CO2 Therapy Use And Cancer - Tumors, Chemotherapy & Radiation Therapy

Transcutaneous carbon dioxide gas therapy
reduces size of metastatic tumors and
enhances the effects of chemotherapy and radiation therapy

Richard Rivers, M.D., Ph.D
Microvascular Physiologist
Johns Hopkins University
Associate Professor
Baltimore, Maryland

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The paper presents the findings from four specific papers, clearly demonstrating that elevated carbon dioxide levels will, by moderating tissue concentrations of HIF (hypoxia-induced factors), ameliorate metastatic tumors and enhance the effectiveness of chemotherapy and radiation therapy on selective malignancies.  

Transcutaneous Carbon Dioxide Induces Mitochondrial Apoptosis and Suppresses Metastasis of Oral Squamous Cell Carcinoma In Vivo

Takeda D, Hasegawa T, Ueha T, Imai Y, Sakakibara A, et al. (2014) Transcutaneous Carbon Dioxide Induces Mitochondrial Apoptos is and Suppresses Metastasis of Oral Squamous Cell Carcinoma In Vivo. PLoS ONE 9(7): e100530. doi:10.1371/journal.pone 0100530

Squamous cell carcinoma (SCC) is a common type of oral cancer. Its growth rate and incidence of spread to other parts of the body through regional lymph nodes is influenced by various factors, including hypoxic conditions.

In this study, the researchers examined the effects of transcutaneous CO(2) on cancer cell death and spreading of cancer. They used human SCC xenografts (cancer cell grafts from a donor). The results showed that transcutaneous CO(2) affects expressions of intracellular messengers (PGC-1a and TFAM and protein levels of cleavage products of caspase-3, caspase-9 and PARP) that relate to cell death. They also showed that transcutaneous CO(2) significantly inhibits SCC tumor growth and affects expressions of factors (HIF-1a, VEGF, MMP-2 and MMP-9) which play essential roles in tumor new blood vessel formation, cancer cell invasion, and spread to other parts of the body.

The experimental model was mice. Male mice aged 7 weeks were maintained under pathogen-free conditions. Cancer cells were injected subcutaneously into the backs of the mice.

Transcutaneous CO(2) was administered. The area of skin around the implanted tumor was moistened. This area was sealed with a polyethylene bag and 100% CO(2) gas was pumped into the bag. Each treatment was performed for 10 minutes, twice a week for two weeks. Control animals were treated similarly with room air replacing the CO(2).

Treatment was started 7 days after cancer cell implantation. Mice were treated with CO(2) twice a week for 3 weeks. Tumor volume and body weight were monitored twice weekly until the end of the treatment. Tumor volume was calculated as previously described according to the formula V=p/66a26b, where a and b represent the shorter and longer diameters of the tumor, respectively.

Data show that transcutaneous CO(2) suppressed tumor growth and cell death and decreased the spread of tumor cells. This happens by decreasing intra-tumoral hypoxia and suppressing metastatic potential with no observable effect in vivo. The findings indicate that transcutaneous CO(2) could be a novel therapeutic tool for treating human SCC. 

Transcutaneous Application of Carbon Dioxide (CO2) Enhances Chemosensitivity by Reducing Hypoxic Conditions
in Human Malignant Fibrous Histiocytoma

ONISHI Y, AKISUE T, KAWAMOTO T, UEHA T, HARA H, TODA M, HARADA R, MINODA M, MORISHITA M, SASAKI R, NISHIDA K, KURODA R and KUROSAKA M. Transcutaneous application of CO2 enhances the antitumor effect of radiation therapy in human malignant fibrous histiocytoma. International Journal of Oncology 45: 732-738, 2014.

Tumor hypoxia is a common feature of various human malignancies. Hypoxia contributes to tumor progression, and is a major cause of tumor resistance to chemotherapy. Hypoxia-inducible factor (HIF)-1 is a key transcription factor in hypoxic responses, and regulates the transcription of genes that are involved in crucial aspects of cancer biology, including angiogenesis, cell survival, and invasion. The aim of this study was to examine the effect of oxygenation by transcutaneous application of CO(2) on the therapeutic efficacy of doxorubicin (DOX) to treat human malignant fibrous histiocytoma (MFH) in vivo.

In this study, a mouse model of human MFH, mice were randomly divided into four groups: control, CO(2), DOX and combination (CO2 + DOX) to examine the effect of transcutaneous application of CO(2) on the hypoxic condition, and to assess the therapeutic effect of combination therapy using transcutaneous CO(2) and DOX treatment in vivo. Carbon dioxide gas was applied to the tumor for 10 minutes, twice a week for two weeks.

