Methionine addiction is a fundamental and general hallmark of cancer. Methionine addiction prevents cancer cells, but not normal cells from proliferation under methionine restriction (MR). Previous ...studies reported that MR altered the histone methylation levels in methionine-addicted cancer cells. However, no study has yet compared the status of histone methylation status, under MR, between cancer cells and normal cells. In the present study, we compared the histone methylation status between cancer cells and normal fibroblasts of H3K4me3 and H3K9me3, using recombinant methioninase (rMETase) to effect MR. Human lung and colon cancer cell lines and human normal foreskin fibroblasts were cultured in control medium or medium with rMETase. The viability of foreskin fibroblasts was approximately 10 times more resistant to rMETase than the cancer cells in vitro. Proliferation only of the cancer cells ceased under MR. The histone methylation status of H3K4me3 and H3K9me3 under MR was evaluated by immunoblotting. The levels of the H3K4me3 and H3K9me3 were strongly decreased by MR in the cancer cells. In contrast, the levels of H3K4me3 and H3K9me3 were not altered by MR in normal fibroblasts. The present results suggest that histone methylation status of H3K4me3 and H3K9me3 under MR was unstable in cancer cells but stable in normal cells and the instability of histone methylation status under MR may determine the high methionine dependency of cancer cells to survive and proliferate.
•Methionine addiction is a fundamental and general hallmark of cancer.•H3K4me3 and H3K9me3 are unstable in cancer but not normal cells under methionine restriction (MR).•These results help explain why cancer cells and not normal cells cease proliferation under MR.•MR is efficiently effected by recombinant methioninase.
Recombinant methioninase (rMETase) was previously administered as an injectable drug to target methionine dependence of cancer. Recently, we observed that rMETase could be administered orally ...(o-rMETase) in a patient-derived orthotopic xenograft (PDOX) mouse model of melanoma. Here, we determined the efficacy of o-rMETase on a pancreatic cancer PDOX model. Forty pancreatic cancer PDOX mouse models were randomized into four groups of 10 mice each. o-rMETase was significantly more effective than i.p.-rMETase, but the combination of both was significantly more effective than either alone. Acquired gemcitabine resistance is a major factor in the recalcitrance of pancreatic cancer. We tested a human pancreatic cancer cell line, which has acquired >100-fold GEM-resistance (PK-9R) than its parental cell line PK-9. In contrast to GEM, both cell lines were very sensitive to rMETase. In orthotopic nude mouse models of PK-9 and PK-9R, GEM inhibited tumor growth in PK-9 but not PK-9R. In contrast, o-rMETase could inhibit both tumors. The combination of GEM + o-rMETase could regress the PK-9 tumor and inhibit PK-9R tumor growth. The present study shows that o-rMETase is effective and overcomes acquired GEM resistance in pancreatic cancer and demonstrates the clinical potential of this strategy.
•Evaluated the efficacy of Oral methioninase (o-rMETase) on a pancreatic cancer PDOX model.•o-rMETase is highly effective against the pancreatic cancer PDOX.•o-rMETase is potentially safer than intra-peritoneally-methioninase.•o-rMETase overcomes acquired gemcitabine resistance in pancreatic cancer.
Positron emission tomography (PET) is widely used to detect cancers. The usual isotope for PET imaging of cancer is
Fdeoxyglucose. The premise of using
Fdeoxyglucose is that cancers are addicted to ...glucose (The Warburg effect). However, cancers are more severely addicted to methionine (The Hoffman effect).
Cmethionine PET (MET-PET) has been effectively used for the detection of glioblastoma and other cancers in the brain, and in comparison, MET-PET has been shown to be more sensitive and accurate than
Fdeoxyglucose PET (FDG-PET). However, MET-PET has been limited to cancers in the brain. The present report describes the first applications of MET-PET to cancers of multiple organs, including rectal, bladder, lung, and kidney. The results in each case show that MET-PET is superior to FDG-PET due to the methionine addiction of cancer and suggest that the broad application of MET-PET should be undertaken for cancer detection.
