and post-translational modifications in prostatic tumor cells.

The HMGA architectural nuclear factors are involved in chromatin dynamics and their overexpression has been strongly linked to the neoplastic transformation process. Here we investigate the expression and post-translational modifications (PTMs) of HMGA proteins (HMGA1a, HMGA1b and HMGA2) in the rat prostatic cancer Dunning model (G, AT-1, and MAT-Ly-Lu cell lines). We demonstrate the expression of HMGA2, in addition to HMGA1a and HMGA1b, in both the anaplastic cell lines AT-1 and MAT-Ly-Lu and an extremely specific HMGA1a mono-methylation only in the most metastatic cell line MAT-Ly-Lu. The HMGA ectopic expression in HMGA-negative Dunning G cells does not significantly alter their growth ability, suggesting that, although HMGA expression is necessary for the progression of neoplastic transformation in several cellular models, in these cells it is not sufficient. These data suggest exploring HMGA2 as a potential marker in human prostate tumor and moreover indicate PTMs as an additional tool in the staging of tumor progression.