The cholesterol lowering drug lovastatin induces cell death in myeloma plasma cells

The insect microbiome is a vast source of bioactive small molecules

Covering: September 1964 to June 2023Bacteria and fungi living in symbiosis with insects have been studied over the last sixty years and found to be important sources of bioactive natural products. Not only classic producers of secondary metabolites such as Streptomyces and other members of the phylum Actinobacteria but also numerous bacteria from the phyla Proteobacteria and Firmicutes and an impressive array of fungi (usually pathogenic) serve as the source of a structurally diverse number of small molecules with important biological activities including antimicrobial, cytotoxic, antiparasitic and specific enzyme inhibitors. The insect niche is often the exclusive provider of microbes producing unique types of biologically active compounds such as gerumycins, pederin, dinactin, and formicamycins. However, numerous insects still have not been described taxonomically, and in most cases, the study of their microbiota is completely unexplored. In this review, we present a comprehensive survey of 553 natural products produced by microorganisms isolated from insects by collating and classifying all the data according to the type of compound (rather than the insect or microbial source). The analysis of the correlations among the metadata related to insects, microbial partners, and their produced compounds provides valuable insights into the intricate dynamics between insects and their symbionts as well as the impact of their metabolites on these relationships. Herein, we focus on the chemical structure, biosynthesis, and biological activities of the most relevant compounds.

Statin-induced Mitochondrial Priming Sensitizes Multiple Myeloma Cells to BCL2 and MCL-1 Inhibitors

The BCL2 inhibitor venetoclax promotes apoptosis in blood cancer cells and is approved for treatment of chronic lymphocytic leukemia and acute myeloid leukemia. However, multiple myeloma cells are frequently more dependent on MCL-1 for survival, conferring resistance to venetoclax. Here we report that mevalonate pathway inhibition with statins can overcome resistance to venetoclax in multiple myeloma cell lines and primary cells. In addition, statins sensitize to apoptosis induced by MCL-1 inhibitor, S63845. In retrospective analysis of venetoclax clinical studies in multiple myeloma, background statin use was associated with a significantly enhanced rate of stringent complete response and absence of progressive disease. Statins sensitize multiple myeloma cells to venetoclax by upregulating two proapoptotic proteins: PUMA via a p53-independent mechanism and NOXA via the integrated stress response. These findings provide rationale for prospective testing of statins with venetoclax regimens in multiple myeloma.

SIGNIFICANCE

BH3 mimetics including venetoclax hold promise for treatment of multiple myeloma but rational combinations are needed to broaden efficacy. This study presents mechanistic and clinical data to support addition of pitavastatin to venetoclax regimens in myeloma. The results open a new avenue for repurposing statins in blood cancer.

Protein acylation links metabolism and the control of signal transduction, transcription regulation, growth, and pathogenicity in Actinobacteria

Actinobacteria have a complex life cycle, including morphological and physiological differentiation which are often associated with the biosynthesis of secondary metabolites. Recently, increased interest in post-translational modifications (PTMs) in these Gram-positive bacteria has highlighted the importance of PTMs as signals that provide functional diversity and regulation by modifying proteins to respond to diverse stimuli. Here, we review the developments in research on acylation, a typical PTM that uses acyl-CoA or related metabolites as donors, as well as the understanding of the direct link provided by acylation between cell metabolism and signal transduction, transcriptional regulation, cell growth, and pathogenicity in Actinobacteria.

Pro-apoptotic complexes of BAX and BAK on the outer mitochondrial membrane

In multicellular organisms the regulated cell death apoptosis is critically important for both ontogeny and homeostasis. Mitochondria are indispensable for stress-induced apoptosis. The BCL-2 protein family controls mitochondrial apoptosis and initiates cell death through the pro-apoptotic activities of BAX and BAK at the outer mitochondrial membrane (OMM). Cellular survival is ensured by the retrotranslocation of mitochondrial BAX and BAK into the cytosol by anti-apoptotic BCL-2 proteins. BAX/BAK-dependent OMM permeabilization releases the mitochondrial cytochrome c (cyt c), which initiates activation of caspase-9. The caspase cascade leads to cell shrinkage, plasma membrane blebbing, chromatin condensation, and apoptotic body formation. Although it is clear that ultimately complexes of active BAX and BAK commit the cell to apoptosis, the nature of these complexes is still enigmatic. Excessive research has described a range of complexes, varying from a few molecules to several 10,000, in different systems. BAX/BAK complexes potentially form ring-like structures that could expose the inner mitochondrial membrane. It has been suggested that these pores allow the efflux of small proteins and even mitochondrial DNA. Here we summarize the current state of knowledge for mitochondrial BAX/BAK complexes and the interactions between these proteins and the membrane.

Undescribed Anti-inflammatory Thalysiaketides from Marine Sponge Clathria (Thalysias) vulpina (Lamarck, 1814)

Two undescribed polyketide type compounds, thalysiaketide A and thalysiaketide B were isolated from a sponge of marine origin Clathria (Thalysias) vulpina (Lamarck, 1814). Thalysiaketide A exhibited significantly greater inhibitory potential against inflammatory 5-lipoxygenase (IC50 0.87 mM) and cyclooxygense-2 (IC50 0.93 mM) compared to those revealed by its thalysiaketide B analogue (IC50 ≥ 1.05 mM). The 5-lipoxygenase inhibitory activity of thalysiaketide A was considerably superior to ibuprofen (standard, IC50 > 4 mM). Higher degree of polar belongings (topological polar surface area 93.06) in conjunction with relatively lower docking parameters of thalysiaketide A with the aminoacyl residues of cyclooxygense-2 and 5-lipoxygenase (docking score -12.99 and -12.27 kcal/mol, respectively) recognized its prospective anti-inflammatory potential.

