[Ergonomical study on Chinese speech warning]

Ergonomical experiments on speech warning under noise background were carried out in 40 healthy males, aged 20-33. Through the determination of auditory reaction time to the Chinese speech warning under dual-tasks and the subjective evalution of the suitable time length of main warning voice by the subject, the optimum parameters of Chinese speech warning in accordance with space ergonomics were determined. It was found that: suitable time length of main warning voice is 0.35-0.55s, main interval is 0.15-0.35s, speech speed is 4-6 word/s, and sentence interval is 0.2-0.4s. Meanwhile, the analysis of heart rate (HR) and heart rate variability (HRV) demonstrated that the speech warning using aforementioned parameters didn't increase the operator's work load. The results can serve as the objective ergonomical basis and the evaluation criterion for design of speech warning in manned space vehicle.

cDNA cloning and characterization of a cis-retinol/3alpha-hydroxysterol short-chain dehydrogenase

We report a mouse cDNA that encodes a 317-amino acid short-chain dehydrogenase which recognizes as substrates 9-cis-retinol, 11-cis-retinol, 5alpha-androstan-3alpha,17beta-diol, and 5alpha-androstan-3alpha-ol-17-one. This cis-retinol/androgen dehydrogenase (CRAD) shares closest amino acid similarity with mouse retinol dehydrogenase isozymes types 1 and 2 (86 and 91%, respectively). Recombinant CRAD uses NAD+ as its preferred cofactor and exhibits cooperative kinetics for cis-retinoids, but Michaelis-Menten kinetics for 3alpha-hydroxysterols. Unlike recombinant retinol dehydrogenase isozymes, recombinant CRAD was inhibited by 4-methylpyrazole, was not stimulated by ethanol, and did not require phosphatidylcholine for optimal activity. CRAD mRNA was expressed intensely in kidney and liver, in contrast to retinol dehydrogenase isozymes, which show strong mRNA expression only in liver. CRAD mRNA expression was widespread (relative abundance): kidney (100) > liver (92) > small intestine (9) = heart (9) > retinal pigment epithelium and sclera (4.5) > brain (2) > retina and vitreous (1.6) > spleen (0.7) > testis (0.6) > lung (0.4). CRAD may catalyze the first step in an enzymatic pathway from 9-cis-retinol to generate the retinoid X receptor ligand 9-cis-retinoic acid and/or may regenerate dihydrotestosterone from its catabolite 5alpha-androstan-3alpha,17beta-diol. These data also illustrate the multifunctional nature of short-chain dehydrogenases and provide a potential mechanism for androgen-retinoid interactions.

Immunohistochemical analysis of the expression of cdk4 and p16INK4 in human endometrioid-type endometrial carcinoma

BACKGROUND

Abnormalities in G1 cell cycle regulation have been associated with the malignant transformation of cells. To obtain further information about the role of factors regulating the G1 cell cycle in the development of endometrial carcinoma, the authors analyzed the expression of cdk4 (cyclin-dependent kinase) and p16INK4 (an inhibitor of cdk4).

METHODS

Immunohistochemical staining was performed on 20 specimens of normal endometria and 41 specimens of endometrioid-type endometrial carcinoma using antibodies against cdk4 and p16INK4.

RESULTS

In the glandular epithelia of the normal endometria, cytoplasmic staining of cdk4 and p16INK4 was observed only in the proliferative phase, but nuclear staining of these agents was negligible. In endometrial carcinomas, 8 (19.5%) and 14 (34.2%) were positive for cdk4 and p16INK4 in the nucleus, respectively. Topographically, the nuclear cdk4 positive tumor cells were negative for p16INK4 and the nuclear p16INK4 positive tumor cells were found in areas without nuclear cdk4 expression, suggesting an inverse correlation between the two agents. In addition, the poorly differentiated carcinomas were more frequently positive for nuclear cdk4 than were the highly differentiated carcinomas (P = 0.03).

CONCLUSIONS

These data suggest that increased expression of nuclear cdk4 associated with loss of p16INK4 expression could be involved in the carcinogenesis of a subset of endometrial carcinomas.

