Genomic Evolution after Chemoradiotherapy in Anal Squamous Cell Carcinoma.

Squamous cell carcinoma of the anal canal (ASCC) accounts for 2% to 4% of gastrointestinal malignancies in the United States and is increasing in incidence; however, genomic features of ASCC are incompletely characterized. Primary treatment of ASCC involves concurrent chemotherapy and radiation (CRT), but the mutational landscape of resistance to CRT is unknown. Here, we aim to compare mutational features of ASCC in the pre- and post-CRT setting.

Intraductal papillary mucinous neoplasm: clinical surveillance and management decisions.

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a relatively rare cystic neoplasm. Although most IPMNs appear to be benign and may be managed by surveillance, all IPMNs are considered premalignant lesions with malignant potential. As such, current efforts are focused on identifying those neoplasms that are at high risk for malignancy to optimize treatment strategy and outcome.

Triplex-forming peptide nucleic acids induce heritable elevations in gamma-globin expression in hematopoietic progenitor cells.

Potentiating homologous recombination using triplex-forming peptide nucleic acids (PNAs) can be used to mediate targeted sequence editing by donor DNAs and thereby induce functional gene expression to supplant non-functional counterparts. Mutations that disrupt the normal function of the β-globin subunit cause hemoglobinopathies such as sickle cell disease and β-thalassemias. However, expression of the functional γ-globin subunit in adults, a benign condition called hereditary persistence of fetal hemoglobin (HPFH), can ameliorate the severity of these disorders, but this expression is normally silenced.

Mitomycin in anal cancer: still the standard of care.

A 52-year-old woman presents with a 2-month history of bright red blood per rectum. Her bleeding is associated with bowel movements and a sense of incomplete evacuation. She denies fecal incontinence or change in stool caliber.

Nanoparticles deliver triplex-forming PNAs for site-specific genomic recombination in CD34+ human hematopoietic progenitors.

Triplex-forming peptide nucleic acids (PNAs) are powerful gene therapy agents that can enhance recombination of short donor DNAs with genomic DNA, leading to targeted and specific correction of disease-causing genetic mutations. Therapeutic use of PNAs is severely limited, however, by challenges in intracellular delivery, particularly in clinically relevant targets such as hematopoietic stem and progenitor cells. Here, we demonstrate efficient and nontoxic PNA-mediated recombination in human CD34(+) cells using poly(lactic-co-glycolic acid) (PLGA) nanoparticles for intracellular oligonucleotide delivery.

Targeted correction of a thalassemia-associated beta-globin mutation induced by pseudo-complementary peptide nucleic acids.

Beta-thalassemia is a genetic disorder caused by mutations in the beta-globin gene. Triplex-forming oligonucleotides and triplex-forming peptide nucleic acids (PNAs) have been shown to stimulate recombination in mammalian cells via site-specific binding and creation of altered helical structures that provoke DNA repair. However, the use of these molecules for gene targeting requires homopurine tracts to facilitate triple helix formation.

Repair of DNA lesions associated with triplex-forming oligonucleotides.

Triplex-forming oligonucleotides (TFOs) are gene targeting tools that can bind in the major groove of duplex DNA in a sequence-specific manner. When bound to DNA, TFOs can inhibit gene expression, can position DNA-reactive agents to specific locations in the genome, or can induce targeted mutagenesis and recombination. There is evidence that third strand binding, alone or with an associated cross-link, is recognized and metabolized by DNA repair factors, particularly the nucleotide excision repair pathway.

Correction of a splice-site mutation in the beta-globin gene stimulated by triplex-forming peptide nucleic acids.

Splice-site mutations in the beta-globin gene can lead to aberrant transcripts and decreased functional beta-globin, causing beta-thalassemia. Triplex-forming DNA oligonucleotides (TFOs) and peptide nucleic acids (PNAs) have been shown to stimulate recombination in reporter gene loci in mammalian cells via site-specific binding and creation of altered helical structures that provoke DNA repair. We have designed a series of triplex-forming PNAs that can specifically bind to sequences in the human beta-globin gene.

Triplex-mediated gene modification.

Gene targeting with DNA-binding molecules such as triplex-forming oligonucleotides or peptide nucleic acids can be utilized to direct mutagenesis or induce recombination site-specifically. In this chapter, several detailed protocols are described for the design and use of triplex-forming molecules to bind and mediate gene modification at specific chromosomal targets. Target site identification, binding molecule design, as well as various methods to test binding and assess gene modification are described.

Repair and recombination induced by triple helix DNA.

Triple-helix DNA structures can form endogenously at mirror repeat polypurine/polypyrimidine sequences or by introduction of triplex-forming oligonucleotides (TFOs). Recent evidence suggests that triple helices are sources of genetic instability, and are subject to increased rates of mutagenesis and recruitment of repair factors. Indeed, observations using TFOs suggest that triple helices provoke a variety of biological processes which can be harnessed to modulate gene expression and induce heritable changes in targeted genes.

Characterization of myelin ligand complexes with neuronal Nogo-66 receptor family members.

Nogo, MAG, and OMgp are myelin-associated proteins that bind to a neuronal Nogo-66 receptor (NgR/NgR1) to limit axonal regeneration after central nervous system injury. Within Nogo-A, two separate domains are known interact with NgR1. NgR1 is the founding member of the three-member NgR family, whereas Nogo-A (RTN4A) belongs to a four-member reticulon family.

Nogo-A interacts with the Nogo-66 receptor through multiple sites to create an isoform-selective subnanomolar agonist.

Nogo is a myelin-derived protein that limits axonal regeneration after CNS injury. A short hydrophilic Nogo-66 loop between two hydrophobic domains of Nogo binds to a Nogo-66 receptor (NgR) to inhibit axonal outgrowth. Inhibition of axon outgrowth and cell spreading by a second Nogo domain, termed Amino-Nogo-A, is thought to be mediated by a distinct receptor complex.