Potential Therapeutic Applications of MDA-9/Syntenin-NF-κB-RKIP Loop in Human Liver Carcinoma.

BACKGROUND: Overexpression of MDA-9/Syntenin occurs in multiple human cancer cell lines and is associated with higher grade of tumor classification, invasiveness and metastasis. In some cases, its role in cancer biology depends on relationships between MDA-9/Syntenin and NF-κB. OBJECTIVE: This study aims to analyze the presence of a regulation loop like that between MDA-9/Syntenin - NF-κB - RKIP in human liver carcinoma. METHODS: Transient transfection was performed with siRNA anti-MDA-9/Syntenin. Expression of different factors was evaluated by Real time-PCR and Western blotting, while NF-κB activation by TransAM assay. Invasion capacity was analyzed by Matrigel Invasion Assay and the effects of agents on cell viability were examined by MTS assay. RESULTS: We have examined basal expression of MDA-9/Syntenin in three cell lines of human liver carcinoma (HA22T/VGH, Hep3B and HepG2). In all cell lines there was an inverse relationship between MDA-9/Syntenin and RKIP expression levels, and a positive correlation between MDA-9/Syntenin expression and NF-κB activation levels. By silencing with a siRNA anti-MDA-9/Syntenin we observed in all cell lines a very strong increase of RKIP at mRNA level. Interestingly, in all cell lines, inhibition of MDA- 9/Syntenin expression induced NF-κB downregulation and contemporary a reduction in invasion ability MMP-2 dependent. Finally, we showed a good additive effect of MDA- 9/Syntenin siRNA when associated with Curcumin or Doxorubicin on cell growth inhibition. CONCLUSION: Our data confirm the key role of MDA-9/Syntenin in HCC biology. The presence of a regulation loop among MDA-9/Syntenin, NF-κB and RKIP provide new pharmacological approaches.

NF-κB Is a Potential Molecular Drug Target in Triple-Negative Breast Cancers.

Breast cancer continues to cause significant burden in global health morbidity and mortality. Triple-negative breast cancers (TNBCs) are highly aggressive with poor prognosis and are characterized by lack of expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor (Her-2). TNBCs are often resistant to cytotoxic chemotherapy and pose major difficulty in achieving personalized medicine due to their molecular heterogeneity. There is increasing evidence that the aberrant activation of nuclear factor (NF)-κB signaling is a frequent characteristic of TNBCs. We evaluated the effects of different potential NF-κB inhibitors, such as bisindolylmaleimide I (BIS, a selective protein kinase C [PKC] inhibitor), MG132 (a proteasome inhibitor), curcumin (endowed with pleiotropic activities), and dehydroxymethylepoxyquinomicin (an inhibitor of NF-κB translocation into the nucleus) on the constitutive activation of NF-κB present in three TNBC cell lines (SUM 149, SUM 159, and MDA-MB-231). We also evaluated whether MDA-9/Syntenin plays a role in NF-κB activation, as observed in other cancer types. Indeed, silencing experiments with a siRNA anti-MDA-9/Syntenin produced a very strong reduction of NF-κB activation in all the three TNBC cell lines. We conclude that different approaches targeting NF-κB activation might potentially prove useful for innovation in anticancer drug development for TNBCs. Further research that bridge preclinical and clinical investigations with NF-κB inhibitors would be timely and warranted.

The use of proton pump inhibitors in an Italian hospital: focus on oncologic and critical non-ICU patients.

