OP0045 NLRP12 INVOLVES IN THE LUPUS WITH POSITIVE INTERFERON SIGNATURE

Background:

Systemic lupus erythematous (SLE) is a systemic autoimmune disease with diverse etiological factors. It was recognized that interferon (IFN) signature involved in the progress of SLE. NLRP12 (NOD-like receptor family (NLR) pyrin domain containing 12) is a pyrin containing NLR protein that we had linked its new biological function to the cross-regulation of Toll like receptor (TLRs) and Rig-I like receptor (RIG-I) pathways. NLPR12 acts as an innate immune check-point in regulating type I IFNs expression during TLRs and RIG-I activation. The importance of NLRP12 in lupus disease activity remained to be elucidated.

Objectives:

To clarify the role of NLRP12 in regulating the interferon signature.

Methods:

Peripheral blood mononuclear cells (PBMCs) were collected from SLE patients and healthy donors for analysis of NLRP12 and IFN-α gene expression by RT-QPCR. PBMCs were applied for Chromatin immuneprecipitation (ChIP) assay and electrical mobility shift assay (EMSA) to determine the putative transcription factor that regulates NLRP12 expression. An involvement of epigenetic regulation of NLRP12 expression in SLE patients was also analyzed. Bone marrow derived dendritic cells (BMDCs) were collected from wild type mouse and Nlrp12 knocked-out mice. Another CD14+ monocytes were isolated from 10 cases of lupus patients and 8 cases of healthy control, following by stimulating different type of nucleic acids, and IFN-α and IL-6 were measured with ELISA assay. CD14+ monocytes in lupus patients were also pre-treated with IFNAR2 antibody for further nucleic acid stimulation. Two mice models were applied for evaluation the role of Nlrp12: intraperitoneal injection of TMPD (2,6,10,14-tetramethylpentadecane, or pristane) in C57BL/6 mice and Faslpr mice. Both models were conducted with and without Nlrp12 knockout.

Results:

NLRP12 expression was significantly lower in PBMC isolated from SLE patients compared to healthy donors. The inverse correlation was observed in NLRP12 and IFNA gene expression as well as NLRP12 expression and amount of double-stranded DNA autoantibody in SLE patients. NLRP12 expression showed negative correlations with IFN-α treatment, as well as herpes simplex virus-1 (HSV-1) infection. Results from ChIP and EMSA analysis indicated a potential transcription factor 1 (TF-1) regulating NLRP12 promoter activity. TF-1 lead to transcriptional suppression of NLRP12 in SLE PBMC, and it was gradually induced after IFN treatment. Recruitment of TF-1 to NLRP12 promoter in SLE PBMC compared to the healthy PBMC was detected, and increased when treating with IFN. Human CD14+ monocytes collected from lupus and healthy control stimulating with different type of nucleic acids revealing significant increasing level of IFN-α and IL-6 in lupus patients. Among animal models, both pristine induced mice and Faslpr mice revealed increasing autoantibodies production and severity of glomerulonephritis in Nlrp12-/- group in comparison with Nlrp12+/+ ones, indicating the role of NLRP12 in maintaining positive interferon signature as well as disease activity.

Conclusion:

Expression level of NLRP1.2 has been demonstrated to be a biomarker of disease activity in SLE patients. The NLRP12 was involved in the interferon signature, which was also negatively regulated by TF-1. Both clinical samples and animal models revealed NLRP12 in maintaining the positive interferon signature, indicating the possible role of exacerbating factor for lupus disease activity.

Disclosure of Interests:

None declared

AB1063 CASE SERIES OF PATIENTS WITH CHRONIC NON-TUBERCULOSIS MYCOBACTERIA ACCOMPANYING WITH ANTI-INTERFERON GAMMA ANTIBODY

Background:

Anti-interferon (IFN) gamma antibody was a rare autoantibody which mainly been reported in Asia. It interferes the interferon pathway and eradication of intracellular pathogens, such as Salmonella or Mycobacteria. This rare disease should be raised for more awareness.

Objectives:

To analyze clinical presentations of the patients with anti-interferon (IFN) gamma antibody.

Methods:

We checked anti-IFN gamma antibody when patient fulfilled multiple NTM infection (especially bone marrow and lymph nodes). There are 6 cases of non-tuberculosis mycobacteria (NTM) infection accompanying with anti-IFN gamma antibody in our hospital from 2015 to 2019 of hospitalist ward, and the antibody titer is recorded.

Results:

Among these cases, patients had initial presentations of fever (100%), elevated CRP and ESR (100%), lymphadenopathy (67%), body weight loss (50%), and elevated LDH (50%). All the 6 cases had negative results of TB-PCR test, but 1 had positive result of interferon gamma release assay (IGRA, 17%). NTM was identified from lymph node biopsy (50%), sputum (33%), skin (33%), and bone marrow (33%). Different NTM was identified, including Mycobacterium abscessus, Mycobacterium fortuitum group complex, Mycobacterium kanasii, and Mycobacterium avium complex. Prolonged antibiotics treatment was used, but all patients had recurrent or persisted NTM infection under medications. 4 cases had different NTM strain after 1 year of treatment from the initial involved organ. One case had an episode of Salmonella bacteremia with septic shock. Another case had positive result of ANA, and other cases had negative auto-antibodies.

Conclusion:

Careful history taking and physical examinations are crucial in diagnosis this acquired immunodeficiency disease. This rare but unique disease should be taken into consideration.

Disclosure of Interests:

None declared

Incidence and risk factors of osteomyelitis in adult and pediatric systemic lupus erythematosus: a nationwide, population-based cohort study

OBJECTIVE

The objective of this paper is to investigate the incidence rate, risk factors and outcome of osteomyelitis among patients with systemic lupus erythematosus (SLE).

MATERIALS AND METHODS

We conducted a cohort study using data for patients enrolled in the Taiwan National Health Insurance Database from 2000 to 2012. Patients with SLE and age- and sex-matched controls without SLE were enrolled. Primary endpoint was the first occurrence of osteomyelitis. Risks of osteomyelitis in SLE patients were analyzed with Cox proportional hazards regression models, including age, sex, comorbidities and medications.

RESULTS

Among 24,705 SLE patients (88.4% women, mean age 35.8 years) with a median follow-up of 9.1 years, 386 patients had osteomyelitis. The incidence rate ratio (IRR) of osteomyelitis in the SLE group vs the control group was 8.52 (95% confidence interval (CI) 7.24-10.05). The SLE group had higher incidence rates of osteomyelitis than the control group, especially in pediatric subgroups (IRR 41.1 95% CI 18.57-107.35). Compared to controls, SLE patients experienced osteomyelitis at a younger age (42.3 vs 58.1 years) but did not have an increased risk of mortality (hazard ratio 0.7; 95% CI 0.21-2.38). Age >60 years, male gender, malignancy within five years, prior bone fracture and higher daily prednisolone dose (>7.5 mg) cumulatively for >180 days increased risk for osteomyelitis.

