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1
ORIGINAL RESEARCH
A List of Candidate Cancer Biomarkersfor Targeted ProteomicsMalu Polanski and N. Leigh AndersonThe Plasma Proteome Institute, P.O. Box: 53450, Washington DC, 20009-3450, USA.
Abstract: We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of can-didate plasma biomarkers that could be useful in early cancer detection and monitoring given suffi ciently sensitive specifi c assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as “tumor associated antigens” by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fi ll the gap currently existing between basic research and clinical use of advanced diagnostics.
Keywords: cancer, biomarkers, targeted proteomics, validation.
Abbreviations: MS mass spectrometry; GO Genome Ontology.
IntroductionThe study of cancer biomarker proteins began in 1847 with the discovery by Henry Bence-Jones of what turned out, more than 100 years later, to be a tumor-produced free antibody light chain “Bence Jones protein” in the urine of a multiple myeloma patient (Bence-Jones 1847; Kyle 1994) where it was present in large quantities and could be revealed by simple heat denaturation. One hundred and 40 years later this protein was demonstrated to be present also in the serum (Sinclair et al. 1986), and in 1998 a routine immunodiagnostic test was approved by the FDA. Hormones produced by tumors were also detected early on (Chan and Sell 1999): adrenocorticotropic hormone (ACTH), calcitonin, and chorionic gonadotropin (hCG), for example, are elevated in specifi c cancer types, though not with the tumor specifi city of Bence-Jones proteins.
Unfortunately, the paradigm in which an overproduced tumor-specifi c protein can be easily detected as a marker of cancer has turned out to be the exception rather than the rule: in the nearly 160 years since Bence-Jones’ discovery, less than 10 proteins have progressed to the level of FDA-approved cancer diagnostic tests, and most of these lack ideal sensitivity and specifi city for cancer.
In recent years “… the emerging science of genomics and proteomics have generated a plethora of candidate cancer biomarkers” (Pritzker 2002). Unfortunately few of these markers immediately stand out as superior prognostic or diagnostic tools, and even fewer have been validated and approved. Several factors might account for the slow pace of advance in cancer biomarkers. On the one hand, available proteomics technology has limited power to detect low-abundance cancer biomarkers against the background of high-abundance plasma proteins, and many of the best markers may thus be missed until discovery technology improves. On the other hand, the capacity to verify and validate existing candidate markers (through rigorous testing in large sample sets from many diseases) is limited, and it is therefore possible that the required biomarkers have already been “discovered” but not yet validated. In this paper, we are concerned with the latter possibility, and specifi cally with the problem of selecting among the existing candidates those that are most promising for systematic validation.
This line of enquiry immediately raises the question: where is the list of known candidate cancer biomarkers? While a number of useful reviews and books discuss specifi c cancer markers with clinical
Correspondence: N. Leigh Anderson, P.O. Box: 53450, Washington DC, 20009-3450,Tel: (301) 728-1451; Fax: (202) 234-9175; Email: [email protected].
Biomarker Insights 2006:1 1– 48
2
Malu Polanski and N. Leigh Anderson
promise, these generally concentrate on proven, or at least well-developed, markers or specifi c disease states. We were unable to fi nd a list that draws together a large population of candidates at all stages of development from multiple discovery sources, and thus our fi rst step has been to create one through a combination of literature search and other methods.
The value of a list of existing candidates could be limited by the general lack of sensitivity and specifi city exhibited by most of the cancer markers found to date, a factor that may have discouraged others from undertaking this task previously. Most candidates that have been followed up in larger studies have shown poor diagnostic value (Table 1), and even those that have been approved for clinical use exhibit lower sensitivity and specifi city than the well-known markers of, eg, acute cardiovas-cular events (ie, troponin in myocardial infarction
or B-type natriuretic peptide in congestive heart failure, Table 1).
On the other hand, there seems to be a growing consensus that panels of markers may be able to supply the specifi city and sensitivity that individual markers lack. For example a panel combining four known biomarkers (leptin, prolactin, osteopontin, insulin-like growth factor II), none of which used alone could distinguish patients from the controls, achieved a sensitivity and specifi city of 95% for the diagnosis of ovarian cancer (Mor et al. 2005). In this case a combination of known proteins in a novel panel provided a signifi cant advance. Xiaoet al. identifi ed 299 proteins in tissue culture by 1-D page and nano-ESI-MS/MS but then used ELISA to test 13 of the most interesting in serum. They reported that CD98, fascin, the secreted chain of the polymeric immunoglobulin receptor and 14-3-3 eta provide greater sensitivity when used together
Table 1. Example sensitivities and specifi cities for the nine FDA approved cancer biomarkers.
