Co-administration of simvastatin and cytotoxic drugs is advantageous in myeloma cell lines

A phase 1 study of simvastatin in combination with topotecan and cyclophosphamide in pediatric patients with relapsed and/or refractory solid and CNS tumors

BACKGROUND

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) can inhibit tumor proliferation, angiogenesis, and restore apoptosis in preclinical pediatric solid tumor models. We conducted a phase 1 trial to determine the maximum tolerated dose (MTD) of simvastatin with topotecan and cyclophosphamide in children with relapsed/refractory solid and central nervous system (CNS) tumors.

METHODS

Simvastatin was administered orally twice daily on days 1-21, with topotecan and cyclophosphamide intravenously on days 1-5 of a 21-day cycle. Four simvastatin dose levels (DLs) were planned, 140 (DL1), 180 (DL2), 225 (DL3), 290 (DL4) mg/m2 /dose, with a de-escalation DL of 100 mg/m2 /dose (DL0) if needed. Pharmacokinetic and pharmacodynamic analyses were performed during cycle 1.

RESULTS

The median age of 14 eligible patients was 11.5 years (range: 1-23). The most common diagnoses were neuroblastoma (N = 4) and Ewing sarcoma (N = 3). Eleven dose-limiting toxicity (DLT)-evaluable patients received a median of four cycles (range: 1-6). There were three cycle 1 DLTs: one each grade 3 diarrhea and grade 4 creatine phosphokinase (CPK) elevations at DL1, and one grade 4 CPK elevation at DL0. All patients experienced at least one grade 3/4 hematologic toxicity. Best overall response was partial response in one patient with Ewing sarcoma (DL0) and stable disease for four or more cycles in four patients. Simvastatin exposure increased with higher doses and may have correlated with toxicity. Plasma interleukin 6 (IL-6) concentrations (N = 6) showed sustained IL-6 reductions with decrease to normal values by day 21 in all patients, indicating potential on-target effects.

CONCLUSIONS

The MTD of simvastatin with topotecan and cyclophosphamide was determined to be 100 mg/m2 /dose.

Time-dependent simvastatin administration enhances doxorubicin toxicity in neuroblastoma

Statins have a primary indication for the reduction and management of hypercholesterolemia; however, evidence shows that statins have the ability to increase the toxicity of chemotherapeutics within cancer cells by inducing anti-proliferative, anti-metastatic, and anti-angiogenic effects. More recently, lipophilic statins have shown complex interaction with energy metabolism, specifically acute mitochondrial dysfunction and delayed inhibition of glycolysis. With the goal to demonstrate that statin-mediated enhancement of chemotherapeutics is time-dependent, we hypothesized that the lipophilic statin simvastatin, in conjunction with variable co-exposure of doxorubicin or cisplatin, will enhance the toxicity of these drugs in neuroblastoma. Utilizing human SK-N-AS neuroblastoma cells, we assessed cell proliferation, necrosis, caspase activation, and overall apoptosis of these cells. After determining the toxicity of simvastatin at 48 h post-treatment, 10μM was chosen as the intervention concentration. We found that significant cell death resulted from 1.0μM dose of doxorubicin with 24 h pre-treatment of simvastatin. On the other hand, simvastatin enhancement of cisplatin toxicity was only observed in the co-exposure model. As doxorubicin has strict dosage limits due to its primary off-target toxicity in cardiac muscle, we further compared the effects of this drug combination on rat H9C2 cardiomyoblasts. We found that simvastatin did not enhance doxorubicin toxicity in this cell line. We conclude that simvastatin provides time-dependent sensitization of neuroblastoma cells to doxorubicin toxicity, and our results provide strong argument for the consideration of simvastatin as an adjuvant in doxorubicin-based chemotherapy programs.

