Abstract 2823: Immunodeficient mice differentially sensitize to estrogen and exhibit severe estrogen-related adverse effects in orthotopic breast cancer model

Estrogen-induced growth induction and stimulation of hormone receptor positive breast cancer is commonly acknowledged and thus external estrogen stimulus is used in animal models to support and accelerate growth of the tumors. However, estrogen is known to have adverse effects in the animals and the experiments may have to be preliminary terminated due to animal welfare issues. The aim of the study was to characterize and to compare estrogen caused adverse effects in athymic nude and NOG mice in orthotopic breast cancer model.

Athymic nude (Hsd:Athymic Nude-Foxn 1nu) and CIEA NOG (NOD.Cg-Prkdcscid Il2rgtm1Sug/JicTac, provided by Taconic Biosciences) were implanted with estrogen (17β-estradiol, E2) releasing hormone rods (5 µg/day) prior to cancer cell inoculation. 5x106 BT-474 (ER, PR and HER+) human breast cancer cells were inoculated to left inguinal mammary fat pad of the mice and the tumor growth was monitored by measuring the tumor volumes twice a week by caliber. The clinical condition and weight development of the mice was carefully monitored with special attention to E2-caused adverse effects. If the mice met the termination criteria (i.e. significant weight loss or general worsening of the overall health) they were sacrificed individually before the intended end of the study.

Nude mice exhibited severe estrogen-caused adverse effects as no adverse effect were observed in NOG mice. Most common adverse effect was redness and skin lesions in the urogenital area observed in 63% of the animals. More severe effects were observed in the lower urinary track including urinary stones and bladder obstruction in 67% of the mice. Also internal effects were observed including appearance change in kidneys and spleen in size and color. Due to severity of these effects 50% of the mice had to preliminary sacrificed. Tumor take (100% vs 85%) and final tumor volumes in average (110 mm2 vs 120 mm2) were comparable between nude and NOG mice.

A clear mouse strain specific impact was observed in the study. Nude mice sensitize to estrogen and exhibit severe estrogen-related adverse effects as no effects were observed in NOG mice. In breast cancer studies where E2 supplementation is needed for sufficient tumor growth, the choice of mouse strain should be carefully considered. Special attention should be paid to possible adverse effects keeping in mind the animal welfare issues.

Citation Format: Tiina E. Kähkönen, Mari I. Suominen, Jenni Mäki-Jouppila, Jussi Halleen, Azusa Tanaka, Michael P. Seiler, Jenni Bernoulli. Immunodeficient mice differentially sensitize to estrogen and exhibit severe estrogen-related adverse effects in orthotopic breast cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2823. doi:10.1158/1538-7445.AM2017-2823

BTB-ZF factors recruit the E3 ligase cullin 3 to regulate lymphoid effector programs

The differentiation of several T and B cell effector programs in the immune system is directed by signature transcription factors that induce rapid epigenetic remodeling. We report that PLZF, the BTB-ZF transcription factor directing the innate-like effector program of NKT thymocytes ^1,2 was prominently associated with cullin 3 (Cul3), an E3 ubiquitin ligase previously shown to use BTB domain-containing proteins as adaptors for substrate binding ^3–7. PLZF transported Cul3 to the nucleus where the two proteins were associated within a chromatin modifying complex. Furthermore, PLZF expression resulted in selective changes of ubiquitination of multiple components of this complex. Cul3 was also found associated with another BTB-ZF transcription factor, Bcl6, which directs the B cell germinal center and the T follicular helper programs. Conditional deletion in mice demonstrated an essential role of Cul3 for the development of PLZF- and Bcl6-dependent lineages. We conclude that distinct lineage-specific BTB-ZF transcription factors recruit Cul3 to alter the ubiquitination pattern of their associated chromatin modifying complex. We propose that this novel function is essential to direct the differentiation of several T and B lymphocyte effector programs, and may also be involved in the oncogenic role of PLZF and Bcl6 in leukemias and lymphomas ^8,9.

