Treatment of acromegaly by rosiglitazone via upregulating 15-PGDH in both pituitary adenoma and liver.

Rosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) ligand, has been reported to reduce growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in 10 patients with acromegaly. However, the mechanisms remain unknown. Here, we reveal that PPARγ directly enhances 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, whose expression is decreased and negatively correlates with tumor size in acromegaly. Rosiglitazone decreases GH production and promotes apoptosis and autophagy in GH3 and primary somatotroph adenoma cells and suppresses hepatic GH receptor (GHR) expression and IGF-1 secretion in HepG2 cells. Activating the PGE2/cAMP/PKA pathway directly increases GHR expression. Rosiglitazone suppresses tumor growth and decreases GH and IGF-1 levels in mice inoculated subcutaneously with GH3 cells. The above effects are all dependent on 15-PGDH expression. Rosiglitazone as monotherapy effectively decreases GH and IGF-1 levels in all nineteen patients with active acromegaly. Evidence suggests that rosiglitazone may be an alternative pharmacological approach for acromegaly by targeting both pituitary adenomas and liver.

Erectile Dysfunction Is Associated With Excessive Growth Hormone Levels in Male Patients With Acromegaly.

Objective: To determine the risk factors for erectile dysfunction (ED) in male patients with acromegaly and to prospectively investigate the short-term changes of erectile function after surgery or medical treatment. Methods: Sixty-three male patients were subjected to nocturnal penile tumescence and rigidity (NPTR) test for the evaluation of erectile function. The measurement of serum nitric oxide (NO) was also performed. Twenty-seven patients were re-evaluated by NPTR after surgery or long-term somatostatin analogues (SSA) treatment. Results: Twenty-two patients (34.9%) had ED. Patients with ED showed higher random GH (17.89 [10.97-44.19] µg/L vs 11.63 [4.31-28.80] µg/L, p = 0.020) and GH nadir (GHn) (10.80 [6.69-38.30] µg/L vs 8.76 [3.62-18.19] µg/L, p = 0.044) during oral glucose tolerance test (OGTT). The NO levels of ED patients were lower than non-ED patients (9.15 [5.58-22.48] µmol/L vs 16.50 [12.33-31.78] µmol/L, p = 0.012). After treatment, patients who present improvement in erectile function showed lower post-GHn (0.07 [0.03-0.12] ng/ml vs 1.32 [0.09-3.60] ng/ml, p = 0.048) and post-IGF-1 index (1.03 ± 0.38 vs 1.66 ± 0.95, p = 0.049). The multivariate analysis indicated post-GHn was still associated with the improvement of erectile function after correction of other covariates (OR: 0.059, 95% CI: 0.003-1.043, p = 0.053). Conclusions: Excessive GH is related to ED in male patients with acromegaly. GH normalization after treatment is beneficial for short-term erectile function recovery.

Gene expression differences in quiescent versus regenerating hair cells of avian sensory epithelia: implications for human hearing and balance disorders.

The sensory receptors for hearing and balance are the hair cells of the cochlea and vestibular organs of the inner ear. Permanent hearing and balance deficits can be triggered by genetic susceptibilities or environmental factors such as infection. Unlike mammalian hair cells that have a limited capacity for regeneration, the vestibular organ of the avian ear is constantly undergoing hair cell regeneration, whereas the avian cochlea undergoes regeneration only when hair cells are damaged. In order to gain insights into the genetic programs that govern the regenerative capacity of hair cells, we interrogated custom human cDNA microarrays with sensory epithelial cell targets from avian inner ears. The arrays contained probes from conserved regions of approximately 400 genes expressed primarily in the inner ear and approximately 1500 transcription factors (TF). Highly significant differences were observed for 20 inner-ear genes and more than 80 TFs. Genes up-regulated in the cochlea included BMP4, GATA3, GSN, FOXF1 and PRDM7. Genes up-regulated in the utricle included SMAD2, KIT, beta-AMYLOID, LOC51637, HMG20B and CRIP2. Many of the highly significant changes were validated by Q-PCR and in situ methods. Some of the observed changes implicated a number of known biochemical pathways including the c-kit pathway previously observed in melanogenesis. Twenty differentially expressed TFs map to chromosomal regions harboring uncloned human deafness loci, and represent novel candidates for hearing loss. The approach described here also illustrates the power of utilizing conserved human cDNA probes for cross-species comparisons.