Structured chaos in a devil's staircase of the Josephson junction

The phase dynamics of Josephson junctions (JJs) under external electromagnetic radiation is studied through numerical simulations. Current-voltage characteristics, Lyapunov exponents, and Poincaré sections are analyzed in detail. It is found that the subharmonic Shapiro steps at certain parameters are separated by structured chaotic windows. By performing a linear regression on the linear part of the data, a fractal dimension of D = 0.868 is obtained, with an uncertainty of ±0.012. The chaotic regions exhibit scaling similarity, and it is shown that the devil's staircase of the system can form a backbone that unifies and explains the highly correlated and structured chaotic behavior. These features suggest a system possessing multiple complete devil's staircases. The onset of chaos for subharmonic steps occurs through the Feigenbaum period doubling scenario. Universality in the sequence of periodic windows is also demonstrated. Finally, the influence of the radiation and JJ parameters on the structured chaos is investigated, and it is concluded that the structured chaos is a stable formation over a wide range of parameter values.

Generation of dendritic cells and macrophages from human induced pluripotent stem cells aiming at cell therapy

This report describes generation of dendritic cells (DCs) and macrophages from human induced pluripotent stem (iPS) cells. iPS cell-derived DC (iPS-DC) exhibited the morphology of typical DC and function of T-cell stimulation and antigen presentation. iPS-DC loaded with cytomegalovirus (CMV) peptide induced vigorous expansion of CMV-specific autologous CD8+ T cells. Macrophages (iPS-MP) with activity of zymosan phagocytosis and C5a-induced chemotaxis were also generated from iPS cells. Genetically modified iPS-MPs were generated by the introduction of expression vectors into undifferentiated iPS cells, isolation of transfectant iPS cell clone and subsequent differentiation. By this procedure, we generated iPS-MP expressing a membrane-bound form of single chain antibody (scFv) specific to amyloid β (Aβ), the causal protein of Alzheimer's disease. The scFv-transfectant iPS-MP exhibited efficient Aβ-specific phagocytosis activity. iPS-MP expressing CD20-specific scFv engulfed and killed BALL-1 B-cell leukemia cells. Anti-BALL-1 effect of iPS-MP in vivo was demonstrated in a xeno-transplantation model using severe combined immunodeficient mice. In addition, we established a xeno-free culture protocol to generate iPS-DC and iPS-MP. Collectively, we demonstrated the possibility of application of iPS-DC and macrophages to cell therapy.

Identification of SARS-COV spike protein-derived and HLA-A2-restricted human CTL epitopes by using a new muramyl dipeptidederivative adjuvant

Severe acute respiratory syndrome (SARS) spread during the winter of 2003, and attempts have been made to develop vaccines against SARS corona virus (SARS-CoV). The present study provides a strategy to rapidly identify SARS-CoV-derived antigenic peptides recognized by HLA-A2-restricted cytotoxic T lymphocytes (CTLs). Forty-three candidate peptides having HLA-A2-binding motifs were selected in silico and HLA-A2/Db chimeric MHC class I-transgenic mice were immunized with these peptides and a new derivative of muramyl dipeptide that can induce upregulation of HLA-DR, CD80, CD86, and CD40 in human CD14+ antigen presenting cells, was administered as an adjuvant. Six HLAA2-restricted mouse CTL epitopes were identified, including two new epitopes which have never been reported before. One of the novel peptides was naturally processed and successfully induced HLAA2-restricted specific CTLs in both HLA transgenic mice and healthy donors. The method was useful, convenient and efficient for rapid identification of CTL epitopes derived from SARS-CoV proteins and will be possibly applicable for other pathogens to develop a peptide-based vaccine.

Growth inhibition efficacy of an adenovirus expressing dual therapeutic genes, wild-type p53, and anti-erbB2 ribozyme, against human bladder cancer cells

The altered expression of both p53 and erbB2 is strongly related to the disease status and the outcome of bladder cancers. We examined the antitumor efficacy by the modulation of these genetic alterations with a newly designed dual-gene-expressing adenovirus (Ad-p53/erbB2Rz), which expresses p53 and anti-erbB2 ribozyme simultaneously in human bladder cancer cells. Cell growth inhibition efficacy along with biological responses of this virus was compared with other viral vectors (Ad-p53, which expresses wild-type p53 cDNA, and Ad-erbB2Rz, which expresses anti-erbB2 ribozyme, solely or in combination). Sufficient transgene expression in targeted cells and the altered expression of the targeted genes and their encoded proteins were obtained by each therapeutic vector. Each of the three therapeutic viral vectors inhibited bladder cancer cell growth, and the putative additive antitumor effect was shown by the combination of two of the therapeutic vectors. Furthermore, Ad-p53/erbB2Rz had superior therapeutic efficacy when the same titers of viruses were infected. Nonspecific vector-related toxicity was minimized by reducing the total amount of viral titers by using the dual-gene-expressing adenovirus. Modulation of multiple genetic abnormalities might enhance the therapeutic efficacy, and vector-related toxicity could be minimized when the total amount of viral titers are reduced.

Hammerhead ribozymes as therapeutic agents for bladder cancer

Hammerhead ribozymes have been investigated extensively as therapeutic agents against cancer. Aberrant or overexpression of genes related to tumorigenicity or cancer growth might be the appropriate targets for ribozyme strategies. Ribozyme-mediated gene therapy should be applied to those diseases that have no successful conventional therapy such as advanced or treatment-resistant bladder cancer. Many genetic alterations have been identified in bladder cancer related to both tumorigenesis and disease progression. Mutated H-ras, fos, and erb-B2 genes have been chosen as targets for ribozymes in previous studies, and antitumor efficacy has been demonstrated by reversion of the malignant phenotypes and by inhibition of tumor growth both in vitro and in vivo. The efficiency of various delivery systems has also been evaluated. An overview of ribozyme strategies, especially for therapeutic applications against bladder cancer, is described here.

Feasibility and assessment of non-invasive in vivo redox status using electron paramagnetic resonance imaging

PURPOSE

To test the feasibility of electron paramagnetic resonance imaging (EPRI) to provide non-invasive images of tissue redox status using redox-sensitive paramagnetic contrast agents.

MATERIAL AND METHODS

Nitroxide free radicals were used as paramagnetic agents and a custom-built 300 MHz EPR spectrometer/imager was used for all studies. A phantom was constructed consisting of four tubes containing equal concentrations of a nitroxide. Varying concentrations of hypoxanthine/xanthine oxidase were added to each tube and reduction of the nitroxide was monitored by EPR as a function of time. Tumor-bearing mice were intravenously infused with a nitroxide and the corresponding reduction rate was monitored on a pixel-by-pixel basis using 2D EPR of the tumor-bearing leg and normal leg serving as control. For animal studies, nitroxides were injected intravenously (1.25 mmol/kg) and EPR projections were collected every 3 min after injection using a magnetic field gradient of 2.5 G/cm. The reduction rates of signal intensity on a pixel-by-pixel basis were calculated and plotted as a redox map. Redox maps were also collected from the mice treated with diethylmaleate (DEM), which depletes tissue thiols and alters the global redox status.

