Simvastatin prevents triple-negative breast cancer metastasis in pre-clinical models through regulation of FOXO3a

Statins as Secondary Preventive Agent to Limit Breast Cancer Metastatic Outgrowth

Metastasis is a leading cause of mortality in breast cancer, as metastatic disease is often aggressive and resistant to conventional treatments. Cancer cells that spread to distant organs can enter a dormant phase for extended periods, sometimes years or decades. During this dormant phase, cancer cells avoid immune and pharmacological response. Thus, new approaches are needed to prevent these disseminated cells from becoming lethal cancers. Statins are known inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase that have been extensively used in patients with cardiovascular diseases to lower cholesterol. However, recent research has demonstrated their potential in anticancer therapies. Epidemiological evidence suggests that statins are associated with a reduction in breast cancer-specific mortality, although they do not appear to affect the incidence of primary tumors. In this review, we discuss the role of statins in metastasis and dormancy, their cytocidal and cytostatic effects and their interactions with different cell types in the tumor microenvironment. The exact mechanisms by which statins reduce mortality without influencing primary tumor growth remain unclear, also warranting further investigation into their potential role in metastasis and tumor dormancy, which could ultimately help patients to improve survival and quality of life.

Nanomedicine marvels: crafting the future of cancer therapy with innovative statin nano-formulation strategies

Statins, traditionally used for managing hyperlipidemia and cardiovascular diseases, have garnered significant interest for their potential anti-cancer properties. Research indicates that statins can inhibit critical processes in cancer development, such as apoptosis, angiogenesis, and metastasis. Despite their promising anti-cancer effects, the clinical application of statins in oncology has been hampered by their inherent low solubility and bioavailability. These pharmacokinetic challenges can be effectively addressed through the use of nano-based drug delivery systems. Nano-formulations enhance the delivery and therapeutic efficacy of statins by improving their solubility, stability, and targeting ability, thus maximizing their concentration within the tumor microenvironment and minimizing systemic side effects. This review delves into the potential of nanoparticles as carriers for statins in cancer therapy. It explores the mechanisms by which statins exert their anti-cancer effects, such as through the inhibition of the mevalonate pathway, modulation of immune responses, and induction of apoptosis. Furthermore, the review examines the development of various statin-loaded nano-formulations, highlighting their advantages over conventional formulations. The novelty of this review lies in its focus on recent advancements in nanoformulations that enhance statin delivery to the tumor microenvironment. By discussing the current advancements and prospects of statin nano-formulations, this review aims to provide a comprehensive understanding of how these innovative strategies can improve cancer treatment outcomes and enhance the quality of life for patients. The integration of nanotechnology with statin therapy offers a novel approach to overcoming existing therapeutic limitations and paving the way for more effective and safer cancer treatments.

Targeting Cholesterol Biosynthesis with Statins Synergizes with AKT Inhibitors in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is responsible for a disproportionate number of breast cancer patient deaths due to extensive molecular heterogeneity, high recurrence rates, and lack of targeted therapies. Dysregulation of the phosphoinositide 3-kinase (PI3K)/AKT pathway occurs in approximately 50% of TNBC patients. Here, we performed a genome-wide CRISPR/Cas9 screen with PI3Kα and AKT inhibitors to find targetable synthetic lethalities in TNBC. Cholesterol homeostasis was identified as a collateral vulnerability with AKT inhibition. Disruption of cholesterol homeostasis with pitavastatin synergized with AKT inhibition to induce TNBC cytotoxicity in vitro in mouse TNBC xenografts and in patient-derived estrogen receptor (ER)-negative breast cancer organoids. Neither ER-positive breast cancer cell lines nor ER-positive organoids were sensitive to combined AKT inhibitor and pitavastatin. Mechanistically, TNBC cells showed impaired sterol regulatory element-binding protein 2 (SREBP-2) activation in response to single-agent or combination treatment with AKT inhibitor and pitavastatin, which was rescued by inhibition of the cholesterol-trafficking protein Niemann-Pick C1 (NPC1). NPC1 loss caused lysosomal cholesterol accumulation, decreased endoplasmic reticulum cholesterol levels, and promoted SREBP-2 activation. Taken together, these data identify a TNBC-specific vulnerability to the combination of AKT inhibitors and pitavastatin mediated by dysregulated cholesterol trafficking. These findings support combining AKT inhibitors with pitavastatin as a therapeutic modality in TNBC. Significance: Two FDA-approved compounds, AKT inhibitors and pitavastatin, synergize to induce cell death in triple-negative breast cancer, motivating evaluation of the efficacy of this combination in clinical trials.

In Vivo Simvastatin and Brain Radiation in a Model of HER2 + Inflammatory Breast Cancer Brain Metastasis

Purpose

Inhibiting HMG-CoA reductase with simvastatin prevents breast cancer metastases in preclinical models and radiosensitizes monolayer and stem-like IBC cell lines in vitro . Given the extensive use of simvastatin worldwide and its expected penetration into the brain, we examined whether regulating cholesterol with simvastatin affected IBC3 HER2+ brain metastases.

Methods and Materials

Breast cancer cell lines KPL4 and MDA-IBC3 were examined in vitro for DNA repair after radiation with or without statin treatment. Brain metastasis endpoints were examined in the MDA-IBC3 brain metastasis model after ex vivo exposure to lipoproteins and after tail vein injections with and without whole-brain radiotherapy (WBR) and oral statin exposure.

Results

Ex vivo preculture of MDA-IBC3 cells with very low-density lipoprotein (vLDL) enhanced the growth of colonized lesions in the brain in vivo compared with control or high-density lipoprotein (HDL), and concurrent oral simvastatin/ WBR reduced the incidence of micrometastatic lesions evaluated 10 days after WBR. However, statin, with or without WBR, did not reduce the incidence, burden, or number of macrometastatic brain lesions evaluated 5 weeks after WBR.

Conclusions

Although a role for cholesterol biosynthesis is demonstrated in DNA repair and response to whole brain radiation in this model, durable in vivo efficacy of concurrent whole brain irradiation and oral statin was not demonstrated.

Ezetimibe inhibits the migration and invasion of triple-negative breast cancer cells by targeting TGFβ2 and EMT

The important role of cholesterol in tumor metastasis has been widely studied in recent years. Ezetimibe is currently the only selective cholesterol uptake inhibitor on the market. Here, we explored the effect of ezetimibe on breast cancer metastasis by studying its impact on breast cancer cell migration, invasion, and epithelial-mesenchymal transition (EMT). Differential gene expression analysis and validation were also carried out to compare ezetimibe-treated and untreated breast cancer cells. Finally, breast cancer cells overexpressing TGFβ2 were constructed, and the effect of TGFβ2 on the migration and invasion of ezetimibe-treated breast cancer cells was examined. Our results show that ezetimibe treatment of breast cancer cells inhibited cell migration, invasion, and EMT, and it significantly suppressed the expression of TGFβ2. Overexpression of TGFβ2 reversed the inhibitory effect of ezetimibe on the migration and invasion of breast cancer cells. Taken together, our results suggest that ezetimibe might be a potential candidate for the treatment of breast cancer metastasis.

