Aberrant expression of beta-catenin, Pin1 and cylin D1 in salivary adenoid cystic carcinoma: relation to tumor proliferation and metastasis

The aims of this study were to investigate the expression levels of beta-catenin, Pin1 and cyclin D1 in salivary adenoid cystic carcinomas (SACC ) and to evaluate its clinical importance, furthermore, to elucidate whether beta-catenin expression was aberrant in SACC and whether Pin1 was involved in aberrant beta-catenin and cyclin D1 expression. The expression of Pin1, beta-catenin and cyclin D1 were examined in the specimens of 65 patients with SACC by immunohistochemistry, protein and mRNA expressions were detected by western blotting and RT-PCR in four SACC cell lines. Pin1 was overexpressed in 51 cases of SACC (78%), and high levels of Pin1 expression correlated with cyclin D1 positive expression (p = 0.02). Fourteen (22%) cases showed positive immunoreactivity for beta-catenin protein in the nuclear/cytoplasmic fraction in tumor tissues, which was defined as cytoplasm/nucleus staining, among which quite evident nuclear expression of beta-catenin was detected in six cases (9%), while cyclin D1 positive expression was detected in 41 cases of SACC (63%). Reduced membranous expression of beta-catenin was detected in the cases with metastasis (11/14). Theses results suggest that Pin1 and Wnt signalling pathway are activated in SACC and may play a pivotal role in SACC carcinogenesis and metastasis.     

Significance of E-cadherin/beta-catenin complex and cyclin D1 in breast cancer

E-cadherin and beta-catenin are important epithelial adhesion molecules in normal epithelium. Loss of E-cadherin - beta-catenin adhesion is an important step in the progression of many epithelial malignancies. beta-catenin plays also a role in intracellular signaling and can function as an oncogene when binds to the T-cell factor 4 (Tcf4)-binding site in the promotor region of cyclin D1 and transactivates genes after translocation to the nucleus. We evaluated the immunohistochemical expression pattern of E-cadherin, beta-catenin in relationship with cyclin D1 overexpression, tumor stage, clinicopathologic parameters and patient survival in 128 mammary infiltrating duct carcinomas. The expression of E-cadherin/beta-catenin complex and beta-catenin/cyclin D1 double staining with confocal scanning laser microscope was evaluated. There were aberrant expressions in 78% of E-cadherin, 79% of beta-catenin, and 66% of cyclin D1 in breast cancer. There was correlation of aberrant expression of E-cadherin or beta-catenin with lymph node metastasis, survival rate, and survival length. However, there was no correlation of cyclin D1 overexpression with aberrant expression of E-cadherin or beta-catenin. No death was found in normal expression of beta-catenin, however lowest survival (50%) was found in nuclear beta-catenin expression. There was correlation of overexpression of cyclin D1 with survival rate and survival length. The highest survival rate and survival length were found in membranous normal beta-catenin expression group, however significant decrement of survival length was found in the groups of aberrant expression one or both of E-cadherin or/and beta-catenin. These results suggest that aberrant expression of E-cadherin, beta-catenin, and cyclin D1 may be involved in tumor metastasis, and analysis of the degree or the pattern of E-cadherin, beta-catenin, cyclin D1, and E-cadherin/beta-catenin complex may be good prognostic markers of mammary infiltrating duct carcinoma.     

Molecular alterations associated with cyclin D1 overexpression in endometrial cancer

