Molecular biology of breast cancer metastasis. Genetic regulation of human breast carcinoma metastasis

Distinct expression and function of breast cancer metastasis suppressor 1 in mutant P53 glioblastoma

PURPOSE

Glioblastoma (GBM) is the most malignant subtype of astrocytic tumors with the worst prognosis in all its progressive forms. Breast cancer metastasis suppressor 1 (BRMS1) is a metastasis suppressor gene that controls malignancy in multiple tumors. As yet, however, its clinical and functional significance in mutant P53 GBM remains inconclusive. Here, we attempted to study the importance of BRMS1 in mutant P53 GBM.

METHODS

BRMS1 expression was evaluated in 74 human astrocytoma tissues by qRT-PCR, Western blotting and immunohistochemistry. BRMS1 expression in the astrocytoma tissues was correlated with clinicopathological parameters, the P53 mutation status and BRMS1 downstream targets, and compared with TCGA and NCI-60 datasets. siRNA-mediated knockdown of BRMS1 was performed in selected GBM cell lines to evaluate the functional role of BRMS1.

RESULTS

Our study revealed an enhanced expression of BRMS1 in GBM which was associated with a poor patient survival, and this observation was corroborated by the TCGA dataset. We also found a positive correlation between BRMS1 expression and a mutant P53 status in GBM which was associated with a poor prognosis. In vitro BRMS1 silencing reduced the growth of mutant P53 GBM cells and repressed their colonization and migration/invasion by modulating EGFR-AKT/NF-κB signaling. Transcriptional profiling revealed a positive and negative correlation of uPA and ING4 expression with BRMS1 expression, respectively.

CONCLUSION

Our data indicate upregulation of BRMS1 in high grade astrocytomas which correlates positively with mutant P53 and a poor patient survival. Silencing of BRMS1 in mutant P53 GBM cell lines resulted in a reduced cellular growth and migration/invasion by suppressing the EGFR-AKT/NF-kB signaling pathway. BRMS1 may serve as a predictive biomarker and therapeutic target in mutant P53 GBM.

The Role of Extracellular Matrix Proteins in Breast Cancer

The extracellular matrix is a structure composed of many molecules, including fibrillar (types I, II, III, V, XI, XXIV, XXVII) and non-fibrillar collagens (mainly basement membrane collagens: types IV, VIII, X), non-collagenous glycoproteins (elastin, laminin, fibronectin, thrombospondin, tenascin, osteopontin, osteonectin, entactin, periostin) embedded in a gel of negatively charged water-retaining glycosaminoglycans (GAGs) such as non-sulfated hyaluronic acid (HA) and sulfated GAGs which are linked to a core protein to form proteoglycans (PGs). This highly dynamic molecular network provides critical biochemical and biomechanical cues that mediate the cell–cell and cell–matrix interactions, influence cell growth, migration and differentiation and serve as a reservoir of cytokines and growth factors’ action. The breakdown of normal ECM and its replacement with tumor ECM modulate the tumor microenvironment (TME) composition and is an essential part of tumorigenesis and metastasis, acting as key driver for malignant progression. Abnormal ECM also deregulate behavior of stromal cells as well as facilitating tumor-associated angiogenesis and inflammation. Thus, the tumor matrix modulates each of the classically defined hallmarks of cancer promoting the growth, survival and invasion of the cancer. Moreover, various ECM-derived components modulate the immune response affecting T cells, tumor-associated macrophages (TAM), dendritic cells and cancer-associated fibroblasts (CAF). This review article considers the role that extracellular matrix play in breast cancer. Determining the detailed connections between the ECM and cellular processes has helped to identify novel disease markers and therapeutic targets.

Hypothalamic kisspeptin and kisspeptin receptors: Species variation in reproduction and reproductive behaviours

Kisspeptin, encoded by the KISS1 gene, was first discovered as a potential metastasis suppressor gene. The prepro-kisspeptin precursor is cleaved into shorter mature bioactive peptides of varying sizes that bind to the G protein-coupled receptor GPR54 (=KISS1R). Over the last two decades, multiple types of Kiss and KissR genes have been discovered in mammalian and non-mammalian vertebrate species, but they are remarkably absent in birds. Kiss neuronal populations are distributed mainly in the hypothalamus. The KissRs are widely distributed in the brain, including the hypothalamic and non-hypothalamic regions, such as the hippocampus, amygdala, and habenula. The role of KISS1-KISS1R in humans and Kiss1-Kiss1R in rodents is associated with puberty, gonadal maturation, and the reproductive axis. However, recent gene deletion studies in zebrafish and medaka have provided controversial results, suggesting that the reproductive role of kiss is dispensable. This review highlights the evolutionary history, localisation, and significance of Kiss-KissR in reproduction and reproductive behaviours in mammalian and non-mammalian vertebrates.

The genomic architecture of metastasis in breast cancer: focus on mechanistic aspects, signalling pathways and therapeutic strategies

Breast cancer is a multifactorial, heterogeneous disease and the second most frequent cancer amongst women worldwide. Metastasis is one of the most leading causes of death in these patients. Early-stage or locally advanced breast cancer is limited to the breast or nearby lymph nodes. When breast cancer spreads to farther tissues/organs from its original site, it is referred to as metastatic or stage IV breast cancer. Normal breast development is regulated by specific genes and signalling pathways controlling cell proliferation, cell death, cell differentiation and cell motility. Dysregulation of genes involved in various signalling pathways not only leads to the formation of primary tumour but also to the metastasis as well. The metastatic cascade is represented by a multi-step process including invasion of the local tumour cell followed by its entry into the vasculature, exit of malignant cells from the circulation and ultimately their colonization at the distant sites. These stages are referred to as formation of primary tumour, angiogenesis, invasion, intravasation and extravasation, respectively. The major sites of metastasis of breast cancer are the lymph nodes, bone, brain and lung. Only about 28% five-year survival rate has been reported for stage IV breast cancer. Metastasis is a serious concern for breast cancer and therefore, various therapeutic strategies such as tyrosine kinase inhibitors have been developed to target specific dysregulated genes and various signalling pathways involved in different steps of metastasis. In addition, other therapies like hyperbaric oxygen therapy, RNA interference and CRISPR/Cas9 are also being explored as novel strategies to cure the stage IV/metastatic breast cancer. Therefore, the current review has been compiled with an aim to evaluate the genetic basis of stage IV breast cancer with a focus on the molecular mechanisms. In addition, the therapeutic strategies targeting these dysregulated genes involved in various signalling pathways have also been discussed. Genome editing technologies that can target specific genes in the affected areas by making knock-in and knock-out alternations and thereby bring significant treatment outcomes in breast cancer have also been summarized.

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ) inhibits cancer cell metastasis behavior of TNBC via suppressing EMT and VEGF

Triple-negative breast cancer (TNBC) is highly metastatic and lacks effective therapeutic targets among several subtypes of breast cancer. Cancer metastasis promotes the malignancy of TNBC and is closely related to the poor prognosis of the TNBC patients. We aim to explore novel agents that effectively inhibit cancer metastasis to treat TNBC. In our study, 2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ), a CA-4 analogue, could inhibit cell motility and invasion in MDA-MB-231 cells, and the mechanism is closely associated to the inhibition of epithelial-to-mesenchymal transition (EMT). Meanwhile, SQ significantly inhibited the expression and secretion of vascular endothelial growth factor (VEGF) in MDA-MB-231 cells. Moreover, the conditioned medium from SQ-treated MDA-MB-231 cells significantly inhibited the motility and invasion of human umbilical vein endothelial cells (HUVECs), which was correlated with the inhibition of EMT process in HUVECs. In addition, exogenous application of VEGF reversed the occurrence of EMT in HUVECs which stimulated by conditioned medium from SQ-treated cells. Furthermore, SQ inhibited vasculogenic mimicry (VM) formation in MDA-MB-231 cells, which was associated with VE-cadherin and EphA2 down-regulation. This study indicates that SQ inhibits MDA-MB-231 cell metastasis through suppressing EMT and VEGF, thereby implicating this compound might be a potential therapeutic agent against metastatic TNBC.

