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N Kim

Publications and source records attributed to N Kim.

At least 109 records · Page 6Linked to original sources
PubMed1997

Experimental esophagitis affects intracellular calcium stores in the cat lower esophageal sphincter.

We previously showed that lower esophageal spincter (LES) tone depends on spontaneous production of inositol 1,4,5-trisphosphate (IP3) and release of intracellular Ca2+ and that acute experimental esophagitis reduces LES tone and IP3 production, suggesting damage to mechanisms responsible for release of Ca2+ from intracellular stores. In the present investigation, we examined the possibility that mechanisms responsible for Ca2+ storage or uptake may also be damaged. LES circular muscle cells were isolated by enzymatic digestion. Contraction was measured in response to IP3 and thapsigargin, which enhances release of Ca2+ from intracellular stores, and in response to calmodulin and to diacylglycerol. In addition, normal cells were incubated in thapsigargin to assess the effect of depletion of intracellular Ca2+ stores on contractile response. Contraction in response to IP3 and thapsigargin was reduced in experimental esophagitis, but contraction in response to calmodulin or diacylglycerol was not. Acetylcholine (ACh)-induced contraction of normal cells was inhibited by the calmodulin antagonist CGS-9343B but not by 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine dihydrochloride (H-7). In contrast, in cells from animals with esophagitis or in thapsigargin-treated cells from normal animals, ACh-induced contraction was inhibited by H-7 and not by CGS-9343B. We conclude that experimental esophagitis may damage intracellular Ca2+ stores in the LES and change the intracellular contractile pathways activated by ACh from calmodulin dependent in normal cells to protein kinase C dependent in esophagitis.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Sympathetically correlated activity of dorsal horn neurons in spinally transected rats.

In mammals with an intact neuraxis, most sympathetic nerve activity is generated by brain stem systems. Therefore these systems have attracted much more attention than spinal systems that generate excitatory inputs to sympathetic preganglionic neurons. The purpose of this study was to determine whether, within hours of C1 spinal cord transection, spinal dorsal horn neurons (DHNs) play a role in generating sympathetic nerve activity. Experiments were conducted in chloralose-anesthetized rats. We recorded renal sympathetic nerve activity (RSNA) in the left renal nerve, and we recorded the activity of neurons located in the left dorsal horn at T2, T8, T10, T13, and L2. We also recorded the activity of neurons in the right dorsal horn at T10. The somatic fields and cutaneous modalities of most neurons were determined. Spike-triggered averaging was used to determine relationships between the ongoing activity of DHNs and ongoing RSNA. In the left dorsal horn, bursts of ongoing activity of 16% of DHNs at T8 and 43% of DHNs at T10 were positively correlated with bursts of ongoing RSNA at latencies of 59 +/- 8 (SE) ms. At no other level on the left side, nor in the T10 segment on the right side, was the activity of DHNs correlated with RSNA. DHNs with activity correlated with RSNA were located only in dorsal horn laminae III-V. Deeper laminae were not investigated in these experiments. The activity of all sympathetically correlated DHNs exhibited bursts of action potentials with interspike intervals of < 10 ms. All but one of the sympathetically correlated DHNs exhibited wide-dynamic-range modalities. The modalities of sympathetically uncorrelated neurons were more heterogeneous. Brief (5-10 s) noxious cutaneous stimulation of mid- and lower thoracic dermatomes on the left side excited all sympathetically correlated DHNs and simultaneously increased RSNA. The excitatory cutaneous fields of sympathetically correlated neurons were circumscribed by the excitatory fields for RSNA. The excitatory cutaneous fields of some sympathetically uncorrelated DHNs extended beyond the excitatory fields for RSNA. Noxious cutaneous stimulation of the extremities on the left side that decreased RSNA simultaneously decreased the activity of all sympathetically correlated DHNs. These data provide electrophysiological evidence that, in spinally transected rats, a population of DHNs may generate or convey excitatory input to renal sympathetic preganglionic neurons.

