REVIEW ARTICLE
a
-enolase: a promising therapeutic and diagnostic tumor
target
Michela Capello, Sammy Ferri-Borgogno, Paola Cappello and Francesco Novelli
Department of Medicine and Experimental Oncology, Center for Experimental Research and Medical Studies (CeRMS), San Giovanni Battista
Hospital, University of Turin, Italy
Introduction
Enolase is a metalloenzyme that catalyzes the dehydra-
tion of 2-phospho-d-glycerate to phosphoenolpyruvate
in the second half of the glycolytic pathway. In the
reverse reaction (anabolic pathway), which occurs dur-
ing gluconeogenesis, the enzyme catalyzes the hydra-
tion of phosphoenolpyruvate to 2-phospho-d-glycerate
[1,2]. Enolase is found from archaebacteria to mam-
mals, and its sequence is highly conserved [3]. In mam-
mals, three genes, ENO1, ENO2 and ENO3 encode for
three isoforms of the enzyme, a-enolase (ENOA),
c-enolase and b-enolase, respectively, with high
sequence identity [4–6]. The expression of these iso-
forms is tissue specific: ENOA is present in almost all
adult tissues, b-enolase is expressed in muscle tissues
and c-enolase is found in neurons and neuroendocrine
tissues [1,7–9]. The monomer of ENOA consists of a
smaller N-terminal domain (residues 1–133) and a lar-
ger C-terminal domain (residues 141–431). In eukarya,
enzymatically active enolase consists of a dimeric form
in which two subunits face each other in an antiparal-
lel manner [1,10]; some eubacterial enolases, by con-
trast, are octameric [11]. Enolase can form homo- or
heterodimers, such as aa, ab, bb, ac and cc [1].

value in cancer. This review will discuss recent information on the
biochemical, proteomics and immunological characterization of ENOA,
particularly its ability to trigger a specific humoral and cellular immune
response. In our opinion, this information can pave the way for effective
new therapeutic and diagnostic strategies to counteract the growth of the
most aggressive human disease.
Abbreviations
EGFR, epidermal growth factor receptor; ENOA, a-enolase; ERK, extracellular signal-regulated kinase; MBP-1, c-myc promoter-binding
protein; MHC, major histocompatibility complex; MMP, matrix metalloproteinase; PAI-1, plasminogen activator inhibitor-1; PTM, post-
translational modification; TAA, tumor-associated antigen; tPA, tissue-type plasminogen activator; uPA, urokinase-type plasminogen activator;
uPAR, urokinase-type plasminogen activator receptor.
1064 FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS
first 96 residues of ENOA and localizes in the nucleus,
where it binds to the c-myc P2 promoter and acts as a
transcription repressor, leading to tumor suppression
[25–27]. ENOA associates with MBP-1 in the tran-
scriptional regulation of the oncogene c-myc [28].
ENOA is a surface plasminogen-binding
receptor in tumors
In breast, lung and pancreatic neoplasia, ENOA is
localized on the surface of cancer cells [29–31], whereas
in melanoma and nonsmall cell lung carcinoma cells it
can also be secreted by exosomes [32,33]. How ENOA
is displayed on the cell surface remains unknown.
Many glycolytic enzymes and cytosolic proteins that
lack N-terminal signal peptide reach the surface of
eukaryotic cells [34]. In mammal cells, some export
routes of unconventional protein secretion have been
postulated: membrane blebbing, membrane flip-flop,
endosomal recycling or a plasma membrane trans-

MMP3) [47–50]. Binding of plasminogen to the cell
surface has profibrinolytic consequences: enhancement
of plasminogen activation, protection of plasmin from
its inhibitor a
2
-antiplasmin and enhancement of the
proteolytic activity of cell-bound plasmin [13,51]. Pro-
teolysis mediated by cell-associated plasmin contributes
to both physiological processes, such as tissue remodel-
ing and embryogenesis, and to pathophysiological
processes, such as cell invasion, metastasis and inflam-
matory response [19,45]. A noteworthy positive corre-
lation exists between elevated levels of plasminogen
activation and malignancy [46,52]. Higher expression
levels of uPA and ⁄ or plasminogen activator inhibitor-1
(PAI-1) in tumor tissues correlate with aggressiveness
and poor prognosis. ENOA takes part, together with
urokinase plasminogen activator receptor (uPAR),
integrins and some cytoskeletal proteins, in a multipro-
tein complex, called metastasome, responsible for
adhesion, migration and proliferation in ovarian can-
cer cells [53]. In human follicular thyroid carcinoma
cells, retinoic acid causes a decrease in ENOA levels
that coincides with their reduced motility [54], and cell
surface ENOA is enhanced in breast cancer cells ren-
dered superinvasive following paclitaxel treatment [55].
In pancreatic cancer patients, deregulated expression
of many proteins involved in the plasminogen pro-fibri-
nolytic cascade (annexin A2, PAI-2, uPA, uPAR, MMP-
1 and MMP-10) correlates with survival [56–59]. In the

