Inhibitory effect of a novel non-steroidal aromatase inhibitor, YM511 on the proliferation of MCF-7 human breast cancer cell

The proliferation of MCF-7, human breast cancer cell line, was stimulated by testosterone and estradiol. The aromatase activity in MCF-7 cells, which catalysed the conversion of testosterone to estradiol, was inhibited by a novel non-steroidal aromatase inhibitor, YM5111, with the IC50 of 0.2 nM, indicating that its inhibitory activity was 5.5 times more potent than that of CGS 16949A. YM511 inhibited the proliferation of MCF-7 stimulated by testosterone but did not inhibit the cell proliferation stimulated by estradiol. The IC50 values of YM511 for cell growth and DNA synthesis were 0.13 nM and 0.18 nM, respectively, demonstrating that YM511 was about 3-5 times more potent than CGS 16949A and had no anti-estrogenic or cytotoxic activity. YM511 significantly inhibited testosterone-stimulated transcriptional activation of estrogen-responsive element (ERE) in MCF-7 cells transfected transiently with ERE-luciferase reporter plasmid. The IC50 of YM511 for transactivation was 0.36 nM, suggesting that its inhibitory potency was comparable to the inhibition of aromatase activity of MCF-7 cells. These data may indicate that the inhibition by YM511 of cell proliferation of MCF-7 is attributed to the decreased production of estrogen due to the inhibition of aromatase activity. YM511 may be useful in the treatment of estrogen-dependent cancers.

Slowing of peripheral motor nerve conduction was ameliorated by aminoguanidine in streptozocin-induced diabetic rats

The aims of this study were to investigate the effect of aminoguanidine (AG) on slowing of motor nerve conduction velocity (MNCV) of the sciatic nerve in streptozocin-induced diabetic rats and to assess its mechanism of action. The MNCV of the sciatic nerve was measured electrophysiologically in diabetic rats treated with and without AG for 16 weeks. To elucidate the action of AG, morphological lesion and abnormality of polyol pathway metabolism in the nerve were examined and tissue levels of advanced glycosylation end-products (AGE) were determined as an indicator of AGE accumulation in tissue. Diabetic rats were treated with AG at three doses of 10, 25 and 50 mg/kg for 16 weeks. Myelinated fiber morphometry and nerve Na+,K(-)-ATPase activity were determined. The AGE levels in renal cortex were measured by a specific ELISA. Aminoguanidine dose-dependently ameliorated slowing of MNCV 16 weeks after the treatment without changing body weight or blood glucose levels. No difference in myelinated fiber morphometry or Na+,K(+)-ATPase activity with or without AG treatment was detected in diabetic rats. Diabetes increased the AGE level in the renal cortex by six times compared to non-diabetic rats, and AG reduced the rise in the AGE level by 40%. The MNCV was inversely correlated with the AGE levels. We conclude that improvement of conduction slowing by AG in experimental diabetes may be through decreasing the AGE level in the peripheral tissues. Aminoguanidine may have a therapeutic potential in controlling diabetic peripheral neuropathy.

Novel muteins of human tumor necrosis factor with potent antitumor activity and less lethal toxicity in mice

Eight muteins of recombinant human tumor necrosis factor-alpha (rhTNF; 1SSSRTP...29RR...155L), in which 29Arg was replaced by another amino acid, were prepared and their anti-tumor effects in BALB/c mice bearing Meth A fibrosarcoma were evaluated. The therapeutic indices, which mark the extent of the therapeutically effective dose, of V29 (29Arg-->Val) and D29 (-->Asp) were 3.5 and 3.2, respectively, whereas that of rhTNF was 1.4. Clearly, the therapeutically effective range of these muteins was extended along with a decrease in lethal toxicity. V29 did not produce hypotension in the rat system, but D29 did. In addition, V29 showed potent anti-tumor activity (Tumor Volume Inhibition Rate = 81% on day 15 after implantation) in 3 consecutive injection schedules despite the decreases in toxicity compared with rhTNF. The relative receptor binding constant was determined using HEp-2 cells (expressing mainly 55-kDa-TNF receptor; p55R) and HL60 cells (expressing mainly 75-kDa-TNF receptor; p75R), and revealed that the reduced toxicity of V29 in mice was due to the reduced binding to p55R (34% of rhTNF). On the other hand, the ratio of the constants HEp-2/HL60 of V29 was 11 in comparison with the value of 1.0 for rhTNF, suggesting that this mutein binds preferentially to p55R. The biological activities in human cell lines (HEp-2 and HL60 cells) correlated well with the binding activities to each receptor in vitro. Therefore, the much lower toxicity and the potent anti-tumor activity of this mutein suggest that V29 merits further investigation in pre-clinical and clinical trials.

