Aree Moon

Phthalates inhibit tamoxifen-induced apoptosis in MCF-7 human breast cancer cells.

Environmental estrogens represent a class of compounds that can mimic the function or activity of the endogenous estrogen 17β-estradiol (E2). Phthalates including butyl benzyl phthalate (BBP), di(n-butyl) phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) are used as plasticizers, and also widely used in food wraps and cosmetic formulations. Phthalates have been shown to mimic estrogen and are capable of binding to the estrogen receptor (ER). It has been demonstrated that estrogen promotes drug resistance to tamoxifen (TAM) in breast cancer. In order to further evaluate the potential role of the phthalates as environmental estrogens, the effect of phthalates was investigated on TAM-induced apoptosis in MCF-7 human breast cancer cells. Our results show that phthalates, BBP (100 μM), DBP (10 μM), and DEHP (10 μM), significantly increased cell proliferation in MCF-7, but not in MDA-MB-231 cells. In addition, BBP, DBP, and DEHP mimicked estrogen in the inhibition of TAM-induced apoptosis in MCF-7 cells. Our data suggest that the inhibitory effect of phthalates on TAM-induced apoptosis involves an increase in intracellular Bcl-2 to Bax ratio. Given that the phthalates are widely used in cosmetics mainly for women, our findings that revealed the promoting effect of BBP, DBP, and DEHP on chemotherapeutic drug resistance to TAM in breast cancer may be of biological relevance.

Capsaicin-induced apoptosis in SK-Hep-1 hepatocarcinoma cells involves Bcl-2 downregulation and caspase-3 activation

Hepatocellular carcinoma is one of the most lethal malignancies and there is no effective preventive measure in this highly malignant disease to date. In the present study, we investigated the chemopreventive potential of capsaicin (8-methyl-N- vanillyl-6-nonenamide), the principal pungent ingredient found in hot red pepper, in SK-Hep-1 hepatocellular carcinoma cells. Treatment of capsaicin inhibited growth of SK-Hep-1 cells in a concentration-dependent manner while 4-methoxy capsaicin (Met-capsaicin) was less potent. This inhibitory effect of capsaicin on SK-Hep-1 cell growth was mainly due to the induction of apoptosis as evidenced by DNA fragmentation and nuclear condensation. Furthermore, capsaicin prominently reduced the ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax and consequently increased caspase-3 activity. These results demonstrate that capsaicin efficiently induced apoptosis in SK-Hep-1 cells through a caspase-3-dependent mechanism, which may contribute to its chemopreventive function.

The p38 MAPK inhibitors for the treatment of inflammatory diseases and cancer.

Background: The p38 mitogen-activated protein kinase (MAPK) is activated by various pro-inflammatory and stressful stimuli. Mounting evidence suggests that the p38 MAPK signaling cascade is involved in various biological responses other than inflammation such as cell proliferation, differentiation, apoptosis and invasion, suggesting that the p38 MAPK can serve as a potential therapeutic target for the treatment of not only inflammatory diseases but also cancer. Methods: The unique characteristics of p38 MAPK are summarized with regard to activation and function of p38 MAPK signaling cascades. We then discuss the involvement of p38 MAPK in diseases and the implications of the possible therapeutic use of p38 MAPK inhibitors. The p38 MAPK inhibitors that have been used in the in vitro/in vivo systems as well as in the clinical trials are summarized. Results/conclusion: The p38 MAPK plays an important role in key cellular processes related to inflammation and cancer. Understanding the signal transduction mechanisms and gene regulation by p38 MAPK provides useful information in the development of p38 MAPK inhibitors with therapeutic benefits with reduced side effects. In this review, we summarize and present the list of p38 MAPK inhibitors in in vitro/in vivo studies as well as in clinical trials.

H‐ras, but not N‐ras, induces an invasive phenotype in human breast epithelial cells: A role for MMP‐2 in the h‐ras‐induced invasive phenotype

Elevated p21ras expression is associated with tumor aggressiveness in breast cancer including the extent of invasion into fat tissues, infiltration into lymphatic vessels and tumor recurrence. In the present study, we have examined the roles of H‐ras and N‐ras, members of the human ras gene family, in the pathogenesis of breast cancer. We show that H‐ras, but not N‐ras, induces an invasive phenotype in human breast epithelial cells (MCF10A) as determined by the Matrigel invasion assay, whereas both H‐ras and N‐ras induce anchorage‐independent growth, as shown by soft agar assay. We examined the effects of H‐ras and N‐ras activation on the expression of MMP‐2 and MMP‐9, which can degrade type IV collagen, the major structural collagen of the basement membrane. We show that MMP‐2 is efficiently induced by H‐ras, whereas MMP‐9 induction is more prominent in N‐ras‐activated MCF10A cells. We also show that H‐ras‐mediated invasiveness is significantly inhibited when the expression of MMP‐2 is down‐regulated, using an oligodeoxyribonucleotide complementary to the MMP‐2 mRNA, or when MMP‐2 activity is blocked by its inhibitor TIMP‐2 (tissue inhibitors of matrix metalloproteinase‐2). Our results show that the H‐ras‐induced invasive phenotype is associated more closely with the expression of MMP‐2 in human breast epithelial cells, rather than the induction of MMP‐9 expression, as shown previously for rat embryonic fibroblasts. Int. J. Cancer 85:176–181, 2000. ©2000 Wiley‐Liss, Inc.