Concurrent Use of Statins in Patients Undergoing Curative Intent Treatment for Triple Negative Breast Cancer: A Systematic Review and Meta-Analysis

Pre-clinical studies in triple negative breast cancer (TNBC) suggest that statins may inhibit cell proliferation, promote cell-cycle arrest, induce apoptosis, change the tumor microenvironment, and improve effectiveness of other therapies. Observational studies have demonstrated variable effects from statin therapy on oncologic outcomes in these patients. As such, we aimed to pool previous data via a systematic review and meta-analysis to elucidate the impact of concurrent statin use on oncologic outcomes for patients with TNBC. Medline, EMBASE, CENTRAL, and PubMed were systematically searched from inception through to June 2022. Studies were included if they compared patients with TNBC receiving and not receiving statin therapy concurrently with oncologic treatment for curative intent in terms of recurrence and survival in a non-metastatic setting. The primary outcomes were 5-year disease-free survival (DFS) and 5-year overall survival (OS). A pairwise meta-analyses was performed using inverse variance random effects. Risk of bias was assessed with the ROBINS-I and the GRADE approach was conducted to assess quality of evidence. From 4014 citations, 5 studies with 625 patients on statin therapy and 2707 patients not on statin therapy were included. There was a significant increase in 5-year DFS for patients on statin therapy compared to patients not on statin therapy (OR 1.44, 95% CI 1.04-1.98, P = .03). No significant difference was noted in 5-year OS between the 2 groups (OR 1.12, 95% CI 0.86-1.47, P = .40). Included studies were at moderate-to-high risk of bias. The GRADE quality of evidence was very low. This review presents very low-quality evidence that concurrent use of statins with oncologic treatment may potentially improve long-term DFS for patients with TNBC undergoing curative intent therapy. Future research by way of large, prospective study is required to further clarify the clinical utility of statins on patients undergoing treatment for TNBC.

Role and regulation of FOXO3a: new insights into breast cancer therapy

Breast cancer is the most common malignancy in the world, particularly affecting female cancer patients. Enhancing the therapeutic strategies for breast cancer necessitates identifying molecular drug targets that effectively eliminate tumor cells. One of these prominent targets is the forkhead and O3a class (FOXO3a), a member of the forkhead transcription factor subfamily. FOXO3a plays a pivotal role in various cellular processes, including apoptosis, proliferation, cell cycle regulation, and drug resistance. It acts as a tumor suppressor in multiple cancer types, although its specific role in cancer remains unclear. Moreover, FOXO3a shows promise as a potential marker for tumor diagnosis and prognosis in breast cancer patients. In addition, it is actively influenced by common anti-breast cancer drugs like paclitaxel, simvastatin, and gefitinib. In breast cancer, the regulation of FOXO3a involves intricate networks, encompassing post-translational modification post-translational regulation by non-coding RNA (ncRNA) and protein-protein interaction. The specific mechanism of FOXO3a in breast cancer urgently requires further investigation. This review aims to systematically elucidate the role of FOXO3a in breast cancer. Additionally, it reviews the interaction of FOXO3a and its upstream and downstream signaling pathway-related molecules to uncover potential therapeutic drugs and related regulatory factors for breast cancer treatment by regulating FOXO3a.

CaaX-motif adjacent residues control G protein prenylation under suboptimal conditions

Prenylation is a universal and irreversible post-translational modification that supports membrane interactions of proteins involved in various cellular processes, including migration, proliferation, and survival. Thus, dysregulation of prenylation contributes to multiple disorders, including cancers, vascular diseases, and neurodegenerative diseases. During prenylation, prenyltransferase enzymes tether metabolically produced isoprenoid lipids to proteins via a thioether linkage. Pharmacological inhibition of the lipid synthesis pathway by statins has long been a therapeutic approach to control hyperlipidemia. Building on our previous finding that statins inhibit membrane association of G protein γ (Gγ) in a subtype-dependent manner, we investigated the molecular reasoning for this differential. We examined the prenylation efficacy of carboxy terminus (Ct) mutated Gγ in cells exposed to Fluvastatin and prenyl transferase inhibitors and monitored the subcellular localization of fluorescently tagged Gγ subunits and their mutants using live-cell confocal imaging. Reversible optogenetic unmasking-masking of Ct residues was used to probe their contribution to the prenylation process and membrane interactions of the prenylated proteins. Our findings suggest that specific Ct residues regulate membrane interactions of the Gγ polypeptide statin sensitivity, and prenylation efficacy. Our results also show that a few hydrophobic and charged residues at the Ct are crucial determinants of a protein's prenylation ability, especially under suboptimal conditions. Given the cell and tissue-specific expression of different Gγ subtypes, our findings explain how and why statins differentially perturb heterotrimeric G protein signaling in specific cells and tissues. Our results may provide molecular reasoning for repurposing statins as Ras oncogene inhibitors and the failure of using prenyltransferase inhibitors in cancer treatment.

Post-diagnostic statin use and breast cancer-specific mortality: a population-based cohort study

PURPOSE

Statins are the most widely prescribed cholesterol lowering medications and have been associated with both improved and unchanged breast cancer outcomes in previous studies. This study examines the association between the post-diagnostic use of statins and breast cancer outcomes (death and recurrence) in a large, representative sample of New Zealand (NZ) women with breast cancer.

METHODS

Women diagnosed with a first primary breast cancer between 2007 and 2016 were identified from four population-based regional NZ breast cancer registries and linked to national pharmaceutical data, hospital discharges, and death records. Cox proportional hazard models were used to estimate the hazard of breast cancer-specific death (BCD) associated with any post-diagnostic statin use.

RESULTS

Of the 14,976 women included in analyses, 27% used a statin after diagnosis and the median follow up time was 4.51 years. Statin use (vs non-use) was associated with a statistically significant decreased risk of BCD (adjusted hazard ratio: 0.74; 0.63-0.86). The association was attenuated when considering a subgroup of 'new' statin users (HR: 0.91; 0.69-1.19), however other analyses revealed that the protective effect of statins was more pronounced in estrogen receptor positive patients (HR: 0.77; 0.63-0.94), postmenopausal women (HR: 0.74; 0.63-0.88), and in women with advanced stage disease (HR: 0.65; 0.49-0.84).

CONCLUSION

In this study, statin use was associated with a statistically significant decreased risk of breast cancer death, with subgroup analyses revealing a more protective effect in ER+ patients, postmenopausal women, and in women with advanced stage disease. Further research is warranted to determine if these associations are replicated in other clinical settings.

Identification of tumor mutation burden-associated molecular and clinical features in cancer by analyzing multi-omics data

Background

Tumor mutation burden (TMB) has been recognized as a predictive biomarker for immunotherapy response in cancer. Systematic identification of molecular features correlated with TMB is significant, although such investigation remains insufficient.

Methods

We analyzed associations of somatic mutations, pathways, protein expression, microRNAs (miRNAs), long non-coding RNAs (lncRNAs), competing endogenous RNA (ceRNA) antitumor immune signatures, and clinical features with TMB in various cancers using multi-omics datasets from The Cancer Genome Atlas (TCGA) program and datasets for cancer cohorts receiving the immune checkpoint blockade therapy.

Results

Among the 32 TCGA cancer types, melanoma harbored the highest percentage of high-TMB (≥ 10/Mb) cancers (49.4%), followed by lung adenocarcinoma (36.9%) and lung squamous cell carcinoma (28.1%). Three hundred seventy-six genes had significant correlations of their mutations with increased TMB in various cancers, including 11 genes (ARID1A, ARID1B, BRIP1, NOTCH2, NOTCH4, EPHA5, ROS1, FAT1, SPEN, NSD1,and PTPRT) with the characteristic of their mutations associated with a favorable response to immunotherapy. Based on the mutation profiles in three genes (ROS1, SPEN, and PTPRT), we defined the TMB prognostic score that could predict cancer survival prognosis in the immunotherapy setting but not in the non-immunotherapy setting. It suggests that the TMB prognostic score's ability to predict cancer prognosis is associated with the positive correlation between immunotherapy response and TMB. Nine cancer-associated pathways correlated positively with TMB in various cancers, including nucleotide excision repair, DNA replication, homologous recombination, base excision repair, mismatch repair, cell cycle, spliceosome, proteasome, and RNA degradation. In contrast, seven pathways correlated inversely with TMB in multiple cancers, including Wnt, Hedgehog, PI3K-AKT, MAPK, neurotrophin, axon guidance, and pathways in cancer. High-TMB cancers displayed higher levels of antitumor immune signatures and PD-L1 expression than low-TMB cancers in diverse cancers. The association between TMB and survival prognosis was positive in bladder, gastric, and endometrial cancers and negative in liver and head and neck cancers. TMB also showed significant associations with age, gender, height, weight, smoking, and race in certain cohorts.

