2006projectindexMinna

Medical Student Research Fellowship for Summer 2006

Mentor: Dr. John Minna/ Dr. Elisabeth D. Martinez
Department: Hamon Center for Therapeutic Oncology Research/Pharmacology
Room number: NB8.114
Mail Code: 8593
Phone number: 214-648-1635
E-mail: elisabeth.martinez@utsouthwestern.edu
Project title: The effect of epigenetic compounds on human cancer cells

Human subjects IRB approved project number (where applicable): N/A

Animal subjects IRB approved project number (where applicable): N/A

Project Type (patient-based research, animal-based research, or basic research; this characterization is only to permit a general classification for grouping similar types of projects): Basic Research

Brief Description of Project:

Pathologies such as human lung cancer result in many cases from the inappropriate silencing or activation of genes. It is well established that gene expression can be partly controlled by modulating the access of transcription factors to target genes through chemical modifications of promoter DNA and/or histones. These modifications are mediated by cellular enzymes, including DNA methyl transferases (DNMT), histone acetyl transferases (HAT) and histone deacetylases (HDAC). In many cancers, the expression or function of these proteins is altered, affecting the regulation of transcriptional processes and thus, cellular growth and function. Over the last several years, a few drugs have been identified that inhibit the methylation or de-acetylation pathways mediated by these enzymes. These compounds have had immediate application in the treatment of cancers because of their ability to reactivate aberrantly silenced tumor suppressor genes and block tumor cell growth. We have recently developed a unique approach to identify novel small molecule inhibitors of DNMTs and HDACs. We have carried out high content screens for such compounds resulting in the identification of eight bona fide hits and two active analogs. We propose now to characterize the biological effects of these compounds evaluating their anti-cancer activity.
Specific Aim 1: To evaluate the ability of the candidate epigenetic modulators to inhibit the growth of human lung, breast and melanoma cancer cells.
Specific Aim 2: To measure the re-activation of aberrantly silenced tumor suppressor genes in these cancer cell lines in response to our compounds.

Project title: Gene expression signatures for sensitivity and resistance to paclitaxel, docetaxel, and nano-particle delivered paclitaxel for human lung cancer derived cell lines.

Human subjects IRB approved project number (where applicable): N/A

Animal subjects IRB approved project number (where applicable): N/A

Brief Description of Project:

Lung cancer is a leading cause of cancer deaths in the U.S. and unfortunately current chemotherapy is still far from acceptable in terms of both efficacy and adverse side effects. In order to better understand the pathways involved and the relative efficacies of different chemotherapies, we have undertaken a comprehensive drug sensitivity program. This involves the screening of a panel of lung cancer cell lines and determining their sensitivity to chemotherapeutics as determined by the concentration of drug resulting in an inhibition of growth by 50% (IC50). The initial phase of this project will involve determining the IC50 values of 50 lung cancer cell lines with paclitaxel and docetaxel, two related and commonly used agents in the treatment of lung cancer. We already have data on paclitaxel that demonstrates ~1500 fold differences in IC50 values between sensitive and resistant cell lines. Docetaxel is used after paclitaxel resistance develops in patients. Thus, identifying lung tumor cells that either have the same or different sensitivities to paclitaxel and docetaxel potentially could be of clinical relevance. The second phase will involve interrogating the microarray data we have on these 50 cell lines based on correlating IC50 values with gene expression values. The result is typically a list of approximately 200 genes whose levels are increased (or decreased) greater than 4-fold in resistant compared to sensitive cell lines. The "gene list" is useful in a variety of ways. First, if multiple genes involved in a common pathway appear, it clearly suggests that pathway is involved in modulating sensitivity to that compound. Secondly, it provides a list of "targets" to "knockdown" using siRNAs or secondary agents that inhibit the protein if they are available. Thus, by the end of this project we hope to have additional drugable targets that potentiate the effects of paclitaxel and/or docetaxel. The potential therapeutic benefit is clear: by hitting two targets we hope to increase efficacy and reduce toxicity.

