Profiling of differentially expressed genes induced by high linear energy transfer radiation in breast epithelial cells

Ionizing Radiation and Estrogen Affecting Growth Factor Genes in an Experimental Breast Cancer Model

Genes associated with growth factors were previously analyzed in a radiation- and estrogen-induced experimental breast cancer model. Such in vitro experimental breast cancer model was developed by exposure of the immortalized human breast epithelial cell line, MCF-10F, to low doses of high linear energy transfer (LET) α particle radiation (150 keV/μm) and subsequent growth in the presence or absence of 17β-estradiol. The MCF-10F cell line was analyzed in different stages of transformation after being irradiated with either a single 60 cGy dose or 60/60 cGy doses of alpha particles. In the present report, the profiling of differentially expressed genes associated with growth factors was analyzed in their relationship with clinical parameters. Thus, the results indicated that Fibroblast growth factor2 gene expression levels were higher in cells transformed by radiation or in the presence of ionizing radiation; whereas the fibroblast growth factor-binding protein 1gene expression was higher in the tumor cell line derived from this model. Such expressions were coincident with higher values in normal than malignant tissues and with estrogen receptor (ER) negative samples for both gene types. The results also showed that transforming growth factor alpha gene expression was higher in the tumor cell line than the tumorigenic A5 and the transformed A3 cell line, whereas the transforming growth factor beta receptor 3 gene expression was higher in A3 and A5 than in Tumor2 cell lines and the untreated controls and the E cell lines. Such gene expression was accompanied by results indicating negative and positive receptors for transforming growth factor alpha and the transforming growth factor beta receptor 3, respectively. Such expressions were low in malignant tissues when compared with benign ones. Furthermore, Fibroblast growth factor2, the fibroblast growth factor-binding protein 1, transforming growth factor alpha, the transforming growth factor beta receptor 3, and the insulin growth factor receptor gene expressions were found to be present in all BRCA patients that are BRCA-Basal, BRCA-LumA, and BRCA-LumB, except in BRCA-Her2 patients. The results also indicated that the insulin growth factor receptor gene expression was higher in the tumor cell line Tumor2 than in Alpha3 cells transformed by ionizing radiation only; then, the insulin growth factor receptor was higher in the A5 than E cell line. The insulin growth factor receptor gene expression was higher in breast cancer than in normal tissues in breast cancer patients. Furthermore, Fibroblast growth factor2, the fibroblast growth factor-binding protein 1, transforming growth factor alpha, the transforming growth factor beta receptor 3, and the insulin growth factor receptor gene expression levels were in stages 3 and 4 of breast cancer patients. It can be concluded that, by using gene technology and molecular information, it is possible to improve therapy and reduce the side effects of therapeutic radiation use. Knowing the different genes involved in breast cancer will make possible the improvement of clinical chemotherapy.

Gene Signatures Induced by Ionizing Radiation as Prognostic Tools in an In Vitro Experimental Breast Cancer Model

Simple Summary

The present work analyzed the expression of genes involved in radiation, using an in vitro experimental breast cancer model developed by the combined treatment of low doses of high linear energy transfer (LET) radiation α particle radiation and estrogen yielding different stages in a malignantly transformed breast cancer cell model called Alpha model. Results showed important findings of genes involved in cancers of the breast, lung, and nervous system, and others. Most of those genes analyzed in these studies such as ATM, selenoproteins, GABA receptor, interleukins, epsin, and cathepsin inhibitors like stefins, and metallothioneins can be used for new prognostic tools and future therapies since they affect cancer progression and metastasis. In conclusion, gene signature demonstrated to be specific to cell line types, hence cell-dependency must be considered in future radiotherapy treatment planning since molecular and clinical features affect such results. Thus, using gene technology and molecular information is possible to improve therapies and reduction of side effects.

Abstract

This study aimed to analyze the expression of genes involved in radiation, using an Affymetrix system with an in vitro experimental breast cancer model developed by the combined treatment of low doses of high linear energy transfer (LET) radiation α particle radiation and estrogen yielding different stages in a malignantly transformed breast cancer cell model called Alpha model. Altered expression of different molecules was detected in the non-tumorigenic Alpha3, a malignant cell line transformed only by radiation and originally derived from the parental MCF-10F human cell line; that was compared with the Alpha 5 cell line, another cell line exposed to radiation and subsequently grown in the presence 17β-estradiol. This Alpha5, a tumorigenic cell line, originated the Tumor2 cell line. It can be summarized that the Alpha 3 cell line was characterized by greater gene expression of ATM and IL7R than control, Alpha5, and Tumor2 cell lines, it presented higher selenoprotein gene expression than control and Tumor2; epsin 3 gene expression was higher than control; stefin A gene expression was higher than Alpha5; and metallothionein was higher than control and Tumor2 cell line. Therefore, radiation, independently of estrogen, induced increased ATM, IL7R, selenoprotein, GABA receptor, epsin, stefin, and metallothioneins gene expression in comparison with the control. Results showed important findings of genes involved in cancers of the breast, lung, nervous system, and others. Most genes analyzed in these studies can be used for new prognostic tools and future therapies since they affect cancer progression and metastasis. Most of all, it was revealed that in the Alpha model, a breast cancer model developed by the authors, the cell line transformed only by radiation, independently of estrogen, was characterized by greater gene expression than other cell lines. Understanding the effect of radiotherapy in different cells will help us improve the clinical outcome of radiotherapies. Thus, gene signature has been demonstrated to be specific to tumor types, hence cell-dependency must be considered in future treatment planning. Molecular and clinical features affect the results of radiotherapy. Thus, using gene technology and molecular information is possible to improve therapies and reduction of side effects while providing new insights into breast cancer-related fields.

