Hongxia Fan

Guaianolide Sesquiterpene Lactones, a Source To Discover Agents That Selectively Inhibit Acute Myelogenous Leukemia Stem and Progenitor Cells

Small molecules that can selectively target cancer stem cells (CSCs) remain rare currently and exhibit no common structural features. Here we report a series of guaianolide sesquiterpene lactones (GSLs) and their derivatives that can selectively eradicate acute myelogenous leukemia (AML) stem or progenitor cells. Natural GSL compounds arglabin, an anticancer clinical drug, and micheliolide (MCL), are able to reduce the proportion of AML stem cells (CD34⁺CD38⁻) in primary AML cells. Targeting of AML stem cells is further confirmed by a sharp reduction of colony-forming units of primary AML cells upon MCL treatment. Moreover, DMAMCL, the dimethylamino Michael adduct of MCL, slowly releases MCL in plasma and in vivo and demonstrates remarkable therapeutic efficacy in the nonobese diabetic/severe combined immunodeficiency AML models. These findings indicate that GSL is an ample source for chemical agents against AML stem or progenitor cells and that GSL is potentially highly useful to explore anti-CSC approaches.

Micheliolide Derivative DMAMCL Inhibits Glioma Cell Growth In Vitro and In Vivo

Background There is no highly effective chemotherapy for malignant gliomas to date. We found that dimethylaminomicheliolide (DMAMCL), a selective inhibitor of acute myeloid leukemia (AML) stem/progenitor cells, inhibited the growth of glioma cells. Methods The distribution of DMAMCL in brain was analyzed by an ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS) system. The anti-tumor evaluations of DMAMCL in vitro were performed by MTT, FACS and RT-PCR. In vivo, the mixture of C6 cells and matrigel was injected into caudatum, and the anti-tumor activity of DMAMCL was evaluated by tumor growth and rat survival. The toxicity of DMAMCL was evaluated by body weight, daily food intake, hematological or serum biochemical analyses, and histological appearance of tissues. Results The IC50 values of DMAMCL against the C6 and U-87MG cell lines in vitro were 27.18 ± 1.89 μM and 20.58 ± 1.61 μM, respectively. DAMMCL down-regulated the anti-apoptosis gene Bcl-2 and increased apoptosis in C6 and U-87MG cells in a dose-dependent manner. In a C6 rat tumor model, daily administration of DMAMCL for 21 days reduced the burden of C6 tumors by 60% to 88% compared to controls, and more than doubled the mean lifespan of tumor-bearing rats. Distribution analysis showed that the DMAMCL concentration was higher in the brain than in plasma. Evaluations for toxicity revealed that oral administration of DMAMCL at 200 or 300 mg/kg once a day for 21 days did not result in toxicity. Conclusions These results suggest that DMAMCL is highly promising for the treatment of glioma.

Abstract 3350: Inhibition of breast cancer and cancer stem cells via a novel micheliolide analogue CY-9

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Natural products that target cancer stem cells (CSCs) have the potential to treat cancers and reduce the occurrence of relapse. The sesquiterpene lactone parthenolide has received much attention for its ability to preferentially target CSCs over their normal equivalents. However, poor pharmacokinetics have severely limited the clinical use of parthenolide, and prompted synthesis of a water soluble analogue, LC-1. Although currently in Phase I trials for disseminated cancers, LC-1 suffers from a short half-life, which could potentially limit its efficacy. In order to identify new sesquiterpene lactones which function similarly to parthenolide and LC-1 but with improved pharmacokinetics, we tested a new micheliolide analogue CY-9 for activity against both breast cancer and CSCs. Using the MTS assay, SUM159 breast cancer cells displayed sensitivity to CY-9 with an IC50 of 5 μM, which is similar to reported inhibitory concentrations of parthenolide. SUM159 cells assayed for Aldefluor expression after a three day treatment with CY-9 (1, 2.5, 5 μM) showed a 27%, 64%, and 83% reduction in their CSC populations, respectively. This CSC depletion was largely reversed in SUM159 cells that were pre-treated with the antioxidant N-Acetyl-Cysteine (NAC) before exposure to CY-9. Inhibition of SUM159 CSC self-renewal after CY-9 treatment was assayed using tumorsphere formation of single SUM159 Aldefluor-positive cells. A seven day treatment of 5 μM CY-9 reduced SUM159 Aldefluor-positive cell tumorsphere formation by 74%. Under drug-free conditions, tumorsphere formation was reduced by 26% in the second passage, but returned to control levels by the third passage. Western blotting also showed that 5 μM CY-9 reduced the levels of nuclear NF-κB. These results demonstrate the effectiveness of our new micheliolide analogue CY-9 at targeting populations of both bulk breast tumor cells and CSCs. The slight reduction in tumorsphere formation under drug-free conditions suggests that inhibition of self-renewal plays a minor role in CY-9s activity against CSCs. Loss of CY-9 activity with cells pre-treated with NAC suggests that the inhibitory effect of CY-9 is partially mediated by its interaction with biologically relevant cysteines and/or ROS generation. Additionally, as NF-κB is vital for defense against cellular stressors such as ROS, depletion of nuclear NF-κB might also explain the observed inhibition with CY-9. Together, these results warrant further study of CY-9 as a potential therapy for breast cancer and CSCs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3350. doi:10.1158/1538-7445.AM2011-3350