Statins Reduce Melanoma Development and Metastasis through MICA Overexpression

Unraveling lipid metabolism reprogramming for overcoming drug resistance in melanoma

Cutaneous melanoma is the deadliest form of skin cancer, and its incidence is continuing to increase worldwide in the last decades. Traditional therapies for melanoma can easily cause drug resistance, thus the treatment of melanoma remains a challenge. Various studies have focused on reversing the drug resistance. As tumors grow and progress, cancer cells face a constantly changing microenvironment made up of different nutrients, metabolites, and cell types. Multiple studies have shown that metabolic reprogramming of cancer is not static, but a highly dynamic process. There is a growing interest in exploring the relationship between melanoma andmetabolic reprogramming, one of which may belipid metabolism. This review frames the recent research progresses on lipid metabolism in melanoma.In addition, we emphasize the dynamic ability of metabolism during tumorigenesis as a target for improving response to different therapies and for overcoming drug resistance in melanoma.

Low-Dose Atorvastatin has Promoting Effect on Melanoma Tumor Growth and Angiogenesis in Mouse Model

Background

Preclinical evidence indicates that statins possess diverse antineoplastic effects in different types of tumors. However, clinical studies have yielded conflicting results regarding the potential of statins to either increase or decrease the risk of cancer. Our objective was to examine the relationship between the dose of a treatment and its impact on melanoma tumor growth and angiogenesis in an in vivo setting.

Materials and Methods

Melanoma cells were injected into C57BL6 mice in four groups. They received 0, 1, 5, and 10 mg/kg of atorvastatin daily. Three others received the mentioned doses one week before the inoculation of melanoma animals. At the end of the third week, the animals were euthanized in a humane manner, and both blood samples and tumor specimens were collected for subsequent analysis.

Results

The tumor size was 1.16 ± 0.25 cm3 in a group treated with therapeutic dose of atorvastatin and was significantly larger than that in the control group (0.42 ± 0.08 cm3). However, there were no significant differences between the two other doses and the control group (0.72 ± 0.22, 0.46 ± 0.08 cm3 in atorvastatin-treated groups with 5 and 10 mg/kg). The vascular density of the tumors was significantly increased in the lowest dose of the atorvastatin treatment group, similar to the results of tumor size (P < 0.05).

Conclusion

Atorvastatin, at low therapeutic concentrations, has been observed to stimulate tumor growth and exhibit pro-angiogenic effects. Therefore, it is advised to exercise caution and recommend clinically relevant doses of statins to patients with cancer.

New insights into the therapeutic potentials of statins in cancer

The widespread clinical use of statins has contributed to significant reductions of cardiovascular morbidity and mortality. Increasing preclinical and epidemiological evidences have revealed that dyslipidemia is an important risk factor for carcinogenesis, invasion and metastasis, and that statins as powerful inhibitor of HMG-CoA reductase can exert prevention and intervention effects on cancers, and promote sensitivity to anti-cancer drugs. The anti-cancer mechanisms of statins include not only inhibition of cholesterol biosynthesis, but also their pleiotropic effects in modulating angiogenesis, apoptosis, autophagy, tumor metastasis, and tumor microenvironment. Moreover, recent clinical studies have provided growing insights into the therapeutic potentials of statins and the feasibility of combining statins with other anti-cancer agents. Here, we provide an updated review on the application potential of statins in cancer prevention and treatment and summarize the underneath mechanisms, with focuses on data from clinical studies.

Epigenetic suppression of PGC1α (PPARGC1A) causes collateral sensitivity to HMGCR-inhibitors within BRAF-treatment resistant melanomas

While targeted treatment against BRAF(V600E) improve survival for melanoma patients, many will see their cancer recur. Here we provide data indicating that epigenetic suppression of PGC1α defines an aggressive subset of chronic BRAF-inhibitor treated melanomas. A metabolism-centered pharmacological screen further identifies statins (HMGCR inhibitors) as a collateral vulnerability within PGC1α-suppressed BRAF-inhibitor resistant melanomas. Lower PGC1α levels mechanistically causes reduced RAB6B and RAB27A expression, whereby their combined re-expression reverses statin vulnerability. BRAF-inhibitor resistant cells with reduced PGC1α have increased integrin-FAK signaling and improved extracellular matrix detached survival cues that helps explain their increased metastatic ability. Statin treatment blocks cell growth by lowering RAB6B and RAB27A prenylation that reduces their membrane association and affects integrin localization and downstream signaling required for growth. These results suggest that chronic adaptation to BRAF-targeted treatments drive novel collateral metabolic vulnerabilities, and that HMGCR inhibitors may offer a strategy to treat melanomas recurring with suppressed PGC1α expression.

Investigating potential anti-proliferative activity of different statins against five cancer cell lines

Statins have been reported to have potential anti-proliferative effects through an unknown mechanism. This study aims to investigate the anti-proliferative activities of five statins, including simvastatin, rosuvastatin, fluvastatin, atorvastatin, and pravastatin, against five different cancer cell lines; cervical epithelial carcinoma DoTc2 4510, malignant melanoma A-375, muscle Ewing's sarcoma A-673, hepatocellular carcinoma HUH-7, as well as breast cancer cells MCF-7. At 100 µM, simvastatin and atorvastatin significantly inhibited 70% of cellular proliferation. At the same concentration, rosuvastatin and fluvastatin showed about 50% of inhibition only in A-375 and A-673 cancer cells in a time- and dose-dependent manner. Of all the statin drugs used, pravastatin had the least inhibitory effect on all the cancer cell lines. Western Blot analysis showed a decrease in mTOR level, and the expression of p53 tumour suppression and BCL-2 proteins was relatively elevated compared to the untreated cells. Simvastatin and atorvastatin may inhibit cellular proliferation via BCL-2/p53, Bax/Bak, and PI3K/Akt/mTOR signalling pathways. This is the first research to evaluate the anti-cancer effects of simvastatin, rosuvastatin, fluvastatin, atorvastatin, and pravastatin against five different cell lines from distinct origins and provided a relevant comparison of their efficacies for their anti-proliferative activity.

