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Gamma tocotrienol targets tyrosine phosphatase SHP2 in mammospheres resulting in cell death through RAS/ERK pathway.

Gu W, Prasadam I, Yu M, Zhang F, Ling P, Xiao Y, Yu C - BMC Cancer (2015)

Bottom Line: We found that mammosphere growth was inhibited in a dose dependent manner, with total inhibition at high doses.Our results suggested that both Src homology 2 domain-containing phosphatase 1 (SHP1) and 2 (SHP2) were affected by gamma-T3 which was accompanied by a decrease in K- and H-Ras gene expression and phosphorylated ERK protein levels in a dose dependent way.These results suggest that gamma-T3 specifically targets SHP2 and the RAS/ERK signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: Australian Institute for Bioengineering and Nanotechnology, the University of Queensland, The corner of Cooper Rd. St Lucia, Brisbane, QLD 4072, Australia. w.gu@uq.edu.au.

ABSTRACT

Background: There is increasing evidence supporting the concept of cancer stem cells (CSCs), which are responsible for the initiation, growth and metastasis of tumors. CSCs are thus considered the target for future cancer therapies. To achieve this goal, identifying potential therapeutic targets for CSCs is essential.

Methods: We used a natural product of vitamin E, gamma tocotrienol (gamma-T3), to treat mammospheres and spheres from colon and cervical cancers. Western blotting and real-time RT-PCR were employed to identify the gene and protein targets of gamma-T3 in mammospheres.

Results: We found that mammosphere growth was inhibited in a dose dependent manner, with total inhibition at high doses. Gamma-T3 also inhibited sphere growth in two other human epithelial cancers, colon and cervix. Our results suggested that both Src homology 2 domain-containing phosphatase 1 (SHP1) and 2 (SHP2) were affected by gamma-T3 which was accompanied by a decrease in K- and H-Ras gene expression and phosphorylated ERK protein levels in a dose dependent way. In contrast, expression of self-renewal genes TGF-beta and LIF, as well as ESR signal pathways were not affected by the treatment. These results suggest that gamma-T3 specifically targets SHP2 and the RAS/ERK signaling pathway.

Conclusions: SHP1 and SHP2 are potential therapeutic targets for breast CSCs and gamma-T3 is a promising natural drug for future breast cancer therapy.

No MeSH data available.


Related in: MedlinePlus

Dose-dependent inhibition of sphere growth of three epithelial cancers by γ-T3: a γ-T3 inhibited mammosphere formation and growth from MCF-7 cells in a dose-dependent manner from 1.0 to 5.0 μg/ml. b morphology of mammosphere in vehicle control and in 5 μg/ml G-T3 treatment. c and d In addition to breast cancer, γ-T3 inhibited sphere formation of colon (HCT-116) and cervical (HeLa) cancers respectively
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Fig2: Dose-dependent inhibition of sphere growth of three epithelial cancers by γ-T3: a γ-T3 inhibited mammosphere formation and growth from MCF-7 cells in a dose-dependent manner from 1.0 to 5.0 μg/ml. b morphology of mammosphere in vehicle control and in 5 μg/ml G-T3 treatment. c and d In addition to breast cancer, γ-T3 inhibited sphere formation of colon (HCT-116) and cervical (HeLa) cancers respectively

Mentions: We used the reported sphere culture method [43, 44] to culture mammospheres from breast carcinoma cell line MCF-7. The mammosphere formation rate was about 20 % from the cell line in several generations (passages) of culture. The mammosphere cells were separated and characterized for surface expression of CD44 and CD24, which are commonly considered as markers of breast cancer stem cells [2]. The results showed CD44 expression increased in mammosphere cells and the positive cell proportion increased from 5.62 % of parent MCF-7 cells to 45.65 % of mammosphere cells (Fig. 1). Meanwhile, the expression of CD24 alone and CD24/CD44 double positive cells was deceased from 15.58 to 5.99 % and from 18.99 to 12.18 %, respectively (Fig. 1). These profiles suggest that after sphere culture the mammosphere cells are enriched for breast cancer stem-like cells, which is consistent with previous reports [2, 45]. We then treated mammosphere cells with γ-T3 in sphere culture by adding γ-T3 directly into the sphere culture medium. As shown in Fig. 2, γ-T3 exhibited a dose-dependent inhibition of the growth of mammosphere cells and sphere formation from MCF-7 cells. At 5 μg/ml, the sphere growth was totally inhibited (Fig. 2a).Fig. 1


Gamma tocotrienol targets tyrosine phosphatase SHP2 in mammospheres resulting in cell death through RAS/ERK pathway.

