Phorbol 12-myristate 13-acetate induces alteration in mucin gene expression and biological properties of colon cancer cells

Suppression of PMA-induced tumor cell invasion and migration by ginsenoside Rg1 via the inhibition of NF-κB-dependent MMP-9 expression

Ginseng has become one of the most commonly used alternative herbal medicines, and its active component, ginsenoside Rg1 has known pharmacological effects, including anticancer properties. However, the effects of ginsenoside Rg1 on metastasis have yet to be investigated. In this study, we demonstrated the ability of ginsenoside Rg1 to suppress phorbol myristate acetate (PMA)-induced invasion and migration in MCF-7 breast cancer cells. MCF-7 cells were treated with ginsenoside Rg1 and incubated with or without PMA. The protein and mRNA expression of MMP-9 and MMP-2 was analyzed using Transwell and wound‑healing assays and western blotting. The results showed that suppression was associated with the reduced secretion of MMP-9, a key metastatic enzyme. MMP-9 levels were regulated transcriptionally and correlated with the suppression of NF-κB phosphorylation and DNA binding activity. Conversely, ginsenoside Rg1 did not affect MMP-2 mRNA and TIMP-1 mRNA levels, or the activation of AP-1, suggesting a specificity of pathway inhibition. Inhibition of NF‑κB activation by p65 small‑interfering RNA (siRNA) was shown to suppress PMA-induced cell invasion and migration. The siRNA studies also showed that PMA-induced MMP-9 expression is NF-κB-dependent. The results suggested that the anticancer properties of ginsenoside Rg1 may derive from its ability to inhibit invasion and migration, and that these processes are regulated in breast cancer cells through the NF-κB‑mediated regulation of MMP-9 expression.

Red ginseng extract reduced metastasis of colon cancer cells in vitro and in vivo

This study investigated the effect of red ginseng extract on metastasis of colon cancer cells in vitro and in vivo. Wound healing migration, cell motility, invasion, and activity, protein expression, and mRNA expression of matrix metalloproteinases (MMPs) were examined in SW480 human colon cancer cells. SW480 cells were cultured with or without 100 μg/L PMA in the absence or presence of various concentrations (100, 200, or 300 μg/mL) of red ginseng extract. Red ginseng extract treatment caused significant suppression of cell motility and invasion (p<0.05) in SW480 cells. Red ginseng extract inhibited MMP-2 and MMP-9 activity and their protein and mRNA expression in a dose-dependent manner (p<0.05) in SW480 cells. For experimental metastasis, BALB/c mice were injected intravenously with CT-26 mouse colon cancer cells in the tail vein, and were orally administered various concentrations (0, 75, 150, or 300 mg/kg body weight) of red ginseng extract for 3 weeks. Numbers of pulmonary nodules were significantly decreased in mice that were fed red ginseng extract (p<0.05). Plasma MMP-2 and MMP-9 activity significantly decreased in response to treatment with red ginseng extract in mice (p<0.05). These data suggest that red ginseng extract may be useful for prevention of cancer invasion and metastasis through inhibition of MMP-2 and MMP-9 pathways.

Selective cyclooxygenase-2 silencing mediated by engineered E. coli and RNA interference induces anti-tumour effects in human colon cancer cells

Background:

Cyclooxygenase-2 (COX-2) overexpression is strongly associated with colorectal tumourigenesis. It has been demonstrated that the chronic use of non-steroidal anti-inflammatory drugs (COX inhibitors) partially protects patients from colorectal cancer (CRC) development and progression but induces severe cardiovascular side effects. New strategies for selective COX-2 blockade are required.

Methods:

We developed an improved technique, based on RNA interference (RNAi), to gain a selective COX-2 silencing in CRC cells by a tumour-dependent expression of anti-COX-2 short-hairpin RNA (shCOX-2). Anti-COX-2 shRNA-expressing vectors were delivered in CRC cells (in vitro) and in colon tissues (ex vivo) using engineered Escherichia coli strains, capable of invading tumour cells (InvColi).

Results:

A highly tumour-dependent shCOX-2 expression and a significant COX-2 silencing were observed in CRC cells following InvColi strain infection. Cyclooxygenase-2 silencing was associated with a strong reduction in both proliferative and invasive behaviour of tumour cells. We also demonstrated a pivotal role of COX-2 overexpression for the survival of CRC cells after bacterial infection. Moreover, COX-2 silencing was achieved ex vivo by infecting colon tissue samples with InvColi strains, leading to anti-inflammatory and anti-tumour effects.

Conclusion:

Our RNAi/InvColi-mediated approach offers a promising tool for a highly selective COX-2 blockade in vitro and in vivo.

