Differanisole A, a novel antitumor antibiotic, enhances growth inhibition and differentiation of human myeloid leukemia cells induced by 9-cis retinoic acid

Differanisole A, 3,5-dichloro-2-hydroxy-4-methoxy-6-n-propylbenzoic acid, inhibited growth of human myeloid leukemia cells. The compound induced G1 arrest and granulocytic differentiation of HL-60 cells, although the differentiation-inducing effect was modest. Differanisole A and 9-cis retinoic acid (9cisRA) synergistically inhibited the growth and induced functional and morphologic differentiation of HL-60 and NB4 cells, whereas the combined treatment with differanisole A and all-trans retinoic acid or 1alpha,25-dihydroxyvitamin D3 was less effective. Similar results were obtained in primary culture of leukemia cells from a patient with acute promyelocytic leukemia. The synergistic effect on growth inhibition and induction of differentiation required simultaneous treatment with differanisole A and 9cisRA. Differanisole A and an RXR-specific ligand (Ro47-5944) cooperatively inhibited the cell growth, while the combined effect of differanisole A and an RAR-specific ligand Am80 was just additive. Differanisole A in combination with 9cisRA may have implications for therapy of acute promyelocytic leukemia patients.

Cotylenin A, a plant-growth regulator, induces the differentiation in murine and human myeloid leukemia cells

Protein factors playing a significant part in differentiation and development have been recently elucidated. However, low molecular factors which also seem to be essential remain still unknown, although only retinoic acid has become such a candidate. Cotylenins had been isolated as the plant-growth regulators, and have been found to affect a number of physiological processes of higher plants. Here we report that at the concentrations above 12.5 microg/ml (20 microM) cotylenin A induced the functional and morphological differentiation in murine (M1) and human myeloid leukemia (HL-60) cells. Although cotylenin A has some similarity to PMA both in carbotricyclic diterpene structure and in biological activity (i.e. differentiation-induction of HL-60 cells into macrophages), the activation of PKC and the elevation of Ca2+-levels by cotylenin A were not observed. Quite recently it has been reported that fusicoccin (closely related to cotylenin A)-targets are 14-3-3 proteins, which are at the crosspoint of a huge array of signalling and regulatory pathways. These results suggest that cotylenin A might become a useful tool for the elucidation of molecular mechanisms of differentiation and development.

Characterization of filamentous phages of Vibrio cholerae O139 and O1

We have analyzed our collection of Vibrio cholerae O139 strains to determine whether filamentous phages are produced in their culture supernatants, and whether any replicative form of DNA is detectable in cell lysates. Two types of filamentous phage, designated fs1 (6.4 kb) and fs2 (8.5 kb), were found in strains of Vibrio cholerae O139, fs1 was commonly produced from clinical isolates of Vibrio cholerae O1. Infectious particles (filamentous phages) were inducible by subculture, mitomycin C, and cultivation in a ligated ileal loop of a rabbit. Type 4 fimbriae of Vibrio cholerae O1 sensitive to D-glucose and D-mannose were suggested to be receptors for fs1 and fs2. The genome of fs1 was revealed to encode a potential new enterotoxin homologous to zonula occludens toxin. Clarification of the relation of type 4 fimbriae and these filamentous phages will provide a new understanding of the colonization of Vibrio-cholerae O1 and O139. Thus the presence of a new enterotoxin encoded by the genome of filamentous phage like fs1 may clarify the pathogenesis of cholera toxin negative clinical isolates of Vibrio cholerae O1 and non-O1. Our findings combined with the earlier report by Ehara et al. [Microbio. Immunol. 37 (1993) 679-688] suggest that type 4 fimbriae of Vibrio cholerae O1 are important for the development of an effective vaccine against cholera.

