Veterinary and human biobanking practices: enhancing molecular sample integrity.

Animal models have historically informed veterinary and human pathophysiology. Next-generation genomic sequencing and molecular analyses using analytes derived from tissue require integrative approaches to determine macroanalyte integrity as well as morphology for imaging algorithms that can extend translational applications. The field of biospecimen science and biobanking will play critical roles in tissue sample collection and processing to ensure the integrity of macromolecules, aid experimental design, and provide more accurate and reproducible downstream genomic data. Herein, we employ animal experiments to combine protein expression analysis by microscopy with RNA integrity number and quantitative measures of morphologic changes of autolysis. These analyses can be used to predict the effect of preanalytic variables and provide the basis for standardized methods in tissue sample collection and processing. We also discuss the application of digital imaging with quantitative RNA and tissue-based protein measurements to show that genomic methods augment traditional in vivo imaging to support biospecimen science. To make these observations, we have established a time course experiment of murine kidney tissues that predicts conventional measures of RNA integrity by RIN analysis and provides reliable and accurate measures of biospecimen integrity and fitness, in particular for time points less than 3 hours post-tissue resection.

Differential oncogenic potential of activated RAS isoforms in melanocytes.

RAS genes are mutated in approximately 30% of all human cancers. Interestingly, there exists a strong bias in favor of mutation of only one of the three major RAS genes in tumors of different cellular origins. NRAS mutations occur in approximately 20% of human melanomas, whereas HRAS and KRAS mutations are rare in this disease. To define the mechanism(s) responsible for this preference in melanocytes, we compared the transformation efficiencies of mutant NRAS and KRAS in immortal, non-transformed Ink4a/Arf-deficient melanocytes. NRAS mutation leads to increased cellular proliferation and is potently tumorigenic. In contrast, KRAS mutation does not enhance melanocyte proliferation and is only weakly tumorigenic on its own. Although both NRAS and KRAS activate mitogen-activated protein kinase signaling, only NRAS enhances MYC activity in these cells. Our data suggest that the activity of specific RAS isoforms is context-dependent and provide a possible explanation for the prevalence of NRAS mutations in melanoma. In addition, understanding this mechanism will have important implications for cancer therapies targeting RAS pathways.

Pathologic human GR mutant has a transdominant negative effect on the wild-type GR by inhibiting its translocation into the nucleus: importance of the ligand-binding domain for intracellular GR trafficking.

The syndrome of familial or sporadic glucocorticoid resistance is characterized by hypercortisolism without the clinical stigmata of Cushing syndrome. This condition is usually caused by mutations of the human GR, a ligand-activated transcription factor that shuttles between the cytoplasm and the nucleus. A pathological human mutant receptor, in which Ile was replaced by Asn at position 559, had negligible ligand binding, was transcriptionally extremely weak, and exerted a transdominant negative effect on the transactivational activity of the wild-type GR, causing severe glucocorticoid resistance in the heterozygous state. To understand the mechanism of this mutant's trans-dominance, we constructed several N-terminal GR fusion chimeras to green fluorescent protein (GFP) and demonstrated that their transactivational activities were similar to those of the original proteins. The GFP-human (h) GRalphaI559N chimera was predominantly localized in the cytoplasm, and only high doses or prolonged glucocorticoid treatment triggered complete nuclear import that took 180 vs. 12 min for GFP-hGRalpha. Furthermore, hGRalphaI559N inhibited nuclear import of the wild-type GFP-hGRalpha, suggesting that its trans-dominant activity on the wild-type receptor is probably exerted at the process of nuclear translocation. As the ligand-binding domain (LBD) of the GR appears to play an important role in its nucleocytoplasmic shuttling, we also examined two additional GR-related fusion proteins. The natural hGR isoform beta (GFP-hGRbeta), containing a unique LBD, was transactivation-inactive, moderately trans-dominant, and localized instantaneously and predominantly in the nucleus; glucocorticoid addition did not change its localization. Similarly, GFP-hGR514, lacking the entire LBD, was instantaneously and predominantly localized in the nucleus regardless of presence of glucocorticoids. Using a cell fusion system we demonstrated that nuclear export of GFP-hGRalphaI559N (250 min) and GFP-hGRbeta (300 min) was drastically impaired compared with that of GFP-hGRalpha (50 min) and GFP-hGR514 (50 min), suggesting that an altered LBD may impede the exit of the GR from the nucleus. We conclude that the trans-dominant negative effect of the pathological mutant is exerted primarily at the translocation step, whereas that of the natural isoform beta is exerted at the level of transcription.

