The nitric oxide-producing properties of Solanum lyratum

We examined the effect of Solanum lyratum Thunb. (Solanaceae) (SL) on the production of nitric oxide (NO). Stimulation of mouse peritoneal macrophages with SL after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in increased NO synthesis. SL had no effect on NO synthesis by itself. When SL was used in combination with rIFN-gamma, there was a marked cooperative induction of NO synthesis in a dose-dependent manner. The optimal effect of SL on NO synthesis was shown 6 h after treatment with rIFN-gamma. The increased production of NO from rIFN-gamma plus SL-stimulated cells was decreased by the treatment with staurosporin. In addition, synergy between rIFN-gamma and SL was mainly dependent on SL-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of SL were endotoxin free. The present results indicate that the capacity of SL to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of SL-induced TNF-alpha secretion via the signal transduction pathway of PKC activation.

DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development

The establishment of DNA methylation patterns requires de novo methylation that occurs predominantly during early development and gametogenesis in mice. Here we demonstrate that two recently identified DNA methyltransferases, Dnmt3a and Dnmt3b, are essential for de novo methylation and for mouse development. Inactivation of both genes by gene targeting blocks de novo methylation in ES cells and early embryos, but it has no effect on maintenance of imprinted methylation patterns. Dnmt3a and Dnmt3b also exhibit nonoverlapping functions in development, with Dnmt3b specifically required for methylation of centromeric minor satellite repeats. Mutations of human DNMT3B are found in ICF syndrome, a developmental defect characterized by hypomethylation of pericentromeric repeats. Our results indicate that both Dnmt3a and Dnmt3b function as de novo methyltransferases that play important roles in normal development and disease.

DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development

The establishment of DNA methylation patterns requires de novo methylation that occurs predominantly during early development and gametogenesis in mice. Here we demonstrate that two recently identified DNA methyltransferases, Dnmt3a and Dnmt3b, are essential for de novo methylation and for mouse development. Inactivation of both genes by gene targeting blocks de novo methylation in ES cells and early embryos, but it has no effect on maintenance of imprinted methylation patterns. Dnmt3a and Dnmt3b also exhibit nonoverlapping functions in development, with Dnmt3b specifically required for methylation of centromeric minor satellite repeats. Mutations of human DNMT3B are found in ICF syndrome, a developmental defect characterized by hypomethylation of pericentromeric repeats. Our results indicate that both Dnmt3a and Dnmt3b function as de novo methyltransferases that play important roles in normal development and disease.

Targeted disruption of mouse Yin Yang 1 transcription factor results in peri-implantation lethality

Yin Yang 1 (YY1) is a zinc finger-containing transcription factor and a target of viral oncoproteins. To determine the biological role of YY1 in mammalian development, we generated mice deficient for YY1 by gene targeting. Homozygosity for the mutated YY1 allele results in embryonic lethality in the mouse. YY1 mutants undergo implantation and induce uterine decidualization but rapidly degenerate around the time of implantation. A subset of YY1 heterozygote embryos are developmentally retarded and exhibit neurulation defects, suggesting that YY1 may have additional roles during later stages of mouse embryogenesis. Our studies demonstrate an essential function for YY1 in the development of the mouse embryo.

The type II activin receptors are essential for egg cylinder growth, gastrulation, and rostral head development in mice

The type II activin receptors, ActRIIA and ActRIIB, have been shown to play critical roles in axial patterning and organ development in mice. To investigate whether their function is required for mesoderm formation and gastrulation as implicated in Xenopus studies, we generated mice carrying both receptor mutations by interbreeding the ActRIIA and ActRIIB knockout mutants. We found that embryos homozygous for both receptor mutations were growth arrested at the egg cylinder stage and did not form mesoderm. Further analyses revealed that ActRIIA(-/-)ActRIIB(+/-) and about 15% of the ActRIIA(-/-) embryos failed to form an elongated primitive streak, resulting in severe disruption of mesoderm formation in the embryo proper. Interestingly, we observed similar gastrulation defects in ActRIIA(-/-)nodal(+/-) double mutants, which, if they developed beyond the gastrulation stage, displayed rostral head defects and cyclopia. These results provide genetic evidence that type II activin receptors are required for egg cylinder growth, primitive streak formation, and rostral head development in mice.

