Prolactin-induced neuroprotection against excitotoxicity is mediated via PI3K/AKT and GSK3β/NF-κB in primary cultures of hippocampal neurons

Prolactin (PRL) is a polypeptide hormone that has been reported to play a significant role in neuroprotection against neuronal excitotoxicity produced by glutamate (Glu) or kainic acid (KA) in both, in vitro and in vivo models. However, the molecular mechanisms involved in PRL's neuroprotective effects in the hippocampus have not been completely elucidated. The aim of the present study was to assess the signaling pathways involved in PRL neuroprotection against excitotoxicity. Primary rat hippocampal neuronal cell cultures were used to assess PRL-induced signaling pathway activation. The effects of PRL on neuronal viability, as well as its effects on activation of key regulatory pathways, phosphoinositide 3-kinases/Protein Kinase B (PI3K/AKT) and glycogen synthase kinase 3β / nuclear factor kappa B (GSK3β/NF-κB), were evaluated under conditions of Glutamate-induced excitotoxicity. Additionally, the effect on downstream regulated genes such as Bcl-2 and Nrf2, was assessed. Here, we show that the PI3K/AKT signaling pathway is activated by PRL treatment during excitotoxicity, promoting neuronal survival through upregulation of active AKT and GSK3β/NF-κB, resulting in induction of Bcl-2 and Nrf2 gene expression. Inhibition of the PI3K/AKT signaling pathway abrogated the protective effect of PRL against Glu-induced neuronal death. Overall, results indicate that the neuroprotective actions of PRL are mediated in part, by the activation of the AKT pathway and survival genes. Our data support the idea that PRL could be useful as a potential neuroprotective agent in different neurological and neurodegenerative diseases.

713 Novel protease activatable linker with tumor targeting motifs enhances the retention of cytokine prodrug and active cytokine at disease site and demonstrates improved efficacy in preclinical model

Background

An emerging class of new protease-activatable prodrugs designed to enhance on-target activity and reduce off-target toxicity are being actively developed. Cytokines are complex immune mediators which display potent anti-tumor activity in preclinical models and have delivered clinical responses in several advanced tumor types. However, clinical development of cytokine therapies has been hampered by high systemic toxicity, a narrow therapeutic index and short circulatory half-life. To address these shortcomings, we have developed next-generation cytokine therapies, On Demand Cytokines or ODCs.

Methods

ODCs are protease-activatable cytokine prodrugs in which the cytokine is linked to an inhibitory moiety via a short proprietary peptide motif. These recombinant proteins are designed to exploit the protease activity present within the tumor microenvironment (TME) and enable the local release of active cytokine to trigger an anti-tumor immune response. ODCs contain tumor stroma targeting elements to further enhance their retention and activation within the malignant tissue. We have developed an array of stromaphilic ODCs, including a panel of IL-2 prodrugs containing single or dual tumor stroma binding motifs and report their preclinical in vitro and in vivo characterization.

Results

All IL-2 prodrugs were successfully manufactured and activated in vitro by Matrix Metalloprotease cleavage which triggered the release of functional cytokine. Binding of prodrugs to tumor stroma components was confirmed in vitro. The ODC-IL2 panel was tested in vivo as single agent in the subcutaneous syngeneic B16F10 melanoma model. The uncleaved drugs were retained in the tumor at 5 to 20-fold higher levels than a control cytokine prodrug lacking any tumor targeting elements. Furthermore, intratumoral levels of IL-2 and IFNg were increased 8 to 80-fold and 10 to 40-fold respectively compared to cytokine levels measured in the control non-targeted ODC treated arm. Finally, stromaphilic ODCs displayed substantially enhanced levels in circulation over non-targeted ODC. Superior anti-tumor efficacy was observed for all stroma targeting pro-cytokines with near complete tumor growth inhibition achieved with the dual targeting site construct.

Conclusions

We have demonstrated that the On Demand Cytokine platform can generate protease-activatable cytokine prodrugs with enhanced tumor retention and on-target activity, to ultimately deliver safer and more effective immunotherapies.

Family Relationships and Their Associations With Perceptions of Family Functioning in Mothers of Children With Intellectual Disability

We explored whether reports of three dyadic relationships (marital/partner, parent-child, sibling) were related to perceptions of family functioning in 467 mothers of children with intellectual disability aged 4-15 years. Structural equation models were fitted to examine associations between relationship indicators and family functioning. The final structural model showed that partner relationship satisfaction, partner disagreement, child-parent conflict, and sibling relationship warmth accounted for the most variance in family functioning, with partner relationship satisfaction having the strongest positive association. Dimensions of dyadic relationships appear to be associated with broader constructs of family functioning in this sample of mothers, signifying the potential for systemic intervention.

