Sporadic Keratocystic Odontogenic Tumor Research Articles

Biallelic PTCH1 Inactivation Is a Dominant Genomic Change in Sporadic Keratocystic Odontogenic Tumors.

Keratocystic odontogenic tumors (KCOTs) are locally aggressive odontogenic neoplasms with recurrence rates of up to 60%. Approximately 5% of KCOTs are associated with nevoid basal cell carcinoma (Gorlin) syndrome and 90% of these show genomic inactivation of the PTCH1 gene encoding Patched 1. Sporadic KCOTs reportedly have PTCH1 mutations in 30% of cases, but previous genomic analyses have been limited by low tumor DNA yield. The aim of this study was to identify recurrent genomic aberrations in sporadic KCOTs using a next-generation sequencing panel with complete exonic coverage of sonic hedgehog (SHH) pathway members PTCH1, SMO, SUFU, GLI1, and GLI2. Included were 44 sporadic KCOTs from 23 female and 21 male patients with a median age of 50 years (range, 10 to 82 y) and located in the mandible (N=33) or maxilla (N=11). Sequencing identified PTCH1 inactivating mutations in 41/44 (93%) cases, with biallelic inactivation in 35 (80%) cases; 9q copy neutral loss of heterozygosity targeting the PTCH1 locus was identified in 15 (34%) cases. No genomic aberrations were identified in other sequenced SHH pathway members. In summary, we demonstrate PTCH1 inactivating mutations in 93% of sporadic KCOTs, indicating that SHH pathway alterations are a near-universal event in these benign but locally aggressive neoplasms. The high frequency of complete PTCH1 loss of function may provide a rational target for SHH pathway inhibitors to be explored in future studies.

Molecular analysis of keratocystic odontogenic tumor cell lines derived from sporadic and basal cell nevus syndrome patients.

Keratocystic odontogenic tumor (KCOT) is a benign tumor often associated with basal cell nevus syndrome(BCNS). Mutations in Patched1(PTCH1), the Hedgehog(Hh) receptor, are responsible for BCNS. BCNS is distinguished by morphological anomalies and predisposition to benign and malignant tumors, including medulloblastoma, basal cell carcinoma, KCOT and ovarian fibromas. Among these tumors, KCOT is the least well studied because a suitable model system is not available for its investigation. To enable KCOT to be studied, we established two KCOT cell lines, one from a BCNS case (designated as iKCOT1) and one from a sporadic KCOT case (designated as sKCOT1). The BCNS‑derived KCOT cell line, iKCOT1, retained a germline-mutated PTCH1 allele and a wild-type PTCH1 allele. The sporadic KCOT-derived KCOT cell line, sKCOT1, had different loss-of-function PTCH1 mutations on both alleles. Both cell lines expressed stem cell markers (CD44, SOX2 and BMI1), mesenchymal cell markers (CDH2, VIM and SNAI2) and a neurogenic marker(NEFL). Culture of the cell lines in high calcium concentration media induced expression of epithelial cell and keratinocyte marker proteins (CDH1, CLDN1, KRT10 and IVL). Parakeratosis, which is characteristic for KCOTs, was observed in 2-Dcultures. The similarities in protein expression patterns between the two cell lines suggested that common mechanisms underlie the development of both types of KCOT and a probable common origin of KCOT cells.

The Clinical Features and Expression of bcl-2, Cyclin D1, p53, and Proliferating Cell Nuclear Antigen in Syndromic and Nonsyndromic Keratocystic Odontogenic Tumor.

