Expression of cyclins E, A, and B, and prognosis in lymph node-negative breast cancer

Prognostic value of cyclin B1 and cyclin B2 expression in breast cancer: A systematic review and updated meta-analysis

BACKGROUND

Cyclin B1 and cyclin B2 are key regulators of cell cycle progression and have been implicated in the prognostic significance of various cancers. This meta-analysis aimed to evaluate the prognostic value of cyclin B1 and B2 expression in breast cancer.

METHODS

A comprehensive literature search was conducted on Pubmed, Embase, MEDLINE, Web of Science, and Cochrane library. Studies with survival data and clinicopathological parameters associated with cyclin B1 and B2 or CCNB1 and CCNB2 genes were included. Survival data and clinicopathological parameters associated with cyclin B1 and B2 expression were extracted. Pooled hazard ratios and odds ratios with 95% confidence intervals were calculated. Subgroup analysis was conducted to assess heterogeneity. Publication bias was evaluated.

RESULTS

A total of 23 studies were included in the analysis. High expression of cyclin B1 was significantly associated with worse overall survival (hazard ratio [HR] = 1.69, P < .01), disease-specific survival (HR = 1.71, P < .01), and disease-free survival (HR = 2.01, P = .01). High expression of cyclin B2 was associated with worse disease-specific survival (HR = 2.46, P = .02). Clinicopathological parameters did not show significant associations with cyclin B1 and B2 expressions. When data on cyclin B1 and B2 were combined, a significant age-related difference was found (odds ratio = 0.62, P = .04).

CONCLUSIONS

This meta-analysis provides evidence supporting the prognostic significance of cyclin B1 and B2 expression in breast cancer. High expression of cyclin B1 and B2 is associated with worse survival, indicating their potential as prognostic markers in breast cancer.

Identification of potential hub genes related to the progression and prognosis of hepatocellular carcinoma through integrated bioinformatics analysis

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths among cancer patients. Genes correlated with the progression and prognosis of HCC are critically needed to be identified. In the present study, 3 Gene Expression Omnibus (GEO) datasets (GSE46408, GSE65372 and GSE84402) were used to analyze the differentially expressed genes (DEGs) between HCC and non-tumor liver tissues. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to clarify the functional roles of DEGs. A protein-protein interaction network was established to screen the hub genes associated with HCC. The prognostic values of hub genes in HCC patients were analyzed using The Cancer Genome Atlas (TCGA) database. The expression levels of hub genes were validated based on ONCOMINE, TCGA and Human Protein Atlas (HPA) databases. Notably, 56 upregulated and 33 downregulated DEGs were markedly enriched under various GO terms and four KEGG terms. Among these DEGs, 10 hub genes with high connectivity degree were identified, including cyclin B1, cyclin A2, cyclin B2, condensin complex subunit 3, PDZ binding kinase, nucleolar and spindle-associated protein 1, aurora kinase A, ZW10 interacting kinetochore protein, protein regulator of cytokinesis 1 and kinesin family member 4A. The upregulated expression levels of these hub genes in HCC tissues were further confirmed by ONCOMINE, TCGA, and HPA databases. Additionally, the increased mRNA expression of each hub gene was related to the unfavorable disease-free survival and overall survival of HCC patients. The present study identified ten genes associated with HCC, which may help to provide candidate targets for the diagnosis and treatment of HCC.

Prognostic and clinicopathological significance of cyclin B expression in patients with breast cancer: A meta-analysis

BACKGROUND

Cyclin B plays a crucial role in cancer cell cycle progression and is overexpressed in many human cancers, including breast cancer. However, the prognostic value of cyclin B expression in breast cancer is controversial. We performed a meta-analysis to assess the clinicopathological and prognostic significance of cyclin B expression in breast cancer.

METHODS

We searched PubMed, web of science, and Embase databases to retrieve the publications investigating the association between cyclin B expression and clinicopathological/prognostic significance in breast cancer patients. The pooled hazard ratio (HR) or odds ratio (OR) with its 95% confidence intervals (CIs) were used to estimate the effects.

RESULTS

Ten studies with 2366 breast cancer patients were included to evaluate the association between cyclin B expression and overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), and clinicopathological parameters. The results showed that cyclin B overexpression in breast cancer patients was significantly associated with both poor OS (univariate analysis: HR = 2.38, 95% CI = 1.72-3.30, P < .001), DFS (univariate analysis: HR = 1.86, 95% CI = 1.50-2.32, P < .001; multivariate analysis: HR = 1.75, 95% CI = 1.22-2.52, P = .003), and DSS (multivariate analysis: HR = 5.42, 95% CI = 2.15-13.66, P < .001). Additionally, cyclin B overexpression was significantly associated with lymphatic invasion (OR = 2.58, 95% CI = 1.03-6.46, P = .017).

CONCLUSION

Cyclin B overexpression appears to be an independent potential prognostic marker to DSS and DFS for breast cancer. Further studies with large sample size are needed to dissect the relationship between cyclin B and clinicopathological features or prognosis of breast cancer.

Cyclin E amplification, over-expression, and relapse-free survival in HER-2-positive primary breast cancer

Cyclin E is a well-characterized cell cycle regulator and an amplified oncogene in breast cancer. Over-expression of cyclin E has generally been associated with poor survival. Recent studies have shown an interaction between HER-2 (ERBB2) and cyclin E, but the exact mechanism is unknown. Interestingly, cyclin E over-expression has been associated with trastuzumab resistance. We studied cyclin E over-expression, CCNE1 amplification, and relapse-free survival in HER-2-positive primary breast cancers treated with and without trastuzumab therapy. Formalin-fixed paraffin-embedded tissue samples from 202 HER-2-positive breast carcinomas were studied. Expression levels of cyclin E and proliferation marker Ki-67 were determined using immunohistochemistry. Chromogenic in situ hybridization (CISH) with a gene-specific bacterial artificial chromosome (BAC) probe was used to analyze presence of CCNE1 amplification. Majority of HER-2-positive breast carcinomas exhibited nuclear staining for cyclin E protein. Cyclin E was highly expressed (≥50 % cells) in 37 % of cases. Incidence of CCNE1 amplification (≥6 gene copies/cell or clusters) was 8 %. Cyclin E amplification and over-expression were strongly associated with each other, grade, hormone receptors, and Ki-67. Neither high cyclin E expression nor CCNE1 amplification was associated with relapse-free survival (RFS) irrespective of short-term (9-week regimen) adjuvant trastuzumab therapy. These results confirm cyclin E and HER-2 gene co-amplification in a fraction of HER-2-positive breast cancers. Cyclin E is frequently over-expressed but appears to have limited value as a prognostic or predictive factor in HER-2-positive breast cancer regardless of trastuzumab therapy.

