title: Nelfinavir targets multiple drug resistance mechanisms to increase the efficacy of doxorubicin in MCF-7/Dox breast cancer cells.
abstract: Development of multidrug resistance (MDR) remains a significant problem in cancer chemotherapy and underscores the importance of using chemosensitizers. Well known MDR mechanisms include: (i) upregulation of drug-efflux; (ii) increased signaling via AKT; and (iii) decreased apoptosis. Therefore, chemosensitizers should target multiple resistance mechanisms. We investigated the efficacy of nelfinavir (NFV), a clinically approved anti-HIV drug, in increasing doxorubicin (DOX) toxicity in a MDR breast cancer cell line, MCF-7/Dox. As compared to parental MCF-7 cells, the MCF-7/Dox were 15-20 fold more resistant to DOX-induced cytotoxicity at 48 h post-exposure (DOX IC50 = 1.8 μM vs. 32.4 μM). Coexposures to NFV could significantly (p < 0.05) decrease DOX-IC50 in MCF-7/Dox cells. Multiple exposures to physiologic concentrations of NFV (2.25 μM or 6.75 μM) decreased DOX-IC50 by 21-fold and 50-fold, respectively. Interestingly, although single exposure to NFV transiently induced P-glycoprotein (P-gp) levels, multiple treatments with NFV inhibited both P-gp expression and efflux function, which increased intracellular DOX concentrations. Single exposure to NFV augmented the markers of cell-survival (AKT) and autophagy (LC3-II), whereas multiple exposures enabled suppression of both total AKT (t-AKT) and insulin like growth factor-1 (IGF-1)-induced phosphorylated AKT (p-AKT) levels. Multiple exposures to NFV also resulted in increased unfolded protein response (UPR) transducers, e.g. Grp78, p-PERK, p-eIF2α, and ATF-4; and endoplasmic reticulum (ER) stress induced death sensors, e.g. CHOP & TRIB-3. Multiple exposures to NFV also abrogated the mitogenic effects of IGF-1. In mice carrying MCF-7/Dox tumor xenografts, intraperitoneal (i.p.) injection of NFV (20 mg/kg/day) and DOX (2 mg/kg/twice/wk) decreased tumor growth more significantly (p < 0.01) than either agent alone. Immunohistochemical (IHC) analysis revealed decreased p-AKT and Ki-67 levels. Thus, NFV overcomes MDR in breast cancer cells and should be tested as an adjunct to chemotherapy.
authors: Department of Pharmacology, Tulane University Medical Center, USA.
authors: Geetika
authors: G
authors: Chakravarty
authors: Department of Pharmacology, Tulane University Medical Center, USA.
authors: Aditi
authors: A
authors: Mathur
authors: Department of Pharmacology, Tulane University Medical Center, USA.
authors: Pallavi
authors: P
authors: Mallade
authors: Department of Pharmacology, Tulane University Medical Center, USA.
authors: Samantha
authors: S
authors: Gerlach
authors: Department of Pharmacology, Tulane University Medical Center, USA.
authors: Joniece
authors: J
authors: Willis
authors: Department of Urology, Tulane University Medical Center, USA.
authors: Amrita
authors: A
authors: Datta
authors: Department of Biostatistics, Tulane University School of Public Health and Tropical Medicine, USA.
authors: Sudesh
authors: S
authors: Srivastav
authors: Department of Urology, Tulane University Medical Center, USA.
authors: Asim B
authors: AB
authors: Abdel-Mageed
authors: Department of Pharmacology, Tulane University Medical Center, USA. Electronic address: dmondal@tulane.edu.
authors: Debasis
authors: D
authors: Mondal
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D019888:Nelfinavir / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; D004317:Doxorubicin; D019888:Nelfinavir
keywords: Breast cancer; Chemosensitization; Doxorubicin; MDR; Nelfinavir; Tumor xenograft