Stem Cell Laboratory
Mayo Clinic Cancer Center
f o u r t e e n T H
A n n u a l
MAYO–LUTHER FORUM ON
HEMATOPOIETIC and
STEM CELLS
Cancer Stem Cells and
Cancer Initiating Cells
Friday, July 17, 2009
8:30 a.m.—1:00 p.m.
Geffen Auditorium, Subway Level
Gonda Building
Mayo Clinic
Rochester, Minnesota
Program
8:30 a.m.
‘ Ph.D.
Stanimir Vuk-Pavlovic,
Welcome and Introduction
8:35 a.m.
Meenhard Herlyn, D.V.M., D.Sc., The Wistar Institute
From Slow–Cycling Melanoma Cells to New Therapy Strategies
9:20 a.m.
John T. Isaacs, Ph.D., Johns Hopkins University
The Role of CD133 in Normal Human Prostate Stem Cells and
Malignant Cancer Initiating Cells
10:05 a.m. Craig T. Jordan, Ph.D., University of Rochester
Characterization and Therapeutic Targeting of Cancer Stem Cells
10:50 a.m. Discussion and Coffee Break
11:10 a.m. Jeffrey M. Rosen, Ph.D., Baylor College of Medicine
Intrinsic Therapeutic Resistance of Breast Cancer Stem Cells
11:55 a.m. John S. Yu, M.D., Cedars-Sinai Medical Center
Stem Cells in Glioblastoma Propagation and Therapy
12:40 p.m. General Discussion
1:00 p.m.
Adjourn
Time allocated to presentations includes five minutes for discussion.
Mrs. Adelyn Luther
“Medical research eventually touches everyone’s life.
When a health problem develops, you want the brightest
minds working on a solution. That is why I am so
pleased to support Mayo’s programs.”
– Mrs. Adelyn Luther
Mrs. Adelyn L. Luther has been a major supporter of Mayo Clinic. She has been
deeply interested in medical research, especially cancer and blood diseases.
Her gifts are recognized in the Maurice Gordon Hematopathology Laboratory,
named for her husband, who died in 1967, and the Luther-Mayo Stem Cell
Biology Program. This innovative biomedical program includes the Stem Cell
Laboratory in the Guggenheim Building, as well as the Mayo-Luther Forum,
which brings noted scientists to Mayo for symposia and discussions of major
issues in cell biology and cell engineering.
Maurice Gordon was a vital energetic business leader in Minnesota. He
started Gordon Millwork after World War II and founded Cardinal IG in 1961
to supply window glass to the millwork firm. When Mr. Gordon passed away
in the summer of 1967, Mrs. Luther stepped in to lead this major business
enterprise. She is still active in the business today.
Mrs. Luther’s philanthropy is an outstanding example of generosity and
commitment that, united with a creative approach to medical science, yield
results that benefit patients from many walks of life.
From Slow–Cycling Melanoma Cells to New Therapy Strategies
Meenhard Herlyn, D.V.M., D.Sc.
The Wistar Institute
Philadelphia, Pennsylvania
Biography – Dr. Herlyn earned a D.V.M. at the Veterinary Medical School in
Hannover, Germany and a D.Sc. in Medical Microbiology at the University
of Munich, Germany. Subsequently he joined The Wistar Institute to pursue
his studies of skin biology and melanoma. Initially Dr. Herlyn catalogued
melanoma cell surface proteins to better understand the means whereby tumor
cells use for locomotion, attachment to vessels and spreading to distant sites.
Later he developed model systems that reconstruct the events associated with
malignant transformation in humans. Today Dr. Herlyn’s major research
interests are normal and malignant stem cells and targeted therapy for
melanoma, for squamous cell carcinoma of the esophagus, head and neck as
well as for breast cancer. His studies, documented in over 400 publications,
have been supported by grants from the National Cancer Institute. Currently
Dr. Herlyn is professor and chair, Molecular and Cellular Oncogenesis Program
at The Wistar Institute. In addition, he serves as associate director of the Wistar
Institute Basic Research Cancer Center. He also holds appointments as professor
of dermatology and professor of pathology and laboratory medicine at the
University of Pennsylvania School of Medicine. Dr. Herlyn is a member of the
Biology and Molecular Biology and Bioengineering Graduate Programs at the
University of Pennsylvania School of Medicine.
