Synthesis and histone deacetylase inhibitory activity of new benzamide derivatives.

Newly synthesized benzamide derivatives were evaluated for their inhibitory activity against histone deacetylase. The structure of these derivatives was unrelated to the known inhibitors, and IC(50) values of the active compounds were in the range of 2-50 microM. Structure-activity relationship on the benzanilide moiety showed that the 2'-substituent, an amino or hydroxy group, was indispensable for inhibitory activity. Although the electronic influence of the substituent in the anilide moiety showed only a small effect on inhibitory activity, the steric factor in the anilide moiety, especially at positions 3'and 4', played an important role in interaction with the enzyme. Among these benzamide derivatives, MS-275 (1), which showed significant antitumor activity in vivo, has been selected for further investigation.

Synthesis of glucuronides of multidrug resistance reversing drug MS-209.

We synthesized the glucuronides of MS-209 to identify the two main unknown metabolites in human urine. Reaction of MS-209 and glucuronyl trichloroacetimidate gave two beta-isomers, which were each glucuronate of (R)- and (S)-MS-209. These spectrum data were identical with the metabolites.

Structure-activity relationship of newly synthesized quinoline derivatives for reversal of multidrug resistance in cancer.

The effect of 24 newly synthesized quinoline derivatives on tumor cell multidrug resistance (MDR) was examined in vitro. At low concentrations, these compounds enhanced the accumulation of [3H]vincristine in K562/ADM cells and reversed tumor cell MDR. The results of the structure-activity relationship analysis indicate that in highly active compounds the two aryl rings in the hydrophobic moiety deviate from a common plane, so they are capable of interacting with hydrogen bond donors of P-170 glycoprotein (P-gp) via pi-hydrogen-pi interactions. Other major structural features which influence the MDR-reversing activities of these compounds are a quinoline nitrogen atom and a basic nitrogen atom in piperazine. Furthermore, in highly active compounds, the distance between the hydrophobic moiety and the basic nitrogen atom (an atom connected to 2-hydroxypropoxyquinoline) must be at least 5 A. Several compounds were found to reverse vincristine resistance in K562/ADM cells in vitro, and compound 16 (MS-209) was selected for clinical studies.

Potentiation of the antitumor activity by a novel quinoline compound, MS-209, in multidrug-resistant solid tumor cell lines.

A novel quinoline compound, MS-209, was examined for its ability to reverse multidrug resistance (MDR) in several murine and human MDR solid tumor cell lines both in vitro and in vivo. MS-209 strongly reversed drug resistance to adriamycin (ADM) and vincristine (VCR) in acquired MDR tumor cell lines, 2780AD and KB-C1. In addition, MS-209 enhanced the cytotoxic effect of ADM and VCR on various human and murine cell lines. Particularly in 4-1St cells, which are extremely resistant to ADM and VCR, MS-209 at a concentration of 3 microM enhanced the cytotoxicity of ADM and VCR, 88- and 350-fold, respectively. MS-209 administered orally, together with ADM, enhanced the antitumor activity of ADM on Colon 26 and 4-1St tumors implanted subcutaneously (SC) in mice; the antitumor effect of ADM plus MS-209 was higher than that of ADM alone at the maximum tolerated dose (MTD). Furthermore, the coadministration schedules of MS-209 to attain the highest potentiation of ADM activity were examined using Colon 26 tumors. The maximum antitumor activity was obtained when MS-209 was administered on the same day as ADM. MS-209 administered a day before the ADM injection exhibited no potentiation effect, whereas MS-209 administered a day after the ADM injection showed a moderate effect. The effect of MS-209 was weaker when administered in a fractionated manner than when administered as a single dose. The results presented in this article suggest that MS-209 is an effective agent to overcome MDR in cancer chemotherapy.

Reversal of multidrug resistance by a novel quinoline derivative, MS-209.

