Pilot study of jadomycin B pharmacokinetics and anti-tumoral effects in zebrafish larvae and mouse breast cancer xenograft models.

Despite numerous therapeutic options, multidrug resistance (MDR) remains an obstacle to successful breast cancer therapy. Jadomycin B, a natural product derived from Streptomyces venezuelae ISP5230, maintains cytotoxicity in MDR human breast cancer cells. Our objectives were to evaluate the pharmacokinetics, toxicity, anti-tumoral, and anti-metastatic effects of jadomycin B in zebrafish larvae and mice. In a zebrafish larval xenograft model, jadomycin B significantly reduced the proliferation of human MDA-MB-231 cells at or below its maximum tolerated dose (40 µm). In female Balb/C mice, a single intraperitoneal dose (6 mg/kg) was rapidly absorbed with a maximum serum concentration of 3.4 ± 0.27 µm. Jadomycin B concentrations declined biphasically with an elimination half-life of 1.7 ± 0.058 h. In the 4T1 mouse mammary carcinoma model, jadomycin B (12 mg/kg every 12 h from day 6 to 15 after tumor cell injection) decreased primary tumor volume compared to vehicle control. Jadomycin B-treated mice did not exhibit weight loss, nor significant increases in biomarkers of impaired hepatic (alanine aminotransferase) and renal (creatinine) function. In conclusion, jadomycin B demonstrated a good safety profile and provided partial anti-tumoral effects, warranting further dose-escalation safety and efficacy studies in MDR breast cancer models.

Esophageal Columnar Metaplasia in Childhood: A Population-Based Case Series Analysis.

BACKGROUND: Adults with Barrett's esophagus (BE) are often entered into surveillance for esophageal adenocarcinoma (EAC), although cancer risk is relatively low. BE can be detected in children (< 16 years). Little is known about the epidemiology of pediatric BE, and it is unclear what the optimal surveillance regimes are in children. AIM: To evaluate the demographic and clinical characteristics, and future neoplastic progression risk in all pediatric BE patients diagnosed in Northern Ireland between 1993 and 2010. METHODS: Data from the population-based Northern Ireland BE register were matched to the Northern Ireland Cancer Registry for EAC outcomes until end 2013. Age-adjusted incidence of pediatric BE was calculated, and characteristics between pediatric and adult BE patients compared using Chi-square tests. RESULTS: Over 18 years, 42 pediatric BE patients (< 16 years) were identified, equivalent to an age-adjusted incidence of < 2 per 100,000 children. There was a clear age differential, with BE incidence increasing with age within the pediatric population. The majority (85.7%) of patients were male, a significantly higher male/female ratio than adult BE patients (p < 0.001). No pediatric BE patients progressed to high-grade dysplasia (HGD) or EAC, although the eldest patient was aged 34 years by the end of follow-up. CONCLUSIONS: This is the largest series of pediatric BE ever reported. It demonstrates that pediatric BE is rare. The male preponderance of this condition is more apparent in childhood compared with adult cases. No children developed HGD/EAC during follow-up, suggesting that regular surveillance is not required, at least until adulthood.

Synthesis, Characterization and Photobiological Studies of Ru(II) Dyads Derived from α-Oligothiophene Derivatives of 1,10-Phenanthroline.

Three new bis(2,2'-bipyridine)-heteroleptic Ru(II) dyads incorporating thienyl groups (n = 1-3, compounds 1, 2 and 3, respectively) appended to 1,10-phenanthroline were synthesized and characterized to investigate the impact of n on the photophysical and photobiological properties within the series. All three complexes showed unstructured emission near 618 nm from a triplet metal-to-ligand charge transfer (3 MLCT) state with a lifetime (τem ) of approximately 1 µs. Transient absorption measurements revealed an additional excited state that was nonemissive and long-lived (τTA  = 43 µs for 2 and 27 µs for 3), assigned as a triplet intraligand (3 IL) state that was accessible only in 2 and 3. All three complexes were strong singlet oxygen (1 O2 ) sensitizers, with quantum yields (Φ∆ ) for 2 and 3 being the largest (74-78%), and all three were photocytotoxic to cancer cells with visible light activation in the order: 3 > 2 > 1. Cell-free DNA photodamage followed the same trend, where potency increased with decreasing 3 IL energy. Compounds 2 and 3 also showed in vitro photobiological effects with red light (625 nm), where their molar absorptivities were <100 m-1  cm-1 . These findings highlight that Ru(II) dyads derived from α-oligothiophenes directly appended to 1,10-phenanthroline-namely 2 and 3-possess low-lying 3 IL states that are highly photosensitizing, and they may therefore be of interest for photobiological applications such as photodynamic therapy (PDT).

Post Polyketide Synthase Carbon-Carbon Bond Formation in Type-II PKS-Derived Natural Products from Streptomyces venezuelae.

