Mitochondrial estrogen receptors alter mitochondrial priming and response to endocrine therapy in breast cancer cells.

Breast cancer is the most common cancer with a high rate of mortality and morbidity among women worldwide. Estrogen receptor status is an important prognostic factor and endocrine therapy is the choice of first-line treatment in ER-positive breast cancer. However, most tumors develop resistance to endocrine therapy. Here we demonstrate that BH3 profiling technology, in particular, dynamic BH3 profiling can predict the response to endocrine therapy agents as well as the development of acquired resistance in breast cancer cells independent of estrogen receptor status. Immunofluorescence analysis and subcellular fractionation experiments revealed distinct ER-α and ER-ß subcellular localization patterns in breast cancer cells, including mitochondrial localization of both receptor subtypes. shRNA-mediated depletion of ER-ß in breast cancer cells led to resistance to endocrine therapy agents and selective reconstitution of ER-ß in mitochondria restored sensitivity. Notably, mitochondria-targeted ER-α did not restore sensitivity, even conferred further resistance to endocrine therapy agents. In addition, expressing mitochondria-targeted ER-ß in breast cancer cells resulted in decreased mitochondrial respiration alongside increased total ROS and mitochondrial superoxide production. Furthermore, our data demonstrated that mitochondrial ER-ß can be successfully targeted by the selective ER-ß agonist Erteberel. Thus, our findings provide novel findings on mitochondrial estrogen signaling in breast cancer cells and suggest the implementation of the dynamic BH3 technique as a tool to predict acquired endocrine therapy resistance.

Kinome-wide RNAi screening for mediators of ABT-199 resistance in breast cancer cells identifies Wee1 as a novel therapeutic target.

Antiapoptotic and proapoptotic BCL-2 protein family members regulate mitochondrial apoptotic pathway. Small molecule inhibitors of antiapoptotic BCL-2 proteins including BCL-2-specific inhibitor ABT-199 (Venetoclax) are in clinical development. However, the efficiency of ABT-199 as a single agent in solid tumors is limited. We performed a high-throughput RNAi kinome screen targeting 691 kinases to identify potentially targetable kinases to enhance ABT-199 response in breast cancer cells. Our studies identified Wee1 as the primary target kinase to overcome resistance to ABT-199. Depletion of Wee1 by siRNA-mediated knockdown or inhibition of Wee1 by the small molecule Wee1 inhibitor AZD1775 sensitized SKBR3, MDA-MB-468, T47D and CAMA-1 breast cancer cells to ABT-199 along with decreased MCL1. BH3-only proteins PUMA and BIM functionally contribute to apoptosis signaling following co-targeting BCL-2 and Wee1. Suppression of Wee1 function increased mitochondrial cell death priming. Furthermore, we found that Wee1 inhibition altered MCL1 phosphorylation and protein stability, which led to HUWE1-mediated MCL1 degradation. Our findings suggest that Wee1 inhibition can overcome resistance to ABT-199 and provide a rationale for further translational investigation of BCL-2 inhibitor/Wee1 inhibitor combination in breast cancer.

RAB25 confers resistance to chemotherapy by altering mitochondrial apoptosis signaling in ovarian cancer cells.

Ovarian cancer remains one of the most frequent causes of cancer-related death in women. Many patients with ovarian cancer suffer from de novo or acquired resistance to chemotherapy. Here, we report that RAB25 suppresses chemotherapy-induced mitochondrial apoptosis signaling in ovarian cancer cell lines and primary ovarian cancer cells. RAB25 blocks chemotherapy-induced apoptosis upstream of mitochondrial outer membrane permeabilization by either increasing antiapoptotic BCL-2 proteins or decreasing proapoptotic BCL-2 proteins. In particular, BAX expression negatively correlates with RAB25 expression in ovarian cancer cells. BH3 profiling assays corroborated that RAB25 decreases mitochondrial cell death priming. Suppressing RAB25 by means of RNAi or RFP14 inhibitory hydrocarbon-stapled peptide sensitizes ovarian cancer cells to chemotherapy as well as RAB25-mediated proliferation, invasion and migration. Our data suggest that RAB25 is a potential therapeutic target for ovarian cancer.

