Effects of thymoquinone and the curcumin analog EF-24 on the activity of the enzyme paraoxonase-1 in human glioblastoma cells U87MG.

The spices and aromatic herbs were used not only in cooking to add flavour and smell to dishes but also for medicinal use. Nigella sativa, also called black cumin, is one of the species that contains an important bioactive component, thymoquinone (TQ), which has antioxidant, anti-inflammatory, antimicrobial, and antidiabetic effects. Curcuma longa, which also includes curcumin, has numerous anti-cancer properties. However, the bioavailability of curcumin is lower than that of its analogs. An analog of curcumin (EF-24), which has better bioavailability than curcumin, is capable of exerting a high anti-cancer effect. In our study, we determined the effects of PON1 enzyme activity on the proliferation and aggressiveness of glioblastoma cancer treated with TQ and EF-24 from lysates of the glioblastoma cell line U87MG. The results were determined as increased PON1 activity after treatment with TQ and EF-24 in the U87MG cell line (p < 0.0001).

The inhibitory effect of boric acid on hypoxia-regulated tumour-associated carbonic anhydrase IX.

Carbonic anhydrases (EC 4.2.1.1) catalyse the reversible hydration of CO2 into bicarbonate and protons. As a hypoxia-sensitive and tumour-associated isoform, isoform CA IX, is significantly overexpressed in various malignancies, being a validated target for new anticancer/antimetastatic drugs. A multitude of studies has shown that CA IX inhibition decreases cancer cell proliferation and metastasis through pHe/pHi modulation and enhancement of ferroptosis among others. Numerous studies demonstrated increased efficacy of cytotoxic drugs combined with CA inhibitors (CAIs) in various cancer types. We tested the inhibitory effect of boric acid (BA), an inorganic Lewis acid, on CA IX as well as other isoforms (CA I, II, and XII). BA acted as a millimolar in vitro CAI, decreased proliferation of two cancer cell lines, although not strong correlations between the in vitro inhibition and in vivo effects were observed. The mechanism of antiproliferative action of BA should be investigated in more detail.

Do CO2 and oxidative stress induce cancer?: a brief study about the evaluation of PON 1, CAT, CA and XO enzyme levels on head and neck cancer patients.

Head and neck cancer (HNC) is one of the most common malignancies in the world. HNC is a group of cancers that starts in the mouth, nose, throat, larynx, sinuses, or salivary glands. According to this section of the body parts; induction of cancer can be associated with CO2 and oxidative stress. The aim of this study is to assess the activities of carbonic anhydrase (CA), catalase (CAT), paraoxonase1 (PON1), and xanthine oxidase (XO) activities in 89 HNC patients and 115 healthy volunteers. Paraoxonase1 activity was found lower in HNC cancer patients. There is no statistically significant difference between patients and controls for catalase, carbonic anhydrase, and xanthine oxidase enzyme levels. According to this results, paraoxonase1 levels could be a candidate as an oxidative marker in HNC patients, but further studies are needed to investigate the other type of cancer related PON1 and the other enzyme levels.

Differentially expressed genes related to lymph node metastasis in advanced laryngeal squamous cell cancers.

