Statin-dependent modulation of mitochondrial metabolism in cancer cells is independent of cholesterol content

Statins, widely used to treat hypercholesterolemia, inhibit the 3-hydroxy-3-methylglutaryl-coenzyme A reductase, the rate-limiting enzyme of de novo cholesterol (Chol) synthesis. Statins have been also reported to slow tumor progression. In cancer cells, ATP is generated both by glycolysis and oxidative phosphorylation. Mitochondrial membrane potential (ΔΨ), a readout of mitochondrial metabolism, is sustained by the oxidation of respiratory substrates in the Krebs cycle to generate NADH and flavin adenine dinucleotide, which are further oxidized by the respiratory chain. Here, we studied the short-term effects of statins (3-24 h) on mitochondrial metabolism on cancer cells. Lovastatin (LOV) and simvastatin (SIM) increased ΔΨ in HepG2 and Huh7 human hepatocarcinoma cells and HCC4006 human lung adenocarcinoma cells. Mitochondrial hyperpolarization after LOV and SIM was dose and time dependent. Maximal increase in ΔΨ occurred at 10 µM and 24 h for both statins. The structurally unrelated atorvastatin also hyperpolarized mitochondria in HepG2 cells. Cellular and mitochondrial Chol remained unchanged after SIM. Both LOV and SIM decreased basal respiration, ATP-linked respiration, and ATP production. LOV and SIM did not change the rate of lactic acid production. In summary, statins modulate mitochondrial metabolism in cancer cells independently of the Chol content in cellular membranes without affecting glycolysis.-Christie, C. F., Fang, D., Hunt, E. G., Morris, M. E., Rovini, A., Heslop, K. A., Beeson, G. C., Beeson, C. C., Maldonado, E. N. Statin-dependent modulation of mitochondrial metabolism in cancer cells is independent of cholesterol content.

Transcriptional profiling of breast cancer cells in response to mevinolin: Evidence of cell cycle arrest, DNA degradation and apoptosis

The merging of high-throughput gene expression techniques, such as microarray, in the screening of natural products as anticancer agents, is considered the optimal solution for gaining a better understanding of the intervention mechanism. Red yeast rice (RYR), a Chinese dietary product, contains a mixture of hypocholesterolemia agents such as statins. Typically, statins have this effect via the inhibition of HMG-CoA reductase, the key enzyme in the biosynthesis of cholesterol. Recently, statins have been shown to exhibit various beneficial antineoplastic properties through the disruption of tumor angiogenesis and metastatic processes. Mevinolin (MVN) is a member of statins and is abundantly present in RYR. Early experimental trials suggested that the mixed apoptotic/necrotic cell death pathway is activated in response to MVN exposure. In the current study, the cytotoxic profile of MVN was evaluated against MCF-7, a breast cancer-derived cell line. The obtained results indicated that MVN-induced cytotoxicity is multi-factorial involving several regulatory pathways in the cytotoxic effects of MVN on breast cancer cell lines. In addition, MVN-induced transcript abundance profiles inferred from microarrays showed significant changes in some key cell processes. The changes were predicted to induce cell cycle arrest and reactive oxygen species generation but inhibit DNA repair and cell proliferation. This MVN-mediated multi-factorial stress triggered specific programmed cell death (apoptosis) and DNA degradation responses in breast cancer cells. Taken together, the observed MVN-induced effects underscore the potential of this ubiquitous natural compound as a selective anticancer activity, with broad safety margins and low cost compared to benchmarked traditional synthetic chemotherapeutic agents. Additionally, the data support further pre-clinical and clinical evaluations of MVN as a novel strategy to combat breast cancer and overcome drug resistance.