Marker Disease Cut Off Sensitivity Specifi city ReferenceCEA malignant pleural effusion NA1 57.5% 78.6% (Li et al. 2003)CEA peritoneal cancer 0.5 ng/ml 75.8% 90.8% (Yamamto dissemination et al. 2004)Her-2/neu stage IV breast cancer 15 ng/mL 40% 98%2 (Cook et al. 2001)Bladder Tumor Antigen urothelial cell carcinoma NA 52.8% 70% (Mian et al. 2000)Thyro-globulin thyroid cancer metastasis 2.3 ng/ml3 74.5% 95% (Lima et al. 2002)Alpha-fetoprotein hepatocellular carcinoma 20 ng/ml 50% 70% (De Masi et al.2005)PSA prostate cancer 4.0 ng/mL 46% 91% (Gann et al. 1995)CA 125 non-small cell lung cancer 95 IU/mL 84% 80% (Dabrowska et al. 2004)CA19.9 pancreatic cancer NA 75% 80% (Yamaguchi et al. 2004)CA 15.3 breast cancer 40 U/ml 58.2% 96.0% (Ciambellotti et al. 1993)leptin, prolactin, ovarian cancer NA 95% 95% (Mor et al.osteopontin, and IGF-II 2005)CD98, fascin, sPIgR4, lung cancer NA 96% 77% (Xiao et al.and 14-3-3 eta 2005) Troponin I myocardial infarction 0.1 microg/L 93% 81% (Eggers et al.2004)B-type natriuretic Congestive heart failure 8 pg/mL 98% 92% (Dao et al.peptide 2001)1. Not available2. vs benign breast diseases 3. vs 3rd week post surgery4. Secreted chain of the polymeric immunoglobulin receptor
Biomarker Insights 2006:1
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Candidate Cancer Biomarkers
as a panel than any of the markers used alone (Xiao et al. 2005).
If, as we and others (Conrads et al. 2003) believe, panels of proteins provide the most promising avenue towards early and accurate cancer detection, then a re-examination of known candidates provides a logical approach to panel generation, with the expectation that a stream of new markers can be added as they are identifi ed by marker discovery studies. This candidate-based, or targeted, approach will require a comprehensive list of prioritized candidates coupled with a tech-nology able to assay these in large sets of plasma and serum samples from clinical and epidemio-logical studies (together a “biomarker pipeline” (Anderson 2005b)).
Here we have begun to compile and prioritize a database of candidate biomarkers reported to be differentially expressed in studies of human cancer. We have included changes observed either at the protein (plasma or tissue) or nucleic acid (tissue DNA or RNA) level for any cancer, and excluded results restricted to animal, cell culture systems, or single case report studies in hopes of focusing on the most promising clinical biomarker candidates. We hypothesize that the protein version of most, if not all of these markers should be detectable in blood plasma at some level, irrespective of the tissue source, ultimately allowing for their use in patient screening, diagnosis or follow-up.
Experimental Procedures
Search strategy The principal strategy for creation of our listinvolved compilation of designated cancer related proteins from: our previously published work(Anderson et al. 2004), PubMed literature searches, cancer microarrays (868 proteins from 111 hu-man cancer Superarrays (http://www.superarry.com and in supplemental material), CirculatingTumor Markers of the New Millennium (Wu 2002), American Association for Clinical Chemistry abstracts and general literature perusal. PubMed searches included de novo PubMed literature searches: [plasma (Title/Abstract) NOT membrane (Title/Abstract) NOT stimulation (Title/Abstract) NOT drug (Title/Abstract) NOT dose (Title/Ab-stract) AND protein (Title/Abstract) AND cancer] and [“cancer antigen” AND human], as well as the PubMed literature search used for proteins
from other sources [“protein name” AND cancer AND human AND (where necessary) diagnostic AND (where necessary) expression] and PubMed “related article” searches. Only proteins for which we found at least one published study on human cancer utilizing primary samples were retained (639 of the array proteins). Each biomarker refer-ence was then manually tabulated and curated as to disease and tissue (including plasma). Single case studies were excluded.
