Roles of the matrix metalloproteinases in mammary gland development and cancer

Targeting canine mammary neoplastic epithelial cells with a reengineered anthrax toxin: first study

Mammary tumors are the most frequent type of neoplasms in intact female dogs. New therapies that target neoplastic cells without affecting normal cells are highly sought. The Bacillus anthracis toxin has been reengineered to target tumor cells that express urokinase plasminogen activators and metalloproteinases. In previous studies carried out in our laboratory, the reengineered anthrax toxin had inhibitory effects on canine oral mucosal melanoma and canine osteosarcoma cells. In this study, five canine neoplastic epithelial cell lines (four adenocarcinomas and one adenoma) and one non-neoplastic canine mammary epithelial cell line were treated with different concentrations of reengineered anthrax toxin components. Cell viability was quantified using an MTT assay and half-maximal inhibitory concentration (IC50) values. Cell lines were considered sensitive when the IC50 was lower than 5000 ng/ml. One canine mammary adenocarcinoma cell line and one mammary adenoma cell line showed significantly decreased viability after treatment, whereas the non-neoplastic cell line was resistant. We conclude that the reengineered anthrax toxin may be considered a targeted therapy for canine mammary neoplasms while preserving normal canine mammary epithelial cells.

Is sex a biological variable in corneal wound healing?

Wound healing differs significantly between men and women in a tissue-dependent manner. Dermal wounds heal faster in women whereas mucosal wounds heal faster in men. However, the effect of sex as a variable in corneal wound healing is largely unknown. The primary objective of this study was to test whether sex is a biological variable in corneal wound healing activated by the trauma or injury using an established in vivo rabbit model with male and female New Zealand White rabbits. Corneal wounds in rabbits were produced by a single topical alkali (0.5N Sodium hydroxide) application. Serial slit-lamp, stereo biomicroscopy, and applanation tonometry evaluated corneal opacity, anterior segment ocular health, and intraocular pressure (IOP), respectively, at various times during the study. Fourteen days after alkali-wound, corneal tissues were collected after humane euthanasia to examine cellular and molecular wound healing parameters. Quantitative PCR (qPCR) and immunofluorescence were used to quantify changes in the extracellular modeling protein levels of alpha-smooth muscle actin (α-SMA), Fibronectin (FN), Collagen-I (Col-I), and Transforming growth factor beta 1 (TGFβ1) involved in corneal healing. Hematoxylin and Eosin (H&E) staining was used to study histopathological changes in morphology and TUNEL assay to evaluate levels of apoptotic cell death. Male and female rabbits showed no significant differences in corneal opacity (Fantes score) or intraocular pressure (IOP) values (9.5 ± 0.5 mm Hg) in live animals. Likewise, no statistically significant sex-based differences in the mRNA levels of α-SMA (male = 5.95 ± 0.21 fold vs. female = 5.32 ± 0.043), FN (male = 3.02 ± 0.24 fold vs. female = 3.23 ± 0.27), Col-I (male = 3.12 ± 0.37 fold vs. female = 3.31 ± 0.24), TGFβ1 (male = 1.65 ± 0.06 fold vs. female = 1.59 ± 0.053); and protein levels of α-SMA (male = 74.16 ± 4.6 vs. female = 71.58 ± 7.1), FN (male = 60.11 ± 4.6 vs. female = 57.41 ± 8.3), Col-I (male = 84.11 ± 2.8 vs. female = 84.55 ± 3.6), TGFβ1 (male = 11.61 ± 2.8 vs. female = 9.5 ± 3.04) were observed. Furthermore, H&E and TUNEL analyses found no statistically significant differences in cellular structures and apoptosis, respectively, in male vs. female corneas. Consistent with earlier reports, wounded corneas showed significantly increased levels of these parameters compared to the unwounded corneas. Our data suggest that sex is not a major biological variable during active early stages of corneal wound healing in rabbits in vivo.

The Association of Matrix Metalloproteinase-1 Promoter Polymorphisms with Breast Cancer

BACKGROUND/AIM

The family of matrix metalloproteinases (MMPs) are responsible for the homeostasis of extracellular matrix components and their genetic polymorphisms may be associated with cancer susceptibility. The serum levels of MMP-1 have been reported to be lower in breast cancer patients than healthy subjects. In the current study, we aimed at investigating the contribution of a polymorphism in the promoter region of MMP-1 to breast cancer in Taiwan.

MATERIALS AND METHODS

The MMP-1 rs1799705 polymorphic genotypes were genotyped among 1,232 breast cancer patients and 1,232 healthy controls by the typical polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The percentages of 2G/2G, 1G/2G, and 1G/1G for MMP1 -1607 genotypes were 35.4, 40.6 and 24.0% in the breast cancer group and 34.1, 43.6, and 22.3% in the healthy control group (p trend=0.3025), respectively. The odds ratios (ORs) after adjusting for age, smoking and alcohol drinking status for those carrying 1G/2G and 1G/1G genotypes at MMP1 -1607 were 0.93 (95%CI=0.76-1.11, p=0.2390) and 1.01 (95%CI=0.77-1.23, p=0.7377), respectively, compared to those carrying the wild-type 2G/2G genotype. Supporting this finding, the adjusted OR for those carrying the 1G allele at MMP-1 -1607 was 1.03 (95%CI=0.91-1.18, p=0.8860), compared to those carrying the wild-type 2G allele. Our findings suggest that the polymorphic genotypes at MMP1 promoter -1607 investigated in the current study, may not play a major role in determining cancer susceptibility to breast cancer in Taiwan. Other early diagnostic and predictive markers are urgently needed for personalized and precise breast cancer detection and therapy.

Role of corneal collagen fibrils in corneal disorders and related pathological conditions

The cornea is a soft tissue located at the front of the eye with the principal function of transmitting and refracting light rays to precisely sense visual information. Corneal shape, refraction, and stromal stiffness are to a large part determined by corneal fibrils, the arrangements of which define the corneal cells and their functional behaviour. However, the modality and alignment of native corneal collagen lamellae are altered in various corneal pathological states such as infection, injury, keratoconus, corneal scar formation, and keratoprosthesis. Furthermore, corneal recuperation after corneal pathological change is dependent on the balance of corneal collagen degradation and contraction. A thorough understanding of the characteristics of corneal collagen is thus necessary to develop viable therapies using the outcome of strategies using engineered corneas. In this review, we discuss the composition and distribution of corneal collagens as well as their degradation and contraction, and address the current status of corneal tissue engineering and the progress of corneal cross-linking.

Rescued expression of WIF-1 in gallbladder cancer inhibits tumor growth and induces tumor cell apoptosis with altered expression of proteins

As a highly conserved metabolic pathway, the Wnt signaling pathway is involved in cell differentiation, proliferation and several other processes. In normal cells, this pathway is suppressed, and abnormal activation is often associated with tumor occurrence and development. In certain types of tumor, Wnt inhibitory factor 1 (WIF-1), an inhibitor of the Wnt pathway, inhibits tumor growth. However, the effect of the expression of WIF-1 on gallbladder cancer remains to be fully elucidated. In the current study, reverse transcription-quantitative polymerase chain reaction and western blotting were conducted. The present study demonstrated that, in gallbladder cancer, WIF-1 generally exhibited low levels of expression as a result of gene promoter methylation. Treatment with the drug, 5-aza-2-deoxycytidine, increased the expression of WIF-1 in the GBC-SD gallbladder cell line. In addition, a WIF-1-expression plasmid was transfected into GBC-SD cells, and it was found that cell proliferation, invasion and metastasis declined significantly, whereas the apoptotic rate increased. A nude mouse tumor transplantation experiment showed that the oncogenicity of the GBC-SD cells expressing WIF-1 was substantially lower, compared with that of the untransfected GBC-SD cells and of GBD-SD cells expressing the control plasmid. A fluorescent protein chip experiment showed that the restored expression of WIF-1 affected the expression of several cellular proteins. These alterations may explain the different biological behavior of the tumor cells expressing WIF-1. As an effective inhibitory factor of the Wnt signaling pathway, WIF-1 modulated the expression of proteins controlling the proliferation, apoptosis and metastasis of gallbladder tumor cells, thus suppressing the tumor. Therefore, WIF-1 may be an effective treatment target for gallbladder cancer.

