The murine cysteinyl leukotriene 2 (CysLT2) receptor. cDNA and genomic cloning, alternative splicing, and in vitro characterization

Two classes of cysteinyl leukotriene receptor, CysLT(1) and CysLT(2), have been identified and pharmacologically characterized in human tissues. Although the CysLT(1) receptor mediates the proinflammatory effects of leukotrienes in human asthma, the physiological roles of CysLT(2) receptor are not defined, and a suitable mouse model would be useful in delineating function. We report here the molecular cloning and characterization of the mouse CysLT(2) receptor (mCysLT(2)R) from heart tissue. mCysLT(2)R cDNA encodes a protein of 309 amino acids, truncated at both ends compared with the human ortholog (hCysLT(2)R). The gene resides on the central region of mouse chromosome 14 and is composed of 6 exons with the entire coding region located in the last exon. Two 5'-untranslated region splice variants were identified with the short form lacking exon 3 as the predominant transcript. Although the overall expression of mCysLT(2)R is very low, the highest expression was detected in spleen, thymus, and adrenal gland by ribonuclease protection assay, and discrete sites of expression in heart were observed by in situ hybridization. Intracellular calcium mobilization in response to cysteinyl leukotriene administration was detected in human embryonic kidney 293T cells transfected with recombinant mCysLT(2)R with a rank order of potency leukotriene C(4)(LTC(4) ) = LTD(4)>>LTE(4). [(3)H]LTD(4) binding to membranes expressing mCysLT(2)R could be effectively competed by LTC(4) and LTD(4) and only partially inhibited by LTE(4) and BAYu9773. The identification of mCysLT(2)R will be useful for establishing CysLT(2)R-deficient mice and determining novel leukotriene functions.

[Studies of intercellular communication in human rhabdomyosarcoma cell lines of different metastatic potential]

OBJECTIVE

To investigate the relationship between intercellular communication and three human rhabdomyosarcoma (RMS) cell lines of different metastatic potential.

METHODS

Indirect immunofluorescent staining and laser scanning confocal microscope (ISCM) were used to detect connexin 43 (CX43), a molecule related with gap junctional intercellular communication (GJIC). Fluorescence redistribution after photobleaching (FRAP) was used to detect function of GJIC.

RESULTS

A high level of CX43 protein expression was revealed in normal human myoblasts. CX43 protein was mainly localized on the surface of cells and sometimes in cytoplasm. CX43 expression was decreased in RMS cells. Both the detection rates and fluorescent intensity of CX43 decreased when the metastatic potential of RMS increased (P < 0.05). In contrast to normal, the fluorescence recovery rates of the RMS cells decreased and there was a negative correlation between the function of GJIC and malignancy of RMS cell lines (P < 0.05).

CONCLUSION

Varying degrees of GJIC inhibition may correlate with different metastatic potential of RMS. This may help to determine the malignant behavior of RMS and be used as a prognostic index of RMS.

The biology of bilirubin production

Heme oxygenase (HO), the rate-limiting enzyme in bilirubin production, has been identified from the late 1960s. This enzyme has been shown to have many other roles in recent years. The inducible form is regulated by oxidative stress, inflammation, and heavy metals, among others, and is cytoprotective in many instance. Nonetheless, there are instances when HO-1 can be deleterious due to the release of iron from the reaction. Another important by-product, carbon monoxide, is a vasodilator and a neurotransmitter and has been implicated in signal transduction pathways. More recently, nonenzymatic, signaling roles of HO have been suggested. This may serve to regulate the endogenous activity of this enzyme when cellular heme levels are low.

Relationship of large multifunctional proteasome 7 gene polymorphism with susceptibility to type 1 diabetes mellitus and DR3 gene

OBJECTIVE

To study the relationship of the large multifunctional proteasome 7 (LMP7) gene polymorphism with susceptibility to type 1 diabetes mellitus (DM-1) and the DR3 gene in south Chinese Han population.

METHODS

LMP7 genotypes and the DR3 gene were identified in 71 DM-1 patients and 86 healthy persons (as controls) by polymerase chain reaction-restriction fragment length polymorphism. DM-1 patients and controls were divided into DR3-positive and DR3-negative subjects. The frequencies of LMP7 genotypes and alleles were compared between DM-1 patients and controls respectively in the random subjects and in the DR3-matched subjects. Furthermore, DM-1 patients were divided into 3 groups according to the age of diabetic onset: group A < or = 14 years, group B 15-30 years, group C > or = 31 years.

