CNS response after erlotinib therapy in a patient with metastatic NSCLC with an EGFR mutation

BACKGROUND

A 73-year-old Asian man with a history of lipidemia, hypertension and myocardial infarction presented with dizziness, decreased appetite, weight loss, nonproductive cough and fatigue. His physical performance status was good, and physical examination was unremarkable except for lower-extremity pitting edema.

INVESTIGATIONS

Physical examination, brain MRI, CT scans of the chest, abdomen and pelvis, bone scan, CT scan-guided biopsy, hematoxylin and eosin staining, EGFR mutational analysis, and chest X-ray.

DIAGNOSIS

Stage IV non-small-cell lung cancer with brain metastasis.

MANAGEMENT

Oral erlotinib 150 mg daily for 10 months and ongoing, and whole-brain irradiation.

Synergistic antileukemic effects between ABT-869 and chemotherapy involve downregulation of cell cycle-regulated genes and c-Mos-mediated MAPK pathway

Internal tandem duplications (ITDs) of fms-like tyrosine kinase 3 (FLT3) receptor play an important role in the pathogenesis of acute myeloid leukemia (AML) and represent an attractive therapeutic target. ABT-869 has demonstrated potent effects in AML cells with FLT3-ITDs. Here, we provide further evidence that ABT-869 treatment significantly downregulates cyclins D and E but increases the expression of p21 and p27. ABT-869 induces apoptosis through downregulation of Bcl-xL and upregulation of BAK, BID and BAD. We also evaluate the combinations of ABT-869 and chemotherapy. ABT-869 demonstrates significant sequence-dependent synergism with cytarabine and doxorubicin in cell lines and primary leukemia samples. The optimal combination was validated in MV4-11 xenografts. Low-density array analysis revealed the synergistic interaction involved in downregulation of cell cycle and mitogen-activated protein kinase pathway genes. CCND1 and c-Mos were the most significantly inhibited targets on both transcriptional and translational levels. Treatment with short hairpin RNAs targeting either CCND1 or c-Mos further sensitized MV4-11 cells to ABT-869. These findings suggest that specific pathway genes were further targeted by adding chemotherapy and support the rationale of combination therapy. Thus, a clinical trial using sequence-dependent combination therapy with ABT-869 in AML is warranted.

Enhanced NFATc1 nuclear occupancy causes T cell activation independent of CD28 costimulation

TCR signals induce the nuclear localization of NFATc proteins, which are removed from the nucleus after rephosphorylation by glycogen synthase kinase 3 and other kinases. Rapid nuclear export might allow continuous monitoring of receptor occupancy, making the transcriptional response proportional to the duration of TCR/CD28 signaling. To investigate this possibility, we analyzed mice in which T cells express a NFATc1 variant (NFATc1(nuc)) with serine-to-alanine changes at the glycogen synthase kinase 3 phosphorylation sites. NFATc1(nuc) T cells have constitutively nuclear NFATc1, enhanced T cell activation in vivo, and calcineurin-independent proliferation in vitro. NFATc1(nuc) T cells are hypersensitive to TCR/CD3 stimulation, resulting in enhanced proliferation and cytokine production that is independent of CD28 costimulation. These results support the notion that CD28 inhibits nuclear export of NFATc transcription factors. In addition, NFATc1(nuc) destabilizes a positive feedback loop in which NFATc1 activates its own transcription as well as its targets, such as CD40 ligand and Th1/Th2 cytokines.

Calcineurin/NFAT signaling in osteoblasts regulates bone mass

Development and repair of the vertebrate skeleton requires the precise coordination of bone-forming osteoblasts and bone-resorbing osteoclasts. In diseases such as osteoporosis, bone resorption dominates over bone formation, suggesting a failure to harmonize osteoclast and osteoblast function. Here, we show that mice expressing a constitutively nuclear NFATc1 variant (NFATc1(nuc)) in osteoblasts develop high bone mass. NFATc1(nuc) mice have massive osteoblast overgrowth, enhanced osteoblast proliferation, and coordinated changes in the expression of Wnt signaling components. In contrast, viable NFATc1-deficient mice have defects in skull bone formation in addition to impaired osteoclast development. NFATc1(nuc) mice have increased osteoclastogenesis despite normal levels of RANKL and OPG, indicating that an additional NFAT-regulated mechanism influences osteoclastogenesis in vivo. Calcineurin/NFATc signaling in osteoblasts controls the expression of chemoattractants that attract monocytic osteoclast precursors, thereby coupling bone formation and bone resorption. Our results indicate that NFATc1 regulates bone mass by functioning in both osteoblasts and osteoclasts.