Coexpression of the mRNAs encoding retinol dehydrogenase isozymes and cellular retinol-binding protein

We used in situ hybridization of adult rat tissue to show that mRNAs encoding cellular retinol-binding protein (CRBP) and retinol dehydrogenase (RoDH) isozymes I/III and II were expressed in hepatocytes uniformly throughout the liver lobule, but were absent from Kupffer cells and endothelial cells of blood vessels and bile ducts. In kidney, CRBP, RoDH(I), and RoDH(II) were found in the proximal tubules of the cortex. Distal tubules, Henle's loops, collecting ducts, and glomeruli showed little, if any, expression. In testis, CRBP, RoDH(I), and RoDH(II) were found in Sertoli cells. Expression, albeit weaker, also occurred in spermatogonia and primary spermatocytes. Peritubular cells and other germ cells had even weaker expression. Only CRBP and RoDH(II) mRNA were detected in interstitial cells. In lung CRBP, RoDH(I) and RoDH(II) were expressed most intensely in the epithelium of the bronchi and bronchioli, but also occurred in the simple columnar epithelial cells of the alveolar duct and in alveolar type II cells. These data are consistent with the hypothesis that holo-CRBP serves as substrate for retinoic acid biosynthesis because they show that the substrate and the enzyme occur in the same cellular loci in vivo. These data also indicate that multiple cellular sites of retinoic acid biosynthesis occur throughout tissues. Also, the general concordance between mRNA localization and CRBP expression patterns, revealed by previous immunocytochemistry studies, supports and extends the conclusion that CRBP mRNA expression correlates with CRBP expression, based earlier on comparing RNA assays with radioimmunoassays.

Arotinoid mofarotene (RO40-8757) up-regulates p21 and p27 during growth inhibition of pancreatic cancer cell lines

Effective chemotherapy for pancreatic cancer is urgently needed. The anti-proliferative activity of a new retinoid, mofarotene (RO40-8757), was compared with that of other retinoids, such as all trans-retinoic acid, 13-cis retinoic acid and 9-cis retinoic acid, on 9 pancreatic cancer cell lines in relation to the effects on various cell cycle-regulating factors. After treatment with each retinoid, anti-proliferative effect was determined by the MTT method and expression of cell cycle-regulating factors, such as cyclins (D1, E and A), cyclin-dependent kinases (2 and 4), cyclin-dependent kinase inhibitors (p21 and p27) and retinoblastoma protein, was analyzed by Western blotting. Mofarotene showed half-maximal inhibition of cell proliferation at concentrations between 0.14 x 10(-6) and 3.8 x 10(-6) mol/l with little cytotoxicity. In contrast, the other retinoids did not inhibit the growth of all cell lines by over 50% compared to controls. A marked increase in the fraction of cells in G1 phase of the cell cycle was observed after mofarotene treatment; this was associated with marked up-regulation of p21/p27 and a shift of retinoblastoma protein into the hypophosphorylated form. In conclusion, mofarotene inhibits the growth of pancreatic cancer cells by inducing G1-phase cell cycle-inhibitory factors (p21, p27 and hypophosphorylated form of Rb protein) and is considered to be a useful agent for pancreatic cancer treatment.

Direct MHC class I complementary DNA transfer to thymus induces donor-specific unresponsiveness, which involves multiple immunologic mechanisms

Our purposes were 1) to determine whether direct transfer of cDNA encoding allogeneic MHC class I Ag to the rat thymus would be capable of inducing donor-specific unresponsiveness and 2) to study the immunologic mechanism of this effect. Plasmid DNA encoding donor strain (ACI-RT1.Aa) MHC class I Ag was directly injected into Lewis (RT1(l)) rat recipient thymus 7 to 10 days before ACI liver transplantation. A single dose of anti-lymphocyte serum was given i.p. on the day of thymic injection. Rats injected intrathymically with plasmid DNA and treated with anti-lymphocyte serum demonstrated prolonged survival in 9 of 13 rats (>100 days). PCR was used to demonstrate that RT1.Aa cDNA was expressed in thymus transiently and later appeared in spleen. CTL limiting dilution assays showed that CTL precursor frequency was decreased in tolerant liver recipients. To test the hypothesis of clonal deletion vs anergy, CTL limiting dilution assays cultures were restimulated with donor cells and IL-2 to reverse anergy. Restimulation caused CTL precursor frequency to return to near normal in only one of five tolerant rats, suggesting clonal deletion or a dense anergic state. Passive transfer of splenocytes from tolerant rats to naive recipients prolonged cardiac allograft survival, suggesting that suppressor-type cells may also contribute to thymic tolerance in our model. In summary, our data suggest that donor MHC class I Ag expressed in thymus by direct DNA injection, followed by liver allografting, results in donor-specific unresponsiveness. The mechanism of this effect is complex, involving multiple immunologic mechanisms.

