Background & Aims
Nonalcoholic steatohepatitis (NASH) is a chronic and severe form of nonalcoholic fatty liver disease that can progress to cirrhosis and hepatocellular carcinoma and is a risk factor ...for cardiovascular disease. Although NASH has no approved treatments, obeticholic acid (OCA), a synthetic bile acid and farnesoid X receptor (FXR) agonist, was shown to improve histological features of NASH and fibrosis. Considering that FXR activation influences plasma lipoprotein concentrations, the Combination OCA aNd sTatins for monitoRing Of Lipids (CONTROL) study evaluated how statins can regulate lipoprotein metabolism with OCA treatment in patients with NASH.
Methods
This randomized, double‐blind, placebo‐controlled, phase 2 study began with a 5‐week screening/statin washout; 84 patients with NASH were randomly assigned (1:1:1:1) to receive placebo or 5 mg, 10 mg or 25 mg OCA once daily during the 16‐week double‐blind phase. Concurrent once daily atorvastatin (10 mg/days) was initiated at Week 4 with subsequent titration. Enrolled patients had biopsy‐confirmed diagnosis of NASH with no evidence of hepatic decompensation. Plasma was collected to analyse lipoprotein parameters.
Results
At Week 4, all OCA groups had an increase from baseline in mean low‐density lipoprotein cholesterol (LDLc) and mean LDL particle concentration (LDLpc), mostly owing to large, less atherogenic LDLc particles. Atorvastatin 10 mg decreased LDLc and LDLpc levels below baseline in all OCA groups by Week 8; higher doses did not provide additional clinical benefits.
Conclusions
The CONTROL study showed that OCA‐induced increases in LDLc in patients with NASH were mitigated with atorvastatin. The combination of OCA and atorvastatin was generally safe and well tolerated (NCT02633956).
Oxidatively modified proteins that accumulate in aging and many diseases can form large aggregates because of covalent cross-linking or increased surface hydrophobicity. Unless repaired or removed ...from cells, these oxidized proteins are often toxic, and threaten cell viability. Most oxidatively damaged proteins appear to undergo selective proteolysis, primarily by the proteasome. Previous work from our laboratory has shown that purified 20 S proteasome degrades oxidized proteins without ATP or ubiquitin in vitro, but there have been no studies to test this mechanismin vivo. The aim of this study was to determine whether ubiquitin conjugation is necessary for the degradation of oxidized proteins in intact cells. We now show that cells with compromised ubiquitin-conjugating activity still preferentially degrade oxidized intracellular proteins, at near normal rates, and this degradation is still inhibited by proteasome inhibitors. We also show that progressive oxidation of proteins such as lysozyme and ferritin does not increase their ubiquitinylation, yet the oxidized forms of both proteins are preferentially degraded by proteasome. Furthermore, rates of oxidized protein degradation by cell lysates are not significantly altered by addition of ATP, excluding the possibility of an energy requirement for this pathway. Contrary to earlier popular belief that most proteasomal degradation is conducted by the 26 S proteasome with ubiquitinylated substrates, our work suggests that oxidized proteins are degraded without ubiquitin conjugation (or ATP hydrolysis) possibly by the 20 S proteasome, or the immunoproteasome, or both.
The inverse relationship between adalimumab concentration and ATA positive in serum samples from non-responding patients treated with adalimumab. Display omitted
► The authors describe the use of the ...homogeneous mobility shift assay (HMSA). ► HMSA was used to measure adalimumab and antibodies-to-adalimumab (ATA). ► The HMSAs for adalimumab and ATA have high sensitivity, precision and accuracy. ► Non-responding patients showed high incidence of ATA generation (44%) using HMSA. ► In non-responding patients, levels of adalimumab and ATA were inversely associated.
This report describes the analytical validation and application of the homogeneous mobility shift assay (HMSA) method for the measurement of adalimumab and human antibodies-to-adalimumab (ATA) in serum samples from patients who have lost response to adalimumab treatment. Validation of the ATA- and the adalimumab-HMSA revealed a lower limit of detection to be 0.026U/mL for ATA and 0.018μg/mL for adalimumab in serum samples. Intra-assay and inter-assay precision determination yielded a coefficient of variation of less than 15%, and the accuracy of both assays was within 20%. Adalimumab drug tolerance in the ATA-HMSA was up to 20μg/mL in the test serum. Serum samples from 100 drug-naïve healthy subjects were tested to set-up the cut point of 0.55U/mL for ATA and 0.68μg/mL for adalimumab. Analysis of 100 serum samples from patients who were losing response to adalimumab showed that 26% had an adalimumab level below the cut point, of these 68% were ATA positive. Overall, 44% of the patients (44/100) were positive for ATA. This study presents evidence that drug and anti-drug antibody levels are important determinants of patient response to therapy.