Distinct apoptotic blocks mediate resistance to panHER inhibitors in HER2+ breast cancer cells.

Despite the development of novel targeted therapies, de novo or acquired chemoresistance remains a significant factor for treatment failure in breast cancer therapeutics. Neratinib and dacomitinib are irreversible panHER inhibitors, which block their autophosphorylation and downstream signaling. Moreover, neratinib and dacomitinib have been shown to activate cell death in HER2-overexpressing cell lines. Here we showed that increased MCL1 and decreased BIM and PUMA mediated resistance to neratinib in ZR-75-30 and SKBR3 cells while increased BCL-XL and BCL-2 and decreased BIM and PUMA promoted neratinib resistance in BT474 cells. Cells were also cross-resistant to dacomitinib. BH3 profiles of HER2+ breast cancer cells efficiently predicted antiapoptotic protein dependence and development of resistance to panHER inhibitors. Reactivation of ERK1/2 was primarily responsible for acquired resistance in SKBR3 and ZR-75-30 cells. Adding specific ERK1/2 inhibitor SCH772984 to neratinib or dacomitinib led to increased apoptotic response in neratinib-resistant SKBR3 and ZR-75-30 cells, but we did not detect a similar response in neratinib-resistant BT474 cells. Accordingly, suppression of BCL-2/BCL-XL by ABT-737 was required in addition to ERK1/2 inhibition for neratinib- or dacomitinib-induced apoptosis in neratinib-resistant BT474 cells. Our results showed that different mitochondrial apoptotic blocks mediated acquired panHER inhibitor resistance in HER2+ breast cancer cell lines as well as highlighted the potential of BH3 profiling assay in prediction of panHER inhibitor resistance in breast cancer cells.

Standalone cohesin as a molecular shuttle in cellulosome assembly.

The cellulolytic bacterium Ruminococcus flavefaciens of the herbivore rumen produces an elaborate cellulosome system, anchored to the bacterial cell wall via the covalently bound scaffoldin ScaE. Dockerin-bearing scaffoldins also bind to an autonomous cohesin of unknown function, called cohesin G (CohG). Here, we demonstrate that CohG binds to the scaffoldin-borne dockerin in opposite orientation on a distinct site, relative to that of ScaE. Based on these structural data, we propose that the complexed dockerin is still available to bind ScaE on the cell surface. CohG may thus serve as a molecular shuttle for delivery of scaffoldins to the bacterial cell surface.

Insights into a type III cohesin-dockerin recognition interface from the cellulose-degrading bacterium Ruminococcus flavefaciens.

Cellulosomes are large multicomponent cellulose-degrading assemblies found on the surfaces of cellulolytic microorganisms. Often containing hundreds of components, the self-assembly of cellulosomes is mediated by the ultra-high-affinity cohesin-dockerin interaction, which allows them to adopt the complex architectures necessary for degrading recalcitrant cellulose. Better understanding of how the cellulosome assembles and functions and what kinds of structures it adopts will further effort to develop industrial applications of cellulosome components, including their use in bioenergy production. Ruminococcus flavefaciens is a well-studied anaerobic cellulolytic bacteria found in the intestinal tracts of ruminants and other herbivores. Key to cellulosomal self-assembly in this bacterium is the dockerin ScaADoc, found on the non-catalytic structural subunit scaffoldin ScaA, which is responsible for assembling arrays of cellulose-degrading enzymes. This work expands on previous efforts by conducting a series of binding studies on ScaADoc constructs that contain mutations in their cohesin recognition interface, in order to identify which residues play important roles in binding. Molecular dynamics simulations were employed to gain insight into the structural basis for our findings. A specific residue pair in the first helix of ScaADoc, as well as a glutamate near the C-terminus, was identified to be essential for cohesin binding. By advancing our understanding of the cohesin binding of ScaADoc, this study serves as a foundation for future work to more fully understand the structural basis of cellulosome assembly in R. flavefaciens.

