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Natural polyamines (PAs) are key players in cellular homeostasis by regulating cell growth and proliferation. Several observations highlight that PAs are also implicated in pathways regulating cell death. Indeed, the PA accumulation cytotoxic effect, maximized with the use of bovine serum amine oxidase (BSAO) enzyme, represents a valuable strategy against tumor progression. In the present study, along with the design, synthesis, and biological evaluation of a series of new spermine (Spm) analogues ( 1-23 ), a mixed structure-based (SB) and ligand-based (LB) protocol was applied. Binding modes of BSAO-PA modeled complexes led to clarify electrostatic and steric features likely affecting the BSAO-PA biochemical kinetics. LB and SB three-dimensional quantitative structure-activity relationship (Py-CoMFA and Py-ComBinE) models were developed by means of the 3d-qsar.com portal, and their analysis represents a strong basis for future design and synthesis of PA BSAO substrates for potential application in oxidative stress-induced chemotherapy. more...

Purpose: One of the recently developed polyamine (PA) analogues, N 1 ,N 11 -diethylnorspermine (DENSpm), has been found to act as an apoptotic inducer in melanoma, breast, prostate and colon cancer cells. Also, its potential to induce autophagy has been established. Unfolded protein responses and starvation of amino acids are known to trigger autophagy. As yet, however, the molecular mechanism underlying PA deficiency-induced autophagy is not fully clarified. Here, we aimed to determine the apoptotic effect of DENSpm after autophagy inhibition by 3-methyladenine (3-MA) or siRNA-mediated Beclin-1 silencing in colon cancer cells., Methods: The apoptotic effects of DENSpm after 3-MA treatment or Beclin-1 silencing were determined by PI and AnnexinV/PI staining in conjunction with flow cytometry. Intracellular PA levels were measured by HPLC, whereas autophagy and the expression profiles of PA key players were determined in HCT116, SW480 and HT29 colon cancer cells by Western blotting., Results: We found that DENSpm-induced autophagy was inhibited by 3-MA treatment and Beclin-1 silencing, and that apoptotic cell death was increased by PA depletion and spermidine/spermine N 1 -acetyltransferase (SSAT) upregulation. We also found that autophagy inhibition led to DENSpm-induced apoptosis through Atg5 down-regulation, p62 degradation and LC3 lipidation in both HCT116 and SW480 cells. p53 deficiency did not alter the response of the colon cancer cells to DENSpm-induced apoptotic cell death under autophagy suppression conditions., Conclusions: From our results we conclude that DENSpm-induced apoptotic cell death is increased when autophagy is inhibited by 3-MA or Beclin-1 siRNA through PA depletion and PA catabolic activation in colon cancer cells, regardless p53 mutation status. more...

Combination of anticancer drugs with therapeutic microRNA (miRNA) has emerged as a promising anticancer strategy. However, the promise is hampered by a lack of desirable delivery systems. We report on the development of self-immolative nanoparticles capable of simultaneously delivering miR-34a mimic and targeting dysregulated polyamine metabolism in cancer. The nanoparticles were prepared from a biodegradable polycationic prodrug, named DSS-BEN, which was synthesized from a polyamine analog N 1 ,N 11 -bisethylnorspermine (BENSpm). The nanoparticles were selectively disassembled in the cytoplasm where they released miRNA. Glutathione (GSH)-induced degradation of self-immolative linkers released BENSpm from the DSS-BEN polymers. MiR-34a mimic was effectively delivered to cancer cells as evidenced by upregulation of intracellular miR-34a and downregulation of Bcl-2 as one of the downstream targets of miR-34a. Intracellular BENSpm generated from the degraded nanoparticles induced the expression of rate-limiting enzymes in polyamine catabolism (SMOX, SSAT) and depleted cellular natural polyamines. Simultaneous regulation of polyamine metabolism and miR-34a expression by DSS-BEN/miR-34a not only enhanced cancer cell killing in cultured human colon cancer cells, but also improved antitumor activity in vivo. The reported findings validate the self-immolative nanoparticles as delivery vectors of therapeutic miRNA capable of simultaneously targeting dysregulated polyamine metabolism in cancer, thereby providing an elegant and efficient approach to combination nanomedicines., (Copyright © 2016 Elsevier B.V. All rights reserved.) more...