Cyclin D1 is frequently overexpressed in human neoplasias by gene rearrangement and amplification. In addition, Ras, PTEN and beta-catenin appear to modulate cyclin D1 levels. Since the causes of cyclin D1 overexpression are poorly understood in EC, we investigated whether or not this alteration is due to cyclin D1 gene amplification or to RAS, PTEN and beta-catenin mutation. We analyzed cyclin D1 expression in 18 AEHs, 65 EECs and 27 NEECs by immunohistochemistry as well as CCND1 gene amplification by FISH. In EECs, mutations in K-RAS, PTEN, beta-catenin and CCND1 were studied by PCR-SSCP and sequencing and MSI was evaluated by analyzing BAT-25 and BAT-26 microsatellites. Contingency tests were used to evaluate the relationships between variables. Cyclin D1 overexpression was not observed in AEHs but was present in 13.8% of EECs and 11.2% of NEECs (p = 0.031). CCND1 amplification was more frequent in NEECs (26.3%) than in EECs (2.1%) (p = 0.002). In EECs, cyclin D1 overexpression was not associated with mutations in K-RAS, PTEN or beta-catenin. However, in EECs with beta-catenin mutations, cyclin D1 was expressed mainly by cells expressing beta-catenin in the cytoplasm and nucleus but not in those with membranous expression. Finally, cyclin D1 overexpression was associated with MSI (p = 0.047). The molecular alterations associated with cyclin D1 overexpression differ in the 2 clinicopathologic types of EC. Cyclin D1 overexpression is associated with gene amplification in NEECs and with nucleocytoplasmic expression of beta-catenin and MSI in EECs.     

Frequent beta-catenin alteration in gallbladder carcinomas

To investigate the contribution of beta-catenin to the development of gallbladder carcinoma, genetic alteration in beta-catenin gene, ctnnb-1 and subcellular localization of beta-catenin protein were searched. Mutational analysis of exon 3 in ctnnb-1, which encodes the serine/threonine residues for GSK3beta phosphorylation sites, was performed for 21 gallbladder carcinomas affected with/without the pancreaticobiliary malunion, PBM, and 6 non-cancerous tissues affected with PBM. We also analyzed subcellular localization of beta-catenin protein in all cases immunohistochemically. Nucleotide sequencing analysis revealed that none of them carried mutations that altered amino acid residues in the potential GSK3beta phophorylation sites, but one nucleotide substitution was found. We also analyzed subcellular localization of beta-catenin protein in all cases immunohistochemically, and confirmed its accumulation in both the nucleus and cytoplasm in 10 out of 21 cancer tissues, while the non-cancerous tissues which were affected with PBM and histologically diagnosed as hyperplasia or dysplasia displayed intense membranous staining. A significant correlation between cytoplasmic or nuclear beta-catenin immunoreactivity and clinicopathological status of gallbladder carcinomas was found, especially in the poorer histological differentiation grade(p < 0.05). In conclusion our results suggested that beta-catenin alteration might be a minor contributor to the development of gallbladder carcinomas through abnormal Wnt-wingless signalling, however, decreased membranous expression of beta-catenin might be correlated to carcinoma progression through loss of cell adhesive function in E-cadherin-catenin fashion.     

乳腺癌组织中E-cadherin、β-catenin及cyclin D1表达的相关性研究

背景与目的上皮性钙粘素(E-cadherin)通过连接素(catenins)与细胞骨架相连介导细胞同质粘附反应,β-catenin除与E-cadherin结合介导细胞粘附反应外,还作为Wnt信号转导通路的重要成分与肿瘤发生密切相关。本研究通过检测乳腺癌组织中E-cadherin、β-catenin及cyclinD1的表达,探讨E-cadherin、β-catenin在乳腺癌发生、发展中的意义。方法采用免疫组织化学SP法检测60例乳腺癌组织中E-cadherin、β-catenin、cyclinD1的表达。结果乳腺癌组织中有29例(48.3%)E-cadherin、18例(30.0%)β-catenin正常表达,28例(46.7%)cyclinD1过度表达。E-cadherin正常表达病例中,31.0%(9/29)的病例呈现cyclinD1过度表达,而E-cadherin异常表达病例中,61.3%(19/31)的病例呈现cyclinD1过度表达,E-cadherin异常表达与cyclinD1的过度表达有显著的正相关性(rs=0.303,P<0.05)。有42例癌组织表现出β-catenin的异常表达,其中57.1%(24/42)的病例出现cyclinD1的过度表达,而β-catenin正常膜表达病例中,22.2%(4/18)的病例呈现cyclinD1的过度表达。β-catenin的异常表达与cyclinD1的过度表达有显著的正相关性(rs=0.321,P<0.05)。结论E-cadherin和β-catenin的异常表达可能通过促使或激活cyclinD1的过度表达导致乳腺癌的发生和发展。     

A survival-stratification model of human colorectal carcinomas with beta-catenin and p27kip1