The Lipoprotein Transport System in the Pathogenesis of Multiple Myeloma: Advances and Challenges

Multiple myeloma (MM) is an incurable neoplastic hematologic disorder characterized by malignant plasma cells, mainly in the bone marrow. MM is associated with multiple factors, such as lipid metabolism, obesity, and age-associated disease development. Although, the precise pathogenetic mechanisms remain unknown, abnormal lipid and lipoprotein levels have been reported in patients with MM. Interestingly, patients with higher APOA1 levels, the major apolipoprotein of high density lipoprotein (HDL), have better overall survival. The limited existing studies regarding serum lipoproteins in MM are inconclusive, and often contradictory. Nevertheless, it appears that deregulation of the lipoprotein transport system may facilitate the development of the disease. Here, we provide a critical review of the literature on the role of lipids and lipoproteins in MM pathophysiology. We also propose novel mechanisms, linking the development and progression of MM to the metabolism of blood lipoproteins. We anticipate that proteomic and lipidomic analyses of serum lipoproteins along with analyses of their functionality may improve our understanding and shed light on novel mechanistic aspects of MM pathophysiology.

Suppression of multiple myeloma by mitochondrial targeting

Treatment of multiple myeloma (MM) aims at inducing cell apoptosis by surpassing the limited capacity of MM cells to cope with oxidative stress. MM cell survival may further be suppressed by limiting cellular cholesterol. Long-chain fatty acid analogs of the MEDICA series promote mitochondrial stress and inhibit cholesterol biosynthesis, thus prompting us to verify their efficacy and mode-of-action in suppressing MM cell survival, in comparison to bortezomib. MEDICA analog is shown here to effectively suppress survival of MM cells, and to inhibit growth of MM xenograft. Suppression of MM cell survival by MEDICA is accompanied by inhibition of the STAT3, MAPK and the mTORC1 transduction pathways due to mitochondrial oxidative stress. MEDICA-induced oxidative stress is abrogated by added exogenous cholesterol. Suppression of MM cell survival by bortezomib is similarly driven by bortezomib-induced oxidative stress, being abrogated by added cholesterol. In line with that, the time-to-best-response of MM patients to bortezomib-based treatment protocols is shown to be positively correlated with their plasma cholesterol level. MEDICA profile may indicate novel therapeutic potential in the management of MM.

A double-blind, placebo-controlled, phase II, randomized study of lovastatin therapy in the treatment of mildly active rheumatoid arthritis

OBJECTIVES

3-hydroxy-3-methylglutaryl coenzyme-A (HMG Co-A) reductase inhibitors (statins) are standard treatment for hyperlipidaemia. In addition to lipid-lowering abilities, statins exhibit multiple anti-inflammatory effects. The objectives of this study were to determine whether treatment of patients with RA with lovastatin decreased CRP or reduced disease activity.

METHODS

We conducted a randomized double-blind placebo-controlled 12 week trial of lovastatin vs placebo in 64 RA patients with mild clinical disease activity but an elevated CRP. The primary efficacy end point was the reduction in mean log CRP. Secondary end points included disease activity, RF and anti-CCP antibody titres. Mechanistic end points included levels of serum cytokines. Safety was assessed; hepatic and muscle toxicities were of particular interest.

RESULTS

Baseline features were similar between groups. No significant difference in mean log CRP reduction between the two groups was observed, and disease activity did not change from baseline in either treatment group. Mechanistic analyses did not reveal significant changes in any biomarkers. A post hoc analysis of subjects not using biologic therapy demonstrated a significantly greater proportion achieving ⩾20% reduction in CRP from baseline in the lovastatin group compared with placebo (P-value = 0.007). No difference was observed in subjects receiving biologics. Lovastatin was well tolerated with no serious safety concerns.

CONCLUSION

This study showed no anti-inflammatory or clinical effects on RA disease activity after 12 weeks of treatment with lovastatin. Lovastatin had a modest effect on CRP in subjects not using biologics, suggesting statins may be anti-inflammatory in selected patients.

TRIAL REGISTRATION

ClinicalTrials.gov, http://clinicaltrials.gov, NCT00302952.

A liposome-micelle-hybrid (LMH) oral delivery system for poorly water-soluble drugs: Enhancing solubilisation and intestinal transport

A novel liposome-micelle-hybrid (LMH) carrier system was developed as a superior oral drug delivery platform compared to conventional liposome or micelle formulations. The optimal LMH system was engineered by encapsulating TPGS micelles in the aqueous core of liposomes and its efficacy for oral delivery was demonstrated using lovastatin (LOV) as a model poorly soluble drug with P-gp (permeability glycoprotein) limited intestinal absorption. LOV-LMH was characterised as unilamellar, spherical vesicles encapsulating micellar structures within the interior aqueous core and showing an average diameter below 200 nm. LMH demonstrated enhanced drug loading, water apparent solubility and extended/controlled release of LOV compared to conventional liposomes and micelles. LMH exhibited enhanced LOV absorption and transportation in a Caco-2 cell monolayer model of the intestine by inhibiting the P-gp transporter system compared to free LOV. The LMH system is a promising novel oral delivery approach for enhancing bioavailability of poorly water-soluble drugs, especially those presenting P-gp effluxes limited absorption.

The mevalonate pathway is an actionable vulnerability of t(4;14)-positive multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy that is often driven by chromosomal translocations. In particular, patients with t(4;14)-positive disease have worse prognosis compared to other MM subtypes. Herein, we demonstrated that t(4;14)-positive cells are highly dependent on the mevalonate (MVA) pathway for survival. Moreover, we showed that this metabolic vulnerability is immediately actionable, as inhibiting the MVA pathway with a statin preferentially induced apoptosis in t(4;14)-positive cells. In response to statin treatment, t(4;14)-positive cells activated the integrated stress response (ISR), which was augmented by co-treatment with bortezomib, a proteasome inhibitor. We identified that t(4;14)-positive cells depend on the MVA pathway for the synthesis of geranylgeranyl pyrophosphate (GGPP), as exogenous GGPP fully rescued statin-induced ISR activation and apoptosis. Inhibiting protein geranylgeranylation similarly induced the ISR in t(4;14)-positive cells, suggesting that this subtype of MM depends on GGPP, at least in part, for protein geranylgeranylation. Notably, fluvastatin treatment synergized with bortezomib to induce apoptosis in t(4;14)-positive cells and potentiated the anti-tumor activity of bortezomib in vivo. Our data implicate the t(4;14) translocation as a biomarker of statin sensitivity and warrant further clinical evaluation of a statin in combination with bortezomib for the treatment of t(4;14)-positive disease.

