Effects of Bortezomib on the Immune System: A Focus on Immune Regulation

Bortezomib promotes the TRAIL-mediated killing of resistant rhabdomyosarcoma by ErbB2/Her2-targeted CAR-NK-92 cells via DR5 upregulation

Treatment resistance and immune escape are hallmarks of metastatic rhabdomyosarcoma (RMS), underscoring the urgent medical need for therapeutic agents against this disease entity as a key challenge in pediatric oncology. Chimeric antigen receptor (CAR)-based immunotherapies, such as the ErbB2 (Her2)-CAR-engineered natural killer (NK) cell line NK-92/5.28.z, provide antitumor cytotoxicity primarily through CAR-mediated cytotoxic granule release and thereafter-even in cases with low surface antigen expression or tumor escape-by triggering intrinsic NK cell-mediated apoptosis induction via additional ligand/receptors. In this study, we showed that bortezomib increased susceptibility toward apoptosis in clinically relevant RMS cell lines RH30 and RH41, and patient-derived RMS tumor organoid RMS335, by upregulation of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor DR5 in these metastatic, relapsed/refractory (r/r) RMS tumors. Subsequent administration of NK-92/5.28.z cells significantly enhanced antitumor activity in vitro. Applying recombinant TRAIL instead of NK-92/5.28.z cells confirmed that the synergistic antitumor effects of the combination treatment were mediated via TRAIL. Western blot analyses indicated that the combination treatment with bortezomib and NK-92/5.28.z cells increased apoptosis by interacting with the nuclear factor κB, JNK, and caspase pathways. Overall, bortezomib pretreatment can sensitize r/r RMS tumors to CAR- and, by upregulating DR5, TRAIL-mediated cytotoxicity of NK-92/5.28.z cells.

B-Myb deficiency boosts bortezomib-induced immunogenic cell death in colorectal cancer

B-Myb has received considerable attention for its critical tumorigenic function of supporting DNA repair. However, its modulatory effects on chemotherapy and immunotherapy have rarely been reported in colorectal cancer. Bortezomib (BTZ) is a novel compound with chemotherapeutic and immunotherapeutic effects, but it fails to work in colorectal cancer with high B-Myb expression. The present study was designed to investigate whether B-Myb deletion in colorectal cancer could potentiate the immune efficacy of BTZ against colorectal cancer and to clarify the underlying mechanism. Stable B-Myb knockdown was induced in colorectal cancer cells, which increased apoptosis of the cancer cells relative to the control group in vitro and in vivo. We found that BTZ exhibited more favourable efficacy in B-Myb-defective colorectal cancer cells and tumor-bearing mice. BTZ treatment led to differential expression of genes enriched in the p53 signaling pathway promoted more powerful downstream DNA damage, and arrested cell cycle in B-Myb-defective colorectal cancer. In contrast, recovery of B-Myb in B-Myb-defective colorectal cancer cells abated BTZ-related DNA damage, cell cycle arrest, and anticancer efficacy. Moreover, BTZ promoted DNA damage-associated enhancement of immunogenicity, as indicated by potentiated expression of HMGB1 and HSP90 in B-Myb-defective cells, thereby driving M1 polarization of macrophages. Collectively, B-Myb deletion in colorectal cancer facilitates the immunogenic death of cancer cells, thereby further promoting the immune efficacy of BTZ by amplifying DNA damage. The present work provides an effective molecular target for colorectal cancer immunotherapy with BTZ.

Bortezomib-loaded immunoliposomes against CD44 expressing macrophages: an interplay for inflammation resolution

Macrophage-driven inflammation is the central player in a range of pathological conditions, comprising autoimmune disorders, various cancers, as well as chronic inflammatory states like rheumatoid arthritis. Therapeutic strategies tailored to specifically target macrophage behavior have acquired substantial interest for their potential to alleviate chronic inflammation effectively. In this study, we introduce a pioneering therapeutic approach utilizing specialized CD44-targeted immunoliposomes carrying bortezomib to address inflammation at the cellular level and the significance of this strategy lies in its precision nature. Bortezomib's inhibition of the proteasome interferes with the finely-tuned mechanism that controls NFκB activation, ultimately leading to a downregulation of the inflammatory response. After performing computational docking demonstrating its strong binding affinity to the proteasome molecule, the resulting nano-construct displayed a hydrodynamic size of 144.26 ± 74.4 nm and a quasi-spherical morphology. Moreover, the nano-construct ensured a minimum shelf-life of 30 days, aiming for targeted delivery with practical longevity. Upon internalization of immunoliposomes, the interaction with CD44 receptors exhibited downstream signaling events. This included the activation of Jun amino-terminal kinases 1/2 (JNK1/2) and the extracellular-signal-regulated kinases (ERK) pathway. JNK1/2 activation may lead to the release of mitochondrial pro-apoptotic factors, triggering the intrinsic apoptotic pathway and activation of caspases, which was confirmed from the level of apoptotic gene and protein expression. The precise targeting and anti-inflammatory action of this therapy against macrophages hold promise for therapeutic interventions in a wide range of inflammatory conditions, offering a novel avenue for precision medicine in the battle against excessive inflammation.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

Haploidentical Transplant in Radiosensitive Severe Combined Immunodeficiency Disease

Severe combined immunodeficiency (SCID) is an inborn error of immunity invariably resulting in mortality in infancy until managed by hematopoietic stem cell transplant (HSCT). We present an unusual case of SCID with a rare mutation involving the non-homologous end-joining 1 (NHEJ1) gene, where a haploidentical HSCT was carried out with modified conditioning and graft versus host prophylaxis regimen using proteasome inhibitor bortezomib with a successful outcome.

