In an attempt to produce better cytotoxic analogues, chemotherapeutic antineoplastic radicals including an alkylating nitrogen mustard derivative of D-phenylalanine (D-melphalan), reactive cyclopropane, anthraquinone derivatives [2-(hydroxymethyl)anthraquinone and the anticancer antibiotic doxorubicin], and an antimetabolite (methotrexate) were coupled to suitably modified agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH). Analogues with D-lysine' and D-ornithine6 or N8-(2,3-diaminopropionyl)-D-lysine and N8-(2,3-diaminopropionyl)-D-ornithine were used as carriers for one or two cytotoxic moieties. The enhanced biological activities produced by the incorporation of D amino acids into position 6 of the agonistic analogues were further increased by the attachment of hydrophobic cytotoxic groups, resulting in compounds with 10-50 times higher activity than LH-RH. Most of the monosubstituted agonistic analogues showed high affinities for the membrane receptors of human breast cancer cells, while the receptor binding afnities of peptides containing two cytotoxic side chains were lower. Chemotherapy has been, for many decades, one of the main approaches for the treatment of malignant neoplasms. Despite the development of modem, more specific cytotoxic drugs, their nonselective action on cells other than cancerous ones remains a major problem. A recent modality for the treatment of hormone-sensitive tumors is based on the use of agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH) (1). Some LH-RH agonists substituted in position 6, 10, or both are much more active than LH-RH and also possess prolonged activity (1-3). Changes in positions 1, 2, 3, and 6 and occasionally in positions 5 and 10 of the LH-RH molecule lead to the formation of powerful antagonists (1-4), which inhibit the release of LH and folliclestimulating hormone from the pituitary, create a state of sex-steroid deprivation, and thus have potential therapeutic applications in the treatment of some hormone-dependent cancers such as those of prostate and breast (1, 5).Ideal anticancer drugs would theoretically be those that eradicate cancer cells without harming normal cells. Some hormonal peptide analogues carrying antineoplastic agents could be used for endocrine therapy and at the same time for targeted chemotherapy of cancers that possess receptors for their peptide moieties on tumor cell membranes.

The effects of treatment with a bombesin receptor antagonist [D-Tpi6, Leu13 psi (CH2NH) Leu14]BN(6-14)(RC-3095) and the combination of an agonist of luteinizing hormone-releasing hormone [D-Trp6]-LH-RH and somatostatin analog D-Phe-Cys-Tyr-D-Trp-Lys-Val- Cys-Trp-NH2 (RC-160) were studied in nude mice bearing xenografts of the hormone-dependent human prostate tumor PC-82. During the 5 weeks of treatment, tumor growth was decreased in all treated groups compared with controls. Bombesin antagonist RC-3095 and the combination of [D-Trp6]-LH-RH and RC-160 caused a greater inhibition of tumor growth than [D-Trp6]-LH-RH or RC-160 alone as based on measurement of tumor volume and percentage change in tumor volume. The largest decrease in tumor weight was also seen in the groups treated with the bombesin antagonist and with the combination of RC-160 and [D-Trp6]-LH-RH. Serum prostatic-specific antigen levels were greatly decreased, and insulin-like growth factor I (IGF-I) as well as growth hormone levels were reduced in all treated groups. Specific binding sites for [D-Trp6]-LH-RH, epidermal growth factor (EGF), IGF-I, and somatostatin (SS-14) were found in the tumor membranes. Receptors for EGF were significantly down-regulated by treatment with the bombesin antagonist or RC-160. Combination of LH-RH agonists with somatostatin analog RC-160 might be considered for improvement of hormonal therapy for prostate cancer. The finding that bombesin antagonist RC-3095 inhibits the growth of PC-82 prostate cancer suggests the merit of further studies to evaluate the possible usefulness of antagonists of bombesin in the management of prostatic carcinoma.

Specific receptors for bombesin/gastrin-releasing peptide, somatostatin, and EGF were investigated in 15 human colon cancer specimens. Eight of 15 clinical specimens (15%) of colon cancer showed the presence of somatostatin receptors. Octapeptide somatostatin analogs, RC-160 and RC-121, showed 10 times higher binding affinity for somatostatin receptors on colon cancer membranes than somatostatin. Analysis of 125I-Tyr4-bombesin binding data revealed the presence of specific binding sites in six (40%) specimens of human colon cancer. Scatchard analysis of 125I-labeled bombesin indicated a single class of receptors in three specimens with an apparent Kd value of 2.5 nM and two classes of receptors with high (Kd = 0.4 +/- 0.2 nM) and low affinity (Kd = 1.6 +/- 0.4 microM) in three other specimens. The 125I-Tyr4-bombesin binding capacities in the colon cancers for high affinity binding sites were from 6 to 228 fmol/mg protein and for low affinity binding sites 76 +/- 15 pmol/mg protein. None of the membrane preparations made from normal colonic mucosa specimens showed specific binding for 125I-Tyr4-bombesin. Five pseudononapeptide (psi 13-14) bombesin (6-14) antagonists, with different modifications at Positions 6 and 14, synthesized in our laboratory, inhibited the binding of 125I-Tyr4-bombesin in nanomolar concentrations. No correlation was found between the degree of differentiation and the presence of binding sites for somatostatin or bombesin. Specific binding of EGF was detected in 80% of colon cancer specimens. EGF binding capacity in colon cancer membranes was on average twice as high as in normal colon mucosa (50 +/- 21 vs 28 +/- 14 fmol/mg protein, respectively). Specific binding sites for somatostatin and EGF, but not bombesin, were also demonstrated in human colon cancer cell line HT-29. In HCT-116 colon cancer line only EGF receptors were found. These receptor findings and our in vivo studies on inhibition of colon cancer growth support the merit of continued evaluation of somatostatin analogs and bombesin/gastrin-releasing peptide antagonists in the management of colonic carcinoma.

