The Role of PI3K in Met Driven Cancer: A Recap

The Receptor Tyrosine Kinase (RTK) Met, overexpressed or mutated in cancer, plays a major role in cancer progression and represents an attractive target for cancer therapy. However RTK inhibitors can lead to drug resistance, explaining the necessity to develop therapies that target downstream signaling. Phosphatidylinositide 3-kinase (PI3K) is one of the most deregulated pathways in cancer and implicated in various types of cancer. PI3K signaling is also a major signaling pathway downstream of RTK, including Met. PI3K major effectors include Akt and “mechanistic Target of Rapamycin” (mTOR), which each play key roles in numerous and various cell functions. Advancements made due to the development of molecular and pharmaceutical tools now allow us to delve into the roles of each independently. In this review, we summarize the current understanding we possess of the activation and role of PI3K/Akt/mTOR, downstream of Met, in cancer

Understanding and targeting PI3K downstream of oncogenic Met mutant

PhDThe Receptor Tyrosine Kinase (RTK) Met, overexpressed or mutated in cancer, plays a major role in cancer progression and represents an attractive target for cancer therapy. This study aimed to investigate whether PI3K plays a role in Met oncogenicity. Three cell models were used: (i) NIH3T3 cells expressing WT Met or the constitutively active mutant M1268T Met; (ii) U87MG glioblastoma cells, with endogenous WT Met constitutively activated due to an autocrine loop; (iii) A549 lung cancer cells expressing endogenous WT Met, activated upon binding exogenous HGF. Met dependent Rac1 translocation to the plasma membrane, actin cytoskeleton organisation, cell migration, anchorage independent growth in soft agar and tumour growth were studied in the presence of inhibitors of pan-PI3K / mTOR, various PI3K Class I isoforms, mTOR or Akt, or following siRNA knock-down of PI3K isoforms. We report that PI3K class I (but not class III) regulates Met dependent cell migration. The PI3K class I isoforms required varies among the cell models. Interestingly, the combined inhibition of all p110 Class I isoforms lead to the strongest reduction of Met dependent cell migration. Met dependent phosphorylation of Akt, an effector of PI3K class I, is reduced upon endocytosis inhibition, suggesting that Met signals to PI3K Class I on endosomes. Our results indicate that mTOR is responsible for Met dependent anchorage independent growth and tumour growth in vivo. Surprisingly, PI3K class I (and class III) are not required. Moreover, Rac1 is required for Met dependent mTOR activation, (phosphorylation of mTORC1’s effector, p70 S6K) subcellular translocation of mTOR and anchorage independent growth. Finally, our results suggest that this Met-Rac1- mTOR pathway occurs on endosomes. Thus while PI3K class I regulates Met dependent cell migration, mTOR regulates Met driven anchorage independent growth and in vivo tumorigenesis. Thus PI3K Class I / mTOR may be targeted in Met driven cancers

The Role of PI3K in Met Driven Cancer: A Recap

The Receptor Tyrosine Kinase (RTK) Met, overexpressed or mutated in cancer, plays a major role in cancer progression and represents an attractive target for cancer therapy. However RTK inhibitors can lead to drug resistance, explaining the necessity to develop therapies that target downstream signaling. Phosphatidylinositide 3-kinase (PI3K) is one of the most deregulated pathways in cancer and implicated in various types of cancer. PI3K signaling is also a major signaling pathway downstream of RTK, including Met. PI3K major effectors include Akt and "mechanistic Target of Rapamycin" (mTOR), which each play key roles in numerous and various cell functions. Advancements made due to the development of molecular and pharmaceutical tools now allow us to delve into the roles of each independently. In this review, we summarize the current understanding we possess of the activation and role of PI3K/Akt/mTOR, downstream of Met, in cancer

Front face fluorescence spectroscopy and multiway analysis for process control and NFC prediction in industrially processed cookies