Abstract – Melanoma can develop from normal epidermal pigmented
melanocytes, dermal neural crest stem cells, hair follicle neural crest stem cells,
or melanocytes reprogrammed into neural–crest–like stem cells. Which cell
type is most prone to malignant transformation is unclear, but it is possible
that more than one contributes to the often observed phenotypic heterogeneity
of the tumor. Heterogeneity could be related to numerous oncogenes and
tumor suppressor genes putatively involved in the generation of melanoma.
Most frequently mutated are the genes within the MAPK and PI3K/AKT
intracellular signaling pathways; their mutations lead to constitutive activation,
amplification, deletion, or silencing of distinct genes. The resulting distinct
melanoma signatures are related to their distinct responses to targeted therapies.
(For example, treatment with inhibitors specific for a mutant—e.g., BRAFV600E—
should be restricted to patients whose lesions carry the mutation.) Thus, the
finding that not all malignant cells are identical implies that melanomas are
composed of distinct subpopulations. However, how each subpopulation differs
from others is often difficult to assess and therefore controversial. Based on
the work in leukemia, the prevailing hypothesis is that tumor heterogeneity is
due to a hierarchy of clones with cancer stem cells (cancer initiating cells) on
the top. For melanoma we propose a more dynamic, stochastic model based
on the observation of a cell subpopulation that proliferates in asynchrony
with the majority of cells. We had termed these cells “label–retaining” in
analogy to keratinocyte stem cells. Label–retaining melanoma cells double in
culture only every two to four weeks whereas most cells double every one to
two days. Using a gene from jumonji family as marker, we found that slowly
cycling melanoma cells are individually distributed within the major rapidly
proliferating population; this suggests that self–renewal does not follow
a hierarchical pattern, but appears more complex and tied to intercellular
communication. Thus, slow cycling cells could be largely responsible for the
notorious melanoma resistance to drugs.
The Role of CD133 in Normal Human Prostate Stem Cells and
Malignant Cancer Initiating Cells
John T. Isaacs, Ph.D.
Johns Hopkins University
Baltimore, Maryland
Biography – Dr. Isaacs obtained the B.A. degree in natural sciences from Johns
Hopkins University, Baltimore, Maryland and the Ph.D. degree in biochemistry
at Emory University, Atlanta, Georgia. He returned to Hopkins for postdoctoral
training in cancer research. He has remained there where he is a professor of
oncology and urology, cellular and molecular medicine and chemical molecular
bioengineering. Dr. Isaacs’ research has focused on the biology and pathology of the
prostate. He has published more than 300 papers describing molecular mechanisms
of prostate cancer progression and the underlying genetic changes, development
and pharmacology of drugs for treatment of prostate cancer and, most recently,
prostate cancer initiating/stem cells. Currently Dr. Isaacs is editor-in-chief of The
Prostate, associate editor of Cancer Research, and member of editorial boards of Cancer
and Metastasis Reviews, Endocrine-Related Cancer and Clinical Cancer Research. His past
editorial service includes Current Opinion in Urology, Proceedings for Experimental
Biology and Medicine and Journal of Clinical Endocrinology and Metabolism. Dr. Isaacs
is a member of American Association for Cancer Research (member, Committee on
the Employment Register and Program Committee); American Chemical Society;
American Urological Association (member, Education Committee); Endocrine
Society; European Society for Urological Oncology and Endocrinology; Society for
Basic Urologic Research (past president); Urological Research Society; and Society for
Experimental Biology and Medicine. Dr. Isaacs served as a member of Experimental
Therapeutics Study Section, NIH; Steering Committee, Prostate Cancer Prevention
Trial; NCI-Inter-Prostate SPORE Clinical Trials Section Concept Review Committee
and Androgen Receptor Working Group, European Union–PRIMA Consortium
External Advisory Board, and External Scientific Advisory Board, Cephalon, Inc.
