Transactivation of the CCL5/RANTES gene by Epstein-Barr virus latent membrane protein 1

The CCL5/CCR5 Axis in Cancer Progression

Tumor cells can “hijack” chemokine networks to support tumor progression. In this context, the C-C chemokine ligand 5/C-C chemokine receptor type 5 (CCL5/CCR5) axis is gaining increasing attention, since abnormal expression and activity of CCL5 and its receptor CCR5 have been found in hematological malignancies and solid tumors. Numerous preclinical in vitro and in vivo studies have shown a key role of the CCL5/CCR5 axis in cancer, and thus provided the rationale for clinical trials using the repurposed drug maraviroc, a CCR5 antagonist used to treat HIV/AIDS. This review summarizes current knowledge on the role of the CCL5/CCR5 axis in cancer. First, it describes the involvement of the CCL5/CCR5 axis in cancer progression, including autocrine and paracrine tumor growth, ECM (extracellular matrix) remodeling and migration, cancer stem cell expansion, DNA damage repair, metabolic reprogramming, and angiogenesis. Then, it focuses on individual hematological and solid tumors in which CCL5 and CCR5 have been studied preclinically. Finally, it discusses clinical trials of strategies to counteract the CCL5/CCR5 axis in different cancers using maraviroc or therapeutic monoclonal antibodies.

Analysis of Epstein-Barr virus and cellular gene expression during the early phases of Epstein-Barr virus lytic induction

In order to develop novel host/pathogen real-time PCR assays for routine diagnostic use, early gene expression patterns from both Epstein-Barr virus (EBV) and Raji cells were examined after inducing the lytic life cycle using 12-O-tetradecanoyl-13-phorbol ester and sodium butyrate. Real-time PCR identified several highly induced (>90-fold) EBV lytic genes over a 48 h time course during the lytic induction phase. Latent genes were induced at low levels during this phase. The cellular response to lytic viral replication is poorly understood. Whole human genome microarray analysis identified 113 cellular genes regulated twofold or more by EBV, including 63 upregulated and 46 downregulated genes, over a 24 h time course post-induction. The most upregulated gene was CHI3L1, a chitinase-3-like 1 protein (18.1-fold; P<0.0084), and the most downregulated gene was TYMS, a thymidylate synthetase (-7.6-fold). Gene Ontology enrichment analysis using MetaCore software revealed cell cycle (core), cell cycle (role of anaphase-promoting complex) in cell cycle regulation) and lymphatic diseases as the most significantly represented biological network processes, canonical pathways and disease biomarkers, respectively. Chemotaxis, DNA damage and inflammation (IL-4 signalling) together with lymphoproliferative disorders and non-Hodgkin's lymphoma were significantly represented biological processes and disease biomarkers.

PD-1/CTLA-4 Blockade Inhibits Epstein-Barr Virus-Induced Lymphoma Growth in a Cord Blood Humanized-Mouse Model

Epstein-Barr virus (EBV) infection causes B cell lymphomas in humanized mouse models and contributes to a variety of different types of human lymphomas. T cells directed against viral antigens play a critical role in controlling EBV infection, and EBV-positive lymphomas are particularly common in immunocompromised hosts. We previously showed that EBV induces B cell lymphomas with high frequency in a cord blood-humanized mouse model in which EBV-infected human cord blood is injected intraperitoneally into NOD/LtSz-scid/IL2Rγ^null (NSG) mice. Since our former studies showed that it is possible for T cells to control the tumors in another NSG mouse model engrafted with both human fetal CD34+ cells and human thymus and liver, here we investigated whether monoclonal antibodies that block the T cell inhibitory receptors, PD-1 and CTLA-4, enhance the ability of cord blood T cells to control the outgrowth of EBV-induced lymphomas in the cord-blood humanized mouse model. We demonstrate that EBV-infected lymphoma cells in this model express both the PD-L1 and PD-L2 inhibitory ligands for the PD-1 receptor, and that T cells express the PD-1 and CTLA-4 receptors. Furthermore, we show that the combination of CTLA-4 and PD-1 blockade strikingly reduces the size of lymphomas induced by a lytic EBV strain (M81) in this model, and that this anti-tumor effect requires T cells. PD-1/CTLA-4 blockade markedly increases EBV-specific T cell responses, and is associated with enhanced tumor infiltration by CD4+ and CD8+ T cells. In addition, PD-1/CTLA-4 blockade decreases the number of both latently, and lytically, EBV-infected B cells. These results indicate that PD-1/CTLA-4 blockade enhances the ability of cord blood T cells to control outgrowth of EBV-induced lymphomas, and suggest that PD-1/CTLA-4 blockade might be useful for treating certain EBV-induced diseases in humans.

