Serial analysis of gene expression identifies connective tissue growth factor expression as a prognostic biomarker in gallbladder cancer.
BACKGROUND
Gallbladder cancer (GBC) is an uncommon neoplasm in the United States, but one with high mortality rates. This malignancy remains largely understudied at the molecular level such that few targeted therapies or predictive biomarkers exist.


METHODS
We built the first series of serial analysis of gene expression (SAGE) libraries from GBC and nonneoplastic gallbladder mucosa, composed of 21-bp long-SAGE tags. SAGE libraries were generated from three stage-matched GBC patients (representing Hispanic/Latino, Native American, and Caucasian ethnicities, respectively) and one histologically alithiasic gallbladder. Real-time quantitative PCR was done on microdissected epithelium from five matched GBC and corresponding nonneoplastic gallbladder mucosa. Immunohistochemical analysis was done on a panel of 182 archival GBC in high-throughput tissue microarray format.


RESULTS
SAGE tags corresponding to connective tissue growth factor (CTGF) transcripts were identified as differentially overexpressed in all pairwise comparisons of GBC (P < 0.001). Real-time quantitative PCR confirmed significant overexpression of CTGF transcripts in microdissected primary GBC (P < 0.05), but not in metastatic GBC, compared with nonneoplastic gallbladder epithelium. By immunohistochemistry, 66 of 182 (36%) GBC had high CTGF antigen labeling, which was significantly associated with better survival on univariate analysis (P = 0.0069, log-rank test).


CONCLUSIONS
An unbiased analysis of the GBC transcriptome by SAGE has identified CTGF expression as a predictive biomarker of favorable prognosis in this malignancy. The SAGE libraries from GBC and nonneoplastic gallbladder mucosa are publicly available at the Cancer Genome Anatomy Project web site and should facilitate much needed research into this lethal neoplasm.
Alvarez
Hector
H
Department of Pathology, Pontificia Universidad Católica de Chile, Santiago, Chile.
Corvalan
Alejandro
A
Roa
Juan C
JC
Argani
Pedram
P
Murillo
Francisco
F
Edwards
Jennifer
J
Beaty
Robert
R
Feldmann
Georg
G
Hong
Seung-Mo
SM
Mullendore
Michael
M
Roa
Ivan
I
Ibañez
Luis
L
Pimentel
Fernando
F
Diaz
Alfonso
A
Riggins
Gregory J
GJ
Maitra
Anirban
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D019295:Computational Biology; D055513:Connective Tissue Growth Factor; D005006:Ethnicity / Q000235:genetics; D005260:Female; D005704:Gallbladder / Q000378:metabolism; D005706:Gallbladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D012044:Regression Analysis; D046888:Tissue Array Analysis
D014408:Biomarkers, Tumor; C526317:CCN2 protein, human; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D055513:Connective Tissue Growth Factor