Vascular endothelial growth factor-A and changes in a tumor-bearing mouse model with Lewis lung cancer

Mesenchymal Stem Cells Promote Metastasis of Lung Cancer Cells by Downregulating Systemic Antitumor Immune Response

Since majority of systemically administered mesenchymal stem cells (MSCs) become entrapped within the lungs, we used metastatic model of lung cancer, induced by intravenous injection of Lewis lung cancer 1 (LLC1) cells, to investigate the molecular mechanisms involved in MSC-mediated modulation of metastasis. MSCs significantly augmented lung cancer metastasis, attenuate concentrations of proinflammatory cytokines (TNF-α, IL-17), and increase levels of immunosuppressive IL-10, nitric oxide, and kynurenine in sera of LLC1-treated mice. MSCs profoundly reduced infiltration of macrophages, TNF-α-producing dendritic cells (DCs), TNF-α-, and IL-17-producing CD4+ T cells but increased IL-10-producing CD4+ T lymphocytes in the lungs of tumor-bearing animals. The total number of lung-infiltrated, cytotoxic FasL, perforin-expressing, TNF-α-, and IL-17-producing CD8+ T lymphocytes, and NKG2D-expressing natural killer (NK) cells was significantly reduced in LLC1 + MSC-treated mice. Cytotoxicity of NK cells was suppressed by MSC-conditioned medium. This phenomenon was abrogated by the inhibitors of inducible nitric oxide synthase (iNOS) and indoleamine 2,3-dioxygenase (IDO), suggesting the importance of iNOS and IDO for MSC-mediated suppression of antitumor cytotoxicity of NK cells. This study provides the evidence that MSCs promote lung cancer metastasis by suppressing antitumor immune response raising concerns regarding safety of MSC-based therapy in patients who have genetic susceptibility for malignant diseases.

In vitro and in vivo anti-tumor effects of selected platinum(IV) and dinuclear platinum(II) complexes against lung cancer cells

In the present study, cytotoxic effects of cisplatin, the most usually used chemotherapeutic agent, were compared with new designed platinum(IV) ([PtCl₄(en)] (en = ethylenediamine) and [PtCl₄(dach)]) (dach = (±)-trans-1,2-diaminocyclohexane) and platinum(II) complexes ([{trans-Pt(NH₃)₂Cl}₂(μ-pyrazine)](ClO₄)₂ (Pt1), [{trans-Pt(NH₃)₂Cl}₂(μ-4,4'-bipyridyl)](ClO₄)₂DMF(Pt2),[{trans-Pt(NH₃)₂Cl}₂(μ-1,2-bis(4pyridyl)ethane)](ClO₄)₂ (Pt3)), in vitro and in vivo against human and murine lung cancer cells, to determine anti-tumor potential of newly synthesized platinum-based drugs in the therapy of lung cancer. Results obtained by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], Lactate dehydrogenase and Annexin V/Propidium Iodide assays showed that, among all tested complexes, [PtCl₄(en)] had the highest cytotoxicity against human and murine lung carcinoma cells in vitro. [PtCl₄(en)] showed significantly higher cytotoxicity then cisplatin in all tested concentrations, mainly by inducing apoptosis in lung cancer cells. [PtCl₄(en)] was well tolerated in vivo. Clinical signs of [PtCl₄(en)]-induced toxicity, such as changes in food, water consumption or body weight, nephrotoxicity or hepatotoxicity was not observed in [PtCl₄(en)]-treated mice. [PtCl₄(en)] managed to increase presence of CD45+ leukocytes, including F4/80+ macrophages, CD11c+ dendritic cells, CD4+ helper and CD8+ cytotoxic T cells (CTLs) in the lungs, cytotoxic NK, NKT and CTLs in the spleens of tumor bearing mice, resulting with reduction of metastatic lesions in the lungs, indicating its potential to stimulate anti-tumor immune response in vivo. Due to its anti-tumor cytotoxicity, biocompatibility, and potential for stimulation of anti-tumor immune response, [PtCl₄(en)] may be a good candidate for further testing in the field of medicinal chemistry.

Role of cytokines and chemokines in alcohol-induced tumor promotion

Excessive chronic alcohol consumption has become a worldwide health problem. The oncogenic effect of chronic alcohol consumption is one of the leading concerns. The mechanisms of alcohol-induced tumorigenesis and tumor progression are largely unknown, although many factors have been implicated in the process. This review discusses the recent progress in this research area with concentration on alcohol-induced dysregulation of cytokines and chemokines. Based on the available evidence, we propose that alcohol promotes tumor progression by the dysregulation of the cytokine/chemokine system. In addition, we discuss specific transcription factors and signaling pathways that are involved in the action of these cytokines/chemokines and the oncogenic effect of alcohol. This review provides novel insight into the mechanisms of alcohol-induced tumor promotion.