The potent and selective inhibition of estrogen production by non-steroidal aromatase inhibitor, YM511

YM511 inhibited aromatase activities in microsomes from rat ovary and human placenta competitively (IC50s: 0.4 and 0.12 nM, respectively). YM511 was about 3 times more potent than other aromatase inhibitors, such as CGS 16949A, CGS 20267 and R 76713. YM511 decreased the contents of estradiol stimulated by pregnant mare's serum gonadotropin in rat ovary with an ED50 of 0.002 mg/kg, indicating that YM511 was equipotent to CGS 20267 and 3 times more potent than the other two inhibitors. Serum estradiol levels in female rats were reduced by YM511 at 0.01 mg/kg into the ovariectomized range. YM511 at 1 mg/kg for 2 weeks decreased rat uterine weight to levels comparable to ovariectomy, showing it was 10 times more potent than other inhibitors. But the maximal inhibitory effect of tamoxifen failed to reach ovariectomized level. YM511 slightly inhibited production of other steroid hormones in vitro and in vivo. The IC50s of YM511 for aldosterone and cortisol production from adrenal cells were from 5500 to 9800 times higher than that for rat ovarian aromatase and 130,000 times higher for testosterone production, indicating that YM511 is a highly specific aromatase inhibitor. The data suggest that YM511 may be a potent and selective agent for suppressing estrogen-dependent action without affecting serum levels of other steroid hormones.

Novel mutein of tumor necrosis factor alpha (F4614) with reduced hypotensive effect

To eliminate systemic toxicity, including the hypotension associated with human tumor necrosis factor alpha (TNF-alpha), we constructed mutant proteins (muteins) by mean of genetic engineering. A novel mutein, F4614, containing mutations of 5Thr-->Gly and 6Pro-->Asp, which resulted in the introduction of cell-adhesive Arg-Gly-Asp and 29Arg-->Val, had remarkably reduced hypotensive effects and lower lethality. We present evidence that the Arg-->Val mutation at position 29 is largely responsible for the reduced hypotensive effect. This effect of F4614 was thought to be closely correlated with its low inducibility of nitric oxide and prostaglandin E2 in vivo. In addition, the therapeutically effective dose of F4614 to MethA fibrosarcoma-transplanted mice was increased compared with that of TNF-alpha, indicating a wide therapeutic index. These results indicated that F4614 has several advantages as a systemic therapeutic drug in the treatment of cancer.

Transport and metabolism of glutathione isopropyl ester in cerebrospinal fluid

The transport of glutathione (GSH) or glutathione isopropyl ester (GSH isopropyl ester) to the cerebrospinal fluid (CSF) in rats was estimated by levels of GSH or GSH isopropyl ester and their metabolites in CSF 30 min after the intravenous administration of GSH or GSH isopropyl ester (300 mg/kg). Although the CSF uptake of GSH isopropyl ester was almost equal to that of GSH as evidenced by about a two-fold increase in the amount of non-protein sulfhydryl groups in CSF, the sum of GSH isopropyl ester and GSH concentrations in the CSF after GSH isopropyl ester treatment was increased by 32% compared with saline-treated controls. On the other hand, treatment with GSH had no significant increase in GSH levels in CSF but increased its metabolite levels, such as cysteinyl-glycine and cysteine. GSH isopropyl ester was less metabolized than GSH. GSH isopropyl ester had low affinity to purified gamma-glutamyl transpeptidase, a key enzyme for metabolism of GSH in the choroid plexus, supporting the finding that GSH isopropyl ester is more stable than GSH in CSF. These results are compatible with our previous report (Yamamoto et al. (1993) showing that the protective action of GSH isopropyl ester against cerebral ischemia was greater than that of GSH in rats. GSH isopropyl ester may be a useful agent which protects the brain from the damage associated with oxygen-related toxicities by increasing GSH levels in the CSF.

