Patrick brought this up about a year ago:
Melatonin Inhibits Androgen Receptor Splice Variant-7 (AR-V7)-Induced Nuclear Factor-Kappa B (NF-κB) Activation and NF-κB Activator-Induced AR-V7 Expression in Prostate Cancer Cells: Potential Implications for the Use of Melatonin in Castration-Resistant Prostate Cancer (CRPC) Therapy
Another interesting article in the European Journal of Anatomy, although it's a bit dated:
Effect of melatonin on androgen receptor and catalase mRNA
I'm not sure how to interpret this:
Nuclear exclusion of the androgen receptor by melatonin
fwiw, I spoke with an oncologist (not our MO) earlier today and asked about melatonin helping inhibit the AR, and he said it was brought up at an ASCO meeting not too long ago, but no really took it any further. He did say it can't hurt to take it.