Epidermal Growth Factor Induces WISP-2/CCN5 Expression in Estrogen Receptor-α-Positive Breast Tumor Cells through Multiple Molecular Cross-talks

Acetylation stabilizes the signaling protein WISP2 by preventing its degradation to suppress the progression of acute myeloid leukemia

Acute myeloid leukemia (AML) is challenging to treat due to its heterogeneity, prompting a deep understanding of its pathogenesis mechanisms, diagnosis, and treatment. Here, we found reduced expression and acetylation levels of WISP2 in bone marrow mononuclear cells from AML patients and that AML patients with lower WISP2 expression tended to have reduced survival. At the functional level, overexpression of WISP2 in leukemia cells (HL-60 and Kasumi-1) suppressed cell proliferation, induced cell apoptosis, and exerted antileukemic effects in an in vivo model of AML. Our mechanistic investigation demonstrated that WISP2 deacetylation was regulated by the deacetylase histone deacetylase (HDAC)3. In addition, we determined that crosstalk between acetylation and ubiquitination was involved in the modulation of WISP2 expression in AML. Deacetylation of WISP2 decreased the stability of the WISP2 protein by boosting its ubiquitination mediated by NEDD4 and proteasomal degradation. Moreover, pan-HDAC inhibitors (valproic acid and trichostatin A) and an HDAC3-specific inhibitor (RGFP966) induced WISP2 acetylation at lysine K6 and prevented WISP2 degradation. This regulation led to inhibition of proliferation and induction of apoptosis in AML cells. In summary, our study revealed that WISP2 contributes to tumor suppression in AML, which provided an experimental framework for WISP2 as a candidate for gene therapy of AML.

CCN5 inhibits proliferation and promotes apoptosis of oral squamous cell carcinoma cells

Oral squamous cell carcinoma (OSCC) is a common cancer with poor prognosis and high mortality. The role of CCN5 has attracted a great focus on the regulation of cancer progression. However, the biological function and mechanism of CCN5 in OSCC are still not well elucidated. The current study was designed to determine the effects of CCN5 on OSCC cell proliferation and apoptosis using two OSCC cell lines. Further, LY294002, a PI3K/AKT antagonist, was employed to explore the mechanism underlying the effects of CCN5 in the regulation of OSCC. The results showed that overexpression of CCN5 in TSCCa cells significantly reduced viable cell number, arrested cell cycle, and suppressed cell-cycle regulators (cyclin D1, cyclin E, and CDK2). CCN5 overexpression increased the apoptotic ratio and Hoechst-positive cell number, and altered the apoptotic-related proteins (caspase-3/9, Bax, and Bcl-2). However, CCN5 silencing induced opposite effects on cell proliferation and apoptosis in Tca-8113 cells. In addition, we observed that CCN5 knockdown increased the expression levels of PI3K (p85α and p110α) and phosphorylated AKT at serine 473 (p-AKT Ser473) in Tca-8113 cells. Inhibiting PI3K/AKT signaling with LY294002 rescued the apoptotic process in CCN5-silenced OSCC cells. Finally, xenograft analysis showed that CCN5 represses tumorigenesis of OSCC cells. These findings together suggest that CCN5 functions as a tumor suppressor for OSCC cell development through inactivation of PI3K/AKT signaling pathway, providing a potential candidate for OSCC therapy.

The MAZ transcription factor is a downstream target of the oncoprotein Cyr61/CCN1 and promotes pancreatic cancer cell invasion via CRAF-ERK signaling

Myc-associated zinc-finger protein (MAZ) is a transcription factor with dual roles in transcription initiation and termination. Deregulation of MAZ expression is associated with the progression of pancreatic ductal adenocarcinoma (PDAC). However, the mechanism of action of MAZ in PDAC progression is largely unknown. Here, we present evidence that MAZ mRNA expression and protein levels are increased in human PDAC cell lines, tissue samples, a subcutaneous tumor xenograft in a nude mouse model, and spontaneous cancer in the genetically engineered PDAC mouse model. We also found that MAZ is predominantly expressed in pancreatic cancer stem cells. Functional analysis indicated that MAZ depletion in PDAC cells inhibits invasive phenotypes such as the epithelial-to-mesenchymal transition, migration, invasion, and the sphere-forming ability of PDAC cells. Mechanistically, we detected no direct effects of MAZ on the expression of K-Ras mutants, but MAZ increased the activity of CRAF-ERK signaling, a downstream signaling target of K-Ras. The MAZ-induced activation of CRAF-ERK signaling was mediated via p21-activated protein kinase (PAK) and protein kinase B (AKT/PKB) signaling cascades and promoted PDAC cell invasiveness. Moreover, we found that the matricellular oncoprotein cysteine-rich angiogenic inducer 61 (Cyr61/CCN1) regulates MAZ expression via Notch-1-sonic hedgehog signaling in PDAC cells. We propose that Cyr61/CCN1-induced expression of MAZ promotes invasive phenotypes of PDAC cells not through direct K-Ras activation but instead through the activation of CRAF-ERK signaling. Collectively, these results highlight key molecular players in PDAC invasiveness and may help inform therapeutic strategies to improve clinical management and outcomes of PDAC.