Overcoming the metastasis-enhancing potential of human tumor necrosis factor alpha by introducing the cell-adhesive Arg-Gly-Asp sequence

A mutein, F4168, of human tumor necrosis factor alpha (hTNF-alpha) containing the cell-adhesive Arg-Gly-Asp (RGD) sequence near the N terminus was constructed. In contrast to hTNF-alpha, the mutein had binding activity to B16F10/L5 melanoma cells similar to that of fibronectin or laminin, indicating that the adhesive nature of the RGD sequence is conferred upon hTNF-alpha. Introduction of the RGD sequence did not alter the antitumor potential of hTNF-alpha. Simultaneous injection of F4168 and B16F10/L5 melanoma cells into mice did not enhance metastasis formation in lungs, whereas hTNF-alpha significantly promoted it. Enhancement of spontaneous lymph node metastasis of B16F10/L5 cells was also evident in TNF-alpha- but not in F4168-treated mice. In the spontaneous lymph node metastasis model of MethA fibrosarcoma, F4168 injection inhibited metastasis formation more effectively than hTNF-alpha. B16F10/L5 melanoma cells treated with hTNF-alpha enhanced not only their binding activity to laminin but also their invasive potential into Matrigel, whereas F4168 showed no such enhancement. These results suggest that F4168 is a low-toxicity mutein of hTNF-alpha.

Antisecretory and antiulcer effects of YM020, a new H+,K(+)-ATPase inhibitor, in rats and dogs

We examined the effects of YM020 (3-cyanomethyl-2-methyl-8-[(3-methyl-2-butenyl)oxy]-imidazo[1,2- a]pyridine), a novel H+,K(+)-ATPase inhibitor, on gastric acid secretion and experimental gastroduodenal lesions in rats and dogs. Intraduodenal, subcutaneous and oral YM020 inhibited basal gastric acid secretion in pylorus-ligated rats with ED50 values of 9.1, 9.1 and 9.5 mg/kg, respectively. Oral pretreatment with YM020 5 hr before ligation still suppressed acid secretion, with a potency a little less than that of omeprazole. In anesthetized dogs, intravenous YM020 inhibited histamine-, methacholine- and pentagastrin-induced gastric acid secretion with ED50 values of 0.05, 0.01 and 0.08 mg/kg, respectively. In Heidenhain pouch dogs, although oral YM020 (3 mg/kg) inhibited histamine-induced acid secretion, acid output returned to control levels faster than in dogs treated with omeprazole. Oral YM020 inhibited the formation of water-immersion restraint stress-, indomethacin-, absolute ethanol-, 0.7 N hydrochloric acid- and cysteamine-induced gastric or duodenal lesions with ED50 values of 2.9, 4.3, 2.0, 11.7 and 8.4 mg/kg, respectively. Moreover, subcutaneous YM020 also suppressed the formation of ethanol- and HCl-induced gastric lesions. These results suggest that YM020 has an antisecretory effect almost the same as or 2 to 3 times weaker than those of omeprazole and that its duration is not as long as that of omeprazole in rats and dogs. Furthermore, YM020 possesses a cytoprotective effect and the mechanism of YM020 may be different to that of omeprazole.

A YIGSR-containing novel mutein without the detrimental effect of human TNF-alpha of enhancing experimental pulmonary metastasis

The injection of B16F10 melanoma cells with recombinant human tumor necrosis factor alpha (TNF-alpha) into the tail vein of C57BL/6 mice resulted in 2- to 25-fold more metastatic foci in the lungs than the injection of tumor cells alone. Clearly, TNF-alpha significantly enhanced experimental tumor metastasis. Furthermore, it enhanced the metastasis of Lewis lung carcinoma cells. In contrast, a mutein of TNF-alpha, designated as F4236, having the cell-adhesive sequence (Tyr-Ile-Gly-Ser-Arg) at the N-terminus of the TNF molecule did not enhance metastasis, but rather exhibited similar antitumor activity to wild-type TNF-alpha in fibrosarcoma-bearing mice.