BACKGROUND: Proton pump inhibitors (PPIs) are among the most misused drugs both at the community and hospital level. Recently, possible risks have been underscored, suggesting the importance of limiting PPI use to proven indications. OBJECTIVE: To survey the appropriateness of PPI use in a University hospital in Italy. Setting Azienda Ospedaliera Universitaria Policlinico 'P. Giaccone', in Palermo, Italy. METHOD: A one day-observational study, reviewing patients' medical records to identify treatments with PPIs and the indications for their use. After discharge, a subgroup of the cohort was followed up to assess the continuation of therapy at home. Appropriateness was evaluated according to the indications stated in the official product information sheet and supported by the AIFA notes. MAIN OUTCOME MEASURE: Prevalence and appropriateness of PPI use in the hospital and after discharge. RESULTS: In the index day 62.9 % of 343 evaluable patients received a PPI. In only 29.1 % of these, the treatment could be considered appropriate. The most frequent reasons for inappropriate treatment were stress ulcer prophylaxis in low risk patients and unwarranted gastro-protection in drug treated patients. 30.9 % of patients received PPIs for uncertain indications: of these, 25.7 % were "critical" patients admitted in non-ICU wards. Furthermore, as much as 88.2 % of anticancer drug treated patients received PPIs as gastroprotective agents. At discharge 48.6 % of patients received a prescription to continue PPI therapy at home and 75.9 % of the 83 followed up patients were found to be still taking these drugs after on average 3 months from discharge. CONCLUSION: This study confirms a high proportion of inappropriate PPI therapy into the hospital that translates in a prolonged unnecessary administration in the community setting. Further studies are needed to assess the cost-effectiveness of PPI therapy in subgroups of patients at moderate risk for gastric complications to optimize current guidelines.

Rash and multiorgan dysfunction following lamotrigine: could genetic be involved?

CASE (DESCRIPTION): We report the case of a 38-year-old woman treated with lamotrigine who experienced multi-organ dysfunction. The patient received the drug at the dose of 100 mg per day. One week later, the treatment was suspended because of an extensive body rash. Twenty-four hours later, the patient appeared drowsy and stuporous and was hospitalized. On the fifth day, the patient was admitted with a clinical picture of acute multi-organ failure in our Institute, where, she, despite the support of vital functions with vasoactive drugs, continuous hemofiltration and ventilation with oxygen, died. Serum lamotrigine concentration was measured 110 h after its last dose and the drug resulted to be still present at 1 mg/L. The patient was homozygous for the UGT1A4-70C and UGT2B7-161C alleles and heterozygous for the UGT2B7-372A>G polymorphism. Regarding ABCB1 the patient showed the 3435CC, 2677GT and 1236CT genotypes. CONCLUSION: Our results may suggest a role of the UGT2B7-372A>G polymorphism in this reaction.

Cytotoxic activity of the novel small molecule AKT inhibitor SC66 in hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is characterized by limited response to current drug therapies. Here, we report that SC66, a novel AKT inhibitor, reduced cell viability in a dose- and time-dependent manner, inhibited colony formation and induced apoptosis in HCC cells. SC66 treatment led to a reduction in total and phospho-AKT levels. This was associated with alterations in cytoskeleton organization, a reduction in expression levels of E-cadherin, ß-catenin and phospho-FAK, together with up-regulation of Snail protein levels. All these alterations were coupled with anoikis cell death induction. In addition, SC66 induced the production of reactive oxygen species (ROS) and DNA damage. Pre-treatment with the ROS scavenger N-Acetyl-cysteine (NAC) prevented SC66-induced cell growth inhibition and anoikis. SC66 significantly potentiated the effects of both conventional chemotherapeutic and targeted agents, doxorubicin and everolimus, respectively. In vivo, SC66 inhibited tumor growth of Hep3B cells in xenograft models, with a similar mechanism observed in the in vitro model. Taken together, these data indicate that the AKT inhibitor SC66 had antitumor effects on HCC cells. This was mediated by ROS production, induction of anoikis-mediated cell death and inhibition of the AKT cell survival pathway. Our results provide a rational basis for the use of SC66 in HCC treatment.

Epigenetic changes and nuclear factor-κB activation, but not microRNA-224, downregulate Raf-1 kinase inhibitor protein in triple-negative breast cancer SUM 159 cells.

