Antileukemic properties of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors

A chest CT-based nomogram for predicting survival in acute myeloid leukemia

BACKGROUND

The identification of survival predictors is crucial for early intervention to improve outcome in acute myeloid leukemia (AML). This study aim to identify chest computed tomography (CT)-derived features to predict prognosis for acute myeloid leukemia (AML).

METHODS

952 patients with pathologically-confirmed AML were retrospectively enrolled between 2010 and 2020. CT-derived features (including body composition and subcutaneous fat features), were obtained from the initial chest CT images and were used to build models to predict the prognosis. A CT-derived MSF nomogram was constructed using multivariate Cox regression incorporating CT-based features. The performance of the prediction models was assessed with discrimination, calibration, decision curves and improvements.

RESULTS

Three CT-derived features, including myosarcopenia, spleen_CTV, and SF_CTV (MSF) were identified as the independent predictors for prognosis in AML (P < 0.01). A CT-MSF nomogram showed a performance with AUCs of 0.717, 0.794, 0.796 and 0.792 for predicting the 1-, 2-, 3-, and 5-year overall survival (OS) probabilities in the validation cohort, which were significantly higher than the ELN risk model. Moreover, a new MSN stratification system (MSF nomogram plus ELN risk model) could stratify patients into new high, intermediate and low risk group. Patients with high MSN risk may benefit from intensive treatment (P = 0.0011).

CONCLUSIONS

In summary, the chest CT-MSF nomogram, integrating myosarcopenia, spleen_CTV, and SF_CTV features, could be used to predict prognosis of AML.

RHOA Therapeutic Targeting in Hematological Cancers

Primarily identified as an important regulator of cytoskeletal dynamics, the small GTPase Ras homolog gene family member A (RHOA) has been implicated in the transduction of signals regulating a broad range of cellular functions such as cell survival, migration, adhesion and proliferation. Deregulated activity of RHOA has been linked to the growth, progression and metastasis of various cancer types. Recent cancer genome-wide sequencing studies have unveiled both RHOA gain and loss-of-function mutations in primary leukemia/lymphoma, suggesting that this GTPase may exert tumor-promoting or tumor-suppressive functions depending on the cellular context. Based on these observations, RHOA signaling represents an attractive therapeutic target for the development of selective anticancer strategies. In this review, we will summarize the molecular mechanisms underlying RHOA GTPase functions in immune regulation and in the development of hematological neoplasms and will discuss the current strategies aimed at modulating RHOA functions in these diseases.

Ferroptosis in hematological malignancies and its potential network with abnormal tumor metabolism

Ferroptosis, a new type of regulated cell death, displays characteristics that transparently differ from apoptosis, autophagy and necroptosis. There is growing appreciation that targeting ferroptosis is potentially a novel strategy in anti-tumor therapy, especially for invasive malignancies demonstrating resistance to chemotherapy. Almost all types of cancer cells depend on abnormal metabolic activities to participate in vicious progression, giving the possibility to interfere with underlying metabolic preferences and compromise malignant cells by inducing ferroptosis. In this perspective, we give an overview of potential interactions between ferroptosis and abnormal tumor metabolism, with special focus on systematic researches in hematological malignancies.

Endocan in Acute Leukemia: Current Knowledge and Future Perspectives

Endocan is a soluble dermatan sulfate proteoglycan expressed by endothelial cells and detected in serum/plasma. Its expression is increased in tumors/tumor vessels in several human malignancies, and high expression (high serum/plasma levels or tumor levels) has an adverse prognostic impact in several malignancies. The p14 endocan degradation product can also be detected in serum/plasma, but previous clinical studies as well as previously unpublished results presented in this review suggest that endocan and p14 endocan fragment levels reflect different biological characteristics, and the endocan levels seem to reflect the disease heterogeneity in acute leukemia better than the p14 fragment levels. Furthermore, decreased systemic endocan levels in previously immunocompetent sepsis patients are associated with later severe respiratory complications, but it is not known whether this is true also for immunocompromised acute leukemia patients. Finally, endocan is associated with increased early nonrelapse mortality in (acute leukemia) patients receiving allogeneic stem cell transplantation, and this adverse prognostic impact seems to be independent of the adverse impact of excessive fluid overload. Systemic endocan levels may also become important to predict cytokine release syndrome after immunotherapy/haploidentical transplantation, and in the long-term follow-up of acute leukemia survivors with regard to cardiovascular risk. Therapeutic targeting of endocan is now possible, and the possible role of endocan in acute leukemia should be further investigated to clarify whether the therapeutic strategy should also be considered.