Direct MHC class I complementary DNA transfer to thymus induces donor-specific unresponsiveness, which involves multiple immunologic mechanisms

Our purposes were 1) to determine whether direct transfer of cDNA encoding allogeneic MHC class I Ag to the rat thymus would be capable of inducing donor-specific unresponsiveness and 2) to study the immunologic mechanism of this effect. Plasmid DNA encoding donor strain (ACI-RT1.Aa) MHC class I Ag was directly injected into Lewis (RT1(l)) rat recipient thymus 7 to 10 days before ACI liver transplantation. A single dose of anti-lymphocyte serum was given i.p. on the day of thymic injection. Rats injected intrathymically with plasmid DNA and treated with anti-lymphocyte serum demonstrated prolonged survival in 9 of 13 rats (>100 days). PCR was used to demonstrate that RT1.Aa cDNA was expressed in thymus transiently and later appeared in spleen. CTL limiting dilution assays showed that CTL precursor frequency was decreased in tolerant liver recipients. To test the hypothesis of clonal deletion vs anergy, CTL limiting dilution assays cultures were restimulated with donor cells and IL-2 to reverse anergy. Restimulation caused CTL precursor frequency to return to near normal in only one of five tolerant rats, suggesting clonal deletion or a dense anergic state. Passive transfer of splenocytes from tolerant rats to naive recipients prolonged cardiac allograft survival, suggesting that suppressor-type cells may also contribute to thymic tolerance in our model. In summary, our data suggest that donor MHC class I Ag expressed in thymus by direct DNA injection, followed by liver allografting, results in donor-specific unresponsiveness. The mechanism of this effect is complex, involving multiple immunologic mechanisms.

A role for mitogen-activated protein kinase in the spindle assembly checkpoint in XTC cells

The spindle assembly checkpoint prevents cells whose spindles are defective or chromosomes are misaligned from initiating anaphase and leaving mitosis. Studies of Xenopus egg extracts have implicated the Erk2 mitogen-activated protein kinase (MAP kinase) in this checkpoint. Other studies have suggested that MAP kinases might be important for normal mitotic progression. Here we have investigated whether MAP kinase function is required for mitotic progression or the spindle assembly checkpoint in vivo in Xenopus tadpole cells (XTC). We determined that Erk1 and/or Erk2 are present in the mitotic spindle during prometaphase and metaphase, consistent with the idea that MAP kinase might regulate or monitor the status of the spindle. Next, we microinjected purified recombinant XCL100, a Xenopus MAP kinase phosphatase, into XTC cells in various stages of mitosis to interfere with MAP kinase activation. We found that mitotic progression was unaffected by the phosphatase. However, XCL100 rendered the cells unable to remain arrested in mitosis after treatment with nocodazole. Cells injected with phosphatase at prometaphase or metaphase exited mitosis in the presence of nocodazole-the chromosomes decondensed and the nuclear envelope re-formed-whereas cells injected with buffer or a catalytically inactive XCL100 mutant protein remained arrested in mitosis. Coinjection of constitutively active MAP kinase kinase-1, which opposes XCL100's effects on MAP kinase, antagonized the effects of XCL100. Since the only known targets of MAP kinase kinase-1 are Erk1 and Erk2, these findings argue that MAP kinase function is required for the spindle assembly checkpoint in XTC cells.

Selective up-regulation of alpha1a-adrenergic receptor protein and mRNA in brown adipose tissue by neural and beta3-adrenergic stimulation

Previous studies have shown that neural stimulation of brown adipose tissue (BAT) reorganizes the expression and activity of signaling proteins in the beta-adrenergic adenylyl cyclase pathway. Cold stress increases neural stimulation of BAT and increases alpha1-adrenergic receptor number; however, the alpha1 receptor subtype involved and the mechanism of up-regulation by cold stress have not been determined. Using reverse transcription/polymerase chain reaction analysis and nuclease protection assay, BAT was demonstrated to express mRNAs encoding alpha1a and alpha1d, but not alpha1b, receptors. Parallel pharmacologic studies of BAT membranes and recombinant alpha1a and alpha1d receptors expressed in COS-7 cells demonstrated that alpha1a receptors predominate in BAT. Exposure of rats to 4 degrees for 4 days increased alpha1a receptors and mRNA in BAT but did not alter expression of alpha1d receptors or mRNA. The induction of alpha1a receptor and mRNA level by cold stress was prevented by selective surgical denervation of BAT. Furthermore, alpha1a receptor and mRNA expression could be induced in warm-adapted rats by infusions of the selective beta3-adrenergic receptor agonist CL 316,243. These data indicate that neural activation of beta3-adrenergic receptors is an important determinant of alpha1a adrenergic receptor expression in BAT.

