PTCH mutations in sporadic and Gorlin-syndrome-related odontogenic keratocysts

Odontogenic keratocysts are relatively common lesions that may occur in isolation or in association with nevoid basal cell carcinoma syndrome (or Gorlin syndrome). The PTCH gene has been reported to be associated with Gorlin syndrome. We investigated 10 cases of non-syndromic keratocysts and two other cases associated with Gorlin syndrome, looking for PTCH mutations. Four novel and 1 known PTCH mutations were identified in five individual patients. Of the 5 mutations identified, 2 were germ-line mutations (2619C>A; 1338_1339insGCG) in 2 cysts associated with Gorlin syndrome, and 3 were somatic mutations (3124_3129dupGTGTGC; 1361_1364delGTCT; 3913G>T) in 3 non-syndromic cysts. This report describes PTCH mutations in both non-syndromic and Gorlin-syndrome-related odontogenic keratocysts in Chinese patients, and suggests that defects of PTCH are associated with the pathogenesis of syndromic as well as a subset of non-syndromic keratocysts.     

PTCH1 and SMO gene alterations in keratocystic odontogenic tumors

Keratocystic odontogenic tumors (KCOTs, previously known as odontogenic keratocysts) are aggressive jaw lesions that may occur in isolation or in association with nevoid basal cell carcinoma syndrome (NBCCS). Mutations in the PTCH1 (PTCH) gene are responsible for NBCCS and are related in tumors associated with this syndrome. Mutations in the SMO gene have been identified in basal cell carcinoma and in medulloblastoma, both of which are features of NBCCS. To clarify the role of PTCH1 and SMO in KCOTs, we undertook mutational analysis of PTCH1 and SMO in 20 sporadic and 10 NBCCS-associated KCOTs, and for SMO, 20 additional cases of KCOTs with known PTCH1 status were also included. Eleven novel (1 of which occurred twice) and 5 known PTCH1 mutations were identified. However, no pathogenic mutation was detected in SMO. Our findings suggest that mutations are rare in SMO, but frequent in PTCH1 in sporadic and NBCCS-associated KCOTs. Abbreviations: NBCCS, nevoid basal cell carcinoma syndrome; KCOTs, keratocystic odontogenic tumors; BCCs, basal cell carcinomas.     

PCR-SSCP和DNA测序检测牙源性角化囊肿中PTCH基因的突变

目的 检测牙源性角化囊肿（OKC）中PTCH基因突变的特点。方法 采用PCR-SSCP筛查与DNA直接测序的方法对12例OKC进行PTCH基因突变的检测, 其中2例为痣样基底细胞癌综合征（NBCCS）相关OKC,10例为散发OKC。 结果 在4例OKC中发现了4处突变,其中2处生殖细胞突变发生在2例NBCCS相关OKC,2处体细胞突变发生在2例散发OKC。另外,还在10例OKC中检测到了8处PTCH基因多态性。结论 NBCCS相关OKC和散发OKC均可发生PTCH基因突变,但突变水平不同,PTCH基因的突变在二者的发病中可能均起重要作用。     

PTCH gene mutations in odontogenic keratocysts

An odontogenic keratocyst (OKC) is a benign cystic lesion of the jaws that occurs sporadically or in association with nevoid basal cell carcinoma syndrome (NBCCS). Recently, the gene for NBCCS was cloned and shown to be the human homologue of the Drosophila segment polarity gene Patched (PTCH), a tumor suppressor gene. The PTCH gene encodes a transmembrane protein that acts in opposition to the Hedgehog signaling protein, controlling cell fates, patterning, and growth in numerous tissues, including tooth. We investigated three cases of sporadic odontogenic keratocysts and three other cases associated with NBCCS, looking for mutations of the PTCH gene. Non-radioactive single-strand conformational polymorphism and direct sequencing of PCR products revealed a deletion of 5 base pairs (bp) in exon 3 (518delAAGCG) in one sporadic cyst as well as mutations in two cysts associated with NBCCS, a nonsense (C2760A) and a missense (G3499A) alteration. This report is the first to describe a somatic mutation of PTCH in sporadic odontogenic keratocysts as well as two novel mutations in cysts associated with NBCCS, indicating a similar pathogenesis in a subset of sporadic keratocysts.     