Leptin-induced ER-α-positive breast cancer cell viability and migration is mediated by suppressing CCN5-signaling via activating JAK/AKT/STAT-pathway

Background

In menopausal women, one of the critical risk factors for breast cancer is obesity/adiposity. It is evident from various studies that leptin, a 16 kDa protein hormone overproduced in obese people, plays the critical role in neovascularization and tumorigenesis in breast and other organs. However, the mechanisms by which obesity influences the breast carcinogenesis remained unclear. In this study, by analyzing different estrogen receptor-α (ER-α)-positive and ER-α-negative BC cell lines, we defined the role of CCN5 in the leptin-mediated regulation of growth and invasive capacity.

Methods

We analyzed the effect of leptin on cell viability of ER-α-positive MCF-7 and ZR-75-1 cell lines and ER-α-negative MDA-MB-231 cell line. Additionally, we also determined the effect of leptin on the epithelial-mesenchymal transition (EMT) bio-markers, in vitro invasion and sphere-formation of MCF-7 and ZR-75-1 cell lines. To understand the mechanism, we determined the impact of leptin on CCN5 expression and the functional role of CCN5 in these cells by the treatment of human recombinant CCN5 protein(hrCCN5). Moreover, we also determined the role of JAK-STAT and AKT in the regulation of leptin-induced suppression of CCN5 in BC cells.

Results

Present studies demonstrate that leptin can induce cell viability, EMT, sphere-forming ability and migration of MCF-7 and ZR-75-1 cell lines. Furthermore, these studies found that leptin suppresses the expression of CCN5 at the transcriptional level. Although the CCN5 suppression has no impact on the constitutive proliferation of MCF-7 and ZR-75-1 cells, it is critical for leptin-induced viability and necessary for EMT, induction of in vitro migration and sphere formation, as the hrCCN5 treatment significantly inhibits the leptin-induced viability, EMT, migration and sphere-forming ability of these cells. Mechanistically, CCN5-suppression by leptin is mediated via activating JAK/AKT/STAT-signaling pathways.

Conclusions

These studies suggest that CCN5 serves as a gatekeeper for leptin-dependent growth and progression of luminal-type (ER-positive) BC cells. Leptin may thus need to destroy the CCN5-barrier to promote BC growth and progression via activating JAK/AKT/STAT signaling. Therefore, these observations suggest a therapeutic potency of CCN5 by restoration or treatment in obese-related luminal-type BC growth and progression.

Role of CCN5 (WNT1 inducible signaling pathway protein 2) in pancreatic islets

In search of direct targets of insulin-like growth factor (IGF)-1 action, we discovered CCN5 (WNT1 inducible signaling pathway protein 2 [WISP2]) as a novel protein expressed in pancreatic β-cells. As a member of the "CCN" ( C ysteine-rich angiogenic inducer 61 [Cyr61], C onnective tissue growth factor [CTGF in humans], and N ephroblastoma overexpressed [Nov; in chickens]) family, the expression of CCN5/WISP2 is stimulated by IGF-1 together with Wnt signaling. When overexpressed in insulinoma cells, CCN5 promotes cell proliferation and cell survival against streptozotocin-induced cell death. The cell proliferation effect seems to be caused by AKT phosphorylation and increased cyclin D1 levels. These properties resemble those of CCN2/CTGF, another isoform of the CCN family, although CCN5 is the only one within the family of six proteins that lacks the C-terminal repeat. Treatment of primary mouse islets with recombinant CCN5 protein produced similar effects to those of gene transfection, indicating that either as a matricellular protein or a secreted growth factor, CCN5 stimulates β-cell proliferation and regeneration in a paracrine fashion. This review also discusses the regulation of CCN5/WISP2 by estrogen and its involvement in angiogenesis and tumorigenesis.

WISP-2 in human gastric cancer and its potential metastatic suppressor role in gastric cancer cells mediated by JNK and PLC-γ pathways

BACKGROUND

It has recently been shown that WISP proteins (Wnt-inducted secreted proteins), a group of intra- and extra-cellular regulatory proteins, have been implicated in the initiation and progression of a variety of tumour types including colorectal and breast cancer. However, the role of WISP proteins in gastric cancer (GC) cells and their clinical implications have not yet been elucidated.

METHODS

The expression of WISP molecules in a cohort of GC patients was analysed using real-time quantitative PCR and immunohistochemistry. The expression of a panel of recognised epithelial-mesenchymal transition (EMT) markers was quantified using Q-PCR in paired tumour and normal tissues. WISP-2 knockdown (kd) sublines using ribozyme transgenes were created in the GC cell lines AGS and HGC27. Subsequently, several biological functions, including cell growth, adhesion, migration and invasion, were studied. Potential pathways for the interaction of EMT, extracellular matrix and MMP were evaluated.

RESULTS

Overexpression of WISP-2 was detected in GC and significantly correlated with early tumour node-metastasis staging, differentiation status and positively correlated with overall survival and disease-free survival of the patients. WISP-2 expression was inversely correlated with that of Twist and Slug in paired samples. Kd of WISP-2 expression promoted the proliferation, migration and invasion of GC cells. WISP-2 suppressed GC cell metastasis through reversing EMT and suppressing the expression and activity of MMP9 and MMP2 via JNK and ERK. Cell motility analysis indicated that WISP-2 kd contributed to GC cells' motility and can be attenuated by PLC-γ and JNK small inhibitors.

