Alterations in gene expression between EMT-6 mammary carcinoma monolayers and spheroids identified by differential display

Differential display was used to define differences in gene expression between murine EMT-6 mammary carcinoma cells grown in monolayer or as spheroids in cell culture. Eighty different combinations of primer sets made of four anchored oligodeo(dT) primers (T(12)MG, T(12)MA, T(12)MT or T(12)MC) and twenty arbitrary ten base primers (AP1-20) were used for RT-PCR of total purified RNA from EMT-6 monolayers or spheroids. After re-screening, fourteen DNA fragments were identified as being selectively expressed in EMT-6 cells grown as spheroids. The fragments were cloned into the pCR II vector. Two of the fourteen cDNA fragments corresponded to mRNA selectively expressed in EMT-6 cells grown as spheroids. These clones were sequenced and found by database searching to correspond to murine heme oxygenase and murine beta(2)-microglobulin. There was a 5.3-fold higher expression of beta(2)-microglobulin and a 5.3-fold greater expression of heme oxygenase in EMT-6 cells grown as spheroids than in the same cells grown as monolayers. These studies reflect the phenotypic flexibility of cells depending upon the growth environment.

Characterization of the motor and enzymatic properties of smooth muscle long S1 and short HMM: role of the two-headed structure on the activity and regulation of the myosin motor

Truncated mutants of smooth muscle myosin containing various lengths of the S2 portion were expressed in Sf9 cells and purified. Truncated myosin having a heavy chain molecular mass of 128 kDa and larger formed a stable dimer, while 108 kDa myosin remained a monomer. On the other hand, 114 and 110 kDa myosins existed as both monomer and dimer. The enzymatic activity and also the in vitro actin sliding activity of these mutant myosins were measured, and the following findings were obtained. (1) Both the actin sliding activity and the actin-activated ATPase activity showed phosphorylation dependence when myosin forms a dimer while the monomeric form was phosphorylation-independent. This indicates that the interaction between the two heads is operating and critical for the regulation. (2) The actin sliding velocity of the dimer form was twice as large as that of the monomer form, while the actin-activated ATPase activity of the two forms was identical, suggesting that the mechano-chemical efficiency is affected by the interaction between the two heads. (3) The depression of the Mg(2+)-ATPase activity of myosin at low ionic strength, characteristic of the 6S-10S transition of smooth muscle myosin, is abolished with the monomer form, suggesting that the association of the two heads is critical for the 6S-10S transition.

Protein kinase C increases force and slows relaxation in smooth muscle: evidence for regulation of the myosin light chain phosphatase

To determine if activation of protein kinase C (PKC) participates in the molecular mechanism for agonist induced force enhancement, force was measured in single beta-escin skinned smooth muscle cells stimulated to contract with Ca2+, myosin light chain (MLC) kinase, PKC and microcystin-LR. The constituently active fragment of protein kinase C (PKM) increased both force and MLC phosphorylation in cells previously stimulated to contract at submaximal Ca2+. For cells contracted with saturating Ca2+, PKM stimulation did not increase either force or MLC phosphorylation. For contractions stimulated with both PKM and microcystin-LR, force rose significantly slower than contractions produced by Ca2+ or MLC kinase, suggesting that PKM increases force by a decrease in the rate of myosin dephosphorylation. Consistent with this hypothesis is the finding that the rate of force relaxation was slowed by PKM. This is the first direct demonstration that activation of PKC increases force in smooth muscle, and these results suggest that in smooth muscle, agonist induced activation of PKC plays a role in force regulation via an inhibition of myosin light chain phosphatase activity.

