Novel therapeutic approach for cancer using four cardiovascular hormones

Heart failure pharmacotherapy and cancer: pathways and pre-clinical/clinical evidence

Heart failure (HF) patients have a significantly higher risk of new-onset cancer and cancer-associated mortality, compared to subjects free of HF. While both the prevention and treatment of new-onset HF in patients with cancer have been investigated extensively, less is known about the prevention and treatment of new-onset cancer in patients with HF, and whether and how guideline-directed medical therapy (GDMT) for HF should be modified when cancer is diagnosed in HF patients. The purpose of this review is to elaborate and discuss the effects of pillar HF pharmacotherapies, as well as digoxin and diuretics on cancer, and to identify areas for further research and novel therapeutic strategies. To this end, in this review, (i) proposed effects and mechanisms of action of guideline-directed HF drugs on cancer derived from pre-clinical data will be described, (ii) the evidence from both observational studies and randomized controlled trials on the effects of guideline-directed medical therapy on cancer incidence and cancer-related outcomes, as synthetized by meta-analyses will be reviewed, and (iii) considerations for future pre-clinical and clinical investigations will be provided.

Biosensors for natriuretic peptides in cardiovascular diseases. A review

Heart failure (HF) is a complex clinical syndrome associated with high rates of morbidity and mortality. Over the years, it has been crucial to find accurate biomarkers capable of doing a precise monitor of HF and provide an early diagnosis. Of these, it has been established an important role of natriuretic peptides in HF assessment. Moreover, the development of biosensors has been garnering interest as new diagnostic medical tools. In this review we first provide a general overview of HF, its pathogenesis, and diagnostic features. We then discuss the role of natriuretic peptides in heart failure by characterizing them and point out their potential as biomarkers. Finally, we adress the evolution of biosensors development and the available natriuretic peptides biosensors for disease monitoring.

Engineered hypoxia-responding Escherichia coli carrying cardiac peptide genes, suppresses tumor growth, angiogenesis and metastasis in vivo

Development of engineered non-pathogenic bacteria, capable of expressing anti-cancer proteins under tumor-specific conditions, is an ideal approach for selectively eradicating proliferating cancer cells. Herein, using an engineered hypoxia responding nirB promoter, we developed an engineered Escherichia coli BW25133 strain capable of expressing cardiac peptides and GFP signaling protein under hypoxic condition for spatiotemporal targeting of mice mammary tumors. Following determination of the in vitro cytotoxicity profile of the engineered bacteria, selective accumulation of bacteria in tumor microenvironment was studied 48 h after tail vein injection of 108 cfu bacteria in animals. For in vivo evaluation of antitumoral activities, mice with establishment mammary tumors received 3 consecutive intravenous injections of transformed bacteria with 4-day intervals and alterations in expression of tumor growth, invasion and angiogenesis specific biomarkers (Ki-67, VEGFR, CD31and MMP9 respectively), as well as fold changes in concentration of proinflammatory cytokines were examined at the end of the 24-day study period. Intravenously injected bacteria could selectively accumulate in tumor site and temporally express GFP and cardiac peptides in response to hypoxia, enhancing survival rate of tumor bearing mice, suppressing tumor growth rate and expression of MMP-9, VEGFR2, CD31 and Ki67 biomarkers. Applied engineered bacteria could also significantly reduce concentrations of IL-1β, IL-6, GC-SF, IL-12 and TNF-α proinflammatory cytokines while increasing those of IL-10, IL-17A and INF-γ. Overall, administration of hypoxia-responding E. coli bacteria, carrying cardiac peptide expression construct could effectively suppress tumor growth, angiogenesis, invasion and metastasis and enhance overall survival of mice bearing mammary tumors.

Drug repositioning in cancer: The current situation in Japan

Cancer is a leading cause of death worldwide, and the incidence continues to increase. Despite major research aimed at discovering and developing novel and effective anticancer drugs, oncology drug development is a lengthy and costly process, with high attrition rates. Drug repositioning (DR, also referred to as drug repurposing), the process of finding new uses for approved noncancer drugs, has been gaining popularity in the past decade. DR has become a powerful alternative strategy for discovering and developing novel anticancer drug candidates from the existing approved drug space. Indeed, the availability of several large established libraries of clinical drugs and rapid advances in disease biology, genomics/transcriptomics/proteomics and bioinformatics has accelerated the pace of activity‐based, literature‐based and in silico DR, thereby improving safety and reducing costs. However, DR still faces financial obstacles in clinical trials, which could limit its practical use in the clinic. Here, we provide a brief review of DR in cancer and discuss difficulties in the development of DR for clinical use. Furthermore, we introduce some promising DR candidates for anticancer therapy in Japan.