Conclusions

The molecular and clinical features significantly associated with TMB could be valuable predictors for TMB and immunotherapy response and therefore have potential clinical values for cancer management.

A review of effects of atorvastatin in cancer therapy

Cancer is one of the most challenging diseases to manage. A sizeable number of researches are done each year to find better diagnostic and therapeutic strategies. At the present time, a package of chemotherapy, targeted therapy, radiotherapy, and immunotherapy is available to cope with cancer cells. Regarding chemo-radiation therapy, low effectiveness and normal tissue toxicity are like barriers against optimal response. To remedy the situation, some agents have been proposed as adjuvants to improve tumor responses. Statins, the known substances for reducing lipid, have shown a considerable capability for cancer treatment. Among them, atorvastatin as a reductase (HMG-CoA) inhibitor might affect proliferation, migration, and survival of cancer cells. Since finding an appropriate adjutant is of great importance, numerous studies have been conducted to precisely unveil antitumor effects of atorvastatin and its associated pathways. In this review, we aim to comprehensively review the most highlighted studies which focus on the use of atorvastatin in cancer therapy.

The Link Between Statins and Breast Cancer in Mouse Models: A Systematic Review

Statins, a class of cholesterol-lowering drugs, have consistently demonstrated pleiotropic effects in both preclinical and clinical studies. Outside of inhibiting the production of cholesterol in cells, statins have shown antineoplastic properties most commonly in breast cancer. Clinical and epidemiological studies, however, are less definitive than preclinical studies regarding statins as potential adjuvant oncologic therapy. Our objective is to summarize mouse model studies that investigate the link between statins and breast cancer using a cancer care continuum framework to provide a clinically relevant picture of the potential use of statins in breast cancer. A systematic review of the PubMed database was performed to identify studies published between January 2007 and July 2022 that investigated the effects of statins on breast cancer prevention, treatment, and survivorship in mouse models. Overall, 58 studies were identified using our search strategy. Based on our inclusion and exclusion criteria, 26 mouse model studies were eligible to be included in our systematic review. In breast cancer mouse models, statins alone and in combination with anti-cancer therapies demonstrate proven antineoplastic effects across the cancer care continuum. The antineoplastic benefit of statins as single agents in mouse model studies helps inform their synergistic benefit that future clinical studies can test. Parameters such as statin timing, dose, and breast cancer subtype are key stepping stones in defining how statins could be used in the treatment of breast cancer.

27-Hydroxycholesterol Binds GPER and Induces Progression of Estrogen Receptor-Negative Breast Cancer

Cholesterol affects the proliferation of breast cancer (BC) and in particular of estrogen receptor-negative (ER-) BC. Cholesterol is converted to 27-hydroxycholesterol (27HC), which promotes the growth of ER+ BC. Potentially, 27HC can be involved in cholesterol-dependent ER- BC proliferation. Stable MDA-MB-231 silenced clones for CYP7B1 (27HC metabolizing enzyme) show an increased basal proliferation rate, which is not observed in the presence of lipoprotein-deprived serum. Furthermore, the treatment of SKBR3, MDA-MB-231 and MDA-MB-468 with 27HC increased cell proliferation that was prevented by G15, a selective G Protein-Coupled Estrogen Receptor (GPER) inhibitor, suggested this receptor to be a potential 27HC target. Binding experiments demonstrate that 27HC is a new ligand for GPER. We show that ERK1/2 and NFκB are part of the 27HC/GPER pathway. The stable silencing of GPER prevents NFκB activation and reduces basal and 27HC-dependent tumor growth. Additionally, conditioned medium from ER- BC cells treated with 27HC promotes tube formation, which does not occur with CM from GPER silenced cells. Collectively, these data demonstrate that cholesterol conversion into 27HC promotes ER- BC growth and progression, and the expression of GPER is required for its effects.

New Advances in Targeted Therapy of HER2-Negative Breast Cancer

Breast cancer has an extremely high incidence in women, and its morbidity and mortality rank first among female tumors. With the increasing development of molecular biology and genomics, molecular targeted therapy has become one of the most active areas in breast cancer treatment research and has also achieved remarkable achievements. However, molecular targeted therapy is mainly aimed at HER2-positive breast cancer and has not yet achieved satisfactory curative effect on HER2-negative breast cancer. This article describes the potential targets that may be used for breast cancer treatment from the aspects of PI3K/AKT signaling pathway, DDR, angiogenesis, the cell cycle, breast cancer stem cells, etc., and explores possible inhibitors for the treatment of HER2-negative breast cancer, such as PI3K inhibitors, AKT inhibitors and m-TOR inhibitors that inhibit the PI3K/AKT signaling pathway, small molecule tyrosine kinase inhibitors that restrain angiogenesis, CDK inhibitors, aurora kinase inhibitors and HDAC inhibitors that block cell cycle, as well as the drugs targeting breast cancer stem cells which have been a hit, aiming to provide a new idea and strategy for the treatment of HER2-negative breast cancer.

ER+ Breast Cancer Mammosphere Formation and Analysis

Mammosphere formation assays are a popular and convenient technique in the study of breast cancer by providing an in vitro mechanism by which to study breast cancer stem cell (BCSC) contribution to tumorigenesis, as well as more closely mimicking the three-dimensional tumor microenvironment. In these assays, BCSCs are stimulated to proliferate in low adherence tissue culture dishes and the resulting mammospheres exhibit activation of stem cell-related signaling pathways. Here we describe the process for generating and analyzing mammospheres under varying conditions.

Association of statin use with clinical outcomes in patients with triple-negative breast cancer

BACKGROUND

Previous studies have examined the association of statin therapy and breast cancer outcomes with mixed results. The objective of this study was to investigate the clinical effects of incident statin use among individuals with triple-negative breast cancer (TNBC).

METHODS

Data from the Surveillance, Epidemiology, and End Results-Medicare and Texas Cancer Registry-Medicare databases were used, and women aged ≥66 years who had stage I, II, and III breast cancer were identified. Multivariable Cox proportional hazards regression models were used to examine the association of new statin use in the 12 months after a breast cancer diagnosis with overall survival (OS) and breast cancer-specific survival (BCSS).

RESULTS

When examining incident statin use, defined as the initiation of statin therapy in the 12 months after breast cancer diagnosis, a significant association was observed between statin use and improved BCSS (standardized hazard ratio, 0.42; 95% confidence interval [CI], 0.20-0.88; P = .022) and OS (hazard ratio, 0.70; 95% CI, 0.50-0.99; P = .046) among patients with TNBC (n = 1534). No association was observed with BCSS (standardized hazard ratio, 0.99; 95% CI, 0.71-1.39; P = .97) or OS (hazard ratio, 1.04; 95% CI, 0.92-1.17; P = .55) among those without TNBC (n = 15,979). The results were consistent when examining statin exposure as a time-varying variable.

CONCLUSIONS

Among women with I, II, and III TNBC, initiation of statin therapy in the 12 months after breast cancer diagnosis was associated with an OS and BCSS benefit. Statins may have a role in select patients with breast cancer, and further investigation is warranted.

Atorvastatin facilitates chemotherapy effects in metastatic triple-negative breast cancer

BACKGROUND

Metastatic triple-negative breast cancer (mTNBC) is treated mainly with chemotherapy. However, resistance frequently occurs as tumours enter dormancy. Statins have been suggested as effective against cancer but as they prolong and promote dormancy, it is an open question of whether the concomitant use would interfere with chemotherapy in primary and mTNBC. We examined this question in animal models and clinical correlations.

