Combination therapy of simvastatin and 5, 6-dimethylxanthenone-4-acetic acid synergistically suppresses the aggressiveness of B16.F10 melanoma cells

Targeting of M2 macrophages with IL-13-functionalized liposomal prednisolone inhibits melanoma angiogenesis in vivo

The intricate cooperation between cancer cells and nontumor stromal cells within melanoma microenvironment (MME) enables tumor progression and metastasis. We previously demonstrated that the interplay between tumor-associated macrophages (TAMs) and melanoma cells can be disrupted by using long-circulating liposomes (LCLs) encapsulating prednisolone phosphate (PLP) (LCL-PLP) that inhibited tumor angiogenesis coordinated by TAMs. In this study, our goal was to improve LCL specificity for protumor macrophages (M2-like (i.e., TAMs) macrophages) and to induce a more precise accumulation at tumor site by loading PLP into IL-13-conjugated liposomes (IL-13-LCL-PLP), since IL-13 receptor is overexpressed in this type of macrophages. The IL-13-LCL-PLP liposomal formulation was obtained by covalent attachment of thiolated IL-13 to maleimide-functionalized LCL-PLP. C57BL/6 mice bearing B16.F10 s.c melanoma tumors were used to investigate the antitumor action of LCL-PLP and IL-13-LCL-PLP. Our results showed that IL-13-LCL-PLP formulation remained stable in biological fluids after 24h and it was preferentially taken up by M2 polarized macrophages. IL-13-LCL-PLP induced strong tumor growth inhibition compared to nonfunctionalized LCL-PLP at the same dose, by altering TAMs-mediated angiogenesis and oxidative stress, limiting resistance to apoptosis and invasive features in MME. These findings suggest IL-13-LCL-PLP might become a promising delivery platform for chemotherapeutic agents in melanoma.

Targeting Wnt/β-catenin signaling using XAV939 nanoparticles in tumor microenvironment-conditioned macrophages promote immunogenicity

The aberrant activation of Wnt/β-catenin signaling in tumor cells and immune cells in the tumor microenvironment (TME) promotes malignant transformation, metastasis, immune evasion, and resistance to cancer treatments. The increased Wnt ligand expression in TME activates β-catenin signaling in antigen (Ag)-presenting cells (APCs) and regulates anti-tumor immunity. Previously, we showed that activation of Wnt/β-catenin signaling in dendritic cells (DCs) promotes induction of regulatory T cell responses over anti-tumor CD4⁺ and CD8⁺ effector T cell responses and promotes tumor progression. In addition to DCs, tumor-associated macrophages (TAMs) also serve as APCs and regulate anti-tumor immunity. However, the role of β-catenin activation and its effect on TAM immunogenicity in TME is largely undefined. In this study, we investigated whether inhibiting β-catenin in TME-conditioned macrophages promotes immunogenicity. Using nanoparticle formulation of XAV939 (XAV-Np), a tankyrase inhibitor that promotes β-catenin degradation, we performed in vitro macrophage co-culture assays with melanoma cells (MC) or melanoma cell supernatants (MCS) to investigate the effect on macrophage immunogenicity. We show that XAV-Np-treatment of macrophages conditioned with MC or MCS significantly upregulates the cell surface expression of CD80 and CD86 and suppresses the expression of PD-L1 and CD206 compared to MC or MCS-conditioned macrophages treated with control nanoparticle (Con-Np). Further, XAV-Np-treated macrophages conditioned with MC or MCS significantly increased IL-6 and TNF-α production, with reduced IL-10 production compared to Con-Np-treated macrophages. Moreover, the co-culture of MC and XAV-Np-treated macrophages with T cells resulted in increased CD8⁺ T cell proliferation compared to Con-Np-treated macrophages. These data suggest that targeted β-catenin inhibition in TAMs represents a promising therapeutic approach to promote anti-tumor immunity.

