A truncated HMGA1 gene induces proliferation of the 3T3-L1 pre-adipocytic cells: a model of human lipomas.

Here we have examined the role of a truncated HMGA1 gene in adipocytic cell growth. We have found that expression of the truncated Hmga1 gene (Hmga1/T) dramatically increases 3T3-L1 cell growth without blocking adipocytic differentiation. The Hmga1/T 3T3-L1 cells had higher E2F activity than the wild-type cells, and a deregulated cell cycle. In fact, the Hmga1/T cells had a reduced G0/G1 fraction, and a greater number of cells in S-phase. However, consistent with the benign nature of tumours associated with HMGA1 rearrangements, the Hmga1/T 3T3-L1 cells did not acquire the malignant phenotype. These results suggest a critical role played by HMGA1 rearrangements in the generation of human lipomas.