system [66–68]. The immune response against such
immunogenic epitopes of TAAs induces the production
of autoantibodies as serological biomarkers for cancers
[70]. Both its overexpression in tumors and its ability
to induce a humoral and ⁄ or cellular immune response
in cancer patients classify ENOA as a true TAA.
ENOA expression is increased in
tumors
The overexpression of ENOA is associated with tumor
development through a process known as aerobic gly-
colysis or the Warburg effect [71]. Warburg observed
that cancer cells consume more glucose than normal
cells and generate ATP by converting pyruvate to lac-
tic acid, even in the presence of a normal oxygen sup-
ply [72]. The mechanism of the Warburg effect was
uncertain until the recent identification of upregulation
of glycolytic enzymes by hypoxia-inducible factor.
When a solid tumor exceeds 1 mm
3
, its cells face hyp-
oxic stress due to slow angiogenesis [73,74]. Because
the ENO1 promoter contains a hypoxia responsive ele-
ment [75,76], ENOA is upregulated at the mRNA
and ⁄ or protein level in several tumors, including brain
[77], breast [78–83], cervix [77,84,85], colon [77,86,87],
eye [77], gastric [77,88,89], head and neck [90,91], kid-
ney [77], leukemia [92], liver [77,93,94], lung [77,95–99],
muscle [77], ovary [77,100], pancreas [29,77,101,102],
prostate [77,103], skin [104] and testis [77] (Table 1).
Results from a bioinformatic study support a correla-

Breast m (68%), p, e (100%) [78–83] Ab [69,125] DP, DFI, M [69,78]
Cervix m, p [77,84,85]
Colon m, p [77,86,87]
Eye m [77]
Gastric m (73%), p [77,88,89]
Head and neck m (68%), p [90,91] Ab (79%) [91,123,124], T [131,132] OS, PFS [91]
Kidney m [77]
Leukemia p (> 50%) [92] Ab (33–86%) [120,121]
Liver m, p (17–80%) [77,93,94] M [93,94]
Lung m, p (79–100%) [77,95–99] Ab (7–80%) [30,69,96,99,126–129] DP, OS, PFS [69,99]
Muscle m [77]
Ovary m, p [77,100]
Pancreas m (100%), p (82–90%) [29,77,101,102] Ab (62%) [119], T [29] OS, PFS [119]
Prostate m, p (100%) [77,103]
Skin m [104] Ab (38–100%) [104,122]
Testis m [77]
Percentages indicate the reported frequencies of enhanced ENOA mRNA, protein and enzymatic activity or the frequencies of anti-ENOA Ig.
m, mRNA; p, protein; e, enzymatic activity; Ab, antibody production; T, T cell response; DP, disease progression; DFI, disease-free interval;
M, malignancy; OS, overall survival; PFS, progression-free survival.
a-enolase in tumor diagnosis and therapy M. Capello et al.
1066 FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS
Table 2. ENOA PTMs in normal and cancer tissues. Asp, aspartate; Glu, glutamate; Lys, lysine; Ser, serine; Thr, threonine; Tyr, tyrosine; numbers refer to the position of each residue in
the ENOA amino acid sequence.
Cell type
Acetylation Methylation Phosphorylation
Reference
Residue Position Residue Position Residue Position
Embryonic kidney Tyr 57 111
Ser 63
Normal pancreas Lys 64, 71, 80, 81, 89, 92, 126, 193,