Multiple myeloma and bone marrow mesenchymal stem cells' crosstalk: Effect on translation initiation

Multiple myeloma (MM) malignant plasma cells reside in the bone marrow (BM) and convert it into a specialized pre-neoplastic niche that promotes the proliferation and survival of the cancer cells. BM resident mesenchymal stem cells (BM-MSCs) are altered in MM and in vitro studies indicate their transformation by MM proximity is within hours. The response time frame suggested that protein translation may be implicated. Thus, we assembled a co-culture model of MM cell lines with MSCs from normal donors (ND) and MM patients to test our hypothesis. The cell lines (U266, ARP-1) and BM-MSCs (ND, MM) were harvested separately after 72 h of co-culture and assayed for proliferation, death, levels of major translation initiation factors (eIF4E, eIF4GI), their targets, and regulators. Significant changes were observed: BM-MSCs (ND and MM) co-cultured with MM cell lines displayed elevated proliferation and death as well as increased expression/activity of eIF4E/eIF4GI; MM cell lines co-cultured with MM-MSCs also displayed higher proliferation and death rates coupled with augmented translation initiation factors; in contrast, MM cell lines co-cultured with ND-MSCs did not display elevated proliferation only death and had no changes in eIF4GI levels/activity. eIF4E expression was increased in one of the cell lines. Our study demonstrates that there is direct dialogue between the MM and BM-MSCs populations that includes translation initiation manipulation and critically affects cell fate. Future research should be aimed at identifying therapeutic targets that may be used to minimize the collateral damage to the cancer microenvironment and limit its recruitment into the malignant process. © 2015 Wiley Periodicals, Inc.

Co-delivery of Sildenafil (Viagra(®)) and Crizotinib for synergistic and improved anti-tumoral therapy

PURPOSE

Cancer multi-drug resistance is a major issue associated with current anti-tumoral therapeutics. In this work, Crizotinib an anti-tumoral drug approved for the treatment of non-small lung cancer in humans, and Sildenafil (Viagra(®)), were loaded into micellar carriers to evaluate the establishment of a possible synergistic anti-tumoral effect in breast cancer cells.

METHODS

Micellar carriers comprised by PEG-PLA block co-polymers were formulated by the solvent displacement method in which the simultaneous encapsulation of Crizotinib and Sildenafil was promoted. Encapsulation efficiency was analyzed by a new UPLC method validated for this combination of compounds. Micelle physicochemical characterization and cellular uptake were characterized by light scattering and confocal microscopy. The bio- and hemocompatibility of the carriers was also evaluated. MCF-7 breast cancer cells were used to investigate the synergistic anti-tumoral effect.

RESULTS

Our results demonstrate that this particular combination induces massive apoptosis of breast cancer cells. The co-delivery of Crizotinib and Sildenafil was only possible due to the high encapsulation efficiency of the micellar systems (>70%). The micelles with size ranging between 93 and 127 nm were internalized by breast cancer cells and subsequently released their payload in the intracellular compartment. The results obtained demonstrated that the delivery of both drugs by micellar carriers led to a 2.7 fold increase in the anti-tumoral effect, when using only half of the concentration that is required when free drugs are administered.

CONCLUSIONS

Altogether, co-delivery promoted a synergistic effect and demonstrated for the first time the potential of PEG-PLA-Crizotinib-Sildenafil combination for application in cancer therapy.

Statins and cancer: current and future prospects

Statins are inhibitors of 3-hydroxy-methylglutaryl (HMG) CoA reductase. They exhibit effects beyond cholesterol reduction, including anticancer activity. This review presents the effects of statins in vitro and their possible molecular anticancer mechanisms and critically discusses the data regarding the role of statins in cancer prevention. Finally, this review focuses on the use of statins combined with other chemotherapeutics to increase the effectiveness of cancer treatments. Despite rare and inconclusive clinical data, the preclinical results strongly suggest that such combined treatment could be a promising new strategy for the treatment of certain tumor types.

Bevacizumab attenuates major signaling cascades and eIF4E translation initiation factor in multiple myeloma cells

Multiple myeloma (MM), a malignancy of plasma cells, remains fatal despite introduction of novel therapies, partially due to humoral factors, including vascular endothelial growth factor (VEGF), in their microenvironment. The aim of this study was to explore the efficacy of anti-VEGF treatment with bevacizumab directly on MM cells. Particular attention was directed to the affect of VEGF inhibition on protein translation initiation. Experiments were conducted on MM cells (lines, bone marrow (BM) samples) cultured on plastic. Inhibition of VEGF was achieved with the clinically employed anti-VEGF antibody, bevacizumab, as a platform and its consequences on viability, proliferation, and survival was assessed. VEGF downstream signals of established importance to MM cell biology were assayed as well, with particular emphasis on translation initiation factor eIF4E. We showed that blocking VEGF is deleterious to the MM cells and causes cytostasis. This was evidenced in MM cell lines, as well as in primary BM samples (BM MM). A common bevacizumab-induced attenuation of critical signaling effectors was determined: VEGFR1, mTOR, c-Myc, Akt, STAT3, (cell lines) and eIF4E translation initiation factor (lines and BM). ERK1/2 displayed a variegated response to bevacizumab (lines). Utilizing a constitutively Akt-expressing MM model, we showed that the effect of bevacizumab on viability and eIF4E status is Akt-dependent. Of note, the effect of bevacizumab was achieved with high concentrations (2 mg/ml), but was shown to be specific. These findings demonstrate that bevacizumab has a direct influence on major pathways critically activated in MM that is independent from its established effect on angiogenesis. The cytostatic effect of VEGF inhibition on MM cells underscores its potential in combined therapy, and our findings, regarding its influence on translation initiation, suggest that drugs that unbalance cellular proteostasis may be particularly effective.

