Simultaneous integrated boost intensity-modulated radiotherapy for treatment of locally advanced non-small-cell lung cancer: a retrospective clinical study

OBJECTIVE

To evaluate the clinical efficacy and safety of simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) for patients with locally advanced non-small-cell lung cancer (LANSCLC).

METHODS

48 patients with LANSCLC treated with SIB-IMRT from January 2010 to April 2012 were retrospectively analysed. A radiation dose of 45-63 Gy (median dose, 51.58 Gy) was delivered to the planning target volume (1.8-2.0 Gy daily fractions) simultaneously with 55.0-74.2 Gy (median dose, 63 Gy) to the planning gross tumour volume (2.00-2.25 Gy daily fractions). 45 patients received concurrent/sequential chemotherapy. The overall survival (OS), locoregional recurrence-free survival (LRFS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. Treatment-related pneumonitis and oesophagitis were graded according to the Common Terminology Criteria for Adverse Events v. 4.0.

RESULTS

By 1 July 2013, 29 of the 48 patients were dead. The median follow-up time for the survivors was 28 months (19-44 months). The median OS and PFS were 21 and 14 months, respectively. The median LRFS time was not reached. The 2-year LRFS, OS and PFS were 62.5%, 45.1% and 28.0%, respectively. Two patients experienced Grade 3 treatment-related pneumonitis, two patients experienced Grade 5 treatment-related pneumonitis and two patients had ≥Grade 3 oesophagitis.

CONCLUSION

SIB-IMRT appears to be an effective therapeutic option in patients with LANSCLC and warrants further evaluation with increased number of patients in prospective clinical trials.

ADVANCES IN KNOWLEDGE

This study explores the feasibility of delivering tumoricidal doses of radiation to primary lesions in non-small-cell lung cancer.

Analysis of the risk factors for the recurrence of cervical cancer following ovarian transposition

PURPOSE

To investigate the potential risk factors related to the recurrence of cervical cancer following ovarian transposition.

MATERIALS AND METHODS

A total of 105 patients with cervical carcinoma were retrospectively analyzed. Each patient underwent surgical therapy in combination with ovarian transposition from September 2000 to November 2009. The potential risk factors for recurrence following ovarian transposition were analyzed.

RESULTS

The average age of the 105 patients was 38.7 years. Twelve patients were in Stage IA, 65 in IB, 12 in Stage IIA, and 16 in Stage IIB. Twenty-five patients had well-differentiated cancer (G1). Forty-eight patients had moderately-differentiated cancer (G2), and 32 patients had poorly-differentiated cancer (G3). Ninety-seven cases were squamous cell carcinoma, three were adenocarcinoma, four were small cell carcinoma, and one case was adenosquamous carcinoma. Five patients (4.8%) had a recurrence, two of whom (1.9%) had ovarian metastasis. Univariate analysis showed that the pathological type (p = 0.005) and degree of differentiation (p = 0.001) were potential risk factors for recurrence of cervical carcinoma following ovarian transposition. Cancer embolus in vessels or lymphatic metastasis was observed in four of the five patients who suffered a recurrence.

CONCLUSION

Pathological type, differentiated degree, and cancer embolus in vessels or lymphatic metastasis were identified as potential risk factors for the recurrence of cervical carcinoma after ovarian transposition.

InP-based deep-ridge NPN transistor laser

We report an InP-based deep-ridge NPN transistor laser (TL, λ∼1.5 μm). By placing the quantum well (QW) active material above the heavily Zn-doped base layer, both the optical absorption of the heavily p-doped base material and the damage of the quality of the QWs resulted from the Zn diffusion into the QWs are decreased greatly. CW operation of the TL is achieved at -40 °C, which is much better than the shallow-ridge InP-based NPN TL. With future optimization of the growth procedure, significant improvement of the performance of the deep-ridge InP-based NPN TLs is expected.

Changes of pituitary and penile structure in male adult rats following castration and high-fat diet

AIM

To investigate the influence of low androgen levels and high-fat diet on the structure of pituitary and penis in male rats.