RESULTS

In the random subjects, the frequency of LMP7-B/B was lower (39% vs 58%, P < 0.05) and that of LMP7-B/A was higher (54% vs 31%, P < 0.01) in DM-1 patients than that in controls. In DR3-positive subjects, the frequencies of LMP7 genotypes and alleles showed no differences between DM-1 patients and controls. In DR3-negative subjects, the frequency of LMP7-B/B was decreased (40% vs 61%) and that of LMP7-B/A was increased (55% vs 28%, P < 0.01) in DM-1 patients. The frequencies of LMP7 genotypes and alleles showed no significant differences among different ages of diabetic onset.

CONCLUSIONS

LMP7-B/B may be the protective genotype, and LMP7-B/A may be the susceptible genotype of DM-1, and this may not be affected by the DR3 gene. Persons with LMP7-B/B may have a decreased risk, and those with LMP7-B/A have an increased risk suffering from DM-1. The LMP7 gene may not be associated with the age of diabetic onset.

Protection against tetanus by needle-free inoculation of adenovirus-vectored nasal and epicutaneous vaccines

The effectiveness of vaccination programs would be enhanced greatly through the availability of vaccines that can be administered simply and, preferably, painlessly without the need for timed booster injections. Tetanus is a prime example of a disease that is readily preventable by vaccination but remains a major threat to public health due to the problems associated with administration of the present vaccine. Here we show that a protective immune response against live Clostridium tetani infection in mice can be elicited by an adenovirus vector encoding the tetanus toxin C fragment when administered as a nasal or epicutaneous vaccine. The results suggest that these vaccination modalities would be effective needle-free alternatives. This is the first demonstration that absorption of a small number of vectored vaccines into the skin following topical application of a patch can provide protection against live bacteria in a disease setting.

[Differential expression of cyclins D1, E and A in human breast diseases]

OBJECTIVE

To understand with greater clearness the effect of overexpression of cyclins gene and the potential implications of it for tumorgenesis in breast.

METHODS

We assayed the expression of cyclins D1, E and A in different types of human breast diseases by immunohistochemical staining.

RESULTS

Significant difference was seen among the malignant tumor, benign tumor and dysplasis(P < 0.001). The expressive intensity of above three kind of cyclins in malignant tumor was the highest, that in benign tumor was higher, and that in dysplasis was low.

CONCLUSION

These data suggest that the expressive intensity of cyclins gene may serve as an indicator for malignant intensity of tumors. The expressive ratio difference of cyclins E and A between infiltrating ductal carcinoma and infiltrating lobular carcinoma may imply that there are different mechanisms involving the occurrence of different histological types of breast tumor.

In situ prostate cancer gene therapy using a novel adenoviral vector regulated by the caveolin-1 promoter

Caveolin-1, a structural component of caveolae, is overexpressed in metastatic and androgen-resistant prostate cancer and highly expressed in tumor-associated endothelial cells. The mouse cav-1 promoter was cloned and placed upstream of the HSV-tk gene in an adenoviral vector (Adcav-1tk) and compared with a cytomegalovirus (CMV) or Rous sarcoma virus (RSV) promoter-driven HSV-tk, AdCMVtk and AdRSVtk vectors, respectively. Mouse and human prostate cancer cells and mouse endothelial cells were infected with Adcav-1tk, AdCMVtk or control vectors without the HSV-tk gene (Adcav-1 and AdCMV) and subsequently treated with ganciclovir (GCV). GCV-mediated in vitro cytotoxicity induced by the Adcav-1tk vector was comparable to that for AdCMVtk in multiple mouse and human prostate cancer cell lines. To evaluate the activity of Adcav-1tk in vivo, orthotopic mouse prostate cancer tumors were generated with RM-9 cells and injected in situ with Adcav-1tk, AdCMVtk, AdRSVtk, or AdCMVbetagal (control) and treated with GCV. All three HSV-tk transducing vectors produced statistically significant reductions in wet weight and increased apoptotic indices compared with the control vector. However, only Adcav-1tk produced significant necrosis, and only Adcav-1tk and AdRSVtk caused significant decreases in microvessel density. In conclusion, Adcav-1tk demonstrated efficacy in vitro and in vivo in preclinical models of prostate cancer. Our results suggest that the cav-1 promoter may have unique benefits in targeting gene therapy to prostate cancer and its associated vasculature.

