title: Differential behaviors of trastuzumab-sensitive and -resistant SKBR3 cells treated with menadione reveal the involvement of Notch1/Akt/FOXO1 signaling elements.
abstract: Given that HER2 serves as a putative target for therapy in HER2-positive breast cancer, intrinsic and/or acquired resistance to trastuzumab (T) has been proposed to be the major obstacle in treatments. In addition, chemoresistance is commonly attributed to increased antioxidant capacity. In that regard, we evaluated the effect of menadione (M) alone and/or its combination with trastuzumab on proliferation, intracellular GSH and ROS contents as well as HER2 and Notch1 signaling pathways in both trastuzumab-resistant (SKBR3(R)) and -sensitive SKBR3 (SKBR3(S)) cells. In spite of increased level of ROS and reduced level of GSH in M-treated SKBR3(S) cells, M-treated SKBR3(R) cells showed a decreased content of ROS and GSH compared to untreated cells. However, M/T co-treatment of SKBR3 cells indicated no effect on ROS content, while decreased the level of GSH compared to untreated control cells. Based on the extent of apoptosis, colony formation and wound healing assays, M alone, and/or in combination with T had a stronger inhibitory effect on proliferation of SKBR3(R) cells relative to SKBR3(S) cells. These effects might be due to the stronger effects of M and/or M/T on downregulation of p-Akt, Hes1, NICD, and upregulation of FOXO1 among SKBR3(R) cells relative to the sensitive SKBR3 cells. These findings would certainly shed light on some of the signaling factors involved in induction of trastuzumab resistance and would be of value in designing more efficient chemosensitization strategies.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran.
authors.forename: Soraya
authors.initials: S
authors.lastname: Sajadimajd
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran. ryazdan@ut.ac.ir.
authors.forename: Razieh
authors.initials: R
authors.lastname: Yazdanparast
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D051881:Receptor, Notch1 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D000068878:Trastuzumab / Q000494:pharmacology*; D024483:Vitamin K 3 / Q000494:pharmacology*
chemical_list: C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C497761:NOTCH1 protein, human; D017382:Reactive Oxygen Species; D051881:Receptor, Notch1; D024483:Vitamin K 3; D051057:Proto-Oncogene Proteins c-akt; D000068878:Trastuzumab
keywords: HER2; Menadione; Notch1; Oxidative stress; SKBR3 cells; Trastuzumab