Nimbolide inhibits invasion and migration, and down-regulates uPAR chemokine gene expression, in two breast cancer cell lines

OBJECTIVES

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in women, worldwide. Urokinase type plasminogen activator (uPA) is a serine protease that is involved in cancer progression, especially invasion and metastasis of breast cancer. Nimbolide is a potent cytotoxic limnoid isolated from Azadirachta indica. Our previous studies have shown that nimbolide elicits pleiotropic effects on breast cancer cells; however, its roles in invasion and migration have not previously been fully elucidated.

MATERIALS AND METHODS

Protein expression of pEGFR, VEGFR, NFκB, IKKα, IKKβ, MMP-2, MMP-9 and TIMP-2 were analysed by western blotting. We also analysed expressions of uPA, uPAR genes and chemokines by real-time PCR. Breast cancer cell invasion was assessed by transwell invasion assay and cell migration analysed by scratch wound healing assay.

RESULTS

Our results showed that reduced protein expression of pEGFR, VEGFR, NFκB, IKKα, β, MMP-2, MMP-9 and TIMP-2 was higher in nimbolide-treated breast cancer cells. mRNA expression of uPA, uPAR, chemokines and their receptors were also significantly reduced in response to nimbolide treatment. Nimbolide inhibited breast cancer cell migration and invasion as shown in transwell invasion and wound healing assays.

CONCLUSION

These results clearly proved inhibitory effects of nimbolide on tumour cell invasion and migration by down-regulating proteins critically involved in regulation of cell invasion and metastasis, suggesting a possible therapeutic role of nimbolide for breast cancer.

The host microenvironment influences prostate cancer invasion, systemic spread, bone colonization, and osteoblastic metastasis

Prostate cancer (PCa) is the second leading cause of cancer death in men worldwide. Most PCa deaths are due to osteoblastic bone metastases. What triggers PCa metastasis to the bone and what causes osteoblastic lesions remain unanswered. A major contributor to PCa metastasis is the host microenvironment. Here, we address how the primary tumor microenvironment influences PCa metastasis via integrins, extracellular proteases, and transient epithelia-mesenchymal transition (EMT) to promote PCa progression, invasion, and metastasis. We discuss how the bone-microenvironment influences metastasis; where chemotactic cytokines favor bone homing, adhesion molecules promote colonization, and bone-derived signals induce osteoblastic lesions. Animal models that fully recapitulate human PCa progression from primary tumor to bone metastasis are needed to understand the PCa pathophysiology that leads to bone metastasis. Better delineation of the specific processes involved in PCa bone metastasize is needed to prevent or treat metastatic PCa. Therapeutic regimens that focus on the tumor microenvironment could add to the PCa pharmacopeia.

Expression of inflammation-mediated cluster of genes as a new marker of canine mammary malignancy

Because canine mammary tumours constitute a serious clinical problem and there are no good prognostic markers (only histopathological variables are used), the aim of the presented study was to find new malignancy markers as well as to identify intracellular pathways and biological processes characteristic for canine mammary malignancy. We compared gene expression of the most malignant mammary tumours (poorly differentiated cancers of the 3rd grade of malignancy) with less malignant tumours (well differentiated cancers of the 1st grade of malignancy). The results of our study indicated that in dogs the number of tumour-infiltrating myeloid cells or expression of myeloid-specific antigens by cancer cells is related to the cancer progression and may constitute a new marker of malignancy, however further studies in this field are required.

Mammary gland development is delayed in mice deficient for aminopeptidase N

Development of the mammary gland requires the coordinated action of proteolytic enzymes during two phases of remodelling. Firstly, new ducts and side-branches thereof need to be established during pregnancy to generate an extensive ductal tree allowing the secretion and transport of milk. A second wave of remodelling occurs during mammary involution after weaning. We have analysed the role of the cell surface protease aminopeptidase N (Anpep, APN, CD13) during these processes using Anpep deficient and Anpep over-expressing mice. We find that APN deficiency significantly delays mammary gland morphogenesis during gestation. The defect is characterised by a reduction in alveolar buds and duct branching at mid-pregnancy. Conversely over-expression of Anpep leads to accelerated ductal development. This indicates that Anpep plays a critical role in the proteolytic remodelling of mammary tissue during adult mammary development.

Cellular mechanisms of zinc dysregulation: a perspective on zinc homeostasis as an etiological factor in the development and progression of breast cancer

Worldwide, breast cancer is the most commonly diagnosed cancer among women and is the leading cause of female cancer deaths. Zinc (Zn) functions as an antioxidant and plays a role in maintaining genomic stability. Zn deficiency results in oxidative DNA damage and increased cancer risk. Studies suggest an inverse association between dietary and plasma Zn levels and the risk for developing breast cancer. In contrast, breast tumor biopsies display significantly higher Zn levels compared with normal tissue. Zn accumulation in tumor tissue also correlates with increased levels of Zn importing proteins. Further, aberrant expression of Zn transporters in tumors correlates with malignancy, suggesting that altered metal homeostasis in the breast could contribute to malignant transformation and the severity of cancer. However, studies have yet to link dysregulated Zn transport and abnormal Zn-dependent functions in breast cancer development. Herein, we summarize studies that address the multi-modal role of Zn dyshomeostasis in breast cancer with respect to the role of Zn in modulating oxidative stress, DNA damage response/repair pathways and cell proliferation/apoptosis, and the relationship to aberrant regulation of Zn transporters. We also compare Zn dysregulation in breast tissue to that of prostate, pancreatic and ovarian cancer where possible.

Osteomimicry of mammary adenocarcinoma cells in vitro; increased expression of bone matrix proteins and proliferation within a 3D collagen environment

Bone is the most common site of metastasis for breast cancer, however the reasons for this remain unclear. We hypothesise that under certain conditions mammary cells possess osteomimetic capabilities that may allow them to adapt to, and flourish within, the bone microenvironment. Mammary cells are known to calcify within breast tissue and we have recently reported a novel in vitro model of mammary mineralization using murine mammary adenocarcinoma 4T1 cells. In this study, the osteomimetic properties of the mammary adenocarcinoma cell line and the conditions required to induce mineralization were characterized extensively. It was found that exogenous organic phosphate and inorganic phosphate induce mineralization in a dose dependent manner in 4T1 cells. Ascorbic acid and dexamethasone alone have no effect. 4T1 cells also show enhanced mineralization in response to bone morphogenetic protein 2 in the presence of phosphate supplemented media. The expression of several bone matrix proteins were monitored throughout the process of mineralization and increased expression of collagen type 1 and bone sialoprotein were detected, as determined by real-time RT-PCR. In addition, we have shown for the first time that 3D collagen glycosaminoglycan scaffolds, bioengineered to represent the bone microenvironment, are capable of supporting the growth and mineralization of 4T1 adenocarcinoma cells. These 3D scaffolds represent a novel model system for the study of mammary mineralization and bone metastasis. This work demonstrates that mammary cells are capable of osteomimicry, which may ultimately contribute to their ability to preferentially metastasize to, survive within and colonize the bone microenvironment.

