Normal breast epithelial cells induce apoptosis of breast cancer cells via Fas signaling

Emergence of Cardiac Glycosides as Potential Drugs: Current and Future Scope for Cancer Therapeutics

Cardiac glycosides are natural sterols and constitute a group of secondary metabolites isolated from plants and animals. These cardiotonic agents are well recognized and accepted in the treatment of various cardiac diseases as they can increase the rate of cardiac contractions by acting on the cellular sodium potassium ATPase pump. However, a growing number of recent efforts were focused on exploring the antitumor and antiviral potential of these compounds. Several reports suggest their antitumor properties and hence, today cardiac glycosides (CG) represent the most diversified naturally derived compounds strongly recommended for the treatment of various cancers. Mutated or dysregulated transcription factors have also gained prominence as potential therapeutic targets that can be selectively targeted. Thus, we have explored the recent advances in CGs mediated cancer scope and have considered various signaling pathways, molecular aberration, transcription factors (TFs), and oncogenic genes to highlight potential therapeutic targets in cancer management.

The p53 inactivators pifithrin-μ and pifithrin-α mitigate TBI-induced neuronal damage through regulation of oxidative stress, neuroinflammation, autophagy and mitophagy

Traumatic brain injury (TBI) is one of the most common causes of death and disability worldwide. We investigated whether inhibition of p53 using pifithrin (PFT)-α or PFT-μ provides neuroprotective effects via p53 transcriptional dependent or -independent mechanisms, respectively. Sprague Dawley rats were subjected to controlled cortical impact TBI followed by the administration of PFTα or PFT-μ (2 mg/kg, i.v.) at 5 h after TBI. Brain contusion volume, as well as sensory and motor functions were evaluated at 24 h after TBI. TBI-induced impairments were mitigated by both PFT-α and PFT-μ. Fluoro-Jade C staining was used to label degenerating neurons within the TBI-induced cortical contusion region that, together with Annexin V positive neurons, were reduced by PFT-μ. Double immunofluorescence staining similarly demonstrated that PFT-μ significantly increased HO-1 positive neurons and mRNA expression in the cortical contusion region as well as decreased numbers of 4-hydroxynonenal (4HNE)-positive cells. Levels of mRNA encoding for p53, autophagy, mitophagy, anti-oxidant, anti-inflammatory related genes and proteins were measured by RT-qPCR and immunohistochemical staining, respectively. PFT-α, but not PFT-μ, significantly lowered p53 mRNA expression. Both PFT-α and PFT-μ lowered TBI-induced pro-inflammatory cytokines (IL-1β and IL-6) mRNA levels as well as TBI-induced autophagic marker localization (LC3 and p62). Finally, treatment with PFT-μ mitigated TBI-induced declines in mRNA levels of PINK-1 and SOD2. Our data suggest that both PFT-μ and PFT-α provide neuroprotective actions through regulation of oxidative stress, neuroinflammation, autophagy, and mitophagy mechanisms, and that PFT-μ, in particular, holds promise as a TBI treatment strategy.

Proteasomal inhibition sensitizes cervical cancer cells to mitomycin C-induced bystander effect: the role of tumor microenvironment

Inaccessibility of drugs to poorly vascularized strata of tumor is one of the limiting factors in cancer therapy. With the advent of bystander effect (BE), it is possible to perpetuate the cellular damage from drug-exposed cells to the unexposed ones. However, the role of infiltrating tumor-associated macrophages (TAMs), an integral part of the tumor microenvironment, in further intensifying BE remains obscure. In the present study, we evaluated the effect of mitomycin C (MMC), a chemotherapeutic drug, to induce BE in cervical carcinoma. By using cervical cancer cells and differentiated macrophages, we demonstrate that MMC induces the expression of FasL via upregulation of PPARγ in both cell types (effector cells) in vitro, but it failed to induce bystander killing in cervical cancer cells. This effect was primarily owing to the proteasomal degradation of death receptors in the cervical cancer cells. Pre-treatment of cervical cancer cells with MG132, a proteasomal inhibitor, facilitates MMC-mediated bystander killing in co-culture and condition medium transfer experiments. In NOD/SCID mice bearing xenografted HeLa tumors administered with the combination of MMC and MG132, tumor progression was significantly reduced in comparison with those treated with either agent alone. FasL expression was increased in TAMs, and the enhanced level of Fas was observed in these tumor sections, thereby causing increased apoptosis. These findings suggest that restoration of death receptor-mediated apoptotic pathway in tumor cells with concomitant activation of TAMs could effectively restrict tumor growth.

