SHP-1 expression by malignant small B-cell lymphomas reflects the maturation stage of their normal B-cell counterparts

Interfering B cell receptor signaling via SHP-1/p-Lyn axis shows therapeutic potential in diffuse large B-cell lymphoma

Background

Diffuse large B cell lymphoma (DLBCL) is an aggressive and molecularly heterogeneous non-Hodgkin’s lymphoma. The B cell receptor (BCR) signaling pathway in DLBCL emerges as a new drug target. Protein phosphatase SHP-1 negatively regulates several oncogenic tyrosine kinases and plays a tumor suppressive role.

Methods

The direct SHP-1 agonists were used to evaluate the potential therapeutic implication of SHP-1 in DLBCL. Immunohistochemical staining for SHP-1 was quantified by H-score. The SHP-1 phosphatase activity was determined using tyrosine phosphatase assay. In vitro studies, including MTT, western blot analysis and cell apoptosis, were utilized to examined biological functions of SHP-1.

Results

Oral administration of SHP-1 agonist showed the potent anti-tumor effects compared to a selective Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib in mice bearing U2932 xenografts. SHP-1 agonist increased SHP-1 activity as well as downregulated p-Lyn in vivo. Here, we demonstrated that immunohistochemical staining for SHP-1 expression was positive in 76% of DLBCL samples. SHP-1 agonist exerted anti-proliferative and apoptotic effects compared with ibrutinib in DLBCL cells. Mechanistically, SHP-1 agonist decreased BCR signaling, especially p-Lyn, and led to apoptosis.

Conclusions

These data suggest that SHP-1 negatively regulates phosphorylation of Lyn, and targeting SHP-1/p-Lyn using SHP-1 agonist has therapeutic potential for treatment of DLBCL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00518-0.

Implication of protein tyrosine phosphatase SHP-1 in cancer-related signaling pathways

The altered expression of SHP-1 (SH2 domain-containing protein tyrosine phosphatase) as a consequence of promoter hypermethylation or mutations has evidently been linked to cancer development. The notion of being a cancer drug target is conceivable as SHP-1 negatively regulates cell cycle and inflammatory pathways which are an inevitable part of oncogenic transformation. In the present review, we try to critically analyze the role of SHP-1 in cancer progression via regulating the above mentioned pathways with the major emphasis on cell cycle components and JAK/STAT pathway, commencing with the SHP-1 biology in immune cell signaling. Lastly, we have provided the future directions for researchers to encourage SHP-1 as a prognostic marker and curative target for this debilitating disease called as cancer.

Alterations of negative regulators of cytokine signalling in immunodeficiency-related non-Hodgkin lymphoma

We investigated immunodeficiency-related non-Hodgkin lymphoma for the presence of molecular alterations affecting negative regulators of the Janus family protein tyrosine kinase/signal transducer and activator of transcription pathway. Protein tyrosine phosphatase, non-receptor type 6/Src homology 2-containing tyrosine phosphatase-1 epigenetic silencing was recurrent in primary effusion lymphoma (100%), and diffuse large B-cell lymphoma (63%), with a higher prevalence in the non-germinal centre subtype, and was associated with the activation of the Janus family protein tyrosine kinase/signal transducer and activator of transcription 3 pathway. Suppressor of cytokine signalling (SOCS)1 and SOCS3 epigenetic silencing were occasionally detected, whereas SOCS1 was frequently mutated in diffuse large B-cell lymphoma and polymorphic post-transplant lymphoproliferative disorders, possibly as a cause of aberrant somatic hypermutation. However, the mutation profile of the coding region of the gene was different from that expected from the aberrant somatic hypermutation process, suggesting that, at least in some cases, SOCS1 mutations may have been selected for their functional activity.

TIMP1 induces CD44 expression and the activation and nuclear translocation of SHP1 during the late centrocyte/post-germinal center B cell differentiation

Tissue inhibitor of metalloproteinase-1 (TIMP1) is a survival factor of germinal center (GC) B cells, and its over-expression is correlated with aggressive B cell lymphomas and classical Hodgkin lymphomas. We previously demonstrated that TIMP1 down-regulates B-cell receptor and BCL6, and activates interleukins-6,-10 (ILs)/signal transducer and activator of transcription-3 (STAT3) signaling in GC B cells. The activation of ILs/STAT3 signaling can amplify CD44 function, and vice versa, and induce protein-tyrosine phosphatase SHP1 activity by a negative feedback mechanism. Here, we show that TIMP1 up-regulates cell surface CD44 (standard and variants 3 and 7-10) and induces the activity and nuclear localization of SHP1 in an Epstein Barr virus (EBV)-negative Burkitt lymphoma cell line, the neoplastic counterpart of GC centroblasts. These results suggest that TIMP1 functions as a differentiating and survival factor of GC B cells by modulating CD44 and SHP1 in the late centrocyte/post-GC stage, regardless of EBV infection.