Changes of Apolipoprotein M Gene Expression During the Cell Differentiation and Apoptosis Induced by Simvastatin in Combination with All-Trans Retinoic Acid in Human Promyelocytic Leukemia Cell Line NB4

We examined the effect of simvastatin (SV) alone and in combination with all-trans retinoic acid (ATRA) on proliferation, differentiation, apoptosis and apolipoprotein M (apoM) expression in the human promyelocytic leukemia cell line NB4. The NB4 cells were incubated with 10 μM Simvastatin (10SV) and 0.5 μM ATRA alone or in combination, taking NB4 cells without any treatment as normal controls. The cells of different groups were collected at 24, 48 and 72 h post-incubation for further detection. Their morphological changes were observed after Wright stain. MTT method was used to assay the growth inhibition rate and flow cytometry to detect CD11b expression level and the early stage apoptosis ratio. Real-time quantitative reverse transcriptase-polymerase chain reaction was used to detect the apoM gene expression levels. As expected 0.5 μM ATRA did not affect proliferation or apoptosis, strongly induced differentiation and decreased apoM expression. 10SV inhibited proliferation, increased apoptosis, induced differentiation and increased apoM expression in a time-dependent manner. The addition of ATRA to SV did not increase the effect of SV on proliferation and apoptosis, but increased the effect of SV on differentiation. And completely abrogated the effect of SV on apoM expression. Together these results show that SV has anti-leukemic properties by itself and that combined therapy may have a place in the current anti-leukemic arsenal.

Retinoic acid promotes the endogenous repair of lung stem/progenitor cells in combined with simvastatin after acute lung injury: a stereological analysis

Background

The treatment of acute respiratory distress syndrome (ARDS), most commonly seen during the organ dysfunction remains unsatisfied. Presently, the stem/progenitor cell-based endogenous repair has been aroused attention enormously. This report investigated the effects of retinoic acid (RA) plus simvastatin (SS) with respect to dynamics of lung repair cells as well as to elucidate the underlying mechanism.

Materials and methods

The experimental Sprague–Dawley rats were divided randomly into normal control (control), sham operated (sham), ARDS, ARDS + vehicle and ARDS + RA + SS groups. ARDS was reproduced through hemorrhagic shock/resuscitation (shock) and subsequent intratracheal LPS (4.5 mg/kg, Escherichia coli serotype O55: B5) injection. The rats were treated by intragastric administration of RA (2 mg/kg/day) and SS (2 mg/kg/day) for 5 days in the ARDS + RA + SS group. Seven days after the first RA-SS injection, a right lower lobe of lung was sampled for histological analysis concerning systemic uniform random sampling method. Immunohistochemistry of inflation-fixed lungs for alveolar type 1 (AT1), alveolar type 2 (AT2) and Clara cells was measured by AQP5, Pro-SPC and CCSP staining respectively. The alveolar cell proliferation and apoptosis were analyzed with Ki67 staining and terminal deoxylnucleotidyl transferase mediated-dUTP nick end labeling (TUNEL) method. Meanwhile, the alveolar cell numerical and surface density (alveolar cells, AT1, AT2, Clara, proliferating and apoptotic cells) were evaluated by stereology.

Results

RA-SS compound exerted anti-inflammatory and pro-repairing effects on respiratory tracts in ARDS induced by hemorrhagic-endotoxin shock. The numerical density and surface density of alveolar cells, AT1 cell fraction, and numerical density of AT2 and Clara cells were significantly increased after treatment with RA-SS compound in ARDS. Concurrently, the Ki67+ alveolar cells were obviously increased while the TUNEL+ alveolar cells were reduced, which was correlated with the attenuation of inflammatory injury and functional repair in injured lung tissues.

Conclusions

Our data convincingly indicated that the prophylactic and therapeutic treatment of RA plus SS had obvious beneficial effect on the remodeling/regeneration of injured pulmonary tissues, suggesting that the underlying mechanisms are related to the re-balance between regeneration and apoptosis in lung stem/progenitor cells.

Suppressive effects of simvastatin on the human acute promyelocytic leukemia NB4 cell line through the regulation of the nuclear factor-κB signaling pathway

The present study examined the effects of simvastatin on the proliferation, apoptosis and gene expression levels involved in the nuclear factor-κB (NF-κB) signaling pathway in the human acute promyelocytic leukemia NB4 cell line by methyl thiazolyl tetrazolium assay, flow cytometry and the Human NF-κB Signaling Pathway RT² Profiler™ PCR Array profiles. The results showed that simvastatin significantly inhibited proliferation and induced apoptosis of the NB4 cells in a time- and dose-dependent manner. Changes were noted in the expression levels of 56 genes involved in the NF-κB signaling pathways in the NB4 cells treated with 15 μm simvastatin at 48 h post-incubation, among which, 47 genes were downregulated and 9 were upregulated. In conclusion, simvastatin potentially inhibits the proliferation and induces the apoptosis of NB4 cells through the regulation of the expression levels of genes involved in the NF-κB signaling pathway.

