Clinical significance of CDC25A and CDC25B expression in squamous cell carcinomas of the oesophagus

CDC25A, CDC25B and CDC25C belong to a family of protein phosphatases which activate the cyclin-dependent kinase at different points of the cell cycle. According to accumulating evidence, CDC25A and CDC25B seem to possess oncogenic properties. We have analysed these expressions by immunohistochemistry, western blot and RT-PCR in a series of 100 patients with squamous cell carcinoma of the oesophagus. When compared with non-cancerous cells, CDC25A and CDC25B were strongly expressed in the cytoplasm of cancer cells, with positive (+) classification in 46% (46 cases) and 48% (48 cases), respectively. There was no significant correlation between CDC25A and CDC25B expression, nor was there any association with the expression of other cell cycle-regulating molecules, including cyclin D1, Rb, p16(INK4), p27(KIP1)and PCNA (proliferating cell nuclear antigen). CDC25A (+), as well as CDC25B (+), was more frequently found in patients with deeper tumour invasion and lymph node metastasis, while tumour size was correlated only with CDC25A expression. Postoperative survival was significantly poorer for CDC25A (+) patients than CDC25A (-) patients, but was not affected by the CDC25B status. Nuclear localization of CDC25A was observed in 51 cases (51%), regardless of its cytoplasmic expression, and was not associated with clinico-pathological factors or prognosis. Multivariate analysis revealed only the CDC25A status to be an independent significant prognostic factor among these biological and clinico-pathological factors. CDC25A but not CDC25B may be a new prognostic factor for squamous cell carcinoma of the oesophagus. Thus, regulation of the G1 checkpoint in the cell cycle may be important in oesophageal carcinogenesis, which may also involve many other oncogenes.     

Overexpression of protease nexin-1 mRNA and protein in oral squamous cell carcinomas

Protease nexin-1 (PN-1) belongs to the serpin family of serine protease inhibitors. It is the phylogenetically closest relative of plasminogen activator inhibitor-1 (PAI-1). Whilst there are numerous studies of the occurrence and functions of PAI-1 in cancer, a possible tumour biological role of PN-1 has been almost totally neglected. We have now compared the level of PN-1 mRNA in 20 cases of oral squamous cell carcinomas and in matched samples of the corresponding normal oral tissues. We found that the average PN-1 mRNA level in tumours and normal tissues was significantly different, being increased up to 13 fold in tumour samples compared with the average level in normal tissues. The PN-1 mRNA level was significantly higher in tumours from patients with lymph node metastasis than in tumours from patients without. We could conclude that PN-1 is frequently overexpressed in oral squamous cell carcinomas and that its level may correlate with the occurrence of lymph node metastasis. We hypothesise that PN-1 may have a tumour biological function similar to that of PAI-1.     

CDC25A、CDC25B在食管鳞癌中的表达及其与凋亡和增殖的关系

目的：探讨CDC25A、CDC25B在食管鳞癌组织中表达的生物学意义及其与细胞增殖和凋亡的关系。方法：采用免疫组织化学SP法检测CDC25A、CDC25B蛋白在52例食管鳞状细胞癌、25例非典型性增生组织和24例正常黏膜中的表达。用FCM法检测其中30例食管鳞癌、5例正常黏膜的细胞凋亡率、增殖指数及CDC25A、CDC25B蛋白含量。结果：CDC25A、CDC25B在癌组织中的阳性表达率分别为50%和48%,均高于不典型增生组织（16%）和正常黏膜（0%）（P〈0.01）;CDC25A、CDC25B的表达均与细胞的分化程度、浸润深度相关,且CDC25A与淋巴结转移相关。核膜CDC25A蛋白阳性组的增殖指数高于核膜CDC25A蛋白阴性组（P〈0.05）。结论：CDC25A可能参与了食管鳞癌的发生发展,有望成为提示食管癌发生和预后的新的生物学标志;CDC25B可能只是在癌变早期发挥了作用。食管鳞癌细胞核内CDC25A蛋白可能有促细胞增殖作用。     

Overexpression of CDC25B,CDC25C and phospho-CDC25C (Ser216) in vulvar squamous cell carcinomas are associated with malignant features and aggressive cancer phenotypes

Background  

CDC25 phosphatases are important regulators of the cell cycle. Their abnormal expression detected in a number of tumors implies that their dysregulation is involved in malignant transformation. However, the role of CDC25s in vulvar cancer is still unknown. To shed light on their roles in the pathogenesis and to clarify their prognostic values, expression of CDC25A, CDC25B and CDC25C in a large series of vulvar squamous cell carcinomas were examined.     