The aim of this study was to describe the clinical features and expression of bcl-2, cyclin D1, p53, and proliferating cell nuclear antigen (PCNA) antibodies in syndromic (nevoid basal cell carcinoma syndrome [NBCCS]) and nonsyndromic patients diagnosed with keratocystic odontogenic tumor (KCOT). This descriptive study comprised 5 patients of KCOT associated with NBCCS and 8 patients of nonsyndromic type treated in the Department of Oral Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre between years 1998 and 2011. The clinical features (site, size, treatment, and recurrence), demographic characteristics, and immunohistochemistry results using antibodies of bcl-2, cyclin D1, p53, and PCNA were examined. The association of the antibody expression and the type of KCOT was analyzed using Fisher exact test. Altogether there were 13 patients, 5 with syndromic KCOT (1 patient met 3 major criteria of NBCCS) and 8 with sporadic KCOT. The age range for syndromic KCT was 11 to 21 years (mean 16.00 years, SD 4.36) and 10 to 54 years (median 24.50 years, interquartile range 19.00) for the nonsyndromic KCOT. Tumor recurrence occurred in 3 patients (7.7%); 1 patient from the syndromic and 2 patients from the nonsyndromic. The most positive expression was observed in PCNA for both the syndromic and nonsyndromic samples and the least positive expression involved the p53. PCNA, bcl-2 protein, and cyclin D1 expressions could be useful in evaluating the proliferative activity of the tumor and the aggressiveness of the clinical presentation; however, the authors would propose for larger sample size research for more definitive results.

P53 polymorphism at codon 72 is associated with keratocystic odontogenic tumors in the Thai population.

To clarify the association between the p53 polymorphism at codon 72 and susceptibility to the sporadic keratocystic odontogenic tumor (KCOT). One hundred KCOTs and 160 match-group healthy controls were genotyped to ascertain the frequency of the p53 codon 72 polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), confirmed by direct sequencing. The frequencies of the Pro/Pro, Arg/Pro, and Arg/Arg genotypes were 23.8%, 49.4%, and 26.9%, respectively, in the controls, while the KCOT cohort demonstrated 43.0%, 39.0%, and 18.0%, respectively. Further analysis suggested that p53 Pro could be a KCOT-susceptible allele (OR (95%CI)=1.77 (1.22 to 2.59), p=0.0024), with a sex-adjusted OR (95%CI) of 1.71 (1.17-2.50), p=0.0046. Moreover, the results indicated that p53 codon 72 Pro homozygous was associated with a two-fold risk of developing KCOT (adjusted OR (95%CI) =2.17(1.23-3.84), p=0.0062). The C/C genotype of P53 gene codon 72 increases the risk of developing sporadic KCOT and may be a useful tool for screening and diagnostic purposes.

Bisphosphonate-Related Osteonecrosis of The Jaw (BRONJ) in Neoplastic and Osteoporotic Patients: Statistical Analysis of the Influence of Primary Disease on the Multifocality

SYNDROMIC (NBCCS) AND SPORADIC KERATOCYSTIC ODONTOGENIC TUMOUR: DIFFERENT RECURRENCE RATE AFTER CONSERVATIVE SURGERY OF 213 LESIONS Simona Miccoli, Simonetta Franco, Matteo Favia, Maria Grazia Lacaita, Silvio Tafuri, Nicola Laforgia, Gianfranco Favia, Department of Odontostomatology and Surgery, Aldo Moro University, Bari, Italy; Department of Emergency and Organ Transplantation, Aldo Moro University, Bari, Italy; Department of Biomedical Sciences and Human Oncology, Aldo Moro University, Bari, Italy Objective: The purpose of this study is to evaluate the different recurrence rate after conservative surgery in 113 patients with 120 syndromic and 93 sporadic Keratocystic Odontogenic Tumours (KOT) treated between 1979 and 2012 at the University of Bari. Study Design: Conservative surgery consisted of KOT enucleation followed by peripheral ostectomy with rotary or piezoelectric instruments. Chi-Squared-Test (c) was used to find association between recurrence rate and syndromic or sporadic KOT using a 95% significance level (P<0.05). Results: 31 patients were affected by NBCCS (group1) and 82 patients presented sporadic lesions (group2). Out of group1, 12 patients had 26 recurrences (38.71%; n1⁄412/31), whereas out of group2, 8 patients presented 11 recurrences (9.76%; n1⁄48/82); (c1⁄412.95; P1⁄40.0003). Conclusions: Since syndromic patients usually present larger KOT and are more prone to continuous formation of new lesions, recurrence rate is significantly higher in group1; nevertheless recurrence rate in group2 is lower than data reported in literature for the same treatment modality.