Cloning, expression and chromosome locations of the human DNMT3 gene family

DNA methylation plays an important role in animal development and gene regulation. In mammals, several genes encoding DNA cytosine methyltransferases have been identified. DNMT1 is constitutively expressed and is required for the maintenance of global methylation after DNA replication. In contrast, the murine Dnmt3 family genes appear to be developmentally regulated and behave like de novo DNA methyltransferases in vitro. In this study, we have cloned human DNMT3A and DNMT3B that encode full-length DNMT3A and DNMT3B proteins with 98% and 94% amino acid sequence identity to their murine homologues. The DNMT3A and DNMT3B show high homology in the carboxy terminal catalytic domain and contain a conserved cysteine-rich region, which shares homology with the X-linked ATRX gene of the SNF2/SWI family. We have mapped human DNMT3A and DNMT3B to chromosomes 2p23 and 20q11.2 respectively, and determined the DNMT3B genomic structure. We further show that DNMT3A expression is ubiquitous and can be readily detected in most adult tissues, whereas DNMT3B is expressed at very low levels in most tissues except testis, thyroid and bone marrow. Significantly, both DNMT3A and DNMT3B expression is elevated in several tumor cell lines to levels comparable to DNMT1. The cloning of the human DNMT3 genes will facilitate further biochemical and genetic studies of their functions in establishment of DNA methylation patterns, regulation of gene expression and tumorigenesis.

The nitric oxide-producing activities of Scutellaria baicalensis

Scutellaria baicalensis (SB) has antibacterial and antiviral activities. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of bacteria, viruses and tumors has received increasing attention. The objective of this study was to determine the effect of SB on the production of NO. Stimulation of mouse peritoneal macrophages with SB after the treatment of recombinant interferon-gamma (rIFN-gamma) resulted in the increased NO production. SB had no effect on NO production by itself. When SB was used in combination with rIFN-gamma, there was a marked cooperative induction of NO production in a dose-dependent manner. The optimal effect of SB on NO production was shown 6 h after treatment with rIFN-gamma. NO production by SB was inhibited by N(G)-monomethyl-L-arginine. The increased production of NO from rIFN-(gamma) plus SB-stimulated cells was decreased by the treatment of protein kinase C inhibitor such as staurosporin. In addition, synergy between rIFN-gamma and SB was mainly dependent on SB-induced tumor necrosis factor-alpha (TNF-alpha) secretion. All the preparations of SB were endotoxin free. These results suggest that the capacity of SB to increase NO production from rIFN-gamma-primed mouse peritoneal macrophages is the result of SB-induced TNF-gamma secretion.

Microbial transformation of sampangine

Microbial transformation studies of the antifungal alkaloid sampangine (2) have revealed that it is metabolized by a number of microorganisms. Using a standard two-stage fermentation technique, Beauvaria bassiana (ATCC 7159), Doratomyces microsporus (ATCC 16225), and Filobasidiella neoformans (ATCC 10226) produced the 4'-O-methyl-beta-glucopyranose conjugate (3), while Absidia glauca (ATCC 22752), Cunninghamella elegans (ATCC 9245), Cunninghamella species (NRRL 5695), and Rhizopus arrhizus (ATCC 11145) produced the beta-glucopyranose conjugate (4). Metabolites 3 and 4 have been characterized on the basis of spectral data. Both 3 and 4 had significant in vitro activity against Cryptococcus neoformans but were inactive against Candida albicans. Metabolite 4 was inactive in vivo in a mouse model of cryptococcosis.

The type I serine/threonine kinase receptor ActRIA (ALK2) is required for gastrulation of the mouse embryo

ActRIA (or ALK2), one of the type I receptors of the transforming growth factor-beta (TGF-beta) superfamily, can bind both activin and bone morphogenetic proteins (BMPs) in conjunction with the activin and BMP type II receptors, respectively. In mice, ActRIA is expressed primarily in the extraembryonic visceral endoderm before gastrulation and later in both embryonic and extraembryonic cells during gastrulation. To elucidate its function in mouse development, we disrupted the transmembrane domain of ActRIA by gene targeting. We showed that embryos homozygous for the mutation were arrested at the early gastrulation stage, displaying abnormal visceral endoderm morphology and severe disruption of mesoderm formation. To determine in which germ layer ActRIA functions during gastrulation, we performed reciprocal chimera analyses. (1) Homozygous mutant ES cells injected into wild-type blastocysts were able to contribute to all three definitive germ layers in chimeric embryos. However, a high contribution of mutant ES cells in chimeras disrupted normal development at the early somite stage. (2) Consistent with ActRIA expression in the extraembryonic cells, wild-type ES cells failed to rescue the gastrulation defect in chimeras in which the extraembryonic ectoderm and visceral endoderm were derived from homozygous mutant blastocysts. Furthermore, expression of HNF4, a key visceral endoderm-specific transcription regulatory factor, was significantly reduced in the mutant embryos. Together, our results indicate that ActRIA in extraembryonic cells plays a major role in early gastrulation, whereas ActRIA function is also required in embryonic tissues during later development in mice.