Bortezomib-loaded mixed micelles realize a "three-in-one" effect for enhanced breast cancer treatment

Comprehensively regulating the TME is now regarded as a promising approach for cancer treatment. Herein, a novel "three-in-one" effect is presented for simultaneously killing tumor cells, inhibiting the EMT of CAFs, and improving immune responses. In this study, bortezomib (BTZ) is selected for the treatment of breast cancer; it has multiple pharmacological mechanisms for killing tumor cells through the NF-κB signaling pathway, inhibiting the activity of CAFs by activating caspase-3, and enhancing the function of CD8+ T cells by regulating the expression of immune-stimulating factors. To improve the druggability of BTZ in solid tumors, BTZ-loaded lipid/glycocholic acid mixed micelles (BTZ-LGs) were prepared to verify the "three-in-one" effect in killing tumor cells, inhibiting CAFs, and improving immune responses. In the present work, BTZ-LGs were verified to show enhanced in vitro cytotoxicity in both 4T1 cells and 4T1/NIH3T3 co-cultured cells, as well as a superior in vivo treatment effect in different tumor-bearing mouse models. Additionally, BTZ-LGs could regulate the expression of α-SMA, caspase-3, E-cadherin, and N-cadherin, indicating their good inhibiting ability on both tumor cells and CAFs. More importantly, immunological analysis revealed that BTZ-LGs promoted the expression of the immunostimulatory factor IL-2 in tumor tissues, activated anti-tumor T cells, and overcame tumor-induced CD8+ T cell dysfunction. All these findings suggest that BTZ-LGs can achieve a "three-in-one" effect in terms of killing tumor cells, suppressing CAFs, and improving immune responses. This simple and multi-effective therapeutic strategy offers a promising approach for cancer therapy.

Risk factors for renal impairment in patients with hematological cancer receiving antineoplastic treatment

PURPOSE

Antineoplastic treatments, mainly chemotherapy, affect the kidneys, causing toxicity, and can trigger acute and chronic kidney injuries. This study aimed to analyze the prevalence of renal disorders in patients with oncohematological neoplasms receiving antineoplastic treatment.

METHODS

This retrospective cohort study included 75 patients with hematological cancer who underwent chemotherapy between 2012 and 2018 in the Hematology Sector of the Walter Cantídeo University Hospital of the Federal University of Ceará. Sociodemographic and clinical data, blood biochemical assessment findings, and glomerular filtration rate (GFR) were analyzed using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The data were tabulated; transferred to the Statistical Package for the Social Sciences software, version 20.0; and analyzed using Pearson's chi-square test or Fisher's exact test for categorical variables followed by a multinomial logistic regression model (p < 0.05).

RESULTS

The prevalence of renal disorders was 52.4% according to the CKD-EPI equation for GFR events. There was a significant association between the decrease in GFRs and the following variables: female sex (p = 0.002), diagnosis of multiple myeloma (p = 0.008), start of treatment within 40 days (p = 0.005), and the following antineoplastic treatments: cyclophosphamide, vincristine, and prednisone (p = 0.026); irarubicin (p = 0.032); azacytidine, dexamethasone, and cyclophosphamide (p < 0.001); zoledronic acid (p < 0.001); and pamidronate (p = 0.012). CALGB 8811 (p < 0.001) was inversely associated with a reduction in the GFR.

CONCLUSIONS

The prevalence of renal disorders was high in patients with oncohematological neoplasms receiving antineoplastic treatment. This requires periodic monitoring of the evaluation of renal function since reductions in GFRs were significantly associated with different treatment protocols used.

Candida albicans Hyphal Extracellular Vesicles Are Different from Yeast Ones, Carrying an Active Proteasome Complex and Showing a Different Role in Host Immune Response

Candida albicans is the principal causative agent of lethal fungal infections, predominantly in immunocompromised hosts. Extracellular vesicles (EVs) have been described as crucial in the interaction of microorganisms with their host. Since the yeast-to-hypha transition is an important virulence trait with great impact in invasive candidiasis (IC), we have addressed the characterization of EVs secreted by hyphal cells (HEVs) from C. albicans, comparing them to yeast EVs (YEVs). YEVs comprised a larger population of bigger EVs with mainly cell wall proteins, while HEVs were smaller, in general, and had a much higher protein diversity. YEVs were able to rescue the sensitivity of a cell wall mutant against calcofluor white, presumably due to the larger amount of cell wall proteins they contained. On the other hand, HEVs also contained many cytoplasmic proteins related to protein metabolism and intracellular protein transport and the endosomal sorting complexes required for transport (ESCRT) pathway related to exosome biogenesis, pointing to an intracellular origin of HEVs. Interestingly, an active 20S proteasome complex was secreted exclusively in HEVs. Moreover, HEVs contained a greater number of virulence-related proteins. As for their immunogenic role, both types of EV presented immune reactivity with human sera from patients suffering invasive candidiasis; however, under our conditions, only HEVs showed a cytotoxic effect on human macrophages and could elicit the release of tumor necrosis factor alpha (TNF-α) by these macrophages. IMPORTANCE This first analysis of HEVs of C. albicans has shown clear differences between them and the YEVs of C. albicans, showing their relevance and possible use in the discovery of new diagnostic markers and treatment targets against C. albicans infections. The data obtained point to different mechanisms of biogenesis of YEVs and HEVs, as well as different involvements in cell biology and host interaction. YEVs played a more relevant role in cell wall maintenance, while HEVs were more closely related to virulence, as they had greater effects on human immune cells. Importantly, an active 20S proteosome complex was described as a fungal-EV cargo. A deeper study of its role and those of many other proteins exclusively detected in HEVs and involved in different relevant biological processes of this fungus could open up interesting new areas of research in the battle against C. albicans.

Prolonged treatment with the proteasome inhibitor MG-132 induces apoptosis in PC12 rat pheochromocytoma cells

Rat pheochromocytoma (PC12) cells were treated with the proteasome inhibitor MG-132 and morphological changes were recorded. Initially, neuronal differentiation was induced but after 24 h signs of morphological deterioration became apparent. We performed nuclear staining, flow cytometry and WST-1 assay then analyzed signal transduction pathways involving Akt, p38 MAPK (Mitogen-Activated Protein Kinase), JNK (c-Jun N-terminal Kinase), c-Jun and caspase-3. Stress signaling via p38, JNK and c-Jun was active even after 24 h of MG-132 treatment, while the survival-mediating Akt phosphorylation declined and the executor of apoptosis (caspase-3) was activated by that time and apoptosis was also observable. We examined subcellular localization of stress signaling components, applied kinase inhibitors and dominant negative H-Ras mutant-expressing PC12 cells in order to decipher connections of stress-mediating pathways. Our results are suggestive of that treatment with the proteasome inhibitor MG-132 has a biphasic nature in PC12 cells. Initially, it induces neuronal differentiation but prolonged treatments lead to apoptosis.

