Combination Therapy of Brain Natriuretic Peptide and Sildenafil Attenuates Pulmonary Hypertension in Rats [abstract]

Abstract only availableFaculty Mentor: Dr. Vincent DeMarco, Child HealthBackground: Pulmonary arterial hypertension (PAH) is a lethal disease characterized by changes in pulmonary vascular structure and function. We tested the hypothesis that Sildenafil, a phosphodiesterase 5 inhibitor, and brain natriuretic peptide (BNP), a guanosine cyclase stimulator, in combination synergistically attenuates PAH when compared to individual therapy in rats through different mechanisms to increase cGMP while minimizing systemic side effects. Methods: Adult male Sprague-Dawley rats were subcutaneously injected with monocrotaline (n=30, 50 mg/kg). After approximately 5 weeks, rats were anesthetized and instrumented to measure systemic pressure (MAP) and right ventricular systolic pressure (RVSP) during infusions of vehicle solution (n=5), intravenous Sildenafil (84 mg/kg/min; n=8), and intravenous BNP (100 ng/kg/min; n=7) alone and a combination of Sildenafil and BNP (n=10). Results: Sildenafil alone decreased RVSP (-17 ±13.2 mmHg) and had a relatively minimal effect on MAP (-4±9.9 mmHg). BNP decreased RVSP (-19±14 mmHg) but also significantly effected MAP (-11±15.3mmHg). Combination therapy with Sildenafil and BNP lowered RVSP (-20±18.7 mmHg), however it also induced the greatest systemic hypotensive effect (MAP = -19±9.9 mmHg). Conclusion: The combination of Sildenafil and BNP, at these doses, significantly attenuates monocrotaline-induced pulmonary hypertension. However, compared with individual treatment, there is no significant difference in effect on RVSP. Furthermore, additive systemic side effects are too significant to consider combination therapy safe. With a different dosing regime, this combination is a potentially viable option in the treatment of patients with PAH

KRAS driven expression signature has prognostic power superior to mutation status in non-small cell lung cancer

KRAS is the most frequently mutated oncogene in non-small cell lung cancer (NSCLC). However, the prognostic role of KRAS mutation status in NSCLC still remains controversial. We hypothesize that the expression changes of genes affected by KRAS mutation status will have the most prominent effect and could be used as a prognostic signature in lung cancer. We divided NSCLC patients with mutation and RNA-seq data into KRAS mutated and wild type groups. Mann-Whitney test was used to identify genes showing altered expression between these cohorts. Mean expression of the top five genes was designated as a "transcriptomic fingerprint" of the mutation. We evaluated the effect of this signature on clinical outcome in 2,437 NSCLC patients using univariate and multivariate Cox regression analysis. Mutation of KRAS was most common in adenocarcinoma. Mutation status and KRAS expression were not correlated to prognosis. The transcriptomic fingerprint of KRAS include FOXRED2, KRAS, TOP1, PEX3 and ABL2. The KRAS signature had a high prognostic power. Similar results were achieved when using the second and third set of strongest genes. Moreover, all cutoff values delivered significant prognostic power (p < 0.01). The KRAS signature also remained significant (p < 0.01) in a multivariate analysis including age, gender, smoking history and tumor stage. We generated a "surrogate signature" of KRAS mutation status in NSCLC patients by computationally linking genotype and gene expression. We show that secondary effects of a mutation can have a higher prognostic relevance than the primary genetic alteration itself

Genetic diversity targets and indicators in the CBD post-2020 Global Biodiversity Framework must be improved

The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come. Previous article in issu

Role of the Abelson Tyrosine Kinases in Regulating Macrophage Functions in Immunity and Cancer

<p>The Abl family of protein tyrosine kinases regulates diverse cellular processes by coordinating cytoskeletal rearrangements. Recent data indicate that pharmacological inhibition of Abl kinases reduces inflammation in preclinical models and in the clinic. While a previous role for Abl kinases in lymphocytes had been described, it remained unclear if Abl kinases regulate innate immune function. To explore this possibility, we generated a myeloid-specific conditional Abl knockout mouse. Using a combination of molecular, genetic, and pharmacological approaches, we demonstrate a role for Abl kinases in regulating the efficiency of macrophage phagocytosis and inflammatory responses. Bone marrow-derived macrophages from mice lacking Abl and Arg kinases exhibit inefficient phagocytosis of sheep erythrocytes and zymosan particles. Treatment with the Abl kinase inhibitors imatinib and GNF-2 or overexpression of kinase-inactive forms of the Abl family kinases also impairs particle internalization in murine macrophages, indicating Abl kinase activity is required for efficient phagocytosis. Further, Abl kinases are present at the phagocytic cup and are activated by Fcgamma receptor engagement. The regulation of phagocytosis by Abl family kinases is mediated in part by the Syk kinase. Loss of Abl and Arg expression or treatment with Abl inhibitors reduced Syk phosphorylation in response to Fcgamma receptor ligation. The link between Abl family kinases and Syk may be direct as purified Arg kinase phosphorylates Syk in vitro. Further, overexpression of membrane-targeted Syk in cells treated with Abl kinase inhibitors partially rescues the impairment in phagocytosis.</p><p>Our studies also revealed a role for Abl kinases in macrophage and cancer cell invasion. Inhibition of Abl kinases suppressed cell invasion in vitro, whereas overexpression of Abl kinases enhanced extracellular matrix degradation. We found that partial loss of Abl kinase expression in myeloid cells reduced macrophage infiltration into tumors in a mouse model of breast cancer. Furthermore, pharmacological inhibition of Abl kinases reduced myeloid cell infiltration and slowed tumor growth in subcutaneous tumor models. We also found that Abl expression and activity are elevated in subsets of human tumor samples. Taken together, our results suggest Abl kinases have an important role in cancer and inflammation, and represent important therapeutic targets for their treatment.</p>Dissertatio