Ectopic expression of cGAS in Salmonella typhimurium enhances STING-mediated IFN-β response in human macrophages and dendritic cells

BACKGROUND

Interferon (IFN)-β induction via activation of the stimulator of interferon genes (STING) pathway has shown promising results in tumor models. STING is activated by cyclic dinucleotides such as cyclic GMP-AMP dinucleotides with phosphodiester linkages 2'-5' and 3'-5' (cGAMPs), that are produced by cyclic GMP-AMP synthetase (cGAS). However, delivery of STING pathway agonists to the tumor site is a challenge. Bacterial vaccine strains have the ability to specifically colonize hypoxic tumor tissues and could therefore be modified to overcome this challenge. Combining high STING-mediated IFN-β levels with the immunostimulatory properties of Salmonella typhimurium could have potential to overcome the immune suppressive tumor microenvironment.

METHODS

We have engineered S. typhimurium to produce cGAMP by expression of cGAS. The ability of cGAMP to induce IFN-β and its IFN-stimulating genes was addressed in infection assays of THP-I macrophages and human primary dendritic cells (DCs). Expression of catalytically inactive cGAS is used as a control. DC maturation and cytotoxic T-cell cytokine and cytotoxicity assays were conducted to assess the potential antitumor response in vitro. Finally, by making use of different S. typhimurium type III secretion (T3S) mutants, the mode of cGAMP transport was elucidated.

RESULTS

Expression of cGAS in S. typhimurium results in a 87-fold stronger IFN-β response in THP-I macrophages. This effect was mediated by cGAMP production and is STING dependent. Interestingly, the needle-like structure of the T3S system was necessary for IFN-β induction in epithelial cells. DC activation included upregulation of maturation markers and induction of type I IFN response. Coculture of challenged DCs with cytotoxic T cells revealed an improved cGAMP-mediated IFN-γ response. In addition, coculture of cytotoxic T cells with challenged DCs led to improved immune-mediated tumor B-cell killing.

CONCLUSION

S. typhimurium can be engineered to produce cGAMPs that activate the STING pathway in vitro. Furthermore, they enhanced the cytotoxic T-cell response by improving IFN-γ release and tumor cell killing. Thus, the immune response triggered by S. typhimurium can be enhanced by ectopic cGAS expression. These data show the potential of S. typhimurium-cGAS in vitro and provides rationale for further research in vivo.

Simvastatin Enhanced Anti-tumor Effects of Bevacizumab against Lung Adenocarcinoma A549 Cells via Abating HIF-1α-Wnt/β-Catenin Signaling Pathway

BACKGROUND

Bevacizumab increased hypoxia-inducible factor (HIF-1α) expression attenuates its antitumor effect. Simvastatin can reduce the expression of HIF-1α to exert a tumor-suppressive effect in many in vitro experiments. Therefore, this study aimed to determine whether simvastatin could strengthen the anti-tumor activity of bevacizumab in lung adenocarcinoma.

OBJECTIVE

To determine whether simvastatin could strengthen the anti-tumor activity of bevacizumab in lung adenocarcinoma.

METHODS

The changes in the biological behavior of A549 cells treated with different drugs were determined through colony forming assay, Cell Counting Assay-8 (CCK-8), transwell assay, wound healing assay, and flow cytometry. The expressions of pathway-related factors HIF-1α and β-Catenin were determined via qRT-PCR and western blotting. The expressions of proliferation-related proteins, invasion-related proteins, and apoptosis-related proteins were detected by western blotting. In addition, a xenograft non-small cell lung cancer model in nude mice was used to explore in vivo tumor growth.

RESULTS

We found that simvastatin combined with bevacizumab synergistically suppressed the proliferation, migration, and invasion of A549 cells while promoting their apoptosis. As demonstrated by qRT-PCR and western blotting experiments, the bevacizumab group displayed a higher expression of pathway-related factors HIF-1α and β-Catenin than the control groups, however simvastatin group showed the opposite trend. Its combination with bevacizumab induced elevation of HIF-1α and β-catenin expressions. During in vivo experiments, simvastatin inhibited tumor growth, and in comparison, the inhibitory effects of its combination with bevacizumab were stronger.

