HIV-related hematological malignancies: a concise review

Investigating the correlation between prominent viruses and hematological malignancies: a literature review

Extensive research has been conducted on the correlation between viral infections and hematological cancers ever since the identification of the Rous Sarcoma Virus as a cancer-causing agent. Numerous viruses, such as the Epstein-Barr virus, hepatitis B virus, hepatitis C virus, human immunodeficiency virus, human T-lymphotropic virus 1, and severe acute respiratory syndrome-related coronavirus 2, have been identified as potential contributors to the development and progression of cancer by disrupting normal cellular processes. Different viruses are associated with distinct forms of blood cancers, each exhibiting unique infection mechanisms, pathogenesis, and clinical symptoms. Understanding these connections is crucial for the development of effective prevention and treatment strategies. Healthcare professionals who possess a solid understanding of these associations can offer precise treatments and closely monitor potential complications in individuals with blood cancers and viral infections. By leveraging this information, healthcare providers can optimize patient care and improve outcomes for those affected by both viral infections and hematological cancers.

Human Immunodeficiency Virus Related Non-Hodgkin's Lymphoma

Human immunodeficiency virus infection is related with an increased risk of hematological malignancy principally, non-Hodgkin lymphoma. Most non-Hodgkin lymphomas are acquired immunodeficiency syndrome defining and constitute greater than 50% of all acquired immunodeficiency syndrome defining cancers. The main pathogenesis mechanisms are immunodeficiency, chronic antigenic stimulation, and the ability to infect cancer cells causing direct carcinogenesis. Human immunodeficiency virus related non-Hodgkin lymphomas are heterogeneous in immunophenotyping and molecular features; and choice of drug treatments is similar with sporadic types. The main objective is to assess the epidemiology, pathogenesis, and morphology of human immunodeficiency virus related non-Hodgkin lymphoma. The searching strategy was done by searching relevant original and review articles from www.biosemanticjane/org, Google scholar, Google, and PubMed sites using keywords like; Acquired immunodeficiency syndrome, Human immunodeficiency virus, and non-Hodgkin lymphoma. In conclusion, human immunodeficiency virus infected people continue to have elevated risk of non-Hodgkin lymphoma. Diffuse large B-cell lymphomas are the most common and severe subtype. The pathogenesis of this type of lymphoma is associated with chromosomal abnormalities that deregulate the expression of various oncogenes by different viral particles and cytokines. However, the role of these viral particles and cytokines on pathogenesis is not clearly stated, so further study could be required.

Aetiology of pancytopenia: Experience of a South African tertiary academic centre

Background

Pancytopenia is a manifestation of numerous disease entities. The causes of pancytopenia differ with geographic region, socio-economic factors and HIV prevalence. Awareness of the common causes of pancytopenia may aid timely diagnosis.

Objective

This study aimed to determine the aetiology of pancytopenia in a South African population.

Methods

A retrospective observational study of adult patients presenting with pancytopenia at Tygerberg Academic Hospital, South Africa, from January 2016 to December 2017 was performed. Data on pancytopenia cases were obtained from the laboratory information system and utilised to determine the causes of pancytopenia.

Results

A total of 673 cases of pancytopenia were identified. The most common causes of pancytopenia were chemoradiation therapy (25%), sepsis (18%), haematological malignancy (9%), advanced HIV (7%), and megaloblastic anaemia (6%). The diagnostic yield of bone marrow examinations (BME) was 57% (n = 52/91). The aetiology of pancytopenia differed according to age, with malignancy being a more common cause of pancytopenia among the elderly.

Conclusion

Several easily recognisable and treatable conditions can manifest as pancytopenia. Prompt management of such conditions, notably sepsis and megaloblastic anaemia, can result in the resolution of the cytopenias and negate the need for a BME. However, haematological malignancy and unexplained pancytopenia strongly rely on a BME to establish a diagnosis. Pancytopenia investigations, when guided by appropriate clinic-laboratory findings, can promptly identify the underlying aetiology, while also identifying cases where an expedited BME is required. This is valuable in resource-conscious medicine.