Oxidative stress in female cancers

Breast, cervical and ovarian cancers are highly prevalent in women worldwide. Environmental, hormonal and viral-related factors are especially relevant in the development of these tumors. These factors are strongly related to oxidative stress (OS) through the generation of reactive oxygen species (ROS). The OS is caused by an imbalance in the redox status of the organism and is literally defined as "an imbalance between ROS generation and its detoxification by biological system leading to impairment of damage repair by cell/tissue". The multistep progression of cancer suggests that OS is involved in cancer initiation, promotion and progression. In this review, we described the role of OS and the interplay with environmental, host and viral factors related to breast, cervical and ovarian cancers initiation, promotion and progression. In addition, the role of the natural antioxidant compound curcumin and other compounds for breast, cervical and ovarian cancers prevention/treatment is discussed.

Metastatic genes targeted by an antioxidant in an established radiation- and estrogen-breast cancer model

Breast cancer remains the second most common disease worldwide. Radiotherapy, alone or in combination with chemotherapy, is widely used after surgery as a treatment for cancer with proven therapeutic efficacy manifested by reduced incidence of loco-regional and distant recurrences. However, clinical evidence indicates that relapses occurring after radiotherapy are associated with increased metastatic potential and poor prognosis in the breast. Among the anticarcinogenic and antiproliferative agents, curcumin is a well-known major dietary natural yellow pigment derived from the rhizome of the herb Curcuma longa (Zingiberaceae). The aim of the present study was to analyze the differential expression of metastatic genes in radiation- and estrogen-induced breast cancer cell model and the effect of curcumin on such metastatic genes in breast carcinogenesis. Expression levels of TGF-α and TGFβ1 genes were upregulated in MCF-10F and downregulated in Tumor2 cell lines treated with curcumin. Expression levels of other genes such as caspase 9 and collagen 4 A2 were upregulated in both MCF-10F and Tumor2-treated cell lines. Integrin α5 and cathepsin B and D decreased its expression in Tumor2, whereas E-Cadherin, c-myc and CD44 expressions were only increased in MCF-10F. It can be concluded that metastatic genes can be affected by curcumin in cancer progression and such substance can be used in breast cancer patients with advanced disease without side-effects commonly observed with therapeutic drugs.

Allelic loss at chromosome 11q13 alters FGF3 gene expression in a human breast cancer progression model

Identification of markers with the potential to predict tumorigenic behavior is important in breast cancer, due to the variability in clinical disease progression. Genetic alterations during neoplastic progression may appear as changes in total DNA content, single genes, or gene expression. Oncogenic alterations are thought to be prognostic indices for patients with breast cancer. Breast cancer deregulation can occur in the normal cellular process and can be measured by microsatellite instability (MSI)/loss of heterozygosity (LOH). Chromosome 11 is unique in this respect, as three regions of MSI/LOH have been identified (11p15-p15.5, 11q13-q13.3 and 11q23-q24). There are many important families of genes, such as FGF, CCND1, FADD, BAD and GAD2, that are located on chromosome 11 and these play a crucial role in breast cancer progression. Among them, different members of the fibroblast growth factor (FGF) family of genes are clustered around human chromosome 11q13 amplicon, which are constantly altering during breast cancer progression. Therefore, in this study, locus 11q13 and FGF3 gene (11q13) function were investigated in a radiation and estrogen breast cancer model induced by high-LET (α-particle) radiation and estrogen exposure. To assess the effect of ionizing radiation and estrogen at chromosome 11q13 loci and the subsequent role of FGF3 gene expression, various microsatellite markers were chosen in this region, and allelic loses (~20-45%) were identified by PCR-SSCP analysis. Results showed an increase in FGF3 protein expression and a 6- to 8-fold change in gene expression of FGF3 and associated genes. These deregulations could be utilized as an appropriate target for therapeutic intervention in breast cancer.