Recombinant production, purification and characterization of vessel dilator in E. coli

Vessel dilator is a 3.9-KDa potent anticancer peptide and a valuable candidate in the treatment of conditions such as congestive heart failure and acute renal failure amongst others. Here we report the recombinant production of vessel dilator in Escherichia coli. Three different synthetic ORF's dubbed VDI, VDII and VDIII, each encoding a trimmer of the vessel dilator peptide attached to a His tag sequence at their C- terminal, were synthesized and placed in pET21c expression vectors. The highest yield, following expression in E. coli BL21 (DE3), was recorded with VDII that carried the shortest fusion partner. Subsequent to the initial capture of the fusion protein by a Ni affinity column, the vessel dilator monomers were cleaved by trypsin treatment, and further purified to at least 90% homogeneity by anion exchange chromatography. De-novo sequencing and in vivo anticancer activity tests were used to verify the peptide sequence and its biological activity, respectively. The final yield was estimated to be approximately 15 mg of the purified vessel dilator per gram wet weight of the bacterial cells.

Immunocytochemical Localization of Atrial Natriuretic Peptide, Vessel Dilator, Long-acting Natriuretic Peptide, and Kaliuretic Peptide in Human Pancreatic Adenocarcinomas

We recently found that four peptide hormones synthesized by the same gene completely inhibit the growth of human pancreatic adenocarcinomas in athymic mice. The present immunocytochemical investigation was designed to determine where in the adenocarcinomas these peptide hormones localize. Atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide localized to the cytoplasm and nucleus of the human pancreatic adenocarcinomas, which is consistent with their ability to decrease DNA synthesis in the nucleus of this cancer. In this first investigation of where these peptide hormones with anticancer effects localize in any cancer, these peptide hormones also localized to the endothelium of capillaries and fibroblasts within these cancers. This is the first demonstration of growth-inhibiting peptide hormones localizing to the nucleus, where they inhibit DNA synthesis and may interact with growth-promoting hormones that localize there as the etiology of their ability to inhibit the growth of adenocarcinomas both in vitro and in vivo.

Atrial natriuretic peptide: a magic bullet for cancer therapy targeting Wnt signaling and cellular pH regulators

Atrial natriuretic peptide (ANP) is a cardiac hormone playing a crucial role in cardiovascular homeostasis mainly through blood volume and pressure regulation. In the last years, the new property ascribed to ANP of inhibiting tumor growth both in vitro and in vivo has made this peptide an attractive candidate for anticancer therapy. The molecular mechanism underlying the anti-proliferative effect of ANP has been mainly related to its interaction with the specific receptors NPRs, through which this natriuretic hormone inhibits some metabolic targets critical for cancer development, including the Ras-MEK1⁄2-ERK1⁄2 kinase cascade, functioning as a multikinase inhibitor. In this review we summarize the current knowledge on this topic, focusing on our recent data demonstrating that the antitumor activity of this natriuretic hormone is also mediated by a concomitant effect on the Wnt/β-catenin pathway and on the pH regulation ability of cancer cells, through a Frizzled-related mechanism. This peculiarity of simultaneously targeting two processes crucial for neoplastic transformation and solid tumor survival reinforces the utility of ANP for the development of both preventive and therapeutic strategies.

Atrial natriuretic peptide (ANP) inhibits DMBA/croton oil induced skin tumor growth by modulating NF-κB, MMPs, and infiltrating mast cells in swiss albino mice

Cardiac hormone atrial natriuretic peptide (ANP) and its receptor, natriuretic peptide receptor-A (NPR-A) are implicated as a vital regulator of cancer cell growth and tumor progression. However, the underlying mechanism by which ANP opposes the cancer growth in in-vivo remains unknown. Herein, we investigated the anti-cancer activity of ANP on 7, 12-dimethyl benzanthracence (DMBA)/Croton oil- induced two-step skin carcinogenic mouse model. Skin tumor incidence and tumor volume were recorded during the experimental period of 16 weeks. ANP (1 μg/kg body weight/alternate days for 4 weeks) was injected subcutaneously from the 13th week of DMBA/Croton oil induction. ANP treatment markedly inhibited the skin tumor growth (P<0.001). A significant reduction in the level of NF-κB activation (P<0.001), infiltrating mast cell count (P<0.01) and MMP-2/-9 (P<0.001, respectively) were noticed in the ANP treated mice skin tissue. Further, ANP treatment revert back the altered levels of serum LDH-4, C-reactive protein (CRP), and enzymatic antioxidants (SOD and CAT activities) to near normal level. Taken together, the results of this study suggest that ANP opposes the skin carcinogenesis by suppressing the inflammatory response and MMPs.