牙源性角化囊肿中PTCH基因的突变检测

目的检测牙源性角化囊肿（OKC）中PTCH基因突变的发生频率、类型及分布特点，分析散发OKC与伴发痣样基底细胞癌综合征（NBCCS）OKC之间的分子病理联系。方法收集8例OKC新鲜病变组织（4例散发，4例伴发NBCCS），提取DNA，采用PCR直接测序法检测OKC病变组织中的PTCH基因突变。结果分别于4例NBCCS—OKC和2例散发OKC中检测到6处PTCH基因突变，2例为错义突变，引起1个氨基酸的改变；其余4例突变分别为1～7个碱基插入或缺失，其中3例引起读码框的改变（移码突变），并导致蛋白质的提前截断，1例导致了2个氨基酸的插入。结论PTCH基因突变不仅常见于NBCCS—OKC，部分散发OKC病变也可以发生该基因的异常。     

Nevoid basal cell carcinoma syndrome: molecular biology and new hypotheses.

To understand the molecular biology of the nevoid basal cell carcinoma syndrome, the hedgehog signaling network is explained. The syndrome is caused by mutations in patched, a tumor suppressor gene. A single point mutation in one patched allele may be responsible for the malformations found in the syndrome. Inactivation of both patched alleles results in the formation of tumors and cysts (basal cell carcinomas, odontogenic keratocysts, and medulloblastomas). Several new hypotheses are proposed to account for a minority of nevoid basal cell carcinoma syndrome patients. Evidence is provided to suggest that these hypotheses deserve to be investigated.     

One germline mutation of PTCH gene in a Chinese family with non-syndromic keratocystic odontogenic tumours

Keratocystic odontogenic tumours (KOCTs) are common benign cystic tumours that arise sporadically or associated with nevoid basal cell carcinoma syndrome (NBCCS). PTCH mutation can be found in sporadically or NBCCS associated KOCTs. Few PTCH mutations in families with non-syndromic KOCTs have been reported. Through PCR and gene sequence analysis, the authors discovered one missense mutation c.3277G>C in exon 19 of PTCH gene in a Chinese family with non-syndromic KOCTs. This mutation causes one highly conserved glycine residue transit to arginine on the 10th transmembrane region of PTCH protein. This work revealed that the missense mutation of PTCH is the causative and dominant gene of KOCTs in this family.     

Immunolocalization of PTCH protein in odontogenic cysts and tumors

The human patched gene (PTCH) functions in both embryologic development and tumor suppression. PTCH mutations have been found in odontogenic keratocysts. However, the expression and localization of the protein product of the gene have not been determined in odontogenic tumors and cysts. We investigated 68 odontogenic lesions by immunohistochemistry, and compared their PTCH expression with that in basal cell carcinomas. All odontogenic lesions, including two keratocysts with truncating mutations, were positive for PTCH. Different types of lesions had different amounts of staining. Lack of staining was noted in the majority of basal cell carcinomas. Taken together, these data suggest that odontogenic keratocysts arise with heterozygous mutations of the PTCH gene.     

Odontogenic keratocysts in a 5-year-old: initial manifestations of nevoid basal cell carcinoma syndrome

The purpose of this paper is to report the occurrence of odontogenic keratocysts in a young child. Odontogenic keratocysts are one of the principal features of nevoid basal cell carcinoma syndrome. Their occurrence in this syndrome is usually during the second or third decades of life. This report describes the occurrence of odontogenic keratocysts in a 5-year-old, which proved to be the initial presentation of nevoid basal cell carcinoma syndrome and highlights the need to consider this syndrome as a possible diagnosis in all cases of odontogenic keratocysts.     