Abstract – To identify potentially novel targets for prostate cancer (PCa)
therapy, it is important to determine whether PCa originates from malignant
transformation of normal prostate stem cells or of more differentiated cells that
reacquired stem cell–like properties. Hence we compared normal human prostate
stem cells and cancer–initiating cells (CICs) in established PCa cell cultures.
We derived prostate epithelial cells (PrECs) from normal human prostate and
found that PrECs contained a small subpopulation of cells expressing CD133,
a stem cell marker. Purified CD133+ PrECs could self–renew and regenerate
cell populations that expressed markers of transit–amplifying cells (ΔNp63),
intermediate cells (prostate stem cell antigen), and neuroendocrine cells (CD56+).
When injected into immunocompromised mice, these cells grew into tissues akin
to stratified human prostate, but depended on the presence of stromal cells. By
the use of different CD133–specific monoclonal antibodies, we found that CD133+
PrECs required full–length glycosylated CD133 protein on the membrane for
attachment and growth. In contrast, androgen receptor–positive (AR+) human
PCa cell lines contained fewer CD133+ cells. These CD133+ cells self-renewed,
expressed AR, generated phenotypically heterogeneous CD133–negative progeny
and proliferated without limits; these properties are consistent with the notion
that these CD133+ cells and CICs are identical. Unlike normal adult prostate
stem cells, prostate CICs are AR–positive and do not require functional CD133.
These findings suggest that prostate CICs derive from a malignantly transformed
intermediate cell that reacquires stem cell-like properties and not from a
malignantly transformed normal stem cell. In addition, this study demonstrates
that AR signaling pathways provide a therapeutic target for prostate CICs.
Characterization and Therapeutic Targeting of Cancer Stem Cells
Craig T. Jordan, Ph.D.
University of Rochester
Rochester, New York
Biography – Dr. Jordan received his B.A. degree from the University of
California, Berkeley, and the Ph.D. degree in molecular biology from Princeton
University, Princeton, New Jersey. As a postdoctoral fellow at the Whitehead
Institute for Biomedical Research, Massachusetts Institute of Technology,
Cambridge, Massachusetts and Genentech Inc., San Francisco, California he
studied stem cell biology. After a brief period in industry (Aastrom Biosciences
and Somatix Therapy Corporation), Dr. Jordan served as junior faculty at the
University of Kentucky, Lexington, Kentucky. From there he moved to the
University of Rochester, Rochester, New York, where currently he serves as
professor of medicine. Dr. Jordan’s research interests have encompassed studies
of fetal and adult hematopoiesis, use of recombinant viruses for transduction
of hematopoietic cells, genes regulating stem cell function and fate and biology
of leukemias with emphasis on leukemic stem cells. More recently, Dr. Jordan
contributed discoveries leading to therapeutic means for specific targeting of
leukemic stem cells. Dr. Jordan was a member, Board of Trustees, International
Society of Experimental Hematology (2002-2004); Chair, Scientific Committee on
Stem Cells, American Society of Hematology (2005-2007); and Chair, LIB Study
Section, American Cancer Society (2005-2006). He was a Scholar (2003-2008) and
Stohlman Scholar (2008) of the Leukemia and Lymphoma Society. Dr. Jordan’s
work has been supported by the National Cancer Institute, Leukemia and
Lymphoma Society, Samuel Waxman Cancer Foundation, U.S. Department of
Defense, New York State and American Cancer Society.