Action Potentials↗
PubMed1997

In vivo characterization of sustained-release formulations of human growth hormone.

Long-acting formulations of recombinant human growth hormone (rhGH) were prepared by stabilizing and encapsulating the protein into three different injectable, biodegradable microsphere formulations composed of polymers of lactic and glycolic acid. The formulations were compared in juvenile rhesus monkeys by measuring the serum levels of rhGH and two proteins induced by hGH, insulin-like growth factor-I and IGF binding protein-3 (IGFBP-3) after single s.c. administration. All three formulations, which differed principally in the composition of the polymer, provided sustained elevated levels of all three proteins for several weeks, and the rate of release of rhGH differed among the formulations consistent with the molecular weight of the polymer used. All three formulations induced a higher level of insulin-like growth factor-I and insulin-like growth factor binding protein than was induced by daily injections of the same amount of rhGH in solution. After three monthly injections of one of the formulations, both the rhGH and IGF-I levels remained elevated for nearly 90 days. Immunogenicity of the rhGH released from this formulation, as assessed by the incidence of seroconversion to hGH and the titer of anti-hGH antibody in both the rhesus monkeys and transgenic mice expressing rhGH, was no greater than that of the unencapsulated protein. In addition, the microsphere injection sites appeared normal by macroscopic evaluation between 1 to 2 mo after microsphere administration and by microscopic evaluation between 2 to 3 mo. These results show that serum levels of a therapeutic protein can be sustained for an extended period when encapsulated into different formulations of injectable, biodegradable microspheres.

Animals↗
PubMed1997

Acute experimental esophagitis activates a second signal transduction pathway in cat smooth muscle from the lower esophageal sphincter.

In single cells, isolated by enzymatic digestion from the circular muscle layer of the lower esophageal sphincter (LES), acute experimental esophagitis (AE) alters signal transduction in response to a maximally effective dose of acetylcholine. In normal LES contraction was inhibited by M3 >> M1 or M2 antagonists. In AE inhibition by M2 antagonists increased significantly so that contraction was inhibited by M3 > M2 > M1 antagonists. In normal cells permeabilized by saponin, contraction was antagonized by antibodies against Gq/11, by the phosphatidylinositol-specific phospholipase C (PI-PLC) antagonist U 73122, but not by the phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor D609, or by the phospholipase D pathway inhibitor propranolol. In AE contraction was reduced by Gq/11 and Gi3 antibodies and by U73122, propranolol and D609. After thapsigargin treatment of normal cells to reduce intracellular Ca++ stores, contraction was inhibited by M2 and M3 antagonists, by antibodies against Gq/11 and Gi3, by U73122, D609 and propranolol, suggesting that depletion of Ca++ stores reproduces the changes induced by AE. We conclude that in normal LES smooth muscle cells acetylcholine-induced contraction is mediated by M3 receptors linked to Gq/11 and PI-PLC, whereas in AE, contraction through this pathway is reduced, perhaps because of reduction in Ca++ stores, and a second pathway is activated by M2 receptors linked to Gi3, PC-PLC and phospholipase D.

Acetylcholine↗
PubMed1997

Cripto-1 inhibits beta-casein expression in mammary epithelial cells through a p21ras-and phosphatidylinositol 3'-kinase-dependent pathway.

