Placental cell fates are regulated in vivo by HIF-mediated hypoxia responses

Placental development is profoundly influenced by oxygen (O(2)) tension. Human cytotrophoblasts proliferate in vitro under low O(2) conditions but differentiate at higher O(2) levels, mimicking the developmental transition they undergo as they invade the placental bed to establish the maternal-fetal circulation in vivo. Hypoxia-inducible factor-1 (HIF-1), consisting of HIF-1alpha and ARNT subunits, activates many genes involved in the cellular and organismal response to O(2) deprivation. Analysis of Arnt(-/-) placentas reveals an aberrant cellular architecture due to altered cell fate determination of Arnt(-/-) trophoblasts. Specifically, Arnt(-/-) placentas show greatly reduced labyrinthine and spongiotrophoblast layers, and increased numbers of giant cells. We further show that hypoxia promotes the in vitro differentiation of trophoblast stem cells into spongiotrophoblasts as opposed to giant cells. Our results clearly establish that O(2) levels regulate cell fate determination in vivo and that HIF is essential for mammalian placentation. The unique placental phenotype of Arnt(-/-) animals also provides an important tool for studying the disease of preeclampsia. Interestingly, aggregation of Arnt(-/-) embryonic stem (ES) cells with tetraploid wild-type embryos rescues their placental defects; however, these embryos still die from yolk sac vascular and cardiac defects.

[Hepatitis C virus infection and B-cell non-Hodgkin's lymphoma]

Oncogenesis is a multifactorial process in which environmental, genetical and infectious factors may be of importance. Specific viruses are supposed to have etiological role in about 15% of human tumors. Recently the B-cell proliferation inducing effect of the hepatotropic and lymphotropic hepatitis-C virus (HCV) came into the limelight based on the high prevalence of HCV positivity in B-cell non-Hodgkin's lymphoma (NHL) patients. The aim of the authors was to establish the prevalence of HCV infection in NHL patients. Paralelly the HBV, CMV and EBV markers, and the alterations of the humoral immune response (immunoglobulins, cryoglobulins, rheumatoid factor) were determined. 42 patients (24 male, 18 female; the mean age: 54.1 years, range 22-80 years) classified as 16 indolent (low risk), and 25 aggressive (intermediate risk) NHL and one with very aggressive Burkitt's lymphoma, according to the modified REAL classification were examined. Enzyme-linked immunosorbent assay (ELISA) for HBsAg and anti-HCV, HBsAg, anti EBV, anti CMV, furthermore polymerase chain reaction (PCR) for HCV-RNA were used. Anti-HCV was found in 6/42 NHL patients (14.3%), while anti-HCV and/or HCV-RNA PCR positivity revealed on overall HCV infection in 10/42 (23.8%) patients. None of them were HBsAg positive. Our findings support the hypothesis, that HCV might have an aetiological role in the lymphoproliferation leading to B-cell NHL.

[Mediastinal actinomycosis]

The history of a 45 year old man is reviewed who was treated with acute exacerbations of chronic mediastinitis. During one and a half year the patient was examined in different departments of internal medicine, he underwent into surgical interventions and several histological and microbiological examinations have been done. On the third occasion the bacterium of Actinomyces Israeli proved to be the etiologic factor of the disease. Some diagnostic and therapeutic points of view of different localization of the illness are discussed.

Mice null for sox18 are viable and display a mild coat defect

We have previously shown that Sox18 is expressed in developing vascular endothelium and hair follicles during mouse embryogenesis and that point mutations in Sox18 are the underlying cause of cardiovascular and hair follicle defects in ragged (Ra) mice. Here we describe the analysis of Sox18(-/-) mice produced by gene targeting. Despite the profound defects seen in Ra mice, Sox18(-/-) mice have no obvious cardiovascular defects and only a mild coat defect with a reduced proportion of zigzag hairs. A reduction in the amount of pheomelanin pigmentation in hair shafts was also observed; later-forming hair follicles showed a reduced subapical pheomelanin band, giving Sox18(-/-) mice a slightly darker appearance than Sox18(+/+) and Sox18(+/-) siblings. Sox18(-/-) mice are viable and fertile and show no difference in the ability to thrive relative to littermates. Because of the mild effect of the mutation on the phenotype of Sox18(-/-) mice, we conclude that the semidominant nature of the Ra mutations is due to a trans-dominant negative effect mediated by the mutant SOX18 proteins rather than haploinsufficiency as has been observed for other SOX genes. Due to the similarity of SOX18 to other subgroup F SOX proteins, SOX7 and -17, and the overlap in expression of these genes, functional redundancy amongst these SOX proteins could also account for the mild phenotype of Sox18(-/-) mice.