Effects of acylcarnitine-transferase inhibitors on adenine nucleotide metabolism and ischemic tissue injury in isolated perfused rat heart

The ability of irreversible acylcarnitine-transferase inhibitors, sodium 2[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) and 2-tetradecyl-glycidic acid (TDGA), to reduce myocardial ischemic injury was studied in Langendorff-perfused hearts exposed to ischemia (zero mmHg) followed by aerobic reperfusion (60 mmHg). Rat hearts were pretreated with either POCA (15 mg/kg) or TDGA (5 mg/kg) s.c. 120 min before the perfusion. Treated hearts showed a decreased release of creatine kinase and lactate on reperfusion after 30 min ischemia. POCA-treated hearts showed significantly higher ATP concentrations than control hearts on reperfusion. POCA also improved the maximum recovery of the pressure-rate product but with a significant delay. During the ischemic period, though, POCA decreased the ATP concentration at a rate three times that of controls during the first 10 min. No further reductions were observed for up to 30 min of ischemia. TDGA also showed a reduction of ATP. Thus, the observation that POCA stimulated ATP synthesis and reduced creatine kinase release on reperfusion after ischemia suggests that this agent provides some protection to the ischemic myocardium. However, during ischemia, it is likely that the depletion of ATP concentration induced by POCA resulted in delayed recovery of mechanical function on reperfusion.

Close correlation between restriction fragment length polymorphism of the L-MYC gene and metastasis of human lung cancer to the lymph nodes and other organs

Restriction length fragment polymorphism of the L-MYC gene was examined in DNAs from lung cancer tissues and normal tissues of 51 Japanese patients with lung cancer. In individual patients, no difference was seen between the restriction length fragments of the two alleles of L-MYC [6-kilobase (kb) and 10-kb fragments in EcoRI digests] in lung cancer tissues and normal tissues. But a striking correlation was found between the restriction length fragment polymorphism pattern of L-MYC and the extent of metastasis, particularly to the lymph nodes at the time of surgery: Patients with only the L band (10 kb) had few lymph node metastatic lesions, whereas patients with either the S band (6 kb) or the S and L bands almost always had lymph node metastatic lesion. A similar correlation was found between the presence of the S band and metastases to other organs. This correlation was particularly marked in cases of adenocarcinoma. These results indicate a clear genetic influence on metastases and a consequent poor prognosis for certain patients of lung cancer; L-MYC restriction length fragment polymorphism is thus shown to be a useful marker for predicting the metastatic potential of human lung cancer.

Isolation of a hexaprenylhydroquinone sulfate from the marine sponge Dysidea sp. as an H,K-ATPase inhibitor

A hexaprenylhydroquinone sulfate has been isolated as an H,K-ATPase inhibitor from a marine sponge Dysidea sp. It also inhibited phospholipase A2 as well as secretion of gastric acid in rats.

Effects of nicardipine on ischemic mechanical failure and tissue injury in isolated perfused rat heart

Using a Langendorff rat heart preparation, we examined effects of nicardipine, a calcium channel blocker, on different stages of ischemic damage, characterized by a development of contracture and leakage of intracellular enzymes. Maximum recoveries of heart rate (HR) and peak left ventricular pressure-HR product after 20 min ischemia were attenuated by about 25% compared with those before ischemia. When nicardipine (0.1 mumol) was added to the perfusate 5 min prior to ischemia, this mechanical failure recovered completely to the pre-ischemic level. Although a significant increase in left ventricular end-diastolic pressure was observed in hearts exposed to 30 min ischemia, the amount of creatine kinase (CK) released during re-flow after 30 min ischemia was not enhanced by contracture but was proportional to the duration of ischemia (compared with that of 20 min ischemia). Nicardipine reduced CK leakage by 25% after 30 min ischemia but did not alter either ATP levels or coronary flow. The beneficial effects of nicardipine on ischemic damage are probably related to inhibition of calcium influx (Terai et al: Biochem Pharmacol 30: 375, 1981), which may accompany reperfusion of ischemic myocardium.

