α-Tomatine, isolated from Lycopersicon esculentum Linn., is a naturally occurring steroidal glycoalkaloid in immature green tomatoes. Some reports demonstrated that α-tomatine had various anticarcinogenic properties. The purpose of this study is to investigate the anti-metastatic effect of α-tomatine in NCI-H460 human non-small cell lung cancer cells. First, the results showed that α-tomatine significantly suppressed the abilities of the adhesion, invasion, and migration of NCI-H460 cells under non-cytotoxic concentrations. Molecular data also showed α-tomatine could inhibit the activation of focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K)/Akt signal involve in the downregulation the enzyme activities, protein and messenger RNA levels of matrix metalloproteinase-7 (MMP-7). Next, α-tomatine also strongly inhibited the degradation of inhibitor of kappaBα (IκBα) and the nuclear levels of nuclear factor kappa B (NF-κB). Also, a dose-dependent inhibition on the binding ability of NF-κB by α-tomatine treatment was further observed. Furthermore, α-tomatine significantly decreased the levels of phospho-Akt and MMP-7 in Akt1-cDNA-transfected cells concomitantly with a marked reduction on cell invasion and migration. Presented results indicated α-tomatine might be further application for treating cancer metastasis.
This study first investigates the anti-metastatic effect of plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MMPs and u-PA expressions in human lung cancer cells, A549. First, the result demonstrated plumbagin could inhibit TPA induced the abilities of the adhesion, invasion, and migration by cell-matrix adhesion assay and Boyden chamber assay. Data also showed plumbagin could inhibit the activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) involved in the down-regulating enzyme activities, protein and messenger RNA levels of matrix metalloproteinase-2 (MMP-2), and urokinase-type plasminogen activator (u-PA) induced by TPA. Next, plumbagin also strongly inhibited TPA-induced phosphorylation and degradation of inhibitor of kappaBalpha (IkappaBalpha), and the nuclear levels of nuclear factor kappa B (NF-kappaB), c-Fos, and c-Jun. Also, a dose-dependent inhibition on the binding abilities of NF-kappaB and activator protein-1 (AP-1) by plumbagin treatment was further observed. Further, the treatment of specific inhibitor for ERK (U0126) to A549 cells could inhibit TPA-induced MMP-2 and u-PA expressions along with an inhibition on cell invasion and migration. Presented data reveals that plumbagin is a novel, effective, anti-metastatic agent that functions by down-regulating MMP-2 and u-PA gene expressions.
Demethoxycurcumin (DMC), curcumin (Cur), and bisdemethoxycurcumin (BDMC) are major forms of curcuminoids found in the rhizomes of turmeric. This study examined the effects of three curcuminoid analogues on breast cancer cells. The results revealed that DMC demonstrated the most potent cytotoxic effects on breast cancer MDA-MB-231 cells. Compared with estrogen receptor (ER)-positive or HER2-overexpressing breast cancer cells, DMC demonstrated the most efficient cytotoxic effects on triple-negative breast cancer (TNBC) cells. However, nonmalignant MCF-10A cells were unaffected by DMC treatment. The study showed that DMC activated AMPK in TNBC cells. Once activated, AMPK inhibited eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) signaling and mRNA translation via mammalian target of rapamycin (mTOR) and decreased the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). DMC also targeted multiple AMPK downstream pathways. Among these, the dephosphorylation of Akt is noteworthy because it circumvents the feedback activation of Akt that results from mTOR inhibition. Moreover, DMC suppressed LPS-induced IL-6 production, thereby blocking subsequent Stat3 activation. In addition, DMC also sustained epidermal growth factor receptor (EGFR) activation by suppressing the phosphatases, PP2a and SHP-2. These results suggest that DMC is a potent AMPK activator that acts through a broad spectrum of anti-TNBC activities.
Background and purpose: Tetracyclines were recently found to induce tumour cell death, but the early processes involved in this cytotoxic effect remain unclear. Experimental approach: Viability of human and mouse melanoma cells was determined by MTT assay and flow cytometry. Kinase/protein/caspase activation was measured by Western blotting and mitochondrial membrane potential (DYm) was analyzed by fluorescence microscopy and flow cytometry. Key results: Human and mouse melanoma cells were treated with doxycycline or minocycline but only doxycycline was cytotoxic. This cell death (apoptosis) in A2058 cells involved activation of caspase-3, -7 and -9 and contributed to inhibition, by doxycycline, of matrix metalloproteinase (MMP) activity and migration of these cells. Doxycycline induced intra-cellular reactive oxygen species (ROS) production, apoptosis signal-regulated kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) activation at an early stage of treatment and induced mitochondrial cytochrome c release into cytosol and DYm change during apoptosis. The JNK inhibitor/small interference RNA inhibited doxycycline-induced JNK activation, DYm change and apoptosis, but did not affect ASK1 activation, suggesting a role of ASK1 for JNK activation in melanoma cell apoptosis. Two ROS scavengers reduced doxycycline-induced JNK and caspase activation, and apoptosis. Taken together, the results suggest the involvement of a ROS-ASK1-JNK pathway in doxycycline-induced melanoma cell apoptosis.
Conclusions and implications:We have shown a promising cytotoxic effect of doxycycline on melanoma cells, have identified ROS and ASK1 as the possible initiators and have demonstrated that JNK activation is necessary for doxycycline-induced melanoma cell apoptosis.
Weight loss due to skeletal muscle atrophy in patients with chronic pulmonary disease is negatively correlated with clinical outcome. Pulmonary fibrosis is a chronic and progressive interstitial lung disease characterized by the dysregulated deposition of the extracellular matrix (ECM) with the destruction of normal tissue, resulting in end-stage organ failure. BLM-induced fibrosis is one of several different experimental models of pulmonary fibrosis, characterized by inflammation and excessive ECM deposition. We directly induced mouse lung injury by the intratracheal administration of bleomycin and monitored the physiological and biochemical changes in lung and skeletal muscle tissues by using lung function testing, ELISA, Western blotting, and immunohistochemistry. Here, we found that BLM-induced lung fibrosis with thickened interstitial lung tissue, including fibronectin and collagen, was correlated with the increased serum concentrations of IL-6 and IL-33 and accompanied by reduced lung function, including FRC (functional residual capacity), C chord (lung compliance), IC (inspiratory capacity), VC (vital capacity), TLC (total lung capacity), and FVC (forced vital capacity) (p<0.05). The activity of AKT in lung tissue was suppressed, but conversely, the activity of STAT3 was enhanced during lung fibrosis in mice. In addition, we found that the amount of sST2, the soluble form of the IL-33 receptor, was dramatically decreased in lung fibrosis tissues. The skeletal muscle tissue isolated from lung injury mice increased the activation of STAT3 and AMPK, accompanied by an increased amount of Atrogin-1 protein in BLM-induced lung fibrosis mice. The mouse myoblast cell-based model showed that IL-6 and IL-33 specifically activated STAT3 and AMPK signaling, respectively, to induce the expression of the muscle-specific proteolysis markers MuRF1 and Atrogin-1. These data suggested that increased levels of IL-6 and IL-33 in the serum of mice with BLM-induced lung injury may cause lung fibrosis with thickened interstitial lung tissue accompanied by reduced lung function and muscle mass through the activation of STAT3 and AMPK signals.
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