Epigenetic regulation of signal transducer and activator of transcription 3 in acute myeloid leukemia

We have demonstrated that constitutive signal transducer and activator of transcription (STAT) 3 activity, observed in approximately 50% of acute myeloid leukemia (AML) cases, is associated with adverse treatment outcome. Constitutive STAT3 activation may result from the expression of oncogenic protein tyrosine kinases or from autocrine stimulation by hematopoietic growth factors. These causes are generally neither necessary nor sufficient for leukemogenesis; additional transforming events or growth stimulatory processes are needed. Here we review the literature addressing epigenetic regulation as a mechanism controlling STAT3 signaling in AML. A better understanding of mechanisms of dysregulation of STAT signaling pathways may serve as a basis for designing novel therapeutic strategies that target these pathways in leukemia cells.

SHP-1 expression in primary central nervous system B-cell lymphomas in immunocompetent patients reflects maturation stage of normal B cell counterparts

SHP-1 is an important negative regulator involved in signaling through receptors for cytokine/growth factors, and differential patterns of SHP-1 expression in several types of B-cell lymphomas closely resemble the patterns seen in their normal B cell counterparts. In an effort to elucidate the origin of primary central nervous system lymphomas (PCNSL), the present study assessed 32 cases of PCNSL. Tumors were subclassified according to WHO classification and were evaluated by immunohistochemistry for expression of antigens associated with germinal center (GC) (CD10, Bcl-6) and non-GC stages (SHP-1, CD138). Twenty-nine cases showed diffuse large-cell centroblastic morphology, whereas three cases showed diffuse large-cell immunoblastic morphology. The immunophenotypes of PCNSL were as follows: SHP-1+/Bcl-6-/CD10-/CD138- (12 of 32 cases); SHP-1+/Bcl-6+/CD10-/CD138- (15 of 32 cases); SHP-1+/Bcl-6+/CD10+/CD138- (two of 32 cases); SHP-1+/Bcl-6-/CD10+/CD138- (one of 32 cases); and SHP-1-/Bcl-6-/CD10-/CD138- (two of 32 cases). These results indicate that PCNSL might be distinct lymphomas that originate from a late germinal center to an early postgerminal center.

[Phosphotyrosine phosphatase SHP-1, somatostatin and prostate cancer]

We review the mechanisms involved in prostatic growth based on androgens and product of neuroendocrine secretion, with special reference to the role of somatostatin (SS) in the inhibition of neoplastic growth. Our contributions in the field confirm the antiproliferative effect of SS on the prostate is mediated by phosphotyrosine phosphatase SHP-1, that is present in human prostate. This enzyme plays a role in the control of prostatic cell proliferation and in the progression of prostate cancer. Besides, we consider its presence may determine the therapeutic potential of SS in the control of prostate cancer.

Intracellular signalling molecules as immunohistochemical markers of normal and neoplastic human leucocytes in routine biopsy samples

We have investigated whether intracellular signal transduction molecules can be used as immunohistological markers of normal and neoplastic human leucocytes in routine tissue sections. We obtained selective labelling of white cells for eight such molecules (the 'linker' molecules SLP-76 and BLNK, the Src family kinases Lyn, Fyn, Syk and Hck, and the phospholipases PLC-gamma1 and PLC-gamma2). Antibodies to SLP-76 and PLC-gamma1 selectively labelled T cells, and antibodies to BLNK, Lyn, Fyn, Syk and PLC-gamma2 labelled B cells (although Fyn immunostaining was restricted to mantle zone B cells). Antibodies to the Syk and Hck kinases labelled probable thymocyte precursors at the periphery of the thymic cortex. In addition to lymphoid cells, several other leucocyte types were immunostained (e.g. SLP-76, Lyn, Syk and Hck were found in megakaryocytes, myeloid cells and/or macrophages, and PLC-gamma2 was detected in arterial endothelium). SLP-76 and PLC-gamma1 were found in most T-cell lymphomas studied, and some B-cell lymphomas were also positive for PLC-gamma1 (e.g. diffuse large cell and Burkitt's lymphoma). The five B cell-associated markers were found in most B-cell non-Hodgkin's lymphomas, although some diffuse large B-cell lymphomas were negative (e.g. for Lyn) and anti-Fyn tended not to stain small B-cell neoplasms. The observation that a range of leucocyte signalling molecules can be detected in routine biopsies offers new possibilities for studying normal and neoplastic human white cells in diagnostic tissue samples.