EBV is a human herpesvirus that remains in the host for life, but is normally well controlled by the host immune response. Nevertheless, EBV causes lymphomas in certain individuals, particularly when T cell function is impaired. Antibodies against two different inhibitory receptors on T cells, PD-1 and CTLA-4, have been recently shown to improve T cell cytotoxic function against a subset of non-virally associated tumors. Here we have used an EBV-infected cord blood-humanized mouse model to show that EBV-infected lymphomas express both the PD-L1 and PD-L2 inhibitory ligands for PD-1. Importantly, we find that the combination of PD-1 and CTLA-4 blockade decreases the growth of EBV-induced lymphomas in this model, and demonstrate that this anti-tumor effect requires T cells and enhances their responses to EBV. Our results suggest that PD-1/CTLA-4 blockade might be useful for treating certain EBV-associated diseases in humans.

Microenvironment-related biomarkers and novel targets in classical Hodgkin's lymphoma

Classical Hodgkin's lymphoma accounts for approximately 10% of all malignant lymphomas. Although most patients can be cured with modern treatment strategies, approximately 25% of them experience either primary or secondary chemorefractoriness or disease relapse, thus requiring novel treatments. Increasing preclinical and clinical evidences have demonstrated the role of microenvironment in the molecular pathogenesis of classical Hodgkin's lymphoma and elucidated the complex cross-talk between the malignant Hodgkin Reed–Sternberg cells and the nonmalignant, reactive cells of the microenvironment, strongly supporting novel therapeutic approaches aimed at targeting Hodgkin's Reed–Sternberg cells along with reactive cells in order to overcome chemorefractoriness. In the near future, these novel therapies will also be tested in chemosensitive patients to reduce long-term toxicities of chemo-radiotherapy.

The inflammatory chemokine CCL5 and cancer progression

Until recently, inflammatory chemokines were viewed mainly as indispensable “gate keepers” of immunity and inflammation. However, updated research indicates that cancer cells subvert the normal chemokine system and these molecules and their receptors become important constituents of the tumor microenvironment with very different ways to exert tumor-promoting roles. The CCR5 and the CCL5 ligand have been detected in some hematological malignancies, lymphomas, and a great number of solid tumors, but extensive studies on the role of the CCL5/CCR axis were performed only in a limited number of cancers. This review summarizes updated information on the role of CCL5 and its receptor CCR5 in cancer cell proliferation, metastasis, and the formation of an immunosuppressive microenvironment and highlights the development of newer therapeutic strategies aimed to inhibit the binding of CCL5 to CCR5, to inhibit CCL5 secretion, or to inhibit the interactions among tumor cells and the microenvironment leading to CCL5 secretion.

Immunologic pathomechanism of Hodgkin's lymphoma

Hodgkin's lymphoma is a lymphoid malignancy of the immune system. The pathognomonic Hodgkin and Reed-Sternberg cells (HRS) are derived mainly from monoclonal, preapoptotic B cells, and they carry rearranged, somatically mutated immunoglobulin heavy chains. In an appropriate microenvironment, HRS cells escape from apoptosis by several mechanisms, including single mutations, aberrant signaling pathways. Eventually, weakened immune surveillance leads to uncontrolled, disproportional B cell proliferation. This review summarizes the latest findings on the pathogenesis of Hodgkin lymphoma, with a special emphasis on immunologic processes, and depicts current and future immunotherapeutic regimens, which improve treatment outcomes and reduce late toxicities.

