Background: Recently we have reported membrane androgen receptors-induced apoptotic regression of prostate cancer cells regulated by Rho/ROCK/actin signaling. In the present study we explored the specificity of these receptors and we analyzed downstream effectors controlling survival and apoptosis in hormone refractory DU145-prostate cancer cells stimulated with membrane androgen receptor-selective agonists.

The serum‐ and glucocorticoid‐dependent kinases 1–3 (SGK1–3) are downstream effectors of phosphatidylinositol 3‐kinases, implicated in various cell responses including colon cancer tumorigenesis in mice. Here, we investigated the role of SGK1 in the regulation of cell motility. Using Caco‐2 colon tumor and HEK293 embryonic kidney cells, we report that transfection with the constitutively active SGK1 mutant (SGK1‐SD) significantly enhanced cell motility. The cell‐adhesion protein vinculin was effectively dephosphorylated in SGK1‐SD‐transfected cells. Treatment of the cells with phosphatase inhibitors restored vinculin phosphorylation and inhibited cell migration, indicating a significant role for vinculin phosphorylation in SGK1‐induced motility. SGK1‐SD‐enhanced cell motility was inhibited by activation of membrane androgen‐binding sites (mAR) via testosterone‐conjugates in both cell lines, whereas intracellular androgen receptor (iAR)‐silencing and flutamide treatment revealed that these effects were clearly independent of the interaction of SGK1 with the classical androgen receptors (iAR). More importantly, mAR activation restored vinculin phosphorylation in SGK1‐SD‐transfected cells, whereas silencing of vinculin fully reversed the mAR‐induced inhibition of the migratory capacity, implying that this protein is directly involved in cell motility regulation by SGK1 and mAR. This study indicates for the first time that SGK1 regulates cell migration via vinculin dephosphorylation, a mechanism that is controlled by mAR function.

Tumor growth is fostered by inhibition of cell death, which involves the receptiveness of tumor to growth factors and hormones. We have recently shown that testosterone exerts proapoptotic effects in prostate and colon cancer cells through a membrane-initiated mechanism. In addition, we have recently reported that dehydroepiandrosterone (DHEA) can control cell fate, activating nerve growth factor (NGF) receptors, namely tropomyosin-related kinase (Trk)A and p75 neurotrophin receptor, in primary neurons and in PC12 tumoral cells. NGF was recently involved in cancer cell proliferation and apoptosis. In the present study, we explored the cross talk between androgens (testosterone and DHEA) and NGF in regulating apoptosis of prostate and colon cancer cells. DHEA and NGF strongly blunted serum deprivation-induced apoptosis, whereas testosterone induced apoptosis of both cancer cell lines. The antiapoptotic effect of both DHEA and NGF was completely reversed by testosterone. In line with this, DHEA or NGF up-regulated, whereas testosterone down-regulated, the expression of TrkA receptor. The effects of androgens were abolished in both cell lines in the presence of TrkA inhibitor. DHEA induced the phosphorylation of TrkA and the interaction of p75 neurotrophin receptor with its effectors, Rho protein GDP dissociation inhibitor and receptor interacting serine/threonine-protein kinase 2. Conversely, testosterone was unable to activate both receptors. Testosterone acted as a DHEA and NGF antagonist, by blocking the activation of both receptors by DHEA or NGF. Our findings suggest that androgens may influence hormone-sensitive tumor cells via their cross talk with NGF receptors. The interplay between steroid hormone and neurotrophins signaling in hormone-dependent tumors offers new insights in the pathophysiology of these neoplasias.

The Mediterranean Sea is subject to pressures from biological invasion due to coastal anthropic activities and global warming, which potentially modify its biogeography. The Red Sea tropical seagrass Halophila stipulacea entered the Eastern Mediterranean over a century ago, and its occurrence is expanding towards the northwest. Here, we highlight the importance of genomics for deciphering the evolutionary and ecological procedures taking place during the invasion process of H. stipulacea and review the relatively sparse genetic information available for the species to date. We report the first draft whole-genome sequencing of a H. stipulacea individual from Greece, based on Illumina Sequencing technology. A comparison of the Internal Transcribed Spacer (ITS) regions revealed a high divergence of the herein sequenced individual compared to Mediterranean populations sequenced two decades ago, rendering further questions on the evolutionary processes taking place during H. stipulacea adaptation in the invaded Mediterranean Sea. Our work sets the baseline for a future analysis of the invasion genomic of the focal species.

The non-indigenous to the Mediterranean tropical seagrass Halophila stipulacea has the possibility to become more prevalent in the Mediterranean basin, exacerbated by the rapid increase of water temperature. Molecular profiling appears a promising tool to study the traits that render H. stipulacea tolerant and resilient and facilitate its rapid and vast geographical spread. Taking advantage from recent seagrass genomes sequencing, proteomics specialty has been applied to several seagrasses giving new insight on the biology and physiology of this group of angiosperms. Thus, it could be of interest to apply proteomics to H. stipulacea that it could be considered as a possible plant model species to study marine biological invasion. The first step to achieve this goal is to obtain high quality proteins from plant tissue. Tissue fixation and protein extraction protocol are the most challenging steps in proteomics . Here we report a fine-tuned procedure obtained by comparing protein yield from H. stipulacea plants frozen in liquid nitrogen or preserved in RNAlater and processed following two different extraction protocols. Higher protein yield have been extracted from the procedure that use the RNAlater preserved plants, extracted with trichloroacetic acid in water followed by trichloroacetic acid in acetone, compared to those obtained from all other procedures. Protein purity of these samples have been tested by the separation in SDS-PAGE comfirming a better resolved profile of peptide bands suitable for a gel-based proteomics. Then, to assess the quality of proteins the mHPLC-ESI-MS/MS mass spectrometry analyses and bioinformatics have been performed.Hundreds proteins have been identified against several seagrass genomic resources available at UniProt, NCBI, SeagrassDB and transcriptomic datasets, which were merged to form the first customized dataset useful for H. stipulacea proteomic investigations.