Clinical use dataFDA approval dates for tests were obtained from the FDA Center for Devices and Radiological Health database. Proteins designated here as clinical markers are those offered commercially by ARUP or by Mayo Medical Laboratories, or else offered for internal use by either NIH or the Fred Hutchinson Cancer Research Center.
Citation analysis Each documented protein on the resulting list was searched against the literature (via PubMed) us-ing the query [“protein name” AND human AND cancer AND diagnostic]. This is admittedly a crude metric of research interest in a biomarker, but provides a useful method of relative prioritization among markers. In tabulating citation frequen-cies we did not exclude those categories ruled out in compiling the list initially: studies of animal systems, single clinical cases, or cell lines. If the “protein name” was not found by this search strategy it was counted as zero. It must be noted that PubMed is not a static archive but rather con-stantly changing both by additions, subtractions, and redefinition of MeSH headings. Still this exercise allowed some relative ranking of interest and therefore importance. Total cancer citations per year were determined using the query [human AND cancer AND diagnostic] limited to a specifi c publication year.
Annotation Swiss-Prot/Uniprot accession numbers were obtained where possible. Most of the TrEMBL annotations were done prior to the addition of species information to the annotation number and so this form of the annotation was maintained. Candidate cancer biomarkers were annotated with GO numbers and IDs from EBI’s human GOA 30.0
Biomarker Insights 2006:1
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Malu Polanski and N. Leigh Anderson
(gene_association.goa_human, ftp://ftp.ebi.ac.uk/pub/databases) and the Gene Ontology’s GO.def version 1.213 (http://www.geneontology.org/ontol-ogy/GO.defs) respectively. Similar ID groupings were then combined. The entire Human GO fi le was treated in an identical fashion for comparison with the candidates.
Protein concentrationsWhere possible, normal or control values for the plasma concentration of each protein were obtained by literature search. Unless specifi cally noted, protein concentrations are for the intact protein not individual subunits.
ResultsA search strategy combining literature search, extraction from microarray data, and a review of existing clinical tests, followed by manual cura-tion, provided a list of 1261 candidate protein biomarkers (supplemental material) for which we found evidence of a quantitative change in some human cancer. As shown in Table 2, the candidates included proteins known to occur in plasma (274), proteins detected in tissue samples (542), and pro-teins whose corresponding mRNA or DNA levels were differentially expressed between cancerous and normal samples (656). These categories are non-exclusive in that a signifi cant number of the candidates were found in more than one type of study. Proteins detected in the plasma represent 22% of the total proteins documented to date.
Citation frequencyCitation frequency analysis was used as one method of prioritizing the biomarkers, on the assumption that proteins most widely studied in the context of cancer had more promise as biomarkers. Citation frequency was determined using a PubMed query intended to count citations in which the authors considered the proteins to have diagnostic value
(Figure 1, Table 3). When this is done, 29% of the 1,261 biomarkers have no such citations, 67% have fewer than 10, and 74% fewer than 20. Likewise only a very limited number of biomarkers have extensive citations, 62 proteins or only 5% of the total number of biomarkers were found to have greater than 500 citations.
Biomarkers with greater than 500 citationsOf the 34 biomarkers with more than 1000 citations (Figure 2, Table 3) 79% are found in the plasma and 56% are presently used clinically (89% of which are reported in plasma). Of the 28 markers with between 500 and 1000 citations (Figure 3) 57% are plasma proteins but only 7% are used clinically. Both of the markers used clinically are plasma proteins. Some proteins with high citation frequency (eg, albumin) are somewhat surprising to see in the context of cancer biomarkers; these have been retained nevertheless because they appear to have reasonable relevance (low serum albumin
Figure 1. Biomarker Citation Frequency. Citation Frequency for each protein was determined using the PubMed query [“protein name” AND human AND cancer AND diagnostic]. Proteins were then histogrammed in bins of 10, 100 and 1000 citations (for frequencies of n<100, 100<n<1000, and n>1000, respectively) and each bin’s count normalized through division by bin size (eg the count of proteins falling in the 11-20 citations bin was divided by 10).
Table 2. Distribution of cancer biomarkers. Other = amniotic, bile, cerebrospinal fl uid, follicular fl uid, milk of lactating women, pancreatic fl uid, seminal plasma, sputum, stools and urine.
