HMG-CoA reductase inhibitors as adjuvant treatment for hematologic malignancies: what is the current evidence?

The impact of oral hypoglycemics and statins on outcomes in myelodysplastic syndromes

Observational studies suggest an anti-neoplastic effect associated with statins, metformin, and dipeptidyl peptidase-4 inhibitors (DPP4i), while sulfonylureas may have a neutral or detrimental effect. We linked the Ontario subset of a prospective Canadian myelodysplastic syndromes (MDS) registry with provincial administrative databases. We assessed the impact of statin/oral hypoglycemic medication exposure on overall survival (OS) using Cox regression analysis, controlling for comorbidities and sociodemographic factors. Five hundred thirty-three patients aged ≥ 66 years were included: 49.3% used statins, 18.9% used metformin, 9.0% used sulfonylureas, and 6.4% used DPP4i. Three hundred ninety-five patients were lower-risk based on the International Prognostic Scoring System. On univariate analysis, we identified a marginal improvement in OS in the lower-risk group using DPP4i (HR 0.98, 95% CI 0.95-1.00, P = 0.05), while there was no impact on mortality for higher-risk DPP4i users (HR 1.03, CI 0.99-1.07, P = 0.21). There was no mortality difference for statins (HR 1.00, CI 1.00-1.01, P = 0.93), metformin (HR 1.00, CI 0.99-1.01, P = 0.81), or sulfonylureas (HR 1.00, CI 0.99-1.02, P = 0.43) in the entire cohort, as well as when stratified into lower/higher-risk groups. On multivariable analysis in the lower-risk group, there was no association between DPP4i and OS (HR 0.98, CI 0.95-1.00, P = 0.06). Prospective studies with larger cohorts of patients and longer follow-up are required to further study the impact of DPP4i in MDS.

Systems biology drug screening identifies statins as enhancers of current therapies in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a B lymphoid malignancy highly dependent on the microenvironment. Despite new targeted therapies such as ibrutinib and venetoclax, disease progression and relapse remain an issue. CLL cell interactions with the supportive tissue microenvironment play a critical role in disease pathogenesis. We used a platform for drug discovery based on systems biology and artificial intelligence, to identify drugs targeting key proteins described to have a role in the microenvironment. The selected compounds were screened in CLL cell lines in the presence of stromal cells to mimic the microenvironment and validated the best candidates in primary CLL cells. Our results showed that the commercial drug simvastatin was the most effective and selective out of the tested compounds. Simvastatin decreased CLL cell survival and proliferation as well as cell adhesion. Importantly, this drug enhanced the antitumor effect of venetoclax and ibrutinib. We proposed that systems biology approaches combined with pharmacological screening could help to find new drugs for CLL treatment and to predict new combinations with current therapies. Our results highlight the possibility of repurposing widely used drugs such as statins to target the microenvironment and to improve the efficacy of ibrutinib or venetoclax in CLL cells.

Cholesterol depletion sensitizes gallbladder cancer to cisplatin by impairing DNA damage response

Gallbladder cancer (GBC) is the common malignancy of the bile tract system with extremely poor clinical outcomes, owing to its metastatic property and intrinsic resistance to the first-line drugs. Although it is well-established that cholesterol abnormity contributes to gallstone formation, a leading risk factor for GBC, the link of cholesterol homeostasis with GBC has not been investigated. The present study systematically examined the genes implicated in cholesterol homeostasis, and revealed altered gene expressions of de novo cholesterol biosynthesis and sterol sulfonation (SULT2B1), reduced bile acid synthesis (CYP7B1 and CYP39A1) and impaired sterol efflux (ABCA1, ABCG5, LCAT, and CETP) in GBC tissues. Suppression of cholesterol biosynthesis by lovastatin inhibited GBC cell proliferation possibly through attenuating the DNA repair process. Further investigation revealed lovastatin sensitized GBC cells to cisplatin-induced apoptosis and suppressed the activation of CHK1, CHK2, and H2AX during DNA damage response. By using chemically distinct statins, HMGCR depletion or supplementing mevalonate, the product of HMGCR, we showed the inhibitory effects on DNA repair process of lovastatin were due to the blockage of the mevalonate pathway. Subcutaneous xenograft mice model suggested lovastatin promoted the therapeutic efficacy of cisplatin, and significantly prolonged the survival times of tumor-bearing mice. Moreover, HMGCR ablation repressed tumor growth in vivo, which can be rescued partially by restored expression of HMGCR, suggesting the on-target effects of lovastatin. Therefore, our study provides the clinical relevance of cholesterol homeostasis with GBC progression, and highlights a novel intervention of combined use of lovastatin and cisplatin for GBC.

