title: Pinus radiata bark extract induces caspase-independent apoptosis-like cell death in MCF-7 human breast cancer cells.
abstract: In the present study, we investigated the anticancer activity of Pinus radiata bark extract (PRE) against MCF-7 human breast cancer cells. First, we observed that PRE induces potent cytotoxic effects in MCF-7 cells. The cell death had features of cytoplasmic vacuolation, plasma membrane permeabilization, chromatin condensation, phosphatidylserine externalization, absence of executioner caspase activation, insensitivity to z-VAD-fmk (caspase inhibitor), increased accumulation of autophagic markers, and lysosomal membrane permeabilization (LMP). Both the inhibition of early stage autophagy flux and lysosomal cathepsins did not improve cell viability. The antioxidant, n-acetylcysteine, and the iron chelator, deferoxamine, failed to restore the lysosomal integrity indicating that PRE-induced LMP is independent of oxidative stress. This was corroborated with the absence of enhanced ROS production in PRE-treated cells. Chelation of both intracellular calcium and zinc promotes PRE-induced LMP. Geranylgeranylacetone, an inducer of Hsp70 expression, also had no significant protective effect on PRE-induced LMP. Moreover, we found that PRE induces endoplasmic reticulum (ER) stress and mitochondrial membrane depolarization in MCF-7 cells. The ER stress inhibitor, 4-PBA, did not restore the mitochondrial membrane integrity, whereas cathepsin inhibitors demonstrated significant protective effects. Collectively, our results suggest that PRE induces an autophagic block, LMP, ER stress, and mitochondrial dysfunction in MCF-7 cells. However, further studies are clearly warranted to explore the exact mechanism behind the anticancer activity of PRE in MCF-7 human breast cancer cells.
authors.affiliation: Department of Forest Products and Biotechnology, College of Forest Science, Kookmin University, 861-1 Chongnung-dong, Songbuk-gu, Seoul, 136-702, South Korea.
authors.forename: Thamizhiniyan
authors.initials: T
authors.lastname: Venkatesan
authors.affiliation: Department of Forest Products and Biotechnology, College of Forest Science, Kookmin University, 861-1 Chongnung-dong, Songbuk-gu, Seoul, 136-702, South Korea.
authors.forename: Young-Woong
authors.initials: YW
authors.lastname: Choi
authors.affiliation: Department of Wood Science and Technology, College of Agriculture and Life Science, Chonbuk National University, Jeonju, 561-756, South Korea.
authors.forename: Sung-Phil
authors.initials: SP
authors.lastname: Mun
authors.affiliation: Department of Forest Products and Biotechnology, College of Forest Science, Kookmin University, 861-1 Chongnung-dong, Songbuk-gu, Seoul, 136-702, South Korea. ykkim@kookmin.ac.kr.
authors.forename: Young-Kyoon
authors.initials: YK
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D006801:Humans; D008247:Lysosomes / Q000187:drug effects; D061986:MCF-7 Cells; D008928:Mitochondria / Q000187:drug effects; D018384:Oxidative Stress; D028223:Pinus / Q000737:chemistry*; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D010936:Plant Extracts; D017382:Reactive Oxygen Species; D020169:Caspases
keywords: Anticancer source; Autophagic inhibitor; Breast cancer; Lysosomal membrane permeabilization; Pinus radiata; Polyphenols