Differential expression and responsiveness of chemokine receptors (CXCR1-3) by human microvascular endothelial cells and umbilical vein endothelial cells.

The basis for the angiogenic effects of CXC chemokines such as interleukin 8 (IL-8) and for angiostatic chemokines such as interferon-inducible protein 10 (IP-10) has been difficult to assess. We recently reported, based on an RNase protection assay, that human umbilical vein endothelial cells (HUVECs) did not express detectable mRNA for the IL-8 receptors CXCR1 and CXCR2. This raised the possibility of heterogeneity of receptor expression by different endothelial cell (ECs) types. Since systemic angiogenesis induced by IL-8 would more likely involve microvessel ECs, we investigated CXC receptor expression on human microvascular dermal endothelial cells (HMECs). By confocal microscopy and immunofluorescence we observed that HMECs consistently expressed high levels of CXCR1 and CXCR4 (mean fluorescence intensity of 261+/-22.1 and 306.2+/-19, respectively) and intermediate levels of CXCR3 and CXCR2 (173.9+/-30. 2 and 156+/-30.9, respectively). In contrast, only a small proportion of HUVEC preparations expressed low levels of CXCR1, -2, and -3 (66+/-19.9; 49+/-15, and 81.4+/-17.9, respectively). However, both HMECs and HUVECs expressed equal levels of CXCR4. As expected, HMECs had more potent chemotactic responses to IL-8 than HUVECs, and this was correlated with the levels of IL-8 receptors on the ECs. Antibodies to CXCR1 and CXCR2 each had inhibitory effects on chemotaxis of HMECs to IL-8, indicating that both IL-8 receptors contributed to the migratory response of these cells toward IL-8. Assessment of the functional capacity of CXCR3 unexpectedly revealed that HMECs migrated in response to relatively higher concentrations (100-500 ng/ml) of each of the 'angiostatic' chemokines IP-10, ITAC, and MIG. Despite this, the 'angiostatic' chemokines inhibited the chemotactic response of HMECs to IL-8. IL-8 and SDF-1alpha but not IP-10 induced calcium mobilization in adherent ECs, suggesting that signaling events associated with calcium mobilization are separable from those required for chemotaxis. Taken together, our data indicated that functional differences among EC types is dependent on the level of the expression of CXC chemokine receptors. Whether this heterogeneity in receptor expression by ECs reflects distinct differentiation pathways remains to be established.

Algorithms for quantitation of protein expression variation in normal versus tumor tissue as a prognostic factor in cancer: Met oncogene expression, and breast cancer as a model.

BACKGROUND: Immunohistochemistry and immunofluorescence (IF) assays frequently rely on subjective observer evaluation for grading. The aim of our study was to develop an objective quantitative index based on confocal laser scanning microscopy (CLSM) and image analysis of an IF assay to determine alteration in protein expression levels in normal versus tumor tissue. The relative levels of Met expression, a prognostic factor in breast cancer, were used as a model for evaluating image analysis algorithms. METHODS: Primary human breast cancer biopsies were collected. Sections containing tumor and adjacent uninvolved normal regions were immunostained for Met and digital images were acquired by CLSM. Subsequently, the digital data were manipulated using several different algorithms to calculate prognostic indexes. The results were correlated with the clinical outcome to determine the prognostic value of these indexes. RESULTS: Different algorithms were used to obtain quantitative indexes to evaluate the relative levels of Met expression. We report a statistical correlation between patient prognosis and relative Met level in normal versus tumor tissue as determined by three distinct algorithms using Kaplan-Meier analysis (log-rank): calculations based on intensity levels differences DV (P = 0.002), DIntensity (P = 0.014), and entropy divergence (Dentropy; P = 0.0023). CONCLUSIONS: Using adjacent normal tissue as an internal reference, a quantitative index of tumor Met level divergence can be objectively determined to have a prognostic value. Moreover, this methodology can be used for other proteins in a variety of different diseases.

