Long‑term exposure to leptin enhances the growth of prostate cancer cells

  • Authors:
    • Terutaka Noda
    • Tadahiko Kikugawa
    • Nozomu Tanji
    • Noriyoshi Miura
    • Seiji Asai
    • Shigeki Higashiyama
    • Masayoshi Yokoyama
  • View Affiliations

  • Published online on: January 23, 2015     https://doi.org/10.3892/ijo.2015.2845
  • Pages: 1535-1542
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Abstract

Obesity correlates with an increased risk of developing prostate cancer (PCa) and leptin plays an important role in PCa progression. Since leptin is produced by adipocytes, the serum leptin level is higher in obese than in non‑obese individuals. However, the effects of leptin remain controversial and unclear. The aim of the present study was to investigate the effect of leptin on PCa cell aggressiveness. Three human PCa cell lines (LNCaP, DU145 and PC‑3) were treated with recombinant leptin for 28 days. Cell proliferation, migration, and invasion were estimated using the WST assay, a wound‑healing assay, and a BD Matrigel invasion assay, respectively. The mechanism underlying the proliferative effect of leptin was investigated by cell transfections with small interfering RNA (siRNA) against the leptin receptor (ObR) or forkhead box O1 (FOXO1), and by immunocytochemistry. Long‑term exposure of PCa cells to leptin enhanced their proliferation, migration and invasion. Leptin increased ObR expression and enhanced Akt phosphorylation constitutively. Leptin also increased the phosphorylation of FOXO1 via PI3K signaling and FOXO1 gene silencing enhanced PCa cell proliferation. Leptin induced the translocation of FOXO1 from the nucleus to the cytoplasm. Furthermore, the PI3K inhibitor, LY294002 suppressed this translocation. These results suggested that leptin regulated the subcellular localization of FOXO1 and induced Akt phosphorylation. Additionally, we revealed that leptin increased the expression of cyclin D1 and decreased the expression of p21 protein. In conclusion, long‑term exposure to leptin increased the cell proliferation, migration, and invasion of PCa cells through inactivation of FOXO1. This inactivation resulted from exclusion of FOXO1 from the nucleus and its restriction to the cytoplasm through PI3K/Akt signaling. Our findings contribute to an understanding of the association between obesity and PCa aggressiveness.
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April-2015
Volume 46 Issue 4

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Noda T, Kikugawa T, Tanji N, Miura N, Asai S, Higashiyama S and Yokoyama M: Long‑term exposure to leptin enhances the growth of prostate cancer cells. Int J Oncol 46: 1535-1542, 2015
APA
Noda, T., Kikugawa, T., Tanji, N., Miura, N., Asai, S., Higashiyama, S., & Yokoyama, M. (2015). Long‑term exposure to leptin enhances the growth of prostate cancer cells. International Journal of Oncology, 46, 1535-1542. https://doi.org/10.3892/ijo.2015.2845
MLA
Noda, T., Kikugawa, T., Tanji, N., Miura, N., Asai, S., Higashiyama, S., Yokoyama, M."Long‑term exposure to leptin enhances the growth of prostate cancer cells". International Journal of Oncology 46.4 (2015): 1535-1542.
Chicago
Noda, T., Kikugawa, T., Tanji, N., Miura, N., Asai, S., Higashiyama, S., Yokoyama, M."Long‑term exposure to leptin enhances the growth of prostate cancer cells". International Journal of Oncology 46, no. 4 (2015): 1535-1542. https://doi.org/10.3892/ijo.2015.2845