Cripto-1 (CR-1) is a recently discovered protein of the epidermal growth factor family that does not directly activate any of the known erbB type 1 tyrosine kinase receptors. Also, CR-1 stimulates the growth of HC-11 mouse mammary epithelial cells. We found that prior treatment of HC-11 cells with exogenous CR-1 induced a competency response to the lactogenic hormones dexamethasone, insulin, and prolactin (DIP) with respect to the induction of the milk protein beta-casein. In contrast, simultaneous treatment of mouse HC-11 cells with CR-1 in the presence of DIP inhibited beta-casein expression. The inhibitory effects of CR-1 on beta-casein expression in response to DIP were not unique to this mouse mammary epithelial cell line, because beta-casein and whey acidic protein expression in primary mouse mammary explant cultures established from midpregnant mice were also differentially inhibited by several epidermal growth factor-related peptides including CR-1. The mitogenic and differentiation effects of CR-1 are mediated by the binding of CR-1 to a cell surface receptor that is known to activate the ras/raf/mitogen-activated protein kinase (MAPK)/MAPK kinase pathway. The inhibitory response of CR-1 in HC-11 cells on beta-casein expression after treatment with DIP can be attenuated by B581, a peptidomimetic farnesyltransferase inhibitor that blocks p21ras farnesylation and activation, and by the phosphatidylinositol 3'-kinase (PI3k) inhibitor LY 294002 but not by PD 98059, a MAPK kinase inhibitor that blocks MAPK activation. These data suggest that the ability of CR-1 to block lactogenic hormone-induced expression of beta-casein is mediated through a p21ras-dependent, PI3k-mediated pathway. This is further substantiated by the observation that CR-1 is able to stimulate the tyrosine phosphorylation of the p85 PI3k regulatory subunit and to increase the activity of PI3k in HC-11 cells.

Animals↗
PubMed1997

Evaluation of the telomeric repeat amplification protocol (TRAP) assay for telomerase as a diagnostic modality in recurrent bladder cancer.

There is a need for the identification of an accurate test for the detection of recurrent bladder cancer. In this study, we evaluate the telomeric repeat amplification protocol (TRAP) assay for detection of telomerase as a potential new method for bladder cancer detection and compare it to voided urine cytology. A urine sample and a bladder wash were obtained from 63 patients with a history of bladder cancer. Cytological evaluation was performed on voided urine, and the TRAP assay was performed on voided urine and bladder wash. The overall clinical sensitivity of the TRAP assay, as defined by the ability to identify correctly the patients with pathologically confirmed bladder cancer, was 35% in voided urine and 50% in bladder wash, whereas the overall clinical sensitivity of voided urine cytology was 71%. The sensitivity of voided urine cytology for the papillary and noninvasive tumors (Ta) was 50%, compared to 92% for the superficially invasive tumors (T1), 62% for the muscle-invasive tumors (T2+), and 100% for the high-grade flat carcinoma in situ (Tis). The clinical sensitivity of the TRAP assay using voided urine was 46% for Ta, 50% for T1, 18% for T2+, and 20% for Tis. The sensitivity of the TRAP assay in Ta disease was similar to that of cytology (50% for cytology versus 46% for the TRAP assay). There was a strong association between the total number of exfoliated malignant cells and the sensitivity of the assay. The sensitivity of the TRAP assay in bladder washes was 44% for Ta, 67% for T1, 46% for T2+, and 43% for Tis. The TRAP assay is reproducible, highly specific, and not dependent on the expertise of the cytopathologist. These results suggest that this assay should be further investigated as a diagnostic tool for bladder cancer.

Carcinoma, Papillary↗
PubMed1996

Enhanced expression of heregulin in c-erb B-2 and c-Ha-ras transformed mouse and human mammary epithelial cells.

Heregulin beta 1 was found to stimulate the anchorage-dependent, serum-free growth of nontransformed human MCF-10A mammary epithelial cells. Unlike epidermal growth factor, transforming growth factor alpha, or amphiregulin, heregulin beta 1 was also able to induce the anchorage-independent growth of MCF-10A cells. In contrast, the anchorage-independent, serum-free growth of c-Ha-ras or c-erb B-2 transformed MCF-10A cells was unaffected by heregulin beta 1, whereas heregulin beta 1 was able to stimulate the anchorage-independent growth of these cells. c-Ha-ras or c-erb B-2 (c-neu) transformed MCF-10A or mouse NOG-8 mammary epithelial cells express elevated levels of 2.5, 5.0, 6.5, 6.8, and 8.5 kb heregulin mRNA transcripts and/or synthesize cell-associated 25, 29, 50, and 115 kDa isoforms of heregulin. Since the MCF-10A cells and transformants also express c-erb B-3, these data suggest that endogenous heregulin might function as an autocrine growth factor for Ha-ras or erb B-2 transformed mammary epithelial cells.

