Search

SH3BGRL, an adaptor protein, is upregulated in breast cancers and indicates its tumorigenic role. But the function of SH3BGRL in other types of cancers is largely unknown. Here, we modulate SH3BGRL expression level in two liver cancer cells and conduct both in vitro and in vivo analyses of SH3BGRL in cell proliferation and tumorigenesis. Results demonstrate that SH3BGRL notably inhibits cell proliferation and arrests the cell cycle in both LO2 and HepG2 cells. Molecularly, SH3BGRL upregulates the expression of ATG5 from proteasome degradation as well as the inhibitions of Src activation and its downstream ERK and AKT signaling pathways, which eventually enhance autophagic cell death. The xenograft mouse model reveals that SH3BGRL overexpression can efficiently suppress tumorigenesis in vivo, while the additional silencing ATG5 in SH3BGRL-overexpressing cells attenuates the inhibitory effect of SH3BGRL on both hepatic tumor cell proliferation and tumorigenicity in vivo. The relevance of SH3BGRL downregulation in liver cancers and their progression is validated based on the large-scale tumor data. Taken together, our results clarify the suppressive role of SH3BGRL in tumorigenesis of liver cancer, which would be of help to the diagnosis of liver cancer, while either promoting the autophagy of liver cancer cells or inhibiting the downstream signaling induced from SH3BGRL downregulation would be a promising therapy. [ABSTRACT FROM AUTHOR]

Phosphatase PRL-3 expression is positively associated to acute myeloid leukemia (AML) progression and drug resistance. SH3-domain-binding glutamic acid-rich protein-like protein (SH3BGRL), a downstream effector of PRL-3, plays a tumor suppressive role in solid tumors, but it remains elusive in AML. Here, we followed up and validated the relevance of SH3BGRL expression to AML progression in 116 cases. Results showed that SH3BGRL is down-regulated in 62.37% AML cases with poor prognosis. Cases with positive response to therapy accompanies with SH3GRL expression restoration. Mechanistically, SH3BGRL down-regulation promotes AML cell cycle progression and enhances the anti-apoptotic ability to drug cytotoxicity. While ectopic SH3BGRL blocks AML cell cycle and proliferation to sensitize them to therapeutic drugs via apoptosis. Xenograft assays further confirmed the suppressive role of SH3BGRL in leukemogenesis. Thus, our results demonstrated that SH3BGRL is a novel crucial player in AML progression and could be both a potential diagnostic and prognostic marker. [ABSTRACT FROM AUTHOR]

BACKGROUND Internal tandem duplication of FMS-like tyrosine kinase (FLT3-ITD) is well known to be involved in acute myeloid leukemia (AML) progression, but FLT3-ITD-negative AML cases account for 70% to 80% of AML, and the mechanisms underlying their pathology remain unclear. This study identifies protein tyrosine phophatase PRL-3 as a key mediator of FLT3-ITD-negative AML. METHODS A total of 112 FLT3-ITD-negative AML patients were sampled between 2010 and 2013, and the occurrence of PRL-3 hyperexpression in FLT3-ITD-negative AML was evaluated by multivariate probit regression analysis. Overexpression or depletion of endogenous PRL-3 expression with the specific small interfering RNAs was performed to investigate the role of PRL-3 in AML progression. Xenograft models were also used to confirm the oncogenic role of PRL-3. RESULTS Compared to healthy donors, PRL-3 is upregulated more than 3-fold in 40.2% of FLT3-ITD-negative AML patients. PRL-3 expression level is adversely correlated to the overall survival of the AML patients, and the AML relapses accompany with re-upregulation of PRL-3. Mechanistically, aberrant PRL-3 expression promoted cell cycle progression and enhanced the antiapoptotic machinery of AML cells to drug cytotoxicity through downregulation of p21 and upregulation of Cyclin D1 and CDK2 and activation of STAT5 and AKT. Depletion of endogenous PRL-3 sensitizes AML cells to therapeutic drugs, concomitant with apoptosis by upregulation of cleaved PARP (poly ADP ribose polymerase) and apoptosis-related caspases. Xenograft assays further confirmed PRL-3's oncogenic role in leukemogenesis. CONCLUSIONS Our results demonstrated that PRL-3 is a novel independent crucial player in both FLT3-ITD-positive and FLT3-ITD-negative AML and could be a potential therapeutic target. Cancer 2014;120:2130-2141. © 2014 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. [ABSTRACT FROM AUTHOR]