FN18-CRM9 immunotoxin promotes tolerance in primate renal allografts

BACKGROUND

Transplant tolerance, rather than immunity, may be favored in the setting of a lower mature lymphoid mass in the recipient induced by anti-T cell agents. A novel immunosuppressive agent, FN18-CRM9, known to specifically kill T cells with great potency, was evaluated in a transplant model.

METHODS

In order to ablate recipient T cells, the immunotoxin FN18-CRM9 was administered to rhesus monkey recipients of MHC-mismatched renal allografts. Donor lymphocytes were injected intrathymically into some animals.

RESULTS

All monkeys with T-cell depletion by immunotoxin had prolonged allograft survival, and tolerance confirmed by skin grafting has been confirmed in five of six long-surviving recipients.

CONCLUSIONS

In this clinically relevant model, profound but transient T-cell depletion by a single agent substantially promotes tolerance.

[Quality criteria for bazhen shennongyin liquor]

Radix Angelicae Sinensis, Radix Paeoniae Alba and Radix et Rhizoma Rhei in Bazhen Shengnongyin Liquor were identified by TLC. The contents of ginsenoside Rb1 in the preparation was determined by TLCS. Simple, accurate and reproducible, this method could be used as the quality criteria for this preparation.

Cloning and characterization of the genes encoding the murine homologues of the human melanoma antigens MART1 and gp100

The recent identification of genes encoding melanoma-associated antigens has opened new possibilities for the development of cancer vaccines designed to cause the rejection of established tumors. To develop a syngeneic animal model for evaluating antigen-specific vaccines in cancer therapy, the murine homologues of the human melanoma antigens MART1 and gp100, which were specifically recognized by tumor-infiltrating lymphocytes from patients with melanoma, were cloned and sequenced from a murine B16 melanoma cDNA library. The open reading frames of murine MART1 and gp100 encode proteins of 113- and 626-amino acids with 68.8 and 77% identity to the respective human proteins. Comparison of the DNA sequences of the murine MART1 genes, derived from normal melanocytes, the immortalized nontumorgenic melanocyte line Melan-a and the B16 melanoma, showed all to be identical. Northern and Western blot analyses confirmed that both genes encoded products that were melanocyte lineage proteins. Mice immunized with murine MART1 or gp100 using recombinant vaccinia virus failed to produce any detectable T-cell responses or protective immunity against B16 melanoma. In contrast, immunization of mice with human gp100 using recombinant adenoviruses elicited T cells specific for hgp100, but these T cells also cross reacted with B16 tumor in vitro and induced significant but weak protection against B16 challenge. Immunization with human and mouse gp100 together [adenovirus type 2 (Ad2)-hgp100 plus recombinant vaccinia virus (rVV)-mgp100], or immunization with human gp100 (Ad2-hgp100) and boosting with heterologous vector (rVV-hgp100 or rVV-mgp100) or homologous vector (Ad2-hgp100), did not significantly enhance the protective response against B16 melanoma. These results may suggest that immunization with heterologous tumor antigen, rather than self, may be more effective as an immunotherapeutic reagent in designing antigen-specific cancer vaccines.

Vitamin D analogues up-regulate p21 and p27 during growth inhibition of pancreatic cancer cell lines

To obtain information regarding the growth-inhibitory effect of 1,25-dihydroxyvitamin D3 and its non-calcaemic analogue 22-oxa-1,25-dihydroxyvitamin D3 on pancreatic cancer cell lines, differences in the effects of G1-phase cell cycle-regulating factors were studied in vitamin D-responsive and non-responsive cell lines. Levels of expression of cyclins (D1, E and A), cyclin-dependent kinases (2 and 4) and cyclin-dependent kinase inhibitors (p21 and p27) were analysed by Western blotting after treatment with these compounds. In the responsive cells (BxPC-3, Hs 700T and SUP-1), our observations were: (1) marked up-regulation of p21 and p27 after 24 h treatment with 10(-7) mol l(-1) 1,25-dihydroxyvitamin D3 and 22-oxa-1,25-dihydroxyvitamin D3; and (2) marked down-regulation of cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors after 7 days' treatment. In non-responsive cells (Hs 766T and Capan-1), no such changes were observed. In conclusion, vitamin D analogues up-regulate p21 and p27 as an early event, which in turn could block the G1/S transition and induce growth inhibition in responsive cells.