Clinical and Therapeutic Implications of Epstein-Barr Virus in HIV-Related Lymphomas

The incidence of lymphomas is increased in people living with HIV (PLWH). Aggressive B-cell non-Hodgkin lymphomas (NHLs) are the most common and are considered an AIDS-defining cancer (ADC). Although Hodgkin lymphoma (HL) is not considered an ADC, its incidence is also increased in PLWH. Among all HIV-related lymphomas (HRL), the prevalence of Epstein-Barr virus (EBV) is high. It has been shown that EBV is involved in different lymphomagenic mechanisms mediated by some of its proteins, contributing to the development of different lymphoma subtypes. Additionally, cooperation between both HIV and EBV can lead to the proliferation of aberrant B-cells, thereby being an additional lymphomagenic mechanism in EBV-associated HRL. Despite the close relationship between EBV and HRL, the impact of EBV on clinical aspects has not been extensively studied. These lymphomas are treated with the same therapeutic regimens as the general population in combination with cART. Nevertheless, new therapeutic strategies targeting EBV are promising for these lymphomas. In this article, the different types of HRL are extensively reviewed, focusing on the influence of EBV on the epidemiology, pathogenesis, clinical presentation, and pathological characteristics of each lymphoma subtype. Moreover, novel therapies targeting EBV and future strategies to treat HRL harboring EBV are discussed.

Clonal Expansion of Infected CD4+ T Cells in People Living with HIV

HIV infection is not curable with current antiretroviral therapy (ART) because a small fraction of CD4+ T cells infected prior to ART initiation persists. Understanding the nature of this latent reservoir and how it is created is essential to development of potentially curative strategies. The discovery that a large fraction of the persistently infected cells in individuals on suppressive ART are members of large clones greatly changed our view of the reservoir and how it arises. Rather than being the products of infection of resting cells, as was once thought, HIV persistence is largely or entirely a consequence of infection of cells that are either expanding or are destined to expand, primarily due to antigen-driven activation. Although most of the clones carry defective proviruses, some carry intact infectious proviruses; these clones comprise the majority of the reservoir. A large majority of both the defective and the intact infectious proviruses in clones of infected cells are transcriptionally silent; however, a small fraction expresses a few copies of unspliced HIV RNA. A much smaller fraction is responsible for production of low levels of infectious virus, which can rekindle infection when ART is stopped. Further understanding of the reservoir will be needed to clarify the mechanism(s) by which provirus expression is controlled in the clones of cells that constitute the reservoir.

SARS-CoV-2: lessons from both the history of medicine and from the biological behavior of other well-known viruses

SARS-CoV-2 is the etiological agent of the current pandemic worldwide and its associated disease COVID-19. In this review, we have analyzed SARS-CoV-2 characteristics and those ones of other well-known RNA viruses viz. HIV, HCV and Influenza viruses, collecting their historical data, clinical manifestations and pathogenetic mechanisms. The aim of the work is obtaining useful insights and lessons for a better understanding of SARS-CoV-2. These pathogens present a distinct mode of transmission, as SARS-CoV-2 and Influenza viruses are airborne, whereas HIV and HCV are bloodborne. However, these viruses exhibit some potential similar clinical manifestations and pathogenetic mechanisms and their understanding may contribute to establishing preventive measures and new therapies against SARS-CoV-2.

Outcomes of HIV-associated Burkitt Lymphoma in Brazil: High treatment toxicity and refractoriness rates - A multicenter cohort study

BACKGROUND

Although the increased use of combined antiretroviral therapy (cART) has decreased the incidence of lymphomas HIV-associated, Burkitt lymphoma (BL) incidence remains stable. Reported outcomes on HIV-associated BL from developed countries seem to corroborate that the regimens do not need to be tailored to the HIV-positive population.

MATERIALS AND METHODS

This is a retrospective multicenter cohort study from Brazil, including HIV-positive patients aged 15 years and above diagnosed with BL.

RESULTS

A total of 54 patients were included. Median age was 39 years (range, 15-64). At diagnosis, advanced disease was found in 86% and 52% had a CD4+ count lower than 200 cells/mm³. Five patients died before starting any regimen. Among the remaining 49 patients, most were treated with Hyper-CVAD (53%) and CODOX-M IVAC (18%). Rituximab was used in frontline in only 16% of the patients. Primary refractory disease was found in 14%. A treatment-related mortality of 38.7% and a complete response rate of 44.9% were found. At 4 years, estimated overall survival (OS) was 39.8%. All relapsed and primary refractory patients eventually died. Remaining patients died from infections (24/34), despite antimicrobial prophylaxis and associated cART.

CONCLUSION

Early mortality and toxicity were higher in our cohort than in developed countries. A faster diagnosis, better understanding of the biology of the disease, establishment of low toxicity regimens, inclusion of rituximab and improvement of supportive care may decrease the mortality of HIV-associated BL in developing countries.

