Experimental Lung Metastasis Model Research Articles

ICOS-expressing Regulatory T Cells Influence the Composition of Antitumor CTL Populations.

The role of ICOS in antitumor T cell responses and overall tumor progression has been controversial. In this study, we compared tumor progression in mice lacking ICOS selectively in regulatory T (Treg) cells or in all T cells. Using an experimental melanoma lung metastasis model, we found that Treg cell-specific ICOS knockout reduces the overall tumor burden compared with Cre control mice, with increased CD4+-to-Treg cell and CD8+-to-Treg cell ratios in the tumor. In contrast, there was no difference in the tumor burden in mice lacking ICOS in all of the T cell compartments. This suggests a dual role of ICOS costimulation in promoting protumor and antitumor T cell responses. Consistent with reduced tumor burden, we found that Treg cell-specific deletion of ICOS leads to an increase of CD8+ CTLs that express high levels of granzyme B and perforin. Moreover, single-cell transcriptome analysis revealed an increase of Ly108+Eomeshi CD8+ T cells at the cost of the Ly108+T-bethi subset in Treg cell-specific knockout mice. These results suggest that ICOS-expressing Treg cells suppress the CTL maturation process at the level of Eomes upregulation, a critical step known to drive perforin expression and cytotoxicity. Collectively, our data imply that cancer immunotherapies using ICOS agonist Abs may work better in Treg cell-low tumors or when they are combined with regimens that deplete tumor-infiltrating Treg cells.

Neutrophil-targeted liposomal platform: A shift in novel approach for early detection and treatment of cancer metastasis

Tumor metastasis is responsible for 90 % of cancer-associated deaths, and its early detection may decrease the likelihood of mortality. Studies have demonstrated that metastasis results from the interaction between “seeds” (tumor cells) and “soil” (pre-metastatic niche, PMN). As the first and most abundant immune cells to be recruited to PMN, neutrophils play a key role in the ultimate formation of metastatic foci through mechanisms such as supporting tumor cell growth, promoting angiogenesis, and shaping an immune-suppressive microenvironment. In this study, two distinct types of sialic acid (SA)-modified liposomes were prepared to target and regulate pro-metastatic neutrophils through the l-selectin receptor. One of these liposomes, named ICG@SAL, was used to encapsulate indocyanine green (ICG) and was specifically designed for the early detection of cancer metastasis. The other liposome, referred to as ABE/Cur@SAL, co-loaded abemaciclib (ABE) and curcumin (Cur), with the intention of suppressing the progression of metastatic tumor. Fluorescence imaging results from the mouse spontaneous metastasis model indicated that ICG@SAL demonstrated faster targeting and stronger accumulation in the metastatic organs than unmodified ICG liposomes (ICG@CL). This suggested that ICG@SAL could detect tumor metastasis at an early stage. The therapy with co-loaded liposomes in the mouse experimental lung metastasis model indicated that ABE/Cur@SAL could inhibit regulatory T (Treg) cell proliferation, enhance effector T cell activity and reduce tumorigenic factor release, implying that ABE/Cur@SAL could inhibit tumor metastasis. Overall, our work provided a sensitive and convenient approach to early diagnosis and treatment of tumor metastasis. ICG@SAL could be employed for the early detection of tumor metastasis, while ABE/Cur@SAL could be used to inhibit the development of tumor metastasis when early metastasis was identified.

Antiplatelet drug ticagrelor suppresses triple negative breast cancer metastasis by targeting PI3K

Metastatic recurrence is still a major challenge in breast cancer treatment. Patients with triple negative breast cancer (TNBC) develop early recurrence and relapse more frequently. Due to the lack of specific therapeutic targets, new targeted therapies for TNBC are urgently needed. Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway is one of the active pathways involved in chemoresistance and survival of TNBC, being considered as a potential target for TNBC treatment. Our present study identified ticagrelor, an anti-platelet drug, as a pan-PI3K inhibitor with potent inhibitory activity against four isoforms of class I PI3K. At doses normally used in clinic, ticagrelor showed weak cytotoxicity against a panel of breast cancer cells, but significantly inhibited the migration, invasion and the actin cytoskeleton organization of human TNBC MDA-MB-231 and SUM-159PT cells. Mechanistically, ticagrelor effectively inhibited PI3K downstream mTOR complex 1 (mTORC1) and mTORC2 signaling by targeting PI3K and decreased the protein expression of epithelial-mesenchymal transition (EMT) markers. In vivo, ticagrelor significantly suppressed tumor cells lung metastasis in 4T1 tumor bearing BALB/c mice model and experimental lung metastasis model which was established by tail vein injection of GFP-labeled MDA-MB-231 cells. The above data demonstrated that ticagrelor can inhibit the migration and invasion of TNBC both in vitro and in vivo by targeting PI3K, suggesting that ticagrelor, a pan-PI3K inhibitor, might represent a promising therapeutic agent for the treatment of metastatic TNBC.

