Molecular hydrogen suppresses glioblastoma growth via inducing the glioma stem-like cell differentiation

Hydrogen: A Rising Star in Gas Medicine as a Mitochondria-Targeting Nutrient via Activating Keap1-Nrf2 Antioxidant System

The gas molecules O2, NO, H2S, CO, and CH4, have been increasingly used for medical purposes. Other than these gas molecules, H2 is the smallest diatomic molecule in nature and has become a rising star in gas medicine in the past few decades. As a non-toxic and easily accessible gas, H2 has shown preventive and therapeutic effects on various diseases of the respiratory, cardiovascular, central nervous system, and other systems, but the mechanisms are still unclear and even controversial, especially the mechanism of H2 as a selective radical scavenger. Mitochondria are the main organelles regulating energy metabolism in living organisms as well as the main organelle of reactive oxygen species' generation and targeting. We propose that the protective role of H2 may be mainly dependent on its unique ability to penetrate every aspect of cells to regulate mitochondrial homeostasis by activating the Keap1-Nrf2 phase II antioxidant system rather than its direct free radical scavenging activity. In this review, we summarize the protective effects and focus on the mechanism of H2 as a mitochondria-targeting nutrient by activating the Keap1-Nrf2 system in different disease models. In addition, we wish to provide a more rational theoretical support for the medical applications of hydrogen.

Antitumoral Activity of Molecular Hydrogen and Proton in the Treatment of Glioblastoma: An Atypical Pharmacology?

Antioxidants in cancer therapy have been a hot topic in the medical field for 20 years. Antioxidants are able to reduce the risk of cancer formation by neutralizing free radicals. Protons (H+) and molecular hydrogen (H2) interact in the cell and are essential in a wide variety of processes. The antioxidant, anti-inflammatory, and antiapoptotic effects of H2 have been studied in numerous experimental and clinical studies. Experimental data indicate that H2 is an antitumor agent in the treatment of glioblastoma (GBM). In vivo H2 inhalation could suppress the growth of GBM tumors, thereby extending the survival of mice with GBM. The sphere-forming ability of glioma cells was suppressed by hydrogen treatment. In addition, H2 treatment also suppressed the migration, invasion, and colony-forming ability of glioma cells. Proton therapy and proton beam radiotherapy offer some advantages over other modern conformal photon-based therapies when used in the treatment of central nervous system malignancies.

Molecular Hydrogen: From Molecular Effects to Stem Cells Management and Tissue Regeneration

It is known that molecular hydrogen is a relatively stable, ubiquitous gas that is a minor component of the atmosphere. At the same time, in recent decades molecular hydrogen has been shown to have diverse biological effects. By the end of 2022, more than 2000 articles have been published in the field of hydrogen medicine, many of which are original studies. Despite the existence of several review articles on the biology of molecular hydrogen, many aspects of the research direction remain unsystematic. Therefore, the purpose of this review was to systematize ideas about the nature, characteristics, and mechanisms of the influence of molecular hydrogen on various types of cells, including stem cells. The historical aspects of the discovery of the biological activity of molecular hydrogen are presented. The ways of administering molecular hydrogen into the body are described. The molecular, cellular, tissue, and systemic effects of hydrogen are also reviewed. Specifically, the effect of hydrogen on various types of cells, including stem cells, is addressed. The existing literature indicates that the molecular and cellular effects of hydrogen qualify it to be a potentially effective agent in regenerative medicine.

Intelligent microneedle patch with prolonged local release of hydrogen and magnesium ions for diabetic wound healing

Diabetes mellitus, an epidemic with a rapidly increasing number of patients, always leads to delayed wound healing associated with consistent pro-inflammatory M1 polarization, decreased angiogenesis and increased reactive oxygen species (ROS) in the microenvironment. Herein, a poly (lactic-co-glycolic acid) (PLGA)-based microneedle patch loaded with magnesium hydride (MgH₂) (MN-MgH₂) is manufactured for defeating diabetic wounds. The application of microneedle patch contributes to the transdermal delivery and the prolonged release of MgH₂ that can generate hydrogen (H₂) and magnesium ions (Mg²⁺) after reaction with body fluids. The released H₂ reduces the production of ROS, transforming the pathological microenvironment induced by diabetes mellitus. Meanwhile, the released Mg²⁺ promotes the polarization of pro-healing M2 macrophages. Consequently, cell proliferation and migration are improved, and angiogenesis and tissue regeneration are enhanced. Such intelligent microneedle patch provides a novel way for accelerating wound healing through steadily preserving and releasing of H₂ and Mg²⁺ locally and sustainably.