CONCLUSIONS

Increased expression of WISP-2 in GC is positively correlated with favourable clinical features and the survival of patients with GC and is a negative regulator of growth, migration and invasion in GC cells. These findings suggest that WISP-2 is a potential tumour suppressor in GC.

The expression of Wnt-1 inducible signaling pathway protein-2 in astrocytoma: Correlation between pathological grade and clinical outcome

Wnt-1 inducible signaling pathway protein-2 (WISP-2) is a member of the CCN family, which is critical for the control of cell morphology, motion, adhesion and other processes involved in tumorigenesis. The expression pattern and clinical significance of WISP-2 in astrocytomas remains unclear. In this study, reverse transcription-polymerase chain reaction was performed to systematically investigate the expression of WISP-2 in 47 astrocytoma tissues of different pathological grades and 10 normal brain tissues. The mRNA expression levels of WISP-2 in the astrocytoma tissues were observed to be significantly higher than those in the normal brain tissues. Furthermore, the upregulation of WISP-2 was found to be associated with astrocytomas of higher pathological grades. Subsequently, 154 astrocytoma and 15 normal brain tissues were analyzed using immunohistochemistry and similar results were obtained. Univariate and multivariate survival analyses were used to determine the correlations between WISP-2 expression and overall survival (OS) and progression-free survival (PFS). The results indicated that the expression of WISP-2 was found to negatively correlate with patient PFS and OS. These results demonstrated that the WISP-2 protein is involved in the pathogenesis and progression of human astrocytomas and may serve as a malignant biomarker of this disease.

Transcriptional regulation of myotrophic actions by testosterone and trenbolone on androgen-responsive muscle

Androgens regulate body composition and skeletal muscle mass in males, but the molecular mechanisms are not fully understood. Recently, we demonstrated that trenbolone (a potent synthetic testosterone analogue that is not a substrate for 5-alpha reductase or for aromatase) induces myotrophic effects in skeletal muscle without causing prostate enlargement, which is in contrast to the known prostate enlarging effects of testosterone. These previous results suggest that the 5α-reduction of testosterone is not required for myotrophic action. We now report differential gene expression in response to testosterone versus trenbolone in the highly androgen-sensitive levator ani/bulbocavernosus (LABC) muscle complex of the adult rat after 6weeks of orchiectomy (ORX), using real time PCR. The ORX-induced expression of atrogenes (Muscle RING-finger protein-1 [MuRF1] and atrogin-1) was suppressed by both androgens, with trenbolone producing a greater suppression of atrogin-1 mRNA compared to testosterone. Both androgens elevated expression of anabolic genes (insulin-like growth factor-1 and mechano-growth factor) after ORX. ORX-induced increases in expression of glucocorticoid receptor (GR) mRNA were suppressed by trenbolone treatment, but not testosterone. In ORX animals, testosterone promoted WNT1-inducible-signaling pathway protein 2 (WISP-2) gene expression while trenbolone did not. Testosterone and trenbolone equally enhanced muscle regeneration as shown by increases in LABC mass and in protein expression of embryonic myosin by western blotting. In addition, testosterone increased WISP-2 protein levels. Together, these findings identify specific mechanisms by which testosterone and trenbolone may regulate skeletal muscle maintenance and growth.

CCN5/WISP-2 promotes growth arrest of triple-negative breast cancer cells through accumulation and trafficking of p27(Kip1) via Skp2 and FOXO3a regulation

The matricellular protein CCN5/WISP-2 represents a promising target in triple-negative breast cancer (TNBC) because treatment or induced activation of CCN5 in TNBC cells promotes cell growth arrest at the G0/G1 phase, reduces cell proliferation and delays tumor growth in the xenograft model. Our studies found that the p27(Kip1) tumor suppressor protein is upregulated and relocalized to the nucleus from cytoplasm by CCN5 in these cells and that these two events (upregulation and relocalization of p27(Kip1)) are critical for CCN5-induced growth inhibition of TNBC cells. In the absence of CCN5, p27(Kip1) resides mostly in the cytoplasm, which is associated with the aggressive nature of cancer cells. Mechanistically, CCN5 inhibits Skp2 expression, which seems to stabilize the p27(Kip1) protein in these cells. On the other hand, CCN5 also recruits FOXO3a to mediate the transcriptional regulation of p27(Kip1). The recruitment of FOXO3a is achieved by the induction of its expression and activity through shifting from cytoplasm to the nucleus. Our data indicate that CCN5 blocks PI3K/AKT signaling to dephosphorylate at S318, S253 and Thr32 in FOXO3a for nuclear relocalization and activation of FOXO3a. Moreover, inhibition of α6β1 receptors diminishes CCN5 action on p27(Kip1) in TNBC cells. Collectively, these data suggest that CCN5 effectively inhibits TNBC growth through the accumulation and trafficking of p27(Kip1) via Skp2 and FOXO3a regulation, and thus, activation of CCN5 may have the therapeutic potential to kill TNBC.