Effects of altered thyroid status on beta-adrenergic actions on skeletal muscle glycogen metabolism

The effects of hypothyroidism on glycogen metabolism in rat skeletal muscle were studied using the perfused rat hindlimb preparation. Three weeks after propylthiouracil treatment, serum thyroxine was undetectable and muscle glycogen and Glc-6-P were decreased. Basal and epinephrine-stimulated phosphorylase a and phosphorylase b kinase activities were also significantly reduced, as were epinephrine-stimulated cAMP accumulation and cAMP-dependent protein kinase activity. Conversely, basal and epinephrine-stimulated glycogen synthase I activities were significantly higher while the Ka of the enzyme for Glc-6-P was lower in hypothyroid animals. Propylthiouracil-treated rats also had increased phosphoprotein phosphatase activities towards phosphorylase and glycogen synthase and decreased activity of phosphatase inhibitor 1. beta-Adrenergic receptor binding and basal and epinephrine-stimulated adenylate cyclase activities were reduced in muscle particulate fractions from hypothyroid rats. Administration of triiodothyronine to rats for 3 days after 3 weeks of propylthiouracil treatment restored the altered metabolic parameters to normal. It is proposed that the decreased beta-adrenergic responsiveness of the enzymes of glycogen metabolism in hypothyroid rat skeletal muscle is due to increased activity of phosphoprotein phosphatases and to reduced beta-adrenergic receptors and adenylate cyclase activity.

Modulation by adrenalectomy and fasting of insulin effects in perfused hindlimb muscle

Perfused hindlimb muscle from fed adrenalectomized rats accumulated more 2-deoxyglucose at submaximal concentrations of insulin in comparison to muscle from fed normal rats. However, in the fasted state, insulin-stimulated 2-deoxyglucose uptake was largely inhibited by adrenalectomy. Basal 2-deoxyglucose uptake did not differ between fed and fasted normal or adrenalectomized rats. The changes in insulin effects caused by adrenalectomy were due to altered hexose transport as shown by measurements of 3-O-methylglucose uptake and of intracellular free and phosphorylated 2-deoxyglucose. Muscles of fasted normal and fed or fasted adrenalectomized rats showed higher basal glycogen synthase --glucose-6-P/+glucose-6-P activity ratios than those of fed normal rats probably because of decreased glycogen content. However, muscles from fed or fasted adrenalectomized rats did not show any alterations in insulin effects on the activity ratio and half-maximal activation constant (A0.5) for glucose-6-P of glycogen synthase. Because of the dissociation of the effects of insulin on hexose transport and glycogen synthase in muscle of fasted adrenalectomized rats, it is concluded that the impairment in insulin-stimulated hexose transport in these animals is due to a defect lying beyond the interaction of insulin with its receptor.

Glycogen storage myopathy with abnormal lactate dehydrogenase

We studied a 3 year old girl with mental retardation and limb muscle weakness. The muscle glycogen content was 17.4 mg/g tissue, which was approximately three times higher than normal. There were no other known abnormalities noted in this child that could explain the cause of glycogen storage disease. Our in vitro glycolysis study showed marked increase of pyruvate, but no increase in lactate levels. The observed results suggested to us that an abnormal lactate dehydrogenase might account for the abnormal accumulation of glycogen in the muscle.

Inhibitory effect of epinephrine on insulin-stimulated glucose uptake by rat skeletal muscle