METHODS

Ten-week-old adult male Sprague-Dawley rats were randomly divided into 2 groups, one fed a high-fat diet the other fed a normal diet; each group consisted of 3 subgroups: controls, castrated rats (with low androgen), and castrated rats given undecanoate replenishment. After 11 weeks, the structure of pituitary and penis were observed under light microscopy. Immunohistochemistry was used to assess the expression of FSH in pituitary and cyclooxygenase-2 (COX-2) in corpora cavernosa penis.

RESULTS

The structures of pituitary and penis in castrated rats were injured, and were more damaged in castration together with high-fat diet. Immunohistochemistry showed FSH expression in castrated rats pituitary while castrated rats on a high-fat diet had less positive staining than those on a normal diet. Vascular structure of corpora cavernosa penis, showed a strongly positive COX-2 expression in high-fat diet rats.

CONCLUSIONS

Castration and high-fat diet could induce structural damages of pituitary and penis in male rats. Replacement with testosterone could partially restore the impaired structure. The positive expression of COX-2 implied inflammatory pathway existence on vascular structure of penis in high-fat diet and low-androgen male rats.

Selection of a phage-displayed peptide recognized by monoclonal antibody directed blocking the site of hepatitis C virus E2 for human CD81

The human CD81 (hCD81) molecule has been identified as a putative receptor for hepatitis C virus (HCV). HCV envelope glycoprotein 2 (E2) most likely plays a pivotal role in binding to host cells by interacting with the hCD81 molecule. In this study, a phage-displayed peptide library was used to select small peptides with anti-hCD81 monoclonal antibody JS-81. The output/input ratio of phages increased about 91 fold after the third round of selection. Eight of the 30 phage clones selected from the phage library showed specific binding to the anti-hCD81 by enzyme linked immunosorbent assay (ELISA). Competitive inhibition test further demonstrated that HCV E2 could significantly inhibit the binding of a positive phage clone to anti-hCD81 JS-81. Exogenous small peptide ATWVCGPCT contained by the positive phage clones showed aligned with the hCD81 sequence from 153-161 by sequence analyses. These results suggest that the selected ATWVCGPCT is a novel hCD81-like small peptide, which can block the binding site of HCV E2 for hCD81. It may be of further application on development of antiviral agents targeting the stage of HCV entry.

Structure and function of HIV-1 auxiliary regulatory protein Vpr: novel clues to drug design

Vpr is a 96-amino acid auxiliary regulatory protein that is packaged in the HIV-1 virion. It enhances the nuclear transport of the pre-integration complex, and regulates cell cycle, transcription and apoptosis. These biological activities suggest strongly that Vpr interacts with cellular biochemical pathways to regulate HIV-1 replication and pathogenesis. The karyophilic property of Vpr appears to be due to direct interaction of Vpr with nuclear transport factors and residents of the nuclear pore complex, whereas transcriptional effects of Vpr may be exerted through direct and indirect mechanisms. Cell cycle arrest at the G2/M checkpoint by Vpr is correlated with the hyperphosphorylation of Cdc2. The pro-apoptotic activity of Vpr is dependent on the subtype of the HIV-1 isolate, and may be dramatically enhanced by a single L64P mutation. Mitochondria- and caspase-dependent mechanisms appear to mediate Vpr-induced apoptosis. Recent evidence suggests that Vpr interacts with a cellular ubiquitination machinery and promotes degradation of Vpr mutants carrying the L64P mutation. Vpr interaction with the ubiquitination machinery may contribute to the regulation of the HIV-1 life cycle at various stages. NMR studies of Vpr have shown a Vpr monomer with three helical domains arranged in a twisted-U shape. However, Vpr most likely exists as a trimer in vivo. Structural/functional domains have been tentatively mapped for Vpr induction of apoptosis and for Vpr interaction with the ubiquitination machinery. Structural refinement of Vpr, specially by crystallography of the potential Vpr trimer, should help design therapeutic approaches to specifically target Vpr.