three in leukemia. The only acetylated serine identified
is specific for colon cancer (Table 2).
Methylation has been assessed in normal and tumor-
al pancreas only. Twenty-four aspartate and glutamate
residues were found in both cell types. However, five
aspartates and five glutamates are specifically methy-
lated only in pancreatic cancer (Table 2).
Phosphorylation is the PTM that displays the most
specific pattern in each cell line. Two serine and one
threonine residues were specifically found in cervix
cancer, one threonine and one serine in embryonic kid-
ney, three serines and two threonines in leukemia;
whereas two tyrosine residues were found in both leu-
kemia and lung cancer and one serine in both tumoral
and normal pancreas.
ENOA in tumor cells is subjected to more acetyla-
tion, methylation and phoshorylation than in normal
tissues, indicating that many PTMs are associated with
cancer development and some are specific for each
kind of tissue or cancer. This can reflect the specific
activation of pro-mitogenic signaling pathways in
tumor cells. In many cases, PTMs regulate the stability
and functions of proteins; for example, in metabolic
enzymes, acetylation acts as an on ⁄ off switch mecha-
nism [116], whereas methylation on carboxylate side-
chains enhances hydrophobicity by increasing the affin-
ity of proteins for phospholipids [115]. We speculate
that PTMs are important mechanisms in the regulation
of ENOA functions, localization and immunogenicity.
ENOA induces a specific immune

dependent on cytokines released by CD4
+
T cells [118].
This coordinated immune response suggests that IgGs
against TAA are not only a diagnostic tool, but also
allow the selection of TAAs for cancer immunotherapy.
In many cancer patients, including pancreatic [119],
leukemia [120,121], melanoma [104,122], head and neck
[91,123,124], breast [69,125] and lung [30,69,96,99,
126–129], ENOA has been shown to induce autoanti-
body production (Table 1). In pancreatic cancer
patients, autoantibodies to ENOA are directed against
two upregulated isoforms phosphorylated in Ser 419
[115,119] (Table 2). Protein phosphorylation increases
the affinity of peptides for MHC molecules that can be
recognized by T cells [130].
In pancreatic cancer, ENOA elicits a CD4
+
and
CD8
+
T cell response both in vitro and in vivo [29].
Anti-MHC class I Ig inhibited the cytotoxic activity of
ENOA-stimulated CD8
+
T cell against pancreatic
tumor cells, but no MHC class I restricted peptide of
ENOA has been identified so far. Moreover, in pancre-
atic ductal adenocarcinoma patients, production of
anti-ENOA IgG is correlated with the ability of T cells

and overall survival, supporting the clinical significance
of phosphorylated ENOA autoantibodies [119].
The concept that autoantibody levels can also function
as markers for the diagnosis and prognosis of cancers
has been extensively pursued [69,133].
a-enolase in tumor diagnosis and therapy M. Capello et al.
1068 FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS
Conclusions
Taken as a whole, these findings illustrate the multi-
functional properties of ENOA in tumorigenesis, and
its key implications in cancer proliferation, invasion
and immune response. In cancer cells, ENOA is overex-
pressed and localizes on their surface, where it acts as a
key protein in tumor metastasis, promoting cellular
metabolism in anaerobic conditions and driving tumor
invasion through plasminogen activation and extracel-
lular matrix degradation. It also displays a characteris-
tic pattern of PTMs, namely acetylation, methylation
and phosphorylation, that regulate protein functions
and immunogenicity. In several kinds of tumor,
patients develop an integrated response of CD4
+
,
CD8
+
T cells and B cells against ENOA, together with
anti-ENOA autoantibodies in their sera. Clinical corre-
lations propose ENOA as a novel target for cancer
immunotherapy. In pancreatic cancer, for example, the
pancreas-specific Ser 419 phosphorylated ENOA is