Induction of differentiation of human myeloid leukemia cells by 2'-deoxycoformycin in combination with 2'-deoxyadenosine

2'-Deoxycoformycin (dCF), a specific and potent inhibitor of adenosine deaminase, has demonstrated significant antitumor effect on lymphoid malignancies. The drug induced functional and morphologic differentiation of myeloid leukemia cells in combination with 2'-deoxyadenosine (dAd), but not dCF alone. NB4, a cell line derived from a patient with t(15; 17) acute promyelocytic leukemia (APL) underwent granulocytic differentiation when treated with all-trans retinoic acid (ATRA) or dCF plus dAd, but not with cytosine arabinoside. Pre-exposure of NB4 cells to ATRA greatly potentiated differentiation induced by dCF plus dAd, but pretreatment with dCF plus dAd before exposure to ATRA was less effective. Differentiation of NB4 cells was effectively induced by clinically applicable concentrations of dCF in combination with dAd. These findings may provide useful information about induction of differentiation in vivo.

Effect of transforming growth factor-beta1 and -beta2 on in vitro rabbit corneal epithelial cell proliferation promoted by epidermal growth factor, keratinocyte growth factor, or hepatocyte growth factor

Corneal epithelial wound healing is intimately controlled by a variety of growth factors, such as epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), and transforming growth factor-betas (TGF-betas). In this study, we investigate the effects of TGF-beta1 and TGF-beta2 on cultured rabbit corneal epithelial cell proliferation promoted by EGF, KGF, or HGF. Both TGF-beta1 and -beta2 dose-dependently inhibited corneal epithelial cell proliferation promoted by KGF (40 ng ml-1) and HGF (40 ng ml-1), and weakly inhibited cell proliferation promoted by EGF (4 ng ml-1). Furthermore, the inhibitory effect tended to be stronger with TGF-beta2 than TGF-beta1. These findings suggest that TGF-beta1 and -beta2 play important roles as negative modulators against the cell proliferation effect of EGF, KGF and HGF.

Conservation of cholera toxin gene in a strain of cholera toxin non-producing Vibrio cholerae O1

BT23, a Vibrio cholerae O1 E1 Tor isolate, possesses the cholera toxin (CT) gene as determined by PCR. However, CT was not detected in the culture medium by the reversed passive latex agglutination test, nor in the whole cell lysate as examined by Western blotting. The toxin-coregulated pilus (TCP) was not detected by Western blotting. This suggests the presence of defects in the regulatory cascade. toxR, toxS and toxT, members of the regulatory cascade, were examined by PCR. toxR and toxS were conserved but toxT was not. CT and TCP production was complemented by transformation of toxT. The lack of toxT was suspected to be the cause of the undetectable production of CT in strain BT23.

Effects of aldose reductase inhibitor CT-112 on the corneal epithelial barrier of galactose-fed rats

PURPOSE

To investigate whether the barrier function of the corneal epithelium is disrupted in galactosemic rats, and to assess the effects of the aldose reductase inhibitor CT-112, in the form of eyedrops, on the corneal epithelial barrier in galactosemic rats.

METHODS

Forty rats were divided into 3 groups based on their diet: a control group, a galactose group and a CT-112 treated galactose group (CT-112 group). After 3 weeks, 31 rats from the 3 groups were subjected to fluorophotometry, in which fluorescein (F) was instilled into one eye and carboxyfluorescein (CF) was instilled into the other eye in a random fashion. The F and CF uptakes were then measured at the central cornea by a slit-lamp fluorophotometer. Three rats from each group were exposed to a horseradish peroxidase (HRP) solution for one hour, and the HRP-reactive substances within the corneal epithelium were also examined via electron microscopy.

RESULTS

There was significantly higher F uptake in the galactose group than in the control (p = 0.003) and CT-112 groups (p = 0.028). There were no significant differences in CF uptake between the 3 groups. Histologically, HRP-reactive substances were found in much greater quantities within the superficial corneal cells of the galactose group than in the control or CT-112 groups.

CONCLUSIONS

These results suggest that cell membrane disruption, as detected by F uptake and HRP penetration, was found in the superficial corneal cells of galactose-fed rats, and that intercellular junction integrity can be assayed by CF uptake and histological evaluation. Moreover, CT-112 eyedrops were effective in improving the corneal epithelial barrier dysfunction of galactose-fed rats.