RESULTS

Redox maps obtained from the phantoms were in agreement with the intensity change in each of the tubes where the signals were decreasing as a function of the enzymatic activity, validating the ability of EPRI to accurately access changes in nitroxide reduction. Redox imaging capability of EPR was next evaluated in vivo. EPR images of the nitroxide distribution and reduction rates in tumor-bearing leg of mice exhibited more heterogeneity than in the normal tissue. Reduction rates were found to be significantly decreased in tumors of mice treated with DEM, consistent with the depletion of thiols and the consequent alteration of the redox status.

CONCLUSION

Using redox-sensitive paramagnetic contrast agents, EPRI can non-invasively discriminate redox status differences between normal tissue and tumors.

Feasibility and assessment of non-invasive in vivo redox status using electron paramagnetic resonance imaging

PURPOSE

To test the feasibility of electron paramagnetic resonance imaging (EPRI) to provide non-invasive images of tissue redox status using redox-sensitive paramagnetic contrast agents.

MATERIAL AND METHODS

Nitroxide free radicals were used as paramagnetic agents and a custom-built 300 MHz EPR spectrometer/imager was used for all studies. A phantom was constructed consisting of four tubes containing equal concentrations of a nitroxide. Varying concentrations of hypoxanthine/xanthine oxidase were added to each tube and reduction of the nitroxide was monitored by EPR as a function of time. Tumor-bearing mice were intravenously infused with a nitroxide and the corresponding reduction rate was monitored on a pixel-by-pixel basis using 2D EPR of the tumor-bearing leg and normal leg serving as control. For animal studies, nitroxides were injected intravenously (1.25 mmol/kg) and EPR projections were collected every 3 min after injection using a magnetic field gradient of 2.5 G/cm. The reduction rates of signal intensity on a pixel-by-pixel basis were calculated and plotted as a redox map. Redox maps were also collected from the mice treated with diethylmaleate (DEM), which depletes tissue thiols and alters the global redox status.

RESULTS

Redox maps obtained from the phantoms were in agreement with the intensity change in each of the tubes where the signals were decreasing as a function of the enzymatic activity, validating the ability of EPRI to accurately access changes in nitroxide reduction. Redox imaging capability of EPR was next evaluated in vivo. EPR images of the nitroxide distribution and reduction rates in tumor-bearing leg of mice exhibited more heterogeneity than in the normal tissue. Reduction rates were found to be significantly decreased in tumors of mice treated with DEM, consistent with the depletion of thiols and the consequent alteration of the redox status.

CONCLUSION

Using redox-sensitive paramagnetic contrast agents, EPRI can non-invasively discriminate redox status differences between normal tissue and tumors.

Malignant adenomyoepithelioma of the breast with lung metastases: report of a case

Adenomyoepithelioma of the breast is a rare lesion, and has a bicellular pattern of epithelial and myoepithelial cells which are regularly distributed in the tubular structures based on the histologic and ultrastructural features. It is thought to be a benign or a low-grade malignant disease. We herein describe a case of malignant adenomyoepithelioma of the breast with lung metastases in an 86-year-old woman. A primary massive tumor in the left breast grew rapidly within a short period of time. A simple mastectomy with sampling of the axillary lymph nodes was performed. The obtained lymph nodes did not include any metastatic lesions. Malignancy was evidenced by the presence of a high mitotic rate and severe nuclear atypia. Three months after the operation, radiology showed multiple lung metastases, and the patient died 2 weeks thereafter. Reviewing the literature, nine similar cases were reported, and the prognosis of malignant adenomyoepithelioma of the breast with distant metastases was very poor with the time of recurrence varying after initial treatments. Malignant adenomyoepithelioma should be followed up with careful screening for distant metastases.

p53 Mutation in bladder cancer patients in Japan and inhibition of growth by in vitro adenovirus-mediated wild-type p53 transduction in bladder cancer cells

BACKGROUND

Altered expression of p53 has been described in nearly half of bladder cancers, and p53 mutations are presumed to play a role in the multistep progression of these tumors.

MATERIALS AND METHODS

The incidence of mutation in the p53 gene and its correlation with histopathologic findings and patient survival were evaluated in 105 Japanese patients with bladder cancer. Laboratory experiments were also performed to confirm the infectivity and efficacy in tumor growth inhibition of an adenovirus expressing wild-type p53 in EJ bladder cancer cells.

RESULTS

Mutations of p53 were observed in 38 bladder cancer specimens (36%), with a significantly higher incidence of mutation being seen in tumors of higher stage and grade. The overall survival was worse in patients with the p53 mutation. In laboratory experiments, adenoviral vectors infected bladder cancer cells in a dose- and cell density-dependent manner. The adenovirus-mediated transduction of wild-type p53 resulted in dose-dependent growth inhibition of bladder cancer cells in vitro. No significant cytotoxicity was observed after infection by a control adenovirus.

CONCLUSION

Transduction of wild-type p53 might be a potential therapeutic option for bladder cancer.

Antitumor effect of bcl-2 antisense phosphorothioate oligodeoxynucleotides on human renal-cell carcinoma cells in vitro and in mice

BACKGROUND AND PURPOSE

Programmed cell death is a genetically regulated pathway that is altered in many cancers. This process is, in part, regulated by the bcl-2 oncogene. Antisense oligodeoxynucleotides (ODNs) targeted to specific oncogenes have been used with some therapeutic success in animal models of leukemia and melanoma cells and human Hodgkin's lymphoma. We evaluated the effects of antisense ODNs targeted to the bcl-2 oncogene on the proliferation of human renal-cell carcinoma (RCC) cells in vitro and on the growth of human RCC xenografts in BALBc nude (nu/nu) mice.

MATERIALS AND METHODS

Expression bcl-2 mRNA in five RCC cell lines (ACHN, Caki-1, RCZ, RCW, and OS-RC-2) was analyzed by reverse transcriptase-polymerase chain reaction. The effects of phosphorothioated ODNs containing human bcl-2 sense and bcl-2 antisense sequences that were transfected with Lipofectin on the proliferation and viability of cultures of established human RCC cell lines were determined by MTS assay. The expression of Bcl-2 protein in ACHN tumor cells following antisense bcl-2 (AS2) ODN treatment was evaluated by Western blot analysis, and the extent of apoptosis in these cells was determined by fluorescence-activated cell sorter (FACS) analysis. The antitumor activity in ACHN xenografts in nu/nu mice was monitored by measuring differences in tumor weight in treated and control mice.

