• Welcome to the Hollenhorst Lab at IU

  • Research

    About the Lab


    Specificity of oncogenic transcription factors


    Transcription factors are proteins that bind to specific places in the genome and regulate which genes should be turned on or off. Humans have almost 2000 transcription factors that can be grouped into "families" of factors with similar DNA binding domains. Due to the similarity of these DNA binding domains, most members of transcription factor families are thought to bind to similar DNA sequences. Despite this similarity, different members of transcription factor families can have very different biological functions. How does this work? If these factors bind the same sequence you would expect them to bind to the same gene targets. But we know that similar transcription factors can have very different biological functions, and in that case you would expect them to activate or repress different genes. One example of this conundrum is the ETS family of transcription factors. There are 28 ETS transcription factors in the human genome. They all bind to a very similar DNA sequence in vitro. However, they all have very different biological functions in vivo. For example, some ETS proteins cause cancer (oncogenes), some inhibit cancer formation (tumor suppressors), and some have no role in cancer. We are leaders in the use of both genomic and biochemical techniques to uncover molecular mechanisms that differentiate function in the ETS and other transcription factor families.


    One of our more recent studies (Kedage et al. 2016 Cell Reports) used biochemistry to show that the four ETS transcription factors that can cause prostate cancer are the only four ETS family members that bind to the co-activator EWS. This identified a molecular mechanism of oncogenic specificity in the ETS family. Because the EWS/ETS interaction is so specific for oncogenic transcription factors, it represents an ideal drug target. We have recently performed a small-molecule screen to identify compounds that can inhibit this protein-protein interaction (Nicholas et al. 2020 PLoS One).





    What are the molecular mechanisms that allow transcription factors expressed due to gene fusions to promote cancer?


    The TMPRSS2:ERG gene fusion is the most common genomic alteration in prostate cancer. It results in expression of the transcription factor ERG in adult prostate cells, a cell type where ERG is normally silent.


    The EWS:FLI1 gene fusion is the causative lesion in 95% of Ewing sarcoma cases. It results in expression of a chimeric protein that includes the N-terminus of EWS and C-terminus of the transcription factor FLI1.


    Various fusions with the transcription factor TFE3 cause a rare but deadly form of renal cell carcinoma (tRCC).


    We study all three of these diseases in an attempt to identify key molecular mechanisms that can be targeted for therapeutic development. Interestingly, if we artificially fuse the N-terminus of EWS to any ETS family transcription factor, it allow that fusion protein to function like ERG and drive cell migration in prostate epithelial cells (Kedage et al 2016 Cell Reports). What is the key to this function? The N-terminus of EWS is intrinsically disordered and can drive phase separation. Does this play a role?

    How does signaling regulate ERG function in prostate cancer?


    Both the Ras/MAPK and PI3K/AKT pathway are important for ERG to promote prostate cancer. We have shown that MAPK signaling allows ERK to phosphorylate ERG, resulting in the loss of an interaction between ERG and the co-repressor EZH2 (Kedage et al. 2017 JBC). ERK is recruited to phosphorylate ERG only at certain regions of the genome. This way, ERK recruitment acts like a switch to control which genes ERG activates, and which genes ERG represses (Strittmatter et al. 2021 PLoS Genetics). We have also shown that the PI3K/AKT pathway can alter the ERG cistrome, allowing ERG to bind to genes that regulate the differentiation of prostate cells to a luminal epithelial cell state (Strittmatter et al. 2021 PLoS Genetics). We are currently using single-cell RNA sequencing experiments to determine how the interplay between Ras/MAPK and PI3K/AKT signaling regulate ERG function across distinct cell types within prostate tumors.

  • Join our group

    Graduate Students

    We accept graduate students through the following programs:

    Postdoctoral Fellows

    We sometimes have postdoctoral opportunities available. Contact Dr. Hollenhorst for details.

  • Lab Members

    Dr. Peter C. Hollenhorst

    Associate Professor of Biochemistry & Molecular Biology, Medical Sciences Program

    B.S. Chemistry and Biology, St. Norbert College

    Ph.D. Biomolecular Chemistry, University of Wisconsin-Madison

    American Cancer Society Postdoctoral Fellow, Huntsman Cancer Institute, University of Utah

    Stevie Morris

    Lab Manager

    B.S., Indiana University

    Dr. Stephanie Metcalf

    American Cancer Society Postdoctoral Fellow

    Ph.D. Louisville

    B.S. IUPUI

    Dr. Saranya Rajendran

    Assistant Research Professor

    Postdoctoral Associate, Yale University

    Ph.D. Biotechnology, Anna University

    M.S. University of Madras

    B.S. Lady Doak College

    Nick Downing

    Cell, Molecular and Cancer Biology Graduate Student

    M.S. Biochemistry, Indiana University School of Medicine

    B.A. Cellular and Molecular Biology DePauw University

    Michael Kwakye

    Biotechnology Masters Student

    B.S. Biology Indiana University

    Renee Kinne

    Cell, Molecular and Cancer Biology Graduate Student

    B.S. Michigan State University


    Lauren Konig

    Undergraduate Researcher


    Alex Kritzer

    Undergraduate Researcher


    Kiah Royse

    Undergraduate Researcher


  • Former Lab Members


    Nagarithinam Selvaraj (former postdoc) - Developmental Scientist II, Leidos Biomedical Research, Frederick MD

    Justin Budka (former graduate student) - Research Scientist, Kite Pharma, Santa Monica CA

    Josh Plotnik (former graduate student) - Senior Scientist, AbbVie, North Chicago IL

