Dysregulated Expression Patterns of Circular RNAs in Cancer: Uncovering Molecular Mechanisms and Biomarker Potential.

Circular RNAs (circRNAs) are stable, enclosed, non-coding RNA molecules with dynamic regulatory propensity. Their biogenesis involves a back-splicing process, forming a highly stable and operational RNA molecule. Dysregulated circRNA expression can drive carcinogenic and tumorigenic transformation through the orchestration of epigenetic modifications via extensive RNA and protein-binding domains. These multi-ranged functional capabilities have unveiled extensive identification of previously unknown molecular and cellular patterns of cancer cells. Reliable circRNA expression patterns can aid in early disease detection and provide criteria for genome-specific personalized medicine. Studies described in this review have revealed the novelty of circRNAs and their biological ss as prognostic and diagnostic biomarkers.

Gene expression profiling identifies potential molecular markers of papillary thyroid carcinoma.

BACKGROUND: Thyroid cancer is the most common endocrine malignancy worldwide, with the predominant form papillary thyroid carcinoma (PTC) representing approximately 80% of cases. OBJECTIVE: This study was addressed to identify potential genes and pathways involved in the pathogenesis of PTC and potential novel biomarkers for this disease. METHODS: Gene expression profiling was carried out by DNA microarray technology. Validation of microarray data by qRT-PCR, western blot, and enzyme linked immunosorbent assay was also performed in a selected set of genes and gene products, with the potential to be used as diagnostic or prognostic biomarkers, such as those associated with cell adhesion, extracellular matrix (ECM) remodeling and immune/inflammatory response. RESULTS: In this study we found that upregulation of extracellular activities, such as proteoglycans, ECM-receptor interaction, and cell adhesion molecules, were the most prominent feature of PTC. Significantly over-expressed genes included SDC1 (syndecan 1), SDC4 (syndecan 4), KLK7 (kallikrein-related peptidase 7), KLK10 (kallikrein-related peptidase 10), SLPI (secretory leukocyte peptidase inhibitor), GDF15 (growth/differentiation factor-15), ALOX5 (arachidonate 5-lipoxygenase), SFRP2 (secreted Frizzled-related protein 2), among others. Further, elevated KLK10 levels were detected in patients with PTC. Many of these genes belong to KEGG pathway "Proteoglycans in cancer". CONCLUSIONS: Using DNA microarray analysis allowed the identification of genes and pathways with known important roles in malignant transformation, and also the discovery of novel genes that may be potential biomarkers for PTC.

Ethanol Enhances Estrogen Mediated Angiogenesis in Breast Cancer.

Angiogenesis, a highly regulated process, is exploited by tumors like breast cancer to ensure a constant supply of oxygen and nutrients and is key for tumor survival and progression. Estrogen and alcohol independently have been observed to contribute to angiogenesis in breast cancer but their combinatorial effects have never been evaluated. The exact mechanism by which estrogen and alcohol contribute to breast cancer angiogenesis remains to be elucidated. In this study, we defined the in vitro effects of the combination of estrogen and alcohol in breast cancer angiogenesis using the tubulogenesis and scratch wound assays. Conditioned media, generated by culturing the murine mammary cancer cell line, TG1-1, in estrogen and ethanol, enhanced tubule formation and migration as well as modulated the MAP Kinase pathway in the murine endothelial cell line, SVEC4-10. Additionally, estrogen and ethanol in combination enhanced the expression of the pro-angiogenic factors VEGF, MMP-9, and eNOS, and modulated Akt activation. These observations suggest that TG1-1 cells secrete pro-angiogenic molecules in response to the combination of estrogen and ethanol that modulate the morphological and migratory properties of endothelial cells. The data presented in this study, is the first in attempting to link the cooperative activity between estrogen and ethanol in breast cancer progression, underscoring correlations first made by epidemiological observations linking the two.

Hyperactive ERK and persistent mTOR signaling characterize vemurafenib resistance in papillary thyroid cancer cells.