CONCLUSIONS

SLE patients have a higher IRR of osteomyelitis than controls. Pediatric and elder SLE patients, patients with a history of bone fracture, malignancy within five years and higher-dose glucocorticoid use have a higher risk of osteomyelitis and should be carefully monitored.

The solution structure of [d(CGC)r(amamam)d(TTTGCG)]2

The solution structure and hydration of a DNA.RNA hybrid chimeric duplex [d(CGC)r(amamam)d(TTTGCG)]2 in which the RNA adenines were substituted by 2'-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2'-OMe-RNA.DNA junction adopted an O4'-endo sugar conformation, while the other DNA residues including 3C in the DNA.2'-OMe-RNA junction, adopted C1'-exo or C2'-endo conformations. The observed NOE intensity of 2'-O-methyl group to H1' proton of 4am at the DNA.2'-OMe-RNA junction is much weaker than those of 5am and 6am. The 2'-O-methyl group of 4am was found to orient towards the minor groove in the trans domain while the 2'-O-methyl groups of 5am and 6am were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1' protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]2, there were no long-lived water molecules found in [d(CGC)r(amamam)d(TTTGCG)]2. This is probably due to the hydrophobic enviroment created by the 2'-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2'-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5 degrees C to 51.9 degrees C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNA.RNA hybrid and chimeric duplexes with 2'-modified RNA residues.

Endothelial cell loss induced by phacoemulsification occurs through apoptosis

BACKGROUND

Cornea endothelial cells are nondividing cells containing pumping function which is crucial for cornea clarity and integrity. Endothelial cell loss occurs after cataract surgical procedures such as phacoemulsification. The authors hypothesize that endothelium damage occurs through apoptosis.

METHODS

Ultrasound was achieved by placing a phacoemulsification probe in the anterior chamber and delivering 0% or 50% of maximum power for 2.5 min. The corneal tissue was harvested immediately, and at 1 and 7 days after the operation. Corneal tissue was stained by hemotoxylin and eosin (H&E) and evaluated by light microscopy. Endothelium apoptosis was monitored using the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay to detect DNA fragmentation.

RESULTS

In corneas which underwent phacoemulsification with 0% energy, no cell loss or apoptosis was identified immediately, 1 or 7 days after the operation. Likewise, in corneas exposed to 50% energy, no cell loss or apoptosis was detected immediately after phacoemulsification. However, minimal amount of cell loss but prominent apoptosis was detected with the TUNEL assay 1 day after the operation, whereas significant cell loss but no apoptosis was detected 7 days after the operation by H&E stain.

CONCLUSIONS

These results demonstrate that corneal endothelial cell loss induced by ultrasound damage occurs through apoptosis.

Suppression of choroidal neovascularization by adeno-associated virus vector expressing angiostatin

PURPOSE

To test the efficacy of a recombinant adeno-associated virus (rAAV) vector that expresses mouse angiostatin in suppressing experimental choroidal neovascularization (CNV) in a rat model.

METHODS

An rAAV vector, rAAV-angiostatin, was constructed to deliver the mouse angiostatin gene. rAAV-angiostatin and a control virus, rAAV-lacZ, were delivered in vivo by subretinal injection in Brown Norway rats, and the delivery was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR). For a CNV suppression experiment, CNV was generated by fundus krypton laser photocoagulation 7 days after the viral vector injection and was evaluated by fluorescein angiography (FA) and histology. Apoptosis in retina was analyzed using the TUNEL assay. Inflammation in the retina was investigated by immunohistochemistry, using antibodies that recognize lymphocytes.

RESULTS

rAAV-angiostatin injection led to sustained expression of the angiostatin gene in chorioretinal tissue for up to150 days. FA analysis revealed significant reduction of the average sizes of CNV lesions in rAAV-angiostatin-injected eyes when compared with rAAV-lacZ-injected eyes at both 14 (P = 0.019) and 150 (P = 0.010) days after injection. Moreover, histologic analysis of CNV lesions also revealed significantly smaller lesions in rAAV-angiostatin-injected eyes (P = 0.004). As for adverse effects, rAAV-angiostatin injection did not cause inflammation or apoptosis of cells in retina and choroid.

CONCLUSIONS

This is the first report that subretinal injection of rAAV-angiostatin can significantly reduce the sizes of CNV lesions. This and the absence of apoptosis and inflammation in chorioretinal tissue indicate the feasibility of a gene therapy approach for treatment of CNV disease.

Sequence variants and functional analysis of human papillomavirus type 16 E5 gene in clinical specimens

Previously, we found that the E5 protein can be expressed in HPV-16 infected precancerous lesions and cervical cancer. In this study, we investigated the presence of sequence variants of E5 in HPV-16 infected tissues. Toward this end, we amplified the E5 gene by polymerase chain reaction from 29 HPV-16 infected tissues including eight normal tissues, seven high grade neoplastic tissues (high grade squamous intraepithelial lesions (HSIL) and 14 cervical cancer tissues. Sequence analysis demonstrated that there were three mutational hot spots at positions 3979, 4042, and 4077 of the HPV-16 DNA; these and other mutations resulted in six variants in the E5 sequence. This resulted in four E5 protein mutants, named WTE5 [wild type E5 protein], 14E5, 21E5 and 56E5. Functional analysis of these four mutant proteins revealed that the transforming activities of 14E5, 21E5 and 56E5 were 0.95, 0.59, and 0.89 fold of WTE5, respectively. Although E5 was expressed in all of the HSIL and cervical cancer tissues, but in only one of the eight normal tissues tested, only WT E5 protein was found in HSIL while in cervical cancer tissues both WT and mutant E5 proteins were detected. Since these E5 proteins exhibited the same in vitro transforming activity, these data suggest that expression of E5 is important in development and progression toward malignancy but mutation of E5 does not affect the transformation process.