Microtubule dynamics at the G2/M transition: abrupt breakdown of cytoplasmic microtubules at nuclear envelope breakdown and implications for spindle morphogenesis

We recently developed a direct fluorescence ratio assay (Zhai, Y., and G.G. Borisy. 1994. J. Cell Sci. 107:881-890) to quantify microtubule (MT) polymer in order to determine if net MT depolymerization occurred upon anaphase onset as the spindle was disassembled. Our results showed no net decrease in polymer, indicating that the disassembly of kinetochore MTs was balanced by assembly of midbody and astral MTs. Thus, the mitosis-interphase transition occurs by a redistribution of tubulin among different classes of MTs at essentially constant polymer level. We now examine the reverse process, the interphase-mitosis transition. Specifically, we quantitated both the level of MT polymer and the dynamics of MTs during the G2/M transition using the fluorescence ratio assay and a fluorescence photoactivation approach, respectively. Prophase cells before nuclear envelope breakdown (NEB) had high levels of MT polymer (62%) similar to that previously reported for random interphase populations (68%). However, prophase cells just after NEB had significantly reduced levels (23%) which recovered as MT attachments to chromosomes were made (prometaphase, 47%; metaphase, 56%). The abrupt reorganization of MTs at NEB was corroborated by anti-tubulin immunofluorescence staining using a variety of fixation protocols. Sensitivity to nocodazole also increased at NEB. Photoactivation analyses of MT dynamics showed a similar abrupt change at NEB, basal rates of MT turnover (pre-NEB) increased post-NEB and then became slower later in mitosis. Our results indicate that the interphase-mitosis (G2/M) transition of the MT array does not occur by a simple redistribution of tubulin at constant polymer level as the mitosis-interphase (M/G1) transition. Rather, an abrupt decrease in MT polymer level and increase in MT dynamics occurs tightly correlated with NEB. A subsequent increase in MT polymer level and decrease in MT dynamics occurs correlated with chromosome attachment. These results carry implications for understanding spindle morphogenesis. They indicate that changes in MT dynamics may cause the steady-state MT polymer level in mitotic cells to be lower than in interphase. We propose that tension exerted on the kMTs may lead to their lengthening and thereby lead to an increase in the MT polymer level as chromosomes attach to the spindle.

Cloning of a rat cDNA encoding retinol dehydrogenase isozyme type III

The primary and rate-limiting step in retinoic acid (RA) biosynthesis requires the conversion of retinol into retinal. Previously, two genes encoding retinol dehydrogenases (RoDH), which recognize holo-cellular retinol-binding protein as substrate, had been cloned, expressed and identified as members of the short-chain dehydrogenase/reductase (SDR) gene family. This work reports the cloning of a cDNA encoding a third RoDH isozyme, RoDH(III). The deduced amino-acid sequence of RoDH(III) indicates 97.8% identity with RoDH(I) and 82.3% identity with RoDH(II). RNase protection assays revealed RoDH(III) mRNA expression only in rat liver, in contrast to RoDH(I) and RoDH(II), which had their mRNA expressed in rat liver, kidney, lung, testis and brain. These data extend the insight that a subfamily of SDR isozymes, tissue-distinctively expressed, catalyzes the first step in RA biogenesis.

Removal of MAP4 from microtubules in vivo produces no observable phenotype at the cellular level

Microtubule-associated protein 4 (MAP4) promotes MT assembly in vitro and is localized along MTs in vivo. These results and the fact that MAP4 is the major MAP in nonneuronal cells suggest that MAP4's normal functions may include the stabilization of MTs in situ. To understand MAP4 function in vivo, we produced a blocking antibody (Ab) to prevent MAP4 binding to MTs. The COOH-terminal MT binding domain of MAP4 was expressed in Escherichia coli as a glutathione transferase fusion protein and was injected into rabbits to produce an antiserum that was then affinity purified and shown to be monospecific for MAP4. This Ab blocked > 95% of MAP4 binding to MTs in an in vitro assay. Microinjection of the affinity purified Ab into human fibroblasts and monkey epithelial cells abolished MAP4 binding to MTs as assayed with a rat polyclonal antibody against the NH2-terminal projection domain of MAP4. The removal of MAP4 from MTs was accompanied by its sequestration into visible MAP4-Ab immunocomplexes. However, the MT network appeared normal. Tubulin photoactivation and nocodazole sensitivity assays indicated that MT dynamics were not altered detectably by the removal of MAP4 from the MTs. Cells progressed to mitosis with morphologically normal spindles in the absence of MAP4 binding to MTs. Depleting MAP4 from MTs also did not affect the state of posttranslational modifications of tubulin subunits. Further, no perturbations of MT-dependent organelle distribution were detected. We conclude that the association of MAP4 with MTs is not essential for MT assembly or for the MT-based functions in cultured cells that we could assay. A significant role for MAP4 is not excluded by these results, however, as MAP4 may be a component of a functionally redundant system.

