Relationship of Ornithine Decarboxylase activity and histological findings in human hepatocellular carcinoma

Increased hepatic putrescine levels as a new potential factor related to the progression of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a chronic liver condition that often progresses to more advanced stages, such as metabolic dysfunction-associated steatohepatitis (MASH). MASH is characterized by inflammation and hepatocellular ballooning, in addition to hepatic steatosis. Despite the relatively high incidence of MASH in the population and its potential detrimental effects on human health, this liver disease is still not fully understood from a pathophysiological perspective. Deregulation of polyamine levels has been detected in various pathological conditions, including neurodegenerative diseases, inflammation, and cancer. However, the role of the polyamine pathway in chronic liver disorders such as MASLD has not been explored. In this study, we measured the expression of liver ornithine decarboxylase (ODC1), the rate-limiting enzyme responsible for the production of putrescine, and the hepatic levels of putrescine, in a preclinical model of MASH as well as in liver biopsies of patients with obesity undergoing bariatric surgery. Our findings reveal that expression of ODC1 and the levels of putrescine, but not spermidine nor spermine, are elevated in hepatic tissue of both diet-induced MASH mice and patients with biopsy-proven MASH compared with control mice and patients without MASH, respectively. Furthermore, we found that the levels of putrescine were positively associated with higher aspartate aminotransferase concentrations in serum and an increased SAF score (steatosis, activity, fibrosis). Additionally, in in vitro assays using human HepG2 cells, we demonstrate that elevated levels of putrescine exacerbate the cellular response to palmitic acid, leading to decreased cell viability and increased release of CK-18. Our results support an association between the expression of ODC1 and the progression of MASLD, which could have translational relevance in understanding the onset of this disease. © 2024 The Pathological Society of Great Britain and Ireland.

Urinary biomarkers for hepatocellular carcinoma: current knowledge for clinicians

Hepatocellular carcinoma (HCC) is the most predominant primary liver cancer, causing many illnesses and deaths worldwide. The insidious clinical presentation, difficulty in early diagnosis, and the highly malignant nature make the prognosis of HCC extremely poor. The complex and heterogeneous pathogenesis of HCC poses significant challenges to developing therapies. Urine-based biomarkers for HCC, including diagnostic, prognostic, and monitoring markers, may be valuable supplements to current tools such as serum α-fetoprotein (AFP) and seem promising for progress in precision medicine. Herein, we reviewed the major urinary biomarkers for HCC and assessed their potential for clinical application. Molecular types, testing platforms, and methods for building multimolecule models in the included studies have shown great diversity, thus providing abundant novel tools for future clinical transformation and applications.

Urinary Excretion of Free and Acetylated Polyamines in Hepatocellular Carcinoma

Polyamines (putrescine, spermidine and spermine) are essential for the proliferation of normal and neoplastic cells, and have been repeatedly recommended as tumor markers, with contrasting and elusive results.

In the present study the urinary excretion of free and acetylated polyamines was measured in patients with hepatocellular carcinoma (HCC), cirrhotics and control subjects.

Separation and quantification of dansyl-derivatives of free, acetylated and total polyamines was performed by reverse-phase high-performance liquid chromatography.

The results show that the urinary excretion of total, free, and acetylated polyamines is significantly higher in HCC patients than in cirrhotics and controls (p<0.001). The N1/N8 acetyl-spermidine molar ratio was found to be higher in HCC patients than in cirrhotics and controls (p<0.001). No correlation was found between urinary excretion of polyamines and serum alpha-fetoprotein, tumor size and severity of liver cirrhosis. The results show that increased urinary excretion of free and acetylated polyamines, as well as an altered N1/N8-acetyl-spermidine molar ratio, is a sensible but not specific feature of HCC patients; polyamines may play a role in human carcinogenesis, but their determination does not seem reliable for the early detection of liver cancer.

Phase 1 study of N(1),N(11)‑diethylnorspermine (DENSPM) in patients with advanced hepatocellular carcinoma

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.

