Breast cancer and cytomegalovirus.

PURPOSE: To determine whether cytomegalovirus is causally associated with breast cancer and whether cytomegalovirus should be categorised as an oncogenic virus. METHODS: We undertook a review of published epidemiological and laboratory studies, using established causal criteria: Bradford Hill criteria to determine whether cytomegalovirus is associated with breast cancer; and Evans/Mueller criteria to determine whether cytomegalovirus should be categorised as an oncogenic virus. RESULTS: Although there are inconsistencies in the findings of published epidemiological and laboratory studies, these may be explained by factors such as: differences in timing of blood samples, differences in selection of cases and controls, or high cytomegalovirus seroprevalence among participants in the epidemiological studies; and, in the laboratory studies, differences in sample preparations, age of sample, whether or not paired breast cancer and normal breast tissue samples were used, differences in the tests, primers and/or antibodies used, differences in histological types of breast cancer studied, and/or features of the virus. CONCLUSIONS: Overall, the results of published studies of cytomegalovirus and breast cancer suggest cytomegalovirus is a causal factor for at least some types of breast cancer. If the evidence for a link between cytomegalovirus and breast cancer continues to strengthen, further research could lead to: targeted screening; therapy using antiviral drugs; and, perhaps, primary prevention of a significant proportion of breast cancer. Vaccination against viruses has already been shown to be effective in preventing cervix and liver cancer; cytomegalovirus vaccines are already under development.

Translating colorectal cancer genetics into clinically useful biomarkers.

Colorectal cancer (CRC) is a major health problem worldwide accounting for over a million deaths annually. While many patients with Stage II and III CRC can be cured with combinations of surgery, radiotherapy and chemotherapy, this is morbid costly treatment and a significant proportion will suffer recurrence and eventually die of CRC. Increased understanding of the molecular pathogenesis of CRC has the potential to identify high risk patients and target therapy more appropriately. Despite increased understanding of the molecular events underlying CRC development, established molecular techniques have only produced a limited number of biomarkers suitable for use in routine clinical practice to predict risk, prognosis and response to treatment. Recent rapid technological developments, however, have made genomic sequencing of CRC more economical and efficient, creating potential for the discovery of genetic biomarkers that have greater diagnostic, prognostic and therapeutic capabilities for the management of CRC. This paper reviews the current understanding of the molecular pathogenesis of CRC, and summarizes molecular biomarkers that surgeons will encounter in current clinical use as well as those under development in clinical and preclinical trials. New molecular technologies are reviewed together with their potential impact on the understanding of the molecular pathogenesis of CRC and their potential clinical utility in classification, diagnosis, prognosis and targeting of therapy.

Association of angiopoietin-2, C-reactive protein and markers of obesity and insulin resistance with survival outcome in colorectal cancer.

BACKGROUND: This study investigated the relationship of obesity, insulin resistance, inflammation and angiogenesis with cancer progression and survival in a colorectal cancer cohort. METHODS: Clinical and pathological data, along with anthropometric and follow-up data, were collected from 344 consecutive colorectal cancer patients. Serum samples at diagnosis were analysed by immunoassay for adiponectin, C-reactive protein (CRP), vascular endothelial growth factor-A (VEGF-A), angiopoietin-2 (Ang-2), insulin-like growth factor-1 (IGF-1), insulin and C-peptide. RESULTS: Serum Ang-2 and VEGF-A levels increased with tumour T stage (P=0.007 and P=0.025, respectively) and N stage (P=0.02 and P=0.03, respectively), and correlated with CRP levels (r=0.43, P<0.001 and r=0.23, P<0.001, respectively). Angiopoietin-2 correlated with C-peptide (r=0.14, P=0.007) and VEGF-A with IGF-1 in males (r=0.25, P=0.001). Kaplan-Meier analysis showed that patients with high serum levels of CRP and Ang-2 had significantly reduced survival (both P≤0.001). After adjusting for tumour stage and age, Ang-2 remained a significant predictor of survival. The CRP levels were inversely associated with survival in American Joint Committee on Cancer stage II patients (P=0.038), suggesting that CRP could be used to support treatment decisions in this subgroup. Serum markers and anthropometric measures of obesity correlated with each other, but not with survival. CONCLUSION: Our study supports the concept that obesity-related inflammation, rather than obesity itself, is associated with colorectal cancer progression and survival. The study confirms serum Ang-2 as a predictive marker for outcome of colorectal cancer.

