Phosphoinositide 3-kinase signaling is critical for ErbB3-driven breast cancer cell motility and metastasis.

Many malignancies show increased expression of the epidermal growth factor (EGF) receptor family member ErbB3 (HER3). ErbB3 binds heregulin ß-1 (HRGß1) and forms a heterodimer with other ErbB family members, such as ErbB2 (HER2) or EGF receptor (EGFR; HER1), enhancing phosphorylation of specific C-terminal tyrosine residues and activation of downstream signaling pathways. ErbB3 contains six YXXM motifs that bind the p85 subunit of phosphoinositide 3 (PI3)-kinase. Previous studies demonstrated that overexpression of ErbB3 in mammary tumor cells can significantly enhance chemotaxis to HRGß1 and overall metastatic potential. We tested the hypothesis that ErbB3-mediated PI3-kinase signaling is critical for heregulin-induced motility, and therefore crucial for ErbB3-mediated invasion, intravasation and metastasis. The tyrosines in the six YXXM motifs on the ErbB3 C-terminus were replaced with phenylalanine. In contrast to overexpression of the wild-type ErbB3, overexpression of the mutant ErbB3 did not enhance chemotaxis towards HRGß1 in vitro or in vivo. We also observed reduced tumor cell motility in the primary tumor by multiphoton microscopy, as well as a dramatically reduced ability of these cells to cross the endothelium and intravasate into the circulation. Moreover, whereas mutation of the ErbB3 C-terminus had no effect on tumor growth, it had a dramatic effect on spontaneous metastatic potential. Treatment with the PI3-kinase inhibitor PIK-75 similarly inhibited motility and invasion in vitro and in vivo. Our results indicate that stimulation of the early metastatic steps of motility and invasion by ErbB3 requires activation of the PI3-kinase pathway by the ErbB3 receptor.

Rac1 protects epithelial cells against anoikis.

Rho family members play a critical role in malignant transformation. Anchorage-independent growth and the ability to avoid apoptosis caused by loss of anchorage (anoikis) are important features of transformed cells. Here we show that constitutive activation of Rac1 inhibits anoikis in Madin-Darby canine kidney (MDCK) epithelial cells. Constitutively active Rac1-V12 decreases DNA fragmentation and caspase activity by 50% in MDCK cells kept in suspension. In addition, expression of Rac1-V12 in MDCK cells in suspension conditions causes an increase in the number of surviving cells. We also investigated the signaling pathways that are activated by Rac1 to stimulate cell survival. We show that expression of Rac1-V12 in MDCK cells in suspension stimulates a number of signaling cascades that have been implicated in the control of cell survival, including the p42/44 ERK, p38, protein kinase B, and nuclear factor kappaB pathways. Using specific chemical or protein inhibitors of these respective pathways, we show that Rac1-mediated cell survival strongly depends on phosphatidylinositol 3-kinase activity and that activation of ERK, p38, and NF-kappaB are largely dispensable for Rac1 survival signaling. In conclusion, these studies demonstrate that Rac1 can suppress apoptosis in epithelial cells in anchorage-independent conditions and suggest a potential role for Rac1-mediated survival signaling in cell transformation.

A randomized, double-blind, placebo-controlled trial of single-dose intravenous secretin as treatment for children with autism.

OBJECTIVE: To determine whether a single injection of intravenous secretin results in measurable improvements in socialization and/or communication skills in children with autism. STUDY DESIGN: Sixty subjects with autism were randomly selected and assigned to either treatment or placebo group. Subjects in the treatment group received 2.0 clinical units of secretin per kilogram of body weight as a single intravenous dose. Subjects in the placebo group received normal saline solution. Neurodevelopmental and behavioral assessments were performed for all subjects before injection and at 3 and 6 weeks after injection. RESULTS: Assessment of language skills and parents' behavioral assessments revealed no significant differences between the treatment and placebo groups. Raters' assessments of severity of autistic symptoms did not differ for the 2 groups at 6 weeks after injection. A marginally statistically significant improvement in autistic behaviors was seen in the treatment group at 3 weeks after injection (P =.051). CONCLUSIONS: A single dose of intravenous secretin does not appear to have significant effects on either parents' perception of autistic behaviors or language skills at 6 weeks after injection. Transient, marginally significant improvements in autistic behaviors may occur in some children.