Brief Report: Malignancies in Adults Living With HIV in Asia

BACKGROUND

Hematological malignancies have continued to be highly prevalent among people living with HIV (PLHIV). This study assessed the occurrence of, risk factors for, and outcomes of hematological and nonhematological malignancies in PLHIV in Asia.

METHODS

Incidence of malignancy after cohort enrollment was evaluated. Factors associated with development of hematological and nonhematological malignancy were analyzed using competing risk regression and survival time using Kaplan-Meier.

RESULTS

Of 7455 patients, 107 patients (1%) developed a malignancy: 34 (0.5%) hematological [0.08 per 100 person-years (/100PY)] and 73 (1%) nonhematological (0.17/100PY). Of the hematological malignancies, non-Hodgkin lymphoma was predominant (n = 26, 76%): immunoblastic (n = 6, 18%), Burkitt (n = 5, 15%), diffuse large B-cell (n = 5, 15%), and unspecified (n = 10, 30%). Others include central nervous system lymphoma (n = 7, 21%) and myelodysplastic syndrome (n = 1, 3%). Nonhematological malignancies were mostly Kaposi sarcoma (n = 12, 16%) and cervical cancer (n = 10, 14%). Risk factors for hematological malignancy included age >50 vs. ≤30 years [subhazard ratio (SHR) = 6.48, 95% confidence interval (CI): 1.79 to 23.43] and being from a high-income vs. a lower-middle-income country (SHR = 3.97, 95% CI: 1.45 to 10.84). Risk was reduced with CD4 351-500 cells/µL (SHR = 0.20, 95% CI: 0.05 to 0.74) and CD4 >500 cells/µL (SHR = 0.14, 95% CI: 0.04 to 0.78), compared to CD4 ≤200 cells/µL. Similar risk factors were seen for nonhematological malignancy, with prior AIDS diagnosis showing a weak association. Patients diagnosed with a hematological malignancy had shorter survival time compared to patients diagnosed with a nonhematological malignancy.

CONCLUSIONS

Nonhematological malignancies were common but non-Hodgkin lymphoma was more predominant in our cohort. PLHIV from high-income countries were more likely to be diagnosed, indicating a potential underdiagnosis of cancer in low-income settings.

Acute Promyelocytic Leukemia and HIV: Case Reports and a Review of the Literature

Acute promyelocytic leukemia (APL) in human immunodeficiency virus (HIV)-infected individuals is very rare. There is currently no consensus regarding the use of anti-cancer drugs with highly active anti-retroviral therapy (ART) in these patients due to their small number. We herein report two cases of APL with HIV-infected patients. Both cases received all-trans-retinoic acid-containing chemotherapies and achieved complete remission. ART was continued throughout the treatment course. The clinical course of these cases suggests that it is preferable to perform standard chemotherapy for APL with ART if patients have an adequate performance status.

Global HIV neurology: a comprehensive review

: Neurological conditions associated with HIV remain major contributors to morbidity and mortality and are increasingly recognized in the aging population on long-standing combination antiretroviral therapy (cART). Importantly, growing evidence shows that the central nervous system (CNS) may serve as a reservoir for viral replication, which has major implications for HIV eradication strategies. Although there has been major progress in the last decade in our understanding of the pathogenesis, burden, and impact of neurological conditions associated with HIV infection, significant scientific gaps remain. In many resource-limited settings, antiretrovirals considered second or third line in the United States, which carry substantial neurotoxicity, remain mainstays of treatment, and patients continue to present with severe immunosuppression and CNS opportunistic infections. Despite this, increased global access to cART has coincided with an aging HIV-positive population with cognitive sequelae, cerebrovascular disease, and peripheral neuropathy. Further neurological research in low-income and middle-income countries (LMICs) is needed to address the burden of neurological complications in HIV-positive patients, particularly regarding CNS viral reservoirs and their effects on eradication.

Is the cancer survival improvement in European and American adolescent and young adults still lagging behind that in children?

Improvements during 1978 to 2006 in the 5-year survival rate of adolescents and young adults (AYAs, age 15-39) and children with cancers common to both age groups were evaluated for 1978 to 2006 in Europe and the USA. AYAs had absolute survival increases of 25% and 15% in Europe and the USA, respectively, but in both cases, AYA 5-year survival was, as of 2006, 4% lower than those in children. Acute lymphoblastic leukemia (ALL) explained most of the survival difference between AYAs and children on both the continents. In the USA, 20- to 39-year-olds with ALL have had less survival improvement than those in Europe.