Animals↗
PubMed1996

Rearrangement of the AML1/CBFA2 gene in myeloid leukemia with the 3;21 translocation: expression of co-existing multiple chimeric genes with similar functions as transcriptional repressors, but with opposite tumorigenic properties.

Several recurring chromosomal translocations involve the AML1 gene at 21q22 in myeloid leukemias resulting in fusion mRNAs and chimeric proteins between AML1 and a gene on the partner chromosome. AML1 corresponds to CBFA2, one of the DNA-binding subunits of the enhancer core binding factor CBF. Other CBF DNA-binding subunits are CBFA1 and CBFA3, also known as AML3 and AML2. AML1, AML2 and AML3 are each characterized by a conserved domain at the amino end, the runt domain, that is necessary for DNA-binding and protein dimerization, and by a transactivation domain at the carboxyl end. AML1 was first identified as the gene located at the breakpoint junction of the 8;21 translocation associated with acute myeloid leukemia. The t(8;21)(q22;q22) interrupts AML1 after the runt homology domain, and fuses the 5' part of AML1 to almost all of ETO, the partner gene on chromosome 8. AML1 is an activator of several myeloid promoters; however, the chimeric AML1/ETO is a strong repressor of some AML1-dependent promoters. AML1 is also involved in the t(3;21)(q26;q22), that occurs in myeloid leukemias primarily following treatment with topoisomerase II inhibitors. We have studied five patients with a 3;21 translocation. In all cases, AML1 is interrupted after the runt domain, and is translocated to chromosome band 3q26. As a result of the t(3;21), AML1 is consistently fused to two separate genes located at 3q26. The two genes are EAP, which codes for the abundant ribosomal protein L22, and MDS1, which encodes a small polypeptide of unknown function. In one of our patients, a third gene EVI1 is also involved. EAP is the closest to the breakpoint junction with AML1, and EVI1 is the furthest away. The fusion of EAP to AML1 is not in frame, and leads to a protein that is terminated shortly after the fusion junction by introduction of a stop codon. The fusion of AML1 to MDS1 is in frame, and adds 127 codons to the interrupted AML1. Thus, in the five cases that we studied, the 3;21 translocation results in expression of two coexisting chimeric mRNAs which contain the identical runt domain at the 5' region, but differ in the 3' region. In addition, the chimeric transcript AML1/MDS1/EVI1 has also been detected in cells from one patient with the 3;21 translocation as well as in one of our patients. Several genes necessary for myeloid lineage differentiation contain the target sequence for AML1 in their regulatory regions. One of them is the CSF1R gene. We have compared the normal AML1 to AML1/MDS1, AML1/EAP and AML1/MDS1/EVI1 as transcriptional regulators of the CSF1R promoter. Our results indicate that AML1 can activate the promoter, and that the chimeric proteins compete with the normal AML1 and repress expression from the CSF1R promoter. AML1/MDS1 and AML1/EAP affect cell growth and phenotype when expressed in rat fibroblasts. However, the pattern of tumor growth of cells expressing the different chimeric genes in nude mice is different. We show that when either fusion gene is expressed, the cells lose contact inhibition and form foci over the monolayer. In addition, cells expressing AML1/MDS1 grow larger tumors in nude mice, whereas cells expressing only AML1/EAP do not form tumors, and cells expressing both chimeric genes induce tumors of intermediate size. Thus, although both chimeric genes have similar effects in transactivation assays of the CSF1R promoter, they affect cell growth differently in culture and have opposite effects as tumor promoters in vivo. Because of the results obtained with cells expressing one or both genes, we conclude that MDS1 seems to have tumorigenic properties, but that AML1/EAP seems to repress the oncogenic property of AML1/MDS1.

Animals↗
PubMed1996

Design issues addressed in published evaluations of adolescent HIV-risk reduction interventions: a review.