CONCLUSION

Based on our findings, simvastatin may affect the biological responses of bevacizumab on A549 cells by restraining the HIF-1α-Wnt/β-catenin signaling pathway, thus representing a novel and effective combination therapy that can be potentially applied in a clinical therapy for lung adenocarcinoma.

Active Tumor-Targeting Nano-formulations Containing Simvastatin and Doxorubicin Inhibit Melanoma Growth and Angiogenesis

Primary melanoma aggressiveness is determined by rapid selection and growth of cellular clones resistant to conventional treatments, resulting in metastasis and recurrence. In addition, a reprogrammed tumor-immune microenvironment supports melanoma progression and response to therapy. There is an urgent need to develop selective and specific drug delivery strategies for modulating the interaction between cancer cells and immune cells within the tumor microenvironment. This study proposes a novel combination therapy consisting of sequential administration of simvastatin incorporated in IL-13-functionalized long-circulating liposomes (IL-13-LCL-SIM) and doxorubicin encapsulated into PEG-coated extracellular vesicles (PEG-EV-DOX) to selectively target both tumor-associated macrophages and melanoma cells. To this end, IL-13 was conjugated to LCL-SIM which was obtained via the lipid film hydration method. EVs enriched from melanoma cells were passively loaded with doxorubicin. The cellular uptake of rhodamine-tagged nano-particles and the antiproliferative potential of the treatments by using the ELISA BrdU-colorimetric immunoassay were investigated in vitro. Subsequently, the therapeutic agents were administered i.v in B16.F10 melanoma-bearing mice, and tumor size was monitored during treatment. The molecular mechanisms of antitumor activity were investigated using angiogenic and inflammatory protein arrays and western blot analysis of invasion (HIF-1) and apoptosis markers (Bcl-xL and Bax). Quantification of oxidative stress marker malondialdehyde (MDA) was determined by HPLC. Immunohistochemical staining of angiogenic markers CD31 and VEGF and of pan-macrophage marker F4/80 was performed to validate our findings. The in vitro data showed that IL-13-functionalized LCL were preferentially taken up by tumor-associated macrophages and indicated that sequential administration of IL-13-LCL-SIM and PEG-EV-DOX had the strongest antiproliferative effect on tumor cells co-cultured with tumor-associated macrophages (TAMs). Accordingly, strong inhibition of tumor growth in the group treated with the sequential combination therapy was reported in vivo. Our data suggested that the antitumor action of the combined treatment was exerted through strong inhibition of several pro-angiogenic factors (VEGF, bFGF, and CD31) and oxidative stress-induced upregulation of pro-apoptotic protein Bax. This novel drug delivery strategy based on combined active targeting of both cancer cells and immune cells was able to induce a potent antitumor effect by disruption of the reciprocal interactions between TAMs and melanoma cells.

Trojan horse treatment based on PEG-coated extracellular vesicles to deliver doxorubicin to melanoma in vitro and in vivo

Tailoring extracellular vesicles (EVs) as targeted drug delivery systems to enhance the therapeutic efficacy showed superior advantage over liposomal therapies. Herein, we developed a novel nanotool for targeting B16.F10 murine melanoma, based on EVs stabilized with Polyethylene glycol (PEG) and loaded with doxorubicin (DOX). Small EVs were efficiently enriched from melanoma cells cultured under metabolic stress by ultrafiltration coupled with size exclusion chromatography (UF-SEC) and characterized by size, morphology, and proteome. To reduce their clearance in vivo, EVs were PEGylated and passively loaded with DOX (PEG-EV-DOX). Our data suggested that the low PEG coverage of EVs might still favor EV surface protein interactions with target proteins from intratumor cells, ensuring their use as "Trojan horses" to deliver DOX to the tumor tissue. Moreover, our results showed a superior antitumor activity of PEG-EV-DOX in B16.F10 murine melanoma models in vivo compared to that exerted by clinically applied liposomal DOX in the same tumor model. The PEG-EV-DOX administration in vivo reduced NF-κB activation and increased BAX expression, suggesting better prognosis of EV-based therapy than liposomal DOX treatment. Collectively, our results highlight the promising potential of EVs as optimal tools for systemic delivery of DOX to solid tumors.

