Inhibition of angiogenesis and invasion by 3,3'-diindolylmethane is mediated by the nuclear factor-kappaB downstream target genes MMP-9 and uPA that regulated bioavailability of vascular endothelial growth factor in prostate cancer

Nondenatured soy extracts reduce UVB-induced skin damage via multiple mechanisms

UV irradiation results in DNA damage, inflammation and immunosuppression, leading to the development of basal and squamous cell carcinomas. Earlier data show that topical treatment with nondenatured soy extracts reduced the incidence and delayed the development/progression of already-initiated skin tumors in high-risk hairless mice. Here we show that pretreatment with nondenatured soy extracts reduced UVB-induced Thymine-Thymine (TT) dimer formation. In vitro, nondenatured soy extracts enhanced UVB-induced checkpoint kinase-1 (Chk1) activation, suggesting a delay in cell cycle progression that enables longer time for DNA repair. Soy also reduced UVB-induced cyclo-oxygenase-2 (COX-2) expression and prostaglandin E2 secretion, and inhibited p38 MAP kinase activation, suggesting its anti-inflammatory activity. Mice pretreated topically with nondenatured soy extracts had reduced levels of UVB-induced TT dimers and COX-2 expression in their skins compared to UVB alone. The nondenatured soy extracts also inhibited vascular endothelial growth factor-induced endothelial tube formation in Matrigel, suggesting a possible inhibitory effect on angiogenesis and tumor progression. Taken together, nondenatured soy extracts could prevent or reduce UVB-induced skin damage via multiple mechanisms, affecting both the initiation and the progression of skin cancer. These data suggest that topical application of nondenatured soy extracts could potentially reduce the incidence of skin cancer.

Cancer chemotherapy with indole-3-carbinol, bis(3'-indolyl)methane and synthetic analogs

Indole-3-carbinol (I3C) conjugates are phytochemicals expressed in brassica vegetables and have been associated with the anticancer activities of vegetable consumption. I3C and its metabolite bis(3'-indolyl)methane (DIM) induce overlapping and unique responses in multiple cancer cell lines and tumors, and these include growth inhibition, apoptosis and antiangiogenic activities. The mechanisms of these responses are complex and dependent on cell context. I3C and/or DIM activate or inactivate multiple nuclear receptors, induce endoplasmic reticulum stress, decrease mitochondrial membrane potential, and modulate multiple signaling pathways including kinases. DIM has been used as a template to synthesize a series of 1,1-bis(3'indolyl)-1-(substituted aromatic)methanes (i.e. C-DIMs) which are also cytotoxic to cancer cells and tumors. Some of the effects of C-DIMs resemble those reported for DIM analogs; however, structure-activity studies with the aromatic ring has resulted in generation of highly unique receptor agonists. For example, p-trifluoromethylphenyl, p-t-butylphenyl and p-biphenyl analogs activate peroxisome proliferator-activated receptor gamma (PPARgamma), and p-methoxyphenyl and p-phenyl compounds activate nerve growth factor-induced-Balpha (NGFI-Balpha, Nur77) orphan nuclear receptor. The effects of C-DIMs on PPARgamma and Nur77 coupled with their receptor-independent activities has resulted in the development of a novel group of multi-targeted anticancer drugs with excellent potential for clinical treatment of cancer.

Apoptosis-inducing effect of erlotinib is potentiated by 3,3'-diindolylmethane in vitro and in vivo using an orthotopic model of pancreatic cancer

Blockade of epidermal growth factor receptor (EGFR) by EGFR tyrosine kinase inhibitors is insufficient for effective antitumor activity because of independently activated survival pathways. A multitargeted approach may therefore improve the outcome of anti-EGFR therapies. In the present study, we determined the effects of 3,3'-diindolylmethane (Bioresponse BR-DIM referred to as B-DIM), a formulated DIM with greater bioavailability on cell viability and apoptosis with erlotinib in vitro and in vivo using an orthotopic animal tumor model. BxPC-3 and MIAPaCa cells with varying levels of EGFR and nuclear factor-kappaB (NF-kappaB) DNA-binding activity were treated with B-DIM (20 micromol/L), erlotinib (2 micromol/L), and the combination. Cell survival and apoptosis was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and histone-DNA ELISA. Electrophoretic mobility shift assay was used to evaluate NF-kappaB DNA-binding activity. We found significant reduction in cell viability by both 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic assays, induction of apoptosis, down-regulation of EGFR phosphorylation, NF-kappaB DNA-binding activity, and expression of antiapoptotic genes in BxPC-3 cells when treated with the combination of erlotinib and B-DIM compared with either agent alone. In contrast, no such effect was observed in MIAPaCa cells by similar treatment. Most importantly, these in vitro results were recapitulated in animal model showing that B-DIM in combination with erlotinib was much more effective as an antitumor agent compared with either agent alone. These results suggest that the utilization of B-DIM could be a useful strategy for achieving better treatment outcome in patients with activated status of EGFR and NF-kappaB in their tumors.