Metformin prevents the development of oral squamous cell carcinomas from carcinogen-induced premalignant lesions

Head and neck squamous cell carcinoma (HNSCC) is a major public health concern. The recent identification of the mTOR complex 1 (mTORC1) signaling pathway as a highly prevalent molecular signature underlying HNSCC pathogenesis has provided the foundation to search for novel therapeutic approaches to prevent and treat HNSCC. Here, we asked whether metformin, the most widely used medication for the treatment of type II diabetes, which acts in part by stimulating the AMP-activated protein kinase (AMPK) signaling pathway thereby reducing mTORC1 activity, may lower the risk of HNSCC development. Indeed, we show that metformin reduces the growth of HNSCC cells and diminishes their mTORC1 activity by both AMPK-dependent and -independent mechanisms. We also optimized an oral-specific carcinogenesis mouse model that results in the accumulation of multiple oral premalignant lesions at the end of the carcinogen exposure, some of which then spontaneously progress into HNSCC. Using this mouse model, we observed that metformin specifically inhibits mTORC1 in the basal proliferating epithelial layer of oral premalignant lesions. Remarkably, metformin prevented the development of HNSCC by reducing significantly the size and number of carcinogen-induced oral tumoral lesions and by preventing their spontaneous conversion to squamous cell carcinomas. Collectively, our data underscore the potential clinical benefits of using metformin as a targeted chemopreventive agent in the control of HNSCC development and progression.     

Frequent inactivation of the TP53 gene in esophageal squamous cell carcinoma from a high-risk population in China.

Esophageal squamous cell carcinoma (ESCC) is one of the most common fatal cancers worldwide, and north central China has some of the highest rates in the world. Previous studies from tumors in this area of China have shown high frequencies of allelic loss on chromosome 17p13-11, which includes the region where the TP53 gene is found. We examined 56 ESCC patients using single-strand conformation polymorphism and DNA sequencing to assess the frequency and spectrum of TP53 mutation and the association between allelic loss at microsatellite marker TP53 and TP53 mutations. Ninety-six % of cases were found to have at least one genetic alteration, including TP53 mutation (77%), allelic loss within the TP53 gene (73%), and/or loss of heterozygosity at the TP53 microsatellite marker (80%); 75% had two or more such alterations, including 59% with both a point mutation and an intragenic allelic loss ("two hits"). The majority of mutations observed were in exon 5, where the most common type of nucleotide substitution was a G:C-->A:T or C:G-->T:A transition, including half that occurred at CpG sites. Allelic loss was most commonly found in exon 4 but was very common in exon 5 as well. Taken together, the multiple genetic alterations of TP53 in this population at high risk for ESCC indicate that there is a very high degree of genetic instability in these tumors, that TP53 is a primary target for inactivation, and that this tumor suppressor gene plays a critical role in the carcinogenesis process for ESCC.     