METHODS

We used a xenograft model of spontaneous metastasis to the liver from an ectopic tumour employing a mTNBC cell line. Atorvastatin was provided to sensitise metastatic cells, followed by chemotherapy. The effects of statin usage on outcomes in women with metastatic breast cancer was assessed respectively by querying a database of those diagnosed from 1999 to 2019.

RESULTS

Atorvastatin had limited influence on tumour growth or chemotherapy effects in ectopic primary tumours. Interestingly, atorvastatin was additive with doxorubicin (but not paclitaxel) when targeting liver metastases. E-cadherin-expressing, dormant, breast cancer cells were resistant to the use of either statins or chemotherapy as compared to wild-type cells; however, the combination of both did lead to increased cell death. Although prospective randomised studies are needed for validation, our retrospective clinical analysis suggested that patients on statin treatment could experience prolonged dormancy and overall survival; still once the tumour recurred progression was not affected by statin use.

CONCLUSION

Atorvastatin could be used during adjuvant chemotherapy and also in conjunction with metastatic chemotherapy to reduce mTNBC cancer progression. These preclinical data establish a rationale for the development of randomised studies.

The potential use of simvastatin for cancer treatment: A review

Statins, typically used to reduce lipid levels, have been rediscovered for exhibiting anticancer activities. Among them, especially simvastatin may influence the proliferation, migration, and survival of cancer cells. The concept of using statins to treat cancer has been adopted since the 1990s In vitro and in vivo experiments and cohort studies using statins have been carried out to demonstrate their antitumor effects (such as proliferation and migration impairment) by influencing inflammatory and oxidative stress-related tumorigenesis. Nevertheless, the biological mechanisms for these actions are not fully elucidated. In this review, we present an overview of the most important studies conducted from 2015 to date on the use of simvastatin in cancer therapy. This review brings the most recent perspectives and targets in epidemiological, in vitro, and in vivo studies, regarding the use of simvastatin alone or in combination with other drugs for the treatment of various types of cancer.

Simvastatin is effective in killing the radioresistant breast carcinoma cells

BACKGROUND

Statins, small molecular 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, are widely used to lower cholesterol levels in lipid-metabolism disorders. Recent preclinical and clinical studies have shown that statins exert beneficial effects in the management of breast cancer by increasing recurrence free survival. Unfortunately, the underlying mechanisms remain elusive.

MATERIALS AND METHODS

Simvastatin, one of the most widely prescribed lipophilic statins was utilized to investigate potential radiosensitizing effects and an impact on cell survival and migration in radioresistant breast cancer cell lines.

RESULTS

Compared to parental cell counterparts, radioresistant MDA-MB-231-RR, T47D-RR andAu565-RR cells were characterized by upregulation of 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMGCR) expression accompanied by epithelial-to-mesenchymal transition (EMT) activation. Radioresistant breast cancer cells can be killed by simvastatin via mobilizing of a variety of pathways involved in apoptosis and autophagy. In the presence of simvastatin migratory abilities and vimentin expression is diminished while E-cadherin expression is increased.

CONCLUSIONS

The present study suggests that simvastatin may effectively eradicate radioresistant breast carcinoma cells and diminish their mesenchymal phenotypes.

Role of Forkhead box O3a transcription factor in autoimmune diseases

Forkhead box O3a (FOXO3a) transcription factor, the most important member of Forkhead box O family, is closely related to cell proliferation, apoptosis, autophagy, oxidative stress and aging. The downregulation of FOXO3a has been verified to be associated with the poor prognosis, severer malignancy and chemoresistance in several human cancers. The activity of FOXO3a mainly regulated by phosphorylation of protein kinase B. FOXO3a plays a vital role in promoting the apoptosis of immune cells. FOXO3a could also modulate the activation, differentiation and function of T cells, regulate the proliferation and function of B cells, and mediate dendritic cells tolerance and immunity. FOXO3a accommodates the immune response through targeting nuclear factor kappa-B and FOXP3, as well as regulating the expression of cytokines. Besides, FOXO3a participates in intercellular interactions. FOXO3a inhibits dendritic cells from producing interleukin-6, which inhibits B-cell lymphoma-2 (BCL-2) and BCL-XL expression, thereby sparing resting T cells from apoptosis and increasing the survival of antigen-stimulated T cells. Recently, plentiful evidences further illustrated the significance of FOXO3a in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, myositis, multiple sclerosis, and systemic sclerosis. In this review, we focused on the biological function of FOXO3a and related signaling pathways regarding immune system, and summarized the potential role of FOXO3a in the pathogenesis, progress and therapeutic potential of autoimmune diseases.

Ras Signaling in Breast Cancer

Ras proteins mediate extracellular and cytoplasmic signaling networks via receptor tyrosine kinase. The Ras pathway induces activation of signaling molecules involved in cell proliferation and growth, cell survival and apoptosis, metabolism, and motility. Although Ras mutations in breast cancer are not frequently reported, hyperactivation of Ras signaling plays an important role in breast cancer growth and progression. Oncogenic Ras activation occurs via loss of Ras GTPase-activating proteins, overexpression of growth factor receptor, and stimulation by various cytokines. Effective control of oncogenic Ras is one of the therapeutic strategies in breast cancer. The mechanisms of intracellular localization, activation, and signaling pathway of Ras in cancer have been used to develop therapeutic candidates. Recent studies have reported an effective therapy for breast cancer by inhibition of enzymes involved in the posttranslational modification of Ras, such as farnesyltransferase and geranylgeranyltransferase 1, and anti-cancer therapies targeting the epidermal growth factor receptor (EGFR). Emerging targets involved in EGF-mediated Ras activity in breast cancer have shed new insight into Ras activation in breast cancer progression. These alternative mechanisms for Ras signaling pathway may suggest novel therapeutic approaches for targeting Ras in breast cancer. In spite of the difficulties in targeting Ras protein, important discoveries highlight the direct inhibition of Ras activity. Further studies may elucidate the effects of targeting Ras protein and the clinical relevance thereof.

Pleiotropic effects of statins: A focus on cancer

The statin drugs ('statins') potently inhibit hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase by competitively blocking the active site of the enzyme. Statins decrease de novo cholesterol biosynthesis and thereby reduce plasma cholesterol levels. Statins exhibit "pleiotropic" properties that are independent of their lipid-lowering effects. For example, preclinical evidence suggests that statins inhibit tumor growth and induce apoptosis in specific cancer cell types. Furthermore, statins show chemo-sensitizing effects by impairing Ras family GTPase signaling. However, whether statins have clinically meaningful anti-cancer effects remains an area of active investigation. Both preclinical and clinical studies on the potential mechanisms of action of statins in several cancers have been reviewed in the literature. Considering the contradictory data on their efficacy, we present an up-to-date summary of the pleiotropic effects of statins in cancer therapy and review their impact on different malignancies. We also discuss the synergistic anti-cancer effects of statins when combined with other more conventional anti-cancer drugs to highlight areas of potential therapeutic development.