A Population-Based Study of the Behavioral and Emotional Adjustment of Older Siblings of Children with and without Intellectual Disability

This is the first study on the behavioral and emotional adjustment of siblings of children with intellectual disabilities (ID) to use a population-based sample, from the third wave of the Millennium Cohort Study (MCS); a UK longitudinal birth cohort study. We examined differences between nearest-in-age older siblings (age 5–15) of MCS children (likely mainly with mild to moderate ID) identified with ID (n = 257 siblings) or not (n = 7246 siblings). The Strengths and Difficulties Questionnaire (SDQ) measured all children’s adjustment. For SDQ total problems, 13.9% of siblings of children with ID and 8.9% of siblings of children without had elevated scores (OR 1.65; 95% CI 1.04, 2.62; p = 0.031). Similar group differences were found for SDQ peer and conduct problems. In logistic regression models, variables consistently associated with older sibling adjustment were: adjustment of the MCS cohort child, older sibling being male, family socio-economic position, primary carer psychological distress, and being from a single parent household. The ID grouping variable was no longer associated with adjustment for all SDQ domains, except siblings of children with ID were less likely to be identified as hyperactive (OR 0.30; 95% CI 0.10, 0.87; p = 0.027). Some older siblings of children with ID may be at additional risk for behavioral and emotional problems. Group differences were related mainly to social and family contextual factors. Future longitudinal research should address developmental pathways by which children with ID may affect sibling adjustment.

Psychological well-being of fathers with and without a child with intellectual disability: a population-based study

BACKGROUND

Few studies have explored the well-being of fathers of children with intellectual disability (ID), despite the significant role that they play in their children's lives. The current study compared fathers of children with and without a child with ID on measures of psychological well-being (life satisfaction, work-family balance and general health) and dimensions of parenting (parenting self-efficacy and parent-child closeness) and then examined whether the presence of a child with ID in the family was a significant predictor of paternal well-being when controlling for a number of father (age, education, employment and residency), child (ID status, gender, behavioural and emotional problems) and family (income poverty and number of children in the household) variables.

METHODS

Data were drawn from the third wave of the Millennium Cohort Study, a UK population-representative and cohort study, where the cohort child was 5 years of age; 256 fathers were identified as having a child with ID, with data available for 10 187 fathers without a child with ID. Fathers were compared on the four well-being and parenting outcomes and then multiple regression models were conducted to explore associations between these outcomes and variables identified as potential correlates of well-being.

RESULTS

Initial group comparisons showed that there were differences in the well-being of fathers, with fathers of children with ID reporting poorer life satisfaction and general health. However, these differences were small. Regression analyses showed that child behavioural and emotional problems, living in income poverty and paternal employment were more important than disability status in predicting fathers' well-being.

CONCLUSIONS

These works add to the limited amount of research on fathers using population-representative data. The current findings are consistent with rejecting a general simplistic and negative narrative that raising a child with ID puts fathers at risk of poorer outcomes. However, some fathers, such as those with children with behavioural problems and living in poverty, may require greater support. Future longitudinal research that explores the impact of paternal well-being on the long-term outcomes of children with and without ID is warranted.

Attitudes of anesthetists towards an anesthesia-led nurse practitioner model for low-risk colonoscopy procedures: a cross-sectional survey

BACKGROUND

The mounting pressure on the Australian healthcare system is driving a continual exploration of areas to improve patient care and access and to maximize utilization of our workforce. We hypothesized that there would be support by anesthetists employed at our hospital for the design, development, and potential implementation of an anesthesia-led nurse practitioner (NP) model for low-risk colonoscopy patients.

METHODS

We conducted a cross-sectional, mixed methods study to ascertain the attitudes and acceptability of anesthetists towards a proposed anesthesia-led NP model for low-risk colonoscopy patients. An online survey using commercial software and theoretical questions pertaining to participants' attitudes towards an anesthesia-led NP model was e-mailed to consultant anesthetists. Participants were also invited to participate in a voluntary 20-min face-to-face interview.

RESULTS

A total of 60 survey responses were received from a pool of 100 anesthetists (response rate = 60%, accounting for 8.04% margin of error). Despite the theoretical benefits of improved patient access to colonoscopy services, most anesthetists were not willing to participate in the supervision and training of NPs. The predominant themes underlying their lack of support for the program were a perception that patient safety would be compromised compared to the current model of anesthesia-led care, the model does not meet the Australian and New Zealand College of Anesthetists guidelines for procedural sedation and analgesia, and the program may be a public liability prone to litigation in the event of an adverse outcome. Concerns about consumer acceptance and cost-effectiveness were also raised. Finally, participants thought the model should be pilot tested to better understand consumer attitudes, logistical feasibility, patient and proceduralist attitudes, clinical governance, and, importantly, patient safety.

CONCLUSIONS

Most anesthetists working in a single-center university hospital did not support an anesthesia-led NP model for low-risk colonoscopy patients. Patient safety, violations of the current Australian and New Zealand College of Anesthetists guidelines on procedural sedation, and logistical feasibility were significant barriers to the acceptance of the model.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry, 12619001036101.

1000 Families Study, a UK multiwave cohort investigating the well-being of families of children with intellectual disabilities: cohort profile

PURPOSE

The 1000 Families Study is a large, UK-based, cohort of families of children with intellectual disability (ID). The main use of the cohort data will be to describe and explore correlates of the well-being of families of children with ID, including parents and siblings, using cross-sectional and (eventually) longitudinal analyses. The present cohort profile intends to describe the achieved cohort.