MicroRNA-10a is reduced in breast cancer and regulated in part through retinoic acid

Background

MicroRNAs (miRNAs) are short non-coding RNA molecules that play a critical role in mRNA cleavage and translational repression, and are known to be altered in many diseases including breast cancer. MicroRNA-10a (miR-10a) has been shown to be deregulated in various cancer types. The aim of this study was to investigate miR-10a expression in breast cancer and to further delineate the role of retinoids and thyroxine in regulation of miR-10a.

Methods

Following informed patient consent and ethical approval, tissue samples were obtained during surgery. miR-10a was quantified in malignant (n = 103), normal (n = 30) and fibroadenoma (n = 35) tissues by RQ-PCR. Gene expression of Retinoic Acid Receptor beta (RARβ) and Thyroid Hormone receptor alpha (THRα) was also quantified in the same patient samples (n = 168). The in vitro effects of all-trans Retinoic acid (ATRA) and L-Thyroxine (T₄) both individually and in combination, on miR-10a expression was investigated in breast cancer cell lines, T47D and SK-BR-3.

Results

The level of miR-10a expression was significantly decreased in tissues harvested from breast cancer patients (Mean (SEM) 2.1(0.07)) Log₁₀ Relative Quantity (RQ)) compared to both normal (3.0(0.16) Log₁₀ RQ, p < 0.001) and benign tissues (2.6(0.17) Log₁₀ RQ, p < 0.05). The levels of both RARβ and THRα gene expression were also found to be decreased in breast cancer patients compared to controls (p < 0.001). A significant positive correlation was determined between miR-10a and RARβ (r = 0.31, p < 0.001) and also with THRα (r = 0.32, p < 0.001). In vitro stimulation assays revealed miR-10a expression was increased in both T47D and SK-BR-3 cells following addition of ATRA (2 fold (0.7)). While T₄ alone did not stimulate miR-10a expression, the combination of T₄ and ATRA was found to have a positive synergistic effect.

Conclusion

The data presented supports a potential tumour suppressor role for miR-10a in breast cancer, and highlights retinoic acid as a positive regulator of the microRNA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1374-y) contains supplementary material, which is available to authorized users.

Expression of CDK1(Tyr15), pCDK1(Thr161), Cyclin B1 (total) and pCyclin B1(Ser126) in vulvar squamous cell carcinoma and their relations with clinicopatological features and prognosis

Cyclin B1-CDK1 complex plays an important role in the regulation of cell cycle. Activation of Cyclin B1 and CDK1 and the formation of the complex in G2/M are under multiple regulations involving many regulators such as isoforms of 14-3-3 and CDC25 and Wee1. Abnormal expression of Cyclin B1 and CDK1 has been detected in various tumors. However, to our knowledge no previous study has investigated Cyclin B1 and CDK1 in vulvar cancer. Therefore, we evaluated the statuses of CDK1Tyr15, pCDK1Thr161, Cyclin B1 (total) and pCyclin B1Ser126 in 297 cases of vulvar squamous cell carcinomas by immunohistochemistry. Statistical analyses were performed to explore their clinicopathological and prognostic values. In at least 25% of tumor cases high expression of CDK1Tyr15, pCDK1Thr161, Cyclin B1 (total) and pCyclin B1Ser126 was observed, compared to the low levels in normal vulvar squamous epithelium. Elevated levels of CDK1Tyr15, pCDK1Thr161, Cyclin B1 (total) and pCyclin B1Ser126 were correlated with advanced tumor behaviors and aggressive features. Although CDK1Tyr15, pCDK1Thr161, Cyclin B1 (total) and pCyclin B1Ser126 could not be identified as prognostic factors, combinations of (pCDK1Thr161 C+N + 14-3-3σN), (pCDK1Thr161 C+N + 14-3-3ηC), (pCDK1Thr161 C+N + Wee1C) and (pCDK1Thr161 C+N + 14-3-3σN + 14-3-3ηC + Wee1C) were correlated with disease-specific survival (p = 0.036, p = 0.029, p = 0.042 and p = 0.007, respectively) in univariate analysis. The independent prognostic significance of (pCDK1Thr161 C+N + 14-3-3σN + 14-3-3ηC + Wee1C) was confirmed by multivariate analysis. In conclusion, CDK1Tyr15, pCDK1Thr161, Cyclin B1 (total) and pCyclin B1Ser126 may be involved in progression of vulvar squamous cell carcinoma. The combination of pCDK1Thr161, 14-3-3σ, 14-3-3η and Wee1 was a statistically independent prognostic factor.

Cyclin E1 is a strong prognostic marker for death from lymph node negative breast cancer. A population-based case-control study

BACKGROUND

A large proportion of women with lymph node negative breast cancer treated with systemic adjuvant treatment do not benefit from such therapy since the patient is already cured by local treatment. Several studies have suggested that proliferation markers are strong prognostic factors in early breast cancer. Cyclins are probably the most specific markers of cell proliferation. Previously high expression of cyclin E has been associated with breast cancer recurrence.

MATERIALS AND METHODS

In this study we investigate the prognostic value of cyclin E1 in node negative breast cancer patients. In a population-based cohort 186 women who died from breast cancer were defined as cases and 186 women alive at the corresponding time as controls. Inclusion criteria were tumour size ≤ 50 mm, no lymph node metastases and no adjuvant chemotherapy. The study was designed to detect an odds ratio of 2.5 with a power of 90% and significance level of 0.05. Cyclin E1 was determined with immunohistochemistry (IHC) on tissue microarray (TMA).

RESULTS

High expression of cyclin E1 was significantly associated with breast cancer death, in both uni- and multivariate analyses with odds ratios (OR) 2.3 [univariate, 95% confidence interval (CI) 1.5-3.6] and 2.1 (multivariate, 95% CI 1.2-3.5).

DISCUSSION

Cyclin E1 is a strong prognostic factor for breast cancer death in a population-based and node negative patient cohort and can identify high-risk patients in this group.

Cell cycle marker expression in benign and malignant intraductal papillary lesions of the breast

AIMS

The diagnosis of intraductal papillary lesions of the breast on core biopsy remains challenging in pathology, with most patients requiring formal surgical excision for a definitive diagnosis. The aim of this study was to determine whether a representative panel of proliferative cell cycle immunohistochemical markers (cyclin A2, cyclin B1 and cyclin D1) could improve the specificity of pathological diagnosis of these lesions.

