Kidney Week

Abstract: TH-PO562

Suppressive Effect of RXR Ligand and MEK Inhibitor on RXR Expression and Cellular Proliferation in Immortalized Polycystic Kidney Cells

Session Information

• Cystic Kidney Diseases - I
  November 02, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Genetic Diseases of the Kidney

• 801 Cystic Kidney Diseases

Authors

• Kugita, Masanori, Fujita Health University, Toyoake, Aichi, Japan

Masanori Kugita,

• Yamaguchi, Tamio, Suzuka University of Medical Science, Suzuka, Mie, Japan

Tamio Yamaguchi,

• Nishii, Kazuhiro, Fujita Health University, Toyoake, Aichi, Japan

Kazuhiro Nishii,

• Sasaki, Mai, Fujita Health University, Toyoake, Aichi, Japan

Mai Sasaki,

• Ogiso, Noboru, National Center for Geriatrics and Gerontology, Obu-city, Aichi, Japan

Noboru Ogiso,

• Aukema, Harold M., University of Manitoba, Winnipeg, Manitoba, Canada

Harold M. Aukema,

• Nagao, Shizuko, Fujita Health University, Toyoake, Aichi, Japan

Shizuko Nagao,

Background

We previously reported that expression of renal retinoid X receptor (RXR) was increased in three animal models of cystic kidney disease (Kugita et al AJP Renal 2011), and presented that treatment with bexaroten, a RXR agonist, significantly decreased renal RXR expression and kidney weight to body weight ratios in Han:SPRD-Cy/+ rats (Kugita et al ASN 2015). In hepatocellular carcinoma, phosphorylated RXR is related to aberrant cell proliferation accompanied by MEK-ERK phosphorylation to inhibit its degradation. RXR ligands may have suppressive effects on cell proliferation by dephosphorylation and degradation of RXR (Adachi et al Hepatology 2002). In the current study, we determined the phosphorylation sites of RXR, and elucidated the effects of a RXR ligand and a MEK inhibitor on expression of RXR and ERK, and proliferation of immortalized PKD cells.

Methods

An immortalized PKD cell line, WT9-12 was obtained from ATCC and was maintained in DMEM with 10% FBS. Phosphorylation of RXR was analyzed by Phos-tag SDS-PAGE. To elucidate the effect of RXR ligand and MEK inhibitor, starved WT9-12 cells were treated with 10mM 9-cis retinoic acid (9cRA) and/or 100mM U0126. The expression levels of RXR and phospho-ERK (pERK) were analyzed by western blotting. Cell proliferation activity was measured by the MTT assay.

Results

In WT9-12 cells, RXR was phosphorylated on Ser and Thr residues. Treatment with 9cAR alone, U0126 alone and the combination of these two reduced the expression of RXR by 20%, 8% and 23%, of pERK by 40%, 22% and 42%, and cell proliferation by 9%, 14% and 26%, respectively, when compared with vehicle treated cells.

Conclusion

The RXR ligand had a suppressive effect on proliferation of immortalized PKD cells, possibly by reducing expression of RXR and pERK. RXR ligands may have therapeutic potential either alone or in combination with MEK inhibitors to ameliorate PKD progression.

Funding

• Government Support - Non-U.S.