Statins enhance efficacy of venetoclax in blood cancers

Statins have shown promise as anticancer agents in experimental and epidemiologic research. However, any benefit that they provide is likely context-dependent, for example, applicable only to certain cancers or in combination with specific anticancer drugs. We report that inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) using statins enhances the proapoptotic activity of the B cell lymphoma-2 (BCL2) inhibitor venetoclax (ABT-199) in primary leukemia and lymphoma cells but not in normal human peripheral blood mononuclear cells. By blocking mevalonate production, HMGCR inhibition suppressed protein geranylgeranylation, resulting in up-regulation of proapoptotic protein p53 up-regulated modulator of apoptosis (PUMA). In support of these findings, dynamic BH3 profiling confirmed that statins primed cells for apoptosis. Furthermore, in retrospective analyses of three clinical studies of chronic lymphocytic leukemia, background statin use was associated with enhanced response to venetoclax, as demonstrated by more frequent complete responses. Together, this work provides mechanistic justification and clinical evidence to warrant prospective clinical investigation of this combination in hematologic malignancies.

Inhibitory effect of simvastatin in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is one of the most common malignant head and neck cancers in southern China. Although the local and regional control of NPC has been considerably improved, patients with advanced disease still suffer from poor prognosis. Statins inhibit the mevalonate pathway and play antiproliferative and proapoptotic roles in a number of cancer cells. However, the effects and molecular mechanism of statins in NPC treatment remain unclear. In this study, the cell viability of NPC cell line, C666-1, after simvastatin exposure was determined using the alamarBlue Cell Viability Assay. Cell apoptosis in C666-1 treated with simvastatin was assessed by flow cytometry and TUNEL assay. The expression levels of cell cycle regulatory proteins were determined using western blotting. Simvastatin markedly decreased cell viability in a concentration-dependent manner, increased caspase 3 activity and induced apoptosis in C666-1 cells. Simvastatin induced Bim expression by regulating phosphorylation of transcriptional factor c-Jun. Simvastatin treatment induced cell cycle arrest in the G1 phase in C666-1 cells by inhibiting the expression of cyclin D1 and cyclin-dependent kinase 4, and enhancing p27 expression. Simvastatin treatment inhibited protein kinase B and extracellular signal regulated kinase 1/2 activation. In conclusion, the results of the present study reveal the possible molecular mechanism of simvastatin-induced anti-tumor effects in C666-1 and suggest that simvastatin is a potential chemotherapy agent in NPC treatment.

Statins may have double-edged effects in patients with lung adenocarcinoma after lung resection

Purpose: The epithelial to mesenchymal transition (EMT) is pivotal for driving metastasis and recurrence in lung cancer. Some in vitro reports have shown that statins suppress EMT by inactivating mutant p53 functions. Several clinical trials of conventional treatments with statins have been performed, but the effect of these drugs on prognosis is still uncertain. The purpose of this study is to examine the impact of statins on EMT and the prognosis of patients with lung adenocarcinoma.

Materials and methods: Morphological changes were evaluated and EMT markers (E-cadherin, vimentin) were analyzed by Western blotting in p53-overexpressing H1650 and mutant p53-harboring H1975 lung adenocarcinoma cells, with and without simvastatin administration. The invasive ability of these cells was analyzed in a Matrigel chemoinvasion assay. A total of 250 lung adenocarcinoma specimens were also collected from patients who underwent surgery in our institute. EMT markers in these tumor specimens were evaluated by immunostaining and p53 mutation status was determined by direct sequencing. Associations among EMT status, p53 mutation status, and statin use were evaluated, and prognosis was analyzed using a marginal structural model.

