Synergistic Cytotoxicity of Pyrazoloacridine with Doxorubicin, Etoposide, and Topotecan in Drug-Resistant Tumor Cells

Discovery of Indolo[3,2-c]isoquinoline Derivatives as Novel Top1/2 Dual Inhibitors with Orally Efficacious Antitumor Activity and Low Toxicity

Topoisomerase (Top) inhibitors used in clinical cancer treatments are limited because of their toxicity and severe side effects. Noteworthily, Top1/2 dual inhibitors overcome the compensatory effect between Top1 and 2 inhibitors to exhibit stronger antitumor efficacies. In this study, a series of indolo[3,2-c]isoquinoline derivatives were designed as Top1/2 dual inhibitors possessing apparent antiproliferative activities. Mechanistic studies indicated that the optimal compounds 23 and 31 with increasing reactive oxygen species levels damage DNA, inducing both cancer cell apoptosis and cycle arrest. Importantly, the results of the toxicity studies showed that compounds 23 and 31 possessed good oral safety profiles. In xenograft models, compound 23 exhibited remarkable antitumor potency, which was superior to the clinical Top inhibitors irinotecan and etoposide. Overall, this work highlights the therapeutic potential and safety profile of compound 23 as a Top1/2 dual inhibitor in tumor therapy and provides valuable lead compounds for further development of Top inhibitors.

Evaluation of cytotoxic effects of several novel tetralin derivatives against Hela, MDA-MB-468, and MCF-7 cancer cells

Background:

The inhibitors of the enzymes estrone sulfatase and 17-β-hydroxysteroid dehydrogenase (17-β-HSD) could provide a means of blocking estrogen biosynthesis leading to regression of estrogen-dependent tumors. We evaluated the cytotoxicity of several tetralin derivatives, 2-(4-halo-phenylmethylene)-3,4-dihydronaphthalene-1-ones, as potential inhibitors of these two enzymes, on Hela, MDA-MB-468, and MCF-7 cancer cell lines.

Materials and Methods:

The cell lines were cultured in RPMI medium and the cytotoxic effect of tested compounds (compounds 1 to 5) was screened at the concentrations of 0.1, 1, and 10 μM either alone or in combination with doxorubicin (100 μM), using MTT assay. The mixtures of cell suspension with solvent (1% DMSO in PBS) and doxorubicin (100 μM) were used as negative and positive controls, respectively. Each concentration of compounds was assayed in four wells and repeated in at least three independent experiments for each cell line. The cytotoxic effect of each particular concentration of tested compounds was expressed as the percent of cell survival.

Results:

None of the compounds exhibited cytotoxic effect (reduction of cell survival to less than 50%) on tested cell lines. However, statistically significant reduction in cell survival was observed for some compounds against particular cell lines. Among all tested combinations of compounds with doxorubicin against cell lines, only compound 4 at 10 μM concentration showed synergistic cytotoxic effect with doxorubicin against Hela cells.

Conclusion:

With the exception of compound 2, other tested compounds have potential for further cytotoxicity evaluation. Synthesizing other tetralin derivatives similar to compound 4 and studying their structure-activity relationships (SARs) would be encouraged.

Design and synthesis of novel amino-substituted xanthenones and benzo[b]xanthenones: Evaluation of their antiproliferative activity and their ability to overcome multidrug resistance toward MES-SA/D×5 cells

A number of new xanthenone and benzo[b]xanthenone amino derivatives and their pyrazole-fused counterparts have been designed and synthesized possessing structural analogy to the potent anticancer agent 9-methoxypyrazoloacridine. The synthesis of the compounds proceeds through nucleophilic substitution of 1-chloro-4-nitroxanthenone or the corresponding benzo[b]xanthenone by the appropriately substituted amine or hydrazine, reduction of the nitro group, and conversion into the suitable dialkylaminoacetamides. This method cannot be applied for synthesis of the pyrazole-fused benzo[b]xanthenones, consequently a different, simple, and high-yielding synthetic procedure was developed for the preparation of the target molecules. In vitro cytotoxic potencies of the new derivatives toward the murine leukemia L1210 cell line, human colorectal adenocarcinoma (HT-29), and human uterine sarcoma (MES-SA and its 100-fold resistant to doxorubicin variant MES-SA/D x 5) cell lines are described and compared to those of reference drugs. The compounds exhibited significant cytotoxic activity against the tested cell lines and in addition they retain activity against the multidrug resistant MES-SA/D x 5 subline, showing resistant factors close to 1. A number of derivatives were found to possess DNA binding capacity, according to a standard ethidium bromide displacement assay. The majority of the studied compounds induce a G2/M arrest, although among them some G1 or S blockers have also been identified.

Design, synthesis, and antiproliferative activity of some novel aminosubstituted xanthenones, able to overcome multidrug resistance toward MES-SA/Dx5 cells

A series of novel xanthenone aminoderivatives and their pyrazole-fused counterparts possessing structural analogy to the potent anticancer agent 9-methoxypyrazoloacridine (PZA) reported. These compounds exhibited an interesting cytotoxic activity against a panel of cell lines. Most noticeably, they retain activity against the multidrug resistant MES-SA/Dx5 subline, showing resistant factors close to 1.