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 and protein accumulation during multistage human esophageal carcinogenesis.

Preinvasive lesions of squamous cell carcinoma are well defined morphologically and provide a model for multistage carcinogenesis. Since alterations in the p53 tumor suppressor gene occur frequently in invasive esophageal squamous cell carcinoma, we examined a set of preinvasive lesions to investigate the timing of p53 mutation. Surgically resected tissues from nine patients with esophageal squamous cell carcinoma contained precursor lesions which had not yet invaded normal tissues. Immunohistochemistry showed high levels of p53 protein in both preinvasive lesions and invasive carcinomas in six cases; sequence analysis of all invasive tumors identified p53 missense mutations in two cases. Preinvasive lesions from both tumors with mutations plus one wild-type tumor were microdissected and sequenced. In one patient there were different mutations in the invasive carcinoma (codon 282, CGGarg > TGGtrp) and a preinvasive lesion (codon 272, GTGval > T/GTGleu/val). In a second case, an invasive carcinoma had a mutation in codon 175 (CGCarg > CAChis), and adjacent preinvasive lesions contained a wild-type sequence. A carcinoma and preinvasive lesion from the third case contained high levels of protein and a wild-type DNA sequence. Therefore, p53 mutation may precede invasion in esophageal carcinogenesis, and multifocal esophageal neoplasms may arise from independent clones of transformed cells. The timing of p53 protein accumulation is favorable for an intermediate biomarker in multistage esophageal carcinogenesis.     

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.     

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 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.     

食管鳞状细胞癌p53基因杂合性缺失和基因突变的相关研究

 目的 检测食管鳞状细胞癌（ESCC）中p53基因杂合性缺失（LOH），p53基因突变及蛋白表达的情况，分析其与临床病理和预后的相关性。方法 采用聚合酶链反应-单链构象多态性分析（PCR-SSCP）和免疫组织化学方法（SP）检测56例ESCC中p53基因LOH和p53基因蛋白的表达情况。结果 56例ESCC组织中p53蛋白阳性表达率为60.7 %（34／56），它与患者的年龄、性别和家族史无关（P＞0.05），有或无淋巴结转移的阳性率分别为81.0 %（17／21），48.6 %（17／35）；生存率低于3年组和高于3年组的p53阳性表达率为73.9 %（17／23），46.4 %（13／28），差异有统计学意义。p53基因LOH率为80.5 %（33／41），与患者的年龄、性别、家族史和有无淋巴结转移无关，与3年生存率有相关性（P＜0.05）。p53基因总突变率为76.8 %（43／56），突变位于17号染色体第4外显子者5例，第5外显子者23例，第6外显子者1例，第7外显子者4例，第8外显子者7例，有3例在内含子。p53基因突变／过度表达率为46.4 %（26／56），两种方法检测的符合率为55.4 %（31／56）。结论 p53基因在ESCC的发生、发展中可能发挥重要作用，伴有p53基因LOH／p53蛋白过度表达的3年生存率明显降低。p53蛋白阳性表达的ESCC更易发生淋巴结转移，可作为判断食管癌预后的参考指标之一。     

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 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.     

人食管鳞状细胞癌中p53基因突变在浙江与河南两地的差异

目的 更深入了解人食管鳞状细胞癌中p53基因突变的地域差异及临床特征之间的差异。方法 从中国食管鳞癌的高发区河南林县以及浙江省收集共92例人食管鳞状细胞癌（ESCC）标本，使用免疫组化、PCR—SSCP分析和DNA测序的方法分析p53肿瘤抑制基因。结果 p53基因的突变或过表达分别为30.4％和51.1％（P〈0．05）。p53的过表达与肿瘤的转移和患者存活期相关，两个不同地域收集的肿瘤标本中发现了不同的突变模式。结论 p53的突变或过表达在食管鳞癌的发展中可能起到了重要的作用致癌因子的各种不同组合，可能是两个地区人群中基因组的不稳定性所致，这种不稳定性在某种水平上决定了不同地区不同的发病率.     