FAS Death Receptor: A Breast Cancer Subtype-Specific Radiation Response Biomarker and Potential Therapeutic Target

Although a standardized approach to radiotherapy has been used to treat breast cancer, regardless of subtype (e.g., luminal, basal), recent clinical data suggest that radiation response may vary significantly among subtypes. We hypothesized that this clinical variability may be due, in part, to differences in cellular radiation response. In this study, we utilized RNA samples for microarray analysis from two sources: 1. Paired pre- and postirradiation breast tumor tissue from 32 early-stage breast cancer patients treated in our unique preoperative radiation Phase I trial; and 2. Sixteen biologically diverse breast tumor cell lines exposed to 0 and 5 Gy irradiation. The transcriptome response to radiation exposure was derived by comparing gene expression in samples before and after irradiation. Genes with the highest coefficient of variation were selected for further evaluation and validated at the RNA and protein level. Gene editing and agonistic antibody treatment were performed to assess the impact of gene modulation on radiation response. Gene expression in our cohort of luminal breast cancer patients was distinctly different before and after irradiation. Further, two distinct patterns of gene expression were observed in our biologically diverse group of breast cancer cell lines pre- versus postirradiation. Cell lines that showed significant change after irradiation were largely luminal subtype, while gene expression in the basal and HER2+ cell lines was minimally impacted. The 100 genes with the most significant response to radiation in patients were identified and analyzed for differential patterns of expression in the radiation-responsive versus nonresponsive cell lines. Fourteen genes were identified as significant, including FAS, a member of the tumor necrosis factor receptor family known to play a critical role in programed cell death. Modulation of FAS in breast cancer cell lines altered radiation response phenotype and enhanced radiation sensitivity in radioresistant basal cell lines. Our findings suggest that cell-type-specific, radiation-induced FAS contributes to subtype-specific breast cancer radiation response and that activation of FAS pathways may be exploited for biologically tailored radiotherapy.

Evaluation of in vitro anti-proliferative and immunomodulatory activities of compounds isolated from Curcuma longa

The rhizome of Curcuma longa (CL) has been commonly used in Asia as a potential candidate for the treatment of different diseases, including inflammatory disorders and cancers. The present study evaluated the anti-proliferative activities of the isolated compounds (three curcuminoids and two turmerones) from CL, using human cancer cell lines HepG2, MCF-7 and MDA-MB-231. The immunomodulatory activities of turmerones (alpha and aromatic) isolated from CL were also examined using human peripheral blood mononuclear cells (PBMC). Our results showed that the curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) and alpha-turmerone significantly inhibited proliferation of cancer cells in dose-dependent manner. The IC(50) values of these compounds in cancer cells ranged from 11.0 to 41.8 microg/ml. alpha-Turmerone induced MDA-MB-231 cells to undergo apoptosis, which was confirmed by annexin-V and propidium iodide staining, and DNA fragmentation assay. The caspase cascade was activated as shown by a significant decrease of procaspases-3, -8 and -9 in alpha-turmerone treated cells. Both alpha-turmerone and aromatic-turmerone showed stimulatory effects on PBMC proliferation and cytokine production. The anti-proliferative effect of alpha-turmerone and immunomodulatory activities of ar-turmerone was shown for the first time. The findings revealed the potential use of CL crude extract (containing curcuminoids and volatile oil including turmerones) as chemopreventive agent.

The anti-apoptotic protein lifeguard is expressed in breast cancer cells and tissues

Lifeguard (LFG) is an anti-apoptotic protein that inhibits Fas-mediated death in tumour cells. However, the molecular function of human LFG in the carcinogenesis of human breast cells is uncertain. We studied the expression and function of endogenous LFG in four breast cancer cell lines (MCF-7, MDA-MB-231, T-47D and HS 578T), a human breast epithelial cell line (HS 578Bst), and in healthy and cancerous breast tissues. Molecular (Western blot and RT-PCR) and immunohistochemical techniques were used to investigate the LFG expression. To investigate the breast cancer cell proliferation in the presence of Fas, we performed fluorescent cell viability assays. The possible association of Fas with LFG was analyzed by immunofluorescence microscopy. In this paper, we provide convincing evidence that LFG is overexpressed in several human breast cancer cell lines. More importantly, we found that the LFG expression correlates with high tumour grades in primary breast tumours. Finally, we demonstrated that Fas sensitivity is reduced in breast cancer cell lines expressing LFG. Our results indicated that LFG is strongly expressed in breast cancer epithelial cells. Moreover, the overexpression of LFG correlated with tumour grade and reduced Fas sensitivity. Our findings support the idea that LFG may have a role in the downregulation of apoptosis in breast cancer cells.