RESULTS

Expression of bcl-2 mRNA was detected in all five RCC lines. Treatment with antisense bcl-2 ODNs inhibited the growth of all tested RCC cells and decreased Bcl-2 protein expression in ACHN cells. The AS2 antisense ODN complementary to the coding region of bcl-2 mRNA showed a superior antiproliferative effect compared with AS1 ODN complementary to the translation initiation region. Inhibition by antisense bcl-2 ODNs of ACHN cells was dose dependent. The FACS analysis revealed that growth inhibition was associated with the induction of programmed cell death. In vivo, AS2 ODN antitumor activity was noted in locally injected groups.

CONCLUSIONS

Treatment of human RCC with antisense ODNs targeted to bcl-2 inhibits growth and is associated with the induction of programmed cell death. These results suggest therapeutic use of antisense bcl2 in the treatment of RCC.

Comparative evaluation of 99mTc-MIBI and 99mTc-HMDP scintimammography for the diagnosis of breast cancer and its axillary metastases

The purpose of the present study was to compare scintimammography using technetium-99m hexakis 2-methoxyisobutylisonitrile (MIBI) with that using 99mTc-hydroxymethylene diphosphonate (HMDP) in the detection of breast cancer and its axillary lesions. The study population comprised 50 consecutive females with breast cancer who were scheduled for surgery. All patients underwent scintimammography with 99mTc-MIBI and 99mTc-HMDP. The images were acquired 5 min (early) and 2 h (delayed) after injection of each radiopharmaceutical. Regions of interest were placed over the breast tumour (T), the axillary lesion (A) and the normal ipsilateral breast tissue (N). The two count ratios were calculated, i.e. the tumour to normal breast tissue ratio (T/N) and the axillary lymph node to normal breast tissue ratio (A/N). For the breast tumours, using 99mTc-MIBI the positive rate was 86% (43/50) for the early and 72% (36/50) for the delayed images. The corresponding values using 99mTc-HMDP were 72% (36/50) and 40% (20/50), respectively. Histopathological examination revealed metastatic lymph node involvement in 22 patients. For the axillary lesions, using 99mTc-MIBI the positive rate was 72.7% (16/22) for the early and 54.5% (12/22) for the delayed images. Using 99mTc-HMDP, the positive rate was only 18.2% (4/22) for the early and 4.5% (1/22) for the delayed images. Using 99mTc-MIBI, the mean T/N (+/- SD) ratios on early and delayed images were 2.69 +/- 1.64 and 2.03 +/- 1.16, respectively, and the mean A/N (+/- SD) ratios on early and delayed images were 2.20 +/- 1.23 and 1.80 +/- 1.20, respectively. The corresponding values using 99mTc-HMDP were 1.77 +/- 0.91, 1.42 +/- 0.72, 1.27 +/- 0.63 and 1.08 +/- 0.25, respectively. The T/N and A/N ratios on the early and delayed 99mTc-MIBI images were both significantly higher than those obtained using 99mTc-HMDP. 99mTc-MIBI scintimammography is more sensitive than 99mTc-HMDP scintimammography for the detection of breast cancer and its axillary lymph node metastases.

Amino acid residues in the alpha IIb subunit that are critical for ligand binding to integrin alpha IIbbeta 3 are clustered in the beta-propeller model

Several distinct regions of the integrin alpha(IIb) subunit have been implicated in ligand binding. To localize the ligand binding sites in alpha(IIb), we swapped all 27 predicted loops with the corresponding sequences of alpha(4) or alpha(5). 19 of the 27 swapping mutations had no effect on binding to both fibrinogen and ligand-mimetic antibodies (e.g. LJ-CP3), suggesting that these regions do not contain major ligand binding sites. In contrast, swapping the remaining 8 predicted loops completely blocked ligand binding. Ala scanning mutagenesis of these critical predicted loops identified more than 30 discontinuous residues in repeats 2-4 and at the boundary between repeats 4 and 5 as critical for ligand binding. Interestingly, these residues are clustered in the predicted beta-propeller model, consistent with this model. Most of the critical residues are located at the edge of the upper face of the propeller, and several critical residues are located on the side of the propeller domain. None of the predicted loops in repeats 1, 6, and 7, and none of the four putative Ca(2+)-binding predicted loops on the lower surface of the beta-propeller were important for ligand binding. The results map an important ligand binding interface at the edge of the top and on the side of the beta-propeller toroid, centering on repeat 3.

Toxicity and health-related quality of life during and after high dose rate brachytherapy followed by external beam radiotherapy for prostate cancer

BACKGROUND

The optimal protocol for combining high dose rate brachytherapy and external beam irradiation as treatment for localized prostate cancer is unknown. Toxicity rates and clinical and biochemical outcomes should be evaluated to validate the current treatment protocol.

METHODS

Fifty-eight patients were treated for prostate cancer with high dose rate brachytherapy followed by 30 Gy of external beam radiation therapy. Toxicity during treatment and for 12-18 months thereafter, and treatment-related morbidity, were evaluated. Physician-assessed treatment-related toxicity was graded at the time of occurrence using the Radiation Therapy Oncology Group morbidity criteria. Four separate self-administered questionnaires were used to collect longitudinally demographic data and general and prostate disease-related measures of quality of life.

RESULTS

Various degrees of rectal bleeding due to radiation proctitis were experienced by 13 patients (22%) at a median time of 11 months. Two of these patients needed hospitalization to undergo laser coagulation of the rectal mucosa. Study patients had statistically significant decreases in five SF-36 domains during the first month of treatment. All measures recovered by 12 months. Sexual function was not affected by irradiation. Lower urinary tract symptoms assessed by IPSS/QOL scores worsened significantly during the first month of treatment but later recovered to baseline levels. Physician-assessed RTOG scores failed to detect these changes.

CONCLUSIONS

Morbidity associated with combined radiation therapy was greatest during the first month of treatment and affected quality of life significantly. Most measures recovered to baseline levels by 12 months following radiation therapy. Although the current protocol appears acceptable, measures should be taken to decrease treatment-related morbidity further.

Retroperitoneoscopic radical nephrectomy by the posterior lumber approach for renal-cell carcinoma associated with chronic renal failure

PURPOSE

To evaluate the efficacy and invasiveness of retroperitoneoscopic radical nephrectomy for renal-cell carcinoma (RCC) in patients with chronic renal failure (CRF), a group known to have relatively high surgical risk.

