35 research outputs found
Induction of Myogenesis in Mesenchymal Cells by MyoD Depends on Their Degree of Differentiation
No full textAbstractExpression of a transfected MyoD gene induces myogenic differentiation of most cell types. In this study, we evaluated the ability of an exogenous MyoD gene to induce myogenic conversion in two pairs of matched cell lines with different degrees of differentiation within either the osteoblastic or chondrocytic lineage. We show that osteoblasts and chondrocytes are resistant to the myogenic effects of MyoD alone. However, in their less-differentiated cell line counterparts, MyoD induces expression of muscle-cell-specific markers. Less-differentiated osteoblasts can be made resistant to MyoD-induced myogenic conversion by induction of adipogenic differentiation using dexamethasone. Finally, a dominant positive form of MyoD, one which is tethered to a partner, E47, activates muscle-specific gene expression in osteoblasts. Our results suggest that the response of a cell to MyoD depends on its lineage and its degree of differentiation. Furthermore, commitment of cells to the osteoblastic or chondrocytic lineage may involve inhibition of alternative pathways, such as those leading to myoblastic differentiation. Finally, osteoblasts may express a protein(s) which interferes with the activity of MyoD by inhibiting its association with E proteins. This interference can be overcome by expression of the MyoD–E47 hybrid, suggesting that osteoblasts are otherwise competent to undergo myogenic conversion
Expression of a Truncated, Kinase-Defective TGF-β Type II Receptor in Mouse Skeletal Tissue Promotes Terminal Chondrocyte Differentiation and Osteoarthritis
No full textTrotabresib, an oral potent bromodomain and extraterminal inhibitor, in patients with high-grade gliomas: A phase I, “window-of-opportunity” study
No full text20.500.12530/87912Background The bromodomain and extraterminal protein (BET) inhibitor trotabresib has demonstrated antitumor activity in patients with advanced solid tumors, including high-grade gliomas. CC-90010-GBM-001 (NCT04047303) is a phase I study investigating the pharmacokinetics, pharmacodynamics, and CNS penetration of trotabresib in patients with recurrent high-grade gliomas scheduled for salvage resection. Methods Patients received trotabresib 30 mg/day on days 1-4 before surgery, followed by maintenance trotabresib 45 mg/day 4 days on/24 days off after surgery. Primary endpoints were plasma pharmacokinetics and trotabresib concentrations in resected tissue. Secondary and exploratory endpoints included safety, pharmacodynamics, and antitumor activity. Results Twenty patients received preoperative trotabresib and underwent resection with no delays or cancelations of surgery; 16 patients received maintenance trotabresib after recovery from surgery. Trotabresib plasma pharmacokinetics were consistent with previous data. Mean trotabresib brain tumor tissue:plasma ratio was 0.84 (estimated unbound partition coefficient [K-PUU] 0.37), and modulation of pharmacodynamic markers was observed in blood and brain tumor tissue. Trotabresib was well tolerated; the most frequent grade 3/4 treatment-related adverse event during maintenance treatment was thrombocytopenia (5/16 patients). Six-month progression-free survival was 12%. Two patients remain on treatment with stable disease at cycles 25 and 30. Conclusions Trotabresib penetrates the blood-brain-tumor barrier in patients with recurrent high-grade glioma and demonstrates target engagement in resected tumor tissue. Plasma pharmacokinetics, blood pharmacodynamics, and safety were comparable with previous results for trotabresib in patients with advanced solid tumors. Investigation of adjuvant trotabresib + temozolomide and concomitant trotabresib + temozolomide + radiotherapy in patients with newly diagnosed glioblastoma is ongoing (NCT04324840)
WISP-1 Is an Osteoblastic Regulator Expressed During Skeletal Development and Fracture Repair
No full textVascular endothelial growth factor stimulates bone repair by promoting angiogenesis and bone turnover
