Expression of RGD minus fibronectin that does not form extracellular matrix fibrils is sufficient to decrease tumor metastasis

Antitumoral and antimetastatic activity of Maitake D-Fraction in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is associated with poor prognosis, high local recurrence rate and high rate of metastasis compared with other breast cancer subtypes. In addition, TNBC lacks a targeted therapy. This scenario highlights the need for novel compounds with high potential for TNBC treatment. In this regard, natural products are important sources of anticancer drugs. D-Fraction, a proteoglucan extracted from the edible and medicinal mushroom Grifola frondosa (Maitake), is a dietary supplement that has been shown to exert both immunostimulatory and immune-independent antitumoral effects on some cancer types. However, its antitumoral potential in TNBC is unknown. Therefore, we employed TNBC cells to investigate if D-Fraction is able to attenuate their aggressive phenotype. We found that D-Fraction decreases MDA-MB-231 cell viability through apoptosis induction and reduces their metastatic potential. D-Fraction increases cell-cell adhesion by increasing E-cadherin protein levels and β-catenin membrane localization, and increases cell-substrate adhesion. D-Fraction also decreases cell motility by affecting actin cytoskeleton rearrangements, and proteolytic activity of MMP-2 and MMP-9. Furthermore, D-Fraction decreases the invasive capacity of MDA-MB-231 cells. In concordance, D-Fraction retards tumor growth and reduces lung metastases in a xenograft model. Altogether, these results suggest the potential therapeutic role of D-Fraction in aggressive TNBC.

Role of non-mulberry silk fibroin in deposition and regulation of extracellular matrix towards accelerated wound healing

Bombyx mori silk fibroin (BMSF) as biopolymer has been extensively explored in wound healing applications. However, limited study is available on the potential of silk fibroin (SF) from non-mulberry (Antheraea assama and Philosamia ricini) silk variety. Herein, we have developed non-mulberry SF (NMSF) based electrospun mats functionalized with epidermal growth factor (EGF) and ciprofloxacin HCl as potential wound dressing. The NMSF based mats exhibited essential properties of wound dressing like biocompatibility, high water retention capacity (440%), water vapor transmission rate (∼2330gm^-2day^-1), high elasticity (∼2.6MPa), sustained drug release and antibacterial activity. Functionalized NMSF mats enhanced the proliferation of human dermal fibroblasts and HaCaT cells in vitro as compared to non-functionalized mats (p⩽0.01) showing effective delivery of EGF. Extensive in vivo wound healing assesment demonstrated accelerated wound healing, enhanced re-epithelialization, highly vascularized granulation tissue and higher wound maturity as compared to BMSF based mats. NMSF mats treated wounds showed regulated deposition of mature elastin, collagen and reticulin fibers in the extracellular matrix of skin. Presence of skin appendages and isotropic collagen fibers in the regenerated skin also demonstrated scar-less healing and aesthetic wound repair.

STATEMENT OF SIGNIFICANCE

A facile fabrication of a ready-to-use bioactive wound dressing capable of concomitantly accelerating the healing process as well as deposition of the extracellular matrix (ECM) to circumvent further scarring complicacies has become a focal point of research. In this backdrop, our present work is based on non-mulberry silk fibroin (NMSF) electrospun antibiotic loaded semi-occlusive mats, mimicking the ECM of skin in terms of morphology, topology, microporous structure and mechanical stiffness. Regulation of ECM deposition and isotropic orientation evinced the potential of the mat as an instructive platform for skin regeneration. The unique peptide motifs of NMSF assisted the augmented recruitment of fibroblast, keratinocytes and endothelial cells leading to accelerated wound healing. Early progression of mature granulation, faster re-epithelialization and angiogenesis in the wounds in in vivo rabbit model forwarded the blended nanofibrous mats of NMSF and PVA ferrying EGF, apt for scarless healing.

Antitumoral Effects of D-Fraction from Grifola Frondosa (Maitake) Mushroom in Breast Cancer

D-Fraction is protein-bound β-1,6 and β-1,3 glucans (proteoglucan) extracted from the edible and medicinal mushroom Grifola frondosa (Maitake). The antitumoral effect of D-Fraction has long been exclusively attributed to their immunostimulatory capacity. However, in recent years increasing evidence showed that D-Fraction directly affects the viability of canine and human tumor cells, independent of the immune system. Previously, we have reported that D-Fraction modulates the expression of genes associated with cell proliferation, cell death, migration, invasion, and metastasis in MCF7 human breast cancer cells. Therefore, the purpose of the current study is to investigate if this modulation of gene expression by Maitake D-Fraction really modulates tumor progression. In the present work, we demonstrate for the first time that Maitake D-Fraction is able to act directly on mammary tumor cells, modulating different cellular processes involved in the development and progression of cancer. We demonstrate that D-Fraction decreases cell viability, increases cell adhesion, and reduces the migration and invasion of mammary tumor cells, generating a less aggressive cell behavior. In concordance with these results, we also demonstrate that D-Fraction decreases tumor burden and the number of lung metastases in a murine model of breast cancer.