Chemomechanical transduction in the actomyosin molecular motor by 2',3'-dideoxydidehydro-ATP and characterization of its interaction with myosin subfragment 1 in the presence and absence of actin

The effect of torsional freedom about the N-glycoside bond of ATP in the ability of the nucleoside triphosphate to support chemomechanical transduction (Takenaka et al., 1978) has been investigated by examining the ability of the nucleotide analogue 2',3'-dideoxy-2',3'-didehydro-ATP (1b, enf-ATP) to act as a substrate for myosin subfragment 1 in the presence and absence of actin and to support actin sliding in the standard in vitro motility assay. By converting the ribosyl ring of the natural substrate to the rigid and almost planar enofuranosyl ring, effects on torsional freedom about the N-glycoside bond due to changes in ribosyl ring pucker and/or by steric interferences of the protons attached to the 2' and 3' carbons are eliminated allowing for increased torsional freedom about the N-glycoside bond. The data indicate that this enofuranosyl analogue is an excellent substrate for subfragment 1 and actosubfragment 1 and produces actin sliding velocities which are twice as fast as those observed with ATP in the standard in vitro motility assay. The analogue diphosphate is trapped in S1 by the common P(i) analogues, but the rate of formation of the ternary complex formed with Vi is very slow compared to that observed with MgADP. Similar conformations of S1 are formed with Mg.enf-ATP and MgATP under steady-state conditions, but S1 with bound Mg.enf-ADP differs significantly from that observed with MgADP.

Identification of myosin III as a protein kinase

Drosophila ninaC gene encodes myosin homologous proteins which are classified as myosin III of the myosin superfamily, yet the physiological and biochemical function of myosin III has not characterized. We report here that myosin III does exhibit protein kinase activity. The kinase homologous domain (MYOIIIPK) of myosin III was expressed in the baculovirus expression system and purified to homogeneity. MYOIIIPK phosphorylated a number of proteins including myosin III p132 and smooth muscle myosin regulatory light chain (LC20), suggesting that myosin III is a multifunctional protein kinase. The phosphoamino acid analysis revealed that myosin III is a serine/threonine kinase but not a tyrosine kinase. The observation that MYOIIIPK phosphorylates myosin III suggests that the autophosphorylation might play a role for the regulation of myosin III function. This is the first direct demonstration of kinase activity for the myosin III class.

Enhancement of smooth muscle contraction with protein phosphatase inhibitor 1: activation of inhibitor 1 by cGMP-dependent protein kinase

New method for purification of phosphatase inhibitor 1 (PPI-1) was developed which avoid the phosphorylation of PPI-1 during the purification and provides a high yield of highly pure preparation. Using this preparation, it was shown that PPI-1 was stoichiometrically phosphorylated by cGMP-dependent protein kinase at Thr-35 and the phosphorylated PPI-1 potently inhibited protein phosphatase 1. Addition of the phosphorylated PPI-1 to beta-escin-skinned single smooth muscle cells resulted in force development of the cells at the submaximal pCa2+. The results suggest that the phosphorylation of PPI-1 can be the mechanism for modifying the Ca2+ sensitivity of smooth muscle contractile response.

Modulation of hematopoiesis in mice with a truncated mutant of the interleukin-2 receptor gamma chain

The interleukin-2 (IL-2) receptor gamma chain is indispensable for IL-2-, IL-4-, IL-7-, IL-9-, and IL-15-mediated signaling. Mutations of the human gamma chain cause the X-linked severe combined immunodeficiency (XSCID), showing that T and natural killer cells absolutely require the gamma chain for their development in humans. To elucidate the roles of the gamma chain in hematopoiesis, we have generated mice, by gene targeting, that express a form of the gamma chain lacking the cytoplasmic region. Male mice carrying the truncated gamma-chain mutant, which mimics mutations in patients with XSCID, showed a decrease in the number of lymphocytes and an increase in monocytes; the number of T cells was profoundly reduced and no natural killer cells were detected, which is similar to the characteristic of human XSCID. Unlike human XSCID, the levels of B cells were also reduced. In spite of the severe decrease in CD45R+/sIgM+ B cells, the level of IgM in serum of the 8-week-old mutant mice was higher than that of control littermates. Interestingly, the stem cell population with surface phenotypes of CD34, c-kit, and Sca-1 was significantly increased. Furthermore, the colony-forming assay showed that the mutant mice had 15-fold higher numbers of hematopoietic progenitor cells in the spleen as compared with that of controls. These results indicate that functional loss of the gamma chain causes significant effects on the immunological system in mice.