The effects of economic reform on health insurance and the financial burden for urban workers in China

Since 1980, Chinese enterprises have been undergoing reforms in employment practice, taxation, and workers' health/welfare benefits coverage. In particular, Chinese businesses have been facing a major challenge with respect to the financial burden of providing medical benefits to their workers. The purpose of this paper is to analyse the impact of enterprise reform on workers' health care benefits and their financial burden due to medical expenses. This study is based on a 1992 survey conducted in 22 cities, and included 406 enterprises and 5920 workers. It was found that there were wide variations of coverage for health care benefits among urban Chinese workers. It was also found that workers with partial coverage were as likely to incur out-of-pocket medical expenditures as workers without coverage. These out-of-pocket medical expenditures could reach as high as 25% of a worker's annual income. Policy recommendations are discussed at the end of the paper.

Differential mechanisms of retinoid transfer from cellular retinol binding proteins types I and II to phospholipid membranes

Cellular retinol-binding proteins types I and II (CRBP-I and CRBP-II) are known to differentially facilitate retinoid metabolism by several membrane-associated enzymes. The mechanism of ligand transfer to phospholipid small unilamellar vesicles was compared in order to determine whether differences in ligand trafficking properties could underlie these functional differences. Unidirectional transfer of retinol from the CRBPs to membranes was monitored by following the increase in intrinsic protein fluorescence that occurs upon ligand dissociation. The results showed that ligand transfer of retinol from CRBP-I was >5-fold faster than transfer from CRBP-II. For both proteins, transfer of the other naturally occurring retinoid, retinaldehyde, was 4-5-fold faster than transfer of retinol. Rates of ligand transfer from CRBP-I to small unilamellar vesicles increased with increasing concentration of acceptor membrane and with the incorporation of the anionic lipids cardiolipin or phosphatidylserine into membranes. In contrast, transfer from CRBP-II was unaffected by either membrane concentration or composition. Preincubation of anionic vesicles with CRBP-I was able to prevent cytochrome c, a peripheral membrane protein, from binding, whereas CRBP-II was ineffective. In addition, monolayer exclusion experiments demonstrated differences in the rate and magnitude of the CRBP interactions with phospholipid membranes. These results suggest that the mechanisms of ligand transfer from CRBP-I and CRBP-II to membranes are markedly different as follows: transfer from CRBP-I may involve and require effective collisional interactions with membranes, whereas a diffusional process primarily mediates transfer from CRBP-II. These differences may help account for their distinct functional roles in the modulation of intracellular retinoid metabolism.

Highly metastatic human prostate cancer growing within the prostate of athymic mice overexpresses vascular endothelial growth factor

Angiogenesis is essential for tumor progression and metastasis. It is mediated by the release of angiogenic factors by the tumor or host. We analyzed the expression of angiogenic factors by the prostate cancer cell line LNCaP and two derived variants, in vitro and in vivo, to determine whether metastatic cell lines express higher levels of these factors. The production of three angiogenic factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and interleukin 8 (IL-8), by LNCaP and its variants, LNCaP-LN3 (highly metastatic) and LNCaP-Pro5 (slightly metastatic), was measured by ELISA. VEGF, bFGF, and IL-8 mRNA expression was determined in vitro by Northern blot analysis. VEGF mRNA expression was determined in vivo by in situ hybridization. VEGF and flk-1 protein expression and microvessel density of LNCaP cell tumors were quantified by immunohistochemistry. In vitro, VEGF production by LNCaP-LN3 (3.15+/-0.04 pg/ml/10(3) cells) was significantly higher than those of both LNCaP (2.38+/-0.34 pg/ml/10(3) cells) and LNCaP-Pro5 (1.67+/-0.37 pg/ml/10(3) cells; P = 0.049 and 0.001, respectively). None of the three cell lines produced detectable levels of bFGF or IL-8 in vitro. In vivo, LNCaP-LN3 tumors exhibited higher levels of VEGF mRNA and protein (152.2+/-28.5 and 200.5+/-28.3) and of flk-1 protein (156.5+/-20.6) and had higher microvessel density (16.4+/-4.2) than either LNCaP tumors (89+/-17.5, 173.3+/-23.0, 124.6+/-21.6, and 12.4+/-3.5, respectively) or LNCaP-Pro5 tumors (63+/-14.7, 141.2+/-38.1, 126.1+/-20, and 5.8+/-2.2, respectively). In conclusion, metastatic human prostate cancer cells exhibited enhanced VEGF production and tumor vascularity compared with prostate cancer cells of lower metastatic potential. Thus, VEGF may play an important role in prostate cancer metastasis.

