Insulin-like growth factor II mRNA binding protein 3, IMP3, L523S, KOC (K-homologous domain-containing protein over-expressed in cancer)

The family of insulin-like growth factor mRNA binding proteins (IMP) modulate RNA trafficking and stabilization during early embryogenesis. IMP1, IMP2 and IMP3 have been identified. IMP3 is a 580 amino acid protein encoded by a gene located at 7p11.2-11.5.

IMP3 is expressed in embryogenesis by skin, muscle and placenta. Its expression by normal adult tissues is negligible, other than gonadal tissues. However, expression has been demonstrated in carcinomas of the pancreas, stomach, colon and lung and in soft tissue sarcomas.

Immunohistochemical expression

 

 

epithelium

stroma

 
 

Endometrium

atrophic

1/181

0/181

 

weakly proliferative

1/151

0/151

proliferative

1/161

0/161

secretory

0/191

5/191

menstrual

0/81

4/81

benign, NOS

0/203

 

atypical endometrial hyperplasia/intra-epithelial neoplasia

3/351

 

serous glandular dysplasia

6/211

 

serous intra-epithelial neoplasia

16/181

 

clear cell glandular dysplasia

2/121

 

clear cell intra-epithelial neoplasia

6/81

 

 

gestational endometrium

0/161

16/161

 

trophoblast

16/161

       

endometrial carcinoma

endometrioid

5/701, 68/1223

 

serous

50/511, 45/453

 

clear cell

11/181

 

mucinous

1/81

 

other

7/151

 

       

 

In renal cell carcinoma (this study was a mix of all types), positivity for IMP3 is associated with a lower rate of disease-free survival at five years2:

 

Stage

IMP3-negative

IMP3-positive

 

I

98%

44%

II

94%

41%

II

62%

16%

     

 

Diagnostic utility

References

1 Zheng W, Yi X, Fadare O, et al. The oncofetal protein IMP3: a novel biomarker for endometrial serous carcinoma. Am J Surg Pathol 2008; 32:304-15

2 Jiang Z, Chu PG, Woda BA, et al. Analysis of RNA-binding protein IMP3 to predict metastasis and prognosis of renal-cell carcinoma: a retrospective study. Lancet Oncol 2006; 7:556-64

3 Li C, Zota V, Woda BA, et al. Expression of a novel oncofetal mRNA-binding protein IMP3 in endometrial carcinomas: diagnostic significance and clinicopathologic correlations. Mod Pathol 2007; 20:1263-8

This page last revised 4.4.2008.

©SMUHT/PW Bishop