Myocardial metastasis of cutaneous squamous cell carcinoma in a renal transplant recipient.

Myocardial metastasis from a cutaneous squamous cell carcinoma (SCC) is rare. Herein we have presented a case of metastasis from cutaneous SCC to the myocardium in a renal transplant recipient, which was confirmed by a cardiac fine-needle biopsy. Postmortem examination revealed disseminated metastatic disease involving myocardium, lungs, thyroid, skin, and peritoneum secondary to cutaneous SCC likely related to immunosuppression. At 46 years of age, he received a renal transplant for chronic renal failure caused by chronic glomerulonephritis. He started to develop multiple nonmelanoma skin cancers 4 years later. At least 23 invasive SCCs and 14 basal cell carcinomas were excised. His immunosuppressive regimen consisted of cyclosporine (150 mg), azathioprine (75 mg), and prednisone (10 mg daily), which was not modified despite multiple nonmelanoma skin cancers. Our case report further illustrates the potentially aggressive and fatal nature of cutaneous SCCs that can develop in organ transplant recipients. It argues for modification of the immunosuppressive regimen in such patients. The management of renal transplant patients with nonmelanoma skin cancers remains difficult and complex.

The angiogenic factor thymidine phosphorylase up-regulates the cell adhesion molecule P-selectin in human vascular endothelial cells and is associated with P-selectin expression in breast cancers.

Thymidine phosphorylase (TP) is an angiogenic enzyme, catalysing the reversible phosphorylation of thymidine to thymine and 2-deoxyribose. TP is up-regulated in neoplasia, being associated with advanced tumour stage, microvessel density and prognosis in several tumour types. Although TP is a non-mitogenic migratory factor for endothelium, the mechanism by which TP mediates these effects is still unclear. We compared the gene expression profile of endothelial cells grown in vitro in the presence or absence of TP by cDNA microarray analysis. To determine the time-course of TP angiogenic induction, endothelial cells were stimulated with TP (10 ng/ml) for 5 and 18 h. Gene expression levels of Tie2, angiopoietin (Ang)1 and Ang2, measured by RNase protection assay (RPA), showed maximal alteration at 18 h. cDNA from human umbilical vein endothelial cells (HUVEC) grown for 18 h in the presence or absence of TP (10 ng/ml) was hybridized to a human cDNA cytokine array representing 375 angiogenic genes. Significantly altered expression occurred in 89 human angiogenic genes (72 genes were up-regulated and 17 down-regulated). Changes in five genes relevant to vascular remodelling biology (Tie2, nNos, P-selectin, ephrin-B1 and TP) were validated in triplicate experiments by real-time RT-PCR. But only P-selectin gene expression remained significant. Correlation between P-selectin and TP was assessed by immunohistochemistry on 161 human breast cancers, using human tissue microarray. Tumour cell TP correlated with tumour cell P-selectin but not with endothelial cell P-selectin. These data show that TP stimulates changes in mRNA expression maximally after 18 h culture in vitro. It confirms a role for TP in vascular remodelling involving several classes of genes, including the cell adhesion molecule, P-selectin. Although confirmation of the role of TP-mediated cell adhesion molecule (CAM) induction is required; however, this pathway may provide an attractive therapeutic target, since it is likely to affect several important tumour processes, including angiogenesis and metastasis.

Expression of vascular endothelial growth factor D is associated with hypoxia inducible factor (HIF-1alpha) and the HIF-1alpha target gene DEC1, but not lymph node metastasis in primary human breast carcinomas.