METHODS

A series of 68 surgically excised intraductal papillary lesion cases were retrospectively selected, and immunohistochemistry for cyclin A2, cyclin B1 and cyclin D1 was performed.

RESULTS

Cyclin B1 (OR 1.80, 95% CI 1.01 to 3.2, p=0.046) and cyclin D1 (OR 1.13, 95% CI 1.05 to 1.22, p=0.002) expression was independently associated with a diagnosis of malignancy in papillary lesions, although expression was frequently heterogeneous and only focal. Cyclin A2 expression (OR 0.76, 95% CI 0.41 to 1.4, p=0.38) was not associated with a malignant diagnosis in multivariable logistic regression models. All three cyclins displayed high sensitivity (80%-95%) for a diagnosis of malignancy, although cyclin B1 showed a superior specificity of 72.7% compared with the low specificity of cyclins A2 and D1.

CONCLUSIONS

Our study has identified for the first time that the expression of key cell cycle markers differs between benign and malignant papillary breast lesions and identified changes to the mitotic marker, cyclin B1, as particularly significant. However, given the low level and heterogeneous nature of expression of these markers, there remains a significant risk of undersampling in core biopsies and thus they are unlikely to be useful in routine clinical practice.

miR-379 regulates cyclin B1 expression and is decreased in breast cancer

MicroRNAs are small non-coding RNA molecules that control gene expression post-transcriptionally, and are known to be altered in many diseases including breast cancer. The aim of this study was to determine the relevance of miR-379 in breast cancer. miR-379 expression was quantified in clinical samples including tissues from breast cancer patients (n=103), healthy controls (n=30) and patients with benign breast disease (n=35). The level of miR-379 and its putative target Cyclin B1 were investigated on all breast tissue specimens by RQ-PCR. Potential relationships with gene expression and patient clinicopathological details were also determined. The effect of miR-379 on Cyclin B1 protein expression and function was investigated using western blot, immunohistochemistry and proliferation assays respectively. Finally, the levels of circulating miR-379 were determined in whole blood from patients with breast cancer (n=40) and healthy controls (n=34). The level of miR-379 expression was significantly decreased in breast cancer (Mean(SEM) 1.9 (0.09) Log₁₀ Relative Quantity (RQ)) compared to normal breast tissues (2.6 (0.16) Log₁₀ RQ, p<0.01). miR-379 was also found to decrease significantly with increasing tumour stage. A significant negative correlation was determined between miR-379 and Cyclin B1 (r=-0.31, p<0.001). Functional assays revealed reduced proliferation (p<0.05) and decreased Cyclin B1 protein levels following transfection of breast cancer cells with miR-379. Circulating miR-379 was not significantly dysregulated in patients with breast cancer compared to healthy controls (p=0.42). This data presents miR-379 as a novel regulator of Cyclin B1 expression, with significant loss of the miRNA observed in breast tumours.

Sticky siRNAs targeting survivin and cyclin B1 exert an antitumoral effect on melanoma subcutaneous xenografts and lung metastases

Background

Melanoma represents one of the most aggressive and therapeutically challenging malignancies as it often gives rise to metastases and develops resistance to classical chemotherapeutic agents. Although diverse therapies have been generated, no major improvement of the patient prognosis has been noticed. One promising alternative to the conventional therapeutic approaches currently available is the inactivation of proteins essential for survival and/or progression of melanomas by means of RNA interference. Survivin and cyclin B1, both involved in cell survival and proliferation and frequently deregulated in human cancers, are good candidate target genes for siRNA mediated therapeutics.

Methods

We used our newly developed sticky siRNA-based technology delivered with linear polyethyleneimine (PEI) to inhibit the expression of survivin and cyclin B1 both in vitro and in vivo, and addressed the effect of this inhibition on B16-F10 murine melanoma tumor development.

Results

We confirm that survivin and cyclin B1 downregulation through a RNA interference mechanism induces a blockage of the cell cycle as well as impaired proliferation of B16-F10 cells in vitro. Most importantly, PEI-mediated systemic delivery of sticky siRNAs against survivin and cyclin B1 efficiently blocks growth of established subcutaneaous B16-F10 tumors as well as formation and dissemination of melanoma lung metastases. In addition, we highlight that inhibition of survivin expression increases the effect of doxorubicin on lung B16-F10 metastasis growth inhibition.

Conclusion

PEI-mediated delivery of sticky siRNAs targeting genes involved in tumor progression such as survivin and cyclin B1, either alone or in combination with chemotherapeutic drugs, represents a promising strategy for melanoma treatment.

The combination of Ki67, histological grade and estrogen receptor status identifies a low-risk group among 1,854 chemo-naïve women with N0/N1 primary breast cancer

Background

The aim was to confirm a previously defined prognostic index, combining a proliferation marker, histological grade, and estrogen receptor (ER) in different subsets of primary N0/N1 chemo-naïve breast cancer patients.

Methods/design

In the present study, including 1,854 patients, Ki67 was used in the index (KiGE), since it is the generally accepted proliferation marker in clinical routine. The low KiGE-group was defined as histological grade 1 patients and grade 2 patients which were ER-positive and had low Ki67 expression. All other patients made up the high KiGE-group. The KiGE-index separated patients into two groups with different prognosis. In multivariate analysis, KiGE was significantly associated with disease-free survival, when adjusted for age at diagnosis, tumor size and adjuvant endocrine treatment (hazard ratio: 3.5, 95% confidence interval: 2.6–4.7, P<0.0001).

Discussion

We have confirmed a prognostic index based on a proliferation marker (Ki67), histological grade, and ER for identification of a low-risk group of patients with N0/N1 primary breast cancer. For this low-risk group constituting 57% of the patients, with a five-year distant disease-free survival of 92%, adjuvant chemotherapy will have limited effect and may be avoided.

Prognostic value of proliferation markers expression in breast cancer

In this study, immunohistochemical expression of five proliferation markers: Ki-67, aurora-A kinase, survivin, B-Myb and cyclin B1, was analyzed. Consecutive 215 tumor samples from breast cancer patients operated from 2002 to 2003 were analyzed using the TMA ("tissue microarray") method. The median follow-up was 95 months (from 7.8 to 107 months). Statistically significant correlations between expression levels in five proliferation markers, and correlations between some of the proliferation markers and traditional prognostic factors were found. Statistically significant prognostic influence of aurora-A kinase, survivin and B-Myb expression levels on overall and disease-free survival was found, and cyclin B1 expression level on disease-free survival. A multivariate analysis confirmed survivin and B-Myb expression as independent prognostic factors of overall (p = 0.0195; p = 0.0004) and disease-free survival (p = 0.0107 and p = 0.0205) in breast cancer patients.