Polyamine and methionine adenosyltransferase 2A crosstalk in human colon and liver cancer

Methionine adenosyltransferase (MAT) is an essential enzyme that is responsible for the biosynthesis of S-adenosylmethionine (SAMe), the principal methyl donor and precursor of polyamines. MAT1A is expressed in normal liver and MAT2A is expressed in all extrahepatic tissues. MAT2A expression is increased in human colon cancer and in colon cancer cells treated with mitogens, whereas silencing MAT2A resulted in apoptosis. The aim of the current work was to examine the mechanism responsible for MAT2A-dependent growth and apoptosis. We found that in RKO (human adenocarcinoma cell line) cells, MAT2A siRNA treatment lowered cellular SAMe and putrescine levels by 70-75%, increased apoptosis and inhibited growth. Putrescine supplementation blunted significantly MAT2A siRNA-induced apoptosis and growth suppression. Putrescine treatment (100pmol/L) raised MAT2A mRNA level to 4.3-fold of control, increased the expression of c-Jun and c-Fos and binding to an AP-1 site in the human MAT2A promoter and the promoter activity. In human colon cancer specimens, the expression levels of MAT2A, ornithine decarboxylase (ODC), c-Jun and c-Fos are all elevated as compared to adjacent non-tumorous tissues. Overexpression of ODC in RKO cells also raised MAT2A mRNA level and MAT2A promoter activity. ODC and MAT2A are also overexpressed in liver cancer and consistently, similar MAT2A-ODC-putrescine interactions and effects on growth and apoptosis were observed in HepG2 cells. In conclusion, there is a crosstalk between polyamines and MAT2A. Increased MAT2A expression provides more SAMe for polyamines biosynthesis; increased polyamine (putrescine in this case) can activate MAT2A at the transcriptional level. This along with increased ODC expression in cancer all feed forward to further enhance the proliferative capacity of the cancer cell.

Thymosin beta4 is a determinant of the transformed phenotype and invasiveness of S-adenosylmethionine decarboxylase-transfected fibroblasts

S-adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in the synthesis of polyamines essential for cell growth and proliferation. Its overexpression induces the transformation of murine fibroblasts in both sense and antisense orientations, yielding highly invasive tumors in nude mice. These cell lines hence provide a good model to study cell invasion. Here, the gene expression profiles of these cells were compared with their normal counterpart by microarray analyses (Incyte Genomics, Palo Alto, CA, and Affymetrix, Santa Clara, CA). Up-regulation of the actin sequestering molecule thymosin beta4 was the most prominent change in both cell lines. Tetracycline-inducible expression of thymosin beta4 antisense RNA caused a partial reversal of the transformed phenotype. Further, reversal of transformation by dominant-negative mutant of c-Jun (TAM67) caused reduction in thymosin beta4 mRNA. Interestingly, a sponge toxin, latrunculin A, which inhibits the binding of thymosin beta4 to actin, was found to profoundly affect the morphology and proliferation of the AdoMetDC transformants and to block their invasion in three-dimensional Matrigel. Thus, thymosin beta4 is a determinant of AdoMetDC-induced transformed phenotype and invasiveness. Up-regulation of thymosin beta4 was also found in ras-transformed fibroblasts and metastatic human melanoma cells. These data encourage testing latrunculin A-like and other agents interfering with thymosin beta4 for treatment of thymosin beta4-overexpressing tumors with high invasive and metastatic potential.

Methylthioadenosine phosphorylase gene expression is impaired in human liver cirrhosis and hepatocarcinoma

Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine and adenine salvage pathways. In mammals, the liver plays a central role in methionine metabolism, and this essential function is lost in the progression from liver cirrhosis to hepatocarcinoma. Deficient MTAP gene expression has been recognized in many transformed cell lines and tissues. In the present work, we have studied the expression of MTAP in human and experimental liver cirrhosis and hepatocarcinoma. We observe that MTAP gene expression is significantly reduced in human hepatocarcinoma tissues and cell lines. Interestingly, MTAP gene expression was also impaired in the liver of CCl4-cirrhotic rats and cirrhotic patients. We provide evidence indicating that epigenetic mechanisms, involving DNA methylation and histone deacetylation, may play a role in the silencing of MTAP gene expression in hepatocarcinoma. Given the recently proposed tumor suppressor activity of MTAP, our observations can be relevant to the elucidation of the molecular mechanisms of multistep hepatocarcinogenesis.

Do altering in ornithine decarboxylase activity and gene expression contribute to antiproliferative properties of COX inhibitors?