Estradiol-induced regression in T47D:A18/PKCalpha tumors requires the estrogen receptor and interaction with the extracellular matrix

Several breast cancer tumor models respond to estradiol (E(2)) by undergoing apoptosis, a phenomenon known to occur in clinical breast cancer. Before the application of tamoxifen as an endocrine therapy, high-dose E(2) or diethystilbesterol treatment was successfully used, albeit with unfavorable side effects. It is now recognized that such an approach may be a potential endocrine therapy option. We have explored the mechanism of E(2)-induced tumor regression in our T47D:A18/PKCalpha tumor model that exhibits autonomous growth, tamoxifen resistance, and E(2)-induced tumor regression. Fulvestrant, a selective estrogen receptor (ER) down-regulator, prevents T47D:A18/PKCalpha E(2)-induced tumor growth inhibition and regression when given before or after tumor establishment, respectively. Interestingly, E(2)-induced growth inhibition is only observed in vivo or when cells are grown in Matrigel but not in two-dimensional tissue culture, suggesting the requirement of the extracellular matrix. Tumor regression is accompanied by increased expression of the proapoptotic FasL/FasL ligand proteins and down-regulation of the prosurvival Akt pathway. Inhibition of colony formation in Matrigel by E(2) is accompanied by increased expression of FasL and short hairpin RNA knockdown partially reverses colony formation inhibition. Classic estrogen-responsive element-regulated transcription of pS2, PR, transforming growth factor-alpha, C3, and cathepsin D is independent of the inhibitory effects of E(2). A membrane-impermeable E(2)-BSA conjugate is capable of mediating growth inhibition, suggesting the involvement of a plasma membrane ER. We conclude that E(2)-induced T47D:A18/PKCalpha tumor regression requires participation of ER-alpha, the extracellular matrix, FasL/FasL ligand, and Akt pathways, allowing the opportunity to explore new predictive markers and therapeutic targets.

Inhibitory effect of HGF on invasiveness of aggressive MDA-MB231 breast carcinoma cells, and role of HDACs

Hepatocyte growth factor (HGF), through Met receptor binding, fulfils numerous functions in invasive tumour growth (survival/proliferation, motility, apoptosis), but epigenetic control of gene expression in this process is poorly understood. In HGF-treated breast cancer cells we studied (a) the chemoinvasion towards CXCL12 (ligand of the chemokine-receptor CXCR4) and (b) the mechanistic basis, that is, the transduction pathways that regulate CXCR4-mediated invasion, and the role played by histone deacetylases (HDACs) after blockade with trichostatin A (TSA). In highly invasive and metastatic MDA-MB231 cells HGF had a dual inhibitory effect, reducing spontaneous migration and specific chemoinvasion towards CXCL12, the latter by decreasing CXCR4 transactivation and protein level. After HGF the levels of phosphorylated (therefore active) c-Src and Akt persistently increased, indicating a role of these signal transducers in the HGF-dependent cellular and molecular effects. c-Src wild-type expression vector (Srcwt) increased active c-Src and mimicked the HGF-dependent inhibition of CXCR4 transactivation. Our findings indicate that HDACs participated in the HGF-inhibitory effects. In fact, blockade of HDACs hindered the HGF- and Srcwt-dependent reductions of CXCR4 transactivation and invasiveness, while inhibition of endogenous c-Src was additive with HGF, further reducing specific chemoinvasion. In conclusion, in MDA-MB231 cells HDAC blockade with TSA partly counteracted the HGF-dependent effects through molecular events that included enhancement of the expression of the genes for invasiveness Met and CXCR4 (depending on serum conditions), reduction of endogenous phospho-c-Src/c-Src and phosphoAkt/Akt ratios and triggering of apoptosis. The potential therapeutic use of TSA should take into account the variable aggressiveness of breast carcinoma cells and microenvironment signals such as HGF at the secondary growth site of the tumour. It was interesting that HGF reduced motility and CXCR4 functionality only of MDA-MB231 cells, and not of low-invasive MCF-7 cells, suggesting a mechanism implicated in metastatic cell homing.

CD4+T cells in CIKs (CD4+ CIKs) reversed resistance to fas-mediated apoptosis through CD40/CD40L ligation rather than IFN-gamma stimulation

BACKGROUND

Cytokine-induced killer cells (CIKs) are nonspecific antitumor effectors with superior advantages. CD4+ CIKs can induce Fas-dependent apoptosis in sensitive Raji cells. Here, a Fas-dependent apoptosis was detected in resistant breast cancer MDA-MB-231 cells, and underlying mechanisms were discriminated.

METHODS

Amplification of CIKs and purification of CD4+ CIKs were performed in 15 patients with malignant solid tumors. The expression of CD40L and soluble cytokines in CD4+ CIKs were analyzed. The apoptotic rates of tumor cells and the expression of Fas on membranes were detected using flow cytometry assay. The specific blocking antibodies against FasL, CD40L, and interferon-gamma (IFN-gamma) were added to abolish their effects. The changes of 4 apoptosis-related genes (Bcl-2, Bax, Fas-associating protein with death domain [FADD], and FLICE inhibitory protein [c-FLIP]) in MDA-MB-231 cells cocultured with CD4+ CIKs were measured by real-time quantitative reverse-transcriptase polymerase chain reaction after 6 hours and 24 hours with or without blocking antibodies.

RESULTS

Upregulated expression of membrane-attached CD40L and dramatically increased secretion of soluble CD40L and IFN-gamma were identified in CD4+ CIK. The susceptibility to Fas-mediated apoptosis of insensitive MDA-MB-231 cells was elevated after being pretreated with supernatants from CD4+ CIK. After coculture with CD4+ CIK, apoptosis in MDA-MB-231 cells paralleled with enhanced expression of Fas was blocked fully by either anti-FasL or anti-CD40L, but only partly by anti-IFN-gamma antibodies. The anti-CD40L monoclonal antibody (McAb) rather than anti-IFN-gamma McAb induced significant increase of c-FLIP, which negatively correlated with the apoptosis observed in MDA-MB-231 cells.