Bioluminescence imaging of DNA synthetic phase of cell cycle in living animals

Bioluminescence reporter proteins have been widely used in the development of tools for monitoring biological events in living cells. Currently, some assays like flow cytometry analysis are available for studying DNA synthetic phase (S-phase) targeted anti-cancer drug activity in vitro; however, techniques for imaging of in vivo models remain limited. Cyclin A2 is known to promote S-phase entry in mammals. Its expression levels are low during G1-phase, but they increase at the onset of S-phase. Cyclin A2 is degraded during prometaphase by ubiquitin-dependent, proteasome-mediated proteolysis. In this study, we have developed a cyclin A2-luciferase (CYCA-Luc) fusion protein targeted for ubiquitin-proteasome dependent degradation, and have evaluated its utility in screening S-phase targeted anti-cancer drugs. Similar to endogenous cyclin A2, CYCA-Luc accumulates during S-phase and is degraded during G2/M-phase. Using Cdc20 siRNA we have demonstrated that Cdc20 can mediate CYCA-Luc degradation. Moreover, using noninvasive bioluminescent imaging, we demonstrated accumulation of CYCA-Luc in response to 10-hydroxycamptothecin (HCPT), an S-phase targeted anti-cancer drug, in human tumor cells in vivo and in vitro. Our results indicate that a CYCA-Luc fusion reporter system can be used to monitor S-phase of cell cycle, and evaluate pharmacological activity of anti-cancer drug HCPT in real time in vitro and in vivo, and is likely to provide an important tool for screening such drugs.

Multi-biomarker pattern for tumor identification and prognosis

In last decades, the basic, clinical, and translational research efforts have been directed to the identification of standard biomarkers associated with the degree of malignancy. There is an increasingly public health concern for earlier detection of cancer development at stages in which successful treatments can be achieved. To meet this urgent clinical demand, early stage cancer biomarkers supported by reliable and robust experimental data that can be readily applicable in the clinical practice, are required. In the current standard protocols, when one or two of the canonical proliferating index biomarkers are analyzed, contradictory results are frequently reached leading to incorrect cancer diagnostic and unsuccessful therapies. Therefore, the identification of other cellular characteristics or signatures present in the tumor cells either alone or in combination with the well-established proliferation markers emerge as an alternative strategy in the improvement of cancer diagnosis and treatment. Because it is well known that several pathways and processes are altered in tumor cells, the concept of "single marker" in cancer results incorrect. Therefore, this review aims to analyze and discuss the proposal that the molecular profile of different genes or proteins in different altered tumor pathways must be established to provide a better global clinical pattern for cancer detection and prognosis.

Cyclin E low-molecular-weight isoform as a predictor of breast cancer in Japanese women

Overexpression of low-molecular-weight isoforms (LMWI) of cyclin E in breast cancer cells is associated with poor prognosis and could serve a novel role in breast cancer progression. LMWI originate from proteolytic processing of cyclin E, which is deregulated and hyperactive. In this study, levels of full-form/LMWI cyclin E were determined with the use of Western blot analysis in 69 Japanese breast cancer patients. LMWI cyclin E levels were significantly correlated with known parameters such as tumor grade and estrogen/progesterone receptor expression. In multivariate analysis, patient survival was significantly correlated with tumor grade but not with either form of cyclin E. LMWI was not as strong a predictor as tumor grade in this study, whereas some cases of early relapse with LMWI overexpression and lower tumor grade were reported. Thus, LMWI might be a good complementary factor to other predictors for early relapse of breast cancer.

The cyclins: a family of widely expressed tumor antigens?

Continuous cell division is a hallmark of cancer and cell-cycle regulators therefore represent relevant target molecules for tumor therapy. Among these targets the cyclins are of particular interest as they are overexpressed in various tumor entities with little expression in normal tissue. Here we review evidence that these molecules are recognized by the immune system, summarize why cyclins A, B and D in particular appear to be interesting targets for active and passive immunotherapy, and discuss whether the entire family could be an interesting novel class of tumor antigens for cancer treatment and prevention.

Protein subcellular localization profiling of breast cancer cells by dissociable antibody microarray staining

We have developed dissociable antibody microarray (DAMA) staining technology that provides a new approach to the global analysis of protein subcellular localization (SCL) in fixed cells. We have developed and optimized this technology for protein SCL profiling, generated ChipView, a program for management and analysis of molecular image database, and utilized the technique to identify proteins with unique SCL in breast cancer cell lines. We compared the SCL profiles of 325 proteins among nine different breast cell lines, and have identified one protein, Cyclin B1, with distinctively different SCLs between normal and cancer cell lines. With classic individual immunostaining, Cyclin B1 was confirmed to localize to the cytoplasm of seven breast cancer cell lines and in both cytoplasm and nuclei of two normal breast cell lines, and to have higher expression levels in the cancer cell lines tested.

Cyclin B is an immunohistochemical proliferation marker which can predict for breast cancer death in low-risk node negative breast cancer

Patients with low-risk node negative breast cancer have an excellent prognosis with 5% breast cancer mortality at 10 years. However, prognostic factors are needed to identify poor prognostic patients who might benefit from adjuvant systemic therapy. Proliferation has been identified as the most important component of gene expression profiles. Cyclin B is a proliferative marker easily assessed by immunohistochemistry. We wanted to examine cyclin B as a prognostic factor in low-risk breast cancer patients.

PATIENTS AND METHODS

Using an experimental study design, we compared women dying early from their breast cancer (n=17) with women free from relapse more than eight years after initial diagnosis (n=24). All women had stage I, node negative and hormone receptor positive disease. None had received adjuvant chemotherapy. Tumor samples were immunostained for cyclin B using commercial antibodies.

RESULTS

The mean percentage of cyclin B (12%) was significantly higher (p=0.001) in women dying from their breast cancer compared with women free from relapse (5%). High cyclin B (> or =9%) identified 11/17 patients dying from breast cancer and low cyclin B identified 22/24 patients free from relapse. The sensitivity and specificity of cyclin B was 65% and 92%, respectively.

DISCUSSION

We found that low-risk node negative patients with high expression of cylin B had a significantly worse outcome than patients with low expression of cyclin B. Cyclin B could separate patients with poor survival from those with good survival with 80% accuracy. We suggest that cyclin B might be a potent prognostic factor in this low-risk patient group.

