Loss of inhibitor of apoptosis proteins as a determinant of polyamine analog-induced apoptosis in human melanoma cells

Hyaluronate-coated perfluoroalkyl polyamine prodrugs as bioactive siRNA delivery systems for the treatment of peritoneal cancers

RNA interference (RNAi) is an emerging therapeutic modality for cancer, which remains in critical need of effective delivery vectors due to the unfavorable biopharmaceutical properties of small RNAs. Polyamines are essential for functioning of mammalian cells. Dysregulated polyamine metabolism is found in many cancers and has been an attractive therapeutic target in combination therapies. Combination therapies based on drugs that affect polyamine metabolism and nucleic acids promise to enhance anticancer activity due to a cooperative effect on multiple oncogenic pathways. Here, we report bioactive polycationic prodrug (F-PaP) based on an anticancer polyamine analog bisethylnorspermine (BENSpm) modified with perfluoroalkyl moieties. Following encapsulation of siRNA, F-PaP/siRNA nanoparticles were coated with hyaluronic acid (HA) to form ternary nanoparticles HA@F-PaP/siRNA. The presence of perfluoroalkyl moieties and HA reduced cell membrane toxicity and improved stability of the particles with cooperatively enhanced siRNA delivery in pancreatic and colon cancer cell lines. We then tested a therapeutic hypothesis that combining BENSpm with siRNA silencing of polo-like kinase 1 (PLK1) would result in cooperative cancer cell killing. HA@F-PaP/siPLK1 induced polyamine catabolism and cell cycle arrest, leading to enhanced apoptosis in the tested cell lines. The HA-coated nanoparticles facilitated tumor accumulation and contributed to strong tumor inhibition and favorable modulation of the immune tumor microenvironment in orthotopic pancreatic cancer model. Combination anticancer therapy with polyamine prodrug-mediated delivery of siRNA. Hyaluronate coating of the siRNA nanoparticles facilitates selective accumulation in orthotopic pancreatic tumors. Perfluoroalkyl conjugation reduces toxicity and improves gene silencing effect. Nanoparticle treatment induces polyamine catabolism and cell cycle arrest leading to strong tumor inhibition and favorable modulation of immune tumor microenvironment.

Co-Delivery of Eugenol and Dacarbazine by Hyaluronic Acid-Coated Liposomes for Targeted Inhibition of Survivin in Treatment of Resistant Metastatic Melanoma

While melanoma remains a challenge for oncologists, possibilities are being continuously explored to fight resistant metastatic melanoma more effectively. Eugenol is reported to inhibit survivin protein in breast cancer cells. Survivin is also overexpressed by melanoma cells, and is known to impart resistance to them against chemotherapy-induced apoptosis. To be able to fight resistant melanoma, we formulated hyaluronic acid (HA)-coated liposomes loaded with an effective combination of anti-melanoma agents (Dacarbazine and Eugenol), using a solvent injection method. Quality-by-Design (QbD) was applied to optimize and obtain a final formulation with the desired quality attributes, and within an acceptable size range. The optimized formulation was then subjected to performance analysis in cell lines. Coated-Dacarbazine Eugenol Liposomes were found to possess 95.08% cytotoxicity at a dacarbazine concentration of 0.5 µg/mL, while Dacarbazine Solution showed only 10.20% cytotoxicity at the same concentration. The number of late apoptotic cells was also found to be much higher (45.16% vs. 8.43%). Furthermore, migration assay and proliferation study also revealed significantly higher inhibition of cell migration and proliferation by Coated-Dacarbazine Eugenol Liposomes, signifying its potential against metastasis. Thus, surface-functionalized dacarbazine- and eugenol-loaded liposomes hold great promise against resistant and aggressive metastatic melanoma, with much less unwanted cytotoxicity and reduced doses of the chemotherapeutic agent.

Coupling of the polyamine and iron metabolism pathways in the regulation of proliferation: Mechanistic links to alterations in key polyamine biosynthetic and catabolic enzymes

Many biological processes result from the coupling of metabolic pathways. Considering this, proliferation depends on adequate iron and polyamines, and although iron-depletion impairs proliferation, the metabolic link between iron and polyamine metabolism has never been thoroughly investigated. This is important to decipher, as many disease states demonstrate co-dysregulation of iron and polyamine metabolism. Herein, for the first time, we demonstrate that cellular iron levels robustly regulate 13 polyamine pathway proteins. Seven of these were regulated in a conserved manner by iron-depletion across different cell-types, with four proteins being down-regulated (i.e., acireductone dioxygenase 1 [ADI1], methionine adenosyltransferase 2α [MAT2α], Antizyme and polyamine oxidase [PAOX]) and three proteins being up-regulated (i.e., S-adenosyl methionine decarboxylase [AMD1], Antizyme inhibitor 1 [AZIN1] and spermidine/spermine-N¹-acetyltransferase 1 [SAT1]). Depletion of iron also markedly decreased polyamine pools (i.e., spermidine and/or spermine, but not putrescine). Accordingly, iron-depletion also decreased S-adenosylmethionine that is essential for spermidine/spermine biosynthesis. Iron-depletion additionally reduced ³H-spermidine uptake in direct agreement with the lowered levels of the polyamine importer, SLC22A16. Regarding mechanism, the "reprogramming" of polyamine metabolism by iron-depletion is consistent with the down-regulation of ADI1 and MAT2α, and the up-regulation of SAT1. Moreover, changes in ADI1 (biosynthetic) and SAT1 (catabolic) partially depended on the iron-regulated changes in c-Myc and/or p53. The ability of iron chelators to inhibit proliferation was rescuable by putrescine and spermidine, and under some conditions by spermine. Collectively, iron and polyamine metabolism are intimately coupled, which has significant ramifications for understanding the integrated role of iron and polyamine metabolism in proliferation.