Roles of JNK-1 and p38 in selective induction of apoptosis by capsaicin in ras-transformed human breast epithelial cells.

Efforts have been made to develop a chemoprevention strategy that selectively triggers apoptosis in malignant cancer cells. Previous studies showed that capsaicin, the major pungent ingredient of red pepper, had differential effect between normal and transformed cells. As an approach to unveil the molecular mechanism by which capsaicin selectively induces apoptosis in transformed cells, we investigated the effect of capsaicin in nontransformed and ras‐transformed cells of a common origin: parental (MCF10A) and H‐ras‐transformed (H‐ras MCF10A) human breast epithelial cells. Here, we show that capsaicin selectively induces apoptosis in H‐ras‐transformed cells but not in their normal cell counterparts. The capsaicin‐induced apoptosis, which is dependent on ras transformation, involves the activity of DEVDase (caspase‐3 like). In H‐ras MCF10A cells, capsaicin treatment markedly activated c‐Jun N‐terminal protein kinase (JNK)‐1 and p38 matigen‐activated protein kinase (MAPK) while it deactivated extracellular signal‐regulated protein kinases (ERKs). The use of kinase inhibitors and overexpression of dominant‐negative forms of MAPKs demonstrated a role of JNK‐1 and p38, but not that of ERKs, in apoptosis induced by capsaicin in H‐ras‐transformed MCF10A cells. Based on the present study, we propose that capsaicin selectively induces apoptosis through modulation of ras‐downstream signaling molecules in ras‐activated MCF10A cells. Taken in conjunction with the fact that uncontrolled ras activation is probably the most common genetic defect in human cancer cells, our finding may be critical to the chemopreventive potential of capsaicin and for developing a strategy to induce tumor cell‐specific apoptosis.

Inhibition of invasion and induction of apoptosis by curcumin in H-ras-transformed MCF10A human breast epithelial cells.

Curcumin, a dietary pigment in turmeric, posseses anti-carcinogenic and anti-metastatic properties. The present study was conducted to studyin vitro chemopreventive effects of curcumin in transformed breast cells. Here, we show that curcumin inhibits H-ras-induced invasive phenotype in MCF10A human breast epithelial cells (H-ras MCF10A) and downregulates matrix metalloproteinase (MMP)-2 dose-dependently. Curcumin exerted cytotoxic effect on H-ras MCF10A cells in a concentration-dependent manner. Curcumin-induced cell death was mainly due to apoptosis in which a prominent downregulation of Bcl-2 and upregulation of Bax were involved. We also suggest a possible involvement of caspase-3 in curcumin-induced apoptosis. Curcumin treatment resulted in the production of reactive oxygen species (ROS) in H-ras MCF10A cells. Apoptotic event by curcumin was significantly inhibited by pretreatment of an antioxidantN-acetyl-1-cysteine (NAC), suggesting redox signaling as a mechanism responsible for curcumin-induced apoptosis in H-ras MCF10A cells. Taken together, our results demonstrate that curcumin inhibits invasion and induces apoptosis, proving the chemopreventive potential of curcumin.

Global gene expression profiling unveils S100A8/A9 as candidate markers in H-ras-mediated human breast epithelial cell invasion

The goal of the present study is to unveil the gene expression profile specific to the biological processes of human breast epithelial cell invasion and migration using an MCF10A model genetically engineered to constitutively activate the H-ras or N-ras signaling pathway. We previously showed that H-Ras, but not N-Ras, induces MCF10A cell invasion/migration, whereas both H-Ras and N-Ras induce cell proliferation and phenotypic transformation. Thus, these cell lines provide an experimental system to separate the gene expression profile associated with cell invasion apart from cell proliferation/transformation. Analysis of whole human genome microarray revealed that 412 genes were differentially expressed among MCF10A, N-Ras MCF10A, and H-Ras MCF10A cells and hierarchical clustering separated 412 genes into four clusters. We then tested whether S100A8 and S100A9, two of the genes which are most highly up-regulated in an H-Ras–specific manner, play a causative role for H-Ras–mediated MCF10A cell invasion and migration. Importantly, small interfering RNA–mediated knockdown of S100A8/A9 expression significantly reduced H-Ras–induced invasion/migration. Conversely, the induction of S100A8/A9 expression conferred the invasive/migratory phenotype to parental MCF10A cells. Furthermore, we provided evidence of signaling cross-talk between S100A8/A9 and the mitogen-activated protein kinase signaling pathways essential for H-Ras–mediated cell invasion and migration. Taken together, this study revealed S100A8/A9 genes as candidate markers for metastatic potential of breast epithelial cells. Our gene profile data provide useful information which may lead to the identification of additional potential targets for the prognosis and/or therapy of metastatic breast cancer. (Mol Cancer Res 2008;6(10):1544–53)

Sphingosine 1-phosphate regulates matrix metalloproteinase-9 expression and breast cell invasion through S1P3-Gαq coupling.