Hypoxia-inducible factor-mediated induction of WISP-2 contributes to attenuated progression of breast cancer

Hypoxia and the hypoxia-inducible factor (HIF) signaling pathway trigger the expression of several genes involved in cancer progression and resistance to therapy. Transcriptionally active HIF-1 and HIF-2 regulate overlapping sets of target genes, and only few HIF-2 specific target genes are known so far. Here we investigated oxygen-regulated expression of Wnt-1 induced signaling protein 2 (WISP-2), which has been reported to attenuate the progression of breast cancer. WISP-2 was hypoxically induced in low-invasive luminal-like breast cancer cell lines at both the messenger RNA and protein levels, mainly in a HIF-2α-dependent manner. HIF-2-driven regulation of the WISP2 promoter in breast cancer cells is almost entirely mediated by two phylogenetically and only partially conserved functional hypoxia response elements located in a microsatellite region upstream of the transcriptional start site. High WISP-2 tumor levels were associated with increased HIF-2α, decreased tumor macrophage density, and a better prognosis. Silencing WISP-2 increased anchorage-independent colony formation and recovery from scratches in confluent cell layers of normally low-invasive MCF-7 cancer cells. Interestingly, these changes in cancer cell aggressiveness could be phenocopied by HIF-2α silencing, suggesting that direct HIF-2-mediated transcriptional induction of WISP-2 gene expression might at least partially explain the association of high HIF-2α tumor levels with prolonged overall survival of patients with breast cancer.

Loss of WISP2/CCN5 in estrogen-dependent MCF7 human breast cancer cells promotes a stem-like cell phenotype

It has been proposed that the epithelial-mesenchymal transition (EMT) in mammary epithelial cells and breast cancer cells generates stem cell features. WISP2 (Wnt-1-induced signaling protein-2) plays an important role in maintenance of the differentiated phenotype of estrogen receptor-positive breast cancer cells and loss of WISP2 is associated with EMT. We now report that loss of WISP2 in MCF7 breast cancer cells can also promote the emergence of a cancer stem-like cell phenotype characterized by high expression of CD44, increased aldehyde dehydrogenase activity and mammosphere formation. Higher levels of the stem cell markers Nanog and Oct3/4 were observed in those mammospheres. In addition we show that low-cell inoculums are capable of tumor formation in the mammary fat pad of immunodeficient mice. Gene expression analysis show an enrichment of markers linked to stem cell function such as SOX9 and IGFBP7 which is linked to TGF-β inducible, SMAD3-dependent transcription. Taken together, our data demonstrate that WISP2 loss promotes both EMT and the stem-like cell phenotype.

Wnt1 inducible signalling pathway protein-2 (WISP‑2/CCN5): roles and regulation in human cancers (review)

Wnt1 inducible signalling pathway protein-2 (WISP‑2), also known as CCN5, CT58, CTGF-L, CTGF-3, HICP and Cop1, is one of the 3 WNT1 inducible proteins that belongs to the CCN family. This family of members has been shown to play multiple roles in a number of pathophysiological processes, including cell proliferation, adhesion, wound healing, extracellular matrix regulation, epithelial-mesenchymal transition, angiogenesis, fibrosis, skeletal development and embryo implantation. Recent results suggest that WISP-2 is relevant to tumorigenesis and malignant transformation, particularly in breast cancer, colorectal cancer and hepatocarcinoma. Notably, its roles in cancer appear to vary depending on cell/tumour type and the microenvironment. The striking difference in the structure of WISP-2 in comparison with the other 2 family members may contribute to its difference in functions, which leads to the hypothesis that WISP-2 may act as a dominant-negative regulator of other CCN family members. In the present review, we summarise the roles, regulation and underlying mechanism of WISP-2 in human cancers.

CCN5/WISP-2: A micromanager of breast cancer progression

The gain of plasticity by a subset of cancer cells is a unique but common sequence of cancer progression from epithelial phenotype to mesenchymal phenotype (EMT) that is followed by migration, invasion and metastasis to a distant organ, and drug resistance. Despite multiple studies, it is still unclear how cancer cells regulate plasticity. Recent studies from our laboratory and others' proposed that CCN5/WISP-2, which is found intracellularly (in the nucleus and cytoplasm) and extracellularly, plays a negative regulator of plasticity. It prevents the EMT process in breast cancer cells as well as pancreatic cancer cells. Multiple genetic insults, including the gain of p53 mutations that accumulate over the time, may perturb CCN5 expression in non-invasive breast cancer cells, which ultimately helps cells to gain invasive phenotypes. Moreover, emerging evidence indicates that several oncogenic lesions such as miR-10b upregulation and activation of TGF-β-signaling can accumulate during CCN5 crisis in breast cancer cells. Collectively, these studies indicate that loss of CCN5 activity may promote breast cancer progression; application of CCN5 protein may represent a novel therapeutic intervention in breast cancer and possibly pancreatic cancer.