Elevated and sustained expression of the transcription factors Egr1 and Egr2 controls NKT lineage differentiation in response to TCR signaling

Interactions driven by the T cell antigen receptor (TCR) determine the lineage fate of CD4(+)CD8(+) thymocytes, but the molecular mechanisms that induce the lineage-determining transcription factors are unknown. Here we found that TCR-induced transcription factors Egr2 and Egr1 had higher and more-prolonged expression in precursors of the natural killer T (NKT) than in cells of conventional lineages. Chromatin immunoprecipitation followed by deep sequencing showed that Egr2 directly bound and activated the promoter of Zbtb16, which encodes the NKT lineage-specific transcription factor PLZF. Egr2 also bound the promoter of Il2rb, which encodes the interleukin 2 (IL-2) receptor β-chain, and controlled the responsiveness to IL-15, which signals the terminal differentiation of the NKT lineage. Thus, we propose that persistent higher expression of Egr2 specifies the early and late stages of NKT lineage differentiation, providing a discriminating mechanism that enables TCR signaling to 'instruct' a thymic lineage.

Immune response to helper dependent adenoviral mediated liver gene therapy: challenges and prospects

Adenovirus-mediated gene therapy holds significant potential especially for applications requiring high levels of target tissue transduction. While significant advances in clinical adenoviral gene therapy applications have been made in cancer, the clinical translation of adenoviral gene replacement therapy for genetic disease has lagged. Encouragingly, advances in vector production have led to the development of Helper-Dependent ("gutted" or "high capacity") adenoviral vectors (HDV) deleted of all viral coding genes. HDV significantly reduces the chronic toxicity associated with early generation adenoviral vectors that has been most significant after systemic administration in both small and large animal models. However, the field remains confounded by innate immune responses inherent to adenovirus, and more generally, to the adaptive immune response to transgene. Together they decrease the effective therapeutic index for any particular treatment. This review summarizes the current advances toward understanding the decisive cell and molecular mechanisms underlying the acute toxicity to systemic HDV administration. We focus on the complex immune response and consequences of systemic vector delivery in the context of liver-directed monogenic disease therapy. Future development of interventions to avoid the innate immune response, including vector and pharmacologic manipulations, should further contribute to minimizing vector toxicity while maximizing the efficacy of systemic HDV gene transfer.

Correction of murine hemophilia A and immunological differences of factor VIII variants delivered by helper-dependent adenoviral vectors

Bioengineering of the factor VIII (FVIII) molecule has led to the production of variants that overcome poor secretion and/or rapid inactivation. We tested six modified FVIII variants for in vivo efficacy by expressing them from helper-dependent adenoviral (HD-Ad) vectors. We constructed a wild-type (WT) variant, a B-domain-deleted (BDD) variant, a point mutant for improved secretion (F309S), a variant with a partial B-domain deletion for improved secretion (N6), a combination of the point mutant and partial BDD variant (F309N6), and an inactivation-resistant (IR8) FVIII variant. All the constructs expressed functional protein after injection of high-dose HD-Ad. Activity ranged from 20 to 50% with WT, to approximately 100% with the N6 and F309N6 variants. Interestingly, mice treated with N6 showed long-term FVIII activity and phenotypic correction for up to 74 weeks, with low anti-FVIII antibody titer. Importantly, the N6 variant was therapeutically efficacious even after a 50% reduction of viral dose, thereby indicating that transgene modification itself can improve the dose efficacy of HD-Ad. This finding is significant, because dose efficacy is a key factor in clinical application. In summary, bioengineering of the FVIII molecule may be an effective approach to improving the safety, immunogenicity, and efficacy of HD-Ad gene therapy in hemophilia A (HA).