1261 Unique proteins Proteins in plasma Tissue proteins DNA & RNA data OtherProteins in plasma 274 60 24 6Tissue proteins 60 542 152 6DNA & RNA data 24 152 656 3Other 6 6 3 15
Biomarker Insights 2006:1
5
Candidate Cancer Biomarkers
Concentration Reference
C
itatio
ns
Total >500
2004 >100
Plasma Conc Known in pg/ml
2004/Total x100 >50
Clinical Markers
Total # of √s
Available Antibody
Human Swiss Prot #
Control Plasma conc pg/ml
Prot
ein
Nam
es
C
omm
ents
Tabl
e 3.
Hig
h pr
iorit
y ca
ncer
mar
kers
. P
rote
ins
havi
ng >
500
tota
l cita
tions
, >10
0 ci
tatio
ns in
200
4, >
50%
200
4 ci
tatio
ns, a
kno
wn
plas
ma
conc
entra
tion
or u
sed
clin
ical
ly a
re li
sted
.
(Con
tinue
d)
Alp
ha-fe
topr
otei
n √
√
√ √
4 ye
s P
0277
1 2.
0E+0
4 (B
ened
uce
A p
regn
ancy
ass
ocia
ted
onco
feta
l pro
tein
et a
l. 20
04)
reex
pres
sed
in h
epat
ocel
lula
r can
cer,
cirr
hosi
s an
d he
patit
is (C
heem
a et
al.
2004
).
Car
cino
embr
yoni
c
√ √
√
√ 4
yes
P06
731
1.0E
+03
(Mav
ligit
and
A re
expr
esse
d on
co-fe
tal p
rote
in, C
EA
is
antig
en
E
stro
v 20
00)
curr
ently
in u
se in
col
orec
tal c
ance
r
(E
ngar
as e
t al.
diag
nosi
s ev
en th
ough
its
sens
itivi
ty c
an b
e
19
99)
parti
cula
rly lo
w in
the
initi
al s
tage
s (H
eptn
eret
al.
1984
).
Epi
derm
al g
row
th
√ √
√
√ 4
yes
P00
533
6.
9E+0
6 (B
aron
et a
l.
A m
embr
ane
tyro
sine
kin
ase
that
inhi
bits
fact
or re
cept
or
20
01)
apop
tosi
s an
d pr
omot
es a
ngio
gene
sis.
Fou
nd to
be
con
nect
ed w
ith in
crea
sed
mal
igna
ncy
(Jez
iors
ki e
t al.
2000
).
Kal
likre
in 3
√
√
√ √
4 ye
s P
0728
8
1.9E
+03
(Her
rman
n
PS
A hy
drol
yzes
the
high
mol
ecul
ar m
ass
(pro
stat
e sp
ecifi
c
et a
l. 20
04)
sem
inal
ves
icle
pro
tein
thus
lead
ing
to th
ean
tigen
)
(Ng
et a
l.
liqui
d fra
ctio
n of
the
sem
inal
coa
gulu
m
20
05)
It is
incr
ease
d in
men
with
pro
stat
e ca
ncer
(T
haku
r et a
l. 20
03).
Vasc
ular
√
√
√ √
4 ye
s P
1569
2
2.0E
+02
(Miy
ashi
ta
VE
GF
is a
pot
ent a
ngio
geni
c fa
ctor
. Ser
umen
doth
elia
l gro
wth
et a
l. 20
03)
leve
ls h
ave
been
det
ecte
d in
mel
anom
afa
ctor
A, V
EG
F
(U
gure
l et a
l. 20
01),
pitu
itary
(Kom
orow
ski e
t al.
20
00) a
nd c
olor
ecta
l car
cino
mas
(D
avie
s et
al.
2000
).
Biomarker Insights 2006:1
6
Malu Polanski and N. Leigh Anderson
Alb
umin
√
√
√
3 ye
s P
0276
8 4.
1E+1
0 (L
abor
ator
ies
A se
rum
pro
tein
resp
onsi
ble
for c
ollo
idal
2001
) os
mot
ic p
ress
ure
and
plas
ma
mol
ecul
e
trans
port.
It is
dec
reas
ed in
end
sta
ge re
nal
dise
ase(
Kay
sen
and
Kum
ar 2
003)
.
CA
125
√ √
√ 3
yes
x
(Woo
las
A
mon
oclo
nal a
ntib
ody
iden
tifi e
d ca
ncer
et a
l. 19
93)
antig
en th
at is
Ele
vate
d in
mos
t clin
ical
ly
(H
asho
lzne
r ad
vanc
ed o
varia
n ca
rcin
omas
and
whi
ch
et
al.