Raf-1 kinase inhibitor protein (RKIP) is a tumor suppressor and metastasis inhibitor, which enhances drug-induced apoptosis of cancer cells. Downregulation of RKIP may be significant in the biology of highly aggressive and drug-resistant tumors, for example triple-negative breast cancers (TNBCs). Potential causes for the low levels of RKIP expressed by SUM 159 TNBC cells were investigated in the present study. Bisulphite modification, methylation specific-polymerase chain reaction (PCR) and a TransAM NF-κB assay were performed and the results suggested that various mechanisms, including methylation of the gene promoter, histone deacetylation and nuclear factor-κB (NF-κB) activation, but not targeting by microRNA-224 (miR/miRNA-224), as determined by transfection of pre-miR-224 miRNA precursor or anti-miR-224 miRNA inhibitor, may downregulate RKIP in these cells. Furthermore, reverse transcription-quantitative PCR, western blotting, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium cell growth assay and flow cytometry revealed that in SUM 159 cells, the demethylating agent 5-aza-2'-deoxycytidine (5-AZA), the histone deacetylase inhibitor trichostatin A (TSA) and the NF-κB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) enhanced RKIP expression and resulted in significant cell growth inhibition and induction of apoptosis. 5-AZA and TSA mainly produced additive antitumor effects, while the combination of DHMEQ and TSA exhibited significant synergy in cell growth inhibition and induction of apoptosis assays. Increasing evidence that aberrant activation of NF-κB signaling is a frequent characteristic of TNBC highlights the fact that this transcription factor may be a useful target for treatment of such tumors. In addition to DHMEQ, proteasome inhibitors may also represent valuable therapeutic resources in this context. Notably, proteasome inhibitors, in addition to the inhibition of NF-κB activation, may also restore RKIP levels by inhibiting proteasome degradation of the ubiquitinated protein. The current results contribute to the understanding of the molecular mechanisms of RKIP downregulation in TNBC and suggest possible novel therapeutic approaches for the treatment of these types of cancer.

From the covalent linkage of drugs to novel inhibitors of ribonucleotide reductase: synthesis and biological evaluation of valproic esters of 3'-C-methyladenosine.

We synthesized a series of serum-stable covalently linked drugs derived from 3'-C-methyladenosine (3'-Me-Ado) and valproic acid (VPA), which are ribonucleotide reductase (RR) and histone deacetylase (HDAC) inhibitors, respectively. While the combination of free VPA and 3'-Me-Ado resulted in a clear synergistic apoptotic effect, the conjugates had lost their HDAC inhibitory effect as well as the corresponding apoptotic activity. Two of the analogs, 2',5'-bis-O-valproyl-3'-C-methyladenosine (A160) and 5'-O-valproyl-3'-C-methyladenosine (A167), showed promising cytotoxic activities against human hematological and solid cancer cell lines. A167 was less potent than A160 but had interesting features as an RR inhibitor. It inhibited RR activity by competing with ATP as an allosteric effector and concomitantly reduced the intracellular deoxyribonucleoside triphosphate (dNTP) pools. A167 represents a novel lead compound, which in contrast to previously used RR nucleoside analogs does not require intracellular kinases for its activity and therefore holds promise against drug resistant tumors with downregulated nucleoside kinases.

High dose of trimethoprim-sulfamethoxazole and daptomycin as a therapeutic option for MRSA endocarditis with large vegetation complicated by embolic stroke: a case report and literature review.

Large cardiac vegetation carries a poor prognosis and high mortality risk, especially if associated with methicillin-resistant Staphylococcus aureus (MRSA) infection. We share our experience of a rare and complicated large cardiac vegetation which had a favourable outcome with combination antibiotic treatment alone. A 35-year-old HIV-negative, HCV-positive male patient with a previous history of methicillin-susceptible S. aureus endocarditis showed MRSA mitral valve endocarditis with large vegetation, complicated by embolic stroke. The strain was soon identified by PCR but only after culture did the patient receive efficacious antibiotics. A combination of daptomycin plus trimethoprim/sulfamethoxazole (TMP/SMX) was administered for six weeks, followed by a high dosage of TMP/SMX for a further six weeks. Effectiveness of the treatment was demonstrated by the patient's clinical improvement and instrumental evidence of cardiac mitral vegetation clearance. Innovative antibiotic strategies in patient management are needed to fight Staphylococcus aureus endocarditis because strains show varying antimicrobial susceptibility patterns in different geographic areas. Timely initiation of targeted antimicrobial therapy remains a crucial step to reduce morbidity and mortality but culture is crucial for appropriate fine-tuning of antibiotic therapy.

Pharmacogenetic considerations for optimizing tacrolimus dosing in liver and kidney transplant patients.

