Project description:Mutations in the core RNA splicing factor SF3B1 are prevalent in leukemias and uveal melanoma, but also recurrent in epithelial malignancies such as breast cancer. Whereas hotspot mutations in SF3B1 alter hematopoietic differentiation, whether SF3B1 mutations contribute to epithelial cancer development and progression is unknown. Here, we identify that SF3B1 mutations in mammary epithelial and breast cancer cells induce a recurrent pattern of aberrant splicing leading to activation of AKT and NF-kB, enhanced cell migration, and accelerated tumorigenesis. Transcriptomic analysis of human cancer specimens, MMTV-cre Sf3b1K700E/WT mice, and isogenic mutant cell lines identified hundreds of aberrant 3’ splice sites induced by mutant SF3B1, a portion of which were breast-specific. Across mouse and human tumors, mutant SF3B1 promoted aberrant splicing (dependent on aberrant branchpoints as well as pyrimidines downstream of the aberrant branchpoint) and consequent suppression of PPP2R5A and MAP3K7, critical negative regulators of AKT and NF-kB. Coordinate activation of NF-kB and AKT signaling was observed in the knock-in models, leading to accelerated cell migration and tumor development in combination with mutant PIK3CA but also hypersensitizing cells to AKT kinase inhibitors. These data identify mutations in SF3B1 as drivers of breast tumorigenesis and reveal unique vulnerabilities in cancers harboring them.
Project description:Cavin-3 is a tumor suppressor protein of unknown function. Using a combination of in vivo knockout and in vitro gain/loss of function approaches, we show that cavin-3 dictates the balance between ERK and Akt signaling. Loss of cavin-3 increases Akt signaling at the expense of ERK, while gain of cavin-3 increases ERK signaling at the expense Akt. Cavin-3 facilitates signal transduction to ERK by anchoring caveolae, a lipid-raft specialization that contains an ERK activation module, to the membrane skeleton of the plasma membrane. Loss of cavin-3 reduces the number of caveolae, thereby separating this ERK activation module from signaling receptors. Loss of cavin-3 promotes Akt signaling through suppression of EGR1 and PTEN. The in vitro consequences of the loss of cavin-3 include induction of Warburg metabolism (aerobic glycolysis), accelerated cell proliferation and resistance to apoptosis. The in vivo consequences of cavin-3 loss are increased lactate production and cachexia. 9 total samples, consisting of 3 cavin-3 siRNA groups (0 days, 3 days and 8 days) one set was untreated, one set was serum starved, one set was serum starved and then treated with EGF for 1 hr.
Project description:This phase II clinical trial studies how well Akt inhibitor MK2206 works in treating patients with relapsed lymphoma. Akt inhibitor MK2206 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.
Project description:Biliary tract cancer (BTC) has poor prognosis. The Notch receptor is aberrantly expressed in extrahepatic cholangiocarcinoma (eCCA). However, the role of Notch signaling in the initiation and progression of eCCA and gallbladder (GB) cancer remains unknown. We investigated the functional role of Notch signaling during tumorigenesis of the extrahepatic bile duct and GB. We demonstrated that simultaneous activation of the Kras–Akt and Notch pathways in EHBD and GB resulted in the formation of BilINs and biliary cancer in a mouse model. Mechanistically, the Kras/Notch–Myc axis activates mTORC1 through phosphorylation of TSC2 in biliary tumorigenesis.
Project description:AKT is involved in a number of key cellular processes including cell proliferation, apoptosis and metabolism. Hyperactivation of AKT is associated with many pathological conditions, particularly cancers. Emerging evidence indicates that arginine methylation is involved in modulating AKT signaling pathway. However, whether and how arginine methylation directly regulates AKT kinase activity remain unknown. Here we report that protein arginine methyltransferase 5 (PRMT5), but not other PRMTs, promotes AKT activation by catalyzing symmetric dimethylation of AKT1 at arginine 391 (R391). Mechanistically, AKT1-R391 methylation cooperates with phosphatidylinositol 3,4,5 trisphosphate (PIP3) to relieve the pleckstrin homology (PH)-in conformation, leading to AKT1 membrane translocation and subsequent activation by phosphoinositide-dependent kinase-1 (PDK1) and the mechanistic target of rapamycin complex 2 (mTORC2). As a result, deficiency in AKT1-R391 methylation significantly suppresses AKT1 kinase activity and tumorigenesis. Lastly, we show that PRMT5 inhibitor synergizes with AKT inhibitor or chemotherapeutic drugs to enhance cell death. Altogether, our study suggests that R391 methylation is an important step for AKT activation and its oncogenic function.
