AIDS Kaposi's Sarcoma Research Articles

The evaluation of human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) in cutaneous lesions of Kaposi's sarcoma: a study of formalin-fixed paraffin-embedded tissue.

The etiologic role of human herpesvirus 8 (HHV8) in Kaposi's sarcoma (KS) remains controversial. This polymerase chain reaction (PCR)-based study was undertaken to evaluate the relationship of HHV8 in KS from our geographical region and to determine its utility in formalin-fixed, paraffin-embedded biopsy specimens. Forty-two biopsy specimens were studied, including nine AIDS-associated cases and four from classic KS. Of the 39 patients included, 21 were HIV+ and 18 had no clinical evidence of HIV infection. Only a single (internal) primer pair was used in the PCR. All PCR products were tested with an HHV8 specific probe by dot blot analysis. Seven of the nine AIDS KS specimens were positive for HHV8 on electrophoresis, and all nine were positive after dot blot. Two of four specimens from classic KS were positive for HHV8 on the gel electrophoresis, and three of four were positive on blot confirmation. Non-KS specimens from 15 HIV+ patients yielded one positive venous hemangioma from a man with HHV8-positive KS at another site. Specimens from HIV-unrelated controls with a variety of diagnoses were negative by PCR with blot. The predominant negativity for HHV8 in non-KS lesions suggests that HHV8 is not widespread in our patients. These results demonstrate yet another series linking KS with HHV8 and show that paraffin-embedded biopsy specimens are satisfactory for this technique.

Trends of Kaposi's sarcoma at AIDS diagnosis in Europe and the United States, 1987-94.

As a proportion of AIDS-defining illnesses, Kaposi's sarcoma (KS) decreased from 1987-89 to 1993-94 in homosexual and bisexual men in all European regions and in the United States. Albeit underestimated, AIDS KS rates in the general male population at ages 25-49 are higher than those of the majority of cancer sites in the same age group.

AIDS-Associated Kaposi's Sarcoma Cells Secrete a Neurotrophic Growth Factor(s)

Here we treat neuronal cells with AIDS-Kaposi's sarcoma cell conditioned medium (A-KSCM) in order to determine if AIDS-Kaposi's sarcoma (A-KS) cells secrete neurotrophic factors. PC12 and NG108-15 cells were differentiated and allowed to form neuronal processes. Under these conditions and in the presence of A-KSCM, PC12 cells exhibited more than a twofold increase in the number of branches per process and a 40% increase in the number of processes per cell. For NG108-15 cells, A-KSCM treatment resulted in a threefold increase in the number of branches per process and nearly a twofold increase in the number of processes per cell. A-KS cells secrete at least seven known growth factors; however, when tested, none of these growth factors mimicked the effect of A-KSCM on neuronal cell processes. Therefore A-KS cells secrete a neurotrophic factor(s) which remains to be identified and may play a criticle role in the progression of A-KS.

