Tumorigenesis and metastasis of neoplastic Kaposi's sarcoma cell line in immunodeficient mice blocked by a human pregnancy hormone

DLX1008 (brolucizumab), a single-chain anti-VEGF-A antibody fragment with low picomolar affinity, leads to tumor involution in an in vivo model of Kaposi Sarcoma

Kaposi Sarcoma (KS) is among the most angiogenic cancers in humans and an AIDS-defining condition. KS-associated herpesvirus (KSHV) is necessary for KS development, as is vascular endothelial growth factor (VEGF-A). DLX1008 is a novel anti-VEGF-A antibody single-chain variable fragment (scFv) with low picomolar affinity for VEGF-A. In vivo imaging techniques were used to establish the efficacy of DLX1008 and to establish the mechanism of action; this included non-invasive imaging by ultrasound and optical fluorescence, verified by post-mortem histochemistry. The results showed that DLX1008 was efficacious in a KS mouse model. The NSG mouse xenografts suffered massive internal necrosis or involution, consistent with a lack of blood supply. We found that imaging by ultrasound was superior to external caliper measurements in the validation of the angiogenesis inhibitor DLX1008. Further development of DLX1008 against VEGF-dependent sarcomas is warranted.

Role of iron in cancer development by viruses

Increased levels of iron in body are attributed to higher cancer risk. Given the fact that 16% of all human cancers are caused by viral infections, iron is suggested to play an important role in carcinogenesis particularly those induced by viral infections. The present study provides an updated summary of the literature and the plausible mechanisms of iron involvement in cancer development by viruses. Our understanding about the interplay between viral infections and iron in different settings particularly cancer development is yet to be improved as it may shed a new light in development of new therapeutic strategies.

Evolution of Kaposi sarcoma in the past 30 years in a tertiary hospital of the European Mediterranean basin

BACKGROUND

The incidence of Kaposi sarcoma (KS) has reduced as a result of the introduction of antiretroviral therapy. It is currently considered a rare disease in developed countries, and there has been a paucity of clinical papers on the subject in recent years in Europe.

AIM

To analyse the clinical features and evolution of the different clinical forms of KS in the past 30 years.

METHODS

Patients with cutaneous lesions of KS diagnosed during the period 1987-2016 at Bellvitge Hospital (an 800-bed university referral centre in Barcelona, Spain) were enrolled. Data recorded included age, sex, ethnicity, involved site, number of lesions, extracutaneous involvement, leg oedema, treatment, blood haemoglobin level, and blood cell (leucocyte, lymphocyte and CD4) counts.

RESULTS

Cutaneous lesions of KS were diagnosed in 191 patients (167 men, 24 women, mean ± SD age 51.95 ± 20.16 years). Clinical forms identified were classic KS (n = 53), acquired immunodeficiency syndrome (AIDS)-associated KS (n = 118), immunosuppression-associated KS (n = 18), and African endemic KS (n = 2). The number of patients diagnosed annually reached a maximum in the 1990s because of the AIDS epidemic, and has decreased since 2000. However, both classic KS and immunosuppression-associated KS doubled from the first to the second half of the analysed period. Cutaneous lesions involved the legs in 137 cases, and extracutaneous lesions were detected in 32 patients. In 46 of 118 patients with AIDS, the diagnosis of KS was simultaneous to the detection of human immunodeficiency virus infection.

CONCLUSION

After a decrease in incidence since the middle of the 1990s, AIDS-associated KS continues to occur in Europe, and the number of annual cases of classic KS and immunosuppression-associated KS is increasing.

An In Vitro Model for Studying Cellular Transformation by Kaposi Sarcoma Herpesvirus

Kaposi sarcoma (KS) is an unusual tumor composed of proliferating spindle cells that is initiated by infection of endothelial cells (EC) with KSHV, and develops most often in the setting of immunosuppression. Despite decades of research, optimal treatment of KS remains poorly defined and clinical outcomes are especially unfavorable in resource-limited settings. KS lesions are driven by pathological angiogenesis, chronic inflammation, and oncogenesis, and various in vitro cell culture models have been developed to study these processes. KS arises from KSHV-infected cells of endothelial origin, so EC-lineage cells provide the most appropriate in vitro surrogates of the spindle cell precursor. However, because EC have a limited in vitro lifespan, and as the oncogenic mechanisms employed by KSHV are less efficient than those of other tumorigenic viruses, it has been difficult to assess the processes of transformation in primary or telomerase-immortalized EC. Therefore, a novel EC-based culture model was developed that readily supports transformation following infection with KSHV. Ectopic expression of the E6 and E7 genes of human papillomavirus type 16 allows for extended culture of age- and passage-matched mock- and KSHV-infected EC and supports the development of a truly transformed (i.e., tumorigenic) phenotype in infected cell cultures. This tractable and highly reproducible model of KS has facilitated the discovery of several essential signaling pathways with high potential for translation into clinical settings.

Expression of estrogen and progesterone receptors across human malignancies: new therapeutic opportunities

Estrogen and progesterone receptors (ERs and PRs) are known for their prognostic as well as treatment predictive value in breast cancer. Although these receptors are differentially expressed in some other malignancies, and likely participate in the biology of those cancer types, the relevance to outcome and therapy is not well established. The use of ER as a highly effective therapeutic target in oncology was pioneered in breast cancer, and the lessons learned from its success could potentially benefit patients with several other malignancies in which hormone receptors are highly expressed. Indeed, there are several potent drugs available that target hormone receptors. These agents show incontrovertible evidence of benefit in patients with hormone receptor-positive breast cancer. It is conceivable that these drugs may have salutary effects in a variety of cancers other than those originating in the breast, based on the overexpression of hormone receptors in some patients, and the preclinical and clinical reports showing responses to these drugs in diverse cancers, albeit in small series or anecdotally. We therefore undertook a literature review in order to summarize the current data regarding the biologic and clinical implications of expression of estrogen and progesterone receptors in various malignancies and the possibilities for deployment of hormone manipulation beyond breast cancer.

Free β-human chorionic gonadotropin, total human chorionic gonadotropin and maternal risk of breast cancer

BACKGROUND

We investigated whether the free β-human chorionic gonadotropin (free β-hCG) would provide additional information to that provided by total hCG alone and thus be useful in future epidemiological studies relating hCG to maternal breast cancer risk.

MATERIALS & METHODS

Cases (n = 159) and controls (n = 286) were a subset of our previous study within the Northern Sweden Maternity Cohort on total hCG during primiparous pregnancy and breast cancer risk.