Tretinoin tocoferil as a possible differentiation-inducing agent against myelomonocytic leukemia

Tretinoin tocoferil is an alpha-tocopherol ester of all-trans retinoic acid (ATRA) and safely used to treat skin ulcers. Tretinoin tocoferil stimulates the formation of granulation tissue in the ulcer, and enhances the migration of guinea pig macrophages and stimulates the proliferation of human skin fibroblasts. These effects are different from those of either ATRA or alpha-tocopherol. Tretinoin tocoferil induces the granulocytic differentiation of human promyelocytic leukemia HL-60 cells, and more than additively enhances cellular differentiation induced by sub-optimal concentrations of ATRA. Tretinoin tocoferil and ATRA synergistically inhibit the proliferation of HL-60 cells, suggesting that tretinoin tocoferil acts differently than ATRA on leukemia cells. Tretinoin tocoferil also enhances the differentiation of HL-60 cells induced by dimethyl sulfoxide, phorbol ester and 1alpha,25-dihydroxyvitamin D3(VD3). Tretinoin tocoferil and VD3 synergistically inhibit the proliferation and induce the differentiation of other myelomonocytic leukemia cells. Toxicity tests in animal models have shown that tretinoin tocoferil is at least 150 times less toxic than ATRA and does not induce teratogenesis. Therefore, the combination of tretinoin tocoferil and VD3 may be useful for treating myelomonocytic leukemia.

TRA1, a novel mRNA highly expressed in leukemogenic mouse monocytic sublines but not in nonleukemogenic sublines

Mouse monocytic Mm-A, Mm-P, Mm-S1, and Mm-S2 cells are sublines of mouse monocytic and immortalized Mm-1 cells derived from spontaneously differentiated, mouse myeloblastic M1 cells. Although these subline cells retain their monocytic characteristics in vitro, Mm-A and Mm-P cells are highly leukemogenic to syngeneic SL mice and athymic nude mice, whereas Mm-S1 and Mm-S2 cells are not or are only slightly leukemogenic. To better understand the molecular mechanisms of these levels of leukemogenicity, we investigated putative leukemogenesis-associated genes or oncogenes involved in the maintenance of growth, especially in vivo, by means of differential mRNA display. We isolated a fragment clone (15T01) from Mm-P cells. The mRNA probed with 15T01 was expressed at high levels in leukemogenic Mm-P and Mm-A cells but not in nonleukemogenic Mm-S1 and Mm-S2 cells. The gene corresponding to 15T01, named TRA1, was isolated from an Mm-P cDNA library. The longest open reading frame of the TRA1 clone predicts a peptide containing 204 amino acids with a calculated molecular weight of 23,049 D. The predicted TRA1 protein is cysteine-rich and contains multiple cysteine doublets. A putative normal counterpart gene, named NOR1, was also isolated from a normal mouse kidney cDNA library and sequenced. NOR1 cDNA predicts a peptide containing 234 amino acids. The sequence of 201 amino acids from the C-terminal NOR1 was completely identical to that of TRA1, whereas the remaining N-terminal amino acids (33 amino acids) were longer than that (3 amino acids) of TRA1 and the N-terminus of NOR1 protein contained proline-rich sequence. A similarity search against current nucleotide and protein sequence databases indicated that the NOR1/TRA1 gene(s) is conserved in a wide range of eukaryotes, because apparently homologous genes were identified in Caenorhabditis elegans and Saccharomyces cerevisiae genomes. Northern blotting using TRA1-specific and NOR1-specific probes indicated that TRA1 mRNA is exclusively expressed in leukemogenic but not in nonleukemogenic Mm sublines and normal tissues and also indicated that NOR1 mRNA is expressed in normal tissues, especially in kidney, lung, liver, and bone marrow cells but not in any Mm sublines. After leukemogenic Mm-P cells were induced to differentiate into normal macrophages by sodium butyrate, the normal counterpart, NOR1, was expressed, whereas the TRA1 level decreased. Furthermore, transfection of TRA1 converted nonleukemogenic Mm-S1 cells into leukemogenic cells. These results indicate that the TRA1 gene is associated at least in part with the leukemogenesis of monocytic Mm sublines.

