Excessive survivin expression in thyroid lymphomas

Survivin as a diagnostic and therapeutic marker for thyroid cancer

Thyroid cancer (TC) is known as the most prevalent form of endocrine malignancy. With regard to high heterogeneity of the nodules, problem of discriminating between benign and malignant ones in terms of pathological characteristics, as well as lack of appropriate molecular markers; significant efforts are being made to identify molecular markers that able to detect tumorous lesions. Survivin, the newest member of the family of proteins inhibiting cell apoptosis, has been recently considered as a novel molecule marker for cancer. Studies on TC have also demonstrated distinctive expression of survivin and its splice variants in cancer cells compared to normal ones. Therefore, detection of survivin expression and its new splice variants can be utilized to identify tumor nodules and distinguish them from non-cancerous ones, along with other routine laboratory methods.

Thyroid lymphoma: recent advances in diagnosis and optimal management strategies

Primary thyroid lymphoma is rare, composing approximately 5% of all thyroid malignancies and less than 3% of all extranodal lymphomas. It typically presents as a rapidly enlarging goiter with associated compressive symptoms. Thyroid ultrasound and fine needle aspiration cytology, using flow cytometry and immunohistochemistry, remain the main modalities used to confirm the presence of lymphoma. The increasing use of an ultrasound-guided core biopsy to achieve an accurate diagnosis has further limited the role of surgery. An open surgical biopsy may still be required not only for definitive diagnosis but also to confirm the subtype of lymphoma. There are limited numbers of randomized or prospective trials to guide management, and controversy remains over optimal treatment. Treatment and prognosis of this disease can be dichotomized into two separate groups: pure mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma (DLBCL) or mixed subtypes. Early stage (stage IE) intrathyroidal MALT lymphomas typically have an indolent course and may be treated with single-modality surgery, radiotherapy, or a combination of both. DLBCLs are more aggressive, and survival outcomes are highest with multimodal therapy incorporating monoclonal antibodies, chemotherapy, and radiotherapy. The prognosis is generally excellent but can be varied because of the heterogeneous nature of thyroid lymphomas. The aim of this paper is to discuss the changes in diagnostic modalities and to focus on the recent alterations in the management of this rare disease, including targeted therapies as well as the more limited role of the endocrine surgeon.

Immunoexpression of Survivin in non-neoplastic lymphoid tissues and malignant lymphomas using a new monoclonal antibody reactive on paraffin sections

Survivin is a member of the inhibitor of apoptosis gene family, which is also implicated in mitosis regulation. Most reports in the literature impute poor prognosis to neoplasms with overexpression of this protein. The purpose of the present study is to validate and compare the immunohistochemical reactivity of malignant lymphomas and reactive lymphoid tissue using a new mouse monoclonal antibody to Survivin produced in our laboratory, 6-78. Survivin was detected by immunohistochemistry on tissue microarrays. It was shown that the antibody anti-Survivin 6-78 reliably stains formalin-fixed, paraffin-embedded reactive and neoplastic lymphoid tissues, mostly in a nuclear pattern. We confirmed using this novel antibody that Survivin immunostaining has a tendency to be lower in reactive lymphoid tissues and low-grade B cell lymphomas than in aggressive lymphomas. This antibody may represent a useful tool for standardizing the study of the immunoexpression of Survivin in neoplasms.

Regulation of D-cyclin translation inhibition in myeloma cells treated with mammalian target of rapamycin inhibitors: rationale for combined treatment with extracellular signal-regulated kinase inhibitors and rapamycin

We have shown that heightened AKT activity sensitized multiple myeloma cells to the antitumor effects of the mammalian target of rapamycin inhibitor CCI-779. To test the mechanism of the AKT regulatory role, we stably transfected U266 multiple myeloma cell lines with an activated AKT allele or empty vector. The AKT-transfected cells were more sensitive to cytostasis induced in vitro by rapamycin or in vivo by its analogue, CCI-779, whereas cells with quiescent AKT were resistant. The ability of mammalian target of rapamycin inhibitors to down-regulate D-cyclin expression was significantly greater in AKT-transfected multiple myeloma cells due, in part, to the ability of AKT to curtail cap-independent translation and internal ribosome entry site (IRES) activity of D-cyclin transcripts. Similar AKT-dependent regulation of rapamycin responsiveness was shown in a second myeloma model: the PTEN-null OPM-2 cell line transfected with wild-type PTEN. Because extracellular signal-regulated kinase (ERK)/p38 activity facilitates IRES-mediated translation of some transcripts, we investigated ERK/p38 as regulators of AKT-dependent effects on rapamycin sensitivity. AKT-transfected U266 cells showed significantly decreased ERK and p38 activity. However, only an ERK inhibitor prevented D-cyclin IRES activity in resistant "low-AKT" myeloma cells. Furthermore, the ERK inhibitor successfully sensitized myeloma cells to rapamycin in terms of down-regulated D-cyclin protein expression and G1 arrest. However, ectopic overexpression of an activated MEK gene did not increase cap-independent translation of D-cyclin in "high-AKT" myeloma cells, indicating that mitogen-activated protein kinase/ERK kinase/ERK activity was required, but not sufficient, for activation of the IRES. These data support a scenario where heightened AKT activity down-regulates D-cyclin IRES function in multiple myeloma cells and ERK facilitates activity.