Pharmacological Inhibition or Silencing of TREM1 Restrains HCC Cell Metastasis by Inactivating TLR/PI3K/AKT Signaling.

Hepatocellular carcinoma (HCC), a widely prevalent malignancy strongly linked to inflammation, remains a significant public health concern. Triggering receptor expressed on myeloid cells 1 (TREM1), a modulator of inflammatory responses identified in recent years, has emerged as a crucial facilitator in cancer progression. Despite its significance, the precise regulatory mechanism of TREM1 in HCC metastasis remains unanswered. In the present investigation, we observed aberrant upregulation of TREM1 in HCC tissues, which was significantly linked to poorer overall survival. Inhibition of TREM1 expression resulted in a significant reduction in HCC Huh-7 and MHCC-97H cell proliferation, invasion, and epithelial-mesenchymal transition (EMT) process. Furthermore, inhibiting TREM1 decreased protein expressions of toll-like receptor 2/4 (TLR2/4) and major myeloid differentiation response gene 88 (MyD88), leading to the inactivation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) in HCC cells. Notably, these effects were reversed by treatment with TLR2-specific agonist (CU-T12-9), indicating a potential crosstalk between TREM1 and TLR2/4. Mechanistic studies revealed a direct interaction between TREM1 and both TLR2 and TLR4. In vivo studies demonstrated that inhibition of TREM1 suppressed the growth of HCC cells in the orthotopic implant model and its metastatic potential in the experimental lung metastasis model. Overall, our findings underscore the role of TREM1 inhibition in regulating EMT and metastasis of HCC cells by inactivating the TLR/PI3K/AKT signaling pathway, thereby providing deeper mechanistic insights into how TREM1 regulates metastasis during HCC progression.

Resveratrol-derived inhibitors of the E3 ubiquitin ligase PELI1 inhibit the metastasis of triple-negative breast cancer

Triple-negative breast cancer (TNBC), as the most challenging subtype of breast cancer, exerts highly invasive ability and metastatic nature to the lymph nodes, which is correlated with poor survival rates among patients. Pellino-1 (PELI1) is an E3 ubiquitin ligase involved in tumor invasion and metastasis, and has the potential to be developed as a novel therapeutic target for TNBC. In this study, we identified a potent inhibitor of PELI1, namely compound 3d, on the basis of natural stilbene framework through medicinal chemistry approaches. This novel PELI1 inhibitor 3d showed potent binding affinity to PELI1 (Kd 8.2 μM) in fluorescence quenching assay, and markedly interrupted the interaction of PELI1 and SNAIL/SLUG confirmed by co-immunoprecipitation. Moreover, 3d exhibited potent antitumor activity in inhibiting tumor cell migration in scratch wound healing assay without affecting cell proliferation in vitro, and down-regulated the downstream EMT-effectors of PELI1 as assessed by western blotting. In the experimental lung metastasis model, 3d showed anti-TNBC metastasis efficacy without observable toxicity in vivo.

Vascular endothelial-derived Von Willebrand factor inhibits lung cancer progression through the αvβ3/ERK1/2 axis

Lung cancer remains a common malignant tumor causing death due to the rapid industrialization and serious pollution of the environment. The Von Willebrand Factor (vWF) protein is an endothelial marker and is widely used to diagnose cancer and other inflammations, however its exact mechanism of action remains largely unexplored. In particular, how it plays two opposing roles in tumor development is not clear. Our study aimed to the impact of endothelial-derived vWF on tumor development by co-culturing human umbilical vein endothelial cells (HUVECs) with lung cancer cells (95D and A549). A knockdown of endothelial-derived vWF assisted lung cancer cell in proliferation, migration and inhibited apoptosis in vitro, while overexpression of endothelial-derived vWF inhibited the proliferation, migration and induced apoptosis of lung cancer cells. The results of further experiments indicated that the vWF secreted by endothelial cells could affect lung cancer cell migration and apoptosis via its binding to integrin αvβ3 on the surface of lung cancer cells. Furthermore, a novel finding was the fact that endothelial-derived vWF inhibited lung cancer cell apoptosis by phosphorylating ERK1/2. At the same time, we established experimental lung metastasis model and xenograft model in normal mice and vWF−/− mice, and found that knockout of vWF in mice significantly promoted lung cancer growth and metastasis. In conclusion, our research found that endothelial-derived vWF could directly combine to αvβ3 on the exterior of A549 and 95D, thereby mediating lung cancer proliferation, migration and apoptosis and inhibiting the development of lung cancer.