Dendritic Cell Function After Gene Transfer with Adenovirus-calcium Phosphate Co-precipitates

Dendritic cells (DCs) are essential for initiating and directing antigen-specific T-cell responses. Genetic modification of DC is under study for cancer immunotherapy, vaccine development, and antigen-targeted immunosuppression. Adenovirus (Ad) type 5 (Ad5)-mediated gene transfer to mouse bone marrow DCs and human monocyte-derived DCs is inefficient because neither express the cognate high-affinity Ads receptor. We show that co-precipitating adenoviral vectors with calcium phosphate (CaPi) increased gene expression (2000-fold) and transduction efficiency (50-fold) in mouse DC, primarily owing to receptor-independent viral uptake. Moreover, Ad5:CaPi-treated DCs were activated to express the maturation surface molecules CD40 and CD86, and to secrete proinflammatory cytokines tumor necrosis factor-alpha and interleukin 6. However, neither DC transduction nor maturation was dependent on viral protein interactions with cell surface integrin. Ad5:CaPi also transduced human DC more efficiently than Ad5 alone, similar to a genetically modified vector (Ad5f35) targeted to the CD46 receptor. As such, this approach combines the efficiency of adenoviral-mediated endosomal escape and nuclear trafficking with the receptor independence of nonviral gene delivery. Importantly, CaPi co-precipitation could be used to functionally modify DC to activate and expand cytomegalovirus-specific memory cytotoxic T lymphocytes. This study identifies a simple technique to improve the efficacy of current Ad5 gene transfer, in support of clinical adoptive immunotherapy.

Toll-like Receptor 9 Triggers an Innate Immune Response to Helper-dependent Adenoviral Vectors

A major obstacle to the clinical application of systemic adenoviral gene replacement therapy is the host innate immune response. Although recent studies have attempted to characterize the cellular basis for this response to systemically administered helper-dependent adenoviral vector (HD-Ad), the underlying molecular components of the innate immune repertoire required to recognize the viral vector have yet to be identified. Here, we show that primary macrophages can sense HD-Ad vectors via the Toll-like Receptor 9 (TLR9) and respond by increasing pro-inflammatory cytokine secretion. Moreover, TLR9 sensing is involved in the rapid innate immune response to HD-Ad in vivo. TLR9 deficiency attenuates the innate immune response to HD-Ad, whereas TLR9 blockade reduces the acute inflammatory response after intravenous injection of the vector. Moreover, HD-Ad upregulates TLR9 gene expression independent of TLR9 function, suggesting that additional innate signaling pathways work cooperatively with TLR9. The identification of the components of the innate immune response to adenovirus will facilitate the development of combinatorial therapy directed at increasing the maximal tolerated dose of systemically delivered adenoviral vectors.

Adeno-associated virus types 5 and 6 use distinct receptors for cell entry

The transduction efficiency of adeno-associated virus (AAV) vectors in various somatic tissues is determined primarily by the viral capsid proteins. In contrast to vectors made with AAV type 2 capsids, those having type 5 or 6 capsids show high transduction rates in airway epithelial cells, in a range that should be sufficient for treating lung disease. Here we have compared the properties of vectors made with AAV5 or AAV6 capsid proteins to determine whether their receptor usage is similar, and found several differences between the viruses. First, an AAV6 vector did not hemagglutinate red blood cells, whereas an AAV5 vector did, and this property was sialic acid dependent. Second, AAV5 vector transduction required sialic acid in all cells tested, whereas AAV6 vector transduction was sialic acid dependent or independent, depending on the target cells tested. Third, levels of an AAV6 vector that interfered with entry of another AAV6 vector only poorly inhibited AAV5 vector transduction and vice versa. These results indicate that AAV5 and AAV6 vectors use distinct cellular receptors for cell entry. Although both AAV5 and AAV6 vectors exhibited high transduction rates in well-differentiated human airway epithelial cultures, they exhibited distinct cell-type transduction profiles in mouse lung that may reflect differences in receptor usage.

Helper-dependent adenoviral gene therapy mediates long-term correction of the clotting defect in the canine hemophilia A model

BACKGROUND

Adenoviral vector-mediated gene therapy might have potential for long-term correction of the monogenic disease hemophilia A.

OBJECTIVE

In this study, we tested the efficacy of administering a helper-dependent adenoviral vector (HDV) designed for maximal liver-restricted canine factor VIII (cFVIII) expression on three out-bred hemophilia A dogs.

METHODS

Three FVIII-deficient animals from the University of North Carolina colony were injected with 1 x 10(12) (Dog A), and 3 x 10(12) (Dog B and C) vp kg(-1) helper-dependent adenoviral vector, and we performed systematic analysis of toxicity, persistence of therapeutic gene expression, and molecular analysis of gene transfer.

