Estrogens regulate the hepatic effects of growth hormone, a hormonal interplay with multiple fates.

The liver responds to estrogens and growth hormone (GH) which are critical regulators of body growth, gender-related hepatic functions, and intermediate metabolism. The effects of estrogens on liver can be direct, through the direct actions of hepatic ER, or indirect, which include the crosstalk with endocrine, metabolic, and sex-differentiated functions of GH. Most previous studies have been focused on the influence of estrogens on pituitary GH secretion, which has a great impact on hepatic transcriptional regulation. However, there is strong evidence that estrogens can influence the GH-regulated endocrine and metabolic functions in the human liver by acting at the level of GHR-STAT5 signaling pathway. This crosstalk is relevant because the widespread exposition of estrogen or estrogen-related compounds in human. Therefore, GH or estrogen signaling deficiency as well as the influence of estrogens on GH biology can cause a dramatic impact in liver physiology during mammalian development and in adulthood. In this review, we will summarize the current status of the influence of estrogen on GH actions in liver. A better understanding of estrogen-GH interplay in liver will lead to improved therapy of children with growth disorders and of adults with GH deficiency.

The influence of estrogens on the biological and therapeutic actions of growth hormone in the liver.

GH is main regulator of body growth and composition, somatic development, intermediate metabolism and gender-dependent dimorphism in mammals. The liver is a direct target of estrogens because it expresses estrogen receptors which are connected with development, lipid metabolism and insulin sensitivity, hepatic carcinogenesis, protection from drug-induced toxicity and fertility. In addition, estrogens can modulate GH actions in liver by acting centrally, regulating pituitary GH secretion, and, peripherally, by modulating GHR-JAK2-STAT5 signalling pathway. Therefore, the interactions of estrogens with GH actions in liver are biologically and clinically relevant because disruption of GH signaling may cause alterations of its endocrine, metabolic, and gender differentiated functions and it could be linked to dramatic impact in liver physiology during development as well as in adulthood. Finally, the interplay of estrogens with GH is relevant because physiological roles these hormones have in human, and the widespread exposition of estrogen or estrogen-related compounds in human. This review highlights the importance of these hormones in liver physiology as well as how estrogens modulate GH actions in liver which will help to improve the clinical use of these hormones.

The GGN and CAG repeat polymorphisms in the exon-1 of the androgen receptor gene are, respectively, associated with insulin resistance in men and with dyslipidemia in women.

The human androgen receptor (AR) gene possesses two trinucleotide repeats of CAG and GGN in exon-1. The GGN repeat affects the amount of AR protein translated, while the CAG repeat affects the efficiency of AR transcriptionaly. In this study, we have genotyped these polymorphic tracts in a representative sample of 557 Caucasian adult individuals (314 women and 243 men) from the Canary Islands, Spain (the ENCA Study), and investigated their association with fasting serum levels of lipids, glucose and insulin. The number of CAG repeats in women (expressed as the average length of the two alleles) was inversely correlated with serum levels of LDL-cholesterol (Spearman rho=-0.179; P<0.01). Women with an average number of CAG repeats in the upper tertile showed significantly lower levels of LDL-cholesterol than those grouped in the lower and middle tertile, after adjusting for age, body mass index, waist-to-hip ratio, smoking and alcohol drinking. The number of GGN repeats in men was correlated with fasting insulin levels (Spearman rho=-0.206; P<0.01), the homeostasis model assessment of insulin resistance (HOMA-IR; Spearman rho=-0.230; P<0.01) and the McAuley index of insulin sensitivity (Spearman rho=0.194; P<0.01). Men with a number of GGN repeats in the upper tertile showed lower levels of insulin and HOMA and a higher level of the McAuley index than those grouped in the lower and middle tertile, after adjusting for the variables listed above. These results support the hypothesis that the longer alleles of the CAG and GGN polymorphisms in the exon-1 of the AR gene, indicative of lower androgenic signaling, respectively protect women from developing dyslipemia and men from developing insulin resistance.

Short alleles of both GGN and CAG repeats at the exon-1 of the androgen receptor gene are associated to increased PSA staining and a higher Gleason score in human prostatic cancer.

