Proteasome inhibition by quercetin triggers macroautophagy and blocks mTOR activity

The bioflavonoid quercetin has long been known to exert anti-tumor effects, although the underlying mechanisms remain unknown. Investigation of the potential interference of this anti-oxidant with the efficacy of cell stress-inducing anti-cancer drugs revealed extensive intracellular vacuolation induced by quercetin in epithelial cancer cells that led to cell cycle arrest and ensuing apoptosis. Accumulation of biomarkers of autophagy, including fluorescent autophagy markers and acidotropic dyes characterized these vacuoles as phagolysosomes. Prior to the formation of autophagosomes, an immediate and pronounced inhibition of the autophagy-controlling mTOR activity in quercetin-treated cancer cells occurred, accompanied by a marked reduction in the phosphorylation of the mTOR substrates 4E-BP1 and p70S6 kinase. Assessment of cellular proteasome activity revealed an effective and immediate inhibition of the activity of the proteasome by quercetin in cancer cells. In addition to the formation of autophagosomes, accumulation of poly-ubiquitinated protein aggregates was observed. Thus, proteasome inhibition by quercetin can be regarded as a major cause of quercetin-induced cancer cell death. These results suggest potential new applications for quercetin in cancer science and identify quercetin as an easy-to-handle agent to study proteasome activity, mTOR signaling and autophagy in human cancer cells for cell biological purposes.

Reduction of alloantibodies via proteasome inhibition in cardiac transplantation

BACKGROUND

The presence of alloantibodies in patients awaiting heart transplantation is associated with increased waiting time to transplant, increased risk of rejection after transplant, an increased risk of cardiac allograft vasculopathy, and decreased survival. So far, treatments to reduce circulating antibodies to allow transplantation have been limited. We report the first clinical experience using a plasma-cell-depleting strategy with bortezomib to reduce anti-HLA antibodies in the heart transplant population.

METHODS

Six patients awaiting cardiac transplantation demonstrated persistently elevated anti-HLA antibodies, despite receiving a course of treatment with intravenous immunoglobulin (IVIg) and rituximab. These patients then underwent supplemental therapy with bortezomib in conjunction with plasmapheresis. One additional patient awaiting cardiac transplantation with elevated anti-HLA antibodies required bortezomib treatment for amyloidosis. Antibody strength was monitored after completion of treatment by solid-phase (single-antigen-bead) assay.

RESULTS

The mean calculated panel-reactive antibody (cPRA) was reduced from 62% to 35% following a course of bortezomib (p = 0.01). Six of 7 patients demonstrated a significant decline in antibody levels. One patient remained refractory to desensitization therapy and died from sepsis while awaiting heart transplantation. Four patients successfully underwent cardiac transplantation without evidence of rejection or graft dysfunction. One patient developed early post-transplant graft dysfunction and died at 1 month from sepsis. Infection was the most common adverse effect associated with desensitization.

CONCLUSIONS

In this pilot study, use of plasmapheresis and bortezomib appeared to decrease cPRA, even in patients refractory to desensitization with IVIg/rituximab, thus increasing the chances that an acceptable donor heart will be available for the sensitized patient awaiting heart transplantation. However, desensitization is associated with an increased risk of infection. Further studies are warranted to determine whether the benefits of desensitization using this strategy outweigh the risks.

Genetic factors underlying the risk of bortezomib induced peripheral neuropathy in multiple myeloma patients

Bortezomib induced peripheral neuropathy is a dose-limiting side effect and a major concern in the treatment of multiple myeloma. To identify genetic risk factors associated with the development of this side effect in bortezomib treated multiple myeloma patients, a pharmacogenetic association study was performed using a discovery set (IFM 2005-01; n = 238) and a validation set (HOVON65/GMMG-HD4 and a Czech dataset; n = 231). After multiplicity correction, none of the 2,149 single nucleotide polymorphisms tested revealed any significant association with bortezomib induced peripheral neuropathy. However, 56 single nucleotide polymorphisms demonstrated an association with bortezomib induced peripheral neuropathy with pointwise, uncorrected significance. Pathway analysis of these polymorphisms demonstrated involvement of neurological disease (FDR <20%). Also a clear enrichment of major bortezomib metabolizing genes was found. Univariate evaluation of these 56 polymorphisms in the validation set demonstrated one single nucleotide polymorphism with pointwise significance: rs619824 in CYP17A1. (IFM 2005-01 clinicaltrials.gov identifier: NCT00200681; HOVON-65/GMMG-HD4 isrctn.org identifier: ISRCTN64455289).