Survivin-derived peptide epitopes and their role for induction of antitumor immunity in hematological malignancies

The immune system's ability to detect and destroy tumor cells offers an attractive approach to broaden the spectrum of cancer therapies. Survivin, a member of the apoptosis inhibitor protein family, is a tumor antigen, overexpressed in human cancers giving rise to peptides eliciting spontaneous CD8+ and CD4+ responses. Due to its dual function, blockade of apoptosis and regulation of cell division, survivin is directly associated with tumor survival and therefore regarded as an ideal target structure for immunotherapeutic approaches. Strong evidence that survivin acts as a T-cell activating antigen has been collected in recent years and the first clinical trials using survivin-based vaccines aim to prove its therapeutic efficacy in the clinic. We focus on the role of survivin in hematological malignancies, including a list of survivin-derived peptides eliciting potent immune responses.

Survivin and EPR-1 expression in acute leukemias: prognostic significance and review of the literature

The aim of this study is to detect the biologic and/or prognostic significance of survivin (S) and effector protease receptor 1: EPR-1 (E) expression in acute leukemias (34 ALL and 40 AML) by using RT-PCR. S and E expressions were found in 83.8 and 20.3% of the cases, respectively. S was detected in 90%, 76.5% and E was detected in 17.5%, 23.5% of the cases with AML and ALL, respectively. There was a significant correlation between S and E (r=0.30 p=0.01). Mortality rate was higher in E(-) cases than E(+) cases (83.1 % versus 66.7%) (p=0.04). The median DFS and OS rates were shorter in S(+) and E(-) cases. In subgroup analysis, there was not a significant difference for OS between S(-) and S(+) cases and E(-) and E(+) cases in ALL group. The median OS rate was significantly longer in S(-) cases than S(+) cases, and longer in E(+) cases than E(-) in AML groups (p=0.04, 0.001, respectively). OS and DFS rates were longest in S(-) E(+) cases and shortest in S(+) E(-) cases (p=0.04 and 0.03, respectively). In multivariate analyses EPR1 negativity was found to be an independent poor risk factor for survival (OR: 2.4, p=0.02). In conclusion S expression is a bad prognostic indicator in cases with acute leukemia especially in AML. S negativity and E positivity show good clinical outcome in acute leukemias. E expression is important due to its property of the possible natural anti-sense of the S.

AKT activity regulates the ability of mTOR inhibitors to prevent angiogenesis and VEGF expression in multiple myeloma cells

We recently demonstrated that the mammalian target of rapamycin (mTOR) inhibitor, CCI-779, curtailed the growth of a subcutaneous challenge of multiple myeloma (MM) cells in immunodeficient mice. This antitumor effect was associated with prevention of cell proliferation, induction of apoptosis and inhibition of angiogenesis. Interestingly, myeloma tumors with heightened AKT activation were particularly sensitive to a CCI-779-induced antitumor response. To investigate whether part of the differential sensitivity was due to an AKT-regulated effect on angiogenesis, we compared the effects of mTOR inhibitors against isogenic MM cell lines that only differ by their degree of AKT activity. In this model, heightened AKT activity significantly sensitized MM cells to the following inhibitory effects of mTOR inhibition: angiogenesis in vivo, vascular endothelial growth factor (VEGF) expression in vitro and in vivo and VEGF translation (but not transcription). Assessment of p70S6 kinase activity indicated that rapamycin induced comparable mTOR inhibition in both cell lines suggesting that an adverse effect on VEGF cap-dependent translation would be comparable. Internal ribosome entry site (IRES)-mediated cap-independent translation is a salvage pathway for protein expression when mTOR is inhibited, so we analyzed a possible regulatory role of AKT on VEGF IRES activity. We found that elevated AKT activity inhibited VEGF IRES function. These results support a mechanism whereby AKT prevents VEGF IRES activity in myeloma cells during mTOR inhibition resulting in a more complete abrogation of VEGF translation, and ultimately, angiogenesis.

Do Bcl-2 and survivin help distinguish benign from malignant B-cell lymphoid aggregates in bone marrow biopsies?