Human papillomavirus (HPV) DNA in esophageal precancer lesions and squamous cell carcinomas from China

A series of 51 biopsies derived from the same number of patients with established invasive squamous-cell carcinoma of the esophagus in Linxian, a high-risk area for esophageal cancer in China, were analyzed histologically and by in situ DNA hybridization to demonstrate human papillomavirus (HPV) infection. Epithelial changes suggesting HPV infection within or adjacent to the carcinoma lesions were found in 25 cases (49.0%). Esophageal lesions with HPV morphology showed both flat (25 cases) and inverted condylomas (2 cases) resembling those found in the genital tract. HPV 6, 11, 16 or 18 DNA sequences were detected in 22/51 (43.1%) of the esophageal specimens. HPV DNA was most frequently localized in epithelium adjacent to carcinomas in areas showing either epithelial hyperplasia (36.1%) or dysplasia (22.2%). Of the lesions with morphological HPV changes, 64% (16/22) were shown to contain HPV DNA. In 2 specimens, HPV DNA was found in frankly malignant cells. High-risk types HPV 16 and/or 18 DNA sequences were found in 16 of the 22 HPV DNA-positive cases (72.7%). Our results confirm previously reported HPV involvement in esophageal squamous-cell lesions, and support the hypothesis of HPV as a possible etiological agent in esophageal carcinogenesis.     

食管鳞癌及其癌前病变组织p63与Ki-67蛋白共表达临床意义的探讨

目的:研究食管癌高发区食管鳞癌组织及癌前病变标本中p63和Ki-67蛋白的联合表达,探讨其共表达与食管癌变的关系及作为早期癌变生物学标志的可能性.方法:应用免疫组化技术对来自食管癌高发区的正常食管黏膜组织和轻度、中度、重度不典型增生上皮以及癌组织共203例组织中p63和Ki-67蛋白的异常表达进行研究.结果:在正常黏膜、轻度、中度、重度不典型增生及癌组织中,p63蛋白异常表达的阳性率分别为15.0%(3/20)、36.8%(14/38)、47.1%(24/51)、65.2%(30/46)和83.3%(40/48);Ki-67异常表达检出率分别为10.0%(2/20)、28.9%(11/38)、41.2%(21/51)、56.5%(26/46)和81.3%(39/48),等级相关分析结果显示,p63、Ki-67表达异常与组织学分级均显著相关(r分别为0.553和0.583,P<0.01),而且p63蛋白与Ki-67蛋白表达之间也具有相关性(r=0.690,P<0.01).结论:p63和Ki-67蛋白共表达与食管癌癌变过程显著相关,p63及Ki-67表达改变的时相分布,有可能成为在食管癌前人群中确立高危个体和选择重点化学预防个体的分子生物学标志.     

CDC2在食管鳞状细胞癌及癌前病变中的表达与临床意义

目的 探讨细胞周期调控蛋白CDC2在食管鳞状细胞癌及癌前病变中的表达及临床意义.方法 利用组织芯片技术和免疫组织化学方法,检测了241例食管鳞状细胞癌及癌前病变组织中CDC2表达水平,分析蛋白表达模式与临床病理参数的相关性.结果 在正常食管黏膜鳞状上皮-低级别上皮内瘤变-高级别上皮内瘤变-浸润性癌序列病变中,CDC2阳...     

Cytologic screening for esophageal cancer: Results from 12,877 subjects from a high-risk population in China

Linxian, China, has one of the highest esophageal-cancer mortality rates in the world. In 1983, esophageal balloon-cytology screening was performed to identify subjects eligible for 2 nutrition-intervention trials in Linxian; 12,877 subjects had cytology slides which were satisfactory for diagnosis. Of the 12,649 subjects with squamous-cell diagnoses, 31% were normal by Chinese cytologic criteria; 38% showed hyperplasia; 21% showed dysplasia 1; 6% showed dysplasia 2; 2% showed near-cancer; and 2% showed cancer. Of the 1,471 subjects with columnar-cell diagnoses, 31 % were normal; 44% showed hyperplasia; 16% showed dysplasia 1; 4% showed dysplasia 2; 2% showed near-cancer; and 3% showed cancer. Squamous dysplasia and cancer were more common among females than males, while columnar dysplasia and cancer showed male predominance. The prevalence of dysplasia and cancer of both cell types increased with age. The prevalence of squamous dysplasia was significantly higher than in earlier balloon-cytology screenings in Linxian, probably reflecting changes in cytologic classification.     