Recent evidence suggests that inflammation is involved in malignant progression of breast cancer. Sphingosine 1-phosphate (S1P), acting on the G-protein-coupled receptors, is known as a potent inflammatory mediator. In this study, the effect of the inflammatory lipid S1P on the regulation of invasive/migratory phenotypes of MCF10A human breast epithelial cells was investigated to elucidate a causal relationship between inflammation and the control of invasiveness of breast cells. We show that S1P causes induction of matrix metalloproteinase-9 (MMP-9) in vitro and in vivo, and thus enhances invasion and migration. We also show that fos plays a crucial role in the transcriptional activation of MMP-9 by S1P. In addition, activation of extracellular-signal-regulated kinases 1 and 2 (ERK1/2), p38 and alpha serine/threonine-protein kinase (Akt) are involved in the process of S1P-mediated induction of MMP-9 expression and invasion. Activation of the S1P receptor S1P3 and Gαq are required for S1P-induced invasive/migratory responses, suggesting that the enhancement of S1P-mediated invasiveness is triggered by the specific coupling of S1P3 to the heterotrimeric Gαq subunit. Activation of phospholipase C-β4 and intracellular Ca2+ release are required for S1P-induced MMP-9 upregulation. Taken together, this study demonstrated that S1P regulates MMP-9 induction and invasiveness through coupling of S1P3 and Gαq in MCF10A cells, thus providing a molecular basis for the crucial role of S1P in promoting breast cell invasion.

Roles of calcium-binding proteins, S100A8 and S100A9, in invasive phenotype of human gastric cancer cells.

Gastric cancer is one of the most common malignancies and is a frequent cause of cancer-related death in Korea. Cure rate of gastric cancer is quite low because of local invasion and metastasis. S100 proteins are calcium-binding proteins which exert various calcium-mediated cellular functions including cell growth, differentiation, migration and signal transduction. S100A8 and S100A9 are overexpressed in many human tumors and have been shown to be implicated in tumor development or progression. In the present study, we investigated the role of S100A8 and S100A9 in invasive phenotype of a human gastric cancer cell line, SNU484. Expression of S100A8 and S100A9 were detected in SNU484 cells. When the expression of these proteins was suppressed by small-interfering RNA (siRNA) targeting S100A8 or S100A9, the invasive and migratory phenotypes of SNU484 cells were significantly inhibited. The siRNAs for S100A8 and S100A9 inhibited matrix metalloproteinase (MMP)-2 expression in SNU484 cells as evidenced by gelatin zymogram assay, immunoblot analysis and reverse transcription (RT)-PCR. These results demonstrate that S100A8 and S100A9 are required for transcriptional activation of MMP-2 gene in SNU484 cells. Taken together, this study revealed a functional contribution of S100A8 and S100A9 proteins to processes required for malignant progression including invasion, migration and proteinase expression in SNU484 human gastric cancer cells.

Inflammatory and microenvironmental factors involved in breast cancer progression

The primary reason for the high mortality rate of breast cancer is metastasis, which can result in a poor survival rate. The tumor environment is important for promotion and invasion of cancer cells. Recent studies have shown that inflammation is associated with breast cancer. Therefore, it is important to investigate the role of the inflammatory and microenvironment in breast cancer progression and metastasis. The present review summarizes some of the markers for inflammation and breast cancer invasion, which may aid in the design of an appropriate therapy for metastatic breast cancer. The following four inflammatory markers are discussed in this review: (1) Tumor associated macrophages (TAMs); (2) Matrix metalloproteinases (MMPs); (3) Sphingosine 1-phosphate (S1P); (4) C-reactive protein (CRP). TAMs are commonly found in breast cancer patients, and high infiltration is positively correlated with poor prognosis and low survival rate. MMPs are well-known for their roles in the degradation of ECM components when cancer cells invade and migrate. MMPs are also associated with inflammation through recruitment of a variety of stromal cells such as fibroblasts and leukocytes. S1P is an inflammatory lipid and is involved in various cellular processes such as proliferation, survival, and migration. Recent studies indicate that S1P participates in breast cancer invasion in various ways. CRP is used clinically to indicate the outcome of cancer patients as well as acute inflammatory status. This review summarizes the current understanding on the role of S1P in CRP expression which promotes the breast epithelial cell invasion, suggesting a specific mechanism linking inflammation and breast cancer. The present review might be useful for understanding the relationship between inflammation and breast cancer for the development of pharmacological interventions that may control the primary molecules involved in the breast cancer microenvironment.