Bortezomib as the first proteasome inhibitor anticancer drug: current status and future perspectives

Targeting the ubiquitin-proteasome pathway has emerged as a rational approach in the treatment of human cancer. Based on positive preclinical and clinical studies, bortezomib was subsequently approved for the clinical use as a front-line treatment for newly diagnosed multiple myeloma patients and for the treatment of relapsed/refractory multiple myeloma and mantle cell lymphoma, for which this drug has become the staple of treatment. The approval of bortezomib by the US Food and Drug Administration (FDA) represented a significant milestone as the first proteasome inhibitor to be implemented in the treatment of malignant disease. Bortezomib has shown a positive clinical benefit either alone or as a part of combination therapy to induce chemo-/radio-sensitization or overcome drug resistance. One of the major mechanisms of bortezomib associated with its anticancer activity is through upregulation of NOXA, which is a proapoptotic protein, and NOXA may interact with the anti-apoptotic proteins of Bcl-2 subfamily Bcl-X(L) and Bcl-2, and result in apoptotic cell death in malignant cells. Another important mechanism of bortezomib is through suppression of the NF-κB signaling pathway resulting in the down-regulation of its anti-apoptotic target genes. Although the majority of success achieved with bortezomib has been in hematological malignancies, its effect toward solid tumors has been less than encouraging. Additionally, the widespread clinical use of bortezomib continues to be hampered by the appearance of dose-limiting toxicities, drug-resistance and interference by some natural compounds. These findings could help guide physicians in refining the clinical use of bortezomib, and encourage basic scientists to generate next generation proteasome inhibitors that broaden the spectrum of efficacy and produce a more durable clinical response in cancer patients. Other desirable applications for the use of proteasome inhibitors include the development of inhibitors against specific E3 ligases, which act at an early step in the ubiquitin-proteasome pathway, and the discovery of less toxic and novel proteasome inhibitors from natural products and traditional medicines, which may provide more viable drug candidates for cancer chemoprevention and the treatment of cancer patients in the future.

Novel proteasome-inhibitory syrbactin analogs inducing endoplasmic reticulum stress and apoptosis in hematological tumor cell lines

The proteasome has been recognized as a druggable target in cancer cells, and this has led to searches for pharmacologic agents that target this cellular organelle for cancer therapeutic purposes. Syrbactins are a group of microbial metabolites consisting of two related families, the glidobactins and the syringolins. Some members of this group have revealed cytotoxic efficacy in tumor cells, and more recently it was discovered that they exert proteasome-inhibitory function. Based on this therapeutic promise and to gain further understanding of their molecular modes of action, we chemically synthesized de-novo three novel syrbactin analogs and characterized their proteasome-inhibitory and in vitro anti-neoplastic activity in human cell lines representing multiple myeloma, Waldenström's macroglobulinemia, and lymphocytic leukemia. Our results show that two of these novel compounds are able to inhibit proteasome activity in the nanomolar range, reduce the expression of anti-apoptotic proteins survivin and Mcl-1, and cause severe endoplasmic reticulum (ER) stress, resulting in pronounced tumor cell death. These anticancer effects can be synergistically enhanced when the agents are combined with thapsigargin, which further aggravates ER stress by a different mechanism. Taken together, our findings support the notion that syrbactin analogs may provide a structural platform for the development of novel cancer therapeutics, and that their efficacy may be further increased when complemented with other agents that trigger ER stress.