A PHASE II STUDY OF THALIDOMIDE FOR KAPOSI'S SARCOMA

BACKGROUND: Thalidomide may have three possible mechanisms of action against Kaposi's sarcoma (KS). It is a selective inhibitor of synthesis of TNFα (an autocrine growth factor in KS), has anti-angiogenic activity in vivo and reduces HIV-1 activation in peripheral blood mononuclear cells (PBMC) in vitro. There is one case report of activity of thalidomide in AIDS KS (Soler et al., 1996). The detection of KSHV (Kaposi's sarcoma herpes virus) in the PBMCs of HIV-seropositive patients by polymerase chain reaction (PCR) has been shown to correlate with the presence of KS and to predict for its development. METHODS: A single institution open label phase II study was designed to establish the activity and toxicity of thalidomide in the treatment of AIDS KS. KSHV DNA levels in PBMCs were determined by PCR quantification and correlated with clinical response. Response evaluation was performed using the AIDS Clinical Trials Group (ACTG) criteria. Only male patients were eligible in view of the teratogenicity of thalidomide. The treatment schedule was thalidomide 100mg orally once at night for an initial study period of two months. RESULTS: Seventeen patients median age 40 years (range 30-48) were enrolled and 11 are evaluable for response. The median CD4 cell count was 36 cells/µl(range 4-552) and 8/17 had prior AIDS defining opportunistic infections. Four patients developed a rash and one Raynaud's syndrome. Six patients were unevaluable due to early withdrawal (toxicity in four patients, progressive disease in one and poor compliance in one). Five of the 11 evaluable patients achieved a partial response. Thus the overall response rate is 45% (95% confidence interval 10-81%). A further two patients had stable disease (18%: 95% confidence interval 0-45%). Results of the PCR quantification for KSHV DNA will be presented. CONCLUSIONS: Although the number of patients in this study is small and therefore the confidence intervals wide, thalidomide appears to have activity in the treatment of AIDS related KS and deserves further investigation. Reference: Soler R, Howard M, Brink N, Gibb D, Tedder R & Nadal D. Regression of AIDS-related Kaposi's sarcoma during therapy with thalidomide. Clin. Infect. Dis 1996:23, 501-503. Acknowledgement: MB and KF are supported by a grant from the Crusaid and Star Foundation.

Infection with AIDS-related herpesviruses in human immunodeficiency virus-negative infants and endemic childhood Kaposi's sarcoma in Africa.

Novel herpesviruses have been described recently. These include human herpesviruses 6, 7 and 8 (HHV-6, -7, -8). HHV-6 has at least two strain groups, variants A and B. The B strains are predominant in the West and can account for over 97% of infections in infants. In contrast, the A strains are rare and the few well-characterized isolates have been from adult African AIDS patients. It is not clear whether the HHV-6 variant A strains are AIDS-related and/or whether they can also be acquired as childhood infections and may reactivate later during adulthood. What contribution geographical variation plays has yet to be assessed. HHV-8 has been associated with AIDS-related epidemic Kaposi's sarcoma (KS), but has also been identified in endemic KS. In regions of Africa where KS is endemic, the onset of AIDS has led to increased prevalence of KS. In this report, we examine in Zambia, an AIDS epidemic and KS endemic region, infection with these novel herpesviruses during infancy. In blood samples from human immunodeficiency virus-negative infants with first febrile episode, both semi-quantitative PCR and sequence analyses were used to identify HHV-8 in 8% and HHV-6 in 30%, with 44% of these variant A; in childhood endemic KS biopsies HHV-8 was detected in 100% and HHV-6 in none. The high viral-DNA loads in the infant blood samples were consistent with viraemia. This is the first demonstration that HHV-6 variant A and HHV-8 may be acquired as common childhood infections.

A single 13-kilobase divergent locus in the Kaposi sarcoma-associated herpesvirus (human herpesvirus 8) genome contains nine open reading frames that are homologous to or related to cellular proteins.

