Depression-Induced Neuropeptide Y Secretion Promotes Prostate Cancer Growth by Recruiting Myeloid Cells.

Purpose: Psychologic depression has been shown to dysregulate the immune system and promote tumor progression. The aim of this study is to investigate how psychologic depression alters the immune profiles in prostate cancer.

Experimental Design: We used a murine model of depression in Myc-CaP tumor-bearing immunocompetent FVB mice and Hi-myc mice presenting with spontaneous prostate cancer. Transwell migration and coculture assays were used to evaluate myeloid cell trafficking and cytokine profile changes evoked by Myc-CaP cells that had been treated with norepinephrine (NE), a major elevated neurotransmitter in depression. Chemoattractant, which correlated with immune cell infiltration, was screened by RNA-seq. The chemoattractant and immune cell infiltration were further confirmed using clinical samples of patients with prostate cancer with a high score of psychologic depression.

Results: Psychologic depression predominantly promoted tumor-associated macrophage (TAM) intratumor infiltrations, which resulted from spleen and circulating monocytic myeloid-derived suppressor cell mobilization. Neuropeptide Y (NPY) released from NE-treated Myc-CaP cells promotes macrophage trafficking and IL6 releasing, which activates STAT3 signaling pathway in prostate cancer cells. Clinical specimens from patients with prostate cancer with higher score of depression revealed higher CD68 TAM infiltration and stronger NPY and IL6 expression.

Conclusions: Depression promotes myeloid cell infiltration and increases IL6 levels by a sympathetic-NPY signal. Sympathetic-NPY inhibition may be a promising strategy for patients with prostate cancer with high score of psychologic depression..