PATIENTS AND METHODS

Between May 1996 and September 1999, six CRF patients maintained on hemodialysis underwent retroperitoneoscopic radical nephrectomy for clinically localized RCC by the posterior lumber approach. The excised kidneys were evacuated via a posterior skin incision (5 cm) between two port sites; the muscle layers were not incised.

RESULTS

The procedure was completed in all patients with no major complications. The mean operative time was 162 (range 135-210) minutes, and the estimated blood loss was 58 (15-100) mL; none of the patients required a blood transfusion. Regular hemodialysis was restarted on postoperative day 2 or 3.

CONCLUSIONS

This procedure seems to be minimally invasive and suitable for the treatment of small RCC in atrophic kidneys, especially in patients with CRF.

Spontaneous rupture of a parathyroid adenoma presenting as a massive cervical hemorrhage: report of a case

We report an unusual case of spontaneous rupture of a parathyroid adenoma causing cervical hemorrhage. A 60-year-old woman presented to our hospital after the sudden development of extensive ecchymosis of her neck and upper anterior chest wall. Computed tomography (CT) scanning revealed a hematoma in the left retrotracheal space, and laboratory examinations revealed significant hypercalcemia, hypophosphatemia, and a high level of intact parathyroid hormone. Primary hyperparathyroidism was diagnosed, but it was not until the hematoma had subsided, 4 months after her initial presentation, that a parathyroid adenoma was revealed by CT. An operation was performed, and a parathyroid adenoma with hemosiderin deposition was histologically diagnosed. Although this phenomenon is unusual, all endocrine surgeons should be well aware of the possibility of its occurrence.

Application of the membrane filter technique to bromodeoxyuridine immunochemistry for exfoliative cytology

The membrane filter technique for smear specimens of tumors in bromodeoxyuridine (BrdU) immunochemistry is described. The staining results of Raji cells processed using the filter technique was compared with that obtained by the conventional cytospin method. Although the BrdU mean labeling index (LI) for in cytospin specimens was almost the same as the LI in membrane filter specimens, filter specimens showed excellent staining and less cell destruction compared with those processed by cytospin. Small amounts of tumor specimens such as squamous cell carcinoma and polymorphous low-grade adenocarcinoma also were processed using the membrane filter appliance. For squamous cell carcinoma, the LI for the filter specimens was 5.36+/-0.38 and that of the paraffin sections was 5.56+/-0.38. The membrane filter technique provided relatively undamaged specimens for exfoliative cytology and will be useful for immunohistochemical evaluation of tumor cells and for routine, noninvasive cytological screening.

Differences between T-cell reactivities to major myelin protein-derived peptides in opticospinal and conventional forms of multiple sclerosis and healthy controls

In Japanese, susceptibility to the conventional form of multiple sclerosis (C-MS) is associated with the HLA-DRB1*1501-DRB5*0101 haplotype while susceptibility to the opticospinal form of MS (OS-MS) is associated with HLA-DPA1*0202-DPB1*0501. To clarify the characteristics of T cells autoreactive to myelin proteins in each MS subtype, we established T-cell lines reactive to such myelin antigens as myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) from 5 of 10 OS-MS patients, 6 of 11 C-MS patients and 7 of 13 healthy controls (HCs), and T-cell epitopes and their restriction molecules were determined. We found that (a) intermolecular epitope spreading was found to be significantly more frequent in MS patients than in HCs (P=0.0128), (b) intramolecular epitope spreading also tended to occur more frequently in MS patients than in HCs (P=0.0584), (c) in OS-MS, HLA-DR-restricted and MOG-autoreactive T cells were more frequently established as compared with those reactive to MBP or PLP epitopes and (d) in C-MS, HLA-DQ-restricted and PLP-autoreactive T cells dominated those autoreactive to MBP or MOG epitopes. A DPB1*0501-restricted MBP-reactive T-cell clone from a patient with OS-MS provided evidence that the first HLA class II anchor amino acid of peptide bound to disease-susceptible DP5 molecule was distinct from that for the DR2 molecule. Taken together, these differences in specificities of myelin-autoreactive T cells between C-MS and OS-MS as well as the difference in the anchor motif of the binding peptides between each MS subtype-susceptible HLA class II molecule may contribute to the development of distinct clinical phenotypes.

Bilateral pneumothorax with extensive subcutaneous emphysema manifested during third molar surgery. A case report

This report describes a case of bilateral pneumothorax with extensive subcutaneous emphysema in a 45-year-old man that occurred during surgery to extract the left lower third molar, performed with the use of an air turbine dental handpiece. Computed tomographic scanning showed severe subcutaneous emphysema extending bilaterally from the cervicofacial region and the deep anatomic spaces (including the pterygomandibular, parapharyngeal, retropharyngeal, and deep temporal spaces) to the anterior wall of the chest. Furthermore, bilateral pneumothorax and pneumomediastinum were present. In our patient, air dissection was probably caused by pressurized air being forced through the operating site into the surrounding connective tissue.

The role of alpha and beta chains in ligand recognition by beta 7 integrins

Integrins alpha(E)beta(7) and alpha(4)beta(7) are involved in localization of leukocytes at mucosal sites. Although both alpha(E)beta(7) and alpha(4)beta(7) utilize the beta(7) chain, they have distinct binding specificities for E-cadherin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1), respectively. We found that mutation of the metal ion-dependent adhesion site (MIDAS) in the alpha(E) A-domain (D190A) abolished E-cadherin binding, as did mutation F298A on the A-domain surface near the MIDAS cleft. A docking model of the A-domain with E-cadherin domain 1 indicates that coordination of the alpha(E) MIDAS metal ion by E-cadherin Glu(31) and a novel projection of Phe(298) into a hydrophobic pocket on E-cadherin provide the basis for the interaction. The location of the binding site on the alpha(E) A-domain resembles that on other integrins, but its structure appears distinctive and particularly adapted to recognize the tip of E-cadherin, a unique integrin ligand. Additionally, mutation of the beta(7) MIDAS motif (D140A) abolished alpha(E)beta(7) binding to E-cadherin and alpha(4)beta(7)-mediated adhesion to MAdCAM-1, and alpha(4) chain mutations that abrogated binding of alpha(4)beta(1) to vascular cell adhesion molecule-1 and fibronectin similarly reduced alpha(4)beta(7) interaction with MAdCAM-1. Thus, although specificity can be determined by the integrin alpha or beta chain, common structural features of both subunits are required for recognition of dissimilar ligands.

