Development of Targeted Therapy Therapeutics to Sensitize Triple-Negative Breast Cancer Chemosensitivity Utilizing Bacteriophage phi29 Derived Packaging RNA

Background: To date, triple-negative breast cancer (TNBC) treatment options are limited due to it lacks expression of receptors and are only available managed with chemotherapy. What's worse, TNBC is frequently developing resistance to chemotherapy. By using siRNA-based therapeutics, our recent work demonstrated X-box-binding protein 1 (XBP1) was linked to HER2+ breast cancer development and chemoresistance. As is well-known, the instability, off-target effects, net negative charge, and hydrophobicity of siRNA hamper its’ in vivo utilization and clinical transformation. Thus, the development of a siRNA delivery system (DDS) with ultra-stability and specificity is demanded to address the predicament of siRNA delivery.Results: Here, we assembled RNase resistant RNA nanoparticles (NPs) based on the 3WJ of Phi29 DNA packaging motor. To targeted therapy and sensitize TNBC to chemotherapy, the RNA NPs were equipped with epidermal growth factor receptor (EGFR) targeting aptamer and XBP1 siRNA. We found our RNA NPs could deplete XBP1 expression and suppress tumor growth after intravenous administration. Meanwhile, RNA NPs treatment could promote the sensitization of chemotherapy and impair angiogenesis in vivo. Conclusions: The results further demonstrate that our RNA NPs could serve as an effective and promising platform not only for siRNA delivery but also for chemotherapy-resistant TNBC therapy.

Genomic Analysis of the Recent Viral Isolate vB_BthP-Goe4 Reveals Increased Diversity of φ29-Like Phages

We present the recently isolated virus vB_BthP-Goe4 infecting Bacillus thuringiensis HD1. Morphological investigation via transmission electron microscopy revealed key characteristics of the genus Phi29virus, but with an elongated head resulting in larger virion particles of approximately 50 nm width and 120 nm height. Genome sequencing and analysis resulted in a linear phage chromosome of approximately 26 kb, harbouring 40 protein-encoding genes and a packaging RNA. Sequence comparison confirmed the relation to the Phi29virus genus and genomes of other related strains. A global average nucleotide identity analysis of all identified φ29-like viruses revealed the formation of several new groups previously not observed. The largest group includes Goe4 and may significantly expand the genus Phi29virus (Salasvirus) or the Picovirinae subfamily.

Complete Genome Sequence of vB_BveP-Goe6, a Virus Infecting Bacillus velezensis FZB42

ABSTRACT The new virus vB_BveP-Goe6 was isolated on the host organism Bacillus velezensis FZB42. The virus morphology indicated its association with the genus Phi29virus . The genome of vB_BveP-Goe6 (19,105 bp) comprises a linear chromosome with a GC content of 39.99%. The genome harbors 26 putative protein-coding genes and a noncoding packaging RNA.