PARTICIPANTS

Over 1000 families of UK children with ID aged between 4 and 15 years 11 months (total n=1184) have been recruited. The mean age of the cohort was 9.01 years old. The cohort includes more boys (61.8%) than girls (27.0%; missing 11.1%). Parents reported that 45.5% (n=539) of the children have autism. Most respondents were a female primary caregiver (84.9%), and 78.0% were the biological mother of the cohort child with ID. The largest ethnic group for primary caregivers was White British (78.5%), over half were married and living with their partner (53.3%) and 39.3% were educated to degree level.

FINDINGS TO DATE

Data were collected on family, parental and child well-being, as well as demographic information. Wave 1 data collection took place between November 2015 and January 2017, primarily through online questionnaires. Telephone interviews were also completed by 644 primary caregivers.

FUTURE PLANS

Wave 2 data collection is ongoing and the research team will continue following up these families in subsequent waves, subject to funding availability. Results will be used to inform policy and practice on family and child well-being in families of children with ID. As this cohort profile aims to describe the cohort, future publications will explore relevant research questions and report key findings related to family well-being.

A clinically feasible multiplex proteomic immunoassay as a novel functional diagnostic for pancreatic ductal adenocarcinoma

To date, targeted therapy for pancreatic ductal adenocarcinoma (PDAC) remains largely unsuccessful in the clinic. Current genomics-based technologies are unable to reflect the quantitative, dynamic signaling changes in the tumor, and require larger tumor samples that are difficult to obtain in PDAC patients. Therefore, a highly sensitive functional tool that can reliably and comprehensively inform intra-tumoral signaling events is direly needed to guide treatment decision. We tested the utility of a highly sensitive proteomics-based functional diagnostic platform, Collaborative Enzyme Enhanced Reactive-immunoassay (CEERTM), on fine-needle aspiration (FNA) samples obtained from 102 patients with radiographically-evident pancreatic tumors. Two FNA passes were collected from each patient, hybridized to customized chips coated with an array of capture antibodies, and detected using two enzyme-conjugated antibodies which emit quantifiable signals. We demonstrate that this technique is highly sensitive in detecting total and phosphorylated forms of multiple signaling molecules in FNA specimens, with reasonable correlation of marker intensities between two different FNA passes. Notably, signals of several markers were significantly higher in PDAC compared to non-cancerous samples. In PDAC samples, we found high total c-Met signal to be associated with poor survival, and confirmed this finding using an independent PDAC tissue microarray.

HER2-Overexpressing Breast Cancers Amplify FGFR Signaling upon Acquisition of Resistance to Dual Therapeutic Blockade of HER2

Purpose: Dual blockade of HER2 with trastuzumab and lapatinib or pertuzumab has been shown to be superior to single-agent trastuzumab. However, a significant fraction of HER2-overexpressing (HER2⁺) breast cancers escape from these drug combinations. In this study, we sought to discover the mechanisms of acquired resistance to the combination of lapatinib + trastuzumab.Experimental Design: HER2⁺ BT474 xenografts were treated with lapatinib + trastuzumab long-term until resistance developed. Potential mechanisms of acquired resistance were evaluated in lapatinib + trastuzumab-resistant (LTR) tumors by targeted capture next-generation sequencing. In vitro experiments were performed to corroborate these findings, and a novel drug combination was tested against LTR xenografts. Gene expression and copy-number analyses were performed to corroborate our findings in clinical samples.Results: LTR tumors exhibited an increase in FGF3/4/19 copy number, together with an increase in FGFR phosphorylation, marked stromal changes in the tumor microenvironment, and reduced tumor uptake of lapatinib. Stimulation of BT474 cells with FGF4 promoted resistance to lapatinib + trastuzumab in vitro Treatment with FGFR tyrosine kinase inhibitors reversed these changes and overcame resistance to lapatinib + trastuzumab. High expression of FGFR1 correlated with a statistically shorter progression-free survival in patients with HER2⁺ early breast cancer treated with adjuvant trastuzumab. Finally, FGFR1 and/or FGF3 gene amplification correlated with a lower pathologic complete response in patients with HER2⁺ early breast cancer treated with neoadjuvant anti-HER2 therapy.Conclusions: Amplification of FGFR signaling promotes resistance to HER2 inhibition, which can be diminished by the combination of HER2 and FGFR inhibitors. Clin Cancer Res; 23(15); 4323-34. ©2017 AACR.

Parental relationship satisfaction in families of children with autism spectrum disorder (ASD): A multilevel analysis

Caring for a child with Autism Spectrum Disorder (ASD) has been linked to a range of negative outcomes for parents but less is known about the putative impact upon the parental couple relationship. The relationship satisfaction of parents of children with ASD was investigated using multilevel modeling. Mothers and fathers (146 couples) reported on their relationship satisfaction, their own well-being, and the behavior problems of the child with ASD and a sibling. Results indicated that mothers and fathers reported similar levels of relationship satisfaction and it was significantly and negatively associated with parental depression and the behavior problems of the child with ASD. Relationship satisfaction was unrelated to the behavior problems of a sibling, the number of children in the household, and family socioeconomic position (SEP). Further longitudinal research that captures a broader range of variables is required to build a theoretical understanding of relationship satisfaction in families of children with ASD. Current evidence suggests that early intervention routes targeting either child behavior problems, parental mental health, or the couple relationship have the potential to benefit inter-connected subsystems within the broader family system. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1259-1268. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Priority setting in research: user led mental health research