Simvastatin Suppresses Human Breast Cancer Cell Invasion by Decreasing the Expression of Pituitary Tumor-Transforming Gene 1

Statins, or 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, have been widely used to lower cholesterol and prevent cardiovascular diseases. Recent preclinical and clinical studies have shown that statins exert beneficial effects in the management of breast cancer, while the underlying mechanisms remain to be elucidated. Herein, we sought to investigate the effect of statins on the expression of pituitary tumor-transforming gene 1 (PTTG1), a critical gene involved in human breast cancer invasion and metastasis. Our results showed that PTTG1 is highly expressed in malignant Hs578T and MDA-MB-231 breast cancer cell lines as compared with normal or less malignant breast cancer cells. Furthermore, we found that the expression of PTTG1 was markedly suppressed by lipophilic statins, such as simvastatin, fluvastatin, mevastatin, and lovastatin, but not by hydrophilic pravastatin. In a dose and time dependent manner, simvastatin suppressed PTTG1 expression by decreasing PTTG1 mRNA stability in MDA-MB-231 cells. Both siRNA-mediated knockdown of PTTG1 expression and simvastatin treatment markedly inhibited MDA-MB-231 cell invasion, MMP-2 and MMP-9 activity, and the expression of PTTG1 downstream target genes, while ectopic expression of PTTG1 promoted cancer cell invasion, and partly reversed simvastatin-mediated inhibition of cell invasion. Mechanistically, we found that inhibition of PTTG1 expression by simvastatin was reversed by geranylgeranyl pyrophosphate, but not by farnesyl pyrophosphate, suggesting the involvement of geranylgeranyl synthesis in regulating PTTG1 expression. Our results identified statins as novel inhibitors of PTTG1 expression in breast cancer cells and provide mechanistic insights into how simvastatin prevent breast cancer metastasis as observed in recent preclinical and clinical studies.

Statins in risk-reduction and treatment of cancer

Statins, which are competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, reduce cholesterol blood levels and the risk of developing cardiovascular diseases and their related complications. In addition to this main activity, statins show pleiotropic effects such as antioxidant, anti-inflammatory and antiproliferative properties, with applications in many pathologies. Based on their antiproliferative properties, in vitro and in vivo studies have investigated their effects on various types of cancer (i.e., breast cancer, prostate cancer, colorectal cancer, ovarian cancer, lung cancer) with different genetic and molecular characteristics. Many positive results were obtained, but they were highly dependent on the physiochemical properties of the statins, their dose and treatment period. Combined therapies of statins and cytotoxic drugs have also been tested, and synergistic or additive effects were observed. Moreover, observational studies performed on patients who used statins for different pathologies, revealed that statins reduced the risk of developing various cancers, and improved the outcomes for cancer patients. Currently, there are many ongoing clinical trials aimed at exploring the potential of statins to lower the mortality and the disease-recurrence risk. All these results are the foundation of new treatment directions in cancer therapy.

Targeting SREBP-2-Regulated Mevalonate Metabolism for Cancer Therapy

Recently, targeting metabolic reprogramming has emerged as a potential therapeutic approach for fighting cancer. Sterol regulatory element binding protein-2 (SREBP-2), a basic helix-loop-helix leucine zipper transcription factor, mainly regulates genes involved in cholesterol biosynthesis and homeostasis. SREBP-2 binds to the sterol regulatory elements (SREs) in the promoters of its target genes and activates the transcription of mevalonate pathway genes, such as HMG-CoA reductase (HMGCR), mevalonate kinase and other key enzymes. In this review, we first summarized the structure of SREBP-2 and its activation and regulation by multiple signaling pathways. We then found that SREBP-2 and its regulated enzymes, including HMGCR, FPPS, SQS, and DHCR4 from the mevalonate pathway, participate in the progression of various cancers, including prostate, breast, lung, and hepatocellular cancer, as potential targets. Importantly, preclinical and clinical research demonstrated that fatostatin, statins, and N-BPs targeting SREBP-2, HMGCR, and FPPS, respectively, alone or in combination with other drugs, have been used for the treatment of different cancers. This review summarizes new insights into the critical role of the SREBP-2-regulated mevalonate pathway for cancer and its potential for targeted cancer therapy.

Anti-tumor effects of mevalonate pathway inhibition in ovarian cancer

BACKGROUND

Ovarian cancer remains the most fatal gynecological malignancy. Current therapeutic options are limited due to late diagnosis in the majority of the cases, metastatic spread to the peritoneal cavity and the onset of chemo-resistance. Thus, novel therapeutic approaches are required. Statins and amino-bisphosphonates are inhibitors of the mevalonate pathway, which is a fundamental pathway of cellular metabolism, essential for cholesterol production and posttranslational protein farnesylation and geranylgeranylation. While this pathway has emerged as a promising treatment target in several human malignancies, its potential as a therapeutic approach in ovarian cancer is still not fully understood.

METHODS

Human ovarian cancer cell lines (IGROV-1, A2780, A2780cis) were treated with increasing concentrations (0.5-100 μM) of statins (simvastatin, atorvastatin, rosuvastatin) and zoledronic acid. Effects on cell vitality and apoptosis were assessed using Cell Titer Blue®, Caspase 3/7 Glo®, clonogenic assays as well as cleaved poly (ADP-ribose) polymerase (cPARP) detection. The inhibition of the mevalonate pathway was confirmed using Western Blot of unprenylated Ras and Rap1a proteins. Quantitative real-time PCR and ELISA were used to analyze modulations on several key regulators of ovarian cancer tumorigenesis.

RESULTS

The treatment of IGROV-1 and A2780 cells with statins and zoledronic acid reduced vitality (by up to 80%; p < 0.001) and induced apoptosis by up to 8-folds (p < 0.001) in a dose-dependent fashion. Rescue experiments using farnesyl pyrophosphate or geranylgeranyl pyrophosphate evidenced that blocked geranylgeranylation is the major underlying mechanism of the pro-apoptotic effects. Gene expression of the tumor-promoting cytokines and mediators, such as transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), interleukin (IL)-8, and IL-6 were significantly suppressed by statins and zoledronic acid by up to 90% (p < 0.001). For all readouts, simvastatin was most potent of all agents used. Cisplatin-resistant A2780cis cells showed a relative resistance to statins and zoledronic acid. However, similar to the effects in A2780 cells, simvastatin and zoledronic acid significantly induced caspase 3/7 activation (6-folds; p < 0.001).

CONCLUSION

Our in vitro findings point to promising anti-tumor effects of statins and zoledronic acid in ovarian cancer and warrant additional validation in preclinical and clinical settings.

CLDN6-mediates SB431542 action through MMPs to regulate the invasion, migration, and EMT of breast cancer cells

Our previous research confirmed the repression of SMADs signaling pathway inhibits the invasion, migration, and EMT in breast cancer MCF-7 and SKBR-3 cell lines by DNMT1 up-regulating CLDN6, but the mechanism is unclear. Western blot was performed to detect the expression of SMAD2, SMAD3, P-SMAD2, and P-SMAD3. Then RT-PCR was carried out to examine the expression of tight junctions and cell adhesion molecule E-cadherin. According to the gene sequence of Claudin6, shRNA was linked with the green fluorescent protein-expressing eukaryotic expression vector pGC silencer TMΜ6/Neo/GFP, and it was transfected into breast cancer MCF-7 cells and SKBR-3 cells. RT-PCR and western blot were applied to verify the Claudin6 gene-silencing effect. We observed cellular morphology with inverted microscope, analyzed the capacity for clone formation, and detected transepithelial electrical resistance. The level of MMP2, and MMP9 in the cells treated with or without SB431542 and MCF-7-shGFP, MCF-7-shClaudin-6, SKBR-3-shGFP, and SKBR-3-shClaudin-6 cells pretreated with SB431542 were examined by RT-PCR and western blot. The expressions of Claudin-6, occludin, and cell adhesion molecule E-cadherin were enhanced by SB431542. SB431542 transformed mesenchymal cell morphology into epithelial cell morphology, inhibited capacity for clone formation, increased transepithelial electrical resistance, and downregulated the expression of MMP2 and MMP9. Knock down of Claudin6 can abolish SB431542 effects. We conclude that Claudin6 mediates the effects of SB431542 on the biologic phenotypes of the breast cancer cells we studied. We speculate Claudin6-mediated the SB431542 inhibition of invasion, migration, and EMT in breast cancer cells via MMP2/9.