Inhibition of autophagy enhances DENSpm-induced apoptosis in human colon cancer cells in a p53 independent manner

PURPOSE

One of the recently developed polyamine (PA) analogues, N ¹ ,N¹¹-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 N¹-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.

Livin/BIRC7 expression as malignancy marker in adrenocortical tumors

Livin/BIRC7 is a member of the inhibitors of apoptosis proteins family, which are involved in tumor development through the inhibition of caspases. Aim was to investigate the expression of livin and other members of its pathway in adrenocortical tumors and in the adrenocortical carcinoma (ACC) cell line NCI-H295R.

The mRNA expression of livin, its isoforms α and β, XIAP, CASP3 and DIABLO was evaluated by qRT-PCR in 82 fresh-frozen adrenal tissues (34 ACC, 25 adenomas = ACA, 23 normal adrenal glands = NAG). Livin protein expression was assessed by immunohistochemistry in 270 paraffin-embedded tissues (192 ACC, 58 ACA, 20 NAG). Livin, CASP3 and cleaved caspase-3 were evaluated in NCI-H295R after induction of livin overexpression.

Relative livin mRNA expression was significantly higher in ACC than in ACA and NAG (0.060 ± 0.116 vs 0.004 ± 0.014 and 0.002 ± 0.009, respectively, p < 0.01), being consistently higher in tumors than in adjacent NAG and isoform β more expressed than α. No significant differences in CASP3, XIAP and DIABLO levels were found among these groups. In immunohistochemistry, livin was localized in both cytoplasm and nuclei. The ratio between cytoplasmic and nuclear staining was significantly higher in ACC (1.51 ± 0.66) than in ACA (0.80 ± 0.35) and NAG (0.88 ± 0.27; p < 0.0001). No significant correlations were observed between livin expression and histopathological parameters or clinical outcome. In NCI-H295R cells, the livin overexpression slightly reduced the activation of CASP3, but did not correlate with cell viability.

In conclusion, livin is specifically over-expressed in ACC, suggesting that it might be involved in adrenocortical tumorigenesis and represent a new molecular marker of malignancy.

Significant correlation between urinary N(1), N(12)-diacetylspermine and tumor invasiveness in patients with clinical stage IA non-small cell lung cancer

Background

To select optimal candidates for limited lung resection, it is necessary to accurately differentiate the non-invasive tumors from other small-sized lung cancer. Urinary N¹, N¹²-diacetylspermine (DiAcSpm) has been reported to be a useful tumor marker for various cancers. We aimed to examine the correlation between preoperative urinary DiAcSpm levels and specific clinicopathological characteristics such as the histological tumor invasiveness in patients with clinical stage IA non-small cell lung cancer (NSCLC).

Methods

We defined non-invasive tumors as NSCLC showing no vascular invasion, lymphatic permeation, pleural invasion, or lymph node metastasis. Preoperative urine samples were obtained from 516 consecutive patients with NSCLC resected at our institution between April 2008 and January 2013. Urinary DiAcSpm values were determined for all preoperative urine samples using the colloid gold aggregation procedure. Among these patients, 171 patients with clinical stage IA NSCLC met the criteria of our study cohort. Finally, we investigated the correlation between non-invasive tumor and urinary DiAcSpm levels.

Results

The median urine DiAcSpm for males was 147.2 nmol/g creatinine and 161.8 nmol/g creatinine in females. These median values were set as the cut-off values for each gender. Patients with higher urinary DiAcSpm levels frequently had significantly elevated serum CEA (p = 0.023) and greater lymph node metastasis (p = 0.048), lymphatic permeation (p = 0.046), and vascular invasion (p = 0.010). Compared with patients with non-invasive tumors, patients with invasive tumors had a tumor size >2.0 cm (p = 0.001), serum CEA >5.0 mg/dL (p < 0.001), high urinary DiAcSpm (p = 0.002), and a tumor disappearance rate (TDR) <0.75 (p < 0.001). Multivariate analysis revealed that a tumor size < 2.0 cm (RR = 2.901, 95% CI; 1.372-6.136, p = 0.005), high urinary DiAcSpm (RR = 3.374, 95% CI; 1.547-7.361, p = 0.002), and TDR < 0.75 (RR = 4.673, 95% CI; 2.178-10.027, p < 0.001) were independent predictors for invasive tumors.

Conclusions

We successfully showed that there was a significant correlation between urinary DiAcSpm levels and pathological tumor invasiveness in patients with clinical stage IA NSCLC. Further research would elucidate the clinical usefulness of DiAcSpm levels as a predictor of tumor invasiveness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1068-5) contains supplementary material, which is available to authorized users.