BACKGROUND: Vascular endothelial growth factor D (VEGF-D) induces angiogenesis and lymphangiogenesis. Nodal metastasis is recognised as a powerful prognostic marker in breast carcinoma, but the molecular mechanisms underlying this process are unknown. Although it has been suggested that VEGF-D may regulate nodal metastasis, this is based largely on animal models, its role in human disease being unclear. AIMS: To measure the pattern and degree of VEGF-D protein expression in normal and neoplastic human breast tissues. METHODS: The pattern and degree of VEGF-D expression was measured in normal tissue and invasive carcinomas, and expression was correlated with clinicopathological parameters, hypoxia markers, and survival. Because other VEGF family members are affected by oestrogen, whether VEGF-D is regulated by oestrogen in breast cancer cell lines was also assessed. RESULTS: VEGF-D was significantly positively associated with hypoxia inducible factor (HIF-1alpha) (p = 0.03) and the HIF-1alpha regulated gene DEC1 (p = 0.001), but not lymph node status, the number of involved lymph nodes, patient age, tumour size, tumour grade, lymphovascular invasion, oestrogen receptor, progesterone receptor, c-erb-B2, or tumour histology (all p>0.05). There was no significant relation between tumour VEGF-D expression and relapse free (p = 0.78) or overall (p = 0.94) survival. VEGF-D expression was enhanced by oestrogen in MCF-7 and T47D breast cancer cells, and was blocked by hydroxytamoxifen. CONCLUSION: These findings support a role for hypoxia and oestrogen induced VEGF-D in human breast cancer and also suggest that tamoxifen and related oestrogen antagonists may exert some of their antitumour effects through the abrogation of VEGF-D induced function.

Modelling kiwifruit budbreak as a function of temperature and bud interactions.

This paper presents two models of budbreak on canes of 'Hayward' kiwifruit (Actinidia deliciosa). A conventional 'chill unit' (CU) type model is compared with an alternative 'loss of potential' (LOP) approach, which assumes that the number of buds developing in spring depends on climate and node position-dependent bud-to-bud interactions that vary in duration and intensity. Both models describe how temperature, and application of a dormancy-breaking chemical, determine the overall amount of budbreak for whole canes. However, the LOP model does so by describing patterns of budbreak along canes. To do this, the cumulative influence of distal neighbours is assumed to cause a progressive fall in the capacity for bud development over the autumn-winter period, an influence that gets stronger as temperature rises. The LOP model also assumes that the rate of decline varies along the cane, as a function of some inherent bud property. These two factors mean that buds towards the base of the cane break less often under the suppressive influence of distal neighbours, while low temperature ('chilling') increases budbreak by diminishing the intensity of suppression relative to bud development rate. Under this scenario, dormancy-breaking chemicals (such as hydrogen cyanamide, HC) enhance budbreak by diminishing the duration of suppression. Models were calibrated using daily temperature series and budbreak proportion data from a multi-year regional survey, and were then tested against independent data sets. Both models were run from a fixed start date until the time budbreak was almost complete, or until a standard date. The fitted models described 87 % of variation in amount of budbreak due to site, year, HC and node position effects in the original data set. Results suggest that the correlation between chilling and the amount of budbreak can be interpreted as a population-based phenomenon based on interaction among buds.

Vascular endothelial growth factor-B and vascular endothelial growth factor-C expression in renal cell carcinomas: regulation by the von Hippel-Lindau gene and hypoxia.