The introduction of tacrolimus in clinical practice has improved patient survival after organ transplant. However, despite the long use of tacrolimus in clinical practice, the best way to use this agent is still a matter of intense debate. The start of the genomic era has generated new research areas, such as pharmacogenetics, which studies the variability of drug response in relation to the genetic factors involved in the processes responsible for the pharmacokinetics and/or the action mechanism of a drug in the body. This variability seems to be correlated with the presence of genetic polymorphisms. Genotyping is an attractive option especially for the initiation of the dosing of tacrolimus; also, unlike phenotypic tests, the genotype is a stable characteristic that needs to be determined only once for any given gene. However, prospective clinical studies must show that genotype determination before transplantation allows for better use of a given drug and improves the safety and clinical efficacy of that medication. At present, research has been able to reliably show that the CYP3A5 genotype, but not the CYP3A4 or ABCB1 ones, can modify the pharmacokinetics of tacrolimus. However, it has not been possible to incontrovertibly show that the corresponding changes in the pharmacokinetic profile are linked with different patient outcomes regarding tacrolimus efficacy and toxicity. For these reasons, pharmacogenetics and individualized medicine remain a fascinating area for further study and may ultimately become the face of future medical practice and drug dosing.

Analysis of possible mechanisms accounting for raf-1 kinase inhibitor protein downregulation in hepatocellular carcinoma.

Abstract Raf-1 kinase inhibitor protein (RKIP) is a tumor and metastasis suppressor that promotes drug-induced apoptosis in cancer cells. It is frequently downregulated, both at the mRNA and protein level, in hepatocellular carcinoma (HCC), but the mechanisms leading to this reduction are obscure. We sequenced the whole RKIP gene in three human HCC cell lines (HA22T/VGH, HepG2, and Hep3B), and in five clinical HCC samples, but could not find any gene variant that might account for their low RKIP levels. We also examined whether gene methylation may be responsible for the altered RKIP expression. No methylation of the RKIP gene was found in the tumor samples, while among the cell lines only Hep3B showed methylation of the gene, which was reduced by treatment with 5-aza-2'-deoxycytidine (5-AZA). The same treatment caused upregulation of RKIP at the mRNA, but not at the protein level, indicating that gene methylation is not a principal mechanism of the decrease in RKIP in the Hep3B cells. Furthermore, different elements consistently suggested that RKIP may be a target repressed by miR-224, a miRNA that is frequently and specifically upregulated in HCC, but our results excluded that this occurs, at least in the HCC cell lines. Factors like Snail, EZH2, and HDAC, have been implicated in the RKIP downregulation present in breast and prostate tumors, though some of our results from the cell lines do not support that they play such a role in HCC; however, this aspect is worthy of further study. However, recent results of ours and others suggest a significant involvement of proteosomal degradation and of its pharmacological inhibition. In conclusion, the causes of RKIP downregulation in HCC remain incompletely understood. However, we think that the present observations will be useful to generate further research, with the ultimate possible goal of devising specific approaches to restore the relevant antitumor function of the factor.

Unusual high dose of tacrolimus in liver transplant patient, a case report.

CASE: We describe the case of a liver transplant patient who had great difficulty in reaching the desired trough blood levels despite the use of high dose tacrolimus. The patient was homozygous for the CYP3A5*3 allele. However, the respective donor carried the wild-type CYP3A5*1/*1 genotype. Regarding ABCB1 SNPs at exon 21 and 26, the patient showed the 2677GT and 3435CC genotypes. For the corresponding donor we observed the 2677GG and 3435CC wild-type genotypes. One, two and three weeks after transplantation the patient received daily 0.219, 0.287 and 0.273 mg/kg of tacrolimus, respectively. However, the corresponding tacrolimus trough blood levels were of 4.6, 5.6 and 6.1 ng/mL. The tacrolimus target level of 10.4 ng/mL was finally reached after 1 month of therapy. During the entire period of observation the kidney showed no sign of damage. No other signs of toxicity were reported except for the occurrence of an isolated systolic hypertension. CONCLUSIONS: CYP3A5 genotyping may represent a useful tool to better evaluate the appropriate initial dose of tacrolimus for patients carrying a liver with the CYP3A5*1/*1 genotype.

Fluoroquinolone-induced liver injury: three new cases and a review of the literature.

