The influence of matriptase-2 on prostate cancer in vitro: A possible role for β-catenin

The type II transmembrane serine proteases (TTSPs) are a family of cell surface proteolytic enzymes contributing to a number of processes, such as tumour invasion and metastasis. Within the TTSPs, matriptase-2 is a relatively newly identified member and this protease has been shown to play a key role in cancer progression. β-catenin has long been regarded as an oncogene. The deregulation of the β-catenin signalling pathway plays a significant role in the progression and possibly the development of cancer. However, little is known about the role of matriptase-2 in prostate cancer. This study aimed to examine the correlation between matriptase-2 and β-catenin. Matriptase-2 was knocked down in the normal prostate cells, PZHPV7 and PNT2C2, using a ribozyme transgene targeting matriptase-2. The altered cells were used in a number of in?vitro experiments designed to investigate the involvement of matriptase-2 with β-catenin and to further characterise its function. The knockdown of matriptase-2 had no effect on cell growth or adhesion but significantly reduced cell motility (PZHPV7 cells, p<0.001; PNT2C2 cells, p=0.001 vs. respective control cells) and invasive capability (PZHPV7 cells, p=0.001; PNT2C2 cells, p=0.007). The knockdown also caused a large increase in β-catenin protein expression at the cell membrane in PZHPV7 and PNT2C2 cells and a decrease in PC3 cells overexpressing matriptase-2, but did not affect the mRNA levels. Matriptase-2 may have an important impact on prostate cancer progression. The data gained from this study suggest that matriptase-2 protects against the development and progression of prostate cancer by regulating the motility and invasive capabilities of prostate cancer cells. Matriptase-2 also reduces the levels of β-catenin at the cell membrane. As β-catenin is highly involved in the regulation of cellular processes, including motility and invasion, the reduction of β-catenin expression by matriptase-2 may be a possible mechanism by which matriptase-2 functions.     

Genetic reduction of matriptase-1 expression is associated with a reduction in the aggressive phenotype of prostate cancer cells in vitro and in vivo

PURPOSE: Matriptase-1 has been implicated as playing an important role in various types of cancer progression through many different cancer related pathways. In the current study we assessed the efficacy of targeting matriptase-1 using ribozyme technology in vitro and in vivo. EXPERIMENTAL DESIGN: Matriptase-1 expression was reduced in the PC-3 and DU-145 cell line using hammerhead ribozyme transgenes. In vitro assays were set up to assess changes in growth, invasion, adhesion and migration in these cells. In vivo tumour development model was also used to examine the efficacy of targeting matriptase-1 in a living environment. RESULTS: The in vitro results suggest an overall reduction in the aggressive nature of the two cell lines (PC-3 and DU-145) when matriptase-1 levels are reduced, with properties such as growth, invasiveness and migration all being reduced (in most cases a greater than 50% reduction in migration and invasion compared to the control was observed), though strangely an increase in adhesion is seen in the PC-3 knockout. The in vitro data is strongly backed up by the results of the in vivo work which demonstrates matriptase-1 deficient cells have a substantially reduced ability to grow and develop in vivo compared to control cells when explanted into nude mice, with significant differences in growth and development (P < or = 0.05) being seen after 7 days, and highly significant differences (p < or = 0.001) after 15 days. CONCLUSIONS: Together this data strongly implicates matriptase-1 as playing a vital role in the aggressive nature and progression of prostate cancer.     

Loss of Nrdp1 enhances ErbB2/ErbB3-dependent breast tumor cell growth

Dysregulation of ErbB receptor tyrosine kinases is thought to promote mammary tumor progression by stimulating tumor cell growth and invasion. Overexpression and aberrant activation of ErbB2/HER2 confer aggressive and malignant characteristics to breast cancer cells, and patients displaying ErbB2-amplified breast cancer face a worsened prognosis. Recent studies have established that ErbB2 and ErbB3 are commonly co-overexpressed in breast tumor cell lines and in patient samples. ErbB2 heterodimerizes with and activates the ErbB3 receptor, and the two receptors synergize in promoting growth factor-induced cell proliferation, transformation, and invasiveness. Our previous studies have shown that the neuregulin receptor degradation protein-1 (Nrdp1) E3 ubiquitin ligase specifically suppresses cellular ErbB3 levels by marking the receptor for proteolytic degradation. Here, we show that overexpression of Nrdp1 in human breast cancer cells results in the suppression of ErbB3 levels, accompanied by the inhibition of cell growth and motility and the attenuation of signal transduction pathways. In contrast, either Nrdp1 knockdown or the overexpression of a dominant-negative form enhances ErbB3 levels and cellular proliferation. Additionally, Nrdp1 expression levels inversely correlate with ErbB3 levels in primary human breast cancer tissue and in a mouse model of ErbB2 mammary tumorigenesis. Our observations suggest that Nrdp1-mediated ErbB3 degradation suppresses cellular growth and motility, and that Nrdp1 loss in breast tumors may promote tumor progression by augmenting ErbB2/ErbB3 signaling.     

