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Deficiency of the tumor suppressor Merlin causes development of schwannoma, meningioma, and ependymoma tumors, which can occur spontaneously or in the hereditary disease neurofibromatosis type 2 (NF2). Merlin mutations are also relevant in a variety of other tumors. Surgery and radiotherapy are current first-line treatments; however, tumors frequently recur with limited treatment options. Here, we use human Merlin-negative schwannoma and meningioma primary cells to investigate the involvement of the endogenous retrovirus HERV-K in tumor development. HERV-K proteins previously implicated in tumorigenesis were overexpressed in schwannoma and all meningioma grades, and disease-associated CRL4 DCAF1 and YAP/TEAD pathways were implicated in this overexpression. In normal Schwann cells, ectopic overexpression of HERV-K Env increased proliferation and upregulated expression of c-Jun and pERK1/2, which are key components of known tumorigenic pathways in schwannoma, JNK/c-Jun, and RAS/RAF/MEK/ERK. Furthermore, FDA-approved retroviral protease inhibitors ritonavir, atazanavir, and lopinavir reduced proliferation of schwannoma and grade I meningioma cells. These results identify HERV-K as a critical regulator of progression in Merlin-deficient tumors and offer potential strategies for therapeutic intervention. SIGNIFICANCE: The endogenous retrovirus HERV-K activates oncogenic signaling pathways and promotes proliferation of Merlin-deficient schwannomas and meningiomas, which can be targeted with antiretroviral drugs and TEAD inhibitors., (©2021 American Association for Cancer Research.)

Meningeal metastasis is a fatal complication of breast cancer that affects 5-8% of patients. When cancer cells seed in the meninges, their subsequent growth results in severe neurological complications involving the cranial nerves, cerebrum and spinal cord, limiting life expectancy to less than 4 months. The incidences of meningeal metastases increase with prolonged lifespan resulting from treatment advances for primary breast cancer and their metastases. Currently, there is no cure. Aggressive multimodal therapies such as radiation and chemotherapy (intra-cerebrospinal fluid (CSF) and systemic) are ineffective. Therapeutic agents are often quickly cleared from the CSF, while higher doses that can achieve a therapeutic response are highly toxic. The secure guarding of the subarachnoid space by the blood-brain barrier on one side and the blood-CSF barrier on the other prevents chemotherapy from reaching cancer cells in the meninges. These challenges with treating meningeal metastases highlight the urgent need for a new therapeutic modality. An ideal treatment would be an agent that avoids rapid clearance, remains within the CSF, reaches the meninges and selectively destroys tumor cells. Replication conditional oncolytic herpes simplex virus type 1 (HSV-1) may be effective in this regard. Viral oncolysis, the destruction of cancer cells by replicating virus, is under clinical investigation for cancers that are unresponsive to current therapies. It is based on the model of multiple cycles of lytic virus replication in cancer cells that amplify the injected dose. The therapeutic potential of oncolytic HSV-1 for breast cancer meningeal metastases is discussed here. HSV-1 could be a potential novel treatment for meningeal metastases that can be translated to the clinic.

Background: Leptomeningeal metastases occur in 2%-5% of patients with breast cancer and have an exceptionally poor prognosis. The blood-brain and blood-meningeal barriers severely inhibit successful chemotherapy. We have developed a straightforward method to induce antitumor memory T-cells using a Her2/neu targeted vesicular stomatitis virus. We sought to determine whether viral infection of meningeal tumor could attract antitumor memory T-cells to eradicate the tumors., Methods: Meningeal implants in mice were studied using treatment trials and analyses of immune cells in the tumors., Results: This paper demonstrates that there is a blood-meningeal barrier to bringing therapeutic memory T-cells to meningeal tumors. The barrier can be overcome by viral infection of the tumor. Viral infection of the meningeal tumors followed by memory T-cell transfer resulted in 89% cure of meningeal tumor in 2 different mouse strains. Viral infection produced increased infiltration and proliferation of transferred memory T-cells in the meningeal tumors. Following viral infection, the leukocyte infiltration in meninges and tumor shifted from predominantly macrophages to predominantly T-cells. Finally, this paper shows that successful viral therapy of peritoneal tumors generates memory CD8 T-cells that prevent establishment of tumor in the meninges of these same animals., Conclusions: These results support the hypothesis that a virally based immunization strategy can be used to both prevent and treat meningeal metastases. The meningeal barriers to cancer therapy may be much more permeable to treatment based on cells than treatment based on drugs or molecules., (© The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (SCC) is associated with high cure rates and distant metastases are rare., Methods and Results: We report a case of a 61-year-old man presenting with acute left-sided weakness. An enhancing dural mass was noted and resected. Histology revealed p16-positive SCC. Further workup revealed a p16-positive right tonsillar primary with ipsilateral nodal disease and was classified as T2N2bM1. The patient underwent whole brain irradiation and definitive chemoradiation with curative intent. Complete clinical response was achieved and the patient continues to be disease-free 6 months posttreatment., Conclusion: HPV-associated oligometastatic oropharyngeal SCC is a rare entity that may have a unique natural history and behavior. Given the excellent treatment response and prognosis of HPV-positive disease in general, these patients may be appropriate for definitive treatment approaches., (© 2014 Wiley Periodicals, Inc.)