Cardiac hormones for the treatment of cancer

Four cardiac hormones, namely atrial natriuretic peptide, vessel dilator, kaliuretic peptide, and long-acting natriuretic peptide, reduce up to 97% of all cancer cells in vitro. These four cardiac hormones eliminate up to 86% of human small-cell lung carcinomas, two-thirds of human breast cancers, and up to 80% of human pancreatic adenocarcinomas growing in athymic mice. Their anticancer mechanisms of action, after binding to specific receptors on cancer cells, include targeting the rat sarcoma-bound GTP (RAS) (95% inhibition)-mitogen-activated protein kinase kinase 1/2 (MEK 1/2) (98% inhibition)-extracellular signal-related kinase 1/2 (ERK 1/2) (96% inhibition) cascade in cancer cells. They also inhibit MAPK9, i.e. c-Jun N-terminal kinase 2. They are dual inhibitors of vascular endothelial growth factor (VEGF) and its VEGFR2 receptor (up to 89%). One of the downstream targets of VEGF is β-catenin, which they reduce up to 88%. The WNT pathway is inhibited up to 68% and secreted frizzled-related protein 3 decreased up to 84% by the four cardiac hormones. AKT, a serine/threonine protein kinase, is reduced up to 64% by the cardiac hormones. STAT3, a final 'switch' that activates gene expression that leads to malignancy, is decreased by up to 88% by the cardiac hormones. STAT3 is specifically decreased as they do not affect STAT1. There is a cross-talk between the RAS-MEK 1/2-ERK 1/2 kinase cascade, VEGF, β-catenin, WNT, JNK, and STAT pathways and each of these pathways is inhibited by the cardiac hormones.

Association between brain natriuretic peptide and distant metastases in advanced non-small cell lung cancer patients

This study aimed to investigate the relationship between clinicopathological factors and plasma brain natriuretic peptide (BNP) levels in non-small cell lung cancer (NSCLC) patients. A total of 133 patients with advanced NSCLC were included in this study. The level of BNP was determined at the time of diagnosis. The BNP plasma concentration was measured using a chemiluminescent enzyme immunoassay kit. The univariate relationship between each independent clinicopathological variable and plasma BNP was examined using the Chi-square test. The survival curves were determined using the Kaplan-Meier method. According to the cut-off value of plasma BNP levels (11.5 and 22.4 pg/ml), plasma BNP negatively correlated with the presence of metastases (Chi-square test, p=0.0374 and p=0.0098, respectively). However, no significant association between patient survival time and plasma BNP levels was found. Reduced plasma BNP levels in advanced NSCLC patients with metastases were noted and the possibility was raised that BNP decreases distant metastases of advanced NSCLC patients.

Regulation and therapeutic targeting of peptide-activated receptor guanylyl cyclases

Cyclic GMP is a ubiquitous second messenger that regulates a wide array of physiologic processes such as blood pressure, long bone growth, intestinal fluid secretion, phototransduction and lipolysis. Soluble and single-membrane-spanning enzymes called guanylyl cyclases (GC) synthesize cGMP. In humans, the latter group consists of GC-A, GC-B, GC-C, GC-E and GC-F, which are also known as NPR-A, NPR-B, StaR, Ret1-GC and Ret2-GC, respectively. Membrane GCs are activated by peptide ligands such as atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP), guanylin, uroguanylin, heat stable enterotoxin and GC-activating proteins. Nesiritide and carperitide are clinically approved peptide-based drugs that activate GC-A. CD-NP is an experimental heart failure drug that primarily activates GC-B but also activates GC-A at high concentrations and is resistant to degradation. Inactivating mutations in GC-B cause acromesomelic dysplasia type Maroteaux dwarfism and chromosomal mutations that increase CNP concentrations are associated with Marfanoid-like skeletal overgrowth. Pump-based CNP infusions increase skeletal growth in a mouse model of the most common type of human dwarfism, which supports CNP/GC-B-based therapies for short stature diseases. Linaclotide is a peptide activator of GC-C that stimulates intestinal motility and is in late-stage clinical trials for the treatment of chronic constipation. This review discusses the discovery of cGMP, guanylyl cyclases, the general characteristics and therapeutic applications of GC-A, GC-B and GC-C, and emphasizes the regulation of transmembrane guanylyl cyclases by phosphorylation and ATP.

