Authors

Lei CaoFollow

Date of Completion

8-10-2012

Embargo Period

8-10-2012

Open Access

Open Access

Abstract

BACKGROUND

The zinc importer LIV-1 is widely distributed, mainly in hormonally controlled tissues. Attention has focused on its role in breast cancer, especially its regulation by estrogen and epidermal growth factor (EGF) and its link to the Epithelial–Mesenchymal Transition (EMT) marker, E-cadherin (CDH1). EMT is important for tumor progression and metastasis. CDH1 expression is under complex control, including by two transcriptional repressors, Snail and Slug. Contrast to CDH1, elevated MMP-9 expression has been linked to increased metastasis and tumor stage.

METHODS

The role of LIV-1 in prostate cancer cell lines, LNCaP and DU145 was investigated. Cells were treated with or without 10ng/ml EGF for 24 hours. LIV-1 shRNA transfection was used to knockdown LIV-1. The mRNA and protein expression were analyzed by two-step RT-PCR and western blot, respectively.

RESULTS

In both DU145 cells and LNCaP cells, EGF induced LIV-1 protein expression by about 20% and decreased CDH1 mRNA and protein by approximately 40%. However, no significant change in LIV-1 mRNA was seen with EGF treatment, indicating a post-transcriptional mechanism. EGF also promoted proliferation in the two cell lines.

LIV-1shRNA vectors decreased the LIV-1 mRNA and protein expression in DU145 cells by around 40%. The effects of LIV-1 knockdown on CDH1, Snail, Slug and MMP-9 mRNA expression were also measured. LIV-1 knockdown increased CDH1 mRNA (80%), while it decreased the expression of Snail mRNA (60%) and MMP-9 mRNA (40%) significantly. There was no significant change observed in Slug mRNA expression. It was also found that LIV-1 knockdown inhibited cell proliferation of DU145 cells, suggesting that LIV-1 may contribute to the EGF-stimulated cell proliferation.

CONCLUSIONS

This study established an inverse relationship between LIV-1 expression and CDH1 in prostate cancer cells.

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