Suppression of Ca2+ signaling enhances melanoma progression

The role of store-operated Ca2+ entry (SOCE) in melanoma metastasis is highly controversial. To address this, we here examined UV-dependent metastasis, revealing a critical role for SOCE suppression in melanoma progression. UV-induced cholesterol biosynthesis was critical for UV-induced SOCE suppression and subsequent metastasis, although SOCE suppression alone was both necessary and sufficient for metastasis to occur. Further, SOCE suppression was responsible for UV-dependent differences in gene expression associated with both increased invasion and reduced glucose metabolism. Functional analyses further established that increased glucose uptake leads to a metabolic shift towards biosynthetic pathways critical for melanoma metastasis. Finally, examination of fresh surgically isolated human melanoma explants revealed cholesterol biosynthesis-dependent reduced SOCE. Invasiveness could be reversed with either cholesterol biosynthesis inhibitors or pharmacological SOCE potentiation. Collectively, we provide evidence that, contrary to current thinking, Ca2+ signals can block invasive behavior, and suppression of these signals promotes invasion and metastasis.

Can statins lessen the burden of virus mediated cancers?

BACKGROUND

Oncogenic viruses, including hepatitis B virus (HBV), hepatitis C virus (HCV), human papillomavirus (HPV), Epstein Barr virus (EBV), and Kaposi Sarcoma Herpes virus (KSHV) contribute to a significant proportion of the world's cancers. Given the sizeable burden of virus mediated cancers, development of strategies to prevent and/or treat these cancers is critical. While large population studies suggest that treatment with hydroxymethylglutaryl-CoA reductase inhibitors, commonly known as statins, may reduce the risk of many cancer types including HBV/HCV related hepatocellular carcinoma, few studies have specifically evaluated the impact of statin use in populations at risk for other types of virus mediated cancers.

MAIN BODY

Studies of populations with HBV and HCV suggest a protective, dose-dependent effect of statins on hepatocellular carcinoma risk and support the theory that statins may offer clinical benefit if used as chemoprophylactic agents to reduce liver cancer incidence. However, no population level data exists describing the impact of statins on populations with other oncogenic viral infections, such as HPV, EBV, and KSHV.

CONCLUSION

Further study of statin use in diverse, global populations with or at high risk for oncogenic viral infections is essential to determine the impact of statin therapy on virus mediated cancer risk.

The cholesterol pathway: impact on immunity and cancer

Cholesterol is a multifaceted metabolite that is known to modulate processes in cancer, atherosclerosis, and autoimmunity. A common denominator between these diseases appears to be the immune system, in which many cholesterol-associated metabolites impact both adaptive and innate immunity. Many cancers display altered cholesterol metabolism, and recent studies demonstrate that manipulating systemic cholesterol metabolism may be useful in improving immunotherapy responses. However, cholesterol can have both proinflammatory and anti-inflammatory roles in mammals, acting via multiple immune cell types, and depending on context. Gaining mechanistic insights into various cholesterol-related metabolites can improve our understanding of their functions and extensive effects on the immune system, and ideally will inform the design of future therapeutic strategies against cancer and/or other pathologies.

Targeting the Tumor Microenvironment: A Literature Review of the Novel Anti-Tumor Mechanism of Statins

Statins is widely used in clinical practice as lipid-lowering drugs and has been proven to be effective in the treatment of cardiovascular, endocrine, metabolic syndrome and other diseases. The latest preclinical evidence shows that statins have anti-proliferation, pro-apoptotic, anti-invasion and radiotherapy sensitization effects on tumor cells, suggesting that statins may become a new type of anti-tumor drugs. For a long time, mevalonate pathway has been proved to play a supporting role in the development of tumor cells. As an effective inhibitor of mevalonate pathway, statins have been proved to have a direct auxiliary anti-tumor effect in a large number of studies. In addition, anti-tumor effects of statins through ferroptosis, pyroptosis, autophagy and tumor microenvironment (TME) have also been gradually discovered. However, the specific mechanism of the antitumor effect of statins in the tumor microenvironment has not been clearly elucidated. Herein, we reviewed the antitumor effects of statins in tumor microenvironment, focusing on hypoxia microenvironment, immune microenvironment, metabolic microenvironment, acid microenvironment and mechanical microenvironment.

Cholesterol Regulates the Tumor Adaptive Resistance to MAPK Pathway Inhibition

Although targeted MAPK pathway inhibition has achieved remarkable patient responses in many cancers, the development of resistance has remained a critical challenge. Adaptive tumor response underlies the drug resistance. Furthermore, such bypass mechanisms often lead to the activation of many pro-survival kinases, which complicates the rational design of combination therapies. Here, we performed global tyrosine phosphoproteomic (pTyr) analyses and demonstrated that targeted MAPK signaling inhibition in melanoma leads to a profound remodeling of the pTyr proteome. Intriguingly, altered cholesterol metabolism might drive, in a coordinated fashion, the activation of these kinases. Indeed, we found an accumulation of intracellular cholesterol in melanoma cells (with BRAF^V600E mutations) and non-small cell lung cancer cells (with KRAS^G12C mutations) treated with MAPK and KRAS^G12C inhibitors, respectively. Importantly, depletion of cholesterol not only prevents the feedback activation of pTyr signaling but also enhances the cytotoxic effects of MAPK pathway inhibitors, both in vitro and in vivo. Together, our findings suggest that cholesterol contributes to the tumor adaptive response upon targeted MAPK pathway inhibitors. These results also suggest that MAPK pathway inhibitors could be combined with cholesterol-lowering agents to achieve a more complete and durable response in tumors with hyperactive MAPK signaling.