Bcl-2 and survivin are cellular proteins that are known to be inhibitors of apoptosis and are commonly found in malignant tissues, including lymphomas. In previous studies, it has been shown that staining for bcl-2 can help distinguish between benign and malignant lymphoid aggregates in bone marrow biopsies. To determine whether staining for survivin expression in lymphoid aggregates can aid investigators in making this clinically important distinction, we stained bone marrow biopsies from 10 patients with benign lymphoid aggregates, and 15 malignant ones derived from B cells (six mantle cell, four follicular cells, two diffuse large cell, two small lymphocytic cell, and one marginal zone lymphoma) with antibodies to CD3, CD20, bcl-2, and survivin by an indirect immunoperoxidase technique. Whereas staining for bcl-2 was significantly stronger in the malignant lymphoid aggregates (P=0.001), both the control and malignant cases were almost uniformly negative for survivin expression. Only three cases (two mantle cell and one small lymphocytic lymphoma) showed very faint expression of survivin. Although bcl-2 and survivin both act to inhibit apoptosis, their expressions do not parallel each other. Survivin is not significantly expressed in either benign or malignant bone marrow aggregates, and therefore measuring its expression does not help distinguish benign from malignant B-cell bone marrow lymphoid aggregates.

Detection of monoclonality of the immunoglobulin heavy chain gene in thyroid malignant lymphoma by vectorette polymerase chain reaction

Distinguishing between thyroid malignant lymphoma and lymphocytic thyroiditis (Hashimoto's thyroiditis) is quite difficult and problematic. B cell lymphomas display clonal Ig heavy-chain (IgH) gene rearrangement, and Southern blot hybridization (SBH) is often used for detection of the monoclonality of the IgH gene. However, SBH is often problematic because it requires a large volume of samples. We examined the efficiency in detecting the monoclonality of IgH gene in thyroid malignant lymphomas by vectorette PCR, which we started with only 200 ng of genomic DNA. Monoclonality was detected in 36 of 47 (76.6%) malignant lymphomas, whereas it was not detected in 10 samples of tissue of Hashimoto's thyroiditis. The sensitivity was almost the same as that with SBH in which monoclonality was detected in 33 of 45 (73.3%) malignant lymphomas. These results suggest that vectorette PCR may be a substitute for SBH, and because it requires only a small volume of samples, it may be used in the analysis of aspiration biopsies.

Inhibitor of apoptosis proteins: new therapeutic targets in hematological cancer?

Apoptosis is an essential process for the selection and survival of lymphocytes. Resistance to apoptosis can promote malignant transformation of hematopoietic cells. Proteins that regulate apoptosis may therefore be critically involved in the development of hematological cancer. A delicate balance between pro- and antiapoptotic mechanisms determines whether a cell death signal can activate the execution of the apoptotic cell death program. The family of inhibitor of apoptosis (IAP) proteins is a recently identified, novel category of apoptosis-regulatory proteins. IAPs can inhibit the activation of caspases that are the executioners of apoptosis, activated by both the extrinsic and intrinsic pathway. IAPs may thereby set the threshold for apoptosis-activation and play a key role in the regulation of apoptotic cell death. IAPs themselves are also subject to strict regulation through feedback mechanisms. This paper focuses on the role of IAP family proteins in the regulation of apoptosis and discusses implications for their involvement in cancer and possible use for cancer therapy, especially in leukemias and lymphomas.

In vivo antitumor effects of the mTOR inhibitor CCI-779 against human multiple myeloma cells in a xenograft model

In vitro studies indicate the therapeutic potential of mTOR inhibitors in treating multiple myeloma. To provide further support for this potential, we used the rapamycin analog CCI-779 in a myeloma xenograft model. CCI-779, given as 10 intraperitoneal injections, induced significant dose-dependent, antitumor responses against subcutaneous growth of 8226, OPM-2, and U266 cell lines. Effective doses of CCI-779 were associated with modest toxicity, inducing only transient thrombocytopenia and leukopenia. Immunohistochemical studies demonstrated the antitumor responses were associated with inhibited proliferation and angiogenesis, induction of apoptosis, and reduction in tumor cell size. Although CCI-779-mediated inhibition of the p70 mTOR substrate was equal in 8226 and OPM-2 tumor nodules, OPM-2 tumor growth was considerably more sensitive to inhibition of proliferation, angiogenesis, and induction of apoptosis. Furthermore, the OPM-2 tumors from treated mice were more likely to show down-regulated expression of cyclin D1 and c-myc and up-regulated p27 expression. Because earlier work suggested heightened AKT activity in OPM-2 tumors might induce hypersensitivity to mTOR inhibition, we directly tested this by stably transfecting a constitutively active AKT allele into U266 cells. The in vivo growth of the latter cells was remarkably more sensitive to CCI-779 than the growth of control U266 cells.