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ABC transporters are highly conserved and represent a major protective mechanism for barrier tissues as well as adult tissue stem cells. Emerging data support the existence of a cancer stem cell that shares features of tissue stem cells, including the ability to self-renew and undergo dysregulated differentiation. Here we show that a rare population of cells coexpressing MDR transporters and stem cell markers is a common feature across therapy-naive epithelial cancers as well as normal epithelial tissue. MDR+ and MDR- candidate tumor stem and progenitor populations were all capable of generating highly anaplastic transplantable human tumors in NOD/SCID. The finding that rare cells bearing stem cell markers and having intrinsic MDR expression and activity are already present within the tumorigenic compartment before treatment with cytotoxic agents is of critical importance to cancer therapy. Just as damaged normal epithelial tissues regenerate after chemotherapy by virtue of highly protected resting tissue stem cells, the existence of malignant counterparts in therapy-naive epithelial cancers suggests a common mechanism by which normal and tumor stem cells protect themselves against toxic injury.

Normal pregnancy has been described as both a pro-inflammatory condition and a T helper (Th)2-dominated state. Deviations in the percentage of different subpopulations of circulating leukocytes have been detected, although with conflicting results. This study was designed to analyse further the phenotype of subpopulations of peripheral blood leukocytes in normal pregnant women.Whole-blood flow cytometry was used to differentiate subsets of leukocytes using directly labeled monoclonal antibodies to specific cell surface antigens and to a panel of activation-associated markers in 33 normal pregnant women in their third trimester and in 26 non-pregnant controls.We found a significant increase in the proportion of granulocytes and of CD8+ T lymphocytes during pregnancy. Up-regulation of the expression of adhesion molecules was observed on granulocytes, monocytes and T lymphocytes.Pregnancy alters the representation of leukocyte subpopulations in the maternal circulation and is associated with systemic activation of leukocytes.

Although leukocytes do not possess significant numbers of ovarian steroid hormone receptors, their numbers in the endometrium vary consistently, relative to the menstrual cycle. The possibility that cell types within the endometrium express leukocyte-attracting genes in response to ovarian hormones was investigated.Endometrial biopsies were collected 10 days post-leutinizing hormone surge; the cell types were separated and cultured individually for 5 days in the presence of increasing amounts of estrogen or progesterone. Following culture, RNA was collected from cells and reverse-transcription-polymerase chain reaction was used to determine relative levels of gene expression of monocyte chemotactic proteins (MCP)-1, -2, and -3, and interleukin (IL)-12 p35 and p40.Although both endometrial stroma and glands were able to make MCP mRNA, steady-state levels of gene expression did not vary significantly relative to hormone treatment. The same was found for the p35 molecule of the IL-12 gene; however, differences were observed for the p40 subunit.Within the human endometrium, chemokines other than MCP and IL-12 are most likely responsible for cycle-related leukocyte recruitment.

Preeclampsia is the leading cause of maternal morbidity and premature fetal delivery in the United States, most likely involving the immune system in disease genesis. In this report, we tested the hypothesis that a superantigen phenomenon is an important factor in the pathogenesis of the disease.A semi-quantitative polymerase chain reaction (PCR) was used to assess T-cell receptor (TCR) beta chain variable (Vbeta) regions as an indicator of T-cell expansion in both peripheral blood and basal plate of preeclamptic patients. All the subjects were also molecularly typed to identify their HLA-class II alleles.In peripheral blood of the majority of the patients, there was a high abundance of the Vbeta4 gene family, which was not observed in the control group. Polyclonality of this Vbeta gene family was confirmed by analysis of the Valpha chain and the complementary determining region 3 (CDR3). The majority of patients carried the Human Leukocyte Antigens (HLA)-DRB1*13 allele.We present evidence for the existence of a superantigen-like effect in at least a subset of patients with preeclampsia.

Embryonic implantation and maintenance of pregnancy is influenced by the maternal immunological response. Type 2 T-helper (Th2) cells secrete interleukins 4, 5, 6 and 10 and are associated with suppression of cell-mediated immunity. Temporal changes in the expression of these cytokines were detectable by immunohistochemistry throughout the menstrual cycle. In pregnancy, 10-fold or greater increases in interleukin 6 and 10 secretion were detectable by enzyme-linked immunoassay compared with the non-pregnant state. The pattern of expression of Th2 cytokines suggests that progesterone may influence endometrial cytokine secretion. During pregnancy, Th2 expression paralleled that of vimentin, a stromal cell marker, suggesting that these cells may be a principal source of Th2 cytokines may be a mechanism of suppressing cell-mediated immunity in the endometrium, which may in turn enhance embryonic implantation and maintenance of pregnancy.

