Phone: (303) 724-3921
The main focus of my laboratory is to determine the role of Ras/MAPK signaling and Ets transcription factors in epithelial cell development and tumorigenesis, with a focus on pituitary and mammary model systems.
With regards to the pituitary project, we study how the combinatorial action of Ets factors, Ets-1 and GABP, acting in concert with the POU-homeodomain transcription factor, Pit-1, serve to regulate the lactotrope-specific basal and Ras-regulated expression of the prolactin gene. Utilizing biochemical, structural, molecular and transgenic approaches, we have discovered that Ets factors play a critical role in specifying lactotrope cell identity in pituitary ontogeny. Using transgenic mice, we show that targeting a dominant-negative Ets transgene to the pituitary lactotrope lineage abrogates pituitary lactotrope development. We are also studying the biological role of Pit-1ß, an alternative-splice form of Pit-1, which appears to act as a negative regulator of Pit-1 functions.
We also seek to elucidate the molecular mechanisms by which lactotrope adenomas arise and why they rarely progress to frank carcinoma. To this end, we have generated GH4 pituitary cell lines stably expressing a doxycycline-regulated HA-V12Ras, to determine whether persistent vs short-term MAPK activation promotes cell proliferation, differentiation or apoptosis.
Finally, we also plan to address the role of adult pituitary progenitor/stem cells in facultative lactotrope expansion during pregnancy and in tumorigenesis.
With regards to our breast cancer project, we study the role of the epithelial-specific Ets transcription factor, Ese-1, in human mammary epithelial cell tumorigenesis. Ese-1 is over-expressed in many breast cancers and, thus, it is particularly relevant in human disease. We have shown that Ese-1 confers a transformed phenotype to immortalized, but nontransformed MCF-12A human mammary epithelial cells via a novel cytoplasmic mechanism. We also demonstrated that exclusive cytoplasmic targeting of a unique, 40-AA serine- and aspartic rich (SAR) subdomain is both necessary and sufficient for the transformation response.
Finally, using anti-Ese-1 monoclonal antibodies that we developed, we found Ese-1 to be expressed in the nucleus in established breast cancer cell lines, and we demonstrated that Ese-1 is required to maintain the transformed state by using shRNA knockdown of endogenous Ese-1 in these cells. Taken together, these studies reveal that Ese-1, as a sole agent, acts via a cytoplasmic mechanism to initiate transformation, but once mammary cells are fully transformed, via the action of several mechanisms, then nuclear Ese-1 is required to maintain the malignant phenotype.
We are making a significant commitment to inducible-methods and transgenic approaches to decipher the role of Ras/MAPK signaling, and specific POU-homeodomain and Ets transcription factors in mediating the ontogeny, maintenance and tumorigenesis of epithelial cells in the pituitary and mammary systems.
1. Prescott JD, Koto K, Singh M, Gutierrez-Hartmann A. The ETS transcription factor ESE-1 transforms MCF-12A mammary epithelial cells via a novel cytoplasmic mechanism. Mol Cell Biol 24:5548-5564, 2004.
2. Farrow KN, Bradford AP, Tentler JJ, Gutierrez-Hartmann A. Structural and functional analysis of the differential effects of c-Jun and v-Jun on prolactin gene expression. Mol Endocrinol 18:2479-2490, 2004
3. Ferry AL, Locasto DM, Meszaros L, Bailey JC, Jonsen MD, Brodsky KS, Hoon CJ, Gutierrez-Hartmann A, Diamond SE. Pit-1ß reduces transcription and CBP recruitment in a DNA context-dependent manner. J Endocrinology 185:173-185, 2005.
4. Duval DL, Jonsen MD, Diamond SE, Murapa P, Jean A, Gutierrez-Hartmann A. Differential utilization of transcription activation subdomains by distinct coactivators regulates Pit-1 basal and Ras responsiveness. Mol Endocrinol, 21:172-185, 2006.
5. Gutierrez-Hartmann A, Duval DL, Bradford AP. ETS transcription factors in Endocrine Systems. Trends Endocrinol Metabolism. 18:150-158, 2007.
6. Jedlicka P, Gutierrez-Hartmann A. ETS transcription factors and gastrointestinal epithelial cell biology. Histol Histopathol 23:1417-24, 2008.
7. Jedlicka P, Sui X, Sussel L, Gutierrez-Hartmann A. Epithelial ETS transcription factors regulate enterocyte maturation, epithelial migration and architectural organization of the small intestinal crypt-villus unit in the mouse. Am J Path, 174:1280-1290, 2009.
8. Jedlicka P, Sui S Gutierrez-Hartmann A. The Ets dominant repressor En/Erm enhances intestinal epithelial tumorigenesis in ApcMin mice. BMC Cancer 9:197, 2009.
10. Jonsen MD, Duval DL, Gutierrez-Hartmann A. The 26-amino acid ß-domain of the POU-homeodomain transcription factor Pit-1ß is a novel, unique and independent interaction domain for a pituitary-specific co-repressor. Mol Endocrinol, 23:1371-1384, 2009
11. Schweppe RE, Kerege AA, Sharma V, Poczobutt JM, Gutierrez-Hartmann A, Grzywa RL, Haugen BR. Distinct Genetic Alterations in the MAPK Pathway Dictate Sensitivity of Thyroid Cancer Cells to MKK1/2 Inhibition. Thyroid, 19:825-835, 2009 (cover article).
12. Jean A, Gutierrez-Hartmann A, Duval DL. A Pit-1 threonine 220 phosphomimic reduces binding to monomeric sites to inhibit Ras and estrogen stimulation of the rat prolactin promoter. Mol Endocrinol 23:91-103, 2009.
13. Walker DM, Pozcobutt J, Gonzales MS, Horita H, Gutierrez-Hartmann A. ESE-1 is required to maintain the transformed phenotype of MCF-7 and ZR-75 human mammary epithelial cells. Open Cancer J, in press.