Project description:Aberrant activation of AKT is a key oncogenic driver in hepatocellular carcinoma (HCC). As AKT activates multiple downstream signaling pathways, the key mechanisms mediating AKT-driven tumorigenesis must be elucidated to develop optimal treatment strategies. Using an Akt/NRas-induced HCC mouse model, we found that AKT promotes tumorigenesis by targeting TSC2 and GSK3α&β rather than FOXO family members. Loss of either TSC2, leading to mTORC1 activation, or both GSK3 isoforms cooperated with activated NRAS to promote HCC formation in vivo, albeit with different latencies. Simultaneous TSC2 and GSK3α&β deletion cooperated with NRAS to rapidly induce HCC formation, mirroring observations from the Akt/NRas HCC model. RNA-seq studies indicated distinct pathways regulated by TSC2/mTORC1 and GSK3α&β during hepatocarcinogenesis, with FOXM1 functioning as a major effector of GSK3. In summary, these findings uncover AKT’s role in suppressing the TSC complex and GSK3 to drive HCC, offering mechanistic insights into oncogenic signaling and potential therapeutic targets.
Project description:Inherited mutation in LKB1 results in the Peutz-Jeghers syndrome (PJS), characterized by intestinal hamartomas and a modestly increased frequency of gastrointestinal and breast cancer1. Somatic inactivation of LKB1 occurs in human lung adenocarcinoma2-4, but its tumor suppressor role in this tissue is unknown. Here we show that somatic Lkb1 deficiency strongly cooperates with somatic K-rasG12D activating mutation to accelerate the development of mouse lung tumorigenesis. Lkb1 deficiency in the setting of K-rasG12D mutation (K-ras Lkb1L/L) was associated with decreased tumor latency and increased tumor aggressiveness including metastasis. Furthermore, tumors from K-ras Lkb1L/L mice demonstrated histologies--squamous, adenosquamous and large cell--not seen with K-rasG12D mutation, Ink4a/Arf inactivation, or p53 inactivation alone or in combination. Experiments in vitro suggest that LKB1 suppresses lung tumorigenesis and progression through both p16INK4a-ARF-p53 dependent and independent mechanisms. These data indicate that LKB1 regulates lung tumor progression and differentiation. Keywords: cancer research To analyze the role of LKB1 in lung cancer progression and differentiation, we have dissected the lung tumors from mice with/without lkb1 loss and performed the microarray analyses to compare their gene expression pattern. In addition, we have also performed microarray analysis in both A549 and H2126 cell lines after reconsistitution of either wt-lkb1 or the kinase dead form of lkb1 (lkb1-KD) to confirm what we observed from in vivo studies.
Project description:Aberrant activation of AKT is a key oncogenic driver in hepatocellular carcinoma (HCC). As AKT activates multiple downstream signaling pathways, the key mechanisms mediating AKT-driven tumorigenesis must be elucidated to develop optimal treatment strategies. Using an Akt/NRas-induced HCC mouse model, we found that AKT promotes tumorigenesis by targeting TSC2 and GSK3α&β rather than FOXO family members. Loss of either TSC2, leading to mTORC1 activation, or both GSK3 isoforms cooperated with activated NRAS to promote HCC formation in vivo, albeit with different latencies. Simultaneous TSC2 and GSK3α&β deletion cooperated with NRAS to rapidly induce HCC formation, mirroring observations from the Akt/NRas HCC model. RNA-seq studies indicated distinct pathways regulated by TSC2/mTORC1 and GSK3α&β during hepatocarcinogenesis, with FOXM1 functioning as a major effector of GSK3. In summary, these findings uncover AKT’s role in suppressing the TSC complex and GSK3 to drive HCC, offering mechanistic insights into oncogenic signaling and potential therapeutic targets.
Project description:This phase II clinical trial studies how well Akt inhibitor MK2206 works in treating patients with advanced gastric or gastroesophageal junction cancer. Akt inhibitor MK2206 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.