Computational Drug Repositioning Identifies Statins as Modifiers of Prognostic Genetic Expression Signatures and Metastatic Behavior in Melanoma

Despite advances in melanoma treatment, more than 70% of patients with distant metastasis die within 5 years. Proactive treatment of early melanoma to prevent metastasis could save lives and reduce overall healthcare costs. Currently, there are no treatments specifically designed to prevent early melanoma from progressing to metastasis. We used the Connectivity Map to conduct an in silico drug screen and identified 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) as a drug class that might prevent melanoma metastasis. To confirm the in vitro effect of statins, RNA sequencing was completed on A375 cells after treatment with fluvastatin to describe changes in the melanoma transcriptome. Statins induced differential expression in genes associated with metastasis and are used in commercially available prognostic tests for melanoma metastasis. Finally, we completed a chart review of 475 patients with melanoma. Patients taking statins were less likely to have metastasis at the time of melanoma diagnosis in both univariate and multivariate analyses (24.7% taking statins vs. 37.6% not taking statins, absolute risk reduction = 12.9%, P = 0.038). These findings suggest that statins might be useful as a treatment to prevent melanoma metastasis. Prospective trials are required to verify our findings and to determine the mechanism of metastasis prevention.

Lipid metabolic Reprogramming: Role in Melanoma Progression and Therapeutic Perspectives

Simple Summary

Melanoma is a devastating skin cancer characterized by an impressive metabolic plasticity. Melanoma cells are able to adapt to the tumor microenvironment by using a variety of fuels that contribute to tumor growth and progression. In this review, the authors summarize the contribution of the lipid metabolic network in melanoma plasticity and aggressiveness, with a particular attention to specific lipid classes such as glycerophospholipids, sphingolipids, sterols and eicosanoids. They also highlight the role of adipose tissue in tumor progression as well as the potential antitumor role of drugs targeting critical steps of lipid metabolic pathways in the context of melanoma.

Abstract

Metabolic reprogramming contributes to the pathogenesis and heterogeneity of melanoma. It is driven both by oncogenic events and the constraints imposed by a nutrient- and oxygen-scarce microenvironment. Among the most prominent metabolic reprogramming features is an increased rate of lipid synthesis. Lipids serve as a source of energy and form the structural foundation of all membranes, but have also emerged as mediators that not only impact classical oncogenic signaling pathways, but also contribute to melanoma progression. Various alterations in fatty acid metabolism have been reported and can contribute to melanoma cell aggressiveness. Elevated expression of the key lipogenic fatty acid synthase is associated with tumor cell invasion and poor prognosis. Fatty acid uptake from the surrounding microenvironment, fatty acid β-oxidation and storage also appear to play an essential role in tumor cell migration. The aim of this review is (i) to focus on the major alterations affecting lipid storage organelles and lipid metabolism. A particular attention has been paid to glycerophospholipids, sphingolipids, sterols and eicosanoids, (ii) to discuss how these metabolic dysregulations contribute to the phenotype plasticity of melanoma cells and/or melanoma aggressiveness, and (iii) to highlight therapeutic approaches targeting lipid metabolism that could be applicable for melanoma treatment.

Recycling the Purpose of Old Drugs to Treat Ovarian Cancer

The main challenge in ovarian cancer treatment is the management of recurrences. Facing this scenario, therapy selection is based on multiple factors to define the best treatment sequence. Target therapies, such as bevacizumab and polymerase (PARP) inhibitors, improved patient survival. However, despite their achievements, ovarian cancer survival remains poor; these therapeutic options are highly costly and can be associated with potential side effects. Recently, it has been shown that the combination of repurposed, conventional, chemotherapeutic drugs could be an alternative, presenting good patient outcomes with few side effects and low costs for healthcare institutions. The main aim of this review is to strengthen the importance of repurposed drugs as therapeutic alternatives, and to propose an in vitro model to assess the therapeutic value. Herein, we compiled the current knowledge on the most promising non-oncological drugs for ovarian cancer treatment, focusing on statins, metformin, bisphosphonates, ivermectin, itraconazole, and ritonavir. We discuss the primary drug use, anticancer mechanisms, and applicability in ovarian cancer. Finally, we propose the use of these therapies to perform drug efficacy tests in ovarian cancer ex vivo cultures. This personalized testing approach could be crucial to validate the existing evidences supporting the use of repurposed drugs for ovarian cancer treatment.

Apolipoprotein A-I anti-tumor activity targets cancer cell metabolism

Previously, we reported apolipoprotein A-I (apoA-I), the major protein component of high-density lipoprotein (HDL), has potent anti-melanoma activity. We used DNA microarray and bioinformatics to interrogate gene expression profiles of tumors from apoA-I expressing (A-I Tg+/-) versus apoA-I-null (A-I KO) animals to gain insights into mechanisms of apoA-I tumor protection. Differential expression analyses of 11 distinct tumors per group with > 1.2-fold cut-off and a false discovery rate adjusted p < 0.05, identified 176 significant transcripts (71 upregulated and 105 downregulated in A-I Tg+/- versus A-I KO group). Bioinformatic analyses identified the mevalonate and de novo serine/glycine synthesis pathways as potential targets for apoA-I anti-tumor activity. Relative to A-I KO, day 7 B16F10L melanoma tumor homografts from A-I Tg+/- exhibited reduced expression of mevalonate-5-pyrophosphate decarboxylase (Mvd), a key enzyme targeted in cancer therapy, along with a number of key genes in the sterol synthesis arm of the mevalonate pathway. Phosphoglycerate dehydrogenase (Phgdh), the first enzyme branching off glycolysis into the de novo serine synthesis pathway, was the most repressed transcript in tumors from A-I Tg+/-. We validated our mouse tumor studies by comparing the significant transcripts with adverse tumor markers previously identified in human melanoma and found 45% concordance. Our findings suggest apoA-I targets the mevalonate and serine synthesis pathways in melanoma cells in vivo, thus providing anti-tumor metabolic effects by inhibiting the flux of biomolecular building blocks for macromolecule synthesis that drive rapid tumor growth.

Statins may reduce disease recurrence in patients with ulcerated primary melanoma

BACKGROUND

Statins may restrict the cellular functions required for melanoma growth and metastasis.

OBJECTIVES

To determine whether long-term statin use commenced before diagnosis of a primary melanoma is associated with reduced risk of melanoma recurrence.