AML1a but not AML1b inhibits erythroid differentiation induced by sodium butyrate and enhances the megakaryocytic differentiation of K562 leukemia cells

AML1 may play a role in growth and differentiation of cells along erythroid and/or megakaryocytic lineages, because a significant level of the AML1 gene is expressed in these cells. We overexpressed AML1a (without the transcription-activating domain) and AML1b (with the domain) proteins in K562 leukemia cells, which can be induced to differentiate into hemoglobin-producing cells and megakaryocytes. The AML1a-transfected K562 cells had a reduced capacity to differentiate in the presence of sodium n-butyrate but not in the presence of other inducers, such as hemin, 1-beta-D-arabinofuranosylcytosine, and herbimycin A. The AML1 antisense oligodeoxynucleotide but not the sense oligomer recovered its differentiation-inducing capacity in the presence of butyrate. On the other hand, AML1b conferred a similar differentiation-inducing capacity upon K562 cells transfected with vector alone. AML1a expression was associated with enhanced sensitivity to megakaryocytic differentiation induced by phorbol ester. These results provide evidence that AML1 proteins play a role in erythroid and megakaryocytic differentiation.

Glucocorticoids induce apoptosis in acute myeloid leukemia cell lines with A t(8;21) chromosome translocation

The t(8;21) chromosome translocation frequently occurs in the AML, acute myeloid leukemia, M2 sub-type. This translocation juxtaposes the AML1 gene on chromosome 21 with the MTG8(ETO) gene on chromosome 8, resulting in the expression of the AML1-MTG8(ETO) fusion transcript. The fusion product is thought to play a critical role in the abnormal proliferation and differentiation of myeloid leukemia cells. We investigated the effects of various differentiation inducers of myeloid leukemia cells on the growth and differentiation of Kasumi-1 and SKNO-1 cells, AML cell lines with t(8;21). These cells resisted differentiation into mature granulocytes and macrophages in response to various inducers of myelomonocytic differentiation, such as dimethyl sulfoxide, retinoic acid, butyrate, 12-O-tetradecanoylphorbol-13-acetate (TPA) and 1alpha,25-dihydroxyvitamin D3. On the other hand, dexamethasone can induce apoptosis in these cells at low concentrations, whereas other myelomonocytic leukemia cell lines tested were resistant to glucocorticoid-induced apoptosis. The levels of glucocorticoid receptor gene expression were high in Kasumi-1 and SKNO-1 cells. Expression of the AML1-MTG8(ETO), bcl-2, and c-myc genes was unchanged following exposure to dexamethasone. Glucocorticoids might induce the apoptosis of some types of AML cells, just like that of some lymphoid leukemia cells.

Amyotrophic lateral sclerosis: occurrence of Bunina bodies in the locus ceruleus pigmented neurons

Bunina bodies, which are small eosinophilic intracytoplasmic inclusions, have been considered to be specific for amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease of unknown cause in adults. They are found usually in the remaining lower motor neurons. We encountered a 66-year-old woman with sporadic ALS showing Bunina body-like eosinophilic inclusions in the cytoplasm of some pigmented neurons in the otherwise intact locus ceruleus (LC). Ultrastructural examination of the LC confirmed that a few pigmented neurons actually contained inclusions identical to Bunina bodies. The finding indicates that Bunina bodies can occur in LC pigmented neurons and suggests that LC may also be involved in the disease process in ALS.

Digitalization of the mother in treating hydrops fetalis in monochorionic twin with Ebstein's anomaly. Case report

Hydrops fetalis thought to be due to Ebstein's anomaly was seen at 22 weeks' gestation in one of two fetuses with a monochorionic placenta. Hydrops was treated with maternal digitalization and resolved by the 28th week of gestation. Hydrops did not recur while maternal digitalization continued. A clinical diagnosis of twin-to-twin transfusion syndrome required termination of the pregnancy at 33 weeks of gestation. The twin with Ebstein's anomaly died 22 hours after birth. The other twin survived and was normal at 19 months of age. Thus, administration of digitalis to the mother controlled hydrops fetalis in one fetus, and ultimately led to the survival of the healthy infant.