Cysteine-rich 61-connective tissue growth factor-nephroblastoma-overexpressed 5 (CCN5)/Wnt-1-induced signaling protein-2 (WISP-2) regulates microRNA-10b via hypoxia-inducible factor-1α-TWIST signaling networks in human breast cancer cells

MicroRNAs (miRNAs) are naturally occurring single-stranded RNA molecules that post-transcriptionally regulate the expression of target mRNA transcripts. Many of these target mRNA transcripts are involved in regulating processes commonly altered during tumorigenesis and metastatic growth. These include cell proliferation, differentiation, apoptosis, migration, and invasion. Among the several miRNAs, miRNA-10b (miR-10b) expression is increased in metastatic breast cancer cells and positively regulates cell migration and invasion through the suppression of the homeobox D10 (HOXD10) tumor suppressor signaling pathway. In breast metastatic cells, miR-10b expression is enhanced by a transcription factor TWIST1. We find that miR-10b expression in breast cancer cells can be suppressed by CCN5, and this CCN5 effect is mediated through the inhibition of TWIST1 expression. Moreover, CCN5-induced inhibition of TWIST1 expression is mediated through the translational inhibition/modification of hypoxia-inducible factor-1α via impeding JNK signaling pathway. Collectively, these studies suggest a novel regulatory pathway exists through which CCN5 exerts its anti-invasive function. On the basis of these findings, it is plausible that reactivation of CCN5 in miR-10b-positive invasive/metastatic breast cancers alone or in combination with current therapeutic regimens could provide a unique, alternative strategy to existing breast cancer therapy.

Cyr61/CCN1 signaling is critical for epithelial-mesenchymal transition and stemness and promotes pancreatic carcinogenesis

BACKGROUND

Despite recent advances in outlining the mechanisms involved in pancreatic carcinogenesis, precise molecular pathways and cellular lineage specification remains incompletely understood.

RESULTS

We show here that Cyr61/CCN1 play a critical role in pancreatic carcinogenesis through the induction of EMT and stemness. Cyr61 mRNA and protein were detected in the early precursor lesions and their expression intensified with disease progression. Cyr61/CCN1 expression was also detected in different pancreatic cancer cell lines. The aggressive cell lines, in which the expressions of mesenchymal/stem cell molecular markers are predominant; exhibit more Cyr61/CCN1 expression. Cyr61 expression is exorbitantly higher in cancer stem/tumor initiating Panc-1-side-population (SP) cells. Upon Cyr61/CCN1 silencing, the aggressive behaviors are reduced by obliterating interlinking pathobiological events such as reversing the EMT, blocking the expression of stem-cell-like traits and inhibiting migration. In contrast, addition of Cyr61 protein in culture medium augments EMT and stemness features in relatively less aggressive BxPC3 pancreatic cancer cells. Using a xenograft model we demonstrated that cyr61/CCN1 silencing in Panc-1-SP cells reverses the stemness features and tumor initiating potency of these cells. Moreover, our results imply a miRNA-based mechanism for the regulation of aggressive behaviors of pancreatic cancer cells by Cyr61/CCN1.

CONCLUSIONS

In conclusion, the discovery of the involvement of Cyr61/CCN1 in pancreatic carcinogenesis may represent an important marker for PDAC and suggests Cyr61/CCN1 can be a potential cancer therapeutic target.

CCN5: biology and pathophysiology

CCN5 is one of six proteins in the CCN family. This family of proteins has been shown to play important roles in many processes, including proliferation, migration, adhesion, extracellular matrix regulation, angiogenesis, tumorigenesis, fibrosis, and implantation. In this review, we focus on the biological and putative pathophysiological roles of CCN5. This intriguing protein is structurally unique among the CCN family members, and has a unique biological activity profile as well.

CCN5: biology and pathophysiology

CCN5 is one of six proteins in the CCN family. This family of proteins has been shown to play important roles in many processes, including proliferation, migration, adhesion, extracellular matrix regulation, angiogenesis, tumorigenesis, fibrosis, and implantation. In this review, we focus on the biological and putative pathophysiological roles of CCN5. This intriguing protein is structurally unique among the CCN family members, and has a unique biological activity profile as well.

Morphologic transformation of human breast epithelial cells MCF-10A: dependence on an oxidative microenvironment and estrogen/epidermal growth factor receptors

Background

MCF-10A, immortalized but non-transformed human breast epithelial cells, are widely used in research examining carcinogenesis. The studies presented here were initiated with the observation that MCF-10A cells left in continuous culture for prolonged periods without re-feeding were prone to the development of transformed foci. We hypothesized that the depletion of labile culture components led to the onset of processes culminating in the observed cell transformation. The purpose of this study was to define the factors which promoted transformation of this cell line.

Results

Changes in levels of phenol red (PHR), hydrocortisone (HC), and epidermal growth factor (EGF) with or without estrogen treatment indicated that both oxidative stress- and estrogen receptor alpha (ERα)-mediated pathways contribute to cell transformation. Gene array and Western blotting analyses of cells maintained in our laboratory and of those from other sources documented detectable ERα and ERbeta (ERβ) in this ERα-negative cataloged cell line. Results also indicate the possibility of a direct association of EGF receptor (EGFR) and ERα in these cells as well as the formation and high induction of a novel ternary complex that includes ERβ (ERα/ERβ/EGFR) in cells grown under conditions facilitating transformation.

Conclusions

Our studies resulted in the development of a growth protocol where the effects of chronic, physiologically relevant alterations in the microenvironment on cellular transformation were examined. From our results, we were able to propose a model of transformation within the MCF-10A cell line in which oxidative stress, ER and EGFR play essential roles. Overall, our work indicates that the immediate microenvironment of cells exerts powerful growth cues which ultimately determine their transformation potential.