Antibody array-based immunosensor for detecting cardiovascular disease risk markers.

Quantitative detection of proteins in multiplexed platforms presents technical advantages at clinical and laboratory settings compared to the monoplex ELISA method. With this purpose, we implemented a pilot study using in-house-designed sandwich-type antibody array for multiplexed detection of seven cardiovascular disease (CVD) risk markers and compared the performance of our immunosensor to conventional ELISA kits. Results indicated that our immunosensor can determine serum amyloid A (SAA), vascular cell adhesion molecule (VCAM), and myoglobin (MYO) concentrations accurately, precisely, and above all very much similar to ELISA. Hence, multiplexed detection and quantification of SAA, VCAM, and MYO with our immunosensor can be considered as a potential multiplexed alternative to the ELISA method.

From in silico to in vitro: modelling and production of Trichoderma reesei endoglucanase 1 and its mutant in Pichia pastoris.

In this study, a major cellulase, namely endoglucanase 1 (EGI) from Trichoderma reesei was mutated by the introduction of four different lysine and glycine rich loops to create a hotspot for directed crosslinking of EGI away from the active site. The impact of the inserted loops on the stability of the enzyme was analyzed using molecular dynamics (MD) and the effect on the active site was studied using molecular mechanics (MM) simulations. The best loop mutation predicted in silico (EGI_L5) was introduced to EGI via site directed mutagenesis. The loop mutant EGI_L5 and EGI were both expressed in Pichia pastoris. Enzymes were characterized and their activities against soluble substrates such as CMC and 4-MUC were determined. Both enzymes exhibited similar pH and temperature activity and thermal stability profiles. Moreover, specific activity of EGI_L5 against 4-MUC was found to be the same as the native enzyme.

Improved thermostability of Clostridium thermocellum endoglucanase Cel8A by using consensus-guided mutagenesis.

The use of thermostable cellulases is advantageous for the breakdown of lignocellulosic biomass toward the commercial production of biofuels. Previously, we have demonstrated the engineering of an enhanced thermostable family 8 cellulosomal endoglucanase (EC 3.2.1.4), Cel8A, from Clostridium thermocellum, using random error-prone PCR and a combination of three beneficial mutations, dominated by an intriguing serine-to-glycine substitution (M. Anbar, R. Lamed, E. A. Bayer, ChemCatChem 2:997-1003, 2010). In the present study, we used a bioinformatics-based approach involving sequence alignment of homologous family 8 glycoside hydrolases to create a library of consensus mutations in which residues of the catalytic module are replaced at specific positions with the most prevalent amino acids in the family. One of the mutants (G283P) displayed a higher thermal stability than the wild-type enzyme. Introducing this mutation into the previously engineered Cel8A triple mutant resulted in an optimized enzyme, increasing the half-life of activity by 14-fold at 85°C. Remarkably, no loss of catalytic activity was observed compared to that of the wild-type endoglucanase. The structural changes were simulated by molecular dynamics analysis, and specific regions were identified that contributed to the observed thermostability. Intriguingly, most of the proteins used for sequence alignment in determining the consensus residues were derived from mesophilic bacteria, with optimal temperatures well below that of C. thermocellum Cel8A.

Effect of codon optimization on the expression of Trichoderma reesei endoglucanase 1 in Pichia pastoris.

Trichoderma reesei cellulases are important biocatalysts for a wide range of industrial applications that include the paper, feed, and textile industries. T. reesei endoglucanase 1 (egl1) was successfully expressed as an active and stable catalyst in Pichia pastoris for the first time. Codon optimization was applied to egl1 of T. reesei to enhance its expression levels in P. pastoris. When compared with the originally cloned egl1 gene of T. reesei, the synthetic codon optimized egl1 gene (egl1s) was expressed at a higher level in P. pastoris. Batch fermentations of both clones with the same copy number under controlled conditions indicated that codon optimized EGI enzyme activity increased to 1.24 fold after 72 h of methanol induction. Our research indicated that P. pastoris is a suitable host for cellulase production.