An anti-cancer derivative of butyric acid (pivalyloxmethyl buterate) and daunorubicin cooperatively prolong survival of mice inoculated with monocytic leukaemia cells

A derivative of butyric acid, pivalyloxymethyl butyrate (AN-9), inhibited the proliferation and induced apoptosis of mouse monocytic leukaemia Mm-A cells, although sodium butyrate, but not AN-9, induced differentiation of the cells. AN-9 and DNA-specific antineoplastic agents synergistically inhibited the growth of Mm-A cells, and the simultaneous treatment was required to evoke the maximum growth-inhibitory effect. On the other hand, there was no synergy between butyrate and the drugs, or AN-9 and anti-metabolic agents in inhibiting the growth of the cells, suggesting that the synergistic effect is specific to AN-9 and DNA-reacting agents. AN-9 as a single agent prolonged the survival of mice inoculated with Mm-A cells in a dose-dependent manner. Moreover, administration of AN-9 plus daunorubicin (DNR) markedly prolonged their survival. These results suggest that combination with AN-9 and DNR entails an obvious therapeutic potential.

Evaluation of the radiosensitizing effects of RK28 intravenous, intraarterial, and intratumoral injections on the rabbit VX2 tumor system

PURPOSE

To evaluate the differences in the radiosensitizing effects of intravenous (i.v.) injection, intraarterial (i.a.) injection, and intratumoral (i.t.) injections of the hypoxic cell radiosensitizer RK28 ([1-(4'-hydroxy-2'-butenoxy)methyl-2-nitroimidazole], a 2-nitroimidazole with an acyclic sugar analogue substituted at the N-1 position of the imidazole ring) using an animal experimental system.

METHODS AND MATERIALS

Rabbit VX2 tumors, which were implanted in the muscle of left hind legs and grown to 3 cm in diameter, were treated with RK28 (80 mg/kg x b.wt.) before 15 Gy of local x-ray irradiation. The auricular vein and the left saphenous artery were used for systemic injection and regional injection, respectively. For i.t. injection, a 21-gauge needle with three lateral holes was positioned in the central area of the tumor. Tumor regression was precisely evaluated by computed tomograpy (CT), and survival time was also studied. Using high-performance liquid chromatography (HPLC), pharmacokinetic studies for RK28 and its seven major metabolites were performed in tumor and serum at 0, 10, 20, 30, and 60 min after drug injection was completed.

RESULTS

Radiosensitizing effects of RK28 were considered present after i.a. injection (p < 0.05) and i.t. injection (p < 0.05) after analyzing tumor volumes on day 21 after treatment. Increased survival was not observed in any group with RK28 injection compared with survival in the group treated by x-ray irradiation alone. Pharmacokinetic studies showed the average concentration of RK28 in the tumor during x-ray irradiation was 1.3 times higher after i.a. injection and 3.5 times higher after i.t. injection than that after i.v. injection. The time modifying factor50 (TMF50: ratio of time for tumor to decrease by 50%, radiation alone vs. radiation plus drug) was calculated to be 1.5 after i.v. injection, 1.7 after i.a. injection, and 2.3 after i.t. injection. The values of TMF50 correlated to the average concentrations of RK28 in the tumor. As to metabolites of RK28, beta-glucuronated compound and cysteine conjugate were highly detected. The concentrations of cysteine conjugate were higher in the tumor than in serum via i.v. injection.

CONCLUSIONS

Radiosensitizing effects of RK28 were observed on the rabbit VX-2 tumor system after i.a. or i.t. injection. Pharmacokinetic studies proved that radiosensitizing effects depended on the concentration in the tumor, though the administration routes were different. Combined forms with nonprotein thiols were detected. However, survival benefits were not obtained by RK28. For clinical applications of RK28, i.a. or i.t. injection could facilitate better local control of cancer.

Immunohistochemical and Ultrastructural characterization of the terminal nerve ganglion cells of the ayu, Plecoglossus altivelis (Salmoniformes, Teleostei)

BACKGROUND

Little is known on the cytological properties of the terminal nerve ganglion (TNG) cells in teleosts (Demski, 1993. Acta Anat., 148:81-95).

