Immortalization and transformation of primary cells mediated by engineered ecDNAs.

Focal gene amplifications are among the most common cancer-associated mutations, but their evolution and contribution to tumorigenesis have proven challenging to recapitulate in primary cells and model organisms. Here we describe a general approach to engineer large (>1 Mbp) focal amplifications mediated by extrachromosomal circular DNAs (ecDNAs, also known as "double minutes") in a spatiotemporally controlled manner in cancer cell lines and in primary cells derived from genetically engineered mice. With this strategy, ecDNA formation can be coupled with expression of fluorescent reporters or other selectable markers to enable the identification and tracking of ecDNA-containing cells. We demonstrate the feasibility of this approach by engineering MDM2-containing ecDNAs in near-diploid human cells, showing that GFP expression can be used to track ecDNA dynamics under physiological conditions or in the presence of specific selective pressures. We also apply this approach to generate mice harboring inducible Myc - and Mdm2 -containing ecDNAs analogous to those spontaneously occurring in human cancers. We show that the engineered ecDNAs rapidly accumulate in primary cells derived from these animals, promoting proliferation, immortalization, and transformation.

Comparison of immediate and short-term outcomes of cricoarytenoid and thyroarytenoid lateralization in dogs with idiopathic laryngeal paralysis.

OBJECTIVE: To compare the immediate and short-term outcomes of thyroarytenoid lateralization (TAL) and cricoarytenoid lateralization (CAL) for the treatment of canine laryngeal paralysis in dogs. STUDY DESIGN: A prospective, clinical trial. ANIMALS: Fourteen client-owned dogs referred to our hospital because of bilateral laryngeal paralysis. METHODS: Dogs with confirmed laryngeal paralysis were randomly assigned to the CAL or TAL group. Video images of the rima glottidis obtained preoperatively, immediately postoperatively (t0), and 15 days postoperatively (t1) were digitized. The rima glottidis area was measured using image-analysis software. An increase in the rima glottidis area was expressed as a percentage of the preoperative area. RESULTS: The rima glottidis area increased by a mean of 152% at t0 and 127% at t1 for the TAL group and 205% at t0 and 199% at t1 for the CAL group compared with preoperative values. The increase in the rima glottidis area differed (P < .05) between the 2 groups at all postoperative time points. A reduction of the area occurred at t1 in both groups. There was no difference between t0 and t1 (P > .05) in the CAL group but there was a large difference (P < .05) in the TAL group. CONCLUSION: Cricoarytenoid lateralization and TAL were both effective for surgical abduction of the arytenoid cartilage. Although a reduction (P < .05) in the rima glottidis area occurred in the TAL group at t1, we observed no associated clinical signs. CLINICAL SIGNIFICANCE: Cricoarytenoid lateralization and TAL result in good short-term outcomes in dogs with laryngeal paralysis.

A unifying paradigm for transcriptional heterogeneity and squamous features in pancreatic ductal adenocarcinoma.

Pancreatic cancer expression profiles largely reflect a classical or basal-like phenotype. The extent to which these profiles vary within a patient is unknown. We integrated evolutionary analysis and expression profiling in multiregion-sampled metastatic pancreatic cancers, finding that squamous features are the histologic correlate of an RNA-seq-defined basal-like subtype. In patients with coexisting basal and squamous and classical and glandular morphology, phylogenetic studies revealed that squamous morphology represented a subclonal population in an otherwise classical and glandular tumor. Cancers with squamous features were significantly more likely to have clonal mutations in chromatin modifiers, intercellular heterogeneity for MYC amplification and entosis. These data provide a unifying paradigm for integrating basal-type expression profiles, squamous histology and somatic mutations in chromatin modifier genes in the context of clonal evolution of pancreatic cancer.

Lip-to-nose flap for reconstruction of the nasal planum after curative intent excision of squamous cell carcinoma in cats: Description of technique and outcome in seven cases.

OBJECTIVE: To describe the surgical technique for nasal planum reconstruction with a lip-to-nose flap after curative intent surgical excision of squamous cell carcinoma (SCC) in cats and to report the surgical outcomes. STUDY DESIGN: Short case series. ANIMALS: Seven cats with SCC of the lateral (n = 6) or dorsal (n = 1) aspect of the nasal planum. METHODS: After tumor excision, a mucocutaneous lip-to-nose flap was harvested from the upper lip and transposed to reconstruct the nasal planum. Variables recorded included surgical time, surgical complications, healing complications, flap success rate, and cosmetic and long-term functional outcomes. RESULTS: Median surgical time was 67.5 minutes (range 49-80), and no intraoperative complications occurred. Postoperatively, six cats developed self-limiting edema of the muzzle, and one cat had nasal discharge for 2 days. No major complications occurred during the healing process, and all cats went on to achieve successful healing of their flap. A small area of partial-thickness necrosis developed at the cranial edge of the flap in three cats and healed spontaneously in all cases within a few days. According to owner satisfaction and periodic clinical assessment, cosmetic and long-term functional of outcomes were considered good in all cats. CONCLUSION: The lip-to-nose flap allowed for aesthetic and functional reconstruction of the nasal planum after curative intent surgical excision of feline SCC. CLINICAL SIGNIFICANCE: The lip-to-nose flap is an option for a single-stage reconstruction of the nasal planum following partial nasal planectomy in cats.

Lip-to-nose flap for nasal plane reconstruction in dogs: A cadaveric and in vivo feasibility study.

OBJECTIVE: To describe a local interpolation flap based on the upper lip for the reconstruction of the dorsal aspect of the nasal plane in dogs. STUDY DESIGN: Ex vivo and in vivo case report. ANIMALS: A 2-year-old medium-sized spayed female mixed-breed dog and a canine cadaver of a medium-sized mixed-breed dog. METHODS: A dorsal defect of the nasal plane of uncertain origin in a dog was reconstructed with a unilateral interpolation flap obtained from the caudal upper lip skin and mucosa (lip-to-nose flap). The procedure was first performed in a cadaveric model to assess its feasibility. RESULTS: The lip-to-nose flap allowed the reconstruction of a dorsal nasal plane defect with a satisfactory cosmetic outcome. The incorporation of the labial mucosa guaranteed a complete and uncomplicated wound healing of the flap; a small area of necrosis occurred at the donor site, which resolved in a few days. CONCLUSION: The use of a lip-to-nose flap was feasible in these 2 medium-sized dogs and led to satisfactory cosmetic outcome. CLINICAL SIGNIFICANCE: A lip-to-nose flap may be considered to reconstruct dorsal nasal plane defects in dogs and allows for a cosmetic outcome.