title: Keratin 7 expression in colorectal cancer--freak of nature or significant finding?
abstract: OBJECTIVE
  To assess the prevalence of keratin 7 (K7) expression in colorectal cancer and to correlate findings with clinicopathological parameters and patients' outcome.
  
  
  RESULTS
  A total of 370 patients were evaluated for K7 expression by immunohistochemistry using a tissue microarray technique. K7 expression was scored semiquantitatively as either focal (<10%), moderate (10-50%) or extensive (>50%). In all, 32 (9%) tumours were immunoreactive for K7, with five cases showing extensive, four moderate and 23 focal expression, respectively. K7 expression was associated with poor tumour differentiation (P = 0.005) and the extent of tumour budding (P = 0.02). In whole sections, K7 immunoreactivity prevailed in single cells and small clusters of cells at the invasion front. Analysis of serial sections showed that K7-positive cells colocalized with keratin 20, whereas they lacked immunoreactivity for E-cadherin, MUC2 and MIB-1. Disease progression occurred in 52% of patients with K7-positive tumours and 41% with K7-negative tumours (P = 0.19); 48% of patients with K7-positive tumours but only 33% with K7-negative tumours died of disease (P = 0.06).
  
  
  CONCLUSIONS
  Aberrant expression of K7 in budding cancer cells represents a modification of the epithelial phenotype ('epithelial-epithelial transition': EET) which may be linked to gains in motility and invasive potential.
authors: Institute of Pathology, Medical University of Graz, Austria.
authors: Lars
authors: L
authors: Harbaum
authors: Marion J
authors: MJ
authors: Pollheimer
authors: Peter
authors: P
authors: Kornprat
authors: Richard A
authors: RA
authors: Lindtner
authors: Andrea
authors: A
authors: Schlemmer
authors: Peter
authors: P
authors: Rehak
authors: Cord
authors: C
authors: Langner
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D054338:Cell Transdifferentiation; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D006801:Humans; D053554:Keratin-20 / Q000378:metabolism; D053552:Keratin-7 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D046888:Tissue Array Analysis
chemical_list: D014408:Biomarkers, Tumor; C507499:KRT20 protein, human; C507497:KRT7 protein, human; D053554:Keratin-20; D053552:Keratin-7