Attenuation of the pro-inflammatory signature of lung cancer-derived mesenchymal stromal cells by statins

Solid tumor growth triggers a dynamic host response, which recapitulates wound healing and defines the tumor microenvironment (TME). In addition to the action of the tumor cells themselves, the TME is maintained by a myriad of immune and stromal cell-derived soluble mediators and extracellular matrix components whose combined action supports tumor progression. However, therapeutic targeting of the TME has proven challenging because of incomplete understanding of the tumor-host crosstalk at the molecular level. Here, we investigated the crosstalk between mesenchymal stromal cells (MSCs) and primary cancer cells (PCCs) from human squamous cell lung carcinoma (SCC). We discovered that PCCs secrete CCL3 and stimulate IL-6, CCL2, ICAM-1 and VCAM-1 expression in MSCs and that the MSC-PCC crosstalk can be disrupted by the lipid-lowering drug simvastatin, which displays pleiotropic effects on cell metabolism and suppresses IL-6 and CCL2 production by MSCs and CCL3 secretion by PCCs. In addition, simvastatin inhibited spheroid formation by PCCs and negatively affected PCC survival. Our observations demonstrate that commonly used statins may be repurposed to target the TME in lung carcinoma.

Selenium and Zinc Biofortification of Pleurotus eryngii Mycelium and Fruiting Bodies as a Tool for Controlling Their Biological Activity

Pleurotus eryngii (DC:Fr.) Quel. is a cultivated mushroom of high culinary value and medicinal properties. Mycelium of P. eryngii is characterized by the ability of effective bio-elements absorption from growth media so it could be biofortified with trace elements with a functional activity in the human body. In this study, the ability of P. eryngii mycelia from in vitro cultures as well as fruiting bodies were investigated in terms of their effectiveness in zinc and selenium accumulation. The effect of Se and Zn biofortification on productivity, chemical compounds, and bio-elements content of P. eryngii was determined as well. To enhance Se and Zn content in P. eryngii fruiting bodies and mycelia, substrates were supplemented with sodium selenite, at a concentration of 50 mg L^-1, zinc sulfate, and zinc hydro-aspartate at a concentration of 87.2 and 100.0 mg L^-1, respectively. Mentioned Zn concentrations contained the same amount of zinc(II) ions, namely 20 mg L^-1. The content of organic compounds include phenolic compounds and lovastatin, which were determined by a high-performance liquid chromatography with diode-array detector (HPLC-DAD) and reverse phase high-performance liquid chromatography (RP-HPLC) method with UV detection. The ability of P. eryngii to accumulate zinc and selenium from the culture medium was demonstrated. The degree of accumulation of zinc turned out to be different depending on the type of salt used. The present study also showed that conducting mycelium of P. eryngii in in vitro culture, with a higher content of zinc ions, can result in obtaining the materials with better antioxidant ability. The results of this study can be used to develop the composition of growing media, which ensures the production of biomass with the desired composition of elements.

Proteasome inhibition in multiple myeloma: lessons for other cancers

Cellular protein homeostasis (proteostasis) depends on the controlled degradation of proteins that are damaged or no longer required by the ubiquitin-proteasome system (UPS). The 26S proteasome is the principal executer of substrate-specific proteolysis in eukaryotic cells and regulates a myriad of cellular functions. Proteasome inhibitors were initially developed as chemical tools to study proteasomal function but rapidly became widely used anticancer drugs that are now used at all stages of treatment for the bone marrow cancer multiple myeloma (MM). Here, we review the mechanisms of action of proteasome inhibitors that underlie their preferential toxicity to MM cells, focusing on endoplasmic reticulum stress, depletion of amino acids, and effects on glucose and lipid metabolism. We also discuss mechanisms of resistance to proteasome inhibition such as autophagy and metabolic rewiring and what lessons we may learn from the success and failure of proteasome inhibition in MM for treating other cancers with proteostasis-targeting drugs.

Biosynthesis of Polyketides in Streptomyces

Polyketides are a large group of secondary metabolites that have notable variety in their structure and function. Polyketides exhibit a wide range of bioactivities such as antibacterial, antifungal, anticancer, antiviral, immune-suppressing, anti-cholesterol, and anti-inflammatory activity. Naturally, they are found in bacteria, fungi, plants, protists, insects, mollusks, and sponges. Streptomyces is a genus of Gram-positive bacteria that has a filamentous form like fungi. This genus is best known as one of the polyketides producers. Some examples of polyketides produced by Streptomyces are rapamycin, oleandomycin, actinorhodin, daunorubicin, and caprazamycin. Biosynthesis of polyketides involves a group of enzyme activities called polyketide synthases (PKSs). There are three types of PKSs (type I, type II, and type III) in Streptomyces responsible for producing polyketides. This paper focuses on the biosynthesis of polyketides in Streptomyces with three structurally-different types of PKSs.

Effect of simvastatin on bovine intramuscular and subcutaneous adipocytes proliferation and gene expression in vitro

Simvastatin (SIM) is a widely used anticholesterolemic drug that blocks the biosynthesis of cholesterol. However, SIM also has pleiotropic effects on 3-hydroxy-3-methyglutary-CoA reductase (HMGR), cholesteryl ester transfer protein (CETP), and lipoprotein lipase (LPL), which are important genes in the cholesterol biosynthesis and transport processes. We investigated the effects of different concentrations of SIM on the mRNA expression of these genes in bovine intramuscular and subcutaneous adipocytes from the longissimus dorsi muscle and subcutaneous fat tissues of Luxi Yellow cattle. The results showed that SIM treatment showed dose-dependent toxicity on normal adipose cells, but no effect on cell proliferation. SIM decreased HMGR expression in a dose-dependent manner but showed no significant effect on CETP and LPL expression. Thus, SIM may lower the cholesterol content by decreasing the HMGR expression level, but CETP and LPL may be regulated through other mechanisms, which require further investigation.