Syndromic (NBCCS) and Sporadic Keratocystic Odontogenic Tumour: Different Recurrence Rate After Conservative Surgery of 213 Lesions

Syndromic (NBCCS) and Sporadic Keratocystic Odontogenic Tumour: Different Recurrence Rate After Conservative Surgery of 213 Lesions

Syndromic (NBCCS) and Sporadic Keratocystic Odontogenic Tumour: Comparison of Histopathological Features in Confocal Laser Scanning Microscopy

Syndromic (NBCCS) and Sporadic Keratocystic Odontogenic Tumour: Comparison of Histopathological Features in Confocal Laser Scanning Microscopy

Why OKC Reclassified into KCOT-A Review

The odontogenic cyst is derived from rest of dental lamina which shows a different growth mechanism and biological behaviour from the more common dentigerous and radicular cyst. The pathogenesis of syndrome associated and sporadic keratocystic odontogenic tumour (KCOT) involve a ‘two hit mechanism ’with allelic loss, which shows that the odontogenic cyst is not a cyst but a tumour.

Underestimated PTCH1 mutation rate in sporadic keratocystic odontogenic tumors

Keratocystic odontogenic tumors (KCOTs) are benign cystic lesions of the jaws that occur sporadically in isolation or in association with nevoid basal cell carcinoma syndrome (NBCCS). The protein patched homolog 1 gene (PTCH1) is associated with NBCCS development and tumor genesis associated with this syndrome. However, previous studies have revealed that more than 85% of syndromic KCOTs and less than 30% of sporadic KCOTs harbor PTCH1 mutations. The significantly lower PTCH1 mutation rates observed in sporadic KCOTs suggest that they serve a minor role in pathogenesis. We aimed to discern the importance of PTCH1 mutations in sporadic KCOTs. PTCH1 mutational analysis was performed with 19 new sporadic KCOT cases by direct sequencing of epithelial lining samples separated from fibrous capsules. Using this approach, we further reexamined 9 sporadic KCOTs that were previously reported to lack PTCH1 mutations by our group. Nineteen PTCH1 mutations were detected in patient samples from 16/19 new cases (84%) all these mutations were absent in fibrous tissues and peripheral blood specimens from the same patients. We also identified four PTCH1 mutations in 3/9 patients (33%) that were previously undetected. These data indicated that PTCH1 mutations occur in sporadic KCOTs at a higher rate than previously suspected, owing to the masking effects of the attached stromal tissues in the test samples. These results suggest that the PTCH1 gene plays a significant role in the pathogenesis of sporadic KCOTs, which is comparable to that observed in NBCCS patients.

Early Dental Epithelial Transcription Factors Distinguish Ameloblastoma from Keratocystic Odontogenic Tumor

The aim of the study was to characterize the molecular relationship between ameloblastoma and keratocystic odontogenic tumor (KCOT) by means of a genome-wide expression analysis. Total RNA from 27 fresh tumor samples of 15 solid/multicystic intraosseous ameloblastomas and 12 sporadic KCOTs was hybridized on Affymetrix whole genome arrays. Hierarchical clustering separated ameloblastomas and KCOTs into 2 distinct groups. The gene set enrichment analysis based on 303 dental genes showed a similar separation of ameloblastomas and KCOTs. Early dental epithelial markers PITX2, MSX2, DLX2, RUNX1, and ISL1 were differentially overexpressed in ameloblastoma, indicating its dental identity. Also, PTHLH, a hormone involved in tooth eruption and invasive growth, was one of the most differentially upregulated genes in ameloblastoma. The most differentially overexpressed genes in KCOT were squamous epithelial differentiation markers SPRR1A, KRTDAP, and KRT4, as well as DSG1, a component of desmosomal cell-cell junctions. Additonally, the epithelial stem cell marker SOX2 was significantly upregulated in KCOT when compared with ameloblastoma. Taken together, the gene expression profile of ameloblastoma reflects differentiation from dental lamina toward the cap/bell stage of tooth development, as indicated by dental epithelium-specific transcription factors. In contrast, gene expression of KCOT indicates differentiation toward keratinocytes.