Riluzole: Anti-invasive effects on rat prostate cancer cells under normoxic and hypoxic conditions

Anti-invasive effects of riluzole and ranolazine, a neuro-protectant and an anti-anginal drug, respectively, on Mat-LyLu rat prostate cancer (PCa) cells were tested in vitro (a) at non-toxic doses and (b) under both normoxic and hypoxic conditions, the latter common to growing tumours. Tetrodotoxin (TTX) was used as a positive control. Hypoxia had no effect on cell viability but reduced growth at 48 hours. Riluzole (5 μmol/L) or ranolazine (20 μmol/L) had no effect on cell viability or growth under normoxia or hypoxia over 24 hours. Matrigel invasion was not affected by hypoxia but inhibited by TTX, ranolazine and riluzole under a range of conditions. The expression of Nav1.7 mRNA, the prevailing, pro-invasive voltage-gated sodium channel α-subunit (VGSCα), was up-regulated by hypoxia. Riluzole had no effect on Nav1.7 mRNA expression in normoxia but significantly reduced it in hypoxia. VGSCα protein expression in plasma membrane was reduced in hypoxia; riluzole increased it but only under hypoxia. It was concluded (a) that riluzole and ranolazine have anti-invasive effects on rat PCa cells and (b) that Nav1.7 mRNA and protein expression can be modulated by riluzole under hypoxia. Overall, therefore, riluzole and ranolazine may ultimately be "repurposed" as anti-metastatic drugs against PCa.

Essential oil extracted from erythrina corallodendron L. leaves inhibits the proliferation, migration, and invasion of breast cancer cells

Erythrina corallodendron L., a kind of landscape tree, has long been used as a traditional medicine. In this study, the composition of essential oil extracted from the leaves was analysed by GC-MS (gas chromatograph-mass spectrometer), with linalool identified as the main compound. Its cytotoxicity against MDA-MB-231, MCF-7 and HMLE cells was examined by MTT and cloning assays. Transwell and wound-healing assays were used to examine the inhibition of migration and invasion. Western blot, qRT-PCR and immunofluorescence staining were used to measure the mRNA and protein expression of factors related to EMT (snail, slug, E-cadherin, N-cadherin and vimentin). The essential oil of Erythrina corallodendron leaves was found to inhibit the proliferation, migration and invasion of breast cancer cells in a dose-dependent manner. The findings of this study suggest that the essential oil of E. corallodendron leaves may merit further investigation as a potential clinical or adjuvant drug for treating breast cancer migration and invasion.

The role of kisspeptin system in cancer biology

Kisspeptins are a family of neuropeptides that are known to be critical in puberty initiation and ovulation. Apart from that kisspeptin derived peptides (KPs) are also known for their antimetastatic activities in several malignancies. Herein we report recent evidence of the role of kisspeptins in cancer biology and we examine the prospective of targeting the kisspeptin pathways leading to a better prognosis in patients with malignant diseases.

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol reverses EGF-induced cell migration and invasion through down-regulation of MDM2 in breast cancer cell lines

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ), a novel synthesized combretastatin A-4
(CA-4) analogue, is identified as a microtubule inhibitor and has been shown to exert anticancer activity in breast cancer cells. Here, we found that SQ reversed epidermal growth factor (EGF)-induced motility and invasion in breast cancer cell lines by the in vitro Wound healing and Transwell assay. Further studies showed that SQ treatment resulted in inhibitory alteration of EGF-stimulated epithelial-to-mesenchymal transition (EMT) and MMP-2 activity. What is more, SQ significantly inhibited the EGF-induced mouse double minute 2- (MDM2) expression and transcription factor Twist1 expression. In addition, compared with the control cells, MDM2 overexpression up-regulated Twist1 expression and dramatically promoted cell migration and invasion, MDM2 under-expression also down-regulated Twist1 expression and suppressed cell motility and invasion. Taken together, our findings suggest that the inhibitory effects of SQ on migration and invasion were related to the suppression of MDM2 and Twist1 signal axis.

CTLA-4 Genetic Variants (rs11571317 and rs3087243): Role in Susceptibility and Progression of Breast Cancer

Background

Dysfunctional regulation at immune checkpoints may lead to escape of the tumor cells and gives a scope to set in the unresolved Breast cancer (BC). The major anti-tumor retort is cell-mediated response which involves T lymphocytes. CTLA-4 (Cytotoxic T lymphocyte associated protein-4) with immune suppressive function and tolerance is associated with various autoimmune diseases and cancers including BC. The present study deals with CTLA-4 gene selected polymorphisms (rs11571317 C/T and rs3087243G/A) to explore their relation with breast cancer susceptibility and progression in BC patients.

Methods

For the present case-control study, we recruited a total of 570 women which include breast cancer patients and healthy control women from south India. Blood samples were collected, genomic DNA was isolated and genotyped by using PCR-RFLP method, and the data were analysed through suitable statistics.

Results

We observed a significant association of rs11571317 with BC in our study group, where CC genotype showed a three-fold increased risk towards BC and CT genotype to be protective. In-silico analyses strengthened our observation revealing the abolition of SP1 binding site in the CTLA-4 promoter by the mutant allele T. The CTLA-4 rs3087243 polymorphism showed an association not with the susceptibility but towards the tumor progression, where GG genotype was coupled with reduced tumor growth (OR = 0.01) and GA (OR = 6.2), AA (OR = 3.4) with increased tumor growth. The T-G haplotype was found to confer protection against breast cancer risk while C-A (OR = 3.6) and T-A (OR = 15.8) haplotypes were associated with disease progression. In-silico analysis for rs3087243 revealed change in threshold values between reference and variant sequences.

Conclusion

The study suggests varied roles of different polymorphisms of CTLA-4 in the aetiopathogenesis of BC. Understanding the mechanism may help in the CTLA-4 based immunotherapy for BC.

KiSS1 gene as a novel mediator of TGFβ-mediated cell invasion in triple negative breast cancer

The invasive and metastatic phenotypes of breast cancer correlate with high recurrence rates and poor survival outcomes. Transforming growth factor-β (TGFβ) promotes tumor progression and metastasis in aggressive breast cancer. Here, we identified the kisspeptin KiSS1 as a downstream target of canonical TGFβ/Smad2 pathway in triple negative breast cancer cells. We also found KiSS1 expression to be required for TGFβ-induced cancer cell invasion. Indeed, knockdown expression of KiSS1 blocked TGFβ-mediated cancer cell invasion as well as metalloproteinase (MMP9) expression and activity. Interestingly, Kisspeptin-10 (KP-10), the smallest active form of kisspeptin also stimulates cancer cell invasive behavior through activation of MAPK/Erk pathway. We described a positive feedback loop between KiSS1 and p21 downstream of TGFβ, further contributing to TGFβ-induced cancer cell invasion. Lastly, we explored both the clinical utility of KiSS1 as a lymph node involvement predictive tool and its potential as a therapeutic target. We found KiSS1 high expression to correlate with lymph node positive status. Furthermore, blocking KiSS1 using a specific small peptide antagonist (p234) impaired TGFβ-mediated cell invasion and MMP9 induction. Together, our results define an essential role of KiSS1 in regulating TGFβ pro-invasive effects and define KiSS1 as a therapeutic new target for triple negative breast cancer.