The expression of HPV-16 E5 protein in squamous neoplastic changes in the uterine cervix

To investigate the expression of human papillomavirus type 16 (HPV-16) E5 protein in squamous neoplastic changes in the uterine cervix, the specific E5 antibody was generated and used to identify the expression of E5 protein in 40 cases of HPV-16-positive tissues and 5 previously identified HPV-negative normal cervical tissues. The results revealed that E5 protein was primarily expressed in the lower third of the epithelium in low-grade squamous intraepithelial lesions (SILs) and throughout the whole epithelium in high-grade SILs. In invasive squamous carcinoma, 60% of HPV-16-infected cancers which contained the episomal viral genome had the E5 gene, and could express E5 protein which was located throughout the whole epithelium. Previously, we documented the expression of type I growth factor receptors [ERBB1/EGFR (epidermal growth factor receptor), ERBB2, ERBB3 and ERBB4] in the full range of cervical neoplasias by immunohistochemistry assay. Hence, in this study, we extensively analyzed the correlation between the expression of E5 protein and the expression of type I growth factor receptors. Among 40 HPV-16- infected cervical neoplasias, we found that the expression of E5 protein was significantly correlated with either the expression of the ERBB1 or the ERBB4 receptor.

Recombinant adeno-associated virus vector expressing glial cell line-derived neurotrophic factor reduces ischemia-induced damage

To explore the potential of using the recombinant adeno-associated viral (rAAV) vector, expressing glial cell line-derived neurotrophic factor (GDNF) as the gene therapy for stroke, we injected rAAV vectors expressing GDNF (rAAV-GDNF) into the cortex of rats which had been experiencing transient bilateral common carotid artery ligation and right middle cerebral artery ligation for 90 min. GDNF levels in cortical tissues of rAAV-GDNF-injected animals were significantly higher than in the control animals injected with rAAV-expressing lacZ (rAAV-lacZ), indicating that rAAV can deliver and express the GDNF gene in cortical tissues. Triphenyltetrazolium chloride tissue stain analysis revealed that the rAAV-delivered GDNF gene could rescue the brain tissues from ischemia-induced injury. Cortical tissues which received rAAV-GDNF injections had both significantly smaller total volumes of infarction and smaller areas of infarction on each brain slice than those which were injected with rAAV-lacZ. An in situ labeling analysis demonstrated significantly less apoptotic cells in cortical tissues rescued by rAAV-GDNF, indicating prevention of apoptosis as the mechanism of cortical cell protection. Moreover, immunohistochemistry staining of Neu-N indicated that the rescued brain tissues contained the same number of Neu-N-positive neuronal cells as contralateral undamaged brain tissues. This provides strong evidence that cortical neuronal cells can be rescued by GDNF gene therapy. Indeed, these findings show that the rAAV is a potential delivery vector of GDNF gene for the therapy of stroke.

Induction of CD8 T cells by vaccination with recombinant adenovirus expressing human papillomavirus type 16 E5 gene reduces tumor growth

The potential of the E5 protein as a tumor vaccine candidate has not been explored yet. In this study, we evaluate the human papillomavirus type 16 (HPV-16) E5 protein delivered by an adenovirus vector as a tumor vaccine for cervical lesions. The results demonstrate that a single intramuscular injection of a recombinant adenovirus carrying the HPV-16 E5 gene into syngeneic animals can reduce the growth of tumors which contain E5 gene expression. Moreover, the E5 vaccine-induced tumor protection occurs through CD8 T cells but not through CD4 T cells in in vitro assays. In addition, our studies using knockout mice with distinct T-cell deficiencies confirm that cytotoxic T-lymphocyte-induced tumor protection is CD8 dependent but CD4 independent. Hence, HPV-16 E5 can be regarded as a tumor rejection antigen.

Bcl-2 accelerates retinoic acid-induced growth arrest and recovery in human gastric cancer cells

The role of Bcl-2 as an anti-apoptotic protein has been well documented. In the present work, we present evidence that Bcl-2 may also be involved in cell growth regulation. SC-M1 is an unique cell line which responds to retinoic acid (RA) treatment with reversible growth arrest [Shyu, Jiang, Huang, Chang, Wu, Roffler and Yeh (1995) Eur. J. Cancer 31, 237-243]. In this study, when treated with RA, SC-M1/Bcl2 cells, which were generated by transfecting SC-M1 cells with bcl-2 DNA, were growth-arrested two days earlier than SC-M1/neo cells, which were generated by transfecting SC-M1 cells with vector DNA. This indicates that Bcl-2 accelerates RA-induced growth arrest. In addition to the accelerated growth arrest, RA-treated SC-M1/Bcl2 cells also recovered from growth arrest two days faster than SC-M1/neo cells after the removal of RA. Previously, we had identified the cyclin-dependent kinase inhibitor p21((WAF1/CIP1)) (p21) as a mediator of RA-induced growth arrest [Tsao, Li, Kuo, Liu and Chen (1996) Biochem. J. 317, 707-711]. In a search for the mechanism by which Bcl-2 affects growth regulation, we found that p21 gene expression was more prominent in SC-M1/Bcl2 cells than in SC-M1/neo cells in the presence of RA, but when RA was removed, p21 gene expression levels in SC-M1/Bcl2 cells were also reduced earlier than in SC-M1/neo cells. The present report is the first to show that Bcl-2 accelerates not only growth arrest but also recovery from growth arrest. Moreover, the close correlation between the effect of Bcl-2 on both RA-induced growth arrest and RA-induced p21 gene expression suggests the possibility that Bcl-2 affects cell growth through the mechanism of p21.

Transcriptional repression of p21((Waf1/Cip1/Sdi1)) gene by c-jun through Sp1 site

Previously, we found that c-jun represses the tumor suppressor p21((Waf1/Cip1/Sdi1)) (p21) gene expression. In this study, we further investigated the mechanism of the inhibitory effect of c-jun on p21. After analysis of a series of deletion and point mutants of p21 promoter, we found that Sp1-3 site (-77 and -83) relative to the transcription start site played an important role for c-jun-repressing-responsive element in the p21 promoter. Both Sp1 and Sp3 transcription factors were the key factors for this event. However, the data from electrophoretic mobility shift assay indicated that c-jun did not change the Sp1 DNA-binding affinity, suggesting that additional factors may be involved in the repression of p21 by c-jun. Furthermore, c-jun could inhibit butyrate-inducing p21 gene expression through Sp1, indicating at least one common pathway whereby p21 expression is affected by c-jun and butyrate in opposing actions. Moreover, the hyperphosphorylated retinoblastoma protein (Rb) increased in c-jun expressing cells, indicating that phosphorylated Rb may play a role in regulating Sp1 to repress p21 expression. This is the first demonstration of how housekeeping factors and oncogene product counteract the function of tumor suppressor genes to control cell cycle progression.

