Dose-response effects of a new growth hormone receptor antagonist (B2036-PEG) on circulating, hepatic and renal expression of the growth hormone/insulin-like growth factor system in adult mice

The effects of growth hormone (GH) in regulating the expression of the hepatic and renal GH and insulin-like growth factor (IGF) system were studied by administering a novel GH receptor antagonist (GHRA) (B2036-PEG) at different doses (0, 1.25, 2.5, 5 and 10 mg/kg/day) to mice for 7 days. No differences were observed in the groups with respect to body weight, food consumption or blood glucose. However, a dose-dependent decrease was observed in circulating IGF-I levels and in hepatic and renal IGF-I levels at the highest doses. In contrast, in the 5 and 10 mg/kg/day GHRA groups, circulating and hepatic transcriptional IGF binding protein-3 (IGFBP-3) levels were not modified, likely resulting in a significantly decreased IGF-I/IGFBP-3 ratio. Hepatic GH receptor (GHR) and GH binding protein (GHBP) mRNA levels increased significantly in all GHRA dosage groups. Endogenous circulatory GH levels increased significantly in the 2.5 and 5 mg/kg/day GHRA groups. Remarkably, increased circulating IGFBP-4 and hepatic IGFBP-4 mRNA levels were observed in all GHRA administration groups. Renal GHR and GHBP mRNA levels were not modified by GHRA administration at the highest doses. Also, renal IGFBP-3 mRNA levels remained unchanged in most GHRA administration groups, whereas IGFBP-1, -4 and -5 mRNA levels were significantly increased in the 5 and 10 mg/kg/day GHRA administration groups. In conclusion, the effects of a specific GHR blockade on circulating, hepatic and renal GH/IGF axis reported here, may prove useful in the future clinical use of GHRAs

The effect of epidermal growth factor and IGF-I infusion on hepatic and renal expression of the IGF-system in adult female rats

Systemic administration of epidermal growth factor (EGF) in neonatal rats results in reduced body weight gain and decreased circulating levels of IGF-I, suggesting its involvement in EGF-induced growth retardation. We investigated the effect of EGF and/or IGF-I administration for 7 days on circulating IGF-I and IGFBP levels and hepatic and renal IGF-system mRNA expression profiles in adult female rats. EGF administration (30 microg/rat/day) did not influence body weight, liver or kidney weight. In contrast, IGF-I (400 microg/rat/day) and EGF/IGF-I administration increased both body weight and kidney weight. Also, serum IGF-I and the 30 kDa IGFBPs (IGFBP-1 and -2) were significantly increased in these groups. Serum IGFBP-3 levels increased in the IGF-I group along with increased hepatic IGFBP-1 and -3 mRNA levels. In contrast, in the EGF administration group serum IGFBP-3 levels were significantly decreased; however, the mRNA levels remained unchanged. In the EGF/IGF-I administration group, serum IGF-I and IGFBP-3 levels were significantly lowered when compared with the IGF-I administration group. This was in contrast to the effect on kidney weight increase that was identical for the IGF-I and EGF/IGF-I groups. The decrease in serum IGFBP-3 was not reflected at the hepatic IGFBP-3 mRNA level. IGFBP-3 expression might be regulated at a post-transcriptional level although EGF induced IGFBP-3 proteolysis could not be demonstrated in vitro. We conclude that EGF administration reduced serum IGFBP-3 whereas IGF-I administration increased the level of IGFBP-3 and IGF-I and resulted in an increased body and kidney weight in adult female rats

Consensus molecular subtype classification of colorectal adenomas

Consensus molecular subtyping is an RNA expression-based classification system for colorectal cancer (CRC). Genomic alterations accumulate during CRC pathogenesis, including the premalignant adenoma stage, leading to changes in RNA expression. Only a minority of adenomas progress to malignancies, a transition that is associated with specific DNA copy number aberrations or microsatellite instability (MSI). We aimed to investigate whether colorectal adenomas can already be stratified into consensus molecular subtype (CMS) classes, and whether specific CMS classes are related to the presence of specific DNA copy number aberrations associated with progression to malignancy. RNA sequencing was performed on 62 adenomas and 59 CRCs. MSI status was determined with polymerase chain reaction-based methodology. DNA copy number was assessed by low-coverage DNA sequencing (n = 30) or array-comparative genomic hybridisation (n = 32). Adenomas were classified into CMS classes together with CRCs from the study cohort and from The Cancer Genome Atlas (n = 556), by use of the established CMS classifier. As a result, 54 of 62 (87%) adenomas were classified according to the CMS. The CMS3 ‘metabolic subtype’, which was least common among CRCs, was most prevalent among adenomas (n = 45; 73%). One of the two adenomas showing MSI was classified as CMS1 (2%), the ‘MSI immune’ subtype. Eight adenomas (13%) were classified as the ‘canonical’ CMS2. No adenomas were classified as the ‘mesenchymal’ CMS4, consistent with the fact that adenomas lack invasion-associated stroma. The distribution of the CMS classes among adenomas was confirmed in an independent series. CMS3 was enriched with adenomas at low risk of progressing to CRC, whereas relatively more high-risk adenomas were observed in CMS2. We conclude that adenomas can be stratified into the CMS classes. Considering that CMS1 and CMS2 expression signatures may mark adenomas at increased risk of progression, the distribution of the CMS classes among adenomas is consistent with the proportion of adenomas expected to progress to CRC

Activin a stimulates AKR1C3 expression and growth in human prostate cancer

Local androgen synthesis in prostate cancer (PC) may contribute to the development of castration-resistant PC (CRPC), but pathways controlling intratumoral steroidogenic enzyme expression in PC are unknown. We investigated the effects of activin, a factor involved in the regulation of PC growth and steroidogenic enzyme expression in other steroidogenic tissues, on intratumoral steroidogenesis in PC. Activin A effects and regulation of the activin-signaling pathway molecules were studied in the PC cell lines LNCaP, VCaP, and PC-3 and in 13 individual PC xenograft models. Also, expression levels of inhibin βA- and βB-subunits (INHBA and INHBB) and of the activin antagonist follistatin were quantitated in patient PC tissues. Activin A induced the expression and enzyme activity of 17β-hydroxysteroid dehydrogenase enzyme AKR1C3 in LNCaP and VCaP cells. Inhibition of endogenous activin A action in the PC-3 cell line decreased AKR1C3 levels and consequently testosterone synthesis. In return, androgens suppressed INHBA expression in both VCaP cells and the PC xenograft models. The antiproliferative effects of activin A were opposed by physiological concentrations of androstenedione in LNCaP cells. In patient PC tissues, expression levels of INHBA were increased in CRPC samples and correlated with AKR1C3 levels. Moreover, a high ratio of activin subunits to follistatin was associated with a worse metastasis-free survival in patients. In conclusion, activin A is controlled by androgens in PC models and regulates local androgen production. Activin A thus seems to mediate (residual) intratumoral androgen levels and could form a n