皮肤基底细胞癌分子生物学研究进展

基底细胞癌是一种常见的皮肤恶性肿瘤，一系列研究发现，信号基因PTCH的突变与基底细胞癌的发生有密切关系，这极大的促进了基底细胞癌分子生物学研究机制的进程，现将近几年来有关于基底细胞癌发生的分子机制研究情况做一综述。     

痣样基底细胞癌综合征一例PTCH1基因突变研究

目的：检测1例痣样基底细胞癌综合征(Gorlin综合征)患者的PTCH1基因突变。方法：收集患者临床资料,提取患者及其3位相关亲属（患者的父母及妹妹）外周血DNA,采用PCR扩增PTCH1基因编码区的全部外显子及其侧翼序列。同时以200例无关健康者外周血基因组DNA作对照。 结果：患者的PTCH1基因发生c.590G>A杂合突变,导致氨基酸发生p.W197X改变。患者的父母、妹妹及200例健康对照未见该基因突变位点。结论：PTCH1基因p.W197X突变很可能是本例患者Gorlin综合征的病因。     

痣样基底细胞癌综合征家系的PTCH1基因突变检测

目的:检测痣样基底细胞癌综合征(NBCCS)家系中先证者和12个家系成员的PTCH1基因突变情况。方法:收集先证者和家系成员的临床资料,提取其外周血DNA,采用聚合酶链式反应(PCR)扩增PTCH1基因编码区的全部外显子和侧翼序列,测序明确突变位点。结果:Sanger测序发现先证者和家系中2个患病成员均携带PTCH1基因9号外显子的第1 341位碱基A发生重复的移码突变(c.1341dupA),导致其编码的448位氨基酸发生移码突变(p.L448fs)。结论:PTCH1基因的检测为该家系提供分子诊断和预测。     

痣样基底细胞癌综合征一家系PTCH1基因突变分析

目的 对痣样基底细胞癌综合征一家系进行PTCH1基因突变分析。 方法 提取先证者（Ⅱ5）及Ⅱ1、Ⅱ3、Ⅲ4的DNA,以50例健康人为对照。应用聚合酶链反应（PCR）、DNA直接测序明确突变位点,根据突变位点设计特异性引物,用PCR来检测突变位点从而进一步确定该家系的致病原因。 结果 先证者PTCH1基因的1条等位基因第14号外显子上2137位胞嘧啶C被胸腺嘧啶T替代（c.2137C > T）,即CAG→TAG,导致终止密码产生（Q714X）,Ⅲ4也检测到相同突变。健康对照者中未检出该突变。 结论 PTCH1基因的无义突变（c.2137C > T）可能是引起该患者临床症状的特异性突变。     

痣样基底细胞癌综合征研究进展

痣样基底细胞癌综合征是一种罕见的常染色体显性遗传性疾病,目前发现的致病基因包括PTCH1和PTCH2,该病可有皮肤损害、口腔损害、骨骼损害、眼睛损害及中枢神经系统损害等,治疗上采取相应的综合性措施。     

基底细胞癌分子生物学机制研究进展

基底细胞癌是最常见的皮肤恶性肿瘤。随着基因测序技术的进步,已发现多个基因参与基底细胞癌的发病机制。其中,PTCH1、SMO、GLI、SUFU的突变导致Hedgehog(HH)通路的异常激活、TP53基因突变与基底细胞癌关系最密切。此外,一些新基因及通路也参与基底细胞癌的形成及发展,包括Hippo-YAP通路、 MYCN/FBXW7基因、TERT基因、DPH3-OXNAD1基因等。本文回顾了近年来基底细胞癌研究的主要分子机制。     

基底细胞癌的分子遗传机制研究进展

基底细胞癌是一种最为常见的皮肤癌。近年来研究表明,SHH信号通路的变异在基底细胞癌的发生中起到一个关键的作用,SHH通路的重要成员包括SHH、PTCH1、SM0、GLI,SHH的失调与细胞的PTCH1基因突变相关,SMO的过度激活和转录因子GLI的异常导致多种细胞生长和增殖的基因转录表达上调,并促进了基底细胞癌的形成。SHH信号通路抑制剂对肿瘤的抑制作用为基底细胞癌的治疗提供了一个新的策略。     