Lack of functional p53 renders DENSpm-induced autophagy and apoptosis in time dependent manner in colon cancer cells

Polyamines (PAs), such as putrescine, spermidine and spermine, are alkyl-amines that are essential for cell growth, proliferation, differentiation and cancer progression in eukaryotic cells. A designed PA analogue; DENSpm, induces cell cycle arrest, inhibits proliferation and induces apoptosis in melanoma, breast, prostate, lung and colon cancer cells. Although the mechanism by which DENSpm induces apoptosis has been examined, the effect of DENSpm on autophagy has not been investigated yet. Therefore, in this study, our objective was to determine the role of p53 in the DENSpm-induced autophagy/apoptotic regulation in a time-dependent manner in colon cancer cells. Exposure of HCT 116 colon cancer cells to DENSpm decreased cell viability in a dose- and time-dependent manner. However, the p53 mutant, SW480, and deficient HCT 116 p53(-/-) cells were more resistant to DENSpm treatment compared to HCT 116 p53(+/+) cells. The resistant profile caused by p53 defect also caused a cell type-specific response to PA pool depletion and SSAT overexpression. In addition to PA depletion, DENSpm induced apoptosis by activating the mitochondria-mediated pathway in a caspase-dependent manner regardless of p53 expression in colon cancer cells. Concomitantly, we determined that DENSpm also affected autophagy in HCT 116 p53(+/+), SW480 and HCT 116 p53(-/-) colon cancer cells for different periods of exposure to DENSpm. Therefore, this study revealed that effect of DENSpm on cell death differs due to p53 protein expression profile. In addition, DENSpm-induced autophagy may be critical in drug resistance in colon cancer cells.

Polyamines and programmed cell death

Polyamines (PAs) have been considered as important molecules for survival. However, evidence reinforces that PAs are also implicated, directly or indirectly, in pathways regulating programmed cell death (PCD). Direct correlation of PAs with cell death refers to their association with particular biological processes, and their physical contact with molecules or structures involved in cell death. Indirectly, PAs regulate PCD through their metabolic derivatives, such as catabolic and interconversion products. Cytotoxic products of PA metabolism are involved in PCD cascades, whereas it remains largely elusive how PAs directly control pathways leading to PCD. In this review, we present and compare advances in PA-dependent PCD in animals and plants.

Polyamine catabolism in relation to trypsin activation and apoptosis in experimental acute pancreatitis

BACKGROUND

Overinduced polyamine catabolism (PC) in a transgenic rat model has been suggested to be a mediator of trypsin activation which is important in acinar cell necrosis. PC has also been observed in experimental taurodeoxycholate pancreatitis. We hypothesized that PC may be a mediator of trypsin activation in taurodeoxycholate pancreatitis.

METHODS

Pancreatitis was induced in wild-type rats by 2 or 6% taurodeoxycholate infusion or in transgenic rats by overexpressing spermidine/spermine N(1)-acetyltransferase (SSAT). The time courses of necrosis, caspase-3 immunostaining, SSAT, polyamine levels, and trypsinogen activation peptide (TAP) were monitored. The effect of the polyamine analogue bismethylspermine (Me(2)Spm) was investigated.

RESULTS

In a transgenic pancreatitis model, TAP and acinar necrosis increased simultaneously after the activation of SSAT, depletion of spermidine, and development of apoptosis. In taurodeoxycholate pancreatitis, necrosis developed along with the accumulation of TAP. SSAT was activated simultaneously or after TAP accumulation and less than in the transgenic model, with less depletion of spermidine than in the transgenic model. Supplementation with Me(2)Spm ameliorated the extent of acinar necrosis at 24 h, but contrary to previous findings in the transgenic model, in the taurodeoxycholate model it did not affect trypsin activation. Compared with the transgenic model, no extensive apoptosis was found in taurodeoxycholate pancreatitis.

CONCLUSIONS

Contrary to transgenic SSAT-overinduced pancreatitis, PC may not be a mediator of trypsin activation in taurodeoxycholate pancreatitis. The beneficial effect of polyamine supplementation on necrosis in taurodeoxycholate pancreatitis may rather be mediated by other mechanisms than amelioration of trypsin activation. and IAP.

Galactoglucomannan oligosaccharide supplementation affects nutrient digestibility, fermentation end-product production, and large bowel microbiota of the dog

A galactoglucomannan oligosaccharide (GGMO) obtained from fiberboard production was evaluated as a dietary supplement for dogs. The GGMO substrate contained increased concentrations of oligosaccharides containing mannose, xylose, and glucose, with the mannose component accounting for 35% of DM. Adult dogs assigned to a 6 × 6 Latin square design were fed 6 diets, each containing a different concentration of supplemental GGMO (0, 0.5, 1, 2, 4, and 8%) that replaced dietary cellulose. Total tract DM and OM apparent digestibilities increased (P < 0.001) linearly, whereas total tract CP apparent digestibility decreased (P < 0.001) linearly as dietary GGMO substrate concentration increased. Fecal concentrations of acetate, propionate, and total short-chain fatty acids increased (P ≤ 0.001) linearly, whereas butyrate concentration decreased (P ≤ 0.001) linearly with increasing dietary concentrations of GGMO. Fecal pH decreased (P ≤ 0.001) linearly as dietary GGMO substrate concentration increased, whereas fecal score increased quadratically (P ≤ 0.001). Fecal phenol (P ≤ 0.05) and indole (P ≤ 0.01) concentrations decreased linearly with GGMO supplementation. Fecal biogenic amine concentrations were not different among treatments except for phenylethylamine, which decreased (P < 0.001) linearly as dietary GGMO substrate concentration increased. Fecal microbial concentrations of Escherichia coli, Lactobacillus spp., and Clostridium perfringens were not different among treatments. A quadratic increase (P ≤ 0.01) was noted for Bifidobacterium spp. as dietary GGMO substrate concentration increased. The data suggest positive nutritional properties of supplemental GGMO when incorporated in a good-quality dog food.

