Proteomic analysis of imatinib-resistant CML-T1 cells reveals calcium homeostasis as a potential therapeutic target

Chronic myeloid leukemia (CML) therapy has markedly improved patient prognosis after introduction of imatinib mesylate for clinical use. However, a subset of patients develops resistance to imatinib and other tyrosine kinase inhibitors (TKIs), mainly due to point mutations in the region encoding the kinase domain of the fused BCR-ABL oncogene. To identify potential therapeutic targets in imatinib-resistant CML cells, we derived imatinib-resistant CML-T1 human cell line clone (CML-T1/IR) by prolonged exposure to imatinib in growth media. Mutational analysis revealed that the Y235H mutation in BCR-ABL is probably the main cause of CML-T1/IR resistance to imatinib. To identify alternative therapeutic targets for selective elimination of imatinib-resistant cells, we compared the proteome profiles of CML-T1 and CML-T1/IR cells using 2-DE-MS. We identified eight differentially expressed proteins, with strongly upregulated Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) in the resistant cells, suggesting that this protein may influence cytosolic pH, Ca²⁺ concentration or signaling pathways such as Wnt in CML-T1/IR cells. We tested several compounds including drugs in clinical use that interfere with the aforementioned processes and tested their relative toxicity to CML-T1 and CML-T1/IR cells. Calcium channel blockers, calcium signaling antagonists and modulators of calcium homeostasis, namely thapsigargin, ionomycin, verapamil, carboxyamidotriazole and immunosuppressive drugs cyclosporine A and tacrolimus (FK-506) were selectively toxic to CML-T1/IR cells. The putative cellular targets of these compounds in CML-T1/IR cells are postulated in this study. We propose that Ca²⁺ homeostasis can be a potential therapeutic target in CML cells resistant to TKIs. We demonstrate that a proteomic approach may be used to characterize a TKI-resistant population of CML cells enabling future individualized treatment options for patients.

Microgravity effects on sea urchin fertilization and development

Gravity has been a pervasive influence on all living systems and there is convincing evidence to suggest that it alters fertilization and embryogenesis in several developmental systems. Notwithstanding the global importance of gravity on development, it has only been recently possible to begin to design experiments which might directly investigate the specific effects of this vector. The goal of this research program is to explore and understand the effects of gravity on fertilization and early development using sea urchins as a model system. Sea urchin development has several advantages for this project including the feasibility of maintaining and manipulating these cells during spaceflight, the high percentage of normal fertilization and early development, and the abundant knowledge about molecular, biochemical, and cellular events during embryogenesis which permits detailed insights into the mechanism by which gravity might interfere with development. Furthermore, skeletal calcium is deposited into the embryonic spicules within a day of fertilization permitting studies of the effects of gravity on bone calcium deposition.

Low efficacy radiography of children

Radiographic procedures performed at a 100-bed pediatric hospital were reviewed jointly by a radiologist and the primary physician staff. The reviewers judged several procedures to be performed unnecessarily, with undue patient risk or cost. Low efficacy examinations were divided into two categories: (1) low-yield examinations with significant gonadal radiation as well as significant cost, and (2) low-yield examinations with low gonadal radiation but significant cost. A joint policy recommendation was then delivered to the house staff concerning appropriate indications for the performance of these low-yield procedures. This active review process is submitted as a model for other medical facilities that seek to reduce risk and cost to the pediatric patient.

Metabolic and hormonal studies comparing three parenteral nutrition regimens in infants

Metabolic and hormonal studies were performed in 6 infants during the first 3 months of life while receiving 3 different types of parenteral nutrition: 1) 20% glucose and a nitrogen source (Dudrick's method) 2) 12% glucose, a nitrogen source and soybean fat emulsion (Intralipid method) and 3) 12% glucose, a nitrogen source and 1% alcohol (Babson's method). All three regimens provided positive nitrogen balance of similar magnitude. The substrate-hormone relationships were appropriate. After parenteral fat free nutrition (primary caloric source glucose) the plasma glucagon levels were significantly lower and the growth hormone levels significantly higher than after the fat emulsion therapy period. The Dudrick and Intralipid methods resulted in a higher caloric intake and weight gain than the Babson method. The former two regimens cannot be completely endorsed, however, since septic and central vein complications are unavoidable with the Dudrick method particularly in the small infant; and the long term effects of intralipid, particularly on the liver are still unknown.