Classical and Novel Prognostic Markers for Breast Cancer and their Clinical Significance

The use of biomarkers ensures breast cancer patients receive optimal treatment. Established biomarkers such as estrogen receptor (ER) and progesterone receptor (PR) have been playing significant roles in the selection and management of patients for endocrine therapy. HER2 is a strong predictor of response to trastuzumab. Recently, the roles of ER as a negative and HER2 as a positive indicator for chemotherapy have been established. Ki67 has traditionally been recognized as a poor prognostic factor, but recent studies suggest that measurement of Ki67-positive cells during treatment will more effectively predict treatment efficacy for both anti-hormonal and chemotherapy. p53 mutations are found in 20–35% of human breast cancers and are associated with aggressive disease with poor clinical outcome when the DNA-binding domain is mutated. The utility of cyclin D1 as a predictor of breast cancer prognosis is controversial, but cyclin D1b overexpression is associated with poor prognosis. Likewise, overexpression of the low molecular weight form of cyclin E1 protein predicts poor prognosis. Breast cancers from BRCA1/2 carriers often show high nuclear grades, negativity to ER/PR/HER2, and p53 mutations, and thus, are associated with poor prognosis. The prognostic values of other molecular markers, such as p14^ARF, TBX2/3, VEGF in breast cancer are also discussed. Careful evaluation of these biomarkers with current treatment modality is required to determine whether their measurement or monitoring offer significant clinical benefits.

Analysis of cyclins A, B1, D1 and E in breast cancer in relation to tumour grade and other prognostic factors

Background

The cell cycle is promoted by activation of cyclin dependent kinases (Cdks), which are regulated positively by cyclins and negatively by Cdk inhibitors. Proliferation of carcinoma is associated with altered regulation of the cell cycle. Little is known on the combined alterations of cyclins A, B1, D1 and E in breast cancer in relation to the tumour grade and other prognostic factors.

Findings

Immunohistochemical analysis of cyclins A, B1, D1 and E, estrogen receptor, progesterone receptor, Ki-67, Her-2/neu and CK5/6 was performed on 53 breast carcinomas. mRNA levels of the cyclins were analysed of 12 samples by RT-PCR. The expression of cyclins A, B1 and E correlated with each other, while cyclin D1 correlated with none of these cyclins. Cyclins A, B1 and E showed association with tumour grade, Her-2/neu and Ki-67. Cyclin E had a negative correlation with hormone receptors and a positive correlation with triple negative carcinomas. Cyclin D1 had a positive correlation with ER, PR and non-basal breast carcinomas.

Conclusion

Cyclin A, B1 and E overexpression correlates to grade, Ki-67 and Her2/neu expression. Overexpression of cyclin D1 has a positive correlation with receptor status and non-basal carcinomas suggesting that cyclin D1 expression might be a marker of good prognosis. Combined analysis of cyclins indicates that cyclin A, B and E expression is similarly regulated, while other factors regulate cyclin D1 expression. The results suggest that the combined immunoreactivity of cyclins A, B1, D and E might be a useful prognostic factor in breast cancer.

Aberrant expression of cyclin E in low-risk node negative breast cancer

BACKGROUND

Cyclin E is a cell cycle regulatory protein which occurs in G1, peaks in late G1 and is degraded in early S-phase. Cyclin E overexpression appears to be an independent prognostic factor for overall survival in breast cancer. Nuclear cyclin A is a reliable marker for S-and G2-phases. Consequently, aberrant expression of cyclin E can be detected by simultaneous immunostainings for cyclin A and cyclin E. Studies have shown that aberrant cyclin E might provide additional prognostic information compared to that of cyclin E alone. This study aimed to investigate cyclin E and aberrant cyclin E expression in low-risk node negative breast cancer.

MATERIAL AND METHODS

We compared women that died from their breast cancer (n=17) with women free from relapse > 8 years after initial diagnosis (n=24). All women had stage I, low risk breast cancer. The groups were matched regarding tumour size, receptor status, adjuvant chemotherapy and tumour differentiation. Tumour samples were analysed regarding expression of cyclin A, cyclin E and double-stained tumour cells using immunoflourescence staining and digital microscopy.

RESULTS

No differences were seen regarding expression of cyclin E or aberrant cyclin E in cases compared to controls.

DISCUSSION

We conclude that neither cyclin E nor aberrant cyclin E is a prognostic factor in low-risk node negative breast cancer patients.

Cyclin E Expression and Prognosis in Breast Cancer Patients: A Meta-Analysis of Published Studies

In vitro studies showed that cyclin E can accelerate the cell cycle by shorten the G1/S phase transition. Therefore, varieties of studies have investigated the relationship between cyclin E and survival in breast cancer patients. However, the results differed widely between studies. We reviewed the published studies and performed a meta-analysis, which including 12 independent studies and 2,534 patients. The combined HR estimate for relapse-free survival (RFS) was 2.32 (95% CI, 1.25-4.30) and 1.72 (95% CI, 0.95-3.10) in univariate and multivariate analysis, respectively. In addition, the combined HR estimate for overall survival (OS) and breast cancer specific survival (BCSS) was 2.98 (95% CI, 1.85-4.78) and 2.86 (95% CI, 1.85-4.41) in univariate and multivariate analysis, respectively. In conclusion, the high level of cyclin E appears to be an independent prognostic factor to OS/BCSS of breast cancer patients but not to RFS.

Phenol peels as a novel therapeutic approach for actinic keratosis and Bowen disease: prospective pilot trial with assessment of clinical, histologic, and immunohistochemical correlations

BACKGROUND

Although chemical peels may be used for precancerous lesions, no histologic or immunohistochemical studies have been performed to validate clinical impressions and/or outcome.

OBJECTIVE

Our purpose was to investigate the efficacy and prognostic relevance of phenol peels in Japanese patients with actinic keratosis and Bowen disease using clinical and histologic criteria.

METHODS

A total of 46 patients were treated with phenol peels, and followed up for at least 1 year after treatment. Biopsy specimens were taken before and after treatment. Cases of complete response were classified by the number of treatment sessions. We evaluated parameters for epidermal thickness, proliferation, dysplasia, and apoptosis, and clinical characteristics to correlate phenol peels with assessments of efficacy, patient-selection criteria, and risk for transformation to cutaneous squamous cell carcinoma.

RESULTS

There were 39 (84.8%) patients with a complete response after one to 8 treatment sessions. Statistically, differences in clinical improvement with peels and the number of treatment sessions correlated with histology, personal history of skin cancer, tumor thickness, and cyclin A expression.

LIMITATIONS

This study was a prospective pilot trial. Blinded, placebo-controlled, randomized studies would be ideal.

CONCLUSION

We conclude that phenol peels are very effective for treating precancerous lesions of actinic keratosis and Bowen disease. In addition, our study clearly demonstrates that tumor thickness and cyclin A could be specific and useful markers as adjunctive diagnostic tools to predict the efficacy of phenol treatment of these lesions.