BACKGROUND: The stabilization and nuclear translocation of beta-catenin are early events in the majority of sporadic colorectal carcinomas (CRC). beta-catenin up-regulates c-Myc and cyclin D1, which antagonize the association of the cyclin-dependent kinase (Cdk) inhibitor, p27(kip1), with Cdk2, thus allowing cell cycle progression through G1 to S-phase. Lack of p27 is a significant predictor of poor survival in a series of 136 CRC specimens. A combination of molecules in the same pathway may be a better prognostic factor. METHODS: The expression of beta-catenin, c-Myc, and cyclin D1 in relation to patients' survival and clinicopathologic parameters in the same series was evaluated by immunohistochemistry. RESULTS: Intense nuclear overexpression of beta-catenin, but not a lack of cell membrane or cytoplasmic expression, is a significant predictor of poor survival by both univariate (P = 0.0029) and multivariate analyses (P = 0.004, risk ratio =3.8), suggesting that beta-catenin is retained in the nucleus to function as an oncogene. None of the patients with high nuclear beta-catenin and low p27 expression survived 5 years or more whereas 65% of patients with all other combinations of the two markers survived (P < 0.0001). This combination is also a significant and independent prognostic factor (P = 0.001; risk ratio = 9.7). Overexpression of c-Myc is associated with higher mortality rates, but the expression of cyclin D1 has no prognostic significance. CONCLUSIONS: The combined expression of beta-catenin and p27 can stratify patients into markedly different survival groups, possibly via their antagonistic effects on metastasis promotion.     

Cyclooxygenase 2 expression and molecular alterations in Peutz-Jeghers hamartomas and carcinomas

PURPOSE: Peutz-Jeghers syndrome (PJS) is a hamartomatous polyposis disorder with a high cancer risk. Debate exists about the premalignant potential of hamartomas. Also, treatment options other than surveillance are not available. Therefore, molecular alterations in hamartomas and PJS carcinomas were studied. The objective was (a) to evaluate expression of cyclooxygenase (COX)-2 as target for chemopreventive treatment and (b) to define the neoplastic potential of hamartomas at the molecular level. Experimental Design: Paraffin-embedded samples of 24 PJS hamartomas, including 2 hamartomas with dysplastic changes, and 11 PJS carcinomas were available. Slides were stained with antibodies against COX-2, beta-catenin, cyclin D1, p21(waf1/cip1), Ki-67, and p53. DNA was studied for loss of heterozygosity (LOH) at 19p (STK11), 5q (APC), and 17p (TP53); mutations in beta-catenin, APC, and K-RAS; and microsatellite instability. RESULTS: Moderate or strong epithelial COX-2 was present in 25% of hamartomas, including two hamartomas with dysplastic changes, and 64% of carcinomas. Several hamartomas showed focal nuclear beta-catenin (18%) and cyclin D1 overexpression (29%), both unrelated to dysplasia at histological examination. Disturbed topographical expression of Ki-67 in relation to p21(waf1/cip1) was focally present in 27% of hamartomas, including those with dysplastic changes. Most carcinomas showed nuclear beta-catenin (71%), cyclin D1 overexpression (71%), and aberrant Ki-67 staining (100%). There was LOH at 19p in 32% of hamartomas and 82% of carcinomas. p53 staining was present in four (36%) carcinomas, one of which showed LOH at 17p. No beta-catenin mutations were found. APC mutations were present in two carcinomas, but LOH at 5q was not found. Two carcinomas had K-RAS mutations, and one carcinoma had microsatellite instability. CONCLUSIONS: The presence of COX-2 expression in PJS carcinomas and dysplastic hamartomas provides a rationale for chemoprevention with nonsteroidal anti-inflammatory drugs or COX-2 inhibitors. Focal immunohistochemical changes, which may indicate a premalignant potential, were present in some nondysplastic PJS hamartomas. Molecular changes in carcinomas and dysplastic hamartomas in PJS are distinct from the usual adenoma-carcinoma sequence.     

beta-catenin expression in primary and metastatic colorectal carcinoma.