The neuroprotective role of boric acid on aluminum chloride-induced neurotoxicity

This study was designed to investigate the qualitative and quantitative changes in brain tissue following aluminum chloride (AlCl3) administration and to determine whether boric acid (BA) has a protective effect against brain damage induced by AlCl 3. For this aim, Sprague-Dawley rats were randomly separated into eight groups: (1) control, (2) AlCl3 (5 mg/kg/day), (3, 4 and 5) BA (3.25, 36 and 58.5 mg/kg/day), (6, 7 and 8) AlCl3 (5 mg/kg/day) plus BA (3.25, 36 and 58.5 mg/kg/day). After the animals were killed, the total numbers of neuron in the brain of all groups were determined using an unbiased stereological analysis. In addition to the stereological analysis, all brains were examined histopathologically by using light and electron microscopy. The stereological and histopathological results indicated a high damage of the rat brain tissues in the AlCl3 and AlCl3 + high dose BA (36 and 58.5) treatment groups. However, protective effects on neuron were observed in the AlCl3 + low dose BA (3.25) group when compared other AlCl3 groups. Our stereological and histopathological findings show that low-dose BA, as a proteasome inhibitor, can decrease the adverse effects of AlCl3 on the cerebral cortex.

Widespread deregulation of phosphorylation-based signaling pathways in multiple myeloma cells: opportunities for therapeutic intervention

Multiple myeloma (MM) is a neoplasm of plasma cell origin that is largely confined to the bone marrow (BM). Chromosomal translocations and other genetic events are known to contribute to deregulation of signaling pathways that lead to transformation of plasma cells and progression to malignancy. However, the tumor stroma may also provide trophic support and enhance resistance to therapy. Phosphorylation of proteins on tyrosine, serine and threonine residues plays a pivotal role in cell growth and survival. Therefore, knowing the status of phosphorylation-based signaling pathways in cells may provide key insights into how cell growth and survival is promoted in tumor cells. To provide a more comprehensive molecular analysis of signaling disruptions in MM, we conducted a kinome profile comparison of normal plasma cells and MM plasma cells as well as their surrounding cells from normal BM and diseased BM. Integrated pathway analysis of the profiles obtained reveals deregulation of multiple signaling pathways in MM cells but also in surrounding bone marrow blood cells compared to their normal counterparts. The deregulated kinase activities identified herein, which include the mTOR (mammalian target of rapamycin)/p70S6K and ERK1/2 (extracellular signal-regulated kinases 1 and 2) pathways, are potential novel molecular targets in this lethal disease.

The role of bortezomib, thalidomide and lenalidomide in the management of multiple myeloma: an overview of clinical and economic information

Bortezomib, thalidomide and lenalidomide can be aimed at treating patients with newly diagnosed multiple myeloma (both eligible and ineligible for transplantation) as well as those with relapsed or refractory disease. This review analysed the available clinical and economic data on these three drugs. Irrespective of which of the three agents is considered, the magnitude of the benefit in newly diagnosed cases (transplanted or non-transplanted) tends to be between 10 and 20 months per patient in terms of progression-free survival or survival; the survival benefit is smaller in relapsed or refractory disease. In addition, a single-institution observational analysis evaluated the outcomes in nearly 3000 consecutive patients examined between 1971 and 2006. The survival in patients diagnosed between 2001 and 2006 was longer than that observed in patients diagnosed between 1994 and 2000. This finding supports the conclusion that novel agents provide a survival improvement compared with traditional therapy. Formal cost-effectiveness studies on these three agents are still lacking. A MEDLINE search retrieved only four short papers or letters and no full-length analysis. Hence, the cost effectiveness of these agents needs further investigation, with separate assessments of the different therapeutic settings. In a simplified analysis, we tried to contrast the average cost of treatment for each of the novel agents versus their respective benefit, expressed in quality-adjusted survival. Despite its preliminary nature, our assessment indicates that the cost effectiveness of these three agents is likely to be within commonly accepted pharmacoeconomic thresholds.