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Background and purpose:The effects of hydrogen peroxide (H2O2) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca 2+ )-induced] and the effect of such treatment on anti-oxidative enzyme activities. Experimental approach: Uteri were isolated from virgin Wistar rats and suspended in an organ bath. Uteri were allowed to contract spontaneously or in the presence of Ca 2+ (6 mM) and treated with H2O2 (2 mM-3 mM) over 2 h. Anti-oxidative enzyme activities (manganese superoxide dismutase-MnSOD, copper-zinc superoxide dismutase-CuZnSOD, catalase-CAT, glutathione peroxidase-GSHPx and glutathione reductase-GR) in H2O2-treated uteri were compared with those in uteri immediately frozen after isolation or undergoing spontaneous or Ca 2+ -induced contractions, without treatment with H2O2. The effect of inhibitors (propranolol, methylene blue, L-NAME, tetraethylamonium, glibenclamide and 4-aminopyridine) on H2O2-mediated relaxation was explored. Key results: H2O2 caused concentration-dependent relaxation of both spontaneous and Ca 2+ -induced uterine contractions. After H2O2 treatment, GSHPx and MnSOD activities were increased, while CuZnSOD and GR (In Ca 2+ -induced rat uteri) were decreased. N w -nitro-L-arginine methyl ester antagonized the effect of H2O2 on Ca 2+ -induced contractions. H2O2-induced relaxation was not affected by propranolol, potentiated by methylene blue and antagonized by tetraethylamonium, 4-aminopyridine and glibenclamide, with the last compound being the least effective. Conclusions and implications: H2O2 induced dose-dependent relaxation of isolated rat uteri mainly via changes in voltagedependent potassium channels. Decreasing generation of reactive oxygen species by stimulation of anti-oxidative pathways may lead to new approaches to the management of dysfunctional uteri.

Human breast carcinoma (MCF-7 MIII), which exhibits an estrogen-independent but estrogen-responsive phenotype, was xenografted in 8-9-week-old intact female athymic nude mice without estrogen supplementation. In this model, we investigated inhibitory effects of the modern luteinizing hormone-releasing hormone (LH-RH) antagonist SB-75 and the agonist D-Trp6-LH-RH. The analogs were administered in the form of sustained delivery systems (microcapsules and microgranules). In the first experiment, treatment lasted 10 weeks. After 9 weeks of treatment, a significant inhibition of tumor volume was first found only in the group treated with SB-75, but the final tumor volume was significantly suppressed both by D-Trp6-LH-RH and SB-75. In the second experiment, treatment was started 70 days after tumor transplantation and was continued for 6 weeks. Chronic treatment with SB-75 or D-Trp6-LH-RH appeared to completely arrest tumor growth as measured by tumor volume, percentage change in tumor volume, and tumor weight. Serum estradiol was suppressed to undetectable levels and LH levels were also diminished. Histologically, the regressive changes in the treated tumors were due to the enhancement of apoptosis (programmed cell death) of tumor cells. Membrane receptor assays showed that LH-RH binding sites were down-regulated in tumor cells after treatment with SB-75 or D-Trp6-LH-RH. The results indicate that the antagonist SB-75, released from sustained delivery systems, can inhibit the growth of MCF-7 MIII tumors as effectively as the agonist D-Trp6-LH-RH, but more rapidly. In view of its immediate blockade of the pituitary-gonadal axis and the absence of side effects, the LH-RH antagonist SB-75 might be considered as a possible new hormonal agent for the treatment of breast cancer.

These results indicate that oxcarbazepine, gabapentin, and topiramate are effective in the writhing model in mice, in a dose range, which is not related to motor impairment; topiramate is the most potent and the most tolerable drug.

The aim of this study was to determine the plasma selenium (Se), copper (Cu), and zinc (Zn) levels and to evaluate their possible association with metabolic syndrome (MetS) components in patients with schizophrenia. The study group consisted of 60 patients with schizophrenia and 60 sex- and age-matched healthy controls. Anthropometric measurements, blood pressure, and biochemical analysis of fasting blood were performed in all subjects. Patients with schizophrenia had significantly higher plasma Cu concentrations compared with controls (0.97 ± 0.31 vs. 0.77 ± 0.32 mg/L, p = 0.001). The plasma Cu concentration showed a positive correlation with plasma glucose and diastolic blood pressure in the patient groups (r s = 0.263, p < 0.05 and r s = 0.272, p < 0.05, respectively). The plasma Se level correlated positive with MetS score (r s = 0.385, p < 0.01), waist circumference (r s = 0.344, p < 0.05), plasma glucose (r s = 0.319, p < 0.05), and triglyceride concentrations (r s = 0.462, p < 0.001) in patients with schizophrenia. Plasma Zn did not correlate with any of the MetS components. These results suggest that alterations in plasma Cu and Se levels in medicated patients with schizophrenia could be associated with metabolic risk factors.