[An experimental study on bone marrow purging in vitro for patients with chronic myelogenous leukemia]

OBJECTIVE

To investigate the effect of IL-2, IFN and bcr-abl AS-ODN on bone marrow purging in vitro for patients with chronic myelogenous leukemia (CML).

METHODS

By amplifying in vitro clone forming culture, and purging the bone marrow of 5 CML patients through different combined use of IL-2, IFN and bcr-abl AS-ODN, we compared the effects of 4 combined regimens.

RESULTS

It was found that the suppressive effects of the 4th regimen combining IL-2 (800 U/ml), IFN (800 u/ml) and bcr-abl AS-ODN (30 micrograms/ml) on leukemia cell clone forming unit (CFU) were significantly different from the suppressive effects of the other 3 regimens (P < 0.01). With the use of the 4th regimen, the GM-CFU and L-CFU survival rates were 26.91% and 3.49% respectively (P < 0.01).

CONCLUSION

The combined regimen of IL-2 (800 U/ml), IFN (800 u/ml) and bcr-abl AS-ODN (30 micrograms/ml) has good effect on selective CML bone marrow purging in vitro and can be used in clinical purging of CML bone marrow.

Histidine 90 function in 4-chlorobenzoyl-coenzyme a dehalogenase catalysis

4-chlorobenzoyl-coenzyme A (4-CBA-CoA) dehalogenase catalyzes the hydrolytic dehalogenation of 4-CBA-CoA by attack of Asp145 on the C4 of the substrate benzoyl ring to form a Meisenheimer intermediate (EMc), followed by expulsion of chloride ion to form an arylated enzyme intermediate (EAr) and, finally, ester hydrolysis in EAr to form 4-hydroxybenzoyl-CoA (4-HBA-CoA). This study examines the contribution of the active site His90 to catalysis of this reaction pathway. The His90 residue was replaced with glutamine by site-directed mutagenesis. X-ray crystallographic analysis of H90Q dehalogenase complexed with 4-HBA-CoA revealed that the positions of the catalytic groups are unchanged from those observed in the structure of the 4-HBA-CoA-wild-type dehalogenase complex. The one exception is the Gln90 side chain, which is rotated away from the position of the His90 side chain. The vacated His90 site is occupied by two water molecules. Kinetic techniques were used to evaluate ligand binding and catalytic turnover rates in the wild-type and H90Q mutant dehalogenases. The rate constants for 4-CBA-CoA (both 7 microM(-1) x s(-1)) and 4-HBA-CoA (33 and 11 microM(-1) x s(-1)) binding to the two dehalogenases are similar in value. For wild-type dehalogenase, the rate constant for a single turnover is 2.3 s(-1) while that for multiple turnovers is 0.7 s(-1). For H90Q dehalogenase, these rate constants are 1.6 x 10(-2) and 2 x 10(-4) s(-1). The rate constants for EMc formation in wild-type and mutant dehalogenase are approximately 200 s(-1) while the rate constants for EAr formation are 40 and 0.3 s(-1), respectively. The rate constant for hydrolysis of EAr in wild-type dehalogenase is 20 s(-1) and in the H90Q mutant, 0.13 s(-1). The 133-fold reduction in the rate of EAr formation in the mutant may be the result of active site hydration, while the 154-fold reduction in the rate EAr hydrolysis may be the result of lost general base catalysis. Substitution of the His90 with Gln also introduces a rate-limiting step which follows catalysis, and may involve renewing the catalytic site through a slow conformational change.

[Phacoemulsification for short eye axis cataract]

OBJECTIVE

To analyze the operative difficulty of cataract phacoemulsification in an eye with shorter axial length and discuss its preventive measures.

METHODS

A retrospective study was performed to analyze the 122 patients (143 eyes) who had undergone cataract phacomulsification. Their ocular axial lengths were 20.21 to 22.10 mm.

RESULTS

Because these patients had shorter ocular axis, shallower anterior chamber depth, narrower space in the anterior ocular segment and higher vitreous pressure, the operation was hard to perform. The rate of posterior capsular rupture was 7.69%. The postoperative inflammatory reaction was severe. The rate of reversible corneal edema (29.37%) was obviously higher than that in cataractous eyes with normal ocular axis (6.7%, P < 0.01), and also higher than that in eyes with normal ocular axis and hard nucleus (12.5%, P < 0.05).