Comparative evaluation of three 64Cu-labeled E. coli heat-stable enterotoxin analogues for PET imaging of colorectal cancer

Analogues of the E. coli heat-stable enterotoxin (STh) are currently under study as both imaging and therapeutic agents for colorectal cancer. Studies have shown that the guanylate cyclase C (GC-C) receptor is commonly expressed in colorectal cancers. It has also been shown that STh peptides inhibit the growth of tumor cells expressing GC-C. The ability to determine GC-C status of tumor tissue using in vivo molecular imaging techniques would provide a useful tool for the optimization of GC-C-targeted therapeutics. In this work, we have compared receptor binding affinities, internalization/efflux rates, and in vivo biodistribution patterns of an STh analogue linked to N-terminal DOTA, TETA, and NOTA chelating moieties and radiolabeled with Cu-64. The peptide F(19)-STh(2-19) was N-terminally labeled with three different chelating groups via NHS ester activation and characterized by RP-HPLC, ESI-MS, and GC-C receptor binding assays. The purified conjugates were radiolabeled with Cu-64 and used for in vitro internalization/efflux, in vivo biodistribution, and in vivo PET imaging studies. In vivo experiments were carried out using SCID mice bearing T84 human colorectal cancer tumor xenografts. Incorporation of DOTA-, TETA-, and NOTA-chelators at the N-terminus of the peptide F(19)-STh(2-19) resulted in IC(50)s between 1.2 and 3.2 nM. In vivo, tumor localization was similar for all three compounds, with 1.2-1.3%ID/g at 1 h pi and 0.58-0.83%ID/g at 4 h pi. The principal difference between the three compounds related to uptake in nontarget tissues, principally kidney and liver. At 1 h pi, (64)Cu-NOTA-F(19)-STh(2-19) demonstrated significantly (p < 0.05) lower uptake in liver than (64)Cu-DOTA-F(19)-STh(2-19) (0.36 +/- 0.13 vs 1.21 +/- 0.65%ID/g) and significantly (p < 0.05) lower uptake in kidney than (64)Cu-TETA-F(19)-STh(2-19) (3.67 +/- 1.60 vs 11.36 +/- 2.85%ID/g). Use of the NOTA chelator for coordination of Cu-64 in the context of E. coli heat-stable enterotoxin analogues results in higher tumor/nontarget tissue ratios at 1 h pi than either DOTA or TETA macrocycles. Heat-stable enterotoxin-based radiopharmaceuticals such as these provide a means of noninvasively determining GC-C receptor status in colorectal cancers by PET.

Four cardiac hormones cause cell death of melanoma cells and inhibit their DNA synthesis

BACKGROUND

There will be an estimated 59,940 new cases of melanoma and 8,110 deaths from melanoma in the United States in 2007. There has been no improvement in survival with melanomas in the last 22 years, with current treatment indicating that new treatment(s) of melanoma are drastically needed. Four cardiac hormones ie, atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide, have significant anticancer effects in adenocarcinomas.

METHODS

Dose-response curves evaluated the effects of these cardiovascular hormones on cell death and DNA synthesis in several melanoma cell lines in culture for 96 hours. Receptors to mediate these peptide hormones effects were examined in the melanoma cells with Western blots. Their intracellular mediator-analog 8-bromo-cyclic GMP was used to determine if it could mimic their effects on decreasing melanoma cell number and DNA synthesis.

RESULTS

The four cardiac hormones caused cell death in up to 71% (P < 0.001) of the melanoma cells within 24 hours. Cardiac hormone receptors (NPR-A, -B, -C) were present on the melanoma cells, and each of the peptide hormones decreased DNA synthesis within the melanoma cells up to 73% (P < 0.001) at their 1-microM concentrations. 8-Bromo-cyclic GMP mimicked their effects, decreasing the number of melanoma cells up to 67% and their DNA synthesis by 58% (both at P < 0.01).

CONCLUSIONS

These results indicate that 4 cardiac hormones have potent beneficial effects by increasing cell death in up to 71% of melanoma cells within 24 hours mediated in part by a 73% decrease in their DNA synthesis.

Four peptides decrease human colon adenocarcinoma cell number and DNA synthesis via cyclic GMP

BACKGROUND

Mortality from colon cancer is significant with an expected 30,350 colon cancer deaths in 2005 with current treatment(s). Long-acting natriuretic peptide, vessel dilator, kaliuretic peptide, and atrial natriuretic peptide have significant anticancer effects in breast and pancreatic adenocarcinomas.

AIM OF STUDY

Whether these peptide hormones have anticancer effects in colon adenocarcinoma cells and whether these effects are specifically mediated by cyclic GMP has not been determined.

METHODS

These peptide hormones were evaluated for anticancer effects in human colon adenocarcinoma cells and to determine whether their anticancer effects are specifically mediated by cyclic GMP.

