P11.12 Periostin is expressed by pericytes and is crucial for angiogenesis in glioma

BACKGROUND

The expression of the matricellular protein periostin has recently been associated with glioma progression and angiogenesis. The aim of the present study was to identify the cellular source of periostin expression in human gliomas and to study the role of periostin in an in vitro model for angiogenesis.

MATERIAL AND METHODS

The expression of periostin in various types and grades of brain tumors was investigated at the genetics level by RT-PCR and at the protein level by immunohistochemistry. In addition, the expression of periostin in glioma samples was studied by double labeling and in situ RNA techniques. Subsequently, by silencing periostin in a 3D in vitro angiogenesis model, its effects on angiogenesis were studied.

RESULTS

Periostin RNA and protein expression was found to be elevated in pilocytic astrocytoma and glioblastoma, but not in grade II/III astrocytomas. The expression of periostin co-localized with PDGFRβ + cells, but not with Olig2+ / Sox2+ glioma stem cells. Silencing of periostin in pericytes resulted in the attenuation of the number and the length of the vessels, and in decrease in the number of vessel junctions formed.

CONCLUSION

The results prove that pericytes are the main source of periostin in human gliomas. We demonstrate that periostin plays an essential role in the growth and branching of blood vessels. Therefore, periostin and / or its molecular interactions should be explored as a novel target for developing a new anti-angiogenic therapy for glioma.

The role of NPY in metabolic homeostasis: implications for obesity therapy

Neuropeptide Y (NPY) is a 36 amino acid amidated peptide which has now emerged as an important regulator of feeding behaviour. Upon intracerebroventricular (icv.) administration, NPY produces a pronounced feeding response in a variety of species. The actions of NPY are believed to be mediated by a family of receptor subtypes named Y1 - y6. Recent studies suggest that the Y1 and Y5 receptor subtypes are intimately involved in NPY induced feeding. This review presents preclinical data obtained with receptor subtype selective agonists and antagonists as well as findings from knockout mice. These new data suggest that NPY receptor antagonists may become an additional option for treating human obesity.

Hammerhead ribozymes that selectively cleave the NPY Y1, Y4, and Y5 receptor full-length RNA

The concept of exploiting the ribozyme catalytic center for cleaving a specific target RNA transcript was applied to the design of selective ribozymes for the rat Y1, Y4, and Y5 receptor subtypes. Ribozymes selective for the neuropeptide Y (NPY) receptor subtypes were designed and chemically modified. Recognition sites were selected both according to the extent of their sequence homology between the receptor subtypes and according to the localization within single-stranded regions accessible for hybridization. Stability of the ribozymes against nucleolytic activities was increased by introducing 2'-O-methylribonucleosides and 3'-terminal modifications, such as inverted ends or dideoxynucleosides. Ribozymes cleaving the full-length rat Y1, Y4 (1200 nt), and Y5 receptor mRNA (2200 nt) were identified. The specificity of the recognition sites and the subtype selectivity of the ribozyme-mediated cleavage was demonstrated.