TFF-3 as an Early Biomarker of Neoplasia in Ulcerative Colitis
KK Lai, R Chen, TA Brentnall, MP Bronner. Cleveland Clinic, Cleveland, OH; University of Washington, Seattle, WA
Background: Biomarkers of neoplastic risk in ulcerative colitis (UC) are needed to focus surveillance efforts onto the patients most likely to benefit. Proteomics offers an excellent opportunity to identify new biomarkers that can be easily adapted to immunohistochemical screening tests.
Design: Quantitative proteomic profiling was performed by isotope-code affinity tag (ICAT) technology and tandem mass spectrometry using nondysplastic rectal tissue from UC with neoplasia elsewhere in the colon (progressor=P) in comparison to UC without dysplasia in the long term (nonprogressor=NP). Variably expressed peptides were validated by routine immunohistochemistry (IHC) on 2mm core tissue microarrays (TMA). Microarrays were constructed from 41 UC patients, including 27 NPs and 14 Ps (with the most advanced neoplastic diagnoses of low-grade dysplasia (LGD) in five patients, high-grade dysplasia (HGD) in four, and colorectal adenocarcinoma (CA) in five). Nondysplastic rectal tissue from all patients was examined along with the full spectrum of available neoplastic lesions in each patient. IHC was graded for intensity and percentage of positive epithelial cells, each on a scale from 0-4, and with calculation of a final score as the product of the grades.
Results: Proteomics revealed TFF-3 down regulation in UC progressors. As shown in the table, TMA IHC confirmed a trend towards decreased TTF-3 expression in nondysplastic rectal biopsies from P versus NP patients. As also shown in the table, TTF-3 was progressively down regulated throughout neoplastic progression from nondysplastic epithelium to carcinoma (p<0.05) (see table).
|Nondysplastic Rectum - NP (n=27)||Nondysplastic Rectum - LGD (n=5)||Nondysplastic Rectum - HGD (n=4)||Nondysplastic Rectum - CA (n=5)||LGD (n=6)||HGD (n=9)||CA (n=5)|
Conclusions: Using ICAT proteomics and tandem mass spectrometry with IHC TMA validation, we demonstrate sequential downregulation of TFF-3 during progression from nondysplastic UC epithelium through dysplasia to CA. We further demonstrate a downward trend for TTF-3 in nondysplastic rectal mucosa from NP patients to CA patients. TFF-3 expression in colonocytes has been postulated to play a role in mucosal healing and to be protective against carcinogenesis. Our results offer further evidence of this and promise for TTF-3 IHC as a biomarker of neoplasia risk in UC.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 99, Monday Morning