Effects of Doxorubicin, Cisplatin, and Tamoxifen on the Metabolic Profile of Human Breast Cancer MCF‑7 Cells As Determined by 1 H High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance Roberta M. Maria, † Wanessa F. Altei, ‡ Heloisa S. Selistre-de-Araujo, ‡ and Luiz A. Colnago* ,† † Embrapa Instrumentaç ã o, Rua XV de Novembro, 1452, Sã o Carlos, SP 13560-970, Brazil ‡ Laborató rio de Bioquímica e Biologia Molecular, Departamento de Ciê ncias Fisioló gicas, Universidade Federal de Sã o Carlos (UFSCar), Rodovia Washington Luís, km 235, Caixa Postal 676, Sã o Carlos, SP 13565-905, Brazil * S Supporting Information ABSTRACT: Doxorubicin (Doxo), cisplatin (Cis), and tamoxifen (Tamo) are part of many chemotherapeutic regimens. However, there have been limited studies of the way metabolism in breast cancer is affected by chemotherapy. We studied, through 1 H high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy, the metabolic profile of human breast cancer MCF-7 control (Con) cells as well as MCF-7 cells treated with Tamo, Cis, and Doxo. 1 H HR-MAS NMR single-pulse spectra evidenced signals from the cell compounds, including fatty acids (membranes), water- soluble proteins, and metabolites. The spectra showed that phosphocholine (i.e., biomarker of breast cancer malignant transformation) signals were stronger in Con than in treated cells. Betaine (i.e., the major osmolyte in cells) was observed at similar concentrations in MCF-7 control and treated cells but was absent in nontumor MCF-10A cells. The NMR spectra acquired with the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence were used only in qualitative analyses because the signal areas were attenuated according to their transverse relaxation time (T 2 ). The CPMG method was used to identify soluble metabolites such as organic acids, amino acids, choline and its derivatives, taurine, and guanidino acetate. 1 H HR-MAS NMR spectroscopy efficiently demonstrated the effects of Tamo, Cis, and Doxo on the metabolic profile of MCF-7 cells. The fatty acid, phosphocholine, and choline variations observed by single-pulse HR-MAS NMR have the potential to characterize both responder and nonresponder tumors at a molecular level. C hemotherapy has improved relapse-free and overall survival times in women with locally advanced breast cancer. 1 Doxorubicin, cisplatin, and tamoxifen are among the frequently used drugs in cancer chemotherapy. Doxorubicin corresponds to a class of compounds featuring similar structures, the so-called anthracyclines. 2 The cytostatic effect of this drug may involve several mechanisms, such as inhibition of both topoisomerase II and RNA polymerase II. 3 The formation of reactive oxygen species (ROS), intercalation of doxorubicin into chromosomal DNA, and generation of complexes with iron have also been attributed to the doxorubicin cytostatic mechanism. 3 Doxorubicin is considered one of the most efficient approaches for the treatment of breast cancer, even though its resistance has led to an unsuccessful outcome in many patients. 4 Cisplatin is another compound used in cancer chemotherapy. It frequently promotes a prompt satisfying response. 5 Cisplatin consists of an inorganic platinum complex that inhibits DNA synthesis. However, the resistance of tumor cells to cisplatin has been a fundamental problem in tumor management, being responsible for the collapse of metastatic cancer treatment. 6 Likewise, cisplatin cytotoxicity to regular tissues as well as the resistance of cancer cells to this compound impairs the therapeutic response. 7,6 Tamoxifen is a nonsteroidal antiestrogen that was first approved by the U.S. Food and Drug Administration (FDA) in 1977 for metastatic breast cancer treatment. 8,9 This chemo- therapeutic compound has also been used to reduce the recurrence of primary breast cancer and contributes to survival rates as an adjuvant treatment. 9,8 Tumor biomarkers have been used to establish the disease stage and the efficacy of different drugs and doses. 10 Biomarkers can also be used to discriminate between “responders” and “non-responders”. 10 In the past decade, metabolomic bio- markers have been combined with radiological, genomic, and proteomic ones to establish the tumor stage. Metabolomics, which stands for the overall assessment of endogenous metabolites within a biological system, 10 has become more frequently used to study the effects of anticancer drugs on tumor cells. 4 Received: January 10, 2017 Revised: March 29, 2017 Published: April 5, 2017 Article pubs.acs.org/biochemistry © 2017 American Chemical Society 2219 DOI: 10.1021/acs.biochem.7b00015 Biochemistry 2017, 56, 2219-2224