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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 Is Amplified in Human Cancers, Its Overexpression Expands BCSCs and Tumorigenicity, and the Cancer-Derived Rab2A Q58H Mutant Has Reduced GTPase Activity(A) Rab2A gene amplification in a wide range of human cancers reported in cBioPortal.(B) Stable overexpression of Rab2A in Pin1 KD or control HMLE cells using retrovirus-mediated gene transfer, as determined by immunoblot.(C) Overexpression of Rab2A in HMLE cells potently induced the CD24−CD44+ population and rescued the phenotypes inhibited by Pin1 KD.(D) Overexpression of Rab2A increased the mammosphere formation in control shRNA (shCtrl) HMLE cells and rescued the phenotypes inhibited by Pin1 KD.(E and F) Overexpression of Rab2A potently induced the EMT in HMLE cells, as assayed by cell morphology (E) and real-time RT-PCR of the marker expressions (F).(G and H) Rab2A overexpression increased tumorigenicity of BCSCs, while its KD impaired the ability of Pin1 overexpression to increase tumorigenicity of BCSCs, as measured by a limiting-dilution tumor-initiation assay in nude mice. Two months later, mice were sacrificed and evaluated for tumor weight (G) and tumor incidence (H).(I) Q58 in Rab2A is evolutionally conserved across species.(J and K) The Q58H mutant displayed decreased GTP hydrolysis activity, compared to the WT Rab2A protein in the in vitro GTPase assay, as monitored by α-32P-labeled GTP hydrolysis (J), and quantified by densitometry of three independent experiments (K).(L) HMLE-Ras cells infected with Rab2A Q58H were more potent in forming tumors than those infected with WT Rab2A when overexpressed at the endogenous levels.In all panels, error bars represent SD of three independent experiments. See also Figure S3.
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Figure 2: Rab2A Is Amplified in Human Cancers, Its Overexpression Expands BCSCs and Tumorigenicity, and the Cancer-Derived Rab2A Q58H Mutant Has Reduced GTPase Activity(A) Rab2A gene amplification in a wide range of human cancers reported in cBioPortal.(B) Stable overexpression of Rab2A in Pin1 KD or control HMLE cells using retrovirus-mediated gene transfer, as determined by immunoblot.(C) Overexpression of Rab2A in HMLE cells potently induced the CD24−CD44+ population and rescued the phenotypes inhibited by Pin1 KD.(D) Overexpression of Rab2A increased the mammosphere formation in control shRNA (shCtrl) HMLE cells and rescued the phenotypes inhibited by Pin1 KD.(E and F) Overexpression of Rab2A potently induced the EMT in HMLE cells, as assayed by cell morphology (E) and real-time RT-PCR of the marker expressions (F).(G and H) Rab2A overexpression increased tumorigenicity of BCSCs, while its KD impaired the ability of Pin1 overexpression to increase tumorigenicity of BCSCs, as measured by a limiting-dilution tumor-initiation assay in nude mice. Two months later, mice were sacrificed and evaluated for tumor weight (G) and tumor incidence (H).(I) Q58 in Rab2A is evolutionally conserved across species.(J and K) The Q58H mutant displayed decreased GTP hydrolysis activity, compared to the WT Rab2A protein in the in vitro GTPase assay, as monitored by α-32P-labeled GTP hydrolysis (J), and quantified by densitometry of three independent experiments (K).(L) HMLE-Ras cells infected with Rab2A Q58H were more potent in forming tumors than those infected with WT Rab2A when overexpressed at the endogenous levels.In all panels, error bars represent SD of three independent experiments. See also Figure S3.

Mentions: To determine more directly the role of Rab2A in breast cancer, we first checked Rab2A gene alterations in cancers in the cBio Cancer Genomics Portal (Cerami et al., 2012). Significantly, Rab2A gene amplification occurs in a wide range of human cancers, with the highest frequency of ~9.5% (72 of 760) in invasive breast carcinoma patients (Figure 2A). Importantly, Rab2A mRNA levels increase significantly with increasing gene copy number in invasive breast carcinomas (p = 1.56E−84) and others (Figure S3A). Moreover, Rab2A amplification is independent of MYC on 8q, according to Tumorscape software (Beroukhim et al., 2010).