CONCLUSIONS

It is emphasized that the correct technique of incision, application of chopping and breaking nucleus technique, lower energy and higher aspiration for effective phacoemulsification with the help of Viscoat viscoelastic material and maintenance of deep anterior chamber are the key procedures to obtain satisfactory operative results.

Prostate-specific antigen response and systemic T cell activation after in situ gene therapy in prostate cancer patients failing radiotherapy

In an extended phase I/II study we evaluated 36 prostate cancer patients with local recurrence after radiotherapy who received single or repeated cycles of replication-deficient adenoviral vector (ADV)-mediated herpes simplex virus-thymidine kinase (HSV-tk) plus ganciclovir (GCV) in situ gene therapy with respect to serum PSA levels, alterations in immune cells, and numbers of apoptotic cells in needle biopsies. An initial cycle of HSV-tk plus GCV gene therapy caused a significant prolongation of the mean serum PSA-doubling time (PSADT) from 15.9 to 42.5 months (p = 0.0271) and in 28 of the injected patients (77.8%) there was a mean PSA reduction (PSAR) of 28%. It took a mean of 8.5 months for the PSA to return to the initial PSA (TR-PSA) value. A repeated cycle of gene therapy failed to significantly extend PSADT but did result in significant increases in PSAR (29.4%) and TR-PSA (10.5 months). Moderately increased serum adenovirus antibody titers were generally observed 2 weeks after initial vector injection. Also at this time there was a statistically significant increase in the mean percent of CD8(+) T cells positive for the HLA-DR marker of activation in peripheral blood (p = 0.0088). Studies using prostate biopsies obtained at the same time point demonstrated that vector DNA was detectable by PCR in most samples yet all patients remained positive for prostate cancer in at least one biopsy core. Further analysis demonstrated a correlation between the level of CD8(+) cells and the number of apoptotic cells in biopsies containing cancer cells (p = 0.042). We conclude that repeated cycles of in situ HSV-tk plus GCV gene therapy can be administered to prostate cancer patients who failed radiotherapy and have a localized recurrence. Biological responses to this experimental therapy including increases in PSADT, PSAR, and TR-PSA, and activated CD8(+) T cells present in the peripheral blood, were demonstrated. Interestingly, the density of CD8(+) cells in posttreatment biopsies correlated with the number of apoptotic cells.

Kiddo, a new transposable element family closely associated with rice genes

The promoter region of the rice ubiquitin2 (rubq2) gene was found to be polymorphic between japonica (T309) and indica (IR24) lines as the result of a 270-bp deletion in T309. A TTATA footprint in the T309 rubq2 promoter suggested that an excision event had occurred, and inspection of the 270-bp region present in IR24 revealed that it had all the characteristics of a miniature inverted repeat transposable element (MITE). Database searches showed that this element is a member of a new MITE family, which we have named Kiddo. Thirty-five complete Kiddo sequences were identified in existing rice genomic sequence databases. They could be arranged into four groups, within-group sequence identity was over 90%, with 65-75% identity between groups. The high sequence similarity within a group indicates that some Kiddo members were recently mobile and may still be active. An additional 24 decayed Kiddo sequences were detected. Interestingly, approximately 80% of 18 Kiddo members from annotated accessions lie within 530 bp of a coding sequence. That approximately 40% of Kiddo members present in genic regions reside in introns suggests that Kiddo transposition entails the use of both DNA and RNA intermediates, and may provide some insight into the origins of individual groups. DNA blot analysis showed that Kiddo is a rice-specific element, although one sequence with limited (72%) similarity to Kiddo group A was detected as a wheat EST. Kiddo family members may represent new molecular and phylogenetic markers, as well as representing valuable materials for studying the molecular mechanisms of MITE transposition.