The role of master regulators in the metabolic/transcriptional coupling in breast carcinomas

Metabolic transformations have been reported as involved in neoplasms survival. This suggests a role of metabolic pathways as potential cancer pharmacological targets. Modulating tumor's energy production pathways may become a substantial research area for cancer treatment. The significant role of metabolic deregulation as inducing transcriptional instabilities and consequently whole-system failure, is thus of foremost importance. By using a data integration approach that combines experimental evidence for high-throughput genome wide gene expression, a non-equilibrium thermodynamics analysis, nonlinear correlation networks as well as database mining, we were able to outline the role that transcription factors MEF2C and MNDA may have as main master regulators in primary breast cancer phenomenology, as well as the possible interrelationship between malignancy and metabolic dysfunction. The present findings are supported by the analysis of 1191 whole genome gene expression experiments, as well as probabilistic inference of gene regulatory networks, and non-equilibrium thermodynamics of such data. Other evidence sources include pathway enrichment and gene set enrichment analyses, as well as motif comparison with a comprehensive gene regulatory network (of homologue genes) in Arabidopsis thaliana. Our key finding is that the non-equilibrium free energies provide a realistic description of transcription factor activation that when supplemented with gene regulatory networks made us able to find deregulated pathways. These analyses also suggest a novel potential role of transcription factor energetics at the onset of primary tumor development. Results are important in the molecular systems biology of cancer field, since deregulation and coupling mechanisms between metabolic activity and transcriptional regulation can be better understood by taking into account the way that master regulators respond to physicochemical constraints imposed by different phenotypic conditions.

Oral DNA vaccines target the tumor vasculature and microenvironment and suppress tumor growth and metastasis

Four novel oral DNA vaccines provide protection against melanoma, colon, breast, and lung carcinoma in mouse models. Vaccines are delivered by attenuated Salmonella typhimurium to secondary lymphoid organs and respectively target vascular endothelial growth factor receptor-2, transcription factor Fos-related antigen-1, anti-apoptosis protein survivin and Legumain, an asparaginyl endopeptidase specifically overexpressed on tumor-associated macrophages (TAMs) in the tumor microenvironment (TME). These vaccines are all capable of inducing potent cell-mediated protective immunity against self-antigens, resulting in marked suppression of tumor growth and dissemination. Key mechanisms induced by these DNA vaccines include efficient suppression of angiogenesis in the tumor vasculature and marked activation of cytotoxic T cells, natural killer cells, and antigen-presenting dendritic cells. The vaccine targeting Legumain establishes the new paradigm whereby a reduction in the density of TAMs in the TME decreases the release of factors potentiating tumor growth and angiogenesis. This, in turn, remodels the TME and decreases its immunosuppressive milieu and thereby potentiates the DNA vaccine's ability to effectively suppress tumor cell proliferation, vascularization, and metastasis. It is anticipated that such research efforts will lead to novel DNA-based vaccines that will be effective for the treatment of cancer.

Gene and protein expressions induced by 17beta-estradiol and parathion in cultured breast epithelial cells

Cancer of the breast is the most common form of malignant disease occurring among women of the western world and environmental substances seem to be involved in the etiology of this disease. Many studies have found an association between human cancer and exposure to agricultural pesticides and among them parathion, the organophosphorous pesticide used in agriculture to control mosquito plagues. The association between breast cancer and prolonged exposure to estrogens suggests that this hormone also may have a role in such process. However, the causative factors for breast carcinogenesis remain an enigma. The objective of this study was to determine the effects of 17beta-estradiol (E2) and parathion on cell transformation of human breast epithelial cells in vitro. The results of this study showed that parathion alone and in combination with E2 induced malignant transformation of an immortalized human breast epithelial cell line, MCF-10F, and the malignant feature was confirmed by anchorage independency and invasive capabilities. Parathion alone efficiently elevated the expression of EGFR, c-Kit, Trio, Rac 3, Rho-A, and mutant p53 proteins. Analysis of gene expression using commercially available human cell cycle array revealed transcriptional alterations in 22 out of a total of 96 genes. Among them, nine genes involved in the regulation of cell cycle were altered. These included cyclins (A1, A2, C, G1, G2, and H), cyclin-dependent kinases (CDKs), and minichromosome maintenance deficient (MCM). Results suggest that parathion has the potency to cause malignant transformation of breast epithelial cells through modulation of expression of cell cycle regulated genes.

