Natural history of bronchial preinvasive lesions

Preinvasive bronchial lesions defined as dysplasia and carcinoma in situ (CIS) have been considered as precursors of squamous cell carcinoma of the lung. The risk and rate of progression of preinvasive lesions to invasive squamous cell carcinoma as well as the mechanism of progression or regression are incompletely understood. While the evidence for the multistage, stepwise progression model is weak with relatively few documented lesions that progress through various grades of dysplasia to CIS and then to invasive carcinoma, the concept of field carcinogenesis is strongly supported. The presence of high-grade dysplasia or CIS is a risk marker for lung cancer both in the central airways and peripheral lung. Genetic alterations such as loss of heterozygosity in chromosome 3p or chromosomal aneusomy as well as host factors such as the inflammatory load and levels of anti-inflammatory proteins in the lung influence the progression or regression of preinvasive lesions. CIS is different than severe dysplasia at the molecular level and has different clinical outcome. Molecular analysis of dysplastic lesions that progress to CIS or invasive cancer and rare lesions that progress rapidly from hyperplasia or metaplasia to CIS or invasive cancer will shed light on the key molecular determinants driving development to an invasive phenotype versus those associated with tobacco smoke damage.     

Mutation of p53 gene codon 63 in saliva as a molecular marker for oral squamous cell carcinomas

The inactivation of tumor suppressor gene (TSG) is important during multistage carcinogenesis. The p53 TSG is frequently mutated in oral squamous cell carcinomas. These mutations can serve as very specific markers for the presence of tumor cells in a background of normal cells. In this study, 10 oral squamous cell carcinoma patients and 27 normal dental students were collected from Chung Shan Medical and Dental College Hospital, Taichung, Taiwan. Extractions of DNA from saliva were obtained. Exon 4 and intron 6 within the p53 gene were amplified with polymerase chain reactions (PCRs) followed by DNA sequence analysis. DNA sequence analysis of PCR products revealed that five of eight (62.5%) tumor saliva samples and five of 27 (18. 52%) healthy saliva samples contained p53 exon 4 codon 63 mutations. These results were significantly different by using Chi-square test (P<0.05). The majority of the base substitutions were C deletions. Probable hot spots for the mutation were identified at exon 4 codon 63, which has not been observed before in head and neck cancers. Our study indicated that mutation of p53 codon 63 in saliva might be a molecular marker for oral squamous cell carcinomas. In addition, the amount of DNA recovered from saliva in most cases is sufficiently large and its quality suitable to enable PCR amplification which could be used in the search for mutations. The protocol described is rapid, cheap, and easy to perform, and may be useful for epidemiological studies for oral carcinogenesis.     

Role of p53 gene mutations in human esophageal carcinogenesis: results from immunohistochemical and mutation analyses of carcinomas and nearby non-cancerous lesions

In order to characterize p53 alterations in esophageal cancer and to study their roles in carcinogenesis, we performed gene mutation and immunohistochemical analysis on 43 surgically resected human esophageal specimens, which contain squamous cell carcinoma (SCC) and adjacent non-cancerous lesions, from a high-incidence area of Linzhou in Henan, China. A newly developed immunohisto-selective sequencing (IHSS) method was used to enrich the p53 immunostain-positive cells for mutation analysis. p53 gene mutations were detected in 30 out of 43 (70%) SCC cases. Among 29 SCC cases that were stained positive for p53 protein, 25 (86%) were found to contain p53 mutations. In five cases of SCC with homogeneous p53 staining, the same mutation was observed in samples taken from four different positions of each tumor. In a well differentiated cancer nest, p53 mutation was detected in only the peripheral p53-positive cells. In tumor areas with heterogeneous p53 staining, either the area stained positive for p53 had an additional mutation to the negatively stained area or both areas lacked any detectable p53 mutation. In the p53-positive non-cancerous lesions adjacent to cancer, p53 mutations were detected in seven out of 16 (47%) samples with basal cell hyperplasia (BCH), eight out of 12 (67%) samples with dysplasia (DYS), and six out of seven (86%) samples with carcinoma in situ (CIS). All mutations found in lesions with DYS and CIS were the same as those in the nearby SCC. In seven cases of BCH containing mutations, only three had the same mutations as the nearby SCC. The results suggest that p53 mutation is an early event in esophageal carcinogenesis occurring in most of the DYS and CIS lesions, and cells with such mutations will progress to carcinoma, whereas the role of p53 mutations in BCH is less clear.     