Prolactin and blood vessels: a comparative endocrinology perspective

The hormone prolactin (PRL), fundamental for lactation in mammals, is known to exert a wide diversity of actions in the various vertebrate groups. Blood vessels are surfacing as important PRL targets, contributing to these hormonal functions. PRL promotes the growth of new blood vessels (angiogenesis) and is proteolytically cleaved to vasoinhibins, a family of peptides (including 16-kDa PRL) with potent antiangiogenic and blood vessel regression effects. These opposing actions point to the regulation of the proteases responsible for PRL cleavage as an efficient way to balance blood vessel growth and involution. This review briefly summarizes the effects of PRL and vasoinhibins on blood vessels in mammals and discusses whether similar vascular actions could contribute to the effects of PRL on the development, growth, and reproduction of lower vertebrates. A comparative study in diverse species may lead to a better understanding of blood vessels as a driving force for the biological actions of PRL.

Nimbolide retards tumor cell migration, invasion, and angiogenesis by downregulating MMP-2/9 expression via inhibiting ERK1/2 and reducing DNA-binding activity of NF-κB in colon cancer cells

Nimbolide, a plant-derived limonoid has been shown to exert its antiproliferative effects in various cell lines. We demonstrate that nimbolide effectively inhibited proliferation of WiDr colon cancer cells through inhibition of cyclin A leading to S phase arrest. It also caused activation of caspase-mediated apoptosis through the inhibition of ERK1/2 and activation of p38 and JNK1/2. Further nimbolide effectively retarded tumor cell migration and invasion through inhibition of metalloproteinase-2/9 (MMP-2/9) expression, both at the mRNA and protein level. It was also a strong inhibitor of VEGF expression, promoter activity, and in vitro angiogenesis. Finally, nimbolide suppressed the nuclear translocation of p65/p50 and DNA binding of NF-κB, which is an important transcription factor for controlling MMP-2/9 and VEGF gene expression.

Role of DDR1 in the gelatinases secretion induced by native type IV collagen in MDA-MB-231 breast cancer cells

Discoidin domain receptors (DDRs) are receptor tyrosine kinases that get activated by collagens in its native triple-helical form. In mammalian cells, DDR family consists of two members, namely DDR1 and DDR2, which mediates migration and proliferation of several cell types. DDR1 is activated by native type IV collagen and overexpressed in human breast cancer. Type IV collagen is the main component of basement membrane (BM), and the ability to degrade and penetrate BM is related with an increased potential for invasion and metastasis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that collectively are capable of degrading all components of the extracellular matrix, including the BM. In breast cancer cells, denatured type IV collagen induces MMP-9 secretion and invasion. However, the role of DDR1 in the regulation of gelatinases (MMP-2 and -9) secretion and invasion in breast cancer cells remains to be studied. We demonstrate here that native type IV collagen induces MMP-2 and -9 secretions and invasion through a DDR1 and Src-dependent pathway, together with an increase of MMP-2 and -9-cell surface levels. MMP-2 and -9 secretions require PKC kinase activity, epidermal growth factor receptor (EGFR) activation, arachidonic acid (AA) production and AA metabolites in MDA-MB-231 breast cancer cells. In summary, our data demonstrate, for the first time, that DDR1 mediates MMP-2 and -9 secretions and invasion induced by native type IV collagen in MDA-MB-231 breast cancer cells.

Zinc in specialized secretory tissues: roles in the pancreas, prostate, and mammary gland

Zinc (Zn) is an essential micronutrient required for over 300 different cellular processes, including DNA and protein synthesis, enzyme activity, and intracellular signaling. Cellular Zn homeostasis necessitates the compartmentalization of Zn into intracellular organelles, which is tightly regulated through the integration of Zn transporting mechanisms. The pancreas, prostate, and mammary gland are secretory tissues that have unusual Zn requirements and thus must tightly regulate Zn metabolism through integrating Zn import, sequestration, and export mechanisms. Recent findings indicate that these tissues utilize Zn for basic cellular processes but also require Zn for unique cellular needs. In addition, abundant Zn is transported into the secretory pathway and a large amount is subsequently secreted in a tightly regulated manner for unique biological processes. Expression of numerous members of the SLC30A (ZnT) and SLC39A (Zip) gene families has been documented in these tissues, yet there is limited understanding of their precise functional role in Zn metabolism or their regulation. Impairments in Zn secretion from the pancreas, prostate, and mammary gland are associated with disorders such as diabetes, infertility, and cancer, respectively. In this review, we will provide a brief summary of the specific role of Zn in each tissue and describe our current knowledge regarding how Zn metabolism is regulated. Finally, in each instance, we will reflect upon how this information shapes our current understanding of the role of Zn in these secretory tissues with respect to human health and disease.

LOXL2-mediated matrix remodeling in metastasis and mammary gland involution

More than 90% of cancer patient mortality is attributed to metastasis. In this study, we investigated a role for the lysyl oxidase-related enzyme lysyl oxidase-like 2 (LOXL2) in breast cancer metastasis, in both patient samples and in vivo models. Analysis of a published microarray data set revealed that LOXL2 expression is correlated with metastasis and decreased survival in patients with aggressive breast cancer. In immunocompetent or immunocompromised orthotopic and transgenic breast cancer models we showed that genetic, chemical or antibody-mediated inhibition of LOXL2 resulted in decreased metastasis. Mechanistic investigations revealed that LOXL2 promotes invasion by regulating the expression and activity of the extracellular proteins tissue inhibitor of metalloproteinase-1 (TIMP1) and matrix metalloproteinase-9 (MMP9). We found that LOXL2, TIMP1, and MMP9 are coexpressed during mammary gland involution, suggesting they function together in glandular remodeling after weaning. Finally, we found that LOXL2 is highly expressed in the basal/myoepithelial mammary cell lineage, like many other genes that are upregulated in basal-like breast cancers. Our findings highlight the importance of LOXL2 in breast cancer progression and support the development of anti-LOXL2 therapeutics for the treatment of metastatic breast cancer.

Substrate screening identifies a novel target sequence for the proteasomal activity regulated by ionizing radiation

The screening for treatment-induced enzyme activities offers the opportunity to discover important regulatory mechanisms and the identification of potential targets for anti-cancer therapies. A novel screening technique was applied to screen substrate peptide sequences for proteolytic activities up- or down-regulated by ionizing radiation in tumor cells. One specific substrate sequence was cleaved in control cell extracts but to a smaller extent in irradiated cell extracts and investigated in detail. Based on protease-class-specific inhibitory studies and cleavage site analysis a potent warhead-inhibitor was synthesized and used to identify the proteasome as the protease of interest. The investigated sequence shows high homology to a regulatory site of nucleoporin 50, an element of the nuclear pore complex, and site specific cleavage of nucleoporin 50 was determined in vitro suggesting a novel link between the ionizing radiation-regulated proteasome and nuclear protein shuttling.

Reevaluating cathepsin D as a biomarker for breast cancer: serum activity levels versus histopathology

Cathepsin D is a lysosomal hydrolase involved in intra- and extracellular proteolysis. This enzyme is aberrantly produced and processed in malignancy, and most notably is over-secreted into the tumor cell microenvironment. This hyper-secretion may lead to excessive degradation of the extracellular matrix, and contribute to tumor progression and metastases. These phenomena have been established in vitro, and there is evidence that Cathepsin D is similarly dysregulated in human breast cancer patients. Because breast cancer lacks an effective screening or surveillance biomarker, here we address the hypothesis that serum Cathepsin D activity may be useful to assess the presence or progression of breast cancer in females. While representative histologic sections from various disease-specific cohorts confirm previous findings that increased Cathepsin D production and secretion correlate with tumor progression, we report no difference in serum Cathepsin D activity between patients who are disease free, patients with pre-invasive or limited invasive disease, and patients with metastatic disease. Furthermore, in patients with known metastatic disease, there were no clinical variables associated with significantly different serum Cathepsin D activity. However, the immunohistochemical localization of Cathepsin D expression in histopathologic sections from breast cancer patients correlates with disease progression. Based on the serum results, and in contradistinction to Cathepsin D localization in breast cancer tissues, our findings support using Cathepsin D as a reliable histopathology biomarker for disease progression, but not for serum screening.