Remodeling tumor microenvironment by liposomal codelivery of DMXAA and simvastatin inhibits malignant melanoma progression

Anti-angiogenic therapies for melanoma have not yet been translated into meaningful clinical benefit for patients, due to the development of drug-induced resistance in cancer cells, mainly caused by hypoxia-inducible factor 1α (HIF-1α) overexpression and enhanced oxidative stress mediated by tumor-associated macrophages (TAMs). Our previous study demonstrated synergistic antitumor actions of simvastatin (SIM) and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) on an in vitro melanoma model via suppression of the aggressive phenotype of melanoma cells and inhibition of TAMs-mediated angiogenesis. Therefore, we took the advantage of long circulating liposomes (LCL) superior tumor targeting capacity to efficiently deliver SIM and DMXAA to B16.F10 melanoma in vivo, with the final aim of improving the outcome of the anti-angiogenic therapy. Thus, we assessed the effects of this novel combined tumor-targeted treatment on s.c. B16.F10 murine melanoma growth and on the production of critical markers involved in tumor development and progression. Our results showed that the combined liposomal therapy almost totally inhibited (> 90%) the growth of melanoma tumors, due to the enhancement of anti-angiogenic effects of LCL-DMXAA by LCL-SIM and simultaneous induction of a pro-apoptotic state of tumor cells in the tumor microenvironment (TME). These effects were accompanied by the partial re-education of TAMs towards an M1 phenotype and augmented by combined therapy-induced suppression of major invasion and metastasis promoters (HIF-1α, pAP-1 c-Jun, and MMPs). Thus, this novel therapy holds the potential to remodel the TME, by suppressing its most important malignant biological capabilities.

Statin as a Potential Chemotherapeutic Agent: Current Updates as a Monotherapy, Combination Therapy, and Treatment for Anti-Cancer Drug Resistance

Cancer is incurable because progressive phenotypic and genotypic changes in cancer cells lead to resistance and recurrence. This indicates the need for the development of new drugs or alternative therapeutic strategies. The impediments associated with new drug discovery have necessitated drug repurposing (i.e., the use of old drugs for new therapeutic indications), which is an economical, safe, and efficacious approach as it is emerged from clinical drug development or may even be marketed with a well-established safety profile and optimal dosing. Statins are inhibitors of HMG-CoA reductase in cholesterol biosynthesis and are used in the treatment of hypercholesterolemia, atherosclerosis, and obesity. As cholesterol is linked to the initiation and progression of cancer, statins have been extensively used in cancer therapy with a concept of drug repurposing. Many studies including in vitro and in vivo have shown that statin has been used as monotherapy to inhibit cancer cell proliferation and induce apoptosis. Moreover, it has been used as a combination therapy to mediate synergistic action to overcome anti-cancer drug resistance as well. In this review, the recent explorations are done in vitro, in vivo, and clinical trials to address the action of statin either single or in combination with anti-cancer drugs to improve the chemotherapy of the cancers were discussed. Here, we discussed the emergence of statin as a lipid-lowering drug; its use to inhibit cancer cell proliferation and induction of apoptosis as a monotherapy; and its use in combination with anti-cancer drugs for its synergistic action to overcome anti-cancer drug resistance. Furthermore, we discuss the clinical trials of statins and the current possibilities and limitations of preclinical and clinical investigations.

