Suppression of integrin αυβ6 by RNA interference in colon cancer cells inhibits extracellular matrix degradation through the MAPK pathway

Abstract

Integrin atb6 plays a very important role in the progression of colon cancer cells and is now defined as a novel, independent prognostic indicator for aggressive colon cancer in humans. Herein, we use the RNA interfering technology to downregulate the expression of atb6 in colon cancer cells. Our data demonstrate that plasmid vector based shRNA can effectively down-regulate atb6 expression in protein and mRNA levels. Supression of integrin atb6 inhibits the phosphorylation and nonphosphorylation level of ERK1/2, the secretion of uPA, pro-MMP-9 and pro-MMP-2 in tumor conditioned medium, and more important, inhibits MAPKdependent [ 3 H] labeled collagen IV degradation via the plasminogen activation cascade. Our study demonstrates in vitro that supression of integrin atb6 inhibits extracellular matrix degradation through the MAPK pathway. ' 2008 Wiley-Liss, Inc.Key words: colon cancer; integrin atb6; MAP kinase; RNA interference Cancer cell invasion and metastasis are regarded as multistep phenomena, involving the proteolytic degradation of the extracellular matrix (ECM), altered cell adhesion and the physical movement of cancer cells. Such migratory and tissue remodeling events involve complex interactions between integrins and matrix degrading protease systems, such as the plasminogen activation system.1 The integrins provide direct links with the ECM, functioning as bidirectional transducers of extra-and intracellular signals, and thus potentially modulating cancer cell invasion. 2Integrin atb6 is restrictedly distributed to epithelial cells. It is primarily expressed during fetal development and wound healing. Upregulation of the integrin atb6 is found in some epithelial carcinomas, most notably in orally-derived squamous cell carcinomas, [3][4][5] where the receptor typically displays a focally localized distribution at the infiltrating edge of tumor islands. Recently, the most compelling finding is that atb6 is defined as a novel, independent prognostic indicator for aggressive colon cancer and gastric carcinoma in humans. 6,7 The integrin atb6 may serve to identify patients that are at higher risk of developing metastatic disease and emerges as an attractive new candidate as a therapeutic target for metastatic colon carcinoma.Many proteinases are capable of degrading ECM components, but the proteinase system primarily responsible for ECM degradation in vivo are matrix metalloproteinases (MMPs) and plasminogen activator (PA) systems.8,9 MMP-2 and MMP-9 have been implicated to play a role in colorectal cancer progression, invasion and metastasis in animal models and patients.10 Urokinase plasminogen activator (uPA )is found in cellular structures at the leading edge of migrating cells that are involved in adhesion, migration, invasion and intravasation and is considered to be a marker for malignancy in colon cancer. 11,12 In our previous work, we have reported the relationship between integrin atb6 and MMP-9 in colon cancer. We reported that atb6 expression in colon cancer cells lead to the increase in secret...

Integrinβ6-Targeted Immunoliposomes Mediate Tumor-Specific Drug Delivery and Enhance Therapeutic Efficacy in Colon Carcinoma

“…HT-29 cells constantly express ITGB6. HT-29 cells with siRNA suppressed ITGB6 expression were also prepared as reported previously (25). The cells were maintained as monolayers in medium comprising DMEM (Hyclone) containing 10% heat inactivated FCS (Gibco) and supplemented with 20 mmol/L HEPES, 100 IU/mL penicillin, and 100 mg/mL streptomycin.…”

Proteomic Differences and Linkages between Chemoresistance and Metastasis of Pancreatic Cancer Using Knowledge-Based Pathway Analysis

“…Recently, integrin mediated intracellular signal transduction has been reported to also regulate various cytoplasmic proteins, such as phosphatidylinositol-3 kinase (PI3K) [32,33], the serine-threonine kinase AKT, and the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) [34,35]. Additionally, integrin ligand binding has been reported to activate focal adhesion kinase (FAK), integrin-linked kinase (ILK), and Src kinases that are related to EMT [36][37][38].…”

Clinical significance of integrin β6 as a tumor recurrence factor in follicular thyroid carcinoma

“…Matrix metalloproteinase (MMP)‐2 and MMP‐9 were also reported to play a role in tumor progression, invasion, and metastasis . Additionally, our previous research had found that suppression of integrin β6 inhibited the phosphorylation and non‐phosphorylation level of extracellular regulated protein kinases (ERK)1/2, the secretion of uPA, pro‐MMP‐9, and pro‐MMP‐2 in tumor conditioned medium, and, most importantly, inhibited mitogen‐activated protein kinase‐dependent labeled collagen IV degradation via the plasminogen activation cascade . The purpose of this study was to discuss the relationship of integrin β6, MMP‐2, and MMP‐9 expression levels in clinical characteristics of human follicular thyroid carcinomas.…”