Diffuse expression of RNA-binding protein IMP3 predicts high-stage lymph node metastasis and poor prognosis in colorectal adenocarcinoma.
BACKGROUND
IMP3 (insulinlike growth factor II mRNA-binding protein 3) is a newly identified oncofetal RNA-binding protein that is involved in cell growth and cell migration during the early stages of embryogenesis. This study sought to elucidate its role in tumor progression and prognosis of colorectal adenocarcinoma (CRA).


METHODS
IMP3 expression in 186 surgically resected unifocal primary CRAs was analyzed by immunohistochemistry. The proportions of tumor cells positive for IMP3 were scored into diffuse (> or =50%), focal or heterogeneous (10-50%), and trace (<10%), and the expression levels were correlated with clinicopathologic features and patient survival.


RESULTS
Cytoplasmic immunoreactivity for IMP3 was diffuse in 66 (35%), focal or heterogeneous in 38 (21%), and trace in 34 (18%) samples. No staining was seen in the adjacent nontumorous tissue. Diffuse IMP3 expression correlated with large tumor (>3 cm, P = .0452), high-stage tumor (IIIa-IV, P = .0417), lymph node metastasis (P = .0232), high lymph node ratio (LNR > or = .7, P = .0016), and lower 5-year survival (P = .0012). Further analysis showed that patients with high-stage CRA and diffuse IMP3 expression had the worst survival rate (P < .0001)-far worse than those without diffuse IMP3 expression (P = .0038). Moreover, multivariant analysis showed diffuse IMP3 expression, serosal invasion, LNR, tumor stage, and adjuvant chemotherapy were independent prognostic factors in CRA.


CONCLUSIONS
Diffuse IMP3 protein expression correlates with invasion and aggressiveness during cancer growth and metastasis, and it is an important prognostic factor of CRAs.
Department of Surgery, Tao-Yuan General Hospital, R.O.C., Taiwan.
Ray-Hwang
RH
Yuan
Chi-Chao
CC
Wang
Chia-Cheng
CC
Chou
King-Jen
KJ
Chang
Po-Huang
PH
Lee
Yung-Ming
YM
Jeng
D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018450:Disease Progression; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics*; D011379:Prognosis; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D016019:Survival Analysis
D014408:Biomarkers, Tumor; C498780:IGF2BP3 protein, human; D009363:Neoplasm Proteins; D016601:RNA-Binding Proteins