Tumor necrosis factor alpha-238G/A polymorphism and risk of breast cancer: An update by meta-analysis

BACKGROUND

The association between the tumor necrosis factor-alpha gene (TNF-a) -238G/A polymorphism and the breast cancer has been analyzed in several studies, but the results have been inconclusive. We then performed a meta-analysis to get a precise estimation of the association.

METHODS

Eight case-control studies with a total of 37,257 cases and 39,564 controls were identified by searching the ISI Web of Knowledge database and the PubMed database up to August 2014.

RESULTS

Overall, no association was found between TNF-alpha-238G/A polymorphism and breast cancer in any of genetic model (additive model OR = 1.06, 95%CI: 0.94-1.21, Pheterogeneity = .02; homozygous model OR = 1.04, 95%CI: 0.83-1.30, Pheterogeneity = .98; dominant model OR = 1.06, 95%CI: 0.92-1.21, Pheterogeneity = .01; recessive model OR = 1.04, 95%CI: 0.83-1.30, Pheterogeneity = .98). Furthermore, no significant association was identified when stratified by ethnicity (Caucasian, Asian).

CONCLUSION

This meta-analysis indicated that the TNF-alpha-238G/A polymorphism is not associated with breast cancer risk in the overall population.

Inherent variability of cancer-specific aneuploidy generates metastases

Background

The genetic basis of metastasis is still unclear because metastases carry individual karyotypes and phenotypes, rather than consistent mutations, and are rare compared to conventional mutation. There is however correlative evidence that metastasis depends on cancer-specific aneuploidy, and that metastases are karyotypically related to parental cancers. Accordingly we propose that metastasis is a speciation event. This theory holds that cancer-specific aneuploidy varies the clonal karyotypes of cancers automatically by unbalancing thousands of genes, and that rare variants form new autonomous subspecies with metastatic or other non-parental phenotypes like drug-resistance – similar to conventional subspeciation.

Results

To test this theory, we analyzed the karyotypic and morphological relationships between seven cancers and corresponding metastases. We found (1) that the cellular phenotypes of metastases were closely related to those of parental cancers, (2) that metastases shared 29 to 96% of their clonal karyotypic elements or aneusomies with the clonal karyotypes of parental cancers and (3) that, unexpectedly, the karyotypic complexity of metastases was very similar to that of the parental cancer. This suggests that metastases derive cancer-specific autonomy by conserving the overall complexity of the parental karyotype. We deduced from these results that cancers cause metastases by karyotypic variations and selection for rare metastatic subspecies. Further we asked whether metastases with multiple metastasis-specific aneusomies are assembled in one or multiple, sequential steps. Since (1) no stable karyotypic intermediates of metastases were observed in cancers here and previously by others, and (2) the karyotypic complexities of cancers are conserved in metastases, we concluded that metastases are generated from cancers in one step – like subspecies in conventional speciation.

Conclusions

We conclude that the risk of cancers to metastasize is proportional to the degree of cancer-specific aneuploidy, because aneuploidy catalyzes the generation of subspecies, including metastases, at aneuploidy-dependent rates. Since speciation by random chromosomal rearrangements and selection is unpredictable, the theory that metastases are karyotypic subspecies of cancers also explains Foulds’ rules, which hold that the origins of metastases are “abrupt” and that their phenotypes are “unpredictable.”

Increased autophagic response in a population of metastatic breast cancer cells

Breast cancer cells are heterogeneous in their ability to invade and fully metastasize, and thus also in their capacity to survive the numerous stresses encountered throughout the multiple steps of the metastatic cascade. Considering the role of autophagy as a survival response to stress, the present study hypothesized that distinct populations of breast cancer cells may possess an altered autophagic capacity that influences their metastatic potential. It was observed that a metastatic breast cancer cell line, MDA-MB-231, that was sensitive to autophagic induction additionally possessed the ability to proliferate following nutrient deprivation. Furthermore, a selected subpopulation of these cells that survived multiple exposures to starvation conditions demonstrated a heightened response to autophagic induction compared to their parent cells. Although this subpopulation maintained a more grape-like pattern in three-dimensional culture compared to the extended spikes of the parent population, autophagic induction in this subpopulation elicited an invasive phenotype with extended spikes. Taken together, these results suggest that autophagic induction may contribute to the ability of distinct breast cancer cell populations to survive and invade.

RECK Gene Polymorphism is Associated with Susceptibility and Prognosis of Wilms' Tumor in Chinese Children

Background

Wilms’ tumor (WT) is the most common malignant renal tumor in children. Previous studies suggested the reversion-inducing, cysteine-rich protein with Kazal motifs (RECK) down-regulation might have a role in numerous human cancers. The current study was done to investigate the associations of RECK single-nucleotide polymorphisms (SNPs) with the WT susceptibility in Chinese children.

Material/Methods

We analyzed 2 SNPs (rs10972727and rs11788747) in a total of 97 WT children and 194 healthy matched controls (1:2 ratio) by real-time PCR and PCR-RFLP genotyping analysis.

Results

We found that the G allele of rs11788747 in the RECK gene was significantly associated with WT in Chinese children (OR=0.7, 95% CI: 0.45–0.99; P=0.042); as with another SNP rs10972727, however, no statistically significant difference was detected. Further analysis showed there was also a statistically significant difference in genotype frequencies between terminal tumor stage (P=0.026) and metastatic groups (P=0.002).

Conclusions

The present data indicate that there is a significant association between mutant G of rs11788747 in RECK and WT risk. G carriers with advanced tumor stage or with metastasis might have an increased risk of WT.

SENP5 mediates breast cancer invasion via a TGFβRI SUMOylation cascade

Identifying novel mechanisms, which are at the core of breast cancer biology, is of critical importance. Such mechanisms may explain response to treatment, reveal novel targets or drive detection assays.

To uncover such novel mechanisms, we used survival analysis on gene expression datasets encompassing 1363 patients. By iterating over the compendia of genes, we screened for their significance as prognosis biomarkers and identified SUMO-specific protease 5 (SENP5) to significantly stratify patients into two survival groups across five unrelated tested datasets. According to these findings, low expression of SENP5 is associated with good prognosis among breast cancer patients.

Following these findings, we analyzed SENP5 silencing and show it is followed by inhibition of anchorage-independence growth, proliferation, migration and invasion in breast cancer cell lines. We further show that these changes are conducted via regulation of TGFβRI levels. These data relate to recent reports about the SUMOylation of TGFβRI. Following TGFβRI changes in expression, we show that one of its target genes, MMP9, which plays a key role in degrading the extracellular matrix and contributes to TGFβ-induced invasion, is dramatically down regulated upon SENP5 silencing.

This is the first report represents SENP5-TGFβ-MMP9 cascade and its mechanistic involvement in breast cancer.

