Inhibition of thymidylate synthase activity by antisense oligodeoxynucleotide and possible role in thymineless treatment

Thymidylate synthase (TS) is an important target for chemotherapeutic treatment of cancer. However, efficacy of TS-targeted anticancer drugs is limited by the development of drug resistance as a result of TS gene amplification. In this work, a phosphorothioated antisense oligonucleotide (ODN), designated ATS-2, was used to suppress cellular synthesis of TS. ATS-2 at 0.2 microM concentration was mixed with lipofectin in a charge ratio of 1:1 and was used to treat the human embryonic kidney (HEK) cell line. A reduction of TS mRNA and protein was achieved. Furthermore, a dose-dependent reduction of cumulative viable cells of up to 98% was observed. Flow cytometer analysis of cell cycle progression indicates that ATS-2-treated cells were arrested and went into apoptosis at the S phase, possibly because of thymidine shortage, suggesting that ATS-2 is specifically effective for dividing cells. When used in combination with the anticancer drug FdUrd, ATS-2 exerted a additive inhibitory effect on cellular proliferation. To elucidate the possible role of cellular thymidine kinase (TdR kinase) in ATS-2 treatment, a second cell line, HeLa, was used. Both HEK and HeLa have similar rates of cell division and ODN uptake. In contrast to HEK, which was shown to have very low levels of TdR kinase activity in [(3)H]thymidine incorporation experiments, [(3)H]thymidine incorporation in HeLa was 15-fold greater than that of HEK. We found that HeLa cells were sensitive to FdUrd but were rather resistant to ATS-2. On the contrary, HEK cells were sensitive to ATS-2 but insensitive to FdUrd. Effects of ATS-2 and FdUrd are, therefore, complementary in thymineless treatment too.

In silico mining of EST databases for novel pre-implantation embryo-specific zinc finger protein genes

Progress in the understanding of early mammalian embryo development has been severely hampered by scarcity of study materials. To circumvent such a constraint, we have developed a strategy that involves a combination of in silico mining of new genes from expressed sequence tags (EST) databases and rapid determination of expression profiles of the dbEST-derived genes using a PCR-based assay and a panel of cDNA libraries derived from different developmental stages and somatic tissues. We demonstrate that in a random sample of 49 independent dbEST-derived zinc finger protein genes mined from a mouse embryonic 2-cell cDNA library, more than three-quarters of these genes are novel. Examination of characteristics of the human orthologues derived from these mouse genes reveals that many of them are associated with human malignancies. Expression studies have further led to the identification of three novel genes that are exclusively expressed in mouse embryos before or up to the 8-cell stage. Two of the genes, designated 2czf45 and 2czf48 (2czf for 2-cell zinc finger), are zinc finger protein genes coding for a RBCC protein with a RFP domain and a protein with three C2H2 fingers, respectively. The third gene, designated 2cpoz56, codes for a protein with a POZ domain that is often associated with zinc finger proteins. These three genes are candidate genes for regulatory or other functions in early embryogenesis. The strategy described in this report should generally be applicable to rapid and large-scale mining of other classes of rare genes involved in other biological and pathological processes. Mol. Reprod. Dev. 59:249-255, 2001.

Identification of genes expressed in the epithelium of porcine oviduct containing early embryos at various stages of development

As a first step toward elucidation of the action of factors secreted by the epithelium of oviduct, differential display reverse transcription-polymerase chain reaction (DDRT-PCR) was used in this study to identify transcripts of such oviductal factors in gilts carrying various stages of early embryo development post hormone-induced ovulation. A total of 13 differentially expressed transcripts were identified between 50 and 120 hr post-hCG injection (between 1- and 8-cell embryonic stages). Twelve of these transcripts were found to be initially expressed at 96 hr post-hCG injection (at 4-cell embryonic stage) and beyond. Three of such genes were shown by sequence analysis to be the porcine transforming growth factor-alpha, the porcine transforming growth factor-beta-binding protein II and a porcine astral natriuretic factor receptor-like transcript. Only one differentially expressed gene was detected between 50-60 and 85 hr post-hCG injection, and this gene turned out to be the porcine follicle-stimulating hormone receptor. The remaining eight transcripts detected by DDRT-PCR were novel. Moreover, most of these newly expressed genes were found to be turned on at a time coincidental with that of the 4-cell block of porcine embryos cultured in vitro. Our results demonstrate that DDRT-PCR is a feasible approach for rapid identification of genes that are differentially expressed in oviductal epithelium. Some of the genes thus identified may be important for unhindered development of embryos in the oviduct.

Analysis of relative binding affinity of E7-pRB of human papillomavirus 16 clinical variants using the yeast two-hybrid system

A number of genotypes of the human papillomaviruses (HPV) are associated with malignancies of the uterine cervix. Sequencing work has revealed the existence of intratype HPV variants with minor differences in the nucleotide sequence. More recent data suggest the possibility that some of the variants may have different modes of clinical manifestation. In this study, sequences of the E6 and E7 oncogenes of 17 HPV16 isolates derived from PAP smear samples of Taiwanese patients were analyzed. A number of E6 and E7 novel variants were found. Particularly, a prevalent (64.7%) E6 polymorphic site A442C with an E113D amino acid substitution seems specific to Taiwanese patients. In E7, two novel but silent polymorphic sites G663A (41.2%) and T846C (88.2%) were also prevalent in the samples analyzed. The yeast two-hybrid system was adopted for rapid assessment of relative E7-pRb binding affinity in the variants. The relative binding affinities of the E7 proteins of different HPV types to pRB were in close agreement with previous biochemical data. A T663G/C24W polymorphic change in E7 correlated with a decrease in E7-pRb relative binding affinity the significance of which remains to be clarified. This semi-quantitative biochemical and genetic approach may be useful as a first step in the development of clinical protocols for the screening and identification of important HPV variants for clinical interpretation and for further functional analysis by transfection or other bioassays.

Semiautomated typing of human papillomaviruses by restriction fragment length polymorphism analysis of fluorescence-labeled PCR fragments

A simplified version of a PCR-based reductional restriction fragment length polymorphism (rRFLP) approach for typing of human papillomaviruses (HPVs) is described previously [Wang et al., 1997]. It is achieved by the use of a biotin-labeled primer in PCR which, on restriction digestion and staining, is associated with only a single restriction fragment. In this report, we describe a further development of the rRFLP approach with the use of a fluorescence-labeled primer in PCR and fragment detection by laser scanning in an automatic sequencer. HPV typing is achieved by computer-assisted matching of the fluorescence-labeled rRFLP patterns with a database of rRFLP patterns of all known anogenital HPV types. On analysis of the typing of 133 HPV-positive cases using this procedure, 20 different HPV types were detected in exfoliated cervical cells in PAP smear samples derived from Taiwanese women. The results indicate the existence of a heterogeneous population of HPV types in Taiwan. Although most cases were associated with the more common HPV types, a significant fraction (about 20%) of the HPV types detected was related to the less common genotypes, which are often not included in commercial kits available for HPV typing. The results indicate the importance of covering as many HPV types as possible in clinical HPV genotyping protocols.