p53 gene mutations in esophageal squamous cell carcinoma and their relevance to etiology and pathogenesis: results in Japan and comparisons with other countries

Esophageal squamous cell carcinoma is a form of cancer that has varying incidence rates among different countries, distinct geographic areas and different ethnic groups. According to previous reports, p53 gene mutations have been identified in 20-80% of these tumors, and these mutations have occurred at an early stage. These findings suggest that such mutations play an important role in esophageal carcinogenesis, and highlight the importance of mutagens, which cause sequence alterations in the p53 gene. In order to clarify the environmental factors and the molecular mechanisms that may be responsible for the occurrence and prevention of a specific mutation in the process of esophageal carcinogenesis, we analyzed p53 gene mutations in 95 samples of esophageal squamous cell carcinoma. We further reviewed published reports investigating the frequency of p53 gene mutations in esophageal cancer from high-risk areas to normal-risk areas and compared these findings to our results in Japan. The frequency of p53 gene mutations in Japanese esophageal cancer is 47.4% and there are three prominent features: (1) a predominance of transversions, in particular the G:C to T:A transversion; (2) a relatively low frequency of transitions; and (3) a relatively high percentage of frameshift mutations. These results indicate the possible importance of the benzo[a]pyrene metabolite and oxidative DNA damage in esophageal carcinogenesis and scarcely correlate with DNA replication errors or alkylation in comparison to other gastrointestinal cancers. In addition, we observed a peculiar sequence of frameshift mutations. Taken together, these data suggest that this tumor suppressor gene plays a critical role in the multistep carcinogenesis process for esophageal squamous cell cancer.     

Heterogeneity of p53 Mutational Status in Esophageal Squamous Cell Carcinoma

In esophageal squamous cell carcinoma, p53 gene mutations have been analyzed for inter- or intra-patient heterogeneity but only a few studies have investigated intratumoral heterogeneity. We investigated this question within individual esophageal cancers, and also in their lymph-node metastases in 8 cases. Analyzing the p53 gene sequence by direct sequencing of polymerase chain reaction products, we found heterogeneity for p53 mutations in the pre-invasive area in 3 esophageal cancers. In all areas sampled in the invasive portion of each cancer, the p53 mutational status was identical in a given tumor. In heterogeneous tumors, the invasive area showed one of the p53 mutations found in the pre-invasive area. In nodal metastases, the p53 mutation was identical to that in the invasive area of each primary tumor. These data suggest that the timing of p53 alteration is not as early as might have been expected, indicating that, in regard to p53 gene alteration, some esophageal cancers are composed of various subclones in the pre-invasive stage with invasiveness developing in one of them, which becomes predominant through clonal selection.     

P53 expression in esophageal dysplasia - a possible biomarker for carcinogenesis of esophageal squamous-cell carcinoma

The tumor suppressor gene product p53 has been detected in a high percentage of esophageal squamous cell carcinoma. To evaluate the role of this protein in carcinogenesis, we examined the p53 overexpression both in esophageal dysplasia and in esophageal squamous cell carcinoma in the same patients. Using anti-p53 antibodies pAb1801 and CM-1, we analyzed immunohistochemically 36 dysplastic lesions from 36 patients with esophageal cancer. Nuclear p53 was detected in 14 of 36 dysplasias (39%). From mild to moderate to severe dysplasia, p53 positivity showed tendency to increase in number. Seventeen of the 36 squamous cell carcinomas showed p53 expression (47%). There was a significant concurrent p53 expression in esophageal dysplasia and its related squamous cell carcinoma (p=0.00345). These results indicate that p53 mutation is closely associated with the initiation of this cancer.     

