Biology and oncogenicity of the Kaposi sarcoma herpesvirus K1 protein

The Kaposi sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8, is a gammaherpesvirus etiologically linked to the development of Kaposi sarcoma, primary effusion lymphomas, and multicentric Castleman disease in humans. KSHV is unique among other human herpesviruses because of the elevated number of viral products that mimic human cellular proteins, such as a viral cyclin, a viral G protein-coupled receptor, anti-apoptotic proteins (e.g. v-bcl2 and v-FLIP), viral interferon regulatory factors, and CC chemokine viral homologues. Several KSHV products have oncogenic properties, including the transmembrane K1 glycoprotein. KSHV K1 is encoded in the viral ORFK1, which is the most variable portion of the viral genome, commonly used to discriminate among viral genotypes. The extracellular region of K1 has homology with the light chain of lambda immunoglobulin, and its cytoplasmic region contains an immunoreceptor tyrosine-based activation motif (ITAM). KSHV K1 ITAM activates several intracellular signaling pathways, notably PI3K/AKT. Consequently, K1 expression inhibits proapoptotic proteins and increases the life-span of KSHV-infected cells. Another remarkable effect of K1 activity is the production of inflammatory cytokines and proangiogenic factors, such as vascular endothelial growth factor. KSHV K1 immortalizes primary human endothelial cells and transforms rodent fibroblasts in vitro; moreover, K1 induces tumors in vivo in transgenic mice expressing this viral protein. This review aims to consolidate and discuss the current knowledge on this intriguing KSHV protein, focusing on activities of K1 that can contribute to the pathogenesis of KSHV-associated human cancers. Copyright © 2015 John Wiley & Sons, Ltd.

Sarcoma histiocítico: análise molecular pela técnica de hibridação genômica comparativa, microRNA e imunoistoquímica

Pós-graduação em Patologia - FMB

Pulmonary artery sarcoma: a rare disease

Pulmonary artery sarcomas (PAS) are rare and probably incurable tumours. The clinical manifestations are non-specific and very similar to that of patients with thromboembolic disease, resulting in delay of the correct diagnosis and proper treatment. We report the case of a 66-year-old woman with PAS diagnosed by computed tomography guided biopsy. Chemotherapy treatment was initiated but the patient died 11 months after diagnosis.

A rare case of iatrogenic gingival Kaposi's sarcoma

Kaposi's sarcoma is an angioproliferative tumour rarely found in the oral cavity. We present the 3rd case of iatrogenic gingival Kaposi's sarcoma reported in the English-language literature which developed in a young patient 5 years after a renal transplant and discuss their histological features and differential diagnosis. (c) 2011 European Association for Cranio-Maxillo-Facial Surgery.

Alterazioni dell'immunità umorale nei pazienti con sarcoma di Kaposi classico: caratterizzazione dei linfociti B circolanti e delle loro sottopopolazioni