Positive correlation of steroid hormones and EGF in canine mammary cancer

There are no published studies focused on the potential crosstalk between steroid hormones and EGF in canine mammary tumourigenesis. The objective was to investigate the role of EGF in canine mammary tumours (CMT) and the relationship with steroid hormones. Sixty-three CMT (39 malignant including 10 inflammatory mammary carcinomas (IMC); 19 benign and 5 dysplasias), and 13 normal mammary glands from dogs without history of neoplastic disease were analysed. Levels of EGF and steroid hormones [progesterone (P4); 17beta-estradiol (E2); androstenedione (A4) and dehydroepiandrosterone (DHEA)], were analysed by EIA in CMT homogenates. Levels of EGF were significantly higher in malignant compared with benign tumours, dysplasias and normal mammary glands (p<0.001). IMC presented the highest EGF levels, with statistical significant difference between IMC and non-IMC cases (p<0.05). Steroid hormone levels were also significantly higher in malignant tumours compared with benign tumours, dysplasias and normal mammary glands (p<0.001). In malignant tumours (non-IMC and IMC), a strong correlation was observed between EGF and: P4 (r=0.452; p=0.003); E2 (r=0.624; p=0.023); A4 (r=0.496; p=0.038); DHEA (r=0.431; p=0.005). These results suggest that EGF is implicated in canine mammary tumourigenesis. The positive correlation observed, opens an interesting perspective of interaction that should be further investigated.

Crocetin inhibits pancreatic cancer cell proliferation and tumor progression in a xenograft mouse model

Crocetin, a carotenoid compound derived from saffron, has long been used as a traditional ancient medicine against different human diseases including cancer. The aim of the series of experiments was to systematically determine whether crocetin significantly affects pancreatic cancer growth both in vitro and/or in vivo. For the in vitro studies, first, MIA-PaCa-2 cells were treated with crocetin and in these sets of experiments, a proliferation assay using H(3)-thymidine incorporation and flow cytometric analysis suggested that crocetin inhibited proliferation. Next, cell cycle proteins were investigated. Cdc-2, Cdc-25C, Cyclin-B1, and epidermal growth factor receptor were altered significantly by crocetin. To further confirm the findings of inhibition of proliferation, H(3)-thymidine incorporation in BxPC-3, Capan-1, and ASPC-1 pancreatic cancer cells was also significantly inhibited by crocetin treatment. For the in vivo studies, MIA-PaCa-2 as highly aggressive cells than other pancreatic cancer cells used in this study were injected into the right hind leg of the athymic nude mice and crocetin was given orally after the development of a palpable tumor. The in vivo results showed significant regression in tumor growth with inhibition of proliferation as determined by proliferating cell nuclear antigen and epidermal growth factor receptor expression in the crocetin-treated animals compared with the controls. Both the in vitro pancreatic cancer cells and in vivo athymic nude mice tumor, apoptosis was significantly stimulated as indicated by Bax/Bcl-2 ratio. This study indicates that crocetin has a significant antitumorigenic effect in both in vitro and in vivo on pancreatic cancer.

CCN5/WISP-2 expression in breast adenocarcinoma is associated with less frequent progression of the disease and suppresses the invasive phenotypes of tumor cells

Although previous in vitro studies predicted that CCN5/WISP-2 may act as an anti-invasive gene in breast cancer, the distribution pattern of CCN5 in breast cancer samples is conflicting. Thus, we systematically investigated the CCN5 expression profile in noninvasive and invasive breast tumor samples and its functional relevance in breast cancer progression. The studies showed that CCN5 expression is biphasic, such that in normal samples CCN5 expression is undetectable, whereas its expression is markedly increased in noninvasive breast lesions, including atypical ductal hyperplasia and ductal carcinoma in situ. Further, CCN5 mRNA and protein levels are significantly reduced as the cancer progresses from a noninvasive to invasive type. Additionally, we showed that CCN5 mRNA and protein level was almost undetectable in poorly differentiated cancers compared with the moderately or well-differentiated samples and its expression inversely correlated with lymph node positivity. The result was further supported by evaluating the RNA expression profile in microdissected sections using real-time PCR analysis. Therefore, our data suggest a protective function of CCN5 in noninvasive breast tumor cells. This hypothesis was further supported by our in vitro studies illuminating that CCN5 is a negative regulator of migration and invasion of breast cancer cells, and these events could be regulated by CCN5 through the modulation of the expression of genes essential for an invasive front. These include Snail-E-cadherin signaling and matrix metalloproteinase (MMP)-9 and MMP-2. Collectively, these studies suggest that the protective effect of CCN5 in breast cancer progression may have important therapeutic implications.

(-)-Epigallocatechin-3-gallate downregulates estrogen receptor alpha function in MCF-7 breast carcinoma cells

BACKGROUND

(-)-Epigallocatechin-3-gallate (EGCG) is the most active catechin present in green tea, demonstrated to have chemopreventive action and to kill cancer cells selectively. As a previous study found that catechins could compete with 17-beta-estradiol for binding to estrogen receptor alpha (ERalpha), we asked whether EGCG could regulate ERalpha action.

METHODS

We used MCF-7, a breast carcinoma cell line having a high level of ERalpha expression. The cells were treated with various EGCG concentrations and cell viability was evaluated by MTT assay. ERalpha and pS2 expression were analyzed by RT-PCR after RNA extraction. To better define EGCG action in relation to ERalpha, we studied EGCG cytotoxicity on MCF-7 resistant to tamoxifen (MCF-7tam), MCF-7 treated with 10(-7)M ICI 182,780 for 8 days and on MDA-MB-231, a cell line that lacked ERalpha by flow cytometry (FCM).