5 Feo S, Oliva D, Barbieri G, Xu WM, Fried M & Giall-
ongo A (1990) The gene for the muscle-specific enolase
is on the short arm of human chromosome 17. Genom-
ics 6, 192–194.
6 Rider CC & Taylor CB (1975) Enolase isoenzymes. II.
Hybridization studies, developmental and phylogenetic
aspects. Biochim Biophys Acta 405, 175–187.
7 Fletcher L, Rider CC & Taylor CB (1976) Enolase
isoenzymes. III. Chromatographic and immunological
characteristics of rat brain enolase. Biochim Biophys
Acta 452, 245–252.
8 Fletcher L, Rider CC, Taylor CB, Adamson ED, Luke
BM & Graham CF (1978) Enolase isoenzymes as
markers of differentiation in teratocarcinoma cells and
normal tissues of mouse. Dev Biol 65, 462–475.
9 Marangos PJ, Zis AP, Clark RL & Goodwin FK
(1978) Neuronal, non-neuronal and hybrid forms of
enolase in brain: structural, immunological and func-
tional comparisons. Brain Res 150, 117–133.
Unphosphorylated
ENOA
Phosphorylated
ENOA
Auto-antibodies against
phosphorylated ENOA
Pancreatic cancer
cell
Non-pancreatic cancer
cell
Pancreatic ductal

binding to cells. Eur J Biochem 227, 407–415.
15 Pancholi V & Fischetti VA (1998) alpha-enolase, a
novel strong plasmin(ogen) binding protein on the sur-
face of pathogenic streptococci. J Biol Chem 273,
14503–14515.
16 Sundstrom P & Aliaga GR (1992) Molecular cloning
of cDNA and analysis of protein secondary structure
of Candida albicans enolase, an abundant, immuno-
dominant glycolytic enzyme. J Bacteriol 174, 6789–
6799.
17 Pal-Bhowmick I, Mehta M, Coppens I, Sharma S &
Jarori GK (2007) Protective properties and surface
localization of Plasmodium falciparum enolase. Infect
Immun 75, 5500–5508.
18 Felez J, Chanquia CJ, Fabregas P, Plow EF & Miles LA
(1993) Competition between plasminogen and tissue
plasminogen activator for cellular binding sites. Blood
82, 2433–2441.
19 Lopez-Alemany R, Longstaff C, Hawley S, Mirshahi M,
Fabregas P, Jardi M, Merton E, Miles LA & Felez J
(2003) Inhibition of cell surface mediated plasminogen
activation by a monoclonal antibody against alpha-eno-
lase. Am J Hematol 72, 234–242.
20 Moscato S, Pratesi F, Sabbatini A, Chimenti D, Scav-
uzzo M, Passatino R, Bombardieri S, Giallongo A &
Migliorini P (2000) Surface expression of a glycolytic
enzyme, alpha-enolase, recognized by autoantibodies in
connective tissue disorders. Eur J Immunol 30, 3575–
3584.
21 Wygrecka M, Marsh LM, Morty RE, Henneke I,

protein NS1-BP interacts with alpha-enolase ⁄ MBP-1
and is involved in c-Myc gene transcriptional control.
Biochim Biophys Acta 1773, 1774–1785.
29 Cappello P, Tomaino B, Chiarle R, Ceruti P,
Novarino A, Castagnoli C, Migliorini P, Perconti G,
Giallongo A, Milella M et al. (2009) An integrated
humoral and cellular response is elicited in pancreatic
cancer by alpha-enolase, a novel pancreatic ductal
adenocarcinoma-associated antigen. Int J Cancer 125,
639–648.
30 He P, Naka T, Serada S, Fujimoto M, Tanaka T,
Hashimoto S, Shima Y, Yamadori T, Suzuki H,
Hirashima T et al. (2007) Proteomics-based identifica-
tion of alpha-enolase as a tumor antigen in non-small
lung cancer. Cancer Sci 98, 1234–1240.
31 Seweryn E, Pietkiewicz J, Bednarz-Misa IS, Ceremuga I,
Saczko J, Kulbacka J & Gamian A (2009) Localization
of enolase in the subfractions of a breast cancer cell line.
Z Naturforsch C 64, 754–758.
32 Mears R, Craven RA, Hanrahan S, Totty N,
Upton C, Young SL, Patel P, Selby PJ & Banks RE
(2004) Proteomic analysis of melanoma-derived
exosomes by two-dimensional polyacrylamide gel
electrophoresis and mass spectrometry. Proteomics 4,
4019–4031.
33 Yu X, Harris SL & Levine AJ (2006) The regulation of
exosome secretion: a novel function of the p53 protein.
Cancer Res 66, 4795–4801.
34 Maxwell CA, McCarthy J & Turley E (2008) Cell-
surface and mitotic-spindle RHAMM: moonlighting or

