Project description:Purpose: The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study we investigated the potential of targeting the catalytic class IA PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types. Experimental Design: The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or down-regulation by small interfering RNA. Results: Over-expression of the PI3K isoforms p110α and p110β was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110α with RNA interference (RNAi) or selective pharmacological inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, while targeting p110β was less effective. Inhibition of p110α also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mammalian target of rapamycin (mTOR) pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). A DNA microarray analysis revealed that p110α inhibition profoundly affected the balance of pro- and anti-apoptotic Bcl-2 family proteins. Finally, p110α inhibition led to impaired SCLC tumor formation and vascularization in vivo. Conclusion: Together our data demonstrate the key involvement of the PI3K isoform p110α in multiple tumor-promoting processes in SCLC.
Project description:Purpose: The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study we investigated the potential of targeting the catalytic class IA PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types. Experimental Design: The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or down-regulation by small interfering RNA. Results: Over-expression of the PI3K isoforms p110 -alpha and p110-alpha was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110 -alpha with RNA interference (RNAi) or selective pharmacological inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, while targeting p110-alph was less effective. Inhibition of p110 -alpha also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mammalian target of rapamycin (mTOR) pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). A DNA microarray analysis revealed that p110-alpha inhibition profoundly affected the balance of pro- and anti-apoptotic Bcl-2 family proteins. Finally, p110 -alpha inhibition led to impaired SCLC tumor formation and vascularization in vivo. Conclusion: Together our data demonstrate the key involvement of the PI3K isoform p110 -alpha in multiple tumor-promoting processes in SCLC. 3 control samples, 3 samples for two treaments
Project description:Phosphoinositide 3-kinase (PI3K) signaling, which requires spatial compartmentalization in plasma membrane micro domains, is aberrantly activated in hepatocellular carcinoma (HCC). As a synthetic enzyme of sphingomyelin, sphingomyelin synthase 2 (SMS2) regulates membrane fluidity and microdomain structure. SMS2 functions in various diseases such as atherosclerosis, and diabetes and lung injury. However, the role of SMS2 in HCC tumorigenesis is unclear. In the present study, we found that SMS2 was substantially reduced in tumor tissues and predicted poor prognosis in HCC patients. Function assays in vitro showed that SMS2 could remarkably prevent cell proliferation, cell cycle, cell migration and invasion. Experiments in vivo revealed that SMS2-deficient mice exhibited more severe carcinogenesis and metastasis induced by diethylnitrosamine/carbon tetrachloride. The result of transcriptome sequencing showed that SMS2 was involved in PI3K/Akt signaling pathway. Further study verified that SMS2 could inhibit the expression of PI3K subunit p110α by promoting the ubiquitination of p110α. SMS2 downregulation changed lipid metabolism and PTEN distribution in lipid raft, attenuated p85α-PTEN interaction, thus promoting p85α-p110α interaction. Finally, we found that loss of SMS2 could inhibiting PTEN localization in lipid rafts. The tumor suppression effect of SMS2 on HCC cells could be rescued by p110α expression. Taken together, our findings not only demonstrates that SMS2 is a prospective tumor suppressor and prognosis indicator in HCC, but also provide understanding of the molecular mechanisms by which PI3K/AKT signaling is activated.
Project description:Although 3-Phosphoinositide-dependent protein kinase-1 (PDK1) has been predominately linked to PI3K-AKT pathway, it may also evoke additional signaling outputs to promote tumorigenesis. Here we report that PDK1 directly induces phosphorylation of Polo-like kinase 1 (PLK1), which in turn induces Myc phosphorylation and protein accumulation. We show that PDK1-PLK1-Myc signaling is critical for cancer cell growth and survival and small molecule inhibition of PDK1/PLK1 provides an effective approach for therapeutic targeting Myc-dependency. Intriguingly, PDK1-PLK1-Myc signaling induces an embryonic stem cell-like gene signature associated with aggressive tumor behaviors and is a robust signaling axis driving cancer stem cell (CSC) self renewal. Finally, we show that PLK1 inhibitor synergizes with mTOR inhibitor to induce synergistic anti-tumor effect in colorectal cancer by antagonizing a compensatory Myc induction. These findings identify a novel pathway in human cancer and CSC activation and provide a therapeutic strategy for targeting Myc-associated tumorigenesis and therapeutic resistance. Gene expression profiling of Human Embryonic Kidney Cells (HEK-TERV) under different conditions: PMN, PDK1, MYC and E545K