PLAIN ENGLISH SUMMARY

Involving people in health research is increasingly recognised as being important to make sure that research is focused more on the needs of people who use health services. At present, ideas about what should be researched most often comes from researchers and/or health professionals like doctors and nurses rather than people with a lived experience of mental illness. In this study, we will talk with this group of people from across Wales to explore what they think research into their health services should focus on. The findings from this work will help to influence the work of the National Centre for Mental Health Research Partnership Group; as well as` researchers and health professionals and others who concentrate on mental health research. The Research group is a partnership between people with a lived experience of mental ill health and professionals with an interest in mental ill health. The group plan to take forward the ideas that came from this research and some of the ideas have already been used to increase funding in the area of mental health research.

ABSTRACT

Background This paper is the result of continued collaboration between members of the Service User and Carer Research Partnership, based in Wales and supported by the National Centre for Mental Health, Health and Care Research Wales, and Hafal. The aim of this study was to explore the research priorities of people with experience of mental health services which include people with a lived experience of mental ill health, their carers, and professionals. Method A nominal group technique was used to gather data. A one-day workshop 'Getting Involved in Research: Priority Setting' was held to gather the ideas and suggestions for research priorities from people who have experience of mental health services. Results Twenty-five participants attended the workshop. 5 were mental health professionals, 20 had a lived experience of mental ill health, (of which 3 were also carers). 11 were male and 14 were female. 120 research ideas were generated across 6 'Ideas Generating Workstations'. Participants took part in a 3 stage vote to narrow down the ideas to 2 main research priorities. Conclusion The two main research priority areas that were identified:'Developing the knowledge of mental health issues amongst school-aged children' as a vehicle to overcome stigma and discrimination, and to support young people to manage their own mental health.'Developing education as a tool for recovery', for example by peer support. In addition, participants engaged in a notable discussion over the research priority: 'How are carers supported during the recovery of the person for whom they care?'

Low EGFR/MET ratio is associated with resistance to EGFR inhibitors in non-small cell lung cancer

PURPOSE

Although activating mutations in the epidermal growth factor receptor (EGFR) gene are predictive markers for response to EGFR inhibitors, 30-40% of EGFR-mutant non-small cell lung cancer (NSCLC) patients are de novo non-responders. Hence, we sought to explore additional biomarkers of response.

METHODS

We conducted a prospective pilot study to characterize the expression and/or activation of key receptor tyrosine kinases (RTKs) in stage IIIB-IV NSCLC tumors. A total of 37 patients were enrolled and 34 underwent EGFR inhibitor treatment.

RESULTS

As expected, patients bearing activating EGFR mutations showed increased progression free survival (PFS) compared to patients with wild-type EGFR status (9.3 vs 1.4 months, p = 0.0629). Analysis of baseline tumor RTK profiles revealed that, regardless of EGFR mutation status, higher levels of EGFR relative to MET correlated with longer PFS. At multiple EGFR/MET ratio cut-offs, including 1, 2 and 3, median PFS according to below vs. above cut-offs were 0.4 vs. 6.1 (p = 0.0001), 0.5 vs. 9.3 (p = 0.0006) and 1.0 vs. 11.2 months (p = 0.0008), respectively.

CONCLUSION

The EGFR/MET ratio measured in tumors at baseline may help identify NSCLC patients most likely to benefit from prolonged PFS when treated with EGFR inhibitors.

Post transcriptional control of the epigenetic stem cell regulator PLZF by sirtuin and HDAC deacetylases

BACKGROUND

The transcriptional repressor promyelocytic leukemia zinc finger protein (PLZF) is critical for the regulation of normal stem cells maintenance by establishing specific epigenetic landscape. We have previously shown that CBP/p300 acetyltransferase induces PLZF acetylation in order to increase its deoxynucleotidic acid (DNA) binding activity and to enhance its epigenetic function (repression of PLZF target genes). However, how PLZF is inactivated is not yet understood.

RESULTS

In this study, we demonstrate that PLZF is deacetylated by both histone deacetylase 3 and the NAD+ dependent deacetylase silent mating type information regulation 2 homolog 1 (SIRT1). Unlike other PLZF-interacting deacetylases, these two proteins interact with the zinc finger domain of PLZF, where the activating CBP/p300 acetylation site was previously described, inducing deacetylation of lysines 647/650/653. Overexpression of histone deacetylase 3 (HDAC3) and SIRT1 is associated with loss of PLZF DNA binding activity and decreases PLZF transcriptional repression. As a result, the chromatin status of the promoters of PLZF target genes, involved in oncogenesis, shift from a heterochromatin to an open euchromatin environment leading to gene expression even in the presence of PLZF.

CONCLUSIONS

Consequently, SIRT1 and HDAC3 mediated-PLZF deacetylation provides for rapid control and fine-tuning of PLZF activity through post-transcriptional modification to regulate gene expression and cellular homeostasis.