Transforming growth factor-beta signaling leads to uPA/PAI-1 activation and metastasis: a study on human breast cancer tissues

Metastasis represents a major problem in the treatment of patients with advanced primary breast cancer. Both Transforming Growth Factor-Beta (TGF-β) signaling and Plasminogen Activator (PA) components, urokinase-type Plasminogen Activator (uPA) and Plasminogen Activator Inhibitor-1 (PAI-1) represent a complex network crucial for such enhanced invasiveness of tumors and imply high prognostic/predictive and promising therapeutic potential. Therefore, protein expression of specific effector molecules comprising the main parts of the TGF-β signaling pathway were determined in HOPE-fixed human tumor tissues through IHC (Scoring) using tissue microarray (TMA) technique and correlated with respective uPA and PAI-1 levels determined earlier in the same TMAs through optimized IHC and semi-quantitative image analysis. TGF-β signaling was active in vast majority (96 %) of the tumor samples and 88 % of all cases were significantly correlated with established metastasis markers uPA and PAI-1. In addition, TGF-β was also closely associated with tumor size, nodal status and two steroid hormone receptors. Consistent interrelationships between TGF-β, PA components and additional tumor characteristics underline the superiority of such more comprising data with regards to confirming TGF-β signaling as a promising target system to inhibit metastasis in advanced breast cancer.

Expression of RECK and MMP-2 in salivary adenoid cystic carcinoma: Correlation with tumor progression and patient prognosis

Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a glycosylphosphatidylinositol-anchored glycoprotein, inhibits the enzymatic activities of certain matrix metalloproteinases (MMPs). RECK has been studied in numerous human tumors, but the expression of RECK in salivary adenoid cystic carcinoma (SACC), and its correlation with patient prognosis, has never been investigated thus far. In the present study, the expression of RECK and MMP-2 was evaluated in two ACC cell lines and in 83 patients with SACC. The results of quantitative polymerase chain reaction and western blot analysis revealed that the ACC-2 and ACC-M cell lines expressed RECK and MMP-2 mRNA and protein. The immunohistochemical staining in the patients demonstrated that positive expression of RECK and MMP-2 was observed in 21/83 (25.3%) and 69/83 (83.1%) cases, respectively, and that RECK expression was significantly associated with the tumor-node-metastasis stage, histological grade and perineural invasion of patients with SACC (P<0.05). Furthermore, there was a significant association between the positive expression of RECK and that of MMP-2 (P<0.0001). Univariate and multivariate analyses confirmed that a lack of RECK expression was an independent and significant factor for the prediction of a poor prognosis. In conclusion, RECK is a promising prognostic marker and potential therapeutic agent in SACC.

Expression of MiR200a, miR93, metastasis-related gene RECK and MMP2/MMP9 in human cervical carcinoma--relationship with prognosis

AIM AND BACKGROUND

Cervical cancer remains the third most common cancer in women globally after breast and colorectal cancer. Well-characterized biomarkers are necessary for early diagnosis and to predict metastatic progression and effective therapy. MiRNAs can regulate gene expression, cell growth, differentiation and apoptosis by targeting mRNAs for translational repression or degradation in tumor cells. The present study was conducted to assess expression of miR93, miR200a, RECK, MMP2, MMP9 in invasive cervical carcinoma, and analyze their clinical significance.

METHOD

A total of 116 patients with invasive cervical carcinoma and 100 patients undergoing hysterectomy for benign lesions were retrospectively examined. Quantitative real-time PCR was performed to determine expression of miR93 and miR200a while RECK, MMP2, MMP9 and MVD were assessed by immunohistochemical staining.

RESULTS

Cervical carcinoma patients demonstrated up-regulation of miR-93, miR-200a, MMP2 and MMP9, with down-regulation of RECK as compared to benign lesion tissues. RECK was significantly inversely related to invasion and lymphatic metastasis. The 5-year survival rate for patients with strong RECK expression was significantly higher than that with weakly expressing tumors.

CONCLUSION

MiR-93 and miR-200a are associated with metastasis and invasion of cervical carcinoma. Thus together with RECK they are potential prognostic markers for cervical carcinoma. RECK cooperating with MMP2, MMP9 expression is a significant prognostic factor correlated with long-term survival for patients with invasive cervical carcinoma.

Metastasis suppressor genes

Metastasis is a major cause of cancer mortality. Metastasis is a complex process that requires the regulation of both metastasis-promoting and metastasis suppressor genes. The discovery of metastasis suppressor genes contributes significantly to our understanding of metastasis mechanisms and provides prognostic markers and therapeutic targets in clinical cancer management. In this review, we summarize the methods that have been used to identify metastasis suppressors and the potential clinical impact of these genes.

Genomics screens for metastasis genes

Metastasis is responsible for most cancer mortality. The process of metastasis is complex, requiring the coordinated expression and fine regulation of many genes in multiple pathways in both the tumor and host tissues. Identification and characterization of the genetic programs that regulate metastasis is critical to understanding the metastatic process and discovering molecular targets for the prevention and treatment of metastasis. Genomic approaches and functional genomic analyses can systemically discover metastasis genes. In this review, we summarize the genetic tools and methods that have been used to identify and characterize the genes that play critical roles in metastasis.

AIB1 cooperates with ERα to promote epithelial mesenchymal transition in breast cancer through SNAI1 activation

Epithelial Mesenchymal Transition (EMT) plays a major role in cancer metastasis. Several genes have been shown to play a role in EMT, and one of these is Amplified-in-breast cancer 1 (AIB1), which has oncogenic function and is known to be amplified in breast cancer. However, the role of AIB1 in EMT remains largely undefined at the molecular level. In this study, the effect of AIB1 overexpression on the EMT of the breast cancer cell line T47D was investigated. Overexpression of AIB1 disrupted the epithelial morphology of the cells. At the same time, the cells displayed a strong metastasis and reduced level of the epithelial marker E-cadherin. In contrast, knockdown of AIB1 in T47D cells increased cell-cell adhesion and produced weak metastasis, as well as a higher level of E-cadherin expression. We proposed that the regulation of EMT by AIB1 occurred through the action of the transcription factor SNAI1, and demonstrated that such interaction required the participation of ERα and the presence of ERα-binding site on SNAI1 promoter. The expression level of E-cadherin and the extent of cell migration and invasion in SNAI1-knocked down T47D cells that overexpressed AIB1 were similar to those of T47D cells that did not overexpress AIB1 and had no SNAI1 knockdown. Taken together, these results suggested that AIB1 exerted its effect on EMT through its interaction with ERα, which could directly bind to the ERα-binding site on the SNAI1 promoter, allowing the AIB1-ERα complex to promote the transcription of SNAI1 and eventually led to repression of E-cadherin expression, consistent with the loss of E-cadherin being a hallmark of EMT.

Methylated APC and GSTP1 genes in serum DNA correlate with the presence of circulating blood tumor cells and are associated with a more aggressive and advanced breast cancer disease

Background

Tumor-related methylated DNA and circulating tumor cells (CTC) in the peripheral blood might be of prognostic importance in breast cancer. Thus, the aim of our study was to examine free methylated DNA and CTC in the blood from breast cancer patients and to correlate it with clinicopathological features known to influence prognosis.

Materials and methods

We prospectively obtained serum samples from 85 patients with breast cancer and 22 healthy volunteers. Sera were analysed by methylation specific PCR (MethyLight PCR) for five genes: adenomatous polyposis coli (APC), ras association domain family protein 1A (RASSF1A), estrogen receptor 1 (ESR1), CDKN2A (p16) and glutathione s-transferase pi 1 (GSTP1). Beta actin (ACTB) served as control. In parallel matched peripheral blood of 63 patients was used to assay for circulating tumor cells in the peripheral blood by a modified immunomagnetic AdnaTest BreastCancerSelect with PCR detection for EPCAM, MUC1, MGB1 and SPDEF.