The Ketel gene encodes a Drosophila homologue of importin-beta

The Drosophila melanogaster Ketel gene was identified via the Ketel(D) dominant female sterile mutations and their ketel(r) revertant alleles that are recessive zygotic lethals. The maternally acting Ketel(D) mutations inhibit cleavage nuclei formation. We cloned the Ketel gene on the basis of a common breakpoint in 38E1. 2-3 in four ketel(r) alleles. The Ketel(+) transgenes rescue ketel(r)-associated zygotic lethality and slightly reduce Ketel(D)-associated dominant female sterility. Ketel is a single copy gene. It is transcribed to a single 3.6-kb mRNA, predicted to encode the 97-kD Ketel protein. The 884-amino-acid sequence of Ketel is 60% identical and 78% similar to that of human importin-beta, the nuclear import receptor for proteins with a classical NLS. Indeed, Ketel supports import of appropriately designed substrates into nuclei of digitonin-permeabilized HeLa cells. As shown by a polyclonal anti-Ketel antibody, nurse cells synthesize and transfer Ketel protein into the oocyte cytoplasm from stage 11 of oogenesis. In cleavage embryos the Ketel protein is cytoplasmic. The Ketel gene appears to be ubiquitously expressed in embryonic cells. Western blot analysis revealed that the Ketel gene is not expressed in several larval cell types of late third instar larvae.

[Treatment of chronic myeloid leukemia with interferon-alpha]

The authors have treated 38 patients with chronic phase chronic myeloid leukemia in their single center in the last five years. Conventional chemotherapy provided about 40-50% hematological response, interferon-alpha seems to be more effective, complete hematological remission occurred in 65%. Interphase cytogenetics and fluorescein in situ hybridisation technique was used to measure the cytogenetic response. They observed complete cytogenetic remission in two cases (8%), major response in 11 (39%), minor response in 4 (15%) and minimal response in 4 cases (15%). Interferon-alpha is an effective, well-tolerated medicine in the treatment of chronic myeloid leukemia.

Expression and regulation of neuropilin-1 in human astrocytomas

Vascular endothelial growth factor (VEGF), through activation of its endothelial receptors VEGFR-1 and VEGFR-2, is an important positive modulator of tumor angiogenesis and edema in solid tumors such as malignant astrocytomas. Neuropilin-1 (Npn-1) is a transmembrane receptor expressed by both endothelial and non-endothelial cells, including tumor cells. Npn-1 has been postulated to function as a co-factor in activation of the biologically relevant VEGFR-2, by the most abundant VEGF165 isoform. However, the function of Npn-1 in normal and pathological angiogenesis, its expression pattern in relation to VEGF in tumors such as astrocytomas and whether it is similarly or differentially regulated compared to VEGF remain unknown. In our study, the expression pattern of Npn-1 and VEGF by human astrocytoma cell lines and specimens was closely correlated and associated with malignant astrocytomas. Mitogens, such as epidermal growth factor and activation of p21-Ras, previously demonstrated to be relevant in astrocytoma proliferation and induction of VEGF, also induce Npn-1 expression. Hypoxia, the main physiological inducer of VEGF expression, decreased Npn-1 expression. Increased Npn-1 expression was also demonstrated in a transgenic mouse astrocytoma model. Astrocytomas are an ideal system for furthering our understanding of the functional relevance, if any, of Npn-1 in tumor angiogenesis.

