NFATc1 and TNFα expression in giant cell lesions of the jaws

Background: Activation mutations of SH3BP2 gene have been demonstrated in cherubism and central giant cell lesion (CGCL). In the present study we first attempted to investigate the SH3BP2 gene in peripheral giant cell lesion (PGCL). The effect of SH3BP2 gene mutations on the transcription of the downstream genes nuclear factor of activated T cells (NFATc1) and the cytokine tumor necrosis factor-alpha (TNF-alpha) was also investigated together with the immunolocalization of NFATc1 protein in a set of cases of PGCL, CGCL and cherubism with and without SH3BP2 mutation. Method: Fresh samples of five PGCL, five CGCL and one cherubism cases were included in this study. One of the samples of CGCL presented a somatic heterozygous mutation c.1442A > T in exon 11. The cherubism case showed a heterozygotic substitution c.320C > T in both blood and lesion. These mutations were previously published. All coding and flanking regions of the SH3BP2 gene were sequenced in the cases of PGCL. The real-time polymerase chain reaction (RT-PCR) was performed to analyze the transcription of NFATc1 and TNF-alpha genes. The immunohistochemical analysis of the NFATc1 protein was also performed. Results: No SH3BP2 gene mutation was found in PGCL. The RT-PCR showed increased expression of NFATc1 and decreased transcription of TNF-alpha in all the samples. The immunohistochemical analysis of the NFATc1 protein showed a predominant nuclear staining in the multinucleated giant cells. Conclusion: The development of giant cells lesions of the jaws and cherubism are possibly mediated by overexpression of NFAT in the nucleus of the multinucleated cells.