Results

We found a hypermethylation in the APC gene in 29% (25/85), in RASSF1A in 26% (22/85), in GSTP1 in 18% (14/76) and in ESR1 in 38% (32/85) of all breast cancer patients. No hypermethylation of CDKN2A was found (0/25). Blood samples of patients were defined CTC positive by detecting the EPCAM 13% (8/63), MUC1 16% (10/63), MGB 9% (5/55), SPDEF 12% (7/58) and in 27% detecting one or more genes (15/55). A significant difference was seen in methylated APC DNA between cancer patients and healthy volunteers. Moreover, methylated APC, RASSF1 and CTC were significantly different in metastatic versus non-metastatic disease. In addition, the presence of methylated APC, RASSF1A and CTC correlated significantly with AJCC-staging (p = 0.001, p = 0.031 and 0.002, respectively). High incidences of methylations were found for the genes RASSF1 and ESR1 in healthy individuals (both 23% 5/22). Methylated GSTP1 was predominantly found in the serum of patients with large primaries (p = 0.023) and was highly significantly correlated with positive Her2/neu status (p = 0.003). Elevated serum CA15.3 was strongly correlated with methylated APC and CTC detection (both p = 0.000). Methylated ESR1 failed to exhibit significant correlations with any of the above mentioned parameters. The presence of CTC in peripheral blood was significantly associated with methylated APC (p = 0.012) and methylated GSTP1 (p = 0.001).

Conclusion

The detection of methylated APC and GSTP1 DNA in serum correlated with the presence of CTC in the blood of breast cancer patients. Both methylated DNA and CTC correlated with a more aggressive tumor biology and advanced disease.

Neurotrophin-3 modulates breast cancer cells and the microenvironment to promote the growth of breast cancer brain metastasis

Metastasis, which remains incompletely characterized at the molecular and biochemical levels, is a highly specific process. Despite the ability of disseminated cancer cells to intravasate into distant tissues, it has been long recognized that only a limited subset of target organs develop clinically overt metastases. Therefore, subsequent adaptation of disseminated cancer cells to foreign tissue microenvironment determines the metastatic latency and tissue tropism of these cells. As a result, studying interactions between the disseminated cancer cells and the adjacent stromal cells will provide a better understanding of what constitutes a favorable or unfavorable microenvironment for disseminated cancer cells in a tissue-specific manner. Previously, we reported a protein signature of brain metastasis showing increased ability of brain metastatic breast cancer cells to counteract oxidative stress. In this study, we showed that another protein from the brain metastatic protein signature, neurotrophin-3 (NT-3), has a dual function of regulating the metastatic growth of metastatic breast cancer cells and reducing the activation of immune response in the brain. More importantly, increased NT-3 secretion in metastatic breast cancer cells results in a reversion of mesenchymal-like (EMT) state to epithelial-like (MET) state and vice versa. Ectopic expression of NT-3 in EMT-like breast cancer cells reduces their migratory ability and increases the expression of HER2 (human epidermal growth factor receptor 2) and E-cadherin at the cell-cell junction. In addition, both endogenous and ectopic expression of NT-3 reduced the number of fully activated cytotoxic microglia. In summary, NT-3 appears to promote growth of metastatic breast cancer cells in the brain by facilitating the re-epithelialization of metastatic breast cancer cells and downmodulating the cytotoxic response of microglia. Most importantly, our results provide new insights into the latency and development of central nervous system macrometastases in patients with HER2-positive breast tumors and provide mechanistic rationale to target HER2 signaling for HER2-positive breast cancer brain metastasis.

Transforming growth factor-1 promotes the transcriptional activation of plasminogen activator inhibitor type 1 in carcinoma-associated fibroblasts

Carcinoma-associated fibroblasts (CAFs) play a pivotal role in promoting the growth, invasion and metastasis of tumor cells. However, to date little is known about the oncogenic mechanisms of CAFs. This study aimed to identify the microenvironmental factors involved in tumor development and progression directed by CAFs in liver metastases. Tissue samples collected from 20 patients with colorectal liver metastases were used in this study. Histological and morphological characterization of the samples was performed using hybridization and immunohistological assays. The mRNA expression of α-smooth muscle actin (α-SMA) was measured by northern blotting. The expression of plasminogen activator inhibitor type 1 (PAI-1) was measured by enzyme-linked immunosorbent assay (ELISA). As a result, co-expression of Thy-1 (CD90) and α-SMA was identified in CAFs, while normal liver samples were negative for α-SMA and Thy-1. Compared with epidermal growth factor (EGF) and tumor necrosis factor (TNF) incubation, the expression of α-SMA increased significantly following transforming growth factor-1 (TGF-1) incubation (P<0.05), while platelet-derived growth factor (PDGF) caused a significant suppression of α-SMA expression (P<0.05). PAI-1 expression was significantly lower in unstimulated fibroblasts compared to TGF-1-treated fibroblasts (P<0.01). The levels of PAI-1 transcription were significantly higher in CAFs from the patient samples compared with the healthy controls. Taken together, our findings suggest that CAFs may be important in migration, matrix degradation, invasion and angiogenesis of tumors, and TGF-1 may promote the activation of PAI-1 transcription in CAFs.

Low expression of RECK indicates a shorter survival for patients with invasive breast cancer

Expression cloning was used to initially isolate the reversion-inducing cysteine-rich protein with Kazal motifs (RECK) gene as a suppressor of transformation. The gene was found to encode a membrane-anchored regulator of MMPs. Experimental studies showed that RECK can suppress tumor invasion, metastasis, and angiogenesis. However, the clinical impact of RECK remains unclear. To assess the clinical significance of RECK expression in invasive breast cancer, a total of 119 patients with invasive breast cancer were retrospectively examined. Expression of RECK in tumor tissues was assessed by immunohistochemical staining. A significant correlation between RECK expression and 5-year survival rate was documented. The 5-year survival rate for patients with strong RECK expression was significantly higher than that for patients with weakly expressing tumors. Univariate and multivariate analyses confirmed that reduced RECK expression was an independent and significant factor in predicting a poor prognosis. In conclusion, RECK expression is a significant prognostic factor correlated with long-term survival for patients with invasive breast cancer. RECK expression is therefore a potentially useful prognostic marker for breast cancer.

VI-14, a novel flavonoid derivative, inhibits migration and invasion of human breast cancer cells

It has been well characterized that flavonoids possess pronounced anticancer potentials including anti-angiogenesis, anti-metastasis, and pro-apoptosis. Herein, we report, for the first time, that VI-14, a novel flavonoid derivative, possesses anti-cancer properties. The purpose of this study is to investigate the anti-migration and anti-invasion activities of VI-14 in breast cancer cells. Our data indicate that VI-14 inhibits adhesion, migration and invasion of MDA-MB-231 and MDA-MB-435 human breast cancer cells. MDA-MB-231 cells treated with VI-14 display reduced activities and expressions of ECM degradation-associated proteins including matrix metalloproteinase 2 (MMP-2) and 9 (MMP-9) at both the protein and mRNA levels. Meanwhile, VI-14 treatment induces an up-regulated expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) and 2 (TIMP-2) in MDA-MB-231 cells. Western blotting results show that phosphorylation levels of critical components of the MAPK signaling pathway, including ERK, JNK and P38, are dramatically decreased in VI-14-treated MDA-MB-231 cells. Furthermore, treatment of VI-14 significantly decreases the nuclear levels and the binding ability of nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1). Taken together, our data suggest that VI-14 treatment suppresses migration and motility of breast cancer cells, and VI-14 may be a potential compound for cancer therapy.