Immunosuppressive TOR kinase inhibitor everolimus (RAD) suppresses growth of cells derived from posttransplant lymphoproliferative disorder at allograft-protecting doses

BACKGROUND

Posttransplant lymphoproliferative disorders (PTLDs) represent a life-threatening complication of standard immunosuppressive therapy. The impact of novel, rapamycin-related immunosuppressive drugs on the pathogenesis of PTLDs remains undefined.

METHODS

We tested the effect of everolimus (RAD, Novartis Pharma AG, Basel, Switzerland) on human PTLD-derived cells using in vitro assays and an in vivo severe combined immunodeficiency disease mouse xenotransplant model.

RESULTS

Everolimus profoundly inhibited the proliferation, cell-cycle progression, and survival of the PTLD-1 cell line established from a pulmonary PTLD. Equally profound inhibition of PTLD-1 growth was achieved in vivo at well-tolerated everolimus doses of 0.5 to 5 mg/kg per day. Five mg/kg per day of everolimus, given once per day, inhibited PTLD-1 tumor volume gain by more than 10-fold in treated mice compared with untreated mice. Because the subsequent pharmacokinetic analysis indicated rapid everolimus absorption, distribution, and clearance in mice (with a half-life of 3 to 6 hr and maximum drug blood concentration reached after 0.5 to 1 hr), treatment was changed to a twice-daily regimen. Everolimus given twice daily at 0.5 mg/kg per dose inhibited tumor-volume gain by more than 60-fold and at 0.25 mg/kg per dose by more than 10-fold. Similar everolimus doses were required to prevent graft rejection in a mouse heart allotransplantation model; the highest dose tested (1.5 mg/kg twice daily) resulted in long-term graft survival in all mice that underwent transplantation.

CONCLUSIONS

Everolimus displays a potent inhibitory effect on PTLD-derived cells in vitro and in vivo in a dose range leading to prevention of allograft rejection and may prove effective in both the prevention and treatment of PTLDs in transplant patients.

Expression of STAT3 and its phosphorylated forms in mantle cell lymphoma cell lines and tumours

The pathogenesis of mantle cell lymphoma (MCL) is incompletely understood, although cyclin D1 overexpression leading to deregulated cell proliferation is probably important. Recent data suggest that interleukin (IL)-10 can increase the proliferative activity of MCL cells. STAT3 (signal transducer and activator of transcription 3) is the signal transducer of IL-10, and STAT3 is activated by phosphorylation. The hypothesis of this study is that STAT3 is activated in MCL. The expression of the two phosphorylated (i.e. active) forms of STAT3, pSTAT3-tyr (phosphorylated at the tyrosine(705) residue) and pSTAT3-ser (phosphorylated at the serine(727) residue), was assessed in four MCL cell lines and 12 MCL tumours using western blots and/or immunofluorescence staining techniques. All MCL cell lines expressed STAT3, but only one had detectable pSTAT3-tyr and none had pSTAT3-ser. Addition of IL-10 rapidly resulted in expression of pSTAT3-tyr but not pSTAT3-ser. All eight cases of frozen MCL tumours examined had detectable pSTAT3-tyr and pSTAT3-ser. Immunofluorescence studies using four formalin-fixed, paraffin wax-embedded MCL tumours demonstrated cytoplasmic localization of STAT3, as opposed to the nuclear localization of the pSTAT3 species. In conclusion, these findings provide evidence that STAT3 is constitutively activated in MCL, supporting the concept that STAT3 signalling may be important in the pathogenesis of these tumours.

Expression of SHP-1 phosphatase indicates post-germinal center cell derivation of B-cell posttransplant lymphoproliferative disorders

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.

Properties of the mantle cell and mantle cell lymphoma

The major lymphoid inhabitant of the follicular mantle is the mantle cell, an immunologically naïve B cell. It is the putative cell of origin of mantle cell lymphoma (MCL), the cells of which have similar morphologic, immunophenotypic, and molecular characteristics to the normal B lymphocytes of the mantle zone. In the past year a number of advances have been made in the biology of the normal mantle cell, its interactions with the other constituents of the follicular and mantle zone microenvironments, and the development of neoplasia in this cell population. In addition, new developments in diagnostic molecular pathology have been used to more readily identify cases of MCL. The authors summarize these new advances in the understanding of the biology of the mantle cell and newer ancillary techniques in the diagnosis of lymphomas arising from this cell type.