Abstract #LB-51: HQO-0601, an amide-containing 3, 4-dihydroquinolinone derivative, against human hematologic malignancies through inhibition of mammalian target of rapamycin signaling pathway

Recently, the hydroxycoumarine skeleton of flavonols has been demonstrated to have a variety of biological activities including antioxidant properties and the ability to induce apoptosis. As a result, they have become the focus of intense studies aimed at developing novel compounds with pharmacological applications. Accordingly, we are interested in designing and synthesizing a series of amide-containing 3, 4-didhydroquinolinones (HQO) derivatives as novel hydroxycoumarine analogues and to evaluate their anti-cancer activities for further drug development. Of over sixty derivatives we tested, several amide substitute compounds showed excellent antiproliferative activity towards human nasopharyngeal carcinoma (NPC-TW01), lung carcinoma (H661), and leukemia (Jurkat) cells. Among them, HQO-0601 possesses great potency towards Jurkat cells with an IC₅₀ of around 200 nM compared to the micromolar range of HQO-0601 needed for NPC-TW01 and H661 cells. In order to distinguish whether the antiproliferative effect of HQO-0601 is cell-line specific or tissue-specific, several human leukemia, solid tumors cells and peripheral blood mononuclear cells (PBMCs) were evaluated. Our results showed that leukemia cell lines are more sensitive to HQO-0601 treatment than solid tumor cell lines. Further examination also showed that HQO-0601 is not cytotoxic to PBMCs even at 50 \#956;M of HQO-0601, the highest concentration used. Further results indicated that HQO-0601 induces growth retardation at S-phase was accompanied by a marked decrease in the level of phosphorylation of CDK2 without affecting the CDK2 and cyclin A protein expression. Moreover, HQO-0601 treatment significantly alters the phosphorylation status of AKT and the mTOR effectors p70 S6 kinase. Taken together, our results strongly indicated that the HQO-0601 induced cell arrest of leukemia might involve in interrupting of the AKT/mTOR signaling pathway and merits further detailed studies.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr LB-51.