Objectives: Human Herpesvirus 8 (HHV-8) is the etiological agent of Kaposi’s Sarcoma (KS) and it is also associated with two B cell lymphoproliferative diseases: primary effusion lymphoma (PEL), and the plasmablastic form of multicentric Castelman’s disease (MCD). HHV-8 establishes persistent infection in the host with tropism for multiple cell types. In KS patients, the virus is found in tumor-spindle cells, peripheral blood monocytes, endothelial progenitor circulating cells, T and B lymphocytes. Peripheral B cells represent one of the major virus reservoir, but the consequences of HHV-8 infection of these cells have been poorly characterized. Therefore, in this study the frequency, the immunophenotypic profile and the functional activity of different peripheral B cell subsets in patients with classic KS (cKS) was analysed in order to identify potential alterations of these cells. The classic variant of KS is ideal to perform such studies, as it lacks confounding factors such as HIV or EBV infection and immunosuppression. Methods: Whole-blood samples from patients with the classical form of KS (cKS) (n=62) and healthy age and sex-matched seronegative controls (HSN) (n=43) were analyzed by multiparametric flow-cytometry to determine the frequency of B cells and their subpopulations, as well as their surface expression of immunoglobulins and activation markers. Results: The frequency of circulating B cells was significantly higher in cKS patients than in controls. In particular, the analysis of the B cell subsets revealed a higher frequency of naïve B cells (CD19+CD27-), among which transitional CD19+CD38highCD5+ and pre-naïve (CD27-CD38intCD5+ ) B cells demonstrated an expansion. Memory B cells (CD19+CD27+) did not differ between the two study groups, except from a higher frequency of CD19+CD27+IgM+IgD+ B cells, the typical phenotype of marginal zone (MZ) B cells, in cKS patients. The characterization of membrane surface activation markers showed lower levels of the activation marker HLA-DR only on CD27- B cells, while CD80 and CD86 were less represented in all the the B cells from cKS patients. Moreover, B cells from cKS patients were smaller and with less granules than the ones from controls. Conclusion: Taken together, these results clearly indicate that circulating B cells are altered in patients with cKS, showing an expansion of the immature phenotypes. These B cell alterations may be due to an indirect viral effect rather than to a direct one: the cytokines expressed in the microenvironment typical of cKS may cause a faster release of immature cells from the bone marrow and a lower grade of peripheral differentiation, as already suggested for other chronic viral infections such as HIV and HCV. Further studies will be necessary to understand how these alterations contribute to the pathogenesis of KS and, eventually, to the different clinical evolution of the disease.

Identificazione di fattori trascrizionali associati al differenziamento neurale in cellule di sarcoma di Ewing: ruolo di NF-kB

Il sarcoma di Ewing (ES) è un tumore maligno pediatrico dell’apparato scheletrico; è associato a una traslocazione specifica codificante la proteina di fusione EWS-FLI1 e all’alta espressione di CD99, una glicoproteina di membrana fisiologicamente coinvolta in diversi processi biologici. EWS-FLI1 e CD99, sono riportati avere ruoli divergenti nella modulazione della malignità e del differenziamento di ES. CD99 inoltre è riportato modulare il pathway di MAPK, il quale interagendo con molteplici fattori di trascrizione partecipa a processi di proliferazione e differenziamento. In questo studio abbiamo investigato in due linee cellulari di ES silenziate per CD99 (TC-71shCD99 e IOR/CARshCD99) l’attività basale di diversi fattori trascrizionali quali: NF-kBp65, AP1, Elk-1, E2F e CREB. L’unico fattore trascrizionale statisticamente significativo è risultato essere NF-kBp65 e abbiamo valutato il suo ruolo nel differenziamento neurale di cellule di ES e la relazione con EWS-FLI1 e CD99. L’attività trascrizionale di NF-kB è stata valutata attraverso gene reporter assay in linee cellulari di ES a diversa espressione di CD99, EWS-FLI1 e NF-kB stesso. Il differenziamento neurale è stato valutato come espressione di βIII-Tubulin in immunofluorescenza. Il silenziamento di CD99 induce una down-modulazione dell’attività trascrizionale di NF-kB, mentre il knockdown di EWS-FLI1 ne induce un’aumento. Inoltre, il silenziamento di EWS-FLI1 non è in grado di contrastare la riduzione dell’attività di NF-kB osservata dopo silenziamento di CD99, suggerendo un ruolo dominante del CD99 nel signaling di NF-kB. Cellule deprivate di CD99 ma non di EWS-FLI1, mostrano un fenotipo differenziato in senso neurale, fenotipo che viene perso quando le cellule sono indotte a sovraesprimere NF-kB. Inoltre, in cellule CD99 positive, il silenziamento di NF-kB induce un leggero differenziamento neurale. In conclusione, questi dati hanno evidenziato il ruolo di NF-kB nel differenziamento di cellule di ES e che potrebbe essere un potenziale target nel ridurre la progressione di questo tumore.