Clinical studies evaluating targeted BRAFV600E inhibitors in advanced thyroid cancer patients are currently underway. Vemurafenib (BRAFV600E inhibitor) monotherapy has shown promising results thus far, although development of resistance is a clinical challenge. The objective of this study was to characterize development of resistance to BRAFV600E inhibition and to identify targets for effective combination therapy. We created a line of BCPAP papillary thyroid cancer cells resistant to vemurafenib by treating with increasing concentrations of the drug. The resistant BCPAP line was characterized and compared to its sensitive counterpart with respect to signaling molecules thought to be directly related to resistance. Expression and phosphorylation of several critical proteins were analyzed by Western blotting and dimerization was evaluated by immunoprecipitation. Resistance to vemurafenib in BCPAP appeared to be mediated by constitutive overexpression of phospho-ERK and by resistance to inhibition of both phospho-mTOR and phospho-S6 ribosomal protein after vemurafenib treatment. Expression of potential alternative signaling molecule, CRAF, was not increased in the resistant line, although formation of CRAF dimers appeared increased. Expression of membrane receptors HER2 and HER3 was greatly amplified in the resistant cancer cells. Papillary thyroid cancer cells were capable of overcoming targeted BRAFV600E inhibition by rewiring of cell signal pathways in response to prolonged vemurafenib therapy. Our study suggests that in vitro culture of cancer cells may be useful in assessing molecular resistance pathways. Potential therapies in advanced thyroid cancer patients may combine vemurafenib with inhibitors of CRAF, HER2/HER3, ERK, and/or mTOR to delay or abort development of resistance.

PLX4032 Mediated Melanoma Associated Antigen Potentiation in Patient Derived Primary Melanoma Cells.

Over expression of various immunogenic melanoma associated antigens (MAAs) has been exploited in the development of immunotherapeutic melanoma vaccines. Expression of MAAs such as MART-1 and gp100 is modulated by the MAPK signaling pathway, which is often deregulated in melanoma. The protein BRAF, a member of the MAPK pathway, is mutated in over 60% of melanomas providing an opportunity for the identification and approval by the FDA of a small molecule MAPK signaling inhibitor PLX4032 that functions to inactivate mutant BRAF(V600E). To this end, we characterized five patient derived primary melanoma cell lines with respect to treatment with PLX4032. Cells were treated with 5µM PLX4032 and harvested. Western blotting analysis, RT-PCR and in vitro transwell migration and invasion assays were utilized to determine treatment effects. PLX4032 treatment modulated phosphorylation of signaling proteins belonging to the MAPK pathway including BRAF, MEK, and ERK and abrogated cell phenotypic characteristics such as migration and invasion. Most significantly, PLX4032 led to an up regulation of many MAA proteins in three of the four BRAF mutated cell lines, as determined at the protein and RNA level. Interestingly, MAGE-A1 protein and mRNA levels were reduced upon PLX4032 treatment in two of the primary lines. Taken together, our findings suggest that the BRAF(V600E) inhibitor PLX4032 has therapeutic potential over and above its known target and in combination with specific melanoma targeting vaccine strategies may have further clinical utility.

Disruption of mutated BRAF signaling modulates thyroid cancer phenotype.

BACKGROUND: Thyroid cancer is the most common endocrine-related cancer in the United States and its incidence is rising rapidly. Since among various genetic lesions identified in thyroid cancer, the BRAFV600E mutation is found in 50% of papillary thyroid cancers and 25% of anaplastic thyroid cancers, this mutation provides an opportunity for targeted drug therapy. Our laboratory evaluated cellular phenotypic effects in response to treatment with PLX4032, a BRAFV600E-specific inhibitor, in normal BRAF-wild-type thyroid cells and in BRAFV600E-positive papillary thyroid cancer cells. METHODS: Normal BRAF-wild-type thyroid cells and BRAFV600E-mutated papillary thyroid cancer cells were subjected to proliferation assays and analyzed for cell death by immunofluorescence. Cell cycle status was determined using an EdU uptake assay followed by laser scanning cytometry. In addition, expression of proteins within the MAPK signal transduction pathway was analyzed by Western blot. RESULTS: PLX4032 has potent anti-proliferative effects selectively in BRAF-mutated thyroid cancer cells. These effects appear to be mediated by the drug's activity of inhibiting phosphorylation of signaling molecules downstream of BRAF within the pro-survival MAPK pathway. Interestingly, PLX4032 promotes the phosphorylation of these signaling molecules in BRAF-wild-type thyroid cells. CONCLUSIONS: These findings support further evaluation of combinational therapy that includes BRAFV600E inhibitors in thyroid cancer patients harboring the BRAFV600E mutation.