Overexpression of CDC25B overrides radiation-induced G2-M arrest and results in increased apoptosis in esophageal cancer cells

CDC25B phosphatase plays a key role in controlling G2-M progression by dephosphorylating two inhibitory residues of CDC2 and also has been suggested to have an oncogenic property. In this study, we investigated the effect of CDC25B overexpression on radiation-induced G2-M arrest and radiation sensitivity in esophageal cancer cells. TE8-CDC25B, in which CDC25B was overexpressed under an inducible system, was more radiosensitive than the vector control (TE8-neo) in a clonogenic survival assay. Without radiation, CDC25B overexpression had little effect on cell cycle fractions or growth rate. After 10-Gy radiation, TE8-CDC25B showed decreased G2-M arrest and increased apoptosis, whereas TE8-neo displayed prolonged G2-M arrest and less apoptosis. During this period, there were no differences in the protein amounts of CDC2 and cyclin B1 between the two cell lines. However, more CDC25B expression, which was reduced immediately by radiation, was sustained in TE8-CDC25B than in TE8-neo. Moreover, induction of tyrosine phosphorylation of CDC2 and reduction of CDC2 kinase activity after irradiation was less significant in TE8-CDC25B than in TE8-neo. These results indicate that cancer cells that overexpress CDC25B override G2-M arrest by retaining CDC2 kinase activity and undergo apoptosis after radiation. This may point to an effective approach toward improving radiotherapy outcomes of various cancers.     

Immunohistochemical analysis of cyclooxygenase-2 expression in premalignant and malignant esophageal glandular and squamous lesions in Cixian,China

Increased cyclooxygenase-2 (COX-2) expression has been observed in both squamous cell carcinoma (SCC) and adenocarcinoma (AC) in Western countries, and COX-2 inhibitors have been considered as potential chemopreventive agents for esophageal cancers. Since chemoprevention often targets the premalignant lesions in high-risk population, it is worthwhile to study COX-2 expression in a spectrum of premalignant and malignant lesions obtained from the high-risk populations. In this study, biopsy samples were taken from 240 subjects identified by screening of the high-risk population in Cixian, China, including 27 normal, 29 with squamous hyperplasia, 84 with dysplasia (31 low grade and 53 high grade), 30 with carcinoma in situ, and 70 with invasive carcinoma (60 SCC and 10 AC). For comparison, tissue samples were also collected from He Lon Jiang Province, a low-risk population in China, including 10 patients with invasive SCC, 20 patients with AC, and 17 patients with Barrett's esophagus. The COX-2 protein expression was examined by immunohistochemistry. Using 10% staining as a threshold, 9 of 10 (90%) invasive SCC from low-risk population were COX-2 positive. However, no positive COX-2 staining was seen on normal, hyperplastic, dysplastic, and in situ squamous lesions from the high-risk population, and only 4 of 60 (6%) invasive SCC exhibited positive COX-2 staining. For glandular lesions, 6 of 10 (60%) AC from high-risk area and 15 of 20 (75%) from low-risk area showed positive COX-2 staining, and 12 of 17 (70%) premalignant Barrett's esophagus were also positive. Our findings show that COX-2 expression various in squamous lesions from high- and low-risk areas, but not in glandular lesions. Additional studies are needed to fully explore the mechanisms that are associated with the different COX-2 immunohistochemical staining patterns in esophageal squamous lesions from low- and high-risk populations.     

食管癌发生发展过程中环氧合酶-2蛋白表达的研究

目的 研究环氧合酶－2（Cox-2)蛋白在食管癌及癌前病变组织中的表达,探讨非类固醇抗炎药在食管癌高危人群中化学预防的可能性。方法 应用免疫组织化学方法检测120例食管癌（原位癌30例,鳞状细胞癌60例,腺癌30例）及其113例增生性病变（单纯增生29例,轻、中、重度不典型增生分别为31例、30例、23例）和27例正常食管黏膜鳞状上皮,以及3例Barrett食管组织中Cox-2蛋白的表达情况。结果 在正常食管黏膜上皮,单纯增生,轻、中、重度不典型增生,原位癌未发现有Cox-2蛋白表达;在6％（4／60）侵袭性鳞状细胞癌和70％（21／30）的食管腺癌中,Cox-2蛋白表达阳性。结论 Cox-2蛋白表达可能与食管腺癌的形成有关,而与鳞状细胞癌的发生发展无关。     

