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The Rab2A GTPase promotes breast cancer stem cells and tumorigenesis via Erk signaling activation.

Luo ML, Gong C, Chen CH, Hu H, Huang P, Zheng M, Yao Y, Wei S, Wulf G, Lieberman J, Zhou XZ, Song E, Lu KP - Cell Rep (2015)

Bottom Line: Mechanistically, Rab2A directly interacts with and prevents dephosphorylation/inactivation of Erk1/2 by the MKP3 phosphatase, resulting in Zeb1 upregulation and β-catenin nuclear translocation.Finally, Rab2A overexpression correlates with poor clinical outcome in breast cancer patients.Thus, Pin1/Rab2A/Erk drives BCSC expansion and tumorigenicity, suggesting potential drug targets.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.

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Rab2A and Its Q58H Mutant Endow BCSC Traits to Normal Primary Human MECs, whereas Silencing Rab2A Inhibits Primary Human BCSC Expansion and Tumorigenesis(A) Western blot showed lentivirus-mediated overexpression of Rab2A and Q58H mutant in two cases of human normal Lin− MECs. Arrowhead, exogenous Flag tagged protein; arrow, endogenous protein.(B) Rab2A or Rab2A Q58H mutant increased the CD24−CD44+ population in primary human MECs.(C) Real-time PCR showed that expression of Rab2A mRNA was markedly increased in the Lin−CD24−CD44+ population, compared to Lin−non-CD24−CD44+ or normal epithelial cells.(D) Expression of Rab2A and unphosphorylated β-catenin protein was markedly increased in Lin−CD24−CD44+ cells compared to Lin−non-CD24−CD44+ cells in human breast cancer tissue and those in normal breast tissue from the same patient.(E) Rab2A was knocked down in Lin−CD24−CD44+ cells sorted from human breast cancer tissue.(F) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased the CD24−CD44+ population.(G and H) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased mammosphere formation. Scale bar represents 100 μm.(I–K) Rab2A KD interfered with both tumor initiation and growth of primary BCSCs in vivo, as shown by tumor growth curve (I), tumor weights (J), and tumor incidence (K). 2,000 lentivirus-transduced Lin−CD24−CD44+ cells isolated from eight breast cancer patients were serially transplanted as xenografts into eight nude mice. P0, freshly isolated primary cells; P1, passage 1; P2, passage 2.In (C) and (H), error bars represent SD of three independent experiments. In (I) and (J), error bars represent SD of eight mice. See also Figure S6.
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Figure 6: Rab2A and Its Q58H Mutant Endow BCSC Traits to Normal Primary Human MECs, whereas Silencing Rab2A Inhibits Primary Human BCSC Expansion and Tumorigenesis(A) Western blot showed lentivirus-mediated overexpression of Rab2A and Q58H mutant in two cases of human normal Lin− MECs. Arrowhead, exogenous Flag tagged protein; arrow, endogenous protein.(B) Rab2A or Rab2A Q58H mutant increased the CD24−CD44+ population in primary human MECs.(C) Real-time PCR showed that expression of Rab2A mRNA was markedly increased in the Lin−CD24−CD44+ population, compared to Lin−non-CD24−CD44+ or normal epithelial cells.(D) Expression of Rab2A and unphosphorylated β-catenin protein was markedly increased in Lin−CD24−CD44+ cells compared to Lin−non-CD24−CD44+ cells in human breast cancer tissue and those in normal breast tissue from the same patient.(E) Rab2A was knocked down in Lin−CD24−CD44+ cells sorted from human breast cancer tissue.(F) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased the CD24−CD44+ population.(G and H) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased mammosphere formation. Scale bar represents 100 μm.(I–K) Rab2A KD interfered with both tumor initiation and growth of primary BCSCs in vivo, as shown by tumor growth curve (I), tumor weights (J), and tumor incidence (K). 2,000 lentivirus-transduced Lin−CD24−CD44+ cells isolated from eight breast cancer patients were serially transplanted as xenografts into eight nude mice. P0, freshly isolated primary cells; P1, passage 1; P2, passage 2.In (C) and (H), error bars represent SD of three independent experiments. In (I) and (J), error bars represent SD of eight mice. See also Figure S6.

Mentions: To extend our findings to primary human cells, we sorted Lin− MECs isolated from reduction mammoplasty tissue from two human donors and infected them with lentiviruses expressing Flag-Rab2A, Flag-Rab2A Q58H at levels similar to or three times the endogenous level (Figures 6A and S6A). Rab2A overexpression led to a dose-dependent increase in the CD24−CD44+ population (Figure 6B). Overexpressing Rab2A Q58H similar to the endogenous level increased the CD24−CD44+ population more than overexpressing Rab2A at three-times-higher levels (Figure 6B). Thus, increasing Rab2A activity by either overexpression or using naturally occurring cancer-derived mutation endows BCSC traits to normal human MECs.


The Rab2A GTPase promotes breast cancer stem cells and tumorigenesis via Erk signaling activation.