Ex vivo derived primary melanoma cells: implications for immunotherapeutic vaccines.

Transformation of the pigment producing melanocytes into melanoma is a complex multi-step process involving the enhanced expression of various antigens considered as immunotherapeutic targets. Significant progress in melanoma research has been made over the years and has resulted in the identification of various antigens over expressed in melanoma as well as advances in immunotherapeutic treatments, which focus on modulating the immune systems response to melanoma. Despite these advances, incidences of melanoma are still on the rise thus warranting additional research in identifying new therapeutic treatments. Our focus is on developing a multivalent immunotherapeutic vaccine that targets various melanoma associated antigens. The approach focuses on the use of five primary patient derived melanoma cells (MEL-2, MEL-V, 3MM, KFM, and GLM-2, which have been characterized in this study. These cells express differential amounts of various melanoma associated antigens such as MART-1, gp100 (Pmel17), MAGE-A1 and tyrosinase as well a cell surface antigens essential for melanoma cell metastasis, such as CD146 and CD71. In addition these cells display differential in vitro migratory and invasive properties as well as have the ability to form solid tumors when implanted into BALB/c nude mice. The retention of the innate phenotype of these primary patient derived cells together with the expression of a multitude repertoire of melanoma associated antigens offers a novel opportunity to target melanoma so as to avoid immune evasion.

Follow-up analysis of a randomized phase III immunotherapeutic clinical trial on melanoma.

Development of a melanoma-specific vaccine is of clinical necessity. Therefore, a phase III, randomized, double-blind trial was performed (June 1988-June 1991) to assess the clinical effectiveness of our vaccinia melanoma oncolysate (VMO) vaccine in stage III melanoma patients. Patient data were collected from 11 institutions, as well as from the Social Security Death Index and were analyzed from April through August 2008 for disease-free interval (DFI) and overall survival (OS). The median OS for patients who were administered the VMO vaccine was 7.71 years, compared to 7.95 years for patients administered the vaccinia virus vaccine (V) (p=0.70). The median DFI for the VMO group was six years, while the median DFI for the V group has not yet been reached. This analysis demonstrated a statistically significant difference in OS in females in both groups (VMO, 79%; V, 92%), as compared to males (VMO, 57%; V, 68%) (p=0.0473). This follow-up analysis demonstrated that females had a survival advantage over males, thus warranting further investigation. This significant observation may facilitate the recruitment of patients for future clinical trials, as well as determine which patients are more likely to benefit from receiving the VMO vaccine.

Hypoxia and estrogen are functionally equivalent in breast cancer-endothelial cell interdependence.

BACKGROUND: Rapid breast tumor development relies on formation of new vasculature to supply the growing malignancy with oxygenated blood. Previously we found that estrogen aided in this neovasculogenesis via recruitment of bone marrow derived endothelial progenitor cells (BM-EPCs), leading to increased vessel formation and vascular endothelial growth factor (VEGF) production in vivo. However, the cellular mechanism of this induction and the signaling pathways involved need elucidation. RESULTS: Using the murine mammary cell line TG1-1 we observed estrogen (E2) lead to an up regulation of hypoxia inducible factor-1 (HIF-1), an effect abrogated by the anti-estrogen Fulvestrant and the HIF-1 inhibitor YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole) suggesting the interchangeability of hypoxia and estrogen mediated effects. Estrogen modulation of HIF-1 and subsequent effects on endothelial cells is dependent on the Akt/PI3K pathway and protein synthesis as validated by the use of the inhibitors wortmannin and cycloheximide which abrogated estrogen's effects respectively. Estrogen treated TG1-1 cells secreted higher levels of VEGF which were comparable to secreted levels from cells grown under hypoxic conditions. Soluble factors in conditioned media from E2 treated breast cancer cells also lead to migration and tube formation of human umbilical vein endothelial cells (HUVEC) in vitro. CONCLUSIONS: Our data provide evidence that estrogen signaling mediates the tumor vasculogenic process required for breast cancer progression and involves a key regulator of the hypoxia signaling pathway. Further, hypoxia and estrogen are interchangeable as both similarly modulate epithelial-endothelial cell interaction.