The aim of this work was to evaluate the potential of using front face fluorescence spectroscopy for rapid quantitative estimation of neoformed contaminants in industrially processed cookies. Two dimensional synchronous front face fluorescence spectra were acquired on cookies to assess the industrial process impact on the fluorescence signal and predict the neoformed contaminants content in cookies. The signal was recorded on two types of cookies; 41 samples taken from different steps of four industrial production lines and 148 cookie samples produced from experimental baking using three different temperatures with two levels of fat saturation and two types of sugar used in the formulation. After spectral pre-treatment of the acquired front face fluorescence spectroscopy data, the multiway arrays were decomposed by means of PARAFAC models. Factors extracted from the decompositions allowed identification of the main front face fluorescence spectroscopy profiles in cookies. These included native tryptophan and riboflavin, and several fluorescence profiles attributed to fat oxidation and Maillard reaction compounds. Relative intensities of the samples fluorescence profiles were then used to discriminate critical steps in the industrial baking process and to predict the content of chromatographically measured neoformed contaminants hydroxymethylfurfural, carboxymethyllysine and acrylamide in the cookies. The effects of spectral pre-treatments on decomposition and regression results were also studied. The results show that process control and neoformed contaminants estimation in industrially processed cookies can be achieved by means of front face fluorescence spectroscopy information

The thermolysin-like metalloproteinase and virulence factor LasB from pathogenic Pseudomonas aeruginosa induces anoikis of human vascular cells.

International audienceDisruption of cell/ECM interactions resulting from uncontrolled pericellular proteolysis leads to detachment-induced cell apoptosis (anoikis), contributing to the morbid evolution of inflammatory vascular diseases. During cardiovascular infections, bacterial proteinases might induce vascular cells to enter a similar pathway. We focused on LasB, the predominant metalloproteinase secreted by the haematotropic pathogen Pseudomonas aeruginosa. While the exosecretome of the LasB-deficient pseudomonal strain PAO1lasB? had limited impact on human vascular cell adherence and viability, secretomes from the LasB-expressing reference strain, PAO1, or clinical isolates from patients with cardiac infection all induced anoikis, as did purified LasB. Immunofluorescence and/or immunoblotting analysis of heart valve myofibroblast cultures or whole tissue revealed an extensive, LasB-dependent degradation of ECM-associated fibronectin and vitronectin, that preceded cell de-adherence, whereas type I collagen showed limited degradation. Moreover, LasB produced a rapid endoproteolysis of the cell-associated urokinase receptor/uPAR, leaving a truncated receptor that is unable to support cell adherence and survival via interactions with vitronectin and integrins. Conversely, major myofibroblast integrins showed no or only minor alterations. Thus, among P. aeruginosa-secreted metalloproteinases, LasB can induce vascular cell anoikis through simultaneous proteolysis of ECM components and cell receptors, suggesting the uPAR-vitronectin axis as a major target in this process

Native size exclusion chromatography-based mass spectrometry (SEC-MS) reveals new components of the early Heat Shock Protein 90 inhibition response among limited global changes

The molecular chaperone heat shock protein 90 (HSP90) works in concert with co-chaperones to stabilize its client proteins, which include multiple drivers of oncogenesis and malignant progression. Pharmacologic inhibitors of HSP90 have been observed to exert a wide range of effects on the proteome, including depletion of client proteins, induction of heat shock proteins, dissociation of co-chaperones from HSP90, disruption of client protein signaling networks, and recruitment of the protein ubiquitylation and degradation machinery-suggesting widespread remodeling of cellular protein complexes. However, proteomics studies to date have focused on inhibitor-induced changes in total protein levels, often overlooking protein complex alterations. Here, we use size-exclusion chromatography in combination with mass spectrometry (SEC-MS) to characterize the early changes in native protein complexes following treatment with the HSP90 inhibitor tanespimycin (17-AAG) for 8 h in the HT29 colon adenocarcinoma cell line. After confirming the signature cellular response to HSP90 inhibition (e.g., induction of heat shock proteins, decreased total levels of client proteins), we were surprised to find only modest perturbations to the global distribution of protein elution profiles in inhibitor-treated HT29 cells at this relatively early time-point. Similarly, co-chaperones that co-eluted with HSP90 displayed no clear difference between control and treated conditions. However, two distinct analysis strategies identified multiple inhibitor-induced changes, including known and unknown components of the HSP90-dependent proteome. We validate two of these-the actin-binding protein Anillin and the mitochondrial isocitrate dehydrogenase 3 complex-as novel HSP90 inhibitor-modulated proteins. We present this dataset as a resource for the HSP90, proteostasis, and cancer communities (https://www.bioinformatics.babraham.ac.uk/shiny/HSP90/SEC-MS/), laying the groundwork for future mechanistic and therapeutic studies related to HSP90 pharmacology. Data are available via ProteomeXchange with identifier PXD033459