In vitro blood compatibility and in vitro cytotoxicity of amphiphilic poly-N-vinylpyrrolidone nanoparticles

This study focused on defining the in vitro behavior of amphiphilic poly-N-vinylpyrrolidone (Amph-PVP) nanoparticles toward whole blood, blood plasma and blood cells in order to assess nanoparticle blood compatibility. In addition, possible effects on endothelium cell growth/viability were evaluated. The Amph-PVP nanoparticles were formed via self-assembling in aqueous media and composed of a hydrophobic alkyl core and a hydrophilic PVP outer shell. Their blood compatibility was evaluated by investigating their effect on red blood cells (RBCs) or erythrocytes, white blood cells (WBCs) or leukocytes, platelets (PLTs) and on complement system activation. Our results clearly demonstrate that the Amph-PVP nanoparticles are stable in presence of blood serum, have no significant effects on the function of RBCs, WBCs, PLTs and complement system activation. The Amph-PVP nanoparticles did not show considerable hemolytic or inflammatory effect, neither influence on platelet aggregation, coagulation process, or complement activation at the tested concentration range of 0.05-0.5 mg/ml. The Amph-PVP nanoparticles did not exhibit any significant effect on HMEC-1 microvascular skin endothelial cells' growth in in vitro experiments. The excellent blood compatibility of the Amph-PVP nanoparticles and the lack of effect on endothelium cell growth/viability represent a crucial feature dictating their further study as novel drug delivery systems.

Heparan sulfate proteoglycans and heparin regulate melanoma cell functions

BACKGROUND

The solid melanoma tumor consists of transformed melanoma cells, and the associated stromal cells including fibroblasts, endothelial cells, immune cells, as well as, soluble macro- and micro-molecules of the extracellular matrix (ECM) forming the complex network of the tumor microenvironment. Heparan sulfate proteoglycans (HSPGs) are an important component of the melanoma tumor ECM. Importantly, there appears to be both a quantitative and a qualitative shift in the content of HSPGs, in parallel to the nevi-radial growth phase-vertical growth phase melanoma progression. Moreover, these changes in HSPG expression are correlated to modulations of key melanoma cell functions.

SCOPE OF REVIEW

This review will critically discuss the roles of HSPGs/heparin in melanoma development and progression.

MAJOR CONCLUSIONS

We have correlated HSPGs' expression and distribution with melanoma cell signaling and functions as well as angiogenesis.

GENERAL SIGNIFICANCE

The current knowledge of HSPGs/heparin biology in melanoma provides a foundation we can utilize in the ongoing search for new approaches in designing anti-tumor therapy. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Could growth factor-mediated extracellular matrix deposition and degradation offer the ground for directed pharmacological targeting in fibrosarcoma?

The specific organization of the tumor extracellular matrix (ECM) is an intrinsic and basic step in the convoluted pathways of tumorigenesis. Fibrosarcoma is a rare, lethal, malignant tumor originating from fibroblasts, characterized by the formation of an abundant ECM. Fibroblastoid cells undergoing malignant transformation specifically alter composition and organization of their ECM to facilitate growth, survival and invasion. Fibrosarcoma cells were shown to have a high content and turnover of ECM components including hyaluronan, proteoglycans, collagens, fibronectin and laminin. Cell signaling by endogenous growth factors, such as TGFβ, EGF, FGF2, VEGF and IFG-I, is directly correlated to ECM remodeling, stroma formation and fibrosarcoma progression. In this regard, growth factors affect the expression of matrix macromolecules, such as secreted and cell-associated proteoglycans, hyaluronan and its receptors CD44 and RHAMM, as well as the expression and activity of matrix- degrading metalloproteinases, which are of critical importance in tissue remodeling and fibrosarcoma progression. Therefore, therapeutic approaches considering growth factors and their receptors as well as downstream signaling in human cancers may well be pharmacological targets being currently explored. In this article, we focus on growth factor signaling regulating fibrosarcoma cell ECM organization at the level of deposition and degradation of ECM macromolecules, the relation of ECM remodeling with fibrosarcoma cell malignant behaviour as well as the putative strategies for its therapeutic intervention.

Heparin regulates colon cancer cell growth through p38 mitogen-activated protein kinase signalling

OBJECTIVES

Heparin acts as an extracellular stimulus capable of activating major cell signalling pathways. Thus, we examined the putative mechanisms utilized by heparin to stimulate HT29, SW1116 and HCT116 colon cancer cell growth.

MATERIALS AND METHODS

Possible participation of the mitogen-activated protein kinase (MAPK) cascade on heparin-induced HT29, SW1116 and HCT116 colon cancer cell growth was evaluated using specific MAPK cascade inhibitors, Western blot analysis, real-time quantitative PCR and FACS apoptosis analysis.

RESULTS

Treatment with a highly specific p38 kinase inhibitor, SB203580, significantly (50-70%) inhibited heparin-induced colon cancer cell growth, demonstrating that p38 MAPK signalling is involved in their heparin-induced proliferative response. This was shown to be correlated with increased (up to 3-fold) phosphorylation of 181/182 threonine/tyrosine residues on p38 MAP kinase. Furthermore, heparin inhibited cyclin-dependent kinase inhibitor p21(WAF1/CIP1) and p53 tumour suppressor gene and protein expression up to 2-fold or 1.8-fold, respectively, and stimulated cyclin D1 expression up to 1.8-fold, in these cell lines through a p38-mediated mechanism. On the other hand, treatment with heparin did not appear to affect HT29, SW1116 and HCT116 cell levels of apoptosis.

CONCLUSIONS

This study demonstrates that an extracellular glycosaminoglycan, heparin, finely modulates expression of genes crucial to cell cycle regulation through specific activation of p38 MAP kinase to stimulate colon cancer cell growth.

Regulation of hyaluronan and versican deposition by growth factors in fibrosarcoma cell lines

Versican, a large chondroitin sulphate proteoglycan and hyaluronan (HA), a non-sulphated glycosaminoglycan are major constituents of the pericellular matrix. In many neoplastic tissues, changes in the expression of versican and HA affect tumour progression. Here, we analyse the synthesis of versican and hyaluronan by fibrosarcoma cells, and document how the latter is affected by PDGF-BB, bFGF and TGFB2, growth factors endogenously produced by these cells. Fibrosarcoma cell lines B6FS and HT1080 were utilised and compared with normal lung fibroblasts (DLF). The major versican isoforms expressed by DLF and B6FS cells were V0 and V1. Treatment of B6FS cells with TGFB2 showed a significant increase of V0 and V1 mRNAs. Versican expression in HT1080 cells was not significantly affected by any of the growth factors. In addition, TGFB2 treatment increased versican protein in DLF cells. HA, showed approximately a 2-fold and a 9-fold higher production in DLF cells compared to B6FS and HT1080 cells, respectively. In HT1080 cells, HA biosynthesis was significantly increased by bFGF, whereas, in B6FS cells it was increased by TGFB2 and PDGF-BB. Furthermore, analysis of HA synthases (HAS) expression indicated that HT1080 expressed similar levels of all three HAS isoforms in the following order: HAS2> HAS3> HAS1. bFGF shifted that balance by increasing the abundance of HAS1. The major HAS isoform expressed by B6FS cells was HAS2. PDGF-BB and TGFB2 showed the most prominent effects by increasing both HAS2 and HAS1 isoforms. In conclusion, these growth factors modulated, through upregulation of specific HAS isoforms, HA synthesis, secretion and net deposition to the pericellular matrix.