Molecular target based combinational therapeutic approaches in thyroid cancer.

BACKGROUND: Thyroid cancer, as with other types of cancer, is dependent on angiogenesis for its continued growth and development. Interestingly, estrogen has been shown to contribute to thyroid cancer aggressiveness in vitro, which is in full support of the observed increased incidence of thyroid cancer in women over men. Provided that estrogen has been observed to contribute to increased angiogenesis of estrogen responsive breast cancer, it is conceivable to speculate that estrogen also contributes to angiogenesis of estrogen responsive thyroid cancer. METHODS: In this study, three human thyroid cancer cells (B-CPAP, CGTH-W-1, ML-1) were treated with estrogen alone or estrogen and anti-estrogens (fulvestrant and 3,3'-diindolylmethane, a natural dietary compound) for 24 hours. The cell culture media was then added to human umbilical vein endothelial cell (HUVECs) and assayed for angiogenesis associated events. Vascular endothelial growth factor (VEGF) levels were also quantified in the conditioned media so as to evaluate if it is a key player involved in these observations. RESULTS: Conditioned medium from estrogen treated thyroid cancer cells enhanced phenotypical changes (proliferation, migration and tubulogenesis) of endothelial cells typically observed during angiogenesis. These phenotypic changes observed in HUVECs were determined to be modulated by estrogen induced secretion of VEGF by the cancer cells. Lastly, we show that VEGF secretion was inhibited by the anti-estrogens, fulvestrant and 3,3'-diindolylmethane, which resulted in diminished angiogenesis associated events in HUVECs. CONCLUSION: Our data establishes estrogen as being a key regulator of VEGF secretion/expression in thyroid cells which enhances the process of angiogenesis in thyroid cancer. These findings also suggest the clinical utility of anti-estrogens as anti-angiogenic compounds to be used as a therapeutic means to treat thyroid cancer. We also observed that 3,3'-diindolylmethane is a promising naturally occurring anti-estrogen which can be used as a part of therapeutic regimen to treat thyroid cancer.

Synthetic Toll like receptor-4 (TLR-4) agonist peptides as a novel class of adjuvants.

BACKGROUND: Adjuvants serve as catalysts of the innate immune response by initiating a localized site of inflammation that is mitigated by the interactions between antigens and toll like receptor (TLR) proteins. Currently, the majority of vaccines are formulated with aluminum based adjuvants, which are associated with various side effects. In an effort to develop a new class of adjuvants, agonists of TLR proteins, such as bacterial products, would be natural candidates. Lipopolysaccharide (LPS), a major structural component of gram negative bacteria cell walls, induces the systemic inflammation observed in septic shock by interacting with TLR-4. The use of synthetic peptides of LPS or TLR-4 agonists, which mimic the interaction between TLR-4 and LPS, can potentially regulate cellular signal transduction pathways such that a localized inflammatory response is achieved similar to that generated by adjuvants. METHODOLOGY/PRINCIPAL FINDINGS: We report the identification and activity of several peptides isolated using phage display combinatorial peptide technology, which functionally mimicked LPS. The activity of the LPS-TLR-4 interaction was assessed by NF-κB nuclear translocation analyses in HEK-BLUE™-4 cells, a cell culture model that expresses only TLR-4, and the murine macrophage cell line, RAW264.7. Furthermore, the LPS peptide mimics were capable of inducing inflammatory cytokine secretion from RAW264.7 cells. Lastly, ELISA analysis of serum from vaccinated BALB/c mice revealed that the LPS peptide mimics act as a functional adjuvant. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate the identification of synthetic peptides that mimic LPS by interacting with TLR-4. This LPS mimotope-TLR-4 interaction will allow for the development and use of these peptides as a new class of adjuvants, namely TLR-4 agonists.

