Phenotypic and Functional Analysis of Fas (CD95) Expression in Primary Central Nervous System Lymphoma of Patients With Acquired Immunodeficiency Syndrome

Advanced Pediatric Diffuse Pontine Glioma Murine Models Pave the Way towards Precision Medicine

Diffuse intrinsic pontine gliomas (DIPGs) account for ~15% of pediatric brain tumors, which invariably present with poor survival regardless of treatment mode. Several seminal studies have revealed that 80% of DIPGs harbor H3K27M mutation coded by HIST1H3B, HIST1H3C and H3F3A genes. The H3K27M mutation has broad effects on gene expression and is considered a tumor driver. Determination of the effects of H3K27M on posttranslational histone modifications and gene regulations in DIPG is critical for identifying effective therapeutic targets. Advanced animal models play critical roles in translating these cutting-edge findings into clinical trial development. Here, we review current molecular research progress associated with DIPG. We also summarize DIPG animal models, highlighting novel genomic engineered mouse models (GEMMs) and innovative humanized DIPG mouse models. These models will pave the way towards personalized precision medicine for the treatment of DIPGs.

Immunohistochemical analysis of cleaved caspase-3 detects high level of apoptosis frequently in diffuse large B-cell lymphomas of the central nervous system

The purpose of the present paper was to examine the level of apoptosis and the relationships among apoptosis, apoptosis-associated proteins, and proliferating potential in lymphoma tissues to clarify the characteristics of apoptosis in diffuse large B-cell lymphomas (DLBCL) of the central nervous system (CNS). The formalin-fixed, paraffin-embedded tissues of CNS and non-CNS DLBCL (20 cases each) were studied by terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) and immunohistochemistry, using antibodies against single-stranded DNA (ssDNA), cleaved caspase-3, bcl-2, bax, p53, Fas and Ki-67. The cleaved caspase-3 immunohistochemistry detected apoptosis of the lymphoma cells most sensitively compared to TUNEL and ssDNA immunohistochemistry. High expression (grade + + or + + +) of cleaved caspase-3 was found more frequently in CNS DLBCL (11 cases, 55%) than non-CNS DLBCL (three cases, 15%; P = 0.009). Bax-positivity of lymphoma cells was increased in six cases of CNS DLBCL, which also showed high positivity of cleaved caspase-3. There was no significant correlation between the cleaved caspase-3-positivity and the Ki-67 positivity. The present study indicates that the number of apoptotic cells and expression level of cleaved caspase-3 were significantly higher in CNS DLBCL than non-CNS DLBCL, and that the correlation of bax and cleaved caspase-3 expression was often present in CNS DLBCL.

Characteristics of nitric oxide-induced apoptosis and its target cells in mitogen-stimulated peripheral blood mononuclear cells from HIV+ subjects

The phenomenon of apoptosis observed in lymphoid cells from HIV+ subjects is an important factor contributing to their massive depletion. Several studies have identified nitric oxide (NO) as one of the molecules involved in the apoptosis phenomenon observed during HIV infection. It has been shown that HIV-derived gp120 enhances NO synthesis in cultured cells from HIV+ individuals. Therefore, we tested the potential of two nitric oxide synthase (NOS) inhibitors with different mechanisms of action as preventive agents of in vitro apoptosis, in peripheral blood mononuclear cells (PBMC) from HIV+ subjects. PBMC isolated from these patients always showed higher apoptosis levels than normal subjects, a fact that correlated with overproduction of NO and with reduction of mitochondrial transmembrane potential in these cells. We identified the CD8+ T lymphocyte sub-population as the major apoptosis target in PBMC cultures. Treatment with NO inhibitors N(G)-monomethyl-L-arginine (L-NMMA) and dexamethasone (DEX) inhibited spontaneous and mitogen-induced apoptosis, while reducing mitochondrial alterations in PBMC from both normal (30%) and HIV+ (70%) subjects. The development of apoptosis in target cells correlated with their mitochondrial transmembrane potential impairment and with increased expression of Fas (CD95) molecules. These results offer additional alternatives for the manipulation of cellular depletion in HIV disease.

GM-CSF and IL-2 induce specific cellular immunity and provide protection against Epstein-Barr virus lymphoproliferative disorder

Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD) is a potentially life-threatening complication in immune-deficient patients. We have used the severe combined immune deficient (SCID) mouse engrafted with human leukocytes (hu-PBL-SCID) to evaluate the use of human cytokines in the prevention of EBV-LPD in vivo. Daily low-dose IL-2 therapy can prevent EBV-LPD in the hu-PBL-SCID mouse, but protection is lost if murine natural killer (NK) cells are depleted. Here we demonstrate that combined therapy with human GM-CSF and low-dose IL-2 is capable of preventing EBV-LPD in the hu-PBL-SCID mouse in the absence of murine NK cells. Lymphocyte depletion experiments showed that human NK cells, CD8(+) T cells, and monocytes were each required for the protective effects of GM-CSF and IL-2 combination therapy. This treatment resulted in a marked expansion of human CD3(+)CD8(+) lymphocytes in vivo. Using HLA tetramers complexed with EBV immunodominant peptides, a subset of these lymphocytes was found to be EBV-specific. These data establish that combined GM-CSF and low-dose IL-2 therapy can prevent the immune deficiencies that lead to fatal EBV-LPD in the hu-PBL-SCID mouse depleted of murine NK cells, and they point to a critical role for several human cellular subsets in mediating this protective effect.