Matrix metalloproteinases as novel biomarkers and potential therapeutic targets in human cancer

The matrix metalloproteinase (MMP) family of enzymes is comprised of critically important extracellular matrix remodeling proteases whose activity has been implicated in a number of key normal and pathologic processes. The latter include tumor growth, progression, and metastasis as well as the dysregulated angiogenesis that is associated with these events. As a result, these proteases have come to represent important therapeutic and diagnostic targets for the treatment and detection of human cancers. In this review, we summarize the literature that establishes these enzymes as important clinical targets, discuss the complexity surrounding their choice as such, and chronicle the development strategies and outcomes of their clinical testing to date. The status of the MMP inhibitors currently in US Food and Drug Administration approved clinical trials is presented and reviewed. We also discuss the more recent and successful targeting of this enzyme family as diagnostic and prognostic predictors of human cancer, its status, and its stage. This analysis includes a wide variety of human cancers and a number of human sample types including tissue, plasma, serum, and urine.

Matrix metalloproteinases as novel biomarkers and potential therapeutic targets in human cancer

The matrix metalloproteinase (MMP) family of enzymes is comprised of critically important extracellular matrix remodeling proteases whose activity has been implicated in a number of key normal and pathologic processes. The latter include tumor growth, progression, and metastasis as well as the dysregulated angiogenesis that is associated with these events. As a result, these proteases have come to represent important therapeutic and diagnostic targets for the treatment and detection of human cancers. In this review, we summarize the literature that establishes these enzymes as important clinical targets, discuss the complexity surrounding their choice as such, and chronicle the development strategies and outcomes of their clinical testing to date. The status of the MMP inhibitors currently in US Food and Drug Administration approved clinical trials is presented and reviewed. We also discuss the more recent and successful targeting of this enzyme family as diagnostic and prognostic predictors of human cancer, its status, and its stage. This analysis includes a wide variety of human cancers and a number of human sample types including tissue, plasma, serum, and urine.

Inflammation and breast cancer: metalloproteinases as common effectors of inflammation and extracellular matrix breakdown in breast cancer

Two rapidly evolving fields are converging to impact breast cancer: one has identified novel substrates of metalloproteinases that alter immune cell function, and the other has revealed a role for inflammation in human cancers. Evidence now shows that the mechanisms underlying these two fields interact in the context of breast cancer, providing new opportunities to understand this disease and uncover novel therapeutic strategies. The metalloproteinase class of enzymes is well studied in mammary gland development and physiology, but mostly in the context of extracellular matrix modification. Aberrant metalloproteinase expression has also been implicated in breast cancer progression, where these genes act as tumor modifiers. Here, we review how the metalloproteinase axis impacts mammary physiology and tumorigenesis and is associated with inflammatory cell influx in human breast cancer, and evaluate its potential as a regulator of inflammation in the mammary gland.

Role of prolactin and vasoinhibins in the regulation of vascular function in mammary gland

The formation of new blood vessels has become a major focus of mammary gland research stimulated by the therapeutic opportunities of controlling angiogenesis in breast cancer. Normal growth and involution of the mammary gland are profoundly affected by the expansion and regression of blood vessels, whereas dysregulation of angiogenesis is characteristic of breast cancer growth and metastasis. Prolactin stimulates the growth and differentiation of the mammary gland under normal conditions, but its role in breast cancer is controversial. Its action is complicated by the fact that prolactin itself is angiogenic, but proteases cleave prolactin to generate vasoinhibins, a family of peptides that act on endothelial cells to suppress angiogenesis and vasodilation and to promote apoptosis-mediated vascular regression. This review summarizes our current knowledge about the vascular effects of prolactin and the generation and action of vasoinhibins, and discusses their possible contribution to the regulation of blood vessels in the normal and malignant mammary gland.

Purification and analysis of thrombospondin-1

Thromboapondin 1 (TSP-1) is a trimeric matricellular protein that is expressed by many cells. It contains several different domains that allow it to participate in cell adhesion, cell migration, and cell signaling. Recently TSP-1 has been shown to activate transforming growth factor beta (TGF-beta) and to inhibit both angiogenesis and tumor growth. This unit contains protocols for the purification of TSP-1 from platelet-rich plasma and the purification of TSP-1 proteolytic fragments.

Na+/H+ exchanger regulatory factor 1 inhibits platelet-derived growth factor signaling in breast cancer cells

INTRODUCTION

The gene encoding Na+/H+ exchanger regulatory factor 1 (NHERF1) is a putative tumor suppressor gene that harbors frequent loss of heterozygosity (LOH) and intragenic mutations in breast carcinoma. The exact biologic activity of NHERF1 in mammary glands, however, remains unclear. It was recently proposed that NHERF1 forms a ternary complex with platelet-derived growth factor receptor (PDGFR) and phosphatase and tensin homolog (PTEN), linking NHERF1 suppressor activity to PDGF-initiated phosphoinositide-3 kinase (PI3K)/PTEN signaling.

METHODS

The effect of NHERF1 on the kinetics of PDGF-induced Akt activation was determined in cells with varied NHERF1 background. Levels of active Akt in mammary gland of NHERF1 knockout and wild-type mice were compared. We also examined how NHERF1 expression status affects cell sensitivity to PDGFR inhibitor. A plausible connection between NHERF1 and PTEN pathway was explored at the genetic level.

RESULTS

We showed that NHERF1, through its PDZ-I domain, interacts directly with the carboxyl-terminal tail of PTEN. Knocking down NHERF1 expression in Zr75.1 cells markedly delayed the turnover of PDGF-induced phospho-Akt. Conversely, NHERF1 over-expression in MCF10A cells led to accelerated phospho-Akt degradation. The slowed decay of phospho-Akt that resulted from NHERF1 loss was evident in mouse embryonic fibroblasts isolated from NHERF1 knockout mice. In agreement with this, mammary gland tissues from these mice exhibited markedly elevated phospho-Akt. The responses of breast cancer cells to PDGFR inhibition were also altered by changes in NHERF1 expression level. Zr75.1 cells with NHERF1 knockdown were more resistant to STI-571-induced apoptosis than parental cells. Similarly, over-expression of NHERF1 rendered MCF10A cells more sensitive to STI-571. NHERF1-induced apoptotic response relies on an intact PTEN pathway; over-expression of NHERF1 in MCF10A cells with PTEN knockdown did not affect STI-571 sensitivity. It was found that NHERF1 LOH-positive breast cancer cells had reduced NHERF1 expression. Interestingly, these cells more frequently had wild-type PTEN or PI3KCA gene than the LOH-negative lines.

CONCLUSION

Our data indicate that the interaction of NHERF1 with PTEN counterbalances PI3K/Akt oncogenic signaling and may affect how cells respond to PDGFR inhibition in breast cancer. The dependence of NHERF1 responses on PTEN and genetic segregation of NHERF1 and PTEN (or PI3KCA) alterations suggest that NHERF1 is an active component of the PTEN pathway. Collectively, our study indicates that the biologic activity of NHERF1 in mammary gland is related to PTEN signaling.

The other side of MMPs: protective roles in tumor progression

The matrix metalloproteinase (MMP) family of extracellular proteinases have long been associated with cancer invasion and metastasis by virtue of their ability to collectively degrade all components of the extracellular matrix (ECM). The general belief that overexpression of a specific MMP, either by tumor cells or the surrounding stroma, is pro-tumorigenic led to the development of synthetic MMP inhibitors for the treatment of cancer. However, there is an increasing amount of literature demonstrating that the expression of certain MMPs, either at the primary or the metastatic site, provides a beneficial and protective effect in multiple stages of cancer progression. Here, we review the evidence for protective effects of MMPs and contrast this with pro-tumorigenic effects of either the same enzyme, or a different MMP of the same family. These studies highlight the importance of targeting specific MMPs for cancer treatment, and point to a potential reason why clinical trials of pharmaceutical inhibitors for MMPs were disappointing. In order to effectively target MMPs in cancer progression, a better understanding of both their pro- and anti-tumorigenic effects is required.