Risk of p53 gene mutation in esophageal squamous cell carcinoma and habit of betel quid chewing in Taiwanese

A recent report suggested that BQ (BQ) chewing significantly correlated with the occurrence of esophageal squamous cell carcinoma (ESCC) in Taiwanese. BQ chewing was shown to be associated with p53 mutation in oral cancers. However, the relationship between BQ chewing and p53 mutation in ESCC is unclear. Seventy-five primary ESCC patients were enrolled for mutational analysis of the p53 gene using polymerase chain amplification and direct sequencing of amplified product. Thirty-seven mutations of the p53 gene were detected in 45.5% (34/75) of tumor specimens. These mutations significantly clustered in exon 5 (21/37) of the p53 gene. The incidence of p53 mutations did not associate with clinicopathological characteristics or the habits of cigarette smoking or alcohol consumption. However, BQ chewers exhibited significantly higher incidence of p53 gene mutations than non-chewers (67.6% vs 32.4%, P = 0.007). After controlling the confounding factors of cigarette smoking and alcohol intake, BQ chewing still showed significant association with the incidence of p53 mutation in ESCCs (RR = 4.23; 95% CI, 1.317-13.60). The A:T to G:C transition (8/37, 21.6%) and G:C to T:A transversion (5/23, 13.5%) were the prevalent spectrum of p53 gene mutations. All A:T to G:C transitional mutations occurred in patients with the habits of BQ chewing and cigarette smoking. Noticeably, alcohol consumption could enhance this peculiar spectrum of p53 mutation in ESCC. Accordingly, p53 might be an important molecular target of BQ carcinogens in the development of ESCC in Taiwanese.     

Unusual profile and high prevalence of p53 mutations in esophageal squamous cell carcinomas from northern Iran

Over 15,000 human tumor p53 mutations have been recorded in the scientific literature, including over 700 mutations in esophageal tumors. There are no data on p53 mutations in esophageal cancer patients from Iran yet; however, this country experiences one of the highest cancer mortality rates in the world for esophageal squamous cell carcinomas (ESCCs). The causes of this high cancer burden in Iran remain obscure and do not appear to be related to tobacco and alcohol consumption, the two major risk factors identified in Europe and North America. Because molecular analysis of tumors can provide clues to endogenous or environmental factors contributing to high cancer risk, we examined 74 Iranian ESCCs for the presence of mutations in exons 5-8 of the p53 gene by PCR and direct sequencing. Forty-eight of the 74 tumors (65%) had one or more p53 gene point mutations, including 5 patients with two or more mutations and one with a tandem mutation in codon 242. Surprisingly, over one-third of the 54 mutations we identified were transitions at CpG sites (20 of a total of 54 mutations, or 37%), a class of mutation that is significantly less common (16% of mutations) in the compilation of ESCC mutations from other countries (chi2 statistic, P < 0.0002), whereas transversions, which the literature shows to be common in ESCCs from non-Iranian patients, were infrequent in the tumors we examined here. Elevated levels of cyclooxygenase-2 and inducible nitric oxide synthase were observed in 74 and 91%, respectively, of tumors from Tehran as determined by immunohistochemistry, and high COX-2 expression correlated significantly with the presence of a p53 mutation in the tumor. Mediators of the inflammatory response in esophageal mucosa, perhaps in conjunction with specific dietary or cultural practices in Iran, may contribute importantly to the p53 mutation load in Iranian ESCC patients.     

食管鳞癌中p53 、p57Kip2和CD68的表达及其临床意义

目的 探讨p53 、p57Kip2和CD68蛋白在食管鳞癌组织中的表达及其与食管鳞癌生物学行为的关系。方法 应用免疫组化SP法检测51例食管鳞癌组织中p53 、p57Kip2和CD68蛋白的表达,并分析3种蛋白表达之间及其分别与临床病理特征之间的关系。结果 食管鳞癌组织中p53 、p57Kip2和CD68的阳性表达率分别为64.71％、45.09％和58.82％;p53和CD68表达与分化程度、淋巴结转移及TNM分期有关（P＜005）;p57Kip2的阳性表达与分化程度和淋巴结转移有关（P＜0.05）,与TNM分期无关（P＞0.05）。p53阳性表达者的p57Kip2阳性表达率为2424％,明显低于p53阴性表达者的8333％（P＜0.05）;CD68阳性表达者的p57Kip2阳性表达率为2000％,亦明显低于p53阴性表达者的8095％（P＜0.05）。结论p57Kip2与CD68、p53在食管鳞癌中的表达呈负相关,3项指标联合检查有助于判断患者的预后。     

Low incidence of p53 mutations in betel quid and tobacco chewing-associated oral squamous carcinoma from India

Mutations of the p53 tumor suppressor gene have been found to be the single most frequent event in human cancers. In India and other southeast Asian countries tobacco chewing with betel quid was attributed to be the major factor in oral carcinogenesis. We have analyzed 72 untreated primary oral squamous cell carcinomas (SCCs) for mutations in the tumor suppressor gene p53 exons 4-9 by PCR-SSCP and DNA sequencing. Sequencing analysis revealed 16 missense mutations, one silent mutation in codon 307 and four A to G substitution polymorphism in codon 213. The incidence of p53 mutation was 21% (15 of 72) excluding the polymorphism and the silent mutation. Eight mutations were clustered in codons 266-282 of exon 8. Of the total mutation events 37.5% were G to A transitions and 31.3% were G to T transversions. These results indicate the possible involvement of tobacco derived nitrosamines and their adducts in the genesis of oral cancer among Indians.     

