The catalytic class I(A) PI3K isoforms play divergent roles in breast cancer cell migration

Transforming growth factor-β (TGFβ) plays an important role in breast cancer metastasis. Here phosphoinositide 3-kinase (PI3K) signalling was found to play an essential role in the enhanced migration capability of fibroblastoid cells (FibRas) derived from normal mammary epithelial cells (EpH4) by transduction of oncogenic Ras (EpRas) and TGFβ1. While expression of the PI3K isoform p110δ was down-regulated in FibRas cells, there was an increase in the expression of p110α and p110β in the fibroblastoid cells. The PI3K isoform p110β was found to specifically contribute to cell migration in FibRas cells, while p110α contributed to the response in EpH4, EpRas and FibRas cells. Akt, a downstream targets of PI3K signalling, had an inhibitory role in the migration of transformed breast cancer cells, while Rac, Cdc42 and the ribosomal protein S6 kinase (S6K) were necessary for the response. Together our data reveal a novel specific function of the PI3K isoform p110β in the migration of cells transformed by oncogenic H-Ras and TGF-β1.

Role of KCNMA1 in breast cancer

KCNMA1 encodes the α-subunit of the large conductance, voltage and Ca(2+)-activated (BK) potassium channel and has been reported as a target gene of genomic amplification at 10q22 in prostate cancer. To investigate the prevalence of the amplification in other human cancers, the copy number of KCNMA1 was analyzed by fluorescence-in-situ-hybridization (FISH) in 2,445 tumors across 118 different tumor types. Amplification of KCNMA1 was restricted to a small but distinct fraction of breast, ovarian and endometrial cancer with the highest prevalence in invasive ductal breast cancers and serous carcinoma of ovary and endometrium (3-7%). We performed an extensive analysis on breast cancer tissue microarrays (TMA) of 1,200 tumors linked to prognosis. KCNMA1 amplification was significantly associated with high tumor stage, high grade, high tumor cell proliferation, and poor prognosis. Immunofluorescence revealed moderate or strong KCNMA1 protein expression in 8 out of 9 human breast cancers and in the breast cancer cell line MFM223. KCNMA1-function in breast cancer cell lines was confirmed by whole-cell patch clamp recordings and proliferation assays, using siRNA-knockdown, BK channel activators such as 17ß-estradiol and the BK-channel blocker paxilline. Our findings revealed that enhanced expression of KCNMA1 correlates with and contributes to high proliferation rate and malignancy of breast cancer.

Inhibition of the AKT/mTOR and erbB pathways by gefitinib, perifosine and analogs of gonadotropin-releasing hormone I and II to overcome tamoxifen resistance in breast cancer cells

Endocrine resistance in breast cancer remains a major clinical problem and is caused by crosstalk mechanisms of growth factor receptor cascades, such as the erbB and PI3K/AKT pathways. The possibilities a single breast cancer cell has to achieve resistance are manifold. We developed a model of 4-hydroxy-tamoxifen (OHT)‑resistant human breast cancer cell lines and compared their different expression patterns, activation of growth factor receptor pathways and compared cells by genomic hybridization (CGH). We also tested a panel of selective inhibitors of the erbB and AKT/mTOR pathways to overcome OHT resistance. OHT‑resistant MCF-7-TR and T47D-TR cells showed increased expression of HER2 and activation of AKT. T47D-TR cells showed EGFR expression and activated MAPK (ERK-1/2), whereas in resistant MCF-7-TR cells activated AKT was due to loss of CTMP expression. CGH analyses revealed remarkable aberrations in resistant sublines, which were predominantly depletions. Gefitinib inhibited erbB signalling and restored OHT sensitivity in T47D-TR cells. The AKT inhibitor perifosine restored OHT sensitivity in MCF-7-TR cells. All cell lines showed expression of receptors for gonadotropin-releasing hormone (GnRH) I and II, and analogs of GnRH-I/II restored OHT sensitivity in both resistant cell lines by inhibition of erbB and AKT signalling. In conclusion, mechanisms to escape endocrine treatment in breast cancer share similarities in expression profiling but are based on substantially different genetic aberrations. Evaluation of activated mediators of growth factor receptor cascades is helpful to predict response to specific inhibitors. Expression of GnRH-I/II receptors provides multi-targeting treatment strategies.