PPARgamma is involved in mesalazine-mediated induction of apoptosis and inhibition of cell growth in colon cancer cells

PURPOSE

Mesalazine has been identified as a candidate chemopreventive agent in colon cancer prophylaxis because of its pro-apoptotic and anti-proliferative effects. However, the precise mechanisms of action are not entirely understood. The aim of our study was to investigate the involvement of peroxisome proliferator-activated receptor gamma (PPARgamma) in mesalazine's anticarcinogenic actions in colorectal cancer cells.

EXPERIMENTAL DESIGN

The effects of mesalazine on cell cycle distribution, cell count, proliferation and caspase-mediated apoptosis were examined in Caco-2, HT-29 and HCT-116 cells used as wild-type, dominant-negative PPARgamma mutant and empty vector cultures. We focused on caspase-3 activity, cleavage of poly(ADP-ribose) polymerase (PARP), caspase-8 and caspase-9, as well as on expression of survivin, X-linked inhibitor of apoptosis (Xiap), phosphatase and tensin homolog deleted from chromosome ten (PTEN) and c-Myc. Techniques employed included transfection assays, immunoblotting, flow cytometry analysis, colorimetric and fluorometric assays.

RESULTS

Mesalazine caused a time- and dose-dependent decrease in both cell growth and proliferation. Growth inhibition was accompanied by a G1/G0 arrest, a significant increase in PTEN, caspase-3 activity, cleavage of PARP and caspase-8, whereas the expressions of Xiap, survivin and c-Myc were decreased simultaneously. Cleavage of caspase-9 was not observed. Moreover, PPARgamma expression and activity were elevated. The growth-inhibitory effect of mesalazine was partially reduced in dominant-negative PPARgamma mutant cells, whereas the expression of c-Myc was not affected. Mesalazine-mediated increased caspase-3 activity, the expression of PTEN, cleavage of PARP and caspase-8 as well as reduced levels of survivin and Xiap were completely abolished in the PPARgamma mutant cell lines.

CONCLUSION

This study clearly demonstrates that mesalazine-mediated pro-apoptotic and anti-proliferative actions are regulated via PPARgamma-dependent and -independent pathways in colonocytes.

Diacetylated derivatives of spermine and spermidine as novel promising tumor markers

N1,N12-diacetylspermine (DiAcSpm) and N1,N8-diacetylspermidine (DiAcSpd) are minor components of human urinary polyamine to which little attention has been paid until recently. HPLC analysis of urinary polyamines has revealed that the excretion of these diacetylpolyamines, in particular, into urine was frequently and markedly increased in association with every type of cancer so far examined. Remission was usually accompanied by recovery of urinary diacetylpolyamines to the normal level. DiAcSpm was more sensitive than CEA for detecting colorectal cancer patients, while DiAcSpd was highly specific for malignant conditions in that the excretion of the latter was scarcely elevated in cases of benign urogenital diseases. An ELISA procedure for rapid determination of DiAcSpm was developed to promote the clinical application of these new tumor markers, and subsequent studies indicated that DiAcSpm was elevated in 60% of colorectal cancer patients at early stages (stage 0 + I), whereas only 10% of these patients were CEA-positive. DiAcSpm may also be useful as a follow-up marker that is efficient for detecting recurrence and sensitive to changes in the clinical condition of patients. The evidence accumulated so far indicates that DiAcSpm and DiAcSpd are promising novel tumor markers. They deserve more intensive studies, including studies of their biochemistry and metabolism.

Targeting polyamine metabolism and function in cancer and other hyperproliferative diseases

The polyamines spermidine and spermine and their diamine precursor putrescine are naturally occurring, polycationic alkylamines that are essential for eukaryotic cell growth. The requirement for and the metabolism of polyamines are frequently dysregulated in cancer and other hyperproliferative diseases, thus making polyamine function and metabolism attractive targets for therapeutic intervention. Recent advances in our understanding of polyamine function, metabolic regulation, and differences between normal cells and tumour cells with respect to polyamine biology, have reinforced the interest in this target-rich pathway for drug development.

Inhibition of cell proliferation and induction of apoptosis by N1,N11-diethylnorspermine-induced polyamine pool reduction

Reduction of cellular polyamine pools results in inhibition of cell proliferation and sometimes in induction of cell death. Reduction of cellular polyamine pools can be achieved by several strategies involving all the mechanisms of polyamine homoeostasis, i.e. biosynthesis, catabolism and transport across the cell membrane. In the present paper, we concentrate on results achieved using the polyamine analogue DENSPM (N1,N11-diethylnorspermine) on different cell lines. We discuss polyamine levels in DENSPM-treated cells in relation to effects on cell cycle kinetics and induction of apoptosis. To really understand the role of polyamines in cell cycle regulation and apoptosis, we believe it is now time to go through the vast polyamine literature in a meta-analysis-based manner. This short review does not claim to be such a study, but it is our hope to stimulate such studies in the polyamine field. Such work is especially important from the viewpoint of introducing drugs that affect polyamine homoeostasis in the treatment of various diseases such as cancer.