Abstract – It has been shown recently that numerous human cancers arise
from stem cells or progenitor cells necessitating the need for cancer stem cell
(CSC)–specific drugs. However, no drug is known to target specifically CSCs
while sparing normal tissue. In the search for CSC–specific drug targets we
have undertaken a characterization of CSC–specific survival mechanisms using
blood cancer—leukemia—as a model. In leukemia stem cells (LSCs) we found
that the intracellular signaling pathway mediated by nuclear transcription factor
kB (NF-kB) was constitutively active, while in normal hematopoietic stem cells
it was inactive. Moreover, LSCs contained higher levels of reactive oxygen
species (ROS) than normal cells. Because NF-kB inhibition and high ROS levels
are associated with increased rates of programmed cell death (apoptosis), we
hypothesized that NF-kB inhibition and reduction of ROS levels will sensitize
LSCs to apoptosis. To test this hypothesis, we incubated leukemia cells with
parthenolide (PTL), a known NF-kB inhibitor and oxidant and found that it
selectively killed the LSCs. Subsequently we tested PTL activity in a large
collection of human tumor cell lines and observed that PTL killed cells in
approximately 80 percent of them. Based on these results we propose PTL as the
first member of a novel class of drugs for CSC–specific therapy of leukemia and
possibly other cancers. In addition, we have generated a PTL analog, dimethyl
amino parthenolide (DMAPT) with superior pharmacologic properties. DMAPT
is orally bioavailable and well tolerated by mice and dogs; it is active in these
animals as documented by changes in numerous biomarkers, including NF-kB
inhibition. Taken together, these data indicate that DMAPT could provide a
novel agent for cancer therapy.
Intrinsic Therapeutic Resistance of Breast Cancer Stem Cells
Jeffrey M. Rosen, Ph.D.
Baylor College of Medicine
Houston, Texas
Biography – Dr. Rosen received the B.A. degree from Williams College,
Williamstown, Massachusetts and the Ph.D. degree at Roswell Park Memorial
Cancer Institute, Buffalo, New York. He completed his postdoctoral studies under
the supervision of Bert O’Malley at Vanderbilt University, Nashville, Tennessee.
Subsequently Dr. Rosen joined Baylor College of Medicine as a founding member
of the first department of cell biology in the USA. As recipient of an American
Cancer Society Scholar Grant he spent a sabbatical leave with George Stark and
Ian Kerr at the Imperial Cancer Research Laboratories participating in studies
of interferon action that led to the discovery of the Jak/Stat pathway. Currently
Dr. Rosen is a Distinguished Service Professor and the C.C. Bell Professor of
Molecular and Cellular Biology and Medicine at Baylor College of Medicine.
He is the recipient of the MERIT award from the National Institutes of Health
currently in its thirty-third year of consecutive funding. His laboratory has
authored 200 publications and book chapters dealing with hormonal regulation
of gene expression, signal transduction, normal mammary gland development,
breast cancer, transgenic animal models of breast and prostate cancer, mammary
gland stem and progenitor cells, and noncoding RNAs. Dr. Rosen has been the
recipient of the Endocrine Society Edwin B. Astwood Award and the Michael E.
DeBakey Excellence in Research Award.
Abstract – Despite the recent advances in breast cancer treatment, many patients
relapse after an initially favorable response to chemotherapy and radiation
therapy. There are at least two possible explanations for this observation. One
is that all cancer cells can acquire resistance resulting in decreased overall
sensitivity to therapy over time. Alternatively, a subpopulation of cells with
tumorigenic potential is intrinsically resistant to therapy. To distinguish
between the two options, we have used a unique p53null murine breast cancer
model that allowed us to identify a tumor initiating subpopulation of cells.
By comparing the transcriptome of this subpopulation with the transcriptome
of normal mammary–gland stem/progenitor cells, we found that the tumor
initiating cells expressed higher levels of DNA–damage response genes and
DNA repair genes. Consistent with these results is our in vitro and in vivo
demonstration of more efficient DNA damage repair in tumor initiating cells
than in the bulk tumor. This finding supports the hypothesis that DNA of
tumor–initiating “cancer stem cells” could be intrinsically more resistant
to damage explaining in part tumor resistance to radiation therapy and
chemotherapy. Further support for this hypothesis comes from our study
of paired human breast cancer core biopsies before and after chemotherapy;
this demonstrated that tumorigenic cells were intrinsically chemoresistant.