High cyclin B1 expression is associated with poor survival in breast cancer

Cyclin B1 regulates the G₂-M transition of the cell cycle. Cyclin B1 expression is higher in premalignant and malignant than normal breast lesions. Correlation of cyclin B1 expression with other histopathological variables and prognostic role in breast cancer are not fully understood. Traditionally used prognostic criteria identify large subset of patients to receive adjuvant chemotherapy and to be exposed to adverse effects. A reliable and simple method helping prognostic evaluation in breast cancer is needed. We analysed cyclin B1 expression on 1348 invasive breast cancers and studied correlations with other histopathological variables and survival. High cyclin B1 correlated with high tumour grade, large tumour size and positive nodal status, oestrogen and progesterone receptor negativity, positive HER2 and p53 status, young age at diagnosis, and high cyclin E, cyclin A and Ki67 expression. Among patients not given adjuvant chemotherapy high cyclin B1 was a strong predictor of shorter overall and metastasis-free survival (RR 3.74, P<0.0005 and RR 3.51, P<0.0005, respectively), and remained as an independent prognostic factor also in multivariate analysis (RR 1.80, P=0.04 and RR 2.31, P=0.02, respectively). This study suggests high cyclin B1 associates with aggressive phenotype and is an independent prognostic factor in breast cancer.

Multiple biomarkers in molecular oncology. II. Molecular diagnostics applications in breast cancer management

In recent years, the application of genomic and proteomic technologies to the problem of breast cancer prognosis and the prediction of therapy response have begun to yield encouraging results. Independent studies employing transcriptional profiling of primary breast cancer specimens using DNA microarrays have identified gene expression profiles that correlate with clinical outcome in primary breast biopsy specimens. Recent advances in microarray technology have demonstrated reproducibility, making clinical applications more achievable. In this regard, one such DNA microarray device based upon a 70-gene expression signature was recently cleared by the US FDA for application to breast cancer prognosis. These DNA microarrays often employ at least 70 gene targets for transcriptional profiling and prognostic assessment in breast cancer. The use of PCR-based methods utilizing a small subset of genes has recently demonstrated the ability to predict the clinical outcome in early-stage breast cancer. Furthermore, protein-based immunohistochemistry methods have progressed from using gene clusters and gene expression profiling to smaller subsets of expressed proteins to predict prognosis in early-stage breast cancer. Beyond prognostic applications, DNA microarray-based transcriptional profiling has demonstrated the ability to predict response to chemotherapy in early-stage breast cancer patients. In this review, recent advances in the use of multiple markers for prognosis of disease recurrence in early-stage breast cancer and the prediction of therapy response will be discussed.

Expression of bcl-2 in breast cancer: correlation with clinicopathological characteristics and survival

Breast cancer is the most common malignancy in women. It is an immensely heterogeneous disease, characterised by a broad variety of clinical development. The research in recent years has focused on finding new markers of prognosis. This study investigates the role of expression of the bcl-2 protein in breast cancer. We analysed bcl-2 expression in 57 women with primary breast carcinoma who were treated with neoadjuvant (primary) chemotherapy, followed by a surgical procedure. The bcl-2 expression was correlated with other clinicopathological characteristics of the tumour- histological grade, stage, expression of hormonal receptors, proliferation rate, and with the survival of the patients. No significant association of bcl-2 expression with either overall survival or disease free survival was found.

Activation of the mammalian target of rapamycin signalling pathway in epidermal tumours and its correlation with cyclin-dependent kinase 2

BACKGROUND

The enzyme mammalian target of rapamycin (mTOR) integrates many different cellular signals to control cell growth and proliferation, protein synthesis and breakdown, and other processes. Dysregulation of mTOR is implicated in a range of human diseases, including cancers and cardiovascular disorders. To date, there has been no report on the expression of protein kinase B (AKT)/mTOR cell signalling in epidermal tumours.

OBJECTIVES

This study was designed to investigate the activation of the mTOR signalling pathway in epidermal tumours and to correlate this with cyclin-dependent kinase 2 (CDK2) expression.

METHODS

Immunohistological staining was performed with phosphorylated (p-) AKT, p-mTOR, p-4E-binding protein 1 (p-4EBP1), p-ribosomal protein S6 (p-S6), p-p70 ribosomal protein S6 kinase 1 (p-p70S6K1) and CDK2 in 15 cases each of seborrhoeic keratosis, actinic keratosis, keratoacanthoma and Bowen's disease (BD), and 25 cases of squamous cell carcinoma (SCC). Fifteen normal skin (NS) samples served as control.

RESULTS

Among 85 tumours, 40 (47%) were positive for p-AKT, 31 (36%) for p-mTOR, 44 (52%) for p-4EBP1, 38 (45%) for p-S6, and 39 (46%) for p-p70S6K1. CDK2 immunostaining was positive in all cases of SCC and BD, and in 67% of benign tumours. All of these markers were stained much more frequently in malignant tumours than in benign tumours or NS. p-AKT, p-mTOR, p-4EBP1, p-p70S6K1 and p-S6 each showed high correlation with CDK2.

CONCLUSIONS

Constitutive activation of the AKT/mTOR pathway was frequent in epidermal tumours, especially in malignant tumours. Activation was highly correlated with CDK2 expression, suggesting that the AKT/mTOR pathway may induce the malignant transition through CDK2 in epidermal tumours.

Identification of a gene signature in cell cycle pathway for breast cancer prognosis using gene expression profiling data

Background

Numerous studies have used microarrays to identify gene signatures for predicting cancer patient clinical outcome and responses to chemotherapy. However, the potential impact of gene expression profiling in cancer diagnosis, prognosis and development of personalized treatment may not be fully exploited due to the lack of consensus gene signatures and poor understanding of the underlying molecular mechanisms.

Methods

We developed a novel approach to derive gene signatures for breast cancer prognosis in the context of known biological pathways. Using unsupervised methods, cancer patients were separated into distinct groups based on gene expression patterns in one of the following pathways: apoptosis, cell cycle, angiogenesis, metastasis, p53, DNA repair, and several receptor-mediated signaling pathways including chemokines, EGF, FGF, HIF, MAP kinase, JAK and NF-κB. The survival probabilities were then compared between the patient groups to determine if differential gene expression in a specific pathway is correlated with differential survival.

Results

Our results revealed expression of cell cycle genes is strongly predictive of breast cancer outcomes. We further confirmed this observation by building a cell cycle gene signature model using supervised methods. Validated in multiple independent datasets, the cell cycle gene signature is a more accurate predictor for breast cancer clinical outcome than the previously identified Amsterdam 70-gene signature that has been developed into a FDA approved clinical test MammaPrint^®.