p53 alterations in chemically induced hamster cheek-pouch lesions

To confirm that the hamster cheek-pouch carcinogenesis model reflects development of human squamous cell carcinoma (SCC), we determined if and when p53 mutations occur in the development of SCC in this model by using immunohistochemical staining and polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis plus direct DNA sequencing. Twenty-four hamster cheek-pouches were treated with a solution of 0.5% 7,12-dimethylbenz[a]anthracene in mineral oil three times a week for 16 wk. The malignant endophytic and exophytic tumors induced with this protocol are preceded by a sequence of premalignant lesions such as hyperplasia with or without dysplasia and carcinoma in situ, similar to the development of this cancer in humans. For this study, p53 protein accumulation was evaluated by immunostaining of various hamster cheek-pouch exophytic and endophytic SCCs as well as flat dysplastic hyperplasia and carcinomas in situ. A moderate percentage (33.3%) of exophytic lesions and most endophytic carcinomas (90%) showed positive p53 staining. In addition we also found p53-positive staining in a number of preneoplastic lesions, including areas of focal hyperplasia, dysplastic hyperplasia, and carcinomas in situ. To determine whether the alterations in p53 staining were due to p53 gene mutation, we used PCR-SSCP analysis and direct sequencing. PCR products corresponding to exons 5a, 6, 7, and 8 from 40 tumors with the highest percentage of p53-stained cells were analyzed. We detected shifted bands in 17 lesions. Direct sequencing of eight selected shifted bands revealed four mutations, including two G→T transversions in codons 216 (tumor #1) and 252 (tumor #2) and one G→C transversion in codon 282 (tumor #3). Tumor #4 contained a frameshift mutation in codon 251. These mutations are consistent with those reported in many human cancers. Therefore, we concluded that in the hamster cheek-pouch model, p53 protein accumulation occurs frequently and early in carcinogenesis, as it does in human SCCs, and some of these p53 alterations are due to p53 gene mutations. These findings may help us better define the mechanisms of carcinogenesis in the hamster cheek-pouch model, and p53 alterations may be an early biomarker of progression for chemoprevention studies. © 1996 Wiley-Liss, Inc.     

Detection of p53 gene mutations in human esophageal squamous cell carcinomas using a p53 yeast functional assay: possible difference in esophageal carcinogenesis between the young and the elderly group.

A p53 yeast functional assay, which cannot only detect p53 gene mutations but also can assess p53 gene function, was used to screen for p53 gene dysfunction in human esophageal squamous cell carcinomas. Surgically resected frozen tissues of esophageal squamous cell carcinomas from 57 patients were examined for p53 gene mutation. Because the mean age of the patients diagnosed with esophageal squamous cell carcinoma was 64 years, we classified those who were <65 years of age as the Young Group and classified the others as the Elderly Group. The incidence of p53 gene mutations was 43 of 57 (75%). The incidence of p53 gene mutations observed in the Young Group was significantly higher than in the Elderly Group (P = 0.0007). Alcohol and smoking status did not relate to p53 gene mutation expression. Survival rate after surgery was not significantly associated with the presence of p53 gene mutation. However, in the Young Group with p53 gene mutation, those who had null mutations had a significantly shorter survival than those without null mutations (P = 0.0455). No other clinicopathological factors were associated with p53 gene mutations. Possibly, there may be a difference in esophageal carcinogenesis between the Young and the Elderly groups, because the incidence of p53 gene mutations is different between the two groups. In the Young Group, p53 gene mutation may cause esophageal carcinogenesis, and null mutation for p53 gene is a significant prognostic factor.     

p53 Gene mutation and genetic instability in superficial multifocal esophageal squamous cell carcinoma

Tumor multicentricity is occasionally observed in esophageal squamous cell carcinoma (SCC). We studied five surgically resected superficial multifocal esophageal SCCs for p53 gene mutation and genetic instability, using DNA extracted from microdissected areas. A total of 38 target areas (TAs) were analyzed in SCC, dysplasia, basal cell hyperplasia (BCH) and normal squamous epithelium. Analysis of the replication error (RER) at 10 microsatellite loci showed microsatellite instability in all TAs, as well as in normal squamous epithelium. p53 gene mutation was identified in 28.9% (11/38 TAs). All cases showed a common missense mutation in exon 8 at codon 273 (CGT-->CAT, Arg-->His), which was DNA contact mutation in the S10 beta strand. In association with microsatellite alterations, 7 of 9 TAs with p53 mutation in exon 8 at codon 273 also showed loss of heterozygosity (LOH) of p53 gene. LOH of p53 gene was detected in 83.8% (31/37 TAs). LOH at D2S123 on 2p16 near MSH2 gene and at D3S1611 on 3p22 near MLH1 gene was detected in 65.4% (17/26) and 71.4% (10/14) TAs, respectively. Frequencies of LOH at p53 and D2S123 were similar in non-cancerous areas and SCCs. LOH of p53 and D2S123 were found in 50% (5/10 TAs) of non-cancerous areas and 60% (9/15 TAs) of SCCs. Our results suggest that genetic instability induces esophageal tumor multicentricity, and that p53 gene contact mutation together with LOH are early events of the multistage carcinogenesis of multifocal primary esophageal SCC.     