The Use of Vismodegib to Shrink Keratocystic Odontogenic Tumors in Patients With Basal Cell Nevus Syndrome

Keratocystic odontogenic tumors (KCOTs) of the jaw affect more than 65% of patients with basal cell nevus syndrome (BCNS). Surgery frequently causes facial disfigurement and is not always curative. Most BCNS-related and some sporadic KCOTs have malignant activation of the Hedgehog signaling pathway. We examined the effect of vismodegib (an oral Hedgehog pathway inhibitor) on KCOT size in patients with BCNS enrolled in a clinical trial testing vismodegib for basal cell carcinoma prevention (NCT00957229), using pretreatment and posttreatment magnetic resonance imaging. Four men and 2 women had pretreatment KCOTs (mean longest diameter, 2.0 cm; range, 0.7-3.3 cm), occurring primarily in the mandible. Patients were treated with vismodegib, 150 mg/d, for a mean (SD) of 18.0 (4.8) months (range, 11-24 months). Four patients experienced a size reduction and 2 had no change. Vismodegib reduced the mean longest diameter of KCOTs in all patients by 1.0 cm (95% CI, 0.03-1.94; P = .02) or 50% from baseline. We observed no enlargement of existing KCOTs or new KCOT development. Vismodegib shrinks some KCOTs in patients with BCNS and may offer an alternative to surgical therapy. These effects were maintained for at least 9 months after drug cessation in 1 patient. Further studies assessing long-term efficacy and optimal maintenance regimens should be performed.

PTCH1 Gene Mutations in Keratocystic Odontogenic Tumors: A Study of 43 Chinese Patients and a Systematic Review

BackgroundThe keratocystic odontogenic tumor (KCOT) is a locally aggressive cystic jaw lesion that occurs sporadically or in association with nevoid basal cell carcinoma syndrome (NBCCS). PTCH1, the gene responsible for NBCCS, may play an important role in sporadic KCOTs. In this study, we analyzed and compared the distribution pattern of PTCH1 mutations in patients with sporadic and NBCCS-associated KCOTs.MethodsWe detected PTCH1 mutations in 14 patients with NBCCS-associated KCOTs and 29 patients with sporadic KCOTs by direct sequencing. In addition, five electronic databases were searched for studies detecting PTCH1 mutations in individuals with NBCCS-associated or sporadic KCOTs, published between January 1996 and June 2013 in English language.ResultsWe identified 15 mutations in 11 cases with NBCCS-associated KCOTs and 19 mutations in 13 cases with sporadic KCOTs. In addition, a total of 204 PTCH1 mutations (187 mutations from 210 cases with NBCCS-associated and 17 mutations from 57 cases with sporadic KCOTs) were compiled from 78 published papers.ConclusionsOur study indicates that mutations in transmembrane 2 (TM2) are closely related to the development of sporadic KCOTs. Moreover, for the early diagnosis of NBCCS, a genetic analysis of the PTCH1 gene should be included in the new diagnostic criteria.

