Arrhythmic expression signatures of circadian clock-associated transcription factors and chronic circadian disruption contribute to advanced prostate cancer growth.

Disruption of circadian rhythms due to night-shift work is classified as a probable carcinogen for cancers of the breast, prostate, and colorectum by the International Agency for Research on Cancer. Global epidemiological studies link chronic circadian clock disruption to increased risk of prostate cancer via hormone and metabolic dysregulation. This study investigated and compared the circadian expression patterns of core-circadian controlled genes (CCCGs) and nuclear receptors (NRs) under a normal 12-h light/dark cycle in normal mouse prostate and advanced androgen-insensitive prostate tumors derived from a transgenic mouse model of prostate adenocarcinoma (TGMAP). Our results showed that a total of eight CCCGs and 22 NRs exhibited rhythmic oscillations in the normal mouse prostate. In contrast, the rhythmic expressions of CCCGs and NRs were significantly disrupted in TGMAP prostate tumors, with a concurrent loss of androgen receptor expression. Circadian administration of cisplatin at a specific morning time point (chrono-chemotherapy), as applied in TGMAP tumor-bearing mice, demonstrated optimal antitumor efficacy, which correlated with the circadian rhythmic expression of DNA damage repair genes. Finally, we showed that chronic jet-lag conditions could promote the oncogenic growth of hormone-sensitive VCaP-derived xenograft tumors, with a correlation to elevated serum androgen levels and increased expression of enzyme genes involved in intratumoral androgen biosynthesis. Together, this study demonstrated that advanced prostate tumors exhibited dysregulated circadian transcriptional networks, as shown by their disrupted expression of CCCGs and NRs. The potential therapeutic application of chrono-chemotherapy in advanced prostate cancer management and the disruption of circadian rhythms under chronic jet-lag conditions could enhance prostate cancer growth.