RESULTS

The associations between total hCG (hazard ratio: 0.79; 95% CI: 0.49-1.27), free β-hCG (hazard ratio: 0.85; 95% CI: 0.33-2.18) and maternal risk of breast cancer were very similar in all analyses and mutual adjustment for either one had minor effects on the risk estimates.

CONCLUSION

In the absence of a reliable assay on intact hCG, total hCG alone can be used in epidemiological studies investigating hCG and breast cancer risk, as free β-hCG does not appear to provide any additional information.

Chemical synthesis of the β-subunit of human luteinizing (hLH) and chorionic gonadotropin (hCG) glycoprotein hormones

Human luteinizing hormone (hLH) and human chorionic gonadotropin (hCG) are human glycoprotein hormones each consisting of two subunits, an identical α-subunit and a unique β-subunit, that form noncovalent heterodimers. Structurally, β-hCG shares a high degree of sequence similarity with β-hLH, including a common N-glycosylation site at the N-terminus but differs mainly in the presence of an extended C-terminal portion incorporating four closely spaced O-linked glycans. These glycoproteins play important roles in reproduction and are used clinically in the treatment of infertility. In addition, the role of hCG as a tumor marker in a variety of cancers has also attracted significant interest for the development of cancer vaccines. In clinical applications, these hormones are administered as mixtures of glycoforms due to limitations of biological methods in producing homogeneous samples of these glycoproteins. Using the powerful tools of chemical synthesis, the work presented herein focuses on the highly convergent syntheses of homogeneous β-hLH and β-hCG bearing model glycans at all native glycosylation sites. Key steps in these syntheses include a successful double Lansbury glycosylation en route to the N-terminal fragment of β-hCG and the sequential installation of four O-linked glycosyl-amino acid cassettes into closely spaced O-glycosylation sites in a single, high-yielding solid-supported synthesis to access the C-terminal portion of the molecule. The final assembly of the individual glycopeptide fragments involved a stepwise native chemical ligation strategy to provide the longest and most complex human glycoprotein hormone (β-hCG) as well as its closely related homologue (β-hLH) as discrete glycoforms.

Modeling human endothelial cell transformation in vascular neoplasias

Endothelial cell (EC)-derived neoplasias range from benign hemangioma to aggressive metastatic angiosarcoma, which responds poorly to current treatments and has a very high mortality rate. The development of treatments that are more effective for these disorders will be expedited by insight into the processes that promote abnormal proliferation and malignant transformation of human ECs. The study of primary endothelial malignancy has been limited by the rarity of the disease; however, there is potential for carefully characterized EC lines and animal models to play a central role in the discovery, development and testing of molecular targeted therapies for vascular neoplasias. This review describes molecular alterations that have been identified in EC-derived neoplasias, as well as the processes that underpin the immortalization and tumorigenic conversion of ECs. Human EC lines, established through the introduction of defined genetic elements or by culture of primary tumor tissue, are catalogued and discussed in relation to their relevance as models of vascular neoplasia.

Oral HHV-8 replication among women in Mombasa, Kenya

Human herpesvirus-8 (HHV-8) replication in the oropharynx may play an important role in HHV-8 transmission and contribute to the development of Kaposi sarcoma (KS) in some individuals. Studies in the United States and Europe report high rates of HHV-8 DNA detection in saliva of HHV-8 infected men, but little is known about the natural history of HHV-8 among persons in sub-Saharan Africa, where prevalence of HHV-8 infection and KS is greatest. To address this gap, this study evaluated oral HHV-8 replication in a cohort of 40 HHV-8 seropositive Kenyan women. Study clinicians collected daily oral swabs from participants for up to 30 consecutive days, and swab samples were tested for HHV-8 DNA using quantitative, real-time polymerase chain reaction. HHV-8 was detected at least once in 27 (68%) participants, and the overall shedding rate was 23%. On days with HHV-8 detection, mean HHV-8 quantity was 4.5 log10  copies/ml. Among HIV-infected women, CD4 count ≥500 cells/mm(3) versus <500 cells/mm(3) was associated with higher HHV-8 copy number (4.8 log10  copies/ml vs. 3.4 log10  copies/ml; coef 1.2 [95% CI, 0.5-1.9]; P = 0.001) and a higher HHV-8 shedding rate (49% vs.12%; RR, 4.2 [95% CI, 0.8-21.4]; P = 0.08). No other factors were associated with HHV-8 shedding rate or copy number. The study demonstrates high rates and quantity of HHV-8 in the oropharynx of HHV-8 seropositive African women. These findings support the observation that oral replication is an essential feature of HHV-8 infection, with likely implications for HHV-8 transmission and KS pathogenesis.

Kaposi's sarcoma-derived cell line SLK is not of endothelial origin, but is a contaminant from a known renal carcinoma cell line

Kaposi's sarcoma (KS) is an endothelial cell-derived tumor. Investigations of the molecular mechanisms of KS pathogenesis and the identification of drugs for treatment of KS depend critically on valid cell-culture models. Two major immortalized cell lines are available for KS research. Recently, the KS cell line KS Y-1 has been shown to be cross-contaminated with the T24 urinary bladder cancer cell line (ATCC HTB-4). Here, we show by short tandem repeat profiling that the second KS cell line, SLK, is indistinguishable from the clear-cell renal-cell carcinoma cell line Caki-1. Immunocytochemical detection of cytokeratin expression confirmed the epithelial-cell origin of SLK cells. Our findings indicate that SLK cells are not of endothelial origin and should not be used in future studies as a model for KS-derived endothelial tumor cells. We suggest that in the future, more attention needs to be paid to the authenticity of cells in lines derived from human tissues.

Human immunodeficiency virus endocrinopathy

Human immunodeficiency virus (HIV) endocrinopathy encompasses a broad spectrum of disorders. Almost all the endocrine organs are virtually affected by HIV infection. HIV can directly alter glandular function. More commonly secondary endocrine dysfunction occurs due to opportunistic infections and neoplasms in immunocompromised state. The complex interaction between HIV infection and endocrine system may be manifested as subtle biochemical and hormonal perturbation to overt glandular failure. Antiretroviral therapy as well as other essential medications often result in adverse endocrinal consequences. Apart from adrenal insufficiency, hypogonadism, diabetes and bone loss, AIDS wasting syndrome and HIV lipodystrophy need special reference. Endocrinal evaluation should proceed as in other patients with suspected endocrine dysfunction. Available treatment options have been shown to improve quality of life and long-term mortality in AIDS patients.