MS-209, a novel quinoline derivative, was examined for its reversing effect on multidrug-resistant tumor cells. MS-209 at 1-10 microM completely reversed resistance against vincristine (VCR) in vitro in multidrug-resistant variants of mouse leukemia P388 cells (VCR-resistant P388/VCR and Adriamycin (ADM)-resistant P388/ADM) and human leukemia K562 cells (VCR-resistant K562/VCR and ADM-resistant K562/ADM). MS-209 at 1-10 microM also completely reversed resistance against ADM in vitro in P388/VCR cells, K562/VCR cells, and K562/ADM cells. In ADM-resistant P388 (P388/ADM) cells, however, ADM resistance was only partially reversed at the MS-209 concentrations tested. MS-209 enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When MS-209 was given p.o. at 80 mg/kg twice a day (total dose, 160 mg/kg per day) with 100 micrograms/kg VCR, a treated/control (T/C) value of 155% was obtained. MS-209 also enhanced the chemotherapeutic effect of ADM in P388/ADM-bearing mice. The most prominent effects were obtained when MS-209 was given with 2 mg/kg ADM, yielding T/C values of 150%-194% for the combined treatment at an MS-209 dose of 200-450 mg/kg. MS-209 inhibited [3H]-azidopine photolabeling of P-glycoprotein efficiently. Furthermore, the accumulation of ADM in K562/ADM cells was increased more efficiently by MS-209 than by verapamil. These results indicate that MS-209, like verapamil, directly interacts with P-glycoprotein and inhibits the active efflux of antitumor agents, thus overcoming multidrug resistance in vitro and in vivo.

Relationship between multidrug resistant gene expression and multidrug resistant-reversing effect of MS-209 in various tumor cells.

MS-209 is a novel quinoline compound which can overcome multidrug resistance (MDR) both in vitro and in vivo, while having a low level of side effects, and is now being evaluated in a clinical phase II study. Reverse transcription-polymerase chain reaction (RT-PCR) was used to quantitate the expression levels of MDR genes in various mouse and human tumor cell lines. The MDR gene and the beta actin gene, as the internal reference standard, were coamplified separately, and the relative expression of the MDR gene was represented by the MDR/beta actin ratio. The in vitro MDR-reversing effect of MS-209 was then compared with the MDR gene expression (MDR/beta actin ratio). We found a significant correlation between these two parameters. Moreover, a significant correlation was also observed between the level of expression of the MDR1 gene and that of P-glycoprotein in human cell lines. Therefore, the efficacy of MS-209 seems to specifically depend on the level of MDR gene expression (P-glycoprotein). From these observations, it is suggested that RT-PCR assays of MDR1 gene in tumor biopsy specimens might be an effective means to predict the response of tumor cells to combination therapy with MS-209.

Circumvention of multidrug resistance by a newly synthesized quinoline derivative, MS-073.

Newly synthesized quinoline derivatives were investigated for their efficacy to reverse multidrug resistance (MDR). In this study, one of the most effective quinoline derivatives, MS-073, was compared with verapamil with regard to its ability to overcome MDR in vitro and in vivo. MS-073 at 0.1 microM almost completely reversed in vitro resistance to vincristine (VCR) in VCR-resistant P388 cells. The compound also reversed in vitro VCR, adriamycin (ADM), etoposide, and actinomycin D resistance in ADM-resistant human myelogenous leukemia K562 (K562/ADM) cells, ADM-resistant human ovarian carcinoma A2780 cells, and colchicine-resistant human KB cells. MS-073 administered i.p. daily for 5 days with VCR enhanced the chemotherapeutic effect of VCR in VCR-resistant P388-bearing mice. Increases in life span of 19-50% were obtained by the combination of 100 micrograms/kg of VCR with 3-100 mg/kg of MS-073, as compared to the control. The ability of MS-073 to reverse MDR was remarkably higher, especially at low MS-073 doses, than that of verapamil, both in vitro and in vivo. MS-073 enhanced accumulation of [3H]VCR in K562/ADM cells. Photolabeling of P-glycoprotein with 200 nM [3H]azidopine in K562/ADM plasma membranes was completely inhibited by 10 microM MS-073, indicating that MS-073 reverses MDR by competitively inhibiting drug binding to P-glycoprotein.

Stimulatory effect of 4-alkylcatechols and their diacetylated derivatives on the synthesis of nerve growth factor.

A series of 4-alkylcatechols and 1,2-diacetoxy-4-alkylbenzenes (from methyl to butyl) were chemically synthesized for in vitro evaluation as stimulators of nerve growth factor (NGF) synthesis. All compounds were proven to be potent in stimulating NGF synthesis in L-M cells (a mouse fibroblast cell line) and mouse astroglial cells. In a series of 4-alkylcatechols, 4-methylcatechol and 4-ethylcatechol severely affected viability and cell adhesive properties. In a series of 1,2-diacetoxy-4-alkylbenzenes, the concentrations required for the maximal effect and the effective ranges of concentrations were higher than those in the 4-alkylcatechol series, and the cell adhesive properties or viabilities were not affected. Evidence is also presented to indicate that the elevation of NGF synthesis by these compounds was not associated with the cell growth.