Antigen-specific tumor vaccines. Development and characterization of recombinant adenoviruses encoding MART1 or gp100 for cancer therapy

The human melanoma tumor Ags, MART1 and gp100, are specifically recognized by HLA-A2-restricted CD8+ CTLs derived from melanoma patients and appear to be involved in tumor regression. In order to develop immunizing vectors for the treatment of patients with metastatic melanoma, replication-defective recombinant adenoviruses, Ad2CMV-MART1 and Ad2CMV-gp100, which encode these tumor Ags, have been generated. Infection of non-Ag expressing HLA-A2+ cell lines A375 and MDA-231 with the vectors resulted in recognition by Ag-specific CTLs as demonstrated by specific target cell lysis and release of cytokines, including IFN-gamma, TNF-alpha, and granulocyte-macrophage-CSF. Sodium butyrate and TNF-alpha can further augment adenovirus-mediated transgene expression and increase recognition by specific CTLs. Although adenovirus-infected cells expressed the E3/19K protein at detectable levels, significant reduction of surface MHC class I expression was observed in only 3 of 10 tumor cell lines infected with either Ad2CMV-MART1 or Ad2CMV-gp100. Because of the suspected homology between the human MART1 and gp100 genes and their murine counterparts, we immunized C57BL/6 mice with these recombinant adenoviruses and demonstrated that immunization with Ad2CMV-gp100 could protect mice from murine melanoma B16 challenge administered intradermally. Depletion of CD8+ but not CD4+ T cells in vivo from Ad2CMV-gp100-vaccinated mice eliminated the protective effect. The anti-gp100 T cells induced by Ad2CMV-gp100 vaccinated appeared to be responsible for the protection. Thus, these recombinant adenoviruses encoding tumor Ags may be useful as vaccines to induce specific T cell immunity for cancer therapy.

Antigen-specific tumor vaccines. Development and characterization of recombinant adenoviruses encoding MART1 or gp100 for cancer therapy

The human melanoma tumor Ags, MART1 and gp100, are specifically recognized by HLA-A2-restricted CD8+ CTLs derived from melanoma patients and appear to be involved in tumor regression. In order to develop immunizing vectors for the treatment of patients with metastatic melanoma, replication-defective recombinant adenoviruses, Ad2CMV-MART1 and Ad2CMV-gp100, which encode these tumor Ags, have been generated. Infection of non-Ag expressing HLA-A2+ cell lines A375 and MDA-231 with the vectors resulted in recognition by Ag-specific CTLs as demonstrated by specific target cell lysis and release of cytokines, including IFN-gamma, TNF-alpha, and granulocyte-macrophage-CSF. Sodium butyrate and TNF-alpha can further augment adenovirus-mediated transgene expression and increase recognition by specific CTLs. Although adenovirus-infected cells expressed the E3/19K protein at detectable levels, significant reduction of surface MHC class I expression was observed in only 3 of 10 tumor cell lines infected with either Ad2CMV-MART1 or Ad2CMV-gp100. Because of the suspected homology between the human MART1 and gp100 genes and their murine counterparts, we immunized C57BL/6 mice with these recombinant adenoviruses and demonstrated that immunization with Ad2CMV-gp100 could protect mice from murine melanoma B16 challenge administered intradermally. Depletion of CD8+ but not CD4+ T cells in vivo from Ad2CMV-gp100-vaccinated mice eliminated the protective effect. The anti-gp100 T cells induced by Ad2CMV-gp100 vaccinated appeared to be responsible for the protection. Thus, these recombinant adenoviruses encoding tumor Ags may be useful as vaccines to induce specific T cell immunity for cancer therapy.

Therapeutic antitumor response after immunization with a recombinant adenovirus encoding a model tumor-associated antigen