Luteinizing hormone receptor deficiency increases the susceptibility to alkylating agent-induced lymphomagenesis in mice

Previous studies have revealed a close link between luteinizing hormone (LH)/human chorionic gonadotropin (hCG) signaling and oncogenesis in gonadal and nongonadal tissues. To investigate whether genetic ablation of LH receptor (Lhr) affects the animal's oncogenic susceptibility, adult female wild-type (wt), heterozygous, and homozygous Lhr knockout (LhrKO) mice were intraperitoneally injected with an alkylating agent, N-methyl-N-nitrosourea (MNU, 50 mg/kg of body weight). The mice were sacrificed when they were short of breath or 10 months after the injection. The results showed that MNU induced non-Hodgkin's thymic and lymphonodus lymphomas in 70.6% and 100% of heterozygous and homozygous animals, respectively, compared with 35.7% in wt siblings. The tumor development was rapid; they were more aggressive and metastasized to the spleen, liver, and kidney in Lhr-deficient mice compared to wt siblings. All tumors were immunostained-positive for a T-cell specific marker, CD3, but not for a B-cell marker, CD22, suggesting that all the lymphomas arose from T-cells, which are known to be LH/hCG receptor-positive. There was no rearrangement of the Lhr gene locus or differences in thymic cell proliferation among the genotypes. However, apoptosis was lower in the Lhr-deficient thymuses. The thymic Bcl-2 levels were elevated and caspase-3 activation was reduced in Lhr heterozygous and homozygous animals. In conclusion, MNU induced a higher incidence and an earlier onset of aggressive lymphomas in LhrKO animals, which may be associated with a reduction in apoptosis of thymocytes.

Gender differences in clinical presentation and outcomes of epidemic Kaposi sarcoma in Uganda

Introduction

The incidence of Kaposi sarcoma (KS) has increased dramatically among women in sub-Saharan Africa since the onset of the HIV pandemic, but data on KS disease in women are limited. To identify gender-related differences in KS presentation and outcomes, we evaluated the clinical manifestations and response in men and women with AIDS-associated KS in Uganda.

Methods and Findings

HIV-infected adults with KS attending the Infectious Diseases Institute (IDI) and Uganda Cancer Institute (UCI) in Kampala, Uganda between 2004 and 2006 were included in a retrospective cohort. Evaluation of KS presentation was based on the clinical features described at the initial KS visit. Response was evaluated as the time to “improvement”, as defined by any decrease in lesion size, lesion number, or edema. The cohort consisted of 197 adults with HIV and KS: 55% (108/197) were women. At presentation, the median CD4 T-cell count was significantly lower in women (58 cells/mm³; IQR 11–156 cells/mm³) than men (124 cells/mm³; IQR 22–254 cells/mm³) (p = 0.02). Women were more likely than men to present with lesions of the face (OR 2.8, 95% CI, 1.4, 5.7; p = 0.005) and hard palate (OR 2.0, 95% CI, 1.1, 3.7; p = 0.02), and were less likely than men to have lower extremity lesions (OR 0.54, 95% CI, 0.3, 0.99; p = 0.05). Women were less likely than men to demonstrate clinical improvement (HR = 0.52, CI 0.31, 0.88; p = 0.01) in multivariate analysis.

Conclusions

The clinical presentation and response of KS differs between men and women in Uganda. These data suggest that gender affects the pathophysiology of KS, which may have implications for the prevention, diagnosis, and treatment of KS in both men and women. Prospective studies are needed to identify predictors of response and evaluate efficacy of treatment in women with KS, particularly in Africa where the disease burden is greatest.

Characteristics of HIV-1-associated Kaposi's sarcoma among women and men in South Africa

Despite the increase of HIV-1-associated Kaposi's sarcoma (KS), little is known about HIV-associated KS in the African setting, particularly among women. A descriptive study of the demographic, clinical, immunological and virological features of AIDS-associated KS from KwaZulu-Natal, South Africa was undertaken. Consecutively, recruited patients were clinically staged; CD4/CD8 cell counts, HIV-1 viral loads and clinical parameters were evaluated. Of the 152 patients (77 male and 75 female) 99% were black. Females were significantly younger (P = 0.02) and had poorer disease prognosis (odds ratio [OR] = 2.7, 95% confidence interval [CI] = 1.4-5.4, P = 0.003) and were more likely to have extensive cutaneous KS when compared with males (OR = 3.1, 95% CI = 1.4-6.7, P = 0.003). One-third of patients had coexisting HIV-related disease, most commonly tuberculosis, and these were more frequent in females (56.7 vs. 43.3%). In conclusion, HIV-associated KS in South Africans has an equal female-to-male ratio. Females are younger and have more severe disease than males.

Purified human chorionic gonadotropin induces apoptosis in breast cancer

Agents that induce apoptosis in breast cancer cells have great potential to facilitate chemotherapeutic intervention and improve patient outcomes. In this study, the effects of injecting purified human chorionic gonadotropin (hCG) directly into human breast cancer xenografts grown in nude mice were examined. It was shown that intratumoral injection of purified hCG increased the apoptotic index in breast cancer xenografts. These results were supported by the findings that exposure of breast cancer cells to purified hCG decreased cell viability in five different breast cancer cell lines. In some of these cell lines, the effects of hCG in cell viability appear to correlate with activation/expression of the hCG/luteinizing hormone receptor. Preoperative apoptotic induction by factors such as purified hCG may improve local control or work synergistically with neoadjuvant chemotherapy to improve complete pathologic response of locally advanced breast cancer.

Coexpression of human chorionic gonadotropin beta subunit and its receptor in nontrophoblastic gynecological cancer

A considerable number of biochemical and physiologic studies evaluate the roles of gonadotropins in carcinogenesis. Latest reports show that human chorionic gonadotropin (hCG), and especially its beta subunit, are secreted by a variety of malignant tumors of different origin. However, the mechanism of hCG action and its role in tumor development is not known yet. This study, with the help of reverse transcription-polymerase chain reaction and immunohistochemistry, is an attempt to document the molecular presence of the hCGβ and luteinizing hormone/hCG receptor (LH/hCGR) in the ovarian, endometrial, and uterine cervix cancer tissues. The LH/hCGR, coexpressed with hCGβ, may act as a potential mediator of hCG action in nontrophoblastic gynecological cancers

Complement insufficiency limits efficacy in a xenograft model of hyperacute rejection for cancer therapy