p53 overexpression in normal and dysplastic tissues adjacent to p53 negative squamous cell carcinomas of the head and neck

p53 overexpression was present in the normal or dysplastic epithelium, but absent in the adjacent invasive cancers of five patients with head and neck squamous cell carcinomas (HNSCC), when p53 immunostaining (IHC) was performed. In three of the five p53 immunoreactive dysplasias and adjacent p53 negative invasive cancers single stranded conformation polymorphism (SSCP) results from exon 7 and 8 were also obtained. Bandshifts in exon 7 were detected in two dysplasias, and bandshifts in exon 8 were found in a third. Sequencing of exon 7 in the first dysplasia with bandshift indicated a deletion of codon 241-242 (loss of CT) resulting in a frame shift. In the second dysplasia with bandshift a mutation was observed in codon 244 resulting in a Gly-->Arg substitution in the protein sequence. In the adjacent IHC p53 negative invasive cancer lesions, no bandshifts could be observed by SSCP, and sequencing did not reveal any mutated p53. WAF1/p21 (IHC) expression was assayed to study p53 function. Image cytometry (ICM) DNA analysis, estimating genetic instability, showed progress in DNA aberration for invasive cancer lesions as compared with the dysplasias. Human papillomavirus (HPV DNA) was not detected by a polymerase chain reaction (PCR) in any of the five cancers thus excluding possible p53 degradation caused by HPV protein. In conclusion, the finding of p53 mutations in mild, moderate, and severe dysplasia indicates that p53 mutation, not only p53 immunoreactivity, can be an early event in HNSCC carcinogenesis. The lack of p53 immunoreactivity in the invasive cancers adjacent to p53 positive dysplasias could possibly be attributed to loss of the mutant allele, or clonal heterogeneity.     

食管脱落上皮细胞中p53基因突变的检测

目的 探讨在食管拉网细胞中进行食管癌基因检测的方法及可行性,了解食管癌前期病变细胞中p53基因的突变与癌变的关系。方法 对四川省盐亭县1982年进行食管癌普查的食管拉网脱落细胞涂片标本,应用聚合酶链反应-单链构象多态性分析(PCR-SSCP)方法,检测其p53基因第5外显子及第7外显子的突变情况。结果 全组48例标本中,食管正常上皮和重度不典型增生上皮各24例,p53基因检测均获成功。食管重度不典型增生上皮细胞中有5例检测到突变,均为p53基因第7外显子突变,而第5外显子未检测到突变;正常食管鳞状上皮拉网脱落细胞中未发现突变。检测到突变的5例食管上皮重度不典型增生者,有3例分别在10年、12年和14年后转变为食管癌。结论p53基因突变的食管上皮不典型增生细胞具有明显的癌变趋势;对食管拉网脱落细胞涂片标本进行微量DNA的提取、扩增和基因检测,可作为研究食管癌前期病变的一种新方法。     

p53 mutation profiling of multiple esophageal carcinoma using laser capture microdissection to demonstrate field carcinogenesis