beta-catenin plays a fundamental role in the regulation of the E-cadherin-catenin cell adhesion complex. It also functions in growth signalling events, independently of the cadherin-catenin complex, and these signalling pathways are disturbed in colorectal cancer. Mutations in either the APC or beta-catenin genes in colorectal cancer cells result in up-regulation of protein expression and subsequent cytoplasmic and nuclear distribution of beta-catenin. In this study, we examined beta-catenin expression in 47 primary colorectal tumors and the corresponding liver metastases. Immunohistochemical studies demonstrated loss of membranous beta-catenin expression in 26% of primary tumors and 60% of liver metastases and a concomitant increase in cytoplasmic and nuclear staining. Widespread nuclear expression of beta-catenin was found in 64% of primary tumors and 21% of liver metastases. No associations were found between any form of beta-catenin expression and either tumor stage or tumor grade. Cellular distribution of beta-catenin was also examined by detergent extraction and Western blot analysis in 16 primary tumors and 23 liver metastases. This analysis showed that most tumors demonstrated reduced beta-catenin in the cytoskeletal fraction and increased beta-catenin in the cytosolic fraction. Furthermore, 3 liver metastases were found to contain a truncated beta-catenin protein of approximately M(r) 80,000. Immunoprecipitation studies showed that the truncated beta-catenin proteins only bound weakly to E-cadherin and beta-catenin compared with non-truncated beta-catenin. These results demonstrate gross alterations in the cellular distribution of beta-catenin in primary colorectal cancers with metastatic potential, as well as in the metastatic tumors. These changes may be the consequence of APC or beta-catenin gene mutations, or possibly result from a post-translational modification of the E-cadherin-catenin complex.     

Secreted Frizzled-related Protein 2 (SFRP2) is Highly Expressed in Canine Mammary Gland Tumors but not in Normal Mammary Glands

Canine mammary gland tumor (MGT) is the commonest tumor in female dogs and a good animal model of human breast cancer. A group of newly identified genes encoding secreted frizzled-related proteins (SFRP) have been implicated in apoptosis regulation and tumorigenesis. Canine mammary tissues from 50 spontaneous MGTs and 10 normal mammary glands (MGs) were obtained from surgically excised specimens and analyzed for expression of SFRP2, beta-catenin, and cyclin D1. By RT-PCR and in situ hybridization, SFRP2 gene was found abundantly expressed in neoplastic mammary tissues but not in normal mammary tissues, suggesting that SFRP2 may contribute as a tumor marker in canine MGTs. By immunohistochemical staining, the immunoreactivity of the SFRP2 protein was detected in more diverse areas than SFRP2 mRNA expression, including nuclei or/and cytoplasm and extracellular matrix of the tumor. In tumor masses, beta-catenin lost its tight association with the membrane and diffused into the nucleus. The expression of beta-catenin (79.4% positive) and cyclin D1 (71.4% positive) was also increased in MGTs. In the course of tumor progression, SFRP2 mRNA ( p < 0.05) and beta-catenin protein ( p < 0.01) steadily increased but not in cyclin D1. The level of SFRP2 was linearly correlated with its downstream target beta-catenin ( p < 0.05), but not correlated with cyclin D1 ( p < 0.5). As revealed in this study, the exclusive overexpression of SFRP2 in canine MGTs suggests that SFRP2 is a potential candidate gene for further investigation of mammary tumorigenesis and complex etiology of the canine model of mammary neoplasms.     

Beta-catenin and cyclin D1 expression in human hepatocellular carcinoma

To understand the nature and roles of mutated beta-catenin in human hepatocellular carcinomas (HCCs), 57 cases of surgically resected HCCs were studied. DNAs extracted from each tumor were examined for somatic mutations of exon 3, and the protein expressions of beta-catenin, cyclin D1, and Ki-67 were observed by immunohistochemical staining. beta-catenin mutations in exon 3 were detected in 10 (17.5%) out of 57 HCCs, including nine missense mutations and one deletion mutation. All of the cases with gene alterations had the anti-HCV antibody, and tested negative for the HBs antigen in the sera. All of the mutations occurred at the serine/threonine phosphorylation sites of glycogen synthase kinase-3beta (GSK-3beta) or their neighboring residues. Significant correlation with intracellular expression (p=0.00055) was shown in the HCCs harboring beta-catenin mutations. The intracellular accumulation of beta-catenin showed significant correlation with the cyclin D1 expression (p=0.00858), and with a higher proliferation index (p=0.00072). In addition, the beta-catenin mutations showed significant association with the cyclin D1 expression (p=0.0424). These results suggest that accumulated beta-catenin proteins may bind to the lymphocyte enhancer binding factor-1 (LEF-1), form the beta-catenin/LEF-1 complex, and stimulate such promoters regulating the cell cycle as the cyclin D1 gene. This is the first report to demonstrate a significant correlation between beta-catenin and the cyclin D1 expression in human HCCs.     