Retinoid-induced repression of human immunodeficiency virus type 1 core promoter activity inhibits virus replication.

The rates of mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1), progression to AIDS following HIV-1 infection, and AIDS-associated mortality are all inversely correlated with serum vitamin A levels (R. D. Semba, W. T. Caiaffa, N. M. H. Graham, S. Cohn, and D. Vlahov, J. Infect. Dis. 171:1196-1202, 1995; R. D. Semba, N. M. H. Graham, W. T. Caiaffa, J. B. Margolik, L. Clement, and D. Vlahov, Arch. Intern. Med. 153:2149-2154, 1993; R. D. Semba, P. G. Miotti, J. D. Chiphangwi, A. J. Saah, J. K. Canner, G. A. Dallabetta, and D. R. Hoover, Lancet 343:1593-1596, 1994). Here we show that physiological concentrations of vitamin A, as retinol or as its metabolite, all-trans retinoic acid, repressed HIV-1Ba-L replication in monocyte-derived macrophages (MDMs). Repression required retinoid treatment of peripheral monocytes during their in vitro differentiation into MDMs. Retinoids had no repressive effect if they were added after virus infection. Retinol, as well as all-trans retinoic acid and 9-cis retinoic acid, also repressed HIV-1 long terminal repeat (LTR)-directed expression up to 200-fold in transfected THP-1 monocytes. Analysis of HIV-1 LTR deletion mutants demonstrated that retinoids were able to repress activation of HIV-1 expression by both NF-kappaB and Tat. A cis-acting sequence required for retinoid-mediated repression of HIV-1 transcription was localized between nucleotides -51 and +12 of the HIV-1 LTR within the core promoter. Protein-DNA cross-linking experiments identified four proteins specific to retinoid-treated cells that bound to the core promoter. We conclude that retinoids render macrophages resistant to virus replication by modulating the interaction of cellular transcription factors with the viral core promoter.

Developmental outcomes of children with myelomeningocele: prenatal predictors.

OBJECTIVE: The purpose of the current investigation was to determine cognitive developmental outcomes for a cohort of children with prenatally detected myelomeningocele and to determine whether the variables of (1) severity of ventriculomegaly and (2) anatomic level of lesion were predictive of cognitive development. STUDY DESIGN: Prenatal ultrasonographic examinations were reviewed by a single perinatologist to determine the degree of ventriculomegaly and the anatomic level of the lesion. Ventriculomegaly was defined as a lateral ventricular atrial width > 10 mm. Anatomic level of lesion was defined as (1) thoracic, (2) high lumbar, (3) midlumbar, (4) low lumbar-high sacral, or (5) sacral. Cognitive developmental quotients for surviving children were determined by one of two developmental pediatricians with use of a modified version of the Clinical Adaptive Test/Clinical Linguistic Auditory Milestone Scale, a measure of visual-motor and language abilities. RESULTS: The mean cognitive developmental quotient for subjects with absent to mild ventriculomegaly was 90.3 (range 54 to 120, SD 17.4), whereas the mean cognitive developmental quotient for those with moderate to severe ventriculomegaly was 74.0 (range 65 to 100, SD 17.1) (p < 0.01). There was a negative correlation between the degree of ventriculomegaly and the cognitive developmental quotient (r = -0.43, p < 0.025) and a positive correlation between the level of the lesion and the cognitive developmental quotient (r = 0.50, p < 0.01). CONCLUSIONS: The degree of ventriculomegaly determined on high-resolution prenatal ultrasonography is predictive of early cognitive development in children with myelomeningocele, with worsening ventriculomegaly being associated with lower cognitive developmental quotients. The anatomic level of the lesion also has predictive value, with lower level lesions being associated with more favorable cognitive outcomes. However, because of the high degree of variance in developmental quotients within the two ventriculomegaly groups, we advise clinicians to use caution in the interpretation and use of our data.