Recombinant adenovirus (rAd), deleted of critical genes that enable viral replication and replaced with genes encoding heterologous proteins, has been shown to be a safe and effective vector in gene therapy studies. To evaluate a potential role for rAd as an immunogen, we used two different replication-defective type 2 rAds encoding the model Ag, beta-galactosidase (beta-gal). To determine whether rAd elicited the kind of immune responses therapeutic in an anti-tumor setting, the beta-gal-expressing adenocarcinoma, CT26.CL25, was used. Splenocytes from BALB/c mice immunized with 1 x 10(7) infectious units (iu) of rAd demonstrated anti-beta-gal activity after in vitro culture with the relevant L(d) beta-gal peptide. Adoptive transfer of these same splenocytes produced dramatic regression of established pulmonary metastases. However, when tumor-bearing mice were treated with 1 x 10(7) iu of rAd, no reduction in established disease was observed even when rAd was given with exogenous IL-2. To increase the viral dose delivered to each animal, we used an E1-E4-deleted rAd that could be grown to much higher titers. Significant reduction occurred with 10-fold more rAd (1 x10(8) iu) was administered. Exogenous IL-2 administration with 1 x 10(8) iu of rAd resulted in augmentation of this anti-tumor effect. These findings demonstrate that when using a nonreplicating virus, the viral dose is directly related to the immune response generated. These data constitute the first reported use of rAd in the treatment of an established experimental cancer and may have implication for the treatment of human cancer.

Therapeutic antitumor response after immunization with a recombinant adenovirus encoding a model tumor-associated antigen

Recombinant adenovirus (rAd), deleted of critical genes that enable viral replication and replaced with genes encoding heterologous proteins, has been shown to be a safe and effective vector in gene therapy studies. To evaluate a potential role for rAd as an immunogen, we used two different replication-defective type 2 rAds encoding the model Ag, beta-galactosidase (beta-gal). To determine whether rAd elicited the kind of immune responses therapeutic in an anti-tumor setting, the beta-gal-expressing adenocarcinoma, CT26.CL25, was used. Splenocytes from BALB/c mice immunized with 1 x 10(7) infectious units (iu) of rAd demonstrated anti-beta-gal activity after in vitro culture with the relevant L(d) beta-gal peptide. Adoptive transfer of these same splenocytes produced dramatic regression of established pulmonary metastases. However, when tumor-bearing mice were treated with 1 x 10(7) iu of rAd, no reduction in established disease was observed even when rAd was given with exogenous IL-2. To increase the viral dose delivered to each animal, we used an E1-E4-deleted rAd that could be grown to much higher titers. Significant reduction occurred with 10-fold more rAd (1 x10(8) iu) was administered. Exogenous IL-2 administration with 1 x 10(8) iu of rAd resulted in augmentation of this anti-tumor effect. These findings demonstrate that when using a nonreplicating virus, the viral dose is directly related to the immune response generated. These data constitute the first reported use of rAd in the treatment of an established experimental cancer and may have implication for the treatment of human cancer.

Cloning of a cDNA for a second retinol dehydrogenase type II. Expression of its mRNA relative to type I

A retinol dehydrogenase, RoDH(1), which recognizes holo-cellular retinol-binding protein (CRBP) as substrate, has been cloned, expressed, and identified as a short-chain dehydrogenase/reductase (Chai, X., Boerman, M. H. E. M., Zhai, Y., and Napoli, J. L. (1995) J. Biol. Chem. 270, 3900-3904). This work reports the cloning and expression of a cDNA encoding a RoDH isozyme, RoDH(II). The predicted amino acid sequence verifies RoDH(II) as a short-chain dehydrogenase/reductase, 82% identical with RoDH(I). RoDH(II) recognized the physiological form of retinol as substrate, CRBP, with a Km of 2 mM. Similar to microsomal RoDH and RoDH(I), RoDH(II) had higher activity with NADP rather than NAD, was stimulated by ethanol and phosphatidyl choline, was not inhibited by the medium-chain alcohol dehydrogenase inhibitor 4-methylpyrazole, but was inhibited by phenylarsine oxide and the short-chain dehydrogenase/reductase inhibitor carbenoxolone. Northern blot analysis detected RoDH(I) and RoDH(II) mRNA only in rat liver, but RNase protection assays revealed RoDH(I) and RoHD(II) mRNA in kidney, lung, testis, and brain. These data indicate that short-chain dehydrogenases/reductase isozymes expressed tissue-distinctively catalyze the first step of retinoic acid biogenesis from the physiologically most abundant substrate, CRBP.