Functional expression of mammalian myosin I beta: analysis of its motor activity

The motor function of vertebrate unconventional myosins is not well understood. In this study, we initiated the baculovirus expression system to characterize a novel myosin I from bovine adrenal gland that we had previously cloned [Zhu, T., & Ikebe, M. (1994) FEBS Lett. 339, 31-36], which is classified as myosin I beta. The expressed myosin I beta was well extracted when calmodulin was coexpressed in Sf9 cells. The recombinant myosin I beta cosedimented with actin in an ATP dependent manner. The purified myosin I beta was composed of one heavy chain and three calmodulins. The electron microscopic image of myosin I beta confirmed its single-headed structure with a short tail, which is similar to that of brush border myosin I (BBMI). Myosin I beta showed high K+,EDTA--ATPase activity (approximately 0.14 mumol/min/mg) and Ca(2+)-ATPase activity (approximately 0.32 mumol/min/mg), and the KCl/pH dependence of these activities was different from that of conventional myosin. Mg(2+)-ATPase activity of myosin I beta alone was increased above pCa 6, while the actin dependent activity was not affected by Ca2+. Actin sliding velocity of myosin I beta in the absence of Ca2+ was 0.3-0.5 microns/s at 25 degrees C, which is much greater than that of BBMI (< 0.05 microns/s). The actin sliding activity was abolished above pCa 6, and the sliding activity was restored when exogenous calmodulin was added in the absence of Ca2+. Within similar Ca2+ concentrations, one of the three calmodulins was dissociated from myosin I beta. The results suggest that Ca2+ dependent association of calmodulin may function as a regulatory mechanism of myosin I beta motor activity and that the motor activity of mammalian myosin I is largely different among distinct myosin I isoforms.

Developmental and tissue distribution of expression of nonmuscle and smooth muscle isoforms of myosin light chain kinase

Using a combination of Northern and Western blotting and RT-PCR, we demonstrate the existence of a high molecular mass MLCK, which is expressed during chicken embryogenesis. It is expressed in developing smooth muscle containing tissues, and is detected at low concentrations in adult tissues. Direct sequencing of the RT-PCR product from embryonic tissue RNA revealed that the embryonic, high molecular mass MLCK is indeed the previously cloned "nonmuscle MLCK". Therefore, the high molecular mass MLCK should be termed embryonic/non-muscle MLCK isoform. Curiously, cultured embryonic gizzard and vascular smooth muscle cells express the lower molecular mass smMLCK protein, albeit at lower levels than in the in vivo tissues.

Structural basis for actomyosin chemomechanical transduction by non-nucleoside triphosphate analogues

Methylation of 2-[(2,4-dinitrophenyl)amino]ethyl triphosphate (dNOTP) was found to abolish its ability to support actin sliding in the in vitro motility assay. A comparative study of the interaction of myosin subfragment 1 (S1) and actoS1 with methylated (MdNOTP) and non-methylated dNOTP was undertaken. Both analogues were shown to be substrates for S1 NTPase in the presence of K+/EDTA, Ca2+, or Mg2+, although their rates of hydrolysis in the presence of the divalent cations were significantly greater than that occurring for ATP. However, actin had only a marginal effect on the rate of hydrolysis of MdNOTP, in sharp contrast to its effect on the hydrolysis of dNOTP and ATP which were quite similar. Moreover, while dNODP is able to form stable ternary S1 complexes with orthovanadate (Vi) or berylium fluoride (BeFx), whose formation results in increased thermal stability of S1, the methylated diphosphate analogue was unable to do so. These differences can be related to methylation-induced changes in the conformation of dNOTP indicated by molecular-modeling approaches. These studies suggest that methylation prevents the specific interaction of the aryl ring of dNOTP with S1 in the adenine binding region necessary for the formation of the force-producing intermediate (M. D. P*) during the S1 Mg(2+)-NTPase cycle.