Hyperacute rejection (HAR) is a rapid immunological response to an organ xenotransplant caused by recognition of endothelial galactose(alpha1,3)galactose (alphaGal) epitopes and complement-mediated cell lysis by host anti-alphaGal antibody ('natural antibody'). The alphaGal epitope is synthesised by a galactosyl transferase ((alpha1,3)GT) which humans lack. Because human cells transduced with (alpha1,3)GT are sensitised to natural antibody/complement-mediated lysis in human serum, delivery of (alpha1,3)GT to tumour vasculature in patients is a potential therapeutic strategy, by mimicking the pathophysiology of organ rejection. We therefore sought to develop an animal model of HAR for cancer therapy. Nude/(alpha1,3)GT knock-out mice allowed the growth of human tumour xenografts and the use of ecotropic retrovirus producer cells to generate expression of alphaGal on tumour vasculature. Lysis of alphaGal-positive murine endothelial cells with rabbit complement in conjunction with murine anti-alphaGal antibody in vitro was used to define the conditions necessary for HAR. However, tumour growth retardation and destruction of alphaGal-positive tumour endothelium were minimal after their administration, despite sera retaining post hoc cytolytic activity with fresh complement. The major limitation of this experimental system, of relevance to other therapeutic approaches, results from the use of a xenograft, in which additional xenoreactivities lead to complement insufficiency. Development of a tractable preclinical model in which to evaluate HAR for cancer therapy requires a syngeneic experimental system.

Role of environmental factors in the pathogenesis of classic and African-endemic Kaposi sarcoma

Kaposi sarcoma (KS) is a mesenchymal tumour associated with human herpesvirus-8 (HHV-8) infection. However, the incidence of HHV-8 infection is far higher than the prevalence of KS, suggesting that viral infection per se is not sufficient for the development of aggressive phenotype and that one or more additional cofactors are required. The great geographical variation in African-endemic and classic KS incidence points to a role for environmental factors in the etiology of Kaposi sarcoma. However, there are few unequivocably established environmental factors involved in KS pathogenesis. This review focuses on the environmental factors thought to be associated with KS, more particularly iron exposure and facilitation of transmission of HHV-8 infection by contact with blood-sucking arthropods.

Promoter switching allows simultaneous transcription of LANA and K14/vGPCR of Kaposi's sarcoma-associated herpesvirus

Latent transcription of the latency-associated nuclear antigen (LANA/ORF73) of Kaposi's sarcoma-associated herpesvirus is driven by the LANAp-c. Complexity arises during lytic reactivation, however, as the bicistronic K14/vGPCR transcript initiates 32 bp downstream of LANAp-c in the opposite orientation. We identify an Rta/ORF50-inducible LANA promoter (LANAp-i) that is distinct from the LANAp-c. LANAp-c is unaffected by Rta/ORF50. Utilization of the second, downstream LANAp-i explains how LANA and K14/vGPCR are simultaneously transcribed during de novo infection or lytic reactivation. Transactivation of LANAp-i and K14/vGPCRp requires the C-terminal activation domain of Rta/ORF50 and is mediated by DNA-binding-dependent and -independent Rta/ORF50 mechanisms. Transcriptional profiling following viral reactivation support promoter reporter phenotypes. In sum, cis-elements within the LANAp were selected to ensure faithful expression of LANA and other genes regulated by LANAp during all stages of the KSHV lifecycle despite potential interference from K14/vGPCRp activity.

Identification of placental transforming growth factor-beta and bikunin metabolites as contaminants of pharmaceutical human chorionic gonadotrophin preparations by proteomic techniques

A contaminant protein complex found in pharmaceutical urinary human chorionic gonadotrophin preparations is reported to have anti-human immunodeficiency virus-associated Kaposi's sarcoma activity. The aim of this study was to isolate and characterize this protein complex by proteomic approaches. Size exclusion chromatography was used in the isolation of these human chorionic gonadotrophin-associated fragments. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the presence of a protein complex that dissociated into two protein bands under reducing conditions. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of this complex showed three polypeptides at approximately 6.2, 11.4, and 15.8 kDa. Peptide mass mapping and N-terminal amino acid sequencing identified two polypeptides as metabolites of placental transforming growth factor-beta (11.4 kDa) and bikunin (15.8 kDa). Subsequent matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of the anti-human immunodeficiency virus-associated Kaposi's sarcoma active preparations CG-10 (Sigma), Pregnyl (Organon), and Profasi (Serono) revealed the presence of metabolites of placental transforming growth factor-beta in all three; no other non-human chorionic gonadotrophin-related protein species were observed in these preparations. Our findings present evidence that urinary human chorionic gonadotrophin preparations are contaminated with metabolites of placental transforming growth factor-beta, which may have transforming growth factor-beta agonist actions, and metabolites of bikunin, which is a protease inhibitor. In combination these molecules may be responsible for the anti-human immunodeficiency virus-associated Kaposi's sarcoma activity demonstrated for these urinary human chorionic gonadotrophin preparations.

Novel pharmacological therapies for the treatment of AIDS-related Kaposi’s sarcoma

Kaposi's sarcoma (KS) is the most common cancer associated with AIDS. KS aetiology and pathogenesis are still poorly defined and no definitive treatment has yet been identified. However, the introduction in 1996 of highly active antiretroviral therapy as a standard of care for those infected with HIV-1 determined a strong protection against the development of opportunistic infections, as well as a remission of pre-existing complications, including KS. Under highly active antiretroviral therapy, KS in particular has shown the highest clinical response rate reported to date among AIDS patients. Furthermore, recent insights into the pathogenetic mechanisms involved in KS development have provided new hope for a response and improved survival in patients with AIDS-related KS. This paper presents an overview of the current knowledge concerning pharmacological approaches to treating this disease. Newer treatments such as PEGylated liposomal anthracyclin, paclitaxel and pathogenesis-based strategies are also discussed.

Uncovering the complexities of Kaposi's sarcoma through genome-wide expression analysis

Gene-expression profiling of endothelial cells infected with Kaposi's sarcoma-associated herpesvirus has led to a greater understanding of the histogenesis and pathogenesis of Kaposi's sarcoma.

Gene-expression profiling of endothelial cells infected with Kaposi's sarcoma-associated herpesvirus has led to a greater understanding of the histogenesis of Kaposi's sarcoma and cellular reprogramming events that occur as a result of viral infection and that may play important roles in viral pathogenesis.

Animal models of cancer and HIV

PURPOSE OF REVIEW

The purpose of this paper is to review current animal models that may be useful for studying cancer associated with human immunodeficiency virus infection.