Increased CCR4 expression on circulating CD4(+) T cells in ankylosing spondylitis, rheumatoid arthritis and systemic lupus erythematosus

Previous studies have suggested that CCR4 is particularly important in the selective recruitment of various subsets of leucocytes in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In this study, we examined the percentage of CD4(+)/CCR4(+) T cells within circulating lymphocytes in active ankylosing spondylitis (AS), RA and SLE patients. The clinical significance of CCR4 expression as well as possible associations between the expression and serum levels of tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma and interleukin (IL)-10 were also examined. Our results showed that the percentage of CD4(+)/CCR4(+) T cells was significantly elevated in AS and RA patients as compared with normal controls. The percentage was also significantly higher in SLE patients who had received no treatment with glucocorticoids or cytotoxic drugs (untreated SLE) than that in controls. In addition, the percentage of CD4(+)/CCR4(+) T cells showed significant positive correlations with the Bath ankylosing spondylitis disease activity index (BASDAI) in AS and with the SLE disease activity index (SLEDAI) in untreated SLE. Of all the cytokines examined, the elevated serum IL-10 level was closely correlated with the percentage of CD4(+)/CCR4(+) T cells in AS, RA and untreated SLE. These results suggest that CCR4 may be crucial in the pathogenesis of AS, RA and SLE. The percentage of CD4(+)/CCR4(+) T cells can serve as a useful marker for the activity of AS and untreated SLE.

Association of estrogen receptor alpha and vitamin D receptor gene polymorphisms with bone mineral density in Chinese males

Osteoporosis is a common health problem not only in females but also in males, however, studies of osteoporosis in males are relatively rare compared to those in females. This is especially true in genetics studies. We evaluated the effects of PvuII and XbaI polymorphisms in the estrogen receptor alpha (ER-alpha) gene and ApaI polymorphism in the vitamin D receptor (VDR) gene on BMD variation in a random sample of 352 unrelated males from 401 Chinese nuclear families. BMD was measured at the lumbar spine (L1-L4) and hip (femoral neck, trochanter, intertrochanteric region). Raw BMD values were adjusted by age, age(2), height, and weight as covariates. We found no significant results for the 3 individual markers on BMD variation, however, ER-alpha haplotype analyses yielded some interesting results. Carriers of haplotype pX had a 4.98% lower BMD at the trochanter (P = 0.02) and 3.55% lower BMD at the lumbar spine (P = 0.09) than non-carriers. PX subjects had a 3.42% higher BMD at the trochanter and 3.26% higher BMD at the lumbar spine than others (P = 0.07 and P = 0.10, respectively). Such results were highly comparable with the significant or nearly significant interactions between ER-PvuII and ER-XbaI on BMD values at the trochanter (P = 0.03) and spine (P = 0.11). No significant results were observed for the interactions between ER-PvuII and VDR-ApaI, between ER-XbaI and VDR-ApaI, and between any of ER-alpha haplotypes and VDR-ApaI locus. Our results suggest that the ER-alpha haplotypes, not individual markers, may be associated with BMD variation at some skeletal sites in our Chinese male samples.

Identification and expression of human CD81 gene on murine NIH/3T3 cell membrane

The human CD81 (hCD81) molecule has been identified as a putative receptor for hepatitis C virus (HCV). In this study, eukaryotic expression vector pCDM8-hCD81 containing hCD81 cDNA and pSV2neo helper plasmid was used to cotransfect with lipofectamine into murine fibroblast cell line NIH/3T3 to establish an hCD81-expressing cell line. Resistant cell clones were obtained 20 days after the selection with neomycin (600 micro/ml) and then cultured as monoclones. The expression of the transfected hCD81 gene in the cells was verified by RT-PCR and flow cytometry analyses. One of the selected cell clones showed obvious expression of hCD81 and was named NIH/3T3-hCD81. Competitive inhibition tests indicated that the binding of monoclonal anti-hCD81 (JS-81) to NIH/3T3-hCD81 cells was inhibited by recombinant HCV E2 protein, suggesting that the expressed hCD81 molecules on NIH/3T3-hCD81 cells maintain natural conformation of binding to HCV E2. The transfected NIH/3T3-hCD81 cells should be of great potential value in studies on HCV attachment and onset of infection.