MATERIALS AND METHODS

To characterize the TNG cells of a salmonoid fish, Plecoglossus altivelis, we adopted immunohistochemistry and transmission electron microscopy (TEM).

RESULTS

The majority of the TNG cells formed a compact mass halfway between the olfactory sac and the olfactory bulb, whereas a few cells were scattered in the ventromedial region of the olfactory bulb. The cell had a voluminous perikaryon that was positive to antisera against gonadotropin-releasing hormone (GnRH), molluscan cardioexcitatory tetrapeptide (FM-RFamide), and neuropeptide Y (NPY). Immunostaining of consecutive sections with each antiserum showed the coexistence of these antigens in the same cells and their processes. Most of the processes originating from the cells projected centrally to the basal forebrain, including the optic nerve. With TEM, the cells revealed a peptidergic nature, i.e., the presence of abundant granular endoplasmic reticula and well-developed Golgi bodies in association with vesicles that were 70-100 nm in diameter. Occasionally, the cells adjoined one another directly without the intervention of glial sheets. Synaptic contacts were frequent in the proximal region of the processes, where thin lateral processes of the cells and axon terminals of unknown origin were intermingled with each other. Terminal buttons being engulfed by the soma were commonly seen.

CONCLUSIONS

The TNG cells of the salmonoid fish share many cytological characteristics with the cells of the nucleus olfactoretinalis of advanced teleosts such as acanthopterygians.

Differentiation inhibitory factor nm23 as a new prognostic factor in acute monocytic leukemia

Differentiation inhibitory factor (nm23 protein) inhibited the induction of differentiation of mouse myeloid leukemia M1 and WEHI-3BD+ and human erythroleukemia HEL, KU812, and K562 cells. Block of differentiation may be associated with the aggressive behavior of leukemia. To examine the role of nm23 in human myeloid leukemia, we investigated the relative levels of nm23-H1, nm23-H2, and c-myc transcripts in 42 patients with acute myelogenous leukemia (AML), and in 5 with chronic myelogenous leukemia at chronic phase by reverse transcriptase polymerase chain reaction. The expression of nm23-H1 and -H2 but not of c-myc in AML was significantly higher than that in normal blood cells. Among AMLs, acute monocytic leukemia (presentation with AML-M5 morphology) was especially associated with elevated nm23-H1 and -H2 mRNA levels. On the other hand, the elevated levels of c-myc expression in AML-M5 were less evident. An analysis of correlation between nm23 expression and clinicopathological parameters showed that resistance to initial chemotherapy is associated with increased nm23-H1 mRNA levels and that a high initial white blood cell count is associated with increased nm23-H2 mRNA levels. Elevated nm23-H1 mRNA levels were associated with significantly reduced the overall survival of AML, especially of AML-M5 patients. The present results indicate that nm23-H1 and -H2 are overexpressed in AML and especially nm23-H1 gene expression predicts the prognosis of AML, especially of AML-M5.

Cloning and genetic analysis of the Vibrio cholerae aminopeptidase gene

The structural gene for the Vibrio cholerae leucine aminopeptidase (lap) was cloned and sequenced. The cloned DNA fragment contained a 1,503-bp open reading frame potentially encoding a 501-amino-acid polypeptide with a calculated molecular mass of 54,442 Da. The deduced amino acid sequence of the entire protein showed high homology with the sequence of Vibrio proteolyticus leucine aminopeptidase. The residues potentially involved in binding the zinc ions were completely conserved in the V. cholerae aminopeptidase as well as in the V. proteolyticus aminopeptidase. The recombinant protein was partially purified and characterized. The molecular mass was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be 34 kDa, suggesting a processing of the protein to acquire the mature form. The protease showed maximum activity at pH 9.0 and was thermostable at 70 degrees C. The substrate leucyl-p-nitroanilide was cleaved by the protease, and its activity was inhibited by EDTA and bestatin. These results suggested that the protein was a leucine aminopeptidase. The PCR analysis of lap gene distribution showed that it was widely distributed among the V. cholerae strains. It was not present in the other species examined.