Prolactin upregulates sphingosine kinase-1 expression and activity in the human breast cancer cell line MCF7 and triggers enhanced proliferation and migration

Sphingosine kinases (SK) catalyze the formation of sphingosine-1-phosphate (S1P) which plays a crucial role in cell growth and survival. Here, we show that prolactin (PRL) biphasically activates the SK-1, but not the SK-2 subtype, in the breast adenocarcinoma cell-line MCF7. A first peak occurs after minutes of stimulation and is followed by a second delayed activation after hours of stimulation. A similar biphasic effect on SK-1 activity is seen for 17beta-estradiol (E(2)). The delayed activation of SK-1 derives from an upregulated mRNA and protein expression and is due to increased SK-1 promoter activity and mechanistically involves STAT5 activation as well as protein kinase C and the classical mitogen-activated protein kinases. Furthermore, glucocorticoids also block both hormone-induced SK-1 expression and activity. Functionally, long-term stimulation of MCF7 cells with PRL or E(2) is well known to trigger increased cell proliferation and migration. Both hormone-induced cell responses critically involve SK-1 activation since the depletion of SK-1, but not SK-2, by siRNA transfection abolishes the hormone-induced cell proliferation and migration. In summary, our data show that PRL and E(2) cause a pronounced delayed SK-1 activation which is due to increased gene transcription, and critically determines the capability of cells to grow and move. Thus, the SK-1 may represent a novel attractive target for anti-tumor therapy.

Effects of epidermal growth factor on the invasion activity of the oral cancer cell lines HSC3 and SAS

Epidermal growth factor (EGF) is excreted in a high concentration in human saliva and modulates the growth and differentiation of various cancer cells. To elucidate the molecular mechanisms by which EGF affects oral cancer growth and invasion, we analyzed the Matrigel invasion activity of the cultured oral cancer cell line. Cells grown under the influence of EGF were subjected to Matrigel invasion assays and cells grown in the absence of EGF were used as controls. Gelatin-zymography and Northern blot analyses quantified the invasiveness and tumorigenicity. Chloramphenicol acetyltransferase assay (CAT assay) determined the EGF stimulation of matrix metalloproteinase (MMP) expression. EGF increased the number of cells penetrating a Matrigel membrane. Gelatin-zymography and Northern blot analysis revealed that MMP9 and Ets1 expressions correlated with EGF but MMP2 was not changed. a transient transfection assay revealed that EGF increased the promoter activities of the MMP9 genes in HSC3 and SAS cells. These results suggest that EGF increases the invasion activity of oral cancer cells partly by increasing MMP9.

Insulin, CCAAT/enhancer-binding proteins and lactate regulate the human 11β-hydroxysteroid dehydrogenase type 2 gene expression in colon cancer cell lines.

11β-Hydroxysteroid dehydrogenases (11beta-HSD) modulate mineralocorticoid receptor transactivation by glucocorticoids and regulate access to the glucocorticoid receptor. The isozyme 11beta-HSD2 is selectively expressed in mineralocorticoid target tissues and its activity is reduced in various disease states with abnormal sodium retention and hypertension, including the apparent mineralocorticoid excess. As 50% of patients with essential hypertension are insulin resistant and hyperinsulinemic, we hypothesized that insulin downregulates the 11beta-HSD2 activity. In the present study we show that insulin reduced the 11beta-HSD2 activity in cancer colon cell lines (HCT116, SW620 and HT-29) at the transcriptional level, in a time and dose dependent manner. The downregulation was reversible and required new protein synthesis. Pathway analysis using mRNA profiling revealed that insulin treatment modified the expression of the transcription factor family C/EBPs (CCAAT/enhancer-binding proteins) but also of glycolysis related enzymes. Western blot and real time PCR confirmed an upregulation of C/EBP beta isoforms (LAP and LIP) with a more pronounced increase in the inhibitory isoform LIP. EMSA and reporter gene assays demonstrated the role of C/EBP beta isoforms in HSD11B2 gene expression regulation. In addition, secretion of lactate, a byproduct of glycolysis, was shown to mediate insulin-dependent HSD11B2 downregulation. In summary, we demonstrate that insulin downregulates HSD11B2 through increased LIP expression and augmented lactate secretion. Such mechanisms are of interest and potential significance for sodium reabsorption in the colon.