The structure and dynamics of rat apo-cellular retinol-binding protein II in solution: comparison with the X-ray structure

The structure and dynamics of rat apo-cellular retinol binding protein II (apo-CRBP II) in solution has been determined by multidimensional NMR analysis of uniformly enriched recombinant rat 13C, 15N-apo-CRBP II and 15N-apo-CRBP II. The final ensemble of 24 NMR structures has been calculated from 3274 conformational restraints or 24.4 restraints/residue. The average root-mean-square deviation of the backbone atoms for the final 24 structures relative to their mean structure is 1.06 A. Although the average solution structure is very similar to the crystal structure, it differs at the putative entrance to the binding cavity, which is formed by the helix-turn-helix motif, the betaC-betaD turn and the betaE-betaF turn. The mean coordinates of the main-chain atoms of amino acid residues 28-38 are displaced in the solution structure relative to the crystal structure. The side-chain of F58, located on the betaC-betaD turn, is reoriented such that it interacts with L37 and no longer blocks entry into the ligand-binding pocket. Residues 28-35, which form the second helix of the helix-turn-helix motif in the crystal structure, do not exhibit a helical conformation in the solution structure. The solution structure of apo-CRBP II exhibits discrete regions of backbone disorder which are most pronounced at residues 28-32, 37-38 and 73-76 in the betaE-betaF turn as evaluated by the consensus chemical shift index, the root-mean-square deviation, amide 1H exchange rates and 15N relaxation studies. These studies indicate that fluctuations in protein conformation occur on the microseconds to ms time-scale in these regions of the protein. Some of these exchange processes can be directly observed in the three-dimensional 15N-resolved NOESY spectrum. These results suggest that in solution, apo-CRBP II undergoes conformational changes on the microseconds to ms time-scale which result in increased access to the binding cavity.

Parathyroid hormone-related peptide (PTHrP) induces parietal endoderm formation exclusively via the type I PTH/PTHrP receptor

A number of studies suggest a role for PTHrP and the classical PTH/PTHrP receptor (type I) in one of the first differentiation processes in mouse embryogenesis, i.e. the formation of parietal endoderm (PE). We previously reported that although in type I receptor (-/-) embryos PE formation seemed normal, the embryos were smaller from at least day 9.5 p.c. and 60% had died before day 12.5 p.c. Here we show that the observed growth defect commences even earlier, at day 8.5 p.c. Using two novel antibodies, we show that the expression of the type I receptor protein at this stage is confined to extraembryonic endoderm only. In addition, we show that large amounts of PTHrP protein are present in the adjacent trophoblast giant cells, suggesting a paracrine interaction of PTHrP and the type I PTH/PTHrP receptor in PE formation. The involvement in PE differentiation of other recently described receptors for PTHrP would explain a possible redundancy for the type I receptor in PE formation. However, deletion of the type I PTH/PTHrP receptor in ES cells by homologous recombination completely prevents PTHrP-induced PE differentiation. Based upon these observations, we propose that PTHrP and the type I PTH/PTHrP receptor, although not required for the initial formation of PE, are required for its proper differentiation and/or functioning.