Expression of cell cycle and apoptosis-related proteins in sporadic odontogenic keratocysts and odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome.

Odontogenic keratocysts are occasionally (4-5%) associated with the nevoid basal cell carcinoma syndrome, a pleiotropic, autosomal disorder presenting a spectrum of developmental abnormalities and a predisposition for the development of different neoplasms. The aim of this study was to establish whether keratocysts showing clinically aggressive behavior associated with nevoid basal cell carcinoma syndrome reflect differences in cellular proliferation rate and/or in the expression of oncoproteins and tumor suppressor genes. For this reason, formalin-fixed paraffin-embedded sections of odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome (16 cases) and sporadic odontogenic keratocysts (16 cases) were compared for expression of proliferating cell nuclear antigen (PCNA) and p53, bcl-2, and bcl-1 (cyclin D1) onco-proteins. Most of the epithelial lining of odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome showed nuclear immunopositivity for p53 protein and overexpression of cyclin D1 with various degrees of staining intensity. All sporadic odontogenic keratocysts were negative for p53 and cyclin D1. The expressions of bcl-2 oncoprotein were found to be substantially similar between the two groups of lesions, with a cytoplasmic immunopositivity localized only in the resting reserve basal layer of the epithelium. PCNA expression showed no statistically significant difference between the two groups of lesions. In conclusion, the finding of cyclin D1 and p53 overexpression in odontogenic keratocysts associated with the nevoid basal cell carcinoma syndrome could be considered a hallmark of a mutated cellular phenotype, thus leading to the hypothesis that their aggressive clinical behavior could be due to a dysregulation of the expression of cyclin D1 and p53 proteins, involved in a check-point control of cellular proliferation.     

Familial multiple odontogenic keratocysts

Multiple odontogenic keratocysts (OKCs) are principle features of nevoid basal cell carcinoma syndrome (NBCCS; Gorlin-Goltz syndrome). NBCCS is a genetic disorder transmitted by an autosomal dominant gene with variable expressivity, which is important to recognize when a patient has multiple OKCs. The cysts of the jaws are among the most common findings. Another feature is a certain appearance of the face, such as: large calvaria, high-arched eyebrows, broad nasal root, and mild hypertelorism. Before-therapy diagnosis is, therefore, as important as after-therapy diagnosis. Genetic counseling and examination may also be indicated. The purpose of this paper was to present a family case report of nevoid basal cell carcinoma syndrome with multiple odontogenic keratocysts. The features identified by these combined clinical, imaging, and histologic findings are described, along with a brief mention of the family history and a review of the literature.     

牙源性角化囊肿SMO基因突变检测

目的检测牙源性角化囊肿(odontogenic keratocyst,OKC)是否存在SMO基因突变,进一步完善对OKC发病机制的认识。方法收集2012年9月至2017年6月就诊于北京大学口腔医学院·口腔医院口腔颌面外科的OKC患者,10例为痣样基底细胞癌综合征性OKC(女性4例,男性6例),20例为散发性OKC(女性7例,男性13例)。采集患者的病变组织,分离衬里上皮和纤维间质,采用Sanger测序法分别检测上皮与间质DNA中SMO基因突变情况。结果检测发现3个SMO基因突变位点,即1例综合征性OKC携带c.2081C>G(p.P694R)突变,2例散发性OKC分别携带c.907C>T(p.L303F)突变和c.1247_1248delinsAA(p.G416E)突变,前2例突变为未被报道过的SMO新突变,且2例散发性OKC均不伴PTCH1突变。结论除PTCH1突变外,OKC还存在SMO基因突变,可能与OKC的发病机制有关。     

Contributions of PTCH gene variants to isolated cleft lip and palate.