Immunohistochemical patterns in rectal cancer: application of tissue microarray with prognostic correlations

We utilized the high-throughput tissue microarray method to characterize immunohistochemical expression patterns with correlations to prognosis in rectal cancer. Immunostaining for the markers Ki-67, Bcl-2, p53, EGFR, E-cadherin, beta-catenin, MLH1 and MSH2 was performed in 269 rectal cancers. Expression profiles were correlated to metastasis-free survival. Immunostaining revealed frequent upregulation and/or aberrant staining patterns for several of the markers, but Ki-67, p53, Bcl-2 and EGFR did not show any correlation to prognosis. However, reduced membranous staining for beta-catenin (p = 0.04), lack of cytoplasmic staining for beta-catenin (p = 0.04), reduced membranous staining for E-cadherin (p = 0.02) and lack of cytoplasmic staining for E-cadherin (p = 0.02) correlated with metastatic disease. Multivariate analysis including the factors Dukes' stage and tumor differentiation grade demonstrated increased risk of metastatic disease in tumors with lack of cytoplasmic staining for beta-catenin (HR = 3.1, p = 0.02), reduced membranous staining for beta-catenin (HR = 1.7, p = 0.06) and reduced membranous staining for E-cadherin (HR = 2.1, p = 0.06). Loss of MMR protein expression was confirmed to be a rare event in rectal cancer with loss of MLH1 staining in 3% and MSH2 in 1% of the tumors. The lack of prognostic information contributed by most of these markers suggests that single markers for prognosis may be of limited value in rectal cancer. However, altered expression of beta-catenin and E-cadherin correlated with metastatic disease, and these markers may have prognostic importance in rectal cancer.     

Beta-catenin expression is altered in human colonic aberrant crypt foci.

The aberrant expression of beta-catenin in colon tumors and the discovery of beta-catenin mutations in small adenomas suggest that alterations of beta-catenin are early events in human colorectal carcinogenesis. Here, we describe the expression of beta-catenin in human aberrant crypt foci (ACF), the earliest identified neoplastic lesions in the colon. Paraffin-embedded sections of 94 ACF, 12 adenomas, and 10 carcinomas were evaluated for beta-catenin expression by immunohistochemistry. Normal colonic epithelial cells adjacent to these lesions showed strong membranous expression of beta-catenin and lacked cytoplasmic and nuclear expression. Cytoplasmic expression of beta-catenin was seen in 25 of 46 ACF with dysplasia and in 2 of 48 ACF with atypia. In ACF with dysplasia, reduced membranous expression of beta-catenin was associated with increased nuclear (P = 0.0013) and cytoplasmic (P = 0.0247) expression. The membranous (P = 0.0003) expression of beta-catenin was reduced, and the cytoplasmic (P = 0.0016) and nuclear (P = 0.0266) expressions increased in ACF according to their degree of dysplasia. Likewise, membranous (P = 0.0007) expression of beta-catenin was reduced, and the cytoplasmic (P = 0.0050) and nuclear (P = 0.0001) expressions increased from ACF to adenoma to carcinoma. These data suggest that ACF and their aberrant expression of beta-catenin play a role in colon tumorigenesis.     

Expression of the E-cadherin-catenin cell adhesion complex in primary squamous cell carcinomas of the head and neck and their nodal metastases.