In vitro susceptibility of cultured human methanogens to lovastatin

Lovastatin is a prodrug that is hydrolysed in vivo to β-hydroxy acid lovastatin, which inhibits 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-Co-A) reductase (HMGR), thereby lowering cholesterol in humans. A side effect of lovastatin is inhibition of isoprenoid synthesis and cell membrane formation in methanogenic Archaea, which are members of the human digestive tract microbiota and are emerging pathogens. In this study, the in vitro susceptibility of the human-associated methanogens Methanobrevibacter smithii, Methanobrevibacter oralis, Methanobrevibacter massiliense, Methanobrevibacter arboriphilus and Methanomassiliicoccus luminyensis to lovastatin (1-4 µg/mL) was tested in the presence of five gut anaerobes aiming to metabolise lovastatin into β-hydroxy acid lovastatin as confirmed by ultra-high-performance liquid chromatography. Five days of incubation with lovastatin had no measurable effect on the growth of the five gut anaerobes but significantly reduced CH₄ production and methanogen growth as measured by quantitative PCR (P <0.01). Quantitative PCR analyses indicated that compared with controls, β-hydroxy acid lovastatin significantly increased the expression of the genes mta and mcrA implicated in methanogenesis and significantly decreased the expression of the fno gene implicated in methanogenesis. Expression of the HMGR gene (hmg) implicated in cell wall synthesis was significantly increased by β-hydroxy acid lovastatin (P <0.01). These results strongly suggest that in the presence of gut anaerobes, lovastatin yields β-hydroxy acid lovastatin, which inhibits methane production and growth of methanogens by affecting their cell membrane biosynthesis. Lovastatin is the first licensed drug to exclusively affect the growth of methanogens whilst protecting the bacterial microbiota.

Ursolic acid-mediated apoptosis of K562 cells involves Stat5/Akt pathway inhibition through the induction of Gfi-1

Ursolic acid (UA) is a promising natural compound for cancer prevention and therapy. We previously reported that UA induced apoptosis in CML-derived K562 cells. Here we show that the apoptotic process is accompanied by down-regulation of Bcl-xL and Mcl-1 expression and dephosphorylation of Bad. These events are associated with Stat5 inhibition, which is partially mediated through elevated expression of transcriptional repressor Gfi-1. Gfi-1 knockdown using siRNA abrogates the ability of UA to decrease Stat5b expression and attenuates apoptosis induction by UA. We also demonstrate that UA suppresses the Akt kinase activity by inhibiting Akt1/2 expression, which correlates with Stat5 inhibition. Stat5 activity inhibited by a chemical inhibitor or siRNA, Akt1/2 mRNA expression is suppressed. Moreover, we show that UA exerts growth-inhibition in Imatinib-resistant K562/G01. UA has synergistic effects when used in combination with Imatinib in both K562 and K562/G01. Altogether, the data provide evidence that UA's pro-apoptotic effect in K562 cells is associated with the Gfi-1/Stat5/Akt pathway. The findings indicate that UA could potentially be a useful agent in the treatment of CML.

Simvastatin modulates mesenchymal stromal cell proliferation and gene expression

Statins are widely used hypocholesterolemic drugs that block the mevalonate pathway, responsible for the biosysnthesis of cholesterol. However, statins also have pleiotropic effects that interfere with several signaling pathways. Mesenchymal stromal cells (MSC) are a heterogeneous mixture of cells that can be isolated from a variety of tissues and are identified by the expression of a panel of surface markers and by their ability to differentiate in vitro into osteocytes, adipocytes and chondrocytes. MSC were isolated from amniotic membranes and bone marrows and characterized based on ISCT (International Society for Cell Therapy) minimal criteria. Simvastatin-treated cells and controls were directly assayed by CFSE (Carboxyfluorescein diacetate succinimidyl ester) staining to assess their cell proliferation and their RNA was used for microarray analyses and quantitative PCR (qPCR). These MSC were also evaluated for their ability to inhibit PBMC (peripheral blood mononuclear cells) proliferation. We show here that simvastatin negatively modulates MSC proliferation in a dose-dependent way and regulates the expression of proliferation-related genes. Importantly, we observed that simvastatin increased the percentage of a subset of smaller MSC, which also were actively proliferating. The association of MSC decreased size with increased pluripotency and the accumulating evidence that statins may prevent cellular senescence led us to hypothesize that simvastatin induces a smaller subpopulation that may have increased ability to maintain the entire pool of MSC and also to protect them from cellular senescence induced by long-term cultures/passages in vitro. These results may be important to better understand the pleiotropic effects of statins and its effects on the biology of cells with regenerative potential.

Bioactive lipids and the control of Bax pro-apoptotic activity

Lipids are key regulators of cell physiology through the control of many aspects of cellular life and survival. In particular, lipids have been implicated at different levels and through many different mechanisms in the cell death program called apoptosis. Here, we discuss the action of lipids in the regulation of the activation and the integration of Bax into the mitochondrial outer membrane, a key pro-apoptotic member of the BCL-2 family. We describe how, during apoptosis, lipids can act simultaneously or in parallel as receptors or ligands for Bax to stimulate or inhibit its pro-death activity.

Toll-like receptor (TLR)-1/2 triggering of multiple myeloma cells modulates their adhesion to bone marrow stromal cells and enhances bortezomib-induced apoptosis

In multiple myeloma (MM), the malignant plasma cells usually localize to the bone marrow where they develop drug resistance due to adhesion to stromal cells and various environmental signals. Hence, modulation of this interaction is expected to influence drug sensitivity of MM cells. Toll-like receptor (TLR) ligands have displayed heterogeneous effects on B-cell malignancies and also on MM cells in a few recent studies, but effects on adhesion and drug sensitivity of myeloma cells in the context of bone marrow stromal cells (BMSCs) have never been investigated. In the present study, we explored the modulatory effects of TLR1/2 ligand (Pam3CSK4) on adhesion of human myeloma cells to BMSCs. It is shown that TLR1/2 triggering has opposite effects in different HMCLs on their adhesion to BMSCs. Fravel, L363, UM-6, UM-9 and U266 showed increased adhesion to BMSC in parallel with an increased surface expression of integrin molecules α4 and αVβ3. OPM-1, OPM-2 and NCI-H929 showed a dose-dependent decrease in adhesion upon TLR activation following a downregulation of β7 integrin expression. Importantly, TLR1/2 triggering increased cytotoxic and apoptotic effects of bortezomib in myeloma cells independent of the effect on stromal cell adhesion. Moreover, the apoptosis-enhancing effect of Pam3CSK4 paralleled induction of cleaved caspase-3 protein in FACS analysis suggesting a caspase-dependent mechanism. Our findings uncover a novel role of TLR activation in MM cells in the context of bone marrow microenvironment. Stimulation of TLR1/2 bypasses the protective shield of BMSCs and may be an interesting strategy to enhance drug sensitivity of multiple myeloma cells.