Inhibition of geranylgeranylation mediates sensitivity to CHOP-induced cell death of DLBCL cell lines

Prenylation is a post-translational hydrophobic modification of proteins, important for their membrane localization and biological function. The use of inhibitors of prenylation has proven to be a useful tool in the activation of apoptotic pathways in tumor cell lines. Rab geranylgeranyl transferase (Rab GGT) is responsible for the prenylation of the Rab family. Overexpression of Rab GGTbeta has been identified in CHOP refractory diffuse large B cell lymphoma (DLBCL). Using a cell line-based model for CHOP resistant DLBCL, we show that treatment with simvastatin, which inhibits protein farnesylation and geranylgeranylation, sensitizes DLBCL cells to cytotoxic treatment. Treatment with the farnesyl transferase inhibitor FTI-277 or the geranylgeranyl transferase I inhibitor GGTI-298 indicates that the reduction in cell viability was restricted to inhibition of geranylgeranylation. In addition, treatment with BMS1, a combined inhibitor of farnesyl transferase and Rab GGT, resulted in a high cytostatic effect in WSU-NHL cells, demonstrated by reduced cell viability and decreased proliferation. Co-treatment of BMS1 or GGTI-298 with CHOP showed synergistic effects with regard to markers of apoptosis. We propose that inhibition of protein geranylgeranylation together with conventional cytostatic therapy is a potential novel strategy for treating patients with CHOP refractory DLBCL.

Relevance of the mevalonate biosynthetic pathway in the regulation of bone marrow mesenchymal stromal cell-mediated effects on T-cell proliferation and B-cell survival

BACKGROUND

Bone marrow mesenchymal stromal cells can suppress T-lymphocyte proliferation but promote survival of normal and malignant B cells, thus representing a possible target for new therapeutic schemes. Here we defined the effects of cholesterol synthesis inhibitors on the interaction between these mesenchymal stromal cells and T or B lymphocytes.

DESIGN AND METHODS

We exposed mesenchymal stromal cells to inhibitors, such as fluvastatin, of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase, responsible for the synthesis of mevalonate, the precursor of cholesterol. Also, these cells were treated with manumycin A, a farnesyl transferase inhibitor which blocks the mevalonate-dependent isoprenylation of small guanosin triphosphate binding proteins. First, mesenchymal stromal cell morphology, cytoskeleton assembly, cell cycle, survival and cytokine production were evaluated. Then, these cells were co-cultured with either T or B lymphocytes and we analyzed: 1) the inhibition of T-cell proliferation to mitogenic stimuli; 2) B-cell survival.

RESULTS

Fluvastatin altered the assembly of actin microfilaments, inactivated RhoA guanosin triphosphate binding protein, inhibited the S-phase of the cell cycle, induced apoptosis in a small fraction of cells but preserved cytokine production. Preincubation of mesenchymal stromal cells with fluvastatin, or manumycin A, down-regulated the expression of adhesion molecules, reduced cell-to-cell interactions and prevented the inhibition exerted by these stromal cells on CD3/T-cell receptor-induced lymphocyte proliferation. Mevalonic acid could revert morphological, phenotypic and functional effects of fluvastatin. Finally, fluvastatin significantly reduced the mesenchymal stromal cells-mediated rescue of B cells in the presence of dexamethasone, although it did not function in the absence of corticosteroids.

