Melatonin MT1 receptor-induced transcriptional up-regulation of p27(Kip1) in prostate cancer antiproliferation is mediated via inhibition of constitutively active nuclear factor kappa B (NF-κB): potential implications on prostate cancer chemoprevention an

Abstract

Our laboratory has recently demonstrated a melatonin MT1 receptor-mediated antiproliferative signaling mechanism in androgen receptor (AR)-positive prostate epithelial cells which involves up-regulation of p27(Kip1) through dual activation of Gα(s)/protein kinase A (PKA) and Gα(q)/protein kinase C (PKC) in parallel, and down-regulation of activated AR signaling via PKC stimulation.

The aim of the present investigation was to identify the transcription factor that mediates melatonin's up-regulatory effect on p27(Kip1) in LNCaP and 22Rv1 prostate cancer cells. Deletion mapping and reporter assays of the p27(Kip1) promoter revealed that the putative melatonin-responsive transcription factor binds to a 116 base-pair region of the promoter sequence, which contains a potential nuclear factor kappa B (NF-κB) binding site. When the NF-κB binding site was abolished by site-directed mutagenesis, the stimulatory effect of melatonin on p27(Kip1) promoter activity was mitigated.

Notably, melatonin inhibited the DNA binding of activated NF-κB via MT1 receptor-induced PKA and PKC stimulation.

Furthermore, melatonin's up-regulatory effect on p27(Kip1) transcription and consequent cell antiproliferation were abrogated by NF-κB activator but mimicked by NF-κB inhibitor.

The results indicate that inhibition of constitutively active NF-κB via melatonin MT1 receptor-induced dual activation of (Gα(s)) PKA and (Gα(q)) PKC can de-repress the p27(Kip1) promoter leading to transcriptional up-regulation of p27(Kip1).

MT1 receptor-mediated inhibition of activated NF-κB signaling provides a novel mechanism supporting the use of melatonin in prostate cancer chemoprevention and therapy.

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See also:

- About Melatonin;

- The Di Bella Method (A Fixed Part - Melatonin tablets);

- Melatonin with adenosine solubilized in water and stabilized with glycine for oncological treatment - technical preparation, effectivity and clinical findings;

- The Di Bella Method (A Fixed Part - Cyclophosphamide and/or Hydroxyurea tablets, one or two per day);

- The Di Bella Method (DBM) in the treatment of prostate cancer: a preliminary retrospective study of 16 patients and a review of the literature.