Solid-phase synthesis, characterization and RNAi activity of branch and hyperbranch siRNAs

• Published in: Bioorganic & medicinal chemistry letters 2013-10, Vol.23 (19), p.5270-5274
• Main Authors: Maina, Anthony, Blackman, Brittany A., Parronchi, Christopher J., Morozko, Eva, Bender, Maria E., Blake, Allan D., Sabatino, David
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Branch siRNA; Cell death; Cell Survival - drug effects; cell viability; circular dichroism spectroscopy; denaturation; gene therapy; GRP78 silencing; Hep G2 Cells; high performance liquid chromatography; Humans; Hyperbranch siRNA; liver neoplasms; Microscopy, Confocal; Oncogene therapy; polyacrylamide gel electrophoresis; RNA Interference; RNA, Small Interfering - chemical synthesis; RNA, Small Interfering - genetics; RNA, Small Interfering - pharmacology; RNAi; small interfering RNA; Solid-Phase Synthesis Techniques
• ISSN: 0960-894X; 1464-3405
• DOI: 10.1016/j.bmcl.2013.08.033

Linear, branch and hyperbranch siRNAs were effectively prepared for down-regulating GRP78 expression and inducing cell death in HepG2 liver cancer cells. Branch and hyperbranch GRP78 siRNAs were synthesized by automated solid-phase synthesis in good yields (44–78%) and isolated in excellent purities (>99%) following HPLC purification. Moreover, siRNAs adopted stable intramolecular hybrids as discerned by native PAGE and thermal denaturation studies. These sequences also exhibited the pre-requisite A-type helical trajectory for triggering RNAi activity as determined by CD spectroscopy. Biological studies confirmed potent suppression of GRP78 expression (50–60%) while compromising cancer cell viability by ∼20%. Thus, branch and hyperbranch siRNAs may serve as potent siRNA candidates in cancer gene therapy applications.