Reductions in cell-cell adhesion and stromal and vascular invasion are essential steps in the progression from localized malignancy to metastatic disease. In this study, changes in the expression of the components of the E-cadherin-catenin cell adhesion complex have been investigated using immunohistochemical techniques in primary tumours and nodal metastases from 36 patients with squamous cell carcinoma of the head and neck. For 14 patients the corresponding primary and nodal metastases samples were available. None of the 51 samples showed normal E-cadherin expression when compared with either the adjacent normal squamous epithelium or with normal colonic epithelium that was used as positive control material. In 88% of primary tumours fewer than 50% of cells exhibited normal membranous E-cadherin expression. Loss of membranous E-cadherin expression was more extensive in poorly differentiated carcinomas while, in individual carcinomas, membranous E-cadherin expression was stronger in those parts of the neoplasm that expressed the differentiation marker involucrin. Expression of beta-catenin generally paralleled that of E-cadherin, but in 12 cases there was strong membranous beta-catenin expression in samples that exhibited predominantly cytoplasmic E-cadherin labelling. Expression of alpha-catenin was generally weak and did not correlate with the expression of either beta-catenin or E-cadherin. Marked intratumoral heterogeneity for protein expression was evident for all antibodies, and the abnormal expression of the catenins is a novel finding. E-cadherin is expressed more intensely in cells with greater squamous differentiation, but there was no correlation between the decreased expression of any of the adhesion molecules of the E-cadherin complex tested and local recurrence, metastasis or survival. The loss of expression of components of the E-cadherin complex is a common abnormality in squamous carcinomas and, while it may be permissive for metastasis, it does not appear to be the only determinant of this process.     

PIN1 overexpression and beta-catenin gene mutations are distinct oncogenic events in human hepatocellular carcinoma

The peptidyl-proplyl-isomerase, PIN1, upregulates beta-catenin by inhibiting its interaction with APC. beta-catenin accumulation occurs in about 70% of hepatocellular carcinoma (HCC), of which only 20% are due to beta-catenin mutations. The role of PIN1 in beta-catenin upregulation in HCC was investigated. PIN1 was shown to be overexpressed in more than 50% of HCC. All cases with PIN1 overexpression also showed beta-catenin accumulation, with 68% of cases showing concomitant beta-catenin and cyclin D1 accumulation. PIN1 was shown to contribute to beta-catenin and cyclin D1 overexpression directly by in vitro cell-line transfection experiments. Finally, we showed that PIN1 overexpression and beta-catenin gene mutations appeared to be mutually exclusive events, leading to beta-catenin accumulation in HCC. These results showed that PIN1 overexpression leading to beta-catenin accumulation might be a critical event in hepatocarcinogenesis, and that PIN1 is a potential target for therapeutic intervention in HCC.     

Overexpression of p21(WAF1/CIP1) is an early event in the development of pancreatic intraepithelial neoplasia.

Pancreatic cancer (PC) is thought to develop through a series of duct lesions termed pancreatic intraepithelial neoplasia (PanIN). Characterization of the molecular pathology of these lesions may lead to additional understanding of pancreatic ductal carcinogenesis. We examined the protein expression of four functionally related genes, p21(WAF1/CIP1) (CDKN1A), p53, cyclin D1 (CCND1), and DPC4/Smad4 (MADH4), aberrations of which are associated with PC, within 451 PanIN lesions present in the pancreata of 60 patients. p21(WAF1/CIP1) overexpression was present in the normal ducts of 9% of patients and increased progressively to 16% of patients with PanIN-1A lesions, to 32% of patients with PanIN-1B lesions, 56% of patients with PanIN-2 lesions, 80% of patients with PanIN-3 lesions, and 85% of patients with invasive carcinomas (P < 0.01). p53 and cyclin D1 overexpression occurred predominantly in PanIN-3 lesions (P < 0.01), and loss of DPC4/Smad4 expression occurred predominantly in PanIN-3 lesions and invasive carcinoma (P < 0.01). In addition, p21(WAF1/CIP1) overexpression occurred independently of p53 and DPC4/Smad4 expression within invasive carcinoma and PanIN-3 lesions. Cyclin D1 overexpression or loss of DPC4/Smad4 expression was apparent in 85% of invasive carcinomas but in only 14% of PanIN-2 lesions. These data demonstrate that overexpression of p21(WAF1/CIP1) occurs early in the development of PanIN, before aberrations in p53, cyclin D1, and DPC4/Smad4 expression. p21(WAF1/CIP1) overexpression, independent of p53 and/or DPC4/Smad4 expression, may reflect increased Ras activity, either directly through activating K-ras mutations or as a consequence of HER-2/neu (ERBB2) overexpression, both of which are common in PC and in early events in the development of PanIN. These data support further the current progression model for PC and demonstrate that aberrant expression of key cell cycle regulatory genes may be important in the early development and progression of PanIN.     