Pharmacokinetics of high-dose simvastatin in refractory and relapsed chronic lymphocytic leukemia patients

PURPOSE

To evaluate the pharmacokinetics of simvastatin at the maximum tolerated dose (MTD) of 7.5 mg/kg, twice daily, in the context of a pilot trial enrolling patients with recurrent and refractory chronic lymphocytic leukemia.

METHODS

Patients received simvastatin orally at MTD for 7 days during a 21-day cycle for 6 cycles. Blood samples were collected during cycle 1. Simvastatin lactone and carboxylate concentrations were measured in plasma and peripheral blood mononuclear cells (PBMCs) using a validated HPLC-MS/MS assay.

RESULTS

Patients accrued to this study showed high variability in their exposure to simvastatin. Exposure was dose proportional (AUC and C max) as compared to those receiving standard hyperlipidemia therapy. Peak plasma concentrations ranged from 0.08 to 2.2 and from 0.03 to 0.6 μM for simvastatin lactone and carboxylate, respectively.

CONCLUSION

Our study shows that when simvastatin is administered at its MTD, only low micro-molar concentrations are achieved in plasma and PBMCs, which is consistent with the results observed in previous studies with lovastatin, but far lower than the concentrations required for anticancer effects in vitro. However, whether simvastatin at its MTD can confer therapeutic benefits to patients still remains to be determined.

Statins, Bcl-2, and apoptosis: cell death or cell protection?

Statins have proven their effectiveness in the treatment of cardiovascular disease. This class of drugs has also attracted attention as a potential treatment for dissimilar diseases such as certain types of cancers and neurodegenerative diseases. What appears to be a contradiction is that, in the case of cancer, it has been suggested that statins increase apoptosis and alter levels of Bcl-2 family members (e.g., reduce Bcl-2 and increase Bax), whereas studies mainly using noncancerous cells report opposite effects. This review examined studies reporting on the effects of statins on Bcl-2 family members, apoptosis, cell death, and cell protection. Much, but not all, of the evidence supporting the pro-apoptotic effects of statins is based on data in cancer cell lines and the use of relatively high drug concentrations. Studies indicating an anti-apoptotic effect of statins are fewer in number and generally used much lower drug concentrations and normal cells. Those conclusions are not definitive, and certainly, there is a need for additional research to determine if statin repositioning is justified for noncardiovascular diseases.

Lovastatin in Aspergillus terreus: fermented rice straw extracts interferes with methane production and gene expression in Methanobrevibacter smithii

Lovastatin, a natural byproduct of some fungi, is able to inhibit HMG-CoA (3-hydroxy-3methyl glutaryl CoA) reductase. This is a key enzyme involved in isoprenoid synthesis and essential for cell membrane formation in methanogenic Archaea. In this paper, experiments were designed to test the hypothesis that lovastatin secreted by Aspergillus terreus in fermented rice straw extracts (FRSE) can inhibit growth and CH₄ production in Methanobrevibacter smithii (a test methanogen). By HPLC analysis, 75% of the total lovastatin in FRSE was in the active hydroxyacid form, and in vitro studies confirmed that this had a stronger effect in reducing both growth and CH₄ production in M. smithii compared to commercial lovastatin. Transmission electron micrographs revealed distorted morphological divisions of lovastatin- and FRSE-treated M. smithii cells, supporting its role in blocking normal cell membrane synthesis. Real-time PCR confirmed that both commercial lovastatin and FRSE increased (P < 0.01) the expression of HMG-CoA reductase gene (hmg). In addition, expressions of other gene transcripts in M. smithii. with a key involvement in methanogenesis were also affected. Experimental confirmation that CH₄ production is inhibited by lovastatin in A. terreus-fermented rice straw paves the way for its evaluation as a feed additive for mitigating CH₄ production in ruminants.

Characterization of the Toll-like receptor expression profile in human multiple myeloma cells

Expression and function of Toll-like receptors (TLRs) in multiple myeloma (MM) has recently become the focus of several studies. Knowledge of expression and biology of these receptors in MM will provide us with a new insight into the role of an inflammatory environment in disease progression or pathogenesis of MM. However, to date a quite heterogeneous expression pattern of TLRs in MM particularly at gene level has been described while information on the TLR expression at the protein level is largely unavailable. In this study, we investigated the TLR expression in human myeloma cell lines (HMCLs) Fravel, L363, UM6, UM9, OPM1, OPM2, U266, RPMI 8226, XG1, and NCI H929 and primary cells from MM patients at both mRNA and protein level (western blot and flow cytometry). We found that all cell lines and primary cells expressed TLR1, TLR3, TLR4, TLR7, TLR8, and TLR9 mRNA and protein. TLR2 and TLR5 were expressed by the majority of HMCLs at mRNA but were not detectable at protein level, while primary samples showed a low level of TLR2, TLR3 and TLR5 protein expression. Our results indicate that MM cells express a broad range of TLRs with a degree of disparity between gene and protein expression pattern. The clear expression of TLRs in MM cells indicates a propensity for responding to tumor-induced inflammatory signals, which seem inevitable in the MM bone marrow environment.

Pentamidine sensitizes chronic myelogenous leukemia K562 cells to TRAIL-induced apoptosis

Pentamidine (PMD) is an anti-protozoa drug with potential anticancer activity. Here we show that PMD at clinically achievable plasma drug concentrations slightly inhibited the growth of human leukemia cell lines. PMD close to its therapeutic doses sensitized TRAIL-resistant K562 cells to the cytokine and potentiated TRAIL-induced apoptosis through activation of caspase-8 and -3. When we investigated the underlying mechanism, we observed that treatment with PMD increased DR5 expression at both mRNA and protein levels and down-regulated anti-apoptotic XIAP and Mcl-1 protein levels. This study provides a rationale for a more in-depth exploration into the combined treatment with PMD and TRAIL as a valuable strategy for leukemia therapy.