Project description:Pancreatic ductal adenocarcinoma is one of the most lethal cancers, with a 5 year-survival rate below 5%. Lack of curative treatment and failure of targeted therapies urge the need to identify novel efficient therapeutic strategy. Achievement of this goal will be obtained through the identification of diagnosis and prognosis biomarkers, identification of novel therapeutic targets and the knowledge of resistance mechanisms induced by these targeted therapies. PI3K/Akt/mTOR signalling, one of the most altered in cancers, is overactivated in pancreatic cancer and correlated with poor prognosis. In the Vertebrates, the family of class I phosphoinoitide-3-kinase (PI3K) includes four isoforms: p110α, p110β, p110δ and p110γ. Although they all perform the same biochemical reaction (phosphorylation of PIP2 in PIP3, a membrane lipid messenger), each isoform were demonstrated to have specific physiological roles. Global PI3K inhibitors are currently being tested in phase I/II clinical trials in advanced solid cancers, but show at maximal doses tolerated a limited therapeutic benefit. Isoform-selective PI3K inhibitors are currently the most promising agents because, at low doses, they are more efficient to inhibit one PI3K isoform, and thus, less toxic than pan-PI3K inhibitors. The objectives of this thesis are to determine isoform-specific PI3K roles and the therapeutic interest to target one or more isoforms in pancreatitis and PDAC, by the identification of isoform-specific pathways and the study of adaptive responses induced by targeting of one or all isoforms of PI3K. In a first part, my work has highlighted, validated and completed results obtained in the team, to demonstrate the significance of PI3K/Akt signalling in two physiological processes: chronic pancreatitis and initiation of pancreatic carcinogenesis. Precisely, the overactivation of PI3K/Akt pathway measured on human and murine chronic pancreatitis samples is correlated with a specific p110α activation gene expression signature. Moreover, genetic and pharmacologic inactivation of p110α during pancreatic chronic inflammation or cancerogenesis (by oncogenic Kras) prevents the formation of acino-ductal metaplasia, structures at the origin of pancreatic carcinogenesis initiation. Development of in vitro acino-ductal transdifferentiation protocol allowed me to demonstrate that only p110α is necessary at this initial step of pancreatic carcinogenesis by the regulation of Rho small GTPases, further regulating actin remodelling. In the second part, by a phosphoproteomic-based approach, I quantified PI3K downstream phosphorylation-regulated targets in a pancreatic cancer cell line treated or not by a pan- or selective PI3K inhibitor at different times. I demonstrated for the first time existence of targets, signalling pathways and adaptive responses regulated by each PI3K isoform. To conclude, all these results demonstrate the rational of combinatorial use of isoform-specific PI3K inhibitors in patients with pancreatic cancer for better clinical response
Project description:Metabolic reprogramming is a hallmark of cancer. Herein we discover that the key glycolytic enzyme pyruvate kinase M2 isoform (PKM2), but not the related isoform PKM1, is methylated by co-activator-associated arginine methyltransferase 1 (CARM1). PKM2 methylation reversibly shifts the balance of metabolism from oxidative phosphorylation to aerobic glycolysis in breast cancer cells. Oxidative phosphorylation depends on mitochondrial calcium concentration, which becomes critical for cancer cell survival when PKM2 methylation is blocked. By interacting with and suppressing the expression of inositol-1,4,5-trisphosphate receptors (InsP3Rs), methylated PKM2 inhibits the influx of calcium from the endoplasmic reticulum to mitochondria. Inhibiting PKM2 methylation with a competitive peptide delivered by nanoparticles perturbs the metabolic energy balance in cancer cells, leading to a decrease in cell proliferation, migration and metastasis. Collectively, the CARM1-PKM2 axis serves as a metabolic reprogramming mechanism in tumorigenesis, and inhibiting PKM2 methylation generates metabolic vulnerability to InsP3R-dependent mitochondrial functions.
Project description:Although 3-Phosphoinositide-dependent protein kinase-1 (PDK1) has been predominately linked to PI3K-AKT pathway, it may also evoke additional signaling outputs to promote tumorigenesis. Here we report that PDK1 directly induces phosphorylation of Polo-like kinase 1 (PLK1), which in turn induces Myc phosphorylation and protein accumulation. We show that PDK1-PLK1-Myc signaling is critical for cancer cell growth and survival and small molecule inhibition of PDK1/PLK1 provides an effective approach for therapeutic targeting Myc-dependency. Intriguingly, PDK1-PLK1-Myc signaling induces an embryonic stem cell-like gene signature associated with aggressive tumor behaviors and is a robust signaling axis driving cancer stem cell (CSC) self renewal. Finally, we show that PLK1 inhibitor synergizes with mTOR inhibitor to induce synergistic anti-tumor effect in colorectal cancer by antagonizing a compensatory Myc induction. These findings identify a novel pathway in human cancer and CSC activation and provide a therapeutic strategy for targeting Myc-associated tumorigenesis and therapeutic resistance.