Her-2/neu and urokinase-type plasminogen activator and its inhibitor in breast cancer.

PURPOSE: Recent studies suggest that HER-2/neu specifically promotes the invasive capacity of tumor cells by up-regulating secretion of the proteolytic enzyme, urokinase-type plasminogen activator (uPA), or its inhibitor, plasminogen activator inhibitor-1 (PAI-1), in colon and gastric cancer. It was the purpose of this study to: (a) evaluate the association between HER-2/neu and uPA and PAI-1 expression in a large primary breast cancer cohort; (b) perform the first multivariate analysis, including HER-2/neu, uPA, and PAI-1 in breast cancer; and (c) define the effect of HER-2/neu overexpression on uPA and PAI-1 expression in breast cancer cells. EXPERIMENTAL DESIGN: HER-2/neu, uPA, and PAI-1 were measured as continuous variables by ELISA in primary breast cancer tissue extracts from 587 patients with clinical follow-up and analyzed for correlations with clinical outcome. Furthermore, a full-length human HER-2/neu cDNA was introduced into five human breast cancer cell lines to define the effects of HER-2/neu overexpression on uPA and PAI-1 expression. In addition, we tested whether HER-2/neu antibodies could reverse any given alteration of uPA and PAI-1 levels. RESULTS: Our findings indicate a weak positive association between HER-2/neu and uPA (r = 0.147; P < 0.001) and no association between HER-2/neu and PAI-1 (r = 0.07; P = 0.085). HER-2/neu overexpression (> or =400 fmol/mg) and high levels of uPA/PAI-1 (> or =5.5 ng/mg and/or > or =14 ng/mg, respectively) were significantly associated with shorter disease-free survival (DFS; P < 0.001 and P = 0.003) and metastasis-free survival (MFS; P = 0.015 and P < 0.001). Multivariate analysis revealed prognostic independence between HER-2/neu and the uPA/PAI-1 axis for DFS and MFS. Both uPA and PAI-1 had no significant discriminatory effect among HER-2/neu-positive patients for DFS. The prognostic value of HER-2/neu overexpression for MFS, however, was significantly enhanced by elevated uPA expression (P = 0.053). Stable transfection of the HER-2/neu gene into multiple human breast cancer cell lines resulted in consistent down-regulation of uPA or PAI-1 expression. In addition, anti-HER-2/neu antibodies did not significantly affect uPA or PAI-1 expression in human cancer cell lines naturally overexpressing HER-2/neu. CONCLUSIONS: The present findings suggest that the invasive phenotype elicited by HER-2/neu overexpression in breast cancer is not a direct effect of uPA or PAI-1 expression. HER-2/neu and the uPA/PAI-1 axis have been shown to affect the invasive capacity of breast cancer independently. Determination of uPA can provide significant additional prognostic information for MFS in HER-2/neu-positive and -negative patients.     

TAGLN基因过表达对乳腺癌细胞迁移和侵袭能力的影响

目的 研究TAGLN基因过表达对人乳腺癌细胞MDA-MB-231迁移能力和侵袭能力的影响及其分子机制.方法 对MDA-MB-231细胞采用慢病毒表达系统构建TAGLN基因稳定过表达细胞株,将MDA-MB-231细胞正常培养设为空白对照组,空载体慢病毒包装感染MDA-MB-231细胞后获得的稳定转染细胞株设为空载体对照组.Real time PCR和Western blot检测TAGLN mRNA和蛋白表达,划痕实验和Transwell侵袭实验检测细胞迁移和侵袭能力,Western blot检测TAGLN基因过表达后基质金属蛋白酶2(matrix metalloproteinase-2,MMP-2)和MMP-9蛋白表达变化.结果 MDA-MB-231细胞感染TAGLN基因过表达慢病毒载体后,细胞中TAGLN mRNA表达和蛋白表达升高(均P＜0.01),成功构建TAGLN基因过表达稳定细胞株(231-TAGLN).231-TAGLN细胞的体外迁移能力和侵袭能力下降,与空载体对照组和空白对照组细胞比较,差异均具有统计学意义(均P＜0.01),同时伴有MMP-2和MMP-9表达水平降低(均P＜0.01).结论 TAGLN基因过表达可以抑制乳腺癌细胞的迁移和侵袭,MMP-2和MMP-9基因表达下降可能参与这一过程.     