Zinc deficiency potentiates induction and progression of lingual and esophageal tumors in p53-deficient mice

Upper aerodigestive tract (UADT) cancer, including oral and esophageal cancer, is an important cause of cancer deaths worldwide. Patients with UADT cancer are frequently zinc deficient (ZD) and show a loss of function of the pivotal tumor suppressor gene p53. The present study examined whether zinc deficiency in collaboration with p53 insufficiency (p53+/-) promotes lingual and esophageal tumorigenesis in mice exposed to low doses of the carcinogen 4-nitroquinoline 1-oxide. In wild-type mice, ZD significantly increased the incidence of lingual and esophageal tumors from 0% in zinc sufficient (ZS) ZS:p53+/+ mice to approximately 40%. On the p53+/- background, ZD:p53+/- mice had significantly greater tumor incidence and multiplicity than ZS:p53+/- and ZD:p53+/+ mice, with a high frequency of progression to malignancy. Sixty-nine and 31% of ZD:p53+/- lingual and esophageal tumors, respectively, were squamous cell carcinoma versus 19 and 0% of ZS:p53+/- tumors (tongue, P = 0.003; esophagus, P = 0.005). Immunohistochemical analysis revealed that the increased cellular proliferation observed in preneoplastic lingual and esophageal lesions, as well as invasive carcinomas, was accompanied by overexpression of cytokeratin 14, cyclooxygenase-2 and metallothionein. In summary, a new UADT cancer model is developed in ZD:p53+/- mouse that recapitulates aspects of the human cancer and provides opportunities to probe the genetic changes intrinsic to UADT carcinogenesis and to test strategies for prevention and reversal of this deadly cancer.     

食管鳞癌自发细胞凋亡和核增殖抗原p53关系的研究

目的通过对食管鳞癌组织中凋亡细胞的原位观察和核增殖抗原（ＰＣＮＡ）的表达状态的研究,探讨不同增殖情况的食管鳞癌组织细胞凋亡情况,同时研究ｐ５３基因的突变和ｐ５３蛋白的表达对食管鳞癌组织细胞凋亡的影响。方法３０例术前未经任何治疗的食管鳞癌手术标本,分别进行凋亡细胞的原位检测（ＴＵＮＥＬ）、ＰＣＮＡ、ｐ５３蛋白的免疫组化染色和ｐ５３基因５,６,７,８外显子ＰＣＲ－ＳＳＣＰ检测。结果不同增殖能力的癌组织中,细胞凋亡的程度差异有显著性（Ｐ＜０．０５）。ｐ５３基因突变组中,增殖程度高与增殖程度低者之间癌细胞凋亡的程度差异有显著性（Ｐ＜０．０５）。ｐ５３基因突变组与非突变组、ｐ５３蛋白表达阳性组与非阳性组癌细胞凋亡的程度差异无显著性（Ｐ＞０．０５）。结论食管鳞癌组织中,细胞增殖活跃则自发性凋亡也相应增多     

p53 expression and p21 expression are mutually exclusive in esophageal squamous cell carcinoma

The accumulation of p53 protein, which is considered to be caused by a p53 gene mutation, is closely associated with poor prognosis in patients with certain types of carcinomas. The progression of esophageal squamous cell carcinoma (ESCC) is also suspected to depend on p53 gene status. We analyzed the relationship between p53 and p21 protein accumulation in ESCC, and simultaneously analyzed the frequency of apoptosis. Formalin-fixed paraffin-embedded sections were taken from 46 patients who underwent esophagectomy for ESCC. These sections were examined by immunostaining with monoclonal antibodies PAb1801 and EA10 to determine p53 and p21 protein accumulation, respectively. We also analyzed the frequency of apoptosis by TdT-mediated dUTP-biotin nick end-labeling (TUNEL). For estimation of the proportion of stained cells, we used computer analysis with NIH image analysis software. p21 protein accumulation showed an almost inverse distribution to that of p53 protein. In areas where both p53 and p21 proteins were accumulated, few apoptotic cells were observed. Particularly in cases of mucosal tumors, p53 protein was prominently accumulated in the lower layer of the tumor, whereas p21 protein accumulation was confined to the upper layer. Our results suggest that progression of esophageal squamous cell carcinoma is controlled by a p53-dependent pathway.     

p53 mutations in formaldehyde-induced nasal squamous cell carcinomas in rats.