Statin-dependent activation of protein kinase Cδ in acute promyelocytic leukemia cells and induction of leukemic cell differentiation

Statins are HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase inhibitors, which block the conversion of HMG-CoA to mevalonate and have potent cholesterol lowering properties. Beyond their importance in the generation of lipid lowering effects, the regulatory effects of statins on the mevalonate pathway have a significant impact on multiple other cellular functions. There is now extensive evidence that statins have anti-inflammatory and anti-neoplastic properties, but the precise mechanisms by which such responses are generated are not well understood. In the present study we demonstrate that statins engage a member of the protein kinase C (PKC) family of proteins, PKCδ, in acute promyelocytic leukemia (APL) cells. Our study shows that atorvastatin and fluvastatin induce proteolytic activation of PKCδ in the APL NB4 cell line, which expresses the t(15;17) translocation. Such engagement of PKCδ results in induction of its kinase domain and downstream regulation of pathways important for statin-dependent leukemia cell differentiation. Our research shows that the function of PKCδ is essential for statin-induced leukemic cell differentiation, as demonstrated by studies involving selective targeting of PKCδ using siRNAs. We also demonstrate that the potent enhancing effects of statins on all-trans retinoic acid (ATRA)-induced gene expression for CCL3 and CCL4 requires the function of PKCδ, suggesting a mechanism by which statins may promote ATRA-induced antileukemic responses. Altogether, our data establish a novel function for PKCδ as a mediator of statin-induced differentiation of APL cells and antileukemic effects.

Anti-cancer characteristics of mevinolin against three different solid tumor cell lines was not solely p53-dependent

Mevinolin (MVN) has been used clinically for the treatment of hypercholesterolemia with very good tolerance by patients. Based on epidemiological evidences, MVN was suggested strongly for the treatment of neoplasia. Early experimental trials suggested the mixed apoptotic/necrotic cell death pathway was activated in response to MVN exposure. Herein, the cytotoxic profile of MVN was evaluated, compared to the robust and frequently used anti-cancer drug doxorubicin (DOX), against breast (MCF-7), cervical (HeLa) and liver (HepG(2)) transformed cell lines. MVN was showed comparable results in cytotoxic profile with DOX in all tested solid tumor cell lines. In addition, the MVN-induced cytotoxicity was inferred to be multi-factorial and not solely dependent on p53 expression. It was concluded that molecular and genetic assessment of MVN-induced cell death would be useful for developing cancer therapeutic treatments.

NCI60 cancer cell line panel data and RNAi analysis help identify EAF2 as a modulator of simvastatin and lovastatin response in HCT-116 cells

Simvastatin and lovastatin are statins traditionally used for lowering serum cholesterol levels. However, there exists evidence indicating their potential chemotherapeutic characteristics in cancer. In this study, we used bioinformatic analysis of publicly available data in order to systematically identify the genes involved in resistance to cytotoxic effects of these two drugs in the NCI60 cell line panel. We used the pharmacological data available for all the NCI60 cell lines to classify simvastatin or lovastatin resistant and sensitive cell lines, respectively. Next, we performed whole-genome single marker case-control association tests for the lovastatin and simvastatin resistant and sensitive cells using their publicly available Affymetrix 125K SNP genomic data. The results were then evaluated using RNAi methodology. After correction of the p-values for multiple testing using False Discovery Rate, our results identified three genes (NRP1, COL13A1, MRPS31) and six genes (EAF2, ANK2, AKAP7, STEAP2, LPIN2, PARVB) associated with resistance to simvastatin and lovastatin, respectively. Functional validation using RNAi confirmed that silencing of EAF2 expression modulated the response of HCT-116 colon cancer cells to both statins. In summary, we have successfully utilized the publicly available data on the NCI60 cell lines to perform whole-genome association studies for simvastatin and lovastatin. Our results indicated genes involved in the cellular response to these statins and siRNA studies confirmed the role of the EAF2 in response to these drugs in HCT-116 colon cancer cells.

