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Mitochondrially targeted vitamin E succinate efficiently kills breast tumour-initiating cells in a complex II-dependent manner.

Yan B, Stantic M, Zobalova R, Bezawork-Geleta A, Stapelberg M, Stursa J, Prokopova K, Dong L, Neuzil J - BMC Cancer (2015)

Bottom Line: This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance.Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function.Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Science, Griffith University, Southport, Qld, 4222, Australia. bing.yan@griffithuni.edu.au.

ABSTRACT

Background: Accumulating evidence suggests that breast cancer involves tumour-initiating cells (TICs), which play a role in initiation, metastasis, therapeutic resistance and relapse of the disease. Emerging drugs that target TICs are becoming a focus of contemporary research. Mitocans, a group of compounds that induce apoptosis of cancer cells by destabilising their mitochondria, are showing their potential in killing TICs. In this project, we investigated mitochondrially targeted vitamin E succinate (MitoVES), a recently developed mitocan, for its in vitro and in vivo efficacy against TICs.

Methods: The mammosphere model of breast TICs was established by culturing murine NeuTL and human MCF7 cells as spheres. This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance. Cell susceptibility to MitoVES was assessed and the cell death pathway investigated. In vivo efficacy was studied by grafting NeuTL TICs to form syngeneic tumours.

Results: Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function. Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES. Killing of mammospheres was suppressed when the mitochondrial complex II, the molecular target of MitoVES, was knocked down. Importantly, MitoVES inhibited progression of syngeneic HER2(high) tumours derived from breast TICs by inducing apoptosis in tumour cells.

Conclusions: These results demonstrate that using mammospheres, a plausible model for studying TICs, drugs that target mitochondria efficiently kill breast tumour-initiating cells.

No MeSH data available.


Related in: MedlinePlus

NeuTL and MCF7 spheres are a plausible model of TICs. Neu TL cells were cultured in serum-containing and sphere medium (A) and assessed for selected stemness genes by qPCR (C). MCF7 cells were cultured in adherent and ‘sphere’ medium (B) and assessed for selected stemness genes by qPCR (D). (E) NeuTL adherent and sphere cells were grafted s.c. in FVB/N c-neu mice (106 cells per animal) and tumour volume assessed using USI. The images on the right are representative USI scans of tumours taken on the given days (indicated by arrows in the graph on the left). (F) Sections of tumours were stained by H&E for morphology, also showing regions of low and more differentiated cancer cells. (G) Tumour sections were evaluated for the level of erbB2 using WB and IHC. In all cases, the level of stemness genes in sphere cells was related to that in their adherent counterparts, set as 1. Data are mean values ± S.D. (n = 3). The symbol ‘*’ indicates statistically significant differences in the level of mRNA in adherent and sphere cells with p < 0.05. Images in panels A, B, E, F and G are representative of three independent experiments
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Fig1: NeuTL and MCF7 spheres are a plausible model of TICs. Neu TL cells were cultured in serum-containing and sphere medium (A) and assessed for selected stemness genes by qPCR (C). MCF7 cells were cultured in adherent and ‘sphere’ medium (B) and assessed for selected stemness genes by qPCR (D). (E) NeuTL adherent and sphere cells were grafted s.c. in FVB/N c-neu mice (106 cells per animal) and tumour volume assessed using USI. The images on the right are representative USI scans of tumours taken on the given days (indicated by arrows in the graph on the left). (F) Sections of tumours were stained by H&E for morphology, also showing regions of low and more differentiated cancer cells. (G) Tumour sections were evaluated for the level of erbB2 using WB and IHC. In all cases, the level of stemness genes in sphere cells was related to that in their adherent counterparts, set as 1. Data are mean values ± S.D. (n = 3). The symbol ‘*’ indicates statistically significant differences in the level of mRNA in adherent and sphere cells with p < 0.05. Images in panels A, B, E, F and G are representative of three independent experiments

Mentions: To establish an in vitro model to study breast TICs, we grew NeuTL and MCF7 cells under condition that promotes sphere generation (Fig. 1 A, B). Both cell lines formed mammospheres within 3-5 days, reaching ~50 μm in diameter. To verify spheres as a model of breast TICs, mRNA level of a series of ‘stemness’ markers was assessed. As can be seen in Fig. 1 C, NeuTL spheres had higher expression of CD44, ALDH, EpCAM, CD61, CD133, CD49 and CD29f, and lower expression of CD24, compared to their adherent counterparts. MCF7 spheres featured higher level of CD44, CD133, OCT4, ABCG2, ESA and c-Kit, and lower level of CD24 (Fig. 1 D).Fig. 1


Mitochondrially targeted vitamin E succinate efficiently kills breast tumour-initiating cells in a complex II-dependent manner.

