Down‐regulation of MMP‐2 through the p38 MAPK‐NF‐κB‐dependent pathway by aloe‐emodin leads to inhibition of nasopharyngeal carcinoma cell invasion

Abstract

Aloe-emodin (AE), extracted from the rhizome of Rheum palmatum, has an anti-proliferative effect on different human cancer cell lines. Nonetheless, the underlying mechanism by which AE inhibits nasopharyngeal carcinoma (NPC) cell invasion is still unclear. The results of this study show that treatment of NPC cells with growth suppressive concentrations of AE caused cell cycle arrest at the S-G(2)/M phase. Coimmunoprecipitation and small interfering RNA (siRNA) studies demonstrated that AE-induced cell cycle arrest in NPC cells was associated with increasing levels of cyclin B1 bound to cyclin-dependent kinase 1. The inhibition of NPC cell invasion by AE was evidenced through the suppression of matrix metalloproteinases-2 (MMP-2) expression. MMP-2 promoter activity and cell invasion were inhibited by p38 mitogen-activated protein kinase (MAPK) siRNA, inhibitor 4-(4-Fluorophenyl)-2-[4-(methylsulfinyl)phenyl]-5-(4-pyridyl)-1H-imidazole (SB203580), and AE, but not by JNK siRNA and inhibitor 1,9-pyrazoloanthrone. Treatment with AE, SB203580, NF-kappaB inhibitors N-p-tosyl-(L)-phenylalanine chloromethyl ketone (TPCK) and pyrrolidine dithiocarbamate (PDTC) or transfection with p38 MAPK siRNA significantly inhibited NF-kappaB transcriptional activity. In addition, TPCK and PDTC treatment inhibited the expression and promoter activity of MMP-2 and thereby significantly inhibited cell invasion activity. The involvement of p38 MAPK activity in NF-kappaB-mediated MMP-2 function was further confirmed through the attenuation of p38 MAPK by SB203580 and NF-kappaB ectopic expression. Collectively, our results indicate that AE inhibits invasion of NPC cells by suppressing the expression of MMP-2 via the p38 MAPK-NF-kappaB signaling pathway.

Potential Therapeutic Molecular Targets for Nasopharyngeal Carcinoma

“…These results indicate that caspase-8-mediated activation of the mitochondrial death pathway plays a critical role in 60 M AE-induced apoptosis of NPC cells (178). A more recent investigation has revealed that 40 M AE significantly inhibits NPC cell growth through cell cycle arrest at the S-G 2 /M phase, which is associated with increased levels of cyclin B1 bound to Cdk1 but not the apoptotic process (179). Gene silencing of MMP-2 mediated by siRNA inhibits NPC cell invasion, thereby demonstrating the involvement of MMP-2 in the NPC invasion process (179).…”

“…Consistent with the data presented by Lee et al (156), an increase in intracellular ROS levels was observed when apoptosis was induced in NPC cells using 60 M AE (178). However, apoptosis, DNA damage, and increases in ROS levels were not detected in the same cells treated with 40 M AE, therefore suggesting that different concentrations of AE could differentially modulate the expression of cellular genes that are involved in cell growth, apoptosis, and cell invasion in different types of cancer cells (179).…”

“…Gene silencing of MMP-2 mediated by siRNA inhibits NPC cell invasion, thereby demonstrating the involvement of MMP-2 in the NPC invasion process (179). Using siRNA against p38 MAPK, the p38 MAPK inhibitor SB203580, NF-B inhibitors N-p-tosyl-Lphenylalanine chloromethyl ketone and pyrrolidine dithiocarbamate, transient ectopic expression of wild type NF-B, a MMP-2 promoter activity assay, and an NF-B-dependent reporter assay it has been further demonstrated that 40 M AE inhibits the invasion of NPC cells by reducing the expression of MMP-2, likely through the inhibition of the p38 MAPK-NF-B pathway, and that NF-κB activity is involved in regulating the expression of MMP-2 and VEGF through the p38 MAPK-dependent pathway (179). The reason that NPC cells are more sensitive to 60 M than 40 M AE for the induction of apoptosis remains unclear.…”

“…A more recent investigation has revealed that 40 M AE significantly inhibits NPC cell growth through cell cycle arrest at the S-G 2 /M phase, which is associated with increased levels of cyclin B1 bound to Cdk1 but not the apoptotic process (179). Gene silencing of MMP-2 mediated by siRNA inhibits NPC cell invasion, thereby demonstrating the involvement of MMP-2 in the NPC invasion process (179). Using siRNA against p38 MAPK, the p38 MAPK inhibitor SB203580, NF-B inhibitors N-p-tosyl-Lphenylalanine chloromethyl ketone and pyrrolidine dithiocarbamate, transient ectopic expression of wild type NF-B, a MMP-2 promoter activity assay, and an NF-B-dependent reporter assay it has been further demonstrated that 40 M AE inhibits the invasion of NPC cells by reducing the expression of MMP-2, likely through the inhibition of the p38 MAPK-NF-B pathway, and that NF-κB activity is involved in regulating the expression of MMP-2 and VEGF through the p38 MAPK-dependent pathway (179).…”

Multiple Molecular Targets of Antrodia camphorata: A Suitable Candidate for Breast Cancer Chemoprevention

“…Lee et al, 2008). The promoter region of MMP-2 contains various cis-acting elements, including potential binding sites for the transcription factors nuclear factor-kappa B (NF-κB), activator protein-1 (AP-1), and stimulatory protein-1 (SP-1) (Lin et al, 2010). NFkB is critically involved in tumor progression through transcriptional regulation of invasion related factors, such as MMP-2/MM-9, uPA and VEGF (Shibata et al, 2002;Yang et al, 2011).…”