Immune System and Cancer

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Immune System and Cancer

• J.club
• 07/29/03

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What are NK cells? A part of the native immune
system, share a common early progenitor with T
cells but do not develop in the thymus 10 of
blood lymphocytes, defined by surface markers
(ex. CD56, NK 1.1, CD2, CD16) Activated by
IFN?, IFN? and IL-12 (IL-12 commonly used to
activate NK cells in vitro)
Involved in early response to infection with
certain viruses and intracellular bacteria
(first line of defense, giving CTLs time to
differentiate)
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Natural Killers NK discovered as tumor
killer cells Mice were immunized against a
tumor, then their lymphocytes tested for ability
to kill tumor cells in vitro. But negative
controls lymphocytes from unimmunized mice or
mice Immunized against a different tumor also
killed tumor cells very well! NK assay 51Cr
release from YAC-1 cells
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MHC/HLA review
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NK receptor overview
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NK receptors
Most inhibitory receptors recognize MHC I
molecules

• 2 groups
• Killer Immunoglobulin Receptors (KIRs)
• C-type lectin receptors (CD94NKG2 family member)
• Both have activating counterparts, but inhibitory
  signals dominant.
• Activation/inhibition depends on
• KIRs - long cytoplasmic tail with ITIMs vs. short
  tails adaptor with ITAMs
• C-type lectin receptors - NKG2 member a/b
  activating, c, e/h, f inhibitory

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NKG2d human and mouse ligands

• RAE-1/H60 evidence
• Tumors expressing RAE-1 or H60 are rejected, NK
  cell-dependent.
• Mice immune to re-challenge with the same tumor
  cells, even if
• RAE-1/H60 are no longer expressed a role for
  adaptive immune system

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• New activating receptor NKG2d
• Low homology to other NKG2 receptors, an
  activating receptor
• conserved between humans, mice and rats
• Expressed on NK cells, macrophages, ?/? and ?/?
  CTLs
• Homodimer, forms an activating complex with
  DAP-10, which
• contains SH2 domains and recruits PI3K
• Can override inhibitory signals from KIRs and
  C-type lectins

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Killing pathways (from Takeda et al, 2002)
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• Adhesion molecules may help NK get to tissue
• Human and rat NK cells synthesize fibronectin,
• mAbs against FN block NK cytotoxicity against
  YAC-1
• NK cells express ?4?1 and ?5?1 integrins, mediate
  adhesion to FN in an
• in vitro assay
• NK cells express L-selectin, its expression is
  upregulated by IFN?, IL-10
• and IL-12
• IL-12 also promotes NK adhesion to P and E
  (endothelial) selectins
• under flow conditions
• LFA-1
• N-CAM

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• Immune surveillance idea and NK cells
• In 1909, Paul Ehrlich proposed that the immune
  system could repress
• carcinomas. Idea was extended in 1957 by
  Burnet/Thomas immune
• surveillance as a way of maintaining tissue
  homeostasis.
• NK cells a good candidate
• Many virally infected and tumor cells express
  less MHC I, escape
• CTL detection/killing
• NK cells kill MHC I cells in vitro
• NK reject MHC I tumor cells, not same cells MHC
  I
• (same experiment for mets.)
• Irradiated mice get MHC I lymphocytes, rapid
  NK-mediated

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• Tumor/NK evidence in mice
• Direct
• NK cells kill MHC I - tumor cells in vitro
• Eliminate tumor cells from circulation of
  mice/rats
• Protect mice from MCA skin carcinogenesis
• CTL knockouts have OK control of
  carcinogen-induced sarcoma growth,
• perforin knockouts (no CTL or NK activity) have
  deficient control
• Correlative
• A/J mice have low NK activity and high rate of
  lymphoma,
• C57/BL6 mice have high NK cell activity and low
  rate of lymphoma

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• Tumor/NK evidence in mice
• Drawbacks
• No good data on protection from spontaneous
  tumors (except MCA)
• Good stimulation by blood cells but few other
  (ex. Not by low MHC I liver)
• In vitro models often activated by cytokines at
  far above physiological
• levels
• NK cells require homing signals (MIP-1? for
  homing to CMV foci in liver)
• No good mouse model lacking NK cells
• (until very recently a group was using a
  granzyme A promoter to express
• Ly49A cDNA, and got a mouse thats specifically
  NK-deficient, both by

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• Tumor/NK evidence in people
• Direct
• In vitro, IL-12 activated human NK cells are
  capable of killing MHC-
• tumor cells
• Chediak-Higashi syndrome impaired NK
  degranulation, susceptible to
• highly metastatic lymphomas
• Correlative in vivo
• Patients on immunosuppressants get more blood
  tumors
• People with congenital or acquired
  immunodeficiencies have a
• significantly higher incidence of malignancies
  (viral infection?)
• NK is impaired in cancer patients, by in vitro
  studies on YAC-1 and

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NKT cells A recently discovered subpopulation of
?? T cells that express NK markers (ex. NK 1.1,
Ly49 in mice), CD44, Ly6C Originate in bone
marrow, differentiate in the thymus Express a
limited set of T cell receptors, CD4/DN
(60/40) CD1-dependent activation (MHC I like
proteins conserved in mammals) Implicated in
immunoregulation and tumor growth, although not
clear if alone or NK-regulated
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CD1 ligand details Sites of constitutive
expression in mouse thymus, liver, spleen,
lung NKT recognize CD1 bound to
glycolipid (experimentally used -
?-galactosylceramide, ?-GalCer)
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• NKT function
• Specialized regulatory component of immune
  system?
• Secrete large amounts of Th1 and Th2 cytokines
  upon stimulation, fast
• Th1 inflammatory, IFN? main cytokine, involves
  CTLs and macrophages
• Th2 humoral, IL-4 main cytokine, stimulates
  T-helper cells and Ab
• production
• Can rapidly stimulate T and B cells in
  antigen-nonspecific manner
• Activate NK cells, macrophages, recruit dendritic
  cells
• Can induce Fas-mediated killing of CD1
  thymocytes
• Experimentally activated by anti-CD3