Angiogenesis is essential for tumor growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B and VEGF-C, two new VEGF family members, have been identified that bind to the tyrosine kinase receptors flt-1 (VEGFR1), KDR (VEGFR2), and flt-4 (VEGFR3). Although the importance of VEGF-A has been shown in renal carcinomas, the contribution of these new ligands in kidney tumors is not clear. We have, therefore, measured the mRNA level of VEGF-B and VEGF-C together with their receptors by RNase protection assay (RPA) in 26 normal kidney samples and 45 renal cell cancers. We observed a significant up-regulation of VEGF-B (P = 0.002) but not VEGF-C (P = 0.3) in neoplastic kidney compared with normal tissues. In addition, although VEGF receptors were higher in tumors than normal kidney, there was a significant up-regulation of only flt-1 (P = 0.003) but not KDR (P = 0.12) or flt-4 (P = 0.09). There was also a significant correlation between VEGF-C and both of its receptors flt-4 (P = 0.006) and KDR (P = 0.03) but no association between VEGF-B and its receptor flt-1 (P = 0.23). A significant increase was observed in flt-1 (P < 0.001), KDR (P = 0.02), and flt-4 (P = 0.01) but not VEGF-B (P = 0.82) or VEGF-C (P = 0.52) expression in clear cell compared with chromophil (papillary) carcinomas. No significant association was demonstrated between VEGF-B, VEGF-C, flt-1, KDR, and flt-4 with patient sex, patient age, or tumor size (P > 0.05). The effect of von Hippel-Lindau (VHL) gene and hypoxia on VEGF-B and VEGF-C expression in the renal carcinoma cell line 786-0 transfected with wild-type and mutant VHL was determined by growing cells under 21% O2- and 0.1% O2. In wild-type VHL cells, whereas VEGF-A was significantly up-regulated under hypoxic compared with normoxic conditions (P < 0.001), expression of VEGF-C was reduced (P < 0.002). Nevertheless, the repression of VEGF-C was lost in mutant VHL cell lines under hypoxia. In contrast VEGF-B was not regulated by VHL despite clear up-regulation in vivo. These findings strongly support an enhanced role for this pathway in clear cell carcinomas by regulating angiogenesis and/or lymphangiogenesis. The study shows that clear cell tumors are able to up-regulate angiogenic growth factor receptors more efficiently than chromophil (papillary), that clear cell tumors can use pathways independent of VHL to regulate angiogenesis, and that this combined regulation may account for their more aggressive phenotype, which suggests that targeting VEGFR1 (flt-l) may be particularly effective in these tumor types.

Angiopoietin-1 is inversely related to thymidine phosphorylase expression in human breast cancer, indicating a role in vascular remodeling.

PURPOSE: Angiogenesis is essential for tumor growth and metastasis. It is a complex, dynamic process that is coordinated by several classes of angiogenic factors. One candidate family is the Tie2 tyrosine kinase, whose expression is restricted largely to endothelial cells. Tie2 has three known ligands, angiopoietin (Ang)-1, Ang-2, and Ang-4, that have different functional effects but play a requisite role in embryonic vessel remodeling. Because there are only limited data on the Tie2 pathway in human breast cancer, and our previous data have suggested that breast tumors establish a blood supply by vascular remodeling, we have investigated the expression of Ang-1, Ang-2, Ang-4, and Tie2 in a series of normal and neoplastic human breast tissues. EXPERIMENTAL DESIGN: We examined mRNA expression by reverse transcription-PCR in 6 normal and 52 malignant breast tissues and correlated expression with clinicopathological and angiogenic variables. We also examined the effect of physiological levels of estrogen on Ang expression. RESULTS: Ang-1, Ang-2, Ang-4, and Tie2 were detected in 19%, 52%, 35%, and 65%, respectively, of tumor samples. There was a significant reduction in expression of tumor Ang-1 (P = 0.04), Ang-2 (P = 0.01), Ang-4 (P = 0.004), and Tie2 (P = 0.02) compared with that in normal breast tissues. There was a significant relationship in tumors between all Angs and between each ligand and Tie2. In a multivariate analysis, there were significant positive correlations between Ang-4 and estrogen receptor (P = 0.016) and a significant inverse correlation between Ang-1 and thymidine phosphorylase expression (P = 0.01). No significant associations were observed between the other members of the Ang/Tie2 gene family and patient age, tumor size, lymph node status, tumor grade, vascular invasion, tumor vascularity, vascular maturation, thymidine phosphorylase, or vascular endothelial growth factor A expression (P > 0.05 for all). The potential regulation of Ang-4 by estrogen was further investigated in vitro. Addition of physiological concentrations of 17beta-estradiol (1 nM) to hormone-free media caused no significant change in Ang-4 mRNA abundance (P = 0.75) in the estrogen receptor-positive cell line MCF-7 after either 2 or 18 h, despite demonstrating induction for the estrogen response gene pS2. CONCLUSIONS: These findings suggest that the Ang/Tie2 pathway plays a significant role in human breast tumor angiogenesis but provide no initial evidence for direct regulation of the pathway by estrogen.