Recruitment of APPL1 to ubiquitin-rich aggresomes in response to proteasomal impairment

Inhibitors of proteasomes have been shown to affect endocytosis of multiple membrane receptors, in particular at the step of cargo sorting for lysosomal degradation. Here we demonstrate that the inhibition of proteasomes causes specific redistribution of an endosomal adaptor APPL1, which undergoes initial solubilization from APPL endosomes followed by clustering in the perinuclear region. MG132 treatment decreases APPL1 labeling of endosomes while the staining of the canonical early endosomes with EEA1 remains unaffected. Upon prolonged treatment with proteasome inhibitors, endogenous APPL1 localizes to the site of aggresome formation, with perinuclear APPL1 clusters encapsulated within a vimentin cage and co-localizing with aggregates positive for ubiquitin. The clustering of APPL1 is concomitant with increased ubiquitination and decreased solubility of this protein. We determined that the ubiquitin ligase Nedd4 enhances polyubiquitination of APPL1, and the ubiquitin molecules attached to APPL1 are linked through lysine-63. Taken together, these results add APPL1 to only a handful of endogenous cellular proteins known to be recruited to aggresomes induced by proteasomal stress. Moreover, our studies suggest that the proteasome inhibitors that are already in clinical use affect the localization, ubiquitination and solubility of APPL1.

RNAi screen of the druggable genome identifies modulators of proteasome inhibitor sensitivity in myeloma including CDK5

The molecular target(s) cooperating with proteasome inhibition in multiple myeloma (MM) remain unknown. We therefore measured proliferation in MM cells transfected with 13 984 small interfering RNAs in the absence or presence of increasing concentrations of bortezomib. We identified 37 genes, which when silenced, are not directly cytotoxic but do synergistically potentiate the growth inhibitory effects of bortezomib. To focus on bortezomib sensitizers, genes that also sensitized MM to melphalan were excluded. When suppressed, the strongest bortezomib sensitizers were the proteasome subunits PSMA5, PSMB2, PSMB3, and PSMB7 providing internal validation, but others included BAZ1B, CDK5, CDC42SE2, MDM4, NME7, RAB8B, TFE3, TNFAIP3, TNK1, TOP1, VAMP2, and YY1. The strongest hit CDK5 also featured prominently in pathway analysis of primary screen data. Cyclin-dependent kinase 5 (CDK5) is expressed at high levels in MM and neural tissues with relatively low expression in other organs. Viral shRNA knockdown of CDK5 consistently sensitized 5 genetically variable MM cell lines to proteasome inhibitors (bortezomib and carfilzomib). Small-molecule CDK5 inhibitors were demonstrated to synergize with bortezomib to induce cytotoxicity of primary myeloma cells and myeloma cell lines. CDK5 regulation of proteasome subunit PSMB5 was identified as a probable route to sensitization.

α,β-Unsaturated carbonyl system of chalcone-based derivatives is responsible for broad inhibition of proteasomal activity and preferential killing of human papilloma virus (HPV) positive cervical cancer cells

Proteasome inhibitors have potential for the treatment of cervical cancer. We describe the synthesis and biological characterization of a new series of 1,3-diphenylpropen-1-one (chalcone) based derivatives lacking the boronic acid moieties of the previously reported chalcone-based proteasome inhibitor 3,5-bis(4-boronic acid benzylidene)-1-methylpiperidin-4-one and bearing a variety of amino acid substitutions on the amino group of the 4-piperidone. Our lead compound 2 (RA-1) inhibits proteasomal activity and has improved dose-dependent antiproliferative and proapoptotic properties in cervical cancer cells containing human papillomavirus. Further, it induces synergistic killing of cervical cancer cell lines when tested in combination with an FDA approved proteasome inhibitor. Exploration of the potential mechanism of proteasomal inhibition by our lead compound using in silico docking studies suggests that the carbonyl group of its oxopiperidine moiety is susceptible to nucleophilic attack by the γ-hydroxythreonine side chain within the catalytic sites of the proteasome.