Opposite effects of protein kinase C beta1 (PKCbeta1) and PKCepsilon in the metastatic potential of a breast cancer murine model

In this paper we investigated whether protein kinase C (PKC) beta1 and PKCepsilon, members of the classical and novel PKC family, respectively, induce phenotypic alterations that could be associated with tumor progression and metastatic dissemination in a murine model of breast cancer. Stable overexpression of PKCbeta1 in LM3 cells altered their ability to proliferate, adhere, and survive, and impaired their tumorigenicity and metastatic capacity. Moreover, PKCbeta1 induced the re-expression of fibronectin, an extracellular matrix glycoprotein which loss has been associated with the acquisition of a transformed phenotype in different cell models, and exerted an important inhibition on proteases production, effects that probably impact on LM3 invasiveness and dissemination. Conversely, PKCepsilon overexpression enhanced LM3 survival, anchorage-independent growth, and caused a significant increase in spontaneous lung metastasis. Our results suggest PKCbeta1 functions as an inhibitory protein for tumor growth and metastasis dissemination whereas PKCepsilon drives metastatic dissemination without affecting primary tumor growth.

[Functional arginine-containing amino acid sequences in peptides and proteins]

L-arginine is a source of nitrogen oxide and plays a great role in a number of other biochemical processes. Functions and prospects for practical application of five groups of arginine-containing amino acid sequences and synthetic polyarginine sequences are considered. The physiological characteristics of well-known arginine-containing peptides, such as RGD peptides, kyotorphin, and tuftsin, are described in detail. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru

Protein kinase Cepsilon mediates polymeric fibronectin assembly on the surface of blood-borne rat breast cancer cells to promote pulmonary metastasis

Malignant breast cancer cells that have entered the blood circulation from primary mammary fat pad tumors or are grown in end-over-end suspension culture assemble a characteristic, multi-globular polymeric fibronectin (polyFn) coat on their surfaces. Surface polyFn is critical for pulmonary metastasis, presumably by facilitating lung vascular arrest via endothelial dipeptidylpeptidase IV (CD26). Here, we show that cell-surface polyFn assembly is initiated by the state of suspension, is dependent upon the synthesis and secretion of cellular Fn, and is augmented in a dose- and time-dependent manner by plasma Fn. PolyFn assembly is regulated by protein kinase Cepsilon (PKCepsilon), which translocates rapidly and in increasing amounts from the cytosol to the plasma membrane and is phosphorylated. PolyFn assembly is impeded by select inhibitors of this kinase, i.e. bisindolylmaleimide I, Ro-32-0432, Gö6983, and Rottlerin, by the phorbol 12-myristate 13-acetate-mediated and time-dependent loss of PKCepsilon protein and decreased plasma membrane translocation, and more specifically, by stable transfection of lung-metastatic MTF7L breast cancer cells with small interfering RNA-PKCepsilon and dominant-negative PKCepsilon constructs (e.g. RD-PKCepsilon). The inability to assemble a cell surface-associated polyFn coat by knockdown of endogenous Fn or PKCepsilon impedes cancer cells from metastasis to the lungs. The present studies identify a novel regulatory mechanism for polyFn assembly on blood-borne breast cancer cells and depict its effect on pulmonary metastasis.

A hybrid protein of the amino-terminal fragment of urokinase and mutant plasminogen activator inhibitor-2 efficiently inhibits tumor cell invasion and metastasis

The urokinase plasminogen activator(uPA) system plays important roles in tumor cell invasion and metastasis. In the present study, we evaluated the effects of ATF-PAI2CD, a hybrid protein of the amino-terminal fragment of urokinase and mutant plasminogen activator inhibitor-2, on 95D cells in vitro and in vivo. Furthermore, our results support a current hypothesis that fusion protein blocks tumor invasion and motility by inhibiting localized pericellular proteolysis. Treatment of 95D cells with ATF-PAI2CD resulted in a dose-dependent decrease in tumor-cell invasion through matrigel, and ATF-PAI2CD was much more effective than PAI-2CD. In addition, extracellular regular protein kinase (ERK1/2) expression was downregulated and the adhesion ability to fibronectin was increased in 95D cells treated with the fusion protein, which was confirmed by cell adhesion assay. A high-concentration of ATF-PAI2CD caused a significant reduction in tumor volume and weight in BALB/c (nu/nu) mice female inoculated with human 95D cells (5 x 10(6)); the antitumor effects were significant, which demonstrated a 67.9+/-4.2% reduction in tumor growth compared with control mice. The number of lymphatic metastasis was significantly reduced in mice treated with high- and middle- concentrations of ATF-PAI2CD, whereas a low-concentration of ATF-PAI2CD failed to exhibit any antimetastatic effects. In conclusion, the results suggested that the hybrid protein has therapeutic potential for lung carcinoma and other tumors to inhibit tumor invasion and metastasis.