Estrogen activity as a preventive and therapeutic target in thyroid cancer.

Thyroid cancer is the most common endocrine-related cancer with increasing incidences during the last five years. Interestingly, according to the American Thyroid Association, the incidences of thyroid proliferative diseases occur four to five times more in women than in men with the risk of developing thyroid disorders being one in every eight females. Several epidemiological studies have suggested a possible correlation between incidences of thyroid malignancies and hormones but the precise contribution of estrogen in thyroid proliferative disease initiation, and progression is not well understood. This review is an attempt to define the phenotypic and genotypic modulatory effects of estrogen on thyroid proliferative diseases. The significance and relevance of expression of estrogen receptors, α and ß, in normal and malignant thyroid tissues and their effects on different molecular pathways involved in growth and function of the thyroid gland are discussed. These novel findings open up areas of developing alternative therapeutic treatments and preventive approaches which employ the use of antiestrogen to treat thyroid malignancies.

Estrogen-mediated angiogenesis in thyroid tumor microenvironment is mediated through VEGF signaling pathways.

OBJECTIVES: To explore the induction of a proangiogenic phenotype in endothelial cells in the thyroid tumor microenvironment by estrogen-treated thyroid cancer cells and to define the role of vascular endothelial growth factor (VEGF) in this interaction. DESIGN: Cell-based in vitro systems analysis. SUBJECTS: Thyroid tumor cell lines (BCPAP [papillary thyroid cancer] and ML-1 [follicular thyroid cancer]) were cultured with estradiol with and without an estrogen receptor (ER) inhibitor (fulvestrant or ICI) and used to treat human umbilical vein endothelial cells (HUVECs). INTERVENTIONS: Immunofluorescence was used to confirm the presence of ERα and ERß in BCPAP cells. Conditioned medium was then used to evaluate the induction of HUVEC tubulogenesis and migration. Secretion of VEGF in this medium was evaluated by Western blot analysis. The expression of phosphoinositide 3-kinase (PI3K), the initiator of a proangiogenic pathway, was evaluated with Western blot analysis of HUVEC lysates. The subsequent effects of an ER inhibitor (fulvestrant/ICI) and a neutralizing VEGF antibody were also observed. RESULTS: Estrogen receptor α and ERß are expressed in thyroid cancer cells. Estrogen-stimulated ML-1 cells secreted an increased amount of VEGF likely as a result of ER signaling. In contact with this environment, HUVECs demonstrate enhanced tubulogenesis and migration. Western blot analysis documented estrogen-mediated upregulation of PI3K in HUVECs. These effects were mitigated by an ER inhibitor (fulvestrant/ICI) and a neutralizing VEGF antibody. CONCLUSIONS: Our data provide evidence that estrogen can induce a proangiogenic endothelial cell phenotype in the thyroid tumor microenvironment through ER and VEGF signaling. Our findings suggest that the effect of antiestrogenic therapy targeting tumor angiogenesis can be enhanced through VEGF inhibition.

Endothelial progenitor cell biology in disease and tissue regeneration.

Endothelial progenitor cells are increasingly being studied in various diseases ranging from ischemia, diabetic retinopathy, and in cancer. The discovery that these cells can be mobilized from their bone marrow niche to sites of inflammation and tumor to induce neovasculogenesis has afforded a novel opportunity to understand the tissue microenvironment and specific cell-cell interactive pathways. This review provides a comprehensive up-to-date understanding of the physiological function and therapeutic utility of these cells. The emphasis is on the systemic factors that modulate their differentiation/mobilization and survival and presents the challenges of its potential therapeutic clinical utility as a diagnostic and prognostic reagent.

