One of the most well-researched natural remedies available, curcumin has been shown in studies to promote weight loss and calm inflammation, among other beneficial effects. And now, a team of German scientists from the Ludwig Maximilian University of Munich (LMU) has discovered that this extract of the popular curry spice turmeric (Curcuma longa) may be useful for treating colon cancer. Their research, which was published in the journal Nature, has identified a pathway by which curcumin can suppress the metastasis of colorectal cancer cells.
The study was inspired by the fact that in over half of all cases of colorectal cancer (CRC), an important protective mechanism in cells is inactivated by mutations—the tumor suppressor gene p53. The product of this gene induces a molecule called miR-34, which plays a critical role in tumor suppression. “There were already indications in the literature that curcumin can induce miR-34,” said study leader Heiko Hermeking, a professor of experimental and molecular pathology at LMU, “but there was no systematic investigation of the phenomenon before now. Moreover, it was unclear what mechanism could be behind it.”
First, Hermeking’s team treated genetically modified human colorectal cancer cell lines and found that curcumin increases the production of reactive oxygen species (ROS) in tumor cells. These ROS activate a signaling pathway that leads to the production of miR-34, which then induces premature aging of the tumor cells and programmed cell death. “Furthermore, the ability of tumor cells to migrate and invade into surrounding tissue is impaired,” said Hermeking.
Next, the team treated mice with colorectal cancer with curcumin to further study the effects. “We were also able to confirm in our mouse model that the curcumin-induced expression of miR-34 suppresses the metastasis of colorectal cancer cells into the lung,” said Hermeking. In addition, curcumin made tumor cells more sensitive to the chemotherapeutic substance 5-FU, enhancing its therapeutic benefit.
According to the authors, the results of the study could give rise to interesting approaches for new colorectal cancer therapies, which would need to be examined in further studies.
“The addition of curcumin to cancer therapy is of great interest, since a phase I clinical study showed that [it] is safe and tolerable in patients with metastatic CRC at doses up to 2 grams daily,” the team wrote in its conclusion. “Moreover, oral consumption of up to 3,600 mg curcumin leads to curcumin concentrations in human colorectal mucosa which are in the range of the concentration used in this study. In the future, the findings presented here may be exploited for the development of therapeutic approaches that aim at restoring the tumor suppressive function of the…miR-34 pathway.”