Abstract
Gas signaling molecules, including carbon monoxide (CO), nitric oxide (NO), and hydrogen sulfide (H(2)S), have been shown to have cancer therapeutic potential, pointing to a new direction for cancer treatment. In recent years, a series of studies have confirmed that hydrogen (H(2)), a weakly reductive gas, also has therapeutic effects on various cancers and can mitigate oxidative stress caused by radiation and chemotherapy, reducing tissue damage and immunosuppression to improve prognosis. Meanwhile, H(2) also has immunomodulatory effects, inhibiting T cell exhaustion and enhancing T cell anti-tumor function. It is worth noting that human intestinal flora can produce large amounts of H(2) daily, which becomes a natural barrier to maintaining the body's resistance to diseases such as tumors. Although the potential anti-tumor mechanisms of H(2) are still to be investigated, previous studies have shown that H(2) can selectively scavenge highly toxic reactive oxygen species (ROS) and inhibit various ROS-dependent signaling pathways in cancer cells, thus inhibiting cancer cell proliferation and metastasis. The ROS scavenging ability of H(2) may also be the underlying mechanism of its immunomodulatory function. In this paper, we review the significance of H(2) produced by intestinal flora on the immune homeostasis of the body, the role of H(2) in cancer therapy and the underlying mechanisms, and the specific application of H(2) to provide new ideas for the comprehensive treatment of cancer patients.