Breast cancer metastatic to the rectum: a case report

INTRODUCTION

Patients with breast cancer may present with systemic recurrence in any organ, primarily the bones, lungs, lymph nodes, liver, pleura, and adrenal glands. We report a case of rectal tumor, metastatic from breast cancer, which represents an unusual location of metastasis.

CASE PRESENTATION

A 74-year-old woman, operated for lobular breast cancer 5 years ago, but not compliant with the annual follow-up, presented with severe constipation and pseudodiarrhea. Digital examination and anoscopy revealed a mass at the lower rectum, 2 cm distant from the anal verge. CT and MRI scan of the abdomen confirmed this finding and did not reveal metastatic lesions elsewhere. The patient underwent abdominoperineal resection.

RESULTS

The postoperative period was uneventful, and the patient was discharged on the 7th postoperative day. The histopathological findings revealed rectal cancer, metastatic from the known invasive lobular breast cancer.

CONCLUSIONS

Rectal metastasis from breast cancer is very rare. The presented case emphasizes the need to keep in mind this possibility and at all times associate the emergency condition with the related history of breast cancer.

Premetastatic niche: ready for new therapeutic interventions?

INTRODUCTION

Bone marrow-derived cells (BMDC) localize in premetastatic niche through chemokines and integrins signals and establish clusters that precede the arrival of even single metastatic tumor cell at distant site. CSCs demonstrate an increased metastatic propensity and would seem likely candidates for the acquisition of migratory capabilities and propagation of heterogeneous tumor cell populations to different target organs. Sonic Hedgehog (SHH), FOXM1 and Notch pathways and signaling molecules such as integrin and chemokine could dictate their fate.

AREAS COVERED

In this review, the molecular mechanisms of premetastatic niche onset are summarized.

EXPERT OPINION

Premetastatic niche is defined as a fertile microenvironment that forms in metastatic target organ and facilitates the invasion, survival and/or proliferation of metastatic tumor cells, providing a novel mechanism for the promotion of metastasis. Drugs targeting premetastatic niche could represent a new promising therapeutic approach in the treatment of bone metastases.

Association of CTLA-4 gene polymorphisms with sporadic breast cancer risk and clinical features in Han women of northeast China

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is an inhibitory molecule that plays a pivotal role in downregulating T-cell mediated immune responses. To determine the role of CTLA-4 in tumor immunity, and to validate previous results as well, we investigated four tag single nucleotide polymorphisms (SNPs) of CTLA-4 in a relatively large Chinese Han cohort from northeastern China. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 581 patients and 566 age-matched controls. Our data indicated that compared with the common genotype and allele of each SNP, the -1722 CC genotype and C allele showed an increased risk of breast cancer (P = 0.030, odds ratio (OR) = 1.457, 95% confidence internal (CI) 1.036-2.051; P = 0.024, OR = 1.214, 95% CI 1.026-1.436, respectively). The -1661 GG genotype and G allele were also associated with an increased risk of breast cancer (P = 0.018, OR = 1.396, 95% CI 1.058-1.843; P = 0.013, OR = 1.353, 95% CI 1.066-1.717, respectively). In the haplotype analysis, the CAAA haplotype showed a higher frequency in cases (P = 0.004), and this association remained significant after correcting the P value for multiple testing. Associations were shown between the SNPs of CTLA-4 and lymph node metastasis, estrogen receptor (ER), progesterone receptor (PR) and P53 statuses. These results indicate that some SNPs in the CTLA-4 gene may affect the risk of breast cancer and show that some SNPs are associated with breast cancer characteristics in Han women in northeastern China.

Trichostatin A reduced phospholipase C gamma-1 transcript and protein contents in MCF-7 breast cancer cells

It has recently been demonstrated that phospholipase C gamma-1 (PLCγ1) activation may contribute to breast carcinoma cell motility and their metastasis. Employing MCF-7 breast cancer cells, we showed the effect of trichostatin A (TSA) on the cellular contents of the PLCγ1 molecule. Using reverse transcription, real-time quantitative PCR and western blot analysis, we demonstrated that TSA reduced the PLCγ1 transcript and protein levels in MCF-7 cells. We also found that TSA decreased the half-life of the PLCγ1 transcript from approximately 7hours to 5hours. Moreover, we observed that protein synthesis appears to be essential in the TSA reduction of PLCγ1 mRNA stability. Since PLCγ1 activation is considered a key factor in the initiation of events that increase malignant cell motility, our observations may support the validity of TSA in anticancer studies.

Matrix metalloproteinase-2 (MMP-2) and MMP-9 expression in invasive ductal carcinoma of the breast

Matrix metalloproteinase-2 (MMP-2) and MMP-9 are gelatinases that play a role in the invasion and metastasis of cancer through the destruction of the basal membrane and extracellular matrix. In this study, we investigated the immunohistochemical expression of MMP-2 and MMP-9 and the correlation between the expression levels and prognostic clinicopathological parameters in 140 patients with invasive ductal carcinoma (IDC). The staining scores for MMP-9 were negative in 21 cases (15%), mild in 27 cases (19%), and strong in 92 cases (66%). MMP-9 expression was increased in high-grade (p=0.001), triple-negative (ER, PR, HER2 negative) (p=0.006), and ER-negative tumors (p=0.004) and tumors with distant metastases (p=0.028). MMP-9 expression was increased in cases with HER2 over-expression/amplification, but no statistically significant difference was found (p=0.215). No correlation was found between lymph node metastasis or tumor size and MMP-9 expression (p=0.492 and p=0.448, respectively). The staining scores for MMP-2 in 140 cases were negative in 10 cases (7%), mild in 25 cases (18%), and strong in 105 cases (75%). MMP-2 expression was increased in ER-negative and high-grade tumors in the lymph node-negative group (p=0.025 and 0.026, respectively). High MMP-9 expression was associated with a shorter disease-free survival and overall survival times (p=0.042 and p=0.046, respectively). In conclusion, increased MMP-9 expression is related to poor prognostic clinicopathological factors in IDC, and hence, it can be utilized as a supplementary prognostic marker. The role of MMP-2 expression in the prognosis of IDC is rather limited.

Normal and disease-related biological functions of Twist1 and underlying molecular mechanisms

This article reviews the molecular structure, expression pattern, physiological function, pathological roles and molecular mechanisms of Twist1 in development, genetic disease and cancer. Twist1 is a basic helix-loop-helix domain-containing transcription factor. It forms homo- or hetero-dimers in order to bind the Nde1 E-box element and activate or repress its target genes. During development, Twist1 is essential for mesoderm specification and differentiation. Heterozygous loss-of-function mutations of the human Twist1 gene cause several diseases including the Saethre-Chotzen syndrome. The Twist1-null mouse embryos die with unclosed cranial neural tubes and defective head mesenchyme, somites and limb buds. Twist1 is expressed in breast, liver, prostate, gastric and other types of cancers, and its expression is usually associated with invasive and metastatic cancer phenotypes. In cancer cells, Twist1 is upregulated by multiple factors including SRC-1, STAT3, MSX2, HIF-1α, integrin-linked kinase and NF-κB. Twist1 significantly enhances epithelial-mesenchymal transition (EMT) and cancer cell migration and invasion, hence promoting cancer metastasis. Twist1 promotes EMT in part by directly repressing E-cadherin expression by recruiting the nucleosome remodeling and deacetylase complex for gene repression and by upregulating Bmi1, AKT2, YB-1, etc. Emerging evidence also suggests that Twist1 plays a role in expansion and chemotherapeutic resistance of cancer stem cells. Further understanding of the mechanisms by which Twist1 promotes metastasis and identification of Twist1 functional modulators may hold promise for developing new strategies to inhibit EMT and cancer metastasis.