RESULTS

There was a 89-97% decrease (p <0.001 for each) in colon adenocarcinoma cells within 24 h with 1 mM of these peptide hormones. There was a significant (p <0.05) decrease in human colon cancer cell number with each 10-fold increase in concentration from 1 to 1,000 microM (i.e., 1 mM) of these four peptide hormones without any proliferation in the 3 d following this decrease. These same hormones decreased DNA synthesis 65-83% (p <0.001). Cyclic GMP antibody inhibited 75- 80% of these peptides' ability to decrease colon adenocarcinoma cell number and inhibited 92-96% of their DNA synthesis effects and 97% of cyclic GMP's effects. Western blots revealed that for the first time natriuretic peptide receptors (NPR) A and C were present in colon adenocarcinoma cells.

CONCLUSIONS

Four peptide hormones eliminate up to 97% of colon cancer cells within 24 h with their DNA effects specifically mediated by cyclic GMP.

Four cardiac hormones eliminate 4-fold more human glioblastoma cells than the green mamba snake peptide

Within 24h four cardiac hormones, i.e., vessel dilator, kaliuretic peptide, atrial natriuretic peptide, and long acting natriuretic peptide decrease the number of human glioblastoma cells 75%, 68%, 67%, and 65% while Dendroaspis (green mamba) peptide caused a 17% decrease when each were utilized at 100 microM. The four cardiac hormones decreased DNA synthesis 65-87% and increased cyclic GMP 1.3- to 3.8-fold in the glioblastoma cells. Natriuretic peptide receptors (NPR)-A and -C were present.

CONCLUSION

four cardiac hormones eliminate up to 75% of glioblastoma cells via cyclic GMP-mediated up to 87% decrease in DNA synthesis.

Four cardiac hormones eliminate up to 82% of human medullary thyroid carcinoma cells within 24 hours

Four cardiac hormones, i.e., atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide, which have anticancer effects, were evaluated for the first time on any endocrine cancer to determine if they have anticancer effects in an endocrine cancer. These four cardiac hormones were evaluated for their anticancer, DNA synthesis, and receptor status in human medullary thyroid cancer cells. There was a significant (p < 0.001) decrease in human medullary thyroid cancer cells with each 10-fold increase from 1 to 100 microM of the four cardiac hormones. There was an 81%, 68%, 71%, and 66% elimination within 24 h of medullary thyroid cancer cells secondary to vessel dilator, kaliuretic peptide, atrial natriuretic peptide, and long-acting natriuretic peptide, respectively (p < 0.0001). Three days after treatment with these peptide hormones, there was no proliferation of the medullary thyroid cancer cells. These cardiac hormones decreased DNA synthesis in the medullary thyroid cells from 65% to 84% (p < 0.0001). Western blots revealed natriuretic peptide receptors-A and -C were present in human medullary thyroid cancer cells. These results indicate the four cardiac hormones have potent anticancer effects by eliminating up to 82% of human medullary thyroid carcinoma cells within 24 h of treatment.

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.

Localization of ANP-synthesizing cells in rat stomach

AIM: To study the morphological positive expression of antrial natriuretic peptide (ANP)-synthesizing cells and ultrastructural localization and the relationship between ANP-synthesizing cells and microvessel density in the stomach of rats and to analyze the distribution of the three histologically distinct regions of ANP-synthesizing cells.

METHODS: Using immunohistochemical techniques, we studied positive expression of ANP-synthesizing cells in rat stomach. A postembedding immunogold microscopy technique was used for ultrastructural localization of ANP-synthesizing cells. Microvessel density in the rat stomach was estimated using tannic acid-ferric chloride (TAFC) method staining. Distribution of ANP-synthesizing cells were studied in different regions of rat stomach histochemically.

RESULTS: Positive expression of ANP-synthesizing cells were localized in the gastric mucosa of rats. Localization of ANP-synthesizing cells identified them to be enterochrochromaffin cells (EC) by using a postembedding immunogold electron microscopy technique. EC cells were in the basal third of the cardiac mucosa region. ANP-synthesizing cells existed in different regions of rat stomach and its density was largest in the gastric cardiac region, and the distribution order of ANP-synthesizing cells in density was cardiac region, pyloric region and fundic region in mucosa layer. We have also found a close relationship between ANP-synthesizing cells and microvessel density in gastric mucosa of rats using TAFC staining.

CONCLUSION: ANP-synthesizing cells are expressed in the gastric mucosa. EC synthesize ANP. There is a close relationship between ANP-synthesizing cells and microvessel density in gastric mucosa of rats.The distribution density of ANP-synthesizing cells is largest in the gastric cardiac region.

