Management of aggressive growth hormone secreting pituitary adenomas.

Aggressive GH-secreting pituitary adenomas (GHPAs) represent an important clinical problem in patients with acromegaly. Surgical therapy, although often the mainstay of treatment for GHPAs, is less effective in aggressive GHPAs due to their invasive and destructive growth patterns, and their proclivity for infrasellar invasion. Medical therapies for GHPAs, including somatostatin analogues and GH receptor antagonists, are becoming increasingly important adjuncts to surgical intervention. Stereotactic radiosurgery serves as an important fallback therapy for tumors that cannot be cured with surgery and medications. Data suggests that patients with aggressive and refractory GHPAs are best treated at dedicated tertiary pituitary centers with multidisciplinary teams of neuroendocrinologists, neurosurgeons, radiation oncologists and other specialists who routinely provide advanced care to GHPA patients. Future research will help clarify the defining features of "aggressive" and "atypical" PAs, likely based on tumor behavior, preoperative imaging characteristics, histopathological characteristics, and molecular markers.

Lipids and Diabetic Retinopathy.

The relationship between lipids and the development and/or severity of diabetic retinopathy (DR) is complex. Large epidemiologic studies suggest an inconsistent and overall modest association between serum triglycerides or major cholesterol species and the severity of DR; however, certain specific lipoprotein species may have stronger associations with DR severity, suggesting a pathophysiological role for lipoproteins analogous to that seen in atherosclerosis. In this lipoprotein-mediated DR pathogenesis model, damage to the blood-retinal barrier allows extravasation of lipoprotein species, which are modified in the intraretinal environment, creating substantial local damage. Additionally, hypolipidemic therapy with statins and fibrates--particularly the latter--have been shown to modulate DR in large-scale studies. Since serum lipid profile changes do not necessarily correlate with DR modulation, the efficacy of these agents may be due to their tissue-specific changes in lipoproteins and/or their anti-inflammatory, antioxidative, antiangiogenic, and antiapoptotic functions.

Cyclic Cushing's disease with misleading inferior petrosal sinus sampling results during a trough phase.

Diagnosing Cushing's syndrome is challenging and is further hampered when investigations are performed in a patient with cyclic Cushing's syndrome. A subset of patients with Cushing's syndrome exhibit periods of abnormal cortisol secretion with interspersed normal secretion. Patients can have periods of clinical improvement during these quiescent phases or remain symptomatic. Initial diagnostic testing can be challenging because of the unpredictable durations of the peak and trough phases, and it is especially challenging when the diagnosis of cyclic Cushing's syndrome has not yet been determined. Here, the authors present the case of a patient with Cushing's disease with a pathology-proven adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma and whose initial inferior petrosal sinus sampling (IPSS) results were deemed indeterminate; further studies elucidated the diagnosis of cyclic Cushing's syndrome. Repeat IPSS was diagnostic of a central source for ACTH secretion, and the patient was treated successfully with transsphenoidal resection. Literature concerning the diagnosis and management of cyclic Cushing's syndrome is also reviewed.

Basal insulin peglispro demonstrates preferential hepatic versus peripheral action relative to insulin glargine in healthy subjects.

OBJECTIVE: We evaluated the endogenous glucose production (EGP) and glucose disposal rate (GDR) over a range of doses of basal insulin peglispro (BIL) and insulin glargine in healthy subjects. RESEARCH DESIGN AND METHODS: This was a single-center, randomized, open-label, four-period, incomplete-block, crossover study conducted in eight healthy male subjects. Subjects had 8-h euglycemic clamps performed with primed, continuous infusions of BIL (5.1 to 74.1 mU/min) in three dosing periods and insulin glargine (20 or 30 mU/m(2)/min) in a fourth period, targeted to achieve 50-100% suppression of EGP. D-[3-(3)H] glucose was infused to assess rates of glucose appearance and disappearance. RESULTS: Mean BIL and insulin glargine concentrations (targeted to reflect the differences in intrinsic affinities of the two basal insulins) ranged from 824 to 11,400 and 212 to 290 pmol/L, respectively, and increased accordingly with increases in dose. Suppression of EGP and stimulation of GDR were observed with increasing concentrations of both insulins. At insulin concentrations where EGP was significantly suppressed, insulin glargine resulted in increased GDR. In contrast, at comparable suppression of EGP, BIL had minimal effect on GDR at lower doses and had substantially less effect on GDR than insulin glargine at higher doses. CONCLUSIONS: The novel basal insulin analog BIL has relative hepatopreferential action and decreased peripheral action, compared with insulin glargine, in healthy subjects.

The Akt pathway in human breast cancer: a tissue-array-based analysis.