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• NKT evidence in cancer
• Rag -/- mice (lack NKT, T and B cells) get more
  metastases than wt mice
• with low IL-12 stimulation. Corrected by adoptive
  transfer of NKT cells.
• ?-GalCer is beneficial in preventing tumor
  growth/mets. in mice
• (stimulation of dendritic cells to release IL-12
  and activate NK?)
• IFN? release also important (stimulate TRAIL
  expression on NK?)
• Important in resistance to MCA-induced
  fibrosarcomas (no exogenous
• ?-GalCer or IL-12 stimulation)
• Purified NKTs cytotoxic to syngeneic MCA-induced
  tumor line

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NK/NKT big picture
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Immune System

• Innate Immune Responses -- components
• Macrophage, Dendritic cells, Neutrophils,
• Mast cells, Eosinophils, Basophils
• NK cells, NKT cells
• Complement system

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Acquired Immune Responses

• B cells
• CD4 T cells
• CD8 T cells

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Cancer Immunosurveillance Hypothesis

• It is an evolutionary necessity that there
  should be some mechanism for eliminating or
  inactivating such potentially dangerous mutant
  cells and it is postulated that this mechanism is
  of immunological character -- Macfarlane Burnet
  and Lewis Thomos (1957)
• Data disfavored the hypothesis studies using
  nude mice
• 1) Osias Stutman used CBA/H background, look
  atMCA
• carcinogen-induced tumor
• wt/nude nu/nu
• 7/39, 95days 5/27, 90days
• 2)10,800nu/nu wt mice in spontaneous tumor
  develp.

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Cancer Immunosurveillance Hypothesis

• Data supporting the hypothesis
• INF-? data block, KO, DN IFNGR1,or STAT-1 KO
  mice have more spon. Or induced tumors
• Perforin-/- more prone to MCA-tumor
• Rag2-/- increased rate of spontaneous tumor in
  aged mice
• Other KO mice researches

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Cancer Immunosurveillance Hypothesis

• Correlative data supporting the hypothesis
• Immune-suppressed patients have higher incidence
  of melanoma, lung cancer
• Positive correlation between tumor infiltrating
  lymphocyte response and increased survival
  (melanoma, breast, colon, prostate)

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Cancer Immunoediting
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Acquired Immune System?

• Not enough!
• CD8-/- mice seems to have
• similar rate of MCA induced
• tumor to WT (low MHC I!!)
• CD4-/- mice can reject syngeneic tumor graft
  while CD8-/- cant
• Rag2-/-
• In PND patients, CTLs targeting neuornal antigen
  cdr2 seem to protect the patients from tumor
  growth.

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Innate Immune Responses and Cancer---
Inflammation and Cancer

• Again, the hypothesis that tumor wounds that
  fail to heal is around for a long time. Virchow
  hypothesized that the origin of cancer was at
  sites of chronic inflammation. 1863
• But, is it true? Is inflammation helping or
  hindering tumor growth?

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Innate Immune Responses and Cancer---
Inflammation and Cancer

• Again, like everything else, two opposite views
• 1) Inflammatory infiltrations contribute to tumor
  growth by inducing DNA damage, providing growth
  and surviving factors, angiogenic/
  lymphangiogenic factor, and proteases -- Foes
• 2) Inflammatory infiltrations help to kill
  transformed cells, therefore limiting the growth
  of tumor. Friends

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Innate Immune Responses and Cancer---
Inflammation and Cancer

• Data supporting Foes
• 1) Association between chronic inflammation and
  cancer risk
• Malignancy Inflammatory stimulus
• Bladder schistosomiasis
• Cervical papillomavirus
• Colorectal inflammatory bowel disease
• Pancreatic chronic pancreatitis
• Lung bronchitis
• etc

Coussens LM and Werb Z, Nature, 2002,
420860 Balkwill F and Mantovani A, Lancet,
2001, 357539
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Inflammation and Cancer

• Cellular components
• Polymorphonucleates (PMNs)

Mast cells
TFN-a, VEGF, FGF-2, IL-8
Chemokines (IL-8, IP-10, MIG, MIP-1a,b etc)
VEFG
Tryptase Chymase
MMPs
Angiogenesis
Recruit TAMs
Angiogenesis
ECM remodeling, Facilitate migration
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Macrophages (TAMs)
MMPs, uPA
Thrombospondin-1
Angiogenesis
IL-2 IFN-g IL-12
ECM remodeling, Facilitate migration
IL-10 (tumor as well)
TGF-b1 PDG bFGF TGF-a IGF-I/II
TNF-a IL-1
CTLs
Kill tumor cells
Tumor growth
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Inflammation and Cancer

• Data supporting Friends
• Individual cytokines been shown to mediate
  tumoricidal activity (TRAIL)
• Activated macrophages mediate tumor rejection
• Some report says TAM positively correlate
  disease-free probability after surgery (while
  others report not informative, both prostate
  cancer)

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Why all these conflicting data?

• They are looking at different stages

Csf1op/csf1op(do not express CSF1 which recruits
MAPs) does not affect the incidence or the
growth of the primary tumors, but delayed the
dev. to invasive, metastatic carcinomas. ? 2
stages CSF-1 promote the later stage. - Lin EY
et al., 2001
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Why all these conflicting data?

• Depend on the type of tumor and the stage of
  tumor secrete cytokines, chemokines to attract
  leukocytes,actively involved in the modulation of
  immune responses (Th1 vs. Th2 etc..)