Vesicular stomatitis virus (VSV) is neuropathogenic in rodents but can be attenuated 50-fold by engineering the mouse interferon-beta (IFN-β) gene into its genome. Intravenously administered VSVs encoding IFN-β have potent activity against subcutaneous tumors in the 5TGM1 mouse myeloma model, without attendant neurotoxicity. However, when 5TGM1 tumor cells were seeded intravenously, virus-treated mice with advanced myeloma developed clinical signs suggestive of meningoencephalitis. Co-administration of a known active antimyeloma agent did not prolong survival, further suggesting that deaths were due to viral toxicity, not tumor burden. Histological analysis revealed that systemically administered 5TGM1 cells seed to the CNS, forming meningeal tumor deposits, and that VSV infects and destroys these tumors. Death is presumably a consequence of meningeal damage and/or direct transmission of virus to adjacent neural tissue. In light of these studies, extreme caution is warranted in clinical testing of attenuated VSVs, particularly in patients with CNS tumor deposits.

Epstein Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is endemic in Southeast Asia, and the plasma level of EBV DNA is a highly sensitive marker of disease recurrence following radiotherapy. Leptomeningeal recurrence from NPC is extremely rare and difficult to diagnose; only 4 cases have been reported in the literature. We report a case of leptomeningeal recurrence in NPC that was diagnosed using imaging and plasma and cerebrospinal fluid EBV DNA assays, followed by a review of the literature., (Copyright 2008 S. Karger AG, Basel.)

Gliomas are the most frequent primary brain tumors in humans. Many studies have been carried out on their etiology; however, the only confirmed risk factors are hereditary predisposing conditions and high dose of ionizing radiation. Recently, human cytomegalovirus (HCMV) gene products and nucleic acids were reported to be present in all of 27 glioma samples investigated in contrast to other brain tissues, and it was hypothesized that HCMV might play a role in glioma pathogenesis. To evaluate these findings, samples of 40 gliomas, 31 meningiomas, and 6 acoustic neurinomas (ACNs) were analyzed for the presence of HCMV macromolecules using polymerase chain reaction (PCR) and immunohistochemistry. Additionally, corresponding blood samples from 72 patients were analyzed for the presence of HCMV DNA to check for a possible contamination of tumor tissues with HCMV-infected blood cells. No HCMV DNA sequences were found, neither in brain tumor tissues nor in corresponding blood samples. Immunohistochemistry did not detect HCMV-specific proteins. Addressing a possible role of other herpesviruses as has been suggested in seroepidemiological studies, seroprevalence of antibodies to HCMV, herpes simplex virus (HSV), Epstein-Barr virus (EBV), and varicella-zoster virus (VZV) were determined by enzyme-linked immunosorbent assay (ELISA). Serological analyses of brain tumor patients showed no significant differences in the prevalences of antibodies to HCMV, HSV, EBV, or VZV compared to the general population. Thus, the data of the present study do not support the hypothesis of an association of herpesviruses with the development of primary brain tumors.

