Domain 5 of high molecular weight kininogen inhibits collagen-mediated cancer cell adhesion and invasion in association with α-actinin-4.

High molecular weight kininogen (HK) is a plasma glycoprotein with multiple functions, including the regulation of coagulation. We previously demonstrated that domain 5 (D5(H)), a functional domain of HK, and its derived peptides played an important role in the vitronectin-mediated suppression of cancer cell adhesion and invasion. However, the underlying mechanisms of the D5(H)-mediated suppressive effects remain to be elucidated. Here, we showed that D5(H) and its derivatives inhibited the collagen-mediated cell adhesion and invasion of human osteosarcoma MG63 cells. Using purified D5(H) fused to glutathione-S-transferase (GST) and D5(H)-derived peptides for column chromatography, an actin-binding protein, α-actinin-4, was identified as a binding protein of D5(H) with high-affinity for P-5m, a core octapeptide of D5(H). Immunofluorescence microscopy demonstrated that D5(H) co-localized with α-actinin-4 inside MG63 cells. In addition, exogenous GST-D5(H) added to the culture media was transported into MG63 cells, although GST alone as a control was not. As α-actinin-4 regulates actin polymerization necessary for cell adhesion and is related to the integrin-dependent attachment of cells to the extracellular matrix, our results suggest that D5(H) may modulate cell adhesion and invasion together with actinin-4.

Safe atlantoaxial fixation using a laminar screw (intralaminar screw) in a patient with unilateral occlusion of vertebral artery: case report.

STUDY DESIGN: A case of atlantoaxial fusion using an intralaminar (unilateral-crossing laminar screw) screw is presented in a patient with unilateral vertebral artery communication with the basilar artery. OBJECTIVES: To document the significance of the intralaminar screw technique in the aforementioned case. SUMMARY OF BACKGROUND DATA: Vertebral artery injury is directly linked with intraoperative or perioperative death if the vertebral artery communicates only unilaterally to the basilar artery or has an obvious dominant side. In this situation, irrespective of whether the pedicle is confirmed to be sufficient for pedicle screw placement, if the vertebral artery is violated, fatal complications will occur. The literature reports that even proficient surgeons cannot guarantee 100% accuracy in pedicle screw placement. The intralaminar screw technique is currently the safest with regard to avoiding violation of the vertebral artery. Biomechanical studies have also shown this technique to ensure sufficient strength. METHODS: The patient had rheumatoid atlantoaxial subluxation, and the right vertebral artery alone communicated with basilar artery, while the left ended blind. She underwent atlantoaxial fixation with an intralaminar screw (unilateral-crossing laminar screw) of the axis and lateral mass atlas screws inserted via the posterior arch. RESULTS: The intralaminar screw (unilateral-crossing laminar screw) was completed, and comprised lateral mass atlas screws and rods. There were no complications during and after surgery. Good bone union was achieved. CONCLUSION: Patients with unilateral dominant vertebral artery are good candidates for the intralaminar screw technique, even if the pedicle anatomy is sufficient to insert pedicle screws.