Whey acidic protein (WAP) regulates the proliferation of mammary epithelial cells by preventing serine protease from degrading laminin

Whey acidic protein (WAP) is a major whey protein in milk that has structural similarity to the family of serine protease inhibitors with WAP motif domains characterized by a four-disulfide core. We previously reported that enforced expression of the mouse WAP transgene in mammary epithelial cells inhibits their proliferation in vitro and in vivo by means of suppressing cyclin D1 expression (Nukumi et al., 2004, Dev Biol 274: 31-44). This study was conducted in order to clarify the molecular mechanism of the inhibitory function of WAP in HC11 cells, a mammary epithelial cell line. The assembly of laminin, a component in the extracellular matrix, was much more prominent around WAP-clonal HC11 cells that stably expressed the WAP transgene than around mock-clonal HC11 cells, and the proliferation of WAP-clonal HC11 cells was particularly inhibited in the presence of laminin. A laminin degradation assay demonstrated that WAP inhibited the activity of the pancreatic elastase-mediated cleavage of laminin B1 and the phosphorylation of ERK1/2. ERK1/2 phosphorylation was blocked by an inhibitor of the epidermal growth factor (EGF) receptor AG1478. Treatment with pancreatic elastase was found to enhance the proliferation of mock-clonal HC11 cells, but had no effect on that of WAP-clonal HC11 cells. The proliferation of WAP-clonal HC11 cells was recovered by the addition of exogenous EGF. We concluded that WAP plays some role in regulating the proliferation of mammary epithelial cells by preventing elastase-type serine protease from carrying out laminin degradation and thereby suppressing the MAP kinase signal pathway.

3-O-methylfunicone produced by penicillium pinophilum affects cell motility of breast cancer cells, downregulating alphavbeta5 integrin and inhibiting metalloproteinase-9 secretion

Recent evidence assigns integrins and metalloproteinases (MMPs) an important role in regulating tumor cell progression. Here, we demonstrate that 3-O-methylfunicone (OMF), a secondary metabolite produced by Penicillium pinophilum, affects cell proliferation and motility of breast cancer MCF-7 cells, downregulating alphavbeta5 integrin, and inhibiting MMP-9 secretion. This effect was absent when the non-tumoral MCF-10 cell line was used. Inhibition of cell motility was also associated to modifications in cell shape and in the distribution of tubulin fibers of OMF-treated MCF-7 cells. In addition, a possible effect on survivin and hTERT was also investigated. We found that OMF strongly inhibits survivin and hTERT gene expression. The results of this study indicate that OMF-induced inhibition of cell motility may be mediated through the modulation of alphavbeta5 integrin and MMP-9 secretion. In addition, the inhibition of typical markers of tumor progression such as hTERT and survivin in MCF-7 and their inactivity towards MCF10 provide strong evidence for a potential use of OMF in anticancer therapy.

Pro-inflammatory cytokine, matrix metalloproteinases and TIMP-1 are involved in wound healing after mastectomy in invasive breast cancer patients

BACKGROUND

Mastectomy provides a good model to study the wound healing process after surgery. The involved factors include selectins, pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), matrix metalloproteinases (MMPs), and their natural inhibitors (TIMPs). In the present study, we observed the kinetic changes of these factors in the process of wound healing after a mastectomy, and analyzed the relationship between these factors and the clinical outcomes.

MATERIALS AND METHODS

Twenty-nine patients, who received a modified radical mastectomy, were recruited to this study. The wound was inspected daily for the presence of flap necrosis, infection and seroma. Drain fluid was collected on days 1, 2 and 5. IL-6, P-selectin, MMP-2, 3, 9 and TIMP-1 were screened by ELISA kits for their impacts on wound healing after mastectomy.

RESULTS

IL-6 demonstrated the highest level on Day 1 after operation and was negatively correlated with MMP-2, which in turn showed a consistently negative correlation with MMP-9 for days 1, 2 and 5. Incidences of seroma formation and skin flap necrosis were 27.6% and 20.7%, respectively. Seroma formation was associated with low MMP-2 levels on Day 5. While skin flap necrosis seemed to correlate with high MMP-2 levels and low levels of MMP-9 and TIMP-1.

CONCLUSION

IL-6, P-selectin, MMP-2, MMP-3, MMP-9 and TIMP-1 are important in the process of wound healing after mastectomy. A low MMP-2 level correlates with the formation of seroma, while MMP-2, MMP-9 and TIMP-1 are associated with skin flap necrosis.

Effects of Shugansanjie Tang on matrix metalloproteinases 1, 3 and 9 and telomerase reverse transcriptase expression in human breast cells in vitro

BACKGROUND

The traditional Chinese medication Shugansanjie Tang (SGT), whose active component is Akebia Trifoliate Koidz, possesses potential anti-tumor and immunostimulatory effects especially for breast cancer. The invasive processes of such cancers have been attributed to matrix metalloproteinases (MMPs) which may be the key factor mediating this process. Telomerase reverse transcriptase (TERT) catalyze the lengthening of telomeres, which prolongs cell life and interrupts natural cell death. The aim of this study is to determine the effects of Shugansanjie Tang on MMP levels and TERT activity using breast cancer cell lines.

MATERIALS AND METHODS

We used the breast cancer cell lines MDA-MB-231 and BT-483. Cell inhibition rate was measured by WST-1 reagent, cell apoptosis by Apoptotic DNA Ladder Kit, mRNA expression of MMP-1, MMP-3 and MMP-9 by PCR and TERT by immunohistochemistry stain.

RESULTS

Comparing to the control group, the test group showed lower cell growth rate, decreased mRNA expression of MMP-1, MMP-3 and MMP-9 production and less intense staining of MMPs with diaminobenzidine tetrahydrochloride.

CONCLUSION

This study demonstrated that Shugansanjie Tang inhibits the growth of breast cancer cells by apoptosis and lowers the level of certain matrix metalloproteinases and activity of telomerase reverse transcriptase in breast cancer in vitro.

Deciphering the molecular basis of breast cancer metastasis with mouse models

Breast cancer begins as a localized disease, but has the potential to spread to distant sites within the body. This process--known as metastasis--is the leading cause of death from breast cancer. Whether the ability of cancer cells to metastasize is an intrinsic or acquired feature is currently a topic of considerable debate. Nevertheless, the key cellular events required for metastasis are generally accepted. These include invasion of the surrounding stromal tissue, intravasation, evasion of programmed cell death, arrest within the vasculature at a distant site, extravasation, and establishment and growth within a new microenvironment. The development of mouse models that faithfully mimic critical aspects of human neoplasia has been instrumental in framing our current understanding of multistage carcinogenesis. This review examines the advantages and limitations of existing murine models for mammary carcinogenesis for probing the molecular mechanisms that contribute to metastasis, as well as non-invasive tumor imaging approaches to facilitate these investigations.