OBJECTIVE: Mutations in patched (PTCH) cause the nevoid basal cell carcinoma syndrome (NBCCS), or Gorlin syndrome. Nevoid basal cell carcinoma syndrome may present with developmental anomalies, including rib and craniofacial abnormalities, and predisposes to several tumor types, including basal cell carcinoma and medulloblastoma. Cleft palate is found in 4% of individuals with nevoid basal cell carcinoma syndrome. Because there might be specific sequence alterations in PTCH that limit expression to orofacial clefting, a genetic study of PTCH was undertaken in cases with cleft lip and/or palate (CL/P) known not to have nevoid basal cell carcinoma syndrome. RESULTS: Seven new normal variants spread along the entire gene and three missense mutations were found among cases with cleft lip and/or palate. One of these variants (P295S) was not found in any of 1188 control samples. A second variant was found in a case and also in 1 of 1119 controls. The third missense (S827G) was found in 5 of 1369 cases and in 5 of 1104 controls and is likely a rare normal variant. Linkage and linkage desequilibrium also was assessed using normal variants in and adjacent to the PTCH gene in 220 families (1776 individuals), each with two or more individuals with isolated clefting. Although no statistically significant evidence of linkage (multipoint HLOD peak = 2.36) was uncovered, there was borderline evidence of significant transmission distortion for one haplotype of two single nucleotide polymorphisms located within the PTCH gene (p = .08). CONCLUSION: Missense mutations in PTCH may be rare causes of isolated cleft lip and/or palate. An as yet unidentified variant near PTCH may act as a modifier of cleft lip and/or palate.     

The odontogenic keratocyst revisited

The treatment of odontogenic keratocysts is reviewed in light of the aetiology and pathogenesis of these lesions. The role of the dental lamina and submucosal hamartias, as frequently seen in nevoid basal cell carcinoma syndrome, is discussed, and the implications for treatment are emphasized.     

The immunoprofile of odontogenic keratocyst (keratocystic odontogenic tumor) that includes expression of PTCH, SMO, GLI-1 and bcl-2 is similar to ameloblastoma but different from odontogenic cysts

Background:  The aggressive biological behavior of odontogenic keratocysts (OKCs), unlike that of other odontogenic cysts, has argued for its recent re-classification as a neoplasm, 'keratocystic odontogenic tumor'. Identification of mutations in the PTCH gene in some of the OKCs that were expected to produce truncated proteins, resulting in loss of control of the cell cycle, provided additional support for OKCs having a neoplastic nature.
Methods:  We investigated the immunohistochemical expression of the sonic hedgehog (SHH) signaling pathway-related proteins, PTCH, smoothened (SMO) and GLI-1, and of the SHH–induced bcl-2 oncoprotein in a series of primary OKC (pOKC), recurrent OKC (rOKC) and nevoid basal cell carcinoma syndrome-associated OKCs (NBCCS-OKCs), and compared them to solid ameloblastomas (SAMs), unicystic ameloblastomas (UAMs), 'orthokeratinized' OKCs (oOKCs), dentigerous cysts (DCs) and radicular cysts (RCs).
Results:  All studied lesions expressed the SHH pathway-related proteins in a similar pattern. The expression of bcl-2 in OKCs (pOKCs and NBCCS-OKCs) and SAMs was significantly higher than in oOKCs, DCs and RCs ( P  <   0.001).
Conclusions:  The present results of the immunoprofile of OKCs (that includes the expression of the SHH-related proteins and the SHH-induced bcl-2 oncoprotein) further support the notion of OKC having a neoplastic nature. As OKCs vary considerably in their biologic behavior, it is suggested that the quality and quantity of interactions between the SHH and other cell cycle regulatory pathways are likely to work synergistically to define the individual phenotype and corresponding biological behavior of this lesion.     

