Biomedical subjects

Junichiro Mizuguchi

Publications and source records attributed to Junichiro Mizuguchi.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Id3-mediated enhancement of cisplatin-induced apoptosis in a sarcoma cell line MG-63.

The molecular mechanism(s) underlying the resistance to cis-diamminedichloroplatinum (CDDP)-induced growth inhibition include DNA repair, apoptosis and cell cycle progression. Inhibitor of differentiation (Id) proteins, which belong to the group of helix-loop-helix proteins, regulate cell cycle progression, differentiation and apoptosis. We examined whether CDDP exposure modulates the expression pattern of Ids and whether ectopic expression of Ids influences CDDP-induced cell death. Cell growth was assessed by WST-8 assay kit. Reactive oxygen species (ROS) was evaluated by flow cytometry using dihydroethidium. MG-63 sarcoma cells were stimulated with CDDP for various times and Id expression was assessed by reverse transcription-polymerase chain reaction. CDDP induced a considerable transient up-regulation of Id3 mRNA, but not Id2, 1-2 h after stimulation. Enforced expression of Id3 caused the MG-63 sarcoma cells to be more sensitive to CDDP-induced growth inhibition, through generation of ROS and caspase-3 activation. Together, our results suggest that CDDP-induced cell death appears to involve Id3.

Antineoplastic Agents↗

PubMedDate not supplied

Enforced expression of a truncated form of Bax-alpha (tBax) driven by human telomerase reverse transcriptase (hTERT) promoter sensitizes tumor cells to chemotherapeutic agents or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

BACKGROUND: We have recently demonstrated that a truncated form of the pro-apoptotic molecule Bax-alpha (tBax) at the NH2-terminus is more potent in inducing cell death than wild-type (wt) Bax. In the present study, whether efficient cell death is induced by tBax expression from human telomerase reverse transcriptase (hTERT) promoter, which is highly active in tumor but not normal cells, was examined. MATERIALS AND METHODS: Cell death was assessed by luciferase reporter assay and the annexin staining method. RESULTS: Enforced expression of tBax resulted in cell death to a greater extent than wt Bax in two types of tumor cells: osteogenic sarcoma MG-63 and squamous cell carcinoma MIT7. The tBax sensitized these tumor cells to death induced by chemotherapeutic agents. Moreover, tBax enhanced cell death induced by the tumor necrosis factor-related apoptosis-inducing ligand to a high level, compared with wt Bax. Furthermore, tBax efficiently induced death of the MG-63 cells overexpressing Bcl-x(L), compared with wt Bax. CONCLUSION: tBax alone, or in combination with chemotherapeutic agents, would be a promising candidate for human gene therapy in the setting of carcinoma, especially for tumors containing high levels of Bcl-x(L).

Antineoplastic Agents↗

PubMedDate not supplied

C-jun N-terminal kinase activation is required for apoptotic cell death induced by TNF-related apoptosis-inducing ligand plus DNA-damaging agents in sarcoma cell lines.

BACKGROUND: Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in combination with a chemotherapeutic agent, cis-diammine dichloroplatinum (CDDP) or doxorubicin (DXR), has recently been demonstrated to result in enhanced apoptotic cell death in the sarcoma cell lines MG-63 and SaOS-2. DNA-damaging agents, such as CDDP induced sustained activation of c-Jun N-terminal kinase (JNK), probably leading to apoptosis. In the present study, whether JNK activation is involved in apoptotic cell death induced by combined treatment with CDDP/DXR and TRAIL was addressed. RESULTS: MG-63 or SaOS-2 cells overexpressing the dominant-negative (dn) form of JNK (dnJNK1) were established by transfection with dnJNK1 cDNA. Following stimulation with the chemotherapeutic agent CDDP or TRAIL, both MG-63 and SaOS-2 cells demonstrated enhanced cell death compared with stimulation by either agent alone, as assayed for apoptosis using annexin V staining or mitochondrial membrane potential using DiOC6 staining. Interestingly, partial inhibition of the cell death induced by the combined treatment with CDDP/DXR and TRAIL was found in MG-63 or SaOS-2 cells overexpressing dnJNK1, suggesting that JNK activation is required for the combined treatment. Moreover, induction of caspase-8 activation by TRAIL or TRAIL plus CDDP/DXR was substantially prevented by dnJNK. CONCLUSION: Efficient cell death induced by combined treatment with the chemotherapeutic agents CDDP/DXR and TRAIL is involved in JNK activation in the sarcoma cell lines MG-63 and SaOS-2. These results would be useful for treatment modalities of patients with sarcoma.

Antineoplastic Combined Chemotherapy Protocols↗