Allyl isothiocyanate and its N-acetylcysteine conjugate suppress metastasis via inhibition of invasion, migration, and matrix metalloproteinase-2/-9 activities in SK-Hep 1 human hepatoma cells

Inhibition of bladder cancer development by allyl isothiocyanate

Bladder cancer is one of the common human cancers and also has a very high recurrence rate. There is a great need for agents capable of inhibiting bladder cancer development and recurrence. Here, we report that allyl isothiocyanate (AITC), an ingredient of many common cruciferous vegetables, potently inhibited the proliferation of bladder carcinoma cell lines in vitro [half maximal inhibitory concentration (IC(50)) of 2.7-3.3 microM], which was associated with profound G(2)/M arrest and apoptosis. In contrast, AITC was markedly less toxic to normal human bladder epithelial cells (IC(50) of 69.4 microM). AITC was then evaluated in two rat bladder cancer models in vivo (an orthotopic model and a subcutaneous model). The orthotopic model closely mimics human bladder cancer development and recurrence. We show that a low oral dose of AITC (1 mg/kg) significantly inhibited the development and muscle invasion of the orthotopic bladder cancers but was ineffective against the subcutaneous xenografts of the same cancer cells in the same animals. This differential effect was explained by our finding that urinary levels of AITC equivalent were two to three orders of magnitude higher than that in the plasma and that its levels in the orthotopic cancer tissues were also three orders of magnitude higher than that in the subcutaneous cancer tissues. Moreover, we show that AITC is a multi-targeted agent against bladder cancer. In conclusion, AITC is selectively delivered to bladder cancer tissue through urinary excretion and potently inhibits bladder cancer development and invasion.

Ontogenetic changes of 2-propenyl and 3-indolylmethyl glucosinolates in Brassica carinata leaves as affected by water supply

Concentrations of 2-propenyl and 3-indolylmethyl glucosinolates in two lines of Brassica carinata (Holeta-1 and 37-A) were assessed during the vegetative life cycle under optimal or drought-inducing water supply conditions. In the well-watered treatment, 2-propenyl and 3-indolylmethyl glucosinolate concentrations remained almost constant from the 6-8 to the 15-16 leaf stage, whereas a drought-induced water supply led to a distinct increase of these glucosinolates. Generally, the 2-propenyl concentration was higher in Holeta-1 at each leaf stage under drought stress as compared with 37-A, indicating a B. carinata line-specific drought response. The drought-induced glucosinolate accumulation seems to be integrated in the plant's process of osmotic adjustment. It seems that under drought, there is a shift from primary to secondary metabolism, thereby promoting glucosinolate synthesis. Thus, by keeping the relative soil-water content below 80%, glucosinolate concentrations could be increased up to the 15-16 leaf stage, resulting in better plant nutritional quality of B. carinata.

Molecular targets of nutraceuticals derived from dietary spices: potential role in suppression of inflammation and tumorigenesis

Despite the fact cancer is primarily a preventable disease, recent statistics indicate cancer will become the number one killer worldwide in 2010. Since certain cancers are more prevalent in the people of some countries than others, suggests the role of lifestyle. For instance cancer incidence among people from the Indian subcontinent, where most spices are consumed, is much lower than that in the Western World. Spices have been consumed for centuries for a variety of purposes-as flavoring agents, colorants, and preservatives. However, there is increasing evidence for the importance of plant-based foods in regular diet to lowering the risk of most chronic diseases, so spices are now emerging as more than just flavor aids, but as agents that can not only prevent but may even treat disease. In this article, we discuss the role of 41 common dietary spices with over 182 spice-derived nutraceuticals for their effects against different stages of tumorigenesis. Besides suppressing inflammatory pathways, spice-derived nutraceuticals can suppress survival, proliferation, invasion, and angiogenesis of tumor cells. We discuss how spice-derived nutraceuticals mediate such diverse effects and what their molecular targets are. Overall our review suggests "adding spice to your life" may serve as a healthy and delicious way to ward off cancer and other chronic diseases.

Antiangiogenic and proapoptotic activities of allyl isothiocyanate inhibit ascites tumor growth in vivo

The authors investigate the antiangiogenic and proapoptotic effects of mustard essential oil containing allyl isothiocyanate (AITC) and explore its mechanism of action on Ehrlich ascites tumor (EAT) cells. Swiss albino mice transplanted with EAT cells were used to study the effect of AITC. AITC was effective at a concentration of 10 mum as demonstrated by the inhibition of proliferation of EAT cells when compared with the normal HEK293 cells. It significantly reduced ascites secretion and tumor cell proliferation by about 80% and inhibited vascular endothelial growth factor expression in tumor-bearing mice in vivo. It also reduced vessel sprouting and exhibited potent antiangiogenic activity in the chorioallantoic membrane and cornea of the rat. AITC arrested the growth of EAT cells by inducing apoptosis and effectively arrested cell cycle progression at the G1 phase. The results clearly suggest that AITC inhibits tumor growth by both antiangiogenic and proapoptotic mechanisms.