Insulin-like growth factors and their receptor (IGF-1R) have been implicated in cancer pathophysiology. We demonstrate that IGF-1R is universally expressed in various hematologic (multiple myeloma, ...lymphoma, leukemia) and solid tumor (breast, prostate, lung, colon, thyroid, renal, adrenal cancer, retinoblastoma, and sarcoma) cells. Specific IGF-1R inhibition with neutralizing antibody, antagonistic peptide, or the selective kinase inhibitor NVP-ADW742 has in vitro activity against diverse tumor cell types (particularly multiple myeloma), even those resistant to conventional therapies, and triggers pleiotropic antiproliferative/proapoptotic molecular sequelae, delineated by global transcriptional and proteomic profiling. NVP-ADW742 monotherapy or its combination with cytotoxic chemotherapy had significant antitumor activity in an orthotopic xenograft MM model, providing in vivo proof of principle for therapeutic use of selective IGF-1R inhibitors in cancer.
Histone deacetylases (HDACs) affect cell growth at the transcriptional level by regulating the acetylation status of nucleosomal histones. HDAC inhibition induces differentiation and/or apoptosis in ...transformed cells. We recently showed that HDAC inhibitors, such as suberoylanilide hydroxamic acid (SAHA), potently induce apoptosis of human multiple myeloma (MM) cells. In this study, we focused on MM as a model to study the transcriptional profile of HDAC inhibitor treatment on tumor cells and to address their pathophysiological implications with confirmatory mechanistic and functional assays. We found that MM cells are irreversibly committed to cell death within few hours of incubation with SAHA. The molecular profile of MM cells before their commitment to SAHA-induced cell death is hallmarked by a constellation of antiproliferative and/or proapoptotic molecular events, including down-regulation of transcripts for members of the insulin-like growth factor (IGF)/IGF-1 receptor (IGF-1R) and IL-6 receptor (IL-6R) signaling cascades, antiapoptotic molecules (e.g., caspase inhibitors), oncogenic kinases, DNA synthesis/repair enzymes, and transcription factors (e.g., XBP-1, E2F-1) implicated in MM pathophysiology. Importantly, SAHA treatment suppresses the activity of the proteasome and expression of its subunits, and enhances MM cell sensitivity to proteasome inhibition by bortezomib (PS-341). SAHA also enhances the anti-MM activity of other proapoptotic agents, including dexamethasone, cytotoxic chemotherapy, and thalidomide analogs. These findings highlight the pleiotropic antitumor effects of HDAC inhibition, and provide the framework for future clinical applications of SAHA to improve patient outcome in MM.
This study examined the hypothesis that postischemic levels of oxidized and/or ubiquitinated proteins may be predictive of functional recovery as they may be indicative of activity of the 20S and/or ...26S proteasomes, respectively. Subjecting isolated rat hearts to 15 min of ischemia had no effect on 20S- and 26S-proteasome activities; however, both were significantly (p < 0.05) decreased by 70% and 54%, respectively, following 30 min of ischemia and 60 min of reperfusion, changes associated with increased levels of protein carbonyls and ubiquitinated proteins. Preischemic treatment of hearts with the proteasome inhibitor, MG132, resulted in dose-dependent decreases (p < 0.05) in recovery of postischemic function MG132 (microM), heart rate x pressure product: 0, 11,158 +/- 2,423; 6, 11,400 +/- 3,009; 12, 5,513 +/- 2,225; 25, 2,325 +/- 992 and increased accumulation of ubiquitinated proteins. Preconditioning with repetitive ischemia (IP) or preischemic treatment with nicorandil (Nic) resulted in a significant increase in postischemic 20S-proteasome activity after 60 min of reperfusion (control, 95 +/- 4; IP, 301 +/- 65; Nic, 242 +/- 61 fluorescence units). Only Nic had similar effects on 26S-proteasome activity. These results support the conclusion that a correlation exists between eventual recovery of postischemic function and levels of oxidized and/or ubiquitinated proteins, a phenomenon that may be dependent on activity of the 20S and 26S proteasomes.