Activation of Intracellular MAPK/ERK Initiated by Hepatitis C Virus Envelope Protein E2 in HepG2 Cells

CD81, widely expressed on the surface of various human cells including hepatocytes, is a protein involved in intracellular signal transduction pathways. Recent studies suggested that human CD81 could specifically interact with hepatitis C virus (HCV) envelope protein E2. Therefore, CD81 has been identified as a putative cellular receptor for HCV. The HCV E2-CD81 interaction was considered a molecular mechanism contributing to HCV infection and pathogenicity. MAPK/ERK is characteristically associated with cell proliferation and hypertrophy. To investigate the effect of HCV on MAPK/ERK, human HepG2 cells were used in this study. CD81 expression on HepG2 cell surface was determined by flow cytometry with method of immunofluorescence. The cells were cultured in DMEM medium without fetal calf serum for 7 h, and then treated with HCV E2 protein at different time courses. Activation of MAPK/ERK in the cells was measured by Western blot, immunohistochemical and immunofluorescent analyses. Phosphorylation of MAPK/ERK was related to the concentration of HCV E2 proteins and to the time length of stimulation. MAPK/ERK in HepG2 cells was activated by HCV E2 protein, suggesting that HCV E2-CD81 interaction might be involved in intracellular signal transduction and might play an active role in HCV pathogenicity.

[Enhancement of immune responses of hepatitis B virus core DNA vaccine by a signal Peptide and a universal helper T lymphocyte epitope]

The human interleukin-2 signal peptide and a potent universal helper T lymphocyte epitope PADRE were spliced to the 5' terminus of hepatitis B viru score HBcAg gene. The modified HBcAg gene was used to construct a DNA vaccine. After the resulted DNA vaccine construct was transfected into COS7 cells, secreted HBcAg was detected in the supernatant by ELISA. BALB/c mice were vaccinated intramuscularly with the modified HBcAg DNA vaccine and the wild-type one. Serum antibodies,T lymphocyte proliferative response and cytotoxic T lymphocyte response of the immunized mice were measured. The results showed that the modified DNA construct induced cellular and humoral immune responses much stronger in vivo than the natural one did, indicating the potential value as a therapeutic vaccine for treatment of chronic hepatitis B.

Cytoplasmic retention of HIV-1 regulatory protein Vpr by protein-protein interaction with a novel human cytoplasmic protein VprBP

Vpr is an HIV-1 auxiliary regulatory protein packaged in the virion. It has been shown to enhance the nuclear transport of the HIV-1 pre-integration complex, activate transcription of cellular and viral promoters, and arrest the cell cycle at the G2/M check-point. We previously identified a cellular protein of 180 kDa (RIP) that interacted with HIV-1 Vpr specifically. We now rename this cellular protein as Vpr-binding protein, or VprBP. In this report, we describe the cloning of the VprBP cDNA that encodes 1507 aa residues and is identical to the previously cloned cDNA KIAA0800. We demonstrate that Vpr specifically interacts with recombinantly expressed VprBP in vitro as well as in vivo. Furthermore, Vpr interacts with the cellular endogenous VprBP in the context of the HIV-1 life cycle. Mutational analysis of VprBP suggests that the Vpr binding domain is located within the C-terminal half of VprBP, which has a Pro-rich domain and several Phe-x-x-Phe repeats. Subcellular fractionation studies show that both the endogenous VprBP and the adenovirus-expressed VprBP are distributed predominantly in the cytoplasmic fraction. Consistent with previous reports, the adenovirus-expressed Vpr is distributed in both the cytoplasmic and the nuclear fractions. However, when VprBP and Vpr are expressed together, Vpr is found almost exclusively in the cytoplasm. Expression of VprBP does not affect the nuclear transport of the adenoviral nuclear protein, pTP. VprBP expressed in insect cells also blocks the nuclear transport of a Vpr-GFP fusion protein, and VprBP mutants incapable of interacting with Vpr fail to block Vpr-GFP nuclear transport. We hypothesize that Vpr interaction with VprBP may cause changes in the host cell cytoplasm that affect HIV-1 pathogenesis as well as HIV-1 replication.