Characterization of a Ca2+-dependent protein kinase from rice root: differential response to cold and regulation by abscisic acid

The Ca2+-dependent protein kinases (CDPKs) and abscisic acid (ABA) are known to be involved in low-temperature stress response. The focus of this study was to characterize the 45 kDa protein kinase identified in the crude extract of rice (Oryza sativa L.) seedling roots in response to cold (5 degrees C) stress. The activity of the 45 kDa protein kinase decreased at low temperature as evident by an in-gel kinase assay using histone III-S as a substrate. Also, the Ca2+-dependent activity of this protein kinase was suppressed by cold in the membrane fractions of the root. A general protein kinase inhibitor and Ca2+ chelator inhibited the activity of the 45 kDa protein kinase, suggesting that it was a plant CDPK. The 45 kDa CDPK identified was found to be independent of photosynthetic tissues such as the leaf and leaf sheath of rice seedlings, supporting a direct sensing mechanism in the roots of rice seedlings to cold stress. The suppressed activity of the 45 kDa CDPK was reverted by supplementing with 5 microM ABA under cold stress. The 45 kDa CDPK activity was stronger in the cold-tolerant variety of the 4 types tested than it was in the cold-sensitive one. These results suggest the involvement of endogenous ABA in regulating the activity of the 45 kDa CDPK in response to cold stress.

Population-based, case-control study of blood C-peptide level and breast cancer risk

Insulin resistance has been suggested to be associated with an increased risk of breast cancer. Insulin sensitivity can be measured using blood C-peptide, a marker of insulin secretion. It is thus conceivable that blood C-peptide levels may be associated with breast cancer risk. To evaluate this hypothesis, we analyzed data from a subset (143 case-control pairs matched by age and status of menopause) of women who participated in the Shanghai Breast Cancer Study, a population-based, case-control study conducted in Shanghai during 1996-1998. Fasting blood samples were collected from study subjects to measure C-peptide levels. For cancer patients, the samples were collected before any cancer therapy. Conditional logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals related to C-peptide levels. Breast cancer risk was increased with increasing levels of C-peptide (trend test, P = 0.01), with an odds ratio of 2.7 (95% confidence interval = 1.2-5.9) observed for the highest compared with the lowest tertile of C-peptide concentration after adjusting for body mass index and age at the first live birth. The risk was not altered after fully adjusting for other traditional risk factors for breast cancer. This positive association was observed in both pre and postmenopausal women and regardless of the levels of waist-to-hip ratio or body mass index. The results from this study were consistent with the insulin-resistance hypothesis for breast cancer and suggest that increased levels of C-peptide may contribute to the development of breast cancer.

[Effects of metal ions on gamma-poly (glutamic acid) synthesis by Bacillus licheniformis]

In the course of gamma-poly (glutamic acid) gamma-PGA fermentation, metal ions K+, Mg2+, Fe3+, Ca2+, Mo6+, Mn2+, Co2+ and Zn2+ in the medium have certain effects on the synthesis of gamma-poly(glutamic acid). Excess or lack of K+, Mg2+ and Fe3+ results in reduced yield of gamma-PGA. It was found that the gamma-PGA synthesis by Bacillus licheniformis was promoted obviously by Ca2+ and Mo6+. Synthesis and stereochemical composition of gamma-PGA was greatly regulated by Mn2+. gamma-PGA was not produced without Mn2+ in medium, and with the increase of Zn2+ concentration the yield of gamma-PGA and the proportion of D-glutamic acid in the peptide increase. Regulative effect of Co2+ and Zn2+ was almost the same as that of Mn2+, thus the combination of Mn2+, Co2+ cannot enhance gamma-PGA synthesis and affect stereochemical composition of gamma-PGA. Based on the experimental date, an appropriate formulation of metal ions in the medium for gamma-PGA production was obtained.

The discovery of sulfonylated dipeptides as potent VLA-4 antagonists

Directed screening of a carboxylic acid-containing combinatorial library led to the discovery of potent inhibitors of the integrin VLA-4. Subsequent optimization by solid-phase synthesis afforded a series of sulfonylated dipeptide inhibitors with structural components that when combined in a single hybrid molecule gave a sub-nanomolar inhibitor as a lead for medicinal chemistry. Preliminary metabolic studies led to the discovery of substituted biphenyl derivatives with low picomolar activities. SAR and pharmacokinetic characterization of this series are presented.

2-[N1-2-pyrimidyl-aminobenzenesulfonamido] ethyl 4-bis(2-chloroethyl) aminophenyl butyrate: a potent antitumor agent

2-[N'-2-Pyrimidyl-aminobenzenesulfonamido] ethyl 4-bis(2-chloroethyl) aminophenyl butyrate has been prepared by reaction of chlorambucil with sulfadiazine derivative. Schiffs base has been used as the protective group of the aromatic amine in the synthesis. It can be completely removed by the irradiation of 365 nm UV light at room temperature. The title compound exhibits a high antitumor activity with a therapeutic index (TI) of 47.55 which is twice that of chlorambucil's (TI: 22.84).