Cancer cells are methionine (MET) and methylation addicted and are highly sensitive to MET restriction. The present study determined the efficacy of oral-recombinant methioninase (o-rMETase) and the ...DNA methylation inhibitor, decitabine (DAC) on restricting MET in an undifferentiated-soft tissue sarcoma (USTS) patient-derived orthotopic xenograft (PDOX) nude-mouse model. The USTS PDOX models were randomized into five treatment groups of six mice: Control; doxorubicin (DOX) alone; DAC alone; o-rMETase alone; and o-rMETase-DAC combination. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was arrested only in the o-rMETase-DAC condition. Tumors treated with the o-rMETase-DAC combination exhibited tumor necrosis with degenerative changes. This study demonstrates that the o-rMETase-DAC combination could arrest the USTS PDOX tumor suggesting clinical promise.
•Cancer cells are methionine (MET) and methylation addicted.•Oral rMETase (o-rMETase) is efficacious in cancers grown in patient-derived orthotopic xenograft (PDOX) models.•Combination of o-rMETase and DAC arrests undifferentiated-soft tissue sarcoma (USTS) USTS-PDOX.•Tumor treated with o-rMETase-DAC combination show tumor necrosis with degenerative changes.•Efficacy of o-rMETase-DAC combination on USTS PDOX tumor show clinical promise.
The aim of the present study was to identify effective drugs for a highly-aggressive liver-metastasis of triple-negative breast cancer (TNBC) in a patient-derived orthotopic xenograft (PDOX) mouse ...model. Drugs tested were oral recombinant methioninase (o-rMETase), low-dose eribulin and their combination.
Patient-derived TNBC was implanted in the liver of nude mice by surgical hepatic implantation. Two weeks after transplantation, 32 mice were randomized (n=8 per group) into a phosphate-buffered saline vehicle-control group; o-rMETase-treatment group (100 units, o-rMETase, oral, daily for 2 weeks); eribulin-treatment group (0.05 mg/kg intraperitoneally once per week for 2 weeks); or combination-treatment group (100 units r-METase, oral, daily for 2 weeks + 0.05 mg/kg eribulin intraperitoneally once per week for 2 weeks).
After 2 weeks, the three treatment groups exhibited significantly-inhibited TNBC growth in the liver compared to the vehicle-control group (p≤0.05).
o-rMETase and low-dose eribulin monotherapy and their combination were efficacious against the highly-aggressive TNBC PDOX growing in the liver. The TNBC PDOX model can be used to identify highly-effective drugs for therapy of TNBC with liver metastasis.
Purpose
Cancers are methionine (MET) and methylation addicted, causing them to be highly sensitive to MET restriction. The present study determined the efficacy of restricting MET with ...oral-recombinant methioninase (o-rMETase) and the DNA methylation inhibitor, azacitidine (AZA) on a chemotherapy-resistant osteosarcoma patient-derived orthotopic xenograft (PDOX) mouse model.
Methods
The osteosarcoma PDOX models were randomized into five treatment groups of six mice: control; doxorubicin (DOX) alone; AZA alone; o-rMETase alone; o-rMETase-AZA combination. Tumor size and body weight were measured during the 14 days of treatment.
Results
We found that tumor growth was arrested only by the o-rMETase–AZA combination treatment, as tumors with this treatment exhibited tumor necrosis with degenerative change.
Conclusion
This study suggests that o-rMETase-AZA combination has clinical potential for patients with chemoresistant osteosarcoma.
Methionine addiction, a fundamental and general hallmark of cancer, is due to the excess use of methionine for transmethylation, and is described as the Hoffman-effect. Methionine-addicted cancer ...cells can revert at low frequency to methionine independence when selected under methionine-restriction. We report here that highly-malignant methionine-addicted H460 human lung-cancer cells, when selected for methionine independence, have greatly-reduced tumorigenic potential.