RESULTS

Both ERalpha and pS2 mRNA were expressed in samples treated with low EGCG concentration (30 microg/ml). At this concentration, no cell change was detectable. In contrast, pS2 expression was lost in samples treated with 100 microg/ml EGCG for 24h, indicating ERalpha alteration. EGCG cytotoxicity was lower when ERalpha was not present (MDA-MB-231) or inactivated (by tamoxifen or ICI 182,780).

CONCLUSIONS

Functionally active ERalpha may have a role in EGCG cytotoxicity, increasing the sensitivity to the drug. As higher EGCG concentrations also killed cells resistant to tamoxifen or treated by 10(-7)M ICI 182,780, EGCG ought to be better investigated in breast carcinoma cells treated with drugs targeted to steroid receptors, as a potential complement of therapy.

Role of WISP-2/CCN5 in the maintenance of a differentiated and noninvasive phenotype in human breast cancer cells

WISP-2/CCN5 is an estrogen-regulated member of the "connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed" (CCN) family of the cell growth and differentiation regulators. The WISP-2/CCN5 mRNA transcript is undetectable in normal human mammary cells, as well as in highly aggressive breast cancer cell lines, in contrast with its higher level in the breast cancer cell lines characterized by a more differentiated phenotype. We report here that knockdown of WISP-2/CCN5 by RNA interference in estrogen receptor alpha (ERalpha)-positive MCF-7 breast cancer cells induced an estradiol-independent growth linked to a loss of ERalpha expression and promoted epithelial-to-mesenchymal transdifferentiation. In contrast, forced expression of WISP-2/CCN5 directed MCF-7 cells toward a more differentiated phenotype. When introduced into the poorly differentiated, estrogen-independent, and invasive MDA-MB-231 breast cancer cells, WISP-2/CCN5 was able to reduce their proliferative and invasive phenotypes. In a series of ERalpha-positive tumor biopsies, we found a positive correlation between the expression of WISP-2/CCN5 and ID2, a transcriptional regulator of differentiation in normal and transformed breast cells. We propose that WISP-2/CCN5 is an important regulator involved in the maintenance of a differentiated phenotype in breast tumor epithelial cells and may play a role in tumor cell invasion and metastasis.

Loss of WISP-2/CCN5 signaling in human pancreatic cancer: A potential mechanism for epithelial-mesenchymal-transition

The objective of this study was to explore the pathophysiological relevance of WISP-2/CCN5 in progression of human pancreatic adenocarcinoma (PAC). We found WISP-2/CCN5 mRNA and protein expression was faint and sporadic in PAC and detected in only 8.7-20% of the samples with varying grades as compared to adjacent normal and chronic pancreatitis samples where expression was very high in the ducts and acini. Colocalization studies in tissue-microarray slides revealed WISP-2/CCN5 mRNA loss was associated with p53 overexpression in PAC. Like tissue samples, p53 mutant-PAC cell lines show loss of WISP-2/CCN5. Moreover, functional analysis studies demonstrate exposure of pancreatic cancer cells to WISP-2/CCN5 recombinant protein enhances mesenchymal-epithelial-transition (MET). Collectively, we suggest WISP-2/CCN5 silencing may be a critical event during differentiation and progression of PAC and mutant p53 is possibly an important player in pursuing this episode.

Differential Expression and Prognostic Implications of the CCN Family Members WISP-1, WISP-2, and WISP-3 in Human Breast Cancer

BACKGROUND

The CCN family has three Wnt-inducted secreted proteins named WISP-1, WISP-2 and WISP-3. These molecules are known to play a diverse role in cells, but their role in cancer cells remains controversial.

METHODS

In this study, we analyzed the expression of the three WISP molecules at the mRNA and protein levels in a cohort of 122 human breast tumors and 32 normal breast tissues, and we correlated these findings with patients' clinical outcomes.

RESULTS

WISP-1 transcripts were found in lower levels in node-positive tumors compared with node-negative tumors (P < .05); were lower in patients with a moderate (P = .01) and poor Nottingham Prognostic Index prognosis (P < .05) compared with good prognostic groups; were of significantly lower level in grade 3 differentiated tumors (P < .05) compared with grade 1; and were of lower levels in patients who developed metastasis and died from breast cancer-related causes (P < .05 in both comparisons). Almost the reverse was found to be true for WISP-2, which had greater levels of expression in node-positive tumors (P = .0043); higher levels in both moderate and poor prognostic groups compared with the good prognostic group (both P < .05); greater level in both grade 2 and 3 when compared with grade 1 (both P < .05); and higher levels in patients who went on to develop metastases (P < .01). WISP-3 transcript levels showed no statistically significant differences between groups.

CONCLUSIONS

WISPs may play important but contrasting roles in breast cancer. WISP-1 seems to act as a tumor suppressor and WISP-2 as a factor that stimulates aggressiveness; WISP-3 has no definable beneficial or detrimental role.