Gender determination in single bovine blastomeres by polymerase chain reaction amplification of sex-specific polymorphic fragments in the amelogenin gene

A sensitive technique for the sexing of bovine embryos was developed using polymerase chain reaction (PCR) amplification of the bovine amelogenin (bAML) gene on the X- and Y-chromosomes of Holstein dairy cattle. Cloning and DNA sequencing showed a 45.1% homology between the fifth intron of the bAML-X and bAML-Y gene with multiple deletions. A pair of sex-specific primers was designed to allow amplification of a single fragment of 467-bp from the X-chromosome of female cattle and two fragments of 467-bp and 341-bp from the X- and Y-chromosomes of male cattle. The primers were successfully applied to bovine sexing from single blastomeres isolated from day-6 to day-7 cow embryos by direct cell lysis and PCR. Our protocol of embryo sexing should be applicable to the diagnosis of defective genes in vitro in human embryos and in other domestic or recreational animals.

A point mutation in the albumin gene in a Chinese patient with familial dysalbuminemic hyperthyroxinemia

Familial dysalbuminemic hyperthyroxinemia (FDH) is an autosomal dominant disorder characterized by euthyroid hyperthyroxinemia. However, FDH has not been reported in Chinese or African patients. Here, we report the first case of FDH in a Chinese patient. A 69-year-old Chinese man was found to have increased serum total T(4) concentrations (198-242nmol/l; normal range 58-148nmol/l) and free T(4) concentrations (>58pmol/l; T(4) analog method, normal range 9-28pmol/l). Serum total T(3) and TSH concentrations were normal. The patient was misdiagnosed as hyperthyroid and was later suspected to have a TSH-producing tumor by the finding of a pituitary microadenoma, which was eventually proven to be a non-functional pituitary 'incidentaloma'. Electrophoretic analysis of the patient's serum proteins demonstrated enhanced albumin binding of [(125)I]T(4). Serum free T(4) concentrations were normal (16-19pmol/l, normal range 9-26pmol/l) when a two-step method was used. Direct sequencing of the albumin gene showed a guanine to adenosine transition in the second nucleotide of codon 218, resulting in a substitution of histidine (CAC) for the normal arginine (CGC) in one of the two alleles in the patient. The point mutation was further confirmed by HphI digestion of exon 7 of the albumin gene. The patient's son was not affected. Our studies demonstrated that the point mutation of the albumin gene in a Chinese patient with FDH was similar to that found in western white families, but differed from that in a Japanese family in whom a guanine to cytosine transition at the same position was found.

Polymorphisms of twelve short tandem repeat loci in a Taiwanese population and their application in parentage testing

With the advancement of techniques in molecular biology, rapid, sensitive, and reliable methods of DNA typing for parentage testing have become available. In this study, we evaluated the usefulness of multiplex polymerase chain reaction (PCR) with 12 unlinked short tandem repeat (STR) loci for paternity testing in Taiwan. The genetic informativeness of this test was then compared with that of conventional human leukocyte antigen (HLA) analysis in 167 parentage studies. The 12 STR loci alone provided a cumulative power of exclusion of up to 0.9998. Paternity was excluded in 59 (35.3%) cases, including 40 of 112 paternity trios and 19 of 55 paternity duos. In the 40 trios in which paternity was excluded, a mean of 6 (range, 3-9) incompatible STR markers were in the 19 duos in which paternity was excluded, a mean of 4 (range, 1-8) incompatible STR markers were noted. In the 72 trios in which the alleged paternity could not be excluded, the mean probabilities of paternity (PP) were 90.6863% with HLA testing alone, 99.9847% with STR analysis alone, and 99.9972% with combined HLA and STR analysis. In the 36 duos in which the alleged paternity could not be excluded, the mean PPs were 81.4768% with HLA testing alone, 99.6124% with STR analysis alone, and 99.9145% with combined HLA and STR analysis. These results suggest that STR analysis is very powerful when used alone for paternity trio testing and when combined with conventional serologic HLA typing for duo parentage testing in the Taiwan population.

Intrahepatic vein fetal blood sampling: current role in prenatal diagnosis

OBJECTIVE

To identify the site of fetal blood sampling (FBS) with lesser complications; and also analyses the reasons for targetting the intrahepatic vein (IHV) for FBS.

METHODS

Fetal blood sampling (FBS) performed on 382 women over a period of 7 years at the National University Hospital, Singapore was analysed. FBS was performed from 13 weeks of gestational age onwards. In 76.4% (292 of 382) the intrahepatic part of the umbilical vein (IHV) was targetted; in 18.3% (70 of 382) percutaneous umbilical cord sampling (PUBS) was performed; in 5.2% (20 of 382) cardiocentesis was performed to obtain fetal blood.

RESULTS

Multivariate analysis showed an increase in odds of fetal loss for umbilical cord and cardiocentesis groups compared with the IHV FBS group. It was statistically significant (p < 0.01) only in the cardiocentesis group for fetal loss at < 2 weeks of performing the procedure.

Specific inhibition of delta antigen by in vitro system by antisense oligodeoxynucleotide: implications for translation mechanism and treatment

Synthetic antisense oligodeoxynucleotides (ODNs) and a system containing transcription and translation coupled rabbit reticulocyte lysate were used to develop a new model modulating the synthesis of small delta antigen which, in turn, inhibits the replication of HDV (hepatitis D virus). The ODN was stable for at least 50 min in this system at 37 degrees C. Unmodified 15-mer antisense D3 and D4, complementary to translation initiation region and coding region, respectively, inhibit the synthesis of small delta antigen by 95% at a concentration of 5 microM, whereas antisenses complementary to 5' noncoding region, stop codon region and polyadenylation site were less effective. This system also showed a dose-dependent inhibitory effect of antisense D3 on the production of the target protein. However, the synthesis of E6 protein, an internal control, was not affected. These observations imply that this in vitro system is convenient for rapid screening of effective antisense compounds and offers a promising perspective for the investigation of translation mechanisms and for the inhibition of HDV replication by antisense strategy.