METHODS

We prospectively followed a cohort of patients newly diagnosed between 2010 and 2014 with localized tumour-stage T1b to T4b melanoma in Queensland, Australia. We used Cox regression analyses to examine associations between long-term statin use and melanoma recurrence for the entire cohort, and then separately by sex and by presence of ulceration, due to evidence of effect modification.

RESULTS

Among 700 patients diagnosed with stage T1b to T4b primary melanoma (mean age 62 years, 59% male, 28% with ulcerated tumours), 94 patients (13%) developed melanoma recurrence within 2 years. Long-term statin users (n = 204, 29%) had a significantly lower risk of disease recurrence than nonusers [adjusted hazard ratio (HR_adj ) 0·55, 95% confidence Interval (CI) 0·32-0·97] regardless of statin subtype or potency. Compared with nonusers of statins, risk of recurrence was significantly decreased in male statin users (HR_adj 0·39, 95% CI 0·19-0·79) but not in female statin users (HR_adj 0·82, 95% CI 0·29-2·27) and in statin users with ulcerated (HR_adj 0·17, 95% CI 0·05-0·52) but not nonulcerated (HR_adj 0·91, 95% CI 0·46-1·81) primary melanoma.

CONCLUSIONS

Statins commenced before melanoma diagnosis may reduce the risk of melanoma recurrence, especially in men and in those with ulcerated tumours. Clinical trial evaluation of the potential role of statins in improving the prognosis of high-risk melanoma is warranted.

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.

Delineation of cell death mechanisms induced by synergistic effects of statins and erlotinib in non-small cell lung cancer cell (NSCLC) lines

Hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) have been shown to overcome tyrosine kinase inhibitor (TKI) resistance in epithelial growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC) cells in vivo and in vitro. However, little is known about the putative induction of non-apoptotic cell death pathways by statins. We investigated the effects of pitavastatin and fluvastatin alone or in combination with erlotinib in three NSCLC cell lines and examined the activation of different cell death pathways. We assessed apoptosis via fluorometric caspase assay and poly (ADP-ribose) polymerase 1 (PARP) cleavage. Furthermore, annexinV/propidium iodide (PI) flow cytometry was performed. Small molecule inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD), necrostatin 1 (Nec1), ferrostatin 1 (Fer1), Ac-Lys-Lys-Norleucinal (Calp1) were used to characterise cell death pathway(s) putatively (co-)activated by pitavastatin/erlotinib co-treatment. Synergism was calculated by additivity and isobolographic analyses. Pitavastatin and fluvastatin induced cell death in EGFR TKI resistant NSCLC cells lines A549, Calu6 and H1993 as shown by caspase 3 activation and PARP cleavage. Co-treatment of cells with pitavastatin and the EGFR TKI erlotinib resulted in synergistically enhanced cytotoxicity compared to pitavastatin monotherapy. Flow cytometry indicated the induction of alternative regulated cell death pathways. However, only co-treatment with mevalonic acid (Mev) or the pan-caspase inhibitor zVAD could restore cell viability. The results show that cytotoxicity mediated by statin/erlotinib co-treatment is synergistic and can overcome erlotinib resistance in K-ras mutated NSCLC and relies only on apoptosis.

Proteome and phosphoproteome reveal mechanisms of action of atorvastatin against esophageal squamous cell carcinoma

Statins comprise a class of prescription drugs used for reducing cholesterol. Evidence has also showed that statins could reduce cancer incidence. However, the anti-tumor mechanism of statins has not been fully defined. Here, we found that atorvastatin inhibited proliferation of esophageal squamous cell carcinoma (ESCC) cells. The underlying mechanisms were explored by mass spectrometry. The proteome data revealed that atorvastatin inhibited the cAMP and Rap1 signal pathways, except for Ras signal pathway. Interestingly, phosphoproteome profiles suggested that ERK^T185/Y187, CDK1^T14, and BRAC1^S1189 phosphorylation–mediated Th17 cell differentiation, Gap junction and the Platinum drug resistance pathway were down-regulated after atorvastatin treatment. The phosphorylation levels of ERK^T185/Y187, CDK1^T14 and BRAC1^S1189 were confirmed by western blotting in KYSE150 cells. More importantly, atorvastatin suppresses ESCC tumor growth in PDX models. The molecular changes in tumor tissues were confirmed by immunohistochemistry. In conclusion, deep-proteome and phosphoproteome analysis reveal a comprehensive mechanism that contributes to atorvastatin’s anti-tumor effect.

Drug consumption and melanocytic nevi: correlation between oral contraceptives or hormone replacement therapy and a high melanocytic nevi count

The prolonged use of drugs such as beta-blockers, acetylsalicylic acid, omeprazole, statins, oral contraceptives and hormone replacement therapy might have some role in melanocytic nevi development and be ultimately linked to melanoma risk. Aims of the study were to evaluate a possible association between the above-mentioned drugs and features such as number and atypia of melanocytic nevi in long-term users. We retrospectively looked at pharmacological, clinical and dermoscopic records of 1321 patients that attended our unit for routine mole check between January 2013 and January 2018. Patients were divided into two groups (low or high melanocytic nevi count), and multivariate analysis was performed with regards to the presence and number of melanocytic nevi and drug assumption. A positive association between the use of oral contraceptives or hormone replacement therapy (P = 0.012) and a high melanocytic nevi count was found through multivariate analysis, after adjusting for sex, age and multiple confounding factors, such as freckles, phototype and a reported history of sun exposure and sunburns. Further prospective studies are necessary to establish whether women using oral contraceptives or on hormone replacement therapy should undergo periodic monitoring of pigmented lesions.

The emerging role of γδ T cells in cancer immunotherapy

The recent successes of chimeric antigen receptor T cells in the treatment of hematological malignancies have clearly led to an explosion in the field of adoptive cell therapy for cancer. Current efforts are focused on the translation of this exciting technology to the treatment of solid tumors and the development of allogeneic ‘off-the-shelf’ therapies. γδ T cells are currently gaining considerable attention in this field as their unique biology and established role in cancer immunosurveillance place them in a unique position to potentially overcome these challenges in adoptive cell therapy. Here, we review the relevant aspects of the function of γδ T cells in cancer immunity, and summarize clinical observations and clinical trial results that highlight their emerging role as a platform for the development of safe and effective cancer immunotherapies.