痣样基底细胞癌综合征1例并文献复习

目的报道痣样基底细胞癌综合征(NBCCS)1例,总结其临床特点及治疗效果,提高对NBCCS的认识。方法报告2007年至2019年在甘肃省人民医院确诊的1例NBCCS患者的临床表现、影像学表现及病理检查结果,并复习相关文献。结果 NBCCS为罕见的常染色体显性遗传性疾病,由PTCH1、PTCH2等多种基因的显性突变引起。临床主要表现为多发性基底细胞癌、多发性颌骨角化囊肿、掌角化障碍和颅内异位钙化、面部畸形(畸形眼、唇腭裂、严重眼畸形)及骨骼系统异常、多器官发育障碍等。临床诊断主要依赖诊断标准,PTCH基因检测可证实诊断。NBCCS涉及多个器官系统,治疗需多学科综合管理,定期复查CT、MRI等明确病变进展情况。结论 NBCCS临床罕见,发病机制尚未明确。临床医师应提高对该病的认识,减少临床误诊。     

口周色素沉着-肠道息肉综合征STK11基因遗传学研究进展

口周色素沉着-肠道息肉综合征(PJS)是一种少见的常染色体显性遗传性疾病.以胃肠道错构瘤息肉和口腔黏膜、手、足和唇部色素沉着为特征.STK11基因的胚系突变是PJS的主要致病因素,定位于染色体19p13.3,编码丝氨酸/苏氨酸蛋白激酶.STK11基因是一种抑癌基因,目前研究显示STK11基因主要是通过对细胞周期的阻滞作用和对细胞凋亡的促进作用抑制肿瘤的发生.到目前为止,在人类基因突变数据库(HGMD)中,已经报道了145种PJS患者STK11基因的胚系突变及40种体细胞突变.其突变研究有待于进一步深入.     

肿瘤生长抑制基因ING1在基底细胞上皮瘤中的表达及突变分析

目的 研究肿瘤生长抑制基因ING1在基底细胞上皮瘤中是否存在过度表达及基因突变。方法 搜集了54份基底细胞上皮瘤标本，运用免疫组织化学染色，DNA单链构象多态性分析(SSCP)及DNA序列测定的方法研究ING1基因在基底细胞上皮瘤中的表达及突变情况。结果 免疫组化显示ING1基因在25％(6／24)基底细胞上皮瘤标本中过度表达。SSCP及DNA序列测定结果显示54例基底细胞上皮瘤标本中仅1例标本(1．8％)发生实质突变。突变发生在ING1基因编码区exon2，因而可能影响所有ING1异构体结构，并影响PHD锌指基序的功能。结论 ING1基因在基底细胞上皮瘤中无明显过度表达及突变。     

UV-specific p53 and PTCH mutations in sporadic basal cell carcinoma of sun-exposed skin

UVB irradiation is known to produce DNA damage at mutation hotspots in the p53 tumor suppressor gene, leading to the development of skin cancers. Mutations in the PTCH tumor suppressor gene, which is known to be responsible for the development of nevoid basal cell carcinoma syndrome, have also been identified in sporadic basal cell carcinomas (BCCs). We describe the case of an 80-year-old welder in whom 3 novel p53 mutations, as well as UV-specific PTCH mutations, were detected in two BCC samples from sun-exposed skin. The simultaneous presence of UV-specific p53 and PTCH mutations in the same BCC sample has not previously been reported.     

Unique features of PTCH1 mutation spectrum in Chinese sporadic basal cell carcinoma

Background Alterations of the PTCH1 gene have been found to contribute to both familial and sporadic basal cell carcinoma (BCC), especially in Caucasian patients. Furthermore, the majority of PTCH1 gene mutations in sporadic BCCs in Caucasian patients carry ultraviolet (UV) signatures, suggesting the key role of UV light in BCC development. However, sporadic BCC in non‐Caucasian population has a lower incidence, and the pathogenesis remains largely unknown. To date, there has been no mutation analysis on PTCH1 gene in Chinese patients with sporadic BCCs. Objective To investigate genetic alterations of the PTCH1 gene in Chinese sporadic BCCs. Methods Direct sequencing was used to screen for mutations in PTCH1 in 31 microdissected samples in Chinese sporadic BCCs. In addition, single nucleotide polymorphisms (SNPs) were studied for loss of heterozygosity (LOH). Results Nineteen PTCH1 mutations in 17 of the 31 BCCs (54.8%) were identified. SNP analysis revealed LOH of PTCH1 in 10 of 23 BCCs (43.5%). Interestingly, the majority of mutations identified (63.2%) were insertion/deletion, which was different from the results in Caucasian cases whose mutations are predominantly point mutations. Only two (10.5%) of the remaining seven mutations were UV‐specific C → T transition or tandem CC → TT transitions. All mutations occurred evenly throughout the entire PTCH1 protein domain without a hot‐spot detected. Conclusion Mutations and LOH in PTCH1 were also highly prevalent in Chinese sporadic BCCs. However, UV light plays a less role in causing these mutations, suggesting other potential mechanisms in the development of sporadic BCC in Chinese patients.     

