RACK1 is up-regulated in angiogenesis and human carcinomas

Angiogenesis is crucial for many biological and pathological processes incl uding the ovarian cycle and tumor growth, To identify molecules relevant fo r angiogenesis, we performed mRNA fingerprinting and subsequent Northern bl ot analysis using bovine cord-forming vs, monolayer-forming endothelial cel ls (EC) in vitro and staged bovine corpora lutea in vivo. We detected the r eceptor for activated C kinase 1 (RACK1), the specific receptor for activat ed protein kinase C beta (PKC beta), to be up-regulated in bovine cord-form ing EC in vitro and in angiogenically active stages of bovine corpora lutea in vivo, Thereafter we established and determined the complete bovine RACK 1 cDNA sequence. RACK1 was massively induced in subconfluent vs. contact-in hibited bovine EC, during angiogenesis in vitro, active phases of the murin e ovarian cycle, human tumor angiogenesis, and in cancer cells in vivo as a ssessed by quantitative PCR and in situ hybridization, RACK1 transcripts we re localized to proliferating EC in vitro and the endothelium of tumor neov ascularizations in vivo by in situ hybridization, PKC beta plays an importa nt role in angiogenesis and cancer growth. Our data suggest that downstream signaling of PKC beta in angiogenically active vs. inactive tissues and en dothelium is affected by the availability of RACK1.