SOX2 and cytokeratins 5, 8 and 18 as potential stem cell biomarkers in botryoid odontogenic, lateral periodontal and gingival cysts.

The aim of this study was to compare the immunohistochemical expression of SOX2 and cytokeratins (CKs) 5, 8 and 18 in the lateral periodontal cyst (LPC) and gingival cyst of the adult (GCA) with the more aggressive botryoid odontogenic cyst (BOC), to evaluate diagnostic or prognostic utility. METHODS: Sections from archival paraffin blocks were processed for immunohistochemical localization of SOX2 and CKs 5, 8 and 18. Sections from 6 odontogenic keratocysts (OKCs) were included for comparison with a cyst that enlarges more rapidly and has a higher rate of recurrence than most other odontogenic cysts. Samples consisted of 12 BOCs, 6 GCAs, 6 LPCs, and 6 OKCs for the CKs, and 9 BOCs, 4 GCAs, 6 LPCs and 6 OKCs for SOX2. RESULTS: In the gingival epithelium in the GCA sections, all four antibodies labeled all cells in the basal cell layer, diminishing progressively through the intermediate layers to no or few cells in the superficial layers, indicative of stem cells and transit amplifying cells residing in the basal cell layer. In most BOCs, GCAs, LPCS and OKCs, antibodies to SOX2 and CK 5 displayed the same pattern as in the gingiva. However, CK 8 labeled all cell layers in all cysts except two OKCs and CK 18 labeled all except the basal cell layer in almost half the cysts. SOX2 was labile and in some older specimens there was no or a faint reaction which disproportionately affected the basal cell layer in the OKCs. There were no differences in the labeling patterns of any antibodies between the BOCs and the combined GCAs and LPCs (chi-square). CONCLUSIONS: Only the labeling patterns of SOX2 and CK 5 were consistent with that of a stem cell biomarker. A role in the more aggressive behavior of the BOC could not be drawn from the results with any of the antibodies.