Platinum drug effects on the expression of genes in the polyamine pathway: time-course and concentration-effect analysis based on Affymetrix gene expression profiling of A2780 ovarian carcinoma cells

PURPOSE

As a follow-up to our previous findings that platinum drugs induce a key enzyme in polyamine catabolism, gene expression profiling and mathematical modeling were used to define the effects of cisplatin and oxaliplatin on the expression of polyamine metabolic pathway genes in A2780 human ovarian carcinoma cells.

METHODS

Time-course and concentration-effect experiments were each carried out with cisplatin or oxaliplatin in two separate experiments and cells subjected to gene expression profiling using Affymetrix array technology. Time-course data were modeled using exponential increase and decrease models. Concentration-effect data were modeled using a four parameter Hill model.

RESULTS

Gene expression profiling of human ovarian carcinoma A2780 cells after exposure to either cisplatin or oxaliplatin indicates that the expression of several genes involved in polyamine pathway is affected by the platinum drugs. Mathematical/Statistical modeling of the data from time-course and concentration-effect experiments of gene expression from nine polyamine pathway genes represented on the HGU95Av2 chip, indicates that three biosynthetic pathway genes (SAMDC, ODC1 and SRM) are down-regulated and one catabolic pathway gene (SSAT) is up-regulated. Expression changes were similar for different probesets for a given gene on the array. Studies on the induction of SSAT by platinum drugs suggested by the Affymetrix data have been previously validated from this laboratory (Hector et al. in Mol Cancer Ther 3:813-822, 2004). Here, the effects of oxaliplatin exposure on SAMDC and ODC observed by Affymetix are validated with real time QRT-PCR.

CONCLUSION

The data indicate a concerted effect of platinum drugs on the polyamine metabolic pathway with down-regulation in the expression of several enzyme genes involved in biosynthesis and many-fold up-regulation in expression of SSAT, an acetylating enzyme gene that is critically involved in polyamine catabolism and export.

N(1),N(12)-Diacetylspermine as a sensitive and specific novel marker for early- and late-stage colorectal and breast cancers

PURPOSE

N(1),N(12)-diacetylspermine (DiAcSpm) in the urine of colorectal and breast cancer patients was examined to establish its usefulness as a novel diagnostic tool for detecting these cancers at clinically early stages.

EXPERIMENTAL DESIGN

Urine samples from 248 colon cancer patients and 83 breast cancer patients as well as 51 patients with benign gastrointestinal diseases treated in Tokyo Metropolitan Komagome Hospital during the period of August 1999 to January 2004 were collected. DiAcSpm was analyzed by ELISA and its sensitivity for malignant conditions was compared with that of serum carcinoembryonic antigen (CEA), CA19-9, and CA15-3.

RESULTS

The sensitivity of urinary DiAcSpm for colon cancer patients (n = 248) was 75.8% (mean +/- 2 SD for 52 healthy controls as a cutoff value), which was markedly higher than the sensitivities of serum CEA (39.5%, P < 0.0001) and CA19-9 (14.1%, P < 0.0001). DiAcSpm was elevated in 60% of tumor-node-metastasis cancer stage 0 + I patients, whereas only 10% (P < 0.0001) and 5% (P < 0.0001) of these patients were CEA- and CA19-9-positive, respectively. The sensitivity of urinary DiAcSpm for 83 cases of breast cancer (60.2%) was higher than the sensitivities of CEA (37.3%, P = 0.0032) and CA15-3 (37.3%, P = 0.0032). DiAcSpm was elevated in 28% of tumor-node-metastasis stage I + II patients, whereas only 3% (P = 0.0064) and 0% (P = 0.001) of these patients were CEA- and CA15-3-positive, respectively.

CONCLUSION

The observations indicate that urinary DiAcSpm is a more sensitive marker than CEA, CA19-9, and CA15-3 and that it can efficiently detect colorectal and breast cancers at early stages.

Effects of antioxidants and caspase-3 inhibitor on the phenylethyl isothiocyanate-induced apoptotic signaling pathways in human PLC/PRF/5 cells

