Uncoupling protein 2 (UCP2) is a mitochondrial anion carrier which plays a key role in energy homeostasis. UCP2 is deregulated in several human cancers and has been suggested to regulate cancer metabolism. However, the role of UCP2 in gallbladder cancer has not been defined.Using clinical samples, we found highly expressed UCP2 in gallbladder cancer tissues, and higher expression levels of UCP2 correlated with worse clinical characteristics. To study whether UCP2 promotes gallbladder cancer growth, UCP2 stable knockdown cells were generated, and cell proliferation was suppressed in these knockdown cells. Further studies demonstrated that glycolysis was inhibited and IKKβ, as well as the downstream signaling molecules NF-κB/FAK/ β-catenin, were downregulated in UCP2 knockdown cells. More importantly, gallbladder cancer cells became sensitive to gemcitabine treatments when UCP2 was inhibited. UCP2 knockdown suppressed the activation of the NF-κB/β-catenin axis and promoted the increases in mitochondrial ROS in gallbladder cancer cells exposed to gemcitabine treatments. The UCP2 inhibitor genipin suppressed xenograft tumor growth and sensitized grafted tumors to gemcitabine treatments. These results suggest targeting UCP2 as a novel therapeutic strategy for the treatment of gallbladder cancer.
BACKGROUND After long-term androgen deprivation therapy, 25-30% prostate cancer (PCa) acquires an aggressive neuroendocrine (NE) phenotype. Dysregulation of YAP1, a key transcription coactivator of the Hippo pathway, has been related to cancer progression. However, its role in neuroendocrine prostate cancer (NEPC) has not been assessed. METHODS Immunohistochemistry was used to evaluate YAP1 protein levels during PCa initiation and progression. YAP1 knockdown and luciferase reporter assays were used to evaluate the ability of YAP1 to modulate Wnt/beta-Catenin signaling. RESULTS YAP1 expression was present in the basal epithelial cells in benign prostatic tissues, lost in low grade PCa, but elevated in high grade prostate adenocarcinomas. Interestingly, the expression of YAP1 was reduced/lost in both human and mouse NEPC. Finally, YAP1 knockdown in PCa cells activates Wnt/beta-Catenin signaling, which has been implicated in NE differentiation of PCa, supporting a functional involvement of the loss of YAP1 expression in NEPC development. CONCLUSIONS The expression of YAP1 is elevated in high grade prostate adenocarcinomas while lost in NEPC. Reduced YAP1 activates Wnt/beta-Catenin signaling in PCa cells. These results suggest that when applied to PCa patients, YAP1 inhibitors shall be used with caution.
Desmoplastic Small Round Cell Tumor (DSRCT) is a rare and aggressive malignant cancer caused by a chromosomal translocation t(11;22)(p13;q12) that produces an oncogenic transcription factor, EWSR1-WT1. EWSR1-WT1 is essential for the initiation and progression of DSRCT. However, the precise mechanism by which EWSR1-WT1 drives DSRCT oncogenesis remains unresolved. Through our integrative gene expression analysis, we identified Salt Inducible Kinase 1 (SIK1) as a direct target of EWSR1-WT1. SIK1 as a member of the AMPK related kinase is involved in many biological processes. We showed that depletion of SIK1 causes inhibition of tumor cell growth, similar to the growth inhibition observed when EWSR1-WT1 is depleted. We further showed that silencing SIK1 leads to cessation of DNA replication in DSRCT cells and inhibition of tumor growth in vivo. Lastly, combined inhibition of SIK1 and CHEK1with small molecule inhibitors, YKL-05-099 and prexasertib, respectively, showed enhanced cytotoxicity in DSRCT cells compared to inhibition of either kinases alone. This work identified SIK1 as a new potential therapeutic target in DSRCT and the efficacy of SIK1 inhibition may be improved when combined with other intervention strategies.
ABSTRACTBACKGROUNDAfter long-term androgen deprivation therapy, 25-30% prostate cancer (PCa) acquires an aggressive neuroendocrine (NE) phenotype. Dysregulation of YAP1, a key transcription coactivator of the Hippo pathway, has been related to cancer progression. However, its role in neuroendocrine prostate cancer (NEPC) has not been assessed.METHODSImmunohistochemistry was used to evaluate YAP1 protein levels during PCa initiation and progression. YAP1 knockdown and luciferase reporter assays were used to evaluate the ability of YAP1 to modulate Wnt/beta-Catenin signaling.RESULTSYAP1 expression was present in the basal epithelial cells in benign prostatic tissues, lost in low grade PCa, but elevated in high grade prostate adenocarcinomas. Interestingly, the expression of YAP1 was reduced/lost in both human and mouse NEPC. Finally, YAP1 knockdown in PCa cells activates Wnt/beta-Catenin signaling, which has been implicated in NE differentiation of PCa, supporting a functional involvement of the loss of YAP1 expression in NEPC development.CONCLUSIONSThe expression of YAP1 is elevated in high grade prostate adenocarcinomas while lost in NEPC. Reduced YAP1 activates Wnt/beta-Catenin signaling in PCa cells. These results suggest that when applied to PCa patients, YAP1 inhibitors shall be used with caution.
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