Abstract 4652: Cerebrospinal fluid pharmacokinetics and pharmacodynamics following high-dose erlotinib treatment in brain cancer patients

Patients with non-small cell lung cancer (NSCLC) who develop leptomeningeal metastases show significant clinical improvement following high-dose gefitinib therapy. Based on this data, we aimed to explore the effect of high-dose erlotinib on clinical response and CNS penetration in primary or metastatic CNS cancer.

We selected patients who had received prior therapy for either primary glioma or for NSCLC with metastases to the brain and treated them with an alternate dosing regimen of erlotinib. Blood and cerebrospinal fluid (CSF) samples were collected at various time points to assess levels of erlotinib. We found that CSF concentrations of erlotinib were generally 2% that of plasma concentrations. Among the five patients examined, CSF concentrations of erlotinib reached up to 131 nM when high doses were administered at 600 to 1200 mg every four to six days. Additionally, drug clearance was decreased with an increased dosing regimen in one of the patients. In one patient, the area under the curve (AUC) estimations showed a 24% increase in the CSF versus only a 2% increase in the plasma following an increase from 150 mg to 600 mg of erlotinib. Moreover, longitudinal CSF samples were evaluated for expression and activation of EGFR as well as various other receptor tyrosine kinases, such as ErbB2, ErbB3, cMET and IGF1R, using the highly sensitive multiplexed immunoassay CEER© platform. The latter provides insight into the molecular makeup of the CNS cancer throughout the therapeutic regimen.

Our clinical data on patients receiving erlotinib therapy for primary and metastatic CNS disease suggests that increased dosing of erlotinib, administered as a pulse dose every four to six days leads to increased CSF drug concentrations. In spite of the variations seen among different patients, we conclude that higher erlotinib dosing regimens can provide enhanced CNS penetration that may prove to be more effective in primary and metastatic CNS cancers especially when coupled with real-time molecular monitoring of the disease to help guide the clinician during the course of treatment.

Citation Format: Sandra Pastorino, Sandeep C. Pingle, Emma Langley, Phillip Kim, Tiffany Juarez, Pengfei Jiang, Christopher Tucker, Txheng Yang, Marlon Saria, Sharat Singh, Santosh Kesari. Cerebrospinal fluid pharmacokinetics and pharmacodynamics following high-dose erlotinib treatment in brain cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4652. doi:10.1158/1538-7445.AM2014-4652

P3-18-04: Pathway Guided Selection of Targeted Inhibitors for Breast Cancer Treatment

Background: The ability to functionally profile a whole spectrum of pathway proteins in tumor may provide valuable information about the likelihood of drug response and potential mechanisms for drug resistance in breast cancer (BCA) patients. Here we report a comprehensive pathway analysis of membrane associated kinases such as HER1, HER2, HER3, cMET, IGF1R, PI3K and downstream signal transduction proteins including Shc, AKT, ERK, MEK, PDK1, PRAS40, p70S6K and eIF4e in breast cancer cell lines and xenografts as in response to inhibitors targeting the Her1/Her2 and PI3K/AKT and MAPK pathways. For comparison we also analyzed NSCLC lines driven by other receptor tyrosine kinases like EGFR and MET. Methods: Lysates prepared from KPL4 cells and MCF7 cells both harboring PIK3CA mutations (with HER2−amplification and low level HER2 expression, respectively) treated with 6 inhibitors (an allosteric AKT inhibitor, Lapatinib, Regorafenib, MET inhibitor, an allosteric MEK inhibitor or PI3K inhibitor) targeting PI3K/AKT and MAPK pathways were analyzed for modulations of pathway protein phosphorylation using a multiplexed immuno-micorarray.

Tissue lysates prepared from KPL4 xenografts treated with AKT inhibitor were analyzed for pathway modulation in response to the drug treatment. The pathway activation profile shift in response to drug treatments in BCA models are compared to other tumor type models with diverse oncogenic backgrounds.

Results: The level of phosphorylated AKT (pAKT) was reduced when MCF7 cells were treated with AKT inhibitor as well as PI3K inhibitor. However, compensatory AKT activation was observed when these cells were treated with BRAF or MEK inhibitor. KPL4 cells also showed reduction of pAKT when treated with Lapatinib, AKT inhibitor or PI3K inhibitor. Compensatory hyper-phosphorylation of ERK (pERK) was observed in both cell lines and KPL4 xenografts with AKT inhibitor treatment while PI3K inhibition did not induce hyper-ERK phosphorylation. Reduction of pERK level was observed when both cell lines were treated with MEK inhibitor. Downstream analytes like PRAS40 and RPS6 summarize PI3K/AKT pathway activity and correlate well with response to treatment whereas eIF4e is a good final readout for activity in the RAS/RAF/MEK/ERK pathway. Treatment with single agents often even shows adverse profile shift through feedback or pathway cross-talk. The comparative analysis of pathway modulation in BCA models to other tumor types in response to drug treatments revealed several adaptive drug resistance mechanism with different oncogenic backgrounds.

Discussion: Evaluation of drug specific pathway modulations in cancer cells provided comprehensive information on efficacy of specific agents on target protein and pathway inhibition. Multiplexed pathway analysis provides valuable information for drug resistance mechanisms due to either redundant pathway activation, cross-talk or through feedback mechanism and may guide appropriate selection of targeted drug-combinations or drug-sequencing in clinical setting. For example, the observed increase in ERK phosphorylation due to AKT inhibition could be blocked by combination therapy with a MEK inhibitor.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-18-04.