The Key Role of Hepcidin-25 in Anemia in Multiple Myeloma Patients with Renal Impairment

Background and objectives: Anemia is common in multiple myeloma (MM) and is caused by a complex pathomechanism, including impaired iron homeostasis. Our aim is to evaluate the biomarkers of iron turnover: serum soluble transferrin receptor (sTfR) and hepcidin-25 in patients at various stages of MM in relation with markers of anemia, iron status, inflammation, renal impairment and burden of the disease and as predictors of mortality. Materials and methods: Seventy-three MM patients (six with smoldering and 67 with symptomatic disease) were recruited and observed for up to 27 months. Control group included 21 healthy individuals. Serum sTfR and hepcidin were measured with immunoenzymatic assays. Results: MM patients with and without anemia had higher sTFR compared to controls, while only anemic patients had higher hepcidin-25. Both hepcidin-25 and sTfR were higher in anemic than non-anemic patients. Higher hepcidin-25 (but not sTfR) was associated with increasing MM advancement (from smoldering to International Staging System stage III disease) and with poor response to MM treatment, which was accompanied by lower blood hemoglobin and increased anisocytosis. Neither serum hepcidin-25 nor sTfR were correlated with markers of renal impairment. Hepcidin-25 predicted blood hemoglobin in MM patients independently of other predictors, including markers of renal impairment, inflammation and MM burden. Moreover, both blood hemoglobin and serum hepcidin-25 were independently associated with patients’ 2-year survival. Conclusions: Our results suggest that hepcidin-25 is involved in anemia in MM and its concentrations are not affected by kidney impairment. Moreover, serum hepcidin-25 may be an early predictor of survival in this disease, independent of hemoglobin concentration. It should be further evaluated whether including hepcidin improves the early diagnosis of anemia in MM.

Cardiac macrophages regulate isoproterenol-induced Takotsubo-like cardiomyopathy

Takotsubo syndrome (TTS) is an acute, stress-induced cardiomyopathy that occurs predominantly in women after extreme physical and/or emotional stress. To date, our understanding of the molecular basis for TTS remains unknown and, consequently, specific therapies are lacking. Myocardial infiltration of monocytes and macrophages in TTS has been documented in clinical studies. However, the functional importance of these findings remains poorly understood. Here, we show that a single high dose of isoproterenol (ISO) in mice induced a TTS-like cardiomyopathy phenotype characterized by female predominance, severe cardiac dysfunction, and robust myocardial infiltration of macrophages. Single-cell RNA-Seq studies of myocardial immune cells revealed that TTS-like cardiomyopathy is associated with complex activation of innate and adaptive immune cells in the heart, and macrophages were identified as the dominant immune cells. Global macrophage depletion (via clodronate liposome administration) or blockade of macrophage infiltration (via a CCR2 antagonist or in CCR2-KO mice) resulted in recovery of cardiac dysfunction in ISO-challenged mice. In addition, damping myeloid cell activation by HIF1α deficiency or exposure to the immunomodulatory agent bortezomib ameliorated ISO-induced cardiac dysfunction. Collectively, our findings identify macrophages as a critical regulator of TTS pathogenesis that can be targeted for therapeutic gain.

Modulation of Immune Reaction in Hydrodynamic Gene Therapy for Hemophilia A

Hemophilia A (HA) is a monogenic disease characterized by plasma clotting factor 8 (F8) deficiency due to F8 mutation. We have been attempting to cure HA permanently using a CRISPR-Cas9 gene-editing strategy. Here, we induced targeted integration of BDDF8 (B-domain-deleted F8) gene into the albumin locus of HA mice by hydrodynamic tail vein injection of editing plasmid vectors. One week after treatment, a high F8 activity ranging from 70% to 280% of normal serum levels was observed in all treated HA mice but dropped to background levels 3-5 weeks later. We found that the humoral immune reaction targeting F8 is the predominant cause of the decreased F8 activity. We hypothesized that hydrodynamic injection-induced liver damage triggered the release of large quantities of inflammatory cytokines. However, co-injection of plasmids expressing a dozen immunomodulatory factors failed to curtail the immune reaction and stabilize F8 activity. The spCas9 plasmid carrying a miR-142-3p target sequence alleviated the cellular immune response but was unable to deliver therapeutic efficacy. Strikingly, immunosuppressant cyclo-phosphamide virtually abolished the immune response, leading to a year-long stable F8 level. Our findings should have important implications in developing therapies in mouse models using the hydrodynamic gene delivery approach, highlighting the ne-cessity of modulating the innate immune response triggered by liver damage.

Immunomodulatory drugs suppress Th1-inducing ability of dendritic cells but enhance Th2-mediated allergic responses

Immunomodulatory drugs (IMiDs), lenalidomide and pomalidomide, are widely used treatments for multiple myeloma; however, they occasionally lead to episodes of itchy skin and rashes. Here, we analyzed the effects of IMiDs on human myeloid dendritic cells (mDCs) as major regulators of Th1 or Th2 responses and the role they play in allergy. We found that lenalidomide and pomalidomide used at clinical concentrations did not affect the survival or CD86 and OX40-ligand expression of blood mDCs in response to lipopolysaccharide (LPS) and thymic stromal lymphopoietin (TSLP) stimulation. Both lenalidomide and pomalidomide dose-dependently inhibited interleukin-12 (IL-12) and TNF production and STAT4 expression, and enhanced IL-10 production in response to LPS. When stimulated with TSLP, both IMiDs significantly enhanced CCL17 production and STAT6 and IRF4 expression and promoted memory Th2-cell responses. In 46 myeloma patients, serum CCL17 levels at the onset of lenalidomide-associated rash were significantly higher than those without rashes during lenalidomide treatment and those before treatment. Furthermore, serum CCL17 levels in patients who achieved a very good partial response (VGPR) were significantly higher compared with a less than VGPR during lenalidomide treatment. The median time to next treatment was significantly longer in lenalidomide-treated patients with rashes than those without. Collectively, IMiDs suppressed the Th1-inducing capacity of DCs, instead promoting a Th2 response. Thus, the lenalidomide-associated rashes might be a result of an allergic response driven by Th2-axis activation. Our findings suggest clinical efficacy and rashes as a side effect of IMiDs are inextricably linked through immunostimulation.

Minocycline for symptom reduction in patients with multiple myeloma during maintenance therapy: a phase II placebo-controlled randomized trial

BACKGROUND

Patients with multiple myeloma (MM) experience substantial cancer/treatment-related symptom burden during maintenance therapy. This is a phase II randomized, double-blinded, placebo-controlled clinical trial to examine the effect of minocycline for symptom reduction by its potential anti-inflammatory effect.

