title: Expression of cell cycle control proteins in primary colorectal tumors does not always predict expression in lymph node metastases.
abstract: Analysis of tumor markers focuses on expression in primary tumors with the assumption that this is representative of metastatic tumor, against which treatment is targeted. Few studies have compared the expression of such markers in primary and secondary tumors. In this study, several key genes involved in cell cycle regulation were investigated in colorectal tumors and corresponding lymph node metastases. The cell cycle regulators p53, cyclin D1, p21, p27, retinoblastoma protein (Rb), and proliferating cell nuclear antigen (PCNA) were examined in a series of 42 paired samples of primary colorectal and secondary lymph node tumors by immunohistochemistry. Expression of p53, p27, and Rb was similar in virtually all paired samples (p53, 38 of 42; p27, 39 of 42; Rb, 40 of 42), indicating that the pattern of these proteins in colorectal tumors may be used to predict that in lymph node tumors. It also suggests a lack of direct involvement in the metastatic process. A lower concordance for p21 and cyclin D1 staining was observed between primary and secondary tumors (p21, 19 of 42; cyclin D1, 22 of 42). p21 expression was more often observed in primary colorectal cancers, whereas cyclin D1 expression was more frequently seen in lymph node metastases, in keeping with the contrasting roles of these proteins as a cell cycle inhibitor (p21) and activator (cyclin D1). The PCNA-labeling index was found to vary considerably in a number of cases, thus limiting the ability to predict expression of this protein in lymph node metastases from the primary tumor. In addition, PCNA-labeling indices between paired samples were neither consistently higher nor lower, suggesting that the proliferative capacity of tumor cells is not directly related to their ability to metastasize.
authors.affiliation: Department of Medicine and Therapeutics, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, Scotland, United Kingdom. j.a.mckay@abdn.ac.uk
authors.forename: J A
authors.initials: JA
authors.lastname: McKay
authors.forename: J J
authors.initials: JJ
authors.lastname: Douglas
authors.forename: V G
authors.initials: VG
authors.lastname: Ross
authors.forename: S
authors.initials: S
authors.lastname: Curran
authors.forename: F Y
authors.initials: FY
authors.lastname: Ahmed
authors.forename: J F
authors.initials: JF
authors.lastname: Loane
authors.forename: G I
authors.initials: GI
authors.lastname: Murray
authors.forename: H L
authors.initials: HL
authors.lastname: McLeod
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018797:Cell Cycle Proteins / Q000032:analysis* / Q000096:biosynthesis; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D019938:Cyclin D1 / Q000032:analysis; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000737:chemistry* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008869:Microtubule-Associated Proteins / Q000032:analysis; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D016160:Retinoblastoma Protein / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000032:analysis; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D018809:Proliferating Cell Nuclear Antigen; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27