J Biol Chem 272, 5718–5726.
42 Winram SB & Lottenberg R (1996) The plasmin-bind-
ing protein Plr of group A streptococci is identified as
glyceraldehyde-3-phosphate dehydrogenase. Microbiol-
ogy 142(Pt 8), 2311–2320.
43 Kassam G, Choi KS, Ghuman J, Kang HM, Fitzpa-
trick SL, Zackson T, Zackson S, Toba M, Shinomiya
A & Waisman DM (1998) The role of annexin II tetra-
mer in the activation of plasminogen. J Biol Chem 273,
4790–4799.
44 Das R, Burke T & Plow EF (2007) Histone H2B as a
functionally important plasminogen receptor on macro-
phages. Blood 110, 3763–3772.
45 Felez J (1998) Plasminogen binding to cell surfaces.
Fibrinolysis Proteolysis 12, 183–189.
46 Andreasen PA, Egelund R & Petersen HH (2000) The
plasminogen activation system in tumor growth, inva-
sion, and metastasis. Cell Mol Life Sci 57, 25–40.
47 Lijnen HR, Van Hoef B, Lupu F, Moons L, Car-
meliet P & Collen D (1998) Function of the plasmino-
gen ⁄ plasmin and matrix metalloproteinase systems
after vascular injury in mice with targeted inactivation
of fibrinolytic system genes. Arterioscler Thromb Vasc
Biol 18, 1035–1045.
48 Plow EF, Felez J & Miles LA (1991) Cellular regula-
tion of fibrinolysis. Thromb Haemost 66, 32–36.
49 Sato H, Takino T, Okada Y, Cao J, Shinagawa A,
Yamamoto E & Seiki M (1994) A matrix metallopro-
teinase expressed on the surface of invasive tumour
cells. Nature 370, 61–65.

metalloproteinase inducer up-regulates the urokinase-
type plasminogen activator system promoting tumor
cell invasion. Cancer Res 67 , 9–15.
58 Siren V, Salmenpera P, Kankuri E, Bizik J, Sorsa T,
Tervahartiala T & Vaheri A (2006) Cell-cell contact
activation of fibroblasts increases the expression of
matrix metalloproteinases. Ann Med 38, 212–220.
59 Smith R, Xue A, Gill A, Scarlett C, Saxby A, Clarkson A
& Hugh T (2007) High expression of plasminogen
activator inhibitor-2 (PAI-2) is a predictor of improved
survival in patients with pancreatic adenocarcinoma.
World J Surg 31, 493–502.
60 Hurtado M, Lozano JJ, Castellanos E, Lopez-
Fernandez LA, Harshman K, Martinez AC, Ortiz AR,
Thomson TM & Paciucci R (2007) Activation of the
epidermal growth factor signalling pathway by tissue
plasminogen activator in pancreas cancer cells. Gut 56,
1266–1274.
61 Ortiz-Zapater E, Peiro S, Roda O, Corominas JM,
Aguilar S, Ampurdanes C, Real FX & Navarro P
(2007) Tissue plasminogen activator induces pancre-
atic cancer cell proliferation by a non-catalytic mech-
anism that requires extracellular signal-regulated
M. Capello et al. a-enolase in tumor diagnosis and therapy
FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS 1071
kinase 1 ⁄ 2 activation through epidermal growth fac-
tor receptor and annexin A2. Am J Pathol 170,
1573–1584.
62 Roda O, Chiva C, Espuna G, Gabius HJ, Real FX,
Navarro P & Andreu D (2006) A proteomic approach