METHODS

Eligible MM patients for maintenance therapy were randomized to receive minocycline (100 mg twice daily) or placebo. The MD Anderson Symptom Inventory for MM (MDASI-MM) was used to assess multiple symptoms weekly during the trial. Clinician-rated toxicities and blood samples were prospectively collected. The effect size, area under the curve (AUC), and t tests were used to determine the symptom burden between treatment groups and identify the 5 most-severe MDASI-MM symptoms. The longitudinal analysis compared the changes in symptom severity and associated inflammatory markers between groups over time.

RESULTS

Sixty-nine evaluable MM patients (33 from the intervention group and 36 from the placebo group) were included. No grade 3+ adverse events related to study medication were noted. The AUCs for the 5 worst MDASI-MM symptoms (fatigue, pain, disturbed sleep numbness/tingling, and drowsiness) were not significantly different between two arms. Regardless of group assignment, pain reduction was positively associated with decreased serum levels of soluble tumor necrosis factor-α receptors 1 and 2 during therapy (all P < 0.05).

CONCLUSIONS

This pPhase II randomized study observed no statistically significant positive signal impact from minocycline on symptom reduction or inflammatory markers during maintenance therapy for MM, although using minocycline was feasible and had a low toxicity profile.

LMP7 polymorphism may modify the presentation and clinical impact of minor histocompatibility antigens in matched related hematopoietic stem cell transplantation

Differential expression of minor histocompatibility antigens between the recipient and donor determines their disparity and can be modified by immunoproteasomes that regulate their processing and presentation. We examined the impact of HA-1 and HA-8 disparity, and immunoproteasome LMP7 polymorphism in 130 pairs. In multivariate analysis, HA-1 disparity showed a statistically significant association with an increased incidence of acute graft-versus-host disease (aGVHD) II-IV (p = 0.043, HR: 3.71, 95%CI = 1.04-13.26), while LMP7-Q/Q showed a trend toward increased incidence of aGVHD compared to LMP7-Q/K and K/K genotypes (p = 0.087, HR: 2.36, 95%CI = 0.88-6.31). All HA-1 and HA-8 disparate patients who developed aGVHD had the LMP7-Q/Q genotype. No significant association could be detected between HA-1, HA-8, or LMP7 and chronic GVHD, relapse-free survival (RFS), overall survival (OS), or transplant-related mortality (TRM). In conclusion, we suggested an association between the HA-1 disparity and the risk of developing aGVHD with a possible modifying effect of LMP7.

Allogeneic Hematopoietic Transplantation for Multiple Myeloma in the New Drugs Era: A Platform to Cure

Allogeneic hematopoietic cell transplantation (alloHCT) represents a treatment option for multiple myeloma (MM) patients. As shown in several studies, alloHCT is highly effective, but it is hampered by a high toxicity, mainly related to the graft-versus-host disease (GVHD), a complex immunological reaction ascribable to the donor’s immune system. The morbidity and mortality associated with GVHD can weaken the benefits of this procedure. On the other side, the high therapeutic potential of alloHCT is also related to the donor’s immune system, through immunological activity known as the graft-versus-myeloma effect. Clinical research over the past two decades has sought to enhance the favorable part of this balance, along with the reduction in treatment-related toxicity. Frontline alloHCT showed promising results and a potential for a cure in the past. Currently, thanks to the improved results of first-line therapies and the availability of effective second- or third-line salvage therapies, alloHCT is reserved for selected high-risk patients and is considered a clinical option. For donor lymphocyte infusion, bortezomib or lenalidomide have been used as consolidation or maintenance therapies post-transplant—none has become standard of care. For those patients who relapse, the best treatment should be evaluated considering the patient’s clinical status and the previous lines of therapy. The use of newer drugs, such as monoclonal antibodies or other immunotherapies in the post-transplant setting, deserves further investigation. However, acceptable toxicity and a synergic effect with the newer immune system could be hopefully expected.

Carfilzomib combined with cyclosporine and methotrexate for the prevention of graft-versus-host disease after allogeneic stem-cell transplantation from unrelated donors

Acute graft-versus-host disease (aGVHD) is the major treatment-related complication after stem-cell transplantation (SCT) from unrelated donors. The proteasome-inhibitor bortezomib was added to GVHD prevention regimens with initial promise. However, two randomized studies failed to show efficacy. We explored the addition of carfilzomib, s second-generation proteasome inhibitor (20 mg/m², intravenously on days +1 and +2) to cyclosporine/methotrexate backbone in 26 patients after SCT from unrelated donors. We compared outcomes to historical group of 100 patients given cyclosporine/methotrexate alone. Median follow-up was 34 months. There was no difference between the groups in engraftment or toxicities. The cumulative incidence of aGVHD grade II-IV, 6 months post transplant was 11% (95% CI, 4-32) and 39% (95% CI, 30-50), respectively (P = 0.01). The cumulative incidence of chronic GVHD, 2 years post transplant, was 49% (95% CI, 32-75) and 41% (95% CI, 33-52), respectively (P = 0.98). Three-year non-relapse mortality was 11% (95% CI, 4-33) and 18% (95% CI, 12-27, P = 0.45) while 3-year relapse rates were 8% (95% CI, 2-29) and 26% (95% CI, 18-36), respectively (P = 0.06). Three-year survival was 81% (95%CI, 66-96) and 56% (95% CI, 46-66), respectively (P = 0.05). In conclusion, carfilzomib with cyclosporine/methotrexate is safe, may reduce aGVHD, and possibly improve survival after unrelated donor SCT. These initial observations merit further study in larger comparative studies. ClinicalTrial.gov NCT01991301.