Conversely, in HER2–overexpressing tumors, lapatinib (an EGFR/HER2
tyrosine kinase inhibitor) decreased the relative proportion of cells of the
tumorigenic phenotype CD44+/CD24-/low and mammosphere formation. Such
cells are characterized by a gene signature otherwise found mainly in human
breast tumors of the recently identified claudinlow and metaplastic subtype;
this subtype expresses many mesenchyme–associated genes. Surprisingly,
post–treatment residual tumors contained a higher fraction of claudinlow cells,
consistent with therapy–mediated enrichment of resistant cells. Such cells
expressed higher levels of markers characteristic of epithelial–to–mesenchymal
transition. Thus, a small subset of cells expressing mesenchymal markers could
be partly responsible for the intrinsic breast cancer resistance to therapy.
Stem Cells in Glioblastoma Propagation and Therapy
John S. Yu, M.D.
Cedars-Sinai Medical Center
Los Angeles, California
Biography – Dr. Yu earned his bachelor degree in French literature and
biological sciences from Stanford University. Subsequently he spent a year
at the Sorbonne studying French literature and pursuing a fellowship in
immunology at the Institut Pasteur, both in Paris, France. He earned his M.D.
degree from Harvard Medical School and M.S. degree from Harvard University
Department of Genetics. Dr. Yu completed his neurosurgical residency at
Massachusetts General Hospital, Boston, where he was a neuroscience fellow
at the Neuroimmunology Unit, National Institute of Mental Health and a
Culpeper Scholar at the Molecular Neurogenetics Unit. Dr. Yu’s other honors
include the Preuss Award, Joint Section on Tumors, American Association of
Neurological Surgeons and Congress of Neurological Surgeons; the Young
Investigator Award, Joint Section on Tumors, AANS and CNS; the Academy
Award, Academy of Neurological Surgeons; and the Mahaley Clinical Research
Award, American Association of Neurological Surgeons. Currently, Dr. Yu is
director of surgical neuro-oncology and professor of neurosurgery, CedarsSinai Medical Center. Along with a clinical focus on the surgical treatment
of malignant and benign brain tumors, he is studying immunotherapy and
stem cell therapy for brain tumors. Dr. Yu has had a longstanding interest in
the use of neural stem cells as drug delivery vehicles for brain cancers and
neurodegenerative diseases and the role of cancer stem cells in glioblastoma
initiation and propagation. Dr. Yu was inducted into Castle and Connelly’s
America’s Top Doctors in 2005 and Marquis Who’s Who in America in 2008.
Abstract – Glioblastoma multiforme is the most frequent and most aggressive
primary brain tumor. The standard of care for this deadly disease includes
surgery followed by radiotherapy and chemotherapy with temozolomide.
Regrettably, this therapy does not extend life expectancy beyond the median
overall survival of 14.6 months. Recent identification of brain cancer stem
cells has provided a new hope for more effective treatments because it might
provide novel therapeutic opportunities by exploiting the features of stem cells
to inhibit brain tumor initiation, progression and invasion. Brain–cancer stem
cells (also designated “tumor initiating cells” or “tumor propagating cells”)
share some features with normal neural stem cells, but do not necessarily
originate from them. As most cancers, glioblastoma contains only a small
fraction of cancer stem cells, but these cells can significantly contribute to
therapeutic resistance, tumor vascularization and tumor invasion. In addition,
recent studies have demonstrated that cancer stem cells are chemoresistant
and could be the major source of cells responsible for glioblastoma recurrence.
The Yu laboratory has focused on the development of immunologic strategies
to target cancer stem cells. Neural stem cells have the ability to track tumor
cells and areas of neurodegeneration. This property is shared by bone marrowderived neural stem cells and can be exploited for use as delivery vehicles for
tumoricidal and/or neuroprotective agents.
First Mayo-Luther Forum, 1996
Lawrence A. Solberg, Jr., Ph.D., M.D.
John E. Wagner, M.D.