Adenovirus-mediated ribozyme targeting of HER-2/neu inhibits in vivo growth of breast cancer cells

HER-2/neu is overexpressed in 25-30% of human breast cancers. We prepared an anti-HER-2/neu hammerhead ribozyme expressed by a recombinant adenovirus (rAdHER-Rz). Human breast cancer cell lines were transduced with high efficiency, resulting in decreased HER-2/neu expression. In vivo injections of rAdHER-Rz into BT-474 tumors established in nude mice inhibited tumor growth to 20% of mock-treated controls. Similar in vivo effects were shown in MCF-7 cells, which do not overexpress HER-2/neu. The growth inhibitory effects of rAdHER-Rz were greater than those of an antisense-expressing vector. These results suggest the utility of anti-HER-2/neu ribozymes as a rational strategy for gene therapy of breast cancer. Gene Therapy (2000) 7, 241-248.

The crystal structure of calcium-free human m-calpain suggests an electrostatic switch mechanism for activation by calcium

Calpains (calcium-dependent cytoplasmic cysteine proteinases) are implicated in processes such as cytoskeleton remodeling and signal transduction. The 2.3-A crystal structure of full-length heterodimeric [80-kDa (dI-dIV) + 30-kDa (dV+dVI)] human m-calpain crystallized in the absence of calcium reveals an oval disc-like shape, with the papain-like catalytic domain dII and the two calmodulin-like domains dIV+dVI occupying opposite poles, and the tumor necrosis factor alpha-like beta-sandwich domain dIII and the N-terminal segments dI+dV located between. Compared with papain, the two subdomains dIIa+dIIb of the catalytic unit are rotated against one another by 50 degrees, disrupting the active site and the substrate binding site, explaining the inactivity of calpains in the absence of calcium. Calcium binding to an extremely negatively charged loop of domain dIII (an electrostatic switch) could release the adjacent barrel-like subdomain dIIb to move toward the helical subdomain dIIa, allowing formation of a functional catalytic center. This switch loop could also mediate membrane binding, thereby explaining calpains' strongly reduced calcium requirements in vivo. The activity status at the catalytic center might be further modulated by calcium binding to the calmodulin domains via the N-terminal linkers.

Ganglioside GT1b in rat brain binds to p58, a brain-specific sodium-dependent inorganic phosphate cotransporter: expression cloning with a specific monoclonal antibody to ganglioside GT1b-binding protein

To evidence the notion that gangliosides involve neuronal cell interactions in the brain, we surveyed the presence of ganglioside-binding proteins in membrane lysates of adult rat cerebellum. Three proteins (p58, p90, and p160) were identified as GT1b-binding proteins by incubation of the blot of the membrane lysate with GT1b micelles. We generated a monoclonal antibody (mAb) specific to the polypeptide portion of the GT1b-binding proteins (YAK-2). The YAK-2 mAb specifically reacted with all three proteins on blots of proteins pretreated under nonreducing conditions for SDS-PAGE, but reacted mainly with p58 under reducing conditions, showing that p90 and p160 are oligomeric forms of p58. The binding activity of the YAK-2 mAb was completely inhibited by the presence of GT1b micelles, indicating the specificity of YAK-2 mAb for p58 and its oligomers. Immunohistochemical investigations revealed that both p58 and GT1b colocalize within the granular layer of adult rat cerebellum. Expression cloning of p58 cDNA was performed using YAK-2 mAb, and five putative clones were obtained. Among them, the nucleotide sequence of one cDNA completely matched that of rat brain-specific sodium-dependent inorganic phosphate cotransporter (rBNPI), a 61 kDa membrane protein. COS7 cells were transfected with a Flag-chimeric construct containing the rBNPI/p58 cDNA, and the membrane lysate was subjected to immunoprecipitation with anti-Flag antibody. One protein (64 kDa) was detected only with YAK-2 mAb, and the membrane lysate specifically bound to GT1b micelles. Taking together, we propose that rBNPI/p58 functions as a GT1b-binding protein in neuronal cells.

Alpha 3 beta 1 adhesion to laminin-5 and invasin: critical and differential role of integrin residues clustered at the boundary between alpha 3 N-terminal repeats 2 and 3

Integrin/ligand interaction is a therapeutic target for many diseases. We previously reported that residues critical for ligand binding are clustered in N-terminal repeat 3 (in the predicted 2-3 loop) of alpha 4, alpha 5 and alpha IIb. Here we have localized residues critical for ligand binding in the alpha 3 subunit of integrin alpha 3 beta 1 with distinct ligand specificity (laminin-5). We identified an alpha 3 epitope common to several function-blocking anti-alpha 3 antibodies at the boundary between repeats 1 and 2 (residues 75-80). We found that swapping the predicted 4-1 loop (residues 153-165) at the boundary between repeats 2 and 3 with the corresponding alpha 4 sequence and mutating Thr-162 and Gly-163 residues in this predicted loop block laminin-5 binding. Thr-162 and Gly-163 and the antibody epitope are separated in the primary structure; however, they are close to each other in the proposed beta-propeller model. Mutating residues recently reported to block (Tyr-186 and Trp-188) or enhance (Asp-122) laminin-5 binding to alpha 3 beta 1 [Krukonis, E. S., Dersch, P., Eble, J. A., and Isberg, R. R.(1998) J. Biol. Chem. 273, 31837-31843] did not affect laminin-5 binding under the assay conditions used. Thr-162 and Gly-163 are not critical for adhesion to invasin, indicating that laminin-5 and invasin may use different recognition mechanisms, and that mutation of Thr-162 and Gly-163 does not drastically affect the integrity of alpha 3 beta 1. These results suggest that residues critical for ligand binding may be similarly (but not identically) located in repeat 3 of the alpha subunit regardless of ligand specificity.

Augmentation of immune response by altered peptide ligands of the antigenic peptide in a human CD4+ T-cell clone reacting to TEL/AML1 fusion protein

The 12;21 chromosomal translocation occurs in leukemic cells from 20(30% of patients with B-lineage childhood acute lymphoblastic leukemia, the result being the TEL/AML1 fusion gene carrying a sequence different from TEL or AML1. Because the protein newly formed by TEL/ AML1 fusion is probably not tolerated by human immune system, the fusion region is a good candidate for tumor antigen expressed only in TEL/ AML1-positive leukemic cells. We established two human CD4+ alphabeta T-cell clones (T31.1 and Y41.2) reacting to the TEL/AML1 fusion region, from two unrelated healthy donors. In order to do this, we stimulated peripheral blood mononuclear cells with synthetic peptides corresponding to the TEL/ AML1 fusion region. Both T31.1 and Y41.2 proliferated in response to TEL/ AML1 fusion protein as well as to a peptide IGRIAECILGMNPSR, in the context of HLA-DP5 and DP17, respectively, and killed B lymphoblastoid cells pulsed with the peptide. Furthermore, these T-cell clones proliferated in response to several altered peptide ligands carrying a single residue substitution in the TEL/AML1 peptide, and some induced augmentation of proliferation and production of Th1-type cytokines. These superagonistic altered peptide ligands can be given consideration for anti-leukemic immunotherapy.