ABT-869, a novel multi-target receptor tyrosine kinase inhibitor (RTKI), combined with chemotherapy is synergistic in the therapy of acute myeloid leukemia cells with FLT3-ITD mutation (FLT3-AML)

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Background: Internal tandem duplications (ITDs) of fms-like tyrosine kinase 3 (FLT3) receptor are identified in 20–25% of adult AML patients associated with poor prognosis. ABT-869 is active in FLT3-AML and is currently under clinical investigaton. We hypothesize that the combination of ABT-869 with chemotherapy can improve the therapeutic index in FLT3-AML. Methods: Using Calcusyn software, the additive, synergistic or antagonistic effect of ABT-869 with concurrent or sequential cytosine arabinoside (Ara-C) or doxorubicin (Dox) was measured in MV4–11 and MOLM-14 cells. The synergistic combination sequence was further tested in a MV4–11 xenograft model in four groups (10 mice/group) including control, Ara-C, ABT-869, and combination (Ara-C first for 4 days, then daily ABT-869). Cell cycle analysis and apoptosis and signal pathway assays were performed in vitro and in vivo. Results: ABT-869 induced dose- and time-dependent apoptosis on FLT3-AML cells resulting in down regulation of p-FLT3, p-STAT5, Bcl-XL and up regulation of p53 and BID. ABT-869 caused G1-phase arrest and the removal of cells in the S- and G2/M-phase mediated by reduction of cyclins D and E. We observed significant synergistic effect with Ara-C or Dox first, followed by ABT-869, as well as in concurrent treatment with ABT-869 and Dox. Simultaneous treatment with ABT-869 and Ara-C only achieved additive effect. Conversely, we found an antagonistic effect in the sequence of pretreatment of ABT-869 followed by chemotherapy. In a MV4–11 xenograft model, all mice succumbed to leukemia in the control and Ara-C groups (median survival = 53 and 55.5 days respectively). Combination therapy gave a faster reduction of tumor volume compared to ABT-869 treatment alone (p=0.03) without recurrence of leukemia in either group by day 67. In vivo immunohistochemistry (IHC) analysis revealed ABT-869 potently inhibited VEGF and phosphor-ERK. Conclusions: ABT-869 can be given after Ara-C or Dox to act synergistically. Our study suggests that combinations of RTKIs with chemotherapy should be carefully tested prior to clinical protocol development. A clinical trial of such combination therapy in FLT3-AML is warranted.

No significant financial relationships to disclose.

Percutaneous interventions on severe coarctation of the aorta: a 21-year experience