CONCLUSIONS

Fluvastatin-mediated effects on bone marrow mesenchymal stromal cells were conceivably due to the inhibition of isoprenylation of small guanosin triphosphate binding proteins, occurring for the lack of mevalonate. Altogether these findings suggest that drugs acting on the mevalonate biosynthetic pathway can regulate mesenchymal stromal cell-induced T-cell suppression and B-lymphocyte survival.

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.

Can cancer be reversed by engineering the tumor microenvironment?

To advance cancer research in a transformative way, we must redefine the problem. Although epithelial cancers, such as breast cancer, may be caused by random somatic gene mutations, the reality is that this is only one of many ways to induce tumor formation. Cancers also can be produced in experimental systems in vitro and in vivo, for example, by inducing sustained alterations of extracellular matrix (ECM) structure. Moreover, certain epithelial cancers can be induced to 'reboot' and regenerate normal tissue morphology when combined with embryonic mesenchyme or exogenous ECM scaffolds that are produced through epithelial-stromal interactions. At the same time, work in the field of Mechanical Biology has revealed that many cell behaviors critical for cancer formation (e.g., growth, differentiation, motility, apoptosis) can be controlled by physical interactions between cells and their ECM adhesions that alter the mechanical force balance in the ECM, cell and cytoskeleton. Epithelial tumor progression also can be induced in vitro by changing ECM mechanics or altering cytoskeletal tension generation through manipulation of the Rho GTPase signaling pathway. Mechanical interactions between capillary cells and ECM that are mediated by Rho signaling similarly mediate control of capillary cell growth and angiogenesis, which are equally critical for cancer progression and metastasis. These findings question basic assumptions in the cancer field, and raise the intriguing possibility that cancer may be a reversible disease that results from progressive deregulation of tissue architecture, which leads to physical changes in cells and altered mechanical signaling. This perspective raises the possibility of developing a tissue engineering approach to cancer therapy in which biologically inspired materials that mimic the embryonic microenvironment are used to induce cancers to revert into normal tissues.

Determinants of sensitivity to lovastatin-induced apoptosis in multiple myeloma

Statins, commonly used to treat hypercholesterolemia, have been shown to trigger tumor-specific apoptosis in certain cancers, including multiple myeloma (MM), a plasma cell malignancy with poor prognosis. In this article, we show that of a panel of 17 genetically distinct MM cell lines, half were sensitive to statin-induced apoptosis and, despite pharmacodynamic evidence of drug uptake and activity, the remainder were insensitive. Sensitive cells were rescued from lovastatin-induced apoptosis by mevalonate, geranylgeranyl PPi, and partially by farnesyl PPi, highlighting the importance of isoprenylation. Expression profiling revealed that Rho GTPase mRNAs were differentially expressed upon lovastatin exposure in sensitive cells, yet ectopic expression of constitutively active Rho or Ras proteins was insufficient to alter sensitivity to lovastatin-induced apoptosis. This suggests that sensitivity involves more than one isoprenylated protein and that statins trigger apoptosis by blocking many signaling cascades, directly or indirectly deregulated by the oncogenic lesions of the tumor cell. Indeed, clustering on the basis of genetic abnormalities was shown to be significantly associated with sensitivity (P = 0.003). These results suggest that statins may be a useful molecular targeted therapy in the treatment of a subset of MM.

Statins and cholesterol lowering after a cancer diagnosis: why not?

The pleiotropic effects of statins continue to garner attention. One area of interest that requires more attention is their potential, or that of another heart healthy agent, to impact favorably or inhibit the progression of numerous cancers, especially prostate cancer. Statins have accumulated a plethora of data in the area of general cancer cell line inhibition, and the potential to have a synergistic impact in patients receiving a variety of conventional treatments for a diversity of cancers is endorsed at least by laboratory and some preliminary small clinical studies. However, prostate cancer is unique compared to other cancers because, despite a high prevalence, some men choose watchful waiting or no treatment, especially if they are older and/or have a well-differentiated tumor. Thus, prostate cancer is a good candidate for the potential investigation of statins after diagnosis, with or without standard therapy. Regardless, because the number 1 or 2 cause of death in men with prostate cancer is cardiovascular disease than even in the worst-case scenario, these agents appear attractive for more immediate clinical study because they could impact a major cause of morbidity and mortality in these men. It is time to see the forest over the tree, and statins seem to have an argument as good as many other agents for allocating more money and time to test their ability as adjuvant therapy in a randomized trial or, in some cases, of nonaggressive disease as a potential monotherapy.