Wanessa F. Altei

Characterization of metabolic profile of intact non-tumor and tumor breast cells by high-resolution magic angle spinning nuclear magnetic resonance spectroscopy

(1)H high-resolution magic angle spinning nuclear magnetic resonance ((1)H HR-MAS NMR) spectroscopy was used to analyze the metabolic profile of an intact non-tumor breast cell line (MCF-10A) and intact breast tumor cell lines (MCF-7 and MDA-MB-231). In the spectra of MCF-10A cells, six metabolites were assigned, with glucose and ethanol in higher concentrations. Fifteen metabolites were assigned in MCF-7 and MDA-MB-231 (1)H HR-MAS NMR spectra. They did not show glucose and ethanol, and the major component in both tumor cells was phosphocholine (higher in MDA-MB-231 than in MCF-7), which can be considered as a tumor biomarker of breast cancer malignant transformation. These tumor cells also show acetone signal that was higher in MDA-MB-231 cells than in MCF-7 cells. The high acetone level may be an indication of high demand for energy in MDA-MB-231 to maintain cell proliferation. The higher acetone and phosphocholine levels in MDA-MB-231 cells indicate the higher malignance of the cell line. Therefore, HR-MAS is a rapid reproducible method to study the metabolic profile of intact breast cells, with minimal sample preparation and contamination, which are critical in the analyses of slow-growth cells.

Jatrophidin I, a cyclic peptide from Brazilian Jatropha curcas L.: Isolation, characterization, conformational studies and biological activity

A cyclic peptide, jatrophidin I, was isolated from the latex of Jatropha curcas L. Its structure was elucidated by extensive 2D NMR spectroscopic analysis, with additional conformational studies performed using Molecular Dynamics/Simulated Annealing (MD/SA). Jatrophidin I had moderate protease inhibition activity when compared with pepstatin A; however, the peptide was inactive in antimalarial, cytotoxic and antioxidant assays.

Synthetic Analogue of the Natural Product Piperlongumine as a Potent Inhibitor of Breast Cancer Cell Line Migration

Piperlongumine is a natural amide alkaloid isolated from several species of Piper and is described in the literature as selectively cytotoxic to several cancer cell lines. Inhibiting cell migration has gained considerable interest as an approach for discovering antimetastatic agents because this process is fundamental to metastasis. Piperlongumine, selected from cell-based assay screening of NuBBE Database, inhibited the migration of MDA-MB-231 breast cancer cells with an EC50 of 3.0 ± 1.0 µM by the Boyden chamber assay. A series of five analogous compounds based on the structure of piperlongumine were designed, synthesized and evaluated in cell migration and cytotoxicity assays. The analogue designed by molecular simplification ((E)-N-acryloyl-3-(3,4,5-trimethoxyphenyl)acrylamide) was the most active of the series, with an EC50 of 1.5 ± 1 µM. Additionally, this compound was selectively cytotoxic, with a selectivity index (SI) of 4.4.

Effects of Doxorubicin, Cisplatin, and Tamoxifen on the Metabolic Profile of Human Breast Cancer MCF-7 Cells As Determined by 1H High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance

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 1H 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. 1H 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 (T2). The CPMG method was used to identify soluble metabolites such as organic acids, amino acids, choline and its derivatives, taurine, and guanidino acetate. 1H 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.

Effect of cis-9, trans-11 Conjugated Linoleic Acid (CLA) on the Metabolism Profile of Breast Cancer Cells Determined by 1 H HR-MAS NMR Spectroscopy

Conjugated linoleic acid (CLA), a fatty acid found in ruminant food products, has been associated with anticarcinogenic activity. However, its effect on cancer metabolism is unclear. In this paper we evaluated the effects of cis-9, trans-11 CLA on the metabolic profile of MCF-7 and MDA-MB-231 breast cancer cells using high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) spectroscopy. The NMR spectra showed that phosphocholine level, a cancer malignance biomarker, was reduced in both cells treated with CLA, but the reduction was more pronounced in MCF-7 cells. The NMR spectra also showed that CLA has opposite effect on MCF-7 and MDA-MB-231 acetone metabolism. Acetone signal has been observed in the spectra of MDA-MB-231 control cells, but not in the spectra of the cells treated with 50 and 100 μM CLA. Conversely, the acetone signal is very small or not observed in the NMR spectra of MCF-7 control cells and in cells treated with 50 μM of CLA, but is very strong in the spectra of the cells treated with 100 μM of CLA. Therefore, this CLA concentration is causing a ketosis in MCF-7 cells by inducing the use of fatty acids as an energy source or by reducing acetone catabolism. These results indicate that CLA interfere in the metabolism of both cells. However, the strongest effect has been observed on the metabolism of MCF-7 cells cultivated in the presence of 100 μM CLA. Therefore, CLA could be a potential anticarcinogenic drug, especially for cells with positive estrogen receptor, such as MCF-7.