The ceramide kinase inhibitor NVP-231 inhibits breast and lung cancer cell proliferation by inducing M phase arrest and subsequent cell death

Background and Purpose Ceramide kinase (CerK) catalyzes the generation of ceramide-1-phosphate which may regulate various cellular functions, including inflammatory reactions and cell growth. Here, we studied the effect of a recently developed CerK inhibitor, NVP-231, on cancer cell proliferation and viability and investigated the role of cell cycle regulators implicated in these responses. Experimental Approach The breast and lung cancer cell lines MCF-7 and NCI-H358 were treated with increasing concentrations of NVP-231 and DNA synthesis, colony formation and cell death were determined. Flow cytometry was performed to analyse cell cycle distribution of cells and Western blot analysis was used to detect changes in cell cycle regulator expression and activation. Key Results In both cell lines, NVP-231 concentration-dependently reduced cell viability, DNA synthesis and colony formation. Moreover it induced apoptosis, as measured by increased DNA fragmentation and caspase-3 and caspase-9 cleavage. Cell cycle analysis revealed that NVP-231 decreased the number of cells in S phase and induced M phase arrest with an increased mitotic index, as determined by increased histone H3 phosphorylation. The effect on the cell cycle was even more pronounced when NVP-231 treatment was combined with staurosporine. Finally, overexpression of CerK protected, whereas down-regulation of CerK with siRNA sensitized, cells for staurosporine-induced apoptosis. Conclusions and Implications Our data demonstrate for the first time a crucial role for CerK in the M phase control in cancer cells and suggest its targeted inhibition, using drugs such as NVP-231, in combination with conventional pro-apoptotic chemotherapy.

Cathepsin D specifically cleaves the chemokines macrophage inflammatory protein-1 alpha, macrophage inflammatory protein-1 beta, and SLC that are expressed in human breast cancer

Cathepsin D (Cath-D) expression in human primary breast cancer has been associated with a poor prognosis. In search of a better understanding of the Cath-D substrates possibly involved in cancer invasiveness and metastasis, we investigated the potential interactions between this protease and chemokines. Here we report that purified Cath-D, as well as culture supernatants from the human breast carcinoma cell lines MCF-7 and T47D, selectively degrade macrophage inflammatory protein (MIP)-1 alpha (CCL3), MIP-1 beta (CCL4), and SLC (CCL21). Proteolysis was totally blocked by the protease inhibitor pepstatin A, and specificity of Cath-D cleavage was demonstrated using a large chemokine panel. Whereas MIP-1 alpha and MIP-1 beta degradation was rapid and complete, cleavage of SLC was slow and not complete. Mass spectrometry analysis showed that Cath-D cleaves the Leu(58) to Trp(59) bond of SLC producing two functionally inactive fragments. Analysis of Cath-D proteolysis of a series of monocyte chemoattractant protein-3/MIP-1 beta hybrids indicated that processing of MIP-1 beta might start by cleaving off amino acids located in the C-terminal domain. In situ hybridization studies revealed MIP-1 alpha, MIP-1 beta, and Cath-D gene expression mainly in the stromal compartment of breast cancers whereas SLC transcripts were found in endothelial cells of capillaries and venules within the neoplastic tissues. Cath-D production in the breast carcinoma cell lines MCF-7 and T47D, as assessed by enzyme-linked immunosorbent assay of culture supernatants and cell lysates, was not affected by stimulation with chemokines such as interleukin-8 (CXCL8), SDF-1 (CXCL12), and SLC. These data suggest that inactivation of chemokines by Cath-D possibly influences regulatory mechanisms in the tumoral extracellular microenvironment that in turn may affect the generation of the antitumoral immune response, the migration of cancer cells, or both processes.