Yan B, Stantic M, Zobalova R, Bezawork-Geleta A, Stapelberg M, Stursa J, Prokopova K, Dong L, Neuzil J - BMC Cancer (2015)

NeuTL and MCF7 spheres are a plausible model of TICs. Neu TL cells were cultured in serum-containing and sphere medium (A) and assessed for selected stemness genes by qPCR (C). MCF7 cells were cultured in adherent and ‘sphere’ medium (B) and assessed for selected stemness genes by qPCR (D). (E) NeuTL adherent and sphere cells were grafted s.c. in FVB/N c-neu mice (106 cells per animal) and tumour volume assessed using USI. The images on the right are representative USI scans of tumours taken on the given days (indicated by arrows in the graph on the left). (F) Sections of tumours were stained by H&E for morphology, also showing regions of low and more differentiated cancer cells. (G) Tumour sections were evaluated for the level of erbB2 using WB and IHC. In all cases, the level of stemness genes in sphere cells was related to that in their adherent counterparts, set as 1. Data are mean values ± S.D. (n = 3). The symbol ‘*’ indicates statistically significant differences in the level of mRNA in adherent and sphere cells with p < 0.05. Images in panels A, B, E, F and G are representative of three independent experiments
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4494715&req=5

Fig1: NeuTL and MCF7 spheres are a plausible model of TICs. Neu TL cells were cultured in serum-containing and sphere medium (A) and assessed for selected stemness genes by qPCR (C). MCF7 cells were cultured in adherent and ‘sphere’ medium (B) and assessed for selected stemness genes by qPCR (D). (E) NeuTL adherent and sphere cells were grafted s.c. in FVB/N c-neu mice (106 cells per animal) and tumour volume assessed using USI. The images on the right are representative USI scans of tumours taken on the given days (indicated by arrows in the graph on the left). (F) Sections of tumours were stained by H&E for morphology, also showing regions of low and more differentiated cancer cells. (G) Tumour sections were evaluated for the level of erbB2 using WB and IHC. In all cases, the level of stemness genes in sphere cells was related to that in their adherent counterparts, set as 1. Data are mean values ± S.D. (n = 3). The symbol ‘*’ indicates statistically significant differences in the level of mRNA in adherent and sphere cells with p < 0.05. Images in panels A, B, E, F and G are representative of three independent experiments
Mentions: To establish an in vitro model to study breast TICs, we grew NeuTL and MCF7 cells under condition that promotes sphere generation (Fig. 1 A, B). Both cell lines formed mammospheres within 3-5 days, reaching ~50 μm in diameter. To verify spheres as a model of breast TICs, mRNA level of a series of ‘stemness’ markers was assessed. As can be seen in Fig. 1 C, NeuTL spheres had higher expression of CD44, ALDH, EpCAM, CD61, CD133, CD49 and CD29f, and lower expression of CD24, compared to their adherent counterparts. MCF7 spheres featured higher level of CD44, CD133, OCT4, ABCG2, ESA and c-Kit, and lower level of CD24 (Fig. 1 D).Fig. 1

Bottom Line: This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance.Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function.Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Science, Griffith University, Southport, Qld, 4222, Australia. bing.yan@griffithuni.edu.au.

ABSTRACT

Background: Accumulating evidence suggests that breast cancer involves tumour-initiating cells (TICs), which play a role in initiation, metastasis, therapeutic resistance and relapse of the disease. Emerging drugs that target TICs are becoming a focus of contemporary research. Mitocans, a group of compounds that induce apoptosis of cancer cells by destabilising their mitochondria, are showing their potential in killing TICs. In this project, we investigated mitochondrially targeted vitamin E succinate (MitoVES), a recently developed mitocan, for its in vitro and in vivo efficacy against TICs.

Methods: The mammosphere model of breast TICs was established by culturing murine NeuTL and human MCF7 cells as spheres. This model was verified by stem cell marker expression, tumour initiation capacity and chemotherapeutic resistance. Cell susceptibility to MitoVES was assessed and the cell death pathway investigated. In vivo efficacy was studied by grafting NeuTL TICs to form syngeneic tumours.

Results: Mammospheres derived from NeuTL and MCF7 breast cancer cells were enriched in the level of stemness, and the sphere cells featured altered mitochondrial function. Sphere cultures were resistant to several established anti-cancer agents while they were susceptible to MitoVES. Killing of mammospheres was suppressed when the mitochondrial complex II, the molecular target of MitoVES, was knocked down. Importantly, MitoVES inhibited progression of syngeneic HER2(high) tumours derived from breast TICs by inducing apoptosis in tumour cells.

Conclusions: These results demonstrate that using mammospheres, a plausible model for studying TICs, drugs that target mitochondria efficiently kill breast tumour-initiating cells.

No MeSH data available.


Related in: MedlinePlus