Raloxifene induces cell death and inhibits proliferation through multiple signaling pathways in prostate cancer cells expressing different levels of estrogen receptor α and β

J Cell Physiol. 2011 May;226(5):1334-9. doi: 10.1002/jcp.22461.


Raloxifene (RAL), a selective estrogen receptor (ER) modulator (SERM) seems to induce apoptosis in both androgen-dependent and -independent prostate cell (PC) lines via activation of ERβ and an antagonistic effect on ERα. In this study, we evaluated the effects of RAL on epithelial PC growth using the two following in vitro models: the androgen-dependent cell line EPN which expressed both ERs; and a stabilized epithelial cell line derived from a prostate cancer specimen (CPEC), which expressed low levels of ERβ and lacked ERα. In EPN cells, there was an increase in the pre-G1 apoptotic peak and a reduction in the S phase of the cell cycle with G0/G1 arrest after E2 or RAL treatment; bcl-2 mRNA and Bcl-2 protein levels were significantly reduced, while activated caspase-3 and Par-4 levels increased significantly after either E2 or RAL treatment; in addition, c-myc transcript was inhibited after 10(-6) M RAL treatment. A dose-dependent increase of metallothionein II gene RNA level was also induced by RAL in EPN. In CPEC, there was only a weak apoptotic peak associated with caspase-3 activation and Par-4 increase after either E2 or RAL treatment; while c-myc transcript level increased. RAL induced a rapid but transient phosphorylation of ERK 1/2 in EPN cells but generated a sustained effect in CPEC. These findings suggest that RAL effects on PC growth control in vitro are cell-specific, depending on ERβ or ERβ/ERα relative expression levels. Moreover, this study demonstrated that RAL affected both transcriptional regulation and non-genomic signals, which resulted in the modulation of multiple signaling pathways of apoptosis and of cell cycle progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Hormonal / pharmacology*
  • Apoptosis / drug effects*
  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cell Cycle / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Dihydrotestosterone / pharmacology
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Estradiol / pharmacology
  • Estrogen Receptor alpha / drug effects*
  • Estrogen Receptor alpha / metabolism
  • Estrogen Receptor beta / drug effects*
  • Estrogen Receptor beta / metabolism
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Male
  • Metallothionein / genetics
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Phosphorylation
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Proto-Oncogene Proteins c-myc / genetics
  • RNA, Messenger / metabolism
  • Raloxifene Hydrochloride / pharmacology*
  • Receptors, Thrombin / genetics
  • Receptors, Thrombin / metabolism
  • Selective Estrogen Receptor Modulators / pharmacology*
  • Signal Transduction / drug effects*
  • Time Factors
  • Transcription, Genetic / drug effects


  • Antineoplastic Agents, Hormonal
  • Estrogen Receptor alpha
  • Estrogen Receptor beta
  • MYC protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • Proto-Oncogene Proteins c-myc
  • RNA, Messenger
  • Receptors, Thrombin
  • Selective Estrogen Receptor Modulators
  • Dihydrotestosterone
  • Raloxifene Hydrochloride
  • Estradiol
  • Metallothionein
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • CASP3 protein, human
  • Caspase 3
  • protease-activated receptor 4