Gum Arabic-encapsulated gold nanoparticles for a non-invasive photothermal ablation of lung tumor in mice

BACKGROUND

In our previous work, we have extensively evaluated the physiochemical characteristics of Gum Arabic-encapsulated gold nanoparticles (GA-AuNPs; 15-18nm) and reported their effectiveness in stopping the tumor initiation via inhibiting the pre-neoplastic lesions in liver.

OBJECTIVE

The rationale of this study is to detect the efficiency of using GA-AuNPs in photothermal application as a non-invasive technique against lung tumor. We investigated the cytotoxicity of GA-AuNPs on A549 cells, and then studied their apoptotic, anti-inflammatory, lipid peroxidation and anti-neovascular effect in in vivo model using a chemically-induced lung cancer in mice. The histopathological changes due to GA-AuNPs were investigated.

RESULTS

In the presence of laser irradiation, GA-AuNPs had a considerable cytotoxicity against A549 cells. The treatment of lung tumor-bearing mice with GA-AuNPs followed by laser exposure enhanced the apoptotic pathway and this was obvious from the histopathological investigations and the elevations in cytochrome-c, death receptor 5 and the subsequent upregulation of caspase-3, we also reported a significant reduction in the levels of the inflammatory mediator TNF-α and the angiogenesis inducer VEGF. An induction of lipid peroxidation was also reported upon treatment with either GA or GA-AuNPs.

CONCLUSION

GA-AuNPs showed no cytotoxicity in the absence of light, however the combination of GA-AuNPs with laser induced cell death in lung tumor tissues with a reduction in the inflammation and angiogenesis together with an elevation in lipid peroxidation, suggesting the potential use of these functionalized nanoparticles as a promising photothermal non-invasive treatment modality.

Endothelial Rac1 is essential for hematogenous metastasis to the lung

A variety of vasoactive stimuli induce endothelial permeability through Rac1, a membrane of Rho small GTPases. Here, we determine whether tumor-secreted vasoactive stimulant through Rac1 inducing permeability contributes to hematogenous metastasis. Activation of Rac1 was assayed in human umbilical vein endothelial cells (HUVEC), transendothelial passages were measured by Transwell chambers, and hematogenously metastatic mouse model was generated by intravenous injection with Lewis lung carcinoma cells (LLC). LLC secreted abundant vascular endothelial growth factor (VEGF) in the culture media and sera of mice bearing LLC xenografts or metastatic LLC, and VEGF activated Rac1 through VEGF receptors/PI3Kβ signaling cascade, resulting in hyperoxidative stress and consequent hyperpermeability in HUVEC. Moreover, in co-culture of LLC and HUVEC, significant increases in endothelial permeability and transendothelial migration of LLC were robustly attenuated by either anti-VEGF neutralizing antibody or Rac1 knockdown in HUVEC. Finally, in metastatic mouse model, deletion of one copy of Rac1 in endothelium not only significantly attenuated LLC-induced vascular permeability, but robustly reduced the metastasis of LLC to lungs. This study supports that tumor-secreted vasoactive stimuli activate Rac1 to induce permeability and consequent transendothelial migration of tumor cells, and that loss of Rac1 function in endothelium is an effective therapeutic intervention for hematogenous metastasis.

The Application of Cytidyl Guanosyl Oligodeoxynucleotide Can Affect the Antitumor Immune Response Induced by a Combined Protocol of Cryoablation and Dendritic Cells in Lewis Lung Cancer Model

BACKGROUND Recently, several combined therapeutic strategies and targeted agents have been under investigation for their potential role in lung cancer. The combined administration of dendritic cells (DCs) and immune-adjuvant cytidyl guanosyl oligodeoxynucleotide (CpG-ODN) after cryosurgery has proven to be an effective strategy for treating lung cancer. However, whether the application of CpG-ODN could affect the therapeutic results remained to be further explored. MATERIAL AND METHODS The Lewis lung cancer (LLC)-bearing mice received cryoablation and injection of ex vivo-cultured DCs into the peritumoral zone. Subsequently, CpG-ODN was administered to experimental animals 6 hours, 12 hours, and 24 hours after DC injection. The mice in the control group received coadministration of DCs and CpG-ODN simultaneously. Therapeutic effects were evaluated by survival rates. The resistance to rechallenge of LLC cell was assessed by lung metastasis and in vitro cytotoxicity of splenocytes. Furthermore, T-cell subsets and multiple cytokines (interleukin [IL]-4, -10, and-12; interferon [IFN]-γ; tumor necrosis factor [TNF]-α) in the blood were assessed to elucidate the underlying mechanisms. RESULTS Higher ratios of CD4+ and CD8+ T cells and higher levels of IL-12, IFN-γ, and TNF-α were found in the blood of the mice that received CpG-ODN therapy 12 h after DC injection. The cytotoxicity potency of the splenocytes of these mice was significantly higher compared with the mice in other groups. Moreover, the mice receiving CpG-ODN therapy 12 h after DC injection showed significantly better resistance to rechallenge. Compared with the mice in other groups, the mice receiving CpG-ODN therapy 12 h after DC injection were superior in survival rates and antimetastatic effects. CONCLUSIONS Our study suggested that the therapeutic efficacy was closely associated with CpG-ODN administration in the combined therapeutic protocol of cryoablation, DCs, and immune adjuvant. In situ administration of CpG-ODN 12 h after DC injection might be considered the optimum application.