A stable IgG-like bispecific antibody targeting the epidermal growth factor receptor and the type I insulin-like growth factor receptor demonstrates superior anti-tumor activity

The epidermal growth factor receptor (EGFR) and the type I insulin-like growth factor receptor (IGF-1R) are two cell surface receptor tyrosine kinases known to cooperate to promote tumor progression and drug resistance. Combined blockade of EGFR and IGF-1R has shown improved anti-tumor activity in preclinical models. Here, we report the characterization of a stable IgG-like bispecific antibody (BsAb) dual-targeting EGFR and IGF-1R that was developed for cancer therapy. The BsAb molecule (EI-04), constructed with a stability-engineered single chain variable fragment (scFv) against IGF-1R attached to the carboxyl-terminus of an IgG against EGFR, displays favorable biophysical properties for biopharmaceutical development. Biochemically, EI-04 bound to human EGFR and IGF-1R with sub nanomolar affinity, co-engaged the two receptors simultaneously, and blocked the binding of their respective ligands with similar potency compared to the parental monoclonal antibodies (mAbs). In tumor cells, EI-04 effectively inhibited EGFR and IGF-1R phosphorylation, and concurrently blocked downstream AKT and ERK activation, resulting in greater inhibition of tumor cell growth and cell cycle progression than the single mAbs. EI-04, likely due to its tetravalent bispecific format, exhibited high avidity binding to BxPC3 tumor cells co-expressing EGFR and IGF-1R, and consequently improved potency at inhibiting IGF-driven cell growth over the mAb combination. Importantly, EI-04 demonstrated enhanced in vivo anti-tumor efficacy over the parental mAbs in two xenograft models, and even over the mAb combination in the BxPC3 model. Our data support the clinical investigation of EI-04 as a superior cancer therapeutic in treating EGFR and IGF-1R pathway responsive tumors.

Stable IgG-like bispecific antibodies directed toward the type I insulin-like growth factor receptor demonstrate enhanced ligand blockade and anti-tumor activity

Bispecific antibodies (BsAbs) target multiple epitopes on the same molecular target or different targets. Although interest in BsAbs has persisted for decades, production of stable and active BsAbs has hindered their clinical evaluation. Here, we describe the production and characterization of tetravalent IgG-like BsAbs that combine the activities of allosteric and competitive inhibitors of the type-I insulin-like growth factor receptor (IGF-1R). The BsAbs, which were engineered for thermal stability, express well, demonstrate favorable biophysical properties, and recognize both epitopes on IGF-1R. Only one BsAb with a unique geometry, denoted BIIB4-5scFv, was capable of engaging all four of its binding arms simultaneously. All the BsAbs (especially BIIB4-5scFv) demonstrated enhanced ligand blocking over the single monoclonal antibodies (mAbs), particularly at high ligand concentrations. The pharmacokinetic profiles of two IgG-like BsAbs were tested in nude mice and shown to be comparable with that of the parental mAbs. The BsAbs, especially BIIB4-5scFv, demonstrated an improved ability to reduce the growth of multiple tumor cell lines and to inhibit ligand-induced IGF-1R signaling in tumor cells over the parental mAbs. BIIB4-5scFv also led to superior tumor growth inhibition over its parental mAbs in vivo. In summary, BsAbs that bridge multiple inhibitory mechanisms against a single target may generally represent a more effective strategy for intervention in oncology or other indications compared with traditional mAb therapy.

Combination of two insulin-like growth factor-I receptor inhibitory antibodies targeting distinct epitopes leads to an enhanced antitumor response

The insulin-like growth factor-I receptor (IGF-IR) is a cell surface receptor tyrosine kinase that mediates cell survival signaling and supports tumor progression in multiple tumor types. We identified a spectrum of inhibitory IGF-IR antibodies with diverse binding epitopes and ligand-blocking properties. By binding distinct inhibitory epitopes, two of these antibodies, BIIB4 and BIIB5, block both IGF-I and IGF-II binding to IGF-IR using competitive and allosteric mechanisms, respectively. Here, we explored the inhibitory effects of combining BIIB4 and BIIB5. In biochemical assays, the combination of BIIB4 and BIIB5 improved both the potency and extent of IGF-I and IGF-II blockade compared with either antibody alone. In tumor cells, the combination of BIIB4 and BIIB5 accelerated IGF-IR downregulation and more efficiently inhibited IGF-IR activation as well as downstream signaling, particularly AKT phosphorylation. In several carcinoma cell lines, the antibody combination more effectively inhibited ligand-driven cell growth than either BIIB4 or BIIB5 alone. Notably, the enhanced tumor growth-inhibitory activity of the BIIB4 and BIIB5 combination was much more pronounced at high ligand concentrations, where the individual antibodies exhibited substantially reduced activity. Compared with single antibodies, the BIIB4 and BIIB5 combination also significantly further enhanced the antitumor activity of the epidermal growth factor receptor inhibitor erlotinib and the mTOR inhibitor rapamycin. Moreover, in osteosarcoma and hepatocellular carcinoma xenograft models, the BIIB4 and BIIB5 combination significantly reduced tumor growth to a greater degree than each single antibody. Taken together, our results suggest that targeting multiple distinct inhibitory epitopes on IGF-IR may be a more effective strategy of affecting the IGF-IR pathway in cancer.