Two small fragments of a novel human gammaherpesvirus genome known as Kaposi's sarcoma (KS)-associated herpesvirus or human herpesvirus 8 (HHV-8) have been shown to be present in virtually all AIDS and non-AIDS KS lesions, as well as in body cavity-based lymphomas (BCBL) and in multicentric Castleman's disease. We have extended those studies by identifying and sequencing a third fragment of HHV-8 DNA encoding a viral thymidylate synthetase (TS) gene. Use of this viral TS fragment as a probe led to the identification and mapping of a cluster of overlapping phage lambda clones from a BCBL tumor DNA genomic library that spanned 48 kb on the left-hand side of the HHV-8 genome between the equivalents of open reading frame 6 (ORF6) and ORF31 of herpesvirus saimiri (HVS). DNA sequencing of a 17-kb segment encompassing a gammaherpesvirus divergent locus (DL-B) between ORF11 and ORF17 revealed the presence of nine viral ORFs with predicted gene products related to cellular proteins. These include the complete TS gene and a dihydrofolate reductase (DHFR) gene, four novel cytokine genes (encoding viral interleukin-6, viral MIP-1A, viral MIP-1B, and BCK) that have not previously been found to be encoded by a virus, and a bcl-2 homolog. This region in HHV-8 also contains the T1.1 abundant lytic cycle nuclear RNA gene and encompasses two genes (or exons) encoding proteins with C4HC3 zinc finger domains of the PHD/leukemia-associated protein subtype. The latter are related to the spliced immediate-early IE1 protein of the gamma-2 class herpesvirus bovine herpesvirus type 4 and a similar motif found in HVS ORF12. Although genes for TS and DHFR enzymes are also encoded by HVS (ORF70 and ORF2), both occur at different genomic loci than in HHV-8, and the HHV-8 DHFR protein is much farther diverged from human DHFR than is the HVS version, implying that they were probably acquired as host cell cDNAs by independent evolutionary events. Transcripts from the IE1-A, IE1-B, DHFR, and MIP-1B genes were all detected by Northern blot hybridization analysis in a BCBL cell line at 12 h after induction with butyrate but were not present before induction, indicating that these are all primarily lytic cycle genes. We conclude that the DL-B locus of gammaherpesviruses displays considerably more variability that previously appreciated and that expression of many of these genes is likely to have important implications for HHV-8 biology and therapy.

Strain variability among Kaposi sarcoma-associated herpesvirus (human herpesvirus 8) genomes: evidence that a large cohort of United States AIDS patients may have been infected by a single common isolate.

Previous analysis of the majority of Kaposi's sarcoma (KS) tumors, in both AIDS and non-AIDS populations, has revealed the consistent presence of two small subsegments (open reading frame 25/26 [ORF25/26] and ORF75) of a novel human gamma class herpesvirus genome referred to as KSHV or HHV-8. We have carried out DNA sequence comparisons with DNAs encompassing a total of 2,500 bp each over three separate PCR-amplified fragments from KS lesions and body cavity-based lymphoma (BCBL) samples from 12 distinct patients, including four African and two classical or endemic non-AIDS KS samples. The results revealed differences at 37 of 2,500 nucleotide positions (i.e., 1.5% overall variation). However, the 12 HHV-8 genomes examined fell into three distinct but very narrow subgroupings (A, B, and C strains). All A strain isolates differed from B strain isolates at 16 positions, but of the eight U.S. samples tested, six were A strains, and these differed at no more than two positions among them. Similarly, three of the four African samples were B strains, which differed from each other at only one position. The two C strain genomes also displayed only one nucleotide variation, but they differed from all A strains at 26 positions and from all B strains at 20 positions. One C strain genome was present in all six independent lesions from an AIDS KS patient with disseminated disease, and the other represented a mosaic A/C recombinant genome from the HBL6 cell line derived from a BCBL tumor. Evaluation of previous data suggests that B and C strains may predominate in Africa and that A strains predominate in classical Mediterranean samples. Although both B and C strains are represented in U.S. AIDS patients, the majority (70 to 80%) of samples from the mid-East Coast region at least appear to be virtually identical, supporting the concept that they may all derive from the spread during the AIDS epidemic of a single recently transmitted infectious agent.

Vascular endothelial growth factor/vascular permeability factor is an autocrine growth factor for AIDS-Kaposi sarcoma.