RECENT FINDINGS

Several animal models, primarily using mice and monkeys, have been developed that recapitulate aspects of the pathology of various malignancies in human acquired immune deficiency syndrome. Studies reviewed here help to elucidate the biology of Kaposi sarcomagenesis and non-Hodgkin lymphomagenesis. Improved understanding through current and future models will better enable clinicians to manage and treat these malignancies.

SUMMARY

A number of potential useful models exist that may facilitate improved understanding of the pathogenesis and treatment of cancers associated with human immunodeficiency virus infection.

Epidermal growth factor contamination and concentrations of intact human chorionic gonadotropin in commercial preparations

It is well-known that many urinary-derived human chorionic gonadotropin (hCG) preparations contain a variety of contaminating agents that may influence the efficacy and possible safety of their application. Herein, we report the finding of epidermal growth factor (EGF) contamination and high hCG beta core levels in two leading brands of hCG - findings that will promote the use of recombinant hCG instead of the cruder, urinary-derived formulations.

Comparison of the Rta/Orf50 transactivator proteins of gamma-2-herpesviruses

The viral immediate-early transactivator Rta/Orf50 is necessary and sufficient to initiate Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) reactivation from latently infected cells. Since Rta/Orf50 is conserved among all known gamma-2-herpesviruses, we investigated whether the murine gamma-68-herpesvirus (MHV-68) and rhesus monkey rhadinovirus (RRV) homologs can functionally substitute for KSHV Rta/Orf50. (i) Our comparison of 12 KSHV promoters showed that most responded to all three Rta/Orf50proteins, but three promoters (vGPCR, K8, and gB) responded only to the KSHV Rta/Orf50 transactivator. Overall, the activation of KSHV promoters was higher with KSHV Rta than with the RRV and MHV-68 Rta. (ii) Only the primate Rta/Orf50 homologs were able to interfere with human p53-depedent transcriptional activation. (iii) Transcriptional profiling showed that the KSHV Rta/Orf50 was more efficient than it's homologs in inducing KSHV lytic transcription from the latent state. These results suggest that the core functionality of Rta/Orf50 is conserved and independent of its host, but the human protein has evolved additional, human-specific capabilities.

Retroviral hybrid LTR vector strategy: functional analysis of LTR elements and generation of endothelial cell specificity

Transcriptional targeting is an important aspect of developing gene therapy vectors in order to restrict transgene expression to selected target cells. One approach, when using retroviral vectors, is to replace viral transcriptional control elements within the long terminal repeat (LTR) with sequences imparting the desired specificity. We have developed such hybrid LTR retroviruses, incorporating sequences from each of the human promoters for flt-1, ICAM-2 and KDR, as part of our antivascular cancer gene therapy strategy targeting tumour endothelial cells. The chosen fragments were used to replace the enhancer or combined enhancer and proximal promoter regions of the viral LTR. All showed activity in primary human breast microvascular endothelial cells, with viruses incorporating ICAM-2 sequences exhibiting the greatest specificity versus nonendothelial cells in vitro and a marked alteration of specificity towards endothelial cells in a subcutaneous xenograft model in vivo. Moreover, our study documents the effect of enhancer and/or proximal promoter deletion on LTR activity and reports that differential dependence in different cell lines can give the false impression of specificity if experiments are not adequately controlled. This finding also has implications for other retroviral vector designs seeking to provide transcriptional specificity and for their safety with respect to prevention of gene activation at sites of proviral integration.

Iron: a target for the management of Kaposi's sarcoma?

BACKGROUND

Kaposi's sarcoma (KS) is a mesenchymal tumour associated with human herpesvirus-8 infection. However, the incidence of human herpesvirus-8 infection is far higher than the prevalence of KS, suggesting that viral infection per se is not sufficient for the development of malignancy and that one or more additional cofactors are required.

DISCUSSION

Epidemiological data suggest that iron may be one of the cofactors involved in the pathogenesis of KS. Iron is a well-known carcinogen and may favour KS growth through several pathways. Based on the apoptotic and antiproliferative effect of iron chelation on KS cells, it is suggested that iron withdrawal strategies could be developed for the management of KS. Studies using potent iron chelators in suitable KS animal models are critical to evaluate whether iron deprivation may be a useful anti-KS strategy.

SUMMARY

It is suggested that iron may be one of non-viral co-factors involved of KS pathogenesis and that iron withdrawal strategies might interfere with tumour growth in patients with KS.

A Trial Study: The Effect of Low Dose Human Chorionic Gonadotropin on the Symptoms of Benign Prostatic Hyperplasia

PURPOSE

Human chorionic gonadotropin (HCG) is a glycoprotein hormone with multiple physiological functions. It interferes with mammary tumorigenesis and modulates growth and tumorigenesis in prostate cancer cells. In addition, HCG receptor transcripts and protein have been demonstrated in normal and hyperplastic prostate glands. Functionally HCG has a growth modulating effect on androgen independent prostate cell lines. We investigated the possible clinical effects of HCG on the symptoms associated with benign prostatic hyperplasia (BPH) in this trial study.

MATERIALS AND METHODS

We performed a multicenter, double-blind, placebo controlled, randomized pilot study evaluating the effects of low dose HCG vs placebo in 101 men (50 to 79 years old) with BPH. The primary efficacy measure was the American Urological Association total symptom index score. Secondary efficacy parameters included peak urinary flow and sexual self-efficacy questionnaire changes.

RESULTS

Low dose HCG appeared to positively effect moderate to severe BPH symptoms according to American Urological Association scores and sexual function but not peak urinary flow. No HCG induced changes were noted in prostate specific antigen or prostate volume.

CONCLUSIONS

These findings suggest that HCG may provide a well tolerated and beneficial therapy for BPH that will be investigated in subsequent studies.

Human herpesvirus 8 K1-associated nuclear factor-kappa B-dependent promoter activity: role in Kaposi's sarcoma inflammation?

BACKGROUND

The growing number of human immunodeficiency virus type 1 (HIV-1) infections worldwide and the increasing use of immunosuppressive modalities for organ transplantation have contributed to an epidemic of Kaposi's sarcoma (KS), which has been etiologically linked to human herpesvirus 8 (HHV8) or KS-associated virus. Since the onset of the acquired immunodeficiency syndrome epidemic, inflammation has been recognized as an essential component of KS pathology. HHV8 bears a gene (K1) encoding a transmembrane protein with an immunoreceptor tyrosine-based activation motif. This motif is present in receptors that mediate inflammation.

PURPOSE

To dissect the cellular effects of K1 function and the eventual role of K1 in KS, we developed a cell model for studying K1 expression.