CONCLUSIONS

Apoptosis in MDA-MB-231 cells induced by CD4+ CIK is Fas-dependent. The reversion of Fas resistance is mediated through CD40/CD40L ligation rather than IFN-gamma stimulation by inhibiting synthesis of c-FLIP.

Norsolorinic acid from Aspergillus nidulans inhibits the proliferation of human breast adenocarcinoma MCF-7 cells via Fas-mediated pathway

Norsolorinic acid, isolated from the Aspergillus nidulans, was investigated for its antiproliferative activity in human breast adenocarcinoma MCF-7 cells. To identity the anticancer mechanism of norsolorinic acid, we assayed its effect on apoptosis, cell cycle distribution, and levels of p53, p21/WAF1, Fas/APO-1 receptor and Fas ligand. The results showed that norsolorinic acid induced apoptosis of MCF-7 cells without mediation of p53 and p21/WAF1. We suggest that Fas/Fas ligand apoptotic system is the main pathway of norsolorinic acid-mediated apoptosis of MCF-7 cells. Our study reports here for the first time that the activity of the Fas/Fas ligand apoptotic system may participate in the antiproliferative activity of norsolorinic acid in MCF-7 cells.

Peroxisome proliferator-activated receptor gamma activates fas ligand gene promoter inducing apoptosis in human breast cancer cells

In just over a decade, apart from established metabolic actions, peroxisome proliferator-activated receptor gamma (PPARgamma) has evolved as key therapeutic target in cancer disease. Fas ligand (FasL), a trans-membrane protein, induces apoptosis by crosslinking with the Fas receptor. Despite the FasL relevance, little is available on the regulation of its expression. In the current study, we explored for the first time the potential role of PPARgamma in triggering apoptotic events through the Fas/FasL pathway in breast cancer cells. In MCF7 cells, by reverse transcription-polymerase chain reaction and Western blotting, we showed that the synthetic PPARgamma ligand rosiglitazone (BRL) enhanced FasL expression, that was abrogated by a specific PPARgamma antagonist GW9662. Transient transfection assays demonstrated that BRL transactivated human FasL promoter gene in a PPARgamma-dependent manner. Progressive 5' deletion analysis has identified a minimal promoter fragment spanning nucleotides from -318 to -237 bp, which is still sensitive to BRL treatment. FasL promoter activity was abrogated by mithramycin, suggesting an involvement of Sp1 transcription factor in PPARgamma action. Electrophoretic mobility shift and chromatin immuno-precipitation assays demonstrated that BRL increased the binding of PPARgamma and Sp1 to the Sp1 sequence located within the FasL gene promoter. The role of PPARgamma and Fas/FasL pathways in BRL-induced apoptotic events was assessed by caspase 8 cleavage in the presence of GW as well as PPARgamma and FasL RNA interferences. Our results indicate that PPARgamma positively regulates the FasL gene expression also in MDA-MB231 and in BT20, revealing a new molecular mechanism by which BRL induces apoptosis in breast cancer cells.

Proteomics Demonstration That Normal Breast Epithelial Cells Can Induce Apoptosis of Breast Cancer Cells through Insulin-like Growth Factor-binding Protein-3 and Maspin

Normal breast epithelial cells are known to exert an apoptotic effect on breast cancer cells, resulting in a potential paracrine inhibition of breast tumor development. In this study we purified and characterized the apoptosis-inducing factors secreted by normal breast epithelial cells. Conditioned medium was concentrated by ultrafiltration and separated on reverse phase Sep-Pak C18 and HPLC. The proapoptotic activity of eluted fractions was tested on MCF-7 breast cancer cells, and nano-LC-nano-ESI-MS/MS allowed the identification of insulin-like growth factor-binding protein-3 (IGFBP-3) and maspin as the proapoptotic factors produced by normal breast epithelial cells. Western blot analysis of conditioned media confirmed the specific secretion of IGFBP-3 and maspin by normal cells but not by breast cancer cells. Immunodepletion of IGFBP-3 and maspin completely abolished the normal cell-induced apoptosis of cancer cells, and recombinant proteins reproduced the effect of normal cell-conditioned medium on apoptosis of breast cancer cells. Together our results indicated that normal breast epithelial cells can induce apoptosis of breast cancer cells through IGFBP-3 and maspin. These findings provide a molecular hypothesis for the long observed inhibitory effect of normal surrounding cells on breast cancer development.