Abstract 3256: Entinostat enhances the efficacy of checkpoint inhibition in breast-to-lung metastases and is associated with alterations in the phenotype and function of myeloid cell populations

Abstract Single agent immune checkpoint inhibitors (ICIs) are ineffective against metastatic breast cancer. One mechanism of intrinsic resistance is the presence of immunosuppressive myeloid cells and dysfunctional dendritic cells in the metastatic tumor microenvironment (TME) that impede the activation of anti-tumor T cells. A comparison of single-cell RNA sequencing analyses between breast-to-lung metastases and published data from breast tumors in the syngeneic NeuN mouse model of HER2+ breast cancer revealed that despite the presence of additional immune cell populations in the lungs, myeloid cells represented the predominant immune cell population in both TMEs and demonstrated similar changes in frequency and gene expression following treatment with the histone deacetylase inhibitor, entinostat. Our work highlights for the first time an increase in the frequency of conventional dendritic cells (cDC) with entinostat treatment in breast-to-lung metastases. Gene expression analyses of breast-to-lung metastases showed that entinostat-treated myeloid derived suppressor cells (MDSCs) and tumor associated macrophages (TAMs) downregulated genes associated with immunosuppression such as S100a8, Cd84, Trem2, and Mmp9. In addition, TAMs and cDCs upregulated the expression of genes associated with antigen presentation such as H2-K1, H2-Ab1, B2m, and Cd74 and pro-inflammatory markers such as Ccl3. NeuN mice were treated with the combination of entinostat and the immune checkpoint inhibitors, anti-PD-1 and anti-CTLA-4, and breast-to-lung metastases were analyzed via flow cytometry, demonstrating an increase in the frequency of cDC1s and CD8+ T cells expressing granzyme B. Furthermore, the treatment combination of entinostat + anti-PD-1 + anti-CTLA-4 significantly increased survival in an experimental model of lung metastasis using a newly characterized model derived from the original NT2.5 HER2+ cell line, NT2.5LM. These results confirm those of our breast expansion cohort from the phase I clinical trial NCI-9844 that demonstrate a 30% overall response rate in 20 heavily pretreated patients with metastatic disease treated with entinostat + Nivolumab (anti-PD-1) + Ipilimumab (anti-CTLA-4). We highlight for the first time significant alterations within multiple myeloid derived cell types, cDCs, TAMs and MDSCs, from within a native metastatic niche, that are likely driving an entinostat mediated improved response to ICI treatment. Citation Format: Edgar Gonzalez, Adam L. MacLean, Evanthia T. Roussos Torres, Aaron Baugh, Jesse Kreger, Sofi Castanon, Valerie Narumi, Elizabeth M. Jaffee. Entinostat enhances the efficacy of checkpoint inhibition in breast-to-lung metastases and is associated with alterations in the phenotype and function of myeloid cell populations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3256.

Murine regulatory T cells utilize granzyme B to promote tumor metastasis.

Regulatory T cells (Tregs) possess a wide range of mechanisms for immune suppression. Among them, Granzyme B (GzmB) and perforin expressed by Tregs were shown to inhibit tumor clearance in previous reports, which contradicted the canonical roles of these cytotoxic molecules expressed by cytotoxic T cells and NK cells in antitumor immune responses. Given the ability of the tumor to manipulate the microenvironment, Treg-derived GzmB function may represent an important approach to aid in tumor growth as well as facilitating tumor metastasis. In this study, we utilized Treg-specific GzmB knockout (Foxp3creGzmBfl/fl) mice to test whether Treg-derived GzmB can aid in tumor progression and metastasis. Using an IL-2 complex to activate GzmB expression in the non-immunogenic B16-F10 tumor model, we provide evidence to show that GzmB produced by Tregs is important for spontaneous metastasis to the lungs. In addition, we depleted CD8 + T cells to selectively measure the impact of Treg-derived GzmB in an experimental lung metastasis model by intravenous injection of B16-F10 tumor cells; our results demonstrate that Treg-derived GzmB plays an important role in increasing the metastatic burden to the lungs.