Kinetochore microtubule dynamics and the metaphase-anaphase transition

We have quantitatively studied the dynamic behavior of kinetochore fiber microtubules (kMTs); both turnover and poleward transport (flux) in metaphase and anaphase mammalian cells by fluorescence photoactivation. Tubulin derivatized with photoactivatable fluorescein was microinjected into prometaphase LLC-PK and PtK1 cells and allowed to incorporate to steady-state. A fluorescent bar was generated across the MTs in a half-spindle of the mitotic cells using laser irradiation and the kinetics of fluorescence redistribution were determined in terms of a double exponential decay process. The movement of the activated zone was also measured along with chromosome movement and spindle elongation. To investigate the possible regulation of MT transport at the metaphase-anaphase transition, we performed double photoactivation analyses on the same spindles as the cell advanced from metaphase to anaphase. We determined values for the turnover of kMTs (t1/2 = 7.1 +/- 2.4 min at 30 degrees C) and demonstrated that the turnover of kMTs in metaphase is approximately an order of magnitude slower than that for non-kMTs. In anaphase, kMTs become dramatically more stable as evidenced by a fivefold increase in the fluorescence redistribution half-time (t1/2 = 37.5 +/- 8.5 min at 30 degrees C). Our results also indicate that MT transport slows abruptly at anaphase onset to one-half the metaphase value. In early anaphase, MT depolymerization at the kinetochore accounted, on average, for 84% of the rate of chromosome movement toward the pole whereas the relative contribution of MT transport and depolymerization at the pole contributed 16%. These properties reflect a dramatic shift in the dynamic behavior of kMTs at the metaphase-anaphase transition. A release-capture model is presented in which the stability of kMTs is increased at the onset of anaphase through a reduction in the probability of MT release from the kinetochore. The reduction in MT transport at the metaphase-anaphase transition suggests that motor activity and/or subunit dynamics at the centrosome are subject to modulation at this key cell cycle point.

LAR-PTPase cDNA transfection suppression of tumor growth of neu oncogene-transformed human breast carcinoma cells

The incidence of amplification of neu oncogene-encoded protein tyrosine kinase in human breast cancer strongly supports the concept that protein tyrosine phosphorylation and dephosphorylation are key regulatory mechanisms in the proliferation, differentiation, and neoplastic transformation of breast epithelial cells. We examined the potential regulatory role of protein tyrosine phosphatases (PTPases) in the maintenance of cellular tyrosine phosphorylation by the introduction of leukocyte common-antigen-related PTPase (LAR-PTPase) cDNA into a tumorigenic human breast carcinoma cell line that overexpressed p185neu protein tyrosine kinase. The transfected human breast carcinoma cells expressed elevated levels of LAR-PTPase as assessed by reverse transcription-polymerase chain reaction and by analysis of LAR-PTPase protein. The LAR-PTPase-transfected human breast carcinoma cells had a significantly (P < 0.01) slower proliferation rate in vitro than control-transfected cells. When LAR-PTPase-transfected cells were inoculated into athymic nude mice, a consistent and significant (P < 0.05) suppression of tumor growth was observed. These results provide evidence that a specific PTPase, LAR-PTPase, can play a suppressive regulatory role in the tumor growth of human breast carcinoma cells that overexpress p185neu protein tyrosine kinase.

Enzymes and binding proteins affecting retinoic acid concentrations

Free retinoids suffer promiscuous metabolism in vitro. Diverse enzymes are expressed in several subcellular fractions that are capable of converting free retinol (retinol not sequestered with specific binding proteins) into retinal or retinoic acid. If this were to occur in vivo, regulating the temporal-spatial concentrations of functionally-active retinoids, such as RA (retinoic acid), would be enigmatic. In vivo, however, retinoids occur bound to high-affinity, high-specificity binding proteins, including cellular retinol-binding protein, type I (CRBP) and cellular retinoic acid-binding protein, type I (CRABP). These binding proteins, members of the superfamily of lipid binding proteins, are expressed in concentrations that exceed those of their ligands. Considerable data favor a model pathway of RA biosynthesis and metabolism consisting of enzymes that recognize CRBP (apo and holo) and holo-CRABP as substrates and/or affecters of activity. This would restrict retinoid access to enzymes that recognize the appropriate binding protein, imparting specificity to RA homeostasis; preventing, e.g. opportunistic RA synthesis by alcohol dehydrogenases with broad substrate tolerances. An NADP-dependent microsomal retinol dehydrogenase (RDH) catalyzes the first reaction in this pathway. RDH recognizes CRBP as substrate by the dual criteria of enzyme kinetics and chemical crosslinking. A cDNA of RDH has been cloned, expressed and characterized as a short-chain alcohol dehydrogenase. Retinal generated in microsomes from holo-CRBP by RDH supports cytosolic RA synthesis by an NAD-dependent retinal dehydrogenase (RalDH). RalDH has been purified, characterized with respect to substrate specificity, and its cDNA has been cloned. CRABP is also important to modulating the steady-state concentrations of RA, through sequestering RA and facilitating its metabolism, because the complex CRABP/RA acts as a low Km substrate.