Formaldehyde induces squamous cell carcinomas in the nasal passages of rats following chronic inhalation exposure at concentrations of > or = 10 ppm. We have examined the complementary DNA of the tumor suppressor gene p53 from 11 primary formaldehyde-induced tumors for mutation using DNA sequence analysis. A polymerase chain reaction-amplified fragment of the rat p53 complementary DNA containing the evolutionarily conserved regions II-V was directly sequenced from each tumor. Point mutations in the p53 complementary DNA sequence were found in 5 of 11 of the tumors analyzed. These data demonstrate p53 point mutations in formaldehyde-induced squamous cell carcinomas and indicate a common alteration in certain rat and human squamous cell carcinomas of the respiratory tract.     

p53 and p16/CDKN2 gene mutations in esophageal tumors from a high-incidence area in South Africa

Squamous cell carcinoma of the esophagus has an uneven geographic distribution, with a high incidence in the Transkei region of Eastern Cape Province, South Africa. The precise molecular events associated with tumorigenesis of esophageal cancer in this region have not been characterized. DNA from human esophageal squamous cell carcinomas (n = 76), as well as adjacent tissue samples (n = 9) and blood (n = 50) from the same patients from the Transkei region were screened for somatic mutations. Exons 5–8 of the p53 gene and exons 1–2 of the p16/ CDKN2 gene were examined for mutations using PCR-SSCP procedures and DNA sequence analysis. Results show that 17% of the tumors contained small deletions, insertions and point mutations, resulting in frameshifts or amino acid changes in the p53 gene. Among the mutations in the structural p16/ CDKN2 gene, 9 were point mutations, 4 were deletions and 3 were insertions. A novel C to T mutation, 25 bp upstream from the ATG start site of p16/ CDKN2, which sometimes occurs together with other structural gene variations, was found. The mutations described here are somatic in origin since none of the DNA samples from the adjacent control tissues or blood samples from the same patients had them. Int. J. Cancer 78:544–549, 1998. © 1998 Wiley-Liss, Inc.     

Prevalence of p53 mutations and protein expression in esophageal cancers in southern Thailand

To investigate p53 alterations in esophageal squamous-cell carcinomas of patients in the high-risk area of southern Thailand, 72 paraffin-embedded samples were analyzed immunohistochemically for p53 protein expression and 16 frozen samples for p53 mutational status. Forty-two of the 72 tumors (58.3%) showed p53 protein accumulation in the nuclei of tumor cells. Expression of p53 in tumors was not significantly correlated with gender, histological grading, depth of invasion, node involvement, smoking or alcohol consumption. Analysis of the p53 gene in a sub-set of 16 tumors showed mis-sense mutations in 7 out of 11 p53-positive and 1 out of 5 p53-negative tumors. The p53 mutational spectrum was 50% transitions (3 C-to-T and 1 G-to-A, all occurring at CpG dinucleotide sites) and 50% transversions (one each, C-to-G, G-to-T, T-to-G, and T-to-A). Our findings support the hypothesis that alterations of p53 are involved in the carcinogenesis of most squamous-cell carcinomas of the esophagus, irrespective of the population and the factors responsible for carcinogenesis. The mutation profile of the p53 gene might indicate etiologic contributions of different mutagen exposures in patients from high-risk areas of southern Thailand. Int. J. Cancer 72:23–26, 1997. © 1997 Wiley-Liss Inc.     

Expression of p53R2 is related to prognosis in patients with esophageal squamous cell carcinoma.

PURPOSE: The p53 gene and its family are important factors for carcinogenesis, prognosis, and chemoresistance in esophageal squamous cell carcinoma. A recently identified ribonucleotide reductase, p53R2, is regulated by p53 for supplying nucleotides to repair damaged DNA. In the present study, we analyzed the expression and clinicopathologic significance of p53 and p53R2 in esophageal squamous cell carcinoma. EXPERIMENTAL DESIGN: We immunohistochemically investigated the relationship between p53 and p53R2 expressions in surgical specimens of primary tumors in 222 patients with esophageal squamous cell carcinoma. RESULTS: The positive expression rate of p53 was 47.1% and that of p53R2 was 61.7%. Positive p53R2 expression was significantly correlated with depth of invasion, lymph node metastasis, stage, and poor prognosis. In the p53-negative group, the 5-year survival rate was better in patients with negative p53R2 expression than in those with positive p53R2 expression. Multivariate analysis indicated that the negative expression of both p53 and p53R2 was an independent prognostic factor along with tumor depth nodal metastasis and stage. CONCLUSIONS: We showed that positive p53R2 expression was related to tumor development and that alteration of p53R2 expression in p53-negative tumors was closely related to prognosis. Evaluation of the expressions of p53 and p53R2 proteins should be useful for determining the tumor properties, including prognosis, in patients with esophageal squamous cell carcinoma.