Therapeutic efficacy of an adenovirus-mediated anti-H-ras ribozyme in experimental bladder cancer

Ras oncogenes are thought to play a critical role in cellular proliferation and tumorigenesis. Reversal of the malignant phenotype, inhibition of tumor growth, and decreased tumorgenicity have been demonstrated with the use of anti-H-ras ribozymes. In this study, the therapeutic efficacy of a hammerhead ribozyme targeting the mutated H-ras oncogene was investigated in an experimental bladder cancer model using a recombinant adenovirus as delivery vehicle. Tumors were established in nude mice by subcutaneous injection of EJ human bladder carcinoma cells harboring a point mutation of the H-ras gene. The tumors were treated with intralesional injections of an adenovirus expressing an anti-H-ras ribozyme (rAd-Hras Rz) by different schedules at serial titers, and the tumor inhibition efficacy was analyzed. The viral infection efficacy and kinetics of ribozyme expression were also evaluated. Intralesional injection of rAd-Hras Rz resulted in significant antineoplastic effects in a dose-dependent fashion. Complete regression of the tumor was achieved by rAd-Hras Rz in several cases without recurrence during the 50-day observation period. Although there was moderate vector-associated cytotoxicity in this cell line, complete regressions were not observed in the cases treated with control adenovirus vectors or vectors expressing an inactive anti-H-ras ribozyme or anti-H-ras antisense oligonucleotides. These results suggest the efficacy of a ribozyme-encoding adenovirus in the experimental gene therapy of human bladder cancer.

[Elevation of serum and urine tumor necrosis factor levels after transurethral resection of the prostate]

BACKGROUND

Recent studies have suggested that inflammatory cytokines are major mediator of the acute phase protein response after surgery. The aim of the present study is to investigate the relationship between the degree of surgical trauma and the change of serum and urine cytokine levels after transurethral resection of the prostate (TUR-P).

METHOD

Serum and urine concentrations of tumor necrosis factor-alpha (TNF), interleukin-6 (IL 6), and interleukin-1 (IL 1) were evaluated in 55 patients who underwent TUR-P and in 23 patients who underwent abdominal surgery. The samples were collected periodically before and after an intervention, and the concentrations of cytokines were measured by enzyme-linked immunosorbent assay.

RESULTS

The concentration of serum TNF was significantly increased 6 hours after TUR-P. Since serum TNF level was not increased after abdominal surgery, serum TNF level was significantly higher after TUR-P than after abdominal surgery. Serum IL 6 and IL 1 levels were not increased after TUR-P. Urine levels of TNF, IL 6 and IL 1 were significantly increased after TUR-P, meanwhile no significant elevation of urine cytokine levels was recognized in the patients who underwent abdominal surgery. The elevation of urine cytokine levels was thought to be caused by the increased production of cytokines at the surgically resected sites. The urine TNF level after TUR-P was increased related to the resected tissue volume and irrigation fluid volume. The preoperative urinary tract infection caused excessive elevation of the urine TNF level after TUR-P. The urine TNF level after TUR-P also tended to be increased depending on the degree of postoperative pyrexia.

CONCLUSION

These results indicate the unique response of TNF to TUR-P. Measurement of serum and urine TNF levels after TUR-P can be a useful index for evaluating the perioperative condition of the patients undergoing TUR-P.

BRCA1 gene mutation and loss of heterozygosity on chromosome 17q21 in primary prostate cancer

The tumor suppressor gene BRCA1 on chromosome 17q21 has been characterized and shown to be mutated in patients with familial breast and ovarian cancer. Several studies examined the relatives of women with breast cancer and noted an association with ovarian and prostate cancer. This study investigated 24 human prostate cancer specimens for BRCA1 gene mutations and loss of heterozygosity (LOH) on chromosome 17q21 assessed by the polymerase chain reaction. LOH was identified using 7 highly polymorphic tandem repeat markers on chromosome 17q21, in addition to an analysis of the whole coding region of the BRCA1 gene. Four of the 24 prostate cancer specimens showed LOH at one or more loci, all of which were histologically poorly differentiated (4 of 11) and stage D (4 of 15). One of the 24 cases showed a germ-line mutation of the BRCA1 gene, and a sister of this patient died of ovarian cancer. It appears that the BRCA1 gene is not frequently involved in the development of primary prostate cancer.

New antibacterial diterpenoids from the Sarcodon scabrosus fungus

The structures of new antibacterial diterpenoids that had been isolated from Sarcodon scabrosus were established by chemical and spectral means to be sarcodonin L (2) and M (3), both having the cyathane skeleton. Other antibacterial compounds were identified to be allocyathin B2 (1), sarcodonin G (4) and sarcodonin A (5) by comparing their spectral data with those of authentic samples.

[Mutation of p53 gene and genomic instability in testicular tumors]

BACKGROUND

During the past decade, studies of human cancer have begun to yield molecular information on the identify of the multiple genetic changes in the development and progression of tumorigenesis. We investigated alterations of p53 and genomic instability in testicular tumors.

MATERIALS AND METHODS

Polymerase chain reaction (PCR) single-strand conformation polymorphism was performed for analysis from exons 5 to 8 of p53 gene in 22 cases and PCR-microsatellite instability analysis using 8 microsatellite markers were conducted in 19 cases of testicular tumor.

RESULTS

No mutations were noted for exons 5 to 8 of the p53 gene. Differences in unrelated microsatellites for tumor and corresponding normal DNA were detected in 5 of 19 (26.3%) cases examined. Alterations noted in more than 2 microsatellites were observed in 3 of 19 (15.8%) and categorized as replication error (RER) phenotype. Two of 7 (28.6%) seminomatous and 1 of 12 (8.3%) non-seminomatous testicular tumors patients showed RER. Two of 16 (12.5%) stage T1-3N0M0 and 1 of 3 (33.3%) stage T1-3N1-3M0-1 showed RER.

CONCLUSIONS

Alterations in microsatellite instability may be involved in the development of testicular tumor.