PURPOSE: Fluoroquinolones are popular and widely used in primary care and hospital settings. Premarketing studies showed a favourable side-effect profile. However, significant morbidity and the need for liver transplantation for acute liver failure have been reported. We reviewed the available data on liver damage linked to fluoroquinolones. METHODS: A systematic search of case reports on the MEDLINE database encompassing the years 2000-2011 was carried out. Additional references were found by a manual search of the retrieved paper. We also describe three new cases of hepatotoxicity attributable to fluoroquinolones seen at our Unit. RESULTS: Thirty-five cases were retrieved from MEDLINE (51.4% male). According to the RUCAM scale, liver injury was classified as hepatocellular (51.4%), cholestatic (28.6%) or mixed (20.0%). Older age (≥ 65 years) was present in 42.8%. The time between initiation of treatment and hepatic injury ranged from 1 to 39 days (median 8 days). According to the RUCAM score, our cases were classified to be "highly probable" or "probable". Only one patient underwent liver biopsy, which showed the features of liver damage linked to drug exposure. Liver enzymes from all patients return to normal range within 4 weeks of withdrawal. Only one patient showed a renal failure, associated with liver injury, with a need for haemodialysis for 3 weeks. CONCLUSIONS: Fluoroquinolones are substantially safe antibiotics. Although fluoroquinolone-related hepatic injury occurs infrequently, its consequences can be severe. Patients should also be cautioned to avoid re-exposure to other members of the fluoroquinolone class.

Timely recognition of cardiovascular toxicity by anticancer agents: a common objective of the pharmacologist, oncologist and cardiologist.

Both conventional and new anticancer drugs can frequently cause adverse cardiovascular effects, which can span from subclinical abnormalities to serious life-threatening and sometimes fatal events. This review examines the principal basic and clinical elements that may be of profit to identify, prevent and treat such toxicities. Clearly, the accomplishment of such objectives requires the strong commitment and cooperation of different professional figures including, but not limited to, pharmacologists, oncologists and cardiologists. The aspect of anticancer drug cardiotoxicity seems to be somehow underestimated, mainly due to inadequate reporting of adverse reactions from oncology drugs in the post-marketing setting. Thus, the implementation of pharmacovigilance is indispensable to rapidly and fully assess the safety of newer agents in real-life patients.

Influence of CYP3A5 and ABCB1 gene polymorphisms and other factors on tacrolimus dosing in Caucasian liver and kidney transplant patients.

Tacrolimus is a substrate of cytochrome P4503A (CYP3A) enzymes as well as of the drug transporter ABCB1. We have investigated the possible influence of CYP3A5 and ABCB1 single nucleotide polymorphisms (SNPs) and other factors (e.g. albumin, hematocrit and steroids) on tacrolimus blood levels achieved in a population of Caucasian liver (n=51) and kidney (n=50) transplant recipients. At 1, 3 and 6 months after transplantation, tacrolimus doses (mg/kg/day) and trough blood levels (C0) were recorded and the weight-adjusted tacrolimus dosage (mg/kg/day) was calculated. Polymerase chain reaction followed by restriction fragment length polymorphism analysis was used for genotyping CYP3A5*1 and *3 [6986A>G] as well as ABCB1 at exons 21 [2677G>T/A] and 26 [3435C>T] in both liver transplant donors and recipients and in kidney transplant recipients. Of the 152 subjects studied, 84.9% showed a CYP3A5*3/*3 genotype. The total frequency of the allelic variant *3 was 93%. For the G2677T/A and C3435T polymorphisms the total frequencies of the allelic variants T/A and T were 44.7 and 46.7%, respectively. At 1, 3 and 6 months after transplantation the dose-adjusted C0 levels were significantly lower in patients with one copy of the *1 allele compared to those homozygous for the *3 allele. In the case of liver transplant patients the tacrolimus dose requirements were dominantly influenced by the polymorphisms of the CYP3A5 gene in the donors. With regard to the ABCB1 SNPs, in general they did not show any appreciable influence on tacrolimus dosing requirements; however, kidney transplant recipients carrying the 2677T/A allele required significantly higher daily tacrolimus doses than subjects homozygous for the wild-type allele. Identification of CYP3A5 single nucleotide polymorphisms prior to transplantation could contribute to evaluate the appropriate initial dosage of tacrolimus in the patients.