Mg-based materials diminish tumor spreading and cancer metastases

Cancer metastases are the most common causes of cancer-related deaths. The formation of secondary tumors at different sites in the human body can impair multiple organ function and dramatically decrease the survival of the patients. In this stage, it is difficulty to treat tumor growth and spreading due to arising therapy resistances. Therefore, it is important to prevent cancer metastases and to increase subsequent cancer therapy success. Cancer metastases are conventionally treated with radiation or chemotherapy. However, these treatments elicit lots of side effects, wherefore novel local treatment approaches are currently discussed. Recent studies already showed anticancer activity of specially designed degradable magnesium (Mg) alloys by reducing the cancer cell proliferation. In this work, we investigated the impact of these Mg-based materials on different steps of the metastatic cascade including cancer cell migration, invasion, and cancer-induced angiogenesis. Both, Mg and Mg–6Ag reduced cell migration and invasion of osteosarcoma cells in coculture with fibroblasts. Furthermore, the Mg-based materials used in this study diminished the cancer-induced angiogenesis. Endothelial cells incubated with conditioned media obtained from these Mg and Mg–6Ag showed a reduced cell layer permeability, a reduced proliferation and inhibited cell migration. The tube formation as a last step of angiogenesis was stimulated with the presence of Mg under normoxia and diminished under hypoxia.

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Magnesium (Mg)-based material degradation decrease cell migration and invasion of an osteosarcoma coculture.

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Mg-based material degradation products reduce cancer-induced angiogenesis at an early stage.

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These materials may reduce secondary tumor formation and metastases.

Overexpression of carnitine palmitoyltransferase 1A promotes mitochondrial fusion and differentiation of glioblastoma stem cells

Glioma stem cells (GSCs) are self-renewing tumor cells with multi-lineage differentiation potential and the capacity of construct glioblastoma (GBM) heterogenicity. Mitochondrial morphology is associated with the metabolic plasticity of GBM cells. Previous studies have revealed distinct mitochondrial morphologies and metabolic phenotypes between GSCs and non-stem tumor cells (NSTCs), whereas the molecules regulating mitochondrial dynamics in GBM cells are largely unknown. Herein, we report that carnitine palmitoyltransferase 1A (CPT1A) is preferentially expressed in NSTCs, and governs mitochondrial dynamics and GSC differentiation. Expressions of CPT1A and GSC marker CD133 were mutually exclusive in human GBMs. Overexpression of CPT1A inhibited GSC self-renewal but promoted mitochondrial fusion. In contrast, disruption of CPT1A in NSTCs promoted mitochondrial fission and reprogrammed NSTCs toward GSC feature. Mechanistically, CPT1A overexpression increased the phosphorylation of dynamin-related protein 1 at Ser-637 to promote mitochondrial fusion. In vivo, CPT1A overexpression decreased the percentage of GSCs, impaired GSC-derived xenograft growth and prolonged tumor-bearing mice survival. Our work identified CPT1A as a critical regulator of mitochondrial dynamics and GSC differentiation, indicating that CPT1A could be developed as a molecular target for GBM cell-differentiation strategy.

Molecular Hydrogen Inhibits Colorectal Cancer Growth via the AKT/SCD1 Signaling Pathway

Objective

Molecular hydrogen (H₂) has been considered a potential therapeutic target in many cancers. Therefore, we sought to assess the potential effect of H₂ on colorectal cancer (CRC) in this study.

Methods

The effect of H₂ on the proliferation and apoptosis of RKO, SW480, and HCT116 CRC cell lines was assayed by CCK-8, colony formation, and flow cytometry assays. The effect of H₂ on tumor growth was observed in xenograft implantation models (inhalation of 67% hydrogen two hours per day). Western blot and immunohistochemistry analyses were performed to examine the expression of p-PI3K, PI3K, AKT, pAKT, and SCD1 in CRC cell lines and xenograft mouse models. The expression of SCD1 in 491 formalin-fixed, paraffin-embedded CRC specimens was investigated with immunochemistry. The relationship between SCD1 status and clinicopathological characteristics and outcomes was determined.