Targeting cholesterol homeostasis in hematopoietic malignancies

Cholesterol is a vital lipid for cellular functions. It is necessary for membrane biogenesis, cell proliferation and differentiation. In addition to maintaining cell integrity and permeability, increasing evidence indicates a strict link between cholesterol homeostasis, inflammation and haematological tumors. This makes cholesterol homeostasis an optimal therapeutic target for hematopoietic malignancies. Manipulating cholesterol homeostasis either interfering with its synthesis or activating the reverse cholesterol transport via the engagement of liver X receptors (LXRs), affects the integrity of tumor cells both in vitro and in vivo. Cholesterol homeostasis has also been manipulated to restore antitumor immune responses in preclinical models. These observations have prompted clinical trials in acute myeloid leukemia (AML) to test the combination of chemotherapy with drugs interfering with cholesterol synthesis, i.e. statins. We review the role of cholesterol homeostasis in hematopoietic malignancies, as well as in cells of the tumor microenvironment, and discuss the potential use of lipid modulators for therapeutic purposes.

Simvastatin enhances the efficacy of nilotinib in chronic myeloid leukaemia by post-translational modification and drug transporter modulation

The resistance of chronic myeloid leukaemia (CML) to tyrosine kinase inhibitors (TKIs) remains a significant clinical problem. Targeting alternative pathways, such as protein prenylation, is known to be effective in overcoming resistance. Simvastatin inhibits 3-hydroxy-3-methylglutaryl-CoA reductase (a key enzyme in isoprenoid-regulation), thereby inhibiting prenylation. We demonstrate that simvastatin alone effectively inhibits proliferation in a panel of TKI-resistant CML cell lines, regardless of mechanism of resistance. We further show that the combination of nilotinib and simvastatin synergistically kills CML cells via an increase in apoptosis and decrease in prosurvival proteins and cellular proliferation. Mechanistically, simvastatin inhibits protein prenylation as shown by increased levels of unprenylated Ras and rescue experiments with mevalonate resulted in abrogation of synergism. The combination also leads to an increase in the intracellular uptake and retention of radio-labelled nilotinib, which further enhances the inhibition of Bcr-Abl kinase activity. In primary CML samples, this combination inhibits clonogenicity in both imatinib-naive and resistant cells. Such combinatorial effects provide the basis for utilising these Food and Drug Administration-approved drugs as a potential clinical approach in overcoming resistance and improving CML treatment.

MDR reversal and pro-apoptotic effects of statins and statins combined with flavonoids in colon cancer cells

The resistance of cancer cells to a variety of structurally non-related cytotoxic drugs is known as multidrug resistance phenomenon (MDR). In cellular membranes an activity of MDR transporters such as P-glycoprotein (ABCB1) is affected by their lipid environment. Many various compounds have been examined for their ability to restore drug-sensitivity of resistant cancer cells. Statins, inhibitors of the key enzyme of mevalonate pathway HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase are drugs commonly prescribed in order to reduce serum level of cholesterol and to diminish the risk of cardiovascular disease. Statins as drugs that influence lipid composition of cell membrane and in that way they also exert influence on lipid bilayer properties appear to be good candidates as MDR modulators. In this work it was shown that statins - mevastatin and simvastatin exert antiproliferative, pro-apoptotic and reversing drug resistance effect in human colon adenocarcinoma cell line LoVo and its drug-resistant subline LoVo/Dx. A hypothesis was also checked whether flavones, which as it is well known are able to influence the biosynthesis of cholesterol, may change the anticancer activity of statins. Our investigations have revealed that combined use of statins and studied flavonoids results in enhanced cell growth inhibition and apoptosis and lower cancer cell proliferation as compared to the application only statins alone. Moreover, in drug resistant LoVo/Dx cells a stronger decrease of resistance to doxorubicine was observed in the presence of statins in combination with flavones as compared to the effect observed for statins only.

Acute Myeloid Leukemia: The Good, the Bad, and the Ugly

Acute myeloid leukemia (AML) was initially subdivided according to morphology (the French-American-British system), which proved helpful in pathologic categorization. Subsequently, clinical and genomic factors were found to correlate with response to chemotherapy and with overall survival. These included a history of antecedent hematologic disease, a history of chemotherapy or radiation therapy, the presence of various recurrent cytogenetic abnormalities, and, more recently, the presence of specific point mutations. This article reviews the biology and responses of one AML subgroup with consistent response and good outcomes following chemotherapy (core-binding factor leukemia), and two subgroups with persistently bad, and even ugly, outcomes (secondary AML and TP53-mutated AML).

Technological advances and proteomic applications in drug discovery and target deconvolution: identification of the pleiotropic effects of statins

Proteomic-based techniques provide a powerful tool for identifying the full spectrum of protein targets of a drug, elucidating its mechanism(s) of action, and identifying biomarkers of its efficacy and safety. Herein, we outline the technological advancements in the field, and illustrate the contribution of proteomics to the definition of the pharmacological profile of statins, which represent the cornerstone of the prevention and treatment of cardiovascular diseases (CVDs). Statins act by inhibiting 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, thus reducing cholesterol biosynthesis and consequently enhancing the clearance of low-density lipoproteins from the blood; however, HMG-CoA reductase inhibition can result in a multitude of additional effects beyond lipid lowering, known as 'pleiotropic effects'. The case of statins highlights the unique contribution of proteomics to the target profiling of a drug molecule.