Evidence for persistence of the SHIV reservoir early after MHC haploidentical hematopoietic stem cell transplantation

Allogeneic transplantation (allo-HCT) has led to the cure of HIV in one individual, raising the question of whether transplantation can eradicate the HIV reservoir. To test this, we here present a model of allo-HCT in SHIV-infected, cART-suppressed nonhuman primates. We infect rhesus macaques with SHIV-1157ipd3N4, suppress them with cART, then transplant them using MHC-haploidentical allogeneic donors during continuous cART. Transplant results in ~100% myeloid donor chimerism, and up to 100% T-cell chimerism. Between 9 and 47 days post-transplant, terminal analysis shows that while cell-associated SHIV DNA levels are reduced in the blood and in lymphoid organs post-transplant, the SHIV reservoir persists in multiple organs, including the brain. Sorting of donor-vs.-recipient cells reveals that this reservoir resides in recipient cells. Moreover, tetramer analysis indicates a lack of virus-specific donor immunity post-transplant during continuous cART. These results suggest that early post-transplant, allo-HCT is insufficient for recipient reservoir eradication despite high-level donor chimerism and GVHD.

Allogeneic hematopoietic cell transplantation (allo-HCT) has led to the cure of HIV in one individual, but the underlying mechanisms are unclear. Here, the authors present a model of allo-HCT in SHIV-infected nonhuman primates and show that the SHIV reservoir persists in multiple tissues early after transplantation.

TMC120 displayed potent cytotoxic effect on human cervical carcinoma through enhancing the polymerization of microtubules

OBJECTIVE

In the post-HAART era, the incidence of some AIDS-defining cancers declined markedly likely reflecting HAART-related improvements in immunity, whereas incidence of some cancers such as cervical cancer has not been affected. Therefore, it is valuable to find whether antiretroviral drugs or prophylactic microbicides could treat or prevent these cancers, especially the cervical cancer.

DESIGN

We screened the anti-HIV drugs, approved or in phase III clinical trials, to identify a potential anticancer drug candidate.

METHODS

We chose cervical HeLa and SiHa cancer cells and focused on studying the antitumor effects in vitro and in vivo. Cell proliferation was measured by MTT assay, the cytotoxic effect was obtained through apoptosis as evidenced by Annexin V flow cytometry assay because of the arresting of cancer cells in G2/M phase of cell cycle. Nude mice xenograft model was performed to detect the antitumor effect in vivo.

RESULTS

TMC120 was identified as a potential anticancer drug candidate. TMC120 displayed potent cytotoxic effect on various human cancer cells, including cervical carcinoma cell line HeLa and SiHa. Further mechanism study showed that TMC120 enhanced the polymerization of microtubules, which was followed by mitotic arrest, as well as abnormal mitotic spindles. TMC120 also substantially retarded the growth rate of the tumor in vivo.

CONCLUSION

TMC120 is a potential chemoprophylactic and therapeutic agent for cervical cancers in a manner similar to paclitaxel, and could be suitable for helping healthy women to prevent HIV infection and cervical cancer.

Primary CNS lymphoma in HIV infection

Primary CNS lymphoma (PCNSL) has been designated an acquired immune deficiency syndrome (AIDS)-defining disease since 1983 and accounts for up to 15% of non-Hodgkin lymphomas in human immunodeficiency virus (HIV) patients. The majority of HIV patients are Epstein-Barr virus (EBV)-related. The most likely etiology is ineffective immunoregulation of EBV, inducing oncogenic protein expression, and subsequent loss of apoptosis and increased proliferation of lymphocytes. PCNSL generally presents with supratentorial, single or multiple, contrast-enhancing lesions. Neurologic symptoms can be headache, cognitive function disorders, focal neurologic, deficit and epilepsy. Differential diagnosis includes other oncologic or infectious causes, with cerebral toxoplasmosis being the most important. Magnetic resonance imaging characteristics, activity on ²⁰¹thallium single-photon emission computed tomography, presence of EBV DNA in the cerebrospinal fluid, and toxoplasmosis serology can make either PCNSL or cerebral toxoplasmosis more or less likely. However, definitive diagnosis of PCNSL relies on histopathologic confirmation. First-choice treatment is combination antiretroviral therapy in combination with high-dose methotrexate(-based) chemotherapy in patients in whom this is feasible. Combination antiretroviral therapy combined with whole-brain radiotherapy may be an alternative. Treatment of EBV with antiviral agents such as ganciclovir or zidovudine may be beneficial, but this needs further study. Prognosis of HIV-related PCNSL is poor, with median survival varying from 2 to 4 months, but patients treated with chemotherapy do better (median survival 1.5 years).

