Project description:PKCe, an oncogenic member of the PKC family, is aberrantly overexpressed in epithelial cancers. To date, little is known about functional interactions of PKCe with other genetic alterations and the effectors of this kinase that contribute to its tumorigenic and metastatic phenotype. Here we demonstrate that PKCe cooperates with the loss of the tumor suppressor Pten for the development of prostate cancer in a mouse model. Mechanistic analysis revealed that PKCe overexpression and Pten loss individually and synergically cause a remarkable up-regulation in the production of the chemokine CXCL13. Notably, targeted disruption of CXCL13 or its receptor CXCR5 in prostate cancer cells impaired their migratory and tumorigenic properties. In addition to providing evidence for an autonomous vicious cycle driven by PKCe, our studies identified a compelling rationale for targeting the CXCL13:CXCR5 axis for prostate cancer treatment.
Project description:The PTEN tumor suppressor controls cell death and survival by regulating functions of various molecular targets. Whilst the role of PTEN lipid-phosphatase activity on PtdIns(3,4,5)P3 and inhibition of PI3K pathway is well characterized, the biological relevance of PTEN protein-phosphatase activity remains undefined. Using knock-in (KI) mice harbouring cancer-associated and functionally relevant missense mutations, we show that although loss of PTEN lipid-phosphatase function cooperates with oncogenic PI3K to promote rapid mammary tumorigenesis, the additional loss of PTEN protein-phosphatase activity triggered an extensive cell death response evident in early and advanced mammary tumors. Omics and drug-targeting studies revealed that PI3Ks act to reduce glucocorticoid receptor (GR) levels, which are rescued by loss of PTEN protein-phosphatase activity to restrain cell survival. The dual regulation of GR by PI3K and PTEN functions as a rheostat that can be exploited for the treatment of PTEN-loss driven cancers.
Project description:We previously found that loss of Plek2 decreased Akt activity and reverted disease phenotypes in hematopoietic system specific Pten knockout mice. Pten knockout mice also show prostate cancer phenotype. Using a well known Pten prostate-specific knockout mouse model, we found that loss of Plek2 also reverted tumorigenesis of prostate cancer via decreasing Akt pathway activity. Furthermore, we found that PLEK2 over-expression increased AKT pathway activity and promoted proliferation in 22RV1 cells which is a kind of prostate cancer cell line. To explore additional pathway which PLEK2 may involve in prostate cancer, we performed RNA sequencing in PLEK2 over-expressed and control 22RV1 cells.
Project description:Hyper-activation of the PI 3-Kinase/ AKT pathway is a driving force of many cancers. Here we identify the AKT-inactivating phosphatase PHLPP1 as a prostate tumor suppressor. We show that Phlpp1-loss causes neoplasia and, upon partial Pten-loss, carcinoma in mouse prostate. This genetic setting initially triggers a growth suppressive response via p53 and the Phlpp2 ortholog, and reveals spontaneous Trp53 inactivation as a condition for full-blown disease. Surprisingly, the co-deletion of PTEN and PHLPP1 in patient samples is highly restricted to metastatic disease and tightly correlated to deletion of TP53 and PHLPP2. These data establish a conceptual framework for progression of PTEN-mutant prostate cancer to life-threatening disease. To better assess the role of Phlpp in prostate we performed micorarray analysis of gene expression in the WT and Pten+/-; Phlpp1-/- mice.
Project description:From the analysis of all genes included in the array a number of individual genes were identified as dys-regulated in HIV-1 infected patients compared to healthy controls. In particular, increased CXCL13 expression in all individual patient samples. Abstract from publication: HIV-1 infection is associated with B-cell abnormalities such as hypergammaglobulinemia, poor immunisation responses and loss of serological memory. To determine whether altered expression of chemokine receptors and their ligands may play a role in B-cell dysfunctions during HIV-1 infection, the expression of CXCR4, CXCR5 and CCR7 receptors and their respective ligands on CD19+ B-cells were examined in HIV-1 infected patients and controls. We report a decreased CXCR5 expression on B-cells from patients (p<0.05), a phenomenon associated with a low CD4 T-cell count (<350 cells/µl). Interestingly, an increased expression of CXCL13, the ligand for CXCR5, was found in peripheral B-cells from HIV-1 infected patients. Moreover upon B-cell activation in vitro, CXCL13 was secreted in culture. In addition, CXCL13 positive B-cells were also found in the lymph nodes of HIV-1 infected patients, but not in control tissue. B-cell migration towards CXCL13, CXCL12 and CCL21, ligands for CXCR5, CXCR4 and CCR7, was also evaluated. In patients with a low CD4 Tcell count, migration towards all ligands was increased. Our findings indicate that altered expression of the chemokine receptor-ligand pair, CXCR5/CXCL13 may participate in the establishment of B-cell dysfunctions during HIV-1 infection. Total RNA was extracted from purified peripheral B-cells from 4 controls and 4 patients.