Bharat B. Aggarwal, Ph.D.
Pablo J. Cagnoni, M.D.
Robert Sackstein, M.D., Ph.D.
Eighth Mayo-Luther Forum, 2003
Rupert Handgretinger, M.D., Ph.D.
P. Jean Henslee-Downey, M.D.
Massimo F. Martelli, M.D.
Rainer Storb, M.D.
John E. Wagner, M.D.
Second Mayo-Luther Forum, 1997
Anne M. Kessinger, M.D.
Gerald J. Spangrude, Ph.D.
Margaret Anne Goodell, Ph.D.
Catherine M. Verfaillie, M.D.
Stephen G. Emerson, Ph.D., M.D.
Ninth Mayo-Luther Forum, 2004
Paul J. Leibson, M.D., Ph.D.
Elmar Reinhold Burchardt, M.D., Ph.D.
Jeffrey S. Miller, M.D.
Luis F. Porrata, M.D.
Bo Dupont, M.D., D.Sc.
Andrea Velardi, M.D.
Third Mayo-Luther Forum, 1998
Pablo Rubinstein, M.D.
R. Scott McIvor, Ph.D.
Irun R. Cohen, M.D.
Chella David, Ph.D.
Ephraim J. Fuchs, M.D.
Tenth Mayo-Luther Forum, 2005
Richard J. O’Reilly, M.D.
Brian Johnstone, Ph.D.
Ann Tsukamoto, Ph.D.
Andre Terzic, M.D., Ph.D.
Edwin M. Horwitz, M.D. Ph.D.
Fourth Mayo-Luther Forum, 1999
Jeffrey L. Platt, M.D.
Scott R. Burger, M.D.
Raj K. Puri, M.D., Ph.D.
Michal Schwartz, M.D.
James M. Robl, Ph.D.
Eleventh Mayo-Luther Forum, 2006
Hans-Michael Dosch, M.D., Ph.D.
Boris Nikolic, M.D.
Jeffrey L. Platt, M.D.
Alan Tyndall, M.B.B.S.
Jingwu Zhang, M.D., Ph.D.
Fifth Mayo-Luther Forum, 2000
Richard Champlin, M.D.
Yair Reisner, Ph.D.
Marc K. Jenkins, Ph.D.
Annemarie Moseley, Ph.D., M.D.
Rainer Storb, M.D.
Twelfth Mayo-Luther Forum, 2007
Richard Clarke
Gina C. Schatteman, Ph.D.
Shawn G. Rhind, Ph.D.
Omaida C. Velazquez, M.D.
Thomas K. Hunt, M.D.
Sixth Mayo-Luther Forum, 2001
Davor Solter, M.D., Ph.D.
Pamela Gehron Robey, Ph.D.
Doros Platika, M.D.
Minoru S.H. Ko, M.D., Ph.D.
Thomas B. Okarma, M.D., Ph.D.
Thirteenth Mayo-Luther Forum, 2008
Martin Pera, B.A., Ph.D.
Dan Kaufman, M.D., Ph.D.
Mahendra Rao, M.D., Ph.D.,
Su-Chun Zhang, M.D., Ph.D.
Martin Friedlander, M.D., Ph.D.
Seventh Mayo-Luther Forum, 2002
Drew M. Pardoll, M.D., Ph.D.
Stephen Mackinnon, M.D.
Cliona M. Rooney, Ph.D.
Antonio Tabilio, M.D.
Robert H. Vonderheide, M.D., D.Phil.
f o u r t e e n T H
© 2009 Mayo Foundation for Medical
Education and Research
Geffen Auditorium, Subway Level
Gonda Building
Mayo Clinic
Rochester, Minnesota
Friday, July 17, 2009
MC1604-33rev0509
A n n u a l
MAYO–LUTHER FORUM ON
HEMATOPOIETIC STEM CELLS
Cancer Stem Cells and Cancer Initiating Cells
Stem Cell Laboratory
Mayo Clinic Cancer Center
200 First Sreet SW
Rochester, Minnesota 55905