Results: Mutant p53 induced EMT and increased the invasive ability of H1650 cells. Simvastatin restored the epithelial phenotype and decreased the invasive ability of both H1650 and H1975 cells. Statin administration was associated with inactivation of EMT only in patients with mutant p53, which was consistent with the in vitro results. Moreover, in patients with mutant p53, statin users had significantly better survival than non-statin users. In contrast, statins significantly worsened the prognosis of patients with wild type p53 (HR 2.10, 95% CI 1.14–3.85).

Conclusion: Statins suppress EMT and change the prognosis of patients with lung adenocarcinoma in a p53 mutation-dependent manner.

Lovastatin induced Kruppel like factor 2 (KLF2), Kruppel like factor 6 (KLF6) and Ras homolog family member B (RHOB) genes and preferentially led to viability reduction of Cisplatin-resistant cells

It was reported that statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase that are used to prevent hypercholesterolemia, have antitumor activity in several cancers. In this study, we investigated the cell viability of statins in Cisplatin-resistant HCP4 and PCDP5 cells compared with their parent Hela and PC3 cells, respectively, and found that HCP4 and PCDP5 cells were 37-fold and 18-fold more resistant to Cisplatin but 13-fold and 7-fold more sensitive to Lovastatin by cell proliferation assay. Lovastatin induced the apoptosis of HCP4 cells more rapidly and to greater extent than in Hela cells as assessed by flow cytometry and western blotting analyses. The MVA pathway was not involved in this acquired Cisplatin resistance. To elucidate the mechanism underlying the reduced viability to Lovastatin, we performed cDNA microarray analysis and identified 65 and 54 genes that were induced more than 2-fold by Lovastatin in HCP4 and PCDP5 cells, respectively. Of these, only three genes, KLF2, KLF6, and RHOB, were commonly induced between HCP4 and PCDP5 cells. These mRNAs were strongly induced by Lovastatin with transcriptional regulation in HCP4 cells. Consistent with transcription, the protein expression of RHOB also was induced by Lovastatin. The induction of these genes was associated with cell cycle arrest and apoptosis. Combination treatment with Cisplatin and Lovastatin resulted in an agonistic effect in Hela and PC3 cells and an antagonistic effect in HCP4 and PCDP5 cells. These results suggest that statins might have the potential to overcome Cisplatin resistance as single-agent therapy.

Cardiovascular disease and cancer: Evidence for shared disease pathways and pharmacologic prevention

Cardiovascular disease (CVD) and cancer are leading causes of mortality and morbidity worldwide. Strategies to improve their treatment and prevention are global priorities and major focus of World Health Organization's joint prevention programs. Emerging evidence suggests that modifiable risk factors including diet, sedentary lifestyle, obesity and tobacco use are central to the pathogenesis of both diseases and are reflected in common genetic, cellular, and signaling mechanisms. Understanding this important biological overlap is critical and may help identify novel therapeutic and preventative strategies for both disorders. In this review, we will discuss the shared genetic and molecular factors central to CVD and cancer and how the strategies commonly used for the prevention of atherosclerotic vascular disease can be applied to cancer prevention.

Simvastatin-Induced Apoptosis in Osteosarcoma Cells: A Key Role of RhoA-AMPK/p38 MAPK Signaling in Antitumor Activity

Osteosarcoma is the most common type of primary bone tumor, novel therapeutic agents for which are urgently needed. To identify such agents, we screened a panel of approved drugs with a mouse model of osteosarcoma. The screen identified simvastatin, which inhibited the proliferation and migration of osteosarcoma cells in vitro Simvastatin also induced apoptosis in osteosarcoma cells in a manner dependent on inhibition of the mevalonate biosynthetic pathway. It also disrupted the function of the small GTPase RhoA and induced activation of AMP-activated protein kinase (AMPK) and p38 MAPK, with AMPK functioning upstream of p38 MAPK. Inhibitors of AMPK or p38 MAPK attenuated the induction of apoptosis by simvastatin, whereas metformin enhanced this effect of simvastatin by further activation of AMPK. Although treatment with simvastatin alone did not inhibit osteosarcoma tumor growth in vivo, its combination with a fat-free diet induced a significant antitumor effect that was enhanced further by metformin administration. Our findings suggest that simvastatin induces apoptosis in osteosarcoma cells via activation of AMPK and p38 MAPK, and that, in combination with other approaches, it holds therapeutic potential for osteosarcoma. Mol Cancer Ther; 16(1); 182-92. ©2016 AACR.