1994
) m
ay b
e el
evat
ed p
redi
agno
sis
CA
125
is a
po
tent
ially
use
ful f
or e
arly
det
ectio
n. H
owev
er,
C
A 12
5 is
not
alw
ays
elev
ated
in m
alig
nant
ca
ncer
and
can
be
elev
ated
in b
enig
n ov
aria
n
tum
ors
(McI
ntos
h et
al.
2004
).
Cal
cito
nin
√
√
√ 3
yes
P01
258
1.0E
+01
(Kar
anik
as
A th
yroi
d ho
rmon
e th
at lo
wer
s ca
lciu
m a
nd
e
t al.
2004
) ph
osph
ate
leve
ls a
nd in
hibi
ts b
one
reso
rptio
n,ca
lcito
nin
is u
sefu
l in
the
dete
ctio
n of
thyr
oid
ca
ncer
s ho
wev
er it
is a
lso
elev
ated
in
Has
him
oto’
s th
yroi
ditis
(Kar
anik
as e
t al.
2004
).
Chr
omog
rani
n A
√
√
√ 3
NF
P10
645
6.5E
+04
(Puj
ol e
t al.
A
neur
oend
ocrin
e se
cret
ory
prot
ein
secr
eted
(par
athy
roid
2003
) by
tum
ours
with
neu
roen
docr
ine
prop
ertie
s.se
cret
ory
prot
ein
1)
The
assa
y is
use
d pr
imar
ily in
the
diag
nosi
s an
d m
onito
ring
of p
atie
nts
with
tum
ours
of n
euro
en-
docr
ine
orig
in. I
ncre
ased
leve
ls in
sm
all c
ell l
ung
canc
er p
atie
nts
are
asso
ciat
ed w
ith s
horte
r sur
viva
l (P
ujol
et a
l. 20
03).
Cor
ticot
ropi
n-
√
√
√ 3
yes
P01
189
1.
1E+0
1 (W
alsh
et a
l.
Cor
itcot
ropi
n-lip
otro
pin
cont
ains
mel
anot
ropi
nlip
otro
pin
cont
ains
2005
) w
hich
incr
ease
s pi
gmen
tatio
n of
the
skin
and
A
CTH
A
CTH
whi
ch s
timul
ates
the
adre
nal g
land
s to
se-
cret
cor
tisol
. It i
s se
cret
ed b
y so
me
pitu
itary
tum
ors
(Cha
nson
and
Sal
enav
e 20
04).
Con
cent
ratio
n fo
r A
CTH
.
Est
roge
n re
cept
or 1
√
√
√
3 ye
s P
0337
2
The
estro
gen
rece
ptor
is a
ste
roid
rece
ptor
whi
ch
stim
ulat
es h
orm
one-
spec
ifi c
trans
crip
tion
of s
pecifi c
ge
nes.
Mos
t bre
ast c
ance
rs e
xpre
ss e
stro
gen
and
prog
este
rone
rece
ptor
(ER
alph
a an
d P
R) (
Cla
rke
et a
l. 20
05).
Gas
trin
√
√
√ 3
yes
P01
350
6.9E
+02
(Tria
ntafi
llid
is
A ho
rmon
e th
at s
timul
ates
HC
l sec
retio
n by
the
et a
l. 20
03)
gast
ric m
ucos
a, it
is in
crea
sed
in g
astri
c an
d co
lore
ctal
can
cer p
atie
nts
(Tria
ntafi
llid
is
et a
l. 20
03).
Pro
gest
eron
e re
cept
or
√ √
√ 3
yes
P06
401
Th
e pr
oges
tero
ne re
cept
or is
a s
tero
id re
cept
or
whi
ch s
timul
ates
hor
mon
e-sp
ecifi
c tra
nscr
iptio
n
Biomarker Insights 2006:1
7
Candidate Cancer Biomarkers
of s
pecifi c
gen
es. T
here
is a
loss
of e
xpre
ssio
n in
pr
osta
te c
ance
r tis
sue
(Ji e
t al.
2005
).
Pro
lact
in
√
√
√ 3
yes
P01
236
1.