Two isoforms of cyclooxygenase (COX) participate in growth control; COX-1 is constitutively expressed in most cells, and COX-2 is an inducible enzyme in response to cellular stimuli. An induction of COX-2 found in neoplastic tissues results in increased cell growth, inhibition of apoptosis, activation of angiogenesis, and decreased immune responsiveness. Although both COX-1 and COX-2 inhibitors are suppressors of cell proliferation and appear to be chemopreventive agents for tumorigenesis, the molecular mechanisms mediating antiproliferative effect of COX inhibitors are still not well defined. This study contrasts and compares the effects of aspirin and celecoxib, inhibitors of COX-1 and COX-2, in rat hepatoma HTC-IR cells. The following were assessed: cell proliferation and apoptosis, ornithine decarboxylase (ODC) activity, and pattern expression of three immediate-early genes, c-myc, Egr-1, and c-fos. We have shown that the treatment of hepatocytes in vitro with the selective COX-2 inhibitor, celecoxib, was associated with induction of apoptosis and complete inhibition of cellular proliferation. Aspirin exhibited a small antiproliferative effect that was not associated with apoptosis. Treatment with celecoxib produced dose- and time-dependent decrease in ODC activity. In addition, at higher drug concentration the decrease in ODC activity was greater in proliferating than in resting cells. Much lesser inhibitory effect on ODC activity was observed in aspirin-treated cells. The two COX inhibitors did not change c-myc expression, significantly decreased the expression of Egr-1, and differentially altered expression of c-fos; aspirin did not change, but celecoxib dramatically decreased the levels of c-fos-mRNA. Our study revealed that celecoxib and aspirin share the ability to inhibit ODC activity and alter the pattern of immediate-early gene expression. It seems that some of the observed effects are likely to be related to COX-independent pathways. The precise mechanisms of action of COX inhibitors should be defined before using these drugs for cancer chemopreventive therapy.

Analysis of polyamines as markers of (patho)physiological conditions

The aliphatic polyamines, putrescine, spermidine and spermine, are normal cell constituents that play important roles in cell proliferation and differentiation. The equilibrium between cellular uptake and release and the balanced activities of biosynthetic and catabolic enzymes of polyamines are essential for normal homeostasis in the proliferation and functions of cells and tissues. However, the intracellular polyamine content increases in hyperplastic or neoplastic growth. Although the involvement of polyamines in physiological and pathological cell proliferation and differentiation has been well established, the role they play is quite different in relation to cell systems and animal models and is dependent on inducer agents and stimuli. Also, the experimental procedures used to deplete polyamines have been shown to influence the cell responses. In this paper, the assay methods currently in use for polyamines are reviewed and compared with respect to sensitivity, reproducibility and applicability to routine analysis. The relevance of polyamine metabolism and the uptake/release process in many physiological and pathological processes is highlighted, and the cellular polyamine pathways are discussed in relation to the possible diagnostic and therapeutic significance of these mediators.

High molecular protein of Helicobacter pylori responsible for inhibition of ornithine decarboxylase activity of human gastric cultured cells

BACKGROUND

Ornithine decarboxylase (ODC), a rate-limiting enzyme of polyamine biosynthesis, mediates epithelial cell proliferation and plays a critical role in the optimal repair of gastric mucosal damage. Several studies have shown that Helicobacter pylori inhibits the growth and proliferation of gastric cells in vitro.

AIM

To test whether H. pylori extract affects ODC mRNA expression and its enzyme activity in gastric cells and to examine the partial characterization of the molecule responsible for this effect.

METHODS

Human gastric cells (MKN-45) were used. Bacterial extracts from various E. coli or H. pylori strains, namely (1) cagA+, vacA+, CagA+, VacA+; (2) cagA+, vacA+, CagA+ VacA-; or (3) cagA-, vacA+, CagA-, VacA- were added to the cells. Cell proliferation was assessed by [3H]-thymidine incorporation, viability by MTT assay and LDH release test, ODC enzyme activity by 14CO2 counts from L-[1(14)C]ornithine, and ODC mRNA by Northern blotting.

RESULTS

H. pylori and E. coli extract did not affect viability of gastric cells. H. pylori extract, especially extracts containing a protein greater than 50 kDa, significantly inhibited proliferation and ODC activity of gastric cells while E. coli extract had no effect. Inhibition of ODC activity was found in extracts of all H. pylori strains, irrespective of CagA and VacA protein expression. Serum stimulation induces an increase in ODC mRNA while H. pylori extract did not affect ODC mRNA expression.

CONCLUSION

High molecular weight (greater than 50 kDa) proteins of H. pylori extract without CagA or VacA protein inhibited proliferation and ODC activity of human gastric cells, but did not affect ODC mRNA expression, suggesting that inhibition of ODC activity is regulated at the post-transcriptional level.