Characterization of Ca2+/calmodulin-dependent protein kinase II from smooth muscle

We have characterized chicken gizzard smooth muscle Ca2+/calmodulin-dependent protein kinase II (CaM-PKII) with particular focus on its autophosphorylation. The autophosphorylation of smooth muscle CaMPKII produced a partially constitutively active enzyme, as occurs with the alpha- and beta-isoforms of this enzyme, but the autophosphorylation kinetics were significantly slower. Phosphorylation during the initial rapid phase coincided with the production of constitutively active enzyme. The phosphorylation was on both serine and threonine residues, which is distinct from the brain enzyme where threonine phosphorylation is much faster and more prevalent than serine phosphorylation. The major autophosphorylation sites identified were different from the known autophosphorylation sites of the alpha- and beta-isoforms. During the initial autophosphorylation phase Ser-319, Ser-352 and a Thr residue within residues 345-368 were found to be phosphorylated. During the subsequent gradual phase two serine residues in the variable region and Ser-280 were phosphorylated, but Thr-286 and Thr-305, which are the known major autophosphorylation sites for the alpha- and beta-isoforms, were not detected as the major autophosphorylation sites of smooth muscle CaMPKII. By comparing the phosphopeptide sequence with the known sequences of various isoforms, we concluded that isoform gamma-b, which contains a unique insertion and two deletions at the C-terminal side of the calmodulin binding domain, is the dominant CaMPKII isoform in smooth muscle. The molecular mass of smooth muscle CaMPKII was estimated to be 240 kDa which would comprise four subunits, fewer than in the alpha- and beta-isoforms. The results show that smooth muscle CaMPKII is functionally distinct from the alpha- and beta-isoforms of this enzyme, which might be crucial for its physiological relevance.

Pseudosubstrate sequence may not be critical for autoinhibition of smooth muscle myosin light chain kinase

It has been hypothesized that basic residues in the autoinhibitory region of myosin light chain (MLC) kinase, which resemble the substrate sequence, interact with the catalytic core via charge interaction and thus inhibit the kinase activity (pseudosubstrate inhibitory hypothesis). In the present study, we produced seven MLC kinase mutants in which the residues in the autoinhibitory region are deleted to various extents, and determined the residues crucial for the autoinhibition of the kinase activity. The activities of MT799 (1-799) and MT796 (1-796) were completely inhibited, whereas MT793 (1-793), MT791 (1-791), MT787 (1-787) and MT783 (1-783) were constitutively active. The tryptic proteolysis of MT799 and MT796 activated the kinase activity, presumably due to the removal of the residues essential for autoinhibition. The mutants which showed the constitutively active kinase activity were not further activated by tryptic proteolysis, suggesting that the residues crucial for autoinhibition were already deleted. On the other hand, MT795 (1-795) was partially constitutively active (33% of maximum activity) and the tryptic proteolysis further activated the enzyme activity, suggesting that MT795 loses part of the residues essential for autoinhibition. The substitution of the residues Tyr794-Met795 but not Lys793 of untruncated MLC kinase significantly increased the Ca2+/calmodulin-independent kinase activity. These results clearly show that the region Tyr794-Met795-Ala796 is critical for autoinhibition. This study shows that the pseudosubstrate sequence is not critical for the autoinhibition mechanism of MLC kinase.

Mode of caldesmon binding to smooth muscle thin filament: possible projection of the amino-terminal of caldesmon from native thin filament

The structure of smooth muscle thin filament was examined by various electron microscopy techniques, with special attention to the mode of caldesmon binding. Chemical cross-linking was positively used to avoid the dissociation of accessory proteins upon dilution. Caldesmon in reconstituted thin filament was observed as fine filamentous projections from thin filament. Native thin filament isolated from smooth muscle showed similarly numerous fine whisker-like projections by all the techniques employed here. Antibody against the amino-terminus of caldesmon labeled the end of such projections indicating the possibility that the amino-terminal myosin binding moiety might stick out from the shaft of the thin filament. Such whiskers are often projected out as a cluster to the same side of native thin filament. Further, we could visualize the assembly of dephosphorylated heavy meromyosin (HMM) with native or reconstituted thin filament forming "nonproductive" complex in the presence of ATP. The association of HMM to the shaft of thin filament was through subfragment-2 moiety, in accordance with biochemical studies. Some HMM particles bound closer to the thin filament shaft, possibly suggesting the presence of the second myosin-binding site on caldesmon. Occasionally two kinds of HMM association as such coexisted at a single site on this filament in tandem. Thus, we constructed a structural model of thin filament. The proposed molecular arrangement is not only compatible with all the biochemical results but also provides additional support for our recent findings (E. Katayoma, G. C. Scott-Woo, and M. Ikebe (1995) J. Biol. Chem. 270, 3919-3925) regarding the capability of caldesmon to induce dephosphorylated myosin filament, which explains the existence of thick filaments in relaxed smooth muscle cells.