The exon 1 of the human androgen receptor (AR) gene contains two length polymorphisms of CAG (polyglutamine) and GGN (polyglycine). "In vitro" experiments suggest that the larger GGN repeats provide a lower AR-protein yield, whereas the larger CAG repeats decrease the AR transcriptional activity, both decreasing the AR signalling intensity. Here we have tested such possibilities in human prostatic cancer (CaP) specimens. We used 72 archival samples of radical prostatectomy. Parallel slides were used for AR protein or PSA immunohistochemistry, and for genotyping studies. Polymorphisms were genotyped by PCR, fragment length analysis and sequencing selected samples. The AR staining was positively correlated with the Gleason score (r=0.320; P=0.005), but it was not correlated to CAG or GGN repeat length or PSA staining. The number of GGN repeats was negatively correlated to the intensity of PSA staining (r=-0.243; P=0.04). Combination of short alleles of both tracts was significantly higher in: the heavier stained tertiles for PSA (P=0.03) and AR (P=0.06); and in the subgroup of samples having a Gleason score of 7 or higher (P=0.021). The results support the hypothesis that the shorter alleles of CAG and GGN repeats in the AR gene are associated to an increased AR signalling intensity in human prostate cancer, and with more aggressive forms of the disease.

Increased risk of breast cancer in women bearing a combination of large CAG and GGN repeats in the exon 1 of the androgen receptor gene.

The exon 1 of the human androgen receptor gene (AR) contains both CAG (polyglutamine) and GGN (polyglycine) repeat length polymorphisms. Large CAG repeats have been related to an increased risk of breast cancer (BC), whereas the influence of the GGN repeats is still unclear. Here, we have studied how the length of CAG and GGN repeats is associated with the risk of BC in a population from Tenerife (Canary Islands, Spain). The study was carried out on 257 woman diagnosed with BC and 393 controls, nesting in the 'CDC of the Canary Islands' cohort study. The AR CAG and GGN genotyping was performed by means of PCR amplification with specific fluorescently labelled primers followed by a capillary electrophoresis. The allelic distribution of CAG and GGN polymorphisms was similar in cases and controls. The mean of short and long CAG and GGN alleles did not show differences between cases and controls and the same was true when the average length of both CAG alleles (CAG(n)) and GGN alleles (GGN(n)) was considered. However, when CAG(n) and GGN(n) were categorised using 22 and 24 repeats as the cut-off point, respectively, significant differences between cases and controls were observed. The CAG(n)>22 repeats were more frequent in cases than in controls, being associated with an increased risk of BC (OR=1.49; CI(95%)=1.06-2.09; p=0.021). No significant differences were found for categorised GGN(n). For CAG(n)/GGN(n) combinations, the highest BC risk was found to be associated with the CAG(n)>22/GGN(n)24 combination (OR=2.47; CI(95%)=1.37-4.46; p=0.003). In conclusion, our results indicate that longer CAG(n)/GGN(n) combinations increase the risk of BC and suggest that CAG and GGN AR polymorphisms should be considered in order to assess the BC risk.

Androgens and androgen receptors in breast cancer.

Aromatase (CYP19) converts adrenal and ovarian androgens into estrogens, which supports the growth of estrogen-dependent breast cancers. Anti-aromatase agents are displacing antiestrogens as the first-line treatment for estrogen receptor positive breast cancers. Androgens can act as estrogen precursors, but besides this capability they can also directly act on breast cancer cells by binding to androgen receptors, which are present in the majority of breast cancer specimens. Epidemiological and clinical evidences suggest that higher levels of circulating androgen increase the risk of developing breast cancer. Androgen receptor gene polymorphisms which render the more transcriptionally active receptors have been related to a lower risk of breast cancer. It is currently accepted that androgens act as antiproliferative agents in the presence of estrogens in some breast cancer cell lines. However, emerging evidence suggests that direct androgenic activity might also stimulate cell growth in a subset of estrogen-resistant breast tumors. Here we discuss the supporting evidence which proposes that androgens themselves are actively involved in breast carcinogenesis and its clinical behaviour.

The relationship between microsatellite instability and PTEN gene mutations in endometrial cancer.

Microsatellite instability (MSI) and mutations in the PTEN gene are among the molecular alterations involved in endometrial carcinogenesis. There is conflicting information regarding to their role in this type of tumor. For this reason, we have studied both molecular lesions in a large population-based series of 205 patients with sporadic endometrial cancer. MSI was found in 41 (20.0%) of the tumors and PTEN mutations were found in 74 (36.1%). There were differences in genotype between tumors with and without MSI. Tumors with MSI showed both a higher frequency of PTEN mutations (58.5% vs. 30.4%) (p=0.002, Fisher's exact test) and a higher number of insertions or deletions (I/D) of one nucleotide within the mononucleotide tracts of the PTEN gene (45.8% vs. 11.4% out of all I/D, p=0.005). Conversely, G:C to A:T transitions in CpG dinucleotides were found mostly in microsatellite stable tumors (57.7% vs. 18.2% out of all single-base substitutions, p=0.037). Overall, 67.6% of tumors with mutated PTEN exhibited multiple mutations or allelic imbalance (AI). Multiple PTEN mutations in the same tumor were more frequent in tumors with MSI (60% vs. 25.7%); by contrast the presence of AI accompanying PTEN mutation was higher in microsatellite stable tumors (74.3% vs. 40%) (p=0.028). In addition, patients with both genetic alterations were diagnosed at more advanced stage of progression (54.2% for MSI vs. 20.0% for MSS, p=0.006), and exhibited a worse prognosis (hazard ratio [95% confidence interval]: 3.0 [1.1-13.1], p=0.034, log-rank test) than patients with only the PTEN gene mutated. Our data suggest that the DNA mismatch repair system status influences: (i) both the frequency and the mutational spectrum of PTEN; (ii) the nature of one of the hits that inactivate this tumor-suppressor gene; and (iii) the clinical condition and behavior of the patients.