Primary Malignant Tumors of the Heart: Four Cardiovascular Hormones Decrease the Number and DNA Synthesis of Human Angiosarcoma Cells

BACKGROUND

A family of six cardiovascular hormones--atrial natriuretic peptide, brain natriuretic peptide, C-natriuretic peptide, long acting natriuretic peptide, vessel dilator and kaliuretic peptide--was investigated for the ability to decrease the number of human angiosarcoma cells.

METHODS AND RESULTS

Within 24 h, vessel dilator, long acting natriuretic peptide, kaliuretic peptide, atrial natriuretic peptide and their intracellular mediator cyclic GMP decreased the number of angiosarcoma cells by 61, 30, 29, 36 and 32%, respectively, and DNA synthesis by 68-85%. Brain natriuretic peptide and C-natriuretic peptide had no effect(s). The natriuretic peptide receptor C was present.

CONCLUSIONS

Four cardiovascular hormones decrease the number of angiosarcoma cells within 24 h via inhibition of DNA synthesis mediated in part by cyclic GMP.

Which of the cardiac natriuretic peptides is most effective for the treatment of congestive heart failure, renal failure and cancer?

Cardiac natriuretic peptides consist of a family of six peptide hormones that are synthesised by three separate genes and then stored as three separate prohormones (i.e. 126 amino acid atrial natriuretic peptide (ANP), 108 amino acid B-type natriuretic peptide (BNP) and 103 amino acid C-type natriuretic peptide (CNP) prohormones). The ANP prohormone contains four peptide hormones: long-acting natriuretic peptide (LANP), vessel dilator, kaliuretic peptide and ANP. 2. Currently, the only natriuretic peptide available commercially to treat congestive heart failure (CHF) is BNP (Nesiritide/Natrecor; SCIOS, Sunnyvale, CA, USA), which causes a small increase in the urine volume of 90 38 mL/h compared with 67 27 mL/h and no significant natriuresis, but has beneficial haemodynamic effects in acute CHF individuals. These haemodynamic effects probably contribute to the side-effects of BNP in patients with acute CHF with a 27% incidence of hypotension and possibly to 22% worsening of renal function, defined as an increase in serum creatinine of 0.5 mg/dL, associated with a worse prognosis. A review of clinical trials suggests a twofold increased risk of death at 30 days post-nesiritide treatment, a finding that needs further investigation. 3. The best of the natriuretic peptides for treating chronic CHF is the vessel dilator, which increases urinary flow up to 13-fold and sodium excretion up to fourfold, without the previously mentioned side-effects. The natriuretic and diuretic effects of vessel dilators last 6 h, which would allow them to be used on a four times per day basis in treating chronic CHF. 4. Atrial natriuretic peptide does not cause significant improvement in acute renal failure (ARF) in humans. The only natriuretic peptide that significantly improves ARF is the vessel dilator. Even when ARF has been established for 2 days before treatment in an ischaemic ARF animal model, vessel dilator decreases serum creatinine from 8.2 0.5 to 0.98 0.12 mg/dL in 6 days. At day 6 of ARF, mortality decreases to 14% (from 88%) without the vessel dilator. After 6 days of treatment with the vessel dilator, the proximal and distal tubules regenerate. 5. In cancer, vessel dilator, LANP, kaliuretic peptide and ANP at 1 mmol/L, decrease up to 97% of human breast, pancreatic and prostate adenocarcinoma cells, as well as small cell and squamous cell lung cancer cells within 24 h. In vivo, vessel dilator, LANP and kaliuretic peptide completely stop the growth of human pancreatic adenocarcinomas in athymic mice and decrease their tumour volume by 49, 28 and 11%, respectively in 1 week.

Vessel dilator: most potent of the atrial natriuretic peptides in decreasing the number and DNA synthesis of human squamous lung cancer cells

Within 24 h four peptide hormones, i.e. vessel dilator, long acting natriuretic peptide, kaliuretic peptide, and atrial natriuretic peptide and their intracellular mediator cyclic GMP decreased the number of human squamous lung cancer cells 51, 22, 25, 21, and 30%, respectively. There was not any proliferation in the 3 days following this decrease in cell number. Vessel dilator decreased DNA synthesis 85% in the squamous lung cancer cells. Thus, vessel dilator significantly decreased the number of human squamous lung cancer cells and their DNA synthesis, mediated in part by cyclic GMP, more than other peptide hormones.