Kaposi sarcoma (KS) is the most common tumor associated with HIV-1 infection and develops in nearly 30% of cases. The principal features of this tumor are abnormal vascularization and the proliferation of endothelial cells and spindle (tumor) cells. KS-derived spindle cells induce vascular lesions and display enhanced vascular permeability when inoculated subcutaneously in the nude mouse. This finding suggests that angiogenesis and capillary permeability play a central role in the development and progression of KS. In this study, we show that AIDS-KS cell lines express higher levels of vascular endothelial growth factor/vascular permeability factor (VEGF/VGF) than either human umbilical vein endothelial cells or human aortic smooth muscle cells. AIDS-KS cells and primary tumor tissues also expressed high levels of Flt-1 and KDR, the receptors for VEGF, while the normal skin of the same patients did not show any expression. We further demonstrate that VEGF antisense oligonucleotides AS-1 and AS-3 specifically block VEGF mRNA and protein production and inhibit KS cell growth in a dose-dependent manner. Furthermore, growth of KS cells in nude mice was specifically inhibited by VEGF antisense oligonucleotides. These results show that VEGF is an autocrine growth factor for AIDS-KS cells. To our knowledge, this is the first report that shows that VEGF acts as a growth stimulator in a human tumor. Inhibitors of VEGF or its cognate receptors may thus be candidates for therapeutic intervention.

Kaposi's sarcoma-associated herpesvirus-like DNA sequences (KSHV/HHV-8) in oral AIDS-Kaposi's sarcoma: A PCR and clinicopathologic study

Recently, a new human herpesvirus (KSHV/HHV-8) has been identified in classic, transplant, endemic, and AIDS Kaposi's sarcoma that may be involved in the pathogenesis of Kaposi's sarcoma. The purpose of this study was to evaluate oral AIDS-Kaposi's sarcoma for detection of KSHV/HHV-8 DNA. DNA extracted from 54 oral AIDS-Kaposi's sarcoma lesions (47 initial, 7 postvinblastine treated), 5 non-Kaposi's sarcoma HIV-positive lesions, and 3 non-Kaposi's sarcoma HIV-negative lesions was evaluated by polymerase chain reaction (KS330 233bp amplicon) for KSHV/HHV-8. The AIDS-Kaposi's sarcoma study population consisted of 52 patients (51:1, men:woman; 92% men having sex with men, 8% heterosexual; mean age, 38 years; mean, CD4 59/mm 3) Opportunistic infections occurred in 88% (candidiasis, 65%; Pneumocystis carinii pneumonia, 31%; nonoral Kaposi's sarcoma, 25%, mycobacterium avium-intracellulare (MAI), 16%; cytomegalovirus, 14%; herpes simplex virus, 14%). Sexually transmitted diseases occurred in 73% (gonorrhea, 37%; syphilis, 23%; condyloma, 22%; HSV, 16%). Most frequent lesion sites were palate (74%) and gingiva (17%). Most common lesion types were purple nodular (48%) and macular (42%). Histopathologic subtypes were nodular (71%), plaque (27%), and patch (2%). Polymerase chain reaction analysis detected KSHV/HHV-8 DNA in 53 of 54 AIDS-Kaposi's sarcoma lesions (47 of 47 initial, 6 of 7 postvinblastine treatment). KSHV/HHV-8 DNA was not detected in non-Kaposi's sarcoma lesions in HIV-positive or HIV-negative persons. KSHV/HHV-8 DNA sequence is present in a high proportion of oral AIDS-Kaposi's sarcoma lesions. Whether KSHV/HHV-8 is an etiologic agent or a cofactor in the development of this vascular neoplasm is uncertain and remains to be proven. Polymerase chain reaction analysis for KSHV/HHV-8 DNA sequence detection may be helpful in identifying Kaposi's sarcoma in early vascular proliferations, when the characteristic histopathologic features are not present.

Clastogenic Factors In Plasma Of HIV-1 Infected Patients Activate HIV-1 Replication In Vitro: Inhibition By Superoxide Dismutase

