Mucins

Mucins are high molecular weight glycoproteins expressed by epithelial cells. Several mucin genes have ben identified or cloned (MUC1 - MUC12) and monoclonal antibodies raised against their glycoprotein products. Sequence homologies distinguish two main families. The MUC genes at 11p15 encode secreted gel-forming mucins (MUC2, MUC5AC, MUC5B, MUC6). The MUC genes at loci 7q22, 3q and 1q21 encode mainly membrane-bound mucins5.

 

Like cytokeratins, they show relative specificity for tissue types. MUC1 is identical to EMA.

MUC2 is expressed by mucinous adenocarcinomas of the colon, breast, pancreas and ovary4. CDX-2 may interact with the MUC2 promoter, activating MUC2 expression4.

 

Immunohistochemical expression

 

MUC1 (EMA)

MUC2

MUC5AC

  

breast

normal mammary gland

10/101

0/101

0/101

ductal carcinoma

13/131

0/131

0/131

GI tract

stomach

 

 

positive1

pancreas

positive1

 

 

intestinal goblet cell

 

positive1

 

rectal mucosa

0/101

10/101

3/101

anal glands

0/61

0/61

6/61

renal cell carcinoma

26/601

 

 

vulva

eccrine glands

12/121

0/121

0/121

apocrine glands

8/81

0/81

0/81

mammary-like glands

6/61

0/61

0/61

Bartholin's glands

7/71

0/71

7/71

cervix

endocervical glands

 

 

positive1
 

 

Columnar-lined oesophagus commonly expresses MUC5AC and MUC6. MUC2 is only expressed in the presence of intestinal metaplasia3.

 

MUC4 expression is acquired in dysplastic ectocervical squamous epithelium2:

normal endocervical glandular epithelium

11/11, in 50% to 100% of cells

normal ectocervical squamous epithelium

4/18, focally in parabasal cells

squamous metaplasia

7/9, in 10% to 50% of parabasal cells

CIN I

17/19, in all layers of the epithelium

CIN II

7/7, in all layers of the epithelium

CIN III

9/9, in all layers of the epithelium
   

Diagnostic utility

 

References

1Kuan, S. F., Montag, A. G., Hart, J., Krausz, T., Recant, W. Differential expression of mucin genes in mammary and extramammary Paget's disease. Am J Surg Pathol 2001;25:1469-1477.

2 Lopez-Ferrer, A., Alameda, F., Barranco, C., Garrido, M., de Bolos, C. MUC4 expression is increased in dysplastic cervical disorders. Human Pathology 2001;32;1197-1202.

3Warson, C., J. H. Van De Bovenkamp, et al. (2002). "Barrett's esophagus is characterized by expression of gastric-type mucins (MUC5AC, MUC6) and TFF peptides (TFF1 and TFF2), but the risk of carcinoma development may be indicated by the intestinal-type mucin, MUC2." Hum Pathol 33(6): 660-8.

4Cathro, H. P. and S. E. Mills (2004). "Immunophenotypic differences between intestinal-type and low-grade papillary sinonasal adenocarcinomas: an immunohistochemical study of 22 cases utilizing CDX2 and MUC2." Am J Surg Pathol 28(8): 1026-32.

5 Handra-Luca A, Lamas G, Bertrand JC, et al. MUC1, MUC2, MUC4, and MUC5AC expression in salivary gland mucoepidermoid carcinoma: diagnostic and prognostic implications. Am J Surg Pathol 2005; 29:881-9

This page last revised 11.9.2005.

©SMUHT/PW Bishop