Effects of statins and farnesyl transferase inhibitors on ERK phosphorylation, apoptosis and cell viability in non-small lung cancer cells

OBJECTIVE

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) can affect post-translational processes, thus being responsible for decreased farnesylation and geranylgeranylation of intracellular small G proteins such as Ras, Rho and Rac, essential for cell survival and proliferation. In this regard, recent in vitro and in vivo studies suggest a possible role for both statins and farnesyl transferase inhibitors in the treatment of malignancies. Within such a context, the aim of our study was to investigate effects of either simvastatin (at concentrations of 1, 15, and 30 μm) or the farnesyl transferase inhibitor R115777 (at concentrations of 0.1, 1, and 10 μm), on two cultures of human non-small lung cancer cells, adenocarcinoma (GLC-82) and squamous (CALU-1) cell lines. In particular, we evaluated actions of these two drugs on phosphorylation of the ERK1/2 group of mitogen-activated protein kinases and on apoptosis, plus on cell numbers and morphology.

MATERIALS AND METHODS

Western blotting was used to detect ERK phosphorylation, and to assess apoptosis by evaluating caspase-3 activation; apoptosis was also further assessed by terminal deoxynucleotidyl-mediated dUTP nick end labelling (TUNEL) assay. Cell counting was performed after trypan blue staining.

RESULTS AND CONCLUSION

In both GLC-82 and CALU-1 cell lines, simvastatin and R115777 significantly reduced ERK phosphorylation; this effect, which reached the greatest intensity after 36 h treatment, was paralleled by a concomitant induction of apoptosis, documented by significant increase in both caspase-3 activation and TUNEL-positive cells, associated with a reduction in cell numbers. Our results thus suggest that simvastatin and R115777 may exert, in susceptible lung cancer cell phenotypes, a pro-apoptotic and anti-proliferative activity, which appears to be mediated by inhibition of the Ras/Raf/MEK/ERK signalling cascade.

Statins and downstream inhibitors of the isoprenylation pathway increase type 2 iodothyronine deiodinase activity

The type 2 iodothyronine selenodeiodinase (D2) is a critical determinant of local thyroid signaling, converting T(4) to the active form T(3) at the cytoplasmic face of the endoplasmic reticulum, thus supplying the nucleus with T(3) without immediately affecting circulating thyroid hormone levels. Although inhibitors of the cholesterol synthesis/isoprenylation pathway, such as hydroxy-methyl-glutaryl-coenzyme A reductase inhibitors (statins) have been to shown to down-regulate selenoproteins via interruption of normal selenocysteine incorporation, little is known about the effect of statins on D2. Here, we report that statins and prenyl transferase inhibitors actually increase D2 activity in cells with endogenous D2 expression. Although we confirmed that lovastatin (LVS) decreases the activity of transiently expressed D2 in HEK-293 cells, the prenyl transferase inhibitors increase activity in this system as well. LVS treatment increases endogenous Dio2 mRNA in MSTO-211H cells but does not alter transiently expressed Dio2 mRNA in HEK-293 cells. The prenyl transferase inhibitors do not increase Dio2 mRNA in either system, indicating that a posttranscriptional mechanism must exist. Cotreatment with LVS or the prenyl transferase inhibitors with the proteasome inhibitor MG-132 did not lead to additive increases in D2 activity, indirectly implicating the ubiquitin-proteasomal system in the mechanism. Finally, C57BL/6J mice treated with LVS or farnesyl transferase inhibitor-277 for 24 h exhibited increased D2 activity in their brown adipose tissue. These data indicate that statins and downstream inhibitors of the isoprenylation pathway may increase thyroid signaling via stimulation of D2 activity.

Treatment with high-dose simvastatin inhibits geranylgeranylation in AML blast cells in a subset of AML patients

It is currently unknown whether the in vitro effects observed with statins in acute myeloid leukemia (AML) cells, including lowering of cholesterol, inhibition of isoprenylation, and sensitization to chemotherapy, also occur in vivo. Therefore, AML mononuclear cells (MNCs) were isolated from 12 patients before and after 7 days of high-dose (7.5-15 mg/kg/day) simvastatin treatment. Parallel mouse studies were performed to have, in addition to AML cells, access to liver tissue, a major target of statins. Serum cholesterol levels were lowered by simvastatin in all patients, however, only limited changes in the messenger RNA expression of cholesterol metabolism genes were seen in patient and mouse MNCs compared to murine liver cells. Still, two out of seven patients displayed an increased in vitro chemosensitivity of their AML cells upon simvastatin treatment. Gene set enrichment analysis on microarray data of AML patient cells and Western blot analysis for the isoprenylated proteins DnaJ and Rap1 on murine and AML patient MNCs demonstrated that in vivo simvastatin treatment resulted in inhibition of geranylgeranylation in murine MNCs and in a subset of patient AML MNCs. In summary, our data demonstrate that simvastatin treatment results in chemosensitization and inhibition of geranylgeranylation in AML cells of a subset of patients.

Thalidomide, dexamethasone and lovastatin with autologous stem cell transplantation as a salvage immunomodulatory therapy in patients with relapsed and refractory multiple myeloma

The treatment of patients with multiple myeloma usually includes many drugs including thalidomide, lenalidomide and bortezomib. Lovastatin and other inhibitors of HMG-CoA reductase demonstrated to exhibit antineoplasmatic and proapoptotic properties in numerous in vitro studies involving myeloma cell lines. We treated 91 patients with relapsed or refractory multiple myeloma with thalidomide, dexamethasone and lovastatin (TDL group, 49 patients) or thalidomide and dexamethasone (TD group, 42 patients). A clinical response defined of at least 50% reduction of monoclonal band has been observed in 32% of TD patients and 44% of TDL patients. Prolongation of overall survival and progression-free survival in the TDL group as compared with the TD group has been documented. The TDL regimen was safe and well tolerated. The incidence of side effects was comparable in both groups. Plasma cells have been cultured in vitro with thalidomide and lovastatin to assess the impact of both drugs on the apoptosis rate of plasma cells. In vitro experiments revealed that the combination of thalidomide and lovastatin induced higher apoptosis rate than apoptosis induced by each drug alone. Our results suggest that the addition of lovastatin to the TD regimen may improve the response rate in patients with relapsed or refractory myeloma.