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γδ T cells are a unique subset of T cells combining innate and adaptive features.

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Tissue-resident γδ T cells have important functions in tissue and cancer immunosurveillance.

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γδ T cells are being exploited increasingly for cancer immunotherapy.

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.

Fluorescence-guided surgery for cancer patients: a proof of concept study on human xenografts in mice and spontaneous tumors in pets

Surgery is often the first treatment option for patients with cancer. Patient survival essentially depends on the completeness of tumor resection. This is a major challenge, particularly in cases of peritoneal carcinomatosis, where tumors are widely disseminated in the large peritoneal cavity. Any development to help surgeons visualize these residual cells would improve the completeness of the surgery. For non-disseminated tumors, imaging could be used to ensure that the tumor margins and the draining lymph nodes are free of tumor deposits.

Near-infrared fluorescence imaging has been shown to be one of the most convenient imaging modalities. Our aim was to evaluate the efficacy of a near-infrared fluorescent probe targeting the αvβ3 integrins (Angiostamp™) for intraoperative detection of tumors using the Fluobeam® device.

We determined whether different human tumor nodules from various origins could be detected in xenograft mouse models using both cancer cell lines and patient-derived tumor cells. We found that xenografts could be imaged by fluorescent staining irrespective of their integrin expression levels. This suggests imaging of the associated angiogenesis of the tumor and a broader potential utilization of Angiostamp™. We therefore performed a veterinary clinical trial in cats and dogs with local tumors or with spontaneous disseminated peritoneal carcinomatosis. Our results demonstrate that the probe can specifically visualize both breast and ovarian nodules, and suggest that Angiostamp™ is a powerful fluorescent contrast agent that could be used in both human and veterinary clinical trials for intraoperative detection of tumors.

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.

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

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

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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.

Prenylated Polyphenols from Clusiaceae and Calophyllaceae with Immunomodulatory Activity on Endothelial Cells

Endothelial cells (ECs) are key players in inflammation and immune responses involved in numerous pathologies. Although attempts were experimentally undertaken to prevent and control EC activation, drug leads and probes still remain necessary. Natural products (NPs) from Clusiaceous and Calophyllaceous plants were previously reported as potential candidates to prevent endothelial dysfunction. The present study aimed to identify more precisely the molecular scaffolds that could limit EC activation. Here, 13 polyphenols belonging to 5 different chemical types of secondary metabolites (i.e., mammea coumarins, a biflavonoid, a pyranochromanone acid, a polyprenylated polycyclic acylphloroglucinol (PPAP) and two xanthones) were tested on resting and cytokine-activated EC cultures. Quantitative and qualitative changes in the expression of both adhesion molecules (VCAM-1, ICAM-1, E-selectin) and major histocompatibility complex (MHC) molecules have been used to measure their pharmaceutical potential. As a result, we identified 3 mammea coumarins that efficiently reduce (up to >90% at 10 μM) both basal and cytokine-regulated levels of MHC class I, class II, MICA and HLA-E on EC surface. They also prevented VCAM-1 induction upon inflammation. From a structural point of view, our results associate the loss of the free prenyl group substituting mammea coumarins with a reduced cellular cytotoxicity but also an abrogation of their anti-inflammatory potential and a reduction of their immunosuppressive effects. A PPAP, guttiferone J, also triggers a strong immunomodulation but restricted to HLA-E and MHC class II molecules. In conclusion, mammea coumarins with a free prenyl group and the PPAP guttiferone J emerge as NPs able to drastically decrease both VCAM-1 and a set of MHC molecules and to potentially reduce the immunogenicity of the endothelium.

The HMG-CoA reductase inhibitor, simvastatin, exhibits anti-metastatic and anti-tumorigenic effects in ovarian cancer

Ovarian cancer is the 5th leading cause of cancer death among women in the United States. The mevalonate pathway is thought to be a potential oncogenic pathway in the pathogenesis of ovarian cancer. Simvastatin, a 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) inhibitor, is a widely used drug for inhibiting the synthesis of cholesterol and may also have anti-tumorigenic activity. Our goal was to evaluate the effects of simvastatin on ovarian cancer cell lines, primary cultures of ovarian cancer cells and in an orthotopic ovarian cancer mouse model. Simvastatin significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, and caused cellular stress via reduction in the enzymatic activity of HMGCR and inhibition of the MAPK and mTOR pathways in ovarian cancer cells. Furthermore, simvastatin induced DNA damage and reduced cell adhesion and invasion. Simvastatin also exerted anti-proliferative effects on primary cell cultures of ovarian cancer. Treatment with simvastatin in an orthotopic mouse model reduced ovarian tumor growth, coincident with decreased Ki-67, HMGCR, phosphorylated-Akt and phosphorylated-p42/44 protein expression. Our findings demonstrate that simvastatin may have therapeutic benefit for ovarian cancer treatment and be worthy of further exploration in clinical trials.

Regulatory properties of statins and rho gtpases prenylation inhibitiors to stimulate melanoma immunogenicity and promote anti-melanoma immune response

Melanoma is a highly lethal cutaneous tumor, killing affected patients through development of multiple poorly immunogenic metastases. Suboptimal activation of immune system by melanoma cells is often due to molecular modifications occurring during tumor progression that prevent efficient recognition of melanoma cells by immune effectors. Statins are HMG-CoA reductase inhibitors, which block the mevalonate synthesis pathway, used by millions of people as hypocholesterolemic agents in cardiovascular and cerebrovascular diseases. They are also known to inhibit Rho GTPase activation and Rho dependent signaling pathways. Rho GTPases are regarded as molecular switches that regulate a wide spectrum of cellular functions and their dysfunction has been characterized in various oncogenic process notably in melanoma progression. Moreover, these molecules can modulate the immune response. Since 10 years we have demonstrated that Statins and other Rho GTPases inhibitors are critical regulators of molecules involved in adaptive and innate anti-melanoma immune response. In this review we summarize our major observations demonstrating that these pharmacological agents stimulate melanoma immunogenicity and suggest a potential use of these molecules to promote anti-melanoma immune response.