Wnt Signaling Pathway in Mammary Gland Development and Carcinogenesis

The signaling pathway mediated by Wingless-type (Wnt) proteins is highly conserved in evolution. This pivotal pathway is known to regulate cell fate decisions, cell proliferation, morphology, migration, apoptosis, differentiation and stem cell self-renewal. It currently includes the canonical or Wnt/beta-catenin pathway in which Wnt proteins bind to 'frizzled' receptors, which leads to downstream activation of gene transcription by beta-catenin. Second, the noncanonical or beta-catenin-independent pathways are now known to be mediated by three possible mechanisms: (1) the Wnt/Ca(2+) pathway, (2) the Wnt/G protein signaling pathway, and (3) the Wnt/PCP or planar cell polarity pathway. Wnt signaling is implicated at several stages of mammary gland growth and differentiation, and possibly in the involution of mammary gland following lactation. Recent evidence suggests the role of Wnt signaling in human breast cancer involves elevated levels of nuclear and/or cytoplasmic beta-catenin using immunohistochemistry, overexpression or downregulation of specific Wnt proteins, overexpression of CKII and sFRP4, downregulation of WIF-1 and sFRP1, as well as amplification of DVL-1. Further research is required to determine how Wnt signaling is involved in the development of different histological types of breast cancer and whether it promotes the viability of cancer stem cells or not.

Insulin-like Growth Factor-1 (IGF-1) Induces WISP-2/CCN5 via Multiple Molecular Cross-talks and Is Essential for Mitogenic Switch by IGF-1 Axis in Estrogen Receptor–Positive Breast Tumor Cells

Previously, we have shown that the expression of Wnt-1-induced signaling protein-2 (WISP-2), also known as CCN5, can be regulated by multiple stimulants in estrogen receptor (ER)-positive breast tumor cells to exert their mitogenic action in these cells. Here, we show that insulin-like growth factor-1 (IGF-1), a strong mitogen, enhanced the expression of the WISP-2/CCN5 gene parallel with the induction of proliferation of ER-positive breast tumor cells. An additive effect was also seen in combination with estrogen. Perturbation of IGF-1-induced WISP-2/CCN5 expression by WISP-2-specific RNA interference impaired the mitogenic action of IGF-1 on ER-positive breast tumor cells. Furthermore, the studies have shown that the multiple molecular cross-talks and side-talks among IGF-1R, ER-alpha, and phosphatidylinositol 3-kinase (PI3K)/Akt signaling molecules are required to induce WISP-2/CCN5 mRNA by IGF-1 in ER-positive, noninvasive breast tumor cells. Because a pure anti-ER ICI 182,780 is not only able to suppress the up-regulation of WISP-2/CCN5 mRNA expression by IGF-1, it also suppresses the PI3K/Akt activity induced by IGF-1 in MCF-7 cells; we anticipate that the membrane ER receptor may participate in this event. Collectively, these studies propose for the first time that WISP-2/CCN5 is an integral signaling molecule in mitogenic action of IGF-1 axis in ER-positive human breast tumor cells.

The epidermal growth factor family has a dual role in deciding the fate of cancer cells

Expression of the epidermal growth factor (EGF) receptors HER1 and HER2 has been implicated in tumour growth and poor survival, whereas expression of HER3 and HER4 has been associated with improved survival of bladder cancer patients. The balance between the expression of the EGF family members may therefore have a role to play in determining the final outcome in cancer cells. To check this, we examined the effect of HER1 activation and inhibition on the expression of the EGF receptors HER3 and HER4 and ligands - the heregulins (HRGs). RT4 bladder cancer cells were treated with 1nM HB-EGF (known to induce cell proliferation by activating HER1 receptor) and the mRNA content of the two receptors (HER3 and HER4) and their activating ligands (HRG1-HRG4) was quantified by real time PCR at indicated time-points. Expressions of HRG1alpha and HRG1beta increased 8-fold and 9-fold, respectively, whereas the expressions of HRG2alpha (4-fold), HRG2beta (2.5-fold) and HRG4 (3.5-fold) decreased. In contrast, inhibition of tyrosine kinase activity of HER1 with 5 microM Iressa (a specific inhibitor of HER1) resulted in an increase in mRNA expression of HRG2alpha (2.5-fold) and HRG4 (1.5-fold). In addition, expression of the receptors HER3 (1.5-fold) and HER4 (2-fold) was also increased. In conclusion, we demonstrate that activation of the HER1 receptor suppressed the expression of a specific set of HRGs. A decrease in expression of HRG2 and HRG4 during HB-EGF treatment supports their role in growth inhibition, whereas an increase in HRG1 expression points to a role as a growth stimulatory member of the EGF family.

Breast cancer cells secreted platelet-derived growth factor-induced motility of vascular smooth muscle cells is mediated through neuropilin-1

Motility of vascular smooth muscle cells (SMCs) is an essential step for both normal and pathologic angiogenesis. We report here that breast tumor cells, such as MCF-7 and MDA-MB-231, can modulate this SMC migration. We present evidence that the tumor cell-derived platelet-derived growth factor (PDGF) is the key regulator of vascular SMCs motility induced by breast cancer cells. PDGF significantly upregulates neuropilin-1 (NRP-1) mRNA expression and protein production in aortic smooth muscle cells (AOSMCs) and depletion of NRP-1 production by AOSMCs with specific short hairpin RNA (shRNA) prevents the PDGF-dependent migration of vascular SMCs. Moreover, we demonstrate that PDGF physically interacts with NRP-1. We propose that tumor-derived PDGF and NRP-1 of AOSMCs function as a relay system that promotes motility of vascular SMCs.