Apoptotic blocks and chemotherapy resistance: strategies to identify Bcl-2 protein signatures.

Acquired or innate resistance to chemotherapy is a major drawback of cancer therapeutics, which is frequently seen in epithelial cancers. However, the molecular mechanisms underlying chemotherapy resistance remain poorly understood. The mitochondrial pathway is a critical death pathway common to many different types of chemotherapy. Aberrations in this pathway can result in resistance to chemotherapy. The Bcl-2 family of proteins control commitment to programmed cell death by mitochondrial apoptosis. In this review, we will summarize the strategies in determining the components of apoptotic defects responsible for chemotherapy resistance, mainly focused on Bcl-2 protein network.

The effect of ethinyl estradiol-cyproterone acetate treatment on homocysteine levels in women with polycystic ovary syndrome.

OBJECTIVE: Women with polycystic ovary syndrome (PCOS) have multiple risk factors for cardiovascular disease. The cardiovascular risk marker homocysteine (Hcy) is elevated in women with PCOS. This prospective study investigated the effect of oral contraceptives containing ethinyl estradiol-cyproterone acetate (EE-CA) on serum Hcy levels in women with PCOS. STUDY DESIGN: A total of 30 women with PCOS were enrolled in this prospective study. The diagnosis of PCOS was made according to the criteria of the Rotterdam PCOS consensus workshop group. All women took oral contraceptives containing EE/CA (35 microg/2 mg) for 3 months. Serum samples for Hcy, lipid profile and hormones were obtained during the early follicular phase (days 3-5) of the spontaneous or progestin-induced bleeding at baseline, and after the third treatment cycle. RESULTS: Three months of EE-CA therapy significantly decreased the Hcy levels from 55.97 +/- 16.04 to 54.03 +/- 16.15 (P = 0.01). A significant correlation was observed between the Hcy and total and free testosterone levels (r = 0.44, P = 0.015 and r = 0.46, P = 0.001 respectively). CONCLUSIONS: Although the decrease in Hcy levels with EE-CA therapy was statistically significant, further studies are necessary to determine the clinical benefit of this treatment.

Does postoperative misoprostol use induce intestinal motility? A prospective randomised double-blind trial.

BACKGROUND: Misoprostol has been shown to increase colonic activity and decrease colonic transit time in chronic constipation patients. AIMS: The aim of this prospective, randomised, double-blind study was to examine the effectiveness of rectally administered misoprostol on inducing intestinal motility after gynaecological surgery. METHODS: Eighty women who underwent hysterectomy were divided randomly into three groups. Group A received misoprostol 200 microg rectally while group B received 400 microg rectal misoprostol after surgery before leaving the operating room. Patients in group C received no drugs. Bowel sounds in four quadrants were checked every hour and possible side-effects of misoprostol like nausea, vomiting, and distension were evaluated. The time interval between surgery and flatus pass and the need of analgesics were noted. Statistical analyses were done with Mann-Whitney U-test and chi2 tests where available. RESULTS: The time between surgery and presence of bowel sounds in four quadrants were similar in all groups (2.7 +/- 1.6, 2.9 +/- 1.2, 2.8 +/- 1.3 h, for groups A, B, and C, respectively). No difference was observed in flatus pass time. The incidence of nausea was significantly increased in group B compared to controls (P < 0.01). Additional analgesic need was significantly higher in groups A and B when compared to controls (P < 0.05 and P < 0.01, for groups A and B, respectively). CONCLUSION: Rectally administered misoprostol does not improve intestinal motility in the early postoperative period and thus, it is not effective in providing early oral food intake. On the contrary, it causes distention that requires additional analgesics and vomiting that naturally limits oral diet intake.