Bystander killing of breast cancer MCF-7 cells by MDA-MB-231 cells exposed to 5-fluorouracil is mediated via Fas

The major drawback with cancer therapy is the development of resistant cells within tumors due to their heterogeneous nature and due to inadequate drug delivery during chemotherapy. Therefore, the propagation of injury ("bystander effect" (BE)) from directly damaged cells to other cells may have great implications in cancer chemotherapy. The general advantage of the bystander cell killing phenomenon is the large therapeutic index that can be achieved. Experiments suggest that this phenomenon is detected in radiation therapy as well as in gene therapy in conjunction with chemotherapy. In the present study, we developed an original in vitro model dedicated to the exploration of bystander cytotoxicity induced during breast carcinoma chemotherapy. In brief, we investigated this perpetuation of injury on untreated bystander MCF-7 breast cancer cells which were coplated with 5-fluorouracil (5-FU)-treated MDA-MB-231 breast cancer cells. To achieve this goal, a specific in vitro coculture model which involved mixing of aggressive MDA-MB-231 breast cancer cells with enhanced green fluorescent protein (EGFP) expressing stable clone of non-metastatic MCF-7 breast cancer cells (MCF-EGFP), was used. A bystander killing effect was observed in MCF-EGFP cells cocultured with MDA-MB-231 cells pretreated with 5-FU. The striking decrease in MCF-EGFP cells, as detected by assaying for total GFP intensity, is mediated by activation of Fas/FasL system. The implication of Fas in MCF-EGFP cell death was confirmed by using antagonistic anti-FasL antibody that reverses bystander cell death by blocking FasL on MDA-MB-231 cells. In addition, inhibition of CD95/Fas receptor on the cell surface of MCF-EGFP cells by treatment with Pifithrin-alpha, a p53 specific transactivation inhibitor, partially abrogated the sensitivity of bystander MCF-EGFP cells. Our data, therefore, demonstrates that the Fas/FasL system could be considered as a new determinant for chemotherapy-induced bystander cell death in breast cancers.

Induction of apoptosis in human breast adenocarcinoma MCF-7 cells by pterocarnin A from the bark of Pterocarya stenoptera via the Fas-mediated pathway

Pterocarnin A, isolated from the bark of Pterocarya stenoptera (Juylandaceae), was investigated for its antiproliferative activity in human breast adenocarcinoma MCF-7 cells. To identify the anticancer mechanism of pterocarnin A, we assayed its effects on apoptosis, cell cycle distribution, and levels of p53, p21/WAF1, Fas/APO-1 receptor and Fas ligand. The results showed that pterocarnin A induced apoptosis of MCF-7 cells without mediation of p53 and p21/WAF1. We suggest that the Fas/Fas ligand apoptotic system is the main pathway of pterocarnin A-mediated apoptosis of MCF-7 cells. Our study reports here for the first time that the activity of the Fas/Fas ligand apoptotic system may participate in the antiproliferative activity of pterocarnin A in MCF-7 cells.

Estrogens decrease γ-ray–induced senescence and maintain cell cycle progression in breast cancer cells independently of p53

PURPOSE

Sequential administration of radiotherapy and endocrine therapy is considered to be a standard adjuvant treatment of breast cancer. Recent clinical reports suggest that radiotherapy could be more efficient in association with endocrine therapy. The aim of this study was to evaluate the estrogen effects on irradiated breast cancer cells (IR-cells).

METHODS AND MATERIALS

Using functional genomic analysis, we examined the effects of 17-beta-estradiol (E(2), a natural estrogen) on MCF-7 breast cancer cells.

RESULTS

Our results showed that E(2) sustained the growth of IR-cells. Specifically, estrogens prevented cell cycle blockade induced by gamma-rays, and no modification of apoptotic rate was detected. In IR-cells we observed the induction of genes involved in premature senescence and cell cycle progression and investigated the effects of E(2) on the p53/p21(waf1/cip1)/Rb pathways. We found that E(2) did not affect p53 activation but it decreased cyclin E binding to p21(waf1/cip1) and sustained downstream Rb hyperphosphorylation by functional inactivation of p21(waf1/cip1). We suggest that Rb inactivation could decrease senescence and allow cell cycle progression in IR-cells.

CONCLUSION

These results may help to elucidate the molecular mechanism underlying the maintenance of breast cancer cell growth by E(2) after irradiation-induced damage. They also offer clinicians a rational basis for the sequential administration of ionizing radiation and endocrine therapies.

Comparative studies of various ganoderma species and their different parts with regard to their antitumor and immunomodulating activities in vitro

OBJECTIVES

Ganoderma lucidum (Lingzhi or Reishi) has been commonly suggested in East Asia as a potential candidate for prevention and treatment of different diseases, including cancer. Ganoderma extracts, in particular Ganoderma lucidum (extracts or isolated components), have previously been shown to possess antitumor activities. The present study aimed at comparing three different species of Ganoderma, wildly grown versus cultivated, as well as the different parts of the fruiting body (whole fruiting body, pileus, and stipe), with regard to their antitumor effects in human breast cancer cells and immunomodulatory activities in mouse splenic lymphocytes in vitro.