Identification of PSA peptide mimotopes using phage display peptide library.

Prostate cancer (PCa) is one of the most common types of cancer in men in the United States and is the second leading cause of cancer related death in men. Clinically, secreted prostate specific antigen (PSA) has gained recognition because of its proteolytic activity being directly linked to PCa cell proliferation leading to disease initiation and progression. Using phage display technology, we identified four distinct cyclical peptides. These peptides apart from differences in their amino acid sequence, elicited minimal cross reactive antibody responses against each other. One of the four peptides analyzed produced an antibody response that recognizes the PSA protein. We demonstrate that the synthetic PSA peptide mimics identified in our study are immunologically active and produce neutralizing activity and this has relevance and utility for prostate cancer disease progression.

3,3'-diindolylmethane modulates estrogen metabolism in patients with thyroid proliferative disease: a pilot study.

BACKGROUND: The incidence of thyroid cancer is four to five times higher in women than in men, suggesting a role for estrogen (E2) in the pathogenesis of thyroid proliferative disease (TPD) that comprises cancer and goiter. The objective of this study was to investigate the antiestrogenic activity of 3,3'-diindolylmethane (DIM), a bioactive compound derived from cruciferous vegetables, in patients with TPD. METHODS: In this limited phase I clinical trial study, patients found to have TPD were administered 300 mg of DIM per day for 14 days. Patients subsequently underwent a total or partial thyroidectomy, and tissue, urine, and serum samples were collected. Pre- and post-DIM serum and urine samples were analyzed for DIM levels as well as estrogen metabolites. DIM levels were also determined in thyroid tissue samples. RESULTS: DIM was detectable in thyroid tissue, serum, and urine of patients after 14 days of supplementation. Urine analyses revealed that DIM modulated estrogen metabolism in patients with TPD. There was an increase in the ratio of 2-hydroxyestrones (C-2) to 16α-hydroxyestrone (C-16), consistent with antiestrogenic activity that results in more of C-2 product compared with C-16. CONCLUSION: Our data suggest that DIM enhances estrogen metabolism in TPD patients and can potentially serve as an antiestrogenic dietary supplement to help reduce the risk of developing TPD. The fact that DIM is detected in thyroid tissue implicates that it can manifest its antiestrogenic activity in situ to modulate TPD.

Estrogen induced metastatic modulators MMP-2 and MMP-9 are targets of 3,3'-diindolylmethane in thyroid cancer.

BACKGROUND: Thyroid cancer is the most common endocrine related cancer with increasing incidences during the past five years. Current treatments for thyroid cancer, such as surgery or radioactive iodine therapy, often require patients to be on lifelong thyroid hormone replacement therapy and given the significant recurrence rates of thyroid cancer, new preventive modalities are needed. The present study investigates the property of a natural dietary compound found in cruciferous vegetables, 3,3'-diindolylmethane (DIM), to target the metastatic phenotype of thyroid cancer cells through a functional estrogen receptor. METHODOLOGY/PRINCIPAL FINDINGS: Thyroid cancer cell lines were treated with estrogen and/or DIM and subjected to in vitro adhesion, migration and invasion assays to investigate the anti-metastatic and anti-estrogenic effects of DIM. We observed that DIM inhibits estrogen mediated increase in thyroid cell migration, adhesion and invasion, which is also supported by ER-α downregulation (siRNA) studies. Western blot and zymography analyses provided direct evidence for this DIM mediated inhibition of E(2) enhanced metastasis associated events by virtue of targeting essential proteolytic enzymes, namely MMP-2 and MMP-9. CONCLUSION/SIGNIFICANCE: Our data reports for the first time that DIM displays anti-estrogenic like activity by inhibiting estradiol enhanced thyroid cancer cell proliferation and in vitro metastasis associated events, namely adhesion, migration and invasion. Most significantly, MMP-2 and MMP-9, which are known to promote and enhance metastasis, were determined to be targets of DIM. This anti-estrogen like property of DIM may lead to the development of a novel preventive and/or therapeutic dietary supplement for thyroid cancer patients by targeting progression of the disease.