Anti-proliferative and cytotoxic activity of rosuvastatin against melanoma cells

Introduction

Statins are considered potential candidate agents for melanoma chemoprevention. Statin-induced mevalonate pathway inhibition leads to reduction of cholesterol synthesis and also to decreased cellular levels of non-steroidal isoprenoids, geranylgeranyl pyrophosphate and farnesyl pyrophosphate. This results in the impairment of protein prenylation which affects carcinogenesis.

Aim

To analyze anti-proliferative and cytotoxic activity of rosuvastatin against melanoma cells.

Material and methods

Melanoma cell lines (A375 and WM1552C) and normal fibroblasts (BJ) were used as the primary research material. Cells were treated with rosuvastatin at concentrations ranging from 0.01 µM to 10 µM. Cell viability was analyzed with the use of an MTT assay. Expression of proliferation marker Ki67 was assessed on the basis of immunofluorescence staining.

Results

Rosuvastatin reduced A375 and BJ cell viability in a time- and dose-dependent manner. After 72 h incubation, the IC₅₀, half maximal inhibitory concentration, was 2.3 µM for melanoma cells and 7.4 µM for normal fibroblasts. In turn, rosuvastatin exhibited relatively lower activity against WM1552C cells. A significant reduction of Ki67 expression was also noted for BJ fibroblasts after prolonged incubation with the tested drug.

Conclusions

The results indicate that the anti-melanoma properties of rosuvastatin are highly dependent on the tumor cell line assessed. However, the concentrations required to decrease melanoma cell viability in vitro exceed the plasma concentrations reached in patients treated with rosuvastatin at well-tolerated doses. What is more disturbing, reduction of proliferation and viability observed in BJ fibroblasts indicated that rosuvastatin at high doses may be toxic for normal cells.

Tocilizumab unmasks a stage-dependent interleukin-6 component in statin-induced apoptosis of metastatic melanoma cells

The interleukin (IL)-6 inhibits the growth of early-stage melanoma cells, but not metastatic cells. Metastatic melanoma cells are susceptible to statin-induced apoptosis, but this is not clear for early-stage melanoma cells. This study aimed to investigate the IL-6 susceptibility of melanoma cells from different stages in the presence of simvastatin to overcome loss of growth arrest. ELISA was used to detect secreted IL-6 in human melanoma cells. The effects of IL-6 were measured by western blots for STAT3 and Bcl-2 family proteins. Apoptosis and proliferation were measured by caspase 3 activity, Annexin V staining, cell cycle analysis, and a wound-healing assay. Human metastatic melanoma cells A375 and 518A2 secrete high amounts of IL-6, in contrast to early-stage WM35 cells. Canonical IL-6 signaling is intact in these cells, documented by transient phosphorylation of STAT3. Although WM35 cells are highly resistant to simvastatin-induced apoptosis, coadministration with IL-6 enhanced the susceptibility to undergo apoptosis. This proapoptotic effect of IL-6 might be explained by a downregulation of Bcl-X_L, observed only in WM35 cells. Furthermore, the IL-6 receptor blocking antibody tocilizumab was coadministered and unmasked an IL-6-sensitive proportion in the simvastatin-induced caspase 3 activity of metastatic melanoma cells. These results confirm that simvastatin facilitates apoptosis in combination with IL-6. Although endogenous IL-6 secretion is sufficient in metastatic melanoma cells, exogenously added IL-6 is needed for WM35 cells. This effect may explain the failure of simvastatin to reduce melanoma incidence in clinical trials and meta-analyses.

Could drugs inhibiting the mevalonate pathway also target cancer stem cells?

Understanding the connection between metabolic pathways and cancer is very important for the development of new therapeutic approaches based on regulatory enzymes in pathways associated with tumorigenesis. The mevalonate cascade and its rate-liming enzyme HMG CoA-reductase has recently drawn the attention of cancer researchers because strong evidences arising mostly from epidemiologic studies, show that it could promote transformation. Hence, these studies pinpoint HMG CoA-reductase as a candidate proto-oncogene. Several recent epidemiological studies, in different populations, have proven that statins are beneficial for the treatment-outcome of various cancers, and may improve common cancer therapy strategies involving alkylating agents, and antimetabolites. Cancer stem cells/cancer initiating cells (CSC) are key to cancer progression and metastasis. Therefore, in the current review we address the different effects of statins on cancer stem cells. The mevalonate cascade is among the most pleiotropic, and highly interconnected signaling pathways. Through G-protein-coupled receptors (GRCP), it integrates extra-, and intracellular signals. The mevalonate pathway is implicated in cell stemness, cell proliferation, and organ size regulation through the Hippo pathway (e.g. Yap/Taz signaling axis). This pathway is a prime preventive target through the administration of statins for the prophylaxis of obesity-related cardiovascular diseases. Its prominent role in regulation of cell growth and stemness also invokes its role in cancer development and progression. The mevalonate pathway affects cancer metastasis in several ways by: (i) affecting epithelial-to-mesenchymal transition (EMT), (ii) affecting remodeling of the cytoskeleton as well as cell motility, (iii) affecting cell polarity (non-canonical Wnt/planar pathway), and (iv) modulation of mesenchymal-to-epithelial transition (MET). Herein we provide an overview of the mevalonate signaling network. We then briefly highlight diverse functions of various elements of this mevalonate pathway. We further discuss in detail the role of elements of the mevalonate cascade in stemness, carcinogenesis, cancer progression, metastasis and maintenance of cancer stem cells.