Results

Hydrogen treatment suppressed the proliferation of CRC cell lines independent of apoptosis, and the cell lines showed different responses to different doses of H₂. Hydrogen also elicited a potent antitumor effect to reduce CRC tumor volume and weight in vivo. Western blot and IHC staining demonstrated that H₂ inhibits CRC cell proliferation by decreasing pAKT/SCD1 levels, and the inhibition of cell proliferation induced by H₂ was reversed by the AKT activator SC79. IHC showed that SCD1 expression was significantly higher in CRC tissues than in normal epithelial tissues (70.3% vs. 29.7%, p = 0.02) and was correlated with a more advanced TNM stage (III vs. I + II; 75.9% vs. 66.3%, p = 0.02), lymph node metastasis (with vs. without; 75.9% vs. 66.3%, p = 0.02), and patients without a family history of CRC (78.7% vs. 62.1%, p = 0.047).

Conclusion

This study demonstrates that high concentrations of H₂ exert an inhibitory effect on CRC by inhibiting the pAKT/SCD1 pathway. Further studies are warranted for clinical evaluation of H₂ as SCD1 inhibitor to target CRC.

Molecular Hydrogen Enhances Proliferation of Cancer Cells That Exhibit Potent Mitochondrial Unfolded Protein Response

Molecular hydrogen ameliorates pathological states in a variety of human diseases, animal models, and cell models, but the effects of hydrogen on cancer have been rarely reported. In addition, the molecular mechanisms underlying the effects of hydrogen remain mostly unelucidated. We found that hydrogen enhances proliferation of four out of seven human cancer cell lines (the responders). The proliferation-promoting effects were not correlated with basal levels of cellular reactive oxygen species. Expression profiling of the seven cells showed that the responders have higher gene expression of mitochondrial electron transport chain (ETC) molecules than the non-responders. In addition, the responders have higher mitochondrial mass, higher mitochondrial superoxide, higher mitochondrial membrane potential, and higher mitochondrial spare respiratory capacity than the non-responders. In the responders, hydrogen provoked mitochondrial unfolded protein response (mtUPR). Suppression of cell proliferation by rotenone, an inhibitor of mitochondrial ETC complex I, was rescued by hydrogen in the responders. Hydrogen triggers mtUPR and induces cell proliferation in cancer cells that have high basal and spare mitochondrial ETC activities.

Molecular hydrogen is a promising therapeutic agent for pulmonary disease

Molecular hydrogen exerts biological effects on nearly all organs. It has anti-oxidative, anti-inflammatory, and anti-aging effects and contributes to the regulation of autophagy and cell death. As the primary organ for gas exchange, the lungs are constantly exposed to various harmful environmental irritants. Short- or long-term exposure to these harmful substances often results in lung injury, causing respiratory and lung diseases. Acute and chronic respiratory diseases have high rates of morbidity and mortality and have become a major public health concern worldwide. For example, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. An increasing number of studies have revealed that hydrogen may protect the lungs from diverse diseases, including acute lung injury, chronic obstructive pulmonary disease, asthma, lung cancer, pulmonary arterial hypertension, and pulmonary fibrosis. In this review, we highlight the multiple functions of hydrogen and the mechanisms underlying its protective effects in various lung diseases, with a focus on its roles in disease pathogenesis and clinical significance.

Molecular Hydrogen as a Novel Antitumor Agent: Possible Mechanisms Underlying Gene Expression

While many antitumor drugs have yielded unsatisfactory therapeutic results, drugs are one of the most prevalent therapeutic measures for the treatment of cancer. The development of cancer largely results from mutations in nuclear DNA, as well as from those in mitochondrial DNA (mtDNA). Molecular hydrogen (H₂), an inert molecule, can scavenge hydroxyl radicals (·OH), which are known to be the strongest oxidizing reactive oxygen species (ROS) in the body that causes these DNA mutations. It has been reported that H₂ has no side effects, unlike conventional antitumor drugs, and that it is effective against many diseases caused by oxidative stress and chronic inflammation. Recently, there has been an increasing number of papers on the efficacy of H₂ against cancer and its effects in mitigating the side effects of cancer treatment. In this review, we demonstrate the efficacy and safety of H₂ as a novel antitumor agent and show that its mechanisms may not only involve the direct scavenging of ·OH, but also other indirect biological defense mechanisms via the regulation of gene expression.