Synthesis and cellular characterization of novel isoxazolo- and thiazolohydrazinylidene-chroman-2,4-diones on cancer and non-cancer cell growth and death

Coumarins are extensively studied anticoagulants that exert additional effects such as anticancerogenic and even anti-inflammatory. In order to find new drugs with anticancer activities, we report here the synthesis and the structural analysis of new coumarin derivatives which combine the coumarin core and five member heterocycles in hydrazinylidene-chroman-2,4-diones. The derivatives were prepared by derivatization of the appropriate heterocyclic amines which were used as electrophiles to attack the coumarin ring. The structures were characterized by spectroscopic techniques including IR, NMR, 2D-NMR and MS. These derivatives were further characterized especially in terms of a potential cytotoxic and apoptogenic effect in several cancer cell lines including the breast and prostate cancer cell lines MCF-7, MDA-MB-231, PC-3, LNCaP, and the monocytic leukemia cell line U937. Cell viability was determined after 48 h and 72 h of treatment with the novel compounds by MTT assay and the 50% inhibitory concentrations (EC50 values) were determined. Out of the 8 novel compounds screened for reduced cell viability, 4c, 4d and 4e were found to be the most promising and effective ones having EC50 values that were several fold reduced when compared to the reference substance 4-hydroxycoumarin. However, the effects were cancer cell line dependent. The breast cancer MDA-MB-231 cells, the prostate cancer LNCaP cells, and U937 cells were most sensitive, MCF-7 cells were less sensitive, and PC-3 cells were more resistant. Reduced cell viability was accompanied by increased apoptosis as shown by PARP-1 cleavage and reduced activity of the survival protein kinase Akt. In summary, this study has identified three novel coumarin derivatives that in comparison to 4-hydroxycoumarin have a higher efficiency to reduce cancer cell viability and trigger apoptosis and therefore may represent interesting novel drug candidates

The multifaceted roles of Eph/ephrin signaling in breast cancer

http://www.ncbi.nlm.nih.gov/pubmed/22568950

High NRBP1 expression in prostate cancer is linked with poor clinical outcomes and increased cancer cell growth

We recently established the rationale that NRBP1 (nuclear receptor binding protein 1) has a potential growth-promoting role in cell biology. NRBP1 interacts directly with TSC-22, a potential tumor suppressor gene that is differently expressed in prostate cancer. Consequently, we analyzed the role of NRBP1 expression in prostate cancer cell lines and its expression on prostate cancer tissue microarrays (TMA).

Doxorubicin Affects Expression of Proteins of Neuronal Pathways in MCF-7 Breast Cancer Cells.

In the present article, we report on the semi-quantitative proteome analysis and related changes in protein expression of the MCF-7 breast cancer cell line following treatment with doxorubicin, using the precursor acquisition independent from ion count (PAcIFIC) mass spectrometry method. PAcIFIC represents a cost-effective and easy-to-use proteomics approach, enabling for deep proteome sequencing with minimal sample handling. The acquired proteomic data sets were searched for regulated Reactome pathways and Gene Ontology annotation terms using a new algorithm (SetRank). Using this approach, we identified pathways with significant changes (≤0.05), such as chromatin organization, DNA binding, embryo development, condensed chromosome, sequence-specific DNA binding, response to oxidative stress and response to toxin, as well as others. These sets of pathways are already well-described as being susceptible to chemotherapeutic drugs. Additionally, we found pathways related to neuron development, such as central nervous system neuron differentiation, neuron projection membrane and SNAP receptor activity. These later pathways might indicate biological mechanisms on the molecular level causing the known side-effect of doxorubicin chemotherapy, characterized as cognitive impairment, also called 'chemo brain'. Mass spectrometry data are available via ProteomeXchange with identifier PXD002998.

