GrowthKyoto – Qahwa World
A Japanese research team has identified the molecular mechanism by which caffeic acid, a polyphenol found in coffee, suppresses the growth of colorectal cancer (CRC) cells.
This discovery, published in Scientific Reports on March 5, 2026, provides a potential scientific basis for epidemiological studies that link regular coffee consumption to a reduced risk of colorectal cancer.
The Molecular Mechanism: Targeting the RPS5-Cyclin D1 Axis While previous research suggested a link between coffee and cancer prevention, the specific components and their biological functions remained unclear.
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Researchers from Kyoto Prefectural University of Medicine and Kansai Medical University Hospital focused on caffeic acid, which is produced when chlorogenic acid (abundant in coffee) is hydrolyzed in the intestines.
Key findings from the study include: Direct Binding to RPS5: Using nano-magnetic beads and mass spectrometry, the team identified ribosomal protein S5 (RPS5) as a direct binding target of caffeic acid. High expression of RPS5 is known to be associated with poor prognosis in colorectal cancer patients.
Inducing G1 Cell Cycle Arrest: The research demonstrated that caffeic acid blocks the function of RPS5, which in turn halts the cell cycle of cancer cells at the G1 phase, preventing them from copying their DNA and proliferating.
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Post-Transcriptional Regulation of Cyclin D1: Both the addition of caffeic acid and the suppression of RPS5 reduced the levels of cyclin D1, a protein critical for driving the cell growth cycle. The study suggests that RPS5 regulates cyclin D1 by controlling the stability of its messenger RNA (mRNA) rather than its promoter activity.
Future Therapeutic Potential Dr. Motoki Watanabe, the lead researcher, stated that these findings reveal a previously unrecognized RPS5-cyclin D1 axis targeted by caffeic acid. This insight could lead to the development of new cancer prevention strategies and treatments, such as optimized derivatives of caffeic acid that more effectively target RPS5.
Important Considerations The researchers noted that this was basic research conducted primarily on cell cultures. They cautioned that the concentrations of caffeic acid required for these effects in a laboratory setting are higher than what is typically achieved through normal coffee consumption. Additionally, since coffee contains other components like caffeine and may not suit everyone’s constitution, excessive consumption is not recommended.