Purpose: N(1),N(11)-diethylnorspermine (DENSPM), a synthetic analog of the naturally occurring polyamine spermine, can induce polyamine depletion and inhibit tumor cell growth. The objectives of this phase I study were to assess the safety, maximum-tolerated dose (MTD), pharmacokinetics, and preliminary antitumor activity of DENSPM in advanced HCC., Methods: Patients with measurable advanced HCC, Child-Pugh A or B cirrhosis, CLIP score ≤3, and Karnofsky score ≥60 % were eligible. DENSPM was given as a short intravenous infusion on days 1, 3, 5, 8, 10, and 12 of each 28-day cycle. The starting dose of 30 mg/m(2) was escalated at a fixed increment of 15 mg/m(2) until the MTD was identified. The plasma pharmacokinetics of DENSPM for the first and last doses given in cycle 1 was characterized., Results: Thirty-eight patients (male 79 %; median age 61 years; Child-Pugh A 84 %; ≥1 prior systemic therapy 45 %) were enrolled and treated. The most common adverse events (AEs) ≥grade 1 were fatigue (53 %), nausea (34 %), diarrhea (32 %), vomiting (32 %), anemia (29 %), and elevated AST (29 %). The most common grade 3-4 AEs were fatigue/asthenia (13 %), elevated AST (13 %), hyperbilirubinemia (11 %), renal failure (8 %), and hyperglycemia (8 %). The MTD was 75 mg/m(2). There were no objective responses, although 7/38 (18 %) patients achieved stable disease for ≥16 weeks. The overall mean (±SD) total body clearance for the initial dose, 66.3 ± 35.9 L/h/m(2) (n = 16), was comparable to the clearance in patients with normal to near normal hepatic function. Drug levels in plasma decayed rapidly immediately after the infusion but remained above 10 nM for several days after dosing at the MTD., Conclusions: N(1),N(11)-diethylnorspermine treatment at the MTD of 75 mg/m(2), given intravenously every other weekday for two consecutive weeks of each 28-day cycle, was relatively well tolerated in patients with advanced HCC including those with mild-to-moderate liver dysfunction. This administration schedule provided prolonged systemic exposure to potentially effective concentrations of the drug. Stable disease was seen in 18 % of patients receiving DENSPM treatment. Further evaluation of DENSPM monotherapy for advanced HCC does not appear to be justified because of insufficient evidence of clinical benefit in the patients evaluated in this study. more...

Numerous studies have shown that platinum compounds stimulate the expression of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase resulting in anti-proliferative activity and apoptosis. As many cancer cell types including pancreatic cancer cells express high levels of polyamines, the possibility to develop anti-tumor strategies to deplete polyamine pools has drawn considerable attention in recent years. This has been effectively accomplished by treating cells with platinum drugs in combination with polyamine analogs such as N(1),N(11)-diethylnorspermine (DENSPM). The present study, examined the cytotoxic effects of oxaliplatin in combination with stimulators of polyamine catabolism in human pancreatic cancer cells, that are notoriously resistant to chemotherapeutic treatment, and colorectal cancer cells. Additionally, as protein kinase CK2 has been shown to be an anti-apoptotic and pro-survival enzyme regulated by the intracellular polyamine pools, we aimed to investigate the effect of combined DENSPM and oxaliplatin treatment on CK2-mRNA and -protein levels. Results reported here show that treatment with oxaliplatin and DENSPM in combination impairs cell viability particularly in the case of colorectal cancer cells. The analysis of CK2 expression and activity indicates that the response to a specific treatment may depend on the impact that individual compounds exert on pro-survival and pro-death proteins at the transcription and translation levels that should be carefully evaluated in view of subsequent clinical studies. more...