Different percutaneous interventions can be used to treat coarctation of the aorta. However, a great amount of information is still needed regarding the long-term course. This article reviews our experience spanning 21 years in the percutaneous treatment of aortic coarctation. Four different conditions for treatment were considered. The first condition 1 (group 1) was balloon angioplasty in neonates and infants with untractable heart failure (n = 54; mean age, 1.2 +/- 1.4 months). After balloon angioplasty, most infants sustained significant clinical improvement. However, 9 patients died in the hospital (17%). As a result, we monitored the course of the 45 survivors during a mean period of 10 +/- 6 years (range, 1-19). During this follow-up period, 17 patients needed a single additional intervention on coarctation (8 underwent surgery and 9 were treated percutaneously). After this second treatment, 11 patients needed one or more further interventions. The actuarial survival probability was 83% at 19 years, with 43% of patients remaining surgery free and 23% reintervention free. The second condition (group 2) was balloon angioplasty in children and adults with coarctation of the aorta before the stenting era (n = 28; mean age, 13 +/- 8 years). After treatment, serial hemodynamic and angiographic studies were performed. The long-term relief was higher in patients with a discrete type of coarctation. The rate of late aneurysm formation was 6%. The third condition (group 3) was stent palliation in infants and children younger than the age of 6 years (n = 17; mean age, 2.1 +/- 1.7 years). The stent was implanted for nondilatable stenoses, as a nondefinitive procedure. Stent palliation provides complete initial relief in hypoplastic coarctations or life-threatening conditions. However, further stent expansion is required to ensure adequate stent diameter in the growing aortic wall. In addition, late intrastent proliferation may occur in small stent diameters (18%) and aneurysm formation in hypoplastic coarctations (18%). Both late complications can be managed percutaneously. The fourth condition (group 4) was stent repair of severe aortic coarctation in adults, adolescents, and children older than the age of 6 years (n = 73; mean age, 20 +/- 12 years). Significant relief was observed after treatment, which persisted at follow-up. One patient died at treatment (1.3%). After a mean follow-up of 5 +/- 3 years, all 72 patients remained symptom free and no restenosis or late aneurysm were detected.

Keratin 17 mutation in pachyonychia congenita type 2 with early onset sebaceous cysts

BACKGROUND

Pachyonychia congenita (PC) is a group of autosomal dominant ectodermal dysplasias caused by mutations in four differentiation-specific keratin genes. Two major clinical subtypes of PC have been generally recognized. Symmetrically thickened fingernails and toenails are the defining characteristic of PC type 2 (PC-2) with onset at infancy. Pilosebaceous cysts are the best hallmark of PC-2, but they usually occur at puberty.

OBJECTIVES

To report a Chinese pedigree of PC-2 with unusually early onset sebaceous cysts and to explore the genetic mutation and its phenotype.

METHODS

Exon 1 of keratin 17 was amplified by polymerase chain reaction (PCR) from genomic DNA from the three patients in the pedigree, the proband, his half-sister and his younger son, two unaffected members in the pedigree and 50 unrelated and unaffected people. PCR products were directly sequenced to detect the mutation.

RESULTS

Direct sequencing of the PCR products revealed a heterozygous 275A-->G mutation in all three affected members. This mutation predicts the substitution of asparagine by serine in codon 92 (N92S) located in the 1A domain of keratin 17.

CONCLUSIONS

Mutation in the 1A domain of keratin 17 underlies the affected members' phenotype, PC-2 with early onset sebaceous cysts and late-onset thickened fingernails and toenails. The onset of the cysts is very early in some people within this family and the age at onset of thickened fingernails and toenails is variable within the family, implying the existence of modifying factors.

Sub-Angstrom high-resolution transmission electron microscopy at 300 keV

Sub-Angstrom transmission electron microscopy has been achieved at the National Center for Electron Microscopy (NCEM) by a one-Angstrom microscope (OAM) project using software and enhanced hardware developed within a Brite-Euram project (Ultramicroscopy 64 (1996) 1). The NCEM OAM provides materials scientists with transmission electron microscopy at a resolution better than 1 A by using extensive image reconstruction to exploit the significantly higher information limit of an FEG-TEM over its Scherzer resolution limit. Reconstruction methods chosen used off-axis holograms and focal series of underfocused images. Measured values of coherence parameters predict an information limit of 0.78 A. Images from a [1 1 0] diamond test specimen show that sub-Angstrom resolution of 0.89 A has been achieved with the OAM using focal series reconstruction.

