Merging tumor targeting and molecular-genetic imaging into an integrated platform is limited by lack of strategies to enable systemic yet ligand-directed delivery and imaging of specific transgenes. Many eukaryotic viruses serve for transgene delivery but require elimination of native tropism for mammalian cells; in contrast, prokaryotic viruses can be adapted to bind to mammalian receptors but are otherwise poor vehicles. Here we introduce a system containing cis-elements from adeno-associated virus (AAV) and single-stranded bacteriophage. Our AAV/phage (AAVP) prototype targets an integrin. We show that AAVP provides superior tumor transduction over phage and that incorporation of inverted terminal repeats is associated with improved fate of the delivered transgene. Moreover, we show that the temporal dynamics and spatial heterogeneity of gene expression mediated by targeted AAVP can be monitored by positron emission tomography. This new class of targeted hybrid viral particles will enable a wide range of applications in biology and medicine.

Integrating vector systems used in clinical gene therapy have proven their therapeutic potential in the long-term correction of immunodeficiencies. The integration loci of such vectors in the cellular genome represent a molecular marker unique for each transduced cell and its clonal progeny. To gain insight into the physiology of gene-modified hematopoietic repopulation and vector-related influences on clonal contributions, we have previously introduced a technology--linear amplification-mediated (LAM) PCR--for detecting and sequencing unknown DNA flanking sequences down to the single cell level (Supplementary Note online). LAM-PCR analyses have enabled qualitative and quantitative measurements of the clonal kinetics of hematopoietic regeneration in gene transfer studies, and uncovered the clonal derivation of non-leukemogenic and leukemogenic insertional side effects in preclinical and clinical gene therapy studies. The reliability and robustness of this method results from the initial preamplification of the vector-genome junctions preceding nontarget DNA removal via magnetic selection. Subsequent steps are carried out on a semisolid streptavidin phase, including synthesis of double complementary strands, restriction digest, ligation of a linker cassette onto the genomic end of the fragment and exponential PCR(s) with vector- and linker cassette-specific primers. LAM-PCR can be adjusted to all unknown DNA sequences adjacent to a known DNA sequence. Here we describe the use of LAM-PCR analyses to identify 5' long terminal repeat (LTR) retroviral vector adjacent genomic sequences.

Aggressive and metastatic cancers show enhanced metabolic plasticity1, but the precise underlying mechanisms of this remain unclear. Here we show how two NOP2/Sun RNA methyltransferase 3 (NSUN3)-dependent RNA modifications—5-methylcytosine (m5C) and its derivative 5-formylcytosine (f5C) (refs.2–4)—drive the translation of mitochondrial mRNA to power metastasis. Translation of mitochondrially encoded subunits of the oxidative phosphorylation complex depends on the formation of m5C at position 34 in mitochondrial tRNAMet. m5C-deficient human oral cancer cells exhibit increased levels of glycolysis and changes in their mitochondrial function that do not affect cell viability or primary tumour growth in vivo; however, metabolic plasticity is severely impaired as mitochondrial m5C-deficient tumours do not metastasize efficiently. We discovered that CD36-dependent non-dividing, metastasis-initiating tumour cells require mitochondrial m5C to activate invasion and dissemination. Moreover, a mitochondria-driven gene signature in patients with head and neck cancer is predictive for metastasis and disease progression. Finally, we confirm that this metabolic switch that allows the metastasis of tumour cells can be pharmacologically targeted through the inhibition of mitochondrial mRNA translation in vivo. Together, our results reveal that site-specific mitochondrial RNA modifications could be therapeutic targets to combat metastasis.