We describe the clinical, radiologic, surgical, and pathologic findings of a 29-year-old Peruvian human immunodeficiency virus-infected man with a primary parasellar meningeal leiomyosarcoma involving the left lesser esphenoidal wing and the cavernous sinus. Over a period of 13 months, he developed headache, vomiting, insomnia, and diplopia. Magnetic resonance imaging revealed a left parasellar extra-axial mass that was isointense in T1, hypointense in T2, and gadolinium-enhanced. The patient underwent subtotal resection of the tumor. The neoplasm was composed of spindle cells with smooth-muscle features. It showed moderate atypia, inconspicuous nucleoli, and scanty mitosis. No tumor necrosis was detected. The immunohistochemistry revealed strong positivity for vimentin, desmin, and smooth-muscle alpha-actin. A low-grade leiomyosarcoma was diagnosed. The in situ hybridization showed positive nuclear reactivity for Epstein-Barr virus-encoded RNA. The immunohistochemistry was negative for Epstein-Barr virus latent membrane protein 1. The main differential diagnosis of primary meningeal smooth-muscle tumors includes meningioma and peripheral nerve sheath tumors. Epstein-Barr virus has been demonstrated in most smooth-muscle tumors associated with acquired immune deficiency syndrome (AIDS). Primary meningeal smooth-muscle tumors, exceedingly rare neoplasms, remarkably affect young adults with AIDS. Comparatively, most AIDS-related visceral (nonmeningeal) smooth-muscle tumors have been reported in children. The permissiveness and tumorigenesis associated with Epstein-Barr virus may depend on the age of human immunodeficiency virus infection.

Brain and leptomeningeal metastases are common in breast cancer patients and our current treatments are ineffective. Reovirus type 3 is a replication competent, naturally occurring virus that usurps the activated Ras-signaling pathway (or an element thereof) of tumor cells and lyses them but leaves normal cells relatively unaffected. In this study we evaluated reovirus as an experimental therapeutic in models of central nervous system (CNS) metastasis from breast cancer. We found all breast cancer cell lines tested were susceptible to reovirus, with > 50% of these cells lysed within 72 h of infection. In vivo neurotoxicity studies showed only mild local inflammation at the injection site and mild communicating hydrocephalus with neither diffuse encephalitis nor behavioral abnormalities at the therapeutically effective dose of reovirus (intracranial) (ie 10(7) plaque-forming units) or one dose level higher. In vivo, a single intratumoral administration of reovirus significantly reduced the size of tumors established from two human breast cancer cell lines and significantly prolonged survival. Intrathecal administration of reovirus also remarkably prolonged survival in an immunocompetent racine model of leptomeningeal metastases. These data suggest that the evaluation of reovirus as an experimental therapeutic for CNS metastases from breast cancer is warranted.

We describe a rare case of diffuse leptomeningeal oligodendrogliomatosis associated with the human herpes virus 6 variant A (HHV-6 A). A 2-year-old boy presented with progressive neurological symptoms and hydrocephalus. The patient had a VP shunt placement but did not fully recover. HHV-6 A was detected in both CSF and serum by nested PCR. His symptoms improved repeatedly, but temporarily, on antiviral treatment. An open brain biopsy, ten months after presentation, revealed leptomeningeal tumour as well as the presence of viral DNA in the tumour tissue. The role of HHV-6 A could be that of a reactivated opportunist. However, this case also raises the question whether this neurotropic virus, with malignant transforming properties in vitro, may have a role in pathogenesis in some cases of brain malignancy.

Recombinant virus 7 (R7), a spontaneous deletion mutant of SV7, which is itself a molecular clone of Moloney murine sarcoma virus 124 (MoMuSV 124), induces brain lesions and tumors of the subcutaneous tissue and spleen in all infected mice. In contrast, SV7 only induces tumors of the spleen and subcutaneous tissues. One of the genetic differences between R7 and SV7 is that R7 encodes a Gag-Mos protein whereas SV7 encodes an Env-Mos protein. To investigate whether the novel R7 gag-mos oncogene is required for brain lesion induction, two viruses (SV7d1 and SVM1) were constructed in which the R7 gag-mos sequences and the adjacent 53 bp of the 5' noncoding sequence were replaced by either the SV7 or myeloproliferative sarcoma virus (MPSV) env-mos oncogenes, respectively. Like R7, SV7d1 and SVM1 induced brain lesions and tumors in the spleen and subcutaneous tissues. A prominent component of R7-, SV7d1-, and SVM1-induced tumors of the brain, subcutaneous tissues, and spleen was the presence of abnormally enlarged cells with eccentric nuclei lining vessels, scattered singly or in small clusters. Their size, localization to the luminal surface of distended vessels, and binding to Bandeiraea simplicifolia (BS-1) lectin, an endothelial cell (EC) marker, suggest that they are most likely transformed ECs. Our findings therefore indicate that the induction of brain lesions is not limited to the expression of the R7 Gag-Mos protein. However, our findings also indicate that expression of the different forms of the Mos protein results in differences in the relative abundance of ECs in brain angioendotheliomas and subcutaneous and spleen tumors induced by these viruses.