Photochemically enhanced binding of small molecules to the tumor necrosis factor receptor-1 inhibits the binding of TNF-alpha

The binding of tumor necrosis factor alpha (TNF-alpha) to the type-1 TNF receptor (TNFRc1) plays an important role in inflammation. Despite the clinical success of biologics (antibodies, soluble receptors) for treating TNF-based autoimmune conditions, no potent small molecule antagonists have been developed. Our screening of chemical libraries revealed that N-alkyl 5-arylidene-2-thioxo-1,3-thiazolidin-4-ones were antagonists of this protein-protein interaction. After chemical optimization, we discovered IW927, which potently disrupted the binding of TNF-alpha to TNFRc1 (IC(50) = 50 nM) and also blocked TNF-stimulated phosphorylation of Ikappa-B in Ramos cells (IC(50) = 600 nM). This compound did not bind detectably to the related cytokine receptors TNFRc2 or CD40, and did not display any cytotoxicity at concentrations as high as 100 microM. Detailed evaluation of this and related molecules revealed that compounds in this class are "photochemically enhanced" inhibitors, in that they bind reversibly to the TNFRc1 with weak affinity (ca. 40-100 microM) and then covalently modify the receptor via a photochemical reaction. We obtained a crystal structure of IV703 (a close analog of IW927) bound to the TNFRc1. This structure clearly revealed that one of the aromatic rings of the inhibitor was covalently linked to the receptor through the main-chain nitrogen of Ala-62, a residue that has already been implicated in the binding of TNF-alpha to the TNFRc1. When combined with the fact that our inhibitors are reversible binders in light-excluded conditions, the results of the crystallography provide the basis for the rational design of nonphotoreactive inhibitors of the TNF-alpha-TNFRc1 interaction.

Evaluation of bacteria isolated from rice for plant growth promotion and biological control of seedling disease of rice

Of 102 rhizoplane and endophytic bacteria isolated from rice roots and stems in California, 37% significantly (P < or = 0.05) inhibited the growth in vitro of two pathogens, Achlya klebsiana and Pythium spinosum, causing seedling disease of rice. Four endophytic strains were highly effective against seedling disease in growth pouch assays, and these were identified as Pseudomonas fluorescens (S3), Pseudomonas tolaasii (S20), Pseudomonas veronii (S21), and Sphingomonas trueperi (S12) by sequencing of amplified 16S rRNA genes. Strains S12, S20, and S21 contained the nitrogen fixation gene, nifD, but only S12 was able to reduce acetylene in pure culture. The four strains significantly enhanced plant growth in the absence of pathogens, as evidenced by increases in plant height and dry weight of inoculated rice seedlings relative to noninoculated rice. Three bacterial strains (S3, S20, and S21) were evaluated in pot bioassays and reduced disease incidence by 50%-73%. Strain S3 was as effective at suppressing disease at the lowest inoculum density (106 CFU/mL) as at higher density (10(8) CFU/mL or undiluted suspension). This study indicates that selected endophytic bacterial strains have potential for control of seedling disease of rice and for plant growth promotion.

An immunophenotypic and molecular study of primary large B-cell lymphoma of bone

Primary non-Hodgkin's lymphomas of bone (PNHLB) is a rare form of extranodal lymphoma. Many studies have reported the clinical, radiologic, and histopathologic characteristics of PNHLB; however, their molecular features have not been well studied. In this report, we present the immunophenotypic and molecular characteristics of 20 primary large B-cell lymphoma (PLBCL) of bone from 20 adults. Most demonstrated centroblastic morphology, with the majority exhibiting nuclear multilobation. One case (5%) demonstrated anaplastic features with strong CD30 expression but was ALK-1 negative. BCL-6 expression was seen in 6 of 20 cases, and strong p53 protein expression was seen in 11 of 20 (55%) cases. The majority of cases analyzed (13/18 = 72%) demonstrated a clonal B-cell process by IgH gene rearrangement studies. Of the five cases that did not demonstrate a clonal population, two expressed BCL-6 protein. No cases demonstrated a bcl-2/JH rearrangement, but BCL-2 protein expression was seen in 11 of 20 (55%) cases. In summary, primary lymphoma of bone is largely a non-Hodgkin's lymphoma of large B-cell type. Our studies demonstrate that p53 and BCL-2 expression may play a role in the pathogenesis of PLCBL of bone. In addition, a subset of the cases are of putative germinal center B-cell origin based on the expression of BCL-6 protein and may be genetically distinct from follicle center lymphomas. The results provide evidence for molecular heterogeneity within primary large B-cell lymphomas of bone.