Familial odontogenic keratocysts. Report of 3 cases and review of Japanese dental literature

Familial odontogenic keratocysts are described in this report. The Case 1 patient, who has 3 sisters, developed odontogenic keratocysts. The 2 younger sisters (Cases 2 and 3) also had odontogenic keratocysts, although the elder sister did not have any odontogenic cysts. The father of the patients had a history of removal of a jaw cyst, and the mother was found later to have malignant ameloblastoma. Besides the odontogenic keratocysts, the Case 1 patient had basal cell nevus, prominent frontal process, and ocular hypertelorism; the Case 2 patient had prominent frontal process; the Case 3 patient had prominent frontal process, ocular hypertelorism, and squint. All 3 sisters are suspected of being patients with the basal cell nevus syndrome. The Japanese dental literature concerning the basal cell nevus syndrome is reviewed.     

Implant prosthodontic rehabilitation of a patient with nevoid basal cell carcinoma syndrome: a clinical report

This clinical report describes the prosthodontic rehabilitation of an edentulous patient with compromised maxillary and mandibular anatomy, caused by the resection of several odontogenic keratocysts associated with nevoid basal cell carcinoma syndrome. Preprosthetic surgical preparation included iliac crest bone grafting to both arches and placement of implants. Prosthodontic treatment included the fabrication of maxillary and mandibular dental implant-supported connecting bars and construction of attachment-retained overdentures.     

Gorlin's syndrome. Case report

The authors present a case of Gorlin's Syndrome, more satisfactorily defined as nevoid basal cell carcinoma syndrome (NBCS), a rare genetic disorder characterized mainly by multiple basal cell carcinomas and odontogenic keratocysts and other less frequent skeletal, sexual and neurological manifestations. Patient 75 years old, male. Previously treated surgically for multiple cutaneous basal cell carcinomas, comes to our Department to remove a suspected asymptomatic keratocyst. Clinical examination reveals cutaneous alterations of hands and feet (webbed hands and feet), a little progenism and multiple nevi and basal cell carcinomas on the body and the head. The oral cavity is free of alterations or clinical signs. NBCS is probably caused by chromosomal abnormalities of chromosome 5 and 9. The abnormalities seen in the latter are similar to those seen in people exposed for long periods to UV radiation. These abnormalities could determine malignant cutaneous tumors removing anti neoplastic protection. The association with odontogenic keratocysts, however not clearly understood, appears in more than 90% of cases. All the other disorders are less frequent. Juvenile basal cell carcinomas, especially if associated with odontogenic keratocysts suggest, the hypothesis of NBCS; if confirmed, this diagnosis makes further familial investigations necessary, to diagnose other cases, at the time unknown.     

Glandular odontogenic cyst: absence of PTCH gene mutation

Glandular odontogenic cyst (GOC) is a rare jawbone cyst of odontogenic origin. Human patched (PTCH) is a tumour suppressor gene that has been recently associated with signalling pathways during odontogenesis. Recently alterations of this gene were found on sporadic odontogenic keratocysts. This evidence, together with the biological behaviour similarities of both lesions, and the absence of reports on molecular analysis of GOC, led us to hypothesize that PTCH gene mutations may underlie the tumorigenesis of GOC. Therefore the aim of this study was to report one additional case of GOC and investigate the PTCH gene of the cyst. No mutations were found in the splicing and coding regions of the PTCH gene. In conclusion, the PTCH gene does not seem to be involved in GOC pathogenesis.     

New mutation of the patched homologue 1 gene in a Chinese family with naevoid basal cell carcinoma syndrome

Naevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, is inherited in an autosomal dominant mode characterised by a combination of developmental anomalies and a predisposition to form tumours. Our aim was to search for patched homologue 1 (PTHC1) mutations in a Chinese family with NBCCS. Mutation analysis of PTCH1 was done of all 10 members of this family by amplified polymerase chain reaction and direct sequencing. Two novel PTCH1 mutations (3146A→T, 1686C→T) were identified in all five affected members. The mutation, 3146A→T in exon 17, is predicted to lead to different PTCH protein translations. 1686C→T mutation in exon 11 is a nonsense mutation. These mutations were not found in any unaffected members of this family or in 100 unrelated healthy Chinese people. Our findings suggest that the 3146A→T mutation in the PTCH gene may be the cause of NBCCS by affecting the conformation and function of the PTCH protein.