METHODS

K1 was cloned from BC-3 lymphoma cells. To monitor transcriptional activation, K1 was coexpressed with plasmids containing luciferase under control of various promoters. K1 expression was monitored by indirect immunofluorescence and by combined immunoprecipitation/immunoblot analysis. Inflammatory cytokines were measured by enzyme-linked immunosorbent assay.

RESULTS

Cellular transfection of the K1 gene induced reporter expression under control of nuclear factor-kappa B (NF-kappaB), which controls the transcription of numerous proteins involved in inflammation. Treatment of cells with aspirin, an agent that targets this intracellular pathway and blocks cell inflammatory responses, blocked K1-induced NF-kappaB-dependent promoter activity. When a second KS cofactor, i.e., the HIV-1-transactivating gene tat, was coexpressed with K1, we observed an additive effect on NF-kappaB-dependent transcription. K1 transfection stimulated the secretion of cytokines interleukin (IL) 6, granulocyte-macrophage colony-stimulating factor, and IL-12. Cells treated with the conditioned media of K1 transfectants exhibited similar characteristics of K1 transfectants, indicating that a paracrine loop was being activated.

CONCLUSION

Thus, K1 may activate cells in which it is expressed, as well as other cells in a paracrine manner. K1 cooperates in signaling with HIV-1 Tat, suggesting that both of the proteins from these viruses converge to reach an enhanced level of inflammation that may underlie progressive KS.

Molecular genetics of Kaposi's sarcoma-associated herpesvirus (human herpesvirus-8) epidemiology and pathogenesis

Kaposi's sarcoma had been recognized as unique human cancer for a century before it manifested as an AIDS-defining illness with a suspected infectious etiology. The discovery of Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, in 1994 by using representational difference analysis, a subtractive method previously employed for cloning differences in human genomic DNA, was a fitting harbinger for the powerful bioinformatic approaches since employed to understand its pathogenesis in KS. Indeed, the discovery of KSHV was rapidly followed by publication of its complete sequence, which revealed that the virus had coopted a wide armamentarium of human genes; in the short time since then, the functions of many of these viral gene variants in cell growth control, signaling apoptosis, angiogenesis, and immunomodulation have been characterized. This critical literature review explores the pathogenic potential of these genes within the framework of current knowledge of the basic herpesvirology of KSHV, including the relationships between viral genotypic variation and the four clinicoepidemiologic forms of Kaposi's sarcoma, current viral detection methods and their utility, primary infection by KSHV, tissue culture and animal models of latent- and lytic-cycle gene expression and pathogenesis, and viral reactivation from latency. Recent advances in models of de novo endothelial infection, microarray analyses of the host response to infection, receptor identification, and cloning of full-length, infectious KSHV genomic DNA promise to reveal key molecular mechanisms of the candidate pathogeneic genes when expressed in the context of viral infection.

Pathogenesis of Kaposi's sarcoma

Kaposi's sarcoma (KS) is a disease characterized by proliferative vascular lesions, which almost invariably contain the KS-associated herpesvirus (KSHV), also called human herpesvirus 8. KSHV is a lymphotrophic and angiotrophic herpesvirus, whose genome encodes several proteins involved in proliferation, antiapoptotic functions, and inflammation. Most KS spindle cells express latent KSHV genes, but a few express lytic genes, which might be involved in angiogenic and paracrine mechanisms that contribute to KS pathogenesis. A number of tissue culture and mouse models have been established, but a comprehensive system that accurately portrays KS pathogenesis still does not exist.

Factors associated with human herpesvirus type 8 infection in an injecting drug user cohort

BACKGROUND

Human herpesvirus type 8 (HHV-8) has been infrequently studied in injecting drug user (IDU) populations.

GOAL

To estimate the seroprevalence of HHV-8 and risk factors for infection in a cohort of 2,946 IDUs.

STUDY DESIGN

In this nested cross-sectional study of 390 IDUs, lytic HHV-8 indirect immunofluorescence assay (IFA) was utilized to estimate the HHV-8 seroprevalence. Multivariate logistic regression was used to assess risk factors for infection.

RESULTS

The HHV-8 seroprevalence among the IDUs examined in 1988 was 11.5% (95% confidence interval, 8.5-15.13). HHV-8 seroprevalence in this population was associated with being female (OR = 2.2; = 0.080), having a larger body mass index (OR = 3.0; = 0.053), and history of genital warts (OR = 4.0; = 0.023). Injection of any drug more than daily exhibited an inverse effect on HHV-8 seropositivity (OR = 0.5; = 0.085).

CONCLUSION

The seroprevalence of HHV-8 in this population is similar to that seen in the general population, with risk factors being more consistent with sexual behaviors than injection drug use.

Kaposi's sarcoma: aetiopathogenesis, histology and clinical features

Kaposi's sarcoma (KS) represents today one of the most common skin cancers in transplanted Mediterranean subjects and, since the epidemic of human immunodeficiency virus/acquired immune deficiency syndrome, in young unmarried single men. The disease has been associated with the recent identified human herpesvirus (HHV)-8 or KS herpesvirus and its incidence in the general population shows a north to south gradient that parallels the HHV-8 increasing prevalence from Nordic countries to sub-Saharan regions. The identification of the aetiopathogenetic mechanisms (viral agents and immunodeficiency) involved in the pathogenesis of KS, are relevant for identifying susceptible subjects (HHV-8 seropositive subjects), monitoring the immune levels in iatrogenic immune suppressed patients, and developing new therapeutic approaches based on antiviral and immune modulators.

LEARNING OBJECTIVE

This article should enable the reader: (i) to learn about the clinical and molecular aspects of KS in order to have a multidisciplinary approach to a tumour that shows unique features; (ii) to consider the role of viral agents and immunity; and (iii) to recognize properties of an opportunistic neoplasm. The identification of the HHV-8 role in KS pathogenesis should establish a relevant tool in the clinical management of KS patients.

Interleukin-2 and cancer: critical analysis of results, problems and expectations

The cancer process in a combination of two kinds of events: a multistep cellular genetic defects giving cells independent growth and great adaptation capability, a multistep interactions profiles with what is called the stromal reaction from the original in situ tumor to the invasive metastatic and angiogenic tumor. The immune system plays an important role in the control of the cancer process but always must be seen as a part integrated in the stromal reaction. In order to boost the immune system capability to treat a cancer we must never forget these cellular and tissular dimensions. Interleukins, growth factors and monoclonal antibodies are new agents are able to bring immunotherapy of cancer to reality. Interleukin 2 did not match our dreams of the ideal factor which can stimulate the defective immune system and bring the cancer evolution to an end. The little but real remissions obtained with the IL-2 high dose protocols still sustains our trust of the immune system as a critical barrier to cancer evolution but the numerous side effects reminds us that cytokines are not to be used as antibiotics and hormones. IL-2 is a regulator of the immune system at the microenvironment level, therefore flooding the blood circulation with high IL-2 doses is not appropriate. We have also to understand that IL-2 can interact directly with cancer cells and also with stromal cells (endothelial and fibroblastic cells), the outcome of IL-2 immunotherapy is not restricted to the interactions with immune cells.