Extensive extranodal metastases of basal-like breast cancer with predominant myoepithelial spindle cell differentiation

A differentiation towards myoepithelial cells has been demonstrated in several types of lesions in the breast. These include multifocal myoepitheliomatosis, the rare mixed tumor or pleomorphic adenoma, adenoid cystic carcinoma, adenomyoepithelioma and myoepithelial carcinoma (malignant myoepithelioma). Myoepithelial carcinoma is the only lesion purely composed of myoepithelial cells. All these tumors are benign and/or of low-grade malignancy, with the exception of malignant myoepithelioma. In contrast to the statement of the current World Health Organization (WHO), recent studies have reported that regional and distant metastases may occur in about 50% of pure myoepithelial carcinomas. The presented case of a breast carcinoma with dominant myoepithelial/spindle cell differentiation in a 58-year-old woman is an excellent example to document the highly aggressive biological behavior of this tumor phenotype. Despite an extensive chemotherapy and radiotherapy, the tumor was rapidly progressive, forming a finally exulcerating local tumor relapse and widespread metastases to the myocardium, lungs, liver, kidneys and skin. Similarities in morphology and biological behavior compared to patients with "triple-negative" (hormone receptor and Her2) monophasic sarcomatoid carcinomas and pure spindle cell sarcomas are discussed.

Cardiovascular complications of conventional and targeted adjuvant breast cancer therapy

Adjuvant therapy has improved the survival of women with early breast cancer (BC). Meta-analyses suggest that anthracycline-based regimens reduced the annual BC death rate by 40% in women below the age of 50 and 20% in older women. Novel agents designed to modulate abnormal growth factor signaling in and around the BC cell further increase patients' chances of survival. However, both conventional chemotherapeutic agents as well as some of the novel signaling inhibitors can induce important cardiovascular side-effects, potentially attenuating the progress made in recent years. The mechanism of cancer drug-induced cardiovascular complications varies greatly with some compounds inducing irreversible myocardial cell damage, while others lead to temporary cell dysfunction. The challenge of the future will be to prospectively discriminate between irreversible damage which can lead to progressive cardiovascular disease and reversible cardiovascular dysfunctions without further prognostic implications. Since adjuvant therapy for BC is potentially curative, emphasis must be placed on finding treatments combining maximum efficacy with the minimum of long-term side-effects in order to achieve survival with preserved quality of life.

Tumor lymphangiogenesis and metastasis to lymph nodes induced by cancer cell expression of podoplanin

The membrane glycoprotein podoplanin is expressed by several types of human cancers and might be associated with their malignant progression. Its exact biological function and molecular targets are unclear, however. Here, we assessed the relevance of tumor cell expression of podoplanin in cancer metastasis to lymph nodes, using a human MCF7 breast carcinoma xenograft model. We found that podoplanin expression promoted tumor cell motility in vitro and, unexpectedly, increased tumor lymphangiogenesis and metastasis to regional lymph nodes in vivo, without promoting primary tumor growth. Importantly, high cancer cell expression levels of podoplanin correlated with lymph node metastasis and reduced survival times in a large cohort of 252 oral squamous cell carcinoma patients. Based on comparative transcriptional profiling of tumor xenografts, we identified endothelin-1, villin-1, and tenascin-C as potential mediators of podoplanin-induced tumor lymphangiogenesis and metastasis. These unexpected findings identify a novel mechanism of tumor lymphangiogenesis and metastasis induced by cancer cell expression of podoplanin, suggesting that reagents designed to interfere with podoplanin function might be developed as therapeutics for patients with advanced cancer.