Andro is a diterpenoid lactone isolated from Andrographis paniculata, an important herbal medicine used in Asia to treat a range of diseases, (respiratory infection, fever, diarrhea). Andro is the major bioactive component extracted from Andrographis paniculata. The three hydroxyls at C-3, C-19 and C-14 are responsible for its biological activities. Recently, the anti-cancer properties of Andro have been recognized, and we found that Andro results in mitochondrial-mediated apoptosis in lymphoma cell lines and fresh malignant cells from patients with lymphoma. Based on the mechanism of action of this novel diterepenoid lactone and a prior report (Manikam et al Journal of Pharmacy and Pharmacol 2009, 61:69), we hypothesized that Andro may have activity in APL. The cell differentiation inducing agent all-trans retinoic acid (ATRA) combined with chemotherapy has become standard first-line treatment for APL through a mechanism that involves cell differentiation, but recent data suggest that ATRA alone or ATRA and arsenic trioxide, which induces apoptosis by degradation of the chimeric fusion protein PML-RARα, may replace ATRA/chemotherapy as initial treatment. Because Andro appears to work through a different mechanism than ATRA, we utilized ATRA-sensitive NB4, ATRA-resistant NB4 (NB4-007/6 and NB4-306) cell lines to test the in-vitro anti-leukemia effect of Andro on APL cells by measuring cell viability (MTT assay), apoptosis (Annexin V-FITC/PI, FACS), mitochondrial membrane potential (MMP) (TMRE/ FACS), cell differentiation (CD11B staining/FACS) and signaling pathways (Western blot). We found that Andro reduced APL cell viability, MMP and increased apoptosis in a time & dose-dependent manner. Moreover ATRA-resistant NB4-007/6 or NB4-306 cell lines were more sensitive to Andro compared with the ATRA-sensitive NB4 cell line. We found that the mechanism of Andro activity is not related to cell differentiation as measured by CD11b. In order to interrogate signaling pathways involved, we studied p27kip1 and FasL expression and found that Andro resulted in up-regulation of both. One of the forkhead box O (FOXO) proteins, FOXO1, a transcription factor, also demonstrated increased phosphorylation at Thr24 at 1h, 3h, and 24h Andro, but reduced phosphorylation at Thr24 at 6h and 16h. Taken together, these data suggest that Andro may have activity in patients with ATRA-resistant APL by a mechanism of action that is distinct from ATRA. Thus, further studies of diterpenoid lactones in APL are warranted.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 717.

©2010 American Association for Cancer Research
2010