In vivo inhibition of PC-3 human androgen-independent prostate cancer by a targeted cytotoxic bombesin analogue, AN-215

The effectiveness of chemotherapy targeted to bombesin (BN) receptors was evaluated in nude mice bearing PC-3 human androgen-independent prostate cancers. Cytotoxic BN analogue AN-215, consisting of 2-pyrrolinodoxorubicin (AN-201) linked to BN-like carrier peptide RC-3094, was injected i.v. at 150 nmol/kg on days 1, 11 and 21. After treatment with AN-215, tumor volume was 69% (p < 0.01) smaller than that in controls and tumor doubling time was extended from 8.5 +/- 0.7 days to 20.3 +/- 3.5 days (p < 0.05). Cytotoxic radical AN-201, carrier RC-3094 and their unconjugated mixture administered at the same dosage were ineffective. The mortality rate was 12.5% in the AN-201 group and 16.7% in the group treated with the mixture, but no deaths occurred in mice receiving AN-215. Because the ester bond linking AN-201 to the carrier molecule is hydrolyzed much faster in mouse serum than in human serum, in the second experiment we investigated the tolerance to AN-215 and its effect in nude mice bearing PC-3 tumors after pharmacological inhibition of serum carboxylesterases. Two applications of AN-201 at 200 nmol/kg were lethal, whereas no mortality was observed after 4 injections of AN-215 at the same dose. Administration of 200 nmol/kg AN-215 on days 1, 7, 17 and 26 again produced 69% tumor inhibition. BN receptors on membranes of PC-3 tumors were detected by (125)I-[Tyr(4)]BN binding, and expression of mRNA for BRS-3 and GRP-R subtypes was also found. AN-215 showed a high affinity to PC-3 tumors, displacing the radioligand at an IC(50) of 12.95 +/- 0.35 nM. Because BN receptors are present on primary and metastatic prostate cancer, targeted chemotherapy with AN-215 might benefit patients with advanced prostatic carcinoma who relapsed androgen ablation.

[Evaluation of myocardial perfusion using intravenous contrast echocardiography]

The aim of the study was to assess the accuracy of rest myocardial contrast echocardiography (MCE) in detecting perfusion abnormalities after intravenous contrast administration in chronic coronary artery disease. In 21 patients (mean age 49 years) contrast agent was injected intravenously. ATL HDI 5000 ultrasound machine was used. Triggering every fifth cardiac cycle in end-systole apical 2-chamber, 3-chamber and 4-chamber views were used. All patients underwent thallium scintigraphy on the same day and coronary angiography was performed within 24 hours. Second harmonic imaging and power Doppler were used in assessing presence or absence of perfusion, localization and extent of perfusion defects, and their relation with wall motion. In the first group all the 13 patients after myocardial infarction had akinetic segments on echocardiography in accordance with the coronary occlusion detected by coronary angiography. In the second group none of the 8 patients without previous myocardial infarction had wall motion abnormality. Group I: dividing the left ventricle into 16 segments out of 208 segments 44 were akinetic. Perfusion defect was detected by MCE in 29 segments. In 12 segments with wall motion abnormality the normal myocardial perfusion was consistent with viable myocardium, 2 inferior akinetic segments could not be evaluated due to contrast attenuation and in one inferior segment MCE in contrast to the thallium scintigraphy showed no perfusion defect. Group II: good contrast effect was detected in all 128 segments except one inferior segment in which there was a fixed perfusion defect also by thallium scintigraphy and coronary angiography revealed occluded right coronary artery. In conclusion MCE and second harmonic triggered imaging is comparable with thallium scintigraphy in detecting fixed perfusion abnormalities. MCE may contribute to the detection of viable myocardium.

Z/EG, a double reporter mouse line that expresses enhanced green fluorescent protein upon Cre-mediated excision

The Cre/loxP system has become an important tool in designing postintegrational switch mechanisms for transgenes in mice. The power and spectrum of application of this system depends on transgenic mouse lines that provide Cre recombinase activity with a defined cell type-, tissue-, or developmental stage-specificity. We have developed a novel mouse line that acts as a Cre reporter. The mice, designated Z/EG (lacZ/EGFP), express lacZ throughout embryonic development and adult stages. Cre excision, however, removes the lacZ gene, which activates expression of the second reporter, enhanced green fluorescent protein. We have found that the double-reporter Z/EG line is able to indicate the occurrence of Cre excision from early embryonic to adult lineages. The advantage of the Z/EG line is that Cre-mediated excision can be monitored in live samples and that live cells with Cre-mediated excision can be isolated using a single-step FACS. It will be a valuable reagent for the increasing number of investigators taking advantage of the powerful tools provided by the Cre/loxP site-specific recombinase system.