Demyelination but no cognitive, motor or behavioral deficits after adenovirus-mediated gene transfer into the brain

Adenovirus-mediated gene transfer of interferon gamma (AdIFN) elicits rejection of intracerebral Lewis lung carcinoma. In this system, gene transfer into brain parenchymal cells is both necessary and sufficient to generate the antitumor response. Despite persistent parenchymal inflammation and demyelination, wild-type mice injected intracerebrally with either AdIFN or beta-galactosidase adenovirus (AdBGAL) perform as well as non-injected animals in behavioral, memory, and motor tests. Both AdIFN and AdBGAL elicit demyelination whose incidence rises sharply when the lowest effective dose of AdIFN is exceeded. Therefore, transfer of interferon gamma into brain parenchyma does not seem to elicit detectable cognitive, behavioral or motor deficits. Furthermore, gene transfer into the brain, by adenoviral vectors currently in clinical trials, is associated with a narrow therapeutic window where the incidence of demyelination rises sharply soon after the effective dose is achieved. Gene Therapy (2000) 7, 2094-2098.

Effects of extracellular human immunodeficiency virus type 1 vpr protein in primary rat cortical cell cultures

Recent evidence suggests that HIV-1 Vpr exists in soluble form in the serum and cerebrospinal fluid (CSF). Further, its abundance in the bloodstream, and the CSF, and its activity on other cell types suggest that it could have an effect on brain activity. Using mixed embryonic rat brain cultures as a model to examine the effects of physiological concentrations of extracellular Vpr protein, Vpr-induced cell death was observed. We also observed similar Vpr-induced effects in enriched primary cortical rat astrocytes, as well as in the C6 glioma cell line. Vpr-induced cell death observed in the astrocytic cells appeared to be caused primarily by a necrotic mechanism, although a few apoptotic nuclei were also present. We did not observe Vpr-induced effects on any primary cortical neurons, although we did observe Vpr-induced cell death in hippocampal neurons and astrocytes. Finally, we observed no cell cycle effects due to extracellular Vpr protein. This data points out that different cell types are affected by the toxic effects of extracellular Vpr protein, and that differential toxic effects of extracellular Vpr protein are observed in similar cell types.

Molecular advances to treat cancer of the brain

Malignant primary and metastatic brain tumours continue to be associated with poor prognosis. Nevertheless, recent advances in molecular medicine, specifically in the strategies of gene therapy, targeting tumour cells, anti-angiogenesis and immunotherapy, have created novel tools that may be of therapeutic value. To date, gene therapy trials have not yet demonstrated clinical efficacy because of inherent defects in vector design. Despite this, advances in adenoviral technology, namely the helper-dependent adenoviral constructs (gutless) and the uncovering of brain parenchymal cells as effective and necessary targets for antitumour benefits of adenoviral-mediated gene transfer, suggest that developments in vector design may be approaching the point of clinical utility. Targeting tumour cells refers to strategies that destroy malignant but spare normal cells. A new assortment of oncolytic viruses have emerged, capable of specific lysis of cancer tissue while sparing normal cells and propagating until they reach the tumour borders. Furthermore, peptides have been transformed into bullets that specifically seek and destroy cancer cells. The concept of tumour angiogenesis has been challenged by new but still very controversial findings that tumour cells themselves may form blood channels. These results may lead to the redirecting of the molecular targets toward anti-angiogenesis in some tumours including glioblastoma multiform. Unfortunately, our knowledge regarding the immunological ignorance of the tumour is still limited. Even so, newly discovered molecules have shed light on novel pathways leading to the escape of the tumour from the immune system. Finally, significant limitations in our current experimental tumour models may soon be overcome by firstly, the development of models of reproducible organ-specific tumours in non-inbred animals and secondly applying genomics to individualize therapy for a particular tumour in a specific patient.