VEGF-B expression in human primary breast cancers is associated with lymph node metastasis but not angiogenesis.

Angiogenesis is essential for tumour growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B, a new VEGF family member that binds to the tyrosine kinase receptor flt-1, has been identified. Although the importance of VEGF has been shown in many human tumour types, the contribution of VEGF-B to tumour neovascularization is unknown in any tumour type. This study therefore measured the mRNA level of VEGF-B and its receptor flt-1 by ribonuclease protection assay and the pattern of VEGF-B expression by immunohistochemistry in 13 normal breast samples and 68 invasive breast cancers. Flt-1 expression was significantly higher in tumours than in normal breast (p=0.02) but no significant difference was seen in VEGF-B between normal and neoplastic breast (p=0.3). There was a significant association between VEGF-B and node status (p=0.02) and the number of involved nodes (p=0.01), but not with age (p=0.7), size (p=0.6), oestrogen receptor (ER) (p=0.2), grade (p=0.5) or vascular invasion (p=0.16). No significant relationship was present between VEGF-B and flt-1 (p=0.2) or tumour vascularity (p=0.4). VEGF-B was expressed mostly in the cytoplasm of tumour cells, although occasional stromal components including fibroblasts and endothelial cells were also positive. No difference in VEGF-B expression was observed adjacent to regions of necrosis, in keeping with this VEGF family member not being hypoxically regulated. These findings suggest that VEGF-B may contribute to tumour progression by a non-angiogenic mechanism, possibly by increasing plasminogen activators and hence metastasis, as has been described in vitro. Measurement of VEGF-B together with other angiogenic factors may identify a poor prognostic patient group, which may benefit from anti-VEGF receptor therapy targeted to flt-1 (VEGFR1) as well as kdr (VEGFR2).

The short form of the alternatively spliced flt-4 but not its ligand vascular endothelial growth factor C is related to lymph node metastasis in human breast cancers.

Angiogenesis is essential for tumor growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently, VEGF-C, a new VEGF family member, has been identified that binds to the tyrosine kinase receptors flt-4 [VEGF receptor (VEGFR) 3] and KDR (VEGFR2). Although the importance of VEGF has been shown in many human tumor types, the contribution of VEGF-C and its primary receptor flt-4 to tumor progression is less well understood. We have therefore measured the level of VEGF-C, flt-4, and KDR mRNA by RNase protection assay and the pattern of VEGF-C expression by immunohistochemistry in 11 normal breast tissue samples and 61 invasive breast cancers. No significant difference in VEGF-C expression was observed between normal and neoplastic breast tissues (P = 0.11). There was a significant correlation between VEGF-C and both flt-4 (P = 0.02) and KDR (P = 0.0002), but no association was seen between VEGF-C and either lymph node status (P = 0.66) or number of involved nodes (P = 0.88), patient age (P = 0.83), tumor size (P = 0.20), estrogen receptor status (P = 0.67), or tumor grade (P = 0.35). No significant relationship was present between VEGF-C and vascular invasion (P = 0.30), tumor vascularity (P = 0.21), VEGF-A (P = 0.62), or thymidine phosphorylase expression (P = 1.00). VEGF-C was expressed predominantly in the cytoplasm of tumor cells, although occasional stromal components including fibroblasts were also positive. We could demonstrate no association between lymph node metastasis and either VEGF-C (P = 0.66) or flt-4 (P = 0.4). However, we did observe a significant loss of the long but not the short isoform of flt-4 in tumors compared with normal tissues (P = 0.02 and P = 0.25, respectively), and this difference was largely accounted for by the reduction of long flt-4 in node-positive tumors. These findings strongly support a role for VEGF-C/flt-4 signaling in tumor growth by enhancement of angiogenesis and/or lymphangiogenesis and suggest that differential regulation of these processes may be controlled via flt-4 isoform transcription. They further suggest that the measurement of flt-4 isoform expression may identify a patient group that is likely to have node-positive disease and therefore benefit from additional treatment and also emphasize an additional ligand interaction that could be exploited by anti-VEGFR therapy.