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 Is Amplified in Human Cancers, Its Overexpression Expands BCSCs and Tumorigenicity, and the Cancer-Derived Rab2A Q58H Mutant Has Reduced GTPase Activity(A) Rab2A gene amplification in a wide range of human cancers reported in cBioPortal.(B) Stable overexpression of Rab2A in Pin1 KD or control HMLE cells using retrovirus-mediated gene transfer, as determined by immunoblot.(C) Overexpression of Rab2A in HMLE cells potently induced the CD24−CD44+ population and rescued the phenotypes inhibited by Pin1 KD.(D) Overexpression of Rab2A increased the mammosphere formation in control shRNA (shCtrl) HMLE cells and rescued the phenotypes inhibited by Pin1 KD.(E and F) Overexpression of Rab2A potently induced the EMT in HMLE cells, as assayed by cell morphology (E) and real-time RT-PCR of the marker expressions (F).(G and H) Rab2A overexpression increased tumorigenicity of BCSCs, while its KD impaired the ability of Pin1 overexpression to increase tumorigenicity of BCSCs, as measured by a limiting-dilution tumor-initiation assay in nude mice. Two months later, mice were sacrificed and evaluated for tumor weight (G) and tumor incidence (H).(I) Q58 in Rab2A is evolutionally conserved across species.(J and K) The Q58H mutant displayed decreased GTP hydrolysis activity, compared to the WT Rab2A protein in the in vitro GTPase assay, as monitored by α-32P-labeled GTP hydrolysis (J), and quantified by densitometry of three independent experiments (K).(L) HMLE-Ras cells infected with Rab2A Q58H were more potent in forming tumors than those infected with WT Rab2A when overexpressed at the endogenous levels.In all panels, error bars represent SD of three independent experiments. See also Figure S3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401741&req=5

Figure 2: Rab2A Is Amplified in Human Cancers, Its Overexpression Expands BCSCs and Tumorigenicity, and the Cancer-Derived Rab2A Q58H Mutant Has Reduced GTPase Activity(A) Rab2A gene amplification in a wide range of human cancers reported in cBioPortal.(B) Stable overexpression of Rab2A in Pin1 KD or control HMLE cells using retrovirus-mediated gene transfer, as determined by immunoblot.(C) Overexpression of Rab2A in HMLE cells potently induced the CD24−CD44+ population and rescued the phenotypes inhibited by Pin1 KD.(D) Overexpression of Rab2A increased the mammosphere formation in control shRNA (shCtrl) HMLE cells and rescued the phenotypes inhibited by Pin1 KD.(E and F) Overexpression of Rab2A potently induced the EMT in HMLE cells, as assayed by cell morphology (E) and real-time RT-PCR of the marker expressions (F).(G and H) Rab2A overexpression increased tumorigenicity of BCSCs, while its KD impaired the ability of Pin1 overexpression to increase tumorigenicity of BCSCs, as measured by a limiting-dilution tumor-initiation assay in nude mice. Two months later, mice were sacrificed and evaluated for tumor weight (G) and tumor incidence (H).(I) Q58 in Rab2A is evolutionally conserved across species.(J and K) The Q58H mutant displayed decreased GTP hydrolysis activity, compared to the WT Rab2A protein in the in vitro GTPase assay, as monitored by α-32P-labeled GTP hydrolysis (J), and quantified by densitometry of three independent experiments (K).(L) HMLE-Ras cells infected with Rab2A Q58H were more potent in forming tumors than those infected with WT Rab2A when overexpressed at the endogenous levels.In all panels, error bars represent SD of three independent experiments. See also Figure S3.
Mentions: To determine more directly the role of Rab2A in breast cancer, we first checked Rab2A gene alterations in cancers in the cBio Cancer Genomics Portal (Cerami et al., 2012). Significantly, Rab2A gene amplification occurs in a wide range of human cancers, with the highest frequency of ~9.5% (72 of 760) in invasive breast carcinoma patients (Figure 2A). Importantly, Rab2A mRNA levels increase significantly with increasing gene copy number in invasive breast carcinomas (p = 1.56E−84) and others (Figure S3A). Moreover, Rab2A amplification is independent of MYC on 8q, according to Tumorscape software (Beroukhim et al., 2010).

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