No full textSeveral growth factors are expressed in distinct temporal and spatial patterns during fracture repair. Of these, vascular endothelial growth factor, VEGF, is of particular interest because of its ability to induce neovascularization (angiogenesis). To determine whether VEGF is required for bone repair, we inhibited VEGF activity during secondary bone healing via a cartilage intermediate (endochondral ossification) and during direct bone repair (intramembranous ossification) in a novel mouse model. Treatment of mice with a soluble, neutralizing VEGF receptor decreased angiogenesis, bone formation, and callus mineralization in femoral fractures. Inhibition of VEGF also dramatically inhibited healing of a tibial cortical bone defect, consistent with our discovery of a direct autocrine role for VEGF in osteoblast differentiation. In separate experiments, exogenous VEGF enhanced blood vessel formation, ossification, and new bone (callus) maturation in mouse femur fractures, and promoted bony bridging of a rabbit radius segmental gap defect. Our results at specific time points during the course of healing underscore the role of VEGF in endochondral vs. intramembranous ossification, as well as skeletal development vs. bone repair. The responses to exogenous VEGF observed in two distinct model systems and species indicate that a slow-release formulation of VEGF, applied locally at the site of bone damage, may prove to be an effective therapy to promote human bone repair.</jats:p
A phase 2 study of an oral mTORC1/mTORC2 kinase inhibitor (CC-223) for non-pancreatic neuroendocrine tumors with or without carcinoid symptoms
No full textSecond-generation mammalian target of rapamycin (mTOR) inhibitors such as CC-223 may have theoretical advantages over first-generation drugs by inhibiting TOR kinase in mTOR complex 1 (mTORC1) and 2 (mTORC2), potentially improving clinical efficacy for well-differentiated neuroendocrine tumors (NET).Enrolled patients had metastatic, well-differentiated NET of non-pancreatic gastrointestinal or unknown origin, with/without carcinoid symptoms, had failed ≥1 systemic chemotherapy, and were taking a somatostatin analog (SSA). Oral once-daily CC-223 was administered in 28-day cycles starting at 45 mg (n = 24), with a subsequent cohort starting at 30 mg (n = 23). Objectives were to evaluate tolerability, preliminary efficacy, and pharmacokinetic and biomarker profiles of CC-223. Forty-seven patients completed the study, with mean treatment duration of 378 days and mean dose of 26 mg; 26% of patients remained on the starting dose. Most frequent grade ≥3 toxicities were diarrhea (38%), fatigue (21%), and stomatitis (11%). By investigator, 3 of 41 evaluable patients (7%) showed partial response (PR) and 34 (83%) had stable disease (SD) for a disease control rate (DCR) of 90% (95% confidence interval [CI] 76.9–97.3%). Duration of PR was 125–401 days; median SD duration was 297 days (min–max, 50–1519 days). Median progression-free survival was 19.5 months (95% CI 10.4–28.5 months). Carcinoid symptoms of flushing, diarrhea, or both improved in 50%, 41%, and 39% of affected patients, respectively. For the first time, this study describes that a second-generation mTOR pathway inhibitor can result in highly durable tumor regression and control of NET carcinoid symptoms. The manageable safety profile, high DCR, and durable response, coupled with reduction in carcinoid symptoms refractory to SSA, make CC-223 a promising agent for further development.</div
Dual TORK/DNA-PK inhibition blocks critical signaling pathways in chronic lymphocytic leukemia
No full textInhibition of B-cell receptor (BCR) signaling pathways in chronic lymphocytic leukemia (CLL) provides significant clinical benefit to patients, mainly by blocking adhesion of CLL cells in the lymph node microenvironment. The currently applied inhibitors ibrutinib and idelalisib have limited capacity however to induce cell death as monotherapy and are unlikely to eradicate the disease. Acquired resistance to therapy in CLL is often caused by mutations in the response network being targeted, both for DNA damage or BCR signaling pathways. Thus, drugs with dual targeting capacity could offer improved therapeutic value. Here, the potency of CC-115, a novel inhibitor of mammalian target of rapamycin kinase (TORK) and DNA-dependent protein kinase (DNA-PK), was evaluated in primary CLL cells in vitro and in CLL patients. Combined TORK and DNA-PK inhibition in vitro resulted in caspase-dependent cell killing irrespective of p53, ATM, NOTCH1, or SF3B1 status. Proliferation induced by CD40(+) interleukin-21 stimulation was completely blocked by CC-115, and CD40-mediated resistance to fludarabine and venetoclax could be reverted by CC-115. BCR-mediated signaling was inhibited by CC-115 and also in CLL samples obtained from patients with acquired resistance to idelalisib treatment. Clinical efficacy of CC-115 was demonstrated in 8 patients with relapsed/refractory CLL/small lymphocytic lymphoma harboring ATM deletions/mutations; all but 1 patient had a decrease in lymphadenopathy, resulting in 1 IWCLL partial response (PR) and 3 PRs with lymphocytosis. In conclusion, these preclinical results, along with early promising clinical activity, suggest that CC-115 may be developed further for treatment of CLL. The trial was registered at www.clinicaltrials.gov as #NCT0135362
