Analysis of apoptosis protein expression in early-stage colorectal cancer suggests opportunities for new prognostic biomarkers.
OBJECTIVE
Although most stage II colon cancers are potentially curable by surgery alone, approximately 20% of patients relapse, suggesting a need for establishing prognostic markers that can identify patients who may benefit from adjuvant chemotherapy. We tested the hypothesis that differences in expression of apoptosis-regulating proteins account for differences in clinical outcome among patients with early-stage colorectal cancer.


METHODS
Tissue microarray technology was employed to assay the expression of apoptosis-regulating proteins by immunohistochemistry in 106 archival stage II colorectal cancers, making correlations with disease-specific survival. The influence of microsatellite instability (MSI), tumor location (left versus right side), patient age, and gender was also examined.


RESULTS
Elevated expression of several apoptosis regulators significantly correlated with either shorter (cIAP2; TUCAN) or longer (Apaf1; Bcl-2) overall survival in univariate and multivariate analyses. These biomarkers retained prognostic significance when adjusting for MSI, tumor location, patient age, and gender. Moreover, certain combinations of apoptosis biomarkers were highly predictive of death risk from cancer. For example, 97% of patients with favorable tumor phenotype of cIAP2(low) plus TUCAN(low) were alive at 5 years compared with 60% of other patients (P = 0.00003). In contrast, only 37% of patients with adverse biomarkers (Apaf1(low) plus TUCAN(high)) survived compared with 83% of others at 5 years after diagnosis (P< 0.0001).


CONCLUSIONS
Immunohistochemical assays directed at detection of certain combinations of apoptosis proteins may provide prognostic information for patients with early-stage colorectal cancer, and therefore could help to identify patients who might benefit from adjuvant chemotherapy or who should be spared it.
Krajewska
Maryla
M
The Burnham Institute, Department of Family Preventive Medicine, University of California-San Diego, La Jolla, California, USA.
Kim
Hoguen
H
Kim
Chul
C
Kang
Haeyoun
H
Welsh
Kate
K
Matsuzawa
Shu-Ichi
S
Tsukamoto
Michelle
M
Thomas
Ronald G
RG
Assa-Munt
Nuria
N
Piao
Zhe
Z
Suzuki
Koichi
K
Perucho
Manuel
M
Krajewski
Stan
S
Reed
John C
JC
D000367:Age Factors; D017209:Apoptosis; D053477:Apoptotic Protease-Activating Factor 1; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000473:pathology; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D018895:Microsatellite Repeats; D015999:Multivariate Analysis; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011379:Prognosis; D016016:Proportional Hazards Models; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012189:Retrospective Studies; D012737:Sex Factors; D013997:Time Factors; D014018:Tissue Distribution; D016896:Treatment Outcome
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D015415:Biomarkers; D014408:Biomarkers, Tumor; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2