SNAIL expression correlates with the translocation of syndecan-1 intracellular domain into the nucleus in prostate cancer cell lines

Abstract

Zinc finger protein SNAI1 (SNAIL) and zinc finger protein SNAI2 (SLUG) transcription factors promote epithelial-mesenchymal transition, a process through which epithelial cells acquire a mesenchymal phenotype, increasing their migratory and invasive properties. In prostate cancer (PCa) progression, increased expression levels of SNAIL and SLUG have been described. In advanced PCa, a decrease in the cell surface proteoglycan syndecan-1 (SDC-1), which has a role in cell-to-extracellular matrix adhesion, has been observed. Notably, SDC-1 nuclear location has been observed in mesenchymal cancers. The present study aimed to determine if SNAIL and SLUG may be associated with the nuclear location of SDC-1 in PCa. To determine the location of SDC-1, antibodies against its intracellular domain (ID) or extracellular domain (ED) were used in benign prostatic hyperplasia (BPH) and PCa samples with high Gleason scores. Only ID-SDC-1 was located in the cell nuclei in advanced PCa samples, but not in the BPH samples. ED-SDC-1 was located in the cell membrane and cytoplasm, exhibiting decreased levels in PCa in comparison with those in BPH. Furthermore, LNCaP and PC3 PCa cell lines with ectopic SNAIL expression exhibited nuclear ID-SDC-1. No change was observed in the ED-SDC-1 levels, and maintained its location in the cell membrane and cytoplasm. SLUG induced no change in ID-SDC-1 location. At the protein level, an association between SNAIL and nuclear ID-SDC-1 was observed. In conclusion, the results of the present study demonstrated that nuclear ID-SDC-1 localization was associated with SNAIL expression in PCa cell lines.