Congenital linear unilateral basal cell nevus: a case report with patched gene molecular studies

BACKGROUND: Linear unilateral basal cell nevus represents a linear collection of macules and papules histologically similar to basal cell carcinoma but with benign clinical behavior. We describe a patient who initially presented at the age of 6 months with a unilateral linear basal cell nevus on the right flank. The differential diagnosis included the nevoid basal cell carcinoma syndrome. Constitutional PTCH mutations are causative of the nevoid basal cell carcinoma syndrome, and somatic PTCH mutations are found in the vast majority of basal cell carcinomas. Somatic SMO mutations have also been found in some basal cell carcinomas. METHODS: Histologic examination of the lesions is performed. Short tandem-repeat molecular analysis at the PTCH locus and sequencing of PTCH and SMO genes is performed. RESULTS: Histologic examination revealed features initially indistinguishable from basal cell carcinoma. Short tandem-repeat DNA analysis did not reveal loss of heterozygosity at the PTCH locus. DNA sequencing of both the PTCH and the SMO genes from the patient's lesions revealed neither inactivating mutations of PTCH nor activating mutations of SMO. CONCLUSION: Molecular examination indicates that the PTCH and SMO genes are not involved in the pathogenesis of the patients' congenital linear unilateral basal cell nevus. Furthermore, we discuss the relationship between linear basal cell nevus and basaloid follicular hamartoma.     

Clinical and genetic study in 22 patients with basal cell nevus syndrome

BACKGROUND: Nevoid basal cell carcinoma syndrome is an autosomal dominant disorder characterized by developmental abnormalities and cancer predisposition. The PTCH 1 gene, the human homolog of the Drosophila segment polarity gene patched, has been shown to be involved in the development of nevoid basal cell carcinoma syndrome. PTCH 1 is mapped to chromosome 9q22.3. The aim of the present study was to report on clinical and genetic characteristics in patients followed for nevoid basal cell carcinoma syndrome and to compare them to the data in the literature. PATIENTS AND METHODS: Screening for PTCH 1 mutations was done in 22 patients followed between 1981 and 2003 for clinical suspicion of nevoid basal cell carcinoma syndrome. Clinical and radiological data were reviewed retrospectively from records. Genetic analysis was performed using blood samples after patient informed consent was obtained. When possible, DNA was also analyzed from the parents of patients in whom PTCH 1 mutations were found. RESULTS: All patients had developed basal cell carcinomas: 45% palmar and plantar pitting, 62% jaw cysts and 66% calcification of falx cerebri. Medulloblastomas and meningiomas were the most common associated tumors. PTCH 1 mutations were identified in 13 patients: 6 familial cases, 3 sporadic cases and for 4 patients, it was not possible to conclude. Nine different new germ-line mutations were identified. DISCUSSION: Genetic analysis allows molecular confirmation of diagnosis in about half of all patients. Early diagnosis is essential for detection of clinical and radiological manifestations in young patients and for provision of advice concerning protection of the skin from the sunlight.     

Spectrum of PTCH1 mutations in French patients with Gorlin syndrome

Gorlin syndrome or nevoid basal cell carcinoma syndrome is an autosomal dominant disease characterized by developmental abnormalities and a predisposition to cancers. The responsible gene for this syndrome is the PTCH tumor suppressor gene encoding for the Sonic Hedgehog receptor. We screened for PTCH mutations in 65 French Gorlin syndrome families or sporadic cases for the first time. Nineteen novel mutations and five new polymorphisms were identified in this group of patients. One microdeletion without frameshift underlines the importance of one amino acid for Ptc receptor function. Although no mutation hot-spot was described, we identified a recurrent mutation.     

Patched 1 expression in Merkel cell carcinoma

The relevance of Hedgehog signaling in Merkel cell carcinoma has only been addressed by a few studies with conflicting results. Thus, we aimed to establish the expression of Hedgehog signaling molecules in Merkel cell carcinoma to characterize causes of aberrant expression and to correlate these findings with the clinical course of the patients. Immunohistochemistry was performed for Sonic, Indian, Patched 1 (PTCH1) and Smoothened on patients’ tumor tissue. Respective mRNA expression was analyzed in 10 Merkel cell carcinoma cell lines using quantitative real‐time polymerase chain reaction. PTCH1 sequencing and DNA methylation microarray analyses were carried out on tumor tissues as well as cell lines. PTCH1 immunoreactivity in Merkel cell carcinoma was similar to that of basal cell carcinomas, which both significantly differed from PTCH1 immunoreactivity in healthy skin. Most PTCH1 mutations found were synonymous or without known functional impact. However, on average, the promoter regions of both PTCH1 were hypomethylated independently from PTCH1 gene expression or Merkel cell polyomavirus status. PTCH1 and GLI1/2/3 genes were differently expressed in different cell lines; notably, there was a significant correlation between GLI2 and PTCH1 mRNA expression. Similar to PTCH1 protein expression in patient tissues, PTCH1 gene expression in Merkel cell carcinoma cell lines is highly variable, but due to the similar methylation pattern across Merkel cell carcinoma cell lines, effects other than methylation seem to be the reason for the differential expression and PTCH1 appears to be upregulated by GLI as a classical Hedgehog target gene.     