Previous Research Activities or Publications with Medical Students:

Dr. Elisabeth D. Martinez:

Publications

Danielsen, M. and Martinez, E. The glucocorticoid receptor resource (1996), Nucleic Acids Res 24:155-156.

Martinez, E., Moore, D., Keller, E. Pearce, D., Robinson, V., McDonald, P., Simons, S., Sanchez, E., Danielsen, M. The Nuclear Receptor Resource Project (1997), Nucleic Acids Res 25:163:165.

Martinez, E., Moore, D., Keller, E., Pearce, D., Vanden Heuvel, J.P., Robinson, V., Gottlieb, B., McDonald, P., Simons, S., Sanchez, E. and Danielsen, M. The Nuclear Receptor Resource: a growing family (1998), Nucleic Acids Res 26:239-241.

List, H.J, Smith, C., Martinez, E.D., Harris, V., Danielsen, M. and Riegel, A. Effects of Antiandrogens on Chromatin Remodeling and Transcription of the Integrated Mouse Mammary Tumor Virus Promoter (2000), Exp. Cell Research 260:160-165.

Martinez, E.D. and Danielsen, M. Loss of androgen receptor transcriptional activity at the G1/S transition: involvement of acetylation pathways (2002), JBC 277 (33):29719-29729.

Tirado, O.M., Martinez, E.D., Rodriguez, O.C., Danielsen, M., Selva, D.M., Reventos, J., Munell, F. and Suarez-Quian, C.A. Short-term effects of Methoxyacetic Acid on Androgen Receptor and Androgen-Binding Protein Expression in Adult Rat Testis (2003), Biol Reprod 68 (4):1437-1446.

Nagaich, A.K., Rayasam, G.V., Martinez, E.D., Becker, M., Qiu, Y., Johnson, T.A., Elbi, C., Fletcher, T.M., John, S., and Hager, G.L. Subnuclear Trafficking and Gene Targeting by Steroid Receptors (2004), Ann N.Y. Acad. Sci. 1024:213-220.

Martinez, E.D., Pattabiraman, N. and Danielsen, M. Analysis of the hormone binding domain of steroid receptors using chimeras generated by homologous recombination (2005), Exp Cell Res 308(2):320-33.

Martinez, E.D., Rayasam, G., Dull, A., Walker, D. and Hager, G.L. An Estrogen Receptor Chimera Senses Ligands by Nuclear Translocation (2005), J Steroid Biochem Mol Biol, 97(4) 307-321.

Qiu, Y., Zhao, Y., Becker, M., John, S., Parekh, B.S., Huang, S., Hendarwanto, A., Martinez, E.D., Chen, Y., Lu, H., Adkins, N.L., Stavreva, D.A., Wiench, M., Georgel, P.T., Schiltz, R.L., and Hager, G.L. HDAC1 acetylation is linked to progressive modulation of steroid receptor induced gene transcription, (2006), Molecular Cell (In Press).

Auld, D.S., Johnson, R.L., Zhang, Y., Veith, H., Jadhav, A., Yasgar, A., Simeonov, A., Zheng, W., Martinez, E.D., Westwick, J.K., Austin, C.P., and Inglese, J. GFP-based cellular assays analyzed by laser scanning microplate cytometry in 1536-well plate format, (2006), Methods in Enzymology Vol. 414, (In Press).

Martinez, E.D. and Hager, G.L. Development of assays for nuclear receptor ligands using fluorescently tagged proteins, (2006), Methods in Enzymology Vol. 414, (In Press).

Martinez, E.D., Dull, A., McMahon, J., Beutler, J. and Hager, G.L., High content screens for epigenetic modulators, (2006), Methods in Enzymology Vol. 414, (In Press).

Mentoring Activities

" Anindya Hendarwanto, Biologist, NCI, NIH: 2002-2005
" Brittany O'Dale, post-baccalaureate fellow, NCI, NIH: 2003-2004
" Duri Yun, undergraduate summer research fellow, NCI, NIH: summer 2002
" John Peyton Hobson, masters student, Georgetown University: 1998-1999

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