Phenylethyl isothiocyanate (PEITC) is a well recognized potential chemopreventive compound against human cancers. In this study, the molecular mechanism of PEITC-induced apoptosis was examined with two antioxidants (N-acetyl-cysteine and vitamin E) and a caspase-3 inhibitor (z-DEVD-fmk). Results demonstrated that PEITC significantly induced human hepatoma PLC/PRF/5 (CD95-negative) cells undergoing apoptosis. Treatment with 0 approximately 10 microM PEITC-triggered cell apoptosis as revealed by the externalization of annexin V-targeted phosphatidylserine and the subsequent appearance of sub-G1 population. Results also displayed that PEITC-induced apoptosis involves the up-regulation of p53 and Bax protein, down-regulation of the XIAP, Bcl-2, Bcl-(XL) and Mcl-1 proteins, cleavage of Bid, and the release of cytochrome c and Smac/Diablo, which were accompanied by the activation of caspases -9, -3 and -8. PEITC-induced the generation of reactive oxygen species and the decrease of mitochondrial membrane potential (Deltapsim) in a time-dependent pattern. N-acetyl-cysteine and vitamin E at 100 microM, and z-DEVD-fmk at 50 microM markedly blocked PEITC-induced apoptosis, which was demonstrated by a decline in the reactive oxygen species generation and the release of the cytochrome c and Smac/Diablo from mitochondria to the cytosol. N-acetyl-cysteine, vitamin E and z-DEVD-fmk also prevented the PEITC in inducing the loss of Deltapsim. They also affected the activity of XIAP and Bax proteins. Taken together, these studies suggest that PEITC is an apoptotic inducer that acts on the mitochondria and the feedback amplification loop of caspase-8/Bid pathways in PLC/PRF/5 cells.

De-regulation of ubiquitin-dependent proteolysis and the pathogenesis of malignant melanoma

Malignant melanoma is similar to the other types of cancer in terms that the pathogenesis of this lethal disease includes abnormal activation of proteins that mediate oncogenic signaling as well as inhibition of anti-proliferative and pro-apoptotic protein regulators. Activity of both types of cellular regulators is often dependent on their abundance and is determined by the rate of proteolysis via the ubiquitin pathway. Aberrations in ubiquitin-dependent degradation of regulatory proteins frequently occur in human cancers including malignant melanoma. Melanoma cells that re-program ubiquitin-dependent proteolysis toward accelerated degradation of protein regulators of tumor suppression and abnormal stabilization of oncogenic proteins are likely to gain an advantage in growth and survival. Specific characteristics of melanoma biology include rapid metastasizing and resistance to conventional anticancer therapy. Exploration of these traits should place an emphasis on a subset of the signal transduction pathways that are governed by a number of key protein regulators whose stability and activity becomes deregulated during progression of malignant melanoma. Targeting the ubiquitination and degradation of these pivotal proteins may provide a promising new therapeutic approach to treatment of this disease.

Pharmacological aspects of cytotoxic polyamine analogs and derivatives for cancer therapy

During the past 20 years, numerous derivatives and analogues of spermidine (Spd) and spermine (Spm) were synthesized with the aim to generate a new type of anticancer drug. The common denominator of most cytotoxic polyamine analogues is their lipophilicity, which is superior to that of the parent amines. The natural polyamines bind to polyanions and to proteins with anionic binding sites. Their hydrophilicity/hydrophobicity is balanced, allowing them to perform physiological functions by interacting with some of these anionic structures, without impairing the functionality of others. Because the attachment of lipophilic substituents to the polyamine backbone increases the binding energy, lipophilic polyamine derivatives affect secondary and tertiary structures of a larger number of macromolecules than do their natural counterparts. In addition, lipophilicity improves the blood-brain barrier transport and thus enhances CNS toxicity. Close structural analogues of spermidine and spermine mimic the natural polyamines in regulatory functions. The cytotoxic mechanisms of analogues with a less close structural resemblance to spermidine or spermine have not been completely clarified. The displacement of spermidine from functional binding sites and the consequent prevention of its physiological roles is a likely mechanism, but many others may play a role as well. Up to now, polyamine analogues were conceived without specific growth-related targets in mind. To develop therapeutically useful drugs, it will be imperative to identify specific targets and to design compounds that interact selectively with the target molecules. It will also be necessary to include, at an early state of the work, pharmacological and toxicological considerations, to avoid unproductive directions.

Effects of vitamin E on the cinnamaldehyde-induced apoptotic mechanism in human PLC/PRF/5 cells

1. Cinnamaldehyde has been shown to be effective in inducing cell apoptosis in a number of human cancer cells. The aim of the present study was to investigate the effect of vitamin E on the apoptotic signalling mechanism induced by cinnamaldehyde in human hepatoma PLC/PRF/5 cells. 2. Using the XTT assay, cinnamaldehyde exhibited a powerful antiproliferative effect on PLC/PRF/5 cells. Apoptosis was elicited when cells were treated with 1 micromol/L cinnamaldehyde, as characterized by the appearance of phosphatidylserine on the outer surface of the plasma membrane. 3. The apoptotic effect induced by cinnamaldehyde could be further supported by the release of cytochrome c, Smac/Diablo and Omi/HtrA2 from mitochondria to the cytosol and activation of caspase 3. Cinnamaldehyde also upregulated the expression of pro-apoptotic protein (Bax) and down-regulated the levels of anti-apoptotic proteins, such as Bcl-2 and the inhibitor of apoptosis protein family (X-linked inhibitor of apoptosis protein (XIAP), cellular inhibitor of apoptosis protein (cIAP)-1 and cIAP-2). 4. Cinnamaldehyde induces the generation of reactive oxygen species (ROS) in cells. Following the pre-incubation of PLC/PRF/5 cells with anti-oxidants, it was found that 100 micromol/L vitamin E significantly diminished the effect of cinnamaldehyde-induced apoptosis, whereas a lesser effect was seen with on 100 micromol/L N-acetyl-L-cysteine. Vitamin E effectively blocked the release of cytochrome c, Smac/Diablo and Omi/HtrA2 from mitochondria to the cytosol in cells treated with cinnamaldehyde. Vitamin E also markedly suppressed caspase 3 activation. The expression of apoptotic inhibitors (XIAP, cIAP-1, cIAP-2) and anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) proteins was affected by vitamin E pretreatment. 5. Taken together, the results suggest that cinnamaldehyde triggers apoptosis possibly through the mitochondrial pathway. Pretreatment with vitamin E markedly prevented cinnamaldehyde-mediated apoptosis, which was associated with the modulation of XIAP, cIAP-1, cIAP-2, Bcl-2 and Bax protein activity.