RESULTS

We observed acute dose-dependent elevation in liver enzymes and thrombocytopenia after injection, although both were transient and resolved within 2 weeks. The whole blood clotting time (WBCT), plasma FVIII concentration, FVIII activity, and activated partial thromboplastin time in all animals improved significantly after treatment, and two animals receiving a higher dose reached near normal WBCT with low-level FVIII activity until terminal sacrifice at 3 months, and 2 years. Importantly, the treated dogs suffered no bleeding events after injection. Moreover, we observed persistent vector-specific DNA and RNA in liver tissue collected from one high-dose animal at days 18 and 79, and could not detect the formation of inhibitory antibodies.

CONCLUSION

Although vector-associated toxicity remains an obstacle, a single injection of HDV led to long-term transgene expression and vector persistence in two FVIII-deficient animals with conversion of their severe phenotype to a moderate one.

Foxj1 is required for apical localization of ezrin in airway epithelial cells

Establishment and maintenance of epithelial cell polarity depend on cytoskeletal organization and protein trafficking to polarized cortical membranes. ERM (ezrin, radixin, moesin) family members link polarized proteins with cytoskeletal actin. Although ERMs are often considered to be functionally similar, we found that, in airway epithelial cells, apical localization of ERMs depend on cell differentiation and is independently regulated. Moesin was present in the apical membrane of all undifferentiated epithelial cells. However, in differentiated cells, ezrin and moesin were selectively localized to apical membranes of ciliated airway cells and were absent from secretory cells. To identify regulatory proteins required for selective ERM trafficking, we evaluated airway epithelial cells lacking Foxj1, an F-box factor that directs programs required for cilia formation at the apical membrane. Interestingly, Foxj1 expression was also required for localization of apical ezrin, but not moesin. Additionally, membrane-cytoskeletal and threonine-phosphorylated ezrin were decreased in Foxj1-null cells, consistent with absent apical ezrin. Although apical moesin expression was present in null cells, it could not compensate for ezrin because ERM-associated EBP50 and the beta2 adrenergic receptor failed to localize apically in the absence of Foxj1. These findings indicate that Foxj1 regulates ERM proteins differentially to selectively direct the apical localization of ezrin for the organization of multi-protein complexes in apical membranes of airway epithelial cells.

Thixotropic solutions enhance viral-mediated gene transfer to airway epithelia

Adenovirus-mediated gene transfer to airway epithelia is inefficient in part because its receptor is absent on the apical surface of the airways. Targeting adenovirus to other receptors, increasing the viral concentration, and even prolonging the incubation time with adenovirus vectors can partially overcome the lack of receptors and facilitate gene transfer. Unfortunately, mucociliary clearance would prevent prolonged incubation time in vivo. Thixotropic solutions (TS) are gels that upon a vigorous shearing force reversibly become liquid. We hypothesized that formulating recombinant adenoviruses in TS would decrease virus clearance and thus enhance gene transfer to the airway epithelia. We found that clearance of virus-sized fluorescent beads by human airway epithelia in vitro and by monkey trachea in vivo were markedly decreased when the beads were formulated in TS compared with phosphate-buffered saline (PBS). Adenovirus formulated in TS significantly increased adenovirus-mediated gene transfer of a reporter gene in human airway epithelia in vitro and in murine airway epithelia in vivo. Furthermore, an adenovirus encoding the cystic fibrosis transmembrane regulator (CFTR) gene (AdCFTR) formulated in TS was more efficient in correcting the chloride transport defect in cystic fibrosis airway epithelia than AdCFTR formulated in PBS. These data indicate a novel strategy to augment the efficiency of gene transfer to the airways that may be applicable to a number of different gene transfer vectors and could be of value in gene transfer to cystic fibrosis (CF) airway epithelia in vivo.

