Preclinical Evaluation of a Replication-Deficient Recombinant Adenovirus Serotype 5 Vaccine Expressing Guanylate Cyclase C and the PADRE T-helper Epitope.

There is an unmet need for improved therapeutics for colorectal cancer, the second leading cause of cancer mortality worldwide. Adjuvant chemotherapy only marginally improves survival in some patients and has no benefit in others, underscoring the clinical opportunity for novel immunotherapeutic approaches to improve survival in colorectal cancer. In that context, guanylate cyclase C (GUCY2C) is an established biomarker and therapeutic target for metastatic colorectal cancer with immunological characteristics that promote durable antitumor efficacy without autoimmunity. Preliminary studies established non-replicating human type 5 adenovirus (Ad5) expressing GUCY2C as safe and effective to induce GUCY2C-specific immune responses and antitumor immunity in mice. This study characterized the biodistribution, immunogenicity, and safety of a vector expressing GUCY2C fused with the human CD4+ T helper cell epitope PADRE (Ad5-GUCY2C-PADRE) to advance this vaccine into clinical trials in colorectal cancer patients. Ad5-GUCY2C-PADRE levels were highest in the injection site and distributed in vivo primarily to draining lymph nodes, the liver, spleen and, unexpectedly, to the bone marrow. Immune responses following Ad5-GUCY2C-PADRE administration were characterized by PADRE-specific CD4+ T-cell and GUCY2C-specific B-cell and CD8+ T-cell responses, producing antitumor immunity targeting GUCY2C-expressing colorectal cancer metastases in the lungs, without acute or chronic autoimmune or other toxicities. Collectively, these data support Ad5-GUCY2C-PADRE as a safe and effective vaccination strategy in preclinical models and position Ad5-GUCY2C-PADRE for Phase I clinical testing in colorectal cancer patients.

Anxiolytic activity of atrial natriuretic peptide in patients with panic disorder.

OBJECTIVE: Preclinical evidence exists for the anxiolytic activity of atrial natriuretic peptide, which is released during lactate-induced panic attacks. Atrial natriuretic peptide receptor modulation may have antipanic activity in patients with panic disorder. METHOD: The effects of 150 microg of atrial natriuretic peptide and placebo on panic attacks induced by cholecystokinin tetrapeptide (CCK-4) (25 microg) were studied in 10 panic disorder patients. The panicogenic activity of CCK-4 was measured with the Acute Panic Inventory. RESULTS: Panic attacks occurred in seven patients in the placebo condition and in two patients in the atrial natriuretic peptide condition. CCK-4 administration was accompanied by a significant increase in Acute Panic Inventory scores. Pretreatment with atrial natriuretic peptide resulted in significantly lower Acute Panic Inventory scores than pretreatment with placebo. CONCLUSIONS: The results support the antipanic activity of atrial natriuretic peptide. Nonpeptidergic atrial natriuretic peptide receptor ligands may be ultimately used to treat anxiety disorders.

Natriuretic peptide receptor-C attenuates hypertension in spontaneously hypertensive rats: role of nitroxidative stress and Gi proteins.

C-Atrial natriuretic peptide (ANP)4-23, a ring deleted analog of ANP that specifically interacts with natriuretic peptide receptor-C (NPR-C), has been shown to decrease the enhanced expression of Giα proteins implicated in the pathogenesis of hypertension. In the present study, we investigated whether in vivo treatment of spontaneously hypertensive rats (SHRs) with C-ANP4-23 could attenuate the development of high blood pressure (BP) and explored the underlying mechanisms responsible for this response. Intraperitoneal injection of C-ANP4-23 at the concentration of 2 or 10 nmol/kg body weight to prehypertensive SHRs attenuated the development of high BP, and at 8 weeks it was decreased by ≈20 and 50 mm Hg, respectively; however, this treatment did not affect BP in Wistar-Kyoto rats. C-ANP4-23 treatment of adult SHRs for 2 weeks also attenuated high BP, heart rate, and restored the impaired vasorelaxation toward control levels. In addition, the enhanced levels of superoxide anion (O2(-)), peroxynitrite, NADPH oxidase activity, and the enhanced expression of Giα proteins, NOX4, p47(phox), nitrotyrosine, and decreased levels of endothelial nitric oxide synthase (eNOS or NOS3) and NO in SHRs were attenuated by C-ANP4-23 treatment; however, the altered levels of NPR-A/NPR-C were not affected by this treatment. In conclusion, these results indicate that NPR-C activation by C-ANP4-23 attenuates the development of high BP in SHRs through the inhibition of enhanced levels of Giα proteins and nitroxidative stress and not through eNOS/cGMP pathway and suggest that NPR-C ligand may have the potential to be used as therapeutic agent in the treatment of cardiovascular complications including hypertension.