A new fluorogenic peptide determines proteasome activity in single cells

The ubiquitin-proteasome system plays a critical role in many diseases, making it an attractive biomarker and therapeutic target. However, the impact of results obtained in vitro using purified proteasome particles or whole cell extracts is limited by the lack of efficient methods to assess proteasome activity in living cells. We have engineered an internally quenched fluorogenic peptide with a proteasome-specific cleavage motif fused to TAT and linked to the fluorophores DABCYL and EDANS. This peptide penetrates cell membranes and is rapidly cleaved by the proteasomal chymotrypsin-like activity, generating a quantitative fluorescent reporter of in vivo proteasome activity as assessed by time-lapse or flow cytometry fluorescence analysis. This reporter is an innovative tool for monitoring proteasomal proteolytic activities in physiological and pathological conditions.

Development and validation of a high-performance liquid chromatography-tandem mass spectrometry method for the determination of the novel proteasome inhibitor CEP-18770 in human plasma and its application in a clinical pharmacokinetic study

CEP-18770, [(1R)-1-{[(2S,3R)-3-hydroxy-2-{[(6-phenyl-2-pyridinyl)carbonyl]amino}butanoyl]amino}-3-methylbutyl]boronic acid, is a novel proteasome inhibitor, now under early clinical evaluation as an anticancer agent. To investigate its clinical pharmacokinetics, a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to measure the drug in human plasma, based on simple protein precipitation with acetonitrile after the addition of irbesartan as internal standard. The method requires a small volume of sample (100 µl) and is rapid and selective, allowing good resolution of peaks in 5 min. It is sensitive, precise and accurate, with overall precision, expressed as coefficient of variation (CV%), always < 10.0%, accuracy in the range 93.8-107.7% and high recovery, close to 100%. The limit of detection is 0.01 ng/ml and the lower limit of quantitation (LLOQ) is 0.20 ng/ml. The assay was validated in the range from the LLOQ up to 50.00 ng/ml. This is the first method developed and validated for analyzing a proteasome inhibitor with a boronic-acid-based structure in human plasma. The method was successfully applied to study the pharmacokinetics of CEP-18770 in cancer patients with solid tumors or multiple myeloma who had received the drug as a short intravenous bolus during the initial Phase I trial.

Cardiotoxicity of the anticancer therapeutic agent bortezomib

Recent case reports provided alarming signals that treatment with bortezomib might be associated with cardiac events. In all reported cases, patients experiencing cardiac problems were previously or concomitantly treated with other chemotherapeutics including cardiotoxic anthracyclines. Therefore, it is difficult to distinguish which components of the therapeutic regimens contribute to cardiotoxicity. Here, we addressed the influence of bortezomib on cardiac function in rats that were not treated with other drugs. Rats were treated with bortezomib at a dose of 0.2 mg/kg thrice weekly. Echocardiography, histopathology, and electron microscopy were used to evaluate cardiac function and structural changes. Respiration of the rat heart mitochondria was measured polarographically. Cell culture experiments were used to determine the influence of bortezomib on cardiomyocyte survival, contractility, Ca(2+) fluxes, induction of endoplasmic reticulum stress, and autophagy. Our findings indicate that bortezomib treatment leads to left ventricular contractile dysfunction manifested by a significant drop in left ventricle ejection fraction. Dramatic ultrastructural abnormalities of cardiomyocytes, especially within mitochondria, were accompanied by decreased ATP synthesis and decreased cardiomyocyte contractility. Monitoring of cardiac function in bortezomib-treated patients should be implemented to evaluate how frequently cardiotoxicity develops especially in patients with pre-existing cardiac conditions, as well as when using additional cardiotoxic drugs.