Germline mutations of the PTCH gene in Japanese patients with nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by developmental and skeletal anomalies, palmo-plantar pits, odontogenic keratocysts, ectopic calcification, and occurrence of various types of tumors including basal cell carcinoma. Recent evidence has indicated that the human homologue of a Drosophila segment polarity gene, PTCH, is a NBCCS susceptibility gene. In the study presented here, we detected two novel mutations of the PTCH gene, I805X/2395delC and Y93X/C297A, in two unrelated Japanese patients. Early protection of the skin from the sunlight is important to the prevention of BCC development in NBCCS patients. Genetic analysis of the PTCH gene is essential for the early, definitive diagnosis of NBCCS, especially before the expression of clinical manifestations is complete.     

NBCCS secondary to an interstitial chromosome 9q deletion

Naevoid basal cell carcinoma syndrome (NBCCS) or Gorlin syndrome is a rare autosomal dominant cancer disorder. The Gorlin's gene, Patched 1 (PTCH1), maps to Chromosome 9q. Germline mutations of PTCH1 occur in patients with NBCCS. The subsequent loss of the remaining allele results in cancer formation. We present a patient with NBCCS and additional phenotypic features including severe developmental delay, short stature and hypotelorism who was found to have an interstitial chromosome 9q deletion. The NBCCS phenotype in our patient occurred as a result of PTCH1 deletion in contrast with an inherited mutation of this gene.     

Brooke-Spiegler syndrome: report of two cases not associated with a mutation in the CYLD and PTCH tumor-suppressor genes

Brooke-Spiegler syndrome represents an autosomal dominant disease characterized by the occurrence of multiple cylindromas, trichoepitheliomas and (sporadically) spiroadenomas. Patients with Brooke-Spiegler syndrome are also at risk of developing tumors of the major and minor salivary glands. Patients with Brooke-Spiegler syndrome have various mutations in the CYLD gene, a tumor-suppressor gene located on chromosome 16q. To date, 68 unique CYLD mutations have been identified. We describe two families with Brooke-Spiegler syndrome, one with familial cylindromatosis and one with multiple familial trichoepithelioma, which showed wide inter-family phenotypic variability. Analysis of germline mutations of the CYLD and PTCH genes was performed using peripheral blood. In addition, formalin-fixed paraffin-embedded tumor samples were analyzed for PTCH somatic mutations and cylindroma cell cultures were obtained directly from patients for further growth and analysis. Clinically, the major features of Brooke-Spiegler syndrome include the presence of heterogeneous skin tumors and wide inter- and intra-familial phenotypic variability. Histopathologically, both cylindromas and trichoepitheliomas were found in affected individuals. Mutations or loss of heterozygosity was not found in CYLD and PTCH genes. In CYLD and PTCH mutation-negative patients, other genes may be affected and further studies are needed to clarify whether these patients may be affected by de novo germline mutations.     

Occurrence and comparison of the expressed keratins in cultured human fibroblasts,endothelial cells and their sarcomas

Mutations of p53 and PTCH gene, two candidate tumor suppressor genes for basal cell carcinoma (BCC), were screened in 15 cases of sporadic BCCs that developed in sun-exposed skin region in a Korean population. p53 and PTCH mutations were detected at a frequency of 33 and 40%, respectively, and the mutations were predominantly UV-signature transition, C-->T transitions at dipyrimidine sites and CC-->TT tandem mutations. In both genes, the most common mutations were missense mutations resulting in amino acid substitution, which is different than the results from Caucasian BCCs where mutations are frequently predicted to make truncated or absent proteins. All mutations, except for one, occurred on the nontranscribed strand where is little efficient removal of UV-induced pyrimidine dimers relative to the transcribed strand. Loss of heterozygocity (LOH) of 9q22 for PTCH loci was found in eight of 15 informative cases of BCCs (53%), but none of the cases were informative for LOH of 17p13 for p53 loci. Not only do our data indicate the key role played by p53 and PTCH in the development of BCCs, these findings also suggest that UVB may significantly contribute to BCC tumorigenesis. Moreover, molecular epidemiology composed of incidence of p53 and PTCH mutations, difference in the type of mutation and repair bias of UV-induced DNA lesions might affect the distinct features of BCCs between different racial population.