Early discharge and postnatal depression: a prospective cohort study.

OBJECTIVES: To determine whether women discharged from hospital < or = 72 hours after childbirth (early discharge) were at greater risk of developing symptoms of postnatal depression during the following six months than those discharged later (late discharge), their reasons for early discharge and their level of postnatal support. DESIGN AND SETTING: Population-based, prospective cohort study with questionnaires at Day 4, and at 8, 16 and 24 weeks postpartum, conducted at all birth sites in the Australian Capital Territory (ACT). PARTICIPANTS: Women resident in the ACT giving birth to a live baby from March to October 1997. MAIN OUTCOME MEASURE: A score > 12 on the Edinburgh Postnatal Depression Scale (EPDS). RESULTS: 1295 (70%) women consented to participate; 1193 (92%) were retained in the study to 24 weeks and, of these, 1182 returned all four questionnaires. Of the 1266 women for whom length-of-stay data were available, 467 (37%) were discharged early and 799 (63%) were discharged late. There were no significant differences between the proportion of women discharged early who ever scored > 12 on the EPDS during the six postpartum months and those discharged late (17% v. 20%), even after controlling for other risk factors (adjusted OR, 0.67; 95% CI, 0.44-1.01). Of women discharged early, 93% had at least one postnatal visit at home from a midwife and 81% were "very satisfied" with the care provided. Most women (96%) reported they had someone to help in practical ways. CONCLUSIONS: Women discharged early after childbirth do not have an increased risk of developing symptoms of postnatal depression during the following six months.

The effects of ovine placental lactogen and bovine growth hormone on hepatic and mammary gene expression in lactating sheep.

The ability of ovine placental lactogen (oPL) to bind to the growth hormone receptor (GHR) raises the possibility that oPL may exert a growth hormone (GH)-like action on galactopoiesis. We have compared the effects of treating lactating ewes for 5 days with an equimolar dose (0.1 mg/kg/day, administered as two equal doses 12 hourly) of either bovine growth hormone (bGH) (n = 10), oPL (n = 10) or saline (n = 9) on hepatic and mammary GHR, insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) gene expression and hepatic GHR number. Hepatic GHR and IGFBP-3 mRNA were unaltered by bGH or oPL treatment. Hepatic IGF-I mRNAs increased following bGH (P < 0.05) but not oPL treatment. GHR gene expression was greater in liver compared to mammary gland extracts. There was no effect of either bGH or oPL treatment on mammary GHR, IGF-I or IGFBP-3 mRNA or hepatic GHR number. These studies confirm the galactopoietic effects of bGH in lactating ruminants and suggest that the mechanism of this action is not via increased hepatic GHR number or gene expression. In addition, the increase in hepatic but not mammary IGF-I mRNA with bGH treatment suggests an endocrine action of IGF-I on milk synthesis. These studies also demonstrate that an equimolar dose of oPL is not galactopoietic or somatogenic in the lactating ewe.