Structural and functional abnormalities in the spleen of an mFtz-F1 gene-disrupted mouse

The spleen has two main functions. The first is to provide a proper microenvironment to lymphoid and myeloid cells, whereas the second involves clearance of abnormal erythrocytes. Ad4BP/SF-1, a product of the mammalian FTZ-F1 gene (mFTZ-F1), was originally identified as a steroidogenic, tissue-specific transcription factor. Immunohistochemical examination of the mammalian spleens confirmed the expression of Ad4BP/SF-1 in endothelial cells of the splenic venous sinuses and pulp vein. In mFtz-F1 gene-disrupted (KO) mice, several structural abnormalities were detected in the spleen, including underdevelopment and nonuniform distribution of erythrocytes. Examination of the spleen of KO fetuses showed failure of development of certain tubular structures during embryogenesis. These structures are normally assembled by Ad4BP/SF-1 immunoreactive cells, and most likely form the vascular system during later stages of development. Other structural abnormalities in the spleen of the KO mice included defects in the tissue distribution of type-IV collagen, laminin, c-kit, and vimentin. These morphologic defects in the vascular system were associated with a decrease in the proportion of hematopoietic cells, although differentiation of these cells was not affected significantly. A high number of abnormal red blood cells containing Howell-Jolly bodies were noted in the KO mice, indicating impaired clearance by the splenic vascular system. We also detected the presence of an mRNA-encoding cholesterol side-chain cleavage P450 in the spleen, resembling the findings in steroidogenic tissues such as the gonads and adrenal cortex. The mRNA transcript was not involved in splenic structural defects as it was detected in the spleens of both normal and KO mice, indicating that the regulatory mechanism of the P450 gene in the spleen is different from that in steroidogenic tissues. Our results indicate that a lack of the mFtz-F1 gene in mice is associated with structural and functional abnormalities of the splenic vascular system.

Matrix valency regulates integrin-mediated lymphoid adhesion via Syk kinase

Lymphocytes accumulate within the extracellular matrix (ECM) of tumor, wound, or inflammatory tissues. These tissues are largely comprised of polymerized adhesion proteins such as fibrin and fibronectin or their fragments. Nonactivated lymphoid cells attach preferentially to polymerized ECM proteins yet are unable to attach to monomeric forms or fragments of these proteins without previous activation. This adhesion event depends on the appropriate spacing of integrin adhesion sites. Adhesion of nonactivated lymphoid cells to polymeric ECM components results in activation of the antigen receptor-associated Syk kinase that accumulates in adhesion-promoting podosomes. In fact, activation of Syk by antigen or agonists, as well as expression of an activated Syk mutant in lymphoid cells, facilitates their adhesion to monomeric ECM proteins or their fragments. These results reveal a cooperative interaction between signals emanating from integrins and antigen receptors that can serve to regulate stable lymphoid cell adhesion and retention within a remodeling ECM.

Structure and function of cytoplasmic retinoid binding proteins

We examined the ligand protein interactions of two highly homologous cellular retinol binding proteins, CRBP and CRBP-II, and two highly homologous cellular retinoic acid binding proteins, CRABP-I and CRABP-II. While the crystal structures of all four have been determined, nuclear magnetic resonance studies provide a means for observing dynamic aspects of ligand protein interactions of these proteins in solution. The cellular functions of these proteins are less well understood. We have modeled retinoid flux between cytoplasmic retinoid proteins and model membranes and with nuclear receptors. Based on our in vitro studies, we propose that certain retinoids may indirectly influence retinoid signaling by displacing endogenous retinoids from the cytoplasmic proteins to the nuclear receptors.

Epithelial cell-initiated inflammation plays a crucial role in early tissue damage in amebic infection of human intestine

BACKGROUND & AIMS

Entamoeba histolytica infection of the intestine can induce severe gut inflammation. The aims of this study were to assess the role of the host inflammatory response in the tissue damage observed with amebiasis and the role of the intestinal epithelial cell in initiating that response.

METHODS

E. histolytica infection was established in human intestinal xenografts in severe combined immunodeficient (SCID-HU-INT) mice. Human intestinal epithelial cell inflammatory responses to amebic infection were inhibited by the intraluminal administration of an antisense oligonucleotide to the human p65 subunit of nuclear factor kappaB, and the role of neutrophils in tissue damage observed with amebiasis was studied by depleting neutrophils from SCID-HU-INT mice.

RESULTS

Administration of the antisense oligonucleotide blocked the production of human interleukin 1beta and interleukin 8 by intestinal epithelial cells and inhibited neutrophil influx into the E. histolytica-infected intestinal xenografts. Inhibition of the gut inflammatory response by the antisense oligonucleotide or the depletion of neutrophils from SCID-HU-INT mice blocked the increase in intestinal permeability observed with amebic infection.

CONCLUSIONS

Intestinal epithelial cells initiate an inflammatory response with resulting neutrophil-mediated tissue damage in response to E. histolytica infection; this inflammatory cascade can be blocked by inhibiting the transcription of genes regulated by nuclear factor kappaB.