Transcutaneous application of CO(2) treatment decreased HIF-1α expression in human MFH tumor tissues, suggesting that the transcutaneous CO(2) treatment reduced the hypoxic conditions. Furthermore, transcutaneous CO(2) treatment alone had an antitumoral effect, and increased the chemotherapeutic effect of DOX on MFH tumor growth in vivo, with no observable effects on body weight.

The findings in this study strongly indicate that transcutaneous CO(2) system has anti-tumor effects and can enhance the chemosensitivity of tumor cells by reducing the local hypoxic conditions.

Transcutaneous Application of Carbon Dioxide (CO2)
Induces Mitochondrial Apoptosis in Human Malignant Fibrous
Histiocytoma In Vivo

Onishi Y, Kawamoto T, Ueha T, Kishimoto K, Hara H, et al. (2012) Transcutaneous Application of Carbon Dioxide (CO 2) Induces Mitochondrial Apoptosis in Human Malignant Fibrous Histiocytoma In Vivo. PLoS ONE 7(11): e49189. doi:10.1371/journal.pone.00049189

Mitochondria play an essential role in cellular energy metabolism and apoptosis. Previous studies have demonstrated that decreased mitochondrial biogenesis is associated with cancer progression. In mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) regulates the activities of multiple nuclear receptors and transcription factors involved in mitochondrial proliferation. In this study, a mouse model of human MFH was used to determine the effect of transcutaneous CO(2)exposure on PGC-1α expression, mitochondrial proliferation and cellular apoptosis. PGC-1α expression was evaluated b y quantitative real-time PCR, while mitochondrial proliferation was assessed by immunofluorescence staining and the relative copy number of mitochondrial DNA (mtDNA) was assessed by real-time PCR. Immunofluorescence staining and DNA fragmentation assays we re used to examine mitochondrial apoptosis. They also evaluated the expression of mitochondrial apoptosis related proteins, such as caspases, cytochorome c and Bax, by immunoblot analysis. They found that the transcutaneous application of CO(2)induces PGC-1α expression, and increases mitochondrial proliferation and apoptosis of tumor cells, significantly reducing tumor volume. Proteins involved in the mitochondrial apoptotic cascade, including caspase 3 and caspase 9, were elevated in CO(2)treated tum ors compared to control. They also observed an enrichment of cytochrome c in the cytoplasmic fraction and Bax protein in the mitochondrial fraction of CO(2) treated tumors, highlighting the involvement of mitochondria in apoptosis. These data indicate that transcutaneous application of CO(2)may represent a novel therapeutic tool in the treatment of human MFH.

Transcutaneous application of Carbon Dioxide (CO2) enhances
the antitumor effect of radiation therapy
in human malignant fibrous histiocytoma. 

Onishi Y, Akisue T, Ka wamoto T, Ueha T, Hara H, Toda M, Harada R, Minoda M, Morishita M, Sasaki R, et al: Transcutaneous application of CO(2) enhances the antitumor effect of radiation therapy in human malignant fibrous histiocytoma. Int J Oncol. 45:732–738. 2014 PubMed/NXBI.

Sarcomas are relatively resistant because of hypoxia. The purpose of this study was to evaluate the effects of transcutaneous CO(2) therapy on the antitumor efficacy of X-ray irradiation using MFH. First, in an in vitro study, apoptotic activity and reactive oxygen species (ROS) production were assessed using flow cytometric and immunoblot analysis at 24 h after X-ray irradiation under three different oxygen conditions (normoxic, reoxygenated and hypoxic). In addition, in the in vivo study, 24 male athymic BALB/c nude mice with MFH tumors that were inoculated in the dorsal subcutaneous area were randomized into four groups: control, CO(2), X-ray irradiation and combination (CO(2) and X-ray irradiation). Treatments were performed twice weekly for 2 weeks, four times in total. Tumor volume was calculated. All tumors were excised and apoptotic activity, ROS production, related proteins and HIF-1α expression were assessed using flow cytometric and immunoblot analysis. The data revealed that X-ray irradiation induced increased apoptosis and ROS production in MFH cells under normoxic and reoxygenated conditions relative to hypoxic conditions (P<00.01). In the in vivo study, tumor volume in the combination group was reduced to 28, 42 and 47% of that in the control, CO(2), and X-ray groups, respectively (P<00.05). Apoptotic activity and ROS production in the combination group were strongly increased with decreasing HIF-1α expression relative to the control, CO(2) and X-ray groups. The transcutaneous CO(2) system enhanced the antitumor action of X-ray irradiation and could be a novel therapeutic tool for overcoming radio-resistance in human malignancies. 

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