Dominant negative Met reduces tumorigenicity-metastasis and increases tubule formation in mammary cells.

Activation of the Met tyrosine kinase growth factor receptor by its ligand HGF/SF has been shown to increase in vitro invasiveness in epithelial cell lines. To study the effect of Met-HGF/SF signaling in breast cancer cells, we transfected met, hgf/sf and dominant negative (DN) forms of met into the poorly differentiated metastatic murine mammary adenocarcinoma cell line DA3. These cells express moderate levels of endogenous Met, which is rapidly phosphorylated in response to HGF/SF treatment. Met+hgf/sf transfection results in significantly increased tumorigenic and metastatic activity in vivo accompanied by reduced tubule formation. DA3 cells transfected with DN forms of Met (DN-DA3) exhibit reduced Met phosphorylation following exposure to HGF/SF. Furthermore, as compared to the parental cells, the DN-DA3 cells exhibit diminished in vitro scattering and invasiveness, while in vivo they display greatly reduced tumorigenicity and spontaneous metastasis. Tumors emanating from DN-DA3 cells injected to BALB/C mice are highly differentiated and display extensive tubule formation. These results suggest that Met-HGF/SF signaling is a determining factor in the delicate balance between differentiation/tubule formation and tumorigenicity-metastasis. Oncogene (2000) 19, 2386 - 2397

The von Hippel-Lindau tumor suppressor targets to mitochondria.

Subcellular localization of von Hippel-Lindau (VHL) tumor suppressor may clarify its role in tumorigenesis. In rat kidney, we observed a granular cytoplasmic immunostaining of VHL, as seen in human tissues. The green fluorescent protein (GFP)-tagged VHL also appeared as cytoplasmic granules in vitro and was colocalized with a mitochondrion-selective dye. Immunogold electron microscopy localized VHL specifically to the mitochondrion. Mitochondria retaining GFP-VHL fusion protein, mimicking an insertional VHL mutant, displayed abnormal phenotypes. Among these, small mitochondria have been observed in clear cell renal carcinomas known to have frequent VHL alterations. Thus, VHL may contribute to tumorigenesis through mitochondria-based action.

The multidrug-resistant phenotype associated with overexpression of the new ABC half-transporter, MXR (ABCG2).

Mechanisms of drug resistance other than P-glycoprotein are of increasing interest as the list of newly identified members of the ABC transport family has grown. We sought to characterize the phenotype of the newly discovered ABC transporter encoded by the mitoxantrone resistance gene, MXR, also known as ABCP1 or BCRP. The pharmacodynamics of mitoxantrone and 12 other fluorescent drugs were evaluated by confocal microscopy in four multidrug-resistant human colon (S1) and breast (MCF-7) cancer cell lines. We utilized two sublines, MCF-7 AdVp3000 and S1-M1-80, and detected overexpression of MXR by PCR, immunoblot assay and immunohistochemistry. These MXR overexpressing sublines were compared to cell lines with P-glycoprotein- and MRP-mediated resistance. High levels of cross-resistance were observed for mitoxantrone, the anthracyclines, bisantrene and topotecan. Reduced levels of mitoxantrone, daunorubicin, bisantrene, topotecan, rhodamine 123 and prazosin were observed in the two sublines with high MXR expression. Neither the P-glycoprotein substrates vinblastine, paclitaxel, verapamil and calcein-AM, nor the MRP substrate calcein, were extruded from MCF-7 AdVp3000 and S1-M1-80 cells. Thus, the multidrug-resistant phenotype due to MXR expression is overlapping with, but distinct from, that due to P-glycoprotein. Further, cells that overexpress the MXR protein seem to be more resistant to mitoxantrone and topotecan than cells with P-glycoprotein-mediated multidrug resistance. Our studies suggest that the ABC half-transporter, MXR, is a potent, new mechanism for conferring multiple drug resistance. Definition of its mechanism of transport and its role in clinical oncology is required.