Secretory production of bioactive recombinant human granulocyte-macrophage colony-stimulating factor by a baculovirus expression system

The proliferation and differentiation of hematopoietic cells are stimulated by a group of glycoproteins called colony stimulating factors (CSFs). Previously, we found that the human hepatoma cell line HA22T/VGH secreted a high level of human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The cDNA of hGM-CSF, including the signal peptide sequence, was amplified from the total RNA of HA22T/VGH by a reverse-transcription polymerase chain reaction and was cloned into the pUC18 vector. After confirming the nucleotide sequence, the cDNA was inserted into a pVL1393 baculovirus transfer vector. The recombinant baculovirus carrying hGM-CSF cDNA was generated by co-transfecting the hGM-CSF recombinant transfer vector and BaculoGold baculovirus DNA into the Sf9 insect cells. The expected hGM-CSF transcript was detected in the recombinant virus-infected Sf9 cells. The conditioned media of the infected cells were analyzed by a slot-blot immunoassay. The results indicate that the infected insect cells produced and secreted hGM-CSF. According to colony forming assay, a maximum titer of 2.1 x 10(6). U ml-1 of hGM-CSF in the medium was obtained on the third day after infection.

Molecular analysis of cellular loci disrupted by papillomavirus 16 integration in cervical cancer: frequent viral integration in topologically destabilized and transcriptionally active chromosomal regions

To discern the structural features of cellular loci that are disrupted by type 16 human papillomavirus (HPV-16) integration in cervical cancer, a polymerase chain reaction (PCR)-based strategy was employed for direct amplification and sequence analysis of four such cellular loci in cancer biopsy samples. One of the HPV-16-disrupted loci was found to be the microtubule-associated protein (MAP-2) gene and the other three loci were uncharacterized and were designated PID-1 to -3 (for papillomavirus integration-disrupted). The junctional sequences of the viral integration sites in the four loci analyzed are bracketed by long tracts of homogeneous purine or pyrimidine or alternating purine-pyrimidine which are known to destabilize the B-form conformation of the DNA structure. Using a panel of human/hamster hybrid cell DNAs and PCR analysis, the four loci were assigned to chromosomes 2 (MAP-2), 9 (PID-1), 1 (PID-2) and 8 (PID-3), respectively. These chromosomes carry numerous other previously determined viral integration and chromosomal fragile sites and the myc oncogenes. The PID-1 locus was further found in Southern analysis to be rearranged and amplified in another cervical cancer biopsy and a cervical carcinoma cell line (CaSki). On Northern analysis, the PID-1 and -3 probes detected a 3.0- and a 3.6-kb transcript, respectively, in normal cervical cells and in cervical cancer cell lines. The findings suggest that HPV-16 genome integrates frequently into topologically destabilized and transcriptionally active chromosomal sites. It remains to be elucidated whether the MAP-2 and the PID loci contribute to the pathogenesis of cervical cancer.

Direct molecular diagnosis of CYP21 mutations in congenital adrenal hyperplasia

The majority of congenital adrenal hyperplasia (CAH) cases arise from mutations in the steroid 21-hydroxylase (CYP21) gene. Without reliance on HLA gene linkage analysis, we have developed primers for differential polymerase chain reaction (PCR) amplification of the CYP21 gene and the non-functional CYP21P gene. Using the amplification created restriction site (ACRS) approach for direct mutational detection, a secondary PCR was then performed using a panel of primers specific for each of the 11 known mutations associated with CAH. Subsequent restriction analysis allowed not only the detection but also the determination of the zygosity of the mutations analysed. Existing deletion of the CYP21 gene could also be detected. In the analysis of 20 independent chromosomes in 11 families of CAH patients in Taiwan, four CYP21 mutation types, besides deletion, were detected. Interestingly, in five different alleles, the CYP21P pseudogene contained some polymorphisms generally associated with the CYP21 gene. These results suggest gene conversion events that are occurring in both CYP21P and CYP21 genes. Our combined differential PCR-ACRS protocol is simple and direct and is applicable for prenatal diagnosis of CAH using chorionic villi or amniotic cells.

Single-step hybridization screening for recombinant DNA clones with correct insert orientation and intact junction using a junctional oligonucleotide probe

Cloning of DNA fragments with blunt ends or identical protruding ends results in colonies with the insertion sequence existing in two possible orientations. The orientation and the junctional sequence of the positive clones need to be established by means of restriction analysis and/or sequencing. Here, we proposed a rapid one-step method for the screening of clones not only with the desired orientation, but also with an intact junctional sequence. In this method, a 16-18 meric oligonucleotide probe synthesized according to the expected vector-insert junctional sequence is used as a probe in colony hybridization screening. Using this strategy, only recombinant clones which fulfill the above criteria will show positive signals in hybridization.

A method for screening antisense oligodeoxyribonucleotides effective for mRNA translation-arrest

A transcription and translation coupled reticulocyte lysate system was established for rapid screening of antisense oligodeoxyribonucleotides (ODNs) to determine which are most effective for mRNA translation-arrest. A plasmid containing the target cDNA under the control of the T7 (or SP6) promoter was added to the lysate system in the presence of the T7 (or SP6) RNA polymerase, RNase H, and the antisense ODN under test. Transcription and translation were accomplished in a one-tube reaction. Translation-arrest caused by antisense ODN was evaluated in terms of the amounts of de novo-synthesized, [35S]-methionine or [35S]cysteine labeled target protein measured by gel electrophoresis and autoradiography. The properties of this system and optimal reaction conditions for use in antisense ODN screening were determined. Our method is simpler and more rapid than other in vitro screening methods.

Constitutive production of colony-stimulating factors by human hepatoma cell lines: possible correlation with cell differentiation

A panel of two poorly differentiated (HA22T/VGH and SK-Hep-1) and six well-differentiated (HuH-6-cl 5, HuH-7, PLC/PRF/5, Hep G2, Hep 3B, and Tong) human hepatocellular carcinoma (HCC) cell lines were studied for the production of colony-stimulating factors (CSFs) using the granulocyte and macrophage colony formation (CFU-GM) assay, immunocytochemical staining, and Northern blotting. Medium conditioned by untreated HA22T/VGH cells contained a high level of CSFs that could stimulate the in vitro colony formation of human myeloid progenitor cells. The HA22T/VGH cell-derived CSF had an apparent molecular weight of 23 kD. Its activity could be effectively neutralized by antiserum against granulocyte-macrophage CSF (GM-CSF) but not by antibodies to other hematopoietic growth factors, including G-CSF, M-CSF, interleukin-3 (IL-3), and IL-6. Correspondingly, immunocytochemical studies using monoclonal anti-GM-CSF showed a strong positive reaction in the cytoplasm of the HA22T/VGH cells. Northern blot analysis revealed that untreated HA22T/VGH cells expressed a considerable amount of GM-CSF mRNA, confirming that GM-CSF production was constitutive. At optimal concentrations, lipopolysaccharide (LPS), IL-1beta, interferon-gamma (IFN-gamma), and tumor-promoting phorbol diester (TPA) could all stimulate HA22T/VGH cells to secrete GM-CSF. In addition to HA22T/VGH, SK-Hep-1 cells could also produce GM-CSF, although less effectively, whereas all the well-differentiated HCC cell lines tested were negative for CSF production. Morphologic, cytochemical, and immunocytochemical examinations demonstrated that both poorly differentiated CSF-producing HCC cell lines (HA22T/VGH and SK-Hep-1) were macrophage-like in morphology, possessed nonspecific esterase (NSE) activity, and expressed CD14, CD68, and HLA-DR on their surface, while all the well-differentiated HCC cell lines were epithelioid and lacked myeloid differentiation antigens. These results suggest that monocytoid features and CSF production may be differentiation markers of hepatocytes at the immature stages, amd that the HA22T/VGH and SK-Hep-1 cell lines may be valuable tools for the study of hepatic function and differentiation.

