Comparison of pulsatile vs. continuous administration of human placental growth hormone in female C57BL/6J mice.

Exogenous growth hormone has different actions depending on the method of administration. However, the effects of different modes of administration of the placental variant of growth hormone on growth, body composition and glucose metabolism have not been investigated. In this study, we examined the effect of pulsatile vs. continuous administration of recombinant variant of growth hormone in a normal mouse model. Female C57BL/6J mice were randomized to receive vehicle or variant of growth hormone (2 or 5 mg/kg per day) by daily subcutaneous injection (pulsatile) or osmotic pump for 6 days. Pulsatile treatment with 2 and 5 mg/kg per day significantly increased body weight. There was also an increase in liver, kidney and spleen weight via pulsatile treatment, whereas continuous treatment did not affect body weight or organ size. Pulsatile treatment with 5 mg/kg per day significantly increased fasting plasma insulin concentration, whereas with continuous treatment, fasting insulin concentration was not significantly different from the vehicle-treated control. However, a dose-dependent increase in fasting insulin concentration and decrease in insulin sensitivity, as assessed by HOMA, was observed with both modes of treatment. At 5 mg/kg per day, hepatic growth hormone receptor expression was increased compared to vehicle-treated animals, by both modes of administration. Pulsatile variant of growth hormone did not alter the plasma insulin-like growth factor-1 concentration, whereas a slight decrease was observed with continuous variant of growth hormone treatment. Neither pulsatile nor continuous treatment affected hepatic insulin-like growth factor-1 mRNA expression. Our findings suggest that pulsatile variant of growth hormone treatment was more effective in stimulating growth but caused marked hyperinsulinemia in mice.

Growth hormone receptor antagonism suppresses tumour regrowth after radiotherapy in an endometrial cancer xenograft model.

Human GH expression is associated with poor survival outcomes for endometrial cancer patients, enhanced oncogenicity of endometrial cancer cells and reduced sensitivity to ionising radiation in vitro, suggesting that GH is a potential target for anticancer therapy. However, whether GH receptor inhibition sensitises to radiotherapy in vivo has not been tested. In the current study, we evaluated whether the GH receptor antagonist, pegvisomant (Pfizer), sensitises to radiotherapy in vivo in an endometrial tumour xenograft model. Subcutaneous administration of pegvisomant (20 or 100 mg/kg/day, s.c.) reduced serum IGF1 levels by 23% and 68%, respectively, compared to vehicle treated controls. RL95-2 xenografts grown in immunodeficient NIH-III mice were treated with vehicle or pegvisomant (100 mg/kg/day), with or without fractionated gamma radiation (10 × 2.5 Gy over 5 days). When combined with radiation, pegvisomant significantly increased the median time tumours took to reach 3× the pre-radiation treatment volume (49 days versus 72 days; p = 0.001). Immunohistochemistry studies demonstrated that 100 mg/kg pegvisomant every second day was sufficient to abrogate MAP Kinase signalling throughout the tumour. In addition, treatment with pegvisomant increased hypoxic regions in irradiated tumours, as determined by immunohistochemical detection of pimonidazole adducts, and decreased the area of CD31 labelling in unirradiated tumours, suggesting an anti-vascular effect. Pegvisomant did not affect intratumoral staining for HIF1α, VEGF-A, CD11b, or phospho-EGFR. Our results suggest that blockade of the human GH receptor may improve the response of GH and/or IGF1-responsive endometrial tumours to radiation.

Trefoil factor 3 (TFF3) enhances the oncogenic characteristics of prostate carcinoma cells and reduces sensitivity to ionising radiation.

Trefoil factor 3 (TFF3) is a secreted protein which functions in mucosal repair of the gastrointestinal tract. This is achieved through the combined stimulation of cell migration and prevention of apoptosis and anoikis, thus facilitating repair. Deregulated TFF3 expression at the gene and protein level is implicated in numerous cancers. In prostate cancer TFF3 has previously been reported as a potential biomarker, overexpressed in a subset of primary and metastatic cases. Here we investigated the effect of increased TFF3 expression on prostate cancer cell behaviour. Oncomine analysis demonstrated that TFF3 mRNA expression was upregulated in prostate cancer compared to normal tissue. Forced-expression models were established in the prostate cancer cell lines, DU145 and PC3, by stable transfection of an expression vector containing the TFF3 cDNA. Forced expression of TFF3 significantly increased total cell number and cell viability, cell proliferation and cell survival. In addition, TFF3 enhanced anchorage independent growth, 3-dimensional colony formation, wound healing and cell migration compared to control transfected cell lines. We also observed reduced sensitivity to ionising radiation in stably transfected cell lines. In dose response experiments, forced expression of TFF3 significantly enhanced the regrowth of PC3 cells following ionising radiation compared with control transfected cells. In addition, TFF3 enhanced clonogenic survival of DU145 and PC3 cells. These studies indicate that targeting TFF3 for the treatment of prostate cancer warrants further investigation.

Postmortem review and genetic analysis in sudden infant death syndrome: an 11-year review.

Sudden infant death syndrome (SIDS) is the unexpected death of a child younger than 1 year that remains unexplained after thorough evaluation. The possibility of an underlying primary arrhythmogenic disorder has been proposed as a potential cause of SIDS. This study sought to review SIDS deaths and to perform genetic analysis in key genes that may contribute to sudden death. From 2000 to 2010, all postmortem records from the Department of Forensic Medicine in Sydney, Australia, were reviewed. Cases that gave the cause of death as "SIDS" or "undetermined" but consistent with SIDS were included. In a subset of cases, the hyperpolarization-activated cyclic nucleotide (HCN)-gated channel family of genes (HCN2 and HCN4) was analyzed. A total of 226 SIDS cases were identified; 61% were male, 41% occurred while bed sharing, and there was a peak in deaths between 2 and 4 months old. The incidence did not decrease over the study period. In a subgroup of SIDS cases (n = 46), genetic analysis identified 2 likely pathogenic variants (2/46; 4%). A novel nonsynonymous variant, HCN4-Ala195Val, predicted to be pathogenic, was identified in a female infant who died at age 4 months. A female infant aged 5 weeks carried a rare nonsynonymous variant, HCN4-Val759Ile, which is similar to previously described variants associated with cardiac arrhythmias. In conclusion, the incidence of SIDS remains constant, with no apparent decline in the last decade. The underlying cause of SIDS remains largely unknown. Mutations in cardiac ion channel genes including rare nonsynonymous HCN gene variants may play a role in the pathogenesis of some SIDS cases.