Gene transfer into brain parenchyma elicits antitumor effects

Gene therapy strategies for cancer currently aim at targeting gene delivery to the malignant cell. In a mouse model of intracerebral Lewis lung carcinoma (3LL), adenoviral vectors transduce not only 3LL cells but also brain parenchymal cells including endothelial cells, neurons, microglia, and astrocytes in vivo. Furthermore, transgene expression persists longer in brain than in tumor. Transfer of IFN-gamma into brain parenchymal cells rather than tumor is both necessary and sufficient to generate antitumor therapeutic benefits. Therefore, parenchymal cells represent an effective and necessary target for delivery of genes that render the brain uninhabitable by the tumor.

Gene transfer of IFN-gamma into established brain tumors represses growth by antiangiogenesis

The experiments in this paper were designed to examine the therapeutic effects of adenoviral-mediated gene transfer of IFN-gamma into a mouse model of an established metastatic brain tumor. Temperature-sensitive replication-defective adenovirus was generated for gene transfer of IFN-gamma (AdIFN) and beta-galactosidase (AdBGAL) cDNAs in vivo. In this model, treatment with AdIFN elicits prolonged survival times and brain tumor rejection. Evidence against an immune-mediated response accounting for this result include: 1) absence of a memory immune response upon challenge, 2) lack of antitumor effects at sites distal to inoculation of AdIFN, and 3) preservation of the therapeutic effects of AdIFN in scid and beige mice and in inducible NO synthase (iNOS) knockouts. High concentrations of IFN-gamma do not inhibit tumor growth in vitro making it unlikely that the antitumor effect of this treatment acts directly on the growth of the tumor cells. However, gene transfer of IFN-gamma inhibits neovascularization of the tumor in a 3LL-Matrigel assay in vivo, and AdIFN induces apoptosis of endothelial cells in vivo, supporting the idea that AdIFN represses tumor growth by inhibiting angiogenesis. The substantial non-immune-mediated therapeutic benefits of AdIFN in animals paves the way for devising novel strategies for treating human brain tumors.

Chronology of genetic changes in the vpu, env, and Nef genes of chimeric simian-human immunodeficiency virus (strain HXB2) during acquisition of virulence for pig-tailed macaques

Recently, we developed a highly pathogenic variant of simian-human immunodeficiency virus, SHIV-4 (containing the tat, rev, vpu, and env of the HXB2 strain of HIV-1 in a genetic background of SIVmac239), through a series of four bone marrow-bone marrow passages-first in rhesus monkeys and then in pig-tailed macaques [Joag et al. (1996) J. Virol. 70, 3189-3197]. Inoculation of pig-tailed macaques with this pathogenic virus (SHIVKU-1) causes subtotal elimination of CD4(+) T cells and fatal opportunistic infections, usually within 6 months. Genetic characterization of SHIVKU-1 showed that it has a functional vpu gene (the first codon is ATG vs ACG for the vpu of SHIV-4) and several amino acid substitutions in Env and nef [Stephens et al. (1997) Virology 231, 313-321]. Two pig-tailed macaques, PPc and PQc, were the first to develop a severe loss of CD4(+) T cells and the acquired immune deficiency syndrome and were euthanized at 26 and 105 weeks, respectively. In this report, we analyzed the changes that occurred in the vpu, nef, and env (gp120) genes of the virus used to inoculate macaques PPc and PQc and established the chronology of changes that occurred in these viral genes as these two animals lost their CD4(+) T cells and progressed to develop acquired immune deficiency syndrome. Compared with SHIV-4, the virus used to inoculate macaques PPc and PQc had 0, 3, and 0 consensus amino acid changes in the Vpu, gp120, and Nef, respectively. An analysis of the viral sequences amplified from peripheral blood mononuclear cells samples taken at various times after inoculation of PPc revealed that the vpu had not reverted to an open reading frame (closed vpu, ACG) at 4 weeks after inoculation, but by 16 weeks vpu had reverted to an open reading frame (open vpu, ATG). Macaque PQc, which had a longer course of disease, had a closed vpu at 4 and 16 weeks, but by 28 weeks, both closed and open vpu were detected. From 39 to 105 weeks, only an open vpu was detected. In both macaques, the reversion to an open vpu correlated well with the second phase (major) of CD4(+) T cell loss. An analysis of the nef and env sequences isolated from the same times after inoculation revealed an association between the reversion of vpu to an open reading frame and the accumulation of increased numbers of consensus changes in these two viral proteins. These data suggest that the concomitant reversion of vpu to an open reading frame along with increased substitutions in Nef and gp120 were important genetic changes in the viral genome that were responsible for the increased and highly efficient rate of replication of the virus in CD4(+) T cells and macrophages, which in turn led to elimination of the CD4(+) T cells and profound loss of immunocompetence in the infected animals.