Receptor mediated antiproliferative effects of the cytotoxic LHRH agonist AN-152 in human ovarian and endometrial cancer cell lines

Eighty percent of human ovarian and endometrial cancers express receptors for luteinizing hormone-releasing hormone (LHRH). These receptors might be used for targeted chemotherapy with cytotoxic LHRH analogs such as AN-152, in which doxorubicin is linked to agonist carrier [D-Lys6]LHRH. The antiproliferative effects of doxorubicin and AN-152 were assessed in LHRH receptor-positive ovarian (EFO-21, EFO-27) and endometrial (HEC-1A, Ishikawa) cancer cell lines as well as in LHRH receptor negative ovarian SKOV-3 and endometrial MFE-296 lines. The mechanism of action of AN-152 was investigated by a blockage of receptors using an excess of the LHRH agonist [D-Trp6]LHRH. In some cases, confocal laser-scanning microscopy was used to visualize the accumulation of AN-152 or doxorubicin within the cells. In 3 of 4 LHRH receptor-positive cell lines (EFO-21, HEC-1A, Ishikawa) AN-152 was more effective than doxorubicin in inhibiting cell proliferation. The effect of AN-152 was shown to be receptor-mediated because it could be reduced by competitive blockade of the LHRH receptors with [D-Trp6]LHRH. In contrast, AN-152 was less active than doxorubicin in LHRH receptor-negative lines. Confocal laser-scanning microscopy showed an intranuclear accumulation of AN-152 and competitive inhibition thereof by [D-Trp6]LHRH in LHRH receptor-positive cell lines, but no intracellular accumulation of AN-152 could be detected in the receptor-negative SKOV-3 line. These results suggest a selective receptor-mediated action of AN-152 in receptor-positive cell lines.

Peptide analogs in the therapy of prostate cancer

The use of peptide analogs in the therapy of prostate cancer is reviewed. The preferred primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists. This treatment is likewise recommended in patients with rising PSA levels after surgery or radiotherapy. LH-RH agonists with or without antiandrogens can be also utilized prior to or following various local treatments in patients with clinically localized prostate cancer and at high risk for disease recurrence. LH-RH antagonists like Cetrorelix are in clinical trials. However, most patients with advanced prostatic carcinoma treated by any modality of androgen deprivation eventually relapse. Treatment of relapsed androgen-independent prostate cancer remains a major challenge, but new therapeutic modalities are being developed based on antagonists of growth hormone-releasing hormone (GH-RH) and bombesin, which inhibit growth factors or their receptors. Another approach consists of cytotoxic analogs of LH-RH, bombesin, and somatostatin containing doxorubicin or 2-pyrrolinodoxorubicin, which can be targeted to receptors for these peptides found in prostate cancers and their metastases. These cytotoxic analogs inhibit growth of experimental androgen-dependent or -independent prostate cancers and reduce the incidence of metastases. A rational therapy with peptide analogs could be selected on the basis of receptors present in biopsy samples. The approaches based on peptide analogs should result in a more effective treatment for prostate cancer.

Effective treatment of metastatic MDA-MB-435 human estrogen-independent breast carcinomas with a targeted cytotoxic analogue of luteinizing hormone-releasing hormone AN-207

A highly potent derivative of doxorubicin, 2-pyrrolinodoxorubicin (AN-201), was linked to [D-Lys6]luteinizing hormone-releasing hormone (LH-RH) to form a cytotoxic analogue, AN-207, that can be targeted to LH-RH receptors. The effects of AN-207 were investigated in MDA-MB-435 human estrogen-independent breast carcinomas, which express LH-RH receptors. In experiment 1, nude mice bearing orthotopically implanted tumors received a single i.v. injection of AN-207, AN-201, or the carrier at 250 nmol/kg. Five weeks after administration of AN-207, tumor volume was significantly decreased by 66% (P < 0.001) and tumor burden by 71% (P < 0.05) as compared with controls, but no significant effects occurred in other groups. Six of eight (75%) control animals and 37.5% of mice treated with AN-201 developed metastases in the lymph nodes, whereas no lymphatic spread was found in any of the mice that received injections of AN-207. The antitumor effect of AN-207 could be partially blocked by pretreatment of the tumor-bearing mice with high doses of agonist [D-Trp6]LH-RH, which suggests that AN-207 acts on LH-RH receptors on tumors. The mortality due to toxicity was 25% in the group receiving AN-201 and 12.5% in the AN-207-treated group. Radioligand binding assays revealed the presence of high-affinity binding sites for LH-RH on tumor membranes, and mRNA for LH-RH receptors was demonstrated by reverse transcription-PCR. In experiment 2, two i.v. injections of AN-207 or AN-201 at 150 nmol/kg were given on days 0 and 28 to mice bearing orthotopic xenografts of MDA-MB-435. The outcome of the treatment was similar to that observed in experiment 1, but without any toxicity-related deaths. Tumor growth inhibition and prevention of metastatic disease suggest that cytotoxic LH-RH analogue AN-207 could be considered for the treatment of human estrogen-independent breast cancers expressing receptors for LH-RH.

