Abstract
Aim: Cellular senescence, leading to cell death through prevention of regular cell renewal, is associated with the upregulation of the tumor suppressor gene p16 INK4a. While this mechanism has been described as leading to progressive nephron loss, p16 INK4a upregulation in renal cell carcinoma has been linked to a disease-specific improved patient survival rate. While in both conditions endothelin-1 is also upregulated, the signaling pathway connecting ET-1 to p16 INK4a has not been characterized until this study. Main methods: Cell culture, qRT-PCR, Western Blot, immunoprecipitation (IP), proximity ligation assay (PLA), and non-radioactive electrophoretic mobility shift assay (EMSA). Key findings: In malignant renal proximal tumor cells (Caki-1), an activation of p16 INK4a and p21 waf1/cip1 was observed. An increased expression of E-26 transformation-specific (ETS) transcription factors was detectable. Using specific antibodies, a complex formation between ETS1 and extracellular signal-regulated kinase-2 (ERK2) was shown. A further complex partner was Mxi2. EMSA with supershift analysis for ETS1 and Mxi2 indicated the involvement of both factors in the protein-DNA interaction. After specifically blocking the endothelin receptors, ETS1 expression was significantly downregulated. However, the endothelin B receptor dependent downregulation was stronger than that of the A receptor. In contrast, primary proximal tubule cells showed a nuclear decrease after ET-1 stimulation. This indicates that other ETS members may be involved in the observed p16 INK4a upregulation (as described in the literature). Significance: ETS1, ERK2 and Mxi2 are important complex partners initiating increased p16 INK4a and p21w af1/cip1 activation in renal tumor cells.
| Original language | English |
|---|---|
| Journal | Life Sciences |
| Volume | 91 |
| Issue number | 13-14 |
| Pages (from-to) | 562-571 |
| Number of pages | 10 |
| ISSN | 0024-3205 |
| DOIs | |
| Publication status | Published - 15.10.2012 |
Funding
The study was supported by the Koeln Fortune Program / Faculty of Medicine, University of Cologne post-doctoral fellowship and a grant from the 2nd Professorinnen Program (to MvB); by a grant from the Marga and Walter Boll Stiftung , Imhoff Stiftung , and the Nolting Stiftung (to JWUF). Since human cells were used, procedures have been followed as outlined in accordance with ethical standards as formulated in the Helsinki Declaration of 1975 (revised 1983). The use of patient tumor samples was approved by the University of Koeln Research Ethics Committee.
Research Areas and Centers
- Academic Focus: Center for Brain, Behavior and Metabolism (CBBM)