Bovine serum amine oxidase (BSAO) oxidatively deaminates polyamines containing primary amine groups, spermidine and spermine, to form the cytotoxic products hydrogen peroxide and aldehyde(s). Polyamines are present at elevated levels in many tumor tissues. The aims of the study were to evaluate the anti-tumoral activities of native and immobilized BSAO in mouse melanoma and also to determine the mechanism of tumor cell death. C57BL mice received a subcutaneous injection of B16 melanoma cells to induce formation of tumors, prior to antitumor treatments with native and immobilized BSAO. The enzyme was immobilized in a poly(ethylene glycol) (PEG) biocompatible matrix. Antitumor treatments consisted of a single injection of enzyme into the tumor. When immobilized BSAO (2.5mU) was injected into the tumor, there was a marked decrease of 70% of the tumor growth. This was compared with a decrease of only 32% of tumor size when the same amount of native BSAO was administered. The type of cell death was analysed in tumors that were treated with native or immobilized BSAO. When tumors were treated with immobilized BSAO, there was induction of a high level of apoptosis (around 70%), compared to less than 10% with the native enzyme. Apoptotic cell death was assessed by nuclear chromatin condensation using Hoechst staining and labelling of externalized phosphatidylserine using Annexin V. However, native BSAO, probably due to a burst of cytotoxic products, induced a high level of necrosis of about 40%, compared to less than 10% with immobilized BSAO. In conclusion, the advantage is that immobilized BSAO can act by allowing the slow release of cytotoxic products, which induces tumor cell death by apoptosis rather than necrosis. more...

Purpose: Polyamines are ubiquitous intracellular polycationic molecules essential for cell growth and differentiation. Polyamine analogs down-regulate ornithine decarboxylase, induce spermidine/spermine N1-acetyltransferase, deplete natural polyamine pools, inhibit growth, and induce programmed cell death in breast cancer models. This study evaluated the activity of the first-generation analog DENSpm in women with metastatic breast cancer., Experimental Design: The overall accrual goal was 34 patients (30 evaluable) in a two-stage design. The second stage of accrual was to proceed if > or =2 among first 15 evaluable patients were progression free at 4 months. The primary objective was to determine whether > or =20% of metastatic breast cancer patients treated with DENSpm as second- or third-line therapy remained progression free after 4 months., Results: Sixteen patients (median age, 52 years; range, 34-65; median performance status, 1; range, 0-1) enrolled in the first stage received 43 cycles (median, 2; range, 1-6) of 100 mg/m2 DENSpm as a 15-min infusion i.v. on days 1-5 every 21 days. All 16 patients were evaluable for toxicity; 15 were evaluable for response. All patients had disease progression by 4 months, and the study closed after the first stage of accrual. The main toxicities included grade 1-2 abdominal pain, transient perioral numbness, nausea, and grade 1 thrombocytopenia. Two patients had grade 3 abdominal pain during cycle 2 infusion: one was hospitalized, and another was subsequently retreated at 80% dose without pain recurrence., Conclusions: Although this dose and administration schedule of DENSpm was quite tolerable, no evidence of clinical activity was detected. Encouraging preclinical activity of polyamine analogs alone and in combination with cytotoxic drugs supports the continued evaluation of newer-generation polyamine analogs for the treatment and prevention of breast cancer. more...

Purpose: Polyamines are essential for tumor growth; consequently, agents that interfere with their metabolisms have been developed as antineoplastic agents. Diethylnorspermine (DENSPM) is one such agent. A focused Phase I clinical trial in patients with advanced non-small cell lung cancer was undertaken., Experimental Design: Twenty-nine patients were treated with DENSPM using a dosing schedule of once daily for 5 days. Doses ranged from 25 mg/m(2)/day to 231 mg/m(2)/day., Results: The dose-limiting toxicity was determined to be gastrointestinal including asthenia, abdominal cramps, diarrhea, and nausea. The maximal tolerated dose was 185 mg/m(2)/day for 5 days. At drug dosages for which it was possible to estimate, serum half-life ranged from 0.5 to 3.7 h without apparent dose dependence. Maximal serum concentrations increased with dosage. However, the increase was greater than the proportional increase of the administered dose. There were no objective disease responses observed during the Phase I trial., Conclusions: The results of the Phase I clinical trial suggest that DENSPM can safely be administered to patients with minimal toxicity. Furthermore, the observed dose-limiting toxicity is unique to DENSPM, thus underscoring the potential for DENSPM to be a suitable agent for chemotherapy in combination with agents possessing different spectrums of toxicities. more...

