RERG is a novel ras-related, estrogen-regulated and growth-inhibitory gene in breast cancer.

Using microarray analysis, we identified a unique ras superfamily gene, termed RERG (ras-related and estrogen-regulated growth inhibitor), whose expression was decreased or lost in a significant percentage of primary human breast tumors that show a poor clinical prognosis. Importantly, high RERG expression correlated with expression of a set of genes that define a breast tumor subtype that is estrogen receptor-positive and associated with a slow rate of tumor cell proliferation and a favorable prognosis for these cancer patients. RERG mRNA expression was induced rapidly in MCF-7 cells stimulated by beta-estradiol and repressed by tamoxifen treatment. Like Ras, RERG protein exhibited intrinsic GDP/GTP binding and GTP hydrolysis activity. Unlike Ras proteins, RERG lacks a known recognition signal for COOH-terminal prenylation and was localized primarily in the cytoplasm. Expression of RERG protein in MCF-7 breast carcinoma cells resulted in a significant inhibition of both anchorage-dependent and anchorage-independent growth in vitro and inhibited tumor formation in nude mice. These features of RERG are strikingly different from most Ras superfamily GTP-binding pro-teins and suggest that the loss of RERG expression may contribute to breast tumorigenesis.

Identification of a human glioma-associated growth factor gene, granulin, using differential immuno-absorption.

Identification of the genes that are differentially expressed in brain tumor cells but not in normal brain cells is important for understanding the molecular basis of these neurological cancers and for defining possible targets for therapeutic intervention. In an effort to discover potentially antigenic proteins that may be involved in the malignant transformation and progression of human glioblastomas, a novel antibody-based approach was developed to identify and isolate gene products that are expressed in brain tumors versus normal brain tissue. Using this method, whereby tumor-specific antibodies were isolated and used to screen a glioblastoma cDNA expression library, 28 gene products were identified. Nine of these clones had homology to known gene products, and 19 were novel. The expression of these genes in multiple different human gliomas was then evaluated by cDNA microarray hybridization. One of the isolated clones had consistently higher levels of expression (3-30-fold) in brain tumors compared with normal brain. Northern blot analysis and in situ hybridization confirmed this differential overexpression. cDNA sequence analysis revealed that this gene was identical to a relatively new class of growth regulators known as granulins, which have tertiary structures resembling the epidermal growth factor-like proteins. The 2.1-kb granulin mRNA was expressed predominantly in glial tumors, with lower levels in spleen, kidney, and testes, whereas expression was not detected in non-tumor brain tissues. Functional assays using [3H]thymidine incorporation indicated that granulin may be a glial mitogen, as addition of synthetic granulin peptide to primary rat astrocytes and three different early-passage human glioblastoma cultures increased cell proliferation in vitro, whereas increasing concentrations of granulin antibody inhibited cell growth in a dose-dependent manner. The differential expression pattern, tissue distribution, and implication of this glioma-associated molecule in growth regulation suggest a potentially important role for granulin in the pathogenesis and/or malignant progression of primary brain neoplasms.

A humoral response to oligodendrocyte-specific protein in MS: a potential molecular mimic.

OBJECTIVE: To determine the antibody response to oligodendrocyte-specific protein (OSP) in patients with MS. BACKGROUND: OSP is a recently identified CNS-specific myelin protein that is abundant and therefore a candidate autoantigen in MS. METHODS: The presence of anti-OSP antibodies was determined using Western blot analysis, peptide blots, and ELISA in patients with MS and in other neurologic and normal control subjects. RESULTS: Using Western blot analysis, seven patients with relapsing-remitting MS (RRMS) were found to contain anti-OSP antibodies in their CSF that were not present in control subjects. Peptide mapping determined that the antibody response was directed to a seven aa peptide (OSP 114-120), which has 71% homology with several common pathogenic proteins. Using OSP 114-120 as antigen, ELISAs were performed on CSF from 85 MS and 51 control patients. Eighty percent of the samples from RRMS patients followed at the University of California at Los Angeles had an ELISA reading above 0.55 optical density units, whereas all 20 control CSF samples had values less than 0.55 U. Similar results were found in specimens from an outside research bank. ELISAs performed on CSF using homologous viral peptides as antigen showed a close correlation with anti-OSP 114-120 ELISA readings, and in some, the readings were higher than those using OSP peptides. CONCLUSIONS: There is a specific humoral response directed against a region of OSP in RRMS patients that cross-reacts with several common viral peptides. This suggests a possible role for molecular mimicry in the development of MS.

Oligodendrocyte-specific protein peptides induce experimental autoimmune encephalomyelitis in SJL/J mice.

Oligodendrocyte-specific protein (OSP) is a recently isolated and cloned, 207-aa, hydrophobic, four-transmembrane protein found in CNS myelin. It represents approximately 7% of total myelin protein. The OSP cDNA sequence has no significant homology with previously reported genes, but the predicted protein structure suggests that OSP is a CNS homologue of peripheral myelin protein-22. We previously reported the presence of anti-OSP Abs in the cerebrospinal fluid of relapsing-remitting multiple sclerosis (MS) patients, but not control patient groups. In this study, we tested the ability of a panel of 20-mer peptides with 10-aa overlaps, representing the sequence of murine OSP, to induce experimental autoimmune encephalomyelitis (EAE), an animal model for MS. SJL mice challenged with murine OSP peptides 52-71, 82-101, 102-121, 142-161, 182-201, and 192-207 exhibited clinical EAE. OSP:52-71 elicited severe relapsing-remitting EAE in some individuals. All other encephalitogenic peptides elicited, at most, a loss of tail tonicity from which the mice most often completely recovered. Mononuclear cell infiltrates and focal demyelination characteristic of EAE were evident. T cell proliferative responses were seen with all encephalitogenic peptides except 142-161 and 182-201. OSP peptides 72-91 and 132-151 did not cause clinical EAE, but did elicit robust proliferative responses. B10.PL and PL/J mice challenged with the same OSP peptide doses as SJL mice did not exhibit clinical EAE. These results in the SJL EAE model, together with the results from MS patient clinical samples, make OSP a promising candidate for autoantigenic involvement in MS.

Hospitalization in an urban homeless population: the Honolulu Urban Homeless Project.

OBJECTIVE: To determine the rate and estimate the cost of hospitalization in a defined urban homeless population. DESIGN: Retrospective chart review. SETTING: Kalihi-Palama Health Clinic Health Care for the Homeless Project, Hawaii State Hospital and seven acute care hospitals in Honolulu, Hawaii. PATIENTS: A total of 1751 homeless clients contacted between 1 December 1988 and 30 November 1990. MEASUREMENTS AND MAIN RESULTS: A total of 1751 individuals were studied for an aggregate of 871.3 person-years. Five hundred sixty-four hospitalizations were identified: ninety-two to the state psychiatric hospital and 472 to acute care hospitals. The age- and sex-adjusted hospitalization rate for acute care hospitals was 542/1000 person-years (compared with the state rate of 96/1000 person-years). Homeless persons were admitted to acute care hospitals for 4766 days compared with a predicted 640 days. The age- and sex-adjusted rate of admission to the state psychiatric hospital was 105/1000 person-years (compared with the state rate of 0.8/1000 person-years). Homeless persons were admitted to the state psychiatric hospital for 3837 days compared with a predicted 139 days. CONCLUSIONS: Homeless individuals in this study were hospitalized in acute care and psychiatric hospitals far more frequently than were members of the general population.