Prospective phase 2 trial of ixazomib after nonmyeloablative haploidentical peripheral blood stem cell transplant

Proteasome inhibition results in extensive immunomodulatory effects that augment natural killer cell cytotoxicity and inhibit aspects of T-cell, B-cell, and dendritic cell function. We performed a phase 2 study that examined the effects of ixazomib for graft-versus-host disease (GVHD) prophylaxis (up to 12 cycles) with posttransplant cyclophosphamide and tacrolimus after standard nonmyeloablative haploidentical donor transplantation (HIDT). Ixazomib was started on day +5 (4 mg on days 1, 8, and 15 of a 28-day cycle), with dose reductions allowed in future cycles for toxicity. All patients received peripheral blood stem cells. Twenty-five patients were enrolled with a median age of 62 years (range, 35-77 years) who had acute leukemia (4), myelodysplastic syndrome (7), non-Hodgkin lymphoma/Hodgkin lymphoma/chronic lymphocytic leukemia (8), and myeloma (6). The hematopoietic cell transplant comorbidity index was ≥3 in 68% of the patients. After a median follow-up of 33.5 months, the cumulative incidence of relapse/progression at 1 year was 24% and 44% at 3 years, which failed to meet the statistically predefined goal of decreasing 1-year risk of relapse. Engraftment occurred in all patients with no secondary graft failure, and 3-year nonrelapse mortality (NRM) was 12%. Cumulative incidence of grade 3 to 4 acute GVHD was 8%, whereas moderate-to-severe chronic GVHD occurred in 19%. Nineteen patients survive with an estimated 1-year overall survival (OS) of 84% and 3-year OS of 74%. Hematologic and cutaneous toxicities were common but manageable. The substitution of ixazomib for mycophenolate mofetil (MMF) post-HIDT results in reliable engraftment, comparable rates of clinically significant GVHD, relapse and NRM, and favorable OS. This trial was registered at www.clinicaltrials.gov as # NCT02169791.

Immunoproteasome Genes Are Modulated in CD34+ JAK2V617F Mutated Cells from Primary Myelofibrosis Patients

Primary myelofibrosis (PMF) is a rare myeloproliferative neoplasm characterized by stem-cell-derived clonal over-proliferation of mature myeloid lineages, bone marrow fibrosis, osteosclerosis, defective erythropoiesis, and pro-inflammatory cytokine over-expression. The aim of the present study was to highlight possible differences in the transcriptome among CD34⁺ cells from peripheral blood (PB) of PMF patients. Therefore, we merged two microarray datasets of healthy control subjects and PMF (34 JAK2^V617F MUTATED and 28 JAK2 wild-type). The GO analysis of upregulated genes revealed enrichment for JAK2/STAT1 pathway gene set in PB CD34⁺ cells of PMF patients with and without the JAK2^V617F mutation comparing to the healthy control subjects, and in particular a significant upregulation of immunoproteasome (IP)-belonging genes as PSMB8, PSMB9, and PSMB10. A more detailed investigation of the IFN-gamma (IFNG) pathway also revealed that IFNG, IRF1, and IFNGR2 were significantly upregulated in PB CD34⁺ cells of PMF patients carrying the mutation for JAK2^V617F compared to JAK2 wild-type PMF patients. Finally, we showed an upregulation of HLA-class I genes in PB CD34⁺ cells from PMF JAK2^V617F mutated patients compared to JAK2 wild-type and healthy controls. In conclusion, our results demonstrate that IPs and IFNG pathways could be involved in PMF disease and in particular in patients carrying the JAK2^V617F mutation.

Post-transplantation Cyclophosphamide: From HLA-Haploidentical to Matched-Related and Matched-Unrelated Donor Blood and Marrow Transplantation

Following allogeneic blood and marrow transplantation (BMT), graft-versus-host disease (GvHD) continues to represent a significant cause of treatment failure, despite the routine use of conventional, mainly calcineurin inhibitor-based prophylaxis. Recently, post-transplant cyclophosphamide (PTCy) has emerged as a safe and efficacious alternative. First, omitting the need for ex vivo T-cell depletion in the setting of haploidentical transplantation, growing evidence supports PTCy role in GvHD prevention in matched-related and matched-unrelated transplants. Through improved understanding of GvHD pathophysiology and advancements in drug development, PTCy emerges as a unique opportunity to design calcineurin inhibitor-free strategies by integrating agents that target different stages of GvHD development.

Therapeutic potential of proteasome inhibitors for dihydropyridine-induced gingival overgrowth

OBJECTIVES

NF-κB plays a crucial role in collagen overproduction in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. We aim to investigate the role of the kappa B (IκB) kinase (IKK)-NF-κB pathway and downstream collagen type I (Col I) synthesis in DIGO cells and to demonstrate the therapeutic strategy of interference of this pathway with proteasome inhibitors.

METHODS

Gingival fibroblasts from DIGO (n = 5) and healthy (n = 5) patients were selected and stimulated with IL-1β, nifedipine, or both. All experiments were run in triplicate and independently for each primary cell sample.

RESULTS

The results demonstrated that both drugs additively mediated NF-κB activity by activating IKKα/β phosphorylation. They also triggered nuclear translocation of NF-κB, Rela, and p50 (*p < .05) and increased Col I production in both healthy and DIGO cells. The addition of proteasome inhibitors, including bortezomib and MG132, promoted the accumulation of phosphorylated p-IκBα, prevented the subsequent cytosol-to-nuclear translocation of p50 and Rela (*p < .05), and abbreviated the biosynthesis of Col I in DIGO cells.

CONCLUSIONS

We suggested that IKK-IκBα activation is mediated by proinflammatory cytokines and CCBs in DIGO cells and triggers downstream NF-κB-Col I synthesis. Proteasome inhibitors may strategically interfere with the IKK-IκBα-NF-κB-Col I pathway and inhibit the etiopathogenesis of DIGO.

Cellular Responses to Proteasome Inhibition: Molecular Mechanisms and Beyond

Proteasome inhibitors have been actively tested as potential anticancer drugs and in the treatment of inflammatory and autoimmune diseases. Unfortunately, cells adapt to survive in the presence of proteasome inhibitors activating a variety of cell responses that explain why these therapies have not fulfilled their expected results. In addition, all proteasome inhibitors tested and approved by the FDA have caused a variety of side effects in humans. Here, we describe the different types of proteasome complexes found within cells and the variety of regulators proteins that can modulate their activities, including those that are upregulated in the context of inflammatory processes. We also summarize the adaptive cellular responses activated during proteasome inhibition with special emphasis on the activation of the Autophagic-Lysosomal Pathway (ALP), proteaphagy, p62/SQSTM1 enriched-inclusion bodies, and proteasome biogenesis dependent on Nrf1 and Nrf2 transcription factors. Moreover, we discuss the role of IRE1 and PERK sensors in ALP activation during ER stress and the involvement of two deubiquitinases, Rpn11 and USP14, in these processes. Finally, we discuss the aspects that should be currently considered in the development of novel strategies that use proteasome activity as a therapeutic target for the treatment of human diseases.