Ovine glucose transporter-1 and -3: cDNA partial sequences and developmental gene expression in the placenta.

Transplacental glucose transfer utilizes specific glucose transporter (GLUT) proteins. cDNAs encoding ovine placental GLUT1 and GLUT3 genes were isolated, cloned and sequenced and then used to investigate their developmental regulation in ovine placenta. A cDNA of approximately 2.2 kb was isolated from a Clontech lambda gt10 ovine adult liver cDNA library using a 436-bp rat GLUT1 cDNA probe. Sequence data obtained from this clone (1600 bp) demonstrated 97 per cent homology to nucleotides 477-2079 of bovine GLUT1. The deduced amino acid sequence of the ovine cDNA presented 99 per cent identity to amino acid 103-493 of bovine GLUT1, and 97-98 per cent identity to corresponding regions in human and rat GLUT1 deduced amino acid sequences. Reverse transcription-PCR (RT-PCR) was used to isolate an ovine cDNA fragment from placental total RNA. Forward and reverse primers (16 mer) were designed to amplify a predicted 483-bp fragment between the second transmembrane-spanning domain (M2) and intracellular loop of GLUT3. The deduced 161 amino acid sequence of the ovine cDNA demonstrated 84 and 88 per cent identity with murine and human GLUT3. These cDNAs were used to investigate the ontogeny of placental oGLUT1 and oGLUT3 gene expression by Northern analysis. Total RNA was extracted from ovine placenta at gestational days 45, 60, 90, 120 and 138 (n=6 per time point). Ovine GLUT1 gene expression increased significantly from days 45 to 60 (P<0.05), peaked at around day 120 of gestation, then decreased to about two-thirds of maximal levels by day 138 of gestation (term 147 +/- 2). Ovine GLUT3 gene expression increased throughout gestation with significant increases from days 45 to 60, 60 to 120 and 120 to 138 (P<0.05). This study confirms the presence of both GLUT1 and GLUT3 genes in the ovine placenta and demonstrates ontogenic regulation of gene expression. The difference in temporal gene expression between oGLUT1 and oGLUT3 suggests distinct roles for each transporter during development. The nucleotide sequences reported in this paper have been submitted to the GenBank/EMBL Data Bank under accession numbers U89029 (oGLUT1) and U89030 (oGLUT3).

Differential effects of maternal ovine placental lactogen and growth hormone (GH) administration on GH receptor, insulin-like growth factor (IGF)-1 and IGF binding protein-3 gene expression in the pregnant and fetal sheep.

The role of placental lactogen (PL) in the regulation of maternal metabolism and fetal growth is not understood. Both PL and growth hormone (GH) have been suggested as possible regulators of mammogenesis. Our aim was to compare the effects of recombinant ovine placental lactogen (oPL) and bovine growth hormone (bGH) on maternal mammary gland development and fetal growth. Pregnant ewes were treated from day 101 to 107 of gestation with twice daily subcutaneous injections of recombinant oPL (n = 7), bGH (n = 8) (0.15 mg/kg live weight/day) or saline (n = 8). On day 108 of gestation, fetal and maternal tissues were collected. The relative abundance of growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) mRNA was assessed in mammary gland, maternal liver and heart, and in fetal and placental tissues. There was no detectable change in mammary tissue GHR, IGF-1 or IGFBP-3 gene expression with either bGH or oPL treatment. Maternal administration of bGH, but not oPL, during pregnancy caused an increase in maternal hepatic IGF-1 gene expression (P < 0.005). Treatment with oPL, but not bGH, resulted in a significant increase (P < 0.025) in the relative abundance of fetal hepatic IGFBP-3 mRNA. Maternal hepatic GHR gene expression was not affected by treatment. This study suggests that while bGH treatment of pregnant ewes induces characteristic somatogenic responses, oPL treatment does not have comparable effects. However, oPL may indirectly influence the fetal somatotropic axis by altering fetal hepatic IGFBP-3 production.