Prevalence and type of precore hepatitis B virus mutants in hepatitis D virus superinfection and its clinical implications

To study the prevalence and type of the hepatitis B e antigen (HBeAg)-negative mutant in hepatitis D virus (HDV) superinfection, the precore region of hepatitis B virus (HBV) was analyzed by cycle sequencing. Of the 58 samples sequenced, 24 were wild type and 34 carried mutants. The precore stop mutation (TAG) at the 28th codon was found in 32 cases, other mutations were found in 7, and double mutations were found in 5. The absence of HBeAg showed a substantial agreement with the presence of mutants (kappa value, 0.74). Of the acute hepatitis patients, HDV replication and clinical manifestations were not significantly different between those with mutant and wild type virus, except that those with mutant virus were older (mean age, 48 vs. 28 years; P < .002). The absence of HBeAg in these patients is mainly due to HDV superinfection in older HBV carriers who already had precore mutant.

Evidence of transmission of hepatitis D virus to spouses from sequence analysis of the viral genome

To study sexual transmission of hepatitis D virus (HDV), 52 spouses of 56 index patients were observed and HDV genomes from antibody to HDV (anti-HDV)-positive couples were sequenced. Of the spouses, 11 (21%) were serum HBsAg positive, 3 (27%) of whom were also anti-HDV positive. The HDV sequences between spouses were found to be nearly identical (98% to 98.8%) in the region analyzed (nt 911 to nt 1260). Only one couple showed an identity > 90% with the genotype I HDV strains. The HDV sequences of the remaining two couples showed > 95% identity with each other and > 91% homology with genotype II, but they shared only a 73.1% to 73.7% homology with those of the first couple. The regions corresponding to the autocatalytic cleavage sites, the junction between the middle and the carboxyl terminal one-third domains, and the middle domain of the open reading frame for delta antigen on the antigenomic HDV RNA were more conserved with < 19% divergence among the three couples. Interestingly, there was a 56% divergence in the region corresponding to the carboxyl end of the open reading frame for the large delta antigen on the antigenomic HDV RNA. In summary, this study provides a direct nucleotide evidence of a common source of HDV infection in each couple. Despite divergence in the viral nucleotide sequence, both genotypes I and II were found in Taiwan and were transmitted from patients with a history of prostitute contact to spouses through sexual contact.

Genotyping of hepatitis D virus by restriction-fragment length polymorphism and relation to outcome of hepatitis D

The outcome of hepatitis D virus (HDV) superinfection varies among patients and in different geographical areas. To find out whether HDV genotype affects outcome, we used a simple genotyping method based on restriction-fragment length polymorphism with enzymes XhoI and SacII for cleavage of PCR products of the HDV genome. Of samples from 88 patients studied, the genotypes of 61 were confirmed by two methods--analysis with both enzymes or by combined restriction-enzyme and direct sequencing analyses--with consistent results. No genotype III HDV was detected among these patients. The majority of patients with acute HDV infection (35/41 [85%]) had genotype II HDV. Among the 41 patients with acute infection, four of six with genotype I had fulminant disease compared with two of 35 with genotype II. Among patients in chronic stage, cirrhosis or hepatocellular carcinoma were found in 12 of 18 with genotype I HDV and eight of 29 with genotype II. Thus genotype II was the predominant HDV genotype in this study in Taiwan. Genotype II HDV was less frequently associated with fulminant hepatitis at the acute stage or with an unfavourable long-term clinical outcome at the chronic stage than was genotype I.

Jun-B oncogene aberrations in cervical cancer cell lines

We describe here structural and expression analysis of the jun-B oncogene in two cervical cancer cell lines. In the CC7T-a cell line, results from both Southern analysis and cDNA cloning studies revealed the existence of two structurally altered jun-B alleles besides the normal gene. One of the altered alleles was due to a type 16 human papillomavirus (HPV-16) integration event, whereas the other allele was a consequence of a chromosomal translocation involving chromosome 19 (jun-B) and an EST182 locus residing in chromosome 15. In the HeLa cell line, which contains integrated HPV-18, an apparent structural aberration, a 3-fold amplification and a 3-fold overexpression of the jun-B gene were observed. Our observations suggest that deregulation of the jun-B gene expression may have contributed to the transformation process in these two cervical cancer cell lines.

Inhibition of alpha-fetoprotein production in a hepatoma cell line by antisense oligonucleotide analogues

alpha-Fetoprotein (AFP) is a fetal protein which is absent in adult serum. However, the AFP gene is expressed in some neoplastic cells. According to the literature, AFP may play a role in accelerating the growth of cancer cells. In this report, 15 meric antisense oligonucleotide analogues (phosphorothioates and methylphosphonates) and their chimeric forms, which were complementary to different regions of AFP mRNA, were synthesized, and their physical characteristics such as stability, melting temperature, and toxicity were compared. They were examined as to their inhibitor effects on the translation of AFP mRNA in a AFP-producing hepatoma cell line, HuH-7. We found that chimeric oligomers with methylphosphonate or phosphorothioate linkages at both the 5' and 3' ends were more effective than prototypic oligomers. Inhibition of 72% was achieved with a chimeric oligomer against the translational initiation region, at a concentration of 25 microM. No suppressive effect of the oligomers was observed on cell viability or albumin production, indicating the specificity of the inhibition.

Frequent deletions and sequence aberrations at the transgene junctions of transgenic mice carrying the papillomavirus regulatory and the SV40 TAg gene sequences

Exogenous DNA microinjected into one-cell mouse zygotes either integrates into the host genome within a short time span, or is rapidly degraded. On integration, a transgene sequence is frequently reiterated. In this report, we describe the enzymatic amplification analysis of transgene junctions of 12 transgenic mice carrying different copy numbers of the same transgene with dissimilar ends. The transgene was composed of the regulatory sequence of the type 18 human papillomavirus linked to the TAg gene of the SV40 virus. Nucleotide sequences of 36 of these junctions were also determined. Deletions were found in 33 (91.7%) of the junctions analysed. At the crossover regions, 55.6% contained short overlapping sequences of one to six nucleotides. Insertions of 2-6 extraneous nucleotides were also found in 8.3% of the transgene junctions. Within a 10-nucleotide sequence on both sides of the transgene junctions, topoisomerase I (topo I) cleavage sites, runs of homogeneous purines or pyrimidiens, alternating purine-pyrimidine tracks and (A-T)-rich sequences were found frequently. Stringent control experiments were also performed to ascertain that the observations made were not artefacts resulting from the polymerase chain reaction. Our data therefore indicate that damage had occurred quite frequently and extensively in our transgene construct. Such transgene damage may also occur to various extents in mice carrying other transgenes. Primary structure of the nucleotide sequences of the injected DNA seems to influence the process of transgene reiteration and aberration.