CMP-N-Acetylneuraminic acid hydroxylase is exclusively inactive in humans

We cloned cDNAs for mouse and human CMP-N-acetylneuraminic acid (CMP-NeuAc) hydroxylases and showed that the human CMP-NeuAc hydroxylase protein is inactive because of a partial deletion in the hydroxylase gene. We report here that no other active CMP-NeuAc hydroxylases are present in humans. Southern blot analysis showed that the human homologue of the mouse CMP-NeuAc hydroxylase is one gene in the human genome and no other homologues of the mouse hydroxylase exist in human genome. The mouse and the human CMP-NeuAc hydroxylases were mapped to chromosome 13A3 and chromosome 6p22, respectively, by fluorescence in situ hybridization. The chromosomal location of the human hydroxylase is syntenic to that of the mouse hydroxylase. These results demonstrate that the human CMP-NeuAc hydroxylase is the only homologue of the mouse hydroxylase, and CMP-NeuAc hydroxylase is exclusively inactive in humans.

The molecular basis for the absence of N-glycolylneuraminic acid in humans

N-Glycolylneuraminic acid (NeuGc) is abundantly expressed in most mammals, but it is not detectable in humans. The expression of NeuGc is controlled by cytidine monophospho-N-acetylneuraminic acid (CMP-NeuAc) hydroxylase activity. We previously cloned a cDNA for mouse CMP-NeuAc hydroxylase and found that the human genome contains a homologue. We report here the molecular basis for the absence of NeuGc in humans. We cloned a cDNA for human CMP-NeuAc hydroxylase from a HeLa cell cDNA library. The cDNA encodes a 486-amino acid protein, and its deduced amino acid sequence lacks a domain corresponding to the N-terminal 104 amino acids of the mouse CMP-NeuAc hydroxylase protein, although the human protein is highly identical (93%) to the rest of the mouse hydroxylase protein. The N-terminal truncation of the human hydroxylase is caused by deletion of a 92-base pair-long exon in human genomic DNA. The human hydroxylase expressed in COS-7 cells exhibited no enzymatic activity, and a mouse hydroxylase mutant, which lacks the N-terminal domain, was also inactive. A chimera composed of the human hydroxylase and the N-terminal domain of the mouse hydroxylase displayed the enzyme activity. These results indicate that the human homologue of CMP-NeuAc hydroxylase is inactive because it lacks an N-terminal domain that is essential for enzyme activity. The absence of NeuGc in human glycoconjugates is due to a partial deletion in the gene that encodes CMP-NeuAc hydroxylase.

Comparison of bromodeoxyuridine labeling indices of smears and sections from mouse NR-S1 tumor

Bromodeoxyuridine (BrdU) labeling indices (LIs) of smears and sections from mouse NR-S1 tumor were labeled in vivo or in vitro and compared to confirm the reliability of smears labeled in vitro. In vivo labeling was carried out by administering 40 mg/kg 5-bromo-2'-deoxyuridine while in vitro labeling was performed by incubating the tumor specimens in RPMI 1640 culture medium containing 200 microM 5-bromo-2'-deoxyuridine under 3 atmospheres. BrdU LIs of sections labeled in vitro (9.49 +/- 0.16) showed lower values than those labeled in vivo (14.95 +/- 0.36). BrdU LIs of smears labeled in vitro (9.87 +/- 0.23) also showed lower values than those labeled in vivo (14.83 +/- 0.49). However, the BrdU LIs of smears were similar to those of sections labeled in vivo and in vitro. In vitro BrdU immunochemistry in smears seems useful for evaluating the biological properties of tumor tissues.

Structural basis of integrin-mediated signal transduction

Integrins are a family of alpha/beta heterodimers of cell adhesion receptors that mediate cell-extracellular matrix and cell-cell interactions. Both alpha and beta subunits have a large extracellular domain and a short cytoplasmic domain. The alpha subunit has seven sequence repeats of 60-70 residues in its N-terminal region. The beta-propeller model, in which seven four-stranded beta-sheets are arranged in a torus around a pseudosymmetry axis, has been proposed as a structural model of these seven repeats. Several predicted loops critical for ligand binding have been identified in the upper face of the proposed beta-propeller model. Several alpha subunits (e.g., alpha 2, alpha L and alpha M) have I-domains of about 200 residues inserted between their second and third repeats. These I-domains adopt a Rossman-fold structure and have major ligand and cation binding sites (the MIDAS site) on their surfaces. The beta subunit has an I-domain-like structure in its N-terminal region. This structure includes multiple sequences/conserved oxygenated residues critical for ligand binding (e.g., Asp-119 in beta 3), and non-conserved residues critical for ligand specificities. Several "activation-dependent" epitopes have been identified in the Cys-rich (stalk) region of beta 1. It has yet to be determined how these multiple ligand binding sites in the alpha and beta subunits are involved in ligand binding, and how conformational changes on activation/ligand occupancy relate to signal transduction.

Defining the topology of integrin alpha5beta1-fibronectin interactions using inhibitory anti-alpha5 and anti-beta1 monoclonal antibodies. Evidence that the synergy sequence of fibronectin is recognized by the amino-terminal repeats of the alpha5 subunit

The high affinity interaction of integrin alpha5beta1 with the central cell binding domain (CCBD) of fibronectin requires both the Arg-Gly-Asp (RGD) sequence (in the 10th type III repeat) and a second site (in the adjacent 9th type III repeat) which synergizes with RGD. We have attempted to map the fibronectin binding interface on alpha5beta1 using monoclonal antibodies (mAbs) that inhibit ligand recognition. The binding of two anti-alpha5 mAbs (P1D6 and JBS5) to alpha5beta1 was strongly inhibited by a tryptic CCBD fragment of fibronectin (containing both synergy sequence and RGD) but not by GRGDS peptide. Using recombinant wild type and mutated fragments of the CCBD, we show that the synergy region of the 9th type III repeat is involved in blocking the binding of P1D6 and JBS5 to alpha5beta1. In contrast, binding of the anti-beta1 mAb P4C10 to alpha5beta1 was inhibited to a similar extent by GRGDS peptide, the tryptic CCBD fragment, or recombinant proteins lacking the synergy region, indicating that the RGD sequence is involved in blocking P4C10 binding. P1D6 inhibited the interaction of a wild type CCBD fragment with alpha5beta1 but had no effect on the binding of a mutant fragment that lacked the synergy region. The epitopes of P1D6 and JBS5 mapped to the NH2-terminal repeats of the alpha5 subunit. Our results indicate that the synergy region is recognized primarily by the alpha5 subunit (in particular by its NH2-terminal repeats) but that the beta1 subunit plays the major role in binding of the RGD sequence. These findings provide new insights into the mechanisms, specificity, and topology of integrin-ligand interactions.