Induction of epithelial differentiation and DNA demethylation in hamster malignant oral keratinocyte by ornithine decarboxylase antizyme

The hamster ornithine decarboxylase antizyme (ODC-Az) cDNA was transfected into the hamster malignant oral keratinocyte cell line, HCPC-1. Ectopic expression of ODC-Az resulted in the reversion of malignant phenotypes and alteration of DNA methylation status of CCGG sites. The phenotypes examined include ODC enzymatic activity, doubling time, morphological change, anchorage dependent growth, tumorigenicity in nude mice, induction of epithelial differentiation marker protein (involucrin), and change of cell cycle position. Comparison of CCGG DNA methylation status of the ODC-Az and control vector transfectants revealed a significant increase in demethylation of 5-methyl cytosines (m5C) of CCGG sites in the ODC-Az transfectants. Ectopic expression of ODC-Az gene in hamster malignant oral keratinocytes led to reduce ODC activity and the subsequent demethylation of 5-methyl cytosines, presumably via the ODC/ polyamines/ decarboxylated S-adenosylmethionine (dc-AdoMet) pathways. Our data suggest that ODC-Az shared the same pathway of polyamines/ dc-AdoMet/DNA methyltransferase (DNA MTase). We propose that ODC-Az mediates a novel mechanism in tumor suppression by DNA demethylation and presumably re-activation of key cellular genes silenced by DNA hypermethylation during cancer development. Oncogene (2001) 20, 24 - 33.

Regulation of spermidine/spermine N1-acetyltransferase expression by cytokines and polyamines in human hepatocarcinoma cells (HepG2)

Spermidine/spermine N1-acetyltransferase (cSAT), a key enzyme in polyamine degradation, is induced by various hepatotoxins and liver tumor promoters. In this paper we demonstrate that physiological factors, such as cytokines, control cSAT expression in HepG2 human hepatocarcinoma cells. Hepatocyte growth factor (HGF) induced the cSAT mRNA precursor (3.5 kb) at 4 h. The mature form of mRNA (1.3 kb) increased 6-8-fold between 8 and 10 h, and remained elevated until 18 h. An increase in cSAT activity (2-fold) and high levels of N1-acetylspermidine were observed concomitantly. Interleukin-1 beta (IL-1 beta) enhanced cSAT expression (both mRNA and enzyme activity) similar to HGF, while tumor necrosis factor-alpha (TNF-alpha) was less effective. This system also provides a useful means for examining the involvement of negative and positive changes of polyamines in the induction of cSAT and c-jun, a gene that participates in the control of cSAT expression. alpha-Difluoromethylornithine (DFMO) pretreatment, by lowering putrescine and spermidine in HGF- or IL-1 beta-treated cells, prevented the induction of cSAT. This effect was reversed by exogenous putrescine or spermidine. IL-1 beta induced c-jun mRNA more than HGF. DFMO prevented almost completely the enhancement of c-jun mRNA expression by IL-1 beta, and this effect was reversed by exogenous putrescine or spermidine. Therefore, we suggest that cSAT and c-jun expression is specifically regulated by polyamine-mediated mechanisms in IL-1 beta treated HepG2 cells. Since cSAT is inducibile by cytokines that control tumor metabolism and growth as well as tumor-host interaction, we hypothesize an involvement of cSAT in hepatoma growth.

Inhibition of the rat adrenal ornithine decarboxylase activity by immobilization stress and/or dexamethasone

The effects of immobilization stress and/or dexamethasone (DEX) on the adrenal ornithine decarboxylase (ODC) activities of sham-operated and adrenal-medulloectomized (enucleated) male Sprague-Dawley rats were investigated. On day 11 after surgery, rats were injected with saline or DEX (1 mg/kg), 3 h before the time of sacrifice (0600 h or 1800 h). Four groups, from sham-operated and enucleated rats (ENU) treated with saline or DEX were subjected to immobilization stress for 1 h prior to sacrifice. Groups of rats from stress-sham-DEX, non stress-sham-DEX, stress-sham, non stress-sham, stress-ENU-DEX, non stress-ENU-DEX, stress-ENU, and non stress-ENU were sacrificed at 0600 h or 1800 h on day 11 after surgery. Adrenal glands were excised and later analyzed for ODC activities. Results indicated that DEX and/or immobilization stress inhibited ODC activities (p<0.05) in normal and regenerating adrenal glands at 1800 h and ODC activity varies diurnally, the activity being greater at 1800 h than at 0600 hours (p<0.001).