Anti-tumor effects of Solanum nigrum L. extraction on C6 high-grade glioma

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum nigrum L. (SN) is a traditional Chinese medicine with anti-tumor effects, has been used in cancer for centuries, but the role on high-grade gliomas (HGG) is not clear.

AIM OF THE STUDY

This work was to investigate the anti-tumor effects of SN extract on rat C6 glioma in vitro and in vivo, providing a new medium for the treatment of HGG.

MATERIALS AND METHODS

After identification and quality inspection of SN medicinal materials by HPLC-MS/MS and HPLC, CCK8 and colony formation assay were conducted to study the effects of SN on vitality and proliferation of C6 cells. Cell morphology was evaluated by HE staining, and flow cytometry was used for apoptosis analysis. The effects on cell migration and invasion were determined by transwell and wound healing assay. Western blot was used to further investigate the influence of SN on migration, invasion and apoptosis of tumor cells. In addition, the rat intracranial transplanted tumor model was used to evaluate the effects of SN on growth and infiltration of tumor and proliferation of transplanted tumor cells.

RESULTS

SN extract suppressed the viability of C6 cells in a dose-dependent manner. The extract attenuated cell cloning, migration and invasion, and induced cell Annexin V+ PI+ late-stage apoptosis. Besides, SN induced the expression of apoptotic proteins including Bax and Cleaved Caspase-3, downregulated anti-apoptotic protein Bcl-2, and decreased the level of migratory proteins MMP-2 and MMP-9. Moreover, SN reduced the growth and infiltration of C6 glioma tissue and suppressed the proliferation of tumor cells in rat brain.

CONCLUSIONS

SN extract has significant inhibitory activity on the growth and invasion of C6 HGG in vivo and in vitro.

Inflammatory tumor microenvironment responsive neutrophil exosomes-based drug delivery system for targeted glioma therapy

Clinical treatment of malignant glioma remains a major challenge due to high infiltrative growth and chemotherapeutic resistance of tumors and the presence of the blood brain barrier (BBB). Advanced nanoplatforms that can efficiently cross the BBB and target to brain tumor are urgently needed. Encouraged by the intrinsic inflammatory chemotaxis and excellent BBB-crossing capability of neutrophils, a bioinspired neutrophil-exosomes (NEs-Exos) system for delivering loaded doxorubicin (DOX) drug for glioma treatment is proposed and systematically investigated. In vivo zebrafish and C6-Luc glioma-bearing mice models show that NEs-Exos carrying the drug rapidly penetrate the BBB and migrate into the brain. Additionally, a transwell BBB model and mouse brain inflammatory study show that NEs-Exos can respond chemotactically to inflammatory stimuli and target infiltrating tumor cells in inflamed brain tumors. Moreover, intravenous injection of NEs-Exos/DOX efficiently suppress tumor growth and prolong survival time in a glioma mouse model. On the basis of these results, NEs-Exos are confirmed to have neutrophil-like chemotactic function and BBB penetration. This novel NEs-Exos/DOX delivery platform represents a promising chemotherapeutic approach for clinical treatment of glioma and other solid tumor or brain diseases.

Neuroprotective Effects of Molecular Hydrogen: A Critical Review

Molecular hydrogen (H2) is a physiologically inert gas. However, during the last 10 years, increasing evidence has revealed its biological functions under pathological conditions. More specifically, H2 has protective effects against a variety of diseases, particularly nervous system disorders, which include ischemia/reperfusion injury, traumatic injury, subarachnoid hemorrhage, neuropathic pain, neurodegenerative diseases, cognitive dysfunction induced by surgery and anesthesia, anxiety, and depression. In addition, H2 plays protective roles mainly through anti-oxidation, anti-inflammation, anti-apoptosis, the regulation of autophagy, and preservation of mitochondrial function and the blood-brain barrier. Further, H2 is easy to use and has neuroprotective effects with no major side-effects, indicating that H2 administration is a potential therapeutic strategy in clinical settings. Here we summarize the H2 donors and their pharmacokinetics. Meanwhile, we review the effectiveness and safety of H2 in the treatment of various nervous system diseases based on preclinical and clinical studies, leading to the conclusion that H2 can be a simple and effective clinical therapy for CNS diseases such as ischemia-reperfusion brain injury, Parkinson's disease, and diseases characterized by cognitive dysfunction. The potential mechanisms involved in the neuroprotective effect of H2 are also analyzed.