Gu W, Prasadam I, Yu M, Zhang F, Ling P, Xiao Y, Yu C - BMC Cancer (2015)

Dose-dependent inhibition of sphere growth of three epithelial cancers by γ-T3: a γ-T3 inhibited mammosphere formation and growth from MCF-7 cells in a dose-dependent manner from 1.0 to 5.0 μg/ml. b morphology of mammosphere in vehicle control and in 5 μg/ml G-T3 treatment. c and d In addition to breast cancer, γ-T3 inhibited sphere formation of colon (HCT-116) and cervical (HeLa) cancers respectively
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4552156&req=5

Fig2: Dose-dependent inhibition of sphere growth of three epithelial cancers by γ-T3: a γ-T3 inhibited mammosphere formation and growth from MCF-7 cells in a dose-dependent manner from 1.0 to 5.0 μg/ml. b morphology of mammosphere in vehicle control and in 5 μg/ml G-T3 treatment. c and d In addition to breast cancer, γ-T3 inhibited sphere formation of colon (HCT-116) and cervical (HeLa) cancers respectively
Mentions: We used the reported sphere culture method [43, 44] to culture mammospheres from breast carcinoma cell line MCF-7. The mammosphere formation rate was about 20 % from the cell line in several generations (passages) of culture. The mammosphere cells were separated and characterized for surface expression of CD44 and CD24, which are commonly considered as markers of breast cancer stem cells [2]. The results showed CD44 expression increased in mammosphere cells and the positive cell proportion increased from 5.62 % of parent MCF-7 cells to 45.65 % of mammosphere cells (Fig. 1). Meanwhile, the expression of CD24 alone and CD24/CD44 double positive cells was deceased from 15.58 to 5.99 % and from 18.99 to 12.18 %, respectively (Fig. 1). These profiles suggest that after sphere culture the mammosphere cells are enriched for breast cancer stem-like cells, which is consistent with previous reports [2, 45]. We then treated mammosphere cells with γ-T3 in sphere culture by adding γ-T3 directly into the sphere culture medium. As shown in Fig. 2, γ-T3 exhibited a dose-dependent inhibition of the growth of mammosphere cells and sphere formation from MCF-7 cells. At 5 μg/ml, the sphere growth was totally inhibited (Fig. 2a).Fig. 1

Bottom Line: We found that mammosphere growth was inhibited in a dose dependent manner, with total inhibition at high doses.Our results suggested that both Src homology 2 domain-containing phosphatase 1 (SHP1) and 2 (SHP2) were affected by gamma-T3 which was accompanied by a decrease in K- and H-Ras gene expression and phosphorylated ERK protein levels in a dose dependent way.These results suggest that gamma-T3 specifically targets SHP2 and the RAS/ERK signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: Australian Institute for Bioengineering and Nanotechnology, the University of Queensland, The corner of Cooper Rd. St Lucia, Brisbane, QLD 4072, Australia. w.gu@uq.edu.au.

ABSTRACT

Background: There is increasing evidence supporting the concept of cancer stem cells (CSCs), which are responsible for the initiation, growth and metastasis of tumors. CSCs are thus considered the target for future cancer therapies. To achieve this goal, identifying potential therapeutic targets for CSCs is essential.

Methods: We used a natural product of vitamin E, gamma tocotrienol (gamma-T3), to treat mammospheres and spheres from colon and cervical cancers. Western blotting and real-time RT-PCR were employed to identify the gene and protein targets of gamma-T3 in mammospheres.

Results: We found that mammosphere growth was inhibited in a dose dependent manner, with total inhibition at high doses. Gamma-T3 also inhibited sphere growth in two other human epithelial cancers, colon and cervix. Our results suggested that both Src homology 2 domain-containing phosphatase 1 (SHP1) and 2 (SHP2) were affected by gamma-T3 which was accompanied by a decrease in K- and H-Ras gene expression and phosphorylated ERK protein levels in a dose dependent way. In contrast, expression of self-renewal genes TGF-beta and LIF, as well as ESR signal pathways were not affected by the treatment. These results suggest that gamma-T3 specifically targets SHP2 and the RAS/ERK signaling pathway.

Conclusions: SHP1 and SHP2 are potential therapeutic targets for breast CSCs and gamma-T3 is a promising natural drug for future breast cancer therapy.

No MeSH data available.


Related in: MedlinePlus