Pathways activated downstream of constitutively active phosphatidylinositol (PI) 3-kinase in PTEN-deficient prostate cancer (PCa) cells are possible therapeutic targets. We found that the nonreceptor ...Tec family tyrosine kinase Bmx/Etk was activated by tyrosine phosphorylation downstream of Src and PI 3-kinase in PTEN-deficient LNCaP and PC3 PCa cells and that Bmx down-regulation by short interfering RNA markedly inhibited LNCaP cell growth. Bmx also associated with ErbB3 in LNCaP cells, and heregulin-β1 enhanced this interaction and further stimulated Bmx activity. Epidermal growth factor (EGF) similarly stimulated an interaction between Bmx and EGF receptor and rapidly increased Bmx kinase activity. Bmx stimulation in response to heregulin-β1 and EGF was Src-dependent, and heregulin-β1 stimulation of Bmx was also PI 3-kinase-dependent. In contrast, the rapid tyrosine phosphorylation and activation of Bmx in response to EGF was PI 3-kinase-independent. Taken together, these results demonstrate that Bmx is a critical downstream target of the constitutively active PI 3-kinase in PTEN-deficient PCa cells and further show that Bmx is recruited by the EGF receptor and ErbB3 and activated in response to their respective ligands. Therefore, Bmx may be a valuable therapeutic target in PCa and other epithelial malignancies in which PI 3-kinase or EGF receptor family pathways are activated.
Novel Approach to Ultrasound‐Guided Thoracostomy Taylor, Lindsay A.; Stenberg, Robert; Tozer, Jordan ...
Journal of ultrasound in medicine,
March 2022, 2022-Mar, 2022-03-00, 20220301, Letnik:
41, Številka:
3
Journal Article
Recenzirano
Objectives
Thoracostomy is often a required treatment in patients with thoracic trauma; however, performing a thoracostomy using traditional techniques can have complications. Ultrasound can be a ...beneficial tool for identifying the correct thoracostomy insertion site. We designed a randomized prospective study to assess if ultrasound guidance can improve thoracostomy site identification over traditional techniques.
Methods
Emergency medicine residents were randomly assigned to use palpation or ultrasound to identify a safe insertion site for thoracostomy placement. The target population comprised of hemodynamically stable trauma patients who received an extended focused assessment with sonography for trauma (EFAST) and a chest computed tomography (CT) exam. The resident placed a radiopaque marker on the skin of the patient where a safe intercostal space was believed to be located, either by palpation or ultrasound. Clinical ultrasound faculty reviewed the CT to confirm marker placement relative to the diaphragm. A Fischer's exact test was used to analyze the groups.
Results
One hundred and forty‐seven patients were enrolled in the study, 75 in the ultrasound group and 72 in the landmark group. This resulted in the placement of 271 total thoracostomy site markers, 142 by ultrasound and 129 by palpation and landmarks. The ultrasound group correctly identified thoracostomy insertion sites above the diaphragm in 97.2% (138/142) of patients, while the palpation group identified a safe insertion site in 88.4% (114/129) of patients (P = .0073).
Conclusion
This study found that emergency medicine residents are more likely to identify a safe tube thoracostomy insertion site in trauma patients by using ultrasound, as compared to using landmarks and palpation.
Bromodomain and extra-terminal domain proteins are promising epigenetic anticancer drug targets. This first-in-human study evaluated the safety, recommended phase II dose, pharmacokinetics, ...pharmacodynamics, and preliminary antitumor activity of the bromodomain and extra-terminal domain inhibitor molibresib (GSK525762) in patients with nuclear protein in testis (NUT) carcinoma (NC) and other solid tumors.
This was a phase I and II, open-label, dose-escalation study. Molibresib was administered orally once daily. Single-patient dose escalation (from 2 mg/d) was conducted until the first instance of grade 2 or higher drug-related toxicity, followed by a 3 + 3 design. Pharmacokinetic parameters were obtained during weeks 1 and 3. Circulating monocyte chemoattractant protein-1 levels were measured as a pharmacodynamic biomarker.