Phytochemicals as potential chemopreventive and chemotherapeutic agents in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the fifth commonest malignancy worldwide and the incidence is rising. Surgery, including transplantation resection, is currently the most effective treatment for HCC; however, recurrence rates are high and long-term survival is poor. Identifying novel chemopreventive and chemotherapeutic agents and targeting them to patients at high risk of developing HCC or following curative treatment may go some way towards improving prognosis. This review examines current knowledge regarding the chemopreventive and chemotherapeutic potential of phytochemicals in heptocarcinogenesis. Both in-vitro and animal studies demonstrate that several phytochemicals, including curcumin, resveratrol, green tea catechins, oltipraz and silibinin, possess promising chemopreventive and chemotherapeutic properties. Despite this, very few clinical trials have been performed. Problems regarding validation of biomarkers, agent delivery, side effects and patient selection are barriers that need to be overcome to determine the potential of such agents in clinical practice.

Allyl isothiocyanate influences cell adhesion, migration and metalloproteinase gene expression in SK-Hep1 cells

Allyl isothiocyanate (AITC) has been reported to exhibit antimetastatic activity, but the mechanism remains unclear. The objective of this study was to determine the effect of AITC on cell adhesion, migration, and metalloproteinase gene expression in SK-Hep1 human hepatoma cells. The gene expression profiles of SK-Hep1 cells were obtained by using the HG-U133A Affymetrix GeneChip human genome array containing 14,500 human genes. Twenty antimetastatic genes including COL4A3, ADAMDEC1, CAPN10, CD14, and ITGB1BP3 were over expressed, while the expression of 35 genes such as COL8A1, MYBPC1, ST14, and SOS2 were down-regulated. Semiquantitative RT-PCR confirmed these results in mRNA levels. Based on these in vitro results, it can be concluded that AITC might be potentially useful in suppressing tumor cell migration and MMP expression.

Endostar Suppresses Invasion Through Downregulating the Expression of Matrix Metalloproteinase-2/9 in MDA-MB-435 Human Breast Cancer Cells

Endostar, a novel recombinant human endostatin expressed and purified in Escherichia coli with an additional nine-amino acid sequence forming another his-tag structure, was approved by the State Food and Drug Administration of China (SFDA) in 2005 for the treatment of non-small-cell lung cancer. However, the molecular mechanism of its potent anticancer activity remains poorly understood and warrants further investigations. In this study, we examined the anti-invasive activities of endostar in vitro. The results showed that endostar suppressed MDA-MB-435 cell adhesion to the fibronectin-coated substrate in a concentration-dependent manner. It could inhibit the wound healing migration of MDA-MB-435 cells and invasion of MDA-MB-435 cells through reconstituted ECM (matrigel). Zymography revealed that endostar decreased the secretion of MMP-2 and MMP-9. Endostar could also inhibit the expressions of MMP-2 and MMP-9 in MDA-MB-435 cells. Additionally, endostar exerted an inhibitory effect on the phosphorylation of ERK1/2. Collectively, these data provided a molecular basis for the anti-invasive effects of endostar.

Benzyl isothiocyanate inhibits metalloproteinase-2/-9 expression by suppressing the mitogen-activated protein kinase in SK-Hep1 human hepatoma cells

Benzyl isothiocyanate (BITC) is a hydrolysis compound of glucotropaeolin in cruciferous vegetables. Many studies have reported that BITC prevents cancers in laboratory animals and might also be chemoprotective in humans. The purpose of this study was to investigate the effects of BITC on cell proliferation, metastasis, and MAPK pathways of SK-Hep1 human hepatocellular carcinoma cells. BITC suppressed SK-Hep1 cell proliferation in a dose-dependent manner, and exposure to 1 and 5 microM BITC reduced cell proliferation by 25% and 30%, respectively. The expression of matrix metalloproteinase (MMP)-2, MMP-9, and membrane type-1/MMP (MT-1/MMP) is a known risk factor for metastatic disease. Gelatin zymography analysis revealed a significant downregulation of MMP-2/-9 protein expression in SK-Hep1 cells treated with 0.1-5 microM BITC. BITC treatment caused dose-dependent decreases in MMP-2/-9 and MT1-MMP mRNA levels as determined by RT-PCR. BITC also increased the mRNA levels of tissue inhibitors of matrix metalloproteinases-2 (TIMP-2) 1.3- and 1.5-fold after a 24 h exposure to 1 and 5 microM BITC, respectively. Increased TIMP-2 expression is mediated by the downregulation of MMP-2 and MT1-MMP. BITC inhibited the phosphorylation activities of all three major mitogen-activated protein kinases (MAPKs) in a dose-dependent manner. BITC at 5 microM reduced the ERK1/2 phosphorylation activity by 50% and p38 activity by 70%. BITC also reduced the p-JNK1/2 level by 30% and 70% at 1 and 5 microM treatments, respectively. These data may represent anti-metastatic activities of BITC through the suppression of MAPKs in SK-Hep1 cells.