Ethacrynic acid and 1 alpha,25-dihydroxyvitamin D3 cooperatively inhibit proliferation and induce differentiation of human myeloid leukemia cells

The active form of vitamin D, 1 alpha,25-dihydroxyvitamin D3 (VD3), inhibits proliferation and induces differentiation of leukemia cells, but its clinical use is limited by the adverse effect of hypercalcemia. In this study we found that the loop diuretic ethacrynic acid, which is used to treat hypercalcemia, enhanced the differentiation of human leukemia cells induced by VD3. Ethacrynic acid alone inhibited the proliferation of human promyelocytic HL-60 cells while only slightly increasing differentiation markers such as nitroblue tetrazolium (NBT)-reducing and lysozyme activities. Ethacrynic acid effectively enhanced the growth-inhibiting action of VD3. In the presence of ethacrynic acid, VD3 increased the NBT-reducing and lysozyme activities and the CD11b expression of HL-60 cells more effectively than VD3 alone. Other loop diuretics, furosemide and bumetanide, also enhanced the differentiation of HL-60 cells induced by VD3, but to a lesser extent than ethacrynic acid. The differentiation of HL-60 cells induced by all-trans retinoic acid, dimethyl sulfoxide or phorbol-12-myristate 13-acetate was also enhanced by ethacrynic acid with increasing NBT-reducing and lysozyme activities and the expression of CD11b or CD14 surface antigen. Morphologically, ethacrynic acid enhanced the monocytic differentiation of HL-60 cells induced by VD3 and phorbol ester and the granulocytic differentiation by retinoic acid and dimethyl sulfoxide. Other human myelomonocytic leukemia ML-1, U937, P39/TSU and P31/FUJ cells were induced to differentiate by VD3 and this was also enhanced by ethacrynic acid. The long-term culture of HL-60 cells showed that ethacrynic acid plus VD3 induced the complete growth arrest of HL-60 cells. Therefore ethacrynic acid, which is used to treat hypercalcemia, enhanced the proliferation-inhibiting and differentiation-inducing activities of VD3 and the combination of ethacrynic acid and VD3 may be useful in therapy for myeloid leukemia.

Intramedullary spinal cord and brain metastases from thyroid carcinoma detected 11 years after initial diagnosis--case report

A 60-year-old male presented with a rare intramedullary spinal cord metastasis from thyroid carcinoma manifesting as rapidly worsening motor and sphincter disturbances. The primary tumor had been treated 11 years previously. Magnetic resonance imaging clearly revealed the hemorrhagic tumor localized in the thoracic spinal cord and an associated, asymptomatic metastasis in the cerebellum. The hypervascular tumors were totally removed. The histological diagnosis was papillary adenocarcinoma. He has been stable for 2 years postoperatively. Surgical resection of intramedullary metastasis should be considered in patients with less malignant tumors such as thyroid carcinoma, especially when accompanied by progressive compression myelopathy.

Enhancement of sensitivity of human lung adenocarcinoma cells to growth-inhibitory activity of interferon alpha by differentiation-inducing agents

A low concentration of differentiation inducers such as dimethylsulphoxide (DMSO), sodium butyrate, hexamethylene bisacetamide and sodium phenylacetate greatly enhanced the antiproliferative effect in vitro and in vivo of interferon alpha (IFN-alpha) to several human lung adenocarcinoma cells. The agents induced morphological changes in the adenocarcinoma cells and the agents together with IFN-alpha-induced alkaline phosphatase activity, which is a typical marker of type II pneumocyte maturation. To understand the mechanism of the DMSO-enhanced interferon sensitivity, we examined the effect of DMSO on high-affinity IFN-alpha receptor and interferon-stimulated promoter-binding factors. The lung adenocarcinoma cells were not impaired in IFN-alpha receptor and interferon-stimulated gene transactivation factor 3 (ISGF-3). Our data suggest that the enhancement of interferon sensitivity in the lung adenocarcinoma cells acts downstream of the activation of ISGF-3.