Distinct gene signatures of transient and acute megakaryoblastic leukemia in Down syndrome

Approximately 10% of newborns with Down syndrome develop Transient Leukemia (TL), a disorder that is unique to infants with constitutional trisomy 21 (or trisomy 21 mosaicism). TL blasts disappear spontaneously within the first 3 months of life in the majority of cases. Despite the resolution of TL, 20-30% of these newborns will go on to develop acute megakaryoblastic leukemia (AMKL) later in life. In this study, samples from both TL and AMKL patients were examined using cDNA microarrays to study the pathogenic progression from TL to AMKL. TL and AMKL samples partition separately by cluster analysis, and AMKL samples had substantial increases in apolipoprotein C-I, transporter 1, myosin alkali light chain 4, and spermidine/spermine N-acetyltransferase, compared to TL samples. Although these findings will require validation in an independent series of TL and AMKL samples, they indicate that TL and AMKL have distinct gene signatures, and provide a basis for studies of the different mechanisms underlying either the resolution of TL or its progression to AMKL.

Activated polyamine catabolism depletes acetyl-CoA pools and suppresses prostate tumor growth in TRAMP mice

The enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) regulates the catabolism and export of intracellular polyamines. We have previously shown that activation of polyamine catabolism by conditional overexpression of SSAT has antiproliferative consequences in LNCaP prostate carcinoma cells. Growth inhibition was causally linked to high metabolic flux arising from a compensatory increase in polyamine biosynthesis. Here we examined the in vivo consequences of SSAT overexpression in a mouse model genetically predisposed to develop prostate cancer. TRAMP (transgenic adenocarcinoma of mouse prostate) female C57BL/6 mice carrying the SV40 early genes (T/t antigens) under an androgen-driven probasin promoter were cross-bred with male C57BL/6 transgenic mice that systemically overexpress SSAT. At 30 weeks of age, the average genitourinary tract weights of TRAMP mice were approximately 4 times greater than those of TRAMP/SSAT bigenic mice, and by 36 weeks, they were approximately 12 times greater indicating sustained suppression of tumor outgrowth. Tumor progression was also affected as indicated by a reduction in the prostate histopathological scores. By immunohistochemistry, SV40 large T antigen expression in the prostate epithelium was the same in TRAMP and TRAMP/SSAT mice. Consistent with the 18-fold increase in SSAT activity in the TRAMP/SSAT bigenic mice, prostatic N(1)-acetylspermidine and putrescine pools were remarkably increased relative to TRAMP mice, while spermidine and spermine pools were minimally decreased due to a compensatory 5-7-fold increase in biosynthetic enzymes activities. The latter led to heightened metabolic flux through the polyamine pathway and an associated approximately 70% reduction in the SSAT cofactor acetyl-CoA and a approximately 40% reduction in the polyamine aminopropyl donor S-adenosylmethionine in TRAMP/SSAT compared with TRAMP prostatic tissue. In addition to elucidating the antiproliferative and metabolic consequences of SSAT overexpression in a prostate cancer model, these findings provide genetic support for the discovery and development of specific small molecule inducers of SSAT as a novel therapeutic strategy targeting prostate cancer.

Metabolic and antiproliferative consequences of activated polyamine catabolism in LNCaP prostate carcinoma cells

Depletion of intracellular polyamine pools invariably inhibits cell growth. Although this is usually accomplished by inhibiting polyamine biosynthesis, we reasoned that this might be more effectively achieved by activation of polyamine catabolism at the level of spermidine/spermine N(1)-acetyltransferase (SSAT); a strategy first validated in MCF-7 breast carcinoma cells. We now examine the possibility that, due to unique aspects of polyamine homeostasis in the prostate gland, tumor cells derived from it may be particularly sensitive to activated polyamine catabolism. Thus, SSAT was conditionally overexpressed in LNCaP prostate carcinoma cells via a tetracycline-regulatable (Tet-off) system. Tetracycline removal resulted in a rapid approximately 10-fold increase in SSAT mRNA and an increase of approximately 20-fold in enzyme activity. SSAT products N(1)-acetylspermidine, N(1)-acetylspermine, and N(1),N(12)-diacetylspermine accumulated intracellularly and extracellularly. SSAT induction also led to a growth inhibition that was not accompanied by polyamine pool depletion as it was in MCF-7 cells. Rather, intracellular spermidine and spermine pools were maintained at or above control levels by a robust compensatory increase in ornithine decarboxylase and S-adenosylmethionine decarboxylase activities. This, in turn, gave rise to a high rate of metabolic flux through both the biosynthetic and catabolic arms of polyamine metabolism. Treatment with the biosynthesis inhibitor alpha-difluoromethylornithine during tetracycline removal interrupted flux and prevented growth inhibition. Thus, flux-induced growth inhibition appears to derive from overaccumulation of metabolic products and/or from depletion of metabolic precursors. Metabolic effects that were not excluded as possible contributing factors include high levels of putrescine and acetylated polyamines, a 50% reduction in S-adenosylmethionine, and a 45% decline in the SSAT cofactor acetyl-CoA. Overall, the study demonstrates that activation of polyamine catabolism in LNCaP cells elicits a compensatory increase in polyamine biosynthesis and downstream metabolic events that culminate in growth inhibition.

