Structure-activity studies for a novel series of bicyclic substituted hexahydrobenz[e]isoindole alpha1A adrenoceptor antagonists as potential agents for the symptomatic treatment of benign prostatic hyperplasia

In search of a uroselective alpha1A subtype selective antagonist, a novel series of 6-OMe hexahydrobenz[e]isoindoles attached to a bicyclic heterocyclic moiety via a two-carbon linker was synthesized. It was found that in contrast to the previously described series of tricyclic heterocycles,(1) this bicyclic series has very specific requirements for the heterocyclic attachments. The most important structural features contributing to the alpha1A/alpha1B selectivity of these compounds were identified. In vitro functional assays for the alpha1 adrenoceptor subtypes were used to further characterize the most selective compounds, and in vivo models of vascular vs prostatic tone were used to assess uroselectivity. Compound 48 showed the highest degree of selectivity in the radioligand binding assays (56-fold), in the in vitro functional tests (80-fold), and for in vivo prostate selectivity (960-fold).

Structure-activity studies for a novel series of tricyclic substituted hexahydrobenz[e]isoindole alpha(1A) adrenoceptor antagonists as potential agents for the symptomatic treatment of benign prostatic hyperplasia (BPH)

In search of a uroselective agent that exhibits a high level of selectivity for the alpha(1A) receptor, a novel series of tricyclic hexahydrobenz[e]isoindoles was synthesized. A generic pharmacophoric model was developed requiring the presence of a basic amine core and a fused heterocyclic side chain separated by an alkyl chain. It was shown that the 6-OMe substitution with R, R stereochemistry of the ring junction of the benz[e]isoindole and a two-carbon spacer chain were optimal. In contrast to the highly specific requirements for the benz[e]isoindole portion and linker chain, a wide variety of tricyclic fused heterocyclic attachments were tolerated with retention of potency and selectivity. In vitro functional assays for the alpha(1) adrenoceptor subtypes were used to further characterize these compounds, and in vivo models of vascular vs prostatic tone were used to assess uroselectivity.

Ascorbate stimulates type I and type III collagen in human Tenon's fibroblasts

PURPOSE

To better understand wound healing after glaucoma filtration surgery by measuring the production of type I and type III collagen in cultured Tenon's fibroblasts and determine the effect of ascorbic acid on collagen subtype production.

METHODS

An ELISA-type dot blot assay was used to directly measure the production of types I and III collagen by subconfluent cultures of fibroblasts from human Tenon's capsule. Because ascorbic acid is both high in aqueous humor and necessary for the production of collagen, we measured the dose response of type I and type III collagen production to ascorbic acid.

RESULTS

Ascorbic acid stimulated an increase in collagen production that reached a maximum level at 100 micrograms/ml. This is approximately half of the ascorbic acid concentration found in human aqueous humor. Unlike previous reports, we found no toxic effects from ascorbic acid at concentrations as high as 250 micrograms/ml over a 24-hour period. The lack of toxicity may result from the use of serum-free media in the assay.

CONCLUSIONS

This culture system will be useful for exploring factors that may alter collagen production and could potentially affect wound healing.

1,25-Dihydroxyvitamin D3 regulation of c-myc protooncogene transcription. Possible involvement of protein kinase C

1,25-Dihydroxyvitamin D3 (1,25-(OH)2D3) regulates the expression of c-myc protooncogene in HL-60 promyelocytic leukemia cells (Reitzma, P. H., Rothberg, P. G., Astrin, S. M., Trial, J., Barshavit, Z., Hall, A., Teitelbaum, S. U., and Kahn, A. J. (1983) Nature 306, 492-494). The regulation of c-myc expression occurs at least in part at the transcriptional level (Simpson, R. U., Hsu, T., Begley, D. A., Mitchell, B. S., and Alizadeh, B. N. (1987) J. Biol. Chem. 262, 4104-4108). Also, 1,25-(OH)2D3 stimulates an increase in protein kinase C (PKC) levels and inhibitors of PKC block 1,25-(OH)2D3-induced differentiation of HL-60 cells (Martell, R. E., Simpson, R. U., and Taylor, J. M. (1987) J. Biol. Chem. 262, 5570-5575). In this report we demonstrated that sphinganine, an inhibitor of PKC that is mechanistically and structurally distinct from 1-(5-isoquinoline sulfonyl)-2-methylpiperazine-HCl (H-7), also blocks 1,25-(OH)2D3 induction of HL-60 cell differentiation. The effect of inhibitors of PKC on 1,25-(OH)2D3 regulation of c-myc transcription was examined. H-7 (18 microM) and sphinganine (3 and 6 microM) blunted 1,25-(OH)2D3-induced reduction of c-myc transcription as assessed by nuclear run-off assays. We showed that c-myc/beta-actin ratios (cpm/cpm, % of control mean +/- S.E.) were as follows: ethanol control, 100 +/- 14%; 50 nM 1,25-(OH)2D3, 17 +/- 5%; 50 nM 1,25-(OH)2D3 and 6 microM H-7, 13 +/- 6%; 50 nM 1,25-(OH)2D3 and 18 microM H-7, 53 +/- 6% 50 nM 1,25-(OH)2D3 and 18 microM N-[2-guanidinoethyl]-5-isoquinoline sulfonamide (HA-1004), 10 +/- 8%; 50 nM 1,25-(OH)2D3 and 6 microM sphinganine, 49 +/- 8%. No significant differences in c-myc transcription between control, 18 microM H-7, 18 microM HA-1004, and 3 or 6 microM sphinganine-treated cells were observed. The block in c-myc transcription was beyond exon 1, and regulation of exon 1 transcription by 1,25-(OH)2D3 was not detected. Furthermore, we demonstrated that expression of markers for HL-60 cell differentiation was more rapidly induced by 25 nM 12-O-tetradecanoylphorbol-13-acetate than 50 nM 1,25-(OH)2D3, suggesting that direct activation of PKC by phorbol esters may make processes required for 1,25-(OH)2D3 induction of differentiation unnecessary. In summary, these data suggest that a primary effect of 1,25-(OH)2D3 on HL-60 cells is to regulate PKC levels, and regulation of c-myc transcription by 1,25-(OH)2D3 is a result of this action.