Cullin1 is a novel marker of poor prognosis and a potential therapeutic target in human breast cancer

BackgroundTo investigate the role of Cullin1 (Cul1) in the development of breast cancer, we examined the expression of Cul1 in breast cancer tissues and analyzed the correlation between Cul1 expression and clinicopathologic variables and patients survival.Patients and methodsWe evaluated the Cul1 expression by immunohistochemistry using a tissue microarray (TMA) which includes 393 breast cancer tissues. We also studied the role of Cul1 in breast cancer cell proliferation, migration and invasion by carrying out CCK8 cell proliferation assay, cell migration and invasion assay.ResultsThe Cul1 expression was significantly correlated with breast cancer histology grade (P = 0.000), estrogen receptor status (P = 0.001), progesterone receptor status (P = 0.001) and human epidermal growth factor receptor 2 status (P = 0.002). Furthermore, we showed a strong correlation between high Cul1 expression and worse 5-year overall and disease-specific survival rates in breast cancer patients (P = 0.026 and P = 0.015, respectively). Finally, we found that Cul1 knockdown inhibits cell proliferation, migration and invasion abilities.ConclusionsCul1 overexpression is significantly correlated with breast cancer progression and predicts worse survival. Cul1 regulates breast cancer cell proliferation, migration and invasion.     

Expression of survivin and E-cadherin in breast cancer

Survivin is a member of the inhibitor of apoptosis (IAP) family, and is involved in the regulation of cell division. Survivin expression is related with poor survival of patients with tumors including neuroblastoma, non-small-cell lung cancer, breast carcinoma, gastric carcinoma, rectal cancer, recurrent ????????????colorectal carcinoma and bladder cancer. It is thought to be an important prognostic marker in cancers[1,2]. E-cadherin functionally belongs to transmembrane glycoproteins family,…     

A PAK5–DNPEP–USP4 axis dictates breast cancer growth and metastasis

Although clinically associated with the progression of multiple cancers, the biological function of p21-activated kinase 5 (PAK5) in breast cancer remains largely unknown. Here, we reveal that the PAK5–aspartyl aminopeptidase (DNPEP)–ubiquitin-specific protease 4 (USP4) axis is involved in breast cancer progression. We show that PAK5 interacts with and phosphorylates DNPEP at serine 119. Functionally, we demonstrate that DNPEP overexpression suppresses breast cancer cell proliferation and invasion and restricts breast cancer growth and metastasis in mice. Furthermore, we identify USP4 as a downstream target of the PAK5–DNPEP pathway; DNPEP mediates USP4 downregulation. Importantly, we verify that DNPEP expression is frequently downregulated in breast cancer tissues and is negatively correlated with PAK5 and USP4 expression. PAK5 decreases DNPEP abundance via the ubiquitin–proteasome pathway. Consistently, analyses of clinical breast cancer specimens revealed significantly increased PAK5 and USP4 levels and an association between higher PAK5 and USP4 expression and worse breast cancer patient survival. These findings suggest a pivotal role for PAK5-elicited signaling in breast cancer progression.     