Polyamines are ubiquitous molecules with multiple intracellular functions. Cells tightly regulate their levels through feedback mechanisms affecting synthesis, intracellular conversion, and transport. Because polyamines have an important role in regulating cell growth, they are a target for cancer therapeutic development. However, to effectively inhibit cell growth through polyamine depletion one needs to inhibit both polyamine synthesis and import. Although the mammalian polyamine transporter has not been cloned, we have identified ORI 1202, an N(1)-spermine-L-lysinyl amide, as an effective polyamine transport inhibitor. ORI 1202 prevents the cellular accumulation of [(3)H]spermidine over a 20-h test period. ORI 1202 (30-100 microM) effectively inhibits cell growth when used in conjunction with the polyamine synthesis inhibitor alpha-difluoromethylornithine (DFMO; > or =230 microM). Human breast, prostate, and bladder carcinoma cell lines and melanoma cell lines show ORI 1202 EC(50) values in the low micromolar range when tested in conjunction with DFMO. This cytostatic effect correlates with a reduction in the intracellular levels of putrescine and spermidine. When ORI 1202 (45 mg/kg, i.p., tidx5) and DFMO (1% in drinking water) were delivered over 14 days, MDA-MB-231 breast tumor xenografts in nude mice showed 50% growth inhibition. Polyamine depletion therapy provides a cytostatic therapy that could be useful against cancer and other diseases resulting from uncontrolled cell growth., (Copyright 2000 Academic Press.) more...

Several new polyamine analogues have been developed for the treatment of human solid tumors. The phenotype-specific activity of some of these analogues has been associated with the superinduction of the rate-limiting enzyme in polyamine catabolism spermidine/spermine N1-acetyltransferase (SSAT). Using immunohistochemistry, we found a majority (64%) of human primary lung cancer explants to exhibit high expression of SSAT after treatment with 10 microM N1,N11-bis(ethyl)norspermine, an agent currently undergoing Phase II clinical trials against several important human solid tumors. The staining of SSAT was found specifically in the tumor tissue and not in the neighboring normal lung tissue. These results demonstrate the ability to detect induction of SSAT in clinical specimens and suggest the potential of this test as a prognostic indicator of drug response. more...

Background: Conventional adjuvant therapy for advanced carcinoid tumors remains disappointing; novel therapeutic agents are needed. We have shown previously that inhibiting polyamine biosynthesis with alpha-difluoromethylornithine (DFMO) slows the growth of carcinoid tumors. However, the clinical utility of DFMO has been limited by its cytostatic property. Synthetic polyamine analogs such as 1,19-bis(ethylamino)-5,10,15-triazanonadecane (BE-4-4-4-4) appear to be cytotoxic against several human tumors. The purpose of our study was to determine whether BE-4-4-4-4 is a more effective antiproliferative and cytotoxic agent than DFMO on human carcinoid (BON) cells in vitro., Methods: BON cells were treated with either 5 mmol/L DFMO, 0.5 to 10 mumol/L BE-4-4-4-4, or vehicle (control). Ornithine decarboxylase activity was determined by the rate of 14CO2 production, and intracellular polyamine levels were determined by chromatography. Cell number and viability were determined by Coulter counter and trypan blue exclusion, respectively., Results: BE-4-4-4-4 inhibited ornithine decarboxylase activity and depleted all 3 polyamines. BE-4-4-4-4 decreased cell numbers by 81% compared with control and 27% compared with DFMO. BE-4-4-4-4 also induced a 2-fold increase in cell death compared with control or DFMO., Conclusions: BE-4-4-4-4 is cytotoxic and more effective than DFMO in inhibiting growth of BON cells. Polyamine analogs such as BE-4-4-4-4 may be effective adjuvant therapeutic agents for advanced carcinoid tumors. more...

The spermine analogue N1,N11-diethylnorspermine (DENSPM) has been shown to induce the polyamine-acetylating enzyme spermidine/spermine N1-acetyltransferase, disrupt polyamine pool homeostasis, and inhibit tumor growth. DENSPM is currently being developed as an anti-neoplastic agent and is about to enter Phase II clinical trials. In this report, the antitumor efficacy of DENSPM was evaluated against a human transitional cell bladder BL13 carcinoma xenograft implanted orthotopically and s.c. in nude athymic mice. DENSPM was administered via continuous s.c. infusion at 93 mg/kg/day for 5 days. Treatment with DENSPM was well tolerated and produced tumor regressions in all mice with a significant proportion (up to 50%) of apparent cures. On the basis of low toxicity and good therapeutic efficacy, there is a strong rationale for evaluation of the therapeutic efficacy of DENSPM against bladder carcinomas in Phase II clinical trials. more...