Cytokine signatures of transformed B cells with distinct Epstein-Barr virus latencies as a potential diagnostic tool for B cell lymphoma

Immunocompromised individuals, including those infected with human immunodeficiency virus (HIV), are at increased risk of Epstein-Barr virus (EBV)-associated aggressive B cell malignancies such as Burkitt's lymphoma (BL) or diffuse large B cell lymphoma (DLBCL). Differential diagnosis of these lymphomas requires histopathological, immunohistochemical and cytogenetic assessments. Rapid, less invasive approaches to the diagnosis of EBV-associated B cell lymphomas are needed. Here, high-throughput cytokine profiling of BL cell lines and EBV-transformed B lymphoblastoid cell lines (B-LCL), representing DLBCL, was carried out. By monitoring the production of 42 different cytokines, unique cytokine signatures were identified for BL and B-LCL/DLBCL. The BL cells produced interleukin (IL)-10, 10 kDa interferon gamma-induced protein (IP-10)/CXCL10, macrophage-derived chemokine (MDC)/CCL22, macrophage inflammatory protein (MIP)-1α/CCL3 and MIP-1β/CCL4. In addition to these five cytokines, the cytokine signature of B-LCL/DLBCL cells included IL-8/CXCL8, IL-13, platelet-derived growth factor (PDGF)-AA, and regulated upon activation, normal T cell expressed and secreted (RANTES)/CCL5. Epstein-Barr virus latency was responsible for the increased production of IL-10, MDC/CCL22 and MIP-1α/CCL3 in BL cells, suggesting that EBV-mediated BL-genesis involves these three cytokines. These results suggest that high-throughput cytokine profiling might be a valuable tool for the differential diagnosis and might deepen our understanding of the pathogenesis of EBV-associated B cell malignancies.

Classical Hodgkin's lymphoma arising in different host's conditions: pathobiology parameters, therapeutic options, and outcome

Epidemiologic and molecular findings suggest that classical Hodgkin's lymphoma (CHL) is not a single disease but consists of more than one entity and may occur in different clinical settings. This review analyzes similarities and disparities among CHL entities arising in different host's conditions with respect to pathobiology parameters, therapeutic options, and outcome. For the purpose of this analysis, CHL entities have been subdivided according to the immune status of the host. In nonimmunosuppressed hosts, according to the age, CHL include pediatric, adult, and elderly forms, whereas, in immunosuppressed hosts, according to the type of immunosuppression, CHL include human immunodeficiency virus (HIV)-associated, iatrogenic, and post-transplant types. CHL entities in different settings are similar in morphology of neoplastic cells, expression of activation markers, and aberrations/activation of NFKB, JAK/STAT, and P13K/AKT pathways, but differ in the association with Epstein-Barr virus (EBV) infection, persistent B-cell phenotype, and cellular background composition. Large B-cell lymphomas resembling CHL may also be observed in the same clinical settings. These lesions, however, do not fulfill the diagnostic criteria of CHL and clinically display a very aggressive behavior. In this article, current treatment options for the CHL entities, especially for elderly CHL and HIV-associated CHL, are specifically reviewed. ABVD remains the gold standard both in nonimmunosuppressed or immunosuppressed hosts even if there are several data suggesting a possible improvement in outcome using the aggressive BEACOPP regimen in advanced stages. Refractory CHL, a clinical condition that may occur throughout the entire spectrum of CHL, is discussed separately.

Endogenous latent membrane protein 1 in Epstein-Barr virus-infected nasopharyngeal carcinoma cells attracts T lymphocytes through upregulation of multiple chemokines

Tumor-infiltrating T lymphocytes are considered to facilitate development of Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC), but how EBV in NPC tumor cells directs T cell infiltration remains unclear. Here we compare EBV-infected NPC cells with and without spontaneous expression of viral latent membrane protein 1 (LMP1) and find that culture supernatants of LMP1-positive NPC cells exert enhanced chemoattraction to primary T cells. Knockdown of endogenous LMP1 in the cells suppresses the chemotactic activity. Endogenous LMP1 in NPC cells upregulates multiple chemokines, among which MIP-1alpha, MIP-1beta and IL-8 contribute to T cell chemotaxis. We further reveal that LMP1-induced production of MIP-1alpha and MIP-1beta in NPC cells requires not only two carboxyl-terminal activation regions of LMP1 but also their downstream NF-kappaB and JNK pathways. This study corroborates that endogenous LMP1 in EBV-infected NPC cells induces multiple chemokines to promote T cell recruitment and perhaps other pathogenic events in NPC.

