Design and synthesis of new bioisosteres of spirooxindoles (MI-63/219) as anti-breast cancer agents.

We report herein the design and synthesis of bioisosteres of spirooxindole (MI-63/219), a small-molecule inhibitors of the MDM2-p53 interaction as anti-breast cancer agents. Compound 5b has been exhibiting significant anti-proliferative activity in nude mice bearing MCF-7 xenograft tumor. The compound 5b was found to act via modulation of MDM2 and p53 expression in breast cancer cells expressing wild type p53. Compound 5b stimulated p53 activation, caused modulation of downstream effectors p21, pRb, and cyclin D1 which regulate cell cycle. Thus, compound triggered G1-S phase cell cycle arrest, which was evident by flow cytometric analysis of treated breast cancer cells. Thus, compound 5b restores the p53 function, which triggers molecular events consistent with cell cycle arrest at G1/S phase.

Designed modulation of sex steroid signaling inhibits telomerase activity and proliferation of human prostate cancer cells.

The predominant estrogen-receptor (ER)-ß signaling in normal prostate is countered by increased ER-α signaling in prostate cancer (CaP), which in association with androgen-receptor (AR) signaling results in pathogenesis of the disease. However CaP treatments mostly target AR signaling which is initially effective but eventually leads to androgen resistance, hence simultaneous targeting of ERs has been proposed. A novel series of molecules were designed with multiple sex-steroid receptor modulating capabilities by coalescing the pharmacophores of known anti-CaP molecules that act via modulation of ER(α/ß) and/or AR, viz. 3,3'diindolylmethane (DIM), mifepristone, toremifene, tamoxifen and raloxifene. N,N-diethyl-4-((2-(4-methoxyphenyl)-1H-indol-3-yl)methyl) aniline (DIMA) was identified as the most promising structure of this new series. DIMA increased annexin-V labelling, cell-cycle arrest and caspase-3 activity, and decreased expression of AR and prostate specific antigen in LNCaP cells, in vitro. Concurrently, DIMA increased ER-ß, p21 and p27 protein levels in LNCaP cells and exhibited ~5 times more selective binding for ER-ß than ER-α, in comparison to raloxifene. DIMA exhibited a dose-dependent ER-ß agonism and ER-α antagonism in classical gene reporter assay and decreased hTERT (catalytic subunit of telomerase) transcript levels in LNCaP at 3.0 µM (P<0.05). DIMA also dose-dependently decreased telomerase enzyme activity in prostate cancer cells. It is thus concluded that DIMA acts as a multi-steroid receptor modulator and effectively inhibits proliferation of prostate cancer cells through ER-ß mediated telomerase inhibition, by countering actions of ER-α and AR. Its unique molecular design can serve as a lead structure for generation of potent agents against endocrine malignancies like the CaP.