A Novel High-Throughput Screening Method for a Human Multicentric Osteosarcoma-Specific Antibody and Biomarker Using a Phage Display-Derived Monoclonal Antibody.

Osteosarcoma is a malignant tumor that produces neoplastic bone or osteoid osteoma. In human multicentric osteosarcoma (HMOS), a unique variant of human osteosarcoma (HOS), multiple bone lesions occur simultaneously or asynchronously before lung metastasis. HMOS is associated with an extremely poor prognosis, and effective treatment options are lacking. Using the proteins in our previously generated HMOS cell lines as antigens, we generated antibodies using a human antibody phage library. We obtained antibody clones recognizing 95 independent antigens and developed a fluorescence probe-based enzyme-linked immunosorbent assay (ELISA) technique capable of evaluating the reactivity of these antibodies by fluorescence intensity, allowing simple, rapid, and high-throughput selection of antibody clones. These results were highly correlated with those using flow cytometry. Subsequently, the HMOS cell lysate was incubated with the antibody, the antigen-antibody complex was recovered with magnetic beads, and the protein bands from electrophoresis were analyzed using liquid chromatography-mass spectrometry (LC/MS). CAVIN1/polymerase I transcript release factor was specifically detected in the HMOS cells. In conclusion, we found via a novel high-throughput screening method that CAVIN1/PTRF is an HMOS-specific cell membrane biomarker and an antigen capable of producing human antibodies. In the future, antibody-drug conjugate targeting of these specific proteins may be promising for clinical applications.

Filamin B Enhances the Invasiveness of Cancer Cells into 3D Collagen Matrices.

Numerous types of cancer cells migrate into extracellular tissues. This phenomenon is termed invasion, and is associated with poor prognosis in cancer patients. In this study, we demonstrated that filamin B (FLNb), an actin-binding protein, is highly expressed in cancer cell lines that exhibit high invasiveness, with a spindle morphology, into 3D collagen matrices. In addition, we determined that knockdown of FLNb in invasive cancer cells converts cell morphology from spindle-shaped, which is associated with high invasiveness, to round-shaped with low invasiveness. Furthermore, di-phosphorylation of myosin regulatory light chain (MRLC) and phosphorylation of focal adhesion kinase (FAK) are inhibited in FLNb-knockdown cancer cells. These results suggest that FLNb enhances invasion of cancer cells through phosphorylation of MRLC and FAK. Therefore, FLNb may be a new therapeutic target for invasive cancers.

Differentiation of adipose-derived stromal vascular fraction culture cells into chondrocytes using the method of cell sorting with a mesenchymal stem cell marker.

The incidence of arthritic diseases is rapidly increasing in most advanced countries. Articular cartilage, which is the most important tissue in the joint, consists of chondrocytes and abundant extracellular matrix, including aggrecan, and shows poor self-repair. We studied the potential of stem cells in mouse subcutaneous adipose tissue as a source of cells to regenerate cartilage tissue. Analysis of adipose-derived stromal vascular fraction culture cells (ADSVFs) using mesenchymal stem cell markers showed that CD90-positive cells accounted for 93.8%, CD105-positive cells for 68.5%, and p75 neurotrophin receptor (p75NTR, CD271)-positive cells for 36.1%. These results indicate that cells positive for mesenchymal stem cell markers are present in ADSVFs. The CD105-positive or -negative cells were isolated from ADSVFs by magnetic cell separation (MACS), and the efficiency of differentiation into chondrocytes was compared with using three methods of pellet method, gel-coating method, and gel-embedding sheet method. Using the CD105-positive cells and the gel-embedding sheet method, aggrecan mRNA was detected about three times higher than pellet and gel-coating methods. The above data suggest that ADSVFs could be differentiated into chondrocyte-like cells in the gel-embedding sheet method and could be useful in regenerative medicine to treat cartilage defects or cartilage degenerative disease. The use of cells sorted by mesenchymal stem cell markers from adipose tissue would gain position in the repair of cartilage tissue.

[Absolute risk for fracture and WHO guideline. Biological markers for osteoarthritis (OA)].

Biological markers for osteoarthritis (OA) are indicators of articular tissue metabolism, measuring the levels of molecules derived from joint structures into synovial fluids, serum and urine. Radiological findings are the basis of diagnosis of OA, but have a weakpoint visualizing the figures that have already occurred. For assessing disease activity or monitoring disease progression, estimation of articular metabolism using biological markers is very important. Synovial fluid reflects specifically the status of the punctured joint, however invasive. Less-invasive newly developed serum and urine markers appear to be also useful for the evaluation of OA.

Design of artificial nucleic acid chaperones for DNA engineering.

We have shown that the comb-type copolymer consisting of a polycation backbone and hydrophilic side chains stabilizes DNA hybrids. Furthermore, the copolymers showed the activity to accelerate DNA strand exchange reactions between double helical DNA and its complementary DNA. The copolymer was considered to stimulate breakage and reassociation of base pairing and act as an artificial nucleic acid chaperone. The polymer's chaperoning activity was elaborated for rapid and precise judging of a subtle difference in DNA sequences. One base alternation out of 20mer DNA was quickly detected by the strand exchange assay employing the copolymer. From these, we conclude that the copolymer would be a useful material in DNA engineering that employs rapid and precise DNA folding.

Acceleration of DNA strand exchange reaction by cationic polymers.

In previous reports, we have demonstrated that the cationic comb-type copolymers (PLL-g-Dex) having a poly-L-lysine main chain and dextran side chains stabilized DNA duplex and triplex. Furthermore, the copolymer was found to accelerate more than 20,000 folds strand exchange reaction between 20 bp duplex and its homologous single strand (1). This study was designed to inspect structural factor of polycationic moieties in acceleration effects. To this end, polypeptides containing lysine or arginine moieties as cationic groups were examined in their potency to accelerating strand exchange reaction. It was shown that arginine-rich peptide showed higher accelerating effect than lysine peptide when total positive charges of peptides were kept constant.