Short interfering RNA directed against Slug blocks tumor growth, metastasis formation, and vascular leakage in bladder cancer

Abstract

In a previous study, we have identified Slug as selectively overexpressed in the highly invasive bladder cancer cells. Furthermore, Slug overexpression was correlated with metastasis in bladder cancer tissues. Here, we investigated the role and underlying mechanism of Slug in the process of growth, invasion and metastasis formation, and vascular leakage in a bladder cancer cell line T24. We knocked down in a bladder cancer cell line T24 by Slug siRNA, and the effects on invasion, metastasis, and proliferation were evaluated in vitro. A pseudometastatic model of bladder cancer in severe combined immunodeficient mice was used to assess the effects of Slug silencing on metastasis and angiogenesis development. Slug-specific siRNA in T24 cells led to a significant decrease in invasiveness and metastasis, proliferation rates, and angiogenesis in vitro. Slug-specific siRNA induced strong changes in cell invasiveness mainly through a mechanism of up-regulation of epithelial markers E-cadherin expression. Interestingly, E-cadherin-specific siRNA attenuated Slug siRNA-induced Matrigel invasion. Moreover, Slug-specific siRNA induced strong changes in microvessel counts in angiogenesis mainly through decreased activity of MMP-2, but not through cadherin expression and decreased activity of MMP-9. Restoration of MMP-2 expression in the Slug-silenced T24 cells resulted in an increased cell angiogenesis. Moreover, Slug-specific siRNA significantly reduced tumor growth by approximately 60% and inhibited metastasis and angiogenesis in a xenograft mouse model. This was accompanied by an increased expression of E-cadherin and a decreased expression of MMP-2 in tumor tissues. These data suggest that Slug regulates tumor growth, invasion and metastasis, and angiogenesis through E-cadherrin and MMPS passway. Blocking Slug signaling in bladder cancer may represent a novel strategy in the future to reduce metastatic disease burden in bladder cancer patients.

Downregulation ofSKA1Gene Expression Inhibits Cell Growth in Human Bladder Cancer

“…Recently, RNA interference has been extensively used to target genes implicated with proliferation, apoptosis, cell cycle regulation, invasion, and metastasis in bladder cancer, [21][22][23][24][25][26][27] which provides promising therapeutic strategies for the treatment of bladder cancer. In the present study, the authors employed lentivirus-mediated RNAi to suppress SKA1 expression in BT5637 and T-24 bladder cancer cell lines.…”

The contribution of TGF-β in Epithelial–Mesenchymal Transition (EMT): Down-regulation of E-cadherin via snail

“…In addition, there are several intracellular signaling pathways involved in regulation of Slug, which can be activated by EGF, FGFs, TGF, and oncogenic Ras [74,75]. It is indicated that the ectopic expression of Slug blocked E-cadherin and promoted Vimentin and Fibronectin expression, resulting in a full EMT phenotype [52,54,76,77], while silencing of Slug expression increased expression of E-cadherin and reversed EMT process [78,79]. Similar to Slug, Snail was found to convert normal epithelial cells into mesenchymal cells through the direct repression of E-cadherin expression [40,54].…”

Riding the crest of the wave: parallels between the neural crest and cancer in epithelial‐to‐mesenchymal transition and migration

“…Furthermore, upregulation of Snail proteins has been shown to correlate with an increased incidence of tumor metastasis, recurrence, and an overall poorer prognosis in human cancers including breast, ovarian, colon, liver, and squamous cell carcinomas, suggesting that Snail is involved in increased EMT and tumor cell migration in human patients 3. In addition, inhibition of Snail in tumor cell lines or in orthotopic mouse models can reverse EMT and invasiveness 16–18. Interestingly, in studies of transformed primary human melanocytes, which form metastatic melanomas in nude mice, the upregulation of Snail2 expression is required for metastatic spread 19.…”

“…3 In addition, inhibition of Snail in tumor cell lines or in orthotopic mouse models can reverse EMT and invasiveness. [16][17][18] Interestingly, in studies of transformed primary human melanocytes, which form metastatic melanomas in nude mice, the upregulation of Snail2 expression is required for metastatic spread. 19 Furthermore, in patients with benign nevi that have not undergone malignant transformation, Snail2 is highly expressed and is significantly correlated with the expression of other NC migration-associated genes.…”