Low-density lipoprotein cholesterol suppresses apoptosis in human multiple myeloma cells

Multiple myeloma (MM) is an incurable disease accompanied by low plasma levels of low-density lipoprotein cholesterol (LDL-c). The significance of altered cholesterol metabolism in the pathophysiology of MM remains elusive. Although it has been hypothesized that myeloma cells depend on exogenous cholesterol for its survival, the role of LDL-c on myeloma cells has not been elucidated. To evaluate the impact of exogenous LDL-c on cell viability, three human myeloma cell lines (RPMI-8226, NCI-H929, and U-266B1) were grown in the presence or absence of lipoproteins. Cell viability was markedly reduced in the absence of lipoproteins in sera. However, exogenous LDL-c improved cell viability. We showed that reduced cell viability was associated with increased levels of cleaved caspase-3, whereas proliferation rate remained unchanged. Interestingly, exogenous LDL-c counteracted apoptosis in human myeloma cell lines and primary cultures of human myeloma cells. Thus, our results demonstrated that LDL-c is an important anti-apoptotic factor for myeloma cells and begin to explain the hypocholesterolemia observed in patients with MM.

In vitro anti-tumour activities of quinolizidine alkaloids derived from Sophora flavescens Ait

The dry root of Sophora flavescens Ait. (SF) has long been used in a variety of Chinese herbal formulations to treat patients with cancer. Alkaloids are commonly known to present in SF as main active constituents. Here, we report that among the six characterized SF-derived quinolizidine alkaloids including sophoridine, aloperine, sophocarpine, matrine, oxymatrine and cytisine, aloperine exerted the most potent in vitro cytotoxic activity against the human cancer cell lines and oxymatrine exhibited selective anti-cancer activity against hepatocellular carcinoma HepG2 cells. Analysis of DNA fragmentation and PARP cleavage revealed that aloperine treatment for 48 hr induced apoptosis in HL-60 cells. In addition, autophagic formation of acidic vacuole was also observed in HL-60 cells exposed to aloperine. These results suggest that aloperine may be a novel contributor to the anti-cancer properties of SF.

Simvastatin overcomes the resistance to serum withdrawal-induced apoptosis of lymphocytes from Alzheimer's disease patients

Statins may exert beneficial effects on Alzheimer's disease (AD) patients. Based on the antineoplastic and apoptotic effects of statins in a number of cell types, we hypothesized that statins may be able to protect neurons by controlling the regulation of cell cycle and/or apoptosis. A growing body of evidence indicates that neurodegeneration involves the cell-cycle activation in postmitotic neurons. Failure of cell-cycle control is not restricted to neurons in AD patients, but occurs in peripheral cells as well. For these reasons, we studied the role of simvastatin (SIM) on cell survival/death in lymphoblasts from AD patients. We report here that SIM induces apoptosis in AD lymphoblasts deprived of serum. SIM interacts with PI3K/Akt and ERK1/2 signaling pathways thereby decreasing the serum withdrawal-enhanced levels of the CDK inhibitor p21(Cip1) (p21) and restoring the vulnerability of AD cells to trophic factor deprivation.

Isoprenoid biosynthetic pathway inhibition disrupts monoclonal protein secretion and induces the unfolded protein response pathway in multiple myeloma cells

Myeloma is characterized by the overproduction and secretion of monoclonal protein. Inhibitors of the isoprenoid biosynthetic pathway (IBP) have pleiotropic effects in myeloma cells. To investigate whether IBP inhibition interferes with monoclonal protein secretion, human myeloma cells were treated with specific inhibitors of the IBP or prenyltransferases. These studies demonstrate that agents that inhibit Rab geranylgeranylation disrupt light chain trafficking, lead to accumulation of light chain in the endoplasmic reticulum, activate the unfolded protein response pathway and induce apoptosis. These studies provide a novel mechanism of action for IBP inhibitors and suggest that further exploration of Rab-targeted agents in myeloma is warranted.

Double impact on p-glycoprotein by statins enhances doxorubicin cytotoxicity in human neuroblastoma cells

The development of multidrug resistance (MDR) is a major problem during cancer treatment. Drug efflux via ATP-binding cassette (ABC) transporters is the main mechanism responsible for resistance to chemotherapeutics. We have recently observed that statins enhance susceptibility to doxorubicin-induced apoptosis in human rhabdomyosarcoma cells, which is now also observed in human SH-SY5Y neuroblastoma cells. We have therefore investigated the ABC transporter activity to confirm a possible inhibition by statins in SH-SY5Y cells. Indeed, simvastatin directly inhibited dye transport at equimolar concentrations of the ABC transporter inhibitor, verapamil. Making use of the fluorescence behavior of doxorubicin the accumulation of anthracycline was monitored in real-time confocal microscopy. The intracellular doxorubicin accumulation was immediately enhanced by statins in SH-SY5Y cells and also in a MYCN-amplified neuroblastoma cell line STA-NB-10. The heavily glycosylated P-glycoprotein (ABCB1, P-gp) transporter appeared as a 180-and 140-kDa species. Atorvastatin and simvastatin reduced the 180-kDa form of P-gp, but not verapamil. Thereby the fully glycosylated species is shifted to the core glycosylated species (140 kDa), which was only seen at statin exposure times longer than 24 hr. The functional importance of glycosylation of the transporter was highlighted by exogenous application of N-glycosidase F, which was sufficient to enhance doxorubicin accumulation. Hence, these novel findings of statins' dual impact on P-gp have clinical implications. The enhanced intracellular accumulation of chemotherapeutics or other ABC transporter substrates in the presence of statins may represent a novel concept to overcome MDR in cancer therapy and improve drug safety.

Lovastatin induces apoptosis of ovarian cancer cells and synergizes with doxorubicin: potential therapeutic relevance

Background

Ovarian carcinoma is a rarely curable disease, for which new treatment options are required. As agents that block HMG-CoA reductase and the mevalonate pathway, the statin family of drugs are used in the treatment of hypercholesterolemia and have been shown to trigger apoptosis in a tumor-specific manner. Recent clinical trials show that the addition of statins to traditional chemotherapeutic strategies can increase efficacy of targeting statin-sensitive tumors. Our goal was to assess statin-induced apoptosis of ovarian cancer cells, either alone or in combination with chemotherapeutics, and then determine these mechanisms of action.

Methods

The effect of lovastatin on ovarian cancer cell lines was evaluated alone and in combination with cisplatin and doxorubicin using several assays (MTT, TUNEL, fixed PI, PARP cleavage) and synergy determined by evaluating the combination index. The mechanisms of action were evaluated using functional, molecular, and pharmacologic approaches.