Critical role of ADAM15 in tumor progression: targeting multiple factors for metastasis promotion

Evaluation of: Najy AJ, Day KC, Day ML: ADAM15 supports prostate cancer metastasis by modulating tumor cell–endothelial cell interaction. Cancer Res. 68, 1092–1099 (2008). Products of a disintegrin and metalloproteinase (ADAM) gene family are multifunctional proteins and have activities of metalloproteinase, integrin-binding, cell adhesion and intracellular signaling. ADAMs play important roles in many biological processes, such as neurogenesis, myogenesis, fertilization and growth factor shedding. Several ADAM genes are also implicated in various types of cancers; however, the exact function of ADAMs in tumorigenesis and tumor progression has not been well understood. In this report, Najy and colleagues have shown that ADAM15 plays a critical role in tumor growth and metastasis in human prostate cancer. Their results indicate that ADAM15 promotes the binding to extracellular matrix proteins, expression of metastatic-associated cell surface proteins, cleavage of N-cadherin and activation of matrix metalloproteinase 9. These events were followed by stimulation of transendothelial migration and bone metastasis. Therefore, ADAM15 signaling may serve as a potential therapeutic target for prostate cancer.

Indole-3-carbinol as a chemopreventive and anti-cancer agent

During the course of oncogenesis and tumor progression, cancer cells constitutively upregulate signaling pathways relevant to cell proliferation and survival as a strategy to overcome genomic instability and acquire resistance phenotype to chemotherapeutic agents. In light of this clinical and molecular heterogeneity of human cancers, it is desirable to concomitantly target these genetic abnormalities by using an agent with pleiotropic mode of action. Indole-3-carbinol and its metabolite 3,3'-diindoylmethane (DIM) target multiple aspects of cancer cell-cycle regulation and survival including Akt-NF kappa B signaling, caspase activation, cyclin-dependent kinase activities, estrogen metabolism, estrogen receptor signaling, endoplasmic reticulum stress, and BRCA gene expression. This broad spectrum of anti-tumor activities in conjunction with low toxicity underscores the translational value of indole-3-carbinol and its metabolites in cancer prevention/therapy. Furthermore, novel anti-tumor agents with overlapping underlying mechanisms have emerged via structural optimization of indole-3-carbinol and DIM, which may provide considerable therapeutic advantages over the parental compounds with respect to chemical stability and anti-tumor potency. Together, these agents might foster new strategies for cancer prevention and therapy.

Mammalian target of rapamycin repression by 3,3'-diindolylmethane inhibits invasion and angiogenesis in platelet-derived growth factor-D-overexpressing PC3 cells

Platelet-derived growth factor-D (PDGF-D) is a newly recognized growth factor known to regulate many cellular processes, including cell proliferation, transformation, invasion, and angiogenesis. Recent studies have shown that PDGF-D and its cognate receptor PDGFR-beta are expressed in prostate tumor tissues, suggesting that PDGF-D might play an important role in the development and progression of prostate cancer. However, the biological role of PDGF-D in tumorigenesis remains elusive. In this study, we found that PDGF-D-overexpressing PC3 cells (PC3 cells stably transfected with PDGF-D cDNA and referred to as PC3 PDGF-D) exhibited a rapid growth rate and enhanced cell invasion that was associated with the activation of mammalian target of rapamycin (mTOR) and reduced Akt activity. Rapamycin repressed mTOR activity and concomitantly resulted in the activation of Akt, which could attenuate the therapeutic effects of mTOR inhibitors. In contrast, B-DIM (BR-DIM from Bioresponse, Inc.; a chemopreventive agent) significantly inhibited both mTOR and Akt in PC3 PDGF-D cells, which were correlated with decreased cell proliferation and invasion. Moreover, conditioned medium from PC3 PDGF-D cells significantly increased the tube formation of human umbilical vein endothelial cells, which was inhibited by B-DIM treatment concomitant with reduced full-length and active form of PDGF-D. Our results suggest that B-DIM could serve as a novel and efficient chemopreventive and/or therapeutic agent by inactivation of both mTOR and Akt activity in PDGF-D-overexpressing prostate cancer.