The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing

The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

Structure-activity relationships in the trans-hexahydroindolo[4,3-ab]phenanthridine ("benzergoline") series. 2. Resolution, absolute configuration, and dopaminergic activity of the selective D1 agonist CY 208-243 and its implication for an "extended rotamer-based dopamine receptor model"

4,6,6a,7,8,12b-Hexahydroindolo[4,3-ab]phenanthridines ("benzergolines") was the first structural class of potent and selective dopamine D1 agonists lacking a catechol group. In order to determine the enantioselectivity of the 7-methyl derivative in the adenylate cyclase assay, its 5,5a-dihydro precursor was resolved and both enantiomers oxidized to the final products. The biological activity was found to reside entirely in the (-)-enantiomer, (-)-1 (CY 208-243). An X-ray study of its (-)-mandelic acid salt revealed a 6aR,12bR absolute configuration, which, in confirmation of the structure hypothesis, corresponds to that of the ergolines. Unexpectedly, an axial conformation of the N-methyl group was observed in the crystal structure. In contrast, subsequently analyzed crystals of the free base of (-)-1 revealed an equatorial conformation of the N-methyl group, which, we assume, represents the bioactive conformation. Based on the determined absolute configuration, (-)-1 could be oriented in a previously described "rotamer-based dopamine receptor model", which allowed the localization of a "subtype selectivity-inducing site" (aryl binding site at the D1 receptor, steric barrier at the D2 receptor), marked by the conformationally fixed "additional" phenyl group of the benzergoline molecule.

SDZ 216-525, a selective and potent 5-HT1A receptor antagonist

The pharmacological properties of SDZ 216-525, methyl 4-(4-[4-(1,1,3-trioxo-2H-1,2-benzoisothiazol-2-yl)butyl]-1-p iperazinyl)1H- indole-2-carboxylate, a new selective and potent 5-HT1A receptor antagonist, are described in vitro (and comparisons made with those of MDL 73005 and NAN 190, two putative 5-HT1A receptor antagonists) and in vivo. In radioligand binding studies, SDZ 216-525 showed high affinity and selectivity for 5-HT1A sites (pKD = 9.2) as compared to 5-HT1B, 5-HT1C, 5-HT1D, 5-HT2 and 5-HT3 sites (pKD = 6.0, 7.2, 7.5, 5.2 and 5.4, respectively). The affinity of the compound for alpha 1, alpha 2, beta 1 and beta 2 adrenoceptors, and dopamine D2 receptors was at least 50-100 times lower than for 5-HT1A sites. The effects of SDZ 216-525, MDL 73005 and NAN 190 on 5-HT1 receptor-linked second messengers were characterised in the following tests: inhibition of forskolin-stimulated adenylate cyclase activity in calf hippocampus (5-HT1A), rat substantia nigra (5-HT1B) and calf substantia nigra (5-HT1D) and stimulation of inositol phosphate production in pig choroid plexus (5-HT1C). SDZ 216-525 potently antagonised the effects of 8-OH-DPAT (8-hydroxy-2-[N-dipropyl-amino]-tetralin) on 5-HT1A receptors (pKB = 10) and displayed no intrinsic activity in this test, whereas it behaved at best as a weak antagonist on the other receptor models (pKB values < 6.9).(ABSTRACT TRUNCATED AT 250 WORDS)

5-HT1-like receptors mediate 5-hydroxytryptamine-induced contraction of guinea-pig isolated iliac artery