Project description:Rationale: The acute respiratory distress syndrome is refractory to pharmacological intervention. Inappropriate activation of alveolar neutrophils is believed to underpin this disease’s complex pathophysiology, yet these cells have been little studied. Objectives: To examine the functional and transcriptional profiles of patient blood and alveolar neutrophils compared to healthy volunteer cells, and define their sensitivity to phosphoinositide 3-kinase inhibition. Methods: Twenty three ventilated patients underwent bronchoalveolar lavage. Alveolar and blood neutrophil apoptosis, phagocytosis and adhesion molecules were quantified by flow cytometry, and oxidase responses by chemiluminescence. Cytokine and transcriptional profiling utilized multiplex and GeneChip arrays. Measurements and Main Results: Patient blood and alveolar neutrophils were distinct from healthy circulating cells, with increased CD11b and reduced CD62L expression, delayed apoptosis and constitutively primed oxidase responses. Incubating control cells with disease bronchoalveolar lavage recapitulated the aberrant functional phenotype and this could be reversed by phosphoinositide 3-kinase inhibitors. In contrast, the pro-survival phenotype of patient cells was recalcitrant to phosphoinositide 3-kinase inhibition. RNA transcriptomic analysis revealed modified immune, cytoskeletal and cell death pathways in patient cells, aligning closely to sepsis and burns data sets but not with phosphoinositide 3-kinase signatures. Conclusions: Acute respiratory distress syndrome blood and alveolar neutrophils display a distinct primed, pro-survival profile and transcriptional signature. The enhanced respiratory burst was phosphoinositide 3-kinase-dependent, but delayed apoptosis and the altered transcriptional profile were not. These unexpected findings cast doubt over the utility of phosphoinositide 3-kinase inhibition in acute respiratory distress syndrome and highlight the importance of evaluating novel therapeutic strategies in patient-derived cells.
Project description:Cardiac hypertrophy can lead to heart failure, and is induced either by physiological stimuli eg postnatal development, chronic exercise training or pathological stimuli eg pressure or volume overload. Majority of new therapies for heart failure has mixed outcomes. A combined mouse model and oligo-array approach are used to examine whether phosphoinositide 3-kinase (p110-alpha isoform) activity is critical for maintenance of cardiac function and long-term survival in a setting of heart failure. The significance and expected outcome are to recognise genes involved in models of heart failure ie pathological- vs physiology-hypertrophy, and examine the molecular mechanisms responsible for such activity. Growth of the heart can be induced by physiological stimuli e.g., postnatal development, chronic exercise training, or pathological stimuli e.g., pressure or volume overload. Physiological hypertrophy (“good”) is characterised by a normal organisation of cardiac structure, and normal or enhanced cardiac function. In comparison, pathological hypertrophy (”bad”) is associated with fibrosis, cardiac dysfunction, and increased morbidity and mortality. The mechanistic process which allows the heart to enlarge in response to physiological stimuli while maintaining normal or enhanced function is of great clinical relevance because one potential therapeutic strategy is to inhibit the pathological growth process while augmenting the physiological growth process. One of the major process that regulate heart size is by phosphoinositide 3-kinase (PI3K). Thus the end goal of this project is to determine whether the p110 alpha isoform of PI3K could be a potential tool for augmenting physiological growth and improving cardiac function of the failing diseased heart, and to examine the underlying mechanisms responsible. Keywords: Disease progression analysis
Project description:Leukemia stem cells (LSCs) are responsible for the initiation, progression, and recurrence of leukemia. Targeting LSCs is thought as an effective way to cure leukemia, for which it is pivotal to identify novel therapeutic targets. The phosphoinositide 3-kinase (PI3K)/Akt signaling pathway is frequently activated in acute myeloid leukemia (AML) and strongly contributes to survival and proliferation of leukemia cells. Herein, we revealed that the p110γ isoform of PI3K was highly expressed in both mouse and human LSCs. Leukemogenesis was drastically delayed upon Pik3cg deletion during serial transplantations in murine acute myeloid leukemia models. Knockout of Pik3cg resulted in a remarkably impaired self-renewal, enhanced differentiation, and 32-fold reduced number of mouse acute myeloid LSCs. Interestingly, Pik3cg deficiency did not alter the functions of mouse hematopoietic stem cells. Mechanistically, PIK3CG/AKT/NRF2/PGD signaling axis controlled the pentose phosphate pathway to regulate redox metabolism and support nucleotide synthesis to maintain LSC fates. PIK3CG knockdown also led to a significant extended survival of recipients transplanted with human AML cells. Pharmaceutical inhibition of PIK3CG could efficiently restrain the progression of AML. PIK3CG may serve as a potential therapeutic target for the elimination of LSCs without influencing normal hematopoiesis.