Stem Cells & Cancer

Norman Iscove M.D.

Multiple kinds of blood cell

Bone marrow is a factory for blood cells

Multiple assembly lines in marrow

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

Multiple assembly lines

Where do precursor cells come from?

Stem cells self-renew

Stem cell

Committed precursors

Differentiating precursors

Stem cells self-renew

Stem cell

Stem cells self-renew

Stem cell

Committed precursor

Stem cells self-renew

Stem cell

Committed precursor

Differentiating precursor

Stem cells self-renew

Stem cell

Stem cells self-renew

Stem cell

Committed precursors

Differentiating precursors

Stem cells self-renew

Stem cell

Stem cells self-renew

Stem cell

Committed precursor

Stem cells self-renew

Stem cell

Committed precursor

Differentiating precursor

Stem cells self-renew

Stem cell

Stem cells self-renew

Stem cell

Committed precursors

Differentiating precursors

Stem cells self-renew

Stem cell

Stem cells self-renew

Stem cell

Committed precursor

Stem cells self-renew

Stem cell

Committed precursor

Differentiating precursor

Stem cells self-renew

Stem cell

Cao et al., PNAS 101:221-226, 2004

Marrow cells

FACS

Stem cells

Remaining cells

Stem cellsOther precursors

Stem cells are the key transplantable element in marrow

time1 stem cell

1 in 20,0001 in 4,000

Stem cells can be purified

Imaging of stem cell transplantation

Normal blood cell formation

• blood cells produced by maturation of precursor cells

• precursor cells have finite proliferative capacity and lifespan

• stem cells are multipotent

• stem cells constantly replenish the precursor cells

• stem cells make new stem cells - "self-renewal"

• self-renewal is unique to stem cells and is essential for continued existence of blood cell production

Differing biology of precursor cells and stem cells

proliferative

Differing biology of precursor cells and stem cells

killed by anti-cancer drugs

Differing biology of precursor cells and stem cells

quiescent

Differing biology of precursor cells and stem cells

relatively resistant to anti-cancer drugs

Differing biology of precursor cells and stem cells

• >95% of marrow cells can be depleted by treatment with certain anti-cancer drugs

• stem cells may entirely resist short-term chemotherapy

Despite massive reduction in marrow bulk by chemotherapeutic agents, marrow will rapidly regenerate from surviving stem cells

Stem cells in normal mammary glands

Stingl et al, Nature 439:993, 2006

1 in 1500 mammary ductal cells can regenerate an entire gland

1 purified cell is sufficient

Leukemia

Leukemia

Normal

Leukemia initiating cells are rare and distinct

time

humanleukemiacells

florid leukemia

1 in 50,000 cells

1 %

leukemia cells

FACS

Stem cells

Remaining cells99 %

Dick et al, 1997

Breast tumour initiating cells are rare and distinct

time

Breast carcinoma

1 %

breast tumour cells

FACS

Stem cells

Remaining cells99 %

Clarke et al, 2003

Human breast carcinoma cells

Brain tumour initiating cells are rare and distinct

time

Brain tumour

1 %

brain tumour cells

FACS

Stem cells

Remaining cells99 %

Dirks et al, 2004

Human brain tumour cells

Colon tumour initiating cells are rare and distinct

time

Colon carcinoma

1 %

colon carcinoma cells

FACS

Stem cells

Remaining cells99 %

Dick et al, 2006

Human colon carcinoma cells

Cancer stem cells

• cancers, like normal tissues, constitute differentiating systems

• bulk cells produced by cancer systems have abnormal properties clinical disease

• bulk cells have finite lifespans

• cancer stem cells are rare and physically distinct from the bulk of tumour cells

• cancer stem cells are essential to the continued existence of cancer systems

• the biology of cancer stem cells differs from the rest of the cells in a tumour

Differing biology of precursor cells and stem cells

killed by anti-cancer drugs

relatively resistant to anti-cancer drugs

relapseremission

Jean Wang

early cure

eventual cure

Tumour stem cell

Stem cell concepts will change treatment strategies

treatment

conventional bulk reduction

stem cell targetted

combined anti-stem and bulk reduction

Cancer stem cells - future work

• new advances will be fuelled by the ability to detect cancer stem cells specifically

• new drugs will be identified by their ability to destroy tumour forming cells rather than bulk tumour cells

• stem cell-based treatment strategies will aim for cure

In leukemia, clinical illness requires interference with differentiation, mutational load may be complex

In solid tumours, clinical change only requires local growth

STOCHASTICMODEL

HIERARCHYMODEL

NO TUMOR

NO TUMOR

NO TUMOR

NO TUMOR

NO TUMOR

NO TUMOR

Models of tumor heterogeneity

Jean Wang

CD133+BRAINCANCER

Injectioninto brain 2004

AMLCD34+CD38

Intravenousinjection 1997

CD44+CD24

Injection into mammary fat pad 2003

BREASTCANCER

CD44+

HEAD & NECKCANCER

Subcutaneousinjection 2007

Identification of cancer-initiating cells

CD133+

Injection under renal capsule 2007

COLONCANCER

or subcutaneousinjection

Jean Wang

ResidualC-ICs

Tumor regeneratesRELAPSE

Tumor shrinksTHERAPIES THATKILL PROLIFERATING

TUMOR CELLS BUT NOT C-ICs

THERAPIES THATKILL C-ICs

Tumor degeneratesCURE

Development of effective anti-cancer therapies

REMISSION

THERAPIES THATKILL PROLIFERATING

TUMOR CELLS AND C-ICs

CURE

REMISSION

Jean Wang

The neutrophil assembly line

The neutrophil assembly line

The neutrophil assembly line

0 110 110

0 204 153

128 0 128

0 0 2550 216 159

0 194 143

128 128 128

128 0 0

Test

Test2

RholoLy6Ahic-kit+B220-CD3-

1 x 106

9 Gy

BM

BMtime

RKSL

CD49b- CD49b+

KL/FL/7/11

Onset of cell division

LTRC orSTRC 24 hr

1 x 106

9 d

100 cells KL/FL/7/11

Stem Cells

• persist throughout adult life

• responsible for permanence of cell-turnover systems

• generate differentiating progeny

• generate undifferentiated progenythat remain primitive

0.0

0.2

0.4

0.6

0.8

1.0

00 20 40 60 80

1

10

100

5 10 150

days360

1

10

100

Leukemia

A new era in cancer stem cells

• novel bioassays

• growth factors / morphogens

• surface markers

Human acute myeloid leukemia is organized as a hierarchy that originates from a primitive hematopoietic cell.Bonnet D, Dick JE. Nat Med. 3:730-7, 1997

Prospective identification of tumorigenic breast cancer cells.Al-Hajj M, Wicha MS, Benito-Hernandez A, Morrison SJ, Clarke MF. Proc Natl Acad Sci USA. 100:3547-9, 2003

Identification of human brain tumour initiating cells.Singh SK, Hawkins C, Clarke ID, Squire JA, Bayani J, Hide T, Henkelman RM, Cusimano MD, Dirks PB. Nature. 432:396-401, 2004

950 rBM cells

Short term "CFC" assays