Pitavastatin induces apoptosis in oral squamous cell carcinoma through activation of FOXO3a

Statins are a class of lipid‐lowering drugs that have recently been used in drug repositioning in the treatment of human cancer. However, the underlying mechanism of statin‐induced cancer cell death has not been clearly defined. In the present study, we evaluated the anticancer effect of pitavastatin on oral squamous cell carcinoma (OSCC), SCC15 and SCC4 cells and found that FOXO3a might be a direct target in pitavastatin‐induced cancer cell death. Our data revealed that pitavastatin selectively suppressed cell viability and induced intrinsic apoptosis in a FOXO3a‐dependent manner in SCC15 cells while no effect was observed in SCC4 cells. Notably, treatment with pitavastatin in SCC15 cells induced the nuclear translocation of FOXO3a via dual regulation of two upstream kinases, AMPK and Akt, resulting in the up‐regulation of PUMA, a transcriptional target gene of FOXO3a. Furthermore, our data revealed that FOXO3a‐mediated PUMA induction plays a role in pitavastatin‐induced intrinsic apoptosis in SCC15 cells. Taken together, our findings suggest that pitavastatin activates the FOXO3a/PUMA apoptotic axis by regulation of nuclear translocation of FOXO3a via Akt/FOXO3a or AMPK/FOXO3a signalling. Therefore, these findings might help to elucidate the underlying mechanism of the anticancer effects of pitavastatin on OSCC.

A High-Throughput Image Cytometry Method for the Formation, Morphometric, and Viability Analysis of Drug-Treated Mammospheres

The nonadherent mammosphere assay has been commonly used to investigate cancer stem cell activities in breast cancers that have the ability to form tumorspheres and maintain tumor growth. The sphere formation step is critical, in that it enables the construction of the mammosphere models for downstream assays. The mammosphere assay has also been used to assess the effects of drug treatment on the tumorspheres formed from primary cancer cells or cell lines. Traditionally, the mammosphere formation has been evaluated by standard microscopy systems that required external software for additional analyses. However, this method can be time-consuming and low-throughput, thus impractical for high-throughput characterization of mammosphere models and screening for potential therapeutic cancer drugs. To overcome these challenges, we developed a plate-based high-throughput method to rapidly analyze mammospheres in whole wells using the Celigo Image Cytometer. The method is employed to characterize mammosphere formation and morphology for adherent and nonadherent propagation of four breast cancer cell lines (MCF7, MDA-MB-436, MDA-MB-231, and SKBR3). Next, the dose-dependent effects of four small molecule drugs (doxorubicin, paclitaxel, 8-quinolinol, and salinomycin) are characterized based on sphere formation and viability stained with calcein AM and propidium iodide. We observed growth and morphometric differences between adherent and nonadherent propagation of the four cell lines. Furthermore, drug treatments induced various effects on mammosphere formation, morphology, and viability. The proposed image cytometry method provides a useful tool suitable for high-throughput characterization and analysis of mammospheres, which can improve assay efficiency when investigating the formation capabilities and drug-induced cytotoxicity effects.

Cholesterol and beyond - The role of the mevalonate pathway in cancer biology

Cancer is a multifaceted global disease. Transformation of a normal to a malignant cell takes several steps, including somatic mutations, epigenetic alterations, metabolic reprogramming and loss of cell growth control. Recently, the mevalonate pathway has emerged as a crucial regulator of tumor biology and a potential therapeutic target. This pathway controls cholesterol production and posttranslational modifications of Rho-GTPases, both of which are linked to several key steps of tumor progression. Inhibitors of the mevalonate pathway induce pleiotropic antitumor-effects in several human malignancies, identifying the pathway as an attractive candidate for novel therapies. In this review, we will provide an overview about the role and regulation of the mevalonate pathway in certain aspects of cancer initiation and progression and its potential for therapeutic intervention in oncology.

Synergistically Enhanced Inhibitory Effects of Pullulan Nanoparticle-Mediated Co-Delivery of Lovastatin and Doxorubicin to Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that is prone to drug resistance and difficult to treat. In this study, we grafted water-soluble pullulan with lovastatin (LV) to develop a novel amphiphilic conjugate, pullulan-encapsulated LV (PLV). The PLV conjugate was synthesized with three different ratios of pullulan to LV and characterized by Fourier transform infrared (FTIR). The degree of substitution (DS) of LV in terms of molar ratio was 7.87%, 3.58%, and 3.06% for PLV (1/2), PLV (1/3), and PLV (1/4), respectively, by proton NMR analysis. We selected the PLV (1/2) conjugate to prepare doxorubicin (DXR)-loaded PLV nanoparticles (PLV/DXR NPs) because of its superior properties. The average size and zeta potential for PLV (1/2) NPs were 177.6 nm and - 11.66 mV, respectively, determined by dynamic light scattering, and those for PLV/DXR NPs were 225.6 nm and - 10.51 mV, respectively. In vitro drug release profiling showed that PLV/DXR NPs sustainably released DXR within 72 h, which was more robust at pH 5.4 (97.90%) than pH 7.4 (76.15%). In the cytotoxicity study, PLV/DXR NPs showed greater inhibition of proliferation of TNBC MDA-MB-231 than non-TNBC MDA-MB-453 cells (IC₅₀ 0.60 vs 11.05 μM). FITC-loaded PLV/DXR NPs were prepared to investigate cellular uptake: both cell lines showed a time-dependent uptake of NPs, but the number of NPs entering MDA-MB-231 cells was greater than that entering the MDA-MB-453 cells. Pullulan-based NP co-delivery of LV and DXR could efficiently inhibit TNBC cells, which may help in designing a powerful drug delivery system for treating TNBC.

PARP1 Inhibition Radiosensitizes Models of Inflammatory Breast Cancer to Ionizing Radiation

Sustained locoregional control of disease is a significant issue in patients with inflammatory breast cancer (IBC), with local control rates of 80% or less at 5 years. Given the unsatisfactory outcomes for these patients, there is a clear need for intensification of local therapy, including radiation. Inhibition of the DNA repair protein PARP1 has had little efficacy as a single agent in breast cancer outside of studies restricted to patients with BRCA mutations; however, PARP1 inhibition (PARPi) may lead to the radiosensitization of aggressive tumor types. Thus, this study investigates inhibition of PARP1 as a novel and promising radiosensitization strategy in IBC. In multiple existing IBC models (SUM-149, SUM-190, MDA-IBC-3), PARPi (AZD2281-olaparib and ABT-888-veliparib) had limited single-agent efficacy (IC₅₀ > 10 μmol/L) in proliferation assays. Despite limited single-agent efficacy, submicromolar concentrations of AZD2281 in combination with RT led to significant radiosensitization (rER 1.12-1.76). This effect was partially dependent on BRCA1 mutational status. Radiosensitization was due, at least in part, to delayed resolution of double strand DNA breaks as measured by multiple assays. Using a SUM-190 xenograft model in vivo, the combination of PARPi and RT significantly delays tumor doubling and tripling times compared with PARPi or RT alone with limited toxicity. This study demonstrates that PARPi improves the effectiveness of radiotherapy in IBC models and provides the preclinical rationale for the opening phase II randomized trial of RT ± PARPi in women with IBC (SWOG 1706, NCT03598257).

Combination therapy with dacarbazine and statins improved the survival rate in mice with metastatic melanoma

Malignant melanoma is a highly aggressive skin cancer, and the overall median survival in patients with metastatic melanoma is only 6-9 months. Although molecular targeted therapies have recently been developed and have improved the overall survival, melanoma patients may show no response and acquisition of resistance to these drugs. Thus, other molecular approaches are essential for the treatment of metastatic melanoma. In the present study, we investigated the effect of cotreatment with dacarbazine and statins on tumor growth, metastasis, and survival rate in mice with metastatic melanomas. We found that cotreatment with dacarbazine and statins significantly inhibited tumor growth and metastasis via suppression of the RhoA/RhoC/LIM domain kinase/serum response factor/c-Fos pathway and enhanced p53, p21, p27, cleaved caspase-3, and cleaved poly(ADP-ribose) polymerase 1 expression in vivo. Moreover, the cotreatment significantly improved the survival rate in metastasis-bearing mice. Importantly, treatment with dacarbazine plus 100 mg/kg simvastatin or fluvastatin prevented metastasis-associated death in 4/20 mice that received dacarbazine + simvastatin and in 8/20 mice that received dacarbazine + fluvastatin (survival rates, 20% and 40%, respectively). These results suggested that cotreatment with dacarbazine and statins may thus serve as a new therapeutic approach to control tumor growth and metastasis in melanoma patients.