Human ovarian cancers express somatostatin receptors

Characteristics of receptors for somatostatin (SST) analog RC-160 on 17 surgical specimens of human epithelial ovarian cancer and two human ovarian cancer lines were determined by ligand competition assays. The expression of mRNA for four SST receptor subtypes (sst1, sst2A, sst3 and sst5) was investigated by RT-PCR. Thirteen of 17 specimens (76%) exhibited high affinity binding sites for RC-160 with Kd = 6.55 nmol/L and a Bmax = 575.4 fmol/mg membrane protein. Specific receptors for RC-160 were also found in xenografts of OV-1063 and UCI-107 human ovarian cancer lines. The mRNA for sst1 was detected in 65% of the ovarian cancer specimens, while the incidence of sst2A, sst3 and sst5 was 65%, 41% and 24%, respectively. Both ovarian cancer cell lines also expressed mRNA for these four subtypes. The presence of these SST receptor subtypes in human ovarian cancers allows the use of SST analogs and their radionuclide and cytotoxic derivatives for the diagnosis and treatment of this malignancy.

Identification of mutations in 15 Hungarian families with hereditary protein C deficiency

Hereditary protein C deficiency represents about 2-9% of inherited thrombophilias. Our aim was to elucidate the molecular basis of protein C deficiency in 25 members of 15 Hungarian families with venous thromboembolic diseases and to identify hitherto undescribed genetical defects in the protein C (PROC) gene. The exons of the PROC gene were screened for mutations with the combination of polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE), and/or PCR and single-strand conformation polymorphism (SSCP) analysis. The amplified DNA fragments with aberrant migration during DGGE and SSCP were sequenced. Mutations were determined in the PROC gene in all of the examined families: one nonsense mutation, one rare frameshift deletion and nine different missense mutations, of which three were novel (1493 A-->G, 35Asp-->Gly; 6231 G-->A, 173Gly-->Glu; 8476 C-->T, 254Thr-->Ile). The combination of hereditary protein C deficiency with other hereditary thrombophilias was rather common. DGGE and SSCP were proved to be efficient and cost-effective screening methods in the genetic analysis of hereditary protein C deficiency.

Embryonic development is disrupted by modest increases in vascular endothelial growth factor gene expression

Previous work has shown that heterozygocity for a null mutation of the VEGF-A gene, resulting in a 50% reduction in VEGF-A expression, is embryonic lethal at embroyonic day (E) 9.5 in mice. We now show that two- to threefold overexpression of VEGF-A from its endogenous locus results in severe abnormalities in heart development and embryonic lethality at E12.5-E14. The mutant embryos displayed an attenuated compact layer of myocardium, overproduction of trabeculae, defective ventricular septation and abnormalities in remodeling of the outflow track of the heart. In addition, aberrant coronary development was characterized by formation of oversized epicardial vessels, apparently through vasculogenesis. We infer that embryonic survival requires a narrow window of VEGF-A expression.

[Are the hemochromatosis (HFE) gene mutation and hepatitis C virus (HCV) infection risk factors for porphyria cutanea tarda?]