Activation of human T lymphocytes is inhibited by peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. PPARgamma co-association with transcription factor NFAT.

T lymphocyte activation is highlighted by the induction of interleukin-2 (IL-2) gene expression, which governs much of the early lymphocyte proliferation responses. Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. PPARgamma mRNA expression was found in human peripheral blood T lymphocytes, raising the possibility of PPARgamma involvement in the regulation of T cell function. Here we show that PPARgamma ligands, troglitazone and 15-deoxy-Delta(12,14) prostaglandin J(2), but not PPARalpha agonist Wy14643, inhibited IL-2 production and phytohemagglutinin-inducible proliferation in human peripheral blood T-cells in a dose-dependent manner. This inhibitory effect on IL-2 was restricted to the PPARgamma2-expressing, not the PPARgamma-lacking, subpopulation of transfected Jurkat cells. The activated PPARgamma physically associates with transcriptional factor NFAT regulating the IL-2 promoter, blocking NFAT DNA binding and transcriptional activity. This interaction with T-cell-specific transcription factors indicates an important immunomodulatory role for PPARgamma in T lymphocytes and could suggest a previously unrecognized clinical potential for PPARgamma ligands as immunotherapeutic drugs to treat T-cell-mediated diseases by targeting IL-2 gene expression.

Targeted disruption of stat6 DNA binding activity by an oligonucleotide decoy blocks IL-4-driven T(H)2 cell response.

The transcription factor, signal transducer and activator of transcription (Stat) 6, regulates T(H)2-lymphocyte activity by controlling the expression and responsiveness to interleukin (IL)-4, which plays a key role in numerous allergic maladies. Therefore, we sought to use a phosphorothiolate cis-element decoy to target disruption of Stat6 transcriptional activity. Here we showed that the Stat6 decoy potently ablated the messenger RNA expression and production of IL-4, but not of several other cytokines. The Stat6 decoy functionally disrupted IL-4-inducible cell proliferation of murine T(H)2 cells and primary human CD4(+) T lymphocytes. Specificity of the decoy was demonstrated by its ability to directly block Stat6 binding to a cis-element probe and transactivation, but not affect Stat6 tyrosine phosphorylation or expression of the IL-4 receptor chains. Moreover, the decoy failed to inhibit non-Stat6-dependent signaling pathways since IL-2 was competent to induce cell proliferation and activation of Stats 1, 3, and 5a/b. With the use of laser scanning confocal microscopy, fluorescently tagged Stat6 decoy was detectable in the cytoplasm and nucleus; however, greater levels of oligonucleotide were present in the latter following IL-4 treatment. Taken together, these data suggest that IL-4-driven T(H)2 cell activity can be preferentially restricted via targeted disruption of Stat6 by a novel and specific decoy strategy that may possess gene therapeutic potential. (Blood. 2000;95:1249-1257)

Regulation of P311 expression by Met-hepatocyte growth factor/scatter factor and the ubiquitin/proteasome system.

P311 is a mouse cDNA originally identified for its high expression in late-stage embryonic brain and adult cerebellum, hippocampus, and olfactory bulb. The protein product of P311, however, had not been identified previously, and its function remains unknown. We report here that P311 expression is regulated at multiple levels by pathways that control cellular transformation. P311 mRNA expression was decreased sharply in both neural and smooth muscle cells when the cells were transformed by coexpression of the oncogenic tyrosine kinase receptor Met and its ligand hepatocyte growth factor/scatter factor. The P311 mRNA was found to encode an 8-kDa polypeptide that was subject to rapid degradation by the lactacystin-sensitive ubiquitin/proteasome system and an unidentified metalloprotease, resulting in a protein half-life of about 5 min. These data suggest that P311 expression is dramatically decreased by several pathways that regulate cellular growth.

Plasmodium yoelii: cloning and characterization of the gene encoding for the mitochondrial heat shock protein 60.