VEGF targeted therapy in acute myeloid leukemia

The cooperation of two classes of mutations in hematopoietic cells is hypothesized in a multistep pathogenesis model of acute myeloid leukemia (AML). Class I mutations confer a proliferative and/or survival advantage, whereas Class II mutations block hematopoietic differentiation and impair apoptosis in AML cells. In addition to these two classes of mutations, a relevant role for angiogenesis in the pathophysiology of AML has been recently proposed. The recognition that the vascular endothelial growth factor (VEGF) pathway is a key regulator of angiogenesis has led to the development of several VEGF-targeted approaches. These include neutralizing antibodies, VEGF traps or selective tyrosine kinase inhibitors for VEGFRs. Other drugs that indirectly affect VEGF pathway, such as statins or arsenic trioxide, also have been shown to possess antiangiogenic activity in leukemias. The benefits of these VEGF targeted agents and their current stage of development as novel anti-antiangiogenic therapies in AML are discussed in this review.

Multidrug resistance strength of the novel multidrug resistance gene HA117: compared with MRP1

The novel gene HA117 is a multidrug resistance (MDR) gene in all-trans retinoic acid resistance HL-60 cells. The transduction of adenovirus vectors encoding HA117 conferred breast cancer cell line 4T1 MDR not only to MRP1 substrate drugs but also to MRP1 non-substrate drugs and the MDR strength of HA117 was similar to that of multidrug resistance-associated protein-1 (MRP1) for MRP1 substrate, but HA117 had no daunorubicin-excretion function.

Molecular mechanisms of toxicity of simvastatin, widely used cholesterol-lowering drug. A review

Statins are widely used and well tolerated cholesterol-lowering drugs, and when used for therapy purposes reduce morbidity and mortality from coronary heart disease. Simvastatin is one of nine known statins, specific inhibitors of hepatic enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase, the rate-limiting step of cholesterol biosynthesis, and is believed to reduce plasma cholesterol levels by decreasing the activity of this enzyme. Statin drugs represent the major improvement in the treatment of hypercholesterolemia that constitutes the main origin of atherosclerosis, leading to coronary heart disease. Although statins are generally safe, minor and severe adverse reactions are well known complications of statin use. Adverse events associated with simvastatin therapy are uncommon, but potentially serious. In this review some details about statins including their adverse effects in humans and animals, the effects of simvastatin on various intracellular and mitochondrial processes, and molecular mechanisms underlying simvastatin cytotoxicity are discussed.

HA117 gene increased the multidrug resistance of K562 cells in vitro: an investigation to the function of a novel gene related to drug resistance

OBJECTIVE

A novel multi-drug resistance gene named as HA117 has been screened and cloned in multidrug resisitant leukemia cell lines in our previous research, but its function is still unknown. In this study, HA117 gene was investigated whether it could increase the drug resistance in chronic myelogenous myeloid leukemia cell line K562.

METHODS

HA117 was cloned and adenovirus vectors were constructed with the HA117 gene (Adeasy-HA117). K562 cells were infected by Ad-HA117 to get the K562/Ad-HA117 cells with HA117 gene expression. The infection efficiency and the multiplicity of infection (MOI) were detected by fluorescence and flow cytometry. The expression of HA117 gene was detected by RT-PCR. The drug sensitivities of K562/Ad-HA117 cells were detected by Methyl Thiazolyl Tetrazolium (MTT) assay.

RESULTS

Recombinant adenovirus vectors were constructed and a MOI of 100 is most suitable to infect K562 cells. The infected K562 cells demonstrated in vitro production of HA117 mRNA as measured by reverse-transcriptase polymerase chain reaction. There were no significant changes in K562/Ad-HA117 cells growth, while the drug sensitivities of K562/Ad-HA117 cells to Vincristine, Adriamycin, Etoposide, Daunorubicin, Mitomycin and Cyclophosphamide decreased 4.44, 7.18, 3.01, 9.53, 3.48 and 3.61 times than that of uninfected K562 cells, respectively (P < 0.05).

CONCLUSION

Expression of the novel gene HA117 could significantly increased the multi-drug resistance of K562 cells, which indicated that HA117 is a functionally relevant multidrug resistance gene.