Gene and protein expressions induced by 17beta-estradiol and parathion in cultured breast epithelial cells

Cancer of the breast is the most common form of malignant disease occurring among women of the western world and environmental substances seem to be involved in the etiology of this disease. Many studies have found an association between human cancer and exposure to agricultural pesticides and among them parathion, the organophosphorous pesticide used in agriculture to control mosquito plagues. The association between breast cancer and prolonged exposure to estrogens suggests that this hormone also may have a role in such process. However, the causative factors for breast carcinogenesis remain an enigma. The objective of this study was to determine the effects of 17beta-estradiol (E2) and parathion on cell transformation of human breast epithelial cells in vitro. The results of this study showed that parathion alone and in combination with E2 induced malignant transformation of an immortalized human breast epithelial cell line, MCF-10F, and the malignant feature was confirmed by anchorage independency and invasive capabilities. Parathion alone efficiently elevated the expression of EGFR, c-Kit, Trio, Rac 3, Rho-A, and mutant p53 proteins. Analysis of gene expression using commercially available human cell cycle array revealed transcriptional alterations in 22 out of a total of 96 genes. Among them, nine genes involved in the regulation of cell cycle were altered. These included cyclins (A1, A2, C, G1, G2, and H), cyclin-dependent kinases (CDKs), and minichromosome maintenance deficient (MCM). Results suggest that parathion has the potency to cause malignant transformation of breast epithelial cells through modulation of expression of cell cycle regulated genes.

Identification of differentially transcribed genes in human lymphoblastoid cells irradiated with 0.5 Gy of gamma-ray and the involvement of low dose radiation inducible CHD6 gene in cell proliferation and radiosensitivity

PURPOSE

To identify candidate genes specifically involved in response to low-dose irradiation in human lymphoblastoid cells; to better clarify the role of the human chromodomain helicase DNA binding protein 6 gene (CHD6), one of these genes, in cell proliferation and radiosensitivity.

MATERIALS AND METHODS

DNA microarray technology was used to analyse global transcriptional profile in human lymphoblastoid AHH-1 cells at 4 h after exposure to 0.5 Gy of gamma-ray. Gene expression changes were confirmed by semi-quantitative reverse transcription--polymerase chain reaction (RT-PCR) and Northern blot. RNA interfering technology was employed to knock-down the CHD6 gene in A549 cells. Colony-forming ability was used to analyse radiosensitivity.

RESULTS

The microarray assay revealed a set of 0.5 Gy-responsive genes, including 30 up-regulated genes and 45 down-regulated genes. The up-regulated genes include a number of genes involved in: signal transduction pathways, e.g., STAT3, CAMKK2, SIRT1, CREM, MAPK3K7IP2 and GPR56; transcription or DNA-binding, e.g., CHD6, CRSP3, SNURF, SH2 domain binding protein 1 and MIZF. Some of the down-regulated genes are involved in: cytoskeleton and cell movement (WASF2, LCP1, MSN, NIPSNAP1, KIF2C); DNA replication and repair (MCM2, MCM3, MCM7 and XRCC-4). Radiation-increased expression of CHD6 was also found in A549 cells and HeLa cells. The sustained CHD6 induction was restricted to relatively low doses (0.2 Gy or 0.5 Gy), no change occurring after 4 Gy irradiation. Silencing of CHD6 mediated by siRNA increased the growth rate of A549 cells by 40 approximately 60%. Most importantly, silencing CHD6 led to an increased radioresistance of A459 cells to radiation doses up to 2 Gy, but barely affected the sensitivity of cells at 4 and 8 Gy.

CONCLUSION

This study has identified a set of genes responsive to 0.5 Gy of gamma-rays. CDH6 gene can be specifically up-regulated by low dose irradiation, and its inducible expression could be involved in a low dose hypersensitive response.

Bystander effect: biological endpoints and microarray analysis

In cell populations exposed to ionizing radiation, the biological effects occur in a much larger proportion of cells than are estimated to be traversed by radiation. It has been suggested that irradiated cells are capable of providing signals to the neighboring unirradiated cells resulting in damage to these cells. This phenomenon is termed the bystander effect. The bystander effect induces persistent, long-term, transmissible changes that result in delayed death and neoplastic transformation. Because the bystander effect is relevant to carcinogenesis, it could have significant implications for risk estimation for radiation exposure. The nature of the bystander effect signal and how it impacts the unirradiated cells remains to be elucidated. Examination of the changes in gene expression could provide clues to understanding the bystander effect and could define the signaling pathways involved in sustaining damage to these cells. The microarray technology serves as a tool to gain insight into the molecular pathways leading to bystander effect. Using medium from irradiated normal human diploid lung fibroblasts as a model system we examined gene expression alterations in bystander cells. The microarray data revealed that the radiation-induced gene expression profile in irradiated cells is different from unirradiated bystander cells suggesting that the pathways leading to biological effects in the bystander cells are different from the directly irradiated cells. The genes known to be responsive to ionizing radiation were observed in irradiated cells. Several genes were upregulated in cells receiving media from irradiated cells. Surprisingly no genes were found to be downregulated in these cells. A number of genes belonging to extracellular signaling, growth factors and several receptors were identified in bystander cells. Interestingly 15 genes involved in the cell communication processes were found to be upregulated. The induction of receptors and the cell communication processes in bystander cells receiving media from irradiated cells supports the active involvement of these processes in inducing bystander effect.