Inactivation of the p53 tumor suppressor gene is one of the most frequent genetic alterations observed in human esophageal carcinomas. In patients with esophageal carcinoma, one of the significant pathological features of the tumor is the presence of multiple lesions within the esophagus. However, the molecular mechanisms involved in the occurrence of multiple lesions have remained elusive. To characterize p53 alterations in multiple esophageal carcinomas and to study their roles in carcinogenesis, we performed p53 immunohistochemical and p53 mutation analyses using laser capture microdissection on surgically resected human esophageal carcinomas from 11 patients: 9 patients with multiple esophageal carcinomas, 1 with an intramural metastasis lesion within the esophagus and 1 with an intraepithelial carcinoma lesion contiguous to the main lesion. In each of the patients with multiple esophageal carcinomas, we examined samples from 1 main lesion and 1 representative concomitant lesion. Molecular analyses of samples from fresh-frozen normal tissues and tumor tissues of the main lesion (whole tumor) were also performed by the same method. p53 protein accumulation was observed in 16 (72.7%) of 22 lesions from the 11 cases. No p53 mutation was found in normal esophageal tissues. In the 9 cases of multiple esophageal carcinomas, point mutations were detected in the whole tumor in 1 (11.1%) case, in the microdissected tumor samples of main lesions in 3 (33.3%) cases and in the microdissected tumor samples of concomitant lesions in 3 (33.3%) cases. For the microdissected tumor samples, there was a 54.5% (12/22) concordance rate between the results of immunostaining and molecular analysis. In the 8 cases of whole tumors in which a p53 mutation was not observed, 2 cases revealed p53 mutation in the microdissected tumor samples of the main lesion. All 6 cases of multiple esophageal carcinomas that showed a p53 mutation in the microdissected tumor sample had a discordant p53 mutational status between the main and concomitant lesions. In contrast, both the intramural metastasis lesion and the intraepithelial carcinoma contiguous to the main lesion showed p53 mutational patterns identical to those of the main lesions. In conclusion, the analysis of microdissected DNA by laser capture microdissection is useful for characterizing the heterogeneity of the p53 gene mutation in multiple carcinoma lesions that cannot be accurately analyzed in whole esophageal tumor DNA. The finding of different p53 gene mutations among multiple esophageal carcinoma lesions suggest further evidence of multicentric or field carcinogenesis of the human esophagus.     

Sequential p53 mutation analysis of pre-invasive and invasive head and neck squamous carcinoma

Single-stranded conformation polymorphism (SSCP) and direct sequencing were performed on uninvolved mucosa, severe dysplasia and invasive carcinoma samples from 20 patients with head and neck squamous carcinoma. Seven (35%) of the non-invasive lesions and 15 (75%) of the invasive carcinomas manifested p53 mutations. Although the majority of mutations were mis-sense, resulting in single amino acid substitution, a silent mutation encoding for the same amino acid and 2 non-sense mutations encoding a stop codon were also observed. Mutations in invasive carcinoma were mostly in exon 8 and involved codons 296, 288 and 298; non-invasive lesions showed more mutations at exons 5 to 7. Five lesions showed simultaneous mutations in 2 different exons; in 3 both non-invasive and invasive carcinomas showed primary mutation at exons 5 to 7, and invasive carcinoma showed a secondary mutation at exon 8. Different codon mutations in the same exon between dysplastic and the corresponding carcinoma samples were found in 2 cases. p53 alterations were not observed in any of the normal mucosa samples. No apparent association between p53 mutations and conventional clinicopathologic parameters, including DNA content, was found in this cohort. Our study indicates that (i) p53 alteration is an early event in the genesis of a subset of head and neck squamous carcinomas, (ii) normal mucosa within the resected specimens lacked p53 mutation, (iii) sequential mutations of different exons of the p53 gene suggests accumulation of genetic alterations during the neoplastic transformation of these lesions and (iv) the difference in codon mutation of the same exon between dysplastic and corresponding carcinoma suggests an independent clonal development. © 1995 Wiley-Liss, Inc.     