Apoptosis and cell proliferation capacity in AKR lymphoma malignancy variants

Dysregulation in apoptotic cell death has recently emerged as a factor in tumorigenesis, but its effect in tumor progression is not yet established. In the present study we evaluated the levels of proliferative and apoptotic cell fractions in a T-cell lymphoma tumor progression model. We compared these features and the expression of apoptosis-related genes in primary tumors of several AKR lymphoma malignancy variants. According to DNA flow cytometry, a considerable proportion of cells (35-40%) was in the proliferative (S + G2/M) phase in all variants, but a slight augmentation with increasing malignancy was noted. Apoptotic cell content was, unexpectedly, the lowest in the less malignant variant. This might be due to the higher content in macrophages observed in this variant, which possibly partly eliminated apoptotic bodies. We found an increase in bcl-2 level with increasing malignancy that was probably counterbalanced by the simultaneous increase observed in the Fas receptor.

Release from apoptosis correlates with tumor progression in the AKR lymphoma

Disturbance of apoptosis is an established factor in tumorigenesis. The role of apoptosis in tumor progression is not yet clear. In the present study we compared the tendency to spontaneous apoptosis (and the proliferative capacity) of tumor cells derived from primary (PT) and metastatic tumor (MT) cells of several AKR lymphoma variants. Apoptosis-related gene expression was also compared. Our results indicate that release from apoptosis has a role in the tumor progression of this T cell lymphoma. At the cellular level, a markedly lower apoptotic tendency was observed in MT than in PT cells. The existence of macrophages only in PT also supports the presence of apoptotic cells in local but not in MTs. By contrast, proliferative capacity does not determine tumor aggressiveness in this system. At the molecular level, we found a higher staining intensity for bcl-2 in MT than in PT cells, suggesting that bcl-2 might be responsible for the reduced apoptosis in MT compared to PT cells. Evidence for p53 overexpression was found in the MT cells of one of the variants but in none of the PT. Comparison of Fas receptor, unexpectedly showed an increased expression in MT versus PT cells, possibly indicating resistance to Fas-induced apoptosis in the MT cells.

Treatment of AIDS-related primary central nervous system lymphoma with zidovudine, ganciclovir, and interleukin 2

AIDS-related primary central nervous system lymphoma (AIDS PCNSL) is a rapidly fatal disease. Conventional therapeutic modalities offer little and new approaches are needed. Previous work has shown that zidovudine (AZT) in combination with other agents is active in retroviral lymphomas. Epstein-Barr virus (EBV) is detected in tumor tissue and cerebrospinal fluid of AIDS PCNSL patients. In a preliminary in vitro study we found that an Epstein-Barr virus-positive B cell line underwent apoptosis on coculture with AZT. This effect was accentuated by the addition of ganciclovir (GCV). We treated five patients with AIDS PCNSL with a regimen consisting of parenteral zidovudine (1.6 g twice daily), ganciclovir (5 mg/kg twice daily), and interleukin 2 (2 million units twice daily). Four of five had an excellent response. Two patients are alive and free of disease 22 and 13 months later; another responded on two separate occasions, 5 months apart, and the last patient responded with a 70-80% regression of tumor but could not be maintained on therapy owing to myelosuppression. We conclude that parenteral zidovudine, ganciclovir, and interleukin 2 is an active combination for AIDS-related central nervous system lymphoma.

Qualitative and quantitative characterization of Fas (APO-1/CD95) on leukemic cells derived from patients with B-cell neoplasms

Expression density and function of Fas (APO-1/CD95) on malignant B-cells, an antigen thought responsible for abnormal tumor biology, remains to be fully understood. Fifty-five cases with B-cell neoplasms of acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), hairy cell leukemia (HCL), B-cell malignant lymphoma (ML), and myeloma (MM) were studied for qualitative and quantitative expression and function of Fas using flow cytometry and annexin-V staining methods. Fas expression was flow cytometrically unimodal with heterogeneous density and showed quantitatively characteristic features among different diseases; weak in ALL, faint in CLL, moderate in HCL, and strong in ML, respectively. Not only full-length but also alternatively spliced truncated mRNAs were detected even in leukemic B-cells with qualitatively faint or negative Fas, and then band density of the former transcripts by RT-PCR was correlated to the Fas protein expression level. Short-term culture of freshly isolated cells gave rise to increases of Fas density and susceptibility for apoptosis, suggesting that the mRNA and inducible Fas are functional at least in vitro. These results show that Fas is a biological marker for characterizing B-cell neoplasms reflecting various stages of B-cell ontogeny and may have clinical utility as a therapeutic strategy.

Neurosurgery at the State University of New York at Buffalo

WALLACE HAMBY STARTED the first practice dedicated to neurosurgery in Buffalo in 1933. Several years later, he was able to establish a residency program and became nationally known for his treatments of cerebral aneurysms and arteriovenous malformations. It was up to Louis Bakay to create an academic department within the State University of New York system and to incorporate an active and successful research program. This tradition has been expanded and enriched under the present leadership of L. Nelson Hopkins. The department is now well recognized, has 10 full-time staff members, and performs approximately 2000 procedures annually. There are numerous research opportunities available, at both the resident and fellowship levels.