OBJECTIVE: This study was conducted to determine: (1) issues in intervention design that have been addressed in behavioral interventions targeting human immunodeficiency virus (HIV)-risk behaviors among adolescents; (2) specific choices made in intervention design; (3) historic changes in the likelihood that issues in intervention design will be addressed; and (4) if an association exists between quality of evaluation design and the number of intervention design issues addressed. DESIGN: Literature search employing five electronic databases and 11 journals for articles published from January 1983 through December 1993 reporting evaluations of adolescent HIV-risk reduction interventions. MAIN OUTCOMES MEASURES: The frequency with which 12 issues in intervention design were addressed: basing the intervention on a theory of behavioral change; specifying a target population; involving the targeted community in the formulation of the intervention; addressing developmental issues; providing facts; strengthening interpersonal skills; describing the media (format) for delivering the intervention; specifying potentially relevant characteristics of the interventionists; describing the duration of the intervention; providing boosters; pilot testing the intervention; and including other potentially augmentative elements. RESULTS: Twenty-eight published intervention articles were included in these analyses. The median number of intervention design issues addressed in any study was six (range three to nine), although this number increased significantly over time (p < .01). There was substantial variability in the frequency with which each individual design issue was addressed, with some design issues (e.g., inclusion of specific facts and the description of the channel employed) being addressed in all studies. Other design issues were addressed in less than one-quarter of studies [e.g., basing the intervention on a theory of behavioral change (18%) and addressing developmental issues (21%)]. The targeted community was involved in one-third of studies. More recent studies and studies employing a randomized evaluation design with both preintervention and postintervention assessments addressed more intervention design issues than did earlier studies and studies employing other evaluation designs (p = .01 and p = .03, respectively). CONCLUSION: The majority of published adolescent HIV-risk reduction studies have not addressed important issues in intervention design. However, more recent studies and studies employing a strong evaluation design have addressed a greater number of these issues. Frameworks to guide intervention efforts (e.g., to serve as "practice guidelines") are needed to allow for both accurate replication and meaningful comparison of differing intervention approaches.

Adolescent↗
PubMed1996

Structure and expression of wild-type and suppressible alleles of the Drosophila purple gene.

Viable mutant alleles of purple (pr), such as prbw, exhibit mutant eye colors. This reflects low 6-pyruvoyl tetrahydropterin (PTP) synthase activity required for pigment synthesis. PTP synthase is also required for synthesis of the enzyme cofactor biopterin; presumably this is why some pr alleles are lethal. The prbw eye color phenotype is suppressed by suppressor of sable [su(s)] mutations. The pr gene was cloned to explore the mechanism of this suppression. pr produces two PTP synthase mRNAs: one constitutively from a distal promoter and one in late pupae and young adult heads from a proximal promoter. The latter presumably supports eye pigment synthesis. The prbw allele has a 412 retrotransposon in an intron spliced from both mRNAs. However, the head-specific mRNA is reduced > 10-fold in prbw and is restored by a su(s) mutation, while the constitutive transcript is barely affected. The Su(s) protein probably alters processing of RNA containing 412. Because the intron containing 412 is the first in the head-specific mRNA and the second in the constitutive mRNA, binding of splicing machinery to nascent transcripts before the 412 insertion is transcribed may preclude the effects of Su(s) protein.

Alcohol Oxidoreductases↗
PubMed1996

Murine leukemia virus-based Tat-inducible long terminal repeat replacement vectors: a new system for anti-human immunodeficiency virus gene therapy.

We have constructed new murine leukemia virus (MLV)-based vectors (TIN vectors) which, following integration, contain human immunodeficiency virus (HIV) type 1 U3 and R sequences in place of the MLV U3 and R regions. This provides, for the first time, single transcriptional unit retroviral vectors under the control of Tat. TIN vectors have several advantages for anti-HIV gene therapy applications.

3T3 Cells↗
PubMed1995

Expression of messenger RNA for amphiregulin, heregulin, and cripto-1, three new members of the epidermal growth factor family, in human breast carcinomas.

