KCl Cotransporter-3 Down-regulates E-Cadherin/β-Catenin Complex to Promote Epithelial-Mesenchymal Transition

Abstract

The potassium chloride cotransporter (KCC) is a major determinant of osmotic homeostasis and plays an emerging role in tumor biology. Here, we investigate if KCC is involved in the regulation of epithelial-mesenchymal transition (EMT), a critical cellular event of malignancy. E-cadherin and B-catenin colocalize in the cell-cell junctions, which becomes more obvious in a time-dependent manner by blockade of KCC activity in cervical cancer SiHa and CaSki cells. Real-time reverse transcription-PCR on the samples collected from the laser microdissection indicates that KCC3 is the most abundant KCC isoform in cervical carcinoma. The characteristics of EMT appear in KCC3-overexpressed, but not in KCC1-or KCC4-overexpressed cervical cancer cells, including the elongated cell shape, increased scattering, down-regulated epithelial markers (E-cadherin and B-catenin), and up-regulated mesenchymal marker (vimentin). Some cellular functions are enhanced by KCC3 overexpression, such as increased invasiveness and proliferation, and weakened cell-cell association. KCC3 overexpression decreases mRNA level of E-cadherin. The promoter activity assays of various regulatory sequences confirm that KCC3 expression is a potent negative regulator for human E-cadherin gene expression. The proteosome inhibitor restores the decreased protein abundance of B-catenin by KCC3 overexpression. In the surgical specimens of cervical carcinoma, the decreased E-cadherin amount was accompanied by the increased KCC3 abundance. Vimentin begins to appear at the invasive front and becomes significantly expressed in the tumor nest. In conclusion, KCC3 down-regulates E-cadherin/B-catenin complex formation by inhibiting transcription of E-cadherin gene and accelerating proteosome-dependent degradation of B-catenin protein. The disruption of E-cadherin/B-catenin complex formation promotes EMT, thereby stimulating tumor progression. [Cancer Res 2007;67(22):11064-73]

Upregulation of vimentin and aberrant expression of E-cadherin/β-catenin complex in oral squamous cell carcinomas: correlation with the clinicopathological features and patient outcome

“…[9][10][11][12] Several studies of epithelial malignancies have shown that E-cadherin or b-catenin can have a transcriptional and regulatory role in invasion and metastasis and is associated with a poor outcome. [13][14][15][16][17][18][19][20][21][22][23] E-cadherin is a 120 kDa calcium-dependent transmembrane glycoprotein encoded by the CDH1 gene located on chromosome 16q21, and it is expressed in most epithelial cells. 18 E-cadherin has a major role in establishing cell polarity and in maintaining normal tissue architecture.…”

Arachidonic Acid Activates K+-Cl--cotransport in HepG2 Human Hepatoblastoma Cells

“…In addition to these physiological roles, inappropriate activation of KCC in red blood cells leads to excessive KCl loss, cell shrinkage and elevation of hemoglobin concentration (Olivieri et al, 1992;Joiner, 1993), leading to deleterious rheological effects, including increased vascular resistance (Stuart and Ellory, 1988). Recently KCC appears to be involved not only in cancer cell proliferation and invasion (Shen et al, 2004;Hsu et al, 2007a;Hsu et al, 2007b), but also in apoptotic cell death ). Therefore, KCC seems to be important in both physiological and pathophysiological processes, but regulatory mechanism of KCC is not much understood.…”

“…Interestingly, recent reports have suggested that KCC is expressed in a variety of human cancer cells. KCC has been reported to down-regulates E-cadherin/ β-catenin complex formation by inhibiting transcription of E-cadherin gene and accelerating proteosome-dependent degradation of β-catenin protein, which promotes epithelialmesenchymal transition, thereby stimulating tumor progression (Hsu et al, 2007a). In addition, upregulation of KCC has been shown to be required for proliferation and invasiveness induced by insulin-like growth factor 1 in breast cancer cells (Hsu et al, 2007b), and cervical and ovarian cancer cells (Shen et al, 2004).…”

Arachidonic Acid Mediates Apoptosis Induced by N-Ethylmaleimide in HepG2 Human Hepatoblastoma Cells

“…Interestingly, Shen et al (2000) have reported that human cervical carcinogenesis is accompanied by up-regulation of KCC transcripts. Recently KCC has shown to be involved in cancer cell proliferation and invasion (Shen et al, 2004;Hsu et al, 2007a;Hsu et al, 2007b). We have also reported that the prolonged activation of KCC could induce apoptosis in HepG2 human hepatoma cells .…”

“…KCC has been reported to down-regulates E-cadherin/β-catenin complex formation by inhibiting transcription of E-cadherin gene and accelerating proteosome-dependent degradation of β-catenin protein, which promotes epithelial-mesenchymal transition, thereby stimulating tumor progression (Hsu et al, 2007a). In addition, upregulation of KCC has been shown to be required for proliferation and invasiveness induced by insulin-like growth factor 1 in breast cancer cells (Hsu et al, 2007b), and cervical and ovarian cancer cells (Shen et al, 2004).…”