As it is not clear whether mutations in hemochromatosis gene (HFE) and hepatitis C virus (HCV) act independently in the pathogenesis of porphyria cutanea tarda (PCT), and prevalence of both risk factors reveals a great variety in different parts of the world, PCT patients from our Central East European country were investigated for this aspect. The occurrence of the C282Y and H63D mutations in HFE gene were determined in 19 PCT patients and compared with the reported control frequencies. Furthermore, the presence of HCV infection was determined and related to the patients' HFE status. The C282Y mutation was found in 3/19 cases (one patient was homozygous and two heterozygous), with an 10.5% allele frequency (vs. 3.8% control) (p < 0.05). Five patients were heterozygous for the H63D mutation, allele frequency 13.1%, which did not differ from the reported control prevalence of 12.3%. Six patients (31.7%) were HCV-RNA positive, out of the six one was heterozygous for H63D mutation and one was compound heterozygous. HCV infection and HFE C282Y mutations may probably be independent predisposing factors for development of PCT in Hungarian patients.

The mouse Pdgfc gene: dynamic expression in embryonic tissues during organogenesis

The signaling activity of Platelet-derived growth factors A and B (PDGF-A and PDGF-B) that is mediated through the two receptor kinases, PDGFR-alpha and PDGFR-beta has been shown to be critical for the development of the cardiovascular organs, the kidney, the lung and the central nervous system. During the cloning of genes for VEGF related proteins, we isolated a mouse cDNA that can encode for a protein of 345 amino acids. A comparison of the amino acid sequence reveals that this predicted gene product displays 95% identity to human PDGF-C. The mouse Pdgfc gene maps to a region of chromosome 17 that is syntenic to human chromosome 6p21.3 In E9. 5-E15.5 mouse embryo, Pdgfc is widely expressed in the surface ectoderm and later in the germinal layer of the skin, the olfactory and otic placode and their derivatives and the lining of the oral cavity. In the gut and visceral organs, such as the lung and the kidney, Pdgfc mRNA is first expressed in the endodermal epithelium and later in mesenchymal tissues associated with the endodermal structures. Similar to other PDGFs, Pdgfc is widely expressed in mesenchymal precursors and the myoblast of the smooth and skeletal muscles. Contrary to PDGF-A, Pdgfc is not expressed in the central nervous system, except in the cerebellum, and neurogenic derivatives of the neural crest cells. Pdgfc is also absent from the heart and the vascular endothelium

[Effectiveness of Lisinopril in the treatment of heart failure]

A prospective study was performed in patients (30 M, 16 F, mean age of 56.0 +/- 9.2 [42-73] years) with congestive heart failure to assess the efficacy of lisinopril during a 16 weeks treatment period. Changes in clinical signs, functional capacity, blood pressure, heart rate, echocardiographic parameters, exercise duration, laboratory data and quality of life were measured. After a 2-week run-in period starting daily dose of study drug was 5 mg, and an increase of medication was considered at 4 weeks. At the end of the study mean daily dose of lisinopril was 15.1 +/- 6.2 mg. Improvement of NYHA status by 2 grades was observed in 4 cases (9%), by 1 grade in 24 cases (51%), there was no change in 17 cases (38%), and worsening was observed in 1 case (2%). During the study both systolic (p = 0.001) and diastolic blood pressure (p = 0.0006) decreased significantly, the changes in pulse rate were not significant. Left ventricular end systolic (p = 0.001) and end diastolic (p = 0.003) dimensions decreased, ejection fraction rose by 4.4% (p = 0.0002). One patient was removed from the study because of drug-induced cough. Comparison of all the laboratory data for pre and post-study periods did not reveal any significant difference. Patients treated with lisinopril improved significantly for clinical, haemodynamic, echocardiographic and quality of life parameters, with few adverse experiences, good tolerability and once-daily dose.

Causes of death of patients with multiple injuries in Debrecen, Hungary

OBJECTIVE

To find out the main causes of death of people who had multiple severe injuries.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Hungary.

SUBJECTS

86 people with severe multiple injuries, of whom 59 died and had necropsies.

MAIN OUTCOME MEASURE

Establishment of a database.

RESULTS

Consumption of alcohol was a common precursor. Head and chest injuries predominated. More pedestrians than people in vehicles were killed, and there were 8 suicides and 3 murders. There were no gunshot injuries.

CONCLUSIONS

Reduction of deaths from multiple injuries is as much a socioeconomic as a medical matter.

