The mechanism by which aplidine, a marine natural product in early clinical development as an anticancer agent, induces cell growth inhibition and apoptosis has been investigated in the human ...leukemia cell line MOLT-4. This cell line is characterized not only by the ability to secrete VEGF, but also for the presence on its surface of the VEGF receptor-1 (VEGFR-1). Previous studies from our laboratory concerned with evaluating early changes in gene expression induced by aplidine in MOLT-4 cells have shown that the drug decreases the expression of VEGFR-1 (Marchini et al. Proc Am Assoc Cancer Res 2000; 41: 833). Here, we report the ability of aplidine to block the VEGF/VEGFR-1 loop. We found that aplidine blocked VEGF secretion that was temporally followed by a decrease in both VEGF and VEGFR-1 production. Aplidine did not directly affect either VEGF transcription or stabilization of its mRNA. Transfection of MOLT-4 cells with an antisense VEGF cDNA construct, resulted in inhibition of colony formations. One clone, transfected with sense VEGF cDNA, secreting 8-10 times more VEGF than parental cells, was less sensitive to aplidine-induced cytotoxicity and apoptosis than control cells. Moreover, addition of VEGF in the medium decreased the activity of aplidine in MOLT-4 cells. These data demonstrate that aplidine inhibits the growth and induces apoptosis in MOLT-4 cells through the inhibition of VEGF secretion which blocks the VEGF/VEGFR-1 autocrine loop necessary for the growth of these cells.
By reverse transcriptase polymerase chain reaction on messenger RNA from human polymorphonuclear cells, we have isolated a sequence identical to the cDNA coding for intracellular interleukin 1 ...receptor antagonist (icIL-1ra), but containing an additional in-frame 63-bp sequence located three codons downstream of the translation start of icIL-1ra. This additional sequence is inserted between the first and second exon of the intracellular form, the latter of which is colinear with part of the first exon of the secreted form of IL-1ra. The additional sequence is coded by an extra exon located 2 kb downstream the first icIL-1ra-specific exon. The complementary DNA sequence of the alternatively spliced form of icIL-1ra shows that the predicted protein differs from classical icIL-1ra in the NH2 terminus by insertion of a leaderless sequence of 21 amino acids rich in glycine and glutamic acid residues. Transcripts coding for this new form of icIL-1ra were detected in activated fibroblasts, keratinocytes, and at low levels in myelomonocytic cells. The recombinant protein expressed in COS cells had an apparent molecular mass in sodium dodecyl sulfate polyacrylamide gel electrophoresis of 25 kD compared to 22 kD of classical icIL-1ra, and was mostly intracellular. The ability of this new form of icIL-1ra to inhibit IL-1 activity, in terms of induction of E-selectin and human immunodeficiency virus replication, was comparable to that of classical icIL-1ra. We propose to refer to this new form of icIL-1ra as icIL-1ra type II.
Hyperinsulinemia and insulin resistance may contribute to the development of cardiac hypertrophy. In humans, however, the evidence is inconclusive.
We studied 50 nondiabetic subjects covering a wide ...range of age (20 to 65 years), body mass index (BMI, 19 to 40 kg x m(-2)), and mean blood pressure (72 to 132 mm Hg). Plasma insulin concentrations and secretory rates were measured at baseline and during an oral glucose tolerance test; insulin sensitivity was measured by the insulin clamp technique. Left ventricular mass (LVM) (by 2D M-mode echocardiography) was distributed normally and was higher in obese (BMI >/=27 kg x m(-2), n=16) or hypertensive patients (blood pressure >140/90 mm Hg, n=21) (50+/-8 and 55+/-10 g x m(-2.7), respectively) than in 13 nonobese, normotensive subjects (40+/-8 g x m(-2.7), P:=0.0004). In a multivariate model adjusting for sex, age, BMI, and blood pressure, neither insulin concentrations (fasting or postglucose) nor insulin sensitivity or secretory rates were significant correlates of LVM. Systolic blood pressure (P:=0.003) and BMI (P:=0.01) were the only independent correlates of LVM. From the regression, the impact of hypertension (as a systolic pressure of 180 versus 140 mm Hg=+20%) was twice as large as that of obesity (as a BMI of 35 versus 25 kg x m(-2)=+11%), the two factors being additive.
When adequate account is taken of body mass and blood pressure, insulin, as concentration, secretion, or action, is not an independent determinant of LVM in nondiabetic subjects.
The ab initio potential energy surface (PES) already computed for the title system is employed here to study the behaviour of the collisional energy transfer processes over a broad range of energies. ...The quantum evaluation of rotationally and vibrationally inelastic partial integral cross sections is carried out under different angular momentum coupling conditions and the results are closely analysed in terms of the specific features of the coupling PES.
State-to-state rate constants for excitation and relaxation processes are obtained in a broad range of temperatures and the overall efficiency of the collisional energy transfer is analysed. The cooperative effect between the rotational anisotropy and the vibrational excitations is clearly shown and discussed.
Three molecular forms of the IL‐1 receptor antagonist (IL‐1ra) have been identified and cloned. Secreted IL‐1ra (sIL‐1ra or IL‐1ra1) contains a classical leader peptide giving a released mature ...protein. Two intracellular isoforms, icIL‐1ra type I (IL‐1ra2) and icIL‐1ra type II (IL‐1ra3), have no leader sequence, thus predicting that these proteins remain intracellular. In an effort to define its biological role, we structurally and functionally characterized IL‐1ra3. Endogenous immunoreactive IL‐1ra3 was detected in a variety of inflammatory cells and tissues. We used a gene transfer strategy to explore the possible intracellular functions of IL‐1ra3 (and IL‐1ra2) and the cell‐associated agonist IL‐1α. The intracellular IL‐1ra3 isoform, as well as IL‐1ra2, does not block the action of exogenous and endogenous IL‐1 under these conditions. Intact IL‐1ra3 was released from the cells killed by NK effectors. The intracellular isoforms may represent a reservoir of IL‐1ra, released upon cell death, whose function is to limit the pro‐inflammatory action of cell debris.
The effect of single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 1.2, 6 or 30 micrograms/kg i.p.) on primary humoral antibody production was studied in young adult C57 BL/6J mice. TCDD ...profoundly suppressed the primary response to thymus-dependent (sheep erythrocytes) and independent (type III pneumococcal polysaccharide) antigens. The inhibitory effect of TCDD was still detectable 42 days after treatment. In contrast, under these experimental conditions, in vitro lymphoproliferative responses to Concanavalin A (Con A) and bacterial lypopolysaccharides and the ability to mediate graft versus host reaction were not significantly affected per unit number of lymphoid cells.
The structures and energetics of complexes between guanine⋯cytosine Watson–Crick (GCWC) DNA base pair and the hydrated Mg
++ cation were investigated by an ab initio Hartree–Fock study in the absence ...of basis set superposition error. The explicit hydration of the cation with four and five water molecules was considered. The various charged fragments were allowed to interact with the N7 and O6 sites of guanine. The BSSE-free gradient geometry optimisation were performed in the framework of the SCF-MI (self-consistent field for molecular interactions) theory. The structures of the complexes were analysed showing that the coordination of the GC pair can generate highly distorted non-Watson–Crick hydrogen bonding patterns.
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