Molecular mechanisms underlying mifepristone's agonistic action on ovarian cancer progression

Background: Recent clinical trials on ovarian cancer with mifepristone (MF) have failed, despite in vitro findings on its strong progesterone (P4) antagonist function.Methods: Ovarian cancer human and murine cell lines, cultured high-grade human primary epithelial ovarian cancer (HG-hOEC) cells and their explants; as well as in vivo transgenic mice possessing ovarian cancer were used to assess themolecular mechanism underlying mifepristone (MF) agonistic actions in ovarian cancer progression.Findings: Here in, we show that ovarian cancer cells express traceable/no nuclear P4 receptor (PGR), but abundantly P4 receptor membrane component 1 (PGRMC1). MF significantly stimulated ovarian cancer cell migration, proliferation and growth in vivo, and the translocation of PGRMC1 into the nucleus of cancer cells; the effects inhibited by PGRMC1 inhibitor. The beneficial antitumor effect of high-doses MF could not be achieved in human cancer tissue, and the low tissue concentrations achieved with the therapeutic doses only promoted the growth of ovarian cancers.Interpretation: Our results indicate that treatment of ovarian cancer with MF and P4 may induce similar adverse agonistic effects in the absence of classical nuclear PGRs in ovarian cancer. The blockage of PGRMC1 activity may provide a novel treatment strategy for ovarian cancer.</div

Weekly AUC2 carboplatin is inactive in acquired platinum resistant ovarian cancer with or without phenoxodiol, a sensitiser of platinum cytotoxicity: the phase III OVATURE multicenter randomized study

Background Platinum-resistant ovarian cancer (PROC) constitutes a therapeutic dilemma with limited efficacy from traditional cytotoxic agents. Based on prior data suggesting that scheduling alterations of platinum would increase activity, the aim of the present study was to assess the potential therapeutic benefit of phenoxodiol (PXD), a novel biomodulator shown to have chemoresistance reversing potential, when combined with weekly AUC2-carboplatin in PROC patients. Patients and methods A multicenter randomized double-blind placebo controlled phase-III-study was conducted to compare oral PXD plus AUC2-carboplatin (group 1) versus placebo plus AUC2-carboplatin (group 2) weekly in PROC patients. The primary end point was progression-free-survival (PFS). Secondary objectives included overall survival (OS), response rates, duration of response and quality of life. Results The study was terminated early 14 April 2009, after recruitment of 142 patients due to feasibility and recruitment challenges. A total of 142 patients were randomized. The groups were well balanced in terms of important baseline characteristics. The median PFS for group 1 was 15.4 weeks [95% confidence interval (CI) 11.1–21.0] versus 20.1 weeks for group 2 (95% CI = 13.1–33.4); P = 0.3. The objective response rate and median survival in group 1 versus group 2 was 0% versus 1% and 38.3 weeks (95% CI 32.0–45.3) versus 45.7 weeks (95% CI 35.6–58.0), respectively. PXD appeared to be well tolerated. The main reason for dose modification in both groups was hematologic toxicity. Conclusions Orally delivered PXD showed no evidence of clinical activity, when combined with weekly AUC2-carboplatin in PROC. In addition, single-agent weekly AUC2-carboplatin appeared to be inactive by response criteria in a homogenously defined population of PROC. This has implications for the design of future studies

Regulation of flavonoid biosynthesis involves an unexpected complex transcriptional regulation of TT8 expression, in Arabidopsis

TT8/bHLH042 is a key regulator of anthocyanins and proanthocyanidins (PAs) biosynthesis in Arabidopsis thaliana. TT8 transcriptional activity has been studied extensively, and relies on its ability to form, with several R2R3-MYB and TTG1 (WD-Repeat protein), different MYB-bHLH-WDR (MBW) protein complexes. By contrast, little is known on how TT8 expression is itself regulated.Transcriptional regulation of TT8 expression was studied using molecular, genetic and biochemical approaches. Functional dissection of the TT8 promoter revealed its modular structure. Two modules were found to specifically drive TT8 promoter activity in PA- and anthocyanin-accumulating cells, by differentially integrating the signals issued from different regulators, in a spatio-temporal manner. Interestingly, this regulation involves at least six different MBW complexes, and an unpredicted positive feedback regulatory loop between TT8 and TTG2. Moreover, the results suggest that some putative new regulators remain to be discovered. Finally, specific cis-regulatory elements through which TT8 expression is regulated were identified and characterized. Together, these results provide a molecular model consistent with the specific and highly regulated expression of TT8. They shed new light into the transcriptional regulation of flavonoid biosynthesis and provide new clues and tools for further investigation in Arabidopsis and other plant species

TP53 status and taxane-platinum versus platinum-based therapy in ovarian cancer patients: A non-randomized retrospective study