Antitumor Activity of Protons and Molecular Hydrogen: Underlying Mechanisms

Simple Summary

Protons (H⁺) and molecular hydrogen (H₂) in the cell are critical in a wide variety of processes. New cancer treatment uses H₂, a biologically inactive gas. H₂ can rapidly penetrate cell membranes and reach subcellular components to protect nuclear DNA and mitochondria. H₂ reduces oxidative stress, exerts anti-inflammatory effects, and acts as a modulator of apoptosis. Exogenous H₂ is a protective therapy that can be used in cancer. Cyclotrons and synchrotrons are currently used to produce protons. Proton beam radiotherapy (PBT) offers great promise for the treatment of a wide variety of cancers. H₂ and different types of H₂ donors may represent a novel therapeutic strategy in cancer treatment.

Abstract

Understanding the structure and dynamics of the various hydrogen forms has been a subject of numerous studies. Protons (H⁺) and molecular hydrogen (H₂) in the cell are critical in a wide variety of processes. A new cancer treatment uses H₂, a biologically inactive gas. Due to its small molecular weight, H₂ can rapidly penetrate cell membranes and reach subcellular components to protect nuclear DNA and mitochondria. H₂ reduces oxidative stress, exerts anti-inflammatory effects, and acts as a modulator of apoptosis. Exogenous H₂, administered by inhalation, drinking H₂-rich water, or injecting H₂-rich saline solution, is a protective therapy that can be used in multiple diseases, including cancer. In particle therapy, cyclotrons and synchrotrons are the accelerators currently used to produce protons. Proton beam radiotherapy (PBT) offers great promise for the treatment of a wide variety of cancers due to the sharp decrease in the dose of radiation at a defined point. In these conditions, H₂ and different types of H₂ donors may represent a novel therapeutic strategy in cancer treatment.

A narrative review of hydrogen-oxygen mixture for medical purpose and the inhaler thereof

Recent development regarding mixture of H₂ (concentration of ~66%) with O₂ (concentration of ~34%) for medical purpose, such as treatment of coronavirus disease-19 (COVID-19) patients, is introduced. Furthermore, the design principles of a hydrogen inhaler which generates mixture of hydrogen (~66%) with oxygen (~34%) for medical purpose are proposed. With the installation of the liquid blocking module and flame arresters, the air pathway of the hydrogen inhaler is divided by multiple isolation zones to prevent any unexpected explosion propagating from one zone to the other. An integrated filtering/cycling module is utilized to purify the impurity, and cool down the temperature of the electrolytic module to reduce the risk of the explosion. Moreover, a nebulizer is provided to selectively atomize the water into vapor which is then mixed with the filtered hydrogen-oxygen mix gas, such that the static electricity of a substance hardly occurs to reduce the risk of the explosion. Furthermore, hydrogen concentration detector is installed to reduce the risk of hydrogen leakage. Result shows that the hydrogen inhaler implementing the aforesaid design rules could effectively inhibit the explosion, even ignition at the outset of the hydrogen inhaler which outputs hydrogen-oxygen gas (approximately 66% hydrogen: 34% oxygen).

A narrative review of hydrogen oncology: from real world survey to real world evidence

The use of hydrogen for cancer control has made great progress in cytology and animal experiments. With the increasing number of hydrogen products on the market, larger numbers of advanced cancer patients have participated in clinical trials or received treatment at home after purchase. Our study reported a real-world survey from 82 patients with good cancer control using hydrogen products, including real world evidence from patients who received ineffective traditional treatment, patients who received traditional treatment that failed, or patients who refused traditional treatment. Two typical cases were reported herein. Subsequently, we included studies on the mechanism of hydrogen oncology. The mechanism of cancer control using hydrogen includes the inhibition of tumor cells and the activation of exhausted lymphocytes. Large-scale real world evidence has shown clinical value, and yet remains to be further developed and researched.

Hydrogen: A Novel Option in Human Disease Treatment

H₂ has shown anti-inflammatory and antioxidant ability in many clinical trials, and its application is recommended in the latest Chinese novel coronavirus pneumonia (NCP) treatment guidelines. Clinical experiments have revealed the surprising finding that H₂ gas may protect the lungs and extrapulmonary organs from pathological stimuli in NCP patients. The potential mechanisms underlying the action of H₂ gas are not clear. H₂ gas may regulate the anti-inflammatory and antioxidant activity, mitochondrial energy metabolism, endoplasmic reticulum stress, the immune system, and cell death (apoptosis, autophagy, pyroptosis, ferroptosis, and circadian clock, among others) and has therapeutic potential for many systemic diseases. This paper reviews the basic research and the latest clinical applications of H₂ gas in multiorgan system diseases to establish strategies for the clinical treatment for various diseases.