The frequent neoplastic disorders present in HIV-infected patients and the implication of oxidative stress in AIDS-Kaposi's sarcoma pathogenesis prompted us to study whether the mechanisms implicated in genotoxic effects of clastogenic factors (CFs) (i.e., chromosome damaging materials released by cells under conditions of oxidant stress) can play a role in HIV-1 expression and whether exogenous superoxide dismutase can inhibit the clastogenic and HIV-inducing effects of CFs. CFs were found in the plasma of all HIV-1 infected patients (n = 21) of this study group, in asymptomatic (CDC II) as well as in symptomatic patients (CDC IV). In addition to their chromosome damaging effect, CFs are able to upregulate HIV-1 expression in U1 cells and in PBMCs activated with PHA and IL2 at all time points (p < .05). Their formation, therefore, is an early event in the disease. It occured despite antiviral medication in these patients. Superoxide dismutase inhibited the clastogenic and the viral inducing effects (p < .05). On the basis of our findings, association of SOD mimetics or superoxide scavengers with antiviral drugs may be a new therapeutic approach. This polytherapy, if started early enough after infection, may prolong the latency period and limit the emergence of drug-resistant viral strains.

Overview of the Management of AIDS-Related Kaposi's Sarcoma

To review the epidemiology, pathogenesis, clinical presentation, diagnosis, and staging of Kaposi's sarcoma (KS), as well as the current role of local and systemic therapies in the management of AIDS-related KS (AIDS-KS). MEDLINE and CANCERLIT searches of the English-language medical literature were conducted. Emphasis was placed on studies published since the onset of the AIDS epidemic in the early 1980s. A manual review of selected bibliographies was also completed. AIDS-KS is a disease with a heterogeneous presentation that affects approximately 20% of patients with AIDS. Although the proportion of AIDS patients developing this disease during the course of their illness is declining, the actual number of AIDS-KS cases is increasing. The etiology of AIDS-KS is not clear, but a sexually transmitted cofactor has been implicated. Recent reports demonstrate that a herpes-like virus may be responsible for the development of KS in patients with and without AIDS. Furthermore, the cellular origin of KS has not been identified and questions remain about whether KS represents a true malignancy. The system used in staging patients with AIDS-KS has changed dramatically since initial therapeutic trials were conducted; this may account for observed differences in outcome among trials. The immunologic status of patients is now included as part of the staging system, since it has prognostic significance. Since specific therapy for AIDS-KS is not curative and does not prolong survival, it should be directed at improving patient cosmesis and palliation of disease-related symptoms. Local therapy, such as radiation, cryotherapy, and intralesional chemotherapy, is recommended for the management of limited disease. Systemic interferon alfa or chemotherapy is indicated for disseminated disease. Interferon alfa is useful in patients with predominantly mucocutaneous disease and is most effective in patients with good prognostic factors, such as absence of B symptoms, no history of opportunistic infections, and a CD4 count of more than 200 cells/mm3. Interferon alfa alone or in combination with zidovudine produces responses in approximately 30% of AIDS-KS patients with good prognostic factors. Single-agent or combination chemotherapy is indicated for rapidly progressive or advanced AIDS-KS. Commonly used agents include doxorubicin, daunorubicin, bleomycin, vincristine, and vinblastine. Responses can be expected in at least 50% of patients treated with single-agent or combination chemotherapy. However, many patients are unable to tolerate the toxicity associated with systemic AIDS-KS therapy. Future research will focus on therapies that target the underlying pathogenesis of this disease. The optimal therapy for patients with AIDS-KS has not been determined. Treatment is appropriately directed at palliation of disease-related symptoms as no therapy has been unequivocally proven to impact survival. Local therapies should be used in the management of localized disease, while systemic therapy is appropriate for disseminated disease. Interferon alfa is useful in patients with primarily mucocutaneous disease or asymptomatic visceral involvement. Chemotherapy is indicated in patients who have rapidly progressive or advanced disease. Therapy must be individualized according to the patient's disease course and other patient-specific factors.