Recombinant adeno-associated virus expressing human papillomavirus type 16 E7 peptide DNA fused with heat shock protein DNA as a potential vaccine for cervical cancer

In this study, we explore a potential vaccine for human papillomavirus (HPV)-induced tumors, using heat shock protein as an adjuvant, a peptide vaccine for safety, and adeno-associated virus (AAV) as a gene delivery vector. The tumor vaccine was devised by constructing a chimeric gene which contained HPV type 16 E7 cytotoxic T-lymphocyte (CTL) epitope DNA (M. C. Feltkamp, H. L. Smits, M. P. Vierboom, R. P. Minnaar, B. M. de Jongh, J. W. Drijfhout, J. ter Schegget, C. J. Melief, and W. M. Kast, Eur. J. Immunol. 23:2242-2249, 1993) fused with the heat shock protein gene as a tumor vaccine delivered via AAV. Our results demonstrate that this vaccine can eliminate tumor cells in syngeneic animals and induce CD4- and CD8-dependent CTL activity in vitro. Moreover, studies with knockout mice with distinct T-cell deficiencies confirm that CTL-induced tumor protection is CD4 and CD8 dependent. Taken together, the evidence indicates that this chimeric gene delivered by AAV has potential as a cervical cancer vaccine.

Full functional rescue of a complete muscle (TA) in dystrophic hamsters by adeno-associated virus vector-directed gene therapy

Limb girdle muscular dystrophy (LGMD) 2F is caused by mutations in the delta-sarcoglycan (SG) gene. Previously, we have shown successful application of a recombinant adeno-associated virus (AAV) vector for genetic and biochemical rescue in the Bio14.6 hamster, a homologous animal model for LGMD 2F (J. Li et al., Gene Ther. 6:74-82, 1999). In this report, we show efficient and long-term delta-SG expression accompanied by nearly complete recovery of physiological function deficits after a single-dose AAV vector injection into the tibialis anterior muscle of the dystrophic hamsters. AAV vector treatment led to more than 97% recovery in muscle strength for both the specific twitch force and the specific tetanic force, when compared to the age-matched control. Vector treatment also prevented pathological muscle hypertrophy and resulted in normal muscle weight and size. Finally, vector-treated muscle showed substantial improvement of the histopathology. This is the first report of successful functional rescue of an entire muscle after AAV-mediated gene delivery. This report also demonstrates the feasibility of in vivo gene therapy for LGMD patients by using AAV vectors.

Therapy and prevention of arthritis by recombinant adeno-associated virus vector with delivery of interleukin-1 receptor antagonist

OBJECTIVE

To evaluate the recombinant adeno-associated virus vector encoding interleukin-1 receptor antagonist (rAAV-IL-1Ra) complementary DNA for its potential in the treatment and prevention of lipopolysaccharide (LPS)-induced arthritis.

METHODS

The therapeutic effect of rAAV-IL-1Ra on arthritis was studied by injecting knees of Sprague-Dawley rats with LPS and rAAV-IL-1Ra and then evaluating the severity of arthritis by leukocyte counts in synovial fluid, histologic changes of synovium, and uptake of 67Ga citrate in joint tissue. To study the therapeutic effect on recurrent arthritis, we induced recurrent arthritis by a second injection of LPS 80 days after primary LPS and rAAV-IL-1Ra injections and then evaluated the severity of recurrent arthritis. To study the prevention of arthritis, rAAV-IL-1Ra was injected into normal joints. After 100 days, LPS was used to induce arthritis, and the severity of arthritis was evaluated.

RESULTS

The production of the rAAV-IL-1Ra transgene was up-regulated by LPS-induced joint inflammation and proved to be efficacious in the therapeutic and preventative protocols. Not only primary but also recurrent arthritis could be suppressed by a single injection of rAAV-IL-1Ra. We found that the transgene expression of IL-1Ra could be reactivated by a second challenge with LPS delayed for 80 days after rAAV administration. The therapeutic level of IL-1Ra protein reached a mean +/- SD of 5.8+/-0.5 ng/ml in synovial fluid. In addition, the rAAV transgene persisted within normal joints for at least 100 days and could still be induced to express, after LPS insult, a high level of IL-1Ra (mean +/- SD 5.2+/-0.8 ng/ml) that prevented the occurrence of arthritis.

CONCLUSION

This gene therapy, by combining highly efficient and stable rAAV gene delivery, disease-regulated gene expression, and the antiinflammatory effect of IL-1Ra, provides a valuable approach for long-term protection against, and prevention of, arthritis.

Adenovirus-mediated p21((WAF1/SDII/CIP1)) gene transfer induces apoptosis of human cervical cancer cell lines

p21((WAF1/SDII/CIP1)) (p21) arrests cell growth by inhibiting cyclin-depend kinases. To explore the potential of using p21 for the gene therapy of cervical cancer, we infected human papillomavirus (HPV)-positive cervical cancer cells (HeLa, SiHa, and Z172) and HPV-negative cervical cancer cells (C33A) with recombinant adenovirus encoding p21 cDNA. The results revealed that effective inhibition of cell growth could be achieved by sense p21 adenovirus but not antisense p21 adenovirus infection and occurred through apoptosis as measured by DNA fragmentation and chromatin condensation. Apoptosis was also observed in xenografts of human cervical cancer cells infected with sense p21 adenovirus, as confirmed by in situ terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL). The apoptosis was not prevented by overexpression of the bcl-2 transgene. To sum up, the apoptotic effect suggests that p21 should be a tumoricidal agent instead of a tumoristatic agent in preventing cervical cancers. In addition, our report substantiates the combination of the high efficiency of adenovirus vector-mediated gene delivery and the apoptotic effect of p21.

The expression of type I growth factor receptors in the squamous neoplastic changes of uterine cervix

AIM

The type I family of growth factor receptors includes ErbB1, ErbB2, ErbB3, and ErbB4 which are frequently overexpressed in various human cancer cells. In this study, we systematically investigated the frequency and distribution of these four receptors in relation to neoplastic changes and tumor behaviors in the uterine cervix.

MATERIALS

A total 84 of cases including 12 cases of normal cervical tissues, 6 cases of low grade squamous intraepithelial lesion, 10 cases of high grade squamous intraepithelial lesion, and 56 cases of squamous cells carcinoma were examined.

RESULTS

Our results show significant difference with increasing grades of dysplasia in terms of these four receptor expressions. No association was found between these four receptors and cell keratinization/differentiation of squamous cell carcinoma of the cervix. Of the four receptors studied, only the expression of erbB2/neu gene was significantly associated with lymph nodal metastasis. Moreover, we find that the coexpression of ErbB1 and ErbB4 was significant in cervical carcinoma.

CONCLUSIONS

The coexpression of ErbB1 and ErbB4 in cervical carcinoma suggests that they may be involved in receptor heterodimerization leading to the activation of signaling pathway in the cervical carcinoma.