1. The effects of 5-hydroxytryptamine (5-HT) and of the 5-HT1-like receptor agonists, 5-carboxamidotryptamine (5-CT) and sumatriptan (GR43175) were investigated in isolated ring preparations of guinea-pig common iliac artery. 2. The three agonists induced very weak, if any, contractions of unstimulated preparations, whereas they elicited concentration-dependent contractions in preparations given a moderate tone by a threshold concentration of prostaglandin F2 alpha (PGF2 alpha). 3. Under the latter conditions, Emax values for 5-HT and 5-CT reached about 45% of PGF2 alpha maximal effect, whereas the Emax value of sumatriptan was significantly lower (about 35%). The rank order of potency (mean EC50 value, nM) was 5-CT (6.6) greater than 5-HT (22.9) greater than sumatriptan (155). Pargyline, cocaine or deoxycorticosterone were without significant effect on the contractions induced by 5-HT. 4. The 5-HT3 receptor antagonist, (1 alpha H, 3 alpha,5 alpha H-tropan-3-yl) 1-H-indole-3-carboxylic acid ester (ICS 205-930; 1 microM), had no effect on 5-HT-, 5-CT- and sumatriptan-induced contractions. 5. The 5-HT2 receptor antagonist, ketanserin (1 microM) caused only small rightward shifts (concentration-ratios, about 2) in the concentration-response curves to 5-HT, 5-CT and sumatriptan without significantly depressing the maximum effects. 6. In the presence of ketanserin (1 microM), the non-selective 5-HT receptor antagonist, methiothepin (0.1 microM), shifted the concentration-response curves to 5-HT and 5-CT to the right in a parallel manner and to a similar extent for both agonists (respective mean pKB values, 8.07 and 8.27). The effect of sumatriptan was also antagonized by methiothepin, but solvent effects precluded quantitative analysis of this antagonism. 7. It is concluded that 5-HT1-like receptors mediate the contractions induced by 5-HT, 5-CT and sumatriptan in guinea-pig isolated iliac artery. For reasons not yet understood, these receptors are detected only when the tissues are moderately pre-contracted by PGF2alpha.

trans-hexahydroindolo[4,3-ab]phenanthridines ("benzergolines"), the first structural class of potent and selective dopamine D1 receptor agonists lacking a catechol group

In contrast to the many selective dopamine (DA) D2 receptor agonists known, only two prototypes of selective D1 receptor agonists have been described; both show preference for the periphery due to their catechol partial structures. Our search for non-catechol, selective D1 agonists was based on the hypothesis that D1 selectivity could be conferred upon ergolines by annulation with a phenyl ring. The target molecules, trans-4,6,6a,7,8,12b-hexahydroindolo-[4,3-ab]phenanthridi nes ("benzergolines"), were efficiently synthesized by using the Ninomiya enamide photocyclization reaction. These compounds were found to be as active as the most potent D1 agonists in the adenylate cyclase D1 receptor model, but showed no activity in the ACh release D2 receptor assay. The acquired subtype selectivity of the novel structures was accompanied by an enhanced potency and efficacy as compared to the corresponding ergolines. This points to a D1 affinity enhancing, D2 receptor discriminating role for the additional phenyl group and provides further support for the existence of a D1 receptor specific accessory aryl binding site. Thus the benzergolines represent the first structural class of potent and selective D1 agonists lacking a catechol group which should allow an efficient central nervous system penetration. On the basis of these results, the D1 agonist pharmacophore has to be revised in the sense that potent activity requires neither a catechol function nor an orthogonal conformation of the aromatic rings.

Characterization of dopamine receptor subtypes by comparative structure-activity relationships: dopaminomimetic activities and solid state conformation of monohydroxy-1,2,3,4,4a,5,10,10a-octahydrobenz[g]quinolines and its implications for a rotamer-based dopamine receptor model

A series of phenolic (cis)- and (trans)-1,2,3,4,4a,5,10,10a-octahydrobenz[g]quinolines were investigated in the D1 and D2 dopamine (DA) models, DA-sensitive adenylate cyclase and electrically evoked acetylcholine release, respectively, and were compared with the effects of the corresponding aminotetralins. A similar structure-activity pattern was found at both DA receptor subtypes. The change from the bicyclic to the tricyclic DA analogs resulted in a loss of activity of all beta-rotameric 8-hydroxy derivatives, suggesting the presence of a steric barrier. Derivatives of the alpha-rotameric 6-hydroxy trans series, in contrast to their inactive cis analogs, showed stimulatory effects that increased from N-methyl to N-n-propyl substitution, indicating an interaction with an N-alkyl binding site. The inactivity of the corresponding N-n-butyl derivative ("N-butyl phenomenon") suggests that the N-alkyl substituents of this series point toward a "small N-alkyl binding site," which can be differentiated from a "large N-alkyl binding site." An X-ray of the active (-)-enantiomer of (trans)-6-hydroxy-N-n-propyloctahydrobenz[g]quinoline-(R)-mandelat e revealed a 4aR, 10aR absolute configuration, corresponding to that of (-)-5-hydroxy-2-(N,N-di-n-propylamino)tetralin. The hydrogen bonding interactions of the axial N+-H proton and the hydroxy group to mandelate anions in the crystal provide a model for a possible drug-receptor interaction. Molecular modeling served to localize the steric barrier and the boundaries of the small N-alkyl binding site, which together form an "extended steric barrier." The results led to the proposal of a refined version of a rotamer-based general DA receptor model, which is supplemented by criteria for the orientation of DA agonists. Its application is demonstrated with apomorphine and ergoline.