KSHV sequences in biopsies and cultured spindle cells of epidemic, iatrogenic and Mediterranean forms of Kaposi's sarcoma

The pathogenesis of Kaposi's sarcoma (KS) is still unclear, and several factors appear to be involved in the onset of the Kaposi's lesion. Epidemiological studies suggest that a common infective agent may contribute to KS. Sequences which appear to represent a new gammaherpesvirus, currently termed KSHV/HHV8, have recently been identified in KS. To further examine the relationship between this virus and KS, we obtained biopsy samples of KS lesions; these samples, the spindle cells cultured from these lesions and the PBMC of the same patients were tested for the presence of KSHV sequences by PCR. In addition, we tested several "late passage" KS spindle cell lines as well as control samples. The biopsy samples were from lesions of the following forms of KS: one sporadic KS, two epidemic KS and three iatrogenic KS, one of which was in the process of regressing after reduction of immunosuppressive therapy, and two that were at different stages (patch and nodular) from a single patient. The sporadic KS specimen was positive, as were the PBMCs from this patient, and cells grown from this biopsy appeared to contain KSHV viral sequences up to the fifth passage. Both epidemic KS biopsies were positive, but in these cases KSHV sequences were not detected in the cultured cells. The biopsy from the regressing iatrogenic KS lesion was negative, as were the cells cultured from this lesion. However, the PBMCs of this patient were weakly positive for KSHV at the time of biopsy, and PBMCs collected from this patient one month later were completely negative. The samples of both the patch and the nodular KS lesions obtained from another immunosuppressed patient showed amplifiable sequences of KSHV, but both the PBMCs of this patient and primary KS cell cultures from these biopsies were negative. Of the late-passage KS lines tested, only one, IST AIDS KS 12, was positive for KSHV. This line is derived from an early angiomatous-macula lesion. Taken together, these data suggest that an active KSHV infection is associated with KS and that elimination of KSHV from the lesion precedes regression of the lesion, strongly correlating KSHV with KS. In addition, early KS lesions may have a higher KSHV burden, or contain cells more susceptible to KSHV infection, further linking KSHV to KS.

Detection of human herpesvirus-like sequence in oral aids-kaposi's sarcoma: a PRC and clinicopathologic study

Detection of human herpesvirus-like sequence in oral aids-kaposi's sarcoma: a PRC and clinicopathologic study

Presence of human herpesvirus-like DNA sequence in oral Kaposi's sarcoma: A preliminary PCR study

DNA sequences closely related to herpesvirus-like sequences have been found in AIDS-associated Kaposi's sarcoma. Subsequent studies indicate that these DNA sequences may be consistently found in AIDS Kaposi's sarcoma and non-AIDS Kaposi's sarcoma from different geographic regions. Oral Kaposi's sarcoma is rare and the specificity of this viral DNA in oral Kaposi's sarcoma and in other oral neoplasms has not been examined. A total of 77 oral neoplasms, including 3 Kaposi's sarcoma specimens from 2 patients with AIDS, were analyzed by polymerase chain reaction for the presence of this herpesvirus-like DNA sequence with the 330-233 primers. All three specimens of oral AIDS-Kaposi's sarcoma from two patients were positive for this DNA sequence. All of the other intraoral lesions including hemangioma, pyogenic granuloma, and various types of epithelial neoplasms, however, had negative reactions. Our results further confirm that oral Kaposi's sarcoma appears to be associated with this herpesvirus-like DNA sequence.

The HIV-1 TAT Protein Induces the Expression and Extracellular Appearance of Acidic Fibroblast Growth Factor