Adenovirus endocytosis requires actin cytoskeleton reorganization mediated by Rho family GTPases

Adenovirus (Ad) endocytosis via alphav integrins requires activation of the lipid kinase phosphatidylinositol-3-OH kinase (PI3K). Previous studies have linked PI3K activity to both the Ras and Rho signaling cascades, each of which has the capacity to alter the host cell actin cytoskeleton. Ad interaction with cells also stimulates reorganization of cortical actin filaments and the formation of membrane ruffles (lamellipodia). We demonstrate here that members of the Rho family of small GTP binding proteins, Rac and CDC42, act downstream of PI3K to promote Ad endocytosis. Ad internalization was significantly reduced in cells treated with Clostridium difficile toxin B and in cells expressing a dominant-negative Rac or CDC42 but not a H-Ras protein. Viral endocytosis was also inhibited by cytochalasin D as well as by expression of effector domain mutants of Rac or CDC42 that impair cytoskeletal function but not JNK/MAP kinase pathway activation. Thus, Ad endocytosis requires assembly of the actin cytoskeleton, an event initiated by activation of PI3K and, subsequently, Rac and CDC42.

The parathyroid hormone/parathyroid hormone-related peptide receptor coordinates endochondral bone development by directly controlling chondrocyte differentiation

During vertebrate limb development, growth plate chondrocytes undergo temporally and spatially coordinated differentiation that is necessary for proper morphogenesis. Parathyroid hormone-related peptide (PTHrP), its receptor, the PTH/PTHrP receptor, and Indian hedgehog are implicated in the regulation of chondrocyte differentiation, but the specific cellular targets of these molecules and specific cellular interactions involved have not been defined. Here we generated chimeric mice containing both wild-type and PTH/PTHrP receptor (-/-) cells, and analyzed cell-cell interactions in the growth plate in vivo. Abnormal differentiation of mutant cells shows that PTHrP directly signals to the PTH/PTHrP receptor on proliferating chondrocytes to slow their differentiation. The presence of ectopically differentiated mutant chondrocytes activates the Indian hedgehog/PTHrP axis and slows differentiation of wild-type chondrocytes. Moreover, abnormal chondrocyte differentiation affects mineralization of cartilaginous matrix in a non-cell autonomous fashion; matrix mineralization requires a critical mass of adjacent ectopic hypertrophic chondrocytes. Further, ectopic hypertrophic chondrocytes are associated with ectopic bone collars in adjacent perichondrium. Thus, the PTH/PTHrP receptor directly controls the pace and synchrony of chondrocyte differentiation and thereby coordinates development of the growth plate and adjacent bone.

[The habit of flowering and fruiting of Scaphium lychnophorum]

The flowering and fruiting are much different between the trees of Scaphium lychnophorum which were introduced in Jinghong. The trees have on-year of fruiting once 3-4 years and off-year continue 2-3 years. In Jinghong, the low temperature in the early flowering period is one factor among the main factors effecting flowering and fruiting of trees. The trees which vegetative grow flush and which grow on the place in a poor sunlight are effected their flowering and fruiting, too.

[Clinical significance of P-glycoprotein expression in breast cancer]

OBJECTIVE

To study the clinical significance of P-glycoprotein (P-gp) in breast cancer.

METHODS

Expression of P-gp in 60 cases of breast cancer was examined by immunohistochemistry. P-gp expression and response to chemotherapy were comparatively investigated in 19 patients with metastatic breast cancer.

RESULTS

The P-gp was positive in 48.3% of the 60 cases of breast cancer. P-gp expression was not related to patients' age, menstruation status, number of axillary lymph nodes involved, clinical stage, histological type, and hormonal receptor status(P > 0.05). The frequency of metastasis (62.1%) and mortality (51.7%) were higher in P-gp positive cases than those in negative cases (16.1% vs 12.9%, P < 0.005). The 5-year survival rate of P-gp positive cases (48.3%) was significantly lower than that of negative cases (87.1%) (P < 0.05). In patients received adjuvant chemotherapy distant metastasis occurred more frequently in P-gp positive cases (94.7%) than in P-gp negative cases (57.1%) (P = 0.0468). More P-gp negative patients (7/9) than positive patients (1/10) were responsive to chemotherapy (P = 0.0055).

CONCLUSION

Immunohistochemical examination of P-gp expression is useful in predicting response to chemotherapy and prognosis in breast cancer patients. P-gp positivity is associated with poor prognosis.