Self-Assembled Core-Shell Nanoscale Coordination Polymer Nanoparticles Carrying a Sialyltransferase Inhibitor for Cancer Metastasis Inhibition.

Despite hypersialylation of cancer cells together with a significant upregulation of sialyltransferase (ST) activity contributes to the metastatic cascade at multiple levels, there are few dedicated tools to interfere with their expression. Although transition state-based ST inhibitors are well-established, they are not membrane permeable. To tackle this problem, herein, we design and construct long-circulating, self-assembled core-shell nanoscale coordination polymer (NCP) nanoparticles carrying a transition state-based ST inhibitor, which make the inhibitor transmembrane and potently strip diverse sialoglycans from various cancer cells. In the experimental lung metastasis and metastasis prevention models, the nanoparticle device (NCP/STI) significantly inhibits metastases formation without systemic toxicity. This strategy enables ST inhibitors to be applied to cells and animals by providing them with a well-designed nanodelivery system. Our work opens a new avenue to the development of transition state-based ST inhibitors and demonstrates that NCP/STI holds great promise in achieving metastases inhibition for multiple cancers.

Fructose utilization enhanced by GLUT5 promotes lung cancer cell migration via activating glycolysis/AKT pathway.

Lung cancer is the leading cause of cancer-related mortalities worldwide, and metastasis contributes to a large number of deaths in lung carcinoma patients. New approaches for anti-metastatic treatment are urgently needed. Enhanced fructose metabolism mediated by GLUT5 directly contributes to cancer metastasis. However, the underlying mechanism remains to be elucidated, which we aimed to explore in this study. The overexpression and knockdown of SLC2A5, the encoding gene of GLUT5, were established by retrovirus system and CRISPR/Cas9 technology, respectively. Cell migration was conducted by trans-well assay. Western blotting assay was carried out to detect the expression of GLUT5, total AKT, phosphorylated AKT (pAKT-S473 and pAKT-T308) and LDHA. Lactate production was measured by colorimetric assay. Experimental lung metastasis model by tail vein injection was constructed to evaluate the metastatic potential of GLUT5 in vivo. Overexpression of SLC2A5 promoted migration of lung cancer cells both in vitro and in vivo, and shortened the overall survival of mice. While, SLC2A5 deletion blocked the migration of lung cancer cells. GLUT5-mediated fructose utilization upregulated phosphorylated AKT, which was responsible for enhanced migration of lung cancer cells. Additionally, GLUT5-mediated fructose utilization boosted glycolysis with overproduction of lactate, resulting in upregulation of phosphorylated AKT. Moreover, lung cancer cell migration and AKT activation were restrained by glycolysis inhibitor 2-deoxy-D-glucose (2-DG) or GLUT5-specific inhibitor 2,5-anhydro-D-mannitol (2,5-AM). Our study unveils glycolysis/lactate/AKT pathway is responsible for lung cancer cell migration induced by GLUT5-mediated fructose metabolism, providing a potential therapeutic avenue for lung cancer metastasis.

Cabozantinib-Loaded PLGA Nanoparticles: A Potential Adjuvant Strategy for Surgically Resected High-Risk Non-Metastatic Renal Cell Carcinoma.