The expression of amphiregulin (AR), heregulin (HRG), and cripto-1 (CR-1) mRNA transcripts was assessed in 60 human primary breast carcinoma. AR and HRG transcripts were expressed respectively in 58% and 25% of the carcinomas as measured by Northern blot analysis. CR-1 mRNA was found in 77% of the carcinomas using Reverse Transcriptase-PCR analysis. Coexpression of two or three of these peptides was observed in several specimens. There was no significant association between AR, HRG, and CR-1 expression and nodal status, EGF receptor, or c-erbB-2 protooncogene expression in these tumors. However, a significant association between AR expression and estrogen receptor positivity was observed.

Amphiregulin↗
PubMed1995

Horseradish peroxidase permeability across rat nasal mucosa in selective stimulation of substance P innervation with capsaicin.

To investigate the physiological role of substance P innervation (SPI) in the nasal mucosa from inhaled irritant macromolecules, SPI in the rat nasal mucosa was selectively stimulated with capsaicin and the degree of horseradish peroxidase (HRP) permeability across the nasal epithelium was evaluated by enzyme immunoassay or by histochemical electron microscopy. The serum level of HRP was reduced significantly in capsaicin-administered rats compared to control rats along the time course with quantitative analysis of the enzyme immunoassay. Control rats showed heavy permeation of HRP across the epithelium, but capsaicin-administered rats showed weak permeation of HRP across the epithelium with histochemical electron microscopy. The epithelial lining and its tight junctions were left intact as judged by electron microscopy. In conclusion, selective stimulation of SPI of the rat nasal mucosa with capsaicin decreased the epithelial absorption permeability to HRP without compromising the epithelial integrity. These findings imply that the physiological role of capsaicin-sensitive SPI in the rat mucosa is to protect the airway from inhaled irritant macromolecules.

Alkaloids↗
PubMed1994

Effect of cadmium on estrogen receptor levels and estrogen-induced responses in human breast cancer cells.

The effects of cadmium on estrogen receptor and other estrogen-regulated genes in the human breast cancer cell line MCF-7 were studied. Treatment of MCF-7 cells with 1 microM cadmium decreased the level of estrogen receptor 58%. Cadmium induced a parallel decrease in estrogen receptor mRNA (62%). Progesterone receptor levels increased 3.2-fold after cadmium treatment. This induction was blocked by the anti-estrogen ICI-164,384. Progesterone receptor mRNA was also increased by cadmium, as well as cathepsin D mRNA. An in vitro nuclear transcription run-on assay showed that cadmium increased the transcription of the progesterone receptor and pS2 genes and decreased transcription of the estrogen receptor gene. These are not general effects of heavy metals, as zinc, 25 and 100 microM, did not affect progesterone receptor protein and mRNA levels. Cadmium stimulated pS2 and progesterone receptor mRNAs in a clone of MDA-MB-231 cells transfected with the human estrogen receptor, but had no effect in MDA-MB-231 cells transfected with antisense estrogen receptor. Cadmium also stimulated an estrogen response element in transient transfection experiments. These data suggest that the effects of cadmium are mediated by the estrogen receptor independent of estradiol. In addition to its effect on gene expression, cadmium induced the growth of MCF-7 cells 5.6-fold.

Breast Neoplasms↗
PubMed1994

Specificity of ribozyme designed for mutated DHFR mRNA.

When MOLT-3 human acute leukemia cells were exposed sequentially to trimetrexate (TMQ) and then to methotrexate (MTX), the cells became resistant to antifolate. We designated this subline MOLT-3/TMQ800-MTX10,000. This cell line was found to contain two point mutations in the dihydrofolate reductase (DHFR) gene: a T-->C transition at nucleotide 95 in codon 31, and a T-->A transition at nucleotide 100 in codon 33. In an attempt to specifically inhibit these double-mutated cells, we synthesized a ribozyme which perfectly base-paired with the double-mutated DHFR mRNA. We found that the ribozyme for the double-mutated DHFR mRNA not only cleaved the mutated DHFR RNA, but also efficiently cleaved the wild-type RNA substrate. This observation suggests proceeding with caution when using a ribozyme against a mutated mRNA of an essential enzyme as a specific means of treatment.