Active Sequences Collection (ASC) database: a new tool to assign functions to protein sequences

Active Sequences Collection (ASC) is a collection of amino acid sequences, with an unique feature: only short sequences are collected, with a demonstrated biological activity. The current version of ASC consists of three sections: DORRS, a collection of active RGD-containing peptides; TRANSIT, a collection of protein regions active as substrates of transglutaminase enzyme (TGase), and BAC, a collection of short peptides with demonstrated biological activity. Literature references for each entry are reported, as well as cross references to other databases, when available. The current version of ASC includes more than 800 different entries. The main scope of this collection is to offer a new tool to investigate the structural features of protein active sites, additionally to similarity searches against large protein databases or searching for known functional patterns. ASC database is available at the web address http://crisceb.unina2.it/ASC/ which also offers a dedicated query interface to compare user-defined protein sequences with the database, as well as an updating interface to allow contribution of new referenced active sequences.

RalA Mediates v-Src, v-Ras, and v-Raf Regulation of CD44 and Fibronectin Expression in NIH3T3 Fibroblasts

Oncogenic transformation of fibroblasts by v-Src and v-Ras is often associated with downregulation of fibronectin (FN) and increased expression of CD44, a receptor for hyaluronan. Both v-Src and v-Ras as well as v-Raf activate phospholipase D through the small GTPase, RalA, an important mediator of transformation and tumorigenesis in vivo. We have therefore investigated whether RalA is involved in the downregulation of FN and overproduction of CD44 upon oncogenic transformation. We report here that compared to untransfected cells NIH3T3 cells transformed by v-Src, v-Ras, or v-Raf have reduced levels of FN and increased levels of CD44. Moreover, the ability to form extracellular FN fibrils was significantly reduced in the oncogene-transformed cells compared to parental controls. Coexpression of the dominant negative S28N-RalA mutant restored the levels of CD44 and FN and the capacity of v-Src-, v-Ras-, and v-Raf-expressing cells to form extracellular FN fibrils, to those observed in NIH3T3 cells. The data presented here show a novel regulatory role for RalA, which is required for tumor formation in transformed NIH3T3 cells, in mediating the signal transduction pathway activated by v-Src, v-Ras, and v-Raf, that leads to FN downregulation and CD44 overexpression.

Identifying differentially expressed genes associated with metastasis of follicular thyroid cancer by cDNA expression array

Patients with follicular thyroid carcinoma have a higher incidence of metastasis than papillary thyroid carcinoma when thyroid cancer is diagnosed. The cDNA expression array technology is utilized herein to profile differentially expressed genes from metastatic human follicular thyroid carcinoma and reveal new tumor markers as well as target genes for therapeutic intervention. Tissue samples were obtained during surgical resection of the thyroid follicular carcinoma and metastatic tissue in the brain of the same patient. Two identical Atlas human cDNA expression arrays were hybridized with 32P-labeled cDNA probes derived from RNA of either primary thyroid cancer or metastatic tissue. Parallel analysis of the hybridized signals allowed us to identify the alteration of gene expression in the metastasis process. Eighteen genes significantly overexpressed and 40 genes significantly underexpressed were identified in the metastatic thyroid cancer. Genes that displayed an altered expression were associated with the processes of cell cycle regulation, apoptosis, DNA damage response, angiogenesis, cell adhesion and mobility, invasion, and immune response. An expression profile of genes that are associated with metastasis process of follicular thyroid cancer was also discussed. Further investigation is required to understand the precise relationship between the altered expression of these genes and the metastasis process of follicular thyroid cancer.

Involvement of fibronectin in the regulation of urokinase production and binding in murine mammary tumor cells

Tumor invasion and metastasis development is a multistep process involving adhesion molecules as well as tumor proteases. It has been reported that tumor cells lacking fibronectin (FN) expression and engineered to re-express FN showed a marked reduction in metastatic ability. Besides its effects on cell adhesion and migration, FN could be modulating other cellular events associated with the metastatic cascade. To test this hypothesis, we analyzed the production of urokinase-type plasminogen activator (uPA), and its receptor (uPAR), 2 molecules involved in the invasive phenotype, in cells over-expressing RGD wild-type FN (FNwt clones) or RGD-mutated FN (FN RGD-minus clones). Secreted uPA activity and antigen were significantly up-regulated in FN-expressing clones, although RGD-minus cells secreted approximately 50% less uPA than the FNwt ones. Interestingly, while control and FN RGD-minus clones were able to readily bind uPA to their surface, FNwt clones exhibited impaired uPA binding. Furthermore, treatment of the parental cell line as well as the control and FN-expressing clones with exogenous purified FN or RGD peptides induced up-regulation of uPA production and the reduction of uPA membrane binding, which was associated with lower expression of uPAR. This modulation by FN was found to be dependent on RGD sequence and beta1 integrin. These results strongly suggest a novel activity for the multifunctional glycoprotein FN regarding the regulation of uPA production as well as the capacity of tumor cells to bind uPA.