Cancer Stem Cells and Radioresistance: Rho/ROCK Pathway Plea Attention

Radiation is the most potent mode of cancer therapy; however, resistance to radiation therapy results in tumor relapse and subsequent fatality. The cancer stem cell (CSC), which has better DNA repair capability, has been shown to contribute to tumor resistance and is an important target for treatment. Signaling molecules such as Notch, Wnt, and DNA repair pathways regulate molecular mechanisms in CSCs; however, none of them have been translated into therapeutic targets. The RhoGTPases and their effector ROCK-signaling pathway, though important for tumor progression, have not been well studied in the context of radioresistance. There are reports that implicate RhoA in radioresistance. ROCK2 has also been shown to interact with BRCA2 in the regulation of cell division. Incidentally, statins (drug for cardiovascular ailment) are functional inhibitors of RhoGTPases. Studies suggest that patients on statins have a better prognosis in cancers. Data from our lab suggest that ROCK signaling regulates radioresistance in cervical cancer cells. Collectively, these findings suggest that Rho/ROCK signaling may be important for radiation resistance. In this review, we enumerate the role of Rho/ROCK signaling in stemness and radioresistance and highlight the need to explore these molecules for a better understanding of radioresistance and development of therapeutics.

γ-Tocotrienol as a Promising Countermeasure for Acute Radiation Syndrome: Current Status

The hazard of ionizing radiation exposure due to nuclear accidents or terrorist attacks is ever increasing. Despite decades of research, still, there is a shortage of non-toxic, safe and effective medical countermeasures for radiological and nuclear emergency. To date, the U.S. Food and Drug Administration (U.S. FDA) has approved only two growth factors, Neupogen (granulocyte colony-stimulating factor (G-CSF), filgrastim) and Neulasta (PEGylated G-CSF, pegfilgrastim) for the treatment of hematopoietic acute radiation syndrome (H-ARS) following the Animal Efficacy Rule. Promising radioprotective efficacy results of γ-tocotrienol (GT3; a member of the vitamin E family) in the mouse model encouraged its further evaluation in the nonhuman primate (NHP) model. These studies demonstrated that GT3 significantly aided the recovery of radiation-induced neutropenia and thrombocytopenia compared to the vehicle controls; these results particularly significant after exposure to 5.8 or 6.5 Gray (Gy) whole body γ-irradiation. The stimulatory effect of GT3 on neutrophils and thrombocytes (platelets) was directly and positively correlated with dose; a 75 mg/kg dose was more effective compared to 37.5 mg/kg. GT3 was also effective against 6.5 Gy whole body γ-irradiation for improving neutrophils and thrombocytes. Moreover, a single administration of GT3 without any supportive care was equivalent, in terms of improving hematopoietic recovery, to multiple doses of Neupogen and two doses of Neulasta with full supportive care (including blood products) in the NHP model. GT3 may serve as an ultimate radioprotector for use in humans, particularly for military personnel and first responders. In brief, GT3 is a promising radiation countermeasure that ought to be further developed for U.S. FDA approval for the ARS indication.

Therapeutic Effects of Repurposed Therapies in Non-Small Cell Lung Cancer: What Is Old Is New Again

The recent emergence of targeted and immunotherapeutic agents has dramatically changed the management for patients with non-small cell lung cancer (NSCLC). Despite these advances, lung cancer is not exempt from the challenges facing oncology drug development, including the huge financial cost and the time required for drug implementation. Repositioning noncancer therapies with potential antineoplastic properties into new therapeutic niches is an alternative treatment strategy offering the possibility of saving money and time and improving outcomes. The goal of such a strategy is to deliver an effective drug with a favorable toxicity profile at a reduced cost. Preclinical models and observational data have demonstrated promising activity for many of these agents, and they are now being studied in prospective trials. We review the relevant published data regarding the therapeutic effects of metformin, statins, nonsteroidal anti-inflammatory drugs, β-blockers, and itraconazole in NSCLC, with a focus on the putative mechanisms of action and clinical data. As these drugs are increasingly being tested in clinical trials, we aim to highlight the salient challenges and future strategies to optimize this approach.