The Akt pathway, an important regulator of cell proliferation and survival, is deregulated in many cancers. The pathway has achieved considerable importance due to the development of kinase inhibitors that are able to successfully reduce tumor growth. This study was conducted to determine the status of the Akt pathway in human breast cancers and to study the relationship between the different component proteins. Expression levels of PTEN, phosphorylated forms of the constituent proteins (Akt, FKHR, mTOR, and S6) and cyclin D1 were evaluated by immunohistochemistry, on consecutive sections from a tissue microarray containing 145 invasive breast cancers and 140 pure ductal carcinomas in-situ. Aberrant expression was correlated statistically with tumor characteristics and disease outcome. The Akt pathway was found to be activated early in breast cancer, in the in-situ stage. In all, 33, 15, 32, and 60% of ductal carcinoma in-situ showed overexpression of Akt, FKHR, mTOR, and cyclin D1. PTEN loss did not correlate statistically with expression of AKT or any of the other proteins with the exception of S6, indicating that Akt activation was not a result of PTEN loss. Expression levels of PTEN and S6 were significantly different in in-situ and invasive cancers, indicating association with disease progression. Loss of PTEN was noted in 11% of in-situ as compared to 26% of invasive cancers, while S6 overexpression was seen in 47% in-situ and in 72% invasive cancers. High-grade carcinomas were associated with PTEN loss, while low-grade carcinomas with good prognostic features showed cyclin D1 overexpression and were associated with longer disease free survival. Additionally, cancers with mTOR overexpression showed a three times greater risk for disease recurrence. Overall, a large proportion of in-situ and invasive breast cancers overexpressed cyclinD1 and S6. Our results may have significant implications in the development and application of targeted therapy.

Down-regulation and growth inhibitory role of C/EBPalpha in breast cancer.

PURPOSE: CCAAT/enhancer binding proteins (C/EBP) are a family of transcription factors that regulate proliferation and differentiation in a variety of tissues. The purpose of this study was to explore the possibility that C/EBPalpha is involved in breast cancer. EXPERIMENTAL DESIGN: We quantified C/EBPalpha mRNA expression levels in 24 primary breast tumors, 16 normal breast samples, and 8 breast cancer cell lines using quantitative real-time reverse transcription-PCR assay. C/EBPalpha protein levels were further determined by immunohistochemical analysis. To examine the consequence of C/EPBalpha expression in breast cancer, we stably transfected an inducible C/EPBalpha expression vector into three breast cancer cell lines. RESULTS: Low expression of C/EBPalpha mRNA was found in 83% of primary breast cancer samples. Immunohistochemical study further showed either a markedly reduced or undetectable expression of C/EBPalpha protein in 30% of breast cancer specimens. The other 70% of breast cancers had C/EBPalpha expression in both the cytoplasm and nucleus; in control, C/EBPalpha was localized to the nucleus in the normal ductal cells. C/EBPalpha expression was associated with estrogen- and progesterone receptor-negative status. Induction of C/EBPalpha expression in these cell lines resulted in growth inhibition accompanied by G0-G1 cell cycle arrest and reduced anchorage-independent cell growth. C/EBPalpha expression was associated with down-regulation of c-myc and up-regulation of p21, PPARgamma, and the breast epithelial differentiation marker, maspin. CONCLUSIONS: These results suggest that reduced expression of C/EBPalpha may play a role in the development and/or progression of breast cancer.

PTEN promoter is methylated in a proportion of invasive breast cancers.

The PTEN protein is a negative regulator of the Akt pathway, leading to suppression of apoptosis and increased cell survival. Its role as a tumor-suppressor gene has been adequately substantiated, and homozygous mutations have been demonstrated in familial and sporadic cancers. In breast cancers, expression of PTEN protein is lost/reduced in 38% of cases. Somatic mutations are, however, rarely found. Our study was therefore designed to determine if differential methylation of the PTEN promoter region has a role in the transcriptional inactivation of the gene in invasive breast carcinomas. A total of 44 samples of invasive human breast cancer, 5 breast cancer cell lines and 16 samples of normal human breast tissue from young and elderly women were studied for methylation of the PTEN promoter by methylation-specific PCR and PTEN protein expression by immunohistochemistry. PTEN methylation occurred in 34% of breast cancers, and 60% of these samples were associated with loss of PTEN protein. Analyzed from a different perspective, 34% of breast cancers had reduced expression of PTEN and 60% had a methylated PTEN promoter. None of the breast cancer cell lines and normal breast tissues showed methylation. In summary, methylation of the PTEN promoter leads to PTEN inactivation in a subset of human breast cancers.