食管鳞状细胞癌组织中核干细胞因子蛋白和mRNA的半定量表达

目的 探讨食管鳞状细胞癌组织中核干细胞因子(NS)蛋白和mRNA的半定量表达情况.方法 应用免疫组化SABC法和逆转录聚合酶链反应(RT-PCR)法,检测62例食管鳞状细胞癌组织及其相对应的31例癌旁不典型增生组织和62例正常食管黏膜组织中NS蛋白和mRNA的半定量表达情况.结果 正常食管黏膜组织、癌旁不典型增生组织和食管鳞状细胞癌组织中,NS蛋白阳性表达率分别为17.7%(11/62)、41.9%(13/31)和69.4%(43/62),组间比较,差异有统计学意义(χ2=33.676,P＜0.01).食管鳞状细胞癌组织中,NS蛋白阳性表达率与其组织学分级、侵袭程度及淋巴结转移密切相关(均为P＜0.05),而与年龄、性别和病理分型无关(均为P＞0.05).食管鳞状细胞癌组织中,NS mRNA的相对含量(0.971±0.121)高于癌旁不典型增生组织(0.913±0.085)和正常食管黏膜组织(0.866±0.103),组间比较,差异有统计学意义(F=14.829,P＜0.01).不同组织学分级、不同侵袭程度及有无淋巴结转移的食管鳞状细胞癌组织之间,NS mRNA的相对含量差异均有统计学意义(均为P＜0.05),NSmRNA的相对含量与年龄、性别和病理分型无关(均为P＞0.05).结论 食管鳞状细胞癌组织中,NS mRNA的表达升高,其高表达与食管鳞状细胞癌的发生发展有关.     

Esophageal squamous cell carcinomas arising in patients from a high-risk area of North China lack an association with Epstein-Barr virus.

The aim of this study was to determine whether EBV associates with esophageal squamous cell carcinoma (ESCC), the most common malignancy in some parts of northern China, because these tumors frequently have an intense lymphocyte infiltrate. Fifty-one paraffin-embedded samples of ESCC from a high-risk area of North China were studied. The tumors included 9 well-differentiated, 31 moderately differentiated, and 11 poorly differentiated tumors. The cancer tissues and their nonmalignant adjacent mucosa (16 dysplastic and 42 normal) were evaluated by in situ hybridization using an antisense EBV-encoded RNA-1 probe and PCR amplification for EBV BamHI W fragment. In all cases, EBV was negative by both in situ hybridization and PCR. Our study suggests that EBV does not play a role in the carcinogenesis of ESCC in the geographic region.     

Overexpression of Pim-1 in head and neck squamous cell carcinomas

Despite ongoing developments of treatment protocols head and neck squamous cell carcinomas (HNSCC) show only marginal improvement in outcome, which has been attributed to a lack of therapy individualized to tumor biological properties. We compared mRNA expression profiles of HNSCC and normal epithelial cells using differential display to identify gene fragments showing differential expression in HNSCC cells. We identified a 127-bp long fragment to be overexpressed in HNSCC cells that revealed a 98.4% homology with the Pim-1 mRNA. The differential expression was confirmed by Northern hybridization. Immunohistochemistry showed overexpression of the Pim-1 protein in 98% (41/42) of invasive HNSCC. Analysis of Pim-1 protein expression in relation to TNM stage and histological grade of the tumors exhibited no significant correlation. However, when samples of primary tumor and metastasis retrieved from the same patients (n=26) were analyzed, nearly significant correlation of Pim-1 expression with histological grade was found (p=0.06). The high frequency of the Pim-1 expression of HNSCC of different grades and stages in conjunction with its absence in non-neoplastic head and neck squamous cell epithelium underlines the functional role of Pim-1 in molecular processes of HNSCC.