Understanding the molecular mechanisms and gene expression in laryngeal squamous cell carcinoma (LSCC) may explain its aggressive biological behavior and regional metastasis pathways. In the present study, patients with locally advanced LSCC tumors were examined for differential gene expression in the normal mucosa (non-tumoral mucosa), tumors and lymph node tissues. The aim was to identify possible predictive genes for lymph node metastasis. A total of 16 patients who had undergone total laryngectomy with neck dissection for advanced LSCC were randomly selected from a hospital database: Eight of the patients had lymph node metastasis (Group 1) and the other eight patients did not have metastasis (Group 2). Overall survival (OS), disease-free survival (DFS) and disease-specific survival (DSS) were analyzed. For each patient, paraffin-embedded tissue samples were collected from non-tumoral mucosa, tumoral lesions and lymph node tissues. RNA was extracted from the tissue samples and used for complementary DNA synthesis, and microarray analysis was subsequently performed on each sample. Gene expression levels were determined in each specimen, and Groups 1 and 2 were compared and statistically analyzed. The microarray results for lymph node metastasis-positive and -negative groups, indicated the differential expression of 312 genes in the lymph nodes, 691 genes in the normal mucosal tissue and 93 genes in the tumor tissue. Transgelin (TAGLN) and cofilin 1 (CFL1) were identified as possible target genes and validated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The RT-qPCR results for TAGLN and CFL1 supported the microarray data. OS, DFS and DSS times were longer in Group 2 than in Group 1 (P=0.002, 0.015 and 0.009, respectively). In addition, TAGLN and CFL1 were associated with DFS and DSS. On the basis of these results, it is suggested that TAGLN and CFL1 expression may play an important role in the pathogenesis of regional metastasis and poor prognosis in advanced LSCC.

alpha-Glucosidase inhibitors have a prolonged antiviral effect against hepatitis B virus through the sustained inhibition of the large and middle envelope glycoproteins.

Previous work has shown that the secretion of enveloped hepatitis B virus (HBV) DNA and the HBV middle envelope protein (MHBs) are sensitive to glucosidase inhibition. Here, it is shown that HBV DNA secretion remains depressed after the removal of the glucosidase inhibitor and long after glucosidase function returns to normal. For example, glyco-processing and the secretion of alpha-1 anti-trypsin returned to normal within 3 h of the removal of the glucosidase inhibitor. In contrast, the secretion of HBV did not return to normal for more than 7 days after the removal of the inhibitor. Consistent with the inhibition of HBV virion secretion, the levels of HBV L and HBV M proteins were also reduced by treatment with the glucosidase inhibitor and remained reduced for 7 days after compound withdrawal. The implications of the prolonged antiviral effect against HBV and the use of glucosidase inhibitors as antiviral agents are discussed.

Imino sugars that are less toxic but more potent as antivirals, in vitro, compared with N-n-nonyl DNJ.

Imino sugar glucosidase inhibitors have selective antiviral activity against certain enveloped, mammalian viruses. Deoxynojirimycins (DNJs) modified by N-alkylation to contain a nine carbon atom side chain (N-n-nonyl-deoxynojirimycin; N-nonyl-DNJ, NN-DNJ) were shown to be, for example, at least 20 times more potent in inhibiting hepatitis B virus (HBV) and bovine viral diarrhoea virus (BVDV) in cell based assays than the non-alkylated DNJ. These data suggested that modification of the alkyl side chain could influence antiviral activity. Previous work has focused on varying side chain length. In this report, the influence of side chain branching and cyclization upon toxicity and antiviral activity was explored. Briefly, using a virus secretion assay for HBV and a single step growth (yield reduction) assay for BVDV, 14 different DNJ-based sugars, possessing various N-alkyl substitutions, were tested for antiviral activity. Of the series, N-methoxy-nonyl-DNJ and N-butyl-cyclohexyl DNJ were determined to have the best selectivity index against BVDV and HBV, with the N-methoxy analogue being the most potent with micromolar antiviral activity. The results of this antiviral survey and the implications for the mechanism of action and ultimate therapeutic potential of the DNJ-based imino sugars is provided and discussed.

Inhibition of cellular alpha-glucosidases results in increased presentation of hepatitis B virus glycoprotein-derived peptides by MHC class I.

Inhibitors of alpha glucosidases prevent the trimming of oligosaccharides on certain nascent glycoproteins, including the hepatitis B virus MHBs envelope glycoprotein. MHBs proteins with untrimmed oligosaccharides do not interact with calnexin, increasing protein misfolding and subsequent degradation by proteasomes. As peptides loaded onto newly synthesized MHC class I complexes are predominantly derived from proteasomes, the possibility that glucosidase inhibition could increase presentation by MHC class I was determined. Using either a model epitope, or a natural MHBs epitope, it was demonstrated that glucosidase inhibitors enhanced presentation by MHC class I and promoted activation of antigen-specific CTLs, suggesting a pharmacologic approach to immune modulation.

