SHP-1 Expression by Malignant Small B-Cell Lymphomas Reflects the Maturation Stage of Their Normal B-Cell Counterparts

Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
American Journal of Surgical Pathology (Impact Factor: 5.15). 08/2001; 25(7):949-55. DOI: 10.1097/00000478-200107000-00015
Source: PubMed


SHP-1 is a protein phosphotyrosine phosphatase that plays an important role in modulating intracellular signaling, which regulates cell activation, proliferation, differentiation, and migration. It is a negative regulator of signal transduction induced by a number of cell receptors. Our immunohistochemical examination of paraffin-embedded reactive lymph nodes and lymphoid tissues revealed that B lymphocytes in follicle germinal centers do not express SHP-1. A weak staining of the B cells in the germinal center light zones was detected when an ultrasensitive amplification system was used. In contrast, normal B cells in mantle and marginal zones as well as interfollicular B lymphocytes and plasma cells displayed strong immunoreactivity. This pattern of SHP-1 expression was repeated in small B-cell lymphomas. All cases of mantle cell lymphoma (12 of 12), marginal zone lymphoma (10 of 10), and chronic lymphocytic leukemia/small lymphocytic lymphoma (13 of 13) expressed SHP-1 protein. However, only 1 of 30 cases of grade 1 follicle center cell lymphoma expressed SHP-1. Our observations highlight the biologic functions of SHP-1 and demonstrate that the SHP-1 expression pattern by small B-cell lymphomas reflects the maturation stage of their normal cell counterparts. These results indicate that determination of SHP-1 expression may help in the differential diagnosis of small B-cell lymphomas.

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    • "However, strong expression of SHP-1 protein also was observed in 40% of mantle zone and some inter-follicular zone lymphocytes in reactive lymphoid hyperplasia specimens (Oka et al., 2001). A few lymphoma samples, including four kinds of malignant small B-cell lymphoma tissues, all mantle cell lymphomas (12/12), marginal zone lymphocytic lymphomas (10/10) and chronic lymphocytic leukemia/ small lymphocytic lymphomas (13/13) were found to express SHP-1 protein at normal levels (Kossev et al., 2001). 6. "
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    ABSTRACT: SHP-1, an SH2 domain-containing protein tyrosine phosphatase, is primarily expressed in hematopoietic cells and behaves as a key regulator controlling intracellular phosphotyrosine levels in lymphocytes. SHP-1 has been proposed as a candidate tumor suppressor gene in lymphoma, leukemia and other cancers, as it functions as an antagonist to the growth-promoting and oncogenic potentials of tyrosine kinase. The decreased levels of SHP-1 protein and SHP-1 mRNA observed in various leukemia and lymphoma cell lines have been attributed to either the methylation of the promoter region of the SHP-1 gene or the post-transcriptional block of SHP-1 protein synthesis. In contrast, SHP-1 protein is normally or over-expressed in some non-lymphocytic cell lines, such as prostate cancer, ovarian cancer and breast cancer cell lines. SHP-1 expression also is decreased in some breast cancer cell lines with negative expression of estrogen receptor as well as some prostate and colorectal cancer cell lines. These data suggest that SHP-1 can play either negative or positive roles in regulating signal transduction pathways. Dysfunction in SHP-1 regulation can cause abnormal cell growth and induce different kinds of cancers. In this paper, we summarize recent studies on the expression and regulation of SHP-1 protein and its pathological function in the development of lymphoma, leukemia and other cancers.
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    ABSTRACT: SHP-1 tyrosine phosphatase acts as a negative regulator of signaling by receptors for growth factors, cytokines, and chemokines and by receptors involved in immune response. Our recent study showed that SHP-1 is tightly regulated at various stages of B-cell differentiation and is expressed in the mantle and marginal zones, interfollicular B cells, and plasma cells, whereas it is nondetectable in germinal center cells. In this study we evaluated expression of SHP-1 in vitro and in vivo in nine cell lines representing three different types of EBV+ B-cell populations closely resembling or derived from posttransplant lymphoproliferative disorders (PTLDs). Furthermore, we examined tissue samples from 58 patients with B-cell PTLDs, both EBV+ (85% of the cases analyzed) and EBV- (15%). SHP-1 protein was strongly expressed in all cell lines and PTLD cases. In addition, the PTLD cases were essentially negative for germinal center B-cell markers: none expressed CD10 and only one expressed BCL-6. More than 40% expressed a late post-germinal B-cell marker, CD138. The universal expression of SHP-1, lack of expression of CD10 and BCL-6, and frequent expression of CD138 suggest that PTLDs are derived from post-germinal center B cells regardless of the EBV cell infection status. Based on the immunophenotype, B-cell PTLDs could be divided into two broad categories corresponding to the early (CD10-/BCL-6-/SHP-1+/CD138-) and late (CD10-/BCL-6-/SHP-1+/CD138+) post-germinal center cells. By being expressed earlier, SHP-1 is a more sensitive marker of post-germinal center B cells than CD138, which is seen on the terminally differentiated immunoblasts and plasma cells.
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