Limits...
Coibamide A induces mTOR-independent autophagy and cell death in human glioblastoma cells.

Hau AM, Greenwood JA, Löhr CV, Serrill JD, Proteau PJ, Ganley IG, McPhail KL, Ishmael JE - PLoS ONE (2013)

Bottom Line: Previous testing of coibamide A in the NCI in vitro 60 cancer cell line panel revealed a potent anti-proliferative response and "COMPARE-negative" profile indicative of a unique mechanism of action.Coibamide A also induces morphologically and biochemically distinct forms of cell death according to cell type.Coibamide A represents a natural product scaffold with potential for the study of mTOR-independent signaling and cell death mechanisms in apoptotic-resistant cancer cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Oregon State University, Corvallis, Oregon, United States of America.

ABSTRACT
Coibamide A is an N-methyl-stabilized depsipeptide that was isolated from a marine cyanobacterium as part of an International Cooperative Biodiversity Groups (ICBG) program based in Panama. Previous testing of coibamide A in the NCI in vitro 60 cancer cell line panel revealed a potent anti-proliferative response and "COMPARE-negative" profile indicative of a unique mechanism of action. We report that coibamide A is a more potent and efficacious cytotoxin than was previously appreciated, inducing concentration- and time-dependent cytotoxicity (EC50<100 nM) in human U87-MG and SF-295 glioblastoma cells and mouse embryonic fibroblasts (MEFs). This activity was lost upon linearization of the molecule, highlighting the importance of the cyclized structure for both anti-proliferative and cytotoxic responses. We show that coibamide A induces autophagosome accumulation in human glioblastoma cell types and MEFs via an mTOR-independent mechanism; no change was observed in the phosphorylation state of ULK1 (Ser-757), p70 S6K1 (Thr-389), S6 ribosomal protein (Ser-235/236) and 4EBP-1 (Thr-37/46). Coibamide A also induces morphologically and biochemically distinct forms of cell death according to cell type. SF-295 glioblastoma cells showed caspase-3 activation and evidence of apoptotic cell death in a pattern that was also seen in wild-type and autophagy-deficient (ATG5-) MEFs. In contrast, cell death in U87-MG glioblastoma cells was characterized by extensive cytoplasmic vacuolization and lacked clear apoptotic features. Cell death was attenuated, but still triggered, in Apaf-1- MEFs lacking a functional mitochondria-mediated apoptotic pathway. From the study of ATG5- MEFs we conclude that a conventional autophagy response is not required for coibamide A-induced cell death, but likely occurs in dying cells in response to treatment. Coibamide A represents a natural product scaffold with potential for the study of mTOR-independent signaling and cell death mechanisms in apoptotic-resistant cancer cells.

Show MeSH

Related in: MedlinePlus

Cytotoxic effect of coibamide A on human glioblastoma cells.(A) Cell death in U87-MG (upper panels) and SF-295 (lower panels) glioma cells after a 3-day exposure to coibamide A (20 nM). Cell death was documented by morphological evaluation of vehicle-(DMSO; panels a and c) or coibamide A-treated (panels b and d) cells using light microscopy. (B) Concentration-response profile for coibamide A-induced cytotoxicity in U87-MG and SF-295 cells. Glioma cells were treated with increasing concentrations of coibamide A (2.3 to 230 nM) for 3 days. Cytotoxicity was determined by MTT assay with the viability of control cells defined as 100%. Dose-response data represent mean viability ± SE (n = 3 wells per treatment) from a comparison that was repeated in at least four independent experiments.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3675158&req=5

pone-0065250-g001: Cytotoxic effect of coibamide A on human glioblastoma cells.(A) Cell death in U87-MG (upper panels) and SF-295 (lower panels) glioma cells after a 3-day exposure to coibamide A (20 nM). Cell death was documented by morphological evaluation of vehicle-(DMSO; panels a and c) or coibamide A-treated (panels b and d) cells using light microscopy. (B) Concentration-response profile for coibamide A-induced cytotoxicity in U87-MG and SF-295 cells. Glioma cells were treated with increasing concentrations of coibamide A (2.3 to 230 nM) for 3 days. Cytotoxicity was determined by MTT assay with the viability of control cells defined as 100%. Dose-response data represent mean viability ± SE (n = 3 wells per treatment) from a comparison that was repeated in at least four independent experiments.

Mentions: Coibamide A produced concentration- and time-dependent cell death in human U87-MG and SF-295 glioblastoma cells. Overt cytotoxicity was not evident within the first 24 to 36 h of coibamide A exposure. When treatment times were extended however, coibamide A caused progressive rounding and detachment of both glioma cell lines from the culture plates. As illustrated in figure 1A, both U87-MG and SF-295 cells showed reduced proliferation and significant changes in morphology by 72 h of exposure to coibamide A (20 nM) relative to vehicle-treated cultures. Coibamide A-induced cytotoxicity was concentration-dependent with EC50 values of 28.8±8.4 nM and 96.2±23 nM for U87-MG and SF-295 cells, respectively (Fig. 1B).