The anti-leukemic and lipid lowering effects of imatinib are not hindered by statins in CML: a retrospective clinical study and in vitro assessment of lipid-genes transcription

Imatinib, which has revolutionized chronic myeloid leukemia (CML) treatment, was suggested to improve lipid profile. Statins, a dyslipidemia drug, were reported to potentiate imatinib's antileukemic effect. However, analysis of imatinib combined with statins is lacking. We have retrospectively analyzed the normalization period of bcr-abl, blood counts, and lipids in 40 CML patients, 19 of which co-treated with statins, during short (<12 months) and prolonged (>12 months) imatinib treatment. Prior statins treatment did not hinder nor sensitized imatinib's anti-leukemic and lipid-lowering effects. CML cells (K562) treated with 1μM imatinib (24-96 h) were further assessed for the expression of central lipid-related genes by real-time PCR. HMGCoAR, LDL-R, and apobec1 expressions were significantly increased while CETP declined after 48-96 h. To conclude, imatinib produces an independent favorable lipid profile, which is not hindered by statins and is partly mediated via transcription regulation of genes involved in the clearance of plasma lipids.

Blockade of the Ras/Raf/ERK and Ras/PI3K/Akt Pathways by Monacolin K Reduces the Expression of GLO1 and Induces Apoptosis in U937 Cells

Monacolin K, a hydrolytic product of icaritin, is the major active component in the traditional fermented Monascus purpureus. Monacolin K inhibits the proliferation of acute myeloid leukemia (AML), but underlying mechanisms remain to be identified. The present study demonstrates that monacolin K inhibits the proliferation of human AML cell line U937 in a dose-dependent manner. Importantly, morphological, DNA fragmentation, and image cytometry analyses indicated that monacolin K induced U937 cell apoptosis. Monacolin K could inactivate Ras translocation from cytosol to cell membrane. Monacolin K could also reduce the Ras-dependent phosphorylation of ERK and Akt, and the subsequent translocation of nuclear factor kappa B (NF-κB) from cytosol to nucleus in U937 cells. The underlying mechanisms of apoptotic activity of monacolin K were associated with inhibition of the Ras/Raf/ERK and Ras/PI3K/Akt signals and down-regulation of HMG-CoA reductase and glyoxalase 1. On the basis of results obtained using specific inhibitors U0126, LY294002, and JSH-23, the Ras/Raf/ERK/NF-κB/GLO1 and Ras/Akt/NF-κB/GLO1 pathways were proposed for the apoptotic effect of monacolin K in U937 cells.

Novel prospects of statins as therapeutic agents in cancer

Statins are well known competitive inhibitors of hydroxymethylglutaryl-CoA reductase enzyme (HMG-CoA reductase), thus traditionally used as cholesterol-lowering agents. In recent years, more and more effects of statins have been revealed. Nowadays alterations of lipid metabolism have been increasingly recognized as a hallmark of cancer cells. Consequently, much attention has been directed toward the potential of statins as therapeutic agents in the oncological field. Accumulated in vitro and in vivo clinical evidence point out the role of statins in a variety of human malignancies, in regulating tumor cell growth and anti-tumor immune response. Herein, we summarize and discuss, in light of the most recent observations, the anti-tumor effects of statins, underpinning the detailed mode of action and looking for their true significance in cancer prevention and treatment, to determine if and in which case statin repositioning could be really justified for neoplastic diseases.

The epigenetic drug 5-azacytidine interferes with cholesterol and lipid metabolism

DNA methylation and histone acetylation inhibitors are widely used to study the role of epigenetic marks in the regulation of gene expression. In addition, several of these molecules are being tested in clinical trials or already in use in the clinic. Antimetabolites, such as the DNA-hypomethylating agent 5-azacytidine (5-AzaC), have been shown to lower malignant progression to acute myeloid leukemia and to prolong survival in patients with myelodysplastic syndromes. Here we examined the effects of DNA methylation inhibitors on the expression of lipid biosynthetic and uptake genes. Our data demonstrate that, independently of DNA methylation, 5-AzaC selectively and very potently reduces expression of key genes involved in cholesterol and lipid metabolism (e.g. PCSK9, HMGCR, and FASN) in all tested cell lines and in vivo in mouse liver. Treatment with 5-AzaC disturbed subcellular cholesterol homeostasis, thereby impeding activation of sterol regulatory element-binding proteins (key regulators of lipid metabolism). Through inhibition of UMP synthase, 5-AzaC also strongly induced expression of 1-acylglycerol-3-phosphate O-acyltransferase 9 (AGPAT9) and promoted triacylglycerol synthesis and cytosolic lipid droplet formation. Remarkably, complete reversal was obtained by the co-addition of either UMP or cytidine. Therefore, this study provides the first evidence that inhibition of the de novo pyrimidine synthesis by 5-AzaC disturbs cholesterol and lipid homeostasis, probably through the glycerolipid biosynthesis pathway, which may contribute mechanistically to its beneficial cytostatic properties.