Analysis of deletion of the integrated human papillomavirus 16 sequence in cervical cancer: a rapid multiplex polymerase chain reaction approach

A protocol for a rapid physical mapping of the integrated type 16 human papillomavirus (HPV16) sequences in biopsied and paraffin-embedded archival cervical cancer samples is described. The procedure involves the use of an anchor primer and a mixture of indicator primers in a multiplex polymerase chain reaction (PCR). A minimal conserved region of viral integration of 2,745 bp in length has been mapped between nucleotide (nt) 6102-941, containing the entire regulatory region and the E6 and E7 open reading frames (ORFs). A general deletion domain of 1,465 bp in the integrated viral genome has been defined between nt 1417-2881, covering most of the E1 ORF at the 3'-half and 60 bp at the 5' terminus of the E2 ORF. This common deleted sequence contains an ATPase active domain speculated to be associated with a DNA helicase function essential for the viral replication, and it also falls within the actively spliced E1-E2 segment of the primary RNA transcripts. Detection of the loss of the 3'-half of the E1 ORF would be an ideal marker for PCR-based rapid determination of HPV integration in cervical cancer cells.

Prenatal diagnosis of beta-thalassemic mutations in Chinese by multiple restriction fragment-single strand conformation polymorphism analysis

A modified approach of polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) has been developed for prenatal diagnosis of beta-thalassemic mutations. In this method, a single PCR product (1,350-bp) is first generated, which is then digested by restriction enzymes (BbsI, BamHI, DraI) to generate multiple shorter restriction fragments for electrophoretic analysis in an SSCP gel. The method is thus termed multiple restriction fragment (MRF)-SSCP. Two cases of chorionic samples and the blood samples of their parents were studied. The previously described amplification-created restriction site (ACRS) method was used to confirm the SSCP results obtained. Two polymorphic sites of the beta-globin gene which would influence the MRF-SSCP patterns are described, including a previously undescribed polymorphic site located at codon 3 (CAT or CAC) of the beta-globin gene.

Hypermethylation of the human papillomavirus transgenome in transgenic mice

We have previously reported an observation that the regulatory sequence of the human papillomavirus (HPV) type 18 genome elicits only basal and unregulated transcriptional activities in transgenic mice [Choo et al., Virology (1992) 188:378-383]. We have now extended the study to other transgenic mice carrying an entire or a subgenomic fragment of HPV-16 and -18. Extremely low levels of HPV transcripts were detected in various organs of the mice only by reverse transcriptase-based polymerase chain reaction. On analysis of the methylation status of the HPV transgenome sequences, hypermethylation was clearly observed, therefore suggesting a possible explanation for low level HPV transgenome transcriptional activity in HPV transgenic mice.

Post-hybridization recovery of membrane filter-bound DNA for enzymatic DNA amplification

We describe here a simple and rapid method for enzymatic DNA amplification using DNA template recovered from membrane filters previously used in hybridization analysis. This is done by first solubilizing membrane pieces carrying DNA of interest in dimethyl sulfoxide, followed by isopropanol precipitation and polymerase chain reaction amplification. The source of membrane-bound DNA successfully tested includes plasmid and human leukocyte DNA and DNA immobilized on bacterial colony filters and plaque lifts. The sensitivity of the procedure is such that DNA recovered from 0.5 microgram of filter-bound total human DNA was enough for PCR amplification of a 0.3-kb fragment. Our protocol will be useful for recycling of scarce DNA samples for cloning and sequencing purposes.

Absence of mutation in the p53 and the retinoblastoma susceptibility genes in primary cervical carcinomas

Previous biochemical and structural studies using established cell lines have led to a hypothesis that the cellular p53 and the retinoblastoma susceptibility (Rb) proteins may play a crucial role in the pathogenesis process of cervical carcinoma. To further test this hypothesis, we have analyzed the structure of the p53 and Rb genes in 38 primary cervical carcinoma samples with known HPV status using the polymerase chain reaction-based single-strand conformation polymorphism (SSCP) approach. All 11 exons as well as 500 bp of the 5'-noncoding region of the p53 gene and exons 13-23 of the Rb gene were analyzed. None of these exons in all the samples analyzed showed band shift in the SSCP gel indicative of the presence of mutation. In the same experiments, however, all known exon mutations as well as previously unreported mutations in the intron sequences of the p53 and Rb genes in the HPV-free C33-A and HT-3 cell lines were detected. The absence of mutation in the p53 gene in all five HPV-negative samples was confirmed by direct sequence analysis. It appears that p53 and Rb mutations are a very rare event in cervical cancer and their occurrence is apparently not strictly correlated with HPV status.

Effect of an extract from Phyllanthus amarus on hepatitis B surface antigen gene expression in human hepatoma cells

It has been suggested that Phyllanthus amarus may be helpful in the treatment of hepatitis B virus infection. We studied the effect of an aqueous extract of P. amarus on the cultured hepatoma cell line HepA2. This cell line had been transfected with tandemly arranged HBV DNA and continued to synthesize and secrete both HBsAg and HBeAg. Extract of P. amarus reversibly inhibited cellular proliferation and suppressed HBsAg production but not HBeAg production in HepA2 cells. We also found that P. amarus suppressed HBsAg gene expression at mRNA level in a time-dependent manner, and selectively abolished the HBsAg gene promoter driven CAT activity. Our results demonstrate that P. amarus contains some active components which can suppress the HBsAg gene expression in human hepatoma cells. Such suppression may contribute the antiviral activity of P. amarus in vivo.

Detection of mutations in the p53 gene in human head and neck carcinomas by single strand conformation polymorphism analysis

Using the polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) analysis, we have examined the highly conserved regions of the p53 gene in 58 biopsy samples of head and neck tumors. Mutations were found in 13/58 (23%) tumor specimens, but not in 6 normal tissues. Ten of 13 mutations were due to single base changes and the remaining 3 were 1- or 8-base deletion mutants. These mutations were clustered in exons 5 and 7 and resulted in amino acid changes. Our results seem to indicate that mutations in the p53 gene contribute to a significant number of cases of the head and neck tumors including 20% of nasopharyngeal carcinoma biopsies. The relationship of Epstein-Barr virus or human papillomavirus and p53 gene mutations in this group of cancers was also analyzed and discussed.