Phellinus linteus suppresses growth, angiogenesis and invasive behaviour of breast cancer cells through the inhibition of AKT signalling

The antitumour activity of a medicinal mushroom Phellinus linteus (PL), through the stimulation of immune system or the induction of apoptosis, has been recently described. However, the molecular mechanisms responsible for the inhibition of invasive behaviour of cancer cells remain to be addressed. In the present study, we demonstrate that PL inhibits proliferation (anchorage-dependent growth) as well as colony formation (anchorage-independent growth) of highly invasive human breast cancer cells. The growth inhibition of MDA-MB-231 cells is mediated by the cell cycle arrest at S phase through the upregulation of p27^Kip1 expression. Phellinus linteus also suppressed invasive behaviour of MDA-MB-231 cells by the inhibition of cell adhesion, cell migration and cell invasion through the suppression of secretion of urokinase-plasminogen activator from breast cancer cells. In addition, PL markedly inhibited the early event in angiogenesis, capillary morphogenesis of the human aortic endothelial cells, through the downregulation of secretion of vascular endothelial growth factor from MDA-MB-231 cells. These effects are mediated by the inhibition of serine-threonine kinase AKT signalling, because PL suppressed phosphorylation of AKT at Thr³⁰⁸ and Ser⁴⁷³ in breast cancer cells. Taken together, our study suggests potential therapeutic effect of PL against invasive breast cancer.

Matrix metalloproteinase control of capillary morphogenesis

Matrix metalloproteinases (MMPs) play crucial roles in a variety of normal (e.g., blood vessel formation, bone development) and pathophysiological (e.g., wound healing, cancer) processes. This is not only due to their ability to degrade the surrounding extracellular matrix (ECM), but also because MMPs function to reveal cryptic matrix binding sites, release matrix-bound growth factors inherent to these processes, and activate a variety of cell surface molecules. The process of blood vessel formation, in particular, is regulated by what is widely classified as the angiogenic switch: a mixture of both pro- and antiangiogenic factors that function to counteract each other unless the stimuli from one side exceeds the other to disrupt the quiescent state. Although it was initially thought that MMPs were strictly proangiogenic, new functions for this proteolytic family, such as mediating vascular regression and generating matrix fragments with antiangiogenic capacities, have been discovered in the last decade. These findings cast MMPs as multifaceted pro- and antiangiogenic effectors. The purpose of this review is to introduce the reader to the general structure and characterization of the MMP family and to discuss the temporal and spatial regulation of their gene expression and enzymatic activity in the following crucial steps associated with angiogenesis: degradation of the vascular basement membrane, proliferation and invasion of endothelial cells within the subjacent ECM, organization into immature tubules, maturation of these nascent vessels, and the pruning and regression of the vascular network.

Evolving role of uPA/uPAR system in human cancers

Recent advancements in cancer research have led to some major breakthroughs; however, the impact on overall cancer-related death rate remains unacceptable, suggesting that further insight into tumor markers and development of targeted therapies is urgently needed. The urokinase plasminogen activator (uPA) system represents a family of serine proteases that are involved in the degradation of basement membrane and the extracellular matrix, leading to tumor cell invasion and metastasis. In this review, we have provided an overview of emerging data, from basic research as well as clinical studies, highlighting the evolving role of uPA/uPAR system in tumor progression. It is currently believed that the expression and activation of uPA plays an important role in tumorigenicity, and high endogenous levels of uPA and uPAR are associated with advanced metastatic cancers. The endogenous inhibitors of this system, PAI-1 and PAI-2, regulate uPA-uPAR activity by either direct inhibition or affecting cell surface expression and internalization. PAI-1's role in cancers is rather unusual; on one hand, it inhibits uPA-uPAR leading to inhibition of invasion and metastasis and on the other it has been reported to facilitate tumor growth and angiogenesis. Individual components of uPA/uPAR system are reported to be differentially expressed in cancer tissues compared to normal tissues and, thus, have the potential to be developed as prognostic and/or therapeutic targets. Therefore, this system represents a highly attractive target that warrants further in-depth studies. Such studies are likely to contribute towards the development of molecularly-driven targeted therapies in the near future.