Disease-inducible transgene expression from a recombinant adeno-associated virus vector in a rat arthritis model

Rheumatoid arthritis (RA) is a systemic autoimmune disease affecting 1% of the world's population, with significant morbidity and mortality. In this study, we investigated a recombinant adeno-associated virus (rAAV) vector for its potential application in RA gene therapy. rAAV encoding Escherichia coli beta-galactosidase was injected into rat joints which had already been induced into acute arthritis after local lipopolysaccharide (LPS) administration, and the efficiency of in vivo transduction was evaluated. We observed a striking correlation between vector transgene expression and disease severity in arthritic joints. The inflammatory reaction peaked at 3 to 7 days after LPS treatment, and, at the same time, 95% of the synoviocytes had high-level transgene expression. Gene expression diminished to the basal level (5%) when the inflammation subsided at 30 days after LPS treatment. More importantly, the diminished transgene expression could be efficiently reactivated by a repeated insult. The transgene expression in normal joints transduced with rAAV remained low for a long period of time (30 days) but could still be induced to high levels (95%) at 3 to 7 days after LPS treatment. This is the first demonstration of disease state-regulated transgene expression. These findings strongly support the feasibility of therapeutic as well as preventative gene transfer approaches for RA with rAAV vectors containing therapeutic genes, which are expected to respond primarily to the disease state of the target tissue.

Simian virus 40 T antigen induces p53-independent apoptosis but does not suppress erbB2/neu gene expression in immortalized human epithelial cells

Previously, we have shown that simian virus 40 (SV40) T antigen can directly cause apoptosis in immortalized human epithelial cells under normal growth conditions. In this study, we further characterized the mechanism of T-antigen-mediated apoptosis involving p53 and whether T antigen can suppress erbB2/neu gene expression. Our results show the differential regulation of erbB2/neu gene expression in different cell clones in response to T antigen transgene, indicating that the regression of erbB2/neu gene by SV40 T is cell-type dependent. Our previous study reported T-antigen-induced apoptosis in p53 mutant cells; however, in this study we find increased levels of p53 protein in T-antigen-containing cells. Therefore, we examined the transactivation function of p53 in these cells. Our data show the failure to transactivate p53, suggesting that increased p53 protein in T antigen expressing cells is functionless at least for transcriptional activation.

rAAV vector-mediated sarcogylcan gene transfer in a hamster model for limb girdle muscular dystrophy

The limb girdle muscular dystrophies (LGMD) are a genetically and phenotypically heterogeneous group of degenerative neuromuscular diseases. A subset of the genetically recessive forms of LGMD are caused by mutations in the four muscle sarcoglycan genes (alpha, beta, gamma and delta). The coding sequences of all known sarcoglycan genes are smaller than 2 kb, and thus can be readily packaged in recombinant adeno-associated virus (rAAV) vectors. Previously, we have demonstrated highly efficient and sustained transduction in mature muscle tissue of immunocompetent animals with rAAV vectors. In this report, we utilize recombinant AAV containing the delta-sarcoglycan gene for genetic complementation of muscle diseases using a delta-sarcoglycan-deficient hamster model (Bio 14.6). We show efficient delivery and widespread expression of delta-sarcoglycan after a single intramuscular injection. Importantly, rAAV vector containing the human delta-sarcoglycan cDNA restored secondary biochemical deficiencies, with correct localization of other sarcoglycan proteins to the muscle fiber membrane. Interestingly, restoration of alpha-, as well as beta-sarcoglycan was homogeneous and properly localized throughout transduced muscle, and appeared unaffected by dramatic overexpression of delta-sarcoglycan in the cytoplasm of some myofibers. These results support the feasibility of rAAV vector's application to treat LGMD by means of direct in vivo gene transfer.

Apoptosis is induced in aging SV40 T antigen-transformed human fibroblasts through p53- and p21CIP1/WAF1-independent pathways

When comparing SV40 T antigen-transformed human fibroblasts of a younger generation (24 population doubling) and aging stage (58 population doubling), we found that detachment of cells from the culture surface occurred more frequently in aging cells. DNA fragmentation and chromatin condensation which are typical findings of apoptosis occurred more frequently in aging cells as compared to cells of a younger generation. There is no increase in the p53 level or decrease in the SV40 T antigen level in aging cells as compared to cells of a younger generation. Retinoic acid treatment which can effectively suppress p21 gene expression did not prevent apoptosis. These findings indicate that apoptosis that occurs due to aging-transformed human fibroblasts is mediated through p53- and p21-independent pathways.

The induction of apoptosis by SV40 T antigen correlates with c-jun overexpression

Simian virus (SV40) T antigen shares many characteristics with adenovirus E1A which is known to induce apoptosis. To verify the potential of SV40 T antigen-mediated apoptosis, we stably expressed T antigen in immortalized human epithelial cells (Z172 and HaCaT). We found that SV40 T antigen could directly cause apoptosis in 22-27% of these cells under normal growth condition as measured by chromatin condensation and nucleosomal fragmentation. The apoptosis of HaCaT cells which contain mutant p53 suggests the p53-independent nature of T antigen-mediated apoptosis. T antigen-induced apoptosis was associated with increased expression of c-Jun protein. Moreover, the overexpression of c-jun alone in these cells also induced apoptosis, indicating that c-jun might play an important role in T antigen-induced apoptosis.

Human papillomavirus, cytomegalovirus and herpes simplex virus infections for cervical cancer in Taiwan

Previously, we had reviewed 43 cases of invasive cancers, adenosquamous cell carcinoma and adenocarcinoma for HPV type infections. With the same cases we extended the investigation to cytomegalovirus (CMV) and herpes simplex virus (HSV) infections. Results show that the prevalence of CMV and HSV infections from these cases of cervical carcinoma was 67 and 76%, respectively, by polymerase chain reaction. The results of the analysis of the association of HPV, CMV and HSV with various clinical characteristics of cervical cancer patients indicated that the correlation between HSV infections and clinical stages of squamous carcinoma was marginally significant (P = 0.068). HSV infections seemed to have a higher association with cell keratinization pattern as compared with the other two viral infections.

E5 proteins of human papillomavirus types 11 and 16 transactivate the c-fos promoter through the NF1 binding element

Human papillomavirus type 11 (HPV-11) and HPV-16 contain an E5 gene that can induce c-fos gene expression in mouse fibroblasts. This study investigated the human c-fos promoter characteristics by mapping the c-fos promoter sequence with several deletion and point mutants that confer responsiveness to E5 of HPV-11 or HPV-16. The mutant studies show that NF1 binding sequences within the c-fos promoter were crucial for the induction of the c-fos gene by E5, and the gel shift assay study suggested that E5 of both HPV-11 and HPV-16 is associated, perhaps indirectly, with this NF1 element in the transactivation of the human c-fos promoter. Using an inducible system, we demonstrate that increased induction of the HPV-11 E5 gene in cells led to increased transactivation of the NF1 element. In addition, the transactivating activity of a series of HPV-11 E5 mutants on the NF1 element had a strong correlation with their respective transforming activities.