Direct binding to nucleic acids by Vpr of human immunodeficiency virus type 1

Human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) is a 15kDa regulatory protein packaged in the HIV-1 virion. Although the molecular mechanism of Vpr function during viral replication remains elusive, Vpr has been found to possess interesting biological activities, including cell-cycle arrest at the G2/M check point, promotion of the HIV-1 pre-integration complex for nuclear transport, and a low but significant level of transcriptional activation of a variety of viral and cellular promoters. We now present data suggesting that HIV-1 Vpr is a nucleic-acid-binding protein. This activity of Vpr was demonstrated by DNA-cellulose chromatography, antibody co-immunoprecipitation, and gel electrophoretic mobility shift assays. By mutational analysis, the C-terminal region of Vpr, which is rich in basic amino-acid residues, was shown to be critical for Vpr binding to nucleic acids. The nucleic-acid-binding activity of Vpr is consistent with several biological activities of Vpr and may provide an important clue for understanding the molecular interactions between HIV-1 and the host cells.

Direct activation of protein phosphatase-2A0 by HIV-1 encoded protein complex NCp7:vpr

The effects of HIV-1 encoded proteins NCp7, vpr and NCp7:vpr complex on the activity of protein phosphatase-2A0 have been tested. We report that NCp7 is an activator of protein phosphatase-2A0 and that vpr activated protein phosphatase-2A0 only slightly. We also report that NCp7 and vpr form a tight complex which becomes a more potent activator of protein phosphatase-2A0 than NCp7 alone. The ability of NCp7 to activate protein phosphatase-2A0 is regulated by vpr. The C-terminal portion of vpr prevents NCp7 from activating protein phosphatase-2A0 while the N-terminal portion of vpr potentiates the effect of NCp7 on the activity of protein phosphatase-2A0. Our findings indicate that vpr may be acting as a targeting subunit which directs NCp7 to activate protein phosphatase-2A0. In view of the fact that protein phosphatase-2A functions as an inhibitor of G0 to M transition of the cell cycle and is involved in other key cellular processes such as the control of RNA transcription, the results presented in this report may explain how HIV-1 causes cell cycle arrest which may lead to CD4+ T cell depletion and also how it disturbs normal cellular processes of its host cell.

Characterization of a leucine-zipper-like domain in Vpr protein of human immunodeficiency virus type 1