Identification of peptide mimotopes of gp96 using single-chain antibody library.

Heat shock proteins such as gp96 are immunogenic and are widely used as vaccines in immunotherapy of cancers. The present study focuses on the use of peptide mimotopes as immunotherapeutic vaccines for prostate cancer. To this end, we developed a 15-mer gp96 peptide mimotope specifically reactive to MAT-LyLu gp96-peptide complex using combinatorial single-chain antibody and peptide phage display library. The immunogenicity of the synthesized gp96 mimotope was analyzed initially in normal BALB/c mice in combination with various adjuvants such as complete Freund's adjuvant (CFA), aluminum salts (ALUM), granulocyte-macrophage colony-stimulating factor (GM-CSF), and liposome, of which CFA served as a positive control. The antibody response was determined and found that the gp96 mimotope with ALUM showed a significant increase in antibody titer, followed by GM-CSF and liposomes. Further, the T cell (CD4(+) and CD8(+)) populations from splenocytes, as well as IgG isotypes, interleukin-4, and interleukin-5 of gp96 mimotope with ALUM-immunized animals, were analyzed. The results suggest that the gp96 mimotope may elicit a potent and effective antitumor antibody response. Further, the study identifies ALUM and GM-CSF as adjuvant options to drive an appropriate protective immune response as these adjuvants have prior use in humans.

Estradiol-mediated tumor neo-vascularization.

Neo-vascularization is essential for tumor growth and metastasis and is presumably initiated by bone marrow-derived endothelial progenitor cells (BM-EPCs). These cells predominantly reside in the bone marrow and are recruited at sites of inflammation, tissue damage and tumors. The tissue-specific factors responsible for recruitment of BM-EPCs and neo-vascularization are the subject of intense investigation. Using bone marrow cells from Tek/green fluorescent protein (GFP) transgenic mice, we analyzed the effect of estrogen on the mobilization of BM-EPCs to orthotopically implanted cancer cells in estrogen- and non-estrogen-supplemented ovariectomized mice. The donor marrow cells were unique as they were fluorescently tagged, allowing for the tracking of their migration to the tumor tissues. Results showed that GFP + BM-EPCs were incorporated within the tumor vasculature in comparison to the sham injections. Notably, estrogen supplementation enhanced the mobilization of BM-EPCs to the tumor site. This elevation shows that estrogen may affect tumor neo-vascularization by inducing the mobilization of BM-EPCs. Understanding and characterizing the mechanism involved in the estrogen-induced mobilization of BM-EPCs may serve as a 'Trojan horse' in the delivery of bio-molecules that may disrupt tumor vasculogenesis and induce the targeted killing of tumor cells.

3,3'-diindolylmethane inhibits migration and invasion of human cancer cells through combined suppression of ERK and AKT pathways.

Metastasis of cancer is a multifactorial disease and is the main cause of death in patients with malignancy. This disease demands treatments which may target multiple dysregulated cellular pathways in cancer cells. The anti-tumor and anti-metastatic properties of natural products in cancer prevention have been confirmed by several epidemiological studies, with cruciferous vegetables being especially protective against many cancers. In this study, we evaluated the anti-carcinogenic effects of 3,3'-diindolylmethane (DIM), which is a bioactive compound present in cruciferous vegetables and a widely used dietary supplement, on events commonly observed during metastasis using in vitro adhesion, migration and invasion assays. Our results indicate that DIM inhibits human cancer cell in vitro proliferation, adhesion, migration and invasion. Western blot analyses show that this inhibition of cell proliferation by DIM is exerted by combined suppression of AKT and ERK pathways. Furthermore, DIM also leads to down-regulation of G1-S cell cycle markers: cyclin D1, cdk6 and cdk4. These findings may lead to development of a novel preventive and/or therapeutic dietary supplement for patients diagnosed with cancer or predisposed to developing certain cancers.