The degradation pathway for the HBV envelope proteins involves proteolysis prior to degradation via the cytosolic proteasome.

To study the pathway of degradation of the hepatitis B virus (HBV) middle envelope protein (M), human hepatoblastoma cells were transfected with a plasmid that specifies production of M in the absence of other viral proteins. When expressed in HepG2 cells, 90% of M protein was secreted into the culture media within a 24-h period. However, quite surprisingly, 10% of this protein remained cell associated and was only slowly degraded over a 24-48-h period. Treatment with inhibitors of the cytosolic proteasome complex resulted in the accumulation of full-length HBV M protein and M derived HBV-specific polypeptides of 20 and 17 kDa. Treatment with the endoglycosidases PNGase F and Endo H, confirmed that the two species were derived from a similar polypeptide with a N-linked glycan modification. Evidence that this peptide was derived from a proteolytic processing event was determined through the detection of the C-terminal fragment using a C-terminal tagged HA tagged construct. The hypothesis that the 20 and 17 kDa polypeptide species are intermediates of M degradation was reinforced by their detection in cells transfected with vectors specifying M secretion defective mutants that accumulate intracellular M. Moreover, deletion of a putative cleavage sites prevented the detection of the 20 and 17 kDa species, consistent with the notion that they are generated by the action of a cellular protease prior to proteasomal degradation. Thus, these results highlight an important way in which large protein aggregates, such as the HBsAg can be processed for efficient degradation via the proteasomes and allow for proper antigen presentation via the MHC I pathway.

The role of the downstream signal sequences in the maturation of the HBV middle surface glycoprotein: development of a novel therapeutic vaccine candidate.

The signal sequences that mediate entry of the hepatitis B virus (HBV) envelope proteins into the endoplasmic reticulum (ER) are located within the S domain at positions 11-32 and at positions 80-98 (from the start of the S domain). In addition, hydrophobic patches at positions 160-184 and 189-210 of the S domain may also be involved in entry into the ER. The role of each of these domains in the entry of the HBV M glycoprotein into the ER was studied by deletion mutations of each of the signal sequences. Glycosylation of proteins was used as a marker of entry into the ER. Our results indicate that association with the ER could not be prevented by the deletion of either individual or combinations of the HBV signal sequences. M protein lacking signal sequence I was able to enter the ER and had limited secretion. In contrast, M protein lacking signal sequence II could not be secreted but still entered the ER. M protein lacking signal sequences I and II, while still associated with the ER, was rapidly degraded by the cytosolic proteasome. The potential use of such a vector as a CTL vaccine was tested through an in vitro antigen presentation assay. In this assay, a DNA vaccine candidate lacking signal sequences I and II lead to a >6-fold increase in CTL activation, as compared to the vector expressing wild type M protein. These results suggest that increased degradation of the HBV envelope proteins can lead to enhanced antigen presentation.

A substituted tetrahydro-tetrazolo-pyrimidine is a specific and novel inhibitor of hepatitis B virus surface antigen secretion.

