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BCRF Grantee Since


Donor Recognition

The Play for P.I.N.K. Award

Area(s) of Focus

Kathryn B. Horwitz, PhD

Distinguished Professor
University of Colorado Denver
Denver, Colorado

Current Research

Approximately 75 percent of all breast cancers fall into the luminal classification and require estrogen to grow. While most of these cancers are treatable with anti-estrogen therapies, luminal cancers also contain cancer cells that do not need estrogen and are resistant to this therapy. Therefore, when luminal cancers are treated, the hormone-responsive cells die but the rogue cells are not affected. Dr. Horwitz’s BCRF research is focused on identifying different cell populations in breast cancers in order to prescribe rational combination therapies that target all the cells. She recently showed that combination anti-hormone/anti-growth factor therapies can efficiently suppress multiple cell populations. Another perplexing challenge with luminal cancers is that they often re-occur many years after initial diagnosis and treatment. Scientists don’t fully understand why this happens but believe that it may be due to a few tumor cells that had lain dormant for years in remote organs (like bone) and are unexpectedly roused and resume growing. Dr. Horwitz is currently studying the problem of tumor dormancy and has shown that sleeping tumors can be awakened by hormones. Her group is continuing their studies to better understand the significance of cell subtypes in luminal cancers, their role in initiating tumors and in spawning dormant mini-tumors at metastatic sites, and the roles of estradiol and progesterone in tumor arousal and recurrence.


Kathryn B. Horwitz, PhD joined the faculty at the University of Colorado after undergraduate studies at Barnard College, graduate studies at the UT Southwestern Medical School and postdoctoral work at UT San Antonio. Research in her laboratory is both basic and translational. It focuses on the role of women’s hormones – estradiol and progesterone – and their receptors, on luminal breast cancer cell heterogeneity, growth, treatment, metastasis and stem cells. Her lab has extensive expertise in molecular and tumor-cell biology, using in vitro and in vivo models and clinical samples. Long-term goals are to improve the strategies and outcomes of therapies for luminal disease. Research topics include: transcriptional mechanisms of progesterone receptors; epigenetic and post-transcriptional receptor modifications and signaling cross-talk; hormones in cancer growth; mechanisms of resistance to endocrine therapies; hormones and regulation of breast cancer stem cells; intratumoral cell heterogeneity in luminal disease; hormonal regulation of metastasis and the stromal microenvironment; development of new breast cancer models, and translation of laboratory findings into clinical practice. She has mentored numerous trainees who hold senior faculty posts at many US medical centers. She is a well-known national and international scholar, has served on multiple society boards, study sections and editorial boards, was elected President of the Endocrine Society, received its Fred Conrad Koch Award for exceptional contributions to endocrinology, and recently received the National Cancer Institute’s Rosalind E. Franklin Award for commitment to cancer research.