Drug Screening Platforms and RPPA

Since its inception as a scalable and cost-effective method for precise quantification of the abundance of multiple protein analytes and post-translational epitopes across large sample sets, reverse phase protein array (RPPA) has been utilized as a drug discovery tool. Key RPPA drug discovery applications include primary screening of abundance or activation state of nominated protein targets, secondary screening for toxicity and selectivity, mechanism-of-action profiling, biomarker discovery, and drug combination discovery. In recent decades, drug discovery strategies have evolved dramatically in response to continual advances in technology platforms supporting high-throughput screening, structure-based drug design, new therapeutic modalities, and increasingly more complex and disease-relevant cell-based and in vivo preclinical models of disease. Advances in biological laboratory capabilities in drug discovery are complemented by significant developments in bioinformatics and computational approaches for integrating large complex datasets. Bioinformatic and computational analysis of integrated molecular, pathway network and phenotypic datasets enhance multiple stages of the drug discovery process and support more informative drug target hypothesis generation and testing. In this chapter we discuss and present examples demonstrating how the latest advances in RPPA complement and integrate with other emerging drug screening platforms to support a new era of more informative and evidence-led drug discovery strategies.

Antitumor activity of arsenite in combination with tetrandrine against human breast cancer cell line MDA-MB-231 in vitro and in vivo

Background

Triple-negative breast cancer (TNBC) is one of the most difficult subtypes of breast cancer to treat due to its aggressive, metastatic behavior, and a lack of a targeted therapy. Trivalent arsenic derivatives (arsenite, As^III) with remarkable clinical efficacy in acute promyelocytic leukemia has been demonstrated to exhibit inhibitory effect against breast cancer cells. To provide novel insight into the development of new therapeutic strategies, antitumor activity of As^III and tetrandrine (Tetra), a Chinese plant-derived alkaloid, against the TNBC cell line MDA-MB-231 in vitro and in vivo was investigated.

Methods

Cytotoxicity was evaluated using cell viability, lactate dehydrogenase leakage and cell cycle assay. Alterations of genes related to cell proliferation and death were analyzed using western blotting. In vivo antitumor activity of As^III alone or in combination with Tetra was studied using MDA-MB-231 xenografts in nude mice.

Results

Synergistic cytotoxic effects of two drugs were observed in the cells. In vivo study also showed that co-administration of As^III and Tetra significantly reduced tumor volume and weight, directly supporting its in vitro antitumor activity. No deaths and reduction of body-weight were observed after a long-term co-administration, indicating its good tolerability. S-phase arrest associated with the upregulation of FOXO3a, p27 along with decreased Cyclin D1 expression was observed in the cells treated with the combined regimen. A substantial upregulated p21 expression and downregulated phospho-FOXO3a and Cyclin D1 expression was observed in the tumor tissues of mice co-administered with As^III and Tetra. Autophagy induction was observed in the combination treatment in vitro and in vivo. The addition of wortmannin, a potent autophagy inhibitor, significantly rescued MDA-MB-231 cells from their cytotoxicity of As^III and Tetra.

Conclusions

S-phase arrest, autophagic and necrotic cell death contribute to the cytocidal effects of the combined regimen of As^III and Tetra. Considering our previous study showing synergistic cytotoxic effects of the combined regimen in estrogen receptor-positive breast cancer cell line MCF-7, these results suggest that development of the combination regimen of As^III plus Tetra may offer many benefits to patients with different types of breast cancer.

Inflammatory breast cancer biology: the tumour microenvironment is key

Inflammatory breast cancer (IBC) is a rare and aggressive disease that accounts for ~2-4% of all breast cancers. However, despite its low incidence rate, IBC is responsible for 7-10% of breast cancer-related mortality in Western countries. Thus, the discovery of robust biological targets and the development of more effective therapeutics in IBC are crucial. Despite major international efforts to understand IBC biology, genomic studies have not led to the discovery of distinct biological mechanisms in IBC that can be translated into novel therapeutic strategies. In this Review, we discuss these molecular profiling efforts and highlight other important aspects of IBC biology. We present the intrinsic characteristics of IBC, including stemness, metastatic potential and hormone receptor positivity; the extrinsic features of the IBC tumour microenvironment (TME), including various constituent cell types; and lastly, the communication between these intrinsic and extrinsic components. We summarize the latest perspectives on the key biological features of IBC, with particular emphasis on the TME as an important contributor to the aggressive nature of IBC. On the basis of the current understanding of IBC, we hope to develop the next generation of translational studies, which will lead to much-needed survival improvements in patients with this deadly disease.

Activation of AMPK by simvastatin inhibited breast tumor angiogenesis via impeding HIF-1α-induced pro-angiogenic factor

Substantial data from preclinical studies have revealed the biphasic effects of statins on cardiovascular angiogenesis. Although some have reported the anti‐angiogenic potential of statins in malignant tumors, the underlying mechanism remains poorly understood. The aim of this study is to elucidate the mechanism by which simvastatin, a member of the statin family, inhibits tumor angiogenesis. Simvastatin significantly suppressed tumor cell‐conditioned medium‐induced angiogenic promotion in vitro, and resulted in dose‐dependent anti‐angiogenesis in vivo. Further genetic silencing of hypoxia‐inducible factor‐1α (HIF‐1α) reduced vascular endothelial growth factor and fibroblast growth factor‐2 expressions in 4T1 cells and correspondingly ameliorated HUVEC proliferation facilitated by tumor cell‐conditioned medium. Additionally, simvastatin induced angiogenic inhibition through a mechanism of post‐transcriptional downregulation of HIF‐1α by increasing the phosphorylation level of AMP kinase. These results were further validated by the fact that 5‐aminoimidazole‐4‐carboxamide ribonucleotide reduced HIF‐1α protein levels and ameliorated the angiogenic ability of endothelial cells in vitro and in vivo. Critically, inhibition of AMPK phosphorylation by compound C almost completely abrogated simvastatin‐induced anti‐angiogenesis, which was accompanied by the reduction of protein levels of HIF‐1α and its downstream pro‐angiogenic factors. These findings reveal the mechanism by which simvastatin induces tumor anti‐angiogenesis, and therefore identifies the target that explains the beneficial effects of statins on malignant tumors.

Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis

Obesity and cachexia represent divergent states of nutritional and metabolic imbalance but both are intimately linked to cancer. There is an extensive overlap in their signalling pathways and molecular components involved such as fatty acids (FAs), which likely play a crucial role in cancer. Forkhead box (FOX) proteins are responsible of a wide range of transcriptional programmes during normal development, and the FOXO3-FOXM1 axis is associated with cancer initiation, progression and drug resistance. Free fatty acids (FFAs), FA synthesis and β-oxidation are associated with cancer development and progression. Meanwhile, insulin and some adipokines, that are up-regulated by FAs, are also involved in cancer development and poor prognosis. In this review, we discuss the role of FA metabolism in cancer and how FA metabolism integrates with the FOXO3-FOXM1 axis. These new insights may provide leads to better cancer diagnostics as well as strategies for tackling cancer development, progression and drug resistance.

low neurotrophin receptor CD271 regulates phenotype switching in melanoma

Cutaneous melanoma represents the most fatal skin cancer due to its high metastatic capacity. According to the “phenotype switching” model, the aggressive nature of melanoma cells results from their intrinsic potential to dynamically switch from a high-proliferative/low-invasive to a low-proliferative/high-invasive state. Here we identify the low affinity neurotrophin receptor CD271 as a key effector of phenotype switching in melanoma. CD271 plays a dual role in this process by decreasing proliferation, while simultaneously promoting invasiveness. Dynamic modification of CD271 expression allows tumor cells to grow at low levels of CD271, to reduce growth and invade when CD271 expression is high, and to re-expand at a distant site upon decrease of CD271 expression. Mechanistically, the cleaved intracellular domain of CD271 controls proliferation, while the interaction of CD271 with the neurotrophin receptor Trk-A modulates cell adhesiveness through dynamic regulation of a set of cholesterol synthesis genes relevant for patient survival.