Urodilatin and four cardiac hormones decrease human renal carcinoma cell numbers.

BACKGROUND: Mortality from renal-cell cancer remains a significant problem with an estimated 12,600 deaths in the United States in 2005 even with current treatment(s) of surgery, chemotherapy, radiation and immunotherapy. Four cardiac natriuretic peptides, that is, atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide and kaliuretic peptide have significant anti-cancer effects in breast, pancreatic, prostate and colon adenocarcinomas. MATERIALS AND METHODS: These four peptide hormones plus brain natriuretic peptide (BNP), C-natriuretic peptide (CNP) and urodilatin, a peptide hormone formed in the kidney by a different post-translational processing of the atrial natriuretic peptide prohormone, were evaluated for their anti-cancer effects in renal carcinomas. RESULTS: Dose-response curves revealed a significant (P < 0.0001) decrease in human renal carcinoma cells with each 10-fold increase in concentration from 1 microm to 100 microm of five of these peptide hormones. There was an 81%, 74%, 66%, 70% and 70% elimination within 24 h in renal carcinoma cells secondary to vessel dilator, kaliuretic peptide, urodilatin, atrial natriuretic peptide and long-acting natriuretic peptide, respectively (P < 0.0001 for each), whereas BNP had no effect and CNP decreased renal cancer cell number by 10% (P = 0.04) at their 100 microm concentrations. Three days after treatment with these peptide hormones, the cancer cells began to proliferate again. The four cardiac hormones and urodilatin decreased DNA synthesis from 65-84% (P < 0.00001), whereas BNP and CNP decreased DNA synthesis 3% and 12% (both non-significant). Western blots revealed for the first time natriuretic peptide receptors (NPR)-A, -B and -C were present in the renal cancer cells. CONCLUSIONS: These results indicate that urodilatin and the four cardiac hormones have potent anti-cancer effects by eliminating up to 81% of renal carcinoma cells within 24 h of treatment.

Long-term treatment with a phosphodiesterase type 5 inhibitor improves pulmonary hypertension secondary to heart failure through enhancing the natriuretic peptides-cGMP pathway.

In advanced heart failure (HF), the compensatory pulmonary vasodilation is attenuated due to the relative insufficiency of cGMP despite increased secretion of natriuretic peptides (NPs). Phosphodiesterase type 5 (PDE5) inhibitors prevent cGMP degradation, and thus may potentiate the effect of the NPs-cGMP pathway. We orally administered a specific PDE5 inhibitor, T-1032 (1 mg/kg; twice a day, n = 7) or placebo (n = 7) for 2 weeks in dogs with HF induced by rapid pacing (270 bpm, 3 weeks) and examined the plasma levels of atrial natriuretic peptide (ANP), cGMP, and hemodynamic parameters. We also examined the hemodynamic changes after injection of a specific NPs receptor antagonist, HS-142-1 (3 mg/kg), under treatment with T-1032. T-1032 significantly increased plasma cGMP levels compared with the vehicle group despite low plasma ANP levels associated with improvement in cardiopulmonary hemodynamics. HS-142-1 significantly decreased plasma cGMP levels in both groups, whereas it did not change all hemodynamic parameters in the vehicle group. In contrast, in the T-1032 group, HS-142-1 significantly increased pulmonary arterial pressure and pulmonary vascular resistance. These results indicated that long-term treatment with a PDE5 inhibitor improved pulmonary hypertension secondary to HF and the NPs-cGMP pathway contributed to this therapeutic effect.