Cell death mechanisms triggered by monoclonal antibodies against CD99 in Ewing sarcoma: Cross-talk between MDM2, IGF-1R and Ras/MAPK

CD99 is a 32 kDa transmembrane protein whose high expression characterizes Ewing sarcoma (ES), a very aggressive pediatric bone tumor. In addition to its diagnostic value, CD99 has therapeutic potential since it leads to rapid and massive ES cell death when engaged with specific antibodies. Here a novel mechanism of cell death triggered via CD99 is shown, leading, ultimately, to the appearance of macropinocytotic vescicles. Anti-CD99 mAb 0662 induces MDM2 ubiquitination and degradation, which causes not only a p53 reactivation but also the IGF-1R induction and its subsequent internalization; CD99 results internalized together with IGF-1R inside endosomes, but then the two molecules display a different sorting: CD99 is degraded, while IGF-1R is recycled on the surface, causing, as a final step, the up-regulation of RAS-MAPK. High-expressing CD99 mesenchymal stem cells show mild Ras induction but no p53 activation and escape cell death, but in presence of EWS/FLI1 mesenchymal stem cells expressing CD99 show a stronger Ras induction and a p53 reactivation, leading to a significant cell death rate. We propose that CD99 triggering in a EWS/FLI1-driven oncogenetic context creates a synergy between RAS upregulation and p53 activation in ES cells, leading to cell death. Moreover, our data rule out possible concerns on toxicity related to the broad CD99 expression in normal tissues and provide the rationale for the therapeutic use of anti-CD99 MAbs in the clinic.

IGF system, CD99 and tumor-specific chromosomal translocations: evaluation of their cross-talk and definition of their role in Ewing sarcoma and prostate cancer

Aberrant expression of ETS transcription factors, including FLI1 and ERG, due to chromosomal translocations has been described as a driver event in initiation and progression of different tumors. In this study, the impact of prostate cancer (PCa) fusion gene TMPRSS2-ERG was evaluated on components of the insulin-like growth factor (IGF) system and the CD99 molecule, two well documented targets of EWS-FLI1, the hallmark of Ewing sarcoma (ES). The aim of this study was to identify common or distinctive ETS-related mechanisms which could be exploited at biological and clinical level. The results demonstrate that IGF-1R represents a common target of ETS rearrangements as ERG and FLI1 bind IGF-1R gene promoter and their modulation causes alteration in IGF-1R protein levels. At clinical level, this mechanism provides basis for a more rationale use of anti-IGF-1R inhibitors as PCa cells expressing the fusion gene better respond to anti-IGF-1R agents. EWS-FLI1/IGF-1R axis provides rationale for combination of anti-IGF-1R agents with trabectedin, an alkylator agent causing enhanced EWS-FLI1 occupancy on the IGF-1R promoter. TMPRSS2-ERG also influences prognosis relevance of IGF system as high IGF-1R correlates with a better biochemical progression free survival (BPFS) in PCa patients negative for the fusion gene while marginal or no association was found in the total cases or TMPRSS2-ERG-positive cases, respectively. This study indicates CD99 is differentially regulated between ETS-related tumors as CD99 is not a target of ERG. In PCa, CD99 did not show differential expression between TMPRSS2-ERG-positive and –negative cells. A direct correlation was anyway found between ERG and CD99 proteins both in vitro and in patients putatively suggesting that ERG target genes comprehend regulators of CD99. Despite a little trend suggesting a correlation between CD99 expression and a better BPFS, no clinical relevance for CD99 was found in the field of prognostic biomarkers.

Early occurrence of lung adenocarcinoma and breast cancer after radiotherapy of a chest wall sarcoma in a patient with a de novo germline mutation in TP53

We report a 26-year-old female patient who was diagnosed within 4 years with chest sarcoma, lung adenocarcinoma, and breast cancer. While her family history was unremarkable, DNA sequencing of TP53 revealed a germline de novo non-sense mutation in exon 6 p.Arg213X. One year later, she further developed a contralateral ductal carcinoma in situ, and 18 months later a jaw osteosarcoma. This case illustrates the therapeutic pitfalls in the care of a young cancer patient with TP53 de novo germline mutations and the complications related to her first-line therapy. Suggestion is made to use the less stringent Chompret criteria for germline TP53 mutation screening. Our observation underlines the possibly negative effect of radiotherapy in generating second tumors in patients with a TP53 mutation. We also present a review of six previously reported cases, comparing their cancer phenotypes with those generally produced by TP53 mutations.