Adapter protein SH2B1beta binds filamin A to regulate prolactin-dependent cytoskeletal reorganization and cell motility

Prolactin (PRL) regulates cytoskeletal rearrangement and cell motility. PRL-activated Janus tyrosine kinase 2 (JAK2) phosphorylates the p21-activated serine-threonine kinase (PAK)1 and the Src homology 2 (SH2) domain-containing adapter protein SH2B1β. SH2B1β is an actin-binding protein that cross-links actin filaments, whereas PAK1 regulates the actin cytoskeleton by different mechanisms, including direct phosphorylation of the actin-binding protein filamin A (FLNa). Here, we have used a FLNa-deficient human melanoma cell line (M2) and its derivative line (A7) that stably expresses FLNa to demonstrate that SH2B1β and FLNa are required for maximal PRL-dependent cell ruffling. We have found that in addition to two actin-binding domains, SH2B1β has a FLNa-binding domain (amino acids 200-260) that binds directly to repeats 17-23 of FLNa. The SH2B1β-FLNa interaction participates in PRL-dependent actin rearrangement. We also show that phosphorylation of the three tyrosines of PAK1 by JAK2, as well as the presence of FLNa, play a role in PRL-dependent cell ruffling. Finally, we show that the actin- and FLNa-binding-deficient mutant of SH2B1β (SH2B1β 3Δ) abolished PRL-dependent ruffling and PRL-dependent cell migration when expressed along with PAK1 Y3F (JAK2 tyrosyl-phosphorylation-deficient mutant). Together, these data provide insight into a novel mechanism of PRL-stimulated regulation of the actin cytoskeleton and cell motility via JAK2 signaling through FLNa, PAK1, and SH2B1β. We propose a model for PRL-dependent regulation of the actin cytoskeleton that integrates our findings with previous studies.

Polymorphisms of tumor necrosis factor-alpha and breast cancer risk: a meta-analysis

We conducted a meta-analysis to assess the association between tumor necrosis factor-alpha (TNF-alpha) gene TNFA -308 (G>A), TNFA -238 (G>A), TNFA -857 (C>T), TNFA -863 (C>A), TNFA -1031 (T>C), TNFA -1210 (A>T) polymorphisms and breast cancer(BC) susceptibility. We also performed subgroup analyses based on ethnicity (Caucasian, Asian, and African). An extensive search was performed to identify all case-control studies investigating such association. Thirteen eligible studies, including 10,236 BC patients and 13,143 controls, were identified. No significant association was observed in all genotypes in worldwide populations, but stratification by ethnicity indicated that the TNFA -308 A allele was associated with a decreased risk of BC compared with the G allele in Caucasian individuals (OR = 0.927, 95%CI = 0.879-0.978). Similar results were obtained when the A/A +A/G genotype was compared with the G/G genotype. In addition, meta-analysis results indicated that the A/A genotype of TNFA -308 was a risk factor for BC in African (A/A vs. G/G OR = 4.085 95%CI = 1.460-11.425; A/A vs. G/A OR = 4.861 95%CI = 1.746-13.527; A/A vs. G/A + G/G OR = 4.246 95%CI = 1.551-11.625), but not in Caucasian or Asian individuals. In conclusion, the results of this meta-analysis indicate that the TNFA -308 A allele may be an important protective factor for BC in European individuals, but it is not likely to confer susceptibility to BC in worldwide populations. In addition, the AA genotype of TNFA -308 may be a risk factor for BC in African individuals. Besides, other polymorphisms were not associated with BC susceptibility.

From bench to bedside: the growing use of translational research in cancer medicine

Cancer is responsible for one in eight deaths worldwide, with more than twelve million new cases diagnosed yearly. A large percentage of patients die after developing cancer despite aggressive treatment, indicating a need for new approaches to cancer therapy. The push for development of novel diagnostic and therapeutic agents has allowed translational cancer research to flourish. Genomic and proteomic technologies have generated an enormous amount of information critical to expanding our understanding of cancer biology. New research on the differences between normal and malignant cell biology has paved the way for the development of drugs targeted to specific biological molecules, potentially increasing antitumor efficacy while minimizing the toxicity to the patient that is seen with conventional therapeutics. Current targets in include regulators of cell cycle, angiogenesis, apoptosis, DNA repair, and growth factors and their receptors. Collaboration among researchers, clinicians, and pharmaceutical companies is vital to conducting clinical trials to translate laboratory findings into clinically applicable therapeutics. In this review, we discuss current therapeutic approaches and present an introduction to a wide range of topics undergoing investigation in an effort to highlight the importance of translational research in the development of clinically relevant therapeutic strategies.

Gene expression of circulating tumour cells in breast cancer patients

Background

The diagnostic tools to predict the prognosis in patients suffering from breast cancer (BC) need further improvements. New technological achievements like the gene profiling of circulating tumour cells (CTC) could help identify new prognostic markers in the clinical setting. Furthermore, gene expression patterns of CTC might provide important informations on the mechanisms of tumour cell metastasation.

Materials and methods

We performed realtime-PCR and multiplex-PCR analyses following immunomagnetic separation of CTC. Peripheral blood (PB) samples of 63 patients with breast cancer of various stages were analyzed and compared to a control group of 14 healthy individuals. After reverse-transcription, we performed multiplex PCR using primers for the genes ga733.3, muc-1 and c-erbB2. Mammaglobin1, spdef and c-erbB2 were analyzed applying realtime-PCR.

Results

ga733.2 overexpression was found in 12.7% of breast cancer cases, muc-1 in 15.9%, mgb1 in 9.1% and spdef in 12.1%. In this study, c-erbB2 did not show any significant correlation to BC, possibly due to a highly ambient expression. Besides single gene analyses, gene profiles were additionally evaluated. Highly significant correlations to BC were found in single gene analyses of ga733.2 and muc-1 and in gene profile analyses of ga733.3*muc-1 and GA7 ga733.3*muc-1*mgb1*spdef.

Conclusion

Our study reveals that the single genes ga733.3, muc-1 and the gene profiles ga733.3*muc-1 and ga733.3*3muc-1*mgb1*spdef can serve as markers for the detection of CTC in BC. The multigene analyses found highly positive levels in BC patients. Our study indicates that not single gene analyses but subtle patterns of multiple genes lead to rising accuracy and low loss of specificity in detection of breast cancer cases.