Alleles with short CAG and GGN repeats in the androgen receptor gene are associated with benign endometrial cancer.

The human androgen receptor (AR) gene possesses 2 trinucleotide repeats of CAG and GGN in exon 1. The CAG repeat corresponds to a polyglutamine tract in the N-terminal region of the receptor, that affects its transcriptional efficiency. The GGN repeat codifies for a polyglycine tract, and affects the amount of the AR protein transcribed. The endometrium contains ARs and the androgens have antiproliferative properties in cultured endometrial cancer (EC) cells. Larger CAG repeats of the AR gene give rise to a weaker transcriptional activity and have been found to be associated with endometrial carcinogenesis. The possible involvement of CAG and GGN tracts in the progression of EC is unknown. To study that possibility, we have genotyped both CAG and GGN polymorphisms of the AR gene in tumor tissue genomic DNA from a series of 204 consecutive patients with EC, and analyzed the results with regard to the pathological features and clinical outcome of patients. We classified the alleles as S (short median). The genotype with both S-CAG repeat alleles (SS-CAG) was more common in patients diagnosed at an early stage (41.6% SS-CAG vs 22.6% SL- and LL-CAG together, p = 0.048) and in tumors that did not invade the vascular space (43.0% SS-CAG vs 26.4% SL- and LL-CAG together, p = 0.034). The genotype with SS-GGN alleles was more common in well-differentiated tumors (41.2% SS-GGN vs 25.2% LS- and LL-GGN together, p = 0.017) and in endometrioid histological subtype tumors (35.3% SS-GGN vs 13.0% SL- and LL-GGN together, p = 0.034). When the genotypes of both repeats coexisting in each tumor specimen were taken into consideration, the relationship between the SS-CAG genotype and early stage remained only in the presence of the SS-GGN genotype (43.9% vs 0%, p = 0.01). No other associations were observed. In univariate survival analysis, patients with short alleles of both repeats (SS-CAG and SS-GGN genotypes simultaneously) had a lower risk of cancer-specific death (p = 0.032, mean follow-up: 63 months). Our data suggests that short CAG or GGN repeats of the AR gene are associated with a more benign condition of traditional prognostic variables in EC.

Prognostic value of the quantitative measurement of the oncoprotein p185(Her-2/neu) in a group of patients with breast cancer and positive node involvement.

Our study attempts to determine the prognostic value of the quantitative measurement of the oncoprotein p185(Her-2/neu) in a group of patients with breast cancer and positive node involvement. In a series of 217 patients with breast cancer and positive nodes in whom the oncoprotein p185 was quantitatively determined by ELISA, we analyzed the clinico-pathological variables including age, menopausal status, tumor size, number of affected nodes, type and histology grade and the molecular variables such as the oestrogen and progesterone receptors (ER and PR, respectively), pS2 and Cathepsin D (CD). Using 260 fmol/mg protein as a cut-off point, 18% of the tumors presented as overexpressing p185. The p185 showed no relationship with any of the clinico-pathological variables studied except that its concentration was elevated in ductal and lobular histology types and in the moderate and poorly differentiated histology grades. With a median follow-up of 50 months (range 1-90), the univariate analysis of disease-free survival (DFS) and overall survival (OS) showed that the histology grade, tumor size, the number of infiltrated nodes, the p185 and the ER were the variables associated with the clinical course of the disease in the patients. In the multivariate analysis, however, only the tumor size, number of affected ganglia, the p185 and the ER remained associated with the clinical progression of the disease. The patients with p185 overexpression had a risk, not only of relapse but also death from the disease, of more than twice that of the patients who had normal p185 concentrations. When the p185 was divided into 3 categories based on +/-1 x SD above or below the mean, the patients with high and low p185 showed, in the univariate analysis, a similar relationship with DFS but not with OS. In the multivariate analysis, both with the DFS as with the OS, only a high p185 concentration retained its association with the clinical course of the disease in the patients. Our results suggest that by quantitatively determining (using ELISA) the p185 oncoprotein, groups of cancer patients of high risk could be better identified for more effective clinical management.