Prevalence and predictors of kaposi sarcoma herpes virus seropositivity: a cross-sectional analysis of HIV-infected adults initiating ART in Johannesburg, South Africa

Background Kaposi sarcoma (KS) is the most common AIDS-defining tumour in HIV-infected individuals in Africa. Kaposi sarcoma herpes virus (KSHV) infection precedes development of KS. KSHV co-infection may be associated with worse outcomes in HIV disease and elevated KSHV viral load may be an early marker for advanced HIV disease among untreated patients. We examined the prevalence of KSHV among adults initiating antiretroviral therapy (ART) and compared immunological, demographic and clinical factors between patients seropositive and seronegative for KSHV. Results We analyzed cross-sectional data collected from 404 HIV-infected treatment-naïve adults initiating ART at the Themba Lethu Clinic, Johannesburg, South Africa between November 2008 and March 2009. Subjects were screened at ART initiation for antibodies to KSHV lytic K8.1 and latent Orf73 antigens. Seropositivity to KSHV was defined as positive to either lytic KSHV K8.1 or latent KSHV Orf73 antibodies. KSHV viremia was determined by quantitative PCR and CD3, 4 and 8 lymphocyte counts were determined with flow cytometry. Of the 404 participants, 193 (48%) tested positive for KSHV at ART initiation; with 76 (39%) reactive to lytic K8.1, 35 (18%) to latent Orf73 and 82 (42%) to both. One individual presented with clinical KS at ART initiation. The KSHV infected group was similar to those without KSHV in terms of age, race, gender, ethnicity, smoking and alcohol use. KSHV infected individuals presented with slightly higher median CD3 (817 vs. 726 cells/mm3) and CD4 (90 vs. 80 cells/mm3) counts than KSHV negative subjects. We found no associations between KSHV seropositivity and body mass index, tuberculosis status, WHO stage, HIV RNA levels, full blood count or liver function tests at initiation. Those with detectable KSHV viremia (n = 19), however, appeared to present with signs of more advanced HIV disease including anemia and WHO stage 3 or 4 defining conditions compared to those in whom the virus was undetectable. Conclusions We demonstrate a high prevalence of KSHV among HIV-infected adults initiating ART in a large urban public-sector HIV clinic. KSHV viremia but not KSHV seropositivity may be associated with markers of advanced HIV disease.

High-grade supraclavicular soft tissue sarcoma as secondary malignancy after successful treatment of acute myeloid leukemia: case report and literature review

It is well known that the treatment protocols for hematopoetic neoplasms carry a high risk of long-term oncogenicity. However, few reports have been published of sarcomas as secondary malignancies. An unusual case report of a soft tissue sarcoma appearing as a secondary cancer is presented, with a review of the published data. The present report involves a soft tissue sarcoma of the neck that occurred 18 years after curative treatment of acute myeloid leukemia by induction chemotherapy and bone marrow transplantation. Consecutive graft-versus-host disease affected the cervical skin. Soft tissue sarcomas appearing as secondary tumors are rare in oncology. The presented case describes the appearance of a sarcoma 18 years after curative treatment of acute myeloid leukemia. This is only the second case of this type reported in published studies.

Is there a need for dedicated bone imaging in addition to 18F-FDG PET/CT imaging in pediatric sarcoma patients?

Many children with sarcomas undergo whole body 2-deoxy-2-((18)F)fluoro-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) and technetium methylene diphosphonate ((99)Tc-MDP) studies. It is unknown whether the combination of both tests results in more accurate detection of bone lesions than (18)F-FDG- PET/CT alone.