Results

We demonstrate that lovastatin induces apoptosis of ovarian cancer cells in a p53-independent manner and synergizes with doxorubicin, a chemotherapeutic agent used to treat recurrent cases of ovarian cancer. Lovastatin drives ovarian tumor cell death by two mechanisms: first, by blocking HMG-CoA reductase activity, and second, by sensitizing multi-drug resistant cells to doxorubicin by a novel mevalonate-independent mechanism. This inhibition of drug transport, likely through inhibition of P-glycoprotein, potentiates both DNA damage and tumor cell apoptosis.

Conclusions

The results of this research provide pre-clinical data to warrant further evaluation of statins as potential anti-cancer agents to treat ovarian carcinoma. Many statins are inexpensive, off-patent generic drugs that are immediately available for use as anti-cancer agents. We provide evidence that lovastatin triggers apoptosis of ovarian cancer cells as a single agent by a mevalonate-dependent mechanism. Moreover, we also show lovastatin synergizes with doxorubicin, an agent administered for recurrent disease. This synergy occurs by a novel mevalonate-independent mechanism that antagonizes drug resistance, likely by inhibiting P-glycoprotein. These data raise important issues that may impact how statins can best be included in chemotherapy regimens.

Simvastatin induces apoptosis of fibroblast-like synoviocytes

Background:

Statins (3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors) exert favorable effects on lipoprotein metabolism, but appeared to possess anti-inflammatory properties among others, as suggested by their ability to inhibit collagen-induced arthritis in mice. Their activity in fibroblast-like synovial cells (FLS) has not yet been studied.

Objectives:

To evaluate the effect of varying doses of simvastatin on apoptosis of FLS.

Methods:

Synovial tissue, obtained during total knee replacement due to osteoarthritis, was cut into small pieces and cultured in Petri dishes with test materials, as previously described. FLS were incubated for 48 hours with 1 μmol/ml, 5 μmol/ ml, 15 μmol/ml and 50 μmol/ml of simvastatin. Following incubation, apoptosis was analyzed by two-dimensional flow cytometry (FACS) using annexin V/PI staining according to the manufacturer’s instructions.

Results:

Different concentrations of simvastatin induced apoptosis of FLS. The level proportion of apoptotic cells of resting or activated with lipopolysaccharide (LPS; 3 μg/ml) FLS, not treated with simvastatin, was 21%. At 48 hours, the rate of apoptosis of activated fibroblasts, incubated with 1 μmol/ml, 5 μmol/ml, 15 and 50 μmol/ml was 22%, 32%, 48% and 41% respectively. Synovial cell viability evaluated by tetrazolium salt XXT was unaffected by the simvastatin concentration used.

Conclusion:

Varying concentrations of simvastatin induce apoptosis of activated fibroblast-like synoviocytes, suggesting another possible mechanism of anti-inflammatory effects of statins in inflammatory conditions.

Differential activities of thalidomide and isoprenoid biosynthetic pathway inhibitors in multiple myeloma cells

Thalidomide has emerged as an effective agent for treating multiple myeloma, however the precise mechanism of action remains unknown. Agents known to target the isoprenoid biosynthetic pathway (IBP) can have cytotoxic effects in myeloma cells. The interactions between thalidomide and IBP inhibitors in human multiple myeloma cells were evaluated. Enhanced cytotoxicity and induction of apoptosis were observed in RPMI-8226 cells. Examination of intracellular levels of farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) revealed a wide variance in basal levels and response to IBP inhibitors. These findings provide a mechanism for the differential sensitivity of myeloma cells to pharmacologic manipulation of the IBP.

Statin Use and Cancer Risk: An Epidemiologic Review

While the beneficial effects of hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on cardiovascular disease are well established, much uncertainty remains about their effects on cancer. The statins inhibit the rate-limiting step in the mevalonate pathway, leading to reduced levels of cholesterol and other molecules of importance for critical cellular processes. A growing body of preclinical data indicates that statins may have antineoplastic properties, but some studies raise the possibility that statins may possess a carcinogenic potential. Clinical and observational studies of the association between statin use and cancer have been inconclusive with regard to any chemopreventive or therapeutic effect, but they do provide reassuring evidence that statins do not appear to be carcinogenic. The reasons for the varying results are unclear but they may relate to methodological issues. Additional studies, including Phase II randomized trials and epidemiological studies with accurate measures of statin use and comprehensive control for confounding factors, are needed to determine the potentially beneficially effects of statins on cancer development and progression.

A phase II clinical trial does not show that high dose simvastatin has beneficial effect on markers of bone turnover in multiple myeloma

Several studies have evaluated the impact of low dose statin (20-80 mg/day) on bone metabolism with inconclusive results despite promising data of preclinical studies. In this study, we investigated the effect of high dose simvastatin (HD-Sim) on biochemical markers of bone turnover and disease activity in six heavily pretreated patients with multiple myeloma (MM). These patients were treated with simvastatin (15 mg/kg/day) for 7 days followed by a rest period of 21 days in two 4-week cycles. Endpoints were changes in the level of biochemical markers of (i) osteoclast activity (tartrate resistant acid phosphatase, TRACP); (ii) bone resorption (collagen fragments CTX and NTX); (iii) bone formation (osteocalcin and aminoterminal propeptide of type I collagen PINP); (iv) cholesterol; (v) regulators of bone metabolism [osteoprotegerin (OPG) and Dickkopf-1 (DKK-1)] and (vi) disease activity (monoclonal proteins or free light chains in serum). TRACP activity in serum and levels of collagen fragments (NTX) in urine increased for all patients temporarily during the 7 days of treatment with HD-Sim indicating that osteoclasts may have been stimulated rather than inhibited. The other markers of bone metabolism showed no change. None of the patients showed any reduction in free monoclonal light chains or monoclonal proteins in serum during treatment with HD-Sim. In spite of the fact that bone turn over effects of HD-Sim may have been blunted by concomitant treatment of patients with other drugs we observed a transient increase in markers of osteoclast activity. This sign of a transient stimulation of osteoclast activity suggests that HD-Sim may be harmful rather than beneficial for MM patients. For this reason and because of gastro-intestinal side effects the study was stopped prematurely.