Potential risk factors associated with the use of cidofovir to treat benign human papillomavirus-related disease

BACKGROUND

Cidofovir is currently being used off-licence to treat different viral infections, such as benign low-risk human papillomavirus (HPV)-related recurrent respiratory papillomatosis (RRP). There are concerns over the safety of this practice as rat studies demonstrated a high malignant transformation rate. As yet, there are no clinical reports of cidofovir-induced malignant changes in humans.

METHODS

Telomerase immortalised human keratinocytes (hTert) stably expressing E6 proteins from either low-risk HPV6b or high-risk HPV16 and vector control cells were treated with either low-dose (5 microg/ml) or higher dose (30 microg/ml) cidofovir for 2 days and the effects evaluated by clonogenic survival assays. Based on these results, gene expression microarray analysis was performed on cidofovir-treated low-risk E6 and vector cells before, during and after drug treatment, and the results verified by real-time PCR.

RESULTS

Both low-risk and high-risk E6-expressing cells show significantly improved long-term survival compared with vector control cells when exposed to 5 microg/ml cidofovir for 2 days, (hTert T6E6 P=0.0007, hTert T16E6 P=0.00023 and hTert vector control P=0.62). Microarray and real-time PCR analyses of low-dose cidofovir-treated low-risk E6-expressing cells revealed changes in gene expression that are known to be associated with malignant progression, which were not observed in drug-treated vector control cells.

CONCLUSIONS

This is the first report that cidofovir can both increase cell survival and induce alterations in gene expression that are known to be associated with malignant transformation in cells transduced only with the E6 gene from low-risk HPV. It is our belief that these data provide cause for concern over the off-license use of this drug to treat RRP.

Expression of CCR5 receptors on Reed-Sternberg cells and Hodgkin lymphoma cell lines: involvement of CCL5/Rantes in tumor cell growth and microenvironmental interactions

The expression of CCL5/Rantes by Hodgkin (H) and Reed-Sternberg (RS) cells has been recently documented. In the present study we demonstrated that the CCL5 receptor (CCR5) is constitutively expressed by Hodgkin Lymphoma (HL)-derived cell lines (i.e. L-428, KM-H2, L-1236 and L-540) as shown by immunohistochemistry, flow cytometry and western blotting and also detected by immunohistochemistry on primary H-RS cells from lymph node tissues. sCD40L never significantly affected CCR5 expression, whereas a short exposure to doxorubicin down regulated its expression. CCR5 receptors on HL cell lines were functionally active, since neutralizing anti-CCL5 monoclonal antibodies inhibited basal proliferation of HL-derived cell lines and recombinant CCR5 ligands (CCL3/Mip-1 alpha, CCL4/Mip1 beta and CCL5/Rantes) increased their clonogenic growth. CCL5 secretion by L-1236, L-428 and KM-H2 cells was stimulated by CD40 engagement and also by coculturing L-1236 cells on primary stromal fibroblasts from HL-involved lymph nodes (HLF). Coculture experiments indicated that a direct contact of H-RS cells induces HLF cells to produce CCL5. Supernatants from L-1236, L-428 and KM-H2 cells stimulated migration of purified CD4+ T-cells and eosinophils in vitro. The migratory response to HL-cell lines supernatants was only partially neutralized (CD4+ cells: 70%; esinophils: 36%) by anti-CCL5 antibodies, reinforcing the notion that multiple chemokines are involved in the recruitment of nonmalignant reactive cells in HL tissues. Taken together, our results indicate a possible involvement of the CCR5/CCR5-ligands signaling in the regulation of H-RS cells growth and in the formation/maintenance of the typical tissue microenvironment of HL.