Transcription repressor activity of spleen tyrosine kinase mediates breast tumor suppression

Spleen tyrosine kinase (SYK) is a candidate tumor suppressor gene in breast. Loss of SYK expression in breast tumors as a result of DNA hypermethylation promotes tumor cell proliferation and invasion and predicts shorter survival of breast cancer patients. We previously reported that, in addition to its well-known cytoplasmic localization, the full-length Syk is also present in the nucleus and that Syk nuclear translocation is a rate-limiting step to determine Syk tumor suppressor function. Here, we show that the full-length form of Syk acts as a transcription repressor in the cell nucleus. Ectopic expression of Syk down-regulates the transcription of FRA1 and cyclin D1 oncogenes. This transcription-repressing activity of Syk is associated with its binding to members of the histone deacetylase family. Syk interacts with transcription factor Sp1 at the Sp1 DNA-binding site in the FRA1 promoter to repress Sp1-activated FRA1 transcription. Thus, breast tumorigenesis and progression resulting from the loss of SYK are underscored by the derepression of Sp1-mediated oncogene transcription.

Array comparative genomic hybridisation (aCGH) analysis of premenopausal breast cancers from a nuclear fallout area and matched cases from Western New York

High-resolution array comparative genomic hybridisation (aCGH) analysis of DNA copy number aberrations (CNAs) was performed on breast carcinomas in premenopausal women from Western New York (WNY) and from Gomel, Belarus, an area exposed to fallout from the 1986 Chernobyl nuclear accident. Genomic DNA was isolated from 47 frozen tumour specimens from 42 patients and hybridised to arrays spotted with more than 3000 BAC clones. In all, 20 samples were from WNY and 27 were from Belarus. In total, 34 samples were primary tumours and 13 were lymph node metastases, including five matched pairs from Gomel. The average number of total CNAs per sample was 76 (range 35–134). We identified 152 CNAs (92 gains and 60 losses) occurring in more than 10% of the samples. The most common amplifications included gains at 8q13.2 (49%), at 1p21.1 (36%), and at 8q24.21 (36%). The most common deletions were at 1p36.22 (26%), at 17p13.2 (26%), and at 8p23.3 (23%). Belarussian tumours had more amplifications and fewer deletions than WNY breast cancers. HER2/neu negativity and younger age were also associated with a higher number of gains and fewer losses. In the five paired samples, we observed more discordant than concordant DNA changes. Unsupervised hierarchical cluster analysis revealed two distinct groups of tumours: one comprised predominantly of Belarussian carcinomas and the other largely consisting of WNY cases. In total, 50 CNAs occurred significantly more commonly in one cohort vs the other, and these included some candidate signature amplifications in the breast cancers in women exposed to significant radiation. In conclusion, our high-density aCGH study has revealed a large number of genetic aberrations in individual premenopausal breast cancer specimens, some of which had not been reported before. We identified a distinct CNA profile for carcinomas from a nuclear fallout area, suggesting a possible molecular fingerprint of radiation-associated breast cancer.

Mechanism of radiation-induced bystander effect: role of the cyclooxygenase-2 signaling pathway

The radiation-induced bystander effect is defined as "the induction of biological effects in cells that are not directly traversed by a charged particle but are in close proximity to cells that are." Although these bystander effects have been demonstrated with a variety of biological endpoints in both human and rodent cell lines (as well as in 3D tissue samples), the mechanism of the phenomenon is not known. Although gap junction communication and the presence of soluble mediator(s) are both known to play important roles in the bystander response, the precise signaling molecules have yet to be identified. By using the Columbia University charged particle beam in conjunction with a strip dish design, we show here that the cyclooxygenase-2 (COX-2, also known as prostaglandin endoperoxide synthase-2) signaling cascade plays an essential role in the bystander process. Treatment of bystander cells with NS-398, which suppresses COX-2 activity, significantly reduced the bystander effect. Because the critical event of the COX-2 signaling is the activation of the mitogen-activated protein kinase pathways, our finding that inhibition of the extracellular signal-related kinase phosphorylation suppressed bystander response further confirmed the important role of mitogen-activated protein kinase signaling cascade in the bystander process. These results provide evidence that the COX-2-related pathway, which is essential in mediating cellular inflammatory response, is the critical signaling link for the bystander phenomenon.

Radiation-induced gene expression profile of human cells deficient in 8-hydroxy-2′-deoxyguanine glycosylase