Conclusion

Taken together, the gene expression signature model we developed from well defined pathways is not only a consistently powerful prognosticator but also mechanistically linked to cancer biology. Our approach provides an alternative to the current methodology of identifying gene expression markers for cancer prognosis and drug responses using the whole genome gene expression data.

The extreme COOH terminus of the retinoblastoma tumor suppressor protein pRb is required for phosphorylation on Thr-373 and activation of E2F

The retinoblastoma protein pRb plays a pivotal role in G(1)- to S-phase cell cycle progression and is among the most frequently mutated gene products in human cancer. Although much focus has been placed on understanding how the A/B pocket and COOH-terminal domain of pRb cooperate to relieve transcriptional repression of E2F-responsive genes, comparatively little emphasis has been placed on the function of the NH(2)-terminal region of pRb and the interaction of the multiple domains of pRb in the full-length context. Using "reverse mutational analysis" of Rb(DeltaCDK) (a dominantly active repressive allele of Rb), we have previously shown that restoration of Thr-373 is sufficient to render Rb(DeltaCDK) sensitive to inactivation via cyclin-CDK phosphorylation. This suggests that the NH(2)-terminal region plays a more critical role in pRb regulation than previously thought. In the present study, we have expanded this analysis to include additional residues in the NH(2)-terminal region of pRb and further establish that the mechanism of pRb inactivation by Thr-373 phosphorylation is through the dissociation of E2F. Most surprisingly, we further have found that removal of the COOH-terminal domain of either RbDeltaCDK(+T373) or wild-type pRb yields a functional allele that cannot be inactivated by phosphorylation and is repressive of E2F activation and S-phase entry. Our data demonstrate a novel function for the NH(2)-terminal domain of pRb and the necessity for cooperation of multiple domains for proper pRb regulation.

Genomic instability and proliferative activity as risk factors for distant metastases in breast cancer

The role of genomic instability and proliferative activity for development of distant metastases in breast cancer was analysed, and the relative contribution of these two risk factors was quantified. A detailed quantitative comparison was performed between Ki67 and cyclin A as proliferative markers. The frequency of Ki67 and cyclin A-positive cells was scored in the same microscopic areas in 428 breast tumours. The frequency of Ki67-positive cells was found to be highly correlated with the frequency of cyclin A-positive cells, and both proliferation markers were equally good to predict risk of distant metastases. The relative contribution of degree of aneuploidy and proliferative activity as risk markers for developing distant metastases was studied independently. Although increased proliferative activity in general was associated with an increased risk of developing distant metastases, ploidy level was found to be an independent and even stronger marker when considering the group of small (T1) node negative tumours. By combining proliferative activity and ploidy level, a large group of low risk breast tumours (39%) could be identified in which only a few percentage of the tumours (5%) developed distant metastases during the 9-year follow-up time period.

Which cyclin E prevails as prognostic marker for breast cancer? Results from a retrospective study involving 635 lymph node-negative breast cancer patients

PURPOSE

To evaluate the prognostic value of cyclin E with a quantitative method for lymph node-negative primary breast cancer patients.

PATIENTS AND METHODS

mRNA transcripts of full-length and splice variants of cyclin E1 (CCNE1) and cyclin E2 (CCNE2) were measured by real-time PCR in frozen tumor samples from 635 lymph node-negative breast cancer patients who had not received neoadjuvant or adjuvant systemic therapy.

RESULTS

None of the PCR assays designed for the specific splice variants of the cyclins gave additional prognosis-related information compared with the common assays able to detect all variants. In Cox multivariate analysis, corrected for the traditional prognostic factors, high levels of cyclin E were independently associated with a short distant metastasis-free survival [hazard ratio (HR), 3.40; P < 0.001 for CCNE1 and HR, 1.76; P < 0.001 for CCNE2, respectively]. After dichotomizing the tumors at the median level of 70% tumor cells, the multivariate analysis showed particularly strong results for CCNE1 in the group of 433 patients with stroma-enriched primary tumors (HR, 5.12; P < 0.001). In these tumors, the worst prognosis was found for patients with estrogen receptor-negative tumors expressing high CCNE1 (HR, 9.89; P < 0.001) and for patients with small (T1) tumors expressing high CCNE1 (HR, 8.47; P < 0.001).

CONCLUSION

Our study shows that both CCNE1 and CCNE2 qualify as independent prognostic markers for lymph node-negative breast cancer patients, and that CCNE1 may provide additional information for specific subgroups of patients.

Ki67 and cyclin A as prognostic factors in early breast cancer. What are the optimal cut-off values?

AIMS

To find the optimal cut-off values for cyclin A and Ki67 in early breast cancer tumours and to evaluate their prognostic values.

METHODS AND RESULTS

Tissue microarray (TMA) slides were constructed from 570 T1-4 N0-1 M0 breast cancer tumours. The TMA slides were stained for cyclin A and Ki67 using immunohistochemistry with commercial antibodies. To investigate the optimal cut-off values for cyclin A, Ki67 average and maximum values the material was split into two parts at cut-offs defined by dividing it into deciles. For each cut-off value the relative risk (RR) for metastasis-free survival (MFS) and overall survival (OS) was calculated comparing patients with high versus low cyclin A or Ki67 expression. When using a cut-off value around the seventh decile, cyclin A and Ki67 score correlated with the highest RR ratio for MFS in the chemotherapy-naïve subgroup. Among patients having received adjuvant chemotherapy, no statistically significant differences in MFS or OS were found.

CONCLUSIONS

The optimal cut-off value for cyclin A average is 8% and for cyclin A maximum value 11%; for Ki67 the corresponding values are 15% and 22%. Additional studies are needed to verify these results.