Patients with high-risk non-metastatic renal cell carcinoma (RCC) are at risk of metastatic relapse following nephrectomy. Cabozantinib (CZ), a potent multitarget tyrosine kinase inhibitor, interferes with angiogenesis and immunosuppression associated with surgery-induced metastasis. Here, we explored the therapeutic potential of CZ-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (CZ-PLGA-NPs) as an adjuvant strategy for targeting post-nephrectomy metastasis. A clinically relevant subline recapitulating post-nephrectomy lung metastasis of high-risk human RCC, namely Renca-SRLu5-Luc, was established through in vivo serial selection of luciferase-expressing murine RCC Renca-Luc cells. CZ was encapsulated into PLGA-NPs via the conventional single emulsion technique. The multifaceted preclinical antimetastatic efficacy of CZ-PLGA-NPs was assessed in Renca-SRLu5-Luc cells. CZ-PLGA-NPs with a smooth surface displayed desirable physicochemical properties, good CZ encapsulation efficiency, as well as controlled and sustained CZ release. CZ-PLGA-NPs exhibited remarkable dose-dependent toxicity against Renca-SRLu5-Luc cells by inducing G2/M cell cycle arrest and apoptosis. CZ-PLGA-NPs attenuated in vitro colony formation, migration, and invasion by abrogating AKT and ERK1/2 activation. An intravenous injection of CZ-PLGA-NPs markedly reduced lung metastatic burden and prolonged lifespan with favorable safety in the Renca-SRLu5-Luc experimental lung metastasis model. The novel CZ-PLGA-NPs system with multifaceted antimetastatic effects and alleviating off-target toxicity potential is a promising adjunctive agent for patients with surgically resected high-risk RCC.

Abstract 4048: New approach to target metastatic colorectal cancer organotropism with L-Annamycin

Abstract Colorectal cancer (CRC) is a frequently occurring disease and the second most common cause of cancer deaths when men and women are combined. CRC metastasis is strongly associated with mortality. The liver and lungs are the most frequent sites of distant disease, accounting for ~70% and ~12% of cases, respectively. We hypothesize that anticancer agents that mimic the organotropism of metastatic CRC will be highly effective in treating CRC patients. Our studies have identified that Annamycin (ANN), a potent topoisomerase II poison that displays organotropism imitating that of metastatic CRC. ANN is an analog of doxorubicin (Dox) that shows unique properties. Notably, ANN is active against multidrug-resistant tumors and undergoes efficient uptake by lungs and liver. ANN is easily formulated in multilamellar liposomes (L-ANN), which further increases ANN levels in lungs and liver. Objective. The objective of this study was to assess the efficacy of L-ANN in experimental CRC liver and lung metastasis models. Methods. The efficacy of L-ANN was tested in syngeneic models of metastatic CRC established in lungs or liver. For lung metastasis model, CT26-Luc cells were injected intravenously (IV) into Balb/c mice, followed by weekly IV treatment of L-ANN (4 and 6 mg/kg). The liver metastatic model was established using intrasplenic injection protocol. Mice received six weekly IV injections of 4 mg/kg of L-ANN or vehicle. Bioluminescent imaging (BLI), Magnetic Resonance Imaging (MRI) or Computer Tomography (CT) were used to track tumor progression. Results. L-ANN exhibited robust antitumor activity in both models. In the lung metastasis model, a dose-dependent delay in the tumor progression was visualized by both BLI and CT scan in the L-ANN treated group. The delay correlated with 272% extension of survival in the group receiving 6 mg/kg L-ANN [median survival (MS) 79d for treated vs 29d vehicle, p<0.0001] and 234% for the animals dosed with L-ANN at 4 mg/kg [MS 68d, p=0.0012]. In the liver metastasis model, all vehicle-treated mice showed massive tumors in the liver and peritoneal cavity as monitored by BLI and MRI. In the vehicle group, 13/14 died or were euthanized by 35d (median survival was 34.5d). Yet, no tumors were detected by BLI or MRI in L-ANN treated mice as of 44d and 0/14 mice died (100% survival). This indicates a highly significant (P< 0.0001) extension of survival (ongoing experiment). Conclusion. In summary, the strategy to develop anticancer agents that imitate metastatic CRC organotropism appears to be highly promising and is supported by these results. Our previous in vivo studies of L-ANN in sarcoma lung metastasis models already led to initiation of multicenter clinical studies (NCT04887298). This study demonstrating L-ANN efficacy in CRC models provides convincing evidence for further preclinical development aimed at initiation of clinical studies in CRC metastatic patients. Citation Format: Rafal J. Zielinski, Krzysztof Grela Grela, Roberto Cardenas-Zuniga, Stanislaw Skora, Izabela Fokt, Edward Felix, Damian Grybowski, Waldemar Priebe. New approach to target metastatic colorectal cancer organotropism with L-Annamycin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4048.