The human OGG1 gene encodes a DNA glycosylase that is involved in the base excision repair of 8-hydroxy-2'-deoxyguanine (8-OH-dG) from oxidatively damaged DNA. Cellular 8-OH-dG levels accumulate in the absence of this activity and could be deleterious for the cell. To assess the role of 8-oxoguanine glycosylase (OGG1) in the cellular defense mechanism in a specific DNA repair defect background, we set out to determine the expression pattern of base excision repair genes and other cellular genes not involved in the base excision pathway in OGG1-deficient human KG-1 cells after ionizing radiation exposure. KG-1 cells have lost OGG1 activity due to a homozygous mutation of Arg229Gln. Gene expression alterations were monitored at 4, 8, 12 and 24 hr in 2 Gy irradiated cells. Large-scale gene expression profiling was assessed with DNA microarray technology. Gene expression analysis identified a number of ionizing radiation-responsive genes, including several novel genes. There were 2 peaks of radiation-induced gene induction or repression: one at 8 hr and the other at 24 hr. Overall the number of downregulated genes was higher than the number of upregulated genes. The highest number of downregulated genes was at 8 hr postirradiation. Genes corresponding to cellular, physiologic, developmental and extracellular processes were identified. The highest number of radiation-induced genes belonged to the signal transduction category, followed by genes involved in transcription and response to stress. Microarray gene expression data were independently validated by relative quantitative RT-PCR. Surprisingly, none of the genes involved in the base excision repair of radiation-induced DNA damage showed altered expression.

Immunochemical analysis of protein expression in breast epithelial cells transformed by estrogens and high linear energy transfer (LET) radiation

Breast cancer is a complex disease involving numerous genetic aberrations. Immunochemical analysis of protein expression is presented in a human breast epithelial cell line neoplastically transformed by high linear energy transfer (LET) alpha particle radiation in the presence of 17beta estradiol (E) and in the parental human breast epithelial cell line (MCF-10F) which served as a non-tumorigenic control. The aim of this work was to determine the levels of mRNA and protein expression in control and transformed cells at various stages of the neoplastic process. The levels of mRNA and protein expression of PCNA, c-fos, JNK2 and Fra-1 were increased in the transformed cell line compared to the levels in non-tumorigenic control cells. The transforming factor Rho A was significantly increased only in the tumor cell line. Furthermore, the levels of mRNA and protein expression of ErbB2 were significantly increased in the transformed cell line and in tumor cells derived from the transformed cells after injecting them into nude mice. A decrease in RbA/p48 protein expression and mRNA levels was observed in cells treated with double doses of alpha particle radiation in the presence of estrogen, regardless of tumorigenicity. Such expression was lower than that in the control untreated MCF-10F cells. In summary, these studies show that estrogen and high LET-radiation induce changes in oncoprotein expression and mRNA levels of human breast cell lines. These changes are indicative of a cascade of events that characterize the process of cell transformation in breast cancer. These results provide evidence that multiple steps with consecutive changes are involved when normal cells become tumorigenic cells as a result of alpha particle irradiation and estrogen treatments.

A DNA vaccine targeting Fos-related antigen 1 enhanced by IL-18 induces long-lived T-cell memory against tumor recurrence

A novel vaccination strategy induced specific CD8(+) T cell-mediated immunity that eradicated spontaneous and experimental pulmonary cancer metastases in syngeneic mice and was also effective in a therapeutic setting of established breast cancer metastases. This was achieved by targeting transcription factor Fos-related antigen 1(Fra-1), overexpressed by many tumor cells, with an ubiquitinated DNA vaccine against Fra-1, coexpressing secretory IL-18. Insight into the immunologic mechanisms involved was provided by adoptive transfer of T lymphocytes from successfully immunized BALB/c mice to syngeneic severe combined immunodeficient (SCID) mice. Specifically, long-lived T memory cells were maintained dormant in nonlymphoid tissues by IL-18 in the absence of tumor antigen. Importantly, a second tumor cell challenge of these SCID mice restored both, robust tumor-specific cytotoxicity and long-lived T-cell memory, capable of eradicating established pulmonary cancer metastases, suggesting that this vaccine could be effective against tumor recurrence.

Constitutive activation of transcription factor AP-1 in cervical cancer and suppression of human papillomavirus (HPV) transcription and AP-1 activity in HeLa cells by curcumin