Nuclear cyclin B1 in human breast carcinoma as a potent prognostic factor

Cyclin B1 is translocated to the nucleus from the cytoplasm, and plays an essential role in cell proliferation through promotion of mitosis. Although overexpression of cyclin B1 was previously reported in breast carcinomas, the biological significance of the intracellular localization of cyclin B1 remains unclear. Therefore, in this study, we examined cyclin B1 immunoreactivity in 109 breast carcinomas, according to the intracellular localization, that is, nucleus, cytoplasm or total (nucleus or cytoplasm). Total cyclin B1 was detected in carcinoma cells in 42% of breast carcinomas examined, whereas nuclear and cytoplasmic cyclin B1 were positive in 17 and 35% of the cases, respectively. Total or cytoplasmic cyclin B1 were positively associated with histological grade, mitosis, Ki-67, p53, c-myc or 14-3-3sigma, and inversely correlated with estrogen or progesterone receptor. Nuclear cyclin B1 was significantly associated with tumor size, lymph node metastasis, histological grade, mitosis, Ki-67 or polo-like kinase 1. Only nuclear cyclin B1 was significantly associated with adverse clinical outcome of the patients, and multivariate analyses of disease-free and overall survival demonstrated nuclear cyclin B1 as the independent marker. A similar tendency was detected in the patients receiving adjuvant therapy after surgery. These results suggest that an onocogenic role of overexpressed cyclin B1 is mainly mediated in nuclei of breast carcinoma cells, and the nuclear translocation is regulated by polo-like kinase 1 and 14-3-3sigma. Nuclear cyclin B1-positive breast carcinoma is resistant to adjuvant therapy, and nuclear cyclin B1 immunoreactivity is a potent prognostic factor in breast carcinoma patients.

Measuring proliferation in breast cancer: practicalities and applications

Various methods are available for the measurement of proliferation rates in tumours, including mitotic counts, estimation of the fraction of cells in S-phase of the cell cycle and immunohistochemistry of proliferation-associated antigens. The evidence, advantages and disadvantages for each of these methods along with other novel approaches is reviewed in relation to breast cancer. The potential clinical applications of proliferative indices are discussed, including their use as prognostic indicators and predictors of response to systemic therapy.

Genomic analysis of the 8p11-12 amplicon in familial breast cancer

Amplification of 8p11-12 has been recurrently reported in sporadic breast cancer. These studies define a complex molecular structure with a set of minimal amplified regions, and different putative oncogenes that show a strong correlation between amplification and over-expression such as ZNF703/FLJ14299, SPFH2/C8orf2, BRF2 and RAB11FIP. However, none of these studies were carried out on familial breast malignancies. We have studied the incidence, molecular features and clinical value of this amplification in familial breast tumors associated with BRCA1, BRCA2 and non-BRCA1/2 gene mutations. We detected 9 out of 80 familial tumors with this amplicon by chromosomal comparative genomic hybridization. Next, we used a high-resolution comparative genomic hybridization array covering the 8p11-12 region to characterize this chromosomal region. This approach allowed us to define 2 cores of common amplification that largely overlap with those reported in sporadic tumors. Our findings confirm the molecular complexity of this chromosomal region and indicate that this genomic event is a common alteration in breast cancer, present not only in sporadic but also in familial tumors. Finally, we found correlation between the 8p11-12 amplification and proliferation (Ki-67) and cyclin E expression, which further proves in familial tumors the poor prognosis association previously reported in sporadic breast cancer.

Reliability of cyclin A assessment on tissue microarrays in breast cancer compared to conventional histological slides

Cyclin A has in some studies been associated with poor breast cancer survival, although all studies have not confirmed this. Its prognostic significance in breast cancer needs evaluation in larger studies. Tissue microarray (TMA) technique allows a simultaneous analysis of large amount of tumours on a single microscopic slide. This makes a rapid screening of molecular markers in large amount of tumours possible. Because only a small tissue sample of each tumour is punched on an array, the question has arisen about the representativeness of TMA when studying markers that are expressed in only a small proportion of cells. For this reason, we wanted to compare cyclin A expression on TMA and on traditional large sections. Two breast cancer TMAs were constructed of 200 breast tumours diagnosed between 1997–1998. TMA slides and traditional large section slides of these 200 tumours were stained with cyclin A antibody and analysed by two independent readers. The reproducibility of the two readers’ results was good or even very good, with kappa values 0.71–0.87. The agreement of TMA and large section results was good with kappa value 0.62–0.75. Cyclin A overexpression was significantly (P<0.001) associated with oestrogen receptor and progesterone receptor negativity and high grade both on TMA and large sections. Cyclin A overexpression was significantly associated with poor metastasis-free survival both on TMA and large sections. The relative risks for metastasis were similar on TMA and large sections. This study suggests that TMA technique could be useful to study histological correlations and prognostic significance of cyclin A on breast cancer on a large scale.

FADD phosphorylation is critical for cell cycle regulation in breast cancer cells

Anti-oestrogen therapy is effective for control of hormone receptor-positive breast cancers, although the detailed molecular mechanisms, including signal transduction, remain unclear. We demonstrated here that long-term tamoxifen treatment causes G2/M cell cycle arrest through c-jun N-terminal kinase (JNK) activation, which is dependent on phosphorylation of Fas-associated death domain-containing protein (FADD) at 194 serine in an oestrogen (ER) receptor-positive breast cancer cell line, MCF-7. Expression of a dominant negative mutant form of MKK7, a kinase upstream of JNK, or mutant FADD (S194A) in MCF-7 cells suppressed the cytotoxicity of long-term tamoxifen treatment. Of great interest, similar signallings could be evoked by paclitaxel, even in an ER-negative cell line, MDA-MB-231. In addition, immunohistochemical analysis using human breast cancer specimens showed a close correlation between phosphorylated JNK and FADD expression, both being significantly reduced in cases with metastatic potential. We conclude that JNK-mediated phosphorylation of FADD plays an important role in the negative regulation of cell growth and metastasis, independent of the ER status of a breast cancer, so that JNK/FADD signals might be promising targets for cancer therapy.

Cyclin E overexpression obstructs infiltrative behavior in breast cancer: a novel role reflected in the growth pattern of medullary breast cancers

Cell cycle deregulation is a prerequisite in tumor development and overexpression of cyclin E, a major G1-S regulator, is often observed in breast cancer and is further linked to poor prognosis. By overexpressing cyclin E in a retinoblastoma-inactivated breast cancer cell line, we induced significant alterations in the expression of genes associated with proliferation and cell adhesion. Rearrangements of the actin cytoskeleton in addition to increased adhesive properties, decreased motility, and invasive potential in functional assays, indicated an overall abrogated mobility. Consistent in vivo findings were obtained upon investigation of 985 primary breast cancers, where cyclin E-high tumors predominantly (67%) displayed a low infiltrative, pushing growth pattern. Furthermore, medullary breast cancers, a subtype defined by its pushing, delimited growth, exhibited a remarkable frequency of cyclin E deregulation (87%) compared with other histologic subtypes (5-20%). Taken together, our results suggest the novel role of cyclin E in modeling infiltrative behavior. The consequences of cyclin E overexpression in breast cancer seems to be multiple, including effects on proliferation as well as growth patterns, a scenario that is indeed observed in the archetype of cyclin E-overexpressing medullary breast cancers.