GDC-0449 suppresses odontogenic keratocyst aggressiveness in fibroblasts by upregulating SPARC via Hedgehog pathway inhibition.

Objective: Odontogenic keratocysts (OKCs) are aggressive jaw lesions, either linked to Gorlin-Goltz syndrome or sporadic. We aimed to investigate the impact of the Hedgehog (Hh) pathway inhibitor GDC-0449 on OKC fibroblasts (OKC-Fs). Additionally, we explored whether secreted protein acidic and rich in cysteine (SPARC) was a novel Hh target and its association with OKC aggressiveness.

Design: Fibroblasts from four syndromic and four non-syndromic OKCs were isolated, with patched 1 (PTCH1) mutations found only in syndromic ones. Syndromic OKC-Fs with PTCH1 mutations were treated with GDC-0449, using mutation-free non-syndromic OKC-Fs as controls. Wound healing and transwell assays assessed the migration and invasion of OKC-Fs. Real-time polymerase chain reaction (PCR), alkaline phosphatase staining, and tartrate-resistant acid phosphatase staining investigated osteogenic differentiation and osteoclastogenic effects. Real-time PCR and western blotting examined the correlation between SPARC and Hh signaling. SPARC siRNA treatment tested its effect on cell migration and invasion.

Results: GDC-0449 inhibited the migration, invasion, and osteoclastogenic ability, while promoting their osteogenic differentiation of syndromic OKC-Fs. Moreover, GDC-0449 inhibited Hh pathway by decreasing glioma-associated oncogene 1 (GLI1) expression in syndromic OKC-Fs harboring PTCH1 mutations. Additionally, by suppressing Hh pathway, GDC-0449 upregulated SPARC expression, suggesting that Hh-GLI1 signaling exerts a negative regulatory effect on SPARC. Knockdown of SPARC promoted the migration and invasion of OKC-Fs, which could be reversed by GDC-0449.

Conclusion: GDC-0449 suppresses aggressiveness and osteoclastogenesis of OKCs while promoting osteogenesis. GDC-0449 treats OKCs by inhibiting Hh signaling and upregulating SPARC. SPARC could be a potential therapeutic target for OKCs.