Withanolides are potent novel targeted therapeutic agents against adrenocortical carcinomas.
BACKGROUND
Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with poor prognosis, as a majority of patients present with advanced disease. Current adjuvant strategies for metastatic patients include mitotane or other cytotoxic agents and carry a significant morbidity as well as a low (<10 %) 5-year survival. Withanolides, including withaferin A, are novel chemotherapeutic agents with potent targeted effects in medullary thyroid cancer and a number of solid malignancies with low toxicity in vivo. We hypothesize that novel naturally derived withanolides will have potent targeted anti-cancer activity against ACCs.


METHODS
In vitro cell viability of ACC cell lines (Y1 and SW13) was measured using MTS cell proliferation assay. Cell cycle and apoptotic analysis studied using annexin V/propidium iodide staining on flow cytometry (FC) and targeted molecular mechanisms of withanolide cytotoxicity were assessed using standard Western blot analysis.


RESULTS
All the withanolides potently reduced ACC cell viability on MTS assay with 7- to 185-fold higher selectivity than normal fibroblasts. Cell cycle analysis demonstrated a shift in cell cycle arrest from G1/G0 to G2/M with induction of apoptosis at nanomolar concentrations of withanolides. Unlike current ACC therapeutics, withanolides modulated expression of several key oncogenic pathway proteins in ACCs by Western blot, including Jagged 1, MAPK, and Akt/mTOR pathway proteins in a dose-dependent manner after 24 h drug treatment of SW13 cells.


CONCLUSIONS
These results demonstrate the first evidence of the anticancer efficacy of withanolides in ACC cells and provide support for future translational evaluation of these compounds as novel therapeutic agents for ACC patients.
Division of Endocrine Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
Chitra
C
Subramanian
Huaping
H
Zhang
Robert
R
Gallagher
Gary
G
Hammer
Barbara
B
Timmermann
Mark
M
Cohen
D000310:Adrenal Gland Neoplasms / Q000188:drug therapy / Q000601:surgery; D018268:Adrenocortical Carcinoma / Q000188:drug therapy / Q000601:surgery; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects*; D016503:Drug Delivery Systems / Q000379:methods*; D006801:Humans; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured / Q000187:drug effects; D054358:Withanolides / Q000494:pharmacology*
D054358:Withanolides; C009684:withaferin A