title: Immunohistochemical expression of the transcription factor DP-1 and its heterodimeric partner E2F-1 in non-Hodgkin lymphoma.
abstract: DP-1 is a G1 cell cycle-related protein that forms heterodimers with E2F, a family of transcriptional factors regulating the expression of genes important for G1 to S progression. Although the exact role of DP-1 is not well understood, it has been shown to stabilize DNA binding of E2F proteins. By immunohistochemistry, the authors examined the expression of DP-1 in lymphoid tissues, including 8 cases of reactive follicular hyperplasia and 69 cases of B-cell non-Hodgkin lymphoma. The expression of the cell cycle-related proteins E2F-1 and Ki-67 was also assessed. Scoring was based on the proportion of labeled nuclei (1-10%, 11-25%, 26-50%, and > 50%). In reactive follicular hyperplasia, staining for DP-1, E2F-1, and Ki-67 was largely confined to the germinal centers. All 25 cases of follicular lymphoma, regardless of grade, had a high proportion (> 50%) of DP-1-positive cells but a lower proportion of cells marking for E2F-1 and Ki-67 (P < 0.001). The diffuse large B-cell lymphomas (n = 24) had high DP-1 and Ki-67 scores but low E2F-1 scores (P < 0.001). Small lymphocytic (n = 10), marginal zone (n = 3), and mantle cell lymphomas (n = 5) contained relatively low proportions of cells labeled for all three markers. Precursor B-cell lymphoblastic lymphoma (n = 2) displayed high proportions of cells positive for DP-1, Ki-67, and E2F-1 (> 50% in both cases). Except in follicular center cell lesions, DP-1 expression generally correlated with that of Ki-67. However, the expression of DP-1 was discordant with that of E2F-1 in benign and malignant follicular center cells, suggesting that DP-1 may have functions other than facilitating E2F-1-dependent gene regulation and cell cycle progression in these neoplasms.
authors.affiliation: Department of Pathology, Los Angeles County and University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Joel A
authors.initials: JA
authors.lastname: Chan
authors.forename: Maria
authors.initials: M
authors.lastname: Olvera
authors.forename: Raymond
authors.initials: R
authors.lastname: Lai
authors.forename: Win
authors.initials: W
authors.lastname: Naing
authors.forename: Sherif A
authors.initials: SA
authors.lastname: Rezk
authors.forename: Russell K
authors.initials: RK
authors.lastname: Brynes
mesh_terms: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D019281:Dimerization; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008228:Lymphoma, Non-Hodgkin / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D019394:Ki-67 Antigen; C493735:TFDP1 protein, human; D050680:Transcription Factor DP1; D014157:Transcription Factors