Yuping Liu

Antimetastatic Therapies of the Polysulfide Diallyl Trisulfide against Triple-Negative Breast Cancer (TNBC) via Suppressing MMP2/9 by Blocking NF-κB and ERK/MAPK Signaling Pathways

Background Migration and invasion are two crucial steps of tumor metastasis. Blockage of these steps may be an effective strategy to reduce the risk. The objective of the present study was to investigate the effects of diallyl trisulfide (DATS), a natural organosulfuric compound with most sulfur atoms found in garlic, on migration and invasion in triple negative breast cancer (TNBC) cells. Molecular mechanisms underlying the anticancer effects of DATS were further investigated. Methods and Results MDA-MB-231 cells and HS 578t breast cancer cells were treated with different concentrations of DATS. DATS obviously suppressed the migration and invasion of two cell lines and changed the morphological. Moreover, DATS inhibited the mRNA/protein/ enzymes activities of MMP2/9 via attenuating the NF-κB pathway. DATS also inhibited ERK/MAPK rather than p38 and JNK. Conclusion DATS inhibits MMP2/9 activity and the metastasis of TNBC cells, and emerges as a potential anti-cancer agent. The inhibitory effects are associated with down-regulation of the transcriptional activities of NF-κB and ERK/MAPK signaling pathways.

PKM2 Regulates Hepatocellular Carcinoma Cell Epithelial-mesenchymal Transition and Migration upon EGFR Activation

Pyruvate kinase isozyme type M2(PKM2) was first found in hepatocellular carcinoma(HCC), and its expression has been thought to correlate with prognosis. A large number of studies have demonstrated that epithelial-mesenchymal transition (EMT) is a crucial event in hepatocellular carcinoma (HCC) and associated metastasis, resulting in enhanced malignancy of HCC. However, the roles of PKM2 in HCC EMT and metastasis remain largely unknown. The present study aimed to determine the effects of PKM2 in EGF-induced HCC EMT and elucidate the molecular mechanisms in vitro. Our results showed that EGF promoted EMT in HCC cell lines as evidenced by altered morphology, expression of EMT-associated markers, and enhanced invasion capacity. Furthermore, the present study also revealed that nuclear translocation of PKM2, which is regulated by ERK pathway, regulated β-catenin-TCF/LEF-1 transcriptional activity and associated EMT in HCC cell lines. These discoveries provide evidence of novel roles of PKM2 in the progression of HCC and potential therapeutic target for advanced cases.

Cancer-promoting effect of capsaicin on DMBA/TPA-induced skin tumorigenesis by modulating inflammation, Erk and p38 in mice.

Epidemiologic and animal studies revealed that capsaicin (8-methyl-N-vanillyl-6-noneamide) can act as a carcinogen or cocarcinogen. However, the influence of consumption of capsaicin-containing foods or vegetables on skin cancer patients remains largely unknown. In the present study, we demonstrated that capsaicin has a cocarcinogenic effect on 9, 10-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin tumorigenesis. Our results showed that topical application of capsaicin on the dorsal skin of DMBA-initiated and TPA-promoted mice could significantly accelerate tumor formation and growth and induce more and larger skin tumors than the model group (DMBA + TPA). Moreover, capsaicin could promote TPA-induced skin hyperplasia and tumor proliferation. Mechanistic study found that inflammation-related factors cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were highly elevated by pretreatment with capsaicin, suggesting an inflammation-dependent mechanism. Furthermore, mice that were administered capsaicin exhibited significant up-regulation of phosphorylation of nuclear factor kappaB (NF-κB), Erk and p38 but had no effect on JNK. Thus, our results indicated that inflammation, Erk and P38 collectively played a crucial role in cancer-promoting effect of capsaicin on carcinogen-induced skin cancer in mice.

Luteolin reduces the invasive potential of malignant melanoma cells by targeting β3 integrin and the epithelial-mesenchymal transition

