Dr. Flint researches hormonal influences on cell cycle regulation, targeted molecular therapies, drug metabolism, drug resistance and cancer. Her primary research project involves the direct interplay between stress hormones (cortisol, NE, and E), cancer and chemotherapy. This is accomplished through a mechanistic study of administration of stress hormones to cancerous cells, and observing these effects both in vitro and in rodent models. The goal is to identify predictive characteristics for molecular response, elucidating the mechanism of action of hormones in cancerous cells, and characterizing the genomic/proteomic profiles encoding cell cycle regulation.

Dr. Flint’s primary research project involves the direct interplay between stress hormones (cortisol, NE, and E), cancer and chemotherapy. This is accomplished through a mechanistic study of administration of stress hormones to cancerous cells, and observing these effects both in vitro by proteomics and in rodent models. We are first investigating paclitaxel, a drug used to treat metastatic breast cancer which acts on the cell cycle.



Dr. Flint has conducted a pilot-scale investigation to assess the adaptation of MDA-MB-231 breast cancer cells to the SILAC medium and 10% dialyzed FBS, to evaluate the ability to identify isotopomeric peptides from this cell system by MS and to demonstrate the presence of a measurable proteomic effect underlying the stress hormone influence on drug resistance.  She cultured one population of MDA-MB-231 cells in ‘light’ SILAC medium (supplemented with L-lysine and L-arginine with natural abundance isotopes) and one population of cells in SILAC medium supplemented with ¹³C₆-lysine and ¹³C₆¹⁵N₄-arginine. The cells were cultured in the ‘light’ and ‘heavy’ isotope-containing SILAC medium for 6 passages. Importantly, she observed no notable differences in morphology or cell proliferation due to either the heavy isotope containing medium or light medium compared to normal media. To test the effect of stress hormones on drug resistance, the light media served as our control population and the cells were exposed to 10^-7M paclitaxel for 48 hr (Fig. 3).

The cells in heavy isotope containing media served as our experimental population and were incubated with 10^-7M paclitaxel, cortisol, NE and E for 48 hours. The cells were then washed, pelleted and counted and mixed together with equal cell numbers. The samples were lysed by boiling in Laemmli buffer prior their resolution by 1D SDS-PAGE. The gel was stained Coomassie blue to provide a general estimation of the protein lysate integrity. 20 protein bands of equivalent size were excised from the gel and digested overnight with sequencing grade trypsin. The extracted tryptic peptides from each of the 20 gel bands were separately analyzed by nanoflow reversed phase (RP) LC coupled online with a hybrid linear ion trap-Orbitrap MS. Please see the 'scientific graphics' page for an illustration of the SILAC workflow for quantifying relative changes in protein abundance from two cell populations in culture.

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Important Publications

Flint MS, RA Budiu, P Teng, M Sun, D Stolz, M Lang, AM Vlad, BL Hood and TP Conrads.  Restraint stress and stress hormones significantly impact T lymphocyte migration and function through specific alterations of the actin cytoskeleton.  Brain Behavior & Immunity in press, 2011.

Flint MS, K McCarty, F Jenkins, TP Conrads, M Sun and A Baum.  Psychological stress accelerates the onset of tumour formation and alters the type and location of tumours in a DMBA mouse carcinogenesis model.  Stress and Health 27:doi:10.1002/smi.1343.

Hood BK, J Grahovac, MS Flint, M Sun, N Charro, D Becker, A Wells and TP Conrads.  Proteomic analysis of laser capture microdissected melanoma cells from skin organ cultures.  Journal of Proteome Research 9:3656-3663, 2010.

Bateman NW, M Sun, BL Hood, MS Flint and TP Conrads.  Defining central themes in breast cancer biology by differential proteomics:  Conserved regulation of cell spreading and focal adhesion kinase.  Journal of Proteome Research 9:5311-5324, 2010.

Flint MS, BL Hood, M Sun, NA Stewart, J Jones-Laughner and TP Conrads.  A proteomic analysis of the murine liver in response to a combined exposure to psychological stress and 7,12-dimethylbenz(a) anthracene.  Journal of Proteome Research 9:509-520, 2010.

Flint MS, NE Bateman, G Kim, BL Hood, NA Stewart and TP Conrads.  Stress hormones mediate drug resistance to paclitaxel in human breast cancer cells through a Cdk-1 dependent pathway.  Psychoneuroendocrinology 34:1533-1541, 2009.

Flint MS, A Baum, WH Chambers and FJ Jenkins. Identifying molecular mechanisms involved in DNA damage and repair in 3T3 cells following stress hormone exposure. Psychoneuroendocrinology 32(5):470-479, 2007.