METHODS

The aqueous extracts (12.5-400 microg/mL) of G. lucidum, G. sinense, and G. tsugae were examined for their antiproliferative activities in human breast cancer cell lines, MCF-7 and MDA-MB-231, as well as in normal human mammary epithelial cells (primary culture). The immunomodulatory effects of the extracts were evaluated in mouse splenic lymphocytes. The proliferative responses of the mentioned cell types were determined by MTT [3-(4,5-dimethylthiazolyl)-2,5-diphenyl-tetrazolium bromide] assay.

RESULTS

The present results demonstrated that the extracts of all tested Ganoderma samples could significantly inhibit cell proliferation in human breast cancer cell lines MCF-7 and MDA-MB-231, with G. tsugae being the most potent. The extracts, however, did not exert any significant cytotoxic effect on human normal mammary epithelial cells. Within the species G. sinense, the inhibitory effects of wildly grown samples were not significantly different from those of the cultivated samples, except at 400 microg/mL. Most of the tested extracts of Ganoderma stimulated mouse splenic lymphocytes proliferation. The extracts from the stipes of the G. tsugae and wildly grown G. sinense showed much stronger inhibitory effects than the other parts of the fruiting body in both cancer cell lines, whereas the extracts from the stipes of G. lucidum and wildly grown G. sinense showed stronger immunopotentiating activities in mouse splenic lymphocytes.

CONCLUSIONS

These results indicate that the aqueous extracts of these commonly available Ganoderma fruiting bodies, G. lucidum, G. sinense, and G. tsugae have antitumor activities in human breast cancer cells and immunomodulatory activities in murine lymphocytes. In addition, the present findings also suggest that the stipes of fruiting bodies of Ganoderma species should be included in the preparation of extract of these fungi in order to obtain the most comprehensive active ingredients. To the best of the authors' knowledge, this is the first detailed comparison among the different parts of the fruiting bodies of Ganoderma.

RETRACTED ARTICLE: Oleandrin-Mediated Expression of Fas Potentiates Apoptosis in Tumor Cells

Chemotherapeutic agent is characterized by its concentration in tumor cells with minimum side effects. Oleandrin, a polyphenolic cardiac glycoside is known to induce apoptosis in tumor cells. However, no report is available on its efficacy in primary cells. In this report we are providing the evidence that oleandrin induces apoptosis, not necrosis in tumor cells but not in primary cells like peripheral blood mononuclear cells (PBMC) and neutrophils. Oleandrin inhibited NF-kappaB activation in tumor cells but not in primary cells. It induced cell death in NF-kappaB-overexpressed tumor cells. Oleandrin induced Fas expression thereby inducing apoptosis in tumor cells but not in primary cells. Dominant negative FADD inhibited oleandrin-induced cell death in tumor cells. Overall, these results suggest that oleandrin mediates apoptosis in tumor cells by inducing Fas but not in primary cells indicating its potential anti-cancer property with no or slight side effect.

Hepatocyte growth factor enhances CXCR4 expression favoring breast cancer cell invasiveness

Microenvironmental factors affect different aspects of tumor cell biology, including cell survival, invasion, and metastasis. Here, we report that hepatocyte growth factor and hypoxia may contribute to breast carcinoma cell invasiveness by inducing the chemokine receptor CXCR4. Hepatocyte growth factor enhanced CXCR4 mRNA and protein expression exclusively in MCF-7 (low invasive) carcinoma cells, while in response to hypoxia, CXCR4 induction was observed in both MCF-7 and MDA-MB 231 (highly invasive) carcinoma cells. The receptor induction had a functional role in cancer cells, as demonstrated by the fact that hepatocyte growth factor pretreatment promoted MCF-7 cell migration toward the CXCR4-specific ligand CXCL12. Extracellular signal-regulated protein kinase 1/2 (ERK1/2) and phosphoinositide-3-kinase (PI3K) transduction pathways seemed to be differently implicated in the early induction of CXCR4 by hepatocyte growth factor or hypoxia in the two breast carcinoma cells examined.

Anti-gastric cancer active immunity induced by FasL/B7-1 gene-modified tumor cells

AIM: To study the activation of cytotoxic T lymphocytes (CTLs) against gastric cancer cells induced by FasL/B7-1 (FB-11) gene-modified tumor cells, and to explore whether co-expression of FasL and B7-1 in SGC-7901 tumor cells could initiate synergistic antitumor effect.

METHODS: FasL and B7-1 genes were transfected into human SGC-7901 gastric cancer cells with adenovirus vectors. The positive clones were selected by G418. FasL and B7-1 genes were detected by flow cytometry and RT-PCR. Abdominal infiltrating lymphocytes and sensitized spleen cells were obtained from mice that were immunized with SGC-7901/FB-11 or wild type SGC-7901 cells intraperitoneally, and cytotoxicity of these CTLs against tumor cells was determined by MTT assay.