Sixty-five patients received molibresib. During dose escalation, 11% experienced dose-limiting toxicities, including six instances of grade 4 thrombocytopenia, all with molibresib 60-100 mg. The most frequent treatment-related adverse events of any grade were thrombocytopenia (51%) and gastrointestinal events, including nausea, vomiting, diarrhea, decreased appetite, and dysgeusia (22%-42%), anemia (22%), and fatigue (20%). Molibresib demonstrated an acceptable safety profile up to 100 mg; 80 mg once daily was selected as the recommended phase II dose. Following single and repeat dosing, molibresib showed rapid absorption and elimination (maximum plasma concentration: 2 hours; t
: 3-7 hours). Dose-dependent reductions in circulating monocyte chemoattractant protein-1 levels were observed. Among 19 patients with NC, four achieved either confirmed or unconfirmed partial response, eight had stable disease as best response, and four were progression-free for more than 6 months.
Once-daily molibresib was tolerated at doses demonstrating target engagement. Preliminary data indicate proof-of-concept in NC.
Recombinant agonists that activate co-stimulatory and cytokine receptors have shown limited clinical anticancer utility, potentially due to narrow therapeutic windows, the need for coordinated ...activation of co-stimulatory and cytokine pathways and the failure of agonistic antibodies to recapitulate signaling by endogenous ligands. RTX-240 is a genetically engineered red blood cell expressing 4-1BBL and IL-15/IL-15Rα fusion (IL-15TP). RTX-240 is designed to potently and simultaneously stimulate the 4-1BB and IL-15 pathways, thereby activating and expanding T cells and NK cells, while potentially offering an improved safety profile through restricted biodistribution. We assessed the ability of RTX-240 to expand and activate T cells and NK cells and evaluated the in vivo efficacy, pharmacodynamics and tolerability using murine models. Treatment of PBMCs with RTX-240 induced T cell and NK cell activation and proliferation. In vivo studies using mRBC-240, a mouse surrogate for RTX-240, revealed biodistribution predominantly to the red pulp of the spleen, leading to CD8 + T cell and NK cell expansion. mRBC-240 was efficacious in a B16-F10 melanoma model and led to increased NK cell infiltration into the lungs. mRBC-240 significantly inhibited CT26 tumor growth, in association with an increase in tumor-infiltrating proliferating and cytotoxic CD8 + T cells. mRBC-240 was tolerated and showed no evidence of hepatic injury at the highest feasible dose, compared with a 4-1BB agonistic antibody. RTX-240 promotes T cell and NK cell activity in preclinical models and shows efficacy and an improved safety profile. Based on these data, RTX-240 is now being evaluated in a clinical trial.
Phosphoinositide kinases Carpenter, Christopher L; Cantley, Lewis C
Current opinion in cell biology,
04/1996, Letnik:
8, Številka:
2
Journal Article
Recenzirano
Recently, a number of cDNA clones with homology to the catalytic subunit of phosphoinositide 3-kinase have been identified, and the sequence of the first cDNA clone encoding a phosphatidylinositol ...4-phosphate 5-kinase has been published. Use of both dominant-negative mutants of phosphoinositide 3-kinase and the inhibitors wortmannin and LY294002 has identified a number of processes in which phosphoinositide 3-kinase participates, including cell motility, the Ras pathway, vesicle trafficking and secretion, and apoptosis. Several possible biochemical targets of phosphoinositides have been found.
Intracellular signaling by most cell surface receptors requires the generation of two major second messengers, phosphatidylinositol-3,4,5-trisphosphate (PtdIns-3,4,5-P3) and ...inositol-1,4,5-trisphosphate (IP3). The enzymes that produce these second messengers, phosphoinositide 3-kinase (PI3K) and phospholipase C (PLC), utilize a common substrate, phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P2). Until now, it has not been clear whether de novo PtdIns-4,5-P2 synthesis is necessary for PtdIns-3,4,5-P3 and IP3 production. Here we show that BTK, a member of the Tec family of cytoplasmic protein tyrosine kinases, associates with phosphatidylinositol-4-phosphate 5-kinases (PIP5Ks), the enzymes that synthesize PtdIns-4,5-P2. Upon B cell receptor activation, BTK brings PIP5K to the plasma membrane as a means of generating local PtdIns-4,5-P2 synthesis. This enzyme-enzyme interaction provides a shuttling mechanism that allows BTK to stimulate the production of the substrate required by both its upstream activator, PI3K, and its downstream target, PLC-gamma2.