[Construction of mucosal vaccine derived from HBV surface antigen epitope A and the assay of its immunogenicity]

The fusion gene of HBV(adr) surface antigen epitope and B subunit of Cholera toxin was constructed and expressed successfully in E. coli at high yield. After denaturation-renaturation process, SDS-PAGE analysis showed that most of the renatured product reassociated in a pentameric form which was the same as natural CTB. Western blot analysis indicated that the immunogenicity of HBsAg antigen epitope was conserved. Moreover, ELISA analysis of the sera of orally, intranasally and intraperitoneally immunized mice showed that the circulating IgG antibodies to HBsAg were developed. The results may be helpful for constructing the novel mucosal vaccine with high efficacy.

DNA hypermethylation is a mechanism for loss of expression of the HLA class I genes in human esophageal squamous cell carcinomas

The three human leukocyte antigen (HLA) class I antigens, HLA-A, HLA-B and HLA-C, play important roles in the elimination of transformed cells by cytotoxic T cells. Frequent loss of expression of these antigens at the cell surface has been observed in many human cancers. Various mechanisms for post-transcriptional regulation have been proposed and tested but the molecular mechanisms for transcriptional regulation are not clear. We show by immunohistochemistry that the HLA class I antigens are absent in 26 of 29 (89%) samples of human esophageal squamous cell carcinomas (ESCC). Eleven of the 26 ESCC samples lost mRNA expression for at least one of the HLA genes, as shown by RT-PCR. DNA from the 29 pairs of ESCC and neighboring normal epithelium were examined for CpG island hypermethylation, homozygous deletion, microsatellite instability (MSI) and loss of heterozygosity (LOH). DNA from normal epithelial tissues had no detectable methylation of the CpG islands of any of these gene loci. Thirteen of 29 ESCC samples (45%) exhibited methylation of one or more of the three HLA loci and six samples (21%) exhibited methylation of all three loci. The HLA-B gene locus was most frequently methylated (38%). HLA-B mRNA expression in an ESCC cell line, where HLA-B was hypermethylated and did not express mRNA, was activated after treatment with 5-aza-2'-deoxycytidine. Homozygous deletion of these three gene loci was not observed. Relatively low rates of LOH and MSI were observed for the microsatellite markers D6S306, D6S258, D6S273 and D6S1666, close to the HLA-A, -B and -C loci, although a high ratio of LOH was observed at a nearby locus (represented by the markers D6S1051 and D6S1560), where the tumor suppressor gene p21(Waf1) resides. A strong correlation between genetic alterations and mRNA inactivation was observed in the ESCC samples. Our results indicate that HLA class I gene expression was frequently down-regulated in ESCC at both the protein and mRNA levels and that hypermethylation of the promoter regions of the HLA-A, -B and -C genes is a major mechanism of transcriptional inactivation.

Effect of poly(ADP-ribosyl)ation and Mg2+ ions on chromatin structure revealed by scanning force microscopy

Poly(ADP-ribosyl)ation of nuclear proteins is responsible for major changes in the high-order chromatin structure. The effects of this post-translation modification on nuclear architecture were examined at different Mg2+ concentrations using scanning force microscopy. A quantitative analysis of the internucleosomal distance, the width, and the volume of chromatin fibers imaged in tapping mode reveals that poly(ADP-ribosyl)ation induces a complete relaxation and decondensation of the chromatin structure. Our data, on the center-to-center distance between adjacent nucleosomes and on the fiber width, indicate that the poly(ADP-ribosyl)ated fibers remain significantly decondensed even in the presence of Mg2+. Our results also show that the Mg2+ assumes an important role in the folding of chromatin structure, but Mg2+ is not able to restore the native feature of chromatin, when the fibers are depleted of H1/H5 histones. The combined effect of post-translation modification and cation ions on the chromatin structure shows that poly(ADP-ribosyl)ation could promote accessibility to DNA even in those nuclear processes that require Mg2+.