Luo ML, Gong C, Chen CH, Hu H, Huang P, Zheng M, Yao Y, Wei S, Wulf G, Lieberman J, Zhou XZ, Song E, Lu KP - Cell Rep (2015)

Rab2A and Its Q58H Mutant Endow BCSC Traits to Normal Primary Human MECs, whereas Silencing Rab2A Inhibits Primary Human BCSC Expansion and Tumorigenesis(A) Western blot showed lentivirus-mediated overexpression of Rab2A and Q58H mutant in two cases of human normal Lin− MECs. Arrowhead, exogenous Flag tagged protein; arrow, endogenous protein.(B) Rab2A or Rab2A Q58H mutant increased the CD24−CD44+ population in primary human MECs.(C) Real-time PCR showed that expression of Rab2A mRNA was markedly increased in the Lin−CD24−CD44+ population, compared to Lin−non-CD24−CD44+ or normal epithelial cells.(D) Expression of Rab2A and unphosphorylated β-catenin protein was markedly increased in Lin−CD24−CD44+ cells compared to Lin−non-CD24−CD44+ cells in human breast cancer tissue and those in normal breast tissue from the same patient.(E) Rab2A was knocked down in Lin−CD24−CD44+ cells sorted from human breast cancer tissue.(F) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased the CD24−CD44+ population.(G and H) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased mammosphere formation. Scale bar represents 100 μm.(I–K) Rab2A KD interfered with both tumor initiation and growth of primary BCSCs in vivo, as shown by tumor growth curve (I), tumor weights (J), and tumor incidence (K). 2,000 lentivirus-transduced Lin−CD24−CD44+ cells isolated from eight breast cancer patients were serially transplanted as xenografts into eight nude mice. P0, freshly isolated primary cells; P1, passage 1; P2, passage 2.In (C) and (H), error bars represent SD of three independent experiments. In (I) and (J), error bars represent SD of eight mice. See also Figure S6.
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Figure 6: Rab2A and Its Q58H Mutant Endow BCSC Traits to Normal Primary Human MECs, whereas Silencing Rab2A Inhibits Primary Human BCSC Expansion and Tumorigenesis(A) Western blot showed lentivirus-mediated overexpression of Rab2A and Q58H mutant in two cases of human normal Lin− MECs. Arrowhead, exogenous Flag tagged protein; arrow, endogenous protein.(B) Rab2A or Rab2A Q58H mutant increased the CD24−CD44+ population in primary human MECs.(C) Real-time PCR showed that expression of Rab2A mRNA was markedly increased in the Lin−CD24−CD44+ population, compared to Lin−non-CD24−CD44+ or normal epithelial cells.(D) Expression of Rab2A and unphosphorylated β-catenin protein was markedly increased in Lin−CD24−CD44+ cells compared to Lin−non-CD24−CD44+ cells in human breast cancer tissue and those in normal breast tissue from the same patient.(E) Rab2A was knocked down in Lin−CD24−CD44+ cells sorted from human breast cancer tissue.(F) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased the CD24−CD44+ population.(G and H) Rab2A KD in Lin−CD24−CD44+ breast cancer cells decreased mammosphere formation. Scale bar represents 100 μm.(I–K) Rab2A KD interfered with both tumor initiation and growth of primary BCSCs in vivo, as shown by tumor growth curve (I), tumor weights (J), and tumor incidence (K). 2,000 lentivirus-transduced Lin−CD24−CD44+ cells isolated from eight breast cancer patients were serially transplanted as xenografts into eight nude mice. P0, freshly isolated primary cells; P1, passage 1; P2, passage 2.In (C) and (H), error bars represent SD of three independent experiments. In (I) and (J), error bars represent SD of eight mice. See also Figure S6.
Mentions: To extend our findings to primary human cells, we sorted Lin− MECs isolated from reduction mammoplasty tissue from two human donors and infected them with lentiviruses expressing Flag-Rab2A, Flag-Rab2A Q58H at levels similar to or three times the endogenous level (Figures 6A and S6A). Rab2A overexpression led to a dose-dependent increase in the CD24−CD44+ population (Figure 6B). Overexpressing Rab2A Q58H similar to the endogenous level increased the CD24−CD44+ population more than overexpressing Rab2A at three-times-higher levels (Figure 6B). Thus, increasing Rab2A activity by either overexpression or using naturally occurring cancer-derived mutation endows BCSC traits to normal human MECs.

Bottom Line: Mechanistically, Rab2A directly interacts with and prevents dephosphorylation/inactivation of Erk1/2 by the MKP3 phosphatase, resulting in Zeb1 upregulation and β-catenin nuclear translocation.Finally, Rab2A overexpression correlates with poor clinical outcome in breast cancer patients.Thus, Pin1/Rab2A/Erk drives BCSC expansion and tumorigenicity, suggesting potential drug targets.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.

Show MeSH
Related in: MedlinePlus