Recent advances in the treatment of AIDS-related Kaposi's sarcoma

Kaposi's sarcoma (KS) is the most common malignancy associated with HIV infection and is considered an AIDS defining condition by the US Centers of Disease Control Guidelines. Several advances in the treatment of AIDS-related KS have been achieved over the past few years, even though a gold standard therapy for KS has not yet been defined and treatment must be tailored to individual needs. Since the availability of highly active antiretroviral therapy (HAART), a dramatic clinical response has been documented in patients with KS, making HAART an essential approach in the management of KS in most, if not all, patients with AIDS-related KS. However, in case of aggressive, visceral, and/or life-threatening KS, more complex therapeutic schedules have to be taken into account, including chemotherapy, radiotherapy, and/or immunotherapy. In general, systemic treatment for KS is limited to widespread, symptomatic disease, whereas local interventions are indicated for minimal, cosmetically troublesome lesions. Among new cytotoxic agents, liposomal anthracyclines and paclitaxel are highly effective molecules for KS and have been approved by the US Food and Drug Administration (FDA) as first-line and second-line monotherapy, respectively, for advanced KS. Furthermore, a greater understanding of the pathogenesis of KS has lead to the development of an array of new experimental agents. Many antiangiogenic agents such as AGM 1470 (TNP 470), thalidomide, and glufanide disodium (IM 862) have produced encouraging responses in patients with KS and large clinical trials are in progress. Retinoic acids may also block neoangiogenesis as well as proliferation of KS cells in vitro, and they have been used either systemically or topically with a high response rate. Thus, a topical compound 0.1% alitretinoin gel was approved in 1999 by the FDA for the treatment of skin lesions associated with KS. Human chorionic gonadotropin, a hormonal agent, has shown a strong inhibitory activity in KS cells, but its role in the regression of KS lesions is not clear. Finally, the identification of a novel gamma-herpesvirus, human herpesvirus-8, as a causative agent for KS, together with novel antiangiogenic compounds, such as metalloproteinase inhibitors, may offer promising targets for the therapy of KS.

Virology, pathogenetic mechanisms, and associated diseases of Kaposi sarcoma-associated herpesvirus (human herpesvirus 8)

Kaposi sarcoma-associated herpesvirus (KSHV) is a recently discovered and characterized member of the herpesvirus family. It is one of a few viruses proved to be associated with tumorigenesis in humans. Its causal association with 4 clinical and epidemiologic variants of Kaposi sarcoma (classic, endemic, iatrogenic, and acquired immunodeficiency virus-associated) as well as with several lymphoproliferative disorders (notably primary effusion lymphoma and multicentric Castleman disease) is reviewed critically. Issues related to the epidemiology, transmission, and molecular and serologic diagnosis are discussed. Several intriguing oncogenic mechanisms of KSHV infection have been identified. These are often dependent on the interaction of KSHV with other viruses, such as human immunodeficiency virus, Epstein-Barr virus, or both. However, important problems remain and once resolved will substantially enhance our understanding of oncogenesis in general and viral-induced oncogenesis in particular. This may also translate into improved treatment and perhaps prevention of this common and intriguing viral infection.

Kaposi's sarcoma and human chorionic gonadotropin: mechanisms, moieties and mysteries

Kaposi's Sarcoma (KS) is a highly angiogenic neoplasm associated with infection by the human gamma-herpesvirus, HHV-8 or Kaposi's sarcoma herpes virus (KSHV). When in 1872 the Hungarian scientist Moritz Kaposi described the sarcoma, which was later named after him, he was dealing with a rare dermatologic disease. Today, KS is a more common pathology due to its high incidence in AIDS, in immuno-suppressed transplantation patients and, in its endemic form, in Africa. The introduction of highly active antiretroviral therapy (HAART) has led to a drastic reduction of KS incidence in HIV-infected patients, but in some cases KS resists the treatment. KS is more common in men than in women. The observation of spontaneous remissions during pregnancy stimulated investigations into the potential anti-KS activity of the pregnancy hormone human chorionic gonadotropin (hCG). The variable effect in clinical trials using urinary preparations of the hormone (u-hCG) has led to the hypothesis that contaminating moieties present in these preparations may account for the anti-KS effect observed in vitro. While the discrepancy between laboratory tests and clinical trials remains a mystery, little is known about potential anti-KS mechanisms of the hormone itself and/or other active moieties present in u-hCG.

Stimulation of Kaposi's sarcoma cell growth by urine from women in early pregnancy, the current source for clinical-grade human chorionic gonadotropin preparations

Clinical-grade preparations of human chorionic gonadotropin (hCG) have been shown to be toxic to Kaposi's sarcoma (KS) cells. However, the results of clinical studies using commercial hCG preparations KS remain highly contradictory. More particularly, some hCG preparations could have a paradoxical growth effect on KS. Such discrepant results may be explained by the fact that the anti-KS activity is not associated with hCG itself but with one or more factors that are co-purified with the hormone. We found here that crude urine from first trimester pregnant women, the current source for commercial hCG, had a growth stimulatory effect on KS cells. By contrast, urine from last trimester pregnant women, from non-pregnant young women, from menopausal women and from men exhibited neither a growth stimulatory nor a growth inhibitory effect on KS cells. The amplitude of this pregnancy urine-associated pro-KS activity/hCG unit was higher than that achieved with clinical-grade hCG preparations. Partial co-purification of pregnancy-associated factors during the extraction procedure of commercial hCG from urine may explain the pro-KS activity achieved with some hCG preparations. We, therefore, suggest a cautious use of hCG purified from pregnancy urine for the treatment of KS.