Polyketide synthase (PKS) derived natural products are biosynthesized by head-to-tail addition of acetate and malonate extender units resulting in linear extended-polyketide chains. Despite the well-documented structural diversity associated with PKS-derived natural products, C-C chain branching deviating from the usual linear pattern is relatively rare. Herein, type-II PKS angucyclic natural products containing a hemiaminal functionality were identified and proposed as the parent of a series of C-C-branched analogues. These C-C linked acetate or pyruvate branching units were located at the α-positions on the extended polyketide chains of jadomycins incorporating 3- and 4-aminomethylbenzoic acids. Labeling studies utilizing [1-13C]-d-glucose provided mechanistic evidence that the C-C bond formation occurred as a result of a previously unidentified post-PKS processing, additional to the enzymes encoded within the biosynthetic gene cluster. Selected compounds were evaluated in cytotoxic or antimicrobial assays.

Jadomycins Inhibit Type II Topoisomerases and Promote DNA Damage and Apoptosis in Multidrug-Resistant Triple-Negative Breast Cancer Cells.

Jadomycins are natural products that kill drug-sensitive and multidrug-resistant (MDR) breast cancer cells. To date, the cytotoxic activity of jadomycins has never been tested in MDR breast cancer cells that are also triple negative. Additionally, there is only a rudimentary understanding of how jadomycins cause cancer cell death, which includes the induction of intracellular reactive oxygen species (ROS). We first created a paclitaxel-resistant, triple-negative breast cancer cell line [paclitaxel-resistant MDA-MB-231 breast cancer cells (231-TXL)] from drug-sensitive control MDA-MB-231 cells (231-CON). Using thiazolyl blue methyltetrazolium bromide cell viability-measuring assays, jadomycins B, S, and F were found to be equipotent in drug-sensitive 231-CON and MDR 231-TXL cells; and using ROS-detecting assays, these jadomycins were determined to increase ROS activity in both cell lines by up to 7.3-fold. Jadomycins caused DNA double-strand breaks in 231-CON and 231-TXL cells as measured by γH2AX Western blotting. Coincubation with the antioxidant N-acetyl cysteine or pro-oxidant auranofin did not affect jadomycin-mediated DNA damage. Jadomycins induced apoptosis in 231-CON and 231-TXL cells as measured by annexin V affinity assays, a process that was retained when ROS were inhibited. This indicated that jadomycins are capable of inducing MDA-MB-231 apoptotic cell death independently of ROS activity. Using quantitative polymerase chain reaction, Western blotting, and direct topoisomerase inhibition assays, it was determined that jadomycins inhibit type II topoisomerases and that jadomycins B and F selectively poison topoisomerase IIß We therefore propose novel mechanisms through which jadomycins induce breast cancer cell death independently of ROS activity, through inhibition or poisoning of type II topoisomerases and the induction of DNA damage and apoptosis.

Heart-lung or lung transplantation for Eisenmenger syndrome.

BACKGROUND: The optimal therapy for end-stage Eisenmenger syndrome (ES) is unknown. We analyzed the United Network for Organ Sharing/International Society for Heart and Lung Transplantation Joint Thoracic Registry to determine predictors of survival. METHODS: Univariate analysis was performed using Kaplan-Meier survival curves. Groups were compared using the log-rank test. Multivariate analysis was performed using a proportional hazards model. RESULTS: There were 605 transplants performed between 1988 and 1998. The causes of ES included atrial septal defect (ASD) in 171, ventricular septal defect (VSD) in 164, multiple congenital anomalies (MCA) in 68 and patent ductus arteriosus (PDA) in 32. Procedures included 430 heart-lung (HLT), 106 bilateral lung, and 69 single lung transplants (LT). Survival after HLT was better than after LT on univariate analysis (p = 0.002). For HLT, survival at 30 days and 1 year was 80.7% and 70.1% compared with 68% and 55.2% for LT. Diagnosis was also a significant predictor of survival (p = 0.011), being best for VSD and MCA (1-year survival 71.4% and 77.6%). There was a highly significant benefit of HLT over LT for VSD patients (p = 0.0001). Diagnosis, the combination of diagnosis and procedure, recipient age, recipient gender, donor age, ischemic time and recipient status were significant in a multivariate model. Multivariate analysis confirmed the superior prognosis of patients with VSD or MCA (p = 0.007 and p = 0.022, respectively) and suggested that the adverse effect of LT was predominately in patients with VSD (risk ratio 1.817, p = 0.035). CONCLUSIONS: This analysis suggests that ES recipients are not a homogeneous group. Patients with VSD and MCA have the best prognosis. HLT appears to offer a survival benefit for patients with ES secondary to VSD and should be re-considered as the operation of choice.