Expression and localization of extracellular matrix-degrading proteinases and their inhibitors in the bovine mammary gland during development, function, and involution

In degrading the extracellular matrix, matrix metalloproteinases (MMP) and the plasminogen activator (PA) system may play a critical role in extensive remodeling that occurs in the bovine mammary gland during development, lactation, and involution. Therefore, the aim of our study was to investigate the mRNA expression of MMP-1, MMP-2, MMP-14, MMP-19, tissue inhibitor of metalloproteinases (TIMP)-1, TIMP-2, urokinase-type PA, tissue-type PA, urokinase-type PA receptor, and PA inhibitor-1 by quantitative PCR and to localize with immunohistochemistry MMP-1, MMP-2, MMP-14, and TIMP-2 proteins in the bovine mammary gland during pubertal mammogenesis, lactogenesis, galactopoiesis, and involution. Expression of mRNA for each of the studied factors was relatively lower during galactopoiesis and early involution but was markedly increased during mammogenesis and late involution, 2 stages in which tissue remodeling is especially pronounced. The localization of proteins for MMP-1, MMP-14, and TIMP-2 showed a similar trend with strong staining intensity in cytoplasm of mammary duct and alveolar epithelial cells during pubertal mammogenesis and late involution. Interestingly, MMP-2 protein was localized only in the cytoplasm of endothelial cells during late involution. Our study demonstrated clearly that expression of extracellular matrix-degrading proteinases coincides with a concomitant expression of their inhibitors. High expression levels of MMP, TIMP, and PA family members seem to be a typical feature of the nonlactating mammary gland.

Retinoids induce MMP-9 expression through RARalpha during mammary gland remodeling

Retinoic acid (RA) is a signaling molecule in the morphogenesis of the mammary gland, modulating the expression of matrix metalloproteinases (MMPs). The aim of this paper was to study the role of RA during weaning, which consists of three events: apoptosis of the secretory cells, degradation of the extracellular matrix, and adipogenesis. CRABP II and CRBP-1 carrier proteins increased significantly during weaning compared with lactating glands but reverted to control values after the litter resuckled. The effects of RA are mediated by the nuclear receptors RARalpha, RARbeta, RARgamma, and RXRalpha, which underwent an increase in protein levels during weaning. In an attempt to elucidate the RARalpha-dependent signaling pathway, ChIP assays were performed. The results showed the binding of RARalpha to the MMP-9 promoter after 24- and 72-h weaning together with its coactivator p300; this fact could be responsible for the increase found in MMP-9 mRNA and protein levels in these conditions. Expression of related MMPs (MMP-2 and MMP-3) was also increased during weaning. Using gelatine zymography, we observed a time-dependent increase in active forms of MMP-9 and MMP-2. On the other hand, the inhibitor of MMPs, TIMP-1, was almost undetectable at 24- and 72-h weaning by Western blot. The role of retinoids in matrix remodeling is reinforced by the fact that administration of an acute dose of retinol palmitate to control lactating rats also induces MMP-9 expression. This emphasizes the importance of retinoids in vivo to regulate mammary gland involution.

Matrix metalloproteinases in cancer: comparison of known and novel aspects of their inhibition as a therapeutic approach

Matrix dissolution is a crucial step during tumor progression that converts a premalignant cell to an overtly malignant one. Main players in this step are the various matrix metalloproteinases (MMPs), which differ in substrate specificity and tissue distribution, and thereby also differ in presence and function during various stages of initial and systemic tumor spread. Accordingly, the inhibition of MMP synthesis and/or activity represents novel potential therapeutic strategies for the treatment of cancer patients. Considerable work has already been carried out on synthetic inhibitors of MMP activity, but with little or even adverse effects in recent clinical studies. The reasons may be inappropriate patient populations in too advanced tumor stages, or inappropriate enzymes as targets for inhibition. Upregulation of endogenous tissue inhibitors of MMP (TIMPs) also provided ambiguous results, since TIMPs possess biologic functions in addition to MMP inhibition, for example, TIMP-2 is a main player in the MMP-2 activation cascade. This may explain, at least in part, the adverse effects of TIMP application/upregulation. Other strategies have been sought in order to overcome these problems. These include the downregulation of MMP transcription by cytokines. However, the effects of cytokines (other than MMP inhibition) may also limit the use of this approach. Finally, empiric evidence for control and modulation of MMP transcription and/or activation by several naturally occurring substances, such as flavonoids, green tea polyphenols and curcumin, represent novel options for the control of MMP activity even in early tumor stages. Additionally, these substances have little or no toxic side effects and good bioavailability, and therefore their continuing analysis provides intriguing insight into tumor pathophysiology and possibly new therapeutic options.

Breast cancer biomarkers

Substantial progress has been made over the past three decades in our understanding of the epidemiology, clinical course and basic biology of breast cancer. This chapter considers the existing ancillary tests and emerging molecular markers in breast cancer prognosis assessment and the prediction of response of breast cancer to treatment of the disease.

Polymorphisms of the promoter regions of matrix metalloproteinases genes MMP-1 and MMP-9 in breast cancer

PURPOSE

Matrix metalloproteinases play a crucial role in the cancer invasion and metastasis, angiogenesis and tumorigenicity. A single guanine insertion--the 1G/2G polymorphism in the promoter of the matrix metalloproteinase 1 (MMP-1) gene creates a binding site for the transcription factor AP-1 and thus may affect the transcription level of MMP-1. The C-->T substitution at the polymorphic site of the MMP-9 gene promoter results in a higher transcription activity of the T-allelic promoter trough the loss of binding site for a repressor protein. The aim of this work was to investigate the influence of 1G/2G and C-->T polymorphisms on the MMP-1 and MMP-9 level and therefore on the occurrence and progression of breast cancer.

EXPERIMENTAL DESIGN

We investigated the distribution of genotypes and frequency of alleles of the 1G/2G and C-->T polymorphisms for 270 patients with breast cancer and 300 healthy women served as control. The genotypes were determined by RFLP-PCR. Additionally, we estimated the level of MMP-1 and MMP-9 antigens in tumor samples and normal breast tissue using ELISA.

RESULTS

The levels of MMP-1 in tumor samples of node positive patients ware significantly higher than in samples of node negative patients (p<0.05). Increased level of MMP-9 correlates with Bloom-Richardson grading III (p<0.05), increased tumor size (p<0.05) and absence of estrogen and progesterone receptors (p<0.01). Additionally, both MMP-1 and MMP-9 levels were higher in tumor than in the normal breast tissue. We showed the higher risk of metastasis development in lymph node for the 2G/2G genotype (OR=2.14; CI 95% 1.24;3.69) and the 2G allele carriers (OR=1.68; CI 95% 1.19;2.39). We found correlation between the T allele (OR=2.61; CI 95% 1.33;4.87), 2G (OR=2.58; CI 95% 1.35;4.91) and malignance.

CONCLUSION

The results suggest that MMP-1 is responsible for the local invasion and MMP-9 is associated with the malignance and the growth of the tumor. We suggest that the 2G allele of the 1G/2G MMP-1 gene polymorphism may be associated with the lymph node metastasis in patients with breast cancer and therefore it can be considered as a progression marker in this disease.

Invasion and metastasis markers in cancers

Over 90% of all adults human cancers are of epithelial origin comprising mainly of skin and aero-digestive tract cancers. A significant proportion of our discipline's workload consists of management of these cancers. This review article is to provide clinicians with a summary of the current research findings in invasion and metastasis of epithelial cancers and the translation of some of this information to clinical use particularly related to skin and head and neck cancers (HNSCC). Metastasis is the leading cause of death in cancer patients. Although surgical resection of isolated metastases is beneficial for some patients, the overall efficacy of surgery, chemotherapy or radiotherapy is limited. Clearly, with today's advances in surgery a majority of these primary cancers are resectable and a cure attainable if surgeons could control or inhibit metastasis.