Exploitation of pleiotropic actions of statins by using tumour-targeted delivery systems

Statins are drugs traditionally used to lower cholesterol levels in blood. At concentrations 100- to 500-fold higher than those needed for reaching cholesterol lowering activity, they have anti-tumour activity. This anti-tumour activity is based on statins pleiotropic effects derived from their ability to inhibit the mevalonate synthesis and include anti-proliferative, pro-apoptotic, anti-angiogenic, anti-inflammatory, anti-metastatic actions and modulatory effects on intra-tumour oxidative stress. Thus, in this review, we summarise the possible pleiotropic actions of statins involved in tumour growth inhibition. Since the administration of these high doses of statins is accompanied by severe side effects, targeted delivery of statins seems to be the appropriate strategy for efficient application of statins in oncology. Therefore, we also present an overview of the current status of targeted delivery systems for statins with possible utilisation in oncology.

Autocrine secretion of 15d-PGJ2 mediates simvastatin-induced apoptotic burst in human metastatic melanoma cells

BACKGROUND AND PURPOSE

Despite new therapeutic approaches, metastatic melanomas still have a poor prognosis. Statins reduce low-density lipoprotein cholesterol and exert anti-inflammatory and anti-proliferative actions. We have recently shown that simvastatin triggers an apoptotic burst in human metastatic melanoma cells by the synthesis of an autocrine factor.

EXPERIMENTAL APPROACH

The current in vitro study was performed in human metastatic melanoma cell lines (A375, 518a2) and primary human melanocytes and melanoma cells. The secretome of simvastatin-stressed cells was analysed with two-dimensional difference gel electrophoresis and MS. The signalling pathways involved were analysed at the protein and mRNA level using pharmacological approaches and siRNA technology.

KEY RESULTS

Simvastatin was shown to activate a stress cascade, leading to the synthesis of 15-deoxy-12,14-PGJ2 (15d-PGJ2 ), in a p38- and COX-2-dependent manner. Significant concentrations of 15d-PGJ2 were reached in the medium of melanoma cells, which were sufficient to activate caspase 8 and the mitochondrial pathway of apoptosis. Inhibition of lipocalin-type PGD synthase, a key enzyme for 15d-PGJ2 synthesis, abolished the apoptotic effect of simvastatin. Moreover, 15d-PGJ2 was shown to bind to the fatty acid-binding protein 5 (FABP5), which was up-regulated and predominantly detected in the secretome of simvastatin-stressed cells. Knockdown of FABP5 abolished simvastatin-induced activation of PPAR-γ and amplified the apoptotic response.

CONCLUSIONS AND IMPLICATIONS

We characterized simvastatin-induced activation of the 15d-PGJ2 /FABP5 signalling cascades, which triggered an apoptotic burst in melanoma cells but did not affect primary human melanocytes. These data support the rationale for the pharmacological targeting of 15d-PGJ2 in metastatic melanoma.

Statins are potential anticancerous agents (review)

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), which is a rate-limiting enzyme in the mevalonate pathway. The pleiotropic effects of statins may be mediated by the inhibition of downstream products such as small GTP-binding proteins, Rho, Ras and Rac whose localization and function are dependent on isoprenylation. Preclinical studies of statins in different cancer cell lines and animal models showed antiproliferative, pro‑apoptotic and anti-invasive effects. Notably, statins showed targeted action in cancerous cell lines compared to normal cells. Previous studies have also shown the synergistic effects of statins with chemotherapeutic agents and radiotherapy. This effect of statins was also observed in chemotherapeutic-resistant tumors. Statins were reported to sensitize the cells to radiation by arresting them in the late G1 phase of the cell cycle. Similarly, population-based studies also demonstrated a chemopreventive and survival benefit of statins in various types of cancers. However, this benefit has yet to be proven in clinical trials. The inter-individual variation in response to statins may be contributed to many genetic and non-genetic factors, including single-nucleotide polymorphisms in HMGCR gene and the overexpression of heterogeneous nuclear ribonucleoprotein A1, which was reported to reduce HMGCR enzyme activity. However, more studies with large phase III randomized controlled trials in cancer patients should be conducted to establish the effect of stains in cancer prevention and treatment.

Statins and cancers

Statins (inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase) are a group of drugs used to treat lipid disorders. They inhibit cholesterol synthesis at an early stage of the biosynthesis pathway, thus eliminating numerous metabolites involved in the cycle. Numerous studies point to different possible effects of statins on cancer cells. Statins inhibit growth of a tumor, invasion and metastasis formation. They block the production of isoprenoids, which are necessary for post-translational modifications of many proteins, including those involved in normal cell signaling. They also contribute to the reduction in the expression of vascular endothelial growth factor, sensitize tumor cells to NK cell activity, and modify the body inflammatory response. Due to different pharmacokinetic properties of individual statins, they may have opposite effects on the risk of cancer. Currently, most information on the effects of statins on the risk of developing cancer is obtained from observational studies. The studies have different results depending on the location of cancer. The protective effect of statins was observed in the meta-analysis of numerous studies including prostate cancer, stomach cancer, esophagus cancer, and hepatocellular carcinoma; however, it has not yet been confirmed that statins influence the risk of developing colorectal cancer, breast cancer, or lung cancer. The protective effect of statins on the development of many kinds of cancer can be a valuable and easy way to reduce morbidity. However, further research is necessary to thoroughly determine the value of this group of drugs.