Heat shock proteins are a highly conserved group of proteins required for the correct folding, transport, and degradation of other proteins in vivo. The Hsp70, Hsp90, and Hsp60 families are among the most widely studied families. Hsp60 is found in eubacteria, mitochondria, and chloroplasts, where, in cooperation with Hsp10, it participates in protein folding and translocation of proteins to the organelles. We have cloned and characterized the Hsp60 gene of Plasmodium yoelii (PyHsp60). PyHsp60 is a single-copy gene, located on chromosome 9, 10, or 11. The PyHsp60 cDNA sequence showed an open reading frame of 1737 nucleotides that codes for a polypeptide of 579 amino acids, with 93% amino acid identity to Plasmodium-falciparum Hsp60 (PfHsp60). Cloning and sequencing of a genomic PCR clone showed the presence of a 201-bp intron, located 141 bp downstream of the ATG codon. A single, heat-inducible, 2.3-kb transcript was detected in Northern blots of RNA isolated from blood stage parasites. Mouse antisera raised against a DNA vaccine vector that expresses PyHsp60 recognized sporozoites and liver- and blood-stage parasites by indirect fluorescent antibody test (IFAT). By Western blot, these antisera reacted with the mycobacterial Hsp65 and recognized a protein of approximately 65 kDa in P. yoelii sporozoites and P. falciparum blood stages. These results show that PyHsp60 and PfHsp60 genes are homologous and that of the PyHsp60 gene encodes a heat-inducible, intracellular protein that is expressed in several of the developmental stages of P. yoelii.

Alteration of Met protooncogene product expression and prognosis in breast carcinomas.

OBJECTIVE: To objectively quantify the expression and prognostic implications of the met protooncogene product (Met) in human breast cancer. STUDY DESIGN: One hundred eighty-two cases of primary human breast cancer were collected. Both the normal and tumor portions of the original surgical pathology specimen were immunostained for Met and imaged using laser scanning confocal microscopy. Then the cases were ranked according to relative concentrations of normal and tumor Met expression. Subsequently, they were quantified using image analysis and the results correlated with clinical outcome to determine the prognostic value of relative levels of Met. RESULTS: Using a quantitative index to evaluate the relative levels of Met expression, high levels of Met expression in the tumor as compared with the adjacent normal ducts predicted poor prognosis for overall survival and metastasis-free survival. The risk ratio for elevated Met expression was 3.94 (P = .0009). This new method also allows determination of the clinical relevance of low levels of Met in the tumor. The overall survival between the patient population with higher, lower and unchanged levels of Met in normal tissue as compared to tumor were significantly different (P = .0020). CONCLUSION: Our studies suggest that in a subpopulation of node-negative breast cancer patients, either high or low levels of Met in tumor tissue relative to normal tissue is an indicator of poor overall survival (P = .0068). Thus, Met expression could be useful for identifying node-negative patients who could benefit from adjuvant therapy.

Comparison of c-met expression in ovarian epithelial tumors and normal epithelia of the female reproductive tract by quantitative laser scan microscopy.

The transmembrane tyrosine kinase receptor c-met with its ligand, hepatocyte growth factor/scatter factor (HGF/SF), acts as a mitogen, motogen, and morphogen in many normal epithelia. HGF/SF-met signaling has also been implicated in neoplastic progression and metastasis. In this study, immunofluorescence staining and quantitative laser scanning confocal microscopy were used to measure c-met expression in ovarian surface epithelial tumors from 17 oophorectomy specimens. These specimens were from patients aged 25 to 81 (mean age, 52) and included 10 malignant tumors, 4 borderline tumors, and five benign tumors including a Brenner tumor. For comparison, c-met expression was measured in normal tissues from the same patients, including 4 ovarian surface epithelia, 4 fallopian tube epithelia, 2 endometria, and 3 endocervical epithelia, as well as 3 cases of endometriosis. Relative pixel intensity values of c-met expression ranged from 0.4 in a normal ovarian surface epithelium to 22.3 in a borderline serous tumor. Malignant tumors (mean, 9.6) and borderline tumors (mean, 12.9) had higher average c-met expression levels than normal tissues (mean, 3.6) and endometriosis (mean, 1.8). The expression levels of benign tumors were intermediate (mean, 7.9). Among the normal tissues, c-met expression in fallopian tubes (mean, 8.2; range, 3.4-12.9) was higher than that of the other normal epithelia (mean, 1.6; range, 0.4-4.3). In eight cases where both normal and malignant tissues were sampled, c-met expression was significantly greater in malignant than in normal epithelia (P = 0.01). These findings indicate that c-met plays a role in the biology of the normal tissues examined. They confirm that its expression increases in the malignant progression of ovarian surface epithelial tumors, and suggest that increases comparable to those in frankly malignant carcinomas have already been reached in borderline lesions, ie, early in the neoplastic process.