Mechanical strain increases contractile enzyme activity in cultured airway smooth muscle cells

Smooth muscle hypertrophy is often found in tissue subjected to abnormal physical stress. To determine if physical stress (strain) per se could increase the contractile potential of airway smooth muscle (ASM), we compared cultured ASM cells subjected to strain to control cells (no strain) for rates of 1) myosin light chain kinase (MLCK)-mediated myosin light chain (LC20) phosphorylation, 2) actin-activated myosin ATPase, and 3) myosin light chain phosphatase-mediated myosin dephosphorylation. Lysates from strained cells showed increases in both LC20 phosphorylation activity and actomyosin ATPase activity but decreased rates of phosphatase-dependent myosin dephosphorylation. The increased LC20 phosphorylation activity and ATPase activity of the strained cells were accompanied by increases in cellular content of MLCK and myosin, respectively, compared with control. Because the cultured ASM cells exposed to strain expressed higher MLCK activity and actomyosin ATPase activity but lower myosin light chain phosphatase activity, these data suggest that physical stress in part determines ASM potential for contractile state.

Influence of an anti-angiogenic treatment on 9L gliosarcoma: oxygenation and response to cytotoxic therapy

Tissue oxygen tensions were measured in subcutaneously growing rat 9L gliosarcoma under normal air and carbogen breathing conditions prior to and after i.v. administration of a perflubron emulsion. When these animals were treated with the anti-angiogenic agents TNP-470 and minocycline for 5 days prior to oxygen measurement, tumor hypoxia was decreased compared with untreated tumors. Hypoxia, defined as the percent of pO2 readings < or = 5 mm Hg, was decreased from 71% in untreated air-breathing controls to 34% in animals treated with the anti-angiogenic agents, the perflubron emulsion and carbogen breathing. These effects were manifest in the increased response of the tumor to single-dose (10, 20 and 30 Gy) radiation therapy. Twenty-four hours after treatment with BCNU oxygenation of the tumors was not altered; however, 24 hr after administration of adriamycin oxygenation of the tumors was increased such that hypoxia in adriamycin-treated tumors in animals receiving the perflubron emulsion and carbogen was reduced to 21%. Tumor growth delay in the s.c. tumors was increased by the addition of treatment with the anti-angiogenic agents from day 4 through day 18 post-tumor cell implantation along with BCNU or adriamycin on days 7-11. Administration of the perflubron emulsion and carbogen breathing resulted in increased tumor growth delay with the chemotherapeutic agents alone and in combination with the anti-angiogenic agents. Life span in animals bearing intracranially implanted 9L gliosarcoma progressively increased with administration of the anti-angiogenic agents and then the anti-angiogenic agents and perflubron emulsion/carbogen compared to treatment with BCNU or adriamycin.

Requirement of the two-headed structure for the phosphorylation dependent regulation of smooth muscle myosin

It is known for smooth muscle myosin that while acto-HMM ATPase activity is regulated by phosphorylation, acto-S-1 ATPase activity is not regulated. To clarify the heavy chain structure required for the regulation, smooth muscle myosin containing 7 different lengths of the S-2 portion were expressed in Sf9 insect cells using Baculovirus expression system. Myosin containing longer than 991 residues of heavy chain formed a stable two-headed structure while myosin with shorter than 944 residues of heavy chain formed a single-headed structure, indicating that the residues Gln945-Asp991 are critical for the formation of the two-headed structure. The actin activated ATPase activity of myosin mutants having a two-headed structure was activated by phosphorylation while that of myosin mutants that failed to form the two-headed structure was completely independent of phosphorylation. These results suggest that the two-headed structure is critical for the phosphorylation-dependent regulation.