Imprime PGG Enhances Anti-Tumor Effects of Tumor-Targeting, Anti-Angiogenic, and Immune Checkpoint Inhibitor Antibodies

Imprime PGG (Imprime) is in late-stage clinical development as a combinatorial agent with several therapeutic modalities. Here we present pre-clinical mechanistic data supportive of Imprime, a soluble yeast β-1,3/1,6-glucan pathogen-associated molecular pattern able to prime innate immune cells in a Dectin-1dependent manner. In tumor-free mice, Imprime evoked broad innate immune responses (type I interferon signature, mobilization of myeloid cells, dendritic cell and monocyte/macrophage expression of co-stimulatory ligands like CD86, and activation of natural killer cells). Imprime-mediated activation of myeloid cells also resulted in functional priming of antigen-specific CD8 T cell response. In tumor-bearing mice, Imprime monotherapy further resulted in activation of systemic and tumor infiltrating macrophages and enhanced cytotoxic CD8 T cell trafficking. Imprime enhanced the anti-tumor activity of several combinatorial agents in mouse cancer models; anti-tyrosinase-related protein 1 antibody in B16F10 melanoma experimental lung metastasis model, anti-vascular endothelial growth factor receptor 2 antibody in H1299 and H441 lung cancer, and anti-programmed cell death protein 1 antibody in MC38 colon cancer models. Mechanistically, combining Imprime with these combinatorial therapeutic agents elicited enhanced innate immune activation, supporting immunological synergy. Finally, Imprime treatment induced similar in vitro phenotypic and functional activation of human innate immune cells. Collectively, these data demonstrate Imprime’s potential to orchestrate a broad, yet coordinated, anti-cancer immune response and complement existing cancer immunotherapies.

Immunization with short peptide particles reveals a functional CD8+ T-cell neoepitope in a murine renal carcinoma model

BackgroundInduction of CD8+ T cells that recognize immunogenic, mutated protein fragments in the context of major histocompatibility class I (MHC-I) is a pressing challenge for cancer vaccine development.MethodsUsing the commonly...

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Upregulated osteoprotegerin expression promotes lung cancer cell invasion by increasing miR-20a expression.

Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily and a major regulatory factor in osteoclast development. OPG has been previously associated with the malignant behavior of various types of cancer, particularly that of cancer metastasis. However, information on the link between the expression profile of OPG and lung cancer metastasis remained elusive. In the present study, the expression levels of OPG in the serum samples of patients with non-small cell lung cancer (NSCLC) was measured using ELISA. The expression of miRNAs was assessed using reverse transcription-quantitative PCR. A549 or H3122 cell invasion was assessed using Transwell invasion assays. The effect of OPG on the invasiveness of lung cancer cells was evaluated using an experimental mouse lung metastasis model. OPG expression was found to be upregulated in the serum of patients with NSCLC compared with that in healthy individuals. The serum levels of OPG in patients with distant metastasis were observably higher compared with those in patients without metastasis. Functionally, overexpression of OPG in NSCLC cells markedly promoted cell invasion. Mechanistically, increased expression of OPG resulted in upregulation of microRNA (miR)-20a in NSCLC cells. Furthermore, miR-20a promoted NSCLC cell invasion, whilst miR-20a inhibition partially abrogated the effect of OPG on NSCLC cell invasion. Taken together, the present results demonstrated that the OPG/miR-20a axis serve an important role in lung cancer metastasis, which potentially provide an additional novel target for lung cancer treatment.

ASK1 suppresses NK cell-mediated intravascular tumor cell clearance in lung metastasis.

Tumor metastasis is the leading cause of death worldwide and involves an extremely complex process composed of multiple steps. Our previous study demonstrated that apoptosis signal‐regulating kinase 1 (ASK1) deficiency in mice attenuates tumor metastasis in an experimental lung metastasis model. However, the steps of tumor metastasis regulated by ASK1 remain unclear. Here, we showed that ASK1 deficiency in mice promotes natural killer (NK) cell‐mediated intravascular tumor cell clearance in the initial hours of metastasis. In response to tumor inoculation, ASK1 deficiency upregulated immune response‐related genes, including interferon‐gamma (IFNγ). We also revealed that NK cells are required for these anti‐metastatic phenotypes. ASK1 deficiency augmented cytokine production chemoattractive to NK cells possibly through induction of the ligand for NKG2D, a key activating receptor of NK cells, leading to further recruitment of NK cells into the lung. These results indicate that ASK1 negatively regulates NK cell‐dependent anti‐tumor immunity and that ASK1‐targeted therapy can provide a new tool for cancer immunotherapy to overcome tumor metastasis.