Integrated Genotypic Analysis of Hedgehog-Related Genes Identifies Subgroups of Keratocystic Odontogenic Tumor with Distinct Clinicopathological Features

Keratocystic odontogenic tumor (KCOT) arises as part of Gorlin syndrome (GS) or as a sporadic lesion. Gene mutations and loss of heterozygosity (LOH) of the hedgehog receptor PTCH1 plays an essential role in the pathogenesis of KCOT. However, some KCOT cases lack evidence for gene alteration of PTCH1, suggesting that other genes in the hedgehog pathway may be affected. PTCH2 and SUFU participate in the occurrence of GS-associated tumors, but their roles in KCOT development are unknown. To elucidate the roles of these genes, we enrolled 36 KCOT patients in a study to sequence their entire coding regions of PTCH1, PTCH2 and SUFU. LOH and immunohistochemical expression of these genes, as well as the downstream targets of hedgehog signaling, were examined using surgically-excised KCOT tissues. PTCH1 mutations, including four novel ones, were found in 9 hereditary KCOT patients, but not in sporadic KCOT patients. A pathogenic mutation of PTCH2 or SUFU was not found in any patients. LOH at PTCH1 and SUFU loci correlated with the presence of epithelial budding. KCOT harboring a germline mutation (Type 1) showed nuclear localization of GLI2 and frequent histological findings such as budding and epithelial islands, as well as the highest recurrence rate. KCOT with LOH but without a germline mutation (Type 2) less frequently showed these histological features, and the recurrence rate was lower. KCOT with neither germline mutation nor LOH (Type 3) consisted of two subgroups, Type 3A and 3B, which were characterized by nuclear and cytoplasmic GLI2 localization, respectively. Type 3B rarely exhibited budding and recurrence, behaving as the most amicable entity. The expression patterns of CCND1 and BCL2 tended to correlate with these subgroups. Our data indicates a significant role of PTCH1 and SUFU in the pathogenesis of KCOT, and the genotype-oriented subgroups constitute entities with different potential aggressiveness.

Distribution of mast cells in benign odontogenic tumors

The aim of this study was to investigate the presence of mast cells in a series of odontogenic tumors. Forty-five cases of odontogenic tumors were investigated using immunohistochemistry for mast cell triptase, and differences between groups were statistically evaluated. Mast cells were present in 96% of odontogenic tumors. Mast cells present in solid ameloblastoma were observed in the tumor stroma surrounding more solid and follicular epithelial islands, with or without squamous metaplasia. The odontogenic mixoma showed few mast cells. In odontogenic tumors with a cystic structure, the mast cells were distributed throughout all areas of the lesions, mainly in keratocystic odontogenic tumor. In addition, the total density of mast cells between all odontogenic tumors showed no significant difference (p > 0.05). A greater mast cells distribution was found in keratocystic odontogenic tumor in relation to adenomatoid odontogenic tumor (p < 0.01), and when the unicystic ameloblastoma and keratocistic odontogenic tumor were compared to the odontogenic myxoma (p < 0.05). Syndrome keratocystic odontogenic tumor showed a higher mean of mast cells when compared with the other tumors of the sample. Mast cells values presented by syndrome keratocystic odontogenic tumor were significantly greater than those of the sporadic keratocystic odontogenic tumor that were not associated with the syndrome (p = 0.03). Mast cells are probably one of the major components of the stromal scaffold in odontogenic tumors. We found significant differences of mast cells between syndrome nonsyndrome keratocystic odontogenic tumors, although their distribution did not seem to have any influence on the biologic behavior of benign odontogenic tumors.

Keratocystic odontogenic tumor associated with nevoid basal cell carcinoma syndrome: Similar behavior to sporadic type?