Mutational analysis by a combined application of the multiple restriction fragment-single strand conformation polymorphism and the direct linear amplification DNA sequencing protocols

We describe here an improved procedure for polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) for rapid mutational detection. To circumvent the restriction of having to analyze relatively short PCR fragments, restriction endonucleases were used to cleave a longer PCR product and the mixture of fragments was analyzed directly in SSCP gel electrophoresis. This multiple restriction fragment (MRF)-SSCP protocol was demonstrated by the detection of a 4-bp deletion in codons 41-42 and a point mutation in the IVS-2 sequence of the human beta-globin gene. The MRF-SSCP or the standard SSCP protocol was then combined with the linear amplification DNA sequencing (LADS) procedure for direct analysis of the PCR products without further purification for an exact characterization of the mutations detected. In the LADS analysis, homo- or heterozygosity of a mutation was easily distinguished by the appearance of a single- or double-lane band in the sequencing gel. The choice of isotope used and different labeling methods were compared and were found, in some cases, to produce SSCP patterns of different complexities. The combined MRF-SSCP/LADS protocol permits rapid mutational analysis of a large number of clinical samples using only very small amounts of materials and can easily be adopted for nonisotopic clinical applications.

Unregulated and basal transcriptional activities of the regulatory sequence of the type 18 human papillomavirus genome in transgenic mice

Type 18 human papillomavirus (HPV18) is a genital virus closely associated with cervical carcinoma. To analyze the transcriptional activities of the long control region (LCR) of the HPV18 genome, we have produced 12 transgenic mice harboring the HPV18/LCR sequence fused to a promoterless SV40 T-antigen (TAg) gene. The mice were small in body size, generally very weak, and none lived longer than 110 days. Three mice with the longest life span (58-110 days) developed hyperplastic thymus and/or lymph node and were further analyzed. In these mice, Northern hybridization failed to detect TAg transcripts in any of the 25 organs studied. However, spliced TAg RNA was detected by polymerase chain reaction in the hyperplastic thymus and lymph node and in the normal submaxillary gland, stomach, large intestine, urinary bladder, and the cerebrum, indicating the presence of very low cellular levels of TAg RNA in these organs. When immunostaining was performed on the hyperplastic thymus, TAg protein was detected only in the ductal epithelial cells. Our results appear to indicate that the HPV18/LCR sequence was able to express only unregulated and basal levels of transcriptional activity in transgenic mice. Such a mode of transcription has become a major hindrance in the use of transgenic mouse system for the studies of the biology of the human papillomavirus.

Characterization of a monoclonal antibody (P40) against the 68 kD major allergen of Penicillium notatum

A monoclonal antibody (MoAb P40) against the 68 kD major allergen of Penicillium notatum (P. notatum) was obtained by immunizing the mouse with a crude extract of P. notatum. Analysed by two-dimensional gel electrophoresis and immunoblotting, P40 reacted with two different isoforms of the 68 kD component of P. notatum with pIs of 5.4 and 5.5. In addition to P. notatum, P40 showed positive ELISA activity to Aspergillus fumigatus (A. fumigatus) but not to components of six other fungi including Alternaria porri, Cladosporium cladosporoides, Aureobasidium pullulans, Fusarium solani, Rhizopus arrhizus and Candida albicans. Analysed by ELISA, MoAb P40 also showed positive activity to two (P. frequentans and P. roseopurpureum) of the 10 other Penicillium species and two (A. terreus and A. flavus) of the four other Aspergillus species tested. SDS-PAGE and immunoblotting studies demonstrated P40 positive reactivity to components with MW of about 67 kD in all these Penicillium and Aspergillus species with positive ELISA activity to P40. Furthermore, immunoblotting activity of MoAb P40 to the 67 kD component of A. niger was also observed. The epitope of the 68 kD allergen of P. notatum recognized by MoAb P40 was resistant to treatment of periodate oxidation with concentration of NaIO4 up to 20 mM. This MoAb may thus be useful in the characterization and purification of the 68 kD allergen from crude extracts, and in the molecular cloning of allergen genes.

A common precursor for a putative hemorrhagic protein and rhodostomin, a platelet aggregation inhibitor of the venom of Calloselasma rhodostoma: molecular cloning and sequence analysis

Rhodostomin is a platelet aggregation inhibitor secreted by the venom gland of Calloselasma rhodostoma. We report here the isolation of a 1.67-kilobase (kb) lambda gt11 cDNA clone using degenerate oligonucleotide probe based on a partial amino acid sequence of rhodostomin. The amino acid sequence deduced from an open reading frame of the cDNA indicates that (i) the 68-amino acid sequence of rhodostomin is located at the carboxyl terminus of the precursor polypeptide and (ii) a peroxisomal targeting sequence (ser.his.ala.) exists between the stop codon and the rhodostomin sequence of the precursor. Since the amino-terminal segment of the deduced sequence shows a high degree of identity with hemorrhagic proteins, which are zinc-metalloproteinases, found in the venom of some crotalid and viperid snakes, our results also predict the existence of at least one such hemorrhagic protein in the venom of Calloselasma rhodostoma. The derivation of a platelet aggregation inhibitor and a hemorrhagic protein from the same precursor protein is consistent with the fact that these proteins may be synergistic in function.

The 40-kilodalton allergen of Candida albicans is an alcohol dehydrogenase: molecular cloning and immunological analysis using monoclonal antibodies

To characterize the 40-kilodalton (kD) major allergen of Candida albicans (C. albicans), six monoclonal antibodies (MoAbs) against this allergen were generated. In SDS-polyacrylamide gel electrophoresis and immunoblot analysis, these MoAbs showed four different reaction patterns to antigens of six different Candida species. With the exception of one MoAb, other MoAbs were resistant to periodate treatment indicating non-carbohydrate epitopes were probably being recognized by these MoAbs. These MoAbs were used in the molecular cloning and immunological analysis of the gene coding for the 40-kD allergen. Nucleotide sequence determination of the two lambda gt11 cDNA clones obtained showed that the 40-kD allergen is an alcohol dehydrogenase (ADH) which shares a 70% amino acid sequence homology with the ADH isozyme I of Saccharomyces cerevisiae. This finding was confirmed by positive immunological response of the lysates of the clones obtained and a preparation of ADH of Saccharomyces cerevisiae to various MoAbs and to IgE antibodies in sera of allergic patients.