Atrial natriuretic peptides: anticancer agents

Atrial natriuretic peptides (ANPs) consist of a family of six peptide hormones that are synthesized by three different genes and then stored as three different prohormones. Within the 126-amino acid ANP prohormone are four peptide hormones: long-acting natriuretic peptide (LANP), vessel dilator, kaliuretic peptide, and ANP, whose main known biologic properties are blood pressure regulation and maintenance of plasma volume. The newest discovered property of these peptide hormones is their anticancer effects. Vessel dilator, LANP, kaliuretic peptide, and ANP decrease the number of human pancreatic adenocarcinoma cells in culture by 65%, 47%, 37%, and 34%, respectively, within 24 hours at their 1 microM concentrations. Similar results have been found with breast adenocarcinomas, squamous cell lung cancer, and small cell lung cancer cells, each associated with an 83% or greater inhibition of deoxyribonucleic acid (DNA) synthesis by these four peptide hormones. Brain natriuretic peptide has no effects even when increased 100-fold (ie, 100 microM). C-type natriuretic peptide has no effects when increased 10-fold, but when increased 100-fold, it decreases 39% of the cancer cells. At this higher 100 microM concentration, vessel dilator kills 92% of the cancer cells within 24 hours. The four peptide hormones synthesized by the ANP gene given subcutaneously via osmotic pumps in athymic mice with human pancreatic adenocarcinomas completely stop the growth of these adenocarcinomas at 1 week. Vessel dilator, LANP, and kaliuretic peptide within 1 week decrease the volume by 49%, 28%, and 11% of the human pancreatic adenocarcinomas, which, with current anticancer treatment, have a mean survival of only 4 months.

PNC-28, a p53-derived peptide that is cytotoxic to cancer cells, blocks pancreatic cancer cell growthin vivo

PNC-28 is a p53 peptide from its mdm-2-binding domain (residues 17-26), which contains the penetratin sequence enabling cell penetration on its carboxyl terminal end. We have found that this peptide induces necrosis, but not apoptosis, of a variety of human tumor cell lines, including several with homozygous deletion of p53, and a ras-transformed rat acinar pancreatic carcinoma cell line, BMRPA1. Tuc3. On the other hand, PNC-28 has no effect on untransformed cells, such as rat pancreatic acinar cells, BMRPA1, and human breast epithelial cells and no effect on the differentiation of human stem cells. In this study, we now test PNC-28 in vivo for its ability to block the growth of BMRPA1. Tuc3 cells. When administered over a 2-week period in the peritoneal cavities of nude mice containing simultaneously transplanted tumors, PNC-28 causes complete destruction of these tumors. When delivered concurrently with tumor explantation at a remote site, PNC-28 causes a complete blockade of any tumor growth during its 2-week period of administration and 2 weeks posttreatment, followed by weak tumor growth that plateaus at low tumor sizes compared with tumor growth in the presence of a control peptide. When administered after tumor growth has occurred at a site remote from the tumor, PNC-28 causes a decrease in tumor size followed by a slow increase in tumor growth that is significantly slower than growth in the presence of control peptide. These results suggest that PNC-28 may be effective in treating cancers especially if delivered directly to the tumor.

The presence of ANP in rat peritoneal mast cells

Atrial natriuretic peptide (ANP) is an important component of the natriuretic peptide system. A great role in many regulatory systems is played by mast cells. Meanwhile involvement of these cells in ANP activity is poorly studied. In this work, we have shown the presence of ANP in rat peritoneal mast cells. Pure fraction of mast cells was obtained by separation of rat peritoneal cells on a Percoll density gradient. By Western blotting, two ANP-immunoreactive proteins of molecular masses of 2.5 kDa and 16.9 kDa were detected in lysates from these mast cells. Electron microscope immunogold labeling has revealed the presence of ANP-immunoreactive material in storage, secreting and released granules of mast cells. Our findings indicate the rat peritoneal mast cells to contain both ANP prohormone and ANP. These both peptides are located in mast cell secretory granules and released by mechanism of degranulation. It is discussed that many mast cell functions might be due to production of natriuretic peptides by these cells.

Four peptide hormones' specific decrease (up to 97%) of human prostate carcinoma cells

BACKGROUND

Mortality from prostate cancer remains a significant problem with current treatment(s), with an expected 30 350 deaths from prostate cancer in 2005. Long-acting natriuretic peptide, vessel dilator, kaliuretic peptide and atrial natriuretic peptide have significant anticancer effects in breast and pancreatic adenocarcinomas. Whether these effects are specific and whether they have anticancer effects in prostate adenocarcinoma cells has not been determined.

MATERIALS AND METHODS

These peptide hormones were evaluated to determine if they have specific anticancer effects in human prostate adenocarcinomas.