CY 208-243: a unique combination of atypical opioid antinociception and D1 dopaminomimetic properties

Here we describe the potent antinociceptive action of the indolophenanthridine, CY 208-243, which has high affinities to the dopamine D1 binding and the opioid sites as well as to the 5-HT1A site. The antinociceptive action was comparable to that of morphine in most, but not all models of nociception, nevertheless, basic differences exist in its overall profile. Antagonism of CY 208-243's antinociceptive action was only possible with either high doses of naloxone or not at all and no cross-tolerance with morphine in CY 208-243 tolerant rats occurred. The biochemical basis for dependence liability may be absent and no opioid activity was observed in cultured hippocampal cells. Physical dependence did not occur after programmed administration in the rhesus monkey, nor did CY 208-243 cause respiratory depression in the rat (rather a stimulation). Lack of generalization in fentanyl-trained rats strongly suggests that CY 208-243 lacks opioid-like subjective cues. The coexistence of D1 dopaminergic and atypical opioid agonist properties represents a unique pharmacodynamic combination which is not shared with any other analgesic, and may provide safe and innovative pain therapy.

Structure-activity relationships of dopaminergic 5-hydroxy-2-aminotetralin derivatives with functionalized N-alkyl substituents

5-Hydroxy-2-aminotetralin derivatives in which one N-alkyl substituent carries a functional group have been prepared and their dopaminergic activities compared with those of 5-hydroxy-2-(di-n-propylamino)tetralin (5-OH-DPAT) and known ergolines. Several members of the series demonstrated high affinities in dopamine (DA) receptor binding and DA agonist properties in the rotational behavior model in the range of known potent ergolines. The results suggest that the accessory binding site for the larger N-alkyl substituent of the 5-hydroxy-2-aminotetralins can accommodate various neutral and bulky functionalities and is probably identical with the site(s) to which the 8-substituents of the ergolines bind.

Further characterization of structural requirements for agonists at the striatal dopamine D2 receptor and a comparison with those at the striatal dopamine D1 receptor. Studies with a series of monohydroxyaminotetralins on acetylcholine release from rat striatum

A series of phenolic hydroxy-2-aminotetralins with either a primary or a tertiary (N,N-di-n-propylated) amino group was investigated on electrically evoked acetylcholine release from striatal slices of reserpinized rats, a dopamine (DA) D2 receptor model. 7-Hydroxy-2-aminotetralin (7-OH-AT) was found to be the most active inhibitor among the primary amines, whereas 5-hydroxy-2-(N,N-dipropylamino)tetralin (5-OH-DPAT) was the most potent compound among the tertiary amines; in the 7-OH series, the activity resided in the (2R)-enantiomers, in contrast to the 5-OH series, where the (2S)-enantiomers represented the effective form. A similar structure-activity pattern was earlier found for the same series of DA agonists at the striatal DA D1 receptor. Differences between the effects of the compounds at the two DA receptor subtypes concerned the N,N-dipropyl substitution which influenced the D2 activity much more pronouncedly, and an added 6-OH group (i.e., a catechol function), which seemed to be of foremost importance at the D1 site. These results suggest two similar major binding sites for the DA receptor subtypes, but differences with respect to additional binding sites. According to this model, DA would interact with both DA receptor subtypes in the beta-rotamer conformation; however, N,N-dipropylation similarly should cause a change in preferred conformation toward the alpha-rotamer form. The potency with respect to acetylcholine release correlated with [3H] spiroperidol binding, but not with [3H]DA binding, confirming that the former binding involves the active site of the D2 receptor.