Met-HGF/SF mediates growth arrest and differentiation in T47D breast cancer cells.

Hepatocyte growth factor/scatter factor (HGF/SF) is a pluripotent growth factor that exerts mitogenic, motogenic, and morphogenic effects. To elucidate the cellular mechanisms underlying the pluripotent function of this growth factor, T47D human breast cancer cells were transfected with human hgf/sf. The hgf/sf-positive clones exhibited different levels of biologically functional HGF/SF expression and up-regulation of endogenous Met (HGF/SF receptor) expression. In addition, a constitutive phosphorylation of the receptor on tyrosine residues was detected, establishing a Met-HGF/SF autocrine loop. The autocrine activation of Met caused marked inhibition in cell growth accompanied by cell accumulation at G0/G1. These cells underwent terminal cell differentiation as determined by morphological changes, synthesis of milk proteins such as beta-casein and alpha-lactalbumin, and production of lipid vesicles. Our results demonstrate that Met-HGF/SF, an oncogenic signal transduction pathway, is capable of inducing growth arrest and differentiation in certain breast cancer cells and, thus, may have potential as therapeutic and/or prognostic tools in breast cancer treatment.

Direct interaction of microtubule- and actin-based transport motors.

The microtubule network is thought to be used for long-range transport of cellular components in animal cells whereas the actin network is proposed to be used for short-range transport, although the mechanism(s) by which this transport is coordinated is poorly understood. For example, in sea urchins long-range Ca2+-regulated transport of exocytotic vesicles requires a microtubule-based motor, whereas an actin-based motor is used for short-range transport. In neurons, microtubule-based kinesin motor proteins are used for long-range vesicular transport but microtubules do not extend into the neuronal termini, where actin filaments form the cytoskeletal framework, and kinesins are rapidly degraded upon their arrival in neuronal termini, indicating that vesicles may have to be transferred from microtubules to actin tracks to reach their final destination. Here we show that an actin-based vesicle-transport motor, MyoVA, can interact directly with a microtubule-based transport motor, KhcU. As would be expected if these complexes were functional, they also contain kinesin light chains and the localization of MyoVA and KhcU overlaps in the cell. These results indicate that cellular transport is, in part, coordinated through the direct interaction of different motor molecules.

Evidence for a role of Met-HGF/SF during Ras-mediated tumorigenesis/metastasis.

Aberrations in Met-hepatocyte growth factor/scatter factor (HGF/SF) signaling have been implicated in the acquisition of tumorigenic and metastatic phenotypes. Here we show that murine NIH3T3 and C127 cells transformed by the Ras oncogene overexpress the Met receptor, resulting in enhanced HGF/SF-mediated responses in vitro including invasion through basement membrane. Accompanying the increase in Met in ras-transformed NIH3T3 cells, there is a decrease in endogenous HGF/SF expression as previously observed in cells exogenously overexpressing Met. However, subcutaneously grown tumors and experimental lung metastases derived from these cells express significantly higher levels of endogenous HGF/SF together with high levels of Met. These results suggest Met-HGF/SF signaling enhances tumor growth and metastasis of Ras-transformed NIH3T3 cells.

HIV-1 envelope gp120 inhibits the monocyte response to chemokines through CD4 signal-dependent chemokine receptor down-regulation.