By modifying current cDNA cloning and electroporation methods, large and representative murine cDNA libraries were synthesized from 10 to 100 ng mRNA isolated from unfertilized egg and preimplantation mouse embryos. High cloning efficiency is essential for complete representation of genes expressed in egg and preimplantation embryos and for the isolation of stage-specific genes using subtractive hybridization. Because the mouse embryo contains no more than 50 pg of poly(A)+ mRNA at any stage of preimplantation development, approximately 5000-10,000 embryos are required to obtain enough mRNA to synthesize libraries using current methods. To obtain a representative library that also includes rare transcripts, the size of the library should be at least 10(6) clones. The average percent conversion of mRNA to single-stranded cDNA was 20-40%, so that a cloning efficiency of nearly 2 x 10(8) cfu/microgram cDNA is required for such a cDNA library. No previous methods have provided directional cloning of cDNA into plasmids with these high efficiencies. The advent of electroporation methods for the introduction of nucleic acids into bacteria has made possible the use of standard plasmid vectors for high-efficiency cDNA cloning. Plasmid vectors are currently available that can accommodate the directional cloning of cDNA such that T7 and T3 RNA polymerase promoter sequences can be used to generate sense and anti-sense transcripts for subtractive hybridization and riboprobe synthesis. The cDNA libraries we derived using this methodology are a reusable and abundant source of genetic information about the control of preimplantation development. Specialized subtractive cDNA libraries enriched for genes expressed exclusively at a predetermined time in development give access to genes expressed in a stage-specific manner. The ability to construct new cDNA libraries from limited amounts of starting material ensures the provision of new and important resources for the identification and study of novel genes or gene families, and it is an important new tool for understanding the molecular control of mammalian development.

By modifying current cDNA cloning and electroporation methods, large and representative murine cDNA libraries were synthesized from 10 to 100 ng mRNA isolated from unfertilized egg and preimplantation mouse embryos. High cloning efficiency is essential for complete representation of genes expressed in egg and preimplantation embryos and for the isolation of stage-specific genes using subtractive hybridization. Because the mouse embryo contains no more than 50 pg of poly(A)+ mRNA at any stage of preimplantation development, approximately 5000-10,000 embryos are required to obtain enough mRNA to synthesize libraries using current methods. To obtain a representative library that also includes rare transcripts, the size of the library should be at least 10(6) clones. The average percent conversion of mRNA to single-stranded cDNA was 20-40%, so that a cloning efficiency of nearly 2 x 10(8) cfu/microgram cDNA is required for such a cDNA library. No previous methods have provided directional cloning of cDNA into plasmids with these high efficiencies. The advent of electroporation methods for the introduction of nucleic acids into bacteria has made possible the use of standard plasmid vectors for high-efficiency cDNA cloning. Plasmid vectors are currently available that can accommodate the directional cloning of cDNA such that T7 and T3 RNA polymerase promoter sequences can be used to generate sense and anti-sense transcripts for subtractive hybridization and riboprobe synthesis. The cDNA libraries we derived using this methodology are a reusable and abundant source of genetic information about the control of preimplantation development. Specialized subtractive cDNA libraries enriched for genes expressed exclusively at a predetermined time in development give access to genes expressed in a stage-specific manner. The ability to construct new cDNA libraries from limited amounts of starting material ensures the provision of new and important resources for the identification and study of novel genes or gene families, and it is an important new tool for understanding the molecular control of mammalian development.

Genetic imprinting in mice results in functional differences in the oocyte and spermatocyte genomes, as evidenced by both genetic and pronuclear transfer experiments. To gain insights into the molecular mechanisms involved in the imprinting process, researchers have studied methylation phenotypes and expression of hemizygous transgenes associated with parental origin. In this report, we describe a transgenic mouse lineage in which expression of both the transgene and an endogenous gene at the insertion site are determined by the parent of origin. The mutation caused by transgene insertion shows variable expressivity and incomplete penetrance in addition to a modified dominant pattern of inheritance.

Two transgenic mice were produced by microinjection of the entire hepatitis B virus (HBV) genome as a 3.2-kilobase EcoRI DNA fragment into one-cell embryos. Each animal contained a single, unique locus of HBV sequence. One founder animal, G7, contained a partially deleted HBV genome lacking both putative HBV surface antigen (HBsAg) promoters. The other animal, G26, contained greater-than-genome-length HBV sequences organized as a partial head-to-tail dimer. Both transgenic animals transmitted the HBV sequences in a Mendelian fashion, and all subsequent transgenic animals had detectable HBsAg in the serum. Expression of HBV sequences in tissues from G7- and G26-derived mice showed preferential expression of the 2.1-kilobase HBsAg RNA transcript in liver and kidney tissues by Northern (RNA) blot analysis. These data are consistent with the notion that HBV DNA contains cis-acting regulatory sequences which are responsible for the predominant expression of HBsAg transcripts in the liver and kidney of transgenic mice.

We are investigating human insulin gene expression in transgenic mice. An 8.8 kilobase (kb) human genomic DNA fragment, including the insulin gene (1.4 kb) and 2 kb of 5' human flanking sequences, was introduced into mouse embryos by pronuclear microinjection. Two lines of transgenic mice have been established, both of which carry the intact human gene in multiple copies. Animals from both lines have significantly higher insulin levels than control mice, and the degree of hyperinsulinemia shows a positive correlation with human gene copy number in the two lines. Expression of the human gene is confirmed by the detection of human C-peptide in plasma. Tissue specificity of expression is maintained, with human insulin mRNA detectable only in the pancreas. The transgenics maintain normal fasting blood glucose in spite of their high insulin levels, but preliminary studies show them to be glucose intolerant when given a glucose load. These mice provide a model system for further studies on the regulation of insulin gene expression and on the effects of chronic hyperinsulinemia on glucose homeostasis.