Involvement of p53 gene mutations in human endometrial carcinomas

Mutations in the p53 gene are associated with a wide variety of human malignancies. Point mutation in one allele and loss of the remaining one generally lead to inactivation of p53 protein. A high frequency of allelic losses corresponding to the 17p13.3 region that contained the p53 gene sequence was also noted in human endometrial carcinoma. Thus, in order to confirm involvement of the p53 gene in endometrial carcinogenesis, we searched for nucleotide sequence change in this gene in 42 endometrial carcinomas that had been subjected to previous LOH analyses. Using the polymerase-chain-reaction-single-strand conformation polymorphism (PCR-SSCP) method, we detected p53 gene mutations in 4 specimens. Two adenocarcinomas with allelic loss on 17p contained a mutant p53 gene in the allele that was retained. One specimen with a p53 gene mutation contained a 17q deletion but was uninformative for LOH on 17p. p53 gene mutation was also noted in the remaining stage-1 carcinoma, though the 17p deletion was not detected in the previous LOH examination. However, 5 specimens with the LOH on 17p retained the wild-type p53 gene. In the remaining 33 specimens, both alleles of p53 gene seemed to be normal. The mutations observed in 2 specimens (cases 10 and 24), involving C-to-T and T-to-G substitutions, were located in a highly conserved region. However, the mutations identified in the remaining 2 cases (29 and 35) were at regions positioned outside conserved stretches.     

Modulation of neoangiogenesis in bronchial preneoplastic lesions.

We have previously demonstrated that vascular count significantly increases in the preneoplastic lesions of the bronchial tree, starting from very low levels in the normal epithelium to a significantly higher number of microvessels in moderate dysplastic lesions and in situ carcinomas. Vascular endothelial growth factor (VEGF) protein expression has shown to be strictly associated with neovascularization both in human cancer and in various type of preinvasive lesions. A number of studies have demonstrated that mutant p53 is involved in the regulation of angiogenesis, and immunohistochemical detection of the p53 protein is associated with p53 gene mutations. In this study we looked for possible correlation between p53 protein detection, VEGF expression and vascular count in a series of preneoplastic and neoplastic lesions of the bronchial tree in order to investigate the angiogenic pattern and its genetic control in the early steps of bronchial cancer development. Twenty-four retrospective bronchial lesions with different grades of dysplasia and a case of normal bronchial epithelium were analysed. Surgical specimens removed from patients either confirmed, or suspect for lung carcinoma were stained immunohistochemically for CD34, VEGF, and p53. There were significant increases in microvascular density (MVD), VEGF, and p53 expression from normal bronchial epithelium through moderate dysplasia to in situ carcinoma to invasive cancer and these factors were significantly associated with moderate dysplastic lesions. A statistically significant difference was observed in MVD between hyperplastic-metaplastic, moderate dysplastic lesions and in situ carcinoma. A similar pattern was also observed for VEGF and p53 protein expression but no significant difference was observed between moderate dysplastic lesions and in situ carcinoma with regard to VEGF protein expression. The association between MVD, VEGF expression, p53 mutations and preinvasive lesions of the bronchial tree suggests that neoangiogenesis is early in non-small cell lung cancer (NSCLC) development and that p53 may have an important role in promoting angiogenesis in this human model of carcinogenesis.     

乳腺导管内增生病变中p53表达与外显子突变的研究

目的：肿瘤抑制基因p53异常是浸润性乳腺癌发生发展中常见事件,而其与包括普通型增生（usualductal hyperplasia,UDH）、不典型增生（atypical ductal hyperplasia,ADH）及导管内原位癌（ductal carcinoma insitu,DCIS）的乳腺导管内增生性病变关系不明。本研究旨在探讨乳腺导管内增生性病变中p53外显子突变及突变型p53蛋白表达情况,以期了解p53突变及蛋白表达在乳腺癌发生发展中的作用。方法：用高分辨率熔解曲线（high-resolution melting,HRM）结合测序研究140例乳腺导管内增生性病变中p53外显子5-8的突变情况。用免疫组化研究240例乳腺导管内增生性病变中突变型p53蛋白表达情况。结果：经过HRM分析,共17例患者DNA熔解曲线与野生型标准品熔解曲线大于阈值结合测序分析结果发现,其中16例出现p53外显子突变。p53在UDH、ADH及DCIS中的突变率为0.0%（0/40）,12.7%（8/63）和21.6%（8/37）,三者间差异显著（P〈0.05）。40例UDH中未出现突变型p53蛋白阳性表达,在14.6%（19/130）的ADH出现阳性表达,在31.4%（22/70）的DCIS中出现阳性表达,三者间差异显著（P〈0.05）。Spearman相关性分析示突变型p53蛋白表达与p53外显子突变呈正相关（r=0.792,P〈0.01）。结论：p53外显子突变及突变型p53蛋白表达发生于乳腺导管内增生性病变中的ADH与DCIS,其可能为乳腺癌发生发展中的早期事件。     