Advances in diagnosing and managing antibody-mediated rejection

Antibody-mediated rejection (AMR) is a unique, significant, and often severe form of allograft rejection that is not amenable to treatment with standard immunosuppressive medications. Significant advances have occurred in our ability to predict patients at risk for, and to diagnose, AMR. These advances include the development of newer anti-human leukocyte antigen (HLA)-antibody detection techniques and assays for non-HLA antibodies associated with AMR. The pathophysiology of AMR suggests a prime role for antibodies, B cells and plasma cells, but other effector molecules, especially the complement system, point to potential targets that could modify the AMR process. An emerging and potentially larger problem is the development of chronic AMR (CAMR) resulting from de novo donor-specific anti-HLA antibodies (DSA) that emerge more than 100 days posttransplantation. Therapeutic options include: (1) High-dose intravenously administered immunoglobulin (IVIG), which has many potential benefits. (2) The use of IVIG+rituximab (anti-CD20, anti-B cell). (3) The combination of plasmapheresis (PP)+low-dose IVIG with or without rituximab. Data support the efficacy of all of the above approaches. Newer approaches to treating AMR include using the proteosome inhibitor (bortezomib), which induces apoptosis in plasma cells, and eculizumab (anti-C5, anticomplement monoclonal antibody).

The risk factors for herpes zoster in bortezomib treatment in patients with multiple myeloma

Background

Bortezomib has significant activity in treating multiple myeloma (MM). The risk of herpes zoster (HZ) has been reported to increase significantly with bortezomib treatment, but the predisposing factors for HZ are not clear. This study is a retrospective analysis of the relevant risk factors for HZ in Korean MM patients treated with bortezomib.

Methods

Sixty-six patients with refractory or relapsed MM who underwent chemotherapy with bortezomib were included in the study. Prophylactic antiviral drugs were not used for treatment. The following parameters were reviewed: age, gender, stage and type of MM, extent of previous treatment, history of HZ, duration from the time of diagnosis to the time of bortezomib treatment initiation, and absolute lymphocyte counts (ALC) at the time of bortezomib treatment initiation.

Results

The incidence of HZ was 16.7%. There were no intergroup differences between the HZ-positive and the HZ-negative groups with regard to a history of HZ, number of previous treatments, and exposure to steroids before bortezomib treatment. The median duration from the time of MM diagnosis to the time of bortezomib treatment initiation in the HZ-positive group was significantly shorter than that in the HZ-negative group. The median ALC at the time of bortezomib initiation in the HZ-positive group was significantly lower than that in the HZ-negative group.

Conclusion

Bortezomib itself might act as a risk factor for HZ by inhibiting cell-mediated immunity, and patients with low ALC at the time of bortezomib treatment initiation were at greater risk of HZ during bortezomib treatment.

Coagulation profiles and thromboembolic events of bortezomib plus thalidomide and dexamethasone therapy in newly diagnosed multiple myeloma

Patients with multiple myeloma (MM) are at relatively high risk of developing thromboembolic event (TEE), especially during treatment with immunomodulatory agents. We characterized coagulation profiles and evaluate the incidence of TEE associated with the combination therapy of bortezomib-thalidomide-dexamethasone (VTD) in Chinese patients with newly diagnosed MM. The results indicated that the platelet count and platelet aggregation induced by the agonists were decreased after a short exposure to bortezomib in vivo. The incidence of TEE was low in VTD therapy for an overall rate of 3%. We do not recommend routine thromboprophylaxis for VTD therapy in Chinese patients with MM.

Bortezomib: a new player in pre- and post-transplant desensitization?

Several desensitization strategies have been investigated for the reversal of acute antibody-mediated rejection or for the removal of preformed anti-HLA antibodies, with the aim to promote access to renal transplantation. Today, their success appears limited or incomplete. Bortezomib, a selective inhibitor of the 26S proteasome, which is largely used in the treatment of multiple myeloma, could be a novel promising desensitizing agent. Its mechanism of action and preliminary clinical use in renal transplantation is reviewed here.