One-step multiplex real-time PCR assay to analyse the latency patterns of Epstein-Barr virus infection

Epstein-Barr virus (EBV) establishes a latent infection with three types of viral gene expression. These latency types can be distinguished by the expression patterns of EBV nuclear antigen (EBNA)1, EBNA2, latent membrane protein (LMP)1, and LMP2. The EBV lytic cycle is initiated by the transcription of the EBV immediate early BZLF1 gene, which can be used to distinguish between a latent and a lytic infection. In this study, a one-step multiplex real-time PCR assay was developed to quantify the EBNA1, EBNA2, LMP1, LMP2, and BZLF1 expression levels simultaneously by relative quantification. To validate this assay, the quantitation of viral gene transcription was performed in EBV-positive B, T, and natural killer cell lines. Because of its rapidity, sensitivity, and specificity, this new assay can be used for quantitative analyses of the latency patterns of EBV infection and the switch from latency to lytic viral replication.

Expression of RANTES and MCP-1 in epithelial cells is regulated via LMP1 and CD40

Epstein-Barr virus (EBV)-associated undifferentiated nasopharyngeal carcinoma (NPC) is characterized by a prominent nonneoplastic lymphoid stroma. The functional role of these inflammatory cells and the mechanism of their recruitment are not fully understood. In B-cells, the EBV-encoded latent membrane protein 1 (LMP1) can induce the expression of chemokines in an NF-kappaB dependent manner. We now show that LMP1 can induce the expression of RANTES and MCP-1 in an epithelial cell line, and that this effect is partially reversible by an inhibitor of NF-kappaB. Since tumor cells of virtually all NPCs show CD40 expression while many cases are LMP1-negative at the protein level, we also investigated the effect of CD40 signaling and demonstrate that CD40 stimulation can transiently induce RANTES and MCP-1 expression in LMP1-negative epithelial cells. In in situ hybridization only rare tumor cells showed expression of these chemokines unrelated to LMP1 expression, a pattern consistent with transient induction through CD40 signaling. Since RANTES and MCP-1 were also detected in the neoplastic cells of oral squamous cell carcinomas lacking a lymphoid stroma it remains uncertain to what extent these CC chemokines contribute to the attraction of inflammatory cells into the NPC microenvironment.

Angioimmunoblastic T-cell lymphoma: histological progression associates with EBV and HHV6B viral load

The clinical and histological presentations of angioimmunoblastic T-cell lymphoma (AITL) often mimic an infectious process. Epstein-Barr virus (EBV) and human herpes virus (HHV6) are known to be associated with AITL, but whether these viral infections play a role in its pathogenesis is unclear. It also remains to be investigated whether there might be other viruses associated with AITL. We first screened 26 well-characterised cases of AITL for herpesvirus by polymerase chain reaction (PCR) with universal primers and found evidence of only EBV and HHV6B infection. Subsequent PCR using virus-specific primers demonstrated EBV and HHV6B infection in 40/49 biopsies (36/42 cases) and 21/49 biopsies (19/42 cases) of AITL respectively with both viral infections found in 17/49 specimens (15/42 cases). Importantly, simultaneous infection with both viruses was found only in specimens showing histological pattern II (n = 2) or III (n = 15). Interestingly, among specimens containing both viruses, there was a tendency towards an inverse correlation between the EBV and HHV6B viral load as shown by quantitative PCR. In specimens positive only for EBV, the viral load was significantly higher in specimens with histological pattern III than those with pattern II. High EBV load was also significantly associated with B-cell monoclonality. Double EBV encoded small RNA (EBER) in situ hybridisation and immunohistochemistry indicated that EBV-infected B cells had a late postgerminal centre immunophenotype. Our results demonstrate an association between EBV and HHV6B infection and the histological progression of AITL, suggesting that these viruses may play a role in the pathogenesis of this lymphoma.