Since HIV-1 infection results in severe immunosuppression, and the envelope protein gp120 has been reported to interact with some of the chemokine receptors on human T lymphocytes, we postulated that gp120 may also affect monocyte activation by a variety of chemokines. This study shows that human peripheral blood monocytes when preincubated with gp120 either purified from laboratory-adapted strains or as recombinant proteins exhibited markedly reduced binding, calcium mobilization, and chemotactic response to chemokines. The gp-120-pretreated monocytes also showed a decreased response to FMLP. This broad inhibition of monocyte activation by chemoattractants required interaction of gp120 with CD4, since the effect of gp120 was only observed in CD4+ monocytes and in HEK 293 cells only if cotransfected with both chemokine receptors and an intact CD4, but not a CD4 lacking its cytoplasmic domain. Anti-CD4 mAbs mimicked the effect of gp120, and both anti-CD4 Ab and gp120 caused internalization of CXCR4 in HEK 293 cells provided they also expressed CD4. Staurosporine blocked the inhibitory effect of gp120 on monocytes, suggesting that cellular signaling was required for gp120 to inhibit the response of CD4+ cells to chemoattractants. Our study demonstrates a broad suppressive effect of gp120 on monocyte activation by chemoattractants through the down-regulation of cell surface receptors. Thus, gp120 may be used by HIV-1 to disarm the monocyte response to inflammatory stimulation.

Opiates transdeactivate chemokine receptors: delta and mu opiate receptor-mediated heterologous desensitization.

An intact chemotactic response is vital for leukocyte trafficking and host defense. Opiates are known to exert a number of immunomodulating effects in vitro and in vivo, and we sought to determine whether they were capable of inhibiting chemokine-induced directional migration of human leukocytes, and if so, to ascertain the mechanism involved. The endogenous opioid met-enkephalin induced monocyte chemotaxis in a pertussis toxin-sensitive manner. Met-enkephalin, as well as morphine, inhibited IL-8-induced chemotaxis of human neutrophils and macrophage inflammatory protein (MIP)-1alpha, regulated upon activation, normal T expressed and secreted (RANTES), and monocyte chemoattractant protein 1, but not MIP-1beta-induced chemotaxis of human monocytes. This inhibition of chemotaxis was mediated by delta and micro but not kappa G protein-coupled opiate receptors. Calcium flux induced by chemokines was unaffected by met-enkephalin pretreatment. Unlike other opiate-induced changes in leukocyte function, the inhibition of chemotaxis was not mediated by nitric oxide. Opiates induced phosphorylation of the chemokine receptors CXCR1 and CXCR2, but neither induced internalization of chemokine receptors nor perturbed chemokine binding. Thus, inhibition of chemokine-induced chemotaxis by opiates is due to heterologous desensitization through phosphorylation of chemokine receptors. This may contribute to the defects in host defense seen with opiate abuse and has important implications for immunomodulation induced by several endogenous neuropeptides which act through G protein-coupled receptors.

Development and characterization of a mouse prostate adenocarcinoma cell line: ductal formation determined by extracellular matrix.

BACKGROUND: Tumor vaccines show promise as a new approach for treating cancer. We have developed a murine prostate cancer cell line which can be used to study growth factor and extracellular matrix regulation of prostate differentiation and will be useful for generating tumor vaccines using the C3(1)/TAG transgenic model of prostate cancer. METHODS: Pr-14 cells were established in defined growth media (GM) and grown in GM, GM + 2% fetal bovine serum (FBS) or DMEM + 10% FBS on plastic, collagen, or Matrigel. Immunofluorescence and Western blot analyses were performed using antibodies to cytokeratin, vimentin, SV40 large T-antigen, and androgen receptor (AR). RESULTS: Pr-14 cells are cytokeratin-positive, vimentin-negative, and express SV40 large T-antigen. These cells are tumorigenic when injected into athymic nude mice and appear to be androgen-independent. Pr-14 cell lines are nontumorigenic when injected into syngeneic FVB/N mice, but form tumors in transgenic TAG-expressing FVB/N mice. Cell growth and morphology are dependent on media composition which determines whether ductal or acinar structures form when grown on Matrigel. CONCLUSIONS: The mouse prostate adenocarcinoma cell line, Pr-14, undergoes alterations in the state of differentiation dependent upon serum concentration when grown on Matrigel. The Pr-14 cell line is a useful reagent to study prostate cell/extracellular matrix interactions, and for immunotherapy and cancer vaccine studies in C3(1)/TAG transgenic mice.