Proteasome Inhibition After Burn Injury

The objective of this study was to assess the effects of proteasome inhibition on the development of burn-induced hypermetabolism. Rats underwent 30-40% total BSA scald burn or sham injury. The proteasome inhibitor bortezomib (0.1 mg/kg) or vehicle (n = 10) was administered i.p. 3× weekly starting at 2 hours (early bortezomib, n = 20) or 48 hours (late-bortezomib, n = 13) postburn. Body weights were determined weekly. Resting energy expenditures (REE) were measured at days 0 (baseline), 7, 14, 21, and 42 postburn. At day 42, blood and pectoral muscle were harvested. Routine blood chemistry parameters were analyzed. Proteasome content, proteasome peptidase activities, and ubiquitin-protein conjugates were measured in muscle extracts. As compared with sham-vehicle-treated animals, specific proteasome activities were increased after burn and vehicle treatment. Bortezomib treatment inhibited proteasome activities and increased ubiquitin-protein conjugates after sham and burn injury. Bortezomib treatment did not affect REE after sham procedure. REE significantly increased by 47% within 7 days and remained elevated until day 42 after burn and vehicle treatment. After early-bortezomib treatment, burn-induced increases in REE were delayed and significantly reduced by 42% at day 42, as compared with vehicle treatment. With late-bortezomib treatment, burn-induced increases in REE were also delayed but not attenuated at day 42. Mortality was 20% with vehicle, 65% (median survival time: 1.875 days) with early-bortezomib and 25% with late-bortezomib treatment after burns (P < .05 early-bortezomib vs vehicle and late-bortezomib). Proteasome inhibition delays development of burn-induced hypermetabolism. Although proteasome inhibition early after burn injury reduces the hypermetabolic response, it significantly increases early burn-associated mortality.

The proteasome inhibitor bortezomib attenuates renal fibrosis in mice via the suppression of TGF-β1

Kidney fibrosis and fibrogenesis significantly exacerbate chronic kidney disease (CKD) progression and are essential therapeutic targets. Bortezomib (BZM) is a proteasome inhibitor used for the treatment of multiple myeloma (MM). Several studies have demonstrated that BZM attenuates renal impairment in patients with MM, although this effect is generally considered to be the result of MM remission. Recently, several studies on BZM reported anti-fibrotic effects on liver and skin in experimental animal models. However, its effect on renal fibrosis has yet to be examined. Here, we investigated the anti-fibrotic effects of BZM in an experimental mouse model of fibrosis that uses aristolochic acid I (AA). Ten weeks of AA administration with BZM treatment twice a week significantly attenuated AA-induced renal dysfunction and albuminuria, reduced the expression of renal fibrosis-related proteins and kidney injury markers, such as αSMA, Kim1, and Ngal, and prevented renal fibrosis at the level of histopathology. Furthermore, pathological activation of TGFβ1-Smad3 signaling and apoptosis, essential pathophysiological causes of AA-induced nephropathy (AAN), were ameliorated by BZM, suggesting this mechanism may be involved in improving fibrosis in AAN. In conclusion, BZM directly inhibits renal fibrosis in CKD via suppression of TGFβ1-Smad3 signaling and is promising in terms of drug repositioning.

Calcineurin and mTOR Inhibitor-Free Post-Transplantation Cyclophosphamide and Bortezomib Combination for Graft-versus-Host Disease Prevention after Peripheral Blood Allogeneic Hematopoietic Stem Cell Transplantation: A Phase I/II Study

Graft-versus-host disease (GVHD) hampers the utility of allogeneic hematopoietic stem cell transplantation (AHSCT). The purpose of this study was to determine the feasibility, safety, and efficacy of a novel combination of post-transplantation cyclophosphamide (PTC) and bortezomib for the prevention of GVHD. Patients undergoing peripheral blood AHSCT for hematological malignancies after reduced-intensity conditioning with grafts from HLA-matched related or unrelated donors were enrolled in a phase I/II clinical trial. Patients received a fixed dose of PTC and an increasing dose of bortezomib in 3 cohorts, from .7 to 1 and then to 1.3 mg/m², administered 6 hours after graft infusion and 72 hours thereafter, during phase I. The study was then extended at the higher dose in phase II for a total of 28 patients. No graft failure and no unexpected grade ≥3 nonhematologic toxicities were encountered. The median times to neutrophil and platelet engraftment were 16 and 27 days, respectively. Day +100 treatment-related mortality was 3.6% (95% confidence interval [CI], .2% to 15.7%). The cumulative incidences of grades II to IV and grades III and IV acute GVHD were 35.9% (95% CI, 18.6% to 53.6%) and 11.7% (95% CI, 2.8% to 27.5%), respectively. The incidence of chronic GVHD was 27% (95% CI, 11.4% to 45.3%). Progression-free survival, overall survival, and GVHD and relapse-free survival rates were 50% (95% CI, 30.6% to 66.6%), 50.8% (95% CI, 30.1% to 68.2%), and 37.7% (95% CI, 20.1% to 55.3%), respectively. Immune reconstitution, measured by CD3, CD4, and CD8 recovery, was prompt. The combination of PTC and bortezomib for the prevention of GVHD is feasible, safe, and yields promising results. The combination warrants further examination in a multi-institutional trial.

Sub-apoptotic dosages of pro-oxidant vitamin cocktails sensitize human melanoma cells to NK cell lysis

Alpha-tochopheryl succinate (αTOS), vitamin K3 (VK3) and vitamin C (ascorbic acid, AA) were previously shown to synergistically promote different death pathways in carcinoma cells, depending on their concentrations and combinations. Similar effects were observed herein in melanoma cells, although αTOS behaved as an antagonist. Interestingly, suboptimal cell death-inducing concentrations (1.5 μM αTOS/20 μM AA/0.2 μM VK3) effectively up-regulated activating Natural Killer (NK) cell ligands, including MICA (the stress-signaling ligand of the NKG2D receptor), and/or the ligands of at least one of the natural cytotoxicity receptors (NKp30, NKp44 and NKp46) in 5/6 melanoma cell lines. Only an isolated MICA down-regulation was seen. HLA class I, HLA class II, ULBP1, ULBP2, ULBP3, Nectin-2, and PVR displayed little, if any, change in expression. Ligand up-regulation resulted in improved lysis by polyclonal NK cells armed with the corresponding activating receptors. These results provide the first evidence for concerted induction of cell death by cell-autonomous and extrinsic (immune) mechanisms. Alarming the immune system much below the cell damage threshold may have evolved as a sensitive readout of neoplastic transformation and oxidative stress. Cocktails of vitamin analogues at slightly supra-physiological dosages may find application as mild complements of melanoma treatment, and in chemoprevention.