Aim:To investigate whether luteolin, a highly prevalent flavonoid, reverses the effects of epithelial-mesenchymal transition (EMT) in vitro and in vivo and to determine the mechanisms underlying this reversal.Methods:Murine malignant melanoma B16F10 cells were exposed to 1% O2 for 24 h. Cellular mobility and adhesion were assessed using Boyden chamber transwell assay and cell adhesion assay, respectively. EMT-related proteins, such as E-cadherin and N-cadherin, were examined using Western blotting. Female C57BL/6 mice (6 to 8 weeks old) were injected with B16F10 cells (1×106 cells in 0.2 mL per mouse) via the lateral tail vein. The mice were treated with luteolin (10 or 20 mg/kg, ip) daily for 23 d. On the 23rd day after tumor injection, the mice were sacrificed, and the lungs were collected, and metastatic foci in the lung surfaces were photographed. Tissue sections were analyzed with immunohistochemistry and HE staining.Results:Hypoxia changed the morphology of B16F10 cells in vitro from the cobblestone-like to mesenchymal-like strips, which was accompanied by increased cellular adhesion and invasion. Luteolin (5−50 μmol/L) suppressed the hypoxia-induced changes in the cells in a dose-dependent manner. Hypoxia significantly decreased the expression of E-cadherin while increased the expression of N-cadherin in the cells (indicating the occurrence of EMT-like transformation), which was reversed by luteolin (5 μmol/L). In B16F10 cells, luteolin up-regulated E-cadherin at least partly via inhibiting the β3 integrin/FAK signal pathway. In experimental metastasis model mice, treatment with luteolin (10 or 20 mg/kg) reduced metastatic colonization in the lungs by 50%. Furthermore, the treatment increased the expression of E-cadherin while reduced the expression of vimentin and β3 integrin in the tumor tissues.Conclusion:Luteolin inhibits the hypoxia-induced EMT in malignant melanoma cells both in vitro and in vivo via the regulation of β3 integrin, suggesting that luteolin may be applied as a potential anticancer chemopreventative and chemotherapeutic agent.

Concerted suppression of STAT3 and GSK3β is involved in growth inhibition of non-small cell lung cancer by Xanthatin.

Xanthatin, a sesquiterpene lactone purified from Xanthium strumarium L., possesses prominent anticancer activity. We found that disruption of GSK3β activity was essential for xanthatin to exert its anticancer properties in non-small cell lung cancer (NSCLC), concurrent with preferable suppression of constitutive activation of STAT3. Interestingly, inactivation of the two signals are two mutually exclusive events in xanthatin-induced cell death. Moreover, we surprisingly found that exposure of xanthatin failed to trigger the presumable side effect of canonical Wnt/β-Catenin followed by GSK3β inactivation. We further observed that the downregulation of STAT3 was required for xanthatin to fine-tune the risk. Thus, the discovery of xanthatin, which has ability to simultaneously orchestrate two independent signaling cascades, may have important implications for screening promising drugs in cancer therapies.

Downregulation of Integrins in Cancer Cells and Anti-Platelet Properties Are Involved in Holothurian Glycosaminoglycan-Mediated Disruption of the Interaction of Cancer Cells and Platelets in Hematogenous Metastasis.

Activated platelets have been recognized as an accessory character in the cascade of tumor hematogenous metastasis, and intervention of tumor cell attachment to the activated platelets or microemboli formation might be a leading strategy to prevent tumor cells surviving in the blood vessels and sequential metastasis. Recently, we have demonstrated that holothurian glycosaminoglycan (hGAG), a sulfated polysaccharide with potent anticoagulant activity extracted from the sea cucumber Holothuria leucospilota Brandt, was highly efficacious against tumor metastasis. In this study, we identified the potential effects of hGAG on the disruption of interactions of cancer cells and platelets and the underlying mechanisms, which were supported by the following evidence: hGAG (1) inhibited thrombin-induced platelet activation and aggregation, (2) reduced adhesion between platelet and breast cancer cells, and abrogated platelets/cancer cells adhering to fibrinogen, (3) attenuated platelet-cancer cell complex formation (the number and size of aggregates) and (4) suppressed both mRNA and protein levels of β1 and β3 integrins, matrix metalloproteinase (MMP)-2 and MMP-9, while increasing the expression of the MMP inhibitor, tissue inhibitor of metalloproteinase (TIMP)-1 in MDA-MB-231 cells. These results suggested that both the antiplatelet properties and mitigation of the levels of cellular adhesion molecules contributed to the anticancer effects of hGAG, and might thus be exploited for clinical adjuvant therapy to attenuate tumor hematogenous metastasis.