Human chorionic gonadotropin inhibits Kaposi's sarcoma associated angiogenesis, matrix metalloprotease activity, and tumor growth

Kaposi's sarcoma is a highly angiogenic, AIDS-associated neoplasm that is more frequent in male than in female patients. Cases of spontaneous regression during pregnancy have been reported and the pregnancy hormone human chorionic gonadotropin (hCG) has shown anti-Kaposi's sarcoma activity in several, but not all, clinical trials. Antiproliferative and proapoptotic activities specific for Kaposi's sarcoma (KS) cells have been shown. We report here further analyses of the anti-KS activity of the hormone and show that urinary hCG, the hCG beta-subunit, the hCG beta-core, and to a lesser extent a recombinant hCG, directly inhibit the activity of matrix metalloproteases of different origin. The hCG hormone also inhibited angiogenesis in vivo in the matrigel sponge assay as well as growth of KS cell xenografts in nude mice. The effect of the pure recombinant hormone dimer on xenograft growth was transient, indicating that the activity of intact hCG alone is not sufficient to overcome the growth potential of this tumor and suggesting that active hCG fragments or other anti-KS activities contribute to the activity of urinary hCG.

Primary Research: Short Communication: Evidence Supporting Rare AIDS-Kaposi's Sarcoma Metastasis In Keeping With Their Vascular Endothelial Evolution

BACKGROUND: It is postulated that the unusual manifestations of Kaposis's sarcoma cells in nonendothelial brain tissues and on eyeballs in advanced acquired immune deficiency syndrome (AIDS) cases are metastasized AIDS-Kaposi's sarcoma cells arising from vascular endothelial cells. METHODS: Experiments were performed to explore the above hypothesis by testing for intercellular adhesion molecule-1 (CD54 antigens) on cutaneous AIDS-Kaposi's sarcoma cells as well as on AIDS-Kaposi's sarcoma cells isolated from eyeballs as studies have illustrated that, unlike localized Kaposi's sarcoma cells of primary lesions, proliferating Kaposi's sarcoma cells in proximity to primary lesions express a negative or diminished phenotype when evaluated for identical surface antigens. Parallel CD54 antigen tests were done on vascular endothelial cells and monocytes/macrophages as endothelial cells are considered evolutionarily related to Kaposi's sarcoma cells and monocytes/macrophages are ideal CD54 antigen positive controls. RESULTS: Our data showed that only AIDS-Kaposi's sarcoma cells of the eyes did not express CD54 antigens. CONCLUSIONS: We therefore report that our findings support the postulation suggesting AIDS-Kaposi's sarcoma dissemination in advanced AIDS patients in keeping with their vascular endothelial heredity.

Desferrioxamine enhances AIDS-associated Kaposi's sarcoma tumor development in a xenograft model

Iron is suspected to be involved in the induction and/or progression of various human tumors. More particularly, we have previously shown that iron may be involved in the pathogenesis of Kaposi's sarcoma (KS). We have also shown that the iron chelator desferrioxamine (DFO) has a potent anti-KS activity in vitro, suggesting that it may represent a potential therapeutic approach for the treatment of KS. The present study was designed to investigate the effect of DFO on the growth of human KS xenografts in immunodeficient mice. Unexpectedly, we found that mice treated with DFO (400 mg/kg, 3 times weekly) (n = 30) exhibited a marked enhancement of tumor growth compared with control mice (n = 33) (230 +/- 134 mm(2) versus 143 +/- 70 mm p < 0.01). No enhancement of tumor growth was seen in mice treated with iron-saturated DFO. At least 2 findings suggest that this paradoxic pro-KS activity occurred independently of mice iron stores. First, treatment with DFO had only a marginal effect on ferritin and hematocrit levels. Second, induction of effective iron depletion by an iron-poor diet (6.7 mg iron/kg diet) (n = 23) did not have a deleterious effect on the growth of the KS xenografts. The lesions obtained from the DFO-treated animals exhibited a significantly decreased apoptotic index (p < 0.05), indicating that some antiapoptotic mechanism induced by DFO may be operating in vivo to favour tumor growth. In conclusion, our data show that DFO has a stimulatory effect on KS growth in immunodeficient mice, suggesting that this drug is not indicated in patients with KS.

AIDS-related malignancies

Cancer remains a significant burden for human immunodeficiency virus (HIV)-infected individuals. Most cancers that are associated with HIV infection are driven by oncogenic viruses, such as Epstein-Barr virus, Kaposi's sarcoma-associated herpesvirus and human papillomavirus. Gaining insight into the epidemiology and mechanisms that underlie AIDS-related cancers has provided us with a better understanding of cancer immunity and viral oncogenesis.

AIDS and non-AIDS-related malignancies: a new vexing challenge in HIV-positive patients. Part I: Kaposi's sarcoma, non-Hodgkin's lymphoma, and Hodgkin's lymphoma

HIV-infected patients are at an increased risk for developing cancers. Three, in particular, are considered to be AIDS-defining malignancies: Kaposi's sarcoma (KS), non-Hodgkin's lymphoma (NHL), and cervical cancer. Other non-AIDS-defining malignancies have been reported in the setting of HIV infection as having an increased frequency compared with their incidence in the general population. One of those most frequently reported is Hodgkin's disease. As with KS and NHL, the problem of diagnosing and treating immunocompromised patients with cancer represents a formidable challenge. Moreover, a newly discovered human gamma-herpes virus, human herpes virus-8 (HHV-8), has been identified in over 90% of KS lesions from patients with and without AIDS, suggesting its etiological importance in the development of KS and new therapeutic approaches.

Update on Kaposi's sarcoma and other HHV8 associated diseases. Part 1: epidemiology, environmental predispositions, clinical manifestations, and therapy

Kaposi's sarcoma (KS) is a mesenchymal tumour involving blood and lymphatic vessels. Only recently has the pathogenesis of this extraordinary neoplasm been elucidated. Viral oncogenesis and cytokine-induced growth together with some state of immunocompromise represent important conditions for this tumour to develop. In 1994, a novel virus was discovered and termed human herpesvirus 8 (HHV8), also known as Kaposi's sarcoma-associated herpes virus, which can be found in all types of KS, whether related to HIV or not. In the era of highly active antiretroviral therapy (HAART), the incidence of AIDS-KS has considerably declined, probably due to enhanced immune reconstitution and anti-HHV8-specific immune responses. If HAART is able to prevent spreading of KS, local therapy of KS may become an essential component of patient management. Part 1 of the review covers the epidemiology, environmental predispositions, clinical manifestations, and therapy of KS. Newer treatments such as pegylated liposomal anthracyclines and experimental strategies are discussed. We also present rationales and graduated treatment algorithms for local and systemic therapy in patients with KS to appropriately meet the challenges of this extraordinary neoplasm. Part 2, to be published next month, will summarise recent insights in the pathogenesis of KS and will discuss other HHV8-related diseases such as Castleman's disease and primary effusion lymphoma.