Methionine-addicted H460 parental cancer cells and methionine-independent revertant H460-R1 cells were injected in nude mice subcutaneously.
When the parental H460 methionine-addicted cells were injected in nude mice at 2.5×10
, 1×10
and 5×10
, the cells could form tumors. In contrast, the H460-R1 methionine-independent revertant cells could not form tumors when the above-listed cell numbers were injected in nude mice.
There is a tight linkage between methionine addiction and malignancy.
Methionine dependence is due to the overuse of methionine for aberrant transmethylation reactions in cancer. Methionine dependence may be the only general metabolic defect in cancer. In order to ...exploit methionine dependence for therapy, our laboratory previously cloned L-methionine α-deamino-γ-mercaptomethane lyase EC 4.4.1.11). The cloned methioninase, termed recombinant methioninase, or rMETase, has been tested in mouse models of human cancer cell lines. Ewing's sarcoma is recalcitrant disease even though development of multimodal therapy has improved patients'outcome. Here we report efficacy of rMETase against Ewing's sarcoma in a patient-derived orthotopic xenograft (PDOX) model. The Ewing's sarcoma was implanted in the right chest wall of nude mice to establish a PDOX model. Eight Ewing's sarcoma PDOX mice were randomized into untreated control group (n = 4) and rMETase treatment group (n = 4). rMETase (100 units) was injected intraperitoneally (i.p.) every 24 hours for 14 consecutive days. All mice were sacrificed on day-15, 24 hours after the last rMETase administration. rMETase effectively reduced tumor growth compared to untreated control. The methionine level both of plasma and supernatants derived from sonicated tumors was lower in the rMETase group. Body weight did not significantly differ at any time points between the 2 groups. The present study is the first demonstrating rMETase efficacy in a PDOX model, suggesting potential clinical development, especially in recalcitrant cancers such as Ewing's sarcoma.
Methionine addiction, a fundamental and general hallmark of cancer, known as the Hoffman Effect, is due to altered use of methionine for increased and aberrant transmethylation reactions. However, ...the linkage of methionine addiction and malignancy of cancer cells is incompletely understood. An isogenic pair of methionine-addicted parental osteosarcoma cells and their rare methionine-independent revertant cells enabled us to compare them for malignancy, their epithelial-mesenchymal phenotype, and pattern of histone-H3 lysine-methylation. Methionine-independent revertant 143B osteosarcoma cells (143B-R) were selected from methionine-addicted parental cells (143B-P) by their chronic growth in low-methionine culture medium for 4 passages, which was depleted of methionine by recombinant methioninase (rMETase). Cell-migration capacity was compared with a wound-healing assay and invasion capability was compared with a transwell assay in 143B-P and 143B-R cells
in vitro
. Tumor growth and metastatic potential were compared after orthotopic cell-injection into the tibia bone of nude mice
in vivo
. Epithelial-mesenchymal phenotypic expression and the status of H3 lysine-methylation were determined with western immunoblotting. 143B-P cells had an IC
50
of 0.20 U/ml and 143B-R cells had an IC
50
of 0.68 U/ml for treatment with rMETase, demonstrating that 143B-R cells had regained the ability to grow in low methionine conditions. 143B-R cells had reduced cell migration and invasion capability
in vitro
, formed much smaller tumors than 143B-P cells and lost metastatic potential
in vivo
, indicating loss of malignancy in 143B-R cells. 143B-R cells showed gain of the epithelial marker, ZO-1 and loss of mesenchymal markers, vimentin, Snail, and Slug and, an increase of histone H3K9me3 and H3K27me3 methylation and a decrease of H3K4me3, H3K36me3, and H3K79me3 methylation, along with their loss of malignancy. These results suggest that shifting the balance in histone methylases might be a way to decrease the malignant potential of cells. The present results demonstrate the rationale to target methionine addiction for improved sarcoma therapy.
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