Ovatodiolide inhibits the oncogenicity and cancer stem cell-like phenotype of glioblastoma cells, as well as potentiate the anticancer effect of temozolomide.

Affiliation

Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Neurology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Division of Neurosurgery, Department of Surgery, Shuang Ho Hospital, Taipei Medical University, New Taipei City 23561, Taiwan; Taipei Neuroscience Institute, Taipei Medical University, Taipei, Taiwan; Department of Medical Research & Education, Taipei Medical University-Shuang Ho Hospital, New Taipei City 23561, Taiwan. Electronic address: [Email]

Abstract

BACKGROUND : Ovatodiolide (Ova), a major bioactive diterpenoid isolate of Anisomeles indica has drawn considerable attention lately as an effective anticancer agent with several published works demonstrating its tumor-inhibitory activity in various cancer types.
OBJECTIVE : In this study, we examined the modulatory effect of Ova on the oncogenicity, proliferation, and cancer stem cell-like traits of glioblastoma (GBM) cells, as well as investigated the underlying molecular mechanism for the anticancer activity of Ova in GBM cell lines, U-87MG and GBM8401.
METHODS : The antiproliferative, apoptotic, and stemness-attenuating effects of Ova were evaluated using the sulforhodamine B (SRB) colorimetric assay, western blot and fluorescent immunocytochemistry. Cell apoptosis was analyzed based on variation in the expression levels of Bcl-2 family of regulator proteins Bax, Bak, Bcl-2 and Bcl-xL.
RESULTS : Ova induced the apoptosis of the U-87MG and GBM8401 cells, as well as effectively inhibited the proliferation and motility of the GBM cell lines in a dose- and time-dependent manner. Ova-induced apoptosis correlated with increased Bax/Bcl-2 ratio, while inhibition of tumor cell migration and colony formation was associated with reduced Slug, Vimentin, NCadherin and β-catenin protein expression and increased E-Cadherin. In addition, exposure to Ova inhibited tumorsphere formation, elicited downregulation of CD44, CD133, Sox2, and Oct4, as well as correlated with dysregulation of the JAK2-STAT3 signaling pathway. Furthermore, we showed for the first time to the best of our knowledge that Ova potentiate the chemotherapeutic effect of Temozolomide.
CONCLUSIONS : Taken together, our findings demonstrate the anticancer potential of Ova in GBM and its efficacy in the treatment of GBM as monotherapy and in combination with Temozolomide.

Keywords

Chemoresistance,Chemotherapy,Glioma stem cells,Temozolomide,Tumorsphere,