β-连接素在胃癌的表达及其与患者生存的关系

背景与目的:细胞粘附功能下降是恶性肿瘤发展的关键因素。作为粘附分子的E-钙粘蛋白在维持正常组织结构方面具有非常重要的作用,但其功能的发挥,需要配体-连接素(α-、β-连接素等)的调节。为探讨β-连接素在胃癌发病机制中的作用,我们研究β-连接素在胃癌的表达情况,并分析其与临床病理特征及生存期的关系。方法:采用免疫组织化学法检测148例胃癌石蜡标本β-连接素和E-钙粘蛋白的表达水平。结果:胃癌组织β-连接素和E-钙粘蛋白的异常表达率分别为43.2%和44.6%;胃癌β-连接素和E-钙粘蛋白其中一种或二种表达异常者达63%。β-连接素和E-钙粘蛋白在低分化癌的异常表达率显著高于高分化癌(均P<0.005)。β-连接素表达异常与胃癌浸润深度密切相关(P<0.025);淋巴结转移阳性(45/84,53.6%)及发生远处转移(21/31,67.7%)的β-连接素异常表达率显著高于淋巴结转移阴性(19/64,29.7%)(P<0.005)及无远处转移者(43/117,36.8%)(P<0.005)。β-连接素正常表达比异常表达具有生存优势(P<0.005),且独立于浸润深度、淋巴结转移及分化程度。结论:胃癌广泛存在E-钙粘蛋白复合体表达异常;β-连接素异常表达是对胃癌生存期具有预测价值的重要指标。     

Overexpression of G1-S cyclins and cyclin-dependent kinases during multistage human pancreatic duct cell carcinogenesis.

PURPOSE: Molecular analysis of pancreatic intraepithelial neoplasia lesions and ductal adenocarcinoma suggested a multistage paradigm for pancreatic duct cell carcinogenesis. This study investigated the molecular basis for the neoplastic duct cells in this pancreatic intraepithelial neoplasia-carcinoma sequence to acquire progressive enhancement of their proliferative potential. EXPERIMENTAL DESIGN: Using tissue microarray blocks containing 15 to 40 pancreatic intraepithelial neoplasia lesions and ductal adenocarcinoma of pancreas, we studied by immunohistochemistry the expression profiles of cyclins and cyclin dependent kinases (CDKs) that regulate the G1-S cell cycle checkpoints. The role of cyclins D3 and D1 in three pancreatic cancer cell lines was investigated using specific short interfering RNA technique. RESULTS: Cyclin D3 overexpression was noted the earliest in pancreatic intraepithelial neoplasia-1A and was prevalent in 90% to 100% of high-grade pancreatic intraepithelial neoplasias and ductal cancer. Cyclin A overexpression was also noted early and reached 50% to 100% of high-grade pancreatic intraepithelial neoplasias and cancer, but the percentage of abnormal duct cells showing overexpression of cyclin A was significantly lower than cyclin D3. Cyclin E overexpression occurred in 20% to 25% of high-grade pancreatic intraepithelial neoplasias and in 75% of ductal carcinoma. Cyclin D1 demonstrated the lowest frequency of overexpression that occurred late. CDK2 and CDK4 overexpression was also noted in early pancreatic intraepithelial neoplasias and progressively increased to reach 60% to 75% in carcinoma. The down-regulation of cyclin D3 mRNA and protein levels using specific short interfering RNA resulted in growth inhibition of pancreatic cancer cell lines. CONCLUSION: The results provide additional insight into the mechanism of G1-S cell cycle checkpoints deregulation during stepwise pancreatic duct cell carcinogenesis, and suggest a p16-independent role for cyclin D3 in deregulating the G1 cell cycle checkpoints during early stages of pancreatic duct cell carcinogenesis.