Background: The capacity of radiation to cure advanced head and neck squamous cell carcinoma is compromised by the proliferation of surviving tumor cells during the course of therapy (overall duration, often 7-9 weeks). Antiproliferative agents that inhibit tumor proliferation, even in the absence of direct cytotoxicity, may be useful adjuncts for concurrent use with radiation. Modulation of endogenous polyamine (PA) metabolism has the potential to inhibit cell growth. The PA analogue 1,19-bis(ethylamino)-5,10,15-triazanonadecane (BE 4444) is a synthetic compound that demonstrates antiproliferative effects in human tumor cells., Objective: To evaluate the PA analogue BE 4444 for its inhibitory effect on the growth of human squamous cell carcinoma xenografts in nude mice., Design: Xenografts of human squamous cell carcinomas were grown in nude mice; then, BE 4444 was injected intraperitoneally (5 mg/kg) on a twice-daily schedule for 8 days. Tumor growth measurements were performed twice weekly for 8 weeks and compared with those of control mice that were injected with sterile saline solution on the same schedule. The PA levels in the tumor and normal tissue samples were assayed at the completion of treatment., Results: Tumor volume in the BE 4444-treated mice was reduced by 62% compared with tumor volumes in control mice, and the tumor growth rate was reduced by 64%. This growth inhibition was maintained through completion of the experiment. Levels of endogenous PAs were not significantly different from control levels, suggesting that the mechanism of action for BE 4444 is not simply PA biosynthesis inhibition., Conclusions: The PA analogue BE 4444 is an inhibitor of human squamous cell cancer growth. Further studies are in progress to characterize the potential value of PA analogues as adjuncts to radiation therapy for rapidly proliferating squamous cell carcinoma of the head and neck. more...

Certain N-alkylated analogues of the natural polyamine spermine have been found to disrupt polyamine pool homeostasis and inhibit tumor cell growth. The most effective of these analogues, N1, N11-diethylnorspermine (DENSPM), apparently depletes intracellular polyamine pools primarily by inducing the polyamine acetylating enzyme spermidine/spermine N1-acetyltransferase, which contributes to polyamine depletion via increased polyamine excretion and catabolism. In this report, the experimental therapeutic efficacy of DENSPM was further examined with the use of other human solid tumor xenografts, including A121 ovarian carcinoma, A549 lung adenocarcinoma, HT29 colon carcinoma, and SH-1 melanoma, and compared with previously obtained findings with MALME-3M and PANUT-3 human melanomas. In vitro studies indicated that the growth sensitivity of most tumor cell lines to DENSPM was similar, with characteristically flat dose-response curves and IC50s ranging between 0.1 and 1 micrometer the only exception was the HT29 colon carcinoma cell line, which had an IC50 of >100 micrometer. For in vivo studies, DENSPM was administered by i.p. injection to female nude athymic mice at 40 and/or 80 mg/kg 3 times a day (every 8 h) for 6 days or by continuous s.c. infusion with the use of Alzet pumps at 120, 240, or 360 mg/kg/day for 4 days. Treatment began after s.c. tumor xenografts had reached 100-200 mm3. The SH-1 melanoma, A549 lung adenocarcinoma, and A121 ovarian carcinoma xenografts responded well to the i.p. administration of analogue with obvious tumor regressions, long-term tumor growth suppressions, and a significant proportion (up to 40%) of apparent cures (i.e., lack of tumor regrowth). However, in similarity to in vitro findings, HT29 colon carcinoma xenografts responded poorly to DENSPM treatment. Massive induction of N1-acetyltransferase activity and extensive depletion of polyamine pools were consistent findings in most tumor types after in vivo or in vitro treatment with DENSPM. The rapidly growing human LOX melanoma xenograft, however, demonstrated poor induction of N1-acetyltransferase activity and the poorest response to DENSPM treatment. In nude athymic mice with MALME-3M melanoma xenografts, constant infusion delivery of DENSPM resulted in prolonged inhibition of tumor growth and long-term tumor regressions comparable to those produced by multiple i.p. injections. On the basis of the unique structure of DENSPM, novel target and mode of intervention, mild host toxicity, and activity against different human solid tumor xenografts, DENSPM is currently being developed as an antitumor agent in humans. more...