71 Warburg O (1930) The Metabolism of Tumours. Con-
stable, London.
72 Vander Heiden MG, Cantley LC & Thompson CB
(2009) Understanding the Warburg effect: the meta-
bolic requirements of cell proliferation. Science 324,
1029–1033.
73 Brown JM & Giaccia AJ (1998) The unique physiology
of solid tumors: opportunities (and problems) for can-
cer therapy. Cancer Res 58, 1408–1416.
74 Lu Z & Sack MN (2008) ATF-1 is a hypoxia-respon-
sive transcriptional activator of skeletal muscle mito-
chondrial-uncoupling protein 3. J Biol Chem 283,
23410–23418.
75 Sedoris KC, Thomas SD & Miller DM (2010) Hypoxia
induces differential translation of enolase ⁄ MBP-1.
BMC Cancer 10, 157.
76 Semenza GL, Jiang BH, Leung SW, Passantino R,
Concordet JP, Maire P & Giallongo A (1996) Hypoxia
response elements in the aldolase A, enolase 1, and lac-
tate dehydrogenase A gene promoters contain essential
binding sites for hypoxia-inducible factor 1. J Biol
Chem 271, 32529–32537.
77 Altenberg B & Greulich KO (2004) Genes of glycolysis
are ubiquitously overexpressed in 24 cancer classes.
Genomics 84, 1014–1020.
78 Tu SH, Chang CC, Chen CS, Tam KW, Wang YJ,
Lee CH, Lin HW, Cheng TC, Huang CS, Chu JS et al.
(2010) Increased expression of enolase alpha in human
breast cancer confers tamoxifen resistance in human
breast cancer cells. Breast Cancer Res Treat 121,

patients. Cancer Res Treat 38, 99–107.
85 Bae SM, Lee CH, Cho YL, Nam KH, Kim YW, Kim
CK, Han BD, Lee YJ, Chun HJ & Ahn WS (2005)
Two-dimensional gel analysis of protein expression
profile in squamous cervical cancer patients. Gynecol
Oncol 99, 26–35.
86 Katayama M, Nakano H, Ishiuchi A, Wu W, Oshima
R, Sakurai J, Nishikawa H, Yamaguchi S & Otsubo T
(2006) Protein pattern difference in the colon cancer
cell lines examined by two-dimensional differential in-
gel electrophoresis and mass spectrometry. Surg Today
36, 1085–1093.
87 Wong CS, Wong VW, Chan CM, Ma BB, Hui EP,
Wong MC, Lam MY, Au TC, Chan WH, Cheuk W
et al. (2008) Identification of 5-fluorouracil response
a-enolase in tumor diagnosis and therapy M. Capello et al.
1072 FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS
proteins in colorectal carcinoma cell line SW480 by
two-dimensional electrophoresis and MALDI-TOF
mass spectrometry. Oncol Rep 20, 89–98.
88 Qi Y, Chiu JF, Wang L, Kwong DL & He QY (2005)
Comparative proteomic analysis of esophageal squa-
mous cell carcinoma. Proteomics 5, 2960–2971.
89 Zhao J, Chang AC, Li C, Shedden KA, Thomas DG,
Misek DE, Manoharan AP, Giordano TJ, Beer DG &
Lubman DM (2007) Comparative proteomics analysis
of Barrett metaplasia and esophageal adenocarcinoma
using two-dimensional liquid mass mapping. Mol Cell
Proteomics 6, 987–999.
90 Govekar RB, D’Cruz AK, Alok Pathak K, Agarwal J,

KY, Park KS, Paik YK & Chang J (2004) Proteomic
analysis distinguishes basaloid carcinoma as a distinct
subtype of nonsmall cell lung carcinoma. Proteomics 4,
3394–3400.
96 Li C, Xiao Z, Chen Z, Zhang X, Li J, Wu X, Li X, Yi H,
Li M, Zhu G et al. (2006) Proteome analysis of human
lung squamous carcinoma. Proteomics 6, 547–558.
97 Huang LJ, Chen SX, Luo WJ, Jiang HH, Zhang PF &
Yi H (2006) Proteomic analysis of secreted proteins of
non-small cell lung cancer. Ai Zheng 25, 1361–1367.
98 Rubporn A, Srisomsap C, Subhasitanont P, Chokchai-
chamnankit D, Chiablaem K, Svasti J & Sangvanich P
(2009) Comparative proteomic analysis of lung cancer
cell line and lung fibroblast cell line. Cancer Genomics
Proteomics 6, 229–237.
99 Chang GC, Liu KJ, Hsieh CL, Hu TS, Charoenfupra-
sert S, Liu HK, Luh KT, Hsu LH, Wu CW, Ting CC
et al. (2006) Identification of alpha-enolase as an auto-
antigen in lung cancer: its overexpression is associated
with clinical outcomes. Clin Cancer Res 12, 5746–5754.
100 Cao L, Li X, Zhang Y, Peng F, Yi H, Xu Y & Wang
Q (2010) Proteomic analysis of human ovarian cancer
paclitaxel-resistant cell lines. Zhong Nan Da Xue Xue
Bao Yi Xue Ban 35, 286–294.
101 Shen J, Person MD, Zhu J, Abbruzzese JL & Li D
(2004) Protein expression profiles in pancreatic adeno-
carcinoma compared with normal pancreatic tissue and
tissue affected by pancreatitis as detected by two-
dimensional gel electrophoresis and mass spectrometry.
Cancer Res 64