Project description:The PIP3/PI3K network is a central regulator of metabolism and is frequently activated in cancer, commonly by loss of the PIP3/PI(3,4)P2-phosphatase, PTEN. Despite huge investment, the drivers of the PI3K network in normal tissues and how they adapt to overactivation are unclear. We find that in healthy mouse prostate PI3K activity is driven by RTK/IRS signalling and constrained by pathway-feedback. In the absence of PTEN, the network is dramatically remodelled. A poorly understood, YXXM- and PIP3/PI(3,4)P2-binding PH domain-containing, adaptor, PLEKHS1, became the dominant activator and was required to sustain PIP3, AKT-phosphorylation and growth in PTEN-null prostate. This was because PLEKHS1 evaded pathway-feedback and experienced enhanced PI3K- and SRC-family kinase-dependent phosphorylation of Y258XXM, eliciting PI3K-activation. hPLEKHS1-mRNA and activating-Y419-phosphorylation of hSRC correlated with PI3K-pathway activity in human prostate cancers. We propose that in PTEN-null cells, receptor-independent, SRC-dependent tyrosine-phosphorylation of PLEKHS1 creates positive-feedback that escapes homeostasis, drives PIP3-signalling and supports tumour progression.
Project description:The PTEN tumor suppressor controls cell death and survival by regulating functions of various molecular targets. Whilst the role of PTEN lipid-phosphatase activity on PtdIns(3,4,5)P3 and inhibition of PI3K pathway is well characterized, the biological relevance of PTEN protein-phosphatase activity remains undefined. Using knock-in (KI) mice harbouring cancer-associated and functionally relevant missense mutations, we show that although loss of PTEN lipid-phosphatase function cooperates with oncogenic PI3K to promote rapid mammary tumorigenesis, the additional loss of PTEN protein-phosphatase activity triggered an extensive cell death response evident in early and advanced mammary tumors. Omics and drug-targeting studies revealed that PI3Ks act to reduce glucocorticoid receptor (GR) levels, which are rescued by loss of PTEN protein-phosphatase activity to restrain cell survival. The dual regulation of GR by PI3K and PTEN functions as a rheostat that can be exploited for the treatment of PTEN-loss driven cancers.
Project description:We used microarrays to analyze the global gene expression and identified differentially expressed gene list between wild-type anterior prostates and Pb-Cre4;PtenLoxP/LoxP anterior prostates, Pb-Cre4;PtenLoxP/LoxP;LrfLoxP/LoxP anterior prostates at 12 weeks of age. Prostate-specific Pten deletion (Pb-Cre4;PtenLoxP/LoxP) results in prostate intraepithelial neoplasia (PIN) which, following a long latency, can progress to high-grade adenocarcinoma, albeit with minimally invasive and metastatic features. However, inactivation of Lrf in the prostate epithelium in combination of Pten results in aggressive prostate tumors. To understand the molecular mechanisms by which loss of Lrf promotes Pten-loss-driven prostate tumorigenesis, we conducted transcriptome comparison of three wild-type anterior prostates, three Pb-Cre4;PtenLoxP/LoxP PIN, and three Pb-Cre4;PtenLoxP/LoxP;LrfLoxP/LoxP anterior prostate tumors.
Project description:Hyper-activation of the PI 3-Kinase/ AKT pathway is a driving force of many cancers. Here we identify the AKT-inactivating phosphatase PHLPP1 as a prostate tumor suppressor. We show that Phlpp1-loss causes neoplasia and, upon partial Pten-loss, carcinoma in mouse prostate. This genetic setting initially triggers a growth suppressive response via p53 and the Phlpp2 ortholog, and reveals spontaneous Trp53 inactivation as a condition for full-blown disease. Surprisingly, the co-deletion of PTEN and PHLPP1 in patient samples is highly restricted to metastatic disease and tightly correlated to deletion of TP53 and PHLPP2. These data establish a conceptual framework for progression of PTEN-mutant prostate cancer to life-threatening disease.
Project description:PTEN loss or PI3K/AKT signaling pathway activation correlates with human prostate cancer progression and metastasis. However, in preclinical murine models, deletion of Pten alone fails to mimic the significant metastatic burden that frequently accompanies the end stage of human disease. To identify additional pathway alterations that cooperate with PTEN loss in prostate cancer progression, we surveyed human prostate cancer tissue microarrays and found that the RAS/MAPK pathway is significantly elevated both in primary and metastatic lesions. In an attempt to model this event, we crossed conditional activatable K-rasG12D/WT mice with the prostate conditional Pten deletion model we previously generated. Although RAS activation alone cannot initiate prostate cancer development, it significantly accelerated progression caused by PTEN loss, accompanied by epithelial-to-mesenchymal transition (EMT) and macrometastasis with 100% penitence. A novel stem/progenitor subpopulation with mesenchymal characteristics was isolated from the compound mutant prostates, which was highly metastatic upon orthotopic transplantation. Importantly, inhibition of RAS/MAPK signaling by PD325901, a MEK inhibitor, significantly reduced the metastatic progression initiated from transplanted stem/progenitor cells. Collectively, these data indicate that activation of RAS/MAPK signaling serves as a potentiating second hit to alteration of the PTEN/PI3K/AKT axis and co-targeting both pathways is highly effective in preventing the development of metastatic prostate cancers. Murine mutants with prostate specific loss of Pten and K-ras activation (K-rasG12D) under regulation of the probasin promoter developed high grade, invasive prostate cancer. RNA was extracted from dissected prostate lobes from individual mutants with pathology thought to closely mimic human disease. Prostate tissue was subject to RNA extraction and hybridization on Affymetrix cDNA microarrays.