Inhibition of growth and metastatic progression of pancreatic carcinoma in hamster after somatostatin receptor subtype 2 (sst2) gene expression and administration of cytotoxic somatostatin analog AN-238

The sst2 somatostatin receptor mediates the antiproliferative effects of somatostatin analogs. The present study demonstrates that stable expression of sst2 in the hamster pancreatic cancer cells PC-1 and PC-1.0 activates an autocrine negative loop leading to an in vitro inhibition of cell proliferation. In vivo studies conducted in Syrian golden hamsters after orthotopic implantation of PC-1.0 cells showed that both tumor growth and metastatic progression of allografts containing 100% of sst2-expressing cells were significantly inhibited for up to 20 days after implantation, as compared with control allografts that did not express sst2. A local antitumor bystander effect was observed after induction of mixed tumors containing a 1:3 ratio of sst2-expressing cells to control cells. Tumor volume and incidence of metastases of mixed tumors were significantly reduced at day 13 post implantation. This effect decreased with time as at day 20, growth of mixed tumors was similar to that of control tumors. After administration of the cytotoxic somatostatin conjugate AN-238 on day 13, antitumor bystander effect observed in mixed tumors was significantly extended to day 20. We also observed that in vitro invasiveness of sst2-expressing PC-1.0 cells was significantly reduced. Tyrosine dephosphorylation of E-cadherin may participate in restoring the E-cadherin function, reducing in turn pancreatic cancer cell motility and invasiveness. This dephosphorylation depends on the tyrosine phosphatase src homology 2-containing tyrosine phosphatase 1 (SHP-1) positively coupled to sst2 receptor. The inhibitory effect of sst2 gene expression on pancreatic cancer growth and invasion combined with chemotherapy with targeted cytotoxic somatostatin analog administration provides a rationale for a therapeutic approach to gene therapy based on in vivo sst2 gene transfer.

Regulation of targeted chemotherapy with cytotoxic lutenizing hormone-releasing hormone analogue by epidermal growth factor

Targeting chemotherapy selectively to cancers can reduce the toxic side effects. AN-152, a conjugate of doxorubicin and [D-Lys6]-luteinizing hormone-releasing hormone (LH-RH), is more potent against LH-RH receptor-bearing cancers and produces less peripheral toxicity than doxorubicin. Many cancers, e.g., 50% of breast cancers, but few normal tissues express these receptors, providing a selective target for this cytotoxic conjugate. In this study, the effectiveness of AN-152 was heightened by receptor up-regulation. The cytotoxic effect of AN-152 can be regulated by the number of active LH-RH receptors on cancer cells. LH-RH receptor-positive (MCF-7) and -negative (UCI-107) cancer cells were treated with epidermal growth factor (EGF) or the somatostatin analogue, RC-160. EGF and RC-160 have been shown previously to regulate LH-RH receptors through phosphorylation. The effect of receptor regulation, by hormone exposure, on the cytotoxicity of AN-152 and doxorubicin and on the cellular uptake of AN-152, [D-Lys6]LH-RH, or doxorubicin was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and by two-photon laser scanning microscopy. The results demonstrated that the cellular entry of the conjugate was: (a) specific for cancers with LH-RH receptors; (b) up-regulated by EGF; (c) down-regulated by RC-160; and (d) the cytotoxicity of the AN-152 paralleled the efficiency of entry. This study illustrates the potential use of receptor regulation for increasing the efficacy of chemotherapeutic approaches that are directed to cell surface receptors.

FACS for the isolation of individual cells from transgenic mice harboring a fluorescent protein reporter

Flow cytometry is extensively used for the isolation of discreet populations of cells from complex pools. The advent of autofluorescent (AFP) reporters such as wild type Green Fluorescent Protein (wtGFP) (Chalfie et al., 1994) and its variants, including enhanced green fluorescent protein (EGFP) and enhanced yellow fluorescent protein (EYFP) (Cormack et al., 1996), as vital reporters opens up the possibility of sorting live reporter-expressing cells. Moreover the use of these reporters in transgenics (Okabe et al., 1997) or mice carrying homologously targeted loci (Godwin et al., 1998) should enable the direct isolation of reporter-expressing cells from any desired lineage. Here we have assessed this approach in transgenic mice. ES cell-mediated transgenesis was used for generating a line of mice that express an autofluorescent EYFP reporter in the heart and part of the neural tube at midgestation. Pools of fluorescent cells harboring and expressing the EYFP reporter were isolated from defined regions of embryos and their origin confirmed by assaying the expression of domain-defined marker genes. Such a tool should prove useful for gaining access to any given lineage that can be fluorescent protein reporter tagged.