Band 7, Heft 1 - Issue 1 – July

Cellular senescence leads to an irreversible block of cellular division capacity both in cell culture and in vivo. The induction of an irreversible cell cycle arrest is very useful for treatment of cancer. Histone deacetylases (HDACs) are considered as therapeutic targets to treat cancer patients. HDAC inhibitors repress cancer growth and are used in various clinical trials. Here, we analyzed whether sodium butyrate (NaBu), an inhibitor of class I and II HDACs, induces cellular senescence in neuroblastoma and prostate cancer (PCa) including an androgen-dependent as well as an androgen-independent human PCa cell line. We found that the HDAC inhibitors NaBu and valproic acid (VPA) induce cellular senescence in tumor cells. Interestingly, also an inhibitor of SIRT1, a class HDAC III, induces cellular senescence. Both neuroblastoma and human prostate cancer cell lines express senescence markers, such as the Senescence Associated-β-galactosidase (SA-β-Gal) and Senescence Associated Heterochromatin Foci (SAHF). Furthermore, NaBu down-regulates the proto-oncogenes c-Myc, Cyclin D1 and E2F1 mRNA levels. The mRNA level of the cell cycle inhibitor p16 remains unchanged whereas that of the tumor suppressor p21 is strongly up-regulated. Interestingly, NaBu treatment robustly increases reactive oxygen species (ROS) levels. These results indicate an epigenetic regulation and an association of HDAC inhibition and ROS production with cellular senescence. The data underline that tumor cells can be driven towards cellular senescence by HDAC inhibitors, which may further arise as a potent possibility for tumor suppression.

The potential role of the androgen receptor (AR) as a predictive or prognostic factor in breast cancer remains unclear. We aimed to determine the prognostic significance of AR in a cohort of breast carcinomas with long-term follow-up and to critically appraise this in the context of existing literature. Four hundred and eight cases of invasive breast cancer were incorporated into tissue microarrays (TMAs). All received tamoxifen and comprised 108 cases which relapsed and 300 cases which did not. Mean follow-up time for the former was 84 months (range 1–142, SD 38.8) and for the latter was 77 months (range 11–229, SD 49.7). TMAs were immunohistochemically stained with AR and scored as a continuous variable and using the Allred score. AR expression was significantly associated with grade, recurrence on tamoxifen, non-breast cancer death estrogen receptor alpha (ERα) and progesterone receptor (PR). AR correlated significantly with better overall survival (OS) and disease-free survival (DFS) using an Allred cut-off of 4 (log rank=0.0053 and 0.0044, respectively), and 20% positive tumor cells (log rank=0.0027 and 0.0059, respectively). AR expression was additionally associated with a reduced risk of recurrence following endocrine therapy. In summary, AR positive breast tumors have better OS and DFS and are less likely to recur following endocrine treatment.

Background: Lower serum vitamin D (25(OH)D) among individuals with African ancestry is primarily attributed to skin pigmentation. However, the influence of genetic polymorphisms controlling for skin melanin content has not been investigated. Therefore, we investigated differences in non-summer serum vitamin D metabolites according to self-reported race, genetic ancestry, skin reflectance and key pigmentation genes ( SLC45A2 and SLC24A5) . Materials and methods: Healthy individuals reporting at least half African American or half European American heritage were frequency matched to one another on age (±2 years) and sex. One hundred and seventy-six autosomal ancestry informative markers were used to estimate genetic ancestry. Melanin index was measured by reflectance spectrometry. Serum vitamin D metabolites [25(OH)D 3 , 25(OH)D 2 and 24,25(OH) 2 D 3 ] were determined by high performance liquid chromatography (HPLC) tandem mass spectrometry. Percent 24,25(OH) 2 D 3 was calculated as a percent of the parent metabolite [25(OH)D 3 ]. Stepwise and backward selection regression models were used to identify leading covariates. Results: Fifty African Americans and 50 European Americans participated in the study. Compared with SLC24A5 111 Thr homozygotes, individuals with the SLC24A5 111 Thr/Ala and 111 Ala/Ala genotypes had, respectively, lower levels of 25(OH)D 3 (23.0 and 23.8 nmol/L lower, p-dominant=0.007), and percent 24,25(OH) 2 D 3 (4.1% and 5.2% lower, p-dominant=0.003), controlling for tanning bed use, vitamin D/fish oil supplement intake, race/ethnicity and genetic ancestry. Results were similar with melanin index adjustment, and were not confounded by glucocorticoid, oral contraceptive, or statin use. Conclusions: The SLC24A5 111 Ala allele was associated with lower serum vitamin 25(OH)D 3 and lower percent 24,25(OH) 2 D 3 , independently from melanin index and West African genetic ancestry.

In order to develop an immunoassay of 7β-hydroxy-epiandrosterone, a stereoselective synthesis of a specific hapten, 7β-hydroxy-19-oxo-androstan 19-(O-carboxymethyl)oxime ( 17 ), was performed. This synthesis was achieved in 16% overall yield starting from the well-known 3β-acetoxy-19-hydroxy-5-androsten-17-one ( 1 ). After coupling of the alkyl oxime moiety, an allylic oxidation of the C-7 carbon under mild conditions followed by two selective reductions established all the functionalities of the final compound 17 .

The hormones 17β-estradiol (17βE2), 21α-hydroxyprogesterone (21α-HOPRG) and corticosterone (CORT) were used as representative models for the study. As a source for hormone excitation in singlet state serviced monochromatic UV-light (λ=254 nm), it was stated that the transients resulting by e – aq emission in air-free mixture water/ethanol 40/60, as long as they are in “status nascendi”, can be regenerated by electron transfer from a potent electron donor, e.g., vitamin C. The hormone regeneration (%) strongly depends, after all, on specific hormone molecular structure, concentration, temperature, etc. Because of the large heterogenic molecular structures, the substrates dissolved in the solvent mixture form “associates” (unstable complexes) in concentrations >10 9 mol/L hormone. The hormones eject, but they also consume e – aq with a rather high reaction rate constant (k≈10 9 up to 2×10 10 L/mol.s), therefore, they act as “electron mediators”. It was also observed that the hormones by dissolution in aerated solvent mixture are sensitive towards oxygen. For an explanation of the results, probable reaction mechanisms are presented. The described method offers a new pathway and possibilities for application in medicine.