Novel prospects of statins as therapeutic agents in cancer

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

Statin use and its effect on all-cause mortality of melanoma patients: a population-based Dutch cohort study

Preclinical data showed anticancer effects of statins in melanoma, but meta-analyses could not demonstrate a reduced melanoma incidence in statin users. Rather than preventing occurrence, statins might reduce growth and metastatic spread of melanomas and ultimately improve survival. In this population-based study, we investigated the relationship between statin use and survival of melanoma patients. Patients ≥18 years who were diagnosed with cutaneous melanoma (Breslow thickness >1 mm) and registered in the Eindhoven Cancer Registry and in PHARMO Database Network between 1 January 1998 and 31 December 2010 were eligible. The hazard ratio (HR) of all-cause mortality was calculated by employing adjusted time-dependent and time-fixed Cox proportional hazard models. Disease-specific survival was estimated by means of 3-year relative survival rates (RSR). A control cohort of randomly selected patients using statins from PHARMO Database Network matched on age and gender was used to compare RSR of statin users to the general population. After melanoma diagnosis, 171 of 709 patients used statins. Use of statins showed a nonsignificantly decreased hazard of death (adjusted HR 0.76, 95% confidence interval [CI] 0.50–1.61). After stratification for gender, male but not female statin users showed a favorable outcome compared to nonusers (HR 0.57, 95% CI 0.32–0.99; HR 1.22, 95% CI 0.62–2.38, respectively). Three-year RSR for male statin users tended to be higher than for nonusers (91% vs. 80.5%, P = 0.06), no differences were observed in women (87.1% vs. 92.5%, P = 0.76). Statin use was not associated with an improved survival of melanoma patients. The trend for better survival of male in contrast to female statin users warrants further research.

Simvastatin, an HMG-CoA reductase inhibitor, exhibits anti-metastatic and anti-tumorigenic effects in endometrial cancer

OBJECTIVE

Our goal was to evaluate the effects of simvastatin on endometrial cancer cell lines and primary cultures of endometrial cancer cells.

METHODS

Cell proliferation in the ECC-1 and Ishikawa endometrial cancer cell lines and primary cultures of endometrial cancer cells was assessed by MTT assay. Apoptosis and cell cycle were detected by Annexin V assay and propidium iodide staining, respectively. Reactive oxygen species and cell adhesion were assessed using ELISA assays. Invasion was analyzed using a transwell invasion assay. Mitochondrial DNA damage was confirmed using qPCR. The effects of simvastatin on the AKT/mTOR and MAPK pathways were determined by Western blotting.

RESULTS

Simvastatin inhibited cell proliferation in a dose-dependent manner in both endometrial cancer cell lines and 5/8 primary cultures of endometrial cancer cells. Simvastatin treatment resulted in G1 cell cycle arrest, a reduction in the enzymatic activity of HMG-CoA, induction of apoptosis as well as DNA damage and cellular stress. Treatment with simvastatin resulted in inhibition of the MAPK pathway and exhibited differential effects on the AKT/mTOR pathway in the ECC-1 and Ishikawa cells. Minimal change in AKT phosphorylation was seen in both cell lines. An increase in phosphorylated S6 was seen in ECC-1 and a decrease was seen in Ishikawa. Treatment with simvastatin reduced cell adhesion and invasion (p<0.01) in both cell lines.

CONCLUSION

Simvastatin had significant anti-proliferative and anti-metastatic effects in endometrial cancer cells, possibly through modulation of the MAPK and AKT/mTOR pathways, suggesting that statins may be a promising treatment strategy for endometrial cancer.

A randomized, double-blind, placebo-controlled phase II clinical trial of lovastatin for various endpoints of melanoma pathobiology

On the basis of large cardiovascular clinical trials of lipid-lowering agents that showed a considerable decrease in the incidence of primary melanomas in the active agent arm, we have carried out a randomized, double-blind clinical trial examining the impact of lovastatin on various biomarkers of melanoma pathogenesis. Subjects with at least two clinically atypical nevi were randomized to receive oral lovastatin or placebo for a 6-month period. Clinical, histopathologic, and molecular biomarkers were evaluated for change in the two groups. Eighty subjects were randomized, evaluable, and included in the analyses. Lovastatin showed no benefit in comparison with placebo in the primary endpoint of decreasing the level of histopathologic atypia, nor in any of the secondary endpoints of decreasing clinical atypia, impact on nevus number, nor in showing significant changes in any of the molecular biomarkers. There were no significant differences in adverse event profiles for lovastatin compared with placebo. The lovastatin arm did show a significant and considerable decrease in total serum cholesterol and serum low-density lipoprotein (LDL) levels compared with placebo, an expected result. This finding bolsters confidence in subject compliance. Given the results of this trial, it is concluded that if lovastatin were to lower the incidence of melanoma, it would appear not to be doing so by reversing atypia of precursor atypical nevi over the 6-month time frame studied. Further research into the pathogenesis of melanoma and in other potential chemopreventive agents is needed.

Effective activity of cytokine-induced killer cells against autologous metastatic melanoma including cells with stemness features

PURPOSE

We investigate the unknown tumor-killing activity of cytokine-induced killer (CIK) cells against autologous metastatic melanoma and the elusive subset of putative cancer stem cells (mCSC).

EXPERIMENTAL DESIGN

We developed a preclinical autologous model using same patient-generated CIK cells and tumor targets to consider the unique biology of each patient/tumor pairing. In primary tumor cell cultures, we visualized and immunophenotypically defined a putative mCSC subset using a novel gene transfer strategy that exploited their exclusive ability to activate the promoter of stemness gene Oct4.

RESULTS

The CIK cells from 10 patients with metastatic melanoma were successfully expanded (median, 23-fold; range, 11-117). Primary tumor cell cultures established and characterized from the same patients were used as autologous targets. Patient-derived CIK cells efficiently killed autologous metastatic melanoma [up to 71% specific killing (n = 26)]. CIK cells were active in vivo against autologous melanoma, resulting in delayed tumor growth, increased necrotic areas, and lymphocyte infiltration at tumor sites. The metastatic melanoma cultures presented an average of 11.5% ± 2.5% putative mCSCs, which was assessed by Oct4 promoter activity and stemness marker expression (Oct4, ABCG2, ALDH, MITF). Expression was confirmed on mCSC target molecules recognized by CIK cells (MIC A/B; ULBPs). CIK tumor killing activity against mCSCs was intense (up to 71%, n = 4) and comparable with results reported against differentiated metastatic melanoma cells (P = 0.8).

CONCLUSIONS

For the first time, the intense killing activity of CIK cells against autologous metastatic melanoma, including mCSCs, has been shown. These findings move clinical investigation of a new immunotherapy for metastatic melanoma, including mCSCs, closer.