Evolution of HIV-Associated Lymphoma Over 3 Decades

INTRODUCTION

The emergence of combined antiretroviral therapy (cART) and improvements in the management of opportunistic infections have altered the HIV epidemic over the last 30 years. We aimed to assess changes to the biology and outcomes of HIV-associated lymphomas over this period at the national center for HIV oncology in the United Kingdom.

METHODS

Clinical characteristics at lymphoma diagnosis have been prospectively collected since 1986, along with details of lymphoma treatment and outcomes. The clinical features and outcomes were compared between 3 decades: pre-cART decade (1986-1995), early-cART decade (1996-2005), and late-cART decade (2006-2015).

RESULTS

A total of 615 patients with HIV-associated lymphoma were included in the study: 158 patients in the pre-cART era, 200 patients in the early-cART era, and 257 patients in the late-cART era. In more recent decades, patients were older (P < 0.0001) and had higher CD4 cell counts (P < 0.0001) at lymphoma diagnosis. Over time, there has also been a shift in lymphoma histological subtypes, with an increase in lymphoma subtypes associated with moderate immunosuppression. The overall survival for patients with HIV-associated lymphoma has dramatically improved over the 3 decades (P < 0.0001).

CONCLUSION

Over the last 30 years, the clinical demographic of HIV-associated lymphomas has evolved, and the outcomes have improved.

Body Mass Index, Haemoglobin, and Total Lymphocyte Count as a Surrogate for CD4 Count in Resource Limited Settings

Background. In view of the lack of evidence on the possibility of an economically viable, easy, and readily available biomarker to substitute the traditional role of CD4 counts in HIV disease progression, this study seeks to investigate the potential use of body mass index (BMI), haemoglobin (Hb), and total lymphocyte count (TLC) as surrogate biomarkers for monitoring the disease. Methods. This cross-sectional study was undertaken at the antiretroviral clinic (ART) of the Bomso Hospital, Kumasi, Ghana. We recruited 384 individuals who were 18 years or older and confirmed HIV seropositive patients. Blood samples were assayed for TLC and Hb. Weight and height were determined and BMI was calculated. Result. At a cut-off point of 12.15 g/dL, Hb had sensitivity and specificity of 73.9% and 56.8%, respectively, whereas BMI had 69.6% and 80.1% sensitivity and specificity, respectively. The sensitivity and specificity were also 100% among the studied participants at a cut-off point of 1200 mm⁻³ for TLC. There was a significant positive correlation between CD4 count and Hb (rho 0.262, p = 0.0001), BMI (rho 0.301, p = 0.0001), and TLC (rho 0.834, p = 0.0001). Conclusion. The study demonstrates that TLC, Hb, and BMI may provide some useful prognostic information independent of that provided by CD4 count.

Mycobacterium avium-Intracellulare Complex (MAC) Producing a Periportal Pseudotumor in a Patient With HIV and a Normal CD4 Count

Mycobacterium avium-intracellulare complex (MAC) is an opportunistic infection typically associated with profound immunosuppression, such as AIDS. The presentation of disseminated MAC can be subtle and mimic systemic symptoms associated with lymphoma; abdominal pseudotumor is an exceptionally rare presentation. In the era of highly active anti-retroviral therapy (HAART), opportunistic infections are increasingly rare, and secondary prophylaxis for MAC may be discontinued after adequate therapy and immune reconstitution. Recurrence of disseminated MAC after adequate therapy may be due to macrolide resistance, but with an adequate CD4 T-cell count and undetectable HIV viral load, recurrence raises questions of more subtle immune dysregulation.

Drug-Drug Interactions Based on Pharmacogenetic Profile between Highly Active Antiretroviral Therapy and Antiblastic Chemotherapy in Cancer Patients with HIV Infection

The introduction of Highly Active Antiretroviral Therapy (HAART) into clinical practice has dramatically changed the natural approach of HIV-related cancers. Several studies have shown that intensive antiblastic chemotherapy (AC) is feasible in HIV-infected patients with cancer, and that the outcome is similar to that of HIV-negative patients receiving the same AC regimens. However, the concomitant use of HAART and AC can result in drug accumulation or possible toxicity with consequent decreased efficacy of one or both classes of drugs. In fact, many AC agents are preferentially metabolized by CYP450 and drug-drug interactions (DDIs) with HAART are common. Therefore, it is important that HIV patients with cancer in HAART receiving AC treatment at the same time receive an individualized cancer management plan based on their liver and renal functions, their level of bone marrow suppression, their mitochondrial dysfunction, and their genotype profile. The rationale of this review is to summarize the existing data on the impact of HAART on the clinical management of cancer patients with HIV/AIDS and DDIs between antiretrovirals and AC. In addition, in order to maximize the efficacy of antiblastic therapy and minimize the risk of drug-drug interaction, a useful list of pharmacogenomic markers is provided.