The angiogenic responses induced by release of angiogenic proteins from tumor cell-activated platelets are regulated by distinct molecular pathways

There is mounting evidence that tumor angiogenesis can be regulated by platelets (Plts), which serve as major sources and delivery vehicles of many proangiogenic cytokines including transforming growth factor‐β and vascular endothelial growth factor. Although considerable progress has been made in understanding the role for Plt secretion in tumor angiogenesis, very little is known about the precise mechanisms underlying cancer cell induction of Plt granule release. Here, we demonstrated that nonsmall cell lung cancer (NSCLC) cells directly induced Plt secretion of several angiogenic regulatory cytokines that promoted angiogenesis in concert. Moreover, we discovered that these Plt‐derived angiogenesis modulators were regulated by different molecular pathways and could be largely inhibited by combination of multiple signaling inhibitors. Our present studies indicated that manipulation of Plt secretion of angiogenic cytokines without compromising hemostatic functions could provide a novel option for management of tumor angiogenesis and metastasis in NSCLC patients with thrombocytosis.

Inhibition of hypoxia-induced epithelial mesenchymal transition by luteolin in non-small cell lung cancer cells

Hypoxia-induced epithelial mesenchymal transition (EMT) is an essential step in cancer metastasis. Luteolin, a flavonoid that is widely distributed in plants, is a novel anticancer agent. However, the mechanism underlying its anticancer effects remains undefined. In this study, for the first time, we demonstrate that luteolin inhibits hypoxia-induced EMT in human non-small cell lung cancer cells in culture, which is demonstrated by the fact that hypoxia-induced EMT reduced the expression of E-cadherin and other epithelial markers and increased the expression of N-cadherin, vimentin and other mesenchymal markers; these effects were markedly attenuated by luteolin. In addition, luteolin also inhibited hypoxia-induced proliferation, motility and adhesion in the cells. Furthermore, we reveal that luteolin inhibits the expression of integrin β1 and focal adhesion kinase (FAK).Since integrin β1 and FAK signaling are closely related to EMT formation, these results suggest that luteolin inhibits hypoxia-induced EMT, at least in part, by inhibiting the expression of integrin β1 and FAK.

Diallyl Trisulfides, a natural histone deacetylase inhibitor, attenuate HIF-1α synthesis and decreases Breast Cancer Metastasis†

Intratumoral hypoxia promotes the distant metastasis of cancer subclones. The clinical expression level of hypoxia‐inducible factor‐1α (HIF‐1α) reflects the prognosis of a variety of cancers, especially breast cancer. Histone deacetylase (HDAC) inhibitors can target HIF‐1α protein due to von Hippel‐Lindau (VHL) protein‐dependent degradation. Dietary organosulfur compounds, such as those in garlic, have been reported as HDAC inhibitors. The effects of diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS) on the ratio of firefly/Renilla luciferase activity in hypoxic MDA‐MB‐231 cells were determined. The mRNA expressions of HIF‐1α target genes ANGPTL4, LOXL4, and LOX in hypoxic MDA‐MB‐231 cells were significantly down‐regulated by DATS. DATS attenuated the metastatic potential of MDA‐MB‐231 cells in hypoxia‐induced embryonic zebrafish, xenograft, and orthotopic tumors. Endothelial cell‐cancer cell adhesion, wound healing, transwell, and tube formation assays showed that DATS dose‐dependently inhibited the migration and angiogenesis of MDA‐MB‐231 cells in vitro. The expressions of L1CAM, VEGF‐A, and EMT‐related proteins (Slug, Snail, MMP‐2) were inhibited by DATS. DATS dose‐dependently inhibited HIF‐1α transcriptional activity and hypoxia‐induced hematogenous metastasis of MDA‐MB‐231 cells. It reduced the protein expression of HIF‐1α, which did not involve inhibition of HIF‐1α mRNA expression or ubiquitin proteasome degradation. Efficient inhibition of HIF‐1α expression was required for DATS to resist breast cancer.

Pleiotropic effects of herbs characterized with blood-activating and stasis-resolving functions on angiogenesis

Accumulative evidences have underpinned the nature candidates from Chinese medicine (CM), particularly CM served as blood activating and stasis resolving (BASR, Huoxue Huayu in Chinese) by targeting tumor-associated angiogenesis. However, recent experiment research on the therapeutic angiogenesis by BASR-CM attracts wide attention and discussion. This opinion review focused on the underlying link between two indications and anticipated that (1) BASR-CM might emphasize on a balanced multi-cytokines network interaction; (2) BASR-CM might address on the nature of diseases prior to differently affecting physiological and pathological angiogenesis; (3) BASR-CM might mainly act on perivascular cells, either promotes arteriogenesis by increasing arteriogenic factors in ischemic diseases, or simultaneously keep a quiescent vasculature to impede angiogenesis in tumor context.