The transcription factor AP-1 plays a central role in the transcriptional regulation of specific types of high-risk human papillomaviruses (HPVs) such as HPV16 and HPV18, which are etiologically associated with the development of cancer of the uterine cervix in women. In our study, we investigated the AP-1 binding activity and the expression pattern of different members of the AP-1 transcription factor family (c-Jun, JunB, JunD, c-Fos, FosB, Fra-1 and Fra-2) in different grades of cervical lesions starting from mild dysplasia to invasive cervical tumors, including normal control tissues, using specific antibodies raised against each of the AP-1 members. Results indicate that though AP-1 showed high binding activity and the majority of its members were highly expressed in tumor tissues, there is a distinct pattern of gradual increase of c-fos and a concomitant decrease of fra-1 expression that perfectly match the progression of cervical lesions. While c-fos is highly expressed in invasive cervical tumor, the expression of fra-1 becomes almost nil or absent, but the reverse is true in both controls and early precancerous lesions. These findings corroborate the results obtained in the cervical cancer cell line, HeLa. Interestingly, despite very low or absent AP-1 binding in normal as well as in premalignant lesions, AP-1 transcription and its binding activity was found to be very high in malignant tissues showing a preferential heterodimerization of c-fos with JunB instead of its canonical dimerization partner c-jun. Both in vivo and in vitro studies demonstrate that the overexpression of c-fos and downregulation of fra-1 expression as well as a change in the dimerization pattern of the AP-1 complex seem to play a crucial role during progression to malignancy. In a previous study, we demonstrated that a synthetic antioxidant, pyrrolidine dithiocarbamate (PDTC) can selectively downregulate HPV expression in human keratinocytes and cervical cancer cell lines. Since a redox regulatory pathway is involved in the expression of HPV that can be modulated by an antioxidant-induced reconstitution of the AP-1 transcription complex, we have used curcumin (diferuloylmethane), an active component of the perennial herb turmeric, which is a potent antioxidant and is well-known for its antiinflammatory and anticarcinogenic activity, to modulate the transcription of AP-1 and HPV. We demonstrate for the first time that curcumin can selectively downregulate HPV18 transcription as well as the AP-1 binding activity in HeLa cells. Most interestingly, curcumin can reverse the expression dynamics of c-fos and fra-1 in this tumorigenic cell line, mimicking the expression pattern observed in normal controls or precancerous lesions. Observation of curcumin-mediated complete downregulation of AP-1 binding activity and reversal of c-fos/fra-1 transcription to a normal state in tumorigenic HeLa cells represents a novel mechanism that can control transcription of pathogenic HPVs during keratinocyte differentiation and progression of cervical cancer. Our study thus provides a basis for developing a novel therapeutic approach to control pathogenic HPV infection by using potent antioxidative agents, such as curcumin.

Matrix metalloproteinase/epidermal growth factor receptor/mitogen-activated protein kinase signaling regulate fra-1 induction by cigarette smoke in lung epithelial cells

Exposure to cigarette smoke (CS) can lead to the development of lung cancer, but the molecular mechanisms underlying this process remain unclear. Given that activator protein 1 (AP-1) regulates genes involved in both physiologic and pathophysiologic processes, we have investigated the effects of CS on Jun and Fos family member expression and regulation using a nonmalignant human bronchial epithelial cell line, 1HAEo. Exposure to CS caused a marked upregulation of c-Jun, c-Fos, and Fra-1, but not of Fra-2, Jun-B, and Jun-D expression. Because Fra-1 is overexpressed in various tumors and upregulates genes associated with tumor progression, we further elucidated the mechanisms that control CS-stimulated fra-1 induction. CS stimulated fra-1 induction primarily at the transcriptional level. However, epidermal growth factor receptor (EGFR)-specific inhibitor, AG1478, completely suppressed CS-stimulated fra-1 expression. Similarly, the specific inhibitors of extracellular signal-regulated kinase (ERK), c-Jun NH2 terminal kinase (JNK), and p38 kinase signaling markedly suppressed fra-1 induction. Consistent with this finding, AG1478 blocked CS-stimulated ERK, JNK, and p38 phosphorylation. These results suggest that EGFR-activated multiple kinase signaling is essential for fra-1 induction. Furthermore, treatment of cells with GM6001, which inhibits matrix metalloproteinase activity, significantly suppressed CS-stimulated EGF shedding, EGFR and ERK kinase phosphorylation, and subsequent fra-1 induction. Collectively, our findings indicate an obligatory role for metalloproteinase-EGFR-mediated mitogen-activated protein kinase signaling in controlling CS-induced fra-1 expression.

DNA vaccines suppress tumor growth and metastases by the induction of anti-angiogenesis

Four novel oral DNA vaccines provide long-lived protection against melanoma, colon, breast, and non-small cell lung carcinoma in mouse model systems. The vaccines are delivered by attenuated Salmonella typhimurium to secondary lymphoid organs and are directed against targets such as carcinoembryonic antigen, tyrosine-related protein, vascular endothelial growth factor receptor-2 [also called fetal liver kinase-1 (FLK-1)], and transcription factor Fos-related antigen-1 (Fra-1). The FLK-1 and Fra-1 vaccines are effective in suppressing angiogenesis in the tumor vasculature. All four vaccines are capable of inducing potent cell-mediated protective immunity, breaking peripheral T-cell tolerance against these self-antigens resulting in effective suppression of tumor growth and metastasis. It is anticipated that such research efforts will contribute toward the rational design of future DNA vaccines that will be effective for prevention and treatment of human cancer.