TATA-binding protein-associated factor 7 regulates polyamine transport activity and polyamine analog-induced apoptosis

Identification of the polyamine transporter gene will be useful for modulating polyamine accumulation in cells and should be a good target for controlling cell proliferation. Polyamine transport activity in mammalian cells is critical for accumulation of the polyamine analog methylglyoxal bis(guanylhydrazone) (MGBG) that induces apoptosis, although a gene responsible for transport activity has not been identified. Using a retroviral gene trap screen, we generated MGBG-resistant Chinese hamster ovary (CHO) cells to identify genes involved in polyamine transport activity. One gene identified by the method encodes TATA-binding protein-associated factor 7 (TAF7), which functions not only as one of the TAFs, but also a coactivator for c-Jun. TAF7-deficient cells had decreased capacity for polyamine uptake (20% of CHO cells), decreased AP-1 activation, as well as resistance to MGBG-induced apoptosis. Stable expression of TAF7 in TAF7-deficient cells restored transport activity (55% of CHO cells), AP-1 gene transactivation (100% of CHO cells), and sensitivity to MGBG-induced apoptosis. Overexpression of TAF7 in CHO cells did not increase transport activity, suggesting that TAF7 may be involved in the maintenance of basal activity. c-Jun NH2-terminal kinase inhibitors blocked MGBG-induced apoptosis without alteration of polyamine transport. Decreased TAF7 expression, by RNA interference, in androgen-independent human prostate cancer LN-CaP104-R1 cells resulted in lower polyamine transport activity (25% of control) and resistance to MGBG-induced growth arrest. Taken together, these results reveal a physiological function of TAF7 as a basal regulator for mammalian polyamine transport activity and MGBG-induced apoptosis.

The melanoma inhibitor of apoptosis protein: a target for spontaneous cytotoxic T cell responses

The identification of tumor antigens which expression is essential for the survival of tumor cells is a new avenue to prevent antigen loss variants emerging due to immunoselection, particularly during immune therapy. The melanoma inhibitor of apoptosis protein, ML-IAP (also named livin) counteracts apoptosis induced by death receptors, hypooxgenic conditions, or chemotherapeutic agents. Thus, elevated expression of ML-IAP renders melanoma cells resistant to apoptotic stimuli and thereby potentially contributes to the oncogenic phenotype. Here, we demonstrate that T cells in a large proportion of melanoma patients infiltrating the tumor or circulating in the peripheral blood specifically recognize ML-IAP-derived peptides. Interestingly, the responses against the peptide epitope ML-IAP280-289 were not restricted to melanoma patients but present among peripheral blood T cells in a few healthy controls. In situ peptide/HLA-A2 multimer staining, however, confirmed the infiltration of ML-IAP-reactive cells into the tumor microenvironment. Moreover, ML-IAP-reactive T cells isolated by magnetic beads coated with peptide/HLA-A2 complexes were cytotoxic against HLA-matched melanoma cells. In conclusion, out data strongly indicate ML-IAP as a suitable target for immunologic intervention.

Small Interfering RNA Suppression of Polyamine Analog-Induced Spermidine/SpermineN1-Acetyltransferase

N1,N11-diethylnorspermine (DENSPM) is a polyamine analog that down-regulates polyamine biosynthesis and potently upregulates the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase (SSAT). In certain cells, such as SKMEL-28 human melanoma cells, induction of SSAT is associated with rapid apoptosis. In this study, we used small interfering RNA (siRNA) to examine the role of SSAT induction in mediating polyamine pool depletion and apoptosis. siRNA duplexes were designed to target three independent sites in the SSAT mRNA coding region (siSSAT). When transfected under nontoxic conditions, two of the duplexes selectively reduced basal SSAT mRNA in HEK-293 cells by >80% and prevented DENSPM-induced SSAT mRNA by 95% in SK-MEL-28 cells. Treatment of SK-MEL-28 cells with 10 muM DENSPM in the presence of 83 nM siSSAT selectively prevented the 1400-fold induction of SSAT activity by approximately 90% and, in turn, prevented analog depletion of spermine (Spm) pools by approximately 35%. siSSAT also prevented DENSPM-induced cytochrome c release and caspase-3 cleavage at 36 h and apoptosis at 48 h as measured by annexin V staining. Overall, the data directly link analog induction of SSAT to Spm pool depletion and to caspase-dependent apoptosis in DENSPM-treated SK-MEL-28 cells. This represents the first use of siRNA technology directed toward a polyamine gene and the first unequivocal demonstration that SSAT induction initiates events leading to polyamine analog-induced apoptosis.