Application of a complete factorial design for the production of zeaxanthin by Flavobacterium sp

Utilizing a four-liter fermentor and applying a complete factorial design 2(3), the combined effects of agitation speed, aeration rate, and corn steep liquor concentration on zeaxanthin production by Flavobacterium sp. were studied. Maximum growth and production of total carotenoids and zeaxanthin were obtained at 600 rpm, 2 vvm and 4.6% corn steep liquor. Under these conditions, zeaxanthin represented 86% of the total carotenoids produced. Lower values of the variables studied resulted in lower growth, volumetric production of zeaxanthin and total carotenoids, and favored the formation of other carotenoids such as beta-carotene and canthaxanthin. The positive effects on growth and total carotenoids and zeaxanthin formation were in a large extent due to the interaction of agitation/corn steep liquor. However, aeration also had a positive effect on growth.

Human SIR2 deacetylates p53 and antagonizes PML/p53-induced cellular senescence

The yeast Sir2 protein mediates chromatin silencing through an intrinsic NAD-dependent histone deacetylase activity. Sir2 is a conserved protein and was recently shown to regulate lifespan extension both in budding yeast and worms. Here, we show that SIRT1, the human Sir2 homolog, is recruited to the promyelocytic leukemia protein (PML) nuclear bodies of mammalian cells upon overexpression of either PML or oncogenic Ras (Ha-rasV12). SIRT1 binds and deacetylates p53, a component of PML nuclear bodies, and it can repress p53-mediated transactivation. Moreover, we show that SIRT1 and p53 co-localize in nuclear bodies upon PML upregulation. When overexpressed in primary mouse embryo fibroblasts (MEFs), SIRT1 antagonizes PML-induced acetylation of p53 and rescues PML-mediated premature cellular senescence. Taken together, our data establish the SIRT1 deacetylase as a novel negative regulator of p53 function capable of modulating cellular senescence.

Rapid purification and biochemical characterization of glucose kinase from Streptomyces peucetius var. caesius

Glucose kinase catalyzes the ATP-dependent phosphorylation of glucose. Streptomyces peucetius var. caesius glucose kinase was purified 292-fold to homogeneity. The enzyme has cytosolic localization and is composed of four identical subunits, each of 31 kDa. The purified enzyme easily dissociates into dimers. However, in the presence of 100 mM glucose the enzyme maintains its tetrameric form. Maximum activity was found at 42 degrees C and pH 7.5. Isoelectric focusing of the enzyme showed a pl of 8.4. The N- and C-terminal amino acid sequences were MGLTIGVD and VYFAREPDPIM, respectively. The kinetic mechanism of S. peucetius var. caesius glucose kinase appears to be a rapid equilibrium ordered type, i.e., ordered addition of substrates to the enzyme, where the first substrate is d-glucose. The K(m) values for d-glucose and MgATP(2-) were 1.6 +/- 0.2 and 0.8 +/- 0.1 mM, respectively. Mg(2+) in excess of 10 mM inhibits enzyme activity.

Differential localization of HDAC4 orchestrates muscle differentiation

The class II histone deacetylases HDAC4 and HDAC5 interact specifically with the myogenic MEF2 transcription factor and repress its activity. Here we show that HDAC4 is cytoplasmic during myoblast differentiation, but relocates to the nucleus once fusion has occurred. Inappropriate nuclear entry of HDAC4 following overexpression suppresses the myogenic programme as well as MEF2-dependent transcription. Activation of the Ca(2+)/calmodulin signalling pathway via constitutively active CaMKIV prevents nuclear entry of HDAC4 and HDAC4-mediated inhibition of differentiation. Consistent with a role of phosphorylation in HDAC4 cytoplasmic localisation, HDAC4 binds to 14-3-3 proteins in a phosphorylation-dependent manner. Together these data establish a role for HDAC4 in muscle differentiation. Recently, HDAC5 has also been implicated in muscle differentiation. However, despite the functional similarities of HDAC4 and HDAC5, their intracellular localisations are opposed, suggesting a distinct role for these enzymes during muscle differentiation.

Purification and characterization of an extracellular lipase from Penicillium candidum

Penicillium candidum produces and secretes a single extracellular lipase with a monomer molecular weight of 29 kDa. However, this enzyme forms dimers and higher molecular weight aggregates under nondenaturing conditions. The lipase from P. candidum was purified 37-fold using Octyl-Sepharose CL-4B and DEAE-Sephadex columns. The optimal assay conditions for lipase activity were 35 degrees C and pH 9. The lipase was stable in the pH range of 5-6 with a pl of 5.5, but rapid loss of the enzyme activity was observed above 25 degrees C. Tributyrin was found to be the best substrate for the P. candidum lipase, among those tested. Metal ions such as Fe2+ and Cu2+ inhibited enzymatic activity and only Ca2+ was able to slightly enhance lipase activity. Ionic detergents inhibited the activity of the enzyme, whereas nonionic detergents stimulated lipase activity.