Bortezomib for the prevention and treatment of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation is the standard treatment for a variety of benign and malignant conditions. However, graft-versus-host disease (GvHD) continues to present a major barrier to the success and wide applicability of this procedure. Although current GvHD prevention and treatment regimens exclusively target T cells, bortezomib, a reversible proteasome inhibitor, possesses unique immune regulatory activities that span a wide variety of cellular processes of T and dendritic cells essential for the development of GvHD. Herein, we review the current understanding of the effects of bortezomib in vitro and in animal models and summarize the clinical data relevant to its use in the prevention and treatment of GvHD. We conclude with an outline of the remaining challenges and opportunities to optimize bortezomib's potential role in this setting.

Novel approaches for preventing acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (alloHSCT) offers potential curative treatment for a wide range of malignant and nonmalignant hematological disorders. However, its success may be limited by post-transplant acute graft-versus-host disease (aGVHD), a systemic syndrome in which donor's immune cells attack healthy tissues in the immunocompromised host. aGVHD is one of the main causes of morbidity and mortality after alloHSCT. Despite standard GVHD prophylaxis regimens, aGVHD still develops in approximately 40-60% of alloHSCT recipients.

AREAS COVERED

In this review, after a brief summary of current knowledge on the pathogenesis of aGVHD, the authors review the current combination of a calcineurin inhibitor with an antimetabolite with or without added anti-thymocyte globulin (ATG) and emerging strategies for GVHD prevention.

EXPERT OPINION

A new understanding of the involvement of cytokines, intracellular signaling pathways, epigenetics and immunoregulatory cells in GVHD pathogenesis will lead to new standards for aGVHD prophylaxis allowing better prevention of severe aGVHD without affecting graft-versus-tumor effects.

Downregulation of myeloma-induced ICOS-L and regulatory T cell generation by lenalidomide and dexamethasone therapy

Multiple myeloma (MM) produces significant cellular and humoral immune defects. We have previously reported that MM induces CD4(+)CD25(+)FoxP3(+) cells (TRegs), via tumour expression of the immune checkpoint regulator, ICOS-L. We sought to define what impact the immunomodulatory drug lenalidomide, alone or with dexamethasone, has on TReg cell generation. Lenalidomide pre-treatment of MM cell lines reduced TReg generation and the concomitant TReg:TEff (CD4(+)CD25(+)FoxP3(-): effector T cells) ratio, as a consequence of reduced ICOSL transcription. Dexamethasone did not affect surface ICOS-L expression but did induce TReg cell apoptosis without impacting on TEff cell survival. Combined lenalidomide and dexamethasone significantly reduced both TReg induction and the TReg:TEff cell ratio. In vivo, serial analysis of the TReg:TEff ratio in MM patients on lenalidomide-dexamethasone therapy revealed a progressive reduction towards age-matched control values, though not complete correction. Our data demonstrate for the first time immune synergism to explain the observed immune-modulation associated with lenalidomide-dexamethasone therapy.

Short Course of Post-Transplantation Cyclophosphamide and Bortezomib for Graft-versus-Host Disease Prevention after Allogeneic Peripheral Blood Stem Cell Transplantation Is Feasible and Yields Favorable Results: A Phase I Study

An effective graft-versus-host disease (GVHD) preventative approach that preserves the graft-versus-tumor effect after allogeneic hematopoietic stem cell transplantation (HSCT) remains elusive. Standard GVHD prophylactic regimens suppress T cells indiscriminately and are suboptimal. Conversely, post-transplantation high-dose cyclophosphamide selectively destroys proliferating alloreactive T cells, allows the expansion of regulatory T cells, and induces long-lasting clonal deletion of intrathymic antihost T cells. It has been successfully used to prevent GVHD after allogeneic HSCT. Bortezomib has antitumor activity on a variety of hematological malignancies and exhibits a number of favorable immunomodulatory effects that include inhibition of dendritic cells. Therefore, an approach that combines post-transplantation cyclophosphamide and bortezomib seems attractive. Herein, we report the results of a phase I study examining the feasibility and safety of high-dose post-transplantation cyclophosphamide in combination with bortezomib in patients undergoing allogeneic peripheral blood HSCT from matched siblings or unrelated donors after reduced-intensity conditioning. Cyclophosphamide was given at a fixed dose (50 mg/kg on days +3 and +4). Bortezomib dose was started at .7 mg/m2, escalated up to 1.3 mg/m2, and was administered on days 0 and +3. Patients receiving grafts from unrelated donors also received rabbit antithymocyte globulin. The combination was well tolerated and allowed prompt engraftment in all patients. The incidences of acute GVHD grades II to IV and grades III and IV were 20% and 6.7%, respectively. With a median follow-up of 9.1 months (range, 4.3 to 26.7), treatment-related mortality was 13.5% with predicted 2-year disease-free survival and overall survival of 55.7% and 68%, respectively. The study suggests that the combination of post-transplantation cyclophosphamide and bortezomib is feasible and may offer an effective and practical GVHD prophylactic regimen. The combination, therefore, merits further examination.

YSY01A, a Novel Proteasome Inhibitor, Induces Cell Cycle Arrest on G2 Phase in MCF-7 Cells via ERα and PI3K/Akt Pathways

Given that the proteasome is essential for multiple cellular processes by degrading diverse regulatory proteins, inhibition of the proteasome has emerged as an attractive target for anti-cancer therapy. YSY01A is a novel small molecule compound targeting the proteasome. The compound was found to suppress viability of MCF-7 cells and cause limited cell membrane damage as determined by sulforhodamine B assay (SRB) and CytoTox 96(®) non-radioactive cytotoxicity assay. High-content screening (HCS) further shows that YSY01A treatment induces cell cycle arrest on G2 phase within 24 hrs. Label-free quantitative proteomics (LFQP), which allows extensive comparison of cellular responses following YSY01A treatment, suggests that various regulatory proteins including cell cycle associated proteins and PI3K/Akt pathway may be affected. Furthermore, YSY01A increases p-CDC-2, p-FOXO3a, p53, p21(Cip1) and p27(Kip1) but decreases p-Akt, p-ERα as confirmed by Western blotting. Therefore, YSY01A represents a potential therapeutic for breast cancer MCF-7 by inducing G2 phase arrest via ERα and PI3K/Akt pathways.