Apparent growth hormone deficiency in children with cerebral palsy.

Ten children with cerebral palsy (CP) and growth failure underwent assessment of the growth hormone (GH) axis, including spontaneous GH secretion, GH secretion in response to pharmacological stimulation, and circulating levels of insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3). Six of the children had subnormal GH secretion consistent with GH deficiency. Subnormal growth velocity was the best clinical predictor of GH deficiency. The large percentage of these children with apparent GH deficiency is surprising. Possible mechanisms include anatomic abnormalities of the hypothalamic-pituitary axis, psychosocial deprivation, and an interaction between suboptimal nutritional status and an abnormal central nervous system.

Functional motor outcome in children with myelomeningocele: correlation with anatomic level on prenatal ultrasound.

Fifteen children with prenatally diagnosed myelomeningocele were followed for at least three years to determine the relations between prenatal anatomic level visualized on high-resolution ultrasound, radiographic level, neuromotor level and functional motor outcome. Prenatal anatomic level accurately predicted neuromotor level and functional motor outcome in 12 of the children and was a better predictor than motor level at birth. Clinicians involved in prenatal counseling may use the anatomic level determined on high-resolution ultrasound to discuss motor prognosis with families.

Antigen-receptor engagement in B cells induces nuclear expression of STAT5 and STAT6 proteins that bind and transactivate an IFN-gamma activation site.

The signal transducer and activator of transcription (STAT) family of transcription factors is triggered by cytokine and growth factor receptors in a number of cell types, and binds to a consensus sequence defined in part by the IFN-gamma activation site (GAS). It is not known whether these transcription factors respond to other kinds of growth stimuli, and, with particular relevance to lymphocytes, it is not known whether STAT proteins participate in Ag-specific responses. To determine the role of STAT proteins, coupling between Ag-receptor cross-linking and nuclear expression of DNA-binding protein complexes that recognize GAS sequences was evaluated. Ag-receptor triggering in primary B lymphocytes stimulated nuclear expression of a complex that specifically binds the IFN response factor-1 (IRF-1) GAS sequence, and is distinguished by electrophoretic mobility and GAS preference from IRF-1 GAS-binding complexes induced by IFN-gamma. Activation of nuclear IRF-1 GAS-binding activity by sIg was inhibited by the tyrosine kinase inhibitor, herbimycin A, and binding activity was eliminated by tyrosine phosphatase treatment. Activation of IRF-1 GAS-binding activity was blocked by depletion of protein kinase C. The IRF-1 GAS-binding activity induced by sIg engagement in B cells was transcriptionally active, and was found to consist of immunoreactive STAT5 and STAT6 proteins. This work demonstrates that the STAT signaling pathway previously associated with cytokine signaling is triggered in B lymphocytes through Ag-receptor engagement in a protein kinase C-dependent fashion. This heretofore described cytokine signaling pathway may play a role in bringing about Ag-specific proliferative and differentiative responses.

Growth hormone deficiency in two children with cerebral palsy.

The authors describe two children with cerebral palsy and linear growth failure secondary to growth hormone deficiency. One of the children was successfully treated with growth hormone replacement therapy. His linear growth velocity increased from 3cm/year before therapy to 8.3 cm/year during the first two years of therapy. Potential complications such as worsening orthopedic status did not occur. Psychosocial benefits were noted. The authors conclude that growth hormone deficiency may play a role in linear growth failure in some children with cerebral palsy and that some of these children may benefit from growth hormone therapy.