Peroxisome proliferator-activated receptor delta and gamma agonists differentially alter tumor differentiation and progression during mammary carcinogenesis

Peroxisome proliferator-activated receptor (PPAR) represents a ligand-dependent nuclear receptor family that regulates multiple metabolic processes associated with fatty acid beta-oxidation, glucose utilization, and cholesterol transport. These and other receptor-mediated actions pertain to their role in hypolipidemic and antidiabetic therapies and as potential targets for cancer chemopreventive agents. The present study evaluated the chemopreventive activity of two highly potent and selective PPARgamma and PPARdelta agonists in a progestin- and carcinogen-induced mouse mammary tumorigenesis model. Animals treated with the PPARgamma agonist GW7845 exhibited a moderate delay in tumor formation. In contrast, animals treated with the PPARdelta agonist GW501516 showed accelerated tumor formation. Significantly, tumors from GW7845-treated mice were predominantly ductal adenocarcinomas, whereas tumors from GW501516-treated animals were adenosquamous and squamous cell carcinomas. Gene expression analysis of tumors arising from GW7845- and GW501516-treated mice identified expression profiles that were distinct from each other and from untreated control tumors of the same histopathology. Only tumors from mice treated with the PPARgamma agonist expressed estrogen receptor-alpha in luminal transit cells, suggesting increased ductal progenitor cell expansion. Tumors from mice treated with the PPARdelta agonist exhibited increased PPARdelta levels and activated 3-phosphoinositide-dependent protein kinase-1 (PDK1), which co-associated, suggesting a link between the known oncogenic activity of PDK1 in mammary epithelium and PPARdelta activation. These results indicate that PPARdelta and PPARgamma agonists produce diverse, yet profound effects on mammary tumorigenesis that give rise to distinctive histopathologic patterns of tumor differentiation and tumor development.

Production of matrix metalloproteinases in specific subpopulations of human-patient breast cancer invading in three dimensional culture system

This article aims at investigating the effect of production of matrix metalloproteinases (MMP) in human breast cancer tissues by means of three dimensional culture system. Thirty-nine tumour samples were taken from breast cancer patients. The tumour blocks were cultured on sponge gel using the three dimensional culture system. Breast cancer cells began shedding into the culture medium after 24 hours of culture. The cells were stained with trypan blue dye to assess viability on days 2, 4, 6 and 8. The culture medium was collected at these time points and tested for matrix metalloproteinases (MMP) 1,2,3 and 9 activities. There was a progressive increase in migration of cancer cells into the gel and culture medium from day 2 to day 8 and the interval difference was statistically significant (F ratio=4.06; p=0.008). The levels of all the MMPs tested were also significantly raised (P<0.05 for all the MMPs tested). When the levels of MMPs were correlated with the metabolic activities in the gel, medium and tumour block, cells in block show no correlation whereas cells in gel correlated significantly with MMP-1 and MMP-3. Cancer cells in the culture medium correlated with MMP-9. In conclusion, there is a progressive migration of cancer cells outside the tumour block. The migration into the gel and culture medium is associated with progressive and differential production of MMPs. It is likely that the three dimensional culture model assists in the selection of different subpopulations of cancer cells with different invasion properties as exemplified by the differential production of MMP.

Mammary ECM composition and function are altered by reproductive state

To address whether reproductive state alters mammary gland extracellular matrix (ECM) composition and function, ECM was isolated from nulliparous, pregnant, lactating, involuting, and regressed rat mammary glands. The ECM composition of fibronectin, tenascin, laminin, clusterin, and MMPs was found to vary dramatically with reproductive state. In 3-dimensional (3-D) culture, we identified novel effects of these endogenous mammary matrices on mammary epithelial cells. Specifically we found that (1) matrix isolated from nulliparous animals promoted the formation of epithelial ducts with bifurcation, (2) matrix isolated from mid-involuting mammary glands induced cell death, (3) matrix isolated from late-stage involuting glands restored glandular development, while (4) matrix isolated from parous animals restricted glandular morphogenesis. Our data were consistent with mammary gland ECM facilitating epithelial cell proliferation, differentiation, death, and glandular reorganization that occur during the pregnancy and involution cycle. Further, we show that the parous gland has persistent changes in ECM function. Cumulatively, our data demonstrated that the microenvironment of the normal adult mammary gland is highly plastic, which has important implications for mammary tumor cell progression and dormancy. These data also raised the possibility of targeting mammary matrix production with preventive or therapeutic interventions.

CXCL12-CXCR4 interactions modulate prostate cancer cell migration, metalloproteinase expression and invasion

The mechanisms responsible for prostate cancer metastasis are incompletely understood at both the cellular and molecular levels. In this regard, chemokines are a family of small, cytokine-like proteins that induce motility of neoplastic cells, leukocytes and cancer cells. The current study evaluates the molecular mechanisms of CXCL12 and CXCR4 in prostate cancer cell migration and invasion. We report that functional CXCR4 is significantly expressed by prostate cancer cell lines, LNCaP and PC3, when compared with normal prostatic epithelial cells (PrEC). As measured using motility and invasion chamber assays, prostate cancer cells migrated and invaded through extracellular matrix components in response to CXCL12, at rates that corresponded to CXCR4 expression. Anti-CXCR4 antibodies (Abs) significantly impaired the migration and invasive potential of PC3 and LNCaP cells. CXCL12 induction also enhanced collagenase-1 (metalloproteinase-1 (MMP-1)) expression by LNCaP and PC3 cells. Collagenase-3 (MMP-13) was expressed by prostate cancer cells, but it was not expressed by PrEC cells or modulated by CXCL12. CXCL12 increased MMP-2 expression by LNCaP and PC3; however, MMP-9 expression was elevated only in PC3 cells after CXCL12-CXCR4 ligation. PC3 cells also expressed high levels of stromelysin-1 (MMP-3) after CXCL12 stimulation. CXCL12 also significantly increased stromelysin-2 (MMP-10) expression by LNCaP cells. Stromelysin-3 (MMP-11) was expressed by LNCaP cells, but not by PC3 or PrEC cells and CXCL12 induced PC3 MMP-11 expression. Membrane type-1 MMP (MMP-14) was not expressed by PrEC or LNCaP cells, but CXCL12 significantly enhanced MMP-14 expression by PC3 cells. These studies reveal important cellular and molecular mechanisms of CXCR4/CXCL12-mediated prostate cancer cell migration and invasion.

Comparative study of matrix metalloproteinase expression between African American and Caucasian Women

To date there are 26 human matrix metalloproteinases (MMPs) which are classified according to their substrate specificity and structural similarities. The four major subgroups of MMPs are gelatinases, interstitial collagenases, stromelysins, and membrane-type matrix metalloproteinases (MT-MMPs). This study investigates the expression of 26 MMPs, which have been shown to play a role in cancer metastasis. Breast tissues and cell lines derived from African American patients and Caucasian patients were assayed to demonstrate alterations in the transcription of genes primarily responsible for degrading the extracellular matrix (ECM). The expression levels of the extracellular matrix and adhesion molecules were analyzed using the gene array technology. Steady state levels of mRNAs were validated by RT-PCR analysis. Total RNA was isolated from tissue and cell lines and used in the RT-PCR assays. From this data, differential expression of MMPs between 6 breast cancer cell lines and 2 non-cancer breast cell lines was demonstrated. We have performed an in vitro comparison of MMP expression and established differences in 12 MMPs (3, 7, 8, 9, 11-15, 23B, 26, and 28) expression between African American and Caucasian breast cell lines. Thus, evidence indicates that altered expression of MMPs may play a role in the aggressive phenotype seen in African American women.

Activin and follistatin in rat mammary gland

Mammary gland morphogenesis and differentiation are mediated through the combined activities of systemic hormones and locally synthesized growth factors. Activin, a member of the transforming growth factor (TGF)-beta superfamily, is known to regulate the growth and differentiation of several cell types. In the present study, we investigated the role of activin in rat mammary gland on different stages of development. We found that activin A in vitro inhibits the proliferation of isolated acini, and this effect increases with the development of the gland. This factor also produces in vitro an inhibition of the final differentiation of acini obtained from 19th day pregnant rats. We also report the expression of activin receptors IIA and IIB mRNA in whole rat mammary gland and acini, with decreased levels of expression of type IIA (in both compartments) and IIB (in acini) during pregnancy and lactogenesis. In addition, we show that activin betaB-subunit mRNA decreases throughout pregnancy, and that the mRNA levels of follistatin (Fst) (its ligand protein) are high in cycling rats and at the beginning of pregnancy and diminish thereafter, having the acini higher levels of expression. Our data show that activin betaB-subunit, follistatin and ActRIIA and IIB transcripts are expressed in rat mammary gland at appropriate times and locations during development, allowing an interplay that might regulate activin action on growth and differentiation of the gland.