乳腺癌演变过程中胰岛素样生长因子-1的表达和临床意义

目的：探讨胰岛素样生长因子-1（IGF-1）在乳腺癌演变过程中的表达变化规律和意义。方法：采用ELESIA方法检测28名健康女性,51例乳腺良性肿瘤患者,8例非典型增生患者,60例乳腺癌患者血清中IGF-1的表达水平;采用免疫组织化学方法检测30例正常乳腺组织,52例乳腺良性肿瘤组织、35例非典型增生组织、49例乳腺癌组织中IGF-1的表迭程度。结果：IGF-1在非典型增生组织中表达程度与在乳腺癌组织、乳腺良性肿瘤组织和正常组织相比呈高表迭,P值分别为0.0208、0.048和〈0.001。乳腺癌组织和良性肿瘤组织的IGF-1表达程度与正常乳腺组织相比呈高表达,P=0.0008,P=0.0004。非典型增生患者和乳腺癌患者血清中IGF-1表达水平与乳腺良性肿瘤患者血清和正常女性血清相比差异均有统计学意义,P=0.019;绝经前乳腺癌患者血清的IGF-1表达水平比绝经后乳腺癌患者的高,P=0.039。结论：IGF-1在乳腺癌的发生和演变过程中起重要作用。IGF-1可能在非典型增生组织向癌的转变过程中发挥关键作用。血清高水平的IGF-1可能与绝经前女性乳腺癌的发病风险增加有关。IGF-1可能为乳腺癌的发病风险预测和靶向治疗提供新的途径。     

Protein kinase C epsilon is a predictive biomarker of aggressive breast cancer and a validated target for RNA interference anticancer therapy

Tumor metastasis is the major cause of morbidity and mortality in patients with breast cancer. It is critical to identify metastasis enabling genes and understand how they are responsible for inducing specific aspects of the metastatic phenotype to allow for improved clinical detection and management. Protein kinase C epsilon (PKC epsilon), a member of a family of serine/threonine protein kinases, is a transforming oncogene that has been reported to be involved in cell invasion and motility. In this study, we investigated the role of PKC epsilon in breast cancer development and progression. High-density tissue microarray analysis showed that PKC epsilon protein was detected in 73.6% (106 of 144) of primary tumors from invasive ductal breast cancer patients. Increasing PKC epsilon staining intensity was associated with high histologic grade (P = 0.0206), positive Her2/neu receptor status (P = 0.0419), and negative estrogen (P = 0.0026) and progesterone receptor status (P = 0.0008). Kaplan-Meier analyses showed that PKC epsilon was significantly associated with poorer disease-free and overall survival (log-rank, P = 0.0478 and P = 0.0414, respectively). RNA interference of PKC epsilon in MDA-MB231 cells, an aggressive breast cancer cell line with elevated PKC epsilon levels, resulted in a cell phenotype that was significantly less proliferative, invasive, and motile than the parental or the control RNA interference transfectants. Moreover, in vivo tumor growth of small interfering RNA-PKC epsilon MDA-MB231 clones was retarded by a striking 87% (P < 0.05) and incidence of lung metastases was inhibited by 83% (P < 0.02). PKC epsilon-deficient clones were found to have lower RhoC GTPase protein levels and activation. Taken together, these results revealed that PKC epsilon plays a critical and causative role in promoting an aggressive metastatic breast cancer phenotype and as a target for anticancer therapy.     

NH(2)-terminal truncated HER-2 protein but not full-length receptor is associated with nodal metastasis in human breast cancer.

BACKGROUND: The full-length receptor p185HER-2 undergoes a metalloprotease-dependent cleavage producing a membrane-associated fragment (p95HER-2) in cultured breast cancer cells. P95HER-2 has potentially enhanced signaling activity, but its expression and role in human breast cancer is poorly characterized. PURPOSE: The purpose of this project was to characterize the expression of p95HER-2 in primary breast cancers and nodal metastasis, and to study association with clinicopathological factors. EXPERIMENTAL DESIGN: P95HER-2 and p185HER-2 were examined in 337 primary breast tumors and 81 metastatic lymph nodes by Western blot analysis, and tested for associations with other clinicopathological factors. RESULTS: P95HER-2 was present in 20.9% of primary tumors from node-negative patients, in 29.1% from patients with one to three metastatic nodes, and in 36.7% from patients with four or more metastatic nodes (P = 0.027). Whereas p185HER-2 overexpression was unrelated to nodal disease (P = 0.63), the odds of lymph node metastasis were enhanced 2.9-fold by the presence of p95HER-2 (48.8% of node-negative versus 73.5% of node-positive patients; P = 0.03; odds ratio = 2.9). P95HER-2 was more frequent in metastatic lymph nodes than in primary tumors (45.7% versus 26.7%; P = 0.0009), whereas p185HER-2 overexpression was similar in both (22.3% versus 23.5%; P = 0.933). P95HER-2 did not significantly correlate with patient age, tumor size, stage, histotype, or hormone receptor status. CONCLUSIONS: P95HER-2 in primary tumors was related to extent of lymph node involvement and was enhanced in nodal tissue suggesting an important role as a marker or cause in breast cancer metastasis. Examination of the prognostic value of p95HER-2 in breast cancer and its coexpression with metalloprotease activity seem warranted.     

