title: Immunohistochemical expression of folate receptor alpha in colorectal carcinoma: patterns and biological significance.
abstract: Folate receptor alpha (FRalpha) has emerged as a potential cancer therapy target with several folate-linked therapeutic agents currently undergoing clinical trials. In addition, FRalpha expression in tumors may offer prognostic significance. Most studies on FRalpha expression used reverse transcriptase polymerase chain reaction or cytofluorimetric assays. The applicability of such methods to paraffin-embedded tissues is limited. The aims of this study were to assess the feasibility of immunohistochemistry in detecting FRalpha expression and to assess the patterns and clinical significance of FRalpha expression in colorectal tissues. We used tissue microarrays containing 152 normal colorectal mucosa samples, 42 adenomas, 177 primary, and 52 metastatic colorectal carcinomas. Our results showed that staining for FRalpha on colorectal tissues was simple and easy to read. FRalpha positivity was more frequent in carcinomas (33% in primaries and 44% in metastases) than in normal mucosa or adenoma (7% in both) (P < .001). Positive staining in primary carcinomas correlated with younger age (n = 130) (P = .008), presence of distant metastasis (n = 130) (P = .043), and non-high-frequency microsatellite instability status (as detected by the standard polymerase chain reaction method using the 5 National Cancer Institute-recommended markers) (n = 77) (P = .006). Positive staining in primary carcinomas also correlated with a worse 5-year disease-specific survival (P = .04) on univariate but not multivariate analysis. Thus, our data show that there is selective expression of FRalpha in some colorectal cancers, providing a foundation for investigating the use of folate conjugates for imaging and therapy of colorectal tumors. Furthermore, our results suggest that a possible association exists between FRalpha expression and the microsatellite instability status in colorectal carcinoma. The significance of such an association as well as the prognostic value of FRalpha expression deserves further exploration.
authors.affiliation: Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. shiaj@mskcc.org
authors.forename: Jinru
authors.initials: J
authors.lastname: Shia
authors.forename: David S
authors.initials: DS
authors.lastname: Klimstra
authors.forename: James R
authors.initials: JR
authors.lastname: Nitzkorski
authors.forename: Philip S
authors.initials: PS
authors.lastname: Low
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.forename: Ron
authors.initials: R
authors.lastname: Landmann
authors.forename: Martin R
authors.initials: MR
authors.lastname: Weiser
authors.forename: Wilbur A
authors.initials: WA
authors.lastname: Franklin
authors.forename: Franklyn G
authors.initials: FG
authors.lastname: Prendergast
authors.forename: Linda
authors.initials: L
authors.lastname: Murphy
authors.forename: Laura H
authors.initials: LH
authors.lastname: Tang
authors.forename: Larissa
authors.initials: L
authors.lastname: Temple
authors.forename: Jose G
authors.initials: JG
authors.lastname: Guillem
authors.forename: W Douglas
authors.initials: WD
authors.lastname: Wong
authors.forename: Philip B
authors.initials: PB
authors.lastname: Paty
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000378:metabolism; D013194:Staining and Labeling; D046888:Tissue Array Analysis
chemical_list: D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface