Inhibition of melanoma cell binding to type IV collagen by analogs of cell adhesion regulator

Noble polymeric surface conjugated with zwitterionic moieties and antibodies for the isolation of exosomes from human serum

New zwitterionic polymer-coated immunoaffinity beads were developed to resist nonspecific protein adsorption from undiluted human serum for diagnostic applications of exosomes. A zwitterionic sulfobetaine monomer with an amine functional group was employed for simple surface chemistry and antifouling properties. An exosomal biomarker protein, epithelial cell adhesion molecule (EpCAM), was selected as a target molecule in this work. The beads were coated with polyacrylic acids (PAA) for increasing biorecognition sites, and protein G was then conjugated with carboxylic acid groups on the surfaces for controlling EpCAM antibody orientation. The remaining free carboxylic acid groups were modified with sulfobetaine moieties, and anti-EpCAM antibody was finally introduced. The amount of anti-EpCAM on the beads was increased by 40% when compared with PAA-uncoated beads. The surfaces of the beads exhibited near-net-zero charge, and nonspecific protein adsorption was effectively suppressed by sulfobetaine moieties. EpCAM was captured from undiluted human serum with almost the same degree of efficiency as from PBS buffer solution using the newly developed immunoaffinity beads.

Alendronate inhibits cell invasion and MMP-2 secretion in human chondrosarcoma cell line

AIM

Chondrosarcoma is a malignant primary bone tumor that responds poorly to both chemotherapy and radiation therapy. The aim of the present study was to investigate the effect of alendronate, a bisphosphonate, on the invasion and migration of human chondrosarcoma cells (JJ012).

METHODS

JJ012 cells were treated with alendronate of various concentrations up to 100 micromol/L for a specified period, and then gelatin zymography and matrigel invasion assay was performed to study the effects of alendronate on matrix metalloproteinase (MMP)-2 activity and the invasion ability of JJ012 cells, respectively.

RESULTS

Our data showed that alendronate exerted a dose- and time-dependent inhibitory effect on the invasion and migration of JJ012 cells. Furthermore, gelatin zymography and RT-PCR showed that alendronate treatment decreased the activity and mRNA levels of MMP-2 in a concentration-dependent manner.

CONCLUSION

Our findings suggest that alendronate may reduce MMP-2 secretion at the transcriptional and translational levels, and inhibit the invasion of chondrosarcoma cell. Therefore, alendronate may be a potential candidate for the systemic therapy of chondrosarcomas, as well as other malignant diseases.

Alendronate regulates cell invasion and MMP-2 secretion in human osteosarcoma cell lines

BACKGROUND

Osteosarcoma is the most common malignant bone tumor of childhood. Significant proportions of these patients eventually develop pulmonary metastases and succumb to their disease even after conventional multi-agent chemotherapy and surgical excision. Matrix metalloproteinase (MMP)-2 induced degradation of blood vessel basement membranes is an important pre-requisite for tumor invasion and metastasis. Bisphosphonates (BPs) have been known to inhibit tumor growth and metastasis in some tumors such as breast cancer, renal cell carcinoma, and prostate cancer, and may do so through inhibition of MMP secretion. We, therefore, tested the effect of BPs on tumor cell invasion, MMP-2 secretion, and apoptosis of osteosarcoma cell lines.

PROCEDURE

Two osteosarcoma cell lines (SaOS-2, U(2)OS) were treated with alendronate (50, 100, and 150 microM) for 24 and 48 hr. Matrigel invasion assay was used to investigate the invasive potential of osteosarcoma cell lines before and after alendronate treatment. Real-time quantitative RT-PCR was used to determine the mRNA level of MMP-2 with and without alendronate treatment. Enzyme-linked immunosorbent assay (ELISA) was used to quantify the cytokine level of MMP-2 secreted in the condition medium. BP-induced cell apoptosis was evaluated by fluorescent flow cytometric analysis.

RESULTS AND CONCLUSIONS

The results showed that alendronate inhibited cell invasion of both osteosarcoma cell lines in a dose-dependent manner. Alendronate reduced the mRNA level and cellular level of MMP-2 in both cell lines in a time and dose-dependent manner. Alendronate also induced significant apoptosis in both cell lines. Our finding suggests that alendronate downregulates MMP-2 secretion and induces apoptosis in osteosarcoma cells, which may both contribute to the reduction of invasive potential of the tumor cells.

ECM remodeling regulates angiogenesis: endothelial integrins look for new ligands

The process of angiogenesis is a dynamic one. Vascular endothelial cells are changing at the same time the extracellular matrix is being remodeled. Stupack and Cheresh discuss how remodeling of the extracellular matrix (ECM) and changes in the endothelial cell protein production and integrin expression contribute to the complex process of new blood vessel growth from an existing vascular bed.

Protein-like molecular architecture: biomaterial applications for inducing cellular receptor binding and signal transduction

The development of biomaterials with desirable biocompatibility has presented a difficult challenge for tissue engineering researchers. First and foremost, materials themselves tend to be hydrophobic and/or thrombogenic in nature, and face compatibility problems upon implantation. To mediate this problem, researchers have attempted to graft protein fragments onto biomaterial surfaces to promote endothelial cell attachment and minimize thrombosis. We envisioned a novel approach, based on the capability of biomolecules to self-assemble into well-defined and intricate structures, for creating biomimetic biomaterials that promote cell adhesion and proliferation. One of the most intriguing self-assembly processes is the folding of peptide chains into native protein structures. We have developed a method for building protein-like structural motifs that incorporate sequences of biological interest. A lipophilic moiety is attached onto a N alpha-amino group of peptide chain, resulting in a "peptide-amphiphile." The alignment of amphiphilic compounds at the lipid-solvent interface is used to facilitate peptide alignment and structure initiation and propagation, while the lipophilic region absorbs to hydrophobic surfaces. Peptide-amphiphiles containing potentially triple-helical or alpha-helical structural motifs have been synthesized. The resultant head group structures have been characterized by CD spectroscopy and found to be thermally stable over physiological temperature ranges. Triple-helical peptide-amphiphiles have been applied to studies of surface modification and cell receptor binding. Cell adhesion and spreading was promoted by triple-helical peptide-amphiphiles. Cellular interaction with the type IV collagen sequence alpha 1(IV) 1263-1277 increased signal transduction, with both the time and level of induction dependent upon triple-helical conformation. Collectively, these results suggest that peptide-amphiphiles may be used to form stable molecular structure on biomaterial surfaces that promote cellular activities and improve biocompatibility.

A fast and inexpensive method for N-terminal fluorescein-labeling of peptides

A new method has been developed to synthesize fluorescein labeled peptides, compounds of increasing importance in bioorganic chemistry, cell biology, pharmacology, drug targeting and medicinal chemistry. We show, that 4(5)-carboxyfluorescein is much more efficient than the hitherto predominantly utilized reagents 4(5)-carboxyfluorescein-N-succinimidylester and 4(5)-fluoresceinisothiocyanate.

In vitro incorporation of synthetic peptides into cells

This article gives a specific example of how a reversible permeabilization kit can be adapted for use with a specific peptide-based protocol. It was relatively easy to design and run the control experiments to determine the necessary adaptations. The basic procedure given with the TRANS-PORT kit is amenable to modification such that is can be used with numerous other in vitro procedures.