Immune Regulation of the cGAS-STING Signaling Pathway in the Tumor Microenvironment and Its Clinical Application

As a DNA receptor in the cytoplasm, cyclic GMP-AMP synthase (cGAS) contributes to the recognition of abnormal DNA in the cytoplasm and contributes to the stimulator of interferon genes (STING) signaling pathway. cGAS could mediate the expression of interferon-related genes, inflammatory-related factors, and downstream chemokines, thus initiating the immune response. The STING protein is a key effector downstream of the DNA receptor pathway. It is widely expressed across cell types such as immune cells, tumor cells, and stromal cells and plays a role in signal transduction for cytoplasmic DNA sensing and immunity. STING agonists, as novel agonists, are used in preclinical research and in the treatment of various tumors via clinical trials and have displayed attractive application prospects. Studying the cGAS-STING signaling pathway will deepen our understanding of tumor immunity and provide a basis for the research and development of antitumor drugs.

Attempts to use statins in cancer therapy: An update

Although it could be speculated that almost everything has been said concerning the use of statins in cancer therapy, statins as anticancer drugs have both committed supporters and opponents, for whom the dispute about the legitimacy of statin use in cancer treatment seems never to be clearly resolved; every year more than 300 reports which deepen the knowledge about statins and their influence on cancer cells are published. In this mini-review, we focus on the latest (since 2015) outcomes of cohort studies and meta-analyses indicating statin effectiveness in cancer treatment. We discuss attempts to improve the bioavailability of statins using nanocarriers and review the effectiveness of statins in combined therapies. We also summarise the latest results regarding the development of mechanisms of resistance to statins by cancer cells and, on the other hand, give a few examples where statins could potentially be used to overcome resistance to commonly used chemotherapeutics. Finally, special attention is paid to new reports on the effect of statins on epithelial-mesenchymal transition.

Overcoming Intrinsic Doxorubicin Resistance in Melanoma by Anti-Angiogenic and Anti-Metastatic Effects of Liposomal Prednisolone Phosphate on Tumor Microenvironment

Regardless of recent progress, melanoma is very difficult to treat, mainly due to the drug resistance modulated by tumor cells as well as by the tumor microenvironment (TME). Among the immune cells recruited at the tumor site, tumor associated macrophages (TAMs) are the most abundant, promoting important tumorigenic processes: angiogenesis, inflammation and invasiveness. Furthermore, it has been shown that TAMs are involved in mediating the drug resistance of melanoma cells. Thus, in the present study, we used liposomal formulation of prednisolone disodium phosphate (LCL-PLP) to inhibit the protumor function of TAMs with the aim to sensitize the melanoma cells to the cytotoxic drug doxorubicin (DOX) to which human melanoma has intrinsic resistance. Consequently, we evaluated the in vivo effects of the concomitant administration of LCL-PLP and liposomal formulation of DOX (LCL-DOX) on B16.F10 melanoma growth and on the production of key molecular markers for tumor development. Our results demonstrated that the concomitant administration of LCL-PLP and LCL-DOX induced a strong inhibition of tumor growth, primarily by inhibiting TAMs-mediated angiogenesis as well as the tumor production of MMP-2 and AP-1. Moreover, our data suggested that the combined therapy also affected TME as the number of infiltrated macrophages in melanoma microenvironment was reduced significantly.

Co-Administration of Vadimezan and Recombinant Coagulase-NGR Inhibits Growth of Melanoma Tumor in Mice

Purpose: Tumor vascular targeting appeared as an appealing approach to fight cancer, though, the results from the clinical trials and drugs in the market were proved otherwise. The promise of anti-angiogenic therapy as the leading tumor vascular targeting strategy was negatively affected with the discovery that tumor vascularization can occur non-angiogenic mechanisms such as co-option. An additional strategy is induction of tumor vascular infarction and ischemia. Methods: Such that we used truncated coagulase (tCoa) coupled to tumor endothelial targeting moieties to produce tCoa-NGR fusion proteins. We showed that tCoa-NGR can bypass coagulation cascade to induce selective vascular thrombosis and infarction of mild and highly proliferative solid tumors in mice. Moreover, combination therapy can be used to improve the potential of cancer vascular targeting modalities. Herein, we report combination of tCoa-NGR with vascular disrupting agent (VDA), vadimezan. Results: Our results show that synergistic work of these two agents can significantly suppress growth of B16-F10 melanoma tumors in C57/BL6 mice. Conclusion: For the first time, we used the simultaneous benefits of two strategies for inducing thrombosis and destruction of tumor vasculature as spatial co-operation. The tCoa-NGR induce thrombosis which reduces blood flow in the peripheral tumor region. And combined with the action of DMXAA, which target inner tumor mass, growth and proliferation of melanoma tumors can be significantly suppressed.