Mounting experimental evidence suggests that the TAT protein, released from human immunodeficiency virus-1 (HIV-1)-infected inflammatory cells, may genetically reprogram targeted cells within a localized environment to develop highly vascularized tumors of mesenchymal origin. The fibroblast growth factor (FGF) family of polypeptides has gained general acceptance as initiators of angiogenesis and functions as potent mitogens for mesoderm-derived cells. To evaluate a potential biological relationship between TAT and acidic FGF (FGF-1), primary murine embryonic fibroblasts either were transfected with the viral transactivator or were transduced (retrovirally mediated) with a secreted, chimeric form of the human polypeptide growth factor, human stomach tumor/Kaposi's sarcoma (hst/KS)FGF-1. Reverse transcriptase-polymerase chain reaction, Western blotting, in situ immunohistochemical, heparin affinity, DNA synthesis, and transient transfection techniques were used to confirm expression, localization, and functionality of the transgenes. Both transfected and transduced cells constitutively expressing either TAT or (hst/KS)FGF-1 adopted a transformed phenotype, maintained aggressive growth behavior, and demonstrated both induction of FGF-specific phosphotyrosyl proteins and nuclear association of FGF-1 and FGF-1 receptor. Increased levels of endogenous, murine FGF-1 mRNA (reverse transcriptase-polymerase chain reaction) and protein (immunoblot analysis) were apparent in both (hst/KS)FGF-1- and TAT-transformed cells. Medium conditioned by (hst/KS)FGF-1-transduced cells contained steady-state levels of biologically active FGF-1 which exhibited a representative molecular weight. Limited sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the conditioned medium from TAT-transformed cells demonstrated the appearance of FGF-1 as latent, high molecular weight complexes requiring reducing agents to activate full biological activity. Collectively, these results suggest that TAT induces the expression and secretion of FGF-1, which may be potentially relevant to the pathophysiological development of AIDS-Kaposi's sarcoma.

Cytokines from activated T cells induce normal endothelial cells to acquire the phenotypic and functional features of AIDS-Kaposi's sarcoma spindle cells.

Kaposi's sarcoma (KS) is a proliferative disease of vascular origin particularly frequent in HIV-1-infected homosexual men (AIDS-KS) and characterized by proliferating spindle-shaped cells, angiogenesis, and inflammatory cell infiltration. Previous work has suggested that KS spindle cells are of endothelial cell origin and that chronic immune activation via the release of inflammatory cytokines may cooperate with basic fibroblast growth factor (bFGF) and the HIV-1 Tat protein in the induction and progression of AIDS-KS. Here we show that KS spindle cells have features of activated endothelial cells, and that conditioned media from activated T cells, rich in the same inflammatory cytokines increased in HIV-1-infected individuals, induce normal endothelial cells to acquire the phenotypic and functional features of KS cells. These include (a) acquisition of a similar pattern of cell surface antigen expression; (b) similar proliferative response to bFGF; (c) induction of the responsiveness to the mitogenic effect of extracellular HIV-1 Tat protein that is now able to promote the G1-S transition of endothelial cell cycle; and (d) induction in nude mice of vascular lesions closely resembling early KS as well as the lesions induced by inoculation of KS cells. These results suggest that chronic immune activation, via release of inflammatory cytokines, may play a role in the induction of KS.

Effects of interleukin-1 and interleukin-1 receptor antagonist in AIDS-Kaposi's sarcoma.

Kaposi's sarcoma (KS) is the most common tumor seen in patients with HIV-1 infection. HIV-1 may induce KS directly through viral protein(s) or indirectly through regulation of cytokines such as IL-1 and IL-6. We have shown that AIDS-KS spindle cells express IL-1 beta and that IL-1ra inhibits KS-spindle cell growth. IL-1ra had little effect on human umbilical vein endothelial cells (HUVEC), human aortic smooth muscle cells (HASM), and human foreskin fibroblast (NN41). These findings support an autocrine activity for IL-1. Furthermore, exogenous IL-1 can enhance AIDS-KS cell growth, and this effect is completely blocked by IL-1ra. As expected, IL-1ra also blocks IL-1 mediated upregulation of IL-6 and bFGF, both of which are autocrine growth factors for KS. IL-1ra is thus a potential candidate for the treatment of AIDS-associated KS.

Block of AIDS-Kaposi's sarcoma (KS) cell growth, angiogenesis, and lesion formation in nude mice by antisense oligonucleotide targeting basic fibroblast growth factor. A novel strategy for the therapy of KS.