Immunoblot analysis of components of Penicillium notatum recognized by human IgE antibodies

Components of the crude extract of Penicillium notatum recognized by human IgE antibodies (Abs) were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The allergenic components were identified with sera from 19 allergic patients and 20 blood donors. The allergen-Ab complexes were visualized by 125I-labeled monoclonal antihuman IgE and autoradiography. A total of 11 allergenic components, ranging in molecular weights (MWs) from 94,000 to 20,000 daltons, were identified. Heterogeneity in the IgE-binding patterns of the serum samples tested was also observed. However, the major allergen appears to be the component with an MW of about 68,000 daltons that was recognized by IgE Abs in 56% of the 39 sera analyzed. Furthermore, the component with an MW of about 64,000 daltons that was recognized by IgE Abs in 46% of the sera analyzed was also considered as an important allergen. Results obtained from this study will be useful in additional characterization of allergens of P. notatum and related fungal species.

Transgenome transcription and replication in the liver and extrahepatic tissues of a human hepatitis B virus transgenic mouse

We have produced a transgenic mouse (B32-1) carrying the complete genome of the human hepatitis B virus (HBV). High titers of the viral surface (HBsAg) and the e antigen (HBeAg) were detected in the serum of the mouse. In the liver and 12 of 16 extrahepatic tissues analyzed, Northern blot hybridization indicated the presence of the 2.1-kilobase (kb) and the 3.5-kb major HBV transcripts. A liver cDNA library was constructed from which the liver RNAs from four cDNA clones with splicing were found. Sequencing analysis showed that the splicing occurred between nucleotides 2451 and 487 of the viral genome, resulting in a truncated viral polymerase gene, as in human hepatocytes. Southern blot analysis of total DNA preparations of the tissues revealed the presence of episomal HBV genome, indicating replication of the viral transgenome in these tissues. However, replication was detected only in some but not all of the tissues that transcribed the 3.5-kb RNA. Partial double-stranded as well as full-length and subgenomic-length single-stranded HBV DNA species of discrete sizes were detected which may represent replication intermediates of preferred replication termination sites of the HBV transgenome. Since many molecular characteristics of mouse B32-1 were similar to those found in HBV-infected humans, HBV transgenic mice similar to B32-1 would be useful in further elucidation of other aspects of the replication and transcription mechanisms of HBV in the liver and extrahepatic tissues.

Detection of beta-globin gene mutations by polymerase chain reaction

The polymerase chain reaction and oligonucleotide probe hybridization technique were applied to the detection of two common mutations of the beta-globin gene found in Chinese, namely the 4-base pair deletion at the 41-42 codons and the C to T substitution at nucleotide 654 of IVS-2. The accuracy of the method was established using beta-thalassemia cases with known mutations or haplotypes of the restriction fragment length polymorphism (RFLP). A further 11 cases of thalassemia intermediate and thalassemia minor were then analysed with the same approach. Our results showed that 5 of the 11 cases carried the TCTT-deletion at codons 41-42. Our method is economical both in terms of materials and time needed and in an alternative to the use of the molecular RFLP approach in the prenatal diagnosis of beta-thalassemia.

Characterization of a monoclonal antibody (RJ5) against the immunodominant 41-kD antigen of Candida albicans

A 41-kD component of Candida albicans was identified to be the major antigen radioimmunoprecipitated by antibodies with increased titers in the sera of patients with invasive candidiasis. A mouse monoclonal antibody (RJ5) was generated which, by immunoblotting, showed positive reactivity to the immunoprecipitated 41-kD component. By two-dimensional gel electrophoresis and immunoblotting, MoAb RJ5 was shown to react with different isoforms of the 41-kD component with pI values from 6.1 to 6.9. Furthermore, MoAb RJ5 showed positive reactivity to cytoplasmic antigens of C. albicans by frozen section and immunoperoxidase staining. By SDS-polyacrylamide gel electrophoresis and immunoblotting, MoAb RJ5 showed no cross-reactivity to antigens of Candida tropicalis and Candida parapsilosis. The epitope of the 41-kD molecule recognized by MoAb RJ5 was susceptible to treatment of proteinase K at concentrations of greater than or equal to 5 micrograms/ml, and was relatively resistant to periodate oxidation with concentration of NaIO4 up to 20 mM. This MoAb may be useful in the purification and characterization of the immunodominant 41-kD antigen of C. albicans, and as a probe in the detection of Candida antigens in the sera of patients with invasive candidiasis.

Rapid verification of lambda-cDNA clones using mixed-base oligonucleotide as screening probe and sequencing primer

A rapid procedure has been developed for the isolation and verification of cDNA clones isolated from a cDNA library based on lambda vectors. Using information of the partial amino acid sequence of a protein, synthetic mixed-base oligonucleotides are first employed as a screening probe using the plaque hybridization procedure. The cDNA inserts of the clones obtained are then directly amplified by polymerase chain reaction (PCR) using primers flanking the cloning site of the vector. Besides being used for cloning into a plasmid vector, the amplified DNA's are also subjected to nucleotide sequence analysis using the same mixed-base oligonucleotides as sequencing primers. This approach allows sequencing through the region of the known amino acid sequence for direct verification of the authenticity of the clones obtained. This procedure has successfully been used for cloning and partial characterization of the gene coding for a platelet aggregation inhibitor.

Detection of human papillomavirus DNA in human cervical lesions by tissue in situ nucleic acid hybridization

Cervical cancer is one of the most common female cancers in Taiwan. Certain types of human papillomavirus (HPV) are frequently detected in the epithelial precancerous and cancerous lesions of the cervix. By the use of tissue in situ hybridization, we investigated the relationship of various types of HPV (group I, HPV-6 & 11, group II, HPV-16 & 18, group III, HPV-31, 33 & 35) with cervical condyloma, carcinoma as well as precancerous lesions. Group I HPV DNAs were mainly found in cervical condylomatous lesions (2/2) of the cervix and cervical intraepithelial neoplasia I (CIN I) (2/4), but were only occasionally found in CIN II (1/4), CIN III (1/9) or non-keratinized squamous cell carcinoma (1/15). HPV DNAs of groups II and III were mainly detected in lesions of CIN III (5/9) and invasive squamous cell carcinoma (large cell, keratinized type: 4/7; large cell, non-keratinized type: 11/15). HPV DNA sequences were invariably detectable only in the cell nuclei of condyloma or dysplastic epithelium or invasive carcinoma. However, they could not only be detected in the upper layer dysplastic cells and koilocytes but also in the well and poorly differentiated cervical cancer cells. The distribution of HPV DNA positive cells in the carcinomas fell into four different patterns: (1) upper zone and non-invasive regions of the carcinoma (11/22, 50%), (2) basal zone and invasive regions (2/22, 9%), (3) randomly scattered (7/22, 32%), and (4) extensively distributed over the whole tumor lesions (2/22, 9%). Thus, our results are consistent with a strong correlation between the presence of HPV-16, 18, 31, 33 and 35 and malignant conversion of cervical epithelial cells.

