Loss of MKK4 expression in ovarian cancer: a potential role for the epithelial to mesenchymal transition.

Abstract

In the current study, we investigated the mechanism relating downregulation of mitogen-activated protein kinase kinase 4 (MKK4) expression to development of ovarian cancer. Over-expression of the MKK4 gene in TOV-21 G cells, a line with homozygous deletion of MKK4, resulted in morphologic changes in which cells growing in a scattered, fibroblast-like pattern formed tightly packed colonies. Based on a wound healing assay and a Matrigel invasion assay, we determined that both motility and invasiveness of MKK4-transfected TOV-21G cells were significantly reduced compared to control vector-transfected cells. To confirm that MKK4 expression related to tumor invasion resulted from an epithelial to mesenchymal transition (EMT)-like morphological change, we used 2 independent but complementary approaches. MKK4 gene knockdown in MDAH 2774 cells over-expressing MKK4 increased invasion activity. Additionally, engineered expression of MKK4 in SKOV3 cells, a line with low endogenous MKK4 expression, produced a phenotype similar to that of TOVG-21G. Interestingly, we found that MKK4 upregulation caused downregulation of phosphorylated NF-κB and Twist, as well as upregulation of E-cadherin, in TOVG-21G and SKOV3 cells. Reciprocal results were obtained in MDAH 2774 cells with MKK4 knockdown. Our results suggest that MKK4 downregulation causes increased phosphorylation NF-κB. This promotes Twist over-expression, resulting in E-cadherin downregulation that induces EMT in ovarian cancer.

• Authors: Shamima Yeasmin, Kentaro Nakayama, Mohammed Tanjimur Rahman, Munmun Rahman, Masako Ishikawa, Atsuko Katagiri, Kouji Iida, Naomi Nakayama, Kohji Miyazaki
• Journal: International journal of cancer (Int J Cancer) Vol. 128 Issue 1 Pg. 94-104 (Jan 01 2011) ISSN: 1097-0215 [Electronic] United States
• PMID: 20309881 (Publication Type: Journal Article)
• Copyright: Copyright © 2010 UICC.

Chemical References

• NF-kappa B
• RNA, Small Interfering
• MAP Kinase Kinase 4
• MAP2K4 protein, human

Topics

• Animals
• Blotting, Western
• Cell Line, Tumor
• Cell Movement (genetics)
• Disease Progression
• Epithelial-Mesenchymal Transition (genetics)
• Female
• Gene Deletion
• Gene Expression Regulation, Enzymologic
• Gene Expression Regulation, Neoplastic
• Humans
• In Situ Hybridization, Fluorescence
• MAP Kinase Kinase 4 (genetics, metabolism)
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• NF-kappa B (metabolism)
• Neoplasms, Experimental (enzymology, genetics, pathology)
• Ovarian Neoplasms (enzymology, genetics, pathology)
• Phosphorylation
• RNA Interference
• RNA, Small Interfering (genetics)
• Reverse Transcriptase Polymerase Chain Reaction
• Transfection
• Transplantation, Heterologous