6E+0
4 (A
l Sifr
i and
A
horm
one
that
stim
ulat
es a
nd s
usta
ins
Rae
f 200
4)
lact
atio
n M
ultip
le re
gres
sion
ana
lysi
s sh
owed
a
sign
ifi ca
nt c
orre
latio
n be
twee
n tu
mor
vol
ume
and
seru
m P
RL
leve
l in
prol
actin
oma
(Ma
et a
l. 20
02).
S10
0 al
pha
chai
n √
√
√
3 ye
s P
2329
7
9.0E
+01
(Tas
et a
l.
A ca
lciu
m b
indi
ng p
rote
in, S
100
has
been
2004
) de
scrib
ed a
s a
usef
ul tu
mor
mar
ker f
or m
alig
nant
m
elan
oma
(Tas
et a
l. 20
04).
Con
cent
ratio
n is
for
the
com
plex
pro
tein
.
Som
atos
tatin
√
√ √
3 N
F P
6127
8
2.0E
+01
(Ner
adilo
va
Som
atos
tatin
inhi
bits
sec
retio
n of
gro
wth
et a
l. 19
89)
horm
one,
insu
lin, g
luca
gon,
gas
trin
, cho
lecy
sto-
kini
n, s
ecre
tin a
nd v
asoa
ctiv
e in
test
inal
pep
tide
amon
g ot
hers
. It h
as b
een
dete
cted
in th
e se
ra o
f 14
-15%
of l
ung
canc
er p
atie
nts
alth
ough
tum
or c
ell
expr
essi
on a
ppea
rs ra
re (O
’Byr
ne e
t al.
2001
).
Thyr
oglo
bulin
√
√ √
3 ye
s P
0126
6
1.0E
+03
(Mon
tella
P
recu
rsor
to th
e th
yroi
d ho
rmon
es th
yrox
ine
et a
l. 20
04)
and
triio
doth
yron
ine
its le
vel i
n pl
asm
a is
use
d in
th
e m
anag
emen
t of t
hyro
id c
ance
r (W
hitle
y an
d A
in
2004
).
V-er
b-b2
, Her
2/ne
u √
√ √
3 ye
s P
0462
6
1.1E
+04
(Wu
2002
) A
n on
coge
ne p
rodu
ct w
hose
tiss
ue e
xpre
ssio
n an
d le
vels
of t
he s
hed
prot
ein
in s
erum
hav
e be
en
show
n to
cor
rela
te w
ith tu
mor
sta
ge in
a ra
nge
of
aden
ocar
cino
mas
(Tsi
gris
et a
l. 20
02).
Ant
igen
iden
tifi e
d by
√
√
2 N
F P
4601
3
A pr
olife
ratio
n-as
soci
ated
ant
igen
that
ism
onoc
lona
l ant
ibod
y
incr
ease
d in
sm
all c
ell l
ung
canc
er p
atie
nts
Ki-6
7
(G
refte
et a
l. 20
04).
B-c
ell
√ √
2
yes
P10
415
A
n in
hibi
tor o
f apo
ptos
is B
cl-2
mai
ntai
nsC
LL/ly
mph
oma
2
ho
meo
stas
is in
the
imm
une
syst
em T
he d
iffer
ing
ef-
fect
s of
Bcl
-2 e
xpre
ssio
n on
pro
gnos
is m
ay b
e du
e to
whi
ch c
ells
are
exp
ress
ing
the
Bcl
-2, i
mm
une
cells
or t
umor
s. H
igh
expr
essi
on in
ova
rian
canc
er
(Her
od e
t al.
1996
) and
non
sm
all l
ung
canc
er (S
hi-
bata
et a
l. 20
04) a
re a
ssoc
iate
d w
ith b
ette
r pro
gno-
sis
whe
reas
wel
l diff
eren
tiate
d tu
mor
s m
ore
likel
y to
be
Bcl
-2 p
ositi
ve (S
oda
et a
l. 19
99).
BC
L2-a
ssoc
iate
d √
√
2 ye
s Q
0781
2
B
ax is
an
apop
tosi
s in
hibi
tor h
ighl
yX
pro
tein
Q07
814
expr
esse
d in
Hod
gkin
’s d
isea
se
Q
0781
5
(S
chla
ifer e
t al.
1995
).
(Con
tinue
d)
Biomarker Insights 2006:1
8
Malu Polanski and N. Leigh Anderson
Bet
a-2-
√
√
2 ye
s P
6176
9
2.1E
+06
(Bie
n et
al.