Curcumin enhances the apoptosis-inducing potential of TRAIL in prostate cancer cells: molecular mechanisms of apoptosis, migration and angiogenesis

BACKGROUND

We have recently shown that curcumin (a diferuloylmethane) inhibits growth and induces apoptosis, and also demonstrated that TRAIL induces apoptosis by binding to specific cell surface death receptors in prostate cancer cells. The objectives of this paper were to investigate the molecular mechanisms by which curcumin enhanced the apoptosis-inducing potential of TRAIL in prostate cancer cells.

RESULTS

Curcumin enhanced the apoptosis-inducing potential of TRAIL in androgen-unresponsive PC-3 cells and sensitized androgen-responsive TRAIL-resistant LNCaP cells. Curcumin inhibited the expressions of Bcl-2, Bcl-XL, survivin and XIAP, and induced the expressions Bax, Bak, PUMA, Bim, and Noxa and death receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5) in both cell lines. Overexpression of dominant negative FADD inhibited the interactive effects of curcumin and TRAIL on apoptosis. Treatment of these cells with curcumin resulted in activation of caspase-3, and caspase-9, and drop in mitochondrial membrane potential, and these events were further enhanced when combined with TRAIL. Curcumin inhibited capillary tube formation and migration of HUVEC cells and these effects were further enhanced in the presence of MEK1/2 inhibitor PD98059.

CONCLUSION

The ability of curcumin to inhibit capillary tube formation and cell migration, and enhance the therapeutic potential of TRAIL suggests that curcumin alone or in combination with TRAIL can be used for prostate cancer prevention and/or therapy.

The evolving biology and treatment of prostate cancer

Since the effectiveness of androgen deprivation for treatment of advanced prostate cancer was first demonstrated, prevention strategies and medical therapies for prostate cancer have been based on understanding the biologic underpinnings of the disease. Prostate cancer treatment is one of the best examples of a systematic therapeutic approach to target not only the cancer cells themselves, but the microenvironment in which they are proliferating. As the population ages and prostate cancer prevalence increases, challenges remain in the diagnosis of clinically relevant prostate cancer as well as the management of the metastatic and androgen-independent metastatic disease states.

Targeting multiple signal pathways by chemopreventive agents for cancer prevention and therapy

In recent years, growing interest has been focused on the field of cancer prevention. Cancer prevention by chemopreventive agents offers significant promise for reducing the incidence and mortality of cancer. Chemopreventive agents may exert their effects either by blocking or metabolizing carcinogens or by inhibiting tumor cell growth. Another important benefit of chemopreventive agents is their nontoxic nature. Therefore, chemopreventive agents have recently been used for cancer treatment in combination with chemotherapeutics or radiotherapy, uncovering a novel strategy for cancer therapy. This strategy opens a new avenue from cancer prevention to cancer treatment. In vitro and in vivo studies have demonstrated that chemopreventive agents could enhance the antitumor activity of chemotherapeutics, improving the treatment outcome. Growing evidence has shown that chemopreventive agents potentiate the efficacy of chemotherapy and radiotherapy through the regulation of multiple signaling pathways, including Akt, NF-kappaB, c-Myc, cyclooxygenase-2, apoptosis, and others, suggesting a multitargeted nature of chemopreventive agents. However, further in-depth mechanistic studies, in vivo animal experiments, and clinical trials are needed to investigate the effects of chemopreventive agents in combination treatment of cancer with conventional cancer therapies. More potent natural and synthetic chemopreventive agents are also needed to improve the efficacy of mechanism-based and targeted therapeutic strategies against cancer, which are likely to make a significant impact on saving lives. Here, we have briefly reviewed the role of chemopreventive agents in cancer prevention, but most importantly, we have reviewed how they could be useful for cancer therapy in combination with conventional therapies.

Inflammation dampened by gelatinase A cleavage of monocyte chemoattractant protein-3

Tissue degradation by the matrix metalloproteinase gelatinase A is pivotal to inflammation and metastases. Recognizing the catalytic importance of substrate-binding exosites outside the catalytic domain, we screened for extracellular substrates using the gelatinase A hemopexin domain as bait in the yeast two-hybrid system. Monocyte chemoattractant protein-3 (MCP-3) was identified as a physiological substrate of gelatinase A. Cleaved MCP-3 binds to CC-chemokine receptors-1, -2, and -3, but no longer induces calcium fluxes or promotes chemotaxis, and instead acts as a general chemokine antagonist that dampens inflammation. This suggests that matrix metalloproteinases are both effectors and regulators of the inflammatory response.