RESULTS: Flow cytometry and RT-PCR showed that FasL and B7-1 genes were highly expressed. FasL and B7-1 transfected cancer cells had a high apoptosis index. DNA laddering suggested that FasL and B7-1 genes induced gastric cancer cell apoptosis. FasL⁺/B7-1⁺SGC-7901 cells (SGC-7901/FB-11) were inoculated subcutaneously in the dorsal skin of C57BL/6 mice and then decreased their tumorigenicity greatly (z = 2.15-46.10, P<0.01). SGC-7901/FB-11 cell-sensitized mice obtained protective immune activity against the rechallenge of wild type SGC-7901 cells (z = 2.06-44.30, P<0.05). The cytotoxicity of CTLs induced by SGC-7901/FB-11 cells against SGC-7901 was significantly higher than that of CTLs activated by wild-type SGC-7901 cells (84.1±2.4% vs 30.5±2.3%, P<0.05).

CONCLUSION: FasL and B7-1 genes can effectively promote the activity of CTLs against gastric cancer cells. FasL/B7-1 molecules play an important role in CTL cytotoxicity.

Induction of apoptosis in human breast adenocarcinoma MCF-7 cells by prodelphinidin B-2 3,3'-di-O-gallate from Myrica rubra via Fas-mediated pathway

Myrica rubra Sieb et Zucc. (Myricaceae) is well known as a rich source of tannins. Prodelphinidin B-2 3,3'-di-O-gallate (PB233'OG) is a proanthocyanidin gallate that has been reported to exhibit antioxidant and antiviral activity. In this study, we evaluated the anti-proliferative activity of PB233'OG isolated from the bark of M. rubra in human breast adenocarcinoma MCF-7 cells. To identity the anti-cancer mechanism of PB233'OG, we assayed its effect on apoptosis, cell cycle distribution, and levels of p53, p21/WAF1, Fas/APO-1 receptor and Fas ligand. The results showed that PB233'OG induced apoptosis of MCF-7 cells without mediation of p53 and p21/WAF1. We suggest that Fas/Fas ligand apoptotic system is the main pathway of PB233'OG-mediated apoptosis of MCF-7 cells. Our study reports here for the first time that the activity of the Fas/Fas ligand apoptotic system may participate in the anti-proliferative activity of PB233'OG in MCF-7 cells.

Antiestrogens, aromatase inhibitors, and apoptosis in breast cancer

Antiestrogens have been the therapeutic agents of choice for breast cancer patients whose tumors express estrogen receptors, regardless of menopausal status. Unfortunately, many patients will eventually develop resistance to these drugs. Antiestrogens primarily act by preventing endogenous estrogen from activating estrogen receptors and promoting cell growth, which can ultimately lead to tumor cell death. Understanding the mechanisms by which antiestrogens cause cell death or apoptosis is critical to our efforts to develop ways to circumvent resistance. This article focuses on antiestrogen-induced apoptosis both in vitro and in vivo. We review the clinical utility of both antiestrogens and aromatase inhibitors and their apoptogenic mechanisms in cell culture models. Among the key signaling components discussed are the roles of Bcl-2 family members, several cytokines, and their receptors, p53, nuclear factor kappa B (NFkappaB), IRF-1, phosphatidylinositol 3-kinase (PI3K)/Akt, and specific caspases. Finally, we discuss the evidence supporting a role for apoptotic defects in acquired and de novo antiestrogen resistance.

Synergistic induction of apoptosis in breast cancer cells by cotreatment with butyrate and TNF-alpha, TRAIL, or anti-Fas agonist antibody involves enhancement of death receptors' signaling and requires P21waf1

Inhibitors of histone deacetylase (HDAC) are considered as potential anticancer agents. We have previously demonstrated that an inhibitor of HDAC, sodium butyrate (NaB), induces apoptosis of breast cancer cells in a P53-independent and P21(waf1)-dependent manner. In this study, we showed that tumor necrosis factor-alpha (TNF-alpha), TNF-related apoptosis-inducing ligand (TRAIL), and anti-Fas agonist antibody potentiated NaB-induced growth inhibition through synergistic induction of apoptosis in breast cancer cell lines (MCF-7, T47-D, and BT-20). In MCF-7 cells, NaB increased the expression of death receptors; NaB alone or in combination with TNF-alpha, TRAIL, and anti-Fas agonist antibody increased the levels of Bid, tBid, and that of cytosolic cytochrome c. Synergistic induction of apoptosis was strongly inhibited by dominant-negative Fas-associated death domain (FADD) and inhibitors of caspases-8 and -9, indicating that potentiation of apoptosis involved key elements of death receptors' signaling pathways. Moreover, cotreatment of NaB and ligands of death receptors up-regulated the levels of P21(waf1) and that of proliferating cell nuclear antigen (PCNA) associated with P21(waf1). Transient transfections of p21(waf1) antisense or p21(waf1) deficient for its interaction with PCNA abolished synergistic induction of apoptosis. This suggested that potentiation of apoptosis by cotreatments required P21(waf1) and its interaction with PCNA. Since breast tumors contain rarely p21 mutations, our results may open interesting prospects in the fight against breast cancer.