Inhibition of NF-κB signaling retards eosinophilic dermatitis in SHARPIN-deficient mice

The NF-κB pathway performs pivotal roles in diverse physiological processes such as immunity, inflammation, proliferation, and apoptosis. NF-κB is kept inactive in the cytoplasm through association with inhibitors (IκB), and translocates to the nucleus to activate its target genes after the IκBs are phosphorylated and degraded. Here, we demonstrate that loss of function of SHANK-associated RH domain interacting protein (SHARPIN) leads to activation of NF-κB signaling in skin, resulting in the development of an idiopathic hypereosinophilic syndrome (IHES) with eosinophilic dermatitis in C57BL/KaLawRij-Sharpin(cpdm)/RijSunJ mice, and clonal expansion of B-1 B cells and CD3(+)CD4(-)CD8(-) T cells. Transcription profiling in skin revealed constitutive activation of classical NF-κB pathways, predominantly by overexpressed members of IL1 family. Compound-null mutants for both the IL1 receptor accessory protein (Il1rap(tm1Roml)) and SHARPIN (Sharpin(cpdm)) resulted in mice having decreased skin disease severity. Inhibition of IκBA degradation by the proteasome inhibitor bortezomib alleviated the dermatitis in Sharpin(cpdm) mice. These results indicate that absence of SHARPIN causes IHES with eosinophilic dermatitis by NF-κB activation, and bortezomib may be an effective treatment for skin problems of IHES.

Eculizumab, bortezomib and kidney paired donation facilitate transplantation of a highly sensitized patient without vascular access

A 43-year-old patient with end-stage renal disease, a hypercoagulable condition and 100% panel reactive antibody was transferred to our institution with loss of hemodialysis access and thrombosis of the superior and inferior vena cava, bilateral iliac and femoral veins. A transhepatic catheter was placed but became infected. Access through a stented subclavian into a dilated azygos vein was established. Desensitization with two cycles of bortezomib was undertaken after anti-CD20 and IVIg were given. A flow-positive, cytotoxic-negative cross-match live-donor kidney at the end of an eight-way multi-institution domino chain became available, with a favorable genotype for this patient with impending total loss of a dialysis option. The patient received three pretransplant plasmapheresis treatments. Intraoperatively, the superior mesenteric vein was the only identifiable patent target for venous drainage. Eculizumab was administered postoperatively in the setting of antibody-mediated rejection and an inability to perform additional plasmapheresis. Creatinine remains normal at 6 months posttransplant and flow cross-match is negative. In this report, we describe the combined use of new agents (bortezomib and eculizumab) and modalities (nontraditional vascular access, splanchnic drainage of graft and domino paired donation) in a patient who would have died without transplantation.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

Cancer cell sensitivity to bortezomib is associated with survivin expression and p53 status but not cancer cell types

Background

Survivin is known playing a role in drug resistance. However, its role in bortezomib-mediated inhibition of growth and induction of apoptosis is unclear. There are conflicting reports for the effect of bortezomib on survivin expression, which lacks of a plausible explanation. Methods: In this study, we tested cancer cells with both p53 wild type and mutant/null background for the relationship of bortezomib resistance with survivin expression and p53 status using MTT assay, flow cytometry, DNA fragmentation, caspase activation, western blots and RNAi technology.

Results

We found that cancer cells with wild type p53 show a low level expression of survivin and are sensitive to treatment with bortezomib, while cancer cells with a mutant or null p53 show a high level expression of survivin and are resistant to bortezomib-mediated apoptosis induction. However, silencing of survivin expression utilizing survivin mRNA-specific siRNA/shRNA in p53 mutant or null cells sensitized cancer cells to bortezomib mediated apoptosis induction, suggesting a role for survivin in bortezomib resistance. We further noted that modulation of survivin expression by bortezomib is dependent on p53 status but independent of cancer cell types. In cancer cells with mutated p53 or p53 null, bortezomib appears to induce survivin expression, while in cancer cells with wild type p53, bortezomib downregulates or shows no significant effect on survivin expression, which is dependent on the drug concentration, cell line and exposure time.

Conclusions

Our findings, for the first time, unify the current inconsistent findings for bortezomib treatment and survivin expression, and linked the effect of bortezomib on survivin expression, apoptosis induction and bortezomib resistance in the relationship with p53 status, which is independent of cancer cell types. Further mechanistic studies along with this line may impact the optimal clinical application of bortezomib in solid cancer therapeutics.