    Vivek Kedage (former graduate student) - Scientist, MedGenome, Foster City CA

    Taylor Nicholas (former graduate student) - Postdoctoral Fellow, Fred Hutchinson Cancer Research Center

    Brady Strittmatter (former graduate student) - Postdoctoral Fellow, Northwestern University Feinberg School of Medicine

    Ben Greulich (former graduate student) - Postdoctoral Fellow, Duke University School of Medicine


  • Publications

    Nicholas, T.R., Metcalf, S.A., Greulich, B.M., and P.C. Hollenhorst. (2021) Androgen signaling connects short isoform production to breakpoint formation at Ewing sarcoma breakpoint region 1. NAR Cancer 3(3), zcab033.
    Strittmatter, B.G., Jerde, T.J., and P.C. Hollenhorst. (2021) Ras/ERK and PI3K/AKT signaling differentially regulate oncogenic ERG mediated transcription in prostate cells. PLoS Genetics 17(7):e1009708.
    Greulich, B.M., Plotnik, J.P., Jerde, T.J., and P.C. Hollenhorst. (2021) Toll-like receptor 4 signaling activates ERG function in prostate cancer and provides a therapeutic target. NAR Cancer 3(1), zcaa046.
    Nicholas, T.R., Meng, J., Greulich, B.M., Morris, T.S., and P.C. Hollenhorst. (2020) A high-throughput screen identifies inhibitors of the interaction between the oncogenic transcription factor ERG and the cofactor EWS. PLoS One 15(9):e0238999.
    Budka, J.A., Ferris, M.W., Capone, M.J., and P.C. Hollenhorst. (2018) Common ELF1 deletion in prostate cancer bolsters oncogenic ETS function, inhibits senescence and promotes docetaxel resistance. Genes and Cancer 9:198-214.
    Damayanti, N.P., Budka, J.A., Khella, H.W.Z., Ferris, M.W., Ku, S.Y., Kauffman, E., Wood, A.C., Ahmed, K., Chintala, V.N., Adelaiye-Ogala, R., Elbanna, M., Orillion, A., Chintala, S., Kao, C., Linehan, W.M., Yousef, G.M., Hollenhorst, P.C., and R. Pili. (2018). Therapeutic targeting of TFE3/IRS-1/PI3K/mTOR axis in translocation renal cell carcinoma. Clinical Cancer Research
    Tomar, S., Plotnik, J.P., Haley, J., Scantland, J., Dasari, S., Sheikh, Z., Emerson, R., Lenz, D., Hollenhorst, P.C., and A.K. Mitra. (2017). ETS1 induction by the microenvironment promotes ovarian cancer metastasis through focal adhesion kinase. Cancer Letters 414:190-204
    Adelaiye-Ogala, R., Budka, J., Damayanti, N.P., Arrington, J., Ferris, M.W., Hsu, C.C., Chintala, S., Orillion, A.R., Miles, K.M., Shen, L., Elbanna, M., Ciamporcero, E., Arisa, S., Pettazzoni, P., Draetta, G.F., Seshadri, M., Hancock, B.A., Radovich, M., Kota, J., Buck, M., Keilhack, H., McCarthy, B.P., Persohn, S.A., Territo, P.R., Zang, Y., Irudayaraj, J., Tao, A.W., Hollenhorst, P., and R. Pili. (2017). EZH2 modifies sunitinib resistance in renal cell carcinoma by kinome reprogramming. Cancer Research 77(23): 6651-6666
    Kedage, V., Strittmatter, B.G., Dausinas, P.B., and P.C. Hollenhorst. (2017). Phosphorylation of the oncogenic transcription factor ERG in prostate cells dissociates polycomb repressive complex 2 allowing target gene activation. Journal of Biological Chemistry 292(42): 17225-17235
    Plotnik, J.P. and P.C. Hollenhorst. (2017). Genome-wide analysis of RAS/ERK signaling targets. Methods in Molecular Biology 1487:277-288.
    Plotnik, J.P. and P.C. Hollenhorst. (2017). Interaction with ZMYND11 mediates opposing roles of Ras-responsive transcription factors ETS1 and ETS2. Nucleic Acids Research 45(8):4452-4462
    Kedage, V., Selvaraj, N., Nicholas, T.R., Budka, J.A., Plotnik, J.P., Jerde, T.J., and P.C. Hollenhorst. (2016). An interaction with Ewing's sarcoma breakpoint protein EWS defines a specific oncogenic mechanism of ETS factors rearranged in prostate cancer. Cell Reports 17(5): 1289-1301.


  • News

    Feb 2022

    Stephanie Metcalf was awarded an American Cancer Society Postdoctoral Fellowship. Congrats Dr. Metcalf!

    May 2021

    Brady Strittmatter published his thesis research in PLoS Genetics and defended his thesis. Congrats Dr. Strittmatter!

    May 2020

    Taylor Nicholas published her paper identifying an inhibitor of the ERG/EWS interaction in PLoS One and successfully defended her thesis. Congrats Dr. Nicholas!

    Feb 2020

    Ben Greulich received the Medical Sciences Program Doane and Eunice Wright fellowship to support his work in the lab. Congrats Ben!

    April 2019

    Brady Strittmatter presented his research at the AACR Annual Meeting in Atlanta GA

  • Contact Us

    We are located in Jordan Hall,

    Indiana University

    Bloomington, Indiana

    Peter's email is pchollen@indiana.edu

    Peter's office phone: 812-855-1151

    Hollenhorst lab phone: 812-856-7608

  • Funding

    Research in the Hollenhorst Lab is supported by...

    Genitourinary Malignancies Pilot Funding

    Funding for Brady Strittmatter

    Funding for Ben Greulich

    National Cancer Institute R01