P-cadherin overexpression is an indicator of clinical outcome in invasive breast carcinomas and is associated with CDH3 promoter hypomethylation.

PURPOSE: P-cadherin overexpression has been reported in breast carcinomas, where it was associated with proliferative high-grade histological tumors. This study aimed to analyze P-cadherin expression in invasive breast cancer and to correlate it with tumor markers, pathologic features, and patient survival. Another purpose was to evaluate the P-cadherin promoter methylation pattern as the molecular mechanism underlying this gene regulation. EXPERIMENTAL DESIGN: Using a series of invasive breast carcinomas, P-cadherin expression was evaluated and correlated with histologic grade, estrogen receptor, MIB-1, and p53 and c-erbB-2 expression. In order to assess whether P-cadherin expression was associated with changes in CDH3 promoter methylation, we studied the methylation status of a gene 5'-flanking region in these same carcinomas. This analysis was also done for normal tissue and for a breast cancer cell line treated with a demethylating agent. RESULTS: P-cadherin expression showed a strong correlation with high histologic grade, increased proliferation, c-erbB-2 and p53 expression, lack of estrogen receptor, and poor patient survival. This overexpression can be regulated by gene promoter methylation because the 5-Aza-2'-deoxycytidine treatment of MCF-7/AZ cells increased P-cadherin mRNA and protein levels. Additionally, we found that 71% of P-cadherin-negative cases showed promoter methylation, whereas 65% of positive ones were unmethylated (P = 0.005). The normal P-cadherin-negative breast epithelial cells showed consistent CDH3 promoter methylation. CONCLUSIONS: P-cadherin expression was strongly associated with tumor aggressiveness, being a good indicator of clinical outcome. Moreover, the aberrant expression of P-cadherin in breast cancer might be regulated by gene promoter hypomethylation.     

miR-124 在乳腺癌中的表达及其作用机制研究

目的：探讨m iR- 124 表达与乳腺癌发生、发展的相关性及机制。方法：运用实时定量聚合酶链反应（qRT-PCR）检测乳腺癌细胞系以及52例患者乳腺癌癌组织和对应的癌旁正常组织样本中miR-124 的表达水平。在乳腺癌细胞株MDA-MB-231和T-47D 中过表达miR-124 后,测定细胞增殖活性以及侵袭转移能力。构建荧光素酶报告载体pMIR- 特异性蛋白1（specificityprotein 1,SP1）的3'UTR,利用荧光素酶活性检测鉴定miR-124 的预测靶基因SP1。qRT-PCR和Westernblot法分别检测SP1 的mRNA 和蛋白质的表达水平。结果：miR-124 在乳腺癌细胞系和癌组织中表达量下调,差异具有统计学意义（P < 0.01）,并与肿瘤的转移、分期、分级和预后相关。在乳腺癌细胞株MDA-MB-231 和T-47D 中过表达miR-124 后抑制乳腺癌细胞系的增殖、侵袭以及迁移（P < 0.01）。 转染miR-124 模拟物显著抑制荧光素酶的活性（P < 0.05）。 转染miR-124 模拟物显著下调MDA-MB-231 和T-47D 细胞中SP1 的mRNA（P < 0.05）和蛋白质的表达水平。结论：miR-124 在乳腺癌癌组织中低表达,miR-124 低表达与乳腺癌不良预后有关,且miR-124 可通过调控转录因子SP1 抑制乳腺癌癌细胞的增殖、侵袭和转移。miR-124 表达异常减少可能是乳腺癌发生、发展的重要因素。     

MTA1 overexpression correlates significantly with tumor grade and angiogenesis in human breast cancers

Metastasis associated antigen 1 (MTA1) is a recently identified candidate metastasis-associated gene that plays an important role in tumorigenesis and tumor aggressiveness, especially tumor invasiveness and metastasis. We analyzed the relationship between MTA1 expression and variable clinicopathological features and characterized its role in tumor angiogenesis in human breast cancers. Two hundred and sixty-three breast cancer cases that successfully underwent surgery at Hanyang University Hospital (Seoul, Korea) between January 1989 and December 1997 were enrolled. MTA1 expression was observed by immunohistochemical staining and correlated with intratumoral microvessel density (MVD) and other clinicopathological parameters. MTA1 overexpression correlated significantly with higher tumor grade (grades 1 and 2 vs grade 3, P = 0.009). However, MTA1 expression did not correlate with tumor stage, status of estrogen and progesterone receptors, or axillary lymph node metastasis. Interestingly, MTA1 expression was found to correlate significantly with tumor MVD (P = 0.002). Survival analysis did not show a significant difference between MTA1 overexpression and poorer survival. In conclusion, MTA1 overexpression was found to be closely associated with higher tumor grade and increased tumor angiogenesis. These findings suggest MTA1 as a predictor of aggressive phenotype and a possible target molecule for anti-angiogenic drugs in breast cancer treatment.     