The high levels of hepatitis B virus (HBV) surface antigen (HBsAg)-bearing subviral particles in the serum of chronically infected individuals are thought to play a role in suppressing the HBV-specific immune response. Current therapeutics are not directed at reducing this viral antigenemia; thus, our group has focused on identifying inhibitors of HBsAg secretion. By using the HBV-expressing cell line HepG2.2.15, high-throughput screening of an 80,288-compound synthetic small-molecule library identified HBF-0259, an aromatically substituted tetrahydro-tetrazolo-(1, 5-a)-pyrimidine. Following resynthesis, HBF-0259 had a 50% effective concentration of approximately 1.5 microM in a secondary, HBV-expressing cell line, with a concentration that exhibited 50% cytotoxicity of >50 microM. The equilibrium concentration of HBF-0259 in aqueous solution at physiological pH was 15 to 16 microM; the selective index was thus >9. As intended by our screening paradigm, HBF-0259 is a selective, potent inhibitor of secretion of both subviral and DNA-containing viral particles, while the secretion of alpha-1-acid glycoprotein and alpha-1-antitrypsin was unaffected. The HBV e antigen, which is not a constituent of HBV particles, was also unaffected, suggesting that the secretion of particles bearing HBV structural glycoproteins is targeted directly. Inhibitory activity was also confirmed by transfection of HBsAg, indicating that the action of the compound is independent of those of other viral proteins. HBF-0259 had no effect on HBV DNA synthesis, demonstrating that inhibition is independent of viral genomic replication. Finally, HBF-0259 had little or no effect on the cell-to-cell spread of two unrelated viruses, suggesting that it is a specific inhibitor of secretion of HBsAg. Possible mechanisms of action and the implications for its development are discussed.

Hepatitis B virus large and middle glycoproteins are degraded by a proteasome pathway in glucosidase-inhibited cells but not in cells with functional glucosidase enzyme.

The secretion of hepatitis B virus (HBV) large (LHBs) and middle (MHBs) envelope polypeptides from tissue cultures requires proper protein folding and is prevented by inhibitors of the endoplasmic reticulum (ER) glucosidase. Using competitive inhibitors of the ER glucosidase, here it is shown that the amounts of glycosylated and unglycosylated forms of LHBs and MHBs proteins are all greatly reduced in tissue cultures producing HBV envelope glycoproteins. In contrast, the HBV small (SHBs) protein was not affected. The reduction in secretion of LHBs and MHBs proteins appears to be mediated by proteasomal degradation pathways, since it is prevented by either lactacystin or epoxomicin, two inhibitors of proteasomal degradation. Although there is no detectable proteasomal degradation of LHBs and MHBs in cells with functional glucosidase, the implications of the nearly quantitative sensitivity of glycosylated and unglycosylated forms of LHBs and MHBs proteins, with selective sparing of SHBs protein, in cells in which glucosidase is inhibited is surprising, and its implications are discussed.

The alkylated imino sugar, n-(n-Nonyl)-deoxygalactonojirimycin, reduces the amount of hepatitis B virus nucleocapsid in tissue culture.

n-(n-Nonyl)-deoxygalactonojirimycin (n,n-DGJ), an alkylated imino sugar, reduces the amount of HBV DNA produced within the stably transfected HBV-producing HepG2.2.15 line in culture and is under consideration for development as a human therapeutic. n,n-DGJ does not appear to inhibit HBV DNA polymerase activity or envelop antigen production (A. Mehta, S. Carrouee, B. Conyers, R. Jordan, T. Butters, R. A. Dwek, and T. M. Block, Hepatology 33:1488-1495, 2001), and the mechanism of antiviral action is unknown. In this study, the step in the virus life cycle affected by n,n-DGJ was explored. Using Northern analysis and immunoprecipitation with anti-HBc antibody, we found that, under conditions in which cell viability was not affected but viral DNA production was substantially reduced, neither the amount of HBV transcription products nor the core polypeptide was detectably reduced. However, the pregenomic RNA, endogenous polymerase activity, and core polypeptide sedimenting in sucrose gradients with a density consistent with that of assembled nucleocapsids were significantly less in the HepG2.2.15 cells incubated with n,n-DGJ. These data suggest that n,n-DGJ either prevents the maturation of HBV nucleocapsids or destabilizes the formed nucleocapsids. Although the cellular and viral mediators of this inhibition are not known, depletion of nucleocapsid has been attributed to some other compounds as well as interferon's mechanism of anti-HBV action. The similarities and differences between this alkylated imino sugar and these other mediators are discussed.