Several reports have suggested a role for polyomaviruses in the pathogenesis of human brain tumors. This potential involvement is not conclusively resolved. For the present study, a highly sensitive PCR-assay with fluorescence-labelled primers was developed to search for polyomavirus sequences in human brain tumor and control DNA samples. The assay was shown to detect approximately one viral large T-antigen (TAg) gene per 250 cells. We identified simian virus 40 (SV40)-like sequences in 2/116 medulloblastomas, in 1/131 meningiomas, in 1/25 ependymomas and in 1/2 subependymomas. A single case of ependymoma contained SV40 VP-1 late gene sequences. Moreover, one of the meningioma samples showed JC virus sequences. In contrast, 60 hepatoblastoma samples and 31 brain samples from schizophrenic patients were consistently negative. BK virus sequences were not detectable in any of our samples. Immunohistochemical analysis of two SV40 positive tumor biopsies failed to detect large TAg in the tumor cells. In the JC positive meningioma, immunoreactivity for the viral late gene product (VP-1) was not observed. Our data do not entirely rule out SV40 and JC virus as an initiative agent with a hit-and-run mechanism. However the low frequency of virus sequences and the absence of TAg protein expression argue against a major role of these viruses in the pathogenesis of human medulloblastomas, meningiomas and ependymomas.

Primary effusion lymphoma (PEL) is a rare and distinctive type of B-cell non-Hodgkin's lymphoma (NHL) that occurs primarily, although not exclusively, in patients with AIDS. It usually develops as a lymphomatous effusion in the absence of a tumor mass, characteristically contains the Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8), usually also contains the Epstein-Barr virus (EBV), displays a characteristic cytomorphology bridging immunoblastic and anaplastic large cell lymphoma, often expresses an indeterminate immunophenotype, and a B-cell genotype. Thus far, PEL has been limited almost entirely to the pleural, peritoneal, and pericardial cavities. We describe a NHL occurring in a gay man with AIDS that is typical of PEL in that it arose in a body cavity or space without an associated tumor mass, displays the cytomorphology typical of PEL, is a clonal B-cell neoplasm, and contains KSHV as well as EBV. This case is singularly distinctive in that it is the first case of PEL reported to arise in the subarachnoid space. This unique case further supports the strong association between KSHV and malignant lymphoma arising in body cavities and growing as an effusion.

A 26-year-old male with AIDS presented with a chief complaint of headaches and neck pain. An MRI revealed two enhancing extra-axial dura based masses, one in the area of the left sphenoid wing and one at the level of C2-3. In both cases, microscopic sections showed actin positive spindle cell neoplasms with long slender nuclei, consistent with leiomyomas. Both tumors were positive for Epstein Barr virus by in situ hybridization. This case report serves to emphasize the importance of considering soft tissue tumors such as leiomyoma in the differential diagnosis of mass lesions that occur in the central nervous system in AIDS and discusses the role of EBV in tumorigenesis.

A 35-year-old man infected with human immunodeficiency virus presented with cervical myelopathy of 2 months duration. Clinical and radiographic evaluation revealed a discrete, subdural mass at C-6. At surgery, the mass proved to have a dural attachment and thus clinically, radiographically, and grossly, it resembled meningioma. Histopathological analysis revealed a leiomyosarcoma that stained diffusely for muscle-specific actin. Electron microscopy revealed basal lamina surrounding the tumor cells and intracytoplasmic bundles of myofilaments. Epstein-Barr virus (EBV) was demonstrated within tumor cell nuclei by in situ hybridization for EBER1 messenger RNA and immunohistochemical staining for EBNA2 protein. Epstein-Barr virus latent membrane protein (LMP1) was not detected. This is the first documentation of an EBV-associated smooth-muscle tumor of the dura, and the first demonstration that tumors in this location contain EBV in an unusual form of latency not seen in lymphoid cell lines. With increasing numbers of individuals being afflicted with long-term immunosuppression, EBV-associated dural leiomyoma and leiomyosarcoma may be encountered more frequently in the future.