Jun activation domain binding protein 1 expression is associated with low p27(Kip1)levels in node-negative breast cancer.

PURPOSE: The purpose is to evaluate expression levels of Jun activation domain-binding protein 1 (JAB1) in breast cancer tissue and adjacent normal tissue, to determine whether JAB1 expression is associated with p27(Kip1) expression in invasive breast carcinomas, and to evaluate the prognostic significance of JAB1 and p27(Kip1) in node-negative breast cancer. EXPERIMENTAL DESIGN: JAB1 levels were measured in 10 matched pairs of invasive breast tumor tissue and adjacent normal tissue using Western blot analysis. We also investigated the immunoreactivity of JAB1 and p27(Kip1) levels in paraffin-embedded tissue specimens from 220 patients with node-negative breast cancer who had not received adjuvant systemic therapy. The median follow-up was 15 years. RESULTS: JAB1 was expressed at higher levels in invasive tumors than in adjacent normal tissue (P = 0.01). JAB1 overexpression was observed in 57% of invasive breast cancers. Low levels of p27(Kip1) were noted in 70% of the tumor specimens. We found an inverse correlation between JAB1 and p27(Kip1) expression levels (P = 0.01). JAB1 overexpression was associated with patient age of at least 50 years (P = 0.03) and tumor size of 相似文献   

Transketolase protein TKTL1 overexpression: A potential biomarker and therapeutic target in breast cancer

Malignant tumors degrade glucose to lactate even in the presence of oxygen via the pentose phosphate pathway (ppp). The non-oxidative part of the ppp is controlled by thiamine-dependant transketolase enzyme reactions. Overexpression of the transketolase-like-1-gene (TKTL1) in urothelial and colorectal cancer is associated with poor patient outcome. We analyzed the expression of the TKTL1 protein in a retrospective institution-based patient cohort with invasive breast cancer by immunohistochemical analysis of 124 paraffin-embedded breast cancer tissues. Our study revealed TKTL1 expression in 86% of breast cancer specimens with 45% showing high expression levels. In contrast, only 29% of corresponding non-neoplastic breast tissues were TKTL1 immunopositive, including 9% with high expression levels. High expression levels of TKTL1 correlated significantly to Her2/neu overexpression (p=0.015). However, TKTL1 expression failed to reach statistical significance for other common prognostic parameters. In contrast to recent data for e.g. colorectal cancer TKTL1 overexpression did not correlate to patient outcome and survival. However, in the context of novel insights into TKTL1-related tumor metabolism and the high proportion of TKTL1 overexpressing breast cancers, this enzyme represents a potential candidate for targeted inhibition of tumor growth in this tumor entity.     

Promoter hypermethylation of the death-associated protein kinase gene in breast cancer is associated with the invasive lobular subtype

Expression of death-associated protein (DAP) kinase, a proapoptotic serine/threonine protein kinase, is frequently lost in human tumors. In a study of 134 primary breast cancer specimens hypermethylation of the DAP kinase gene was found in 13% of cases. A highly significant difference (P < 0.001) of DAP kinase inactivation was observed between invasive lobular cancer (n = 19) and invasive ductal cancer (n = 85; 53% versus 9%, respectively). Hypermethylation correlated with loss of RNA expression, estrogen receptor positivity (P < 0.01), and the absence of p53 overexpression (P < 0.01). In contrast to invasive lobular cancer, the in situ-growing precursor lesion lacked epigenetic modification of the DAP kinase promotor by aberrant methylation indicating a potential role in tumor progression. Unlike the DAP kinase gene, hypermethylation of the cyclin D2 and RASSF1A genes did not correlate with a particular histological subtype or to invasiveness [corrected]. We conclude that different histological subtypes of breast cancer may not only differ concerning specific chromosomal abnormalities and DNA mutations but also with regard to epigenetic inactivation patterns.