Gaining insight into microbial physiology in the large intestine: a special role for stable isotopes

The importance of the human large intestine for nutrition, health, and disease, is becoming increasingly realized. There are numerous indications of a distinct role for the gut in such important issues as immune disorders and obesity-linked diseases. Research on this long-neglected organ, which is colonized by a myriad of bacteria, is a rapidly growing field that is currently providing fascinating new insights into the processes going on in the colon, and their relevance for the human host. This review aims to give an overview of studies dealing with the physiology of the intestinal microbiota as it functions within and in interaction with the host, with a special focus on approaches involving stable isotopes. We have included general aspects of gut microbial life as well as aspects specifically relating to genomic, proteomic, and metabolomic studies. A special emphasis is further laid on reviewing relevant methods and applications of stable isotope-aided metabolic flux analysis (MFA). We argue that linking MFA with the '-omics' technologies using innovative modeling approaches is the way to go to establish a truly integrative and interdisciplinary approach. Systems biology thus actualized will provide key insights into the metabolic regulations involved in microbe-host mutualism and their relevance for health and disease.

p38 mitogen-activated protein kinase pathway is involved in protein kinase Calpha-regulated invasion in human hepatocellular carcinoma cells

Protein kinase Calpha (PKCalpha) has been suggested to play an important role in tumorigenesis, invasion, and metastasis. In this study, we investigated the signal pathways selectively activated by PKCalpha in human hepatocellular carcinoma (HCC) cells to determine the role of mitogen-activated protein kinases (MAPK) in PKCalpha-mediated HCC migration and invasion. A stable SK-Hep-1 cell clone (siPKCalpha-SK) expressing DNA-based small interfering RNA (siRNA) PKCalpha was established and was then characterized by cell growth, migration, and invasion. The expression of PKCalpha was decreased in siPKCalpha-SK, and cell growth, migration, and invasion were reduced. These changes were associated with the decrease in p38 MAPK phosphorylation level, but not in c-jun-NH(2)-kinase-1/2 (JNK-1/2) and extracellular signal-regulated kinase-1/2 (ERK-1/2). This phenomenon was confirmed in the SK-Hep-1 cells treated with antisense PKCalpha olignucleotide. The p38 MAPK inhibitor SB203580 or dominant negative p38 mutant plasmid (DN-p38) was used to evaluate the dependency of p38 MAPK in PKCalpha-regulated migration and invasion. Attenuation of cell migration and invasion was revealed in the SK-Hep-1 cells treated with the SB203580 or DN-p38, but not with ERK-1/2 inhibitor PD98059 or JNK-1/2 inhibitor SP600125. Overexpression of constitutively active MKK6 or PKCalpha may restore the inactivation of p38 and the attenuation of cell migration and invasion in siPKCalpha-SK. Similar findings were observed in the stable HA22T/VGH cell clone expressing siRNA PKCalpha. This study provides new insight into the role of p38 MAPK in PKCalpha-mediated malignant phenotypes, especially in PKCalpha-mediated cancer cell invasion, which may have valuable implications for developing new therapies for some PKCalpha-overexpressing cancers.

Phenylethyl isothiocyanate and its N-acetylcysteine conjugate suppress the metastasis of SK-Hep1 human hepatoma cells

Phenylethyl isothiocyanate (PEITC), a hydrolysis compound of gluconasturtiin, is metabolized to N-acetylcysteine (NAC)-PEITC in the body after the consumption of cruciferous vegetables. We observed an inhibitory effect of PEITC and its metabolite NAC-PEITC on cancer cell proliferation, adhesion, invasion, migration and metastasis in SK-Hep1 human hepatoma cells. PEITC and NAC-PEITC suppressed SK-Hep1 cell proliferation in a dose-dependent manner, and exposure to 10 microM PEITC or NAC-PEITC reduced cell proliferation by 25% and 30%, respectively. NAC-PEITC inhibited cancer cell adhesion, invasion and migration to a similar or to an even larger degree than PEITC. The expression of matrix metalloproteinase (MMP) 2, MMP-9 and membrane type 1 matrix metalloproteinase (MT1-MMP) is a known risk factor for metastatic disease. Gelatin zymography analysis revealed a significant downregulation of MMP-2/MMP-9 protein expression in SK-Hep1 cells treated with 0.1-5 microM PEITC or NAC-PEITC. PEITC and NAC-PEITC treatment caused dose-dependent decreases in MMP-2/MMP-9 and MT1-MMP mRNA levels, as determined by reverse transcription polymerase chain reaction. PEITC and NAC-PEITC also increased the mRNA levels of tissue inhibitors of matrix metalloproteinase (TIMPs) 1 and 2. Our data suggest that this inhibition is mediated by downregulation of MMP and upregulation of TIMPs.