RESULTS

Dose-response curves revealed a significant (P < 0.05) decrease in human prostate cancer number with each tenfold increase in the concentration from 1 microM to 1000 microM (i.e. 1 mM) of these four peptide hormones. There was a 97.4%, 87%, 88% and 89% (P < 0.001 for each) decrease in prostate cancer cells secondary to vessel dilator, long-acting natriuretic peptide, kaliuretic peptide and atrial natriuretic peptide, respectively, at their 1-mM concentrations within 24 h, without any proliferation in the 3 days following this decrease. These same hormones decreased DNA synthesis from 68% to 89% (P < 0.001). When utilized with their respective antibodies their ability to decrease prostate adenocarcinoma cells or inhibit their DNA synthesis was completely blocked. Western blots revealed that for the first time natriuretic peptide receptors (NPR) A- and C- were present in prostate cancer cells.

CONCLUSIONS

These results indicate that these peptide hormones' anticancer effects are specific. Furthermore, they have very potent effects of eliminating up to 97% of prostate cancer cells within 24 h of treatment.

Five cardiac hormones decrease the number of human small-cell lung cancer cells

BACKGROUND

Four peptide hormones of a family of six hormones, i.e. atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-natriuretic peptide (CNP), long acting natriuretic peptide (LANP), vessel dilator and kaliuretic peptide, significantly decrease the number of adenocarcinoma cells in culture. The present investigation was designed to determine whether these peptide hormones' effects are specific to adenocarcinomas or whether they might decrease the number of cancer cells of a different type of cancer, i.e. small-cell lung cancer.

METHODS AND MATERIALS

These six hormones were evaluated for their ability to decrease the number and/or proliferation of human small-cell lung cancer cells in culture for 24, 48, 72, and 96 h.

RESULTS

Within 24 h, vessel dilator, LANP, kaliuretic peptide, ANP and their intracellular mediator cyclic GMP, each at 1 microM, decreased the number of small-cell lung cancer cells by 63% (P < 0.001), 21% (P < 0.05), 30% (P < 0.05), 39% (P < 0.05), and 31% (P < 0.05), respectively. There was no proliferation in the 3 days following this decrease in cell number. These same hormones decreased DNA synthesis 68% to 82% (P < 0.001). Brain natriuretic peptide and CNP did not decrease the number of small-cell lung cancer cells or inhibit their DNA synthesis at 1 microM or 10 microM concentrations. Dose-response curves revealed that at 100 microM, the vessel dilator decreased 92% of the cancer cells in 24 h while BNP had no effect, but CNP caused a 39% decrease. Western blots revealed that the natriuretic peptide receptors A- and C- were present in these cancer cells.

CONCLUSIONS

Five peptide hormones significantly decrease the number of human small-cell lung cancer cells within 24 h and inhibit their proliferation for at least 96 h. Their mechanism of doing so involves inhibition of DNA synthesis mediated in part by cyclic GMP.

Four peptide hormones decrease the number of human breast adenocarcinoma cells

BACKGROUND

A family of six hormones, i.e. atrial natriuretic peptide, brain natriuretic peptide, C-natriuretic peptide, long-acting natriuretic peptide, vessel dilator, and kaliuretic peptide's main known biologic properties are sodium and water excreting and blood pressure lowering.

METHODS AND MATERIALS

These six hormones, each at their 1-microm concentrations, were evaluated for their ability to decrease the number and/or proliferation of breast adenocarcinoma cells in culture for 24, 48, 72, and 96 h.

RESULTS

Within 24 h, vessel dilator, long-acting natriuretic peptide, kaliuretic peptide, atrial natriuretic peptide and 8-bromo-cyclic GMP, a cell-permeable analogue of their intracellular mediator cyclic GMP (each at 1 microm), decreased the number of breast adenocarcinoma cells 60%, 31%, 27%, 40%, and 31%, respectively. There was no proliferation in the 3 days following this decrease in breast adenocarcinoma cell number. These same hormones decreased DNA synthesis 69% to 85% (P < 0.001). Brain natriuretic peptide and CNP did not decrease the number of breast adenocarcinoma cells or inhibit their DNA synthesis. Vessel dilator, long-acting natriuretic peptide, kaliuretic peptide and 8-bromo-cyclic GMP (each at 1 microM) decreased the number of cells in the S phase of the cell cycle by 62%, 33%, 50%, and 39%, respectively (all P < 0.05). Natriuretic peptide receptors-A and -C were present in the breast adenocarcinoma cells.

CONCLUSIONS

Four peptide hormones significantly decrease the number of human breast adenocarcinoma cells within 24 h and inhibit the proliferation of these cells for at least 96 h. Their mechanism of doing so involves inhibition of DNA synthesis and a decrease in cells in the S phase of the cell cycle mediated in part by cyclic GMP.