Glutamine metabolism in sepsis and infection

Severe infection causes marked derangements in the flow of glutamine among organs, and these changes are accompanied by significant alterations in regional cell membrane transport and intracellular glutamine metabolism. Skeletal muscle, the major repository of glutamine, exhibits a twofold increase in glutamine release during infection, which is associated with a significant increase in endogenous glutamine biosynthesis. Despite an increase in glutamine synthetase activity in skeletal muscle, the intracellular glutamine pool becomes depleted, indicating that release rates exceed rates of synthesis. Simultaneously, the circulating pool of glutamine does not increase, indicating accelerated uptake by other organs. The liver appears to be the major organ of glutamine uptake in severe infection; studies in endotoxemic rodents have shown net hepatic glutamine uptake to increase by as much as 8- to 10-fold. This increase is due partially to increases in liver blood flow, but also to a three- to fourfold increase in hepatocyte System N activity in the liver. Cytokines and glucocorticoids mediate the increased uptake of glutamine by the liver in septic states as well as other compounds. Sepsis does not appear to induce an increase in System N gene expression, indicating that the increase in hepatic glutamine transport observed during severe infection is probably regulated at the protein level. The bowel displays a decrease in glutamine utilization during sepsis, a response that may be related to the decrease in circulating insulin-like growth factor-1 (IGF-1) levels that is characteristic of sepsis. Recent studies suggest that IGF-1 has a direct effect on stimulating glutamine transport across the gut lumen and thus may represent a therapeutic avenue for improving gut nutrition during severe infection. The cells of the immune system (lymphocytes, macrophages) are also major glutamine consumers during inflammatory states in which cell proliferation is increased. Under these conditions, glutamine availability can become rate limiting for key cell functions, such as phagocytosis and antibody production.

The triple threat to nascent apolipoprotein B. Evidence for multiple, distinct degradative pathways

We previously showed that Omega-3 fatty acids reduce secretion of apolipoprotein B (apoB) from cultured hepatocytes by stimulating post-translational degradation. In this report, we now characterize this process, particularly in regard to the two known processes that degrade newly synthesized apoB, endoplasmic reticulum (ER)-associated degradation and re-uptake from the cell surface. First, we found that Omega-3-induced degradation preferentially reduces the secretion of large, assembled apoB-lipoprotein particles, and apoB polypeptide length is not a determinant. Second, based on several experimental approaches, ER-associated degradation is not involved. Third, re-uptake, the only process known to destroy fully assembled nascent lipoproteins, was clearly active in primary hepatocytes, but Omega-3-induced degradation of apoB continued even when re-uptake was blocked. Cell fractionation showed that Omega-3 fatty acids induced a striking loss of apoB100 from the Golgi, while sparing apoB100 in the ER, indicating a post-ER process. To determine the signaling involved, we used wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, which blocked most, if not all, of the Omega-3 fatty acid effect. Therefore, nascent apoB is subject to ER-associated degradation, re-uptake, and a third distinct degradative pathway that appears to target lipoproteins after considerable assembly and involves a post-ER compartment and PI3K signaling. Physiologic, pathophysiologic, and pharmacologic regulation of net apoB secretion may involve alterations in any of these three degradative steps.

In situ transmission electron microscopy studies and real-time digital imaging

A newly designed CCD camera has been utilized for real-time and static image acquisitions. The performance of the camera is demonstrated for heating/cooling in-situ TEM experiments performed on a commercial high strength aluminium alloy using a double tilt heating holder. The real-time digital imaging capability of the new camera should facilitate the in-situ TEM that is now re-establishing itself as a strategic tool for materials characterization.

A role for calnexin in the assembly of the MHC class I loading complex in the endoplasmic reticulum

Heterodimers of MHC class I glycoprotein and beta(2)-microglobulin (beta(2)m) bind short peptides in the endoplasmic reticulum (ER). Before peptide binding these molecules form part of a multisubunit loading complex that also contains the two subunits of the TAP, the transmembrane glycoprotein tapasin, the soluble chaperone calreticulin, and the thiol oxidoreductase ERp57. We have investigated the assembly of the loading complex and provide evidence that after TAP and tapasin associate with each other, the transmembrane chaperone calnexin and ERp57 bind to the TAP-tapasin complex to generate an intermediate. These interactions are independent of the N:-linked glycan of tapasin, but require its transmembrane and/or cytoplasmic domain. This intermediate complex binds MHC class I-beta(2)m dimers, an event accompanied by the loss of calnexin and the acquisition of calreticulin, generating the MHC class I loading complex. Peptide binding then induces the dissociation of MHC class I-beta(2)m dimers, which can be transported to the cell surface.