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FEBS Lett. 2005 Jan 31;579(3):615-20.

Differentiative pathway activated by 3-aminobenzamide, an inhibitor of PARP, in human osteosarcoma MG-63 cells.

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Dipartimento di Biologia Cellulare e dello Sviluppo, Sezione di Biochimica, Università di Palermo, Policlinico, via del Vespro 129, 90127 Palermo, Italy.


This study describes the molecular mechanism by which treatment with 3-AB, a potent inhibitor of PARP, allows human osteosarcoma MG-63 cells to restrict growth and enter differentiation. Our findings show that in MG-63 cells, aberrant gene expression keeps Rb protein constitutively inactivated through hyperphosphorylation and this promotes uncontrolled proliferation of the cells. After 3-AB-treatment, the poly(ADP-ribosyl)ation of nuclear proteins markedly decreases and this results in an increase in both the hypophosphorylated active form of Rb and pRb/E2F complexes. These effects are accompanied by G1 arrest, downregulation of gene products required for proliferation (cyclin D1, beta-catenin, c-Jun, c-Myc and Id2) and upregulation of those implicated in the osteoblastic differentiation (p21/Waf1, osteopontin, osteocalcin, type I collagen, N-cadherins and alkaline phosphatase). Our study suggests that use of PARP inhibitors may induce a remodeling of chromatin with the reprogramming of gene expression and the activation of differentiation.

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