Human papillomavirus type 11 and 16 E5 represses p21(WafI/SdiI/CipI) gene expression in fibroblasts and keratinocytes

Here we report that the E5 proteins of human papillomavirus type 11 (HPV-11) and HPV-16 suppressed the expression of the p21(WafI/SdiI/CipI) tumor suppressor gene in NIH 3T3 cells and immortalized human keratinocytes. The promoter activity of p21 was repressed by E5 of HPV-11 and -16, suggesting that p21 gene suppression by E5 was at the transcriptional level. Using an inducible system, we demonstrated that increased induction of HPV-11 E5 in NIH 3T3 cells and keratinocytes led to increased repression of p21 promoter activity. The repression of p21 promoter activity by a series of E5 mutants was somewhat correlated with their respective transforming activities. Previously, we and other investigators showed that the E5 proteins of HPV-11 and -16 can activate the expression of c-jun. The repression of p21 gene expression might be a mechanism of oncogene-mediated growth promotion, since the expression of c-jun also led to a reduction of the levels of p21 RNA and protein in keratinocytes. This is the first demonstration that E5 proteins of HPV-11 and -16 repress p21 gene expression, and this might be one of the mechanisms by which E5 stimulates cell proliferation. In addition, this is also the first report of c-jun repression of p21.

Reversal of the temperature-shift-induced growth restriction of a temperature-sensitive simian virus 40 T-antigen-transformed human fibroblast cell line by treatment with retinoic acid

We previously established a human fibroblast cell line, HFL 6-2, that contains a temperature sensitive simian virus 40 (SV40) T antigen, permitting cell growth at 35 degrees C but restricting growth at 39 degrees C. p21 (Waf1/Cip1) was significantly induced by temperature shifts in HFL 6-2 cells. Here we show that all-trans-retinoic acid (RA) treatment prevented the growth restriction of HFL 6-2 cells at 39 degrees C. In the presence of RA, HFL 6-2 cells proliferated into sizeable colonies even at 39 degrees C. [3H]Thymidine incorporation and flow cytometry analysis revealed that cells exposed to RA maintained DNA synthesis at 39 degrees C. Prevention of growth restriction by RA was correlated with a lack of induction of p21 at the transcription level. These observations suggest that RA may prevent the senescence process by repressing p21 gene expression, and perturb the growth regulation of somatic cells.

Mutational analysis of human papillomavirus type 11 E5a oncoprotein

In this study, we investigated the structural basis of human papillomavirus type 11 (HPV-11) E5a transforming activity at the amino acid level. The effects of insertion, deletion , and substitution mutations on teh E5a transforming activity were determined by the assay of anchorage-independent growth. In the conserved Cys-X-Cys structure, substitution of Ser for Cys-73 resulted in indistinguishable transforming activity, whereas substitution of Ser for Cys-75 or Ser for both Cys-73 and Cys-75 retained 50 and 42% transformation, respectively. This suggests that Cys at position 75 may be important for transformation. Charge and structural changes at teh COOH termini of several mutants impaired transformation significantly, but those at the middle region did so only mildly. In addition, the 16,000-molecular-weight pore-forming protein (16K protein) is known to associate with BPV-1, HPV-6, and HPV-16 E5 proteins. In this study, we investigated the correlation between E5a-16K binding affinity and the transforming activity of E5a by the use of 11 E5a mutants. Results show that E5a and these 11 E5a mutants could bind to the 16K protein when these proteins were coexpressed in COS cells, suggesting that simple binding of the 16K protein by E5a may not be sufficient for cell transformation.

Coincidental expression of E5a and c-jun in human papillomavirus type 6/11-infected condylomata

Previously, we have shown that E5a can induce expression of the c-jun gene in human papillomavirus (HPV)-11 E5a transformed NIH 3T3 cells and human epidermal keratinocytes. In this study, we investigated the relationship between expression of the E5a gene and c-jun in pathologically confirmed condylomata specimens using mRNA hybridization in situ. The c-jun RNA concentration was significantly higher in condylomata specimens with E5a mRNA expression than in specimens without E5a mRNA expression, or in normal cervical specimens. The cells with c-jun expression were located predominantly in the basal and parabasal cell layers. These layers were also the primary location of E5a-expressing cells. This is the first demonstration of a strong correlation (74%) between expression of the E5a and c-jun genes in condylomata specimens. This correlation might reflect regulation by HPV-11 E5a of c-jun gene expression in condyloma.

The regulation mechanism of c-jun and junB by human papillomavirus type 16 E5 oncoprotein

In this study, we show that HPV-16 E5 induced anchorage-independent growth in immortalized human epidermal keratinocytes and that HPV-16 E5 in human keratinocytes had higher expression of c-jun and junB; also, we investigated the role of transcriptional initiation pathways in the expression elevation. In addition, Ras-dependent pathway, as well as PKC-dependent pathway, leads to HPV-16 E5-induced c-jun gene expression.

Overexpression of the proto-oncogene c-jun in association with low-risk type specific human papillomavirus infection in condyloma acuminata

Infection with different types of human papillomavirus (HPV) is associated with neoplasia at different anatomic sites. The "low-risk" HPVs (LR-HPV) are responsible for benign genital lesions such as condyloma acuminata. In order to clarify the tumorigenic mechanism of LR-HPV, the HPV infection status was investigated and the expression of the c-jun proto-oncogene in different HPV-related skin and genital lesions analyzed. Of the 17 condyloma specimens analyzed by Western blotting, 13 cases (76.5%) exhibited overexpression of the c-jun gene. All 13 cases harbored high copy numbers of the LR-HPV genome with an average of 926 copies per cell, whereas the other four cases had an average of 12 copies of LR-HPV per cell (P < 0.001). Further typing of HPV by Southern blotting revealed that HPV-6 and HPV-11 infections predominated in c-jun positive cases. The c-jun protein was detected much less frequently in cervical cancers (three of 29, or 10.3%) and skin warts (one of 10), and was not detected in five genital polyps or in five normal cervical tissues. These findings suggest a type 6/11-specific induction of c-jun gene expression in HPV-related neoplastic lesions.

