Nucleolar C-Terminal Expression of POTE G and H in Non-Hodgkin Lymphomas
Nivin Ishaq, Srinivasa C Chekuri, Jessica E Fleming, Zhi He, John Lam, Xinchun Zhou. University of Mississippi, Jackson, MS
Background: Proteins expressed in prostate, ovary, testis and placenta (POTEs) are a group of newly discovered molecules encoded by different POTE gene paralogs. Our previous studies found that the C-terminal common to POTE G and H are localized in nucleoli in certain normal tissues, such as prostate, ovary, and placenta, and in many cancers including lymphoma. This study aimed to determine whether nucleolar expression of the C-terminal of POTE G and H correlates with proliferation indices of non- Hodgkin lymphomas.
Design: We constructed a tissue microarray (TMA) with 66 formalin-fixed paraffin-embedded tumor samples from patients with various types of non- Hodgkin lymphomas. According to proliferative index, the specimens were divided into high proliferative group (n=42, including Burkett's, diffuse large B- cell, and lymphoblastic lymphoma) and low proliferative group (n=23, including follicular, mantle and small lymphocytic/chronic lymphocytic lymphoma). We performed immunohistochemistry (IHC) for N- and C-terminals of POTE G and H and Ki-67 on the TMA slides. The final IHC score was calculated by area score (0-3) multiplied by intensity score (0-3), with a maximal score of 9. We used bivariate analysis to correlate IHC scores between Ki-67 and N-, or C-terminal of POTE; we used the T-test to compare mean IHC scores between the two groups.
Results: The IHC signals for Ki-67, N- and C-terminals of POTE G and H were seen in nuclei, cytoplasm, and nucleoli, respectively. The expression level of nuclear Ki-67 had a significant correlation with the nucleolar expression level of C-terminal of POTE G and H (Kendall tau = 0.41, p-value <0.01). There was no correlation between Ki-67 and the N-terminal of POTE G and H. The mean IHC score of the C-terminal, but not of the N-terminal, was significantly higher in high proliferating compared to low proliferating non- Hodgkin lymphomas (3.244±2.98 vs. 1.83±2.21, p=0.04).
Conclusions: In our cohort of 66 non-Hodgkin's lymphomas, we found: i) significant correlation between nucleolar expression of Ki-67 and the C-terminal of POTE G and H, and ii) significant correlation between Ki67 and C-terminal expression of POTE G and H in lymphomas with high proliferation compared to those with low proliferative indices. Further studies are needed to explore the role of nucleolar expression of the C-terminal of POTE G and H in the classification and diagnosis of non-Hodgkin's lymphoma.
Monday, March 4, 2013 1:00 PM
Poster Session II # 195, Monday Afternoon