Comparative Phytochemical Profile, Antioxidant, Antimicrobial and In Vivo Anti-Inflammatory Activity of Different Extracts of Traditionally Used Romanian Ajuga genevensis L. and A. reptans L. (Lamiaceae)

Several Ajuga species are used in Romanian folk medicine for their antioxidant, antimicrobial and anti-inflammatory properties, to treat pain, fever or arthritis. Still, the active compounds responsible for these effects and their mechanism of action are scarcely known. This research was designed to investigate the phytochemical profile (e.g. iridoids, polyphenolic compounds, phytosterols), as well as the biological potential (antioxidant, antibacterial, antifungal, anti-inflammatory properties) of two selected Ajuga species collected from different regions of Romanian spontaneous flora. The main compounds identified in A. reptans aerial parts extracts were 8-O-acetylharpagide, isoquercitrin and β-sitosterol, whilst in A. genevensis were 8-O-acetylharpagide, luteolin and campesterol. The extracts were screened for their antioxidant potential using different methods (DPPH, TEAC, EPR) and the results showed a good activity, in accordance with the polyphenol content (18-26 mg GAE/g dw). The antifungal activity on the tested strains was good. The determination of few parameters linked with the inflammatory mechanism allowed the assessment of in vivo anti-inflammatory potential. Ajuga reptans and A. genevensis ethanol extracts had anti-inflammatory activity through lowering the oxidative stress, phagocytosis, PMN and total leukocytes. The best anti-oxidative and anti-inflammatory activity was observed for the Ajuga reptans 100 mg dw/mL extract when compared with diclofenac, thus the dose could be correlated with the pharmacological effect. These findings provide substantial evidence that both selected Ajuga species have the potential to be valued as sources of phytochemicals in effective anti-inflammatory herbal preparations.

Biologically Active Ajuga Species Extracts Modulate Supportive Processes for Cancer Cell Development

Backround:Ajuga species have been used in traditional medicine for their diuretic, anti-inflammatory, wound-healing, and hepatoprotective properties.

Purpose: The phytochemical profile and anticancer potential of three Ajuga sp. (A. genevensis, A. chamaepitys, and A. laxmannii) from Romania was investigated.

Materials and Methods: The phytochemicals were extracted from the aerial parts of Ajuga sp. by using different solvents and methods. The hydroalcoholic extracts were examined for total phenolic, flavonoid and iridoid contents, and HPLC/MS was used to analyze the polyphenolic compounds and iridoids. The phytochemical profile was also evaluated by principal component analysis in connection with antitumor efficacy of extracts. The antiproliferative potential was evaluated using the ELISA BrdU-colorimetric immunoassay. Western Blot with regard to inflammatory protein NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) p65 subunit expression in cell lysates was performed. Quantification of oxidative stress marker malondialdehyde (MDA) was determined by high-performance liquid chromatography (HPLC). Enzymatic and non-enzymatic antioxidant capability was assessed by measuring catalase activity and by evaluating the total antioxidant capacity (TAC) of treated cells.

Results:Ajuga laxmannii ethanol extract showed the highest total phenolic and flavonoid content, while A. genevensis ethanol extract was more abundant in iridoids. The overall cytostatic effect of the investigated plant extracts was exerted through strong inhibitory actions on NF-κB, the key molecule involved in the inflammatory response and via oxidative stress modulatory effects in both murine colon carcinoma and melanoma cell lines.

Conclusion:Ajuga laxmannii showed the most significant antitumor activity and represents an important source of bioactive compounds, possibly an additional form of treatment alongside conventional anticancer drugs.