Base Sequence↗
PubMed1994

Amphiregulin as an autocrine growth factor for c-Ha-ras- and c-erbB-2-transformed human mammary epithelial cells.

Amphiregulin (AR), a member of the epidermal growth factor (EGF) family, was found to be as potent as EGF in stimulating the anchorage-dependent growth (ADG) of immortalized, nontransformed human mammary epithelial MCF-10A cells. MCF-10A cells transformed by either an activated human c-Ha-ras protooncogene (MCF-10A ras) or by overexpression of a nonactivated rat c-neu gene (MCF-10A neu) exhibited a 35% reduction in the response to AR in ADG when compared to MCF-10A cells, but AR was still as potent as EGF in these transformants. Exogenous AR exhibited only 15-20% of the activity of EGF in stimulating the anchorage-independent growth, a response that is normally dependent upon exogenous EGF, of the oncogene-transformed MCF-10A cells. MCF-10A cells express low levels of a 1.4-kb AR mRNA transcript, while MCF-10A ras and MCF-10A neu cells display a 15- to 30-fold increase in the levels of AR mRNA and endogenous AR protein as determined by Western blot analysis. Exogenous EGF was found to induced both the AR mRNA and protein in the MCF-10A parental and transformed cells. A 20-mer phosphorothioate antisense deoxyoligonucleotide complementary to the 5' sequence of AR mRNA was able to significantly reduce the levels of endogenous AR protein and to inhibit the EGF-stimulated ADG and anchorage-independent growth of MCF-10A ras and MCF-10A neu cells. These data suggest that AR may function as an EGF-dependent autocrine growth factor in mammary epithelial cells that have been transformed by either a point-mutated c-Ha-ras or c-neu.

Amphiregulin↗
PubMed1994

Expression of transforming growth factor alpha, amphiregulin and cripto-1 in human breast carcinomas.

The expression of three epidermal growth factor (EGF)-related peptides, transforming growth factor alpha (TGF-alpha), amphiregulin (AR) and cripto-1 (CR-1), was examined by immunocytochemistry (ICC) in 68 primary infiltrating ductal (IDCs) and infiltrating lobular breast carcinomas (ILCs), and in 23 adjacent non-involved human mammary tissue samples. Within the 68 IDC and ILC specimens, 54 (79%) expressed immunoreactive TGF-alpha, 52 (77%) expressed AR and 56 (82%) expressed CR-1. Cytoplasmic staining was observed with all of the antibodies, and this staining could be eliminated by preabsorption of the antibodies with the appropriate peptide immunogen. Cytoplasmic staining with all of the antibodies was confined to the carcinoma cells, since no specific immunoreactivity could be detected in the surrounding stromal or endothelial cells. In addition to cytoplasmic reactivity, the AR antibody also exhibited nuclear staining in a number of the carcinoma specimens. No significant correlations were found between the percentage of carcinoma cells that were positive for TGF-alpha, AR or CR-1 and oestrogen receptor status, axillary lymph node involvement, histological grade, tumour size, proliferative index, loss of heterozygosity on chromosome 17p or overall patient survival. However, a highly significant inverse correlation was observed between the average percentage of carcinoma cells that expressed AR in individual tumours and the presence of a point-mutated p53 gene. Likewise, a significantly higher percentage of tumour cells in the ILC group expressed AR as compared with the average percentage of tumour cells that expressed AR in the IDC group. Of the 23 adjacent, non-involved breast tissue samples, CR-1 could be detected by ICC in only three (13%), while TGF-alpha was found in six (26%) and AR in ten (43%) of the non-involved breast tissues. These data demonstrate that breast carcinomas express multiple EGF-related peptides and show that the differential expression of CR-1 in malignant breast epithelial cells may serve as a potential tumour marker for breast cancer.

Amphiregulin↗