Oral Lentinula edodes mycelia extract enhances the antitumor effect of radiotherapy via gut-associated activation of dendritic and cytotoxic T cells

Everyday Food, High-Tech Cancer Care

What if something derived from a familiar food—the shiitake mushroom—could quietly train the immune system to help modern cancer treatments work better? This study explores how an extract made from the thread-like roots (mycelia) of Lentinula edodes, the shiitake mushroom, may boost the effects of radiation therapy by working through the gut and awakening key immune cells that attack tumors.

How a Mushroom Extract Meets the Immune System

The researchers focused on a hot-water extract called L.E.M., which can be mixed into regular chow and eaten by mice. Earlier work showed that L.E.M. can shrink tumors by stimulating T cells, a type of white blood cell that recognizes and kills cancer cells. But it was not clear how a substance taken by mouth could trigger such widespread immune effects. Because much of the body’s immune surveillance begins in the intestine, the team asked whether L.E.M. first acts in gut-associated lymphoid tissue—special immune organs that constantly sample what passes through the intestines.

Gut Gatekeepers Get Switched On

The scientists fed tumor-bearing mice either normal chow or chow containing 2% L.E.M. and examined immune cells in the mesenteric lymph nodes, which drain the intestines. There they found that dendritic cells—“sentinel” cells that collect foreign material and show it to T cells—looked more mature and activated in L.E.M.-fed animals. In particular, a subset called CD103+ dendritic cells, known to carry information from the gut lining to the lymph nodes, was clearly increased. These changes suggest that L.E.M. turns the gut into a more alert immune training ground, better prepared to launch killer T cells against tumor-related targets.

From Gut Signals to Body-Wide Defenses

The team then looked beyond the gut to see if this local activation spread through the body. In the spleen, another key immune organ, mice given L.E.M. showed more dendritic cells that are specialized in activating cytotoxic, or “killer,” T cells. When radiation therapy was added—focused X-rays aimed at the tumor—this effect became stronger. Radiation itself causes tumor cells to die and spill their contents, effectively waving a red flag to the immune system. In mice that had been primed with L.E.M., this signal was amplified: more memory-type CD8+ T cells appeared in the blood, and within the tumors the number of antigen-specific killer T cells rose sharply compared with radiation alone.

Real Impact on Tumor Growth

Immune changes matter most if they translate into better tumor control, and here the results were striking. Mice that received L.E.M. alone showed slower tumor growth than untreated animals, indicating that the extract has its own antitumor power. Radiation on its own also slowed tumor expansion, as expected. But the combination of oral L.E.M. plus radiation kept tumors significantly smaller for longer than radiation by itself. In effect, L.E.M. acted as an immune “primer”: it did not flood the body with constant high levels of T cells, but it prepared dendritic cells and T cells to respond more vigorously when radiation released tumor material.

What This Could Mean for Patients

To a layperson, the take-home message is that an orally taken mushroom-derived extract can tune the gut immune system in a way that helps the body make better use of radiation therapy. By waking up sentinel cells in the intestine and spleen, L.E.M. sets the stage for more powerful and longer-lasting killer T cell responses once radiation exposes the tumor. While this work was done in a specific mouse melanoma model and more studies are needed in other cancers and in humans, it points to a future in which simple, low-burden oral immune boosters are paired with standard treatments to make them safer, stronger, and more durable.

Citation: Takeshima, T., Wang, Y. & Hasegawa, S. Oral Lentinula edodes mycelia extract enhances the antitumor effect of radiotherapy via gut-associated activation of dendritic and cytotoxic T cells. Sci Rep 16, 5290 (2026). https://doi.org/10.1038/s41598-026-35752-7

Keywords: cancer immunotherapy, radiation therapy, shiitake mushroom extract, gut immune system, T cells