CD4-Positive T-Cell Primary Central Nervous System Lymphoma in an HIV Positive Patient

OBJECTIVES

Primary central nervous system lymphomas (PCNSLs) in patients with human immunodeficiency virus (HIV) are predominantly B-cell lymphomas associated with Epstein-Barr virus (EBV) and rarely CD8-positive T-cell PCNSLs.

METHODS

Patient history, laboratory results, cerebrospinal fluid (CSF), imaging, and brain biopsy specimens were reviewed and tested for T-cell receptor clonality.

RESULTS

A 64-year-old HIV-positive woman sought treatment for lethargy and left-sided weakness. Brain imaging showed regional increased T2 signal with restricted diffusion in cerebral hemispheres. CSF flow cytometry revealed CD4-positive T lymphocytes with loss of CD3, CD5, and CD7. EBV-positive T-cell lymphoma was immunohistochemically confirmed on brain biopsy specimens. Molecular analysis detected clonal T-cell receptor gene rearrangement. The patient received intrathecal methotrexate and whole-brain radiation. She did not respond to treatment and was eventually placed in hospice care.

CONCLUSIONS

To our knowledge, this is the first report of CD4-positive T-cell PCNSL in an HIV-positive patient and will help to raise clinical awareness of this previously unknown entity.

Inhibiting the Recruitment of PLCγ1 to Kaposi's Sarcoma Herpesvirus K15 Protein Reduces the Invasiveness and Angiogenesis of Infected Endothelial Cells

Kaposi’s sarcoma (KS), caused by Kaposi’s sarcoma herpesvirus (KSHV), is a highly vascularised tumour of endothelial origin. KSHV infected endothelial cells show increased invasiveness and angiogenesis. Here, we report that the KSHV K15 protein, which we showed previously to contribute to KSHV-induced angiogenesis, is also involved in KSHV-mediated invasiveness in a PLCγ1-dependent manner. We identified βPIX, GIT1 and cdc42, downstream effectors of PLCγ1 in cell migration, as K15 interacting partners and as contributors to KSHV-triggered invasiveness. We mapped the interaction between PLCγ1, PLCγ2 and their individual domains with two K15 alleles, P and M. We found that the PLCγ2 cSH2 domain, by binding to K15P, can be used as dominant negative inhibitor of the K15P-PLCγ1 interaction, K15P-dependent PLCγ1 phosphorylation, NFAT-dependent promoter activation and the increased invasiveness and angiogenic properties of KSHV infected endothelial cells. We increased the binding of the PLCγ2 cSH2 domain for K15P by substituting two amino acids, thereby creating an improved dominant negative inhibitor of the K15P-dependent PLCγ1 activation. Taken together, these results demonstrate a necessary role of K15 in the increased invasiveness and angiogenesis of KSHV infected endothelial cells and suggest the K15-PLCγ1 interaction as a possible new target for inhibiting the angiogenic and invasive properties of KSHV.

Kaposi’s Sarcoma (KS), etiologically linked to Kaposi’s sarcoma herpesvirus (KSHV), is a tumour of endothelial origin characterised by angiogenesis and invasiveness. In vitro, KSHV infected endothelial cells display an increased invasiveness and high angiogenicity. Here we report that the KSHV protein K15, which increases the angiogenicity of endothelial cells, contributes to KSHV-mediated invasiveness by the recruitment and activation of the cellular protein PLCγ1 and its downstream effectors βPIX, GIT1 and cdc42. We explored the functional consequences of disrupting the K15-PLCγ1 interaction by using an isolated PLCγ2 cSH2 domain as a dominant negative inhibitor. This protein fragment, by interacting with K15, reduces K15-driven recruitment and activation of PLCγ1 in a dose-dependent manner. Moreover, the PCLγ2 cSH2 domain, when overexpressed in KSHV infected endothelial cells, reduces the angiogenesis and invasiveness induced by the virus. These findings highlight the role of the K15-PLCγ1 interaction in KSHV-mediated invasiveness and identify it as a possible therapeutic target.