Receptor tyrosine kinase inhibitors: Are they real tumor killers?

Inhibiting tumor growth by targeting the tumor vasculature was first proposed by Judah Folkman almost 40 years ago. Since then, different approaches and numerous drugs and agents have been developed to achieve this goal, either with the aim of inhibiting tumor neoangiogenesis or normalizing the tumor vasculature. Among the most promising therapeutic targets are receptor tyrosine kinases (RTKs), some of which are predominantly expressed on tumor endothelial cells, although they are sometimes also present on tumor cells. The majority of RTK inhibitors investigated over the past two decades competes with ATP at the active site of the kinase and therefore block the phosphorylation of intracellular targets. Some of these drugs have been approved for therapy, whereas others are still in clinical trials. Here, we discuss the scientific basis, current status, problems and future prospects of RTK inhibition in anti-tumor therapy.

Activation of the NF-κB pathway as a mechanism of alcohol enhanced progression and metastasis of human hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC), the most common form of primary liver cancer, is the third leading cause of cancer-related death in human. Alcohol is a known risk factor for HCC. However it is still unclear whether and how alcohol enhances the progression and metastasis of existing HCC.

METHODS AND RESULTS

We first retrospectively investigated 52 HCC patients (24 alcohol-drinkers and 28 non-drinkers), and found a positive correlation between alcohol consumption and advanced Tumor-Node-Metastasis (TNM) stages, higher vessel invasion and poorer prognosis. In vitro and in vivo experiments further indicated that alcohol promoted the progression and migration/invasion of HCC. Specifically, in a 3-D tumor/endothelial co-culture system, we found that alcohol enhanced the migration/invasion of HepG2 cells and increased tumor angiogenesis. Consistently, higher expression of VEGF, MCP-1 and NF-κB was observed in HCC tissues of alcohol-drinkers. Alcohol induced the accumulation of intracellular reactive oxygen species (ROS) and the activation of NF-κB signaling in HepG2 cells. Conversely, blockage of alcohol-mediated ROS accumulation and NF-κB signaling inhibited alcohol-induced expression of VEGF and MCP-1, the tumor growth, angiogenesis and metastasis.

CONCLUSION

This study suggested that chronic moderate alcohol consumption may promote the progression and metastasis of HCC; the oncogenic effect may be at least partially mediated by the ROS accumulation and NF-ĸB-dependent VEGF and MCP-1 up-regulation.

Mouse models for studying angiogenesis and lymphangiogenesis in cancer

The formation of new blood vessels (angiogenesis) is required for the growth of most tumors. The tumor microenvironment also induces lymphangiogenic factors that promote metastatic spread. Anti-angiogenic therapy targets the mechanisms behind the growth of the tumor vasculature. During the past two decades, several strategies targeting blood and lymphatic vessels in tumors have been developed. The blocking of vascular endothelial growth factor (VEGF)/VEGF receptor-2 (VEGFR-2) signaling has proven effective for inhibition of tumor angiogenesis and growth, and inhibitors of VEGF-C/VEGFR-3 involved in lymphangiogenesis have recently entered clinical trials. However, thus far anti-angiogenic treatments have been less effective in humans than predicted on the basis of pre-clinical tests in mice. Intrinsic and induced resistance against anti-angiogenesis occurs in patients, and thus far the clinical benefit of the treatments has been limited to modest improvements in overall survival in selected tumor types. Our current knowledge of tumor angiogenesis is based mainly on experiments performed in tumor-transplanted mice, and it has become evident that these models are not representative of human cancer. For an improved understanding, angiogenesis research needs models that better recapitulate the multistep tumorigenesis of human cancers, from the initial genetic insults in single cells to malignant progression in a proper tissue environment. To improve anti-angiogenic therapies in cancer patients, it is necessary to identify additional molecular targets important for tumor angiogenesis, and to get mechanistic insight into their interactions for eventual combinatorial targeting. The recent development of techniques for manipulating the mammalian genome in a precise and predictable manner has opened up new possibilities for the generation of more reliable models of human cancer that are essential for the testing of new therapeutic strategies. In addition, new imaging modalities that permit visualization of the entire mouse tumor vasculature down to the resolution of single capillaries have been developed in pre-clinical models and will likely benefit clinical imaging.