Human immunodeficiency virus type 1 (HIV-1) replicates productively in vitro in CD4(+)-T cells and/or macrophages. In the host, however, HIV-1 replication may be restricted by the quiescence of susceptible cells. Vpr is a 15-kDa late viral gene product, which is assembled in the virion and suspected to enhance HIV-1 replication in the infected host. We demonstrated previously that Vpr interacted specifically with the cellular transcription factor Sp1, and activated transcription from the HIV-1 long-terminal-repeat. Both Vpr-Sp1 interaction and trans-activation by Vpr required a central Leu/Ile-rich domain (LR domain, aa 60-81) in Vpr. This domain of Vpr was also found critical for Vpr interaction with another cellular protein of 180 kDa. We now provide biochemical evidence that the Vpr LR-domain has a leucine-zipper-like structure. The leucine-zipper structure has been found in a variety of cellular transcription factors, which use the leucine-zipper domain to form a specific dimer before they can bind to DNA through an upstream basic domain. The LR domain of HIV-1 Vpr, when fused to the basic domain of the cellular transcription factor CREB, was capable of supporting specific DNA binding by the CREB basic domain. Point mutational analysis of the Leu/Ile residues in the LR domain suggested that multiple Leu/Ile residues may be involved in maintaining the leucine-zipper-like structure. Mutagenesis in the context of the full-length Vpr also helped identify Leu/Ile residues may be involved in maintaining the leucine-zipper-like structure. Mutagenesis in the context of the full-length Vpr also helped identify Leu/Ile residues critical for Vpr interaction with the cellular 180-kDa protein. These results suggested that the leucine-zipper-like domain may be an important functional determinant for HIV-1 Vpr.

Chimeric simian/human immunodeficiency virus that causes progressive loss of CD4+ T cells and AIDS in pig-tailed macaques

By animal-to-animal passage of simian/human immunodeficiency virus (SHIV) in pig-tailed macaques, we have developed a macaque model of human immunodeficiency virus type 1 (HIV-1) disease in humans. Passaging was begun with a chimeric virus containing the env gene of HIV-1 HXBc2 and the gag and pol genes of simian immunodeficiency virus SIVmac239. SHIV was passaged serially in cohorts of two macaques each, using bone marrow-to-bone marrow transfers at 5, 5, and 16 weeks for passages 2, 3, and 4, respectively. The fifth passage was done by using cell-free virus isolated from cerebrospinal fluid of a passage 4 macaque. The virus became more virulent with each passage. Virus replication was restricted in all three animals in passages 1 and 2 but not in five of the six animals in passages 3, 4, and 5. In these animals, intense virus replication in the lymphoid tissues resulted in almost total elimination of CD4+ T cells within weeks of inoculation, and three of these animals developed AIDS in less than 1 year. The more uniform virus-host interaction initiated by the cell-free virus in the passage 5 animals contrasted with a more variable pattern of disease initiated by infectious bone marrow cells during earlier passages. The virulent cell-free SHIV can now be used to screen the efficacy of vaccines directed against the envelope of HIV-1.

Interaction of virion protein Vpr of human immunodeficiency virus type 1 with cellular transcription factor Sp1 and trans-activation of viral long terminal repeat

Acquired immunodeficiency syndrome (AIDS) is a result of replication of the human immunodeficiency virus type 1 (HIV-1) predominantly in CD4+ T lymphocytes and macrophages. However, most of these cells in vivo are immunologically quiescent, a condition restricting HIV-1 replication. Vpr is an HIV-1 virion protein suspected to enhance HIV-1 replication in vivo. We demonstrate in this report that Vpr specifically activates HIV-1 long terminal repeat (LTR)-directed transcription. This effect is most pronounced on a minimal promoter from HIV-1 LTR containing the TATA box and binding motifs for the ubiquitous cellular transcription factor Sp1. Evidence is presented that Vpr interacts with Sp1 when Sp1 is bound to the Sp1 motifs within the HIV-1 LTR Both Vpr-Sp1 interaction and Vpr trans-activation require a central Leu/Ile-rich domain in Vpr. Our findings suggest that Vpr trans-activation through Sp1 is most critical for the immediate early transcription of HIV-1 when other positive regulators, such as NF-kappa B, are limited or inactive, a condition presumably present in vivo. By interacting with Sp1, Vpr also has the potential to influence cellular gene expression and cellular functions. Thus, therapeutic approaches directed toward blocking the Vpr trans-activation function could prove valuable in treating AIDS.