Kaposi's sarcoma (KS) is the most frequent tumor of HIV-1-infected individuals (AIDS-KS). Typical features of KS are proliferating spindle-shaped cells, considered to be the tumor cells of KS, and endothelial cells forming blood vessels. Basic fibroblast growth factor (bFGF), a potent angiogenic factor, is highly expressed by KS spindle cells in vivo and after injection in nude mice it induces vascular lesions closely resembling early KS in humans. Similar lesions are induced by inoculating nude mice with cultured spindle cells from AIDS-KS lesions (AIDS-KS cells) which produce and release bFGF. Here we show that phosphorothioate antisense (AS) oligonucleotides directed against bFGF mRNA (ASbFGF) inhibit both the growth of AIDS-KS cells derived from different patients and the angiogenic activity associated with these cells, including the induction of KS-like lesions in nude mice. These effects are due to the block of the production of bFGF which is required by AIDS-KS cells to enter the cell cycle and which, after release, mediates angiogenesis. The effects of ASbFGF are specific, dose dependent, achieved at low (0.1-1 microM), nontoxic, oligomer concentrations, and are reversed by the addition of bFGF to the cells, suggesting that ASbFGF oligomers are promising drug candidates for KS therapy.

Topical bleomycin-dimethylsulfoxide in AIDS Kaposi's sarcoma.

Proliferating cell nuclear antigen (PCNA) is a co-factor for DNA polymerase delta, which replicates genomic DNA during cell growth and division. Using a monoclonal antibody to PCNA (PC10) and conventional immunofluorescent techniques, we have compared the effect of differentiation stimuli on PCNA expression in normal and HPV immortalised keratinocytes. Two positive nuclear staining patterns were observed, a strong speckled form characteristic of proliferating cells and a weaker diffuse form. Strong nuclear staining was present in 44 +/- 4% (mean +/- SEM) of normal keratinocytes proliferating as a monolayer in 70 microM calcium serum-free medium but decreased to 13 +/- 3% after the differentiation stimulus of 2 mM calcium medium for 2 days. An even greater reduction was observed following other differentiation agents, 1,25 dihydroxyvitamin D3, the phorbol ester TPA and the non-specific protein kinase C inhibitor staurosporine. Transforming growth factor-beta, which slows keratinocyte growth without inducing differentiation, reduced strong staining to 17 +/- 3% of cells, but with an increase in the diffuse pattern of staining from 39 +/- 4 to 57 +/- 3%. HPV immortalised cells were resistant to the above agents except staurosporine, which inhibited growth and reduced the strong nuclear staining from 44 +/- 5% to 15 +/- 2%.

The Tat protein of human immunodeficiency virus type 1, a growth factor for AIDS Kaposi sarcoma and cytokine-activated vascular cells, induces adhesion of the same cell types by using integrin receptors recognizing the RGD amino acid sequence.

Spindle-shaped cells of vascular origin are the probable tumor cells of Kaposi sarcoma (KS). These cells, derived from patients with KS and AIDS, proliferate in response to extracellular Tat protein of human immunodeficiency virus type 1. Normal vascular cells, believed to be the progenitors of AIDS-KS cells, acquire spindle morphology and become responsive to the mitogenic effect of Tat after culture with inflammatory cytokines. Such cytokines are increased in human immunodeficiency virus type 1-infected people, suggesting that immune stimulation (rather than immune deficiency) is a component of AIDS-KS pathogenesis. Here we show that (i) Tat promotes adhesion of AIDS-KS and normal vascular cells; (ii) adhesion of normal vascular cells to Tat is induced by exposure of the cells to the same cytokines; (iii) adhesion is associated with the amino acid sequence RGD of Tat through a specific interaction with the integrin receptors alpha 5 beta 1 and alpha v beta 3, although it is augmented by the basic region; and (iv) the expression of both integrins is increased by the same cytokines that promote these cells to acquire spindle morphology and become responsive to the adhesion and growth effects of Tat. The results also suggest that RGD-recognizing integrins mediate the vascular cell-growth-promoting effect of Tat.