N-Alkylated polyamine analogues have been shown to exert antiproliferative effects in several tumor models, with the bis-ethyl derivatives exerting the greatest suppression of polyamines by virtue of down-regulation of the polyamine biosynthetic enzymes. Pancreatic adenocarcinoma presents a challenge both clinically and experimentally due to its inherent resistance to conventional therapy, which results in its having the worst 5-year survival rate of all cancers. We have previously shown that N1,N12-bis(ethyl)spermine (BESPM) is much more potent than the polyamine enzyme inhibitor alpha-difluoromethylornithine (DFMO) against pancreatic adenocarcinoma cell lines. In the present study, we compared the biochemical and antiproliferative effects of two N-alkylated polyamine analogues, N1,N14-bis(ethyl)homospermine (BEHSPM) and N1,N11-bis(ethyl)norspermine (BENSPM) in two human pancreatic ductal adenocarcinoma cell lines, PANC-1 (poorly differentiated) and BxPC-3 (moderately well-differentiated), and in the WD PaCa (well-differentiated ductal) hamster cell line. BENSPM displayed greater antiproliferative activity in the human pancreatic cancer cell lines, whereas BEHSPM was more potent in the hamster cell line. Both BEHSPM and BENSPM suppress the activity of the major biosynthetic enzymes ornithine decarboxylase and S-adenosylmethionine decarboxylase. However, the induction of polyamine depletion in the human cell lines was only modest for BENSPM and minimal for BEHSPM, which suggests that the substantial antiproliferative activity of these analogues may result from mechanisms other than polyamine depletion. The somewhat greater polyamine depletion seen following treatment with BENSPM is thought to result from its striking induction of spermidine/spermine N1-acetyltransferase. The biochemical and antiproliferative activity of BENSPM makes it an attractive agent for further preclinical and clinical development, especially in pancreatic cancer. more...

Adenocarcinoma of the pancreas presents a formidable challenge both experimentally and clinically, whereby effective anticancer therapy is lacking. We have recently explored a relatively new class of antitumor agents in pancreatic cancer cell lines and have found the bis-ethyl derivatives of spermine to show considerable promise. In the present paper, we report the results of in vivo studies demonstrating the antitumor activity of two of these N-alkylated analogues, N1,N14-bis(ethyl)homospermine (BEHSPM) and N1,N11-bis(ethyl)norspermine (BENSPM) in athymic (nude) mouse xenografts of two human pancreatic ductal adenocarcinoma cell lines, PANC-1 (poorly differentiated) and BxPC-3 (moderately well-differentiated). BENSPM was found to exert greater antitumor activity in vivo than either BEHSPM or other conventional agents, largely because higher doses could be given due to its lower toxicity to mice. BENSPM shows greater activity than any other agent we have thus far tested against our pancreatic-cancer models. Optimal schedules of administration have yet to be determined. Nevertheless, of the analogues tested, BENSPM presently appears to be the analogue of choice for further development. more...

The therapeutic concept of irreversible inhibition of both ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) by alpha-difluoromethylornithine (DFMO) and methylglyoxal bis-guanylhydrazone (MGBG) is based on pathologic activities of these enzymes in tumor tissue. The polyamines putrescine, spermidine and spermine are measured in highest concentration in the prostate of both men and animals, with a significant increase of spermine in benign hyperplasia of the prostate. Patients with metastatic cancer of the prostate have elevated putrescine levels in the 24-hour urine. Treatment with 3 or 1% DFMO or 11 mg/kg MGBG in transplantable human and experimental cancer of the prostate demonstrated a significant anti-growth effect. A combination of DFMO and MGBG is tumor-destructive. The combination of 1% DFMO and 11 mg/kg MGBG distinctly reduces the activity of ODC and SAMDC and significantly lowers the levels of putrescine, spermidine and spermine in the tumor. more...