Analysis of the unoccupied site of an integrated human papillomavirus 16 sequence in a cervical carcinoma

We have previously cloned and analyzed the structure of a type 16 human papillomavirus (HPV16) integration in a primary cervical carcinoma tissue, M50 (Choo et al., J. Virol. 62, 1659-1666, 1988). We found that specific nucleotide sequences within the HPV16 genome influenced the genomic organization of the integrated viral genome. Using the viral-cellular junctions of the M50 DNA as probes, we have now cloned the unoccupied site from a human genomic library. Mapping analysis showed that a deletion of about 1.1 kilobase pairs (kb) had occurred at the integration site of M50. Sequencing of the integration junctions of the unoccupied site and comparison with the viral sequence has revealed short regions of sequence homology between the viral and the cellular genomes at both junctions. Our results are consistent with a mechanism of integration of the HPV16 sequences in the M50 carcinoma involving illegitimate recombination events using short patches of homologous sequences between the two heterologous genomes for anchorage and as guides for crossover. Preferred topoisomerase I cleavage sites and alternating purine and pyrimidine bases, which favor the formation of Z-DNA, could also be identified at the integration regions, supporting a proposed role for the topoisomerase I enzyme in the illegitimate recombination in the viral integration process.

An improved scheme for the identification of antigens recognized by specific antibodies in two-dimensional gel electrophoresis and immunoblotting

This paper describes an improved scheme for the identification of antigens in crude extracts recognized by specific antibodies when analyzed by a combination of two-dimensional gel electrophoresis and immunoblotting. First, protein components in gels are electrophoretically transferred to a polyvinylidene difluoride membrane which does not shrink or change dimensions in organic solvents. The efficiency of transfer and the localization of sample proteins on the membrane are checked and recorded by staining the blotting membrane with Fast Green FCF and recording the profile on a transparency. After blocking and the immunoassay, the results are recorded by photography. The sites of immune reaction are marked and the same membrane is restained briefly with Coomassie Brilliant Blue R-250 for the protein profile. Thus antigens in complex mixtures, recognized by antibodies of interest, can easily be identified from the restained membrane. If the whole protein profile is not well demonstrated, when used in combination with the profile recorded on the transparency, spots appearing on the restained membrane can still be used as useful landmarks in the final unequivocal antigenic identification. This improved scheme circumvents problems arising from membrane shrinkage and difficulties in accurately matching immunoreactive spots by conventional procedures and thus provides an accurate, simple and fast approach in the identification of antigens after immunoblotting.

High prevalence of human papillomavirus infection and possible association with betel quid chewing and smoking in oral epidermoid carcinomas in Taiwan

Seventeen oral epidermoid carcinomas, three oral papillomas, and 17 normal gingival tissues were tested for the presence of human papillomavirus (HPV) types 6, 11, 16, and 18 sequences by Southern blot hybridization. Episomal HPV-16 sequences in various amounts were detected in 76.4% of the oral carcinomas and in all three cases of papilloma. However, only one of the 17 normal tissues was HPV positive with an unknown type. None of the samples contained HPV-6, -11, or -18 sequences. Examination of the habits of the patients showed that 59% of the patients were betel quid chewers and 82% were smokers. Thus, the concurrent incidence of HPV infection and betal quid chewing and/or smoking habits in oral carcinoma patients observed in Taiwan is consistent with the view that both viral and chemical factors may be involved in the process of carcinogenesis.

Allergenic components of Candida albicans identified by immunoblot analysis

Allergenic components of Candida albicans fractionated by SDS-polyacrylamide gel electrophoresis (PAGE) and transferred to nitrocellulose membranes were identified using sera from 30 asthmatic patients who showed positive skin test and RAST (radio-allergosorbent test) to C. albicans. The IgE-binding yeast components in the complex antigen preparation were then detected by reaction with enzyme-labelled anti-human IgE antibodies. They were confirmed by Coomassie blue R-250 staining of the membrane to visualize all protein bands after reaction with the enzyme substrate. The IgE-binding patterns of the sera tested were heterogeneous, displaying a total of 16 identifiable components with molecular weights ranging from 20 to 94 kD. A 40 kD component showed the highest IgE-binding frequency, being recognized by 23 (77%) of the 30 sera examined. The other 15 allergenic components identified were recognized by less than 25% of the sera tested. Only two of the 30 serum samples contained IgE antibodies reactive with seven to eight allergenic components. Ten of the 30 sera reacted with only one allergenic component, and the remaining serum samples recognized two to five of the 16 identified allergens. Results described in this study are applicable to allergen standardization work and provide a basis for further study on the role of C. albicans in clinical allergy.

Presence of catenated human papillomavirus type 16 episomes in a cervical carcinoma cell line

Human papillomavirus (HPV) is frequently associated with cervical carcinoma and derived cell lines. In primary tissues of the carcinoma, the viral genome may be present in episomal or integrated configuration. In cell lines, however, only integrated HPV sequences have been reported. In this article, we describe the presence of episomal type 16 HPV (HPV16), demonstrated by electron microscopy and two-dimensional agarose gel electrophoresis, in a cervical carcinoma cell line, CC7T/VGH, established in 1980 in Taiwan. In CC7T/VGH, the HPV16 sequences are transcriptionally active, and at least three major HPV16 RNA species were detected in Northern blots. Results from restriction enzyme and S1 nuclease analysis suggest a composition of oligomeric HPV16 molecules in dimeric repeats. In addition, the HPV16 oligomers exist as catenated molecules of interlocking rings instead of concatemers. A monomeric copy of the HPV16 episome was cloned from a Hirt supernatant of CC7T/VGH by using a plasmid vector. Mapping and partial sequencing studies revealed an internal deletion of 163 base pairs within the L1 open reading frame. However, insertion of an A.C nucleotide pair at the deletion junction restored the otherwise frame-shifted L1 open reading frame. Two base transitions were also found within the E7 and the E1 open reading frames. Our findings suggest the need for closer examination for HPV episomal catenation in other cervical carcinoma cell lines as well as in primary carcinoma tissues of the uterine cervix and the anogenital tract. With CC7T/VGH, a way is now available for studies of many important aspects of the biology of HPV such as replication and gene expression of the extrachromosomal viral genome.

Analysis of the structure and expression of the c-myc oncogene in cervical tumor and in cervical tumor-derived cell lines

The structure of the c-myc oncogene in 17 cervical tumors and patient-matched nontumor tissues from Chinese patients residing in Taiwan was analysed. In contrast to recent reports on Mexican patients, none of the samples showed rearrangements and sequence amplification in the c-myc gene. The discrepancy may be explained by different carcinogenesis mechanisms being in operation in different geographic regions. Although no structural alterations in the c-myc gene were found in seven cervical carcinoma cell lines analysed, Northern blot analysis indicated different levels of c-myc gene expression which may be related to the presence of human papillomavirus (HPV) sequence in the cell and suggests a possible c-myc-hpv interaction in some stages of the transformation process.