DNA vaccines designed to inhibit tumor growth by suppression of angiogenesis

The development of new blood vessels, i.e. angiogenesis, is a rate-limiting step in the development of tumors since tumor growth is generally limited to 1-2 mm3 in the absence of a blood supply. Thus, the inhibition of tumor growth by attacking the tumor's vascular supply offers a primary target for antiangiogenic intervention by DNA-based vaccines. Here, we describe two novel orally delivered DNA vaccines which suppress tumor angiogenesis and induce a robust cell-mediated immune response that provides for long-lived protection against melanoma, colon, breast and non-small-cell lung carcinoma in mouse model systems. These vaccines, which are delivered by attenuated Salmonella typhimurium to secondary lymphoid organs, are directed against such targets as vascular endothelial growth factor receptor 2 (FLK-1) and transcription factor Fos-related antigen 1 (Fra-1). Both vaccines break peripheral T cell tolerance against these self-antigens and induce a robust T cell-mediated immune response leading to suppression of tumor angiogenesis and resulting in effective suppression of tumor growth and metastases. Such research efforts may open up new possibilities for the rational design of future DNA vaccines effective for the prevention and treatment of cancer.

Genomic instability and bystander effects induced by high-LET radiation

An understanding of the radiobiological effects of high-linear energy transfer (LET) radiation is essential for radiation protection and human risk assessment. Ever since the discovery of X-rays was made by Röntgen more than a century ago, it has always been accepted that the deleterious effects of ionizing radiation, such as mutation and carcinogenesis, are due mainly to direct damage to DNA. With the availability of a precision single-particle microbeam, it is possible to demonstrate, unequivocally, the presence of a bystander effect with many biological end points. These studies provide clear evidence that irradiated cells can induce a bystander mutagenic response in neighboring cells not directly traversed by alpha-particles, and that cell-cell communication processes play a critical role in mediating the bystander phenomenon. Following exposure to high-LET radiation, immortalized human bronchial (BEP2D) and breast (MCF-10F) cells have been shown to undergo malignant transformation through a series of successive steps, before becoming tumorigenic in nude mice. There is a progressive increase in genomic instability, determined either by gene amplification or allelic imbalance, with the highest incidence observed among established tumor cell lines, relative to transformed, nontumorigenic and control cell lines.

Role of Vitamin D receptor gene in radiation-induced neoplastic transformation of human breast epithelial cell

1 Alpha,25-(OH)(2)-Vitamin D(3), the physiologically active metabolite of Vitamin D is known for its pro-differentiating and antiproliferative activity on various cancer cell lines. It exerts its growth-regulatory effects through binding to the Vitamin D recepter (VDR), a member of the steroid/thyroid/retinoic acid receptor family, which functions as a ligand-dependent transcription factor. There is accumulating evidence that Vitamin D may be an important determinant of both the occurrence and progression of breast cancer. Since radiation is an important etiological factor for breast cancer progression, it is important to study the role of VDR gene in radiation-induced breast carcinogenesis. This study is focused on a human breast tumor model developed by irradiating the spontaneously immortalized MCF-10F cell line with graded doses of high-linear energy transfer (LET) radiation followed by treatment with estrogen. Study of VDR gene by restriction digestion with ApaI, BsmI and TaqI detected no polymorphism but direct sequencing analyses identified few single-base mutations within intron 8 and exon 9 of the gene. Over-expression of the VDR gene was noticed in irradiated and tumorigenic cell lines compared with control. Likewise, immunohistochemical data indicated a significant increase in VDR intensity in irradiated and tumorigenic cell lines. Considering all these evidence, it is likely that VDR can be used as a prognostic marker of tumor progression in radiation- and estrogen-induced breast carcinogenesis.

Transcription factor Fos-related antigen 1 is an effective target for a breast cancer vaccine

Protection against breast cancer was achieved with a DNA vaccine against murine transcription factor Fos-related antigen 1, which is overexpressed in aggressively proliferating D2F2 murine breast carcinoma. Growth of primary s.c. tumor and dissemination of pulmonary metastases was markedly suppressed by this oral DNA vaccine, carried by attenuated Salmonella typhimurium, encoding murine Fos-related antigen 1, fused with mutant polyubiquitin, and cotransformed with secretory murine IL-18. The life span of 60% of vaccinated mice was tripled in the absence of detectable tumor growth after lethal tumor cell challenge. Immunological mechanisms involved activation of T, natural killer, and dendritic cells, as indicated by up-regulation of their activation markers and costimulatory molecules. Markedly increased specific target cell lysis was mediated by both MHC class I-restricted CD8+ T cells and natural killer cells isolated from splenocytes of vaccinated mice, including a significant release of proinflammatory cytokines IFN-gamma and IL-2. Importantly, fluorescence analysis of fibroblast growth factor 2 and tumor cell-induced vessel growth in Matrigel plugs demonstrated marked suppression of angiogenesis only in vaccinated animals. Taken together, this multifunctional DNA vaccine proved effective in protecting against growth and metastases of breast cancer by combining the action of immune effector cells with suppression of tumor angiogenesis.

Rapid cycling bipolar disease: new concepts and treatments

Having been recognized by Kraeplin at the beginning of the 20th century, rapid cycling was first described as a specific entity by Dunner et al. in 1974. The prevalence of rapid cycling ranges from 12% to 20% in patients with bipolar disorder who are not selected for a high rate of cycling.