Human papillomavirus 11 E5a delays the growth restriction induced by temperature shift in temperature-sensitive simian virus 40 T antigen-immortalized keratinocytes

The transfection with human papillomavirus type 11 E5a oncoprotein can cause longer and more active proliferation in the human keratinocytes previously transfected stably with temperature sensitive SV40 T antigen at 39 degrees C. Also, after the E5a transfection in parental temperature sensitive SV40 T antigen gene transfected cells, we observe a delay in the accumulation of p21 gene at 39 degrees C. Moreover, T antigen degradation did not occur at 39 degrees C in the E5a transfected cells as it did in the parental cells. We draw from these observations that E5a may transiently stabilize temperature sensitive T antigen and/or repress p21 synthesis.

Differential regulation of cyclin A, cyclin B and p21 concentrations in a growth-restricted human fibroblast cell line

When the culture temperature was shifted from 35 degrees C to 39 degrees C, human fibroblasts immortalized by the temperature-sensitive simian virus 40 T antigen became larger and acquired the morphological characteristics of senescent fibroblasts. After culture at 39 degrees C for 48 h, most cells had ceased to proliferate. A rapid depletion of cells with S-phase DNA content was observed after the temperature shift. To elucidate the mechanism governing this rapid arrest of proliferation, we studied the expression of genes involved in the regulation of cell cycle progression. Cyclin A, cyclin B and p34cdc2 concentrations were not changed during growth restriction, whereas p21 was rapidly induced in these growth-restricted cells. Transient expression of exogenous p21 in cells cultured at 35 degrees C led to growth restriction and morphological changes characteristic of senescence. Furthermore, we studied the reversibility of growth restriction induced by the temperature increase. The results showed that senescent morphology and growth arrest were not reversible. In these cells the p21 concentration remained high and p34cdc2 remained undetectable. This indicates that p21 accumulation might be responsible for the maintenance of senescence. Our findings provide information on the use of growth restriction of immortalized fibroblasts induced by a temperature shift as a model system to study senescence.

Differential induction and regulation of c-jun, junB, junD and c-fos by human papillomavirus type 11 E5a oncoprotein

The E5a gene of human papillomavirus type 11 (HPV-11) is a transforming oncogene. In this study, we investigated the mechanism of E5a induced transformation. Our results show that the expression of c-jun and junB, but not junD, was activated by HPV-11 E5a in NIH 3T3 cells and human epidermal keratinocytes. However, the expression of c-fos was activated by E5a in NIH 3T3 cells, but not in keratinocytes. We further investigated the mechanism of c-jun and junB induction by E5a. The amount of c-jun and junB RNAs correlated with the amount of E5a RNA in the heavy metal inducible system. E5a constitutively activated the expression of c-jun and junB at the initiation of transcription level. In addition, analyses of the effect of serum on c-jun expression in E5a transformed human epidermal keratinocytes show that EGF might have a stimulatory effect on c-jun gene expression in E5a expressing keratinocytes.

Protein kinase C-and ras-dependent activation of c-jun gene by human papillomavirus type 11 E5a oncoprotein

E5a of HPV-11 is a transforming oncogene. Previously, we have shown that E5a constitutively activates the expression of protooncogene c-jun by transcriptional regulation through the AP-1 binding site in the c-jun promoter. In the present study, we used two different types of cells: the E5a transfected NIH 3T3 cells and human epidermal keratinocytes, and selectively inhibited different signal transduction pathways to investigate effects of E5a on c-jun expression. We find that protein kinase C and ras-dependent pathways are important for the c-jun induction by E5a, but not the cAMP-dependent pathway.

Retinoic acid represses the gene expression of topoisomerase II in HEP3B cells

All-trans-retinoic acid (RA) affects cell growth and regulates gene expression. We examined the expression of topoisomerase 11 gene in Hep3B cells treated with RA. At low RA concentration which did not significantly affect the growth rate of Hep3B cells, RA inhibited the synthesis of topoisomerase II mRNA as revealed by Northern analysis and nuclear run-on analysis. These results indicated that the repression of topoisomerase II gene expression could be directly induced by RA rather than was a secondary event which occurred after cell growth was inhibited by RA. An unexpected finding is that after up to 72 h continuous exposure to RA, the topoisomerase II protein concentration remained unchanged.

Antisense oligodeoxynucleotides to c-jun inhibits proliferation of transformed NIH 3T3 cells induced by E5a of HPV-11

E5a of HPV-11 is a transforming oncogene. Previously, we had shown that the E5a gene is required only for the initiation of transformation; c-jun might be involved in the maintenance of transformation. In this study, we exposed E5a transformed NIH 3T3 cells to antisense oligodeoxynucleotides complementary to the 24 nucleotides corresponding to the translation initiation site of the c-jun gene, and examined the effects of this treatment on cell proliferation. Results show that antisense c-jun oligodeoxynucleotides could repress c-jun production and inhibit cell proliferation in E5a transformed cells.

E5a gene of human papillomavirus type 11 is required for initiation but not for maintenance of transformation in NIH 3T3 cells

We have previously shown that the E5a gene of human papilloma virus type 11 (HPV-11/HPV-6c) is a transforming oncogene. In order to dissect the biological consequences of E5a gene expression we utilized the lac operator/repressor system to manipulate E5a gene expression. Cells were cotransfected with the lac repressor gene and the E5a gene that had been inserted downstream of a simian virus 40 (SV40) promoter containing the lac operator sequence. The expression of E5a gene could therefore be repressed by binding of lac repressor to the lac operator sequence in proximity to this SV40 regulatory region. The transfected cells were cultured in the presence of the inducer IPTG and under G418 selection. IPTG derepressed E5a gene expression by binding to the repressor and reducing its affinity for the lac operator sequence. In these studies, we found that E5a-transformed cells still maintained the transformed phenotype as judged by growth density, cell morphology and anchorage-independent growth when E5a gene expression was repressed. We also found that c-jun expression was induced 3 h after E5a expression was induced by IPTG and c-jun expression was not shut down after repression of E5a expression. This is the first demonstration that the E5a gene of HPV-11 initiates transformation of NIH 3T3 cells but is dispensable for maintenance of the transformed phenotype.

Effects of E5a and E7 genes of human papillomavirus type 11 on immortalized human epidermal keratinocytes and NIH 3T3 cells

The E5a gene of HPV-11 expressed in NIH 3T3 cells led to tumorigenesis in nude mice; whereas when expressed in keratinocytes, E5a induced anchorage independent growth, but was nontumorigenic in nude mice. The E7 gene of HPV-11 expressed NIH 3T3 cells led to tumors in nude mice and morphological transformation, but not anchorage independent growth. Keratinocytes expressing the E7 gene induced colony formation in soft agarose, but not tumorigenesis in nude mice. Comparison of transforming activities of HPV-11 E5a and E7 genes of HPV-11 showed that the efficiency of cell transformation by E7 was weaker than that of E5a.