Coibamide A induces mTOR-independent autophagy and cell death in human glioblastoma cells.

Hau AM, Greenwood JA, Löhr CV, Serrill JD, Proteau PJ, Ganley IG, McPhail KL, Ishmael JE - PLoS ONE (2013)

Cytotoxic effect of coibamide A on human glioblastoma cells.(A) Cell death in U87-MG (upper panels) and SF-295 (lower panels) glioma cells after a 3-day exposure to coibamide A (20 nM). Cell death was documented by morphological evaluation of vehicle-(DMSO; panels a and c) or coibamide A-treated (panels b and d) cells using light microscopy. (B) Concentration-response profile for coibamide A-induced cytotoxicity in U87-MG and SF-295 cells. Glioma cells were treated with increasing concentrations of coibamide A (2.3 to 230 nM) for 3 days. Cytotoxicity was determined by MTT assay with the viability of control cells defined as 100%. Dose-response data represent mean viability ± SE (n = 3 wells per treatment) from a comparison that was repeated in at least four independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675158&req=5

pone-0065250-g001: Cytotoxic effect of coibamide A on human glioblastoma cells.(A) Cell death in U87-MG (upper panels) and SF-295 (lower panels) glioma cells after a 3-day exposure to coibamide A (20 nM). Cell death was documented by morphological evaluation of vehicle-(DMSO; panels a and c) or coibamide A-treated (panels b and d) cells using light microscopy. (B) Concentration-response profile for coibamide A-induced cytotoxicity in U87-MG and SF-295 cells. Glioma cells were treated with increasing concentrations of coibamide A (2.3 to 230 nM) for 3 days. Cytotoxicity was determined by MTT assay with the viability of control cells defined as 100%. Dose-response data represent mean viability ± SE (n = 3 wells per treatment) from a comparison that was repeated in at least four independent experiments.
Mentions: Coibamide A produced concentration- and time-dependent cell death in human U87-MG and SF-295 glioblastoma cells. Overt cytotoxicity was not evident within the first 24 to 36 h of coibamide A exposure. When treatment times were extended however, coibamide A caused progressive rounding and detachment of both glioma cell lines from the culture plates. As illustrated in figure 1A, both U87-MG and SF-295 cells showed reduced proliferation and significant changes in morphology by 72 h of exposure to coibamide A (20 nM) relative to vehicle-treated cultures. Coibamide A-induced cytotoxicity was concentration-dependent with EC50 values of 28.8±8.4 nM and 96.2±23 nM for U87-MG and SF-295 cells, respectively (Fig. 1B).

Bottom Line: Previous testing of coibamide A in the NCI in vitro 60 cancer cell line panel revealed a potent anti-proliferative response and "COMPARE-negative" profile indicative of a unique mechanism of action.Coibamide A also induces morphologically and biochemically distinct forms of cell death according to cell type.Coibamide A represents a natural product scaffold with potential for the study of mTOR-independent signaling and cell death mechanisms in apoptotic-resistant cancer cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Oregon State University, Corvallis, Oregon, United States of America.

ABSTRACT
Coibamide A is an N-methyl-stabilized depsipeptide that was isolated from a marine cyanobacterium as part of an International Cooperative Biodiversity Groups (ICBG) program based in Panama. Previous testing of coibamide A in the NCI in vitro 60 cancer cell line panel revealed a potent anti-proliferative response and "COMPARE-negative" profile indicative of a unique mechanism of action. We report that coibamide A is a more potent and efficacious cytotoxin than was previously appreciated, inducing concentration- and time-dependent cytotoxicity (EC50<100 nM) in human U87-MG and SF-295 glioblastoma cells and mouse embryonic fibroblasts (MEFs). This activity was lost upon linearization of the molecule, highlighting the importance of the cyclized structure for both anti-proliferative and cytotoxic responses. We show that coibamide A induces autophagosome accumulation in human glioblastoma cell types and MEFs via an mTOR-independent mechanism; no change was observed in the phosphorylation state of ULK1 (Ser-757), p70 S6K1 (Thr-389), S6 ribosomal protein (Ser-235/236) and 4EBP-1 (Thr-37/46). Coibamide A also induces morphologically and biochemically distinct forms of cell death according to cell type. SF-295 glioblastoma cells showed caspase-3 activation and evidence of apoptotic cell death in a pattern that was also seen in wild-type and autophagy-deficient (ATG5-) MEFs. In contrast, cell death in U87-MG glioblastoma cells was characterized by extensive cytoplasmic vacuolization and lacked clear apoptotic features. Cell death was attenuated, but still triggered, in Apaf-1- MEFs lacking a functional mitochondria-mediated apoptotic pathway. From the study of ATG5- MEFs we conclude that a conventional autophagy response is not required for coibamide A-induced cell death, but likely occurs in dying cells in response to treatment. Coibamide A represents a natural product scaffold with potential for the study of mTOR-independent signaling and cell death mechanisms in apoptotic-resistant cancer cells.

Show MeSH
Related in: MedlinePlus