乳腺导管内增生病变中p53表达与外显子突变的研究

目的 肿瘤抑制基因p53异常是浸润性乳腺癌发生发展中常见事件,而其与包括普通型增生(usual ductal hyperplasia,UDH)、不典型增生 (atypical ductal hyperplasia,ADH)及导管内原位癌 (ductal carcinoma in situ,DCIS)的乳腺导管内增生性病变关系不明.本研究旨在探讨乳腺导管内增生性病变中p53外显子突变及突变型p53蛋白表达情况,以期了解p53突变及蛋白表达在乳腺癌发生发展中的作用.方法 用高分辨率熔解曲线(high-resolution melting,HRM)结合测序研究140例乳腺导管内增生性病变中p53外显子5-8的突变情况.用免疫组化研究240例乳腺导管内增生性病变中突变型p53蛋白表达情况.结果 经过HRM分析,共17例患者DNA熔解曲线与野生型标准品熔解曲线大于阈值结合测序分析结果发现,其中16例出现p53外显子突变.p53在UDH、ADH及DCIS中的突变率为0.0%(0/40),12.7%(8/63)和21.6%(8/37),三者间差异显著(P<0.05).40例UDH中未出现突变型p53蛋白阳性表达,在14.6%(19/130)的ADH出现阳性表达,在31.4%(22/70)的DCIS中出现阳性表达,三者间差异显著(P<0.05).Spearman相关性分析示突变型p53蛋白表达与p53外显子突变呈正相关(r=0.792,P<0.01).结论 p53外显子突变及突变型p53蛋白表达发生于乳腺导管内增生性病变中的ADH与DCIS,其可能为乳腺癌发生发展中的早期事件.     

Topographical analysis of p53 expression and DNA ploidy in early bronchial squamous cell carcinoma and preneoplastic lesions.

The significance of p53 mutations and DNA aneuploidy in carcinoma cells has been investigated on the basis of a multi-step development theory of carcinogenesis. It has, however, not been determined whether these alterations can be used as diagnostic markers for the early detection of bronchial squamous cell carcinoma (BSqCC). To address this problem, we topographically investigated p53 alterations and DNA aneuploidy in 24 X-ray-negative, early BSqCC patients with various preneoplastic lesions and in 25 non-carcinoma patients with preneoplastic lesions. Bronchial lesions (n=88) were morphologically classified as hyperplasia (HP, n=5), squamous metaplasia (SM, n=23), low-grade dysplasia (LGD, n=14), high-grade dysplasia (HGD, n=11), intraepithelial carcinoma including 'carcinoma in situ' (CIS) (IEC, n=15), and microinvasive carcinoma (MIC, n=20). Immunohistochemistry for the p53 protein and image cytometry for DNA ploidy detection were performed in serial sections of each lesion. Overexpression of p53 protein was detected in 36, 73, and 65% of the HGD, IEC, and MIC lesions, respectively. Aneuploid DNA profiles were found only in carcinoma lesions, 33% in IEC and 85% in MIC. The topographical analysis revealed two types of early BSqCCs, one with adjacent preneoplastic lesions (sequential type, n=8) and another without such lesions (de novo type, n=16). The p53 protein was frequently overexpressed in both types (sequential type, 79%; de novo type, 62%). In the sequential type, however, the p53 protein was overexpressed in HGD lesions that were directly adjacent to p53-overexpressing carcinoma lesions without exception. The present topographical study suggests that p53 mutations play an important role in the carcinogenesis of BSqCC and that p53-overexpressing HGD lesions in sequential types should be regarded as 'truly' preneoplastic lesions that actually develop into carcinomas. In addition, our study demonstrated that DNA aneuploidy might occur at times after p53 alteration with increasing frequency, as invasive growth begins. Such combination analysis of p53 immunohistochemistry and nuclear DNA ploidy in routine histology may contribute to estimates of malignant potential in preneoplastic and intraepithelial squamous lesions and provide additional information for early detection of BSqCC.