Liver X receptor agonist inhibits proliferation of ovarian carcinoma cells stimulated by oxidized low density lipoprotein.

OBJECTIVES

We previously observed an association between ovarian cancer outcome and statin use and hypothesized lipoproteins have direct effects on ovarian cancer proliferation. Here we investigate the direct effects of low density lipoprotein (LDL) and oxidized LDL (oxLDL) on proliferation and the inhibitory effects of fluvastatin and a liver X receptor (LXR) agonist.

METHODS

The effects of LDL, oxLDL, the LXR agonist TO901317, fluvastatin and cisplatin on cellular proliferation were determined using MTT assays. LXR pathway proteins were assayed by immunoblotting. Cytokine expression was determined by antibody array.

RESULTS

Concentrations of oxLDL as small as 0.1 microg/ml stimulated CAOV3 and SKOV3 proliferation, while LDL had no effect. TO901317 inhibited the proliferation of CAOV3, OVCAR3 and SKOV3 cells stimulated by oxLDL. Fluvastatin inhibited oxLDL mediated proliferation of CAOV3 and SKOV3. Cardiotrophin 1 (CT-1) was mitogenic to CAOV3 and SKOV3, was induced by oxLDL, and was reversed by TO901317. OxLDL increased cisplatin IC50s by 3.8 microM and > 60 microM for CAOV3 and SKOV3 cells, respectively. The LXR pathway proteins CD36, LXR, and ABCA1 were expressed in eight ovarian carcinoma cell lines (A2780, CAOV3, CP70, CSOC882, ES2, OVCAR3, SKOV3).

CONCLUSIONS

OxLDL reduced ovarian carcinoma cell chemosensitivity and stimulated proliferation. These effects were reversed by LXR agonist or fluvastatin. The LXR agonist also inhibited expression of the ovarian cancer mitogen CT-1. These observations suggest a biologic mechanism for our clinical finding that ovarian cancer survival is associated with statin use. Targeting LXR and statin use may have a therapeutic role in ovarian cancer.