Summary
The proteasome inhibitor bortezomib has shown impressive clinical activity alone and in combination with conventional and other novel agents for the treatment of multiple myeloma (MM). ...Although bortezomib is known to be a selective proteasome inhibitor, the downstream mechanisms of cytotoxicity and drug resistance are poorly understood. However, resistance to bortezomib as a single agent develops in the majority of patients, and activity in other malignancies has been less impressive. To elucidate mechanisms of bortezomib resistance, we compared differential gene expression profiles of bortezomib‐resistant SUDHL‐4 and bortezomib‐sensitive SUDHL‐6 diffuse large B‐cell lymphoma lines in response to bortezomib. At concentrations that effectively inhibited proteasome activity, bortezomib induced apoptosis in SUDHL‐6 cells, but not in SUDHL‐4 cells. We showed that overexpression of activating transcription factor 3 (ATF3), ATF4, ATF5, c‐Jun, JunD and caspase‐3 is associated with sensitivity to bortezomib‐induced apoptosis, whereas overexpression of heat shock protein (HSP)27, HSP70, HSP90 and T‐cell factor 4 is associated with bortezomib resistance.
Smac, second mitochondria-derived activator of caspases, promotes apoptosis via activation of caspases. Heat shock protein 27 (Hsp27) negatively regulates another mitochondrial protein, cytochrome c, ...during apoptosis; however, the role of Hsp27 in modulating Smac release is unknown. Here we show that Hsp27 is overexpressed in both dexamethasone (Dex)-resistant multiple myeloma (MM) cell lines (MM.1R, U266, RPMI-8226) and primary patient cells. Blocking Hsp27 by an antisense (AS) strategy restores the apoptotic response to Dex in Dex-resistant MM cells by triggering the release of mitochondrial protein Smac, followed by activation of caspase-9 and caspase-3. Moreover, AS-Hsp27 overcomes interleukin-6 (IL-6)-mediated protection against Dex-induced apoptosis. These data demonstrate that Hsp27 inhibits the release of Smac, and thereby confers Dex resistance in MM cells.
We tested the in vitro and in vivo antitumor activity of the maytansinoid DM1 (N2′-deacetyl-N2′-(3-mercapto-1-oxopropyl)-maytansine), a potent antimicrotubule agent, covalently linked to the murine ...monoclonal antibody (mAb) B-B4 targeting syndecan-1 (CD138). We evaluated the in vitro activity of B-B4–DM1 against a panel of CD138+ and CD138- cell lines, as well as CD138+ patient multiple myeloma (MM) cells. Treatment with B-B4–DM1 selectively decreased growth and survival of MM cell lines, patient MM cells, and MM cells adherent to bone marrow stromal cells. We further examined the activity of B-B4–DM1 in 3 human MM models in mice: (1) severe combined immunodeficient (SCID) mice bearing subcutaneous xenografts; (2) SCID mice bearing green fluorescent protein–positive (GFP+) xenografts; and (3) SCID mice implanted with human fetal bone (SCID-hu) and subsequently injected with patient MM cells. Tumor regression and inhibition of tumor growth, improvement in overall survival, and reduction in levels of circulating human paraprotein were observed in mice treated with B-B4–DM1. Although immunohistochemical analysis demonstrates restricted CD138 expression in human tissues, the lack of B-B4 reactivity with mouse tissues precludes evaluation of its toxicity in these models. In conclusion, B-B4–DM1 is a potent anti-MM agent that kills cells in an antigen-dependent manner in vitro and mediates in vivo antitumor activity at doses that are well tolerated, providing the rationale for clinical trials of this immunoconjugate in MM.
We recently demonstrated that caveolae, vesicular flask-shaped invaginations of the plasma membrane, represent novel therapeutic targets in multiple myeloma. In the present study, we demonstrate that ...vascular endothelial growth factor (VEGF) triggers Src-dependent phosphorylation of caveolin-1, which is required for p130(Cas) phosphorylation and multiple myeloma cell migration. Conversely, depletion of caveolin-1 by antisense methodology abrogates p130(Cas) phosphorylation and VEGF-triggered multiple myeloma cell migration. The proteasome inhibitor bortezomib both inhibited VEGF-triggered caveolin-1 phosphorylation and markedly decreased caveolin-1 expression. Consequently, bortezomib inhibited VEGF-induced multiple myeloma cell migration. Bortezomib also decreased VEGF secretion in the bone marrow microenvironment and inhibited VEGF-triggered tyrosine phosphorylation of caveolin-1, migration, and survival in human umbilical vascular endothelial cells. Taken together, these studies demonstrate the requirement of caveolae for VEGF-triggered multiple myeloma cell migration and identify caveolin-1 in multiple myeloma cells and human umbilical vascular endothelial cells as a molecular target of bortezomib.
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