Frequent alteration of the Yin Yang 1/Raf-1 kinase inhibitory protein ratio in hepatocellular carcinoma.

The transcription factor Yin Yang 1 (YY1) can favor several aspects of tumorigenesis. In turn, Raf-1 Kinase Inhibitor Protein (RKIP) inhibits the oncogenic activities of MAPK and NF-κB pathways and promotes drug-induced apoptosis. Mutual influences between YY1 and RKIP may exist, and there are already separate evidences that relevant increases in YY1 and reductions in RKIP occur in hepatocellular carcinoma (HCC). However, the levels of the two factors have never been concomitantly examined in HCC. We evaluated by RT-PCR the mRNA levels of YY1, YY1AP, RKIP, and survivin in 35 clinical HCCs (91% HCV-related), in their adjacent cirrhotic tissues and in 6 healthy livers. Immunohistochemical analyses were also performed. The ratio of YY1 to RKIP mRNA was constantly profoundly inverted in the tumors compared with the adjacent nontumoral tissues. A similar result occurred frequently at protein level. Hyperactivation of YY1 in tumors was corroborated by its nuclear localization and the finding that in the tumors there were also increases in YY1AP, a YY1 coactivator not expressed in normal liver, and in survivin, as a possible target of YY1. The frequent alteration in the YY1-RKIP balance might represent a marker of malignant progression and be exploited for therapeutic interventions in HCC.

Chemotherapy-induced cardiotoxicity: role of the tissue Doppler in the early diagnosis of left ventricular dysfunction.

Cardiotoxicity is a common complication of chemotherapy. The aim of this study was to assess the cardiotoxicity of anticancer drugs using tissue Doppler imaging. A prospective study was carried out using patients with early breast cancer (72 women, median age: 57 ± 12 year) and other inclusion and exclusion criteria. Inclusion criteria were treatment with epirubicin, trastuzumab, fluorouracil, cyclophosphamide, taxotere, and taxolo; left ventricular ejection fraction (LVEF) of more than 50%; and absence of important pathologies. Exclusion criteria were presence of known heart disease, earlier exposure to mediastinal irradiation, and earlier chemotherapy. On the basis of treatment, patients were divided into five groups: A=fluorouracil-epirubicin-cyclophosphamide (FEC), B = FEC + trastuzumab, C = trastuzumab, D = FEC + taxotere, and E = FEC + taxol + trastuzumab. Cardiological evaluation including electrocardiogram and echocardiogram was carried out at baseline, 3 months, and 6 months after the start of chemotherapy in all patients. The Doppler patterns were integrated with other echo parameters (tissue Doppler). Significant changes (P < 0.05) in the echo parameters of the tissue Doppler were observed in treated patients during follow-up but not in LVEF. In conclusion, the tissue Doppler is more sensitive than standard Doppler in the study of diastolic function and LVEF in the study of systolic function. The tissue Doppler should integrate conventional echocardiography in the study of left ventricular function in patients treated with anticancer drugs. It is very important to reduce the risk of cardiovascular complications, especially heart failure, in breast cancer survivors.

Novel combination of celecoxib and proteasome inhibitor MG132 provides synergistic antiproliferative and proapoptotic effects in human liver tumor cells.

Molecular targeted therapy has shown promise as a treatment for advanced hepatocellular carcinoma (HCC). Celecoxib (Celebrex®) exhibits antitumor effects in human HCC cells, and its mechanism of action is mediated either by its ability to inhibit cyclooxygenase 2 (COX-2) or by a number of various other COX-2 independent effects. Proteasome inhibitors (PIs) can exert cell growth inhibitory and apoptotic effects in different tumor cell types, including HCC cells. The present study examined the interaction between celecoxib and the PI MG132 in two human liver tumor cell lines HepG2 and HA22T/VGH. Our data showed that each inhibitor reduced proliferation and induced apoptosis in a dose-dependent manner in both cell lines. Moreover, the combination of celecoxib with MG132 synergistically inhibited cell viability and increased apoptosis, as documented by caspase 3 and 7 activation, PARP cleavage, and down-regulation of Bcl-2. Celecoxib and MG132, both alone and synergistically in combination, induced expression of the endoplasmic reticulum (ER) stress genes ATF4, CHOP, TRB3 and promoted the splicing of XBP1 mRNA. Knockdown of TRB3 mRNA expression by small interference RNA significantly decreased combination-induced cell death in HA22T/VGH cells, whereas it increased combination-induced cell death in HepG2 cells, suggesting that activation of the ER stress response might have either a detrimental or a protective role in liver tumor cell survival. In conclusion, our data indicate that combination treatment with celecoxib and MG132 resulted in synergistic antiproliferative and proapoptotic effects against liver cancer cells, providing a rational basis for the clinical use of this combination in the treatment of liver cancer.