Heme oxygenase-1 inhibits breast cancer invasion via suppressing the expression of matrix metalloproteinase-9

In the present study, we investigated the antitumor effects of the invasiveness and migration of heme oxygenase 1 (HO-1) in human breast carcinoma cells. 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced matrix metalloproteinase-9 (MMP-9) enzyme activity and gene expression at both protein and mRNA levels were examined in human breast carcinoma cells (MCF-7 and MDA-MB-231), and the addition of the MMP-9 inhibitor, SB3CT, significantly suppressed TPA-induced invasion and migration according to the in vitro Transwell assay. Elevation of HO-1 gene expression by ferric protoporphyrin IX inhibited TPA-induced invasion of MCF-7 cells, which was blocked by adding the heme oxygenase inhibitor, tin protoporphyrin IX, or transfection of cells with HO-1 short hairpin RNA. MCF-7 cells overexpressing HO-1 (MCF-7/HO-1) were established in the present study, and TPA-induced MMP-9 gene expression, tumor invasion, and colony formation were significantly reduced in MCF-7/HO-1 cells, compared with those in Neo-transfected cells. Activation of protein kinase Calpha/extracellular signal-regulated kinases/AP-1 with stimulation of reactive oxygen species production was involved in TPA-induced invasion of MCF-7 cells, which was attenuated by HO-1 protein induced by ferric protoporphyrin IX or transfection of HO-1 expression vectors. Additionally, the addition of carbon monoxide, but not ferric ions, biliverdin, or bilirubin, inhibited TPA-induced invasion through suppressing MMP-9, extracellular signal-regulated kinases, and AP-1 activation stimulated by TPA. The beneficial role of HO-1 in blocking tumor invasion was first identified in this study.

Distinctive epidermal growth factor receptor/extracellular regulated kinase-independent and -dependent signaling pathways in the induction of airway mucin 5B and mucin 5AC expression by phorbol 12-myristate 13-acetate

Elevated expression of gel-forming mucin (MUC) genes MUC5AC and MUC5B is a major pathological feature in various airway diseases. In this study, we show that phorbol 12-myristate 13-acetate (PMA) is a potent stimulator for MUC5B gene expression under air-liquid interface conditions in three airway epithelial cell systems: primary cultures of normal human bronchial epithelial cells, the immortalized normal bronchial epithelial cell line HBE1, and the human lung adenocarcinoma cell line A549. Stimulation was time- and dose-dependent, could be demonstrated by promoter-reporter gene transfection, and was sensitive to mithramycin A, suggesting the involvement of a specificity protein 1-based transcriptional mechanism in the stimulation. PMA-induced MUC5B message and promoter-reporter gene activity were specifically sensitive to inhibition of protein kinase C delta, which was further confirmed by the forced expression of dominant-negative mutant of protein kinase C delta. Regarding downstream transduction, PMA-induced MUC5B expression was sensitive to inhibitors and dominant-negative expression of signaling molecules involved in Ras/mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase1-mediated c-Jun N-terminal kinase and p38 pathways. This contrasted with the inhibition of PMA-induced MUC5AC expression by inhibitors of the Ras/epidermal growth factor receptor/extracellular regulated kinase signaling pathway. These results demonstrate for the first time that PMA-stimulated MUC5AC and MUC5B expressions are regulated through distinctive epidermal growth factor receptor/extracellular regulated kinase-dependent and -independent signaling pathways.

Lipopolysaccharide induces overexpression of MUC2 and MUC5AC in cultured biliary epithelial cells: possible key phenomenon of hepatolithiasis

Bacterial infection, bile stasis, mucin hypersecretion, and an alteration of the mucin profile such as an aberrant expression of gel-forming apomucin (MUC2 and MUC5AC) in the intrahepatic biliary tree are thought to be important in the lithogenesis of hepatolithiasis. So far, there have been no detailed studies linking bacterial infection to altered mucus secretion of biliary epithelium. In this study, the influence of lipopolysaccharide (LPS), a bacterial component, on apomucin expression in cultured murine biliary epithelial cells was examined with emphasis on the participation of tumor necrosis factor (TNF)-alpha. It was found that LPS up-regulated the expression of MUC2 and MUC5AC in cultured murine biliary epithelial cells. LPS also induced the expression of TNF-alpha in biliary epithelial cells and its secretion into the culture medium. The up-regulation of these apomucins was inhibited by pretreatment with TNF-alpha antibody. TNF-alpha alone also induced the overexpression of MUC2 and MUC5AC in cultured biliary epithelial cells. This overexpression was inhibited by pretreatment with calphostin C, an inhibitor of protein kinase C. These findings suggest that LPS can induce overexpression of MUC2 and MUC5AC in biliary epithelial cells via synthesis of TNF-alpha and activation of protein kinase C. This mechanism might be involved in the lithogenesis of hepatolithiasis.