Multiple loop structures critical for ligand binding of the integrin alpha4 subunit in the upper face of the beta-propeller mode 1

A non-I-domain integrin, alpha4beta1, recognizes vascular cell adhesion molecule 1 (VCAM-1) and the IIICS portion of fibronectin. To localize regions of alpha4 critical for ligand binding, we swapped several predicted loops within or near the putative ligand-binding site of alpha4 (which spans repeats 2-5 of the seven N-terminal repeats) with the corresponding regions of alpha5. Swapping residues 112-131 in repeat 2, or residues 237-247 in repeat 4, completely blocked adhesion to immobilized VCAM-1 and connecting segment 1 (CS-1) peptide. However, swapping residues 40-52 in repeat 1, residues 151-164 in repeat 3, or residues 282-288 (which contain a putative cation binding motif) in repeat 5 did not affect or only slightly reduced adhesion to these ligands. The binding of several function-blocking antibodies is blocked by swapping residues 112-131, 151-164, and 186-191 (which contain previously identified residues critical for ligand binding, Tyr-187 and Gly-190). These results are consistent with the recently published beta-propeller folding model of the integrin alpha4 subunit [Springer, T. A. (1997) Proc. Natl. Acad. Sci. USA 94, 65-72], in which seven four-stranded beta-sheets are arranged in a torus around a pseudosymmetric axis. The regions of alpha4 critical for ligand binding are adjacent to each other and are located in the upper face, the predicted ligand-binding site, of the beta-propeller model, although they are not adjacent in the primary structure.

Surgical risks of acute cholecystitis in elderly

BACKGROUND/AIMS

For the elderly patient, an emergency biliary procedure carries a higher risk than an elective operation. Recently introduced advances in ultrasonography and critical care medicine have affected the clinical risks of surgery for acute cholecystitis in the elderly. This study evaluated the clinical risks of open cholecystectomy for the elderly with acute cholecystitis.

MATERIALS AND METHODS

During a 10 year period (1985-1994), a total of 145 patients were diagnosed with acute cholecystitis and underwent cholecystectomy. According to their age, the patients were divided into 3 groups (Group A < 59 years of age; Group B between 60-69 years of age; Group C > 70 years of age). The characteristics and the surgical risk factors in open cholecystectomy for the elderly with acute cholecystitis were evaluated.

RESULTS

The rate of acalculous cholecystitis and choledochal stones were significantly (p < 0.05) high in Group C. Septic complication, gangrenous changes, and positive bile culture were also increased parallel to the increase in age. A noteworthy finding was an incidental carcinoma found in a case in group B and in 3 cases in group C. Hospital stay was significantly longer in Group C than in the other groups due to pre-operative complications and post-operative morbidity.

CONCLUSION

With respect to increase in elderly patients with acute cholecystitis who present more frequent gangrenous changes and carcinomatous changes as well as high rate of septic complication, successful treatment of these patients is increased when early surgery can be performed on the basis of accurate and prompt diagnosis using imaging modalities and meticulous peri-operative management.

Critical residues of integrin alphaIIb subunit for binding of alphaIIbbeta3 (glycoprotein IIb-IIIa) to fibrinogen and ligand-mimetic antibodies (PAC-1, OP-G2, and LJ-CP3)

Integrin alphaIIbbeta3 plays a critical role in platelet aggregation through its interaction with fibrinogen. Elucidation of the mechanisms of alphaIIbbeta3-fibrinogen interaction is critical to understanding hemostasis and thrombosis. Here we report that mutations of Gly-184, Tyr-189, Tyr-190, Phe-191, and Gly-193 within the predicted turn structure of the third amino-terminal repeat of alphaIIb significantly block binding of alphaIIbbeta3 to soluble fibrinogen. These mutations also block binding of alphaIIbbeta3 to ligand-mimetic monoclonal antibodies PAC-1, OP-G2, LJ-CP3, which have an RGD-related RYD sequence in their antigen-binding sites. These mutations do not significantly affect the expression of alphaIIbbeta3, in contrast to most of the natural alphaIIb mutations occurring in Glanzmann's thrombasthenic patients. The data suggest that these residues are critically involved in alphaIIbbeta3-ligand interactions.

Abrogation of lung metastasis of human fibrosarcoma cells by ribozyme-mediated suppression of integrin alpha6 subunit expression

The interaction of tumor cells with the basement membrane plays a crucial role in tumor metastasis. VLA-6 (alpha6beta1) integrin is one of the major surface receptors for the basement membrane, specifically recognizing laminin. To study the role of VLA-6 integrin in tumor invasion and metastasis, we synthesized a ribozyme that selectively degrades the integrin alpha6 subunit mRNA. The catalytic activity of the ribozyme was verified by in vitro cleavage of alpha6 subunit mRNA. Introduction of the anti-alpha6 ribozyme gene into the human fibrosarcoma cell line HT1080 yielded stable transfectants, which expressed a significantly reduced level of integrin alpha6 mRNA. Flow cytometric analysis showed that the surface expression of VLA-6, but not other integrins, was reduced by approximately 70% in transfected cells. Ribozyme-transfected cells were less adherent to laminin-coated substrata and less invasive into reconstituted basement membrane than mock-transfected cells. When injected i.v. into nude mice, ribozyme-transfected cells produced no lung metastasis in all except 1 of 35 mice, though mock-transfected cells produced multiple lung metastases in 22 of 29 mice. Our results indicate that VLA-6 integrin plays a critical role in tumor invasion and metastasis and may serve as a potential target for eradication of tumor metastasis in the lung.

Induction of experimental bone metastasis in mice by transfection of integrin alpha 4 beta 1 into tumor cells

Cell adhesion receptors (eg, integrins and CD44) play an important role in invasion and metastasis during tumor progression. The increase in integrin alpha 4 beta 1 expression on primary melanomas has been reported to significantly correlate with the development of metastases. alpha 4 beta 1 is a cell surface heterodimer that mediates cell-cell and cell-extracellular matrix interactions through adhesion to vascular cell adhesion molecule (VCAM)-1 and to the IIICS region of fibronectin. To test the effects of alpha 4 beta 1 expression on tumor cell metastasis, Chinese hamster ovary cells were transfected with human alpha 4 cDNA. Whereas alpha 4-negative Chinese hamster ovary cells developed only pulmonary metastasis, alpha 4-positive Chinese hamster ovary cells developed bone and pulmonary metastasis in 3 to 4 weeks when injected intravenously into nude mice. Bone metastasis was inhibited by antibody against alpha 4 or VCAM-1. Expression of alpha 3 beta 1, alpha 6 beta 1, or alpha V beta 1 did not induce bone metastasis. Expression of alpha 4 beta 1 also induced bone metastasis in K562 human erythroleukemia cells injected into SCID mice. These results demonstrate that alpha 4 beta 1 can induce tumor cell trafficking to bone, probably via interaction with VCAM-1 that is constitutively expressed on bone marrow stromal cells.