Autophosphorylation of smooth muscle myosin light chain kinase at its regulatory domain

Autophosphorylation of smooth muscle myosin light chain kinase was initially reported by Foyt et al. [Foyt, H. L., & Means, A. R. (1985) J. Cyclic Nucleotide Protein Phosphorylation Res. 260, 8978-8983], however, the effects of autophosphorylation on the kinase activity as well as the location of the sites have not been elucidated. Here we demonstrate that MLCK is autophosphorylated at three sites, Thr 803, Ser 815, and Ser 823, and this phosphorylation alters MLCK activity. Two phosphorylation sites are located in the regulatory domain of the kinase, the threonine site toward the autoinhibitory region and the serine site (Ser 815) in close proximity to the calmodulin anchoring site. The autophosphorylation was significantly inhibited by the binding of calmodulin. The autophosphorylation at Thr 803 is an intramolecular process, and the alignment of the basic amino acid residues nearby Thr 803 was highly homologous to the phosphorylation site of myosin light chain, suggesting that the regulatory site is in close proximity to the catalytic site in the three-dimensional structure. The phosphorylation at the threonine site activated the calmodulin-independent activity while the phosphorylation at the serine site inhibited the calmodulin-dependent activity due to a decrease in the affinity for calmodulin. This finding shows another example of the activation of calmodulin-dependent kinases by autophosphorylation at its autoinhibitory region and provides a new clue for understanding the calmodulin/MLCK signalling pathway.

Inhibition of 20-kDa myosin light chain exchange by monoclonal antibodies against 17-kDa myosin light chain

Two anti-17,000 Da myosin light chain (LC17) monoclonal antibodies (MM2 and MM10), which increase the actin-activated Mg(2+)-ATPase activity of dephosphorylated smooth muscle myosin, inhibited the exchange of the 20,000 Da regulatory light chain of myosin (LC20). MM2, which shows higher potency of activation of ATPase activity, inhibited the exchange more extensively than MM10, suggesting that there is a correlation between the activation of ATPase activity and the inhibition of the LC20 exchange. The inhibition of the exchange was observed for intact myosin and heavy meromyosin but not subfragment 1, suggesting that the heavy chain at the head-rod junction is involved in the inhibition of LC20 exchange by anti-LC17 antibodies. Alternatively, the interaction between the two heads of the myosin molecule may influence the inhibition of LC20 exchange. These results suggest that LC20 interacts with both LC17 and the heavy chain, and the interaction between LC20 and LC17 is involved in the activation of actin-activated ATPase activity of smooth muscle myosin.

Conformational changes of the myosin heads during hydrolysis of ATP as analyzed by x-ray solution scattering

We have shown for the first time that the myosin head (subfragment-1, S1), the energy-transducing component in the actomyosin motor system undergoes a distinct shape change during hydrolysis of ATP using x-ray solution scattering techniques. Among various analogs for intermediate states of the S1 ATPase cycle, the complexes with MgADP and vanadate (S1.ADP.Vi), MgADP and beryllium fluoride (S1.ADP.BeF3), or MgADP and aluminum fluoride (S1.ADP.AIF4) showed a shape change similar to that in the presence of MgATP, but the complexes with ATP gamma S (S1.ADP gamma S) and MgADP trapped by cross-linking with pPDM (S1.ADP-pPDM) seemed to have a shape similar to that of nucleotide-free S1. These results indicate that the shape of an S1**.ADP.Pi state is more rounded or bent than in other intermediate states of the S1 ATPase cycle. Such changes occur in light chain 2-deficient S1 and also in smooth muscle S1. However, MgADP-fluoride complexes with smooth muscle S1 (without phosphorylation of a regulatory light chain) seemed to have a structure similar to that of nucleotide-free S1. Analysis of x-ray scattering data indicated that a conformational change of S1 in the presence of MgATP might be caused by a hinge-like bending movement between the catalytic and regulatory domains. The global change of S1 is correlated with some specific changes of a nucleotide-binding moiety.