Biological effects of selective COX-2 inhibitor NS398 on human glioblastoma cell lines

Background

Cyclooxygenase-2 (COX-2), an inflammation-associated enzyme, has been implicated in tumorigenesis and progression of glioblastoma (GBM). The poor survival of GBM was mainly associated with the presence of glioma stem cells (GSC) and the markedly inflammatory microenvironment. To further explore the involvement of COX-2 in glioma biology, the effects of NS398, a selective COX-2 inhibitor, were evaluated on GSC derived from COX-2 expressing GBM cell lines, i.e., U87MG and T98G, in terms of neurospheres' growth, autophagy, and extracellular vesicle (EV) release.

Methods

Neurospheres' growth and morphology were evaluated by optical and scanning electron microscopy. Autophagy was measured by staining acidic vesicular organelles. Extracellular vesicles (EV), released from neurospheres, were analyzed by transmission electron microscopy. The autophagic proteins Beclin-1 and LC3B, as well as the EV markers CD63 and CD81, were analyzed by western blotting. The scratch assay test was used to evaluate the NS398 influence on GBM cell migration.

Results

Both cell lines were strongly influenced by NS398 exposure, as showed by morphological changes, reduced growth rate, and appearance of autophagy. Furthermore, the inhibitor led to a functional change of EV released by neurospheres. Indeed, EV secreted by NS398-treated GSC, but not those from control cells, were able to significantly inhibit adherent U87MG and T98G cell migration and induced autophagy in recipient cells, thus leading to effects quite similar to those directly caused by NS398 in the same cells.

Conclusion

Despite the intrinsic diversity and individual genetic features of U87MG and T98G, comparable effects were exerted by the COX-2 inhibitor NS398 on both GBM cell lines. Overall, our findings support the crucial role of the inflammatory-associated COX-2/PGE2 system in glioma and glioma stem cell biology.

A Gallbladder Carcinoma Patient With Pseudo-Progressive Remission After Hydrogen Inhalation

Background

Hydrogen therapy has been reported to convert exhausted programmed cell death receptor (PD-1)+CD8+ T cells to PD-1-CD8+ T cells, in advanced colorectal cancer patients, which is associated with significantly prolonged survival.

Case presentation

A 72-year-old female patient presented with metastatic gallbladder cancer and underwent symptomatic treatment combined with hydrogen therapy. The tumors were initially enlarged and displayed increased tumor marker expression following hydrogen inhalation therapy, after which they continued to remit, similar to the pseudo-progression that occurs after anti-PD-1 treatment. During one month of hydrogen therapy, the patient's gallbladder and liver tumors continued to progress, and intestinal obstruction occurred. The intestinal obstruction was gradually relieved after symptomatic treatment, and the metastases in the abdominal cavity gradually decreased in size, anemia and hypoalbuminemia were corrected, and both the lymphocyte and tumor marker levels returned to normal. The patient was able to resume normal life two and a half months after hydrogen inhalation and survived over 10 months.

Conclusion

This is the first report of pseudo-progression followed by sustained remission after hydrogen inhalation. This phenomenon is similar to the pseudo-progression-remission pattern that occurs following PD-1 antibody treatment. These findings suggest that hydrogen may have an inhibitory effect on PD-1 expression.

Hydrogen Gas in Cancer Treatment

Gas signaling molecules (GSMs), composed of oxygen, carbon monoxide, nitric oxide, hydrogen sulfide, etc., play critical roles in regulating signal transduction and cellular homeostasis. Interestingly, through various administrations, these molecules also exhibit potential in cancer treatment. Recently, hydrogen gas (formula: H₂) emerges as another GSM which possesses multiple bioactivities, including anti-inflammation, anti-reactive oxygen species, and anti-cancer. Growing evidence has shown that hydrogen gas can either alleviate the side effects caused by conventional chemotherapeutics, or suppress the growth of cancer cells and xenograft tumor, suggesting its broad potent application in clinical therapy. In the current review, we summarize these studies and discuss the underlying mechanisms. The application of hydrogen gas in cancer treatment is still in its nascent stage, further mechanistic study and the development of portable instruments are warranted.