Gene expression profiling of mammary gland development reveals putative roles for death receptors and immune mediators in post-lactational regression

INTRODUCTION

In order to gain a better understanding of the molecular processes that underlie apoptosis and tissue regression in mammary gland, we undertook a large-scale analysis of transcriptional changes during the mouse mammary pregnancy cycle, with emphasis on the transition from lactation to involution.

METHOD

Affymetrix microarrays, representing 8618 genes, were used to compare mammary tissue from 12 time points (one virgin, three gestation, three lactation and five involution stages). Six animals were used for each time point. Common patterns of gene expression across all time points were identified and related to biological function.

RESULTS

The majority of significantly induced genes in involution were also differentially regulated at earlier stages in the pregnancy cycle. This included a marked increase in inflammatory mediators during involution and at parturition, which correlated with leukaemia inhibitory factor-Stat3 (signal transducer and activator of signalling-3) signalling. Before involution, expected increases in cell proliferation, biosynthesis and metabolism-related genes were observed. During involution, the first 24 hours after weaning was characterized by a transient increase in expression of components of the death receptor pathways of apoptosis, inflammatory cytokines and acute phase response genes. After 24 hours, regulators of intrinsic apoptosis were induced in conjunction with markers of phagocyte activity, matrix proteases, suppressors of neutrophils and soluble components of specific and innate immunity.

CONCLUSION

We provide a resource of mouse mammary gene expression data for download or online analysis. Here we highlight the sequential induction of distinct apoptosis pathways in involution and the stimulation of immunomodulatory signals, which probably suppress the potentially damaging effects of a cellular inflammatory response while maintaining an appropriate antimicrobial and phagocytic environment.

Antiestrogen resistance in breast cancer and the role of estrogen receptor signaling

Antiestrogens include agents such as tamoxifen, toremifene, raloxifene, and fulvestrant. Currently, tamoxifen is the only drug approved for use in breast cancer chemoprevention, and it remains the treatment of choice for most women with hormone receptor positive, invasive breast carcinoma. While antiestrogens have been available since the early 1970s, we still do not fully understand their mechanisms of action and resistance. Essentially, two forms of antiestrogen resistance occur: de novo resistance and acquired resistance. Absence of estrogen receptor (ER) expression is the most common de novo resistance mechanism, whereas a complete loss of ER expression is not common in acquired resistance. Antiestrogen unresponsiveness appears to be the major acquired resistance phenotype, with a switch to an antiestrogen-stimulated growth being a minor phenotype. Since antiestrogens compete with estrogens for binding to ER, clinical response to antiestrogens may be affected by exogenous estrogenic exposures. Such exposures include estrogenic hormone replacement therapies and dietary and environmental exposures that directly or indirectly increase a tumor's estrogenic environment. Whether antiestrogen resistance can be conferred by a switch from predominantly ERalpha to ERbeta expression remains unanswered, but predicting response to antiestrogen therapy requires only measurement of ERalpha expression. The role of altered receptor coactivator or corepressor expression in antiestrogen resistance also is unclear, and understanding their roles may be confounded by their ubiquitous expression and functional redundancy. We have proposed a gene network approach to exploring the mechanistic aspects of antiestrogen resistance. Using transcriptome and proteome analyses, we have begun to identify candidate genes that comprise one component of a larger, putative gene network. These candidate genes include NFkappaB, interferon regulatory factor-1, nucleophosmin, and the X-box binding protein-1. The network also may involve signaling through ras and MAPK, implicating crosstalk with growth factors and cytokines. Ultimately, signaling affects the expression/function of the proliferation and/or apoptotic machineries.

Proteomics in studies of signal transduction in epithelial cells

An understanding of the complexity of cancer is important for correct diagnostics and efficient treatment of this disease. Recent developments of proteomics technologies allow us to address the complexity of tumorigenesis at a level of global protein profiling. This review discusses recent studies of signaling processes in cells of epithelial origin undertaken with the use of global protein profiling. Tumors of epithelial origin comprise about 90% of human breast cancers, and it is believed that transformation of breast epithelial cells shares common features of transformation with other mammalian cells: destabilization of the genome followed by acquisition of immortalization, unrestricted growth, evasion of death-inducing signals, and acquisition of invasive and tumor promoting characteristics. Functional proteomics of growth-promoting, growth-inhibiting, and pro-apoptotic signaling pathways, in combination with proteomics studies of breast epithelial cell differentiation and profiling of breast tumorigenesis, revealed groups of regulated proteins: structural components, stress-regulated proteins, regulators of transcription, translation and RNA processing, and regulators of posttranslational modifications, e.g., kinases, phosphatases, and proteases. The first lesson of proteomics studies is the discovery of significant number of new targets, as compared to total number of affected proteins. The second lesson is the poor correlation between expressions of proteins and their mRNAs. The third lesson is the low amplitude of protein changes compared to that observed for mRNA. These observations also recommend the analysis of signaling patterns rather than separate signaling pathways.