<p>Abstract</p> <p>Background</p> <p>Taxane-platinum therapy (TP) has replaced platinum-based therapy (PC or PAC, DNA damaging chemotherapy) in the postoperative treatment of ovarian cancer patients; however, it is not always effective. TP53 protein plays a differential role in response to DNA-damaging agents and taxanes. We sought to define profiles of patients who benefit the most from TP and also of those who can be treated with PC.</p> <p>Methods</p> <p>We compared the effectiveness of PC/PAC (n = 253) and TP (n = 199) with respect to tumor TP53 accumulation in ovarian cancer patients with FIGO stage IIB-IV disease; this was a non-randomized retrospective study. Immunohistochemical analysis was performed on 452 archival tumors; univariate and multivariate analysis by the Cox's and logistic regression models was performed in all patients and in subgroups with [TP53(+)] and without TP53 accumulation [TP53(-)].</p> <p>Results</p> <p>The advantage of taxane-platinum therapy over platinum-based therapy was seen in the TP53(+), and not in the TP53(-) group. In the TP53(+) group taxane-platinum therapy enhanced the probability of complete remission (p = .018), platinum sensitivity (p = .014), platinum highly sensitive response (p = .038) and longer survival (OS, p = .008). Poor tumor differentiation diminished the advantage from taxane-platinum therapy in the TP53(+) group. In the TP53(-) group PC/PAC was at least equally efficient as taxane-platinum therapy and it enhanced the chance of platinum highly sensitive response (p = .010). However, in the TP53(-) group taxane-platinum therapy possibly diminished the risk of death in patients over 53 yrs (p = .077). Among factors that positively interacted with taxane-platinum therapy in some analyses were endometrioid and clear cell type, FIGO III stage, bulky residual tumor, more advanced age of patient and moderate tumor differentiation.</p> <p>Conclusion</p> <p>Our results suggest that taxane-platinum therapy is particularly justified in patients with TP53(+) tumors or older than 53 years. In the group of patients ≤53 yrs and with TP53(-) tumors platinum-based therapy is possibly equally efficient. We provide hints for planning randomized trials to verify these observations.</p

Cuticular Defects in Oryza sativa ATP-binding Cassette Transporter G31 Mutant Plants Cause Dwarfism, Elevated Defense Responses and Pathogen Resistance.

The cuticle covers the surface of the polysaccharide cell wall of leaf epidermal cells and forms an essential diffusion barrier between plant and environment. Homologs of the ATP-binding cassette (ABC) transporter AtABCG32/HvABCG31 clade are necessary for the formation of a functional cuticle in both monocots and dicots. Here we characterize the osabcg31 knockout mutant and hairpin RNA interference (RNAi)-down-regulated OsABCG31 plant lines having reduced plant growth and a permeable cuticle. The reduced content of cutin in leaves and structural alterations in the cuticle and at the cuticle-cell wall interface in plants compromised in OsABCG31 expression explain the cuticle permeability. Effects of modifications of the cuticle on plant-microbe interactions were evaluated. The cuticular alterations in OsABCG31-compromised plants did not cause deficiencies in germination of the spores or the formation of appressoria of Magnaporthe oryzae on the leaf surface, but a strong reduction of infection structures inside the plant. Genes involved in pathogen resistance were constitutively up-regulated in OsABCG31-compromised plants, thus being a possible cause of the resistance to M. oryzae and the dwarf growth phenotype. The findings show that in rice an abnormal cuticle formation may affect the signaling of plant growth and defense

OsMADS26 negatively regulates resistance to pathogens and drought tolerance in rice

Universite de Montpellier, Unite Mixte de Recherche Diversite, Adaptation, et Developpement des Plantes, 34095 Montpellier cedex 5, France (G.N.K., I.B., P.G.); Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement, Unite Mixte de Recherche Amelioration Genetique et Adaptation des Plantes Mediterraneennes et Tropicales, 34398 Montpellier cedex 5, France (G.N.K., P.K.P., F.R., M.B., D.M., E.G.); Department of Biotechnology, Guru Nanak Dev University, Amritsar 143 005, India (P.K.P.); Department of Plant Systems Biology, Flanders Institute for Biotechnology, 9052 Ghent, Belgium (B.P., T.B.); Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (B.P., T.B.); Institut National de la Recherche Agronomique, Unite Mixte de Recherche Biologie et Genetique des Interactions Plante-Parasite, 34398 Montpellier, France (P.B., J.-B.M.); Laboratoire Mixte International Rice Functional Genomics and Plant Biotechnology, Institut de Recherche pour le Developpement, University of Science and Technology of Hanoi, Agricultural Genetics Institute, 00 000 Hanoi, Vietnam (C.D.M., V.N.D., P.G.); International Center for Tropical Agriculture, 6713 Cali, Colombia (M.G.S., I.M.); Consiglio Nazionale delle Ricerche, Institute of Agricultural Biology and Biotechnology, 20133 Milan, Italy (A.-M.G.);and Institut de Recherche pour le Developpement, Unite Mixte de Recherche Interactions Plantes Microorganismes et Environnement, 34398 Montpellier cedex, France (C.B.