Objective The objective of this study was to analyze the expression of proliferative markers and p53 in keratocystic odontogenic tumor (KCOT) sporadic type and KCOT associated with nevoid basal cell carcinoma syndrome (NBCCS). Study Design and Setting We performed a cross-sectional study. A total of 19 patients with KCOT were selected from the Oral Pathology Laboratory archives, Central University of Venezuela, from 1995 to 2005. Subjects and Methods Twelve cases corresponded to sporadic KCOT, and seven cases were associated with NBCCS. Immunohistochemical analysis for p53, proliferating cell nuclear antigen (PCNA), and Ki-67 was performed in all 19 cases. Results Of the seven cases associated with NBCCS, six (86%) were positive for PCNA. From the 12 sporadic cases, nine (75%) were positive for PCNA. Only one case of sporadic KCOT showed Ki-67 positivity. Five of 12 (42%) cases of sporadic KCOT were positive for p53, and only one (14%) case associated with NBCCS was positive for p53. Conclusion On the basis of the analysis of the expression of PCNA, Ki-67, and p53, there appears to be no evidence to indicate higher aggressiveness in growth and infiltrative behavior in syndromic KCOT compared with the sporadic type. Therefore, surgical treatment may be approached in the same manner in KCOT sporadic and syndromic with the goal of minimizing recurrence.

Mechanisms of Inactivation of PTCH1 Gene in Nevoid Basal Cell Carcinoma Syndrome: Modification of the Two-Hit Hypothesis

PTCH1 has been identified as the gene responsible for nevoid basal cell carcinoma syndrome (NBCCS). Keratocystic odontogenic tumors (KCOT) are aggressive jaw lesions that may occur in isolation or in association with NBCCS. The aim of this study was to investigate the genetic and/or epigenetic mechanisms of inactivation of the PTCH1 gene in patients with NBCCS and related sporadic KCOTs. Loss of heterozygosity was analyzed in 44 patients (15 NBCCS-related and 29 sporadic KCOTs), all of whom were previously analyzed for PTCH1 mutations. Allelic location was established in tumors carrying two coincident mutations. PTCH1 mRNA expression and promoter methylation status were analyzed in a panel of KCOTs to define the possible role of epigenetic effects on PTCH1 inactivation. Although mutations and loss of heterozygosity of PTCH1 were frequently detected in both syndromic and nonsyndromic cases, hypermethylation of the PTCH1 promoter was not identified in the present series. Of all the 44 cases examined, 13 were identified to fit the two-hit model, 14 to conform to a one-hit model, and the remaining 17 cases showing no alteration in PTCH1. The distribution of two-hit, one-hit, and non-hit cases was significantly different between syndrome and nonsyndrome patients (P < 0.02). This study indicates that PTCH1 gene alternation may play a significant role in the pathogenesis of NBCCS and the related sporadic tumors. Not only the standard two-hit model, but also haploinsufficiency or dominant-negative isoforms may be implicated in the inactivation of the PTCH1 gene.

Recurrence of Keratocystic Odontogenic Tumor: Clinicopathological Features and Immunohistochemical Study of the Hedgehog Signaling Pathway

Aims: Critical factors responsible for the recurrence of keratocystic odontogenic tumor (KCOT) were examined. Methods: The clinicopathological features were retrospectively studied in 74 patients with 75 sporadic KCOTs. From the 75 KCOTs, 23 were examined for the expression of Sonic Hedgehog (SHH), Patched and Smoothened (SMO) by immunohistochemistry. Results: Recurrence in multilocular lesions was more frequent than in unilocular lesions. Nine (64%) of 14 multilocular lesions recurred, in contrast to 2 (7%) of 27 unilocular lesions (p = 0.0350). The average length of recurrent lesions (62.8 ± 6.5 mm) was larger than that of nonrecurrent lesions (43.0 ± 4.0 mm; p = 0.0363). The immunoreactivity of proliferation-related SMO in KCOTs with recurrence was higher than that of those without recurrence (p = 0.0475), whereas the expressions of a ligand, SHH, and an inhibitory receptor, Patched, were not associated with KCOT recurrence. The expressions of SHH and SMO showed inverse correlation in whole KCOT (p = 0.0318). Conclusion: These findings suggest that recurrence of KCOT is associated with multilocular large lesions and high SMO expression.