The effect of epinephrine on basal and insulin-stimulated glucose uptake in perfused hindlimbs of fed rats was studied. Insulin increased glucose uptake in a dose-dependent manner from a basal value of 1.5+/-0.3 up to a maximum value of 5.3+/-0.9 mumol/min per 100 g with 6 nM (1 m U/ml). Epinephrine at 10 nM and 0.1 muM also increased glucose uptake to 2.6+/-0.1 and 3.1+/-0.1 mumol/min per 100 g, respectively. These same concentrations of epinephrine, however, suppressed the insulin-stimulated glucose uptake to 3.2+/-0.3 mumol/min per 100 g. Both the stimulatory and inhibitory effects of epinephrine on glucose uptake were completely reversed by propranolol, but were not significantly altered by phentolamine. Uptake of 3-O-methylglucose and 2-deoxyglucose into thigh muscles of the perfused hindlimbs was stimulated fivefold by insulin, but was unaffected by epinephrine. Epinephrine also did not inhibit the stimulation of uptake by insulin. Epinephrine decreased the phosphorylation of 2-deoxyglucose, however, and caused the intracellular accumulation of free glucose. These last two effects were more prominent in the presence of insulin. Whereas epinephrine caused large rises in glucose-6-P and fructose-6-P, insulin did not alter the concentration of these metabolites either in the absence or presence of epinephrine.THESE DATA INDICATE THAT: (a) epinephrine has a stimulatory effect on glucose uptake by perfused rat hindlimbs that does not appear to be exerted on skeletal muscle; (b) epinephrine does not affect hexose transport in skeletal muscle; (c) epinephrine inhibits insulin-stimulated glucose uptake in skeletal muscle by inhibiting glucose phosphorylation. It is hypothesized that the inhibition of glucose phosphorylation is due to the stimulation of glycogenolysis, which leads to the accumulation of hexose phosphates, which inhibit hexokinase.

Studies on the interactions between insulin and epinephrine in the control of skeletal muscle glycogen metabolism

Possible inhibitory effects of insulin on epinephrine-induced changes in the enzymes of glycogen metabolism in skeletal muscle were tested using a perfused rat hindlimb preparation. Epinephrine and/or insulin were infused over a wide range of concentrations. Insulin at 6 X 10(-9) M increased the activity ratio (--Glc-6-P/+Glc-6-P) of glycogen synthase from a basal value of 0.09 +/- 0.01 to 0.13 +/- 0.01 and caused a 23% decrease in the Ka for Glc-6-P. In contrast, epinephrine at 10(-7) M decreased the activity ratio to 0.05 +/- 0.01 and increased the Ka for Glc-6-P 6.3-fold. Insulin was without effect on the concentration of cAMP or the activity ratio (-cAMP/+cAMP) of cAMP-dependent protein kinase and caused a small decrease in the activity ratio (-AMP/+AMP) of phosphorylase, whereas epinephrine caused large increases in all these parameters. Insulin at 6 X 10(-11) to 6 X 10(-8) M had no inhibitory effect on the actions of 10(-8) or 10(-7) M epinephrine on glycogen synthase, phosphorylase or cAMP-dependent protein kinase at 30 min or at earlier times. Insulin (6 X 10(-9) M) also did not alter th concentration of cAMP in the presence of 10(-8) or 10(-7) M epinephrine. These data are not consistent with the view that insulin activates glycogen synthase by producing an inhibitor of cAMP-dependent protein kinase. Nor do they support the hypothesis that insulin acts by decreasing the activity of an inhibitor of a multisubstrate phosphoprotein phosphatase.

Glycogen metabolism in rat liver during transition from the fed to fasted states

Hepatic glycogen metabolism was studied in rats during the period of transition from the fed to fasted states. Glycogenic activity was measured in vivo based on the incorporation of [14C]glucose into liver glycogen. Its changes were almost parallel to the changes in glycogen synthase activity. Progressive accumulation of liver glycogen that occurred in the fed state was associated with a proportional increase in glycogenic activity. Within 4 h after the cessation of food intake, glycogenic activity showed a precipitous fall from the peak to its nadir without significant changes in glycogen content. Meanwhile, the glucose concentration in the portal vein decreased. Upon further development of fasting, glycogenic activity displayed a progressive regain, reciprocally as glycogen contents gradually decreased. The precipitous fall of glycogenic activity during the transition from the fed to fasted states was associated with a transient increase in plasma glucagon, and was partly overcome by the injection of anti-glucagon serum. It is concluded that the fall of portal venous concentration of glucose and secretion of glucagon act as a signal to initiate liver glycogen metabolism characteristic of the fasted or postabsorptive state.