The presence of functional CCR5 and EBV reactivation after allogeneic haematopoietic stem cell transplantation

EBV reactivation is a serious complication affecting the recipients of allogeneic haematopoietic stem cell transplants (allogeneic HSCT). Recent reports have suggested that EBV reactivation induces increased expression of C-C chemokine receptor-5 (CCR5) or its ligands. Therefore, the 32-nucleotide deletion within the CCR5-encoding gene (CCR5Delta32 polymorphism) was analysed in 92 recipients of allogeneic HSCT and their donors and related with EBV load. In addition in 30 patients, at the same time points employing a real-time PCR technique, the number of viral copies and CCR5 transcripts were assessed. The incidence of EBV reactivation 2-3 months after transplantation was significantly lower in patients carrying the CCR5Delta32 allele (P=0.008). The association was confirmed in multivariate analysis, in which recipient CCR5Delta32 (OR=0.166, P=0.026) in addition to recipient age (OR=1.536, P=0.034) were identified as independent risk factors for EBV reactivation. Moreover, EBV reactivation was more frequently seen when patients and their donors were lacking the CCR5 deletion mutation as compared to other donor-recipient pairs (P=0.022). The CCR5 expression was significantly higher in the group of patients having EBV reactivation than in those lacking it (R=25.354, P=0.024). These results suggest that the expression of functional CCR5 plays a role in initiation/perpetuation of EBV reactivation.

Lack of association between the -403G/A promoter polymorphism in the human CCL5/RANTES chemokine gene in liver transplant outcome

Chemokines play a major role in the inflammatory and immune responses that mediate allograft outcome. CCL5/RANTES expansion chemokine is potent eosinophil, monocyte, basophils and lymphocyte chemoattractant and has recently been studied in transplantation with discrepant results, but systemic concentrations have been correlated to liver graft survival and incidence of rejection. Recent studies revealed that a functional mutation at -403 in the promoter may have a significance for inflammatory and infectious immune responses. Our objective was to investigate CCL5/RANTES promoter polymorphism in rejection and graft survival in liver transplant. We examined the CCL5/RANTES polymorphism in a series of 218 liver transplants and 101 healthy Caucasian subjects. CCL5/RANTES genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). After comparing recipients (with acute rejection episodes versus without rejection) with the control population, we found no significant deviation in the distribution of the alleles or genotypes of CCL5/RANTES dimorphism in any comparison (P > 0.05). Indeed, 5 years allograft survival was 61.3% in recipients with the GG genotype against 58.8% in recipients with the GA and AA genotypes. These differences were also not statistically significant. In conclusion, human CCL5/RANTES gene promoter polymorphism does not seem to influence acute rejection development and allograft survival in liver recipients.

Potential mechanism of resistance to TRAIL-induced apoptosis in Burkitt's lymphoma

OBJECTIVES

Members of the tumor necrosis factor family are potent inducers of apoptosis in sensitive cells and may be suitable for novel anti-cancer therapies aimed at inducing apoptosis via the activation of receptors with the death domain on malignant cells. We characterized the sensitivity of Burkitt's lymphoma (BL) cell lines to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and anti-Fas agonist, and investigated the mechanism of resistance of BL cell lines to TRAIL and Fas apoptotic pathways.

METHODS

Epstein-Barr virus (EBV) status in BL cell lines was determined by PCR. The extent of apoptosis following exposure to TRAIL and anti-Fas agonist was measured by 7A6 antigen staining. Expression of TRAIL receptors and Fas was determined by flow cytometry and reverse transcriptase-PCR. Western blot analyses were used to determine the expression of proapoptotic and antiapoptotic proteins. NF-kappaB activity was evaluated by electrophoretic mobility shift assay.

RESULTS

The sensitivity of BL cell lines to anti-Fas agonist depended on the expression of Fas. In contrast, the expression of TRAIL receptors did not correlate with the sensitivity to TRAIL-induced apoptosis. Interestingly, EBV-infected BL cell lines which showed constitutive levels of NF-kappaB activation, were TRAIL-resistant. NF-kappaB inhibitors reversed the resistance to TRAIL-induced apoptosis.

CONCLUSIONS

Our results suggest that activation of NF-kappaB by EBV infection plays an important role in resistance of BL cell lines to TRAIL-induced apoptosis, and that NF-kappaB inhibitors may be useful adjuncts in clinical use of TRAIL against BL.