Cancer stem cells (CSCs) comprise subpopulation of tumor cells associated with cancer initiation, progression, and treatment failures found in several malignancies, including oral squamous cells carcinoma (OSCC). Currently, among the methods employed for detection and isolation of CSCs the most used is flow cytometry immunophenotyping. The expression of surface markers for CSCs in SCC-9 cells, derived from tongue OSCC, has not been described in the literature. Objective: To identify and compare the expression of cell surface markers associate to CSCs in the SCC9 ZsGreen and its metastatic derivative SCC9 ZsGreen LN1 cells. Methods: The CSC subpopulations in cultured SCC9 ZsGreen and SCC9 ZsGreen LN1 were identified by flow cytom- etry using the following surface markers: CD44 standard (and its isoforms, CD44 v3, and CD44 v6), CD133, CD326, CD24, and CD271. Results: SCC9 ZsGreen cells were significantly more posi- tive for CD44, CD133, and CD271 while SCC9 ZsGreen LN1 expressed more CD326. The positivity for CD24 e CD44 v3 was also higher in SCC9 ZsGreen LN1, however, without statistical significance. Conclusions: The 2 OSCC cell lines presented distinct pat- terns of cancer stem cells surface markers. Further experiments will be needed to better characterize the CSCs populations pres- ent in SCC9 and SCC9 ZsGreen LN1 cell lines. (FAPESP 14/ 20832-3). FASN INHIBITION WITH TVB-3166 IN ORAL SQUAMOUS CELL CARCINOMA CELL LINES. IARA GON ¸ CALVES DE AQUINO, FLORENCE CUADRA ZELAYA, RICARDO DELLA COLETTA, D  EBORA CAMPANELLA BASTOS and, EDGARD GRANER Introduction: Over-expression of fatty acid synthase (fasn) is associated with poor prognosis in several human can- cers, including oral squamous cell carcinoma (OSCC). Objective: To evaluate the effects of the fasn inhibitor TVB-3166 on the cell viability, morphology, cell cycle and migration of SCC-9 and SCC-9 LN-1 cells derived from tongue OSCC. Study Design: Cell viability was determined using stan- dard MTT assay after 48 hours of treatment with increasing doses of TVB-3166. IC50 was calculated with the aid of Compu- Syn software. Morphology and cell migration assay were evalu- ated using phase contrast microscopy and cell cycle by flow cytometry. Results: TVB-3166 significantly reduced cell viability in a dose-dependent manner in both cells lines. IC50 was 30 mM and 37 mM for SCC-9 and LN-1, respectively. TVB-3166 induced morphologic changes of the cells to a fusiform pattern. In SCC-9 cells the treatment reduced cell migration, diminished the number of cells in the S phase, and increased the number of cells in G0/G1 phase. Conclusions: Our preliminary results suggest that fasn inhibition with TVB-3166 affects important processes of tumor progression in cell lines derived from OSCC. CD1A+ LANGERHANS CELLS ARE REDUCED IN ORAL SUBMUCOUS FIBROSIS AND ORAL SQUAMOUS CELL CARCINOMA. LUAN C  ESAR DA SILVA, FELIPE PAIVA FONSECA, OSLEI PAES DE ALMEIDA, M  ARCIO AJUDARTE LOPES, RAGHU RADHAKRISHNAN, LUIZ PAULO KOWALSKI and, PABLO AGUSTIN VARGAS Oral submucous fibrosis (OSMF) affects mainly the Indian subcontinent and its manifestations are closely linked with the habit of chewing betel. Immune system cells such as Langerhans cells (LC) and dendritic cells (DC) are linked to the immunopa- thogenesis of various lesions and have been studied for their abil- ity of recognizing precursor malignant cells and to destroy them. Objective: Verify the distribution of LC and immature DC in OSMF and oral squamous cell carcinoma (OSCC). Study design: Fourteen cases of OSFM, 9 of OSCC associ- ated to OSMF, and 40 of OSCC were retrieved. The original diagnoses were confirmed by 2 oral pathologists, who further classified OSFM in grade I, II, and III. OSCC cases were classi- fied as well, moderately, and poorly differentiated. Immunoreac- tions against CD1a were performed and the number of positive LC and DC were quantified. Results: Analysis revealed a significant decrease in the number of immature LC and DC in OSCC compared to OSCC- OSMF (P < .01) and OSMF (P < .01). No statistical correlation was found between OSMF and OSCC-OSMF. Conclusions: The results suggest that depletion of immature LC and DC would represent an important step for developing OSCC. STUDY OF IMMUNOHISTOCHEMICAL EXPRESSION OF RANKL, OPG, IL-6, AND CTSK IN ODONTOGENIC CYSTS AND TUMORS. FERNANDA MARCELLO SCOTTI, DIOGO LENZI CAPELLA, DANIELLA SERAFIN COUTO VIEIRA and, ELENA RIET CORREA RIVERO Objective: To evaluate the receptor activator of nuclear factor-K B ligand (RANKL), osteoprotegerin (OPG), interleu- kin-6 (IL-6), and cathepsin K (CTSK) antigens in 34 radicular cysts (RC), 28 odontogenic keratocysts (OKC), and 25 amelo- blastomas (AM). Study Design: The immunohistochemical expression of these proteins was evaluated considering the mean of percentage marked area in 10 consecutive fields (400 x), considering epithe- lial and connective tissue individually. The analysis of variance (ANOVA) test was used to compare the groups. A P value < .05 indicated statistically significant data. Results: RANKL was statistically higher in CR and OKC compared with AM in epithelium and connective tissue. No statistical difference was found for the OPG between the groups. Statistical difference was noted to IL-6 between all groups only in connective tissue, decreasing from CR, to AM, and to OKC. CTSK was statistically higher in AM and OKC compared with CR. Conclusions: In AM and OKC cases, the mechanism of bone resorption seems to be related to the CTSK pathway, whose expression was independent of the inflammatory component. To RC the mechanism of bone resorption is more related with RANKL and IL-6 proteins and dependent of an inflammatory component. HISTOLOGIC COMPARATIVE STUDY OF BONE SPECIMENS FROM BISPHOSPHO- NATE-RELATED OSTEONECROSIS OF THE ABSTRACTS OOOO e172 January 2020