Th
e no
npol
ymor
phic
cha
in o
f MH
C c
lass
mic
rogl
obul
in
20
04)
I mol
ecul
es. I
t is
slig
htly
incr
ease
d in
chi
ldre
n w
ith
acut
e le
ukem
ias
and
lym
phom
as b
ut n
ot in
sol
id
tum
or d
isor
ders
.
Bre
ast c
ance
r 1
√ √
2
yes
P38
398
Th
e B
RC
A1
prot
ein
is a
tum
or s
uppr
esso
rea
rly o
nset
th
at m
edia
tes
DN
A da
mag
e an
d re
pair,
tran
scrip
-tio
nal a
ctiv
ity a
nd c
hrom
osom
al s
tabi
lity.
How
ever
, w
hile
inhe
rited
mut
atio
ns o
f BR
CA
1 ar
e re
spon
sibl
e fo
r abo
ut 4
0-45
% o
f her
edita
ry b
reas
t can
cers
, th
ese
mut
atio
ns a
ccou
nt fo
r onl
y 2-
3% o
f all
brea
st
canc
ers
(Ros
en e
t al.
2003
).
CA
15.3
√
√
2 ye
s x
A m
onoc
lona
l ant
ibod
y id
entifi
ed
canc
er a
ntig
en
incr
ease
d in
pat
ient
s w
ith m
etas
tatic
bre
ast c
ance
r (L
ockh
art e
t al.
1999
).
CA
19.9
√
√
2 N
F x
A m
onoc
lona
l ant
ibod
y id
entifi
ed
canc
er a
ntig
en
incr
ease
d in
col
orec
tal c
ance
r pat
ient
s (L
ockh
art
et a
l. 19
99).
Cad
herin
1 ty
pe 1
√
√
2 ye
s P
1283
0
7.0E
+06
(Cha
n et
al.
E-c
adhe
rin, a
cel
l adh
esio
n pr
otei
n, p
lays
a ro
leE
-cad
herin
2001
) in
tiss
ue fo
rmat
ion
and
arch
itect
ure.
Ele
vate
d(e
pith
elia
l)
le
vels
of s
E-c
adhe
rin a
re fo
und
in s
era
of p
atie
nts
with
bla
dder
can
cer a
nd c
orre
late
with
kno
wn
prog
-no
stic
fact
ors.
(Griffi t
hs e
t al.
1996
).
Cas
pase
3
√ √
2
yes
P42
574
C
aspa
se 3
is in
volv
ed in
not
onl
y ap
opto
sis
exec
u-tio
n bu
t als
o pr
olife
ratio
n. It
has
bee
n sh
own
to
be d
ownr
egul
ated
in g
astri
c ly
mph
oma
tissu
e bu
t ne
gativ
ely
asso
ciat
ed w
ith ly
mph
nod
e m
etas
tase
s in
gas
tric
carc
inom
a (S
un e
t al.
2004
).
CD
44 a
ntig
en
√
√
2
yes
P16
070
2.
2E+0
5 (L
ockh
art
Cer
tain
CD
44 is
ofor
ms
that
regu
late
act
ivat
ion
et a
l. 19
99)
and
mig
ratio
n of
lym
phoc
ytes
and
mac
roph
ages
m
ay a
lso
enha
nce
loca
l gro
wth
and
met
asta
tic
spre
ad o
f tum
or c
ells
. Pre
sent
in s
erum
of n
orm
al
indi
vidu
als
it is
ele
vate
d in
the
seru
m fr
om g
as-
tric
and
colo
n ca
ncer
pat
ient
s, (G
uo e
t al.
1994
), H
odgk
in’s
lym
phom
a pa
tient
s(Lo
ckha
rt et
al.
1999
), an
d ac
ute
leuk
emia
pat
ient
s (Y
okot
a et
al.
1999
).
Cel
lula
r tum
or
√ √
2
yes
P04
637
Th
e p5
3 tu
mor
sup
pres
sor p
rote
in re
gula
tes
antig
en p
53
prol
ifera
tion,
cel
l cyc
le c
heck
poin
ts, a
nd a
popt
osis
. M
ore
than
one
hal
f of a
ll lu
ng c
ance
rs c
onta
in a
m
utat
ion
of th
e p5
3 tu
mor
sup
pres
sor g
ene
(Joh
nson
and
Kel
ley
1993
).
Biomarker Insights 2006:1