840.
108 Mayya V, Lundgren DH, Hwang SI, Rezaul K, Wu L,
Eng JK, Rodionov V & Han DK (2009) Quantitative
phosphoproteomic analysis of T cell receptor signaling
reveals system-wide modulation of protein-protein
interactions. Sci Signal 2, ra46.
109 Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek
EJ, Zhang H, Zha XM, Polakiewicz RD & Comb MJ
M. Capello et al. a-enolase in tumor diagnosis and therapy
FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS 1073
(2005) Immunoaffinity profiling of tyrosine phosphory-
lation in cancer cells. Nat Biotechnol 23, 94–101.
110 Rikova K, Guo A, Zeng Q, Possemato A, Yu J, Haack
H, Nardone J, Lee K, Reeves C, Li Y et al. (2007)
Global survey of phosphotyrosine signaling identifies
oncogenic kinases in lung cancer. Cell 131, 1190–1203.
111 Molina H, Horn DM, Tang N, Mathivanan S & Pan-
dey A (2007) Global proteomic profiling of phospho-
peptides using electron transfer dissociation tandem
mass spectrometry. Proc Natl Acad Sci USA 104,
2199–2204.
112 Kim SC, Sprung R, Chen Y, Xu Y, Ball H, Pei J,
Cheng T, Kho Y, Xiao H, Xiao L et al. (2006) Sub-
strate and functional diversity of lysine acetylation
revealed by a proteomics survey. Mol Cell 23, 607–618.
113 Yu LR, Zhu Z, Chan KC, Issaq HJ, Dimitrov DS &
Veenstra TD (2007) Improved titanium dioxide enrich-
ment of phosphopeptides from HeLa cells and high
confident phosphopeptide identification by cross-vali-
dation of MS ⁄ MS and MS ⁄ MS ⁄ MS spectra. J Prote-

Cell Proteomics 4, 1718–1724.
121 Zou L, Wu Y, Pei L, Zhong D, Gen M, Zhao T, Wu
J, Ni B, Mou Z, Han J et al. (2005) Identification of
leukemia-associated antigens in chronic myeloid leuke-
mia by proteomic analysis. Leuk Res 29, 1387–1391.
122 Forgber M, Trefzer U, Sterry W & Walden P (2009)
Proteome serological determination of tumor-associ-
ated antigens in melanoma. PLoS ONE 4, e5199.
123 Shukla S, Govekar RB, Sirdeshmukh R, Sundaram
CS, D’Cruz AK, Pathak KA, Kane SV & Zingde SM
(2007) Tumor antigens eliciting autoantibody response
in cancer of gingivo-buccal complex. Proteomics Clin
Appl 1, 1592–1604.
124 Shukla S, Pranay A, D’Cruz AK, Chaturvedi P, Kane
SV & Zingde SM (2009) Immunoproteomics reveals
that cancer of the tongue and the gingivobuccal com-
plex exhibit differential autoantibody response. Cancer
Biomark 5, 127–135.
125 Ejma M, Misiuk-Hojlo M, Gorczyca WA, Podemski
R, Szymaniec S, Kuropatwa M, Rogozinska-Szczepka
J & Bartnik W (2008) Antibodies to 46-kDa retinal
antigen in a patient with breast carcinoma and cancer-
associated retinopathy. Breast Cancer Res Treat 110,
269–271.
126 Jankowska R, Witkowska D, Porebska I, Kuropatwa
M, Kurowska E & Gorczyca WA (2004) Serum anti-
bodies to retinal antigens in lung cancer and sarcoido-
sis. Pathobiology 71, 323–328.
127 Nakanishi T, Takeuchi T, Ueda K, Murao H & Shi-
mizu A (2006) Detection of eight antibodies in cancer

a-enolase in tumor diagnosis and therapy M. Capello et al.
1074 FEBS Journal 278 (2011) 1064–1074 ª 2011 The Authors Journal compilation ª 2011 FEBS