Changes in CpG islands promoter methylation patterns during ductal breast carcinoma progression

Aberrant promoter methylation of several known or putative tumor suppressor genes occurs frequently during carcinogenesis, and this epigenetic change has been considered as a potential molecular marker for cancer. We examined the methylation status of nine genes (APC, CDH1, CTNNB1, TIMP3, ESR1, GSTP1, MGMT, THBS1, and TMS1), by quantitative methylation specific PCR. Synchronous preinvasive lesions (atypical ductal hyperplasia and/or ductal carcinoma in situ) and invasive ductal breast carcinoma from 52 patients, together with pure lesions from 24 patients and 12 normal tissues paired to tumor and 20 normal breast distant from tumor were analyzed. Aberrant promoter methylation was detected in both preinvasive and invasive lesions for genes APC, CDH1, CTNNB1, TIMP3, ESR1, and GSTP1. However, hierarchical mixed model and Generalized Estimating Equations model analyses showed that only APC, CDH1, and CTNNB1 promoter regions showed a higher frequency and methylation levels in pathologic samples when compared with normal breast. Whereas APC and CTNNB1 did not show differences in methylation levels or frequencies, CDH1 showed higher methylation levels in invasive tumors as compared with preinvasive lesions (P < 0.04, Mann-Whitney test with permutation correction). The analysis of APC, CDH1, and CTNNB1 methylation status was able to distinguish between normal and pathologic samples with a sensitivity of 67% (95% confidence interval, 60-71%) and a specificity of 75% (95% confidence interval, 69-81%). Our data point to the direct involvement of APC, CDH1, and CTNNB1 promoter methylation in the early stages of breast cancer progression and suggest that they may represent a useful tool for the detection of tumor cells in clinical specimens.

The steroid receptor coactivator-1 regulates twist expression and promotes breast cancer metastasis

In breast cancer, steroid receptor coactivator-1 (SRC-1) expression positively correlates with HER2 expression and poor prognosis. In mouse mammary tumor virus-polyoma middle T (PyMT) breast cancer mouse model, SRC-1 strongly promotes mammary tumor metastasis. However, the molecular targets and mechanisms that mediate the role of SRC-1 in metastasis are unknown. In this study, SRC-1 wild-type (WT) and knockout (KO) cell lines were developed from the mammary tumors of WT/PyMT and KO/PyMT mice. WT cells exhibited strong migration and invasion capabilities, reduced E-cadherin and beta-catenin epithelial markers, gained N-cadherin and vimentin mesenchymal markers, and formed undifferentiated invasive structures in three-dimensional culture. In contrast, KO cells showed slow migration and invasion, retained E-cadherin, had less N-cadherin and vimentin, and developed partially differentiated three-dimensional structures. Importantly, WT cells expressed Twist, a master regulator of metastasis, at significantly higher levels versus KO cells. SRC-1 knockdown in WT cells reduced Twist expression, whereas SRC-1 restoration in KO cells also rescued Twist expression. Furthermore, SRC-1 was found to coactivate Twist transcription through physical interaction with the transcription factor PEA3 at the proximal Twist promoter. Accordingly, Twist knockdown in WT cells increased E-cadherin and reduced cell invasion and metastasis, and Twist expression in KO cells decreased E-cadherin and increased cell invasion. SRC-1 knockdown in human breast cancer cells also decreased Twist, cell migration, and invasion. Therefore, SRC-1 promotes breast cancer invasiveness and metastasis by coactivating PEA3-mediated Twist expression. Intervention of SRC-1 function may provide new strategies to inhibit breast cancer metastasis.

Id2 promotes the invasive growth of MCF-7 and SKOV-3 cells by a novel mechanism independent of dimerization to basic helix-loop-helix factors

Background

Inhibitor of differentiation 2 (Id2) is a critical factor for cell proliferation and differentiation in normal vertebrate development. Most of the biological function of Id2 has been ascribed to its helix-loop-helix motif. Overexpression of Id2 is frequently observed in various human tumors, but its role for invasion potential in tumor cells is dispute. We aimed to reveal the role of Id2 in invasion potential in poorly invasive and estrogen receptor α (ERα)-positive MCF-7 and SKOV-3 cancer cells.

Methods

MCF-7 and SKOV-3 cells were stably transfected with the wild-type, degradation-resistant full-length or helix-loop-helix (HLH)-deleted Id2, respectively. Protein levels of Id2 and its mutants and E-cadherin were determined by western blot analysis and mRNA levels of Id2 and its mutants were determined by RT-PCR. The effects of Id2 and its mutants on cell proliferation were determined by [³H]-thymidine incorporation assay and the 3- [4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) dye method. The in vitro invasion potential of cells was evaluated by Transwell assay. Cell motility was assessed by scratch wound assay. The promoter activity of E-cadherin was determined by cotransfection and luciferase assays.

Results

Ectopic transfection of the wild-type Id2 markedly increased the protein and mRNA expression of Id2 in MCF-7 and SKOV-3 cells; the protein level but not mRNA level was further increased by transfection with the degradation-resistant Id2 form. The ectopic expression of Id2 or its mutants did not alter proliferation of either MCF-7 or SKOV-3 cells. Transfection of the wild-type Id2 significantly induced the invasion potential and migratory capacity of cells, which was further augmented by transfection with the degradation-resistant full-length or HLH-deleted Id2. E-cadherin protein expression and transactivation of the proximal E-cadherin promoter were markedly suppressed by the degradation-resistant full-length or HLH-deleted Id2 but not wild-type Id2. Ectopic expression of E-cadherin in MCF-7 and SKOV-3 cells only partially blunted the invasion potential induced by the degradation-resistant HLH-deleted Id2.

Conclusion

Overexpression of Id2 in ERα-positive epithelial tumor cells indeed increases the cells' invasive potential through a novel mechanism independent of dimerization to basic helix-loop-helix factors. E-cadherin contributes only in part to Id2-induced cell invasion when Id2 is accumulated to a higher level in some specific cell types.

Correlation between MMPs and their inhibitors in breast cancer tumor tissue specimens and in cell lines with different metastatic potential

Background

The metastatic disease rather than the primary tumor itself is responsible for death in most solid tumors, including breast cancer. The role of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs) and Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) in the metastatic process has previously been established. However, in all published studies only a limited number of MMPs/MMP inhibitors was analyzed in a limited number of cell lines. Here, we propose a more comprehensive approach by analyzing the expression levels of several MMPs (MMP-2, MMP-9 and MMP-14) and MMP inhibitors (TIMP-1, TIMP-2 and RECK) in different models (five human breast cancer cell lines, 72 primary breast tumors and 30 adjacent normal tissues).

Methods

We analyzed the expression levels of MMP-2, MMP-9 and MMP-14 and their inhibitors (TIMP-1, TIMP-2 and RECK) by quantitative RT-PCR (qRT-PCR) in five human breast cancer cell lines presenting increased invasiveness and metastatic potential, 72 primary breast tumors and 30 adjacent normal tissues. Moreover, the role of cell-extracellular matrix elements interactions in the regulation of expression and activity of MMPs and their inhibitors was analyzed by culturing these cell lines on plastic or on artificial ECM (Matrigel).

Results

The results demonstrated that MMPs mRNA expression levels displayed a positive and statistically significant correlation with the transcriptional expression levels of their inhibitors both in the cell line models and in the tumor tissue samples. Furthermore, the expression of all MMP inhibitors was modulated by cell-Matrigel contact only in highly invasive and metastatic cell lines. The enzyme/inhibitor balance at the transcriptional level significantly favors the enzyme which is more evident in tumor than in adjacent non-tumor tissue samples.

Conclusion

Our results suggest that the expression of MMPs and their inhibitors, at least at the transcriptional level, might be regulated by common factors and signaling pathways. Therefore, the multi-factorial analysis of these molecules could provide new and independent prognostic information contributing to the determination of more adequate therapy strategies for each patient.