Genital human papillomavirus infections in Taiwan

OBJECTIVES

Identification and typing of HPV infections in genital condyloma and normal cytological cervix.

METHODS

Cervical cells from 289 Pap cases with normal cytological findings were examined for HPV infection by slot blot hybridization. Fifteen condyloma biopsy specimens were studied by Southern blot hybridization.

RESULTS

Thirty-six cases (12.5%) with normal cervical cytology were HPV positive. The predominant HPV type in women with normal cytology is HPV-16. Risk factors for HPV infection in women with normal cytology depend on age and history of pregnancies. Twelve cases (80%) of condyloma contained HPV-6 or -11 sequences. The predominant HPV type in genital condyloma is HPV-11.

CONCLUSIONS

HPV detection in population-based screening programs for cervical neoplasia can be an important tool in identifying women who are at risk of developing dysplasia and cervical cancer.

Interaction between replication forks and topoisomerase I-DNA cleavable complexes: studies in a cell-free SV40 DNA replication system

The extreme S-phase-specific cytotoxicity of camptothecin has been shown to involve active DNA replication. To investigate the role of DNA replication in camptothecin cytotoxicity, we have studied the interaction between the DNA replication machinery and the topoisomerase I-camptothecin-DNA ternary cleavable complex in a cell-free SV40 DNA replication system. The formation of topoisomerase I-camptothecin-DNA-cleavable complexes on the replication template efficiently and irreversibly inhibited DNA replication. Two aberrant forms of replication products were produced whose abundance varied with the concentrations of exogenously added topoisomerase I and camptothecin. At low concentrations of topoisomerase I and camptothecin, the major aberrant DNA replication product was close-to-unit-length-linear DNA, while at higher concentrations the predominant product was close-to-dimer-size-linear DNA. Analysis of these aberrant replication products has suggested a "collision" model in which the interaction between an advancing replication fork and a topoisomerase I-camptothecin-DNA-cleavable complex results in irreversible arrest of the replication fork and the formation of a double-strand DNA break at the fork. Concomitant with fork arrest and fork breakage, the reversible cleavable complex was converted into a topoisomerase I-linked DNA break. We propose that one or several of these events triggers S-phase-specific cell killing and G2-phase cell cycle arrest.

Characterization and analysis of human papillomaviruses of skin warts

We analysed human papillomavirus (HPV) infections in 61 tissue specimens of skin warts of Taiwanese patients by DNA hybridization. The prevalence of HPV infection was 69% by Southern blot hybridization. The typing of HPVs was performed by dot blot hybridization under highly stringent conditions with each probe separately. The prevalence of HPV-1, 2/3, 4, 5, 8, 11, 16 and 18 in skin warts was 13, 7, 16, 2, 0, 5, 2 and 8%, respectively. Chi-squared analysis revealed that there was a correlation between HPV type and copy number. Most HPV-4-induced warts were verruca vulgaris. HPV-1 DNA was detected in verruca plantaris and verruca vulgaris. No specific histopathological features were found to be indicative of the presence or absence of HPV, or of the various types of HPV infection.

Identification and typing of human papillomavirus in cervical cancers in Taiwan

BACKGROUND

Although human papillomaviruses (HPV) are associated with cervical cancer, it has yet to be determined if specific HPV types have clinical or prognostic significance.

METHODS

Identification and typing of HPV were done by polymerase chain reaction (PCR) and restriction fragment length polymorphism.

RESULTS

Of the 43 cases of cervical cancer, 31 (72%) were HPV positive. The results of HPV typing in 40 cases of squamous cell carcinoma of the cervix revealed the presence of HPV-16 in 20 cases (50%), HPV-18 in 2 cases, HPV-11 in 1 case, HPV-33 in 1 case, HPV-52 in 1 case, HPV-58 in 1 case, and unidentified HPV types in 5 cases. Neither HPV-31 nor HPV-42 were present in our study. One case of squamous cell carcinoma had HPV-11 integration. Chi-square analysis revealed significant correlation between HPV genotypes and squamous cell patterns, no significant correlation between HPV genotypes and clinical stages, and cell differentiation of squamous cell carcinoma of cervix.

CONCLUSIONS

These findings may contribute to understanding the role of HPV in cancer and the value of typing as a prognostic indicator.

Construction of site-specific mutants of E5A protein of HPV-11 using the polymerase chain reaction and a single mutant primer

The method of Perrin and Gilliland (1990) was modified to create site-specific mutants. The polymerase chain reaction and a single mutant primer are needed to carry out site-specific mutagenesis. Using this method, removal of the excess primers and nucleotides from the initial amplification is not necessary. This method provides a simpler way to generate site-specific mutants.

The involvement of active DNA synthesis in camptothecin-induced G2 arrest: altered regulation of p34cdc2/cyclin B

Cell cycle arrest in G2 phase is a common response to a variety of DNA-damaging agents. The coupling between DNA damage and G2 arrest was studied in synchronized HeLa cells using camptothecin, a highly specific inhibitor of topoisomerase I that damages DNA through the formation of reversible topoisomerase I-DNA cleavable complexes. Brief camptothecin treatment of early S-phase HeLa cells caused arrest at G2 phase and abolished the activation of p34cdc2 protein kinase. Both tyrosine dephosphorylation of p34cdc2 and cyclin B accumulation were altered. These cell cycle-dependent changes were not observed when DNA replication was inhibited by aphidicolin during the brief camptothecin treatment. Our results suggest that to produce G2 arrest, active DNA synthesis is required at the time of camptothecin treatment, as was previously shown for camptothecin-induced cytotoxicity. Furthermore, our results suggest that the interaction of the replication fork with DNA damage may ultimately trigger altered regulation of p34cdc2/cyclin B, leading to cell cycle arrest at the G2 phase.

Transcription-driven supercoiling of DNA: direct biochemical evidence from in vitro studies

The translocation of an RNA polymerase elongation complex along double helical DNA has been proposed to generate positive supercoiling waves ahead of and negative supercoiling waves behind the transcription ensemble. This twin supercoiled domain model has been tested in vitro. In the presence of prokaryotic DNA topoisomerase I, which selectively removes negative supercoils, transcription from a single promoter results in rapid and extensive positive supercoiling of the DNA template. The accumulation of positive supercoils in the DNA template requires continued movement of the elongation complex as well as sizable nascent RNA chains. These in vitro results provide direct biochemical evidence supporting the twin supercoiled domain model of transcription. Furthermore, the magnitute of DNA supercoiling (torsional) waves generated by transcription is much greater than previously expected, suggesting that transcription is one of the principal factors affecting intracellular DNA supercoiling.