Transinactivation of the epidermal growth factor receptor tyrosine kinase and focal adhesion kinase phosphorylation by dietary flavonoids: effect on invasive potential of human carcinoma cells

Focal adhesion kinase (FAK), a member of a growing family of structurally distinct protein tyrosine kinases (PTK), has been linked to specific phosphorylation events, and the elevation of FAK activity in human carcinoma cells correlated with increased invasive potential. Transactivation of the epidermal growth factor receptor (EGFR) tyrosine kinase activity is proposed to stimulate cell migration and the subsequent activation of downstream signaling pathways. Quercetin (Qu) and luteolin (Lu), are potent PTK inhibitors as well as putative chemopreventive agents. The present work, we demonstrate that Qu and Lu at concentration of 20 microM transinactivated EGFR tyrosine kinase activity with marked reduction in phosphotyrosyl level of 170, 125, 65, 60 and 42 kDa cellular proteins, and induced apoptosis in MiaPaCa-2 cells. The 125 kDa protein was further identified as a FAK by immunoprecipitation and immunoblotting analyses. Tumor cells treated with Lu or Qu dampened the phosphorylation of FAK. In addition, our data clearly demonstrated that tumor cells responded to Qu and Lu by parallel reductions in the levels of phosphorylated FAK and the secreted matrix metalloproteinase (MMP) that may lead to the suppression of invasive potential and cell migration in vitro. While the molecular mechanism of FAK regulation of MMP secretion in tumor cells remains unclear, our results suggested that blockade of the EGFR-signaling pathway may contributed to the net effect. As suggested in the current study, targeting EGFR and FAK with the objective of modulating their regulatory pathways could offer prospects for the treatment of EGFR-responsive cancers in the future.

ESX induces transformation and functional epithelial to mesenchymal transition in MCF-12A mammary epithelial cells

ESX is an epithelial-restricted member of a large family of transcription factors known as the Ets family. ESX expression has been shown to be correlated with Her2/neu proto-oncogene amplification in highly aggressive breast cancers and induced by Her2/neu in breast cell lines, but its role in tumorigenesis is unknown. Previously, we have shown that ESX enhances breast cell survival in colony-formation assays. In order to determine whether ESX can act as a transforming gene, we stably transfected MCF-12A human mammary epithelial cells with the ESX expression vector, pCGN2-HA-ESX. The MCF-12A cell line is immortalized, but nontransformed, and importantly, these cells fail to express endogenous ESX protein. We used pCGN2-HA-Ets-2 and pSVRas expression vectors as positive controls for transformation. Like HA-Ets-2 and V12-Ras, stable expression of ESX induced EGF-independent proliferation, serum-independent MAPK phosphorylation and growth in soft agar. Additionally, stable ESX expression conferred increased cell adhesion, motility and invasion in two-dimensional and transwell filter assays, and an epithelial to mesenchymal morphological transition. In three-dimensional cultures, parental and vector control (pCGN2) cells formed highly organized duct-like structures with evidence of cell polarity, ECM adhesion-dependent proliferation and cell survival, and lack of cellular invasion into surrounding matrix. Remarkably, the ESX stable cells formed solid, disorganized structures, with lack of cell polarity, loss of adhesion junctions and cytokeratin staining and loss of dependence on ECM adhesion for cell proliferation and survival. In addition, ESX cells invaded the surrounding matrix, indicative of a transformed and metastatic phenotype. Taken together, these data show that ESX expression alone confers a transformed and in vitro metastatic phenotype to otherwise normal MCF-12A cells.

Inhibition of transforming growth factor-beta and matrix metalloproteinases by estrogen and prolactin in breast cancer cells

Hormones, estrogen and prolactin, transforming growth factor-beta (TGF-beta), and matrixmetalloproteinases (MMPs) may modulate breast cancer progression. The goal of this research was to examine the regulation of expression of TGF-beta and MMPs (MMP-1, 2, 9) by estrogen and prolactin, independently and in combination, at physiological doses, and at doses stimulating cancer cell (T47D) proliferation in vitro. Prolactin, and estrogen synergistically, and similarly, inhibited the expression of TGF-beta and MMPs at physiological concentrations without altering cell proliferation, indicating a beneficial role of the hormones. The growth stimulating concentration of prolactin, but not estrogen, also inhibited the TGF-beta and MMP expression.

Progression of mouse mammary tumors: MCP-1-TNFalpha cross-regulatory pathway and clonal expression of promalignancy and antimalignancy factors

The progression of breast cancer is affected by multiple cellular and microenvironmental components. The monocyte chemoattractant MCP-1, IL-6 and matrix metalloproteinases (MMP) were suggested to promote, each on its own, breast cancer progression. We recently demonstrated that the high-tumorigenicity phenotype of the DA3 and CSML murine mammary adenocarcinoma cells is correlated with a high expression of MCP-1, IL-6 and MMP. This raised the possibility that common intrinsic tumor-derived factors regulate the concordant expression of these 3 components. The aim of the present study was to gain insight into the mode by which the secretion of MCP-1, IL-6 and MMP from murine mammary adenocarcinoma cells is regulated. This was investigated in cellular clones established from a highly malignant variant of the DA3 tumor (DA3-high). We also determined the secretion of the antimalignancy chemokine IP-10 from these cells. The results indicate that the secretion levels of IL-6, MMP and IP-10 varied between the clones. In contrast, all the clones secreted uniformly high levels of MCP-1, suggesting that MCP-1 constitutes an important feature of the malignancy phenotype of mammary carcinoma. In most of the clones, elevated levels of 1 of the 3 promalignancy factors did not correlate with a high expression of the other 2 factors and vice versa. These findings indicate that the 3 promalignancy factors are not coregulated by a common intrinsic tumor-derived factor. Rather, these results suggest that the individual capacities of the different clones to secrete these factors are summed up in the high-malignancy DA3 parental tumor population, which secretes relatively high levels of MCP-1, IL-6 and MMP as compared to DA3 cells expressing a low-malignancy phenotype. In contrast to the lack of coordinated intrinsic regulation of MCP-1, IL-6 and MMP, it was found that recombinant TNFalpha, a product of tumor-associated macrophages contributing to breast cancer progression, upregulated the secretion of MCP-1, IL-6 and MMP from all the clones. These results suggest a key role for this microenvironmental, monocyte-derived cytokine in the coordinated regulation of these 3 molecules. Furthermore, additional results demonstrated that monocytic cell-derived TNFalpha upregulated MCP-1 secretion from the tumor cells and that MCP-1 in turn promoted the secretion of TNFalpha from monocytic cells. This may result in a positive feedback loop, whereby the tumor cells and the monocytic cells at tumor site promote each other's ability to express and secrete promalignancy factors. We next attempted to assess the contribution of the promalignancy factors MCP-1, IL-6 and MMP and of the antimalignancy factor IP-10 to mammary adenocarcinoma progression. To this end, a preliminary formula was developed in which the net balance between secretion levels of the promalignancy factors and that of the antimalignancy IP-10 chemokine from different clones was related to their in vivo tumorigenicity profile. This formula suggests that a balance between the secretion levels of these factors plays an important role in determining the malignancy phenotype of mammary carcinomas. In all, our findings demonstrate that the mammary tumor cell population is composed of a heterogeneous assortment of clones whose individual characteristics are averaged in the whole population. The malignancy potential of such tumors is thus determined, inter alia, by a combinatorial effect of several promalignancy and antimalignancy factors secreted from each of the clones comprising these tumors. Our results also suggest that the expression of such factors is determined by several nonmutually exclusive regulatory mechanisms.