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) plays a central role in regulating the actin cytoskeleton as a substrate for phosphoinositide 3-kinase and phospholipase C as well as by binding ...directly to proteins that control the processes of actin monomer sequestration, filament severing, capping, nucleation, cross-linking, and bundling (Ma, L., Cantley, L. C., Janmey, P. A., and Kirschner, M. W. (1998) J. Cell Biol. 140, 1125–1136; Hinchliffe, K. (2000) Curr. Biol. 10, R104–R1051). Three related phosphatidylinositol 4-phosphate 5-kinases (PI(4)P 5-kinases) have been identified in mammalian cells (types Iα, Iβ, and Iγ) and appear to play distinct roles in actin remodeling. Here we have identified a fourth member of this family by searching the human genome and EST data bases. This new protein, which we have designated phosphatidylinositol phosphate kinase homolog (PIPKH), is expressed at relatively high levels in brain and testis. Immunoprecipitates of PIPKH expressed in mammalian cells contain PI(4)P 5-kinase activity, but this activity is not affected by mutations in residues that inactivate other type I PI(4)P 5-kinases. We show that the PI(4)P 5-kinase activity in PIPKH immunoprecipitates can be explained by the ability of PIPKH to heterodimerize with other type I PI(4)P 5-kinases. Transfection of 293t cells with PIPKH resulted in >8-fold increase in total phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) without a significant net increase in total PI(4,5)P2. When coexpressed with PIPKH, green fluorescent protein (GFP) fusion construct of the pleckstrin homology domain from Bruton's tyrosine kinase (GFP-BTK-PH) localized in intracellular vesicular structures, suggesting an unusual intracellular site of PI(3,4,5)P3 production. Finally, expression of PIPKH induced the reorganization of actin from predominantly stress fibers to predominantly foci and comets similar to those observed previously in cells infected with the intracellular pathogen Listeria or transfected with recombinant PIPKIα. These results suggest that PIPKH acts as a scaffold to localize and regulate type I PI(4)P 5-kinases and the synthesis of PI(3,4,5)P3.
Rho family GTPases appear to play an important role in the regulation of the actin cytoskeleton, but the mechanism of regulation is unknown. Since phosphoinositide 3-kinase and phosphatidylinositol ...4,5-bisphosphate have also been implicated in actin reorganization, we investigated the possibility that Rho family members interact with phosphoinositide kinases. We found that both GTP- and GDP-bound Rac1 associate with phosphatidylinositol-4-phosphate 5-kinase in vitro and in vivo. Phosphoinositide 3-kinase also bound to Rac1 and Cdc42Hs, and these interactions were GTP-dependent. Stimulation of Swiss 3T3 cells with platelet-derived growth factor induced the association of PI 3-kinase with Rac in immunoprecipitates. PI 3-kinase activity was also detected in Cdc42 immunoprecipitates from COS7 cells. These results suggest that phosphoinositide kinases are involved in Rho family signal transduction pathways and raise the possibility that the effects of Rho family members on the actin cytoskeleton are mediated in part by phosphoinositide kinases.
Inactivating mutations in the serine-threonine kinase LKB1 (STK11) are found in most patients with Peutz-Jeghers syndrome; however the function of LKB1 is unknown. We found that LKB1 binds to and ...regulates brahma-related gene 1 (Brg1), an essential component of chromatin remodeling complexes. The association requires the N terminus of LKB1 and the helicase domain of Brg1 and LKB1 stimulates the ATPase activity of Brg1. Brg1 expression in SW13 cells induces the formation of flat cells indicative of cell cycle arrest and senescence. Expression of a kinase-dead mutant of LKB1, SL26, in SW13 cells blocks the formation of Brg1-induced flat cells, indicating that LKB1 is required for Brg1-dependent growth arrest. The inability of mutants of LKB1 to mediate Brg1-dependent growth arrest may explain the manifestations of Peutz-Jeghers syndrome.
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