Lack of nucleophilic addition in the isoxazole and pyrazole diketone modified analogs of curcumin; implications for their antitumor and chemosensitizing activities.

Curcumin (CUR) can be considered as a good lead compound for the design of new anticancer drugs. Further, structure-activity relationship studies may clarify the importance of the redox activities in the antitumor effects of the drug. We have elaborated the alpha,beta-unsaturated 1,3-diketone moiety of CUR into the isoxazole (ISO) and pyrazole (PYR) derivatives. These derivatives should be much less prone to nucleophilic addition than CUR and benzyl mercaptan addition analyses showed that indeed they do not form isolable conjugated products. When compared with CUR, ISO and PYR exhibited increased cell growth inhibitory and pro-apoptotic effects in liver cancer HA22T/VGH cells as well as in other tumor cell types; in contrast to CUR, the antitumor effects of ISO or PYR were not influenced by concomitant administration of N-acetylcysteine, as a source of -SH groups, or buthionine sulfoximine, as an inhibitor of glutathione synthesis. Further, treatment with CUR, but not with ISO or PYR, significantly decreased the content of reduced glutathione in the HA22T/VGH cells. Finally, ISO and PYR lacked the ability of the parent compound to sensitize the HA22T/VGH cells to cisplatin (CIS), an effect which appeared to occur through an interaction of CUR and CIS at the level of the -SH groups. Thus, the ability of interacting with cell thiols might not be requested for the more potent antitumor activities of new diketone modified CUR derivatives, which might rely on other mechanisms, though possibly devoid of chemosensitization capabilities.

Antitumor effects of dehydroxymethylepoxyquinomicin, a novel nuclear factor-kappaB inhibitor, in human liver cancer cells are mediated through a reactive oxygen species-dependent mechanism.

Activation of the nuclear transcription factor-kappaB (NF-kappaB) has been implicated in liver tumorigenesis. We evaluated the effects of a novel NF-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in two human liver cancer cell lines HA22T/VGH and HuH-6. DHMEQ treatment dose dependently decreased the DNA-binding capacity of the NF-kappaB p65 subunit, inhibited cell growth and proliferation, and increased apoptosis as shown by caspase activation, release of cytochrome c, poly(ADP-ribose) polymerase cleavage, and down-regulation of survivin. DHMEQ also induced a dose-dependent activation of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling, and inhibition of this pathway significantly reduced cell growth. It is noteworthy that we observed that DHMEQ stimulated reactive oxygen species (ROS) production in a dose-dependent manner and that pretreatment of the cells with the antioxidant N-acetyl-L-cysteine (NAC) significantly reduced DHMEQ-induced ROS generation. Accordingly, NAC completely reversed the DHMEQ-induced growth inhibition, caspase activation, and cell death. DHMEQ-treated cells exhibited DNA damage, as evaluated by accumulation in nuclear foci of phospho-H2AX, which was completely reversed by NAC. Moreover, DHMEQ induced the expression of genes involved in the endoplasmic reticulum stress response (GRP78, CHOP, TRB3) and promoted the splicing of XBP1 mRNA in a dose-dependent fashion in both cell lines, which was reversed in the presence of NAC. Knockdown of TRB3 mRNA expression by small interference RNA significantly decreased DHMEQ-induced cell growth inhibition. These data suggest that DHMEQ antitumor effects are primarily mediated through ROS generation. Thereby, considering that cancer cells are under increased ER stress and oxidative stress conditions, DHMEQ may greatly improve various anticancer strategies.