Effect of caldesmon on the assembly of smooth muscle myosin

Smooth muscle myosin filaments are much less stable than the skeletal muscle counterpart. Smooth myosin requires higher concentration of Mg2+ than skeletal myosin to form thick filaments and addition of ATP disassembles the dephosphorylated smooth muscle myosin filaments into monomers but not phosphorylated ones. We found that the addition of caldesmon to dephosphorylated myosin induced the formation of the filaments under the conditions where myosin by itself is soluble or disassembled. Although the induced filaments were short at 1 mM Mg2+, they became medium sized and seemed like side polar filaments with prominent 14 nm periodicity at higher Mg2+ conditions (8 mM). In the presence of F-actin, myosin filaments induced by caldesmon were associated along actin filaments to form large structures. The association of actin and myosin filaments was observed only in the presence of caldesmon, suggesting that caldesmon cross-linked actin and myosin filaments. This cross-linking was disrupted by the addition of calmodulin. Caldesmon-induced filament formation of dephosphorylated myosin in the presence of Mg(2+)-ATP may explain the existence of myosin filaments in relaxed smooth muscle fibers. A similar effect of telokin on myosin filament assembly was also examined and is discussed.

Transient regression in lymphocyte count in B-cell chronic lymphocytic leukemia after viral infection

Transient regression in the lymphocyte count of a patient with B-cell chronic lymphocytic leukemia (B-CLL) after viral infection is reported. A similar event occurred under natural interferon-alpha (IFN-alpha) treatment. It was confirmed that the event was not caused by a direct cytotoxic effect of IFN-alpha by analyzing the DNA fragmentation to estimate apoptotic and necrotic cell death before and after the administration of IFN-alpha. The study also suggested that the event was not caused by a cytostatic effect of IFN-alpha.

Increased efficacy of chemo- and radio-therapy by a hemoglobin solution in the 9L gliosarcoma

Tissue oxygen tensions were measured in the rat 9L gliosarcoma under conditions of normal air breathing or carbogen breathing and after intravenous administration of a hemoglobin solution with air breathing or carbogen breathing. Administration of the hemoglobin decreased the level of hypoxia in the tumors. Treatment of the animals with the antiangiogenic combination of TNP-470 and minocycline also increased tumor oxygenation compared with untreated controls. Treatment with the antiangiogenic agents along with administration of the hemoglobin solution/carbogen breathing decreased the hypoxic fraction (% pO2 readings < or = 5 mmHg) from 71 % to 30%. Treatment of the tumor-bearing animals with BCNU or adriamycin modestly reduced hypoxia in the tumors, while treatment with fractionated radiation markedly increased hypoxia in the tumors. Tumor growth delay was used to assess the response of the subcutaneous tumor to the various treatment combinations. There was a strong correlation between increased therapeutic response and decreased tumor hypoxia. Tumor growth delay from BCNU increased from 5.3 days to 16.4 days with TNP-470/-minocycline/hemoglobin solution/carbogen. Similarly, the tumor growth delay from adriamycin increased from 3.9 days to 17.0 days with TNP-470/minocycline/hemoglobin solution/carbogen. Finally, the tumor growth delay from fractionated radiation increased from 4.8 days to 13.3 days with TNP-470/minocycline/hemoglobin solution/carbogen. When etanidazole was added to the complete radiation regimen, the tumor growth delay increased further to 20.5 days. These data show that the addition of non-toxic agents that increase tumor oxygenation to cytotoxic therapies can markedly increase therapeutic response.

Potentiation of cytotoxic therapies by TNP-470 and minocycline in mice bearing EMT-6 mammary carcinoma

The ability of the antiangiogenic agents TNP-470 and minocycline, singly or in combination, to potentiate the antitumor effects of several cytotoxic therapies was assessed in the murine EMT-6 mammary carcinoma as well as in two drug resistant sublines of that tumor designated EMT-6/CTX and EMT-6/CDDP. The antiangiogenic agents alone or in combination did not alter the growth of the tumors. However, their administration along with cyclophosphamide, CDDP, or thiotepa substantially increased the tumor growth delay produced by these cytotoxic therapies in tumors responsive to the drugs--the increase was about 2-fold for TNP-470 and minocycline together. In drug resistant tumors, treatment with the antiangiogenic agents did not reverse drug resistance but did increase the effect of the cytotoxic drugs. Treatment with TNP-470/minocycline also increased the oxygenation of each of the three tumors. Thus, TNP-470/minocycline administration increased the efficacy of fractionated radiation therapy, especially when used along with a perflubron emulsion oxygen delivery agent/carbogen. These results indicate that treatment regimens including therapies directed toward the proliferating normal cells within a tumor mass as well as therapies directed toward the malignant cells can produce improved outcomes.