Scutellaria litwinowii Induces Apoptosis Through Both Extrinsic and Intrinsic Apoptotic Pathways in Human Promyelocytic Leukemia Cells

Abstract

Scutellaria is a genus of Lamiaceae with known antiproliferative potentials. Scutellaria litwinowii Bornm. & Sint. ex Bornm. is one of the Iranian species of Scutellaria. Although there are widespread reports about the cytotoxic and antitumor effects of some species of this genus, research on the molecular mechanism responsible for the anticancer effects of S. litwinowii has not yet been conducted. In the current study, the apoptotic effects of S. litwinowii on 2 myeloid cell lines, apoptosis-proficient HL60 cells and apoptosis-resistant K562 cells, were analyzed. An increase in the activity of caspases-3, -8, and -9, poly (ADP ribose) polymerase (PARP) cleavage, detection of phosphatidylserine on the outer layer of cell membrane and sub-G1 peak in the flow cytometry histogram of treated cells, suggested the induction of apoptosis. S. litwinowii also increased the Bax/Bcl-2 ratio. It could be concluded that S. litwinowii induced apoptosis in both apoptosis-proficient and apoptosis-resistant leukemic cells and it might be considered as a novel candidate in the treatment of hematological malignancies.

ACKNOWLEDGMENTS

We would like to thank Dr. H. Nasirli for her assistance in flow cytometry. We are also grateful for the editorial assistance of Dr. N. Tayarani-Najaran. Our sincere thanks to Mr. O. Felthaus for reading the manuscript and offering valuable suggestions. This work was supported by grants (No. 87553) for the Pharmacy doctorate Program from Research Affairs of Mashhad University of Medical Sciences.