Amiodarone's major metabolite, desethylamiodarone inhibits proliferation of B16-F10 melanoma cells and limits lung metastasis formation in an in vivo experimental model.

Previously, we demonstrated the in vitro anti-tumor effects of desethylamiodarone (DEA) in bladder and cervix cancer cell lines. In the present study, we intended to establish its potentiality in B16-F10 metastatic melanoma cells in vitro and in vivo. We assessed cell proliferation, apoptosis and cell cycle by using sulforhodamine B assay, Muse™ Annexin V & Dead Cell and Muse® Cell Cycle assays, respectively. We determined colony formation after crystal violet staining. For studying mechanistic aspects, immunoblotting analysis was performed. We used a C57BL/6 experimental lung metastasis model for demonstrating in vivo anti-metastatic potential of DEA. DEA inhibited in vitro proliferation and colony formation, and in vivo lung metastasizing properties of B16-F10 cells. It arrested the cells in G0/G1 phase of their cycle likely via p21 in a p53-dependent fashion, and induced caspase mediated apoptosis likely via inversely regulating Bcl-2 and Bax levels, and reducing Akt and ERK1/2 activation. In this study, we provided in vitro and in vivo experimental evidences for DEA’s potentiality in the therapy of metastatic melanomas. Since DEA is the major metabolite of amiodarone, a worldwide used antiarrhythmic drug, safety concerns could be resolved more easily for it than for a novel pharmacological agent.

Antimetastatic effects of thalidomide by inducing the functional maturation of peripheral natural killer cells.

Thalidomide and its analogues are known as immunomodulatory drugs (IMiDs) that possess direct antimyeloma effects, in addition to other secondary effects, including antiangiogenic, antiinflammatory, and immunomodulatory effects. Although the involvement of natural killer (NK) cells in the antitumor effects of IMiDs has been reported, it is unclear whether IMiDs inhibit cancer cell metastasis by regulating the antitumor function of NK cells. In this study, we examined the protective effects of thalidomide against cancer metastasis by focusing on its immunomodulatory effects through NK cells. Using experimental lung metastasis models, we found that pharmacological effects of thalidomide on host cells, but not its direct anticancer tumor effects, are responsible for the inhibition of lung metastases. To exert the antimetastatic effects of thalidomide, both γ‐interferon (IFN‐γ) production and direct cytotoxicity of NK cells were essential, without notable contribution from T cells. In thalidomide‐treated mice, there was a significant increase in the terminally differentiated mature CD27lo NK cells in the peripheral tissues and NK cells in thalidomide‐treated mice showed significantly higher cytotoxicity and IFN‐γ production. The NK cell expression of T‐bet was upregulated by thalidomide treatment and the downregulation of glycogen synthase kinase‐3β expression was observed in thalidomide‐treated NK cells. Collectively, our study suggests that thalidomide induces the functional maturation of peripheral NK cells through alteration of T‐bet expression to inhibit lung metastasis of cancer cells.

The therapeutic potential of losartan in lung metastasis of colorectal cancer.

Colorectal cancer (CRC) is a common cancer with a high incidence rate. Components of the renin-angiotensin system (RAS) have been reported to be dysregulated in several malignancies including CRC. Here, we have explored the potential anti-metastatic effects of a RAS inhibitor, losartan, in an experimental model of lung metastasis in CRC. A murine model of lung metastasis of CRC was used, which involved the intravenous injection of CT26 cells via a tail vein. Four experimental groups comprised: an untreated group; a group that received 5-FU which was administered intraperitoneally; a losartan group and a combination group that received 5-FU plus losartan. We evaluated the anti-inflammatory effects of losartan by histopathological method, and the measurement of oxidative or antioxidant markers including malondialdehyde (MDA) and total thiol (T-SH) tissue levels, superoxide dismutase (SOD) and catalase activity. We found that losartan inhibited lung metastasis of CRC and there was a reduction of the IL-6 expression level in the tissue sample. It was also associated with reduced levels of the anti-angiogenic factor vascular endothelial growth factor (VEGF). Furthermore, we found that losartan induced oxidative stress as assessed by an elevation of MDA level, reduction of T-SH, SOD and catalase activities in lung tissue. Our findings demonstrated that losartan ameliorates angiogenesis, inflammation and the induction of oxidative stress via angiotensin II type I receptor (AT1R). This may shine some lights on targeting the RAS pathway as a potential therapeutic approach in the treatment of metastatic CRC patients.