Longitudinal analysis of patient-reported symptoms post-autologous stem cell transplant and their relationship to inflammation in patients with multiple myeloma

After autologous stem cell transplant (AuSCT), patients with multiple myeloma (MM) may receive lenalidomide maintenance therapy. This longitudinal study examined patient-reported symptom burden during the 3-9 months post-AuSCT and its association with maintenance therapy and circulating inflammatory markers. Fifty-one patients with MM rated symptom severity weekly using the MD Anderson Symptom Inventory MM module. When possible, blood for inflammatory marker assay was drawn at enrollment. Trajectory analysis identified clusters of patients who consistently reported higher or lower symptom severity. Although disease was relatively stable 3-9 months post-AuSCT, patients were not symptom-free: 35% were in the high-symptom group. Fatigue, pain, numbness/tingling, bone aches and muscle weakness were the most severe symptoms. Controlled for clinical variables, elevated baseline tumor necrosis factor-α (TNF-α) predicted high-symptom group membership (p = 0.014). Maintenance therapy and tumor response were not related to high symptom burden. Associations between inflammation and symptom burden in this exploratory study warrant further confirmatory study.

Electrophysiological, behavioral and histological characterization of paclitaxel, cisplatin, vincristine and bortezomib-induced neuropathy in C57Bl/6 mice

Polyneuropathy is a frequent and potentially severe side effect of clinical tumor chemotherapy. The goal of this study was to characterize paclitaxel-, cisplatin-, vincristine- and bortezomib-induced neuropathy in C57BL/6 mice with a comparative approach. The phenotype of the animals was evaluated at four time points with behavioral and electrophysiological tests, followed by histology. Treatment protocols used in this study were well tolerated and induced a sensory and predominantly axonal polyneuropathy. Behavioral testing revealed normal motor coordination, whereas all mice receiving verum treatment developed mechanical allodynia and distinct gait alterations. Electrophysiological evaluation showed a significant decrease of the caudal sensory nerve action potential amplitude for all cytostatic agents and a moderate reduction of nerve conduction velocity for cisplatin and paclitaxel. This finding was confirmed by histological analysis of the sciatic nerve which showed predominantly axonal damage: Paclitaxel and vincristine affected mostly large myelinated fibers, bortezomib small myelinated fibers and cisplatin damaged all types of myelinated fibers to a similar degree. Neuropathic symptoms developed faster in paclitaxel and vincristine treated animals compared to cisplatin and bortezomib treatment. The animal models in this study can be used to elucidate pathomechanisms underlying chemotherapy-induced polyneuropathy and for the development of novel therapeutic and preventative strategies.

Angiogenesis in multiple sclerosis and experimental autoimmune encephalomyelitis

Angiogenesis, the formation of new vessels, is found in Multiple Sclerosis (MS) demyelinating lesions following Vascular Endothelial Growth Factor (VEGF) release and the production of several other angiogenic molecules. The increased energy demand of inflammatory cuffs and damaged neural cells explains the strong angiogenic response in plaques and surrounding white matter. An angiogenic response has also been documented in an experimental model of MS, experimental allergic encephalomyelitis (EAE), where blood–brain barrier disruption and vascular remodelling appeared in a pre-symptomatic disease phase. In both MS and EAE, VEGF acts as a pro-inflammatory factor in the early phase but its reduced responsivity in the late phase can disrupt neuroregenerative attempts, since VEGF naturally enhances neuron resistance to injury and regulates neural progenitor proliferation, migration, differentiation and oligodendrocyte precursor cell (OPC) survival and migration to demyelinated lesions. Angiogenesis, neurogenesis and oligodendroglia maturation are closely intertwined in the neurovascular niches of the subventricular zone, one of the preferential locations of inflammatory lesions in MS, and in all the other temporary vascular niches where the mutual fostering of angiogenesis and OPC maturation occurs. Angiogenesis, induced either by CNS inflammation or by hypoxic stimuli related to neurovascular uncoupling, appears to be ineffective in chronic MS due to a counterbalancing effect of vasoconstrictive mechanisms determined by the reduced axonal activity, astrocyte dysfunction, microglia secretion of free radical species and mitochondrial abnormalities. Thus, angiogenesis, that supplies several trophic factors, should be promoted in therapeutic neuroregeneration efforts to combat the progressive, degenerative phase of MS.

Targeting the ubiquitin proteasome system in haematological malignancies

The ubiquitin proteasome system (UPS) plays a central role in cellular protein homeostasis through the targeted destruction of damaged/misfolded proteins and regulatory proteins that control critical cellular functions. The UPS comprises a sequential series of enzymatic activities to covalently attach ubiquitin to proteins to target them for degradation through the proteasome. Aberrancies within this system have been associated with transformation and tumourigenesis and thus, the UPS represents an attractive target for the development of anti-cancer therapies. The use of the first-in-class proteasome inhibitor, bortezomib, in the treatment of Plasma Cell Myeloma and Mantle Cell Lymphoma has validated the UPS as a therapeutic target. Following on its success, efforts are focused on the development of second-generation proteasome inhibitors and small molecule inhibitors of other components of the UPS. This review will provide an overview of the UPS and discuss current and novel therapies targeting the UPS.

Update on staphylococcal superantigen-induced signaling pathways and therapeutic interventions

Staphylococcal enterotoxin B (SEB) and related bacterial toxins cause diseases in humans and laboratory animals ranging from food poisoning, acute lung injury to toxic shock. These superantigens bind directly to the major histocompatibility complex class II molecules on antigen-presenting cells and specific Vβ regions of T-cell receptors (TCR), resulting in rapid hyper-activation of the host immune system. In addition to TCR and co-stimulatory signals, proinflammatory mediators activate signaling pathways culminating in cell-stress response, activation of NFκB and mammalian target of rapamycin (mTOR). This article presents a concise review of superantigen-activated signaling pathways and focuses on the therapeutic challenges against bacterial superantigens.