The aggressive nature of melanoma cells relies on their ability to switch from a high-proliferative/low-invasive to a low-proliferative/high-invasive state; however, the mechanisms governing this switch are unclear. Here, using in vivo models of human melanoma, the authors show that CD271 is a key regulator of phenotype switching and metastasis formation.

Marketed drugs used for the management of hypercholesterolemia as anticancer armament

The design of novel pharmacologic agents as well as their approval for sale in markets all over the world is a tedious and pricey process. Inevitably, oncologic patients commonly experience unwanted effects of new anticancer drugs, while the acquisition of clinical experience for these drugs is largely based on doctor–patient partnership which is not always effective. The repositioning of marketed non-antineoplastic drugs that hopefully exhibit anticancer properties into the field of oncology is a challenging option that gains ground and attracts preclinical and clinical research in an effort to override all these hindrances and minimize the risk for reduced efficacy and/or personalized toxicity. This review aims to present the anticancer properties of drugs used for the management of hypercholesterolemia. A global view of the antitumorigenicity of all marketed antihypercholesterolemic drugs is of major importance, given that atherosclerosis, which is etiologically linked to hypercholesterolemia, is a leading worldwide cause of morbidity and mortality, while hypercholesterolemia and tumorigenesis are known to be interrelated. In vitro, in vivo and clinical literature data accumulated so far outline the mechanistic basis of the antitumor function of these agents and how they could find application at the clinical setting.

Impact of Statin Use on Outcomes in Triple Negative Breast Cancer

Purpose: We sought to investigate if the use of HMG Co-A reductase inhibitors (statins) has an impact on outcomes among patients with triple negative breast cancer (TNBC).

Methods: We reviewed the cases of women with invasive, non-metastatic TNBC, diagnosed 1997-2012. Clinical outcomes were compared based on statin use (defined as ever use during treatment vs. never use). We identified a subset of women for whom a 5-value lipid panel (5VLP) was available, including total cholesterol, low density lipoprotein, high density lipoprotein, very low density lipoprotein, and triglycerides. The Kaplan-Meier method was used to estimate median overall survival (OS), distant metastases-free survival (DMFS), and local-regional recurrence-free survival (LRRFS). A Cox proportional hazards regression model was used to test the statistical significance of prognostic factors.

Results: 869 women were identified who met inclusion criteria, with a median follow-up time of 75.1 months (range 2.4-228.9 months). 293 (33.7%) patients used statins and 368 (42.3%) had a 5VLP. OS, DMFS, and LRRFS were not significant based on statin use or type. Controlling for the 5VLP values, on multivariable analysis, statin use was significantly associated with OS (HR 0.10, 95% CI 0.01-0.76), but not with DMFS (HR 0.14, 95% CI 0.01-1.40) nor LRRFS (HR 0.10 95% CI 0.00-3.51).

Conclusions: Statin use among patients with TNBC is not associated with improved OS, although it may have a benefit for a subset of patients. Prospective assessment would be valuable to better assess the potential complex correlation between clinical outcome, lipid levels, and statin use.

Fluvastatin Prevents Lung Adenocarcinoma Bone Metastasis by Triggering Autophagy

Bone is one of the most preferred sites of metastasis in lung cancer. Currently, bisphosphonates and denosumab are major agents for controlling tumor-associated skeletal-related events (SREs). However, both bisphosphonates and denosumab significantly increase the risk for jaw osteonecrosis. Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors and the most frequently prescribed cholesterol-lowering agents, have been reported to inhibit tumor progression and induce autophagy in cancer cells. However, the effects of statin and role of autophagy by statin on bone metastasis are unknown. In this study, we report that fluvastatin effectively prevented lung adenocarcinoma bone metastasis in a nude mouse model. We further reveal that fluvastatin-induced anti-bone metastatic property was largely dependent on its ability to induce autophagy in lung adenocarcinoma cells. Atg5 or Atg7 deletion, or 3-methyadenine (3-MA) or Bafilomycin A1 (Baf A1) treatment prevented the fluvastatin-induced suppression of bone metastasis. Furthermore, we reveal that fluvastatin stimulation increased the nuclear p53 expression, and fluvastatin-induced autophagy and anti-bone metastatic activity were mostly dependent on p53.

•

Fluvastatin effectively prevents lung adenocarcinoma bone metastasis in a nude mouse model.

•

Fluvastatin-induced anti-bone metastatic property was largely dependent on its ability to induce autophagy.

•

Fluvastatin-induced autophagy and anti-bone metastatic activity are mediated by p53.

Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are most frequently prescribed cholesterol-lowering agent with minimal side effects. In this study, we present a novel function of statins in suppressing lung adenocarcinoma bone metastasis, and this function is dependent on statin-induced autophagy. Currently, there is no cure for bone metastasis, and the current treatment options using anti-bone metastatic agents have negative side effects. For example, bisphosphonates or denosumab treatments reduce tumor-associated skeletal-related events, but simultaneously increase the risk of the osteonecrosis in the jaw. As a possible therapeutic treatment option, fluvastatin is promising to cancer patients with a high risk of bone metastasis.

Capsaicin Suppresses Cell Proliferation, Induces Cell Cycle Arrest and ROS Production in Bladder Cancer Cells through FOXO3a-Mediated Pathways

Capsaicin (CAP), a highly selective agonist for transient receptor potential vanilloid type 1 (TRPV1), has been widely reported to exhibit anti-oxidant, anti-inflammation and anticancer activities. Currently, several therapeutic approaches for bladder cancer (BCa) are available, but accompanied by unfavorable outcomes. Previous studies reported a potential clinical effect of CAP to prevent BCa tumorigenesis. However, its underlying molecular mechanism still remains unknown. Our transcriptome analysis suggested a close link among calcium signaling pathway, cell cycle regulation, ROS metabolism and FOXO signaling pathway in BCa. In this study, several experiments were performed to investigate the effects of CAP on BCa cells (5637 and T24) and NOD/SCID mice. Our results showed that CAP could suppress BCa tumorigenesis by inhibiting its proliferation both in vitro and in vivo. Moreover, CAP induced cell cycle arrest at G0/G1 phase and ROS production. Importantly, our studies revealed a strong increase of FOXO3a after treatment with CAP. Furthermore, we observed no significant alteration of apoptosis by CAP, whereas Catalase and SOD2 were considerably upregulated, which could clear ROS and protect against cell death. Thus, our results suggested that CAP could inhibit viability and tumorigenesis of BCa possibly via FOXO3a-mediated pathways.

Next-generation phenotypic screening

Phenotypic drug discovery (PDD) strategies are defined by screening and selection of hit or lead compounds based on quantifiable phenotypic endpoints without prior knowledge of the drug target. We outline the challenges associated with traditional phenotypic screening strategies and propose solutions and new opportunities to be gained by adopting modern PDD technologies. We highlight both historical and recent examples of approved drugs and new drug candidates discovered by modern phenotypic screening. Finally, we offer a prospective view of a new era of PDD underpinned by a wealth of technology advances in the areas of in vitro model development, high-content imaging and image informatics, mechanism-of-action profiling and target deconvolution.