Constitutive activation of toll-mediated antifungal defense in serpin-deficient Drosophila

The antifungal defense of Drosophila is controlled by the spaetzle/Toll/cactus gene cassette. Here, a loss-of-function mutation in the gene encoding a blood serine protease inhibitor, Spn43Ac, was shown to lead to constitutive expression of the antifungal peptide drosomycin, and this effect was mediated by the spaetzle and Toll gene products. Spaetzle was cleaved by proteolytic enzymes to its active ligand form shortly after immune challenge, and cleaved Spaetzle was constitutively present in Spn43Ac-deficient flies. Hence, Spn43Ac negatively regulates the Toll signaling pathway, and Toll does not function as a pattern recognition receptor in the Drosophila host defense.

HDAC4 deacetylase associates with and represses the MEF2 transcription factor

The acetylation state of histones can influence transcription. Acetylation, carried out by acetyltransferases such as CBP/p300 and P/CAF, is commonly associated with transcriptional stimulation, whereas deacetylation, mediated by the three known human deacetylases HDAC1, 2 and 3, causes transcriptional repression. The known human deacetylases represent a single family and are homologues of the yeast RPD3 deacetylase. Here we identify and characterize HDAC4, a representative of a new human histone deacetylase family, which is homologous to the yeast HDA1 deacetylase. We show that HDAC4, unlike other deacetylases, shuttles between the nucleus and the cytoplasm in a process involving active nuclear export. In the nucleus, HDAC4 associates with the myocyte enhancer factor MEF2A. Binding of HDAC4 to MEF2A results in the repression of MEF2A transcriptional activation, a function that requires the deacetylase domain of HDAC4. These results identify MEF2A as a nuclear target for HDAC4-mediated repression and suggests that compartmentalization may be a novel mechanism for controlling the nuclear activity of this new family of deacetylases.

MEF-2 function is modified by a novel co-repressor, MITR

The MEF-2 proteins are a family of transcriptional activators that have been detected in a wide variety of cell types. In skeletal muscle cells, MEF-2 proteins interact with members of the MyoD family of transcriptional activators to synergistically activate gene expression. Similar interactions with tissue or lineage-specific cofactors may also underlie MEF-2 function in other cell types. In order to screen for such cofactors, we have used a transcriptionally inactive mutant of Xenopus MEF2D in a yeast two-hybrid screen. This approach has identified a novel protein expressed in the early embryo that binds to XMEF2D and XMEF2A. The MEF-2 interacting transcription repressor (MITR) protein binds to the N-terminal MADS/MEF-2 region of the MEF-2 proteins but does not bind to the related Xenopus MADS protein serum response factor. In the early embryo, MITR expression commences at the neurula stage within the mature somites and is subsequently restricted to the myotomal muscle. In functional assays, MITR negatively regulates MEF-2-dependent transcription and we show that this repression is mediated by direct binding of MITR to the histone deacetylase HDAC1. Thus, we propose that MITR acts as a co-repressor, recruiting a specific deacetylase to downregulate MEF-2 activity.

Distinguishing androgen receptor agonists and antagonists: distinct mechanisms of activation by medroxyprogesterone acetate and dihydrotestosterone

Natural and pharmacological androgen receptor (AR) ligands were tested for their ability to induce the AR NH2-terminal and carboxyl-terminal (N/C) interaction in a two-hybrid protein assay to determine whether N/C complex formation distinguishes in vivo AR agonists from antagonists. High-affinity agonists such as dihydrotestosterone, mibolerone, testosterone, and methyltrienolone at concentrations between 0.1 and 1 nM induce the N/C interaction more than 40-fold. The lower affinity anabolic steroids, oxandrolone and fluoxymesterone, require concentrations of 10-100 nM for up to 23-fold induction of the N/C interaction. However no N/C interaction was detected in the presence of the antagonists, hydroxyflutamide, cyproterone acetate, or RU56187, at concentrations up to 1 microM, or with 1 microM estradiol, progesterone, or medroxyprogesterone acetate; each of these steroids at 1-500 nM inhibited the dihydrotestosterone-induced N/C interaction, with medroxyprogesterone acetate being the most effective. In transient and stable cotransfection assays using the mouse mammary tumor virus reporter vector, all ligands displayed concentration-dependent AR agonist activity that paralleled induction of the N/C interaction, with antagonists and weaker agonists failing to induce the N/C interaction. AR dimerization and DNA binding in mobility shift assays and AR stabilization reflected, but were not dependent on, the N/C interaction. The results indicate that the N/C interaction facilitates agonist potency at low physiological ligand concentrations as detected in transcription, dimerization/DNA binding, and stabilization assays. However the N/C interaction is not required for agonist activity at sufficiently high ligand concentrations, nor does its inhibition imply antagonist activity.

Intermolecular NH2-/carboxyl-terminal interactions in androgen receptor dimerization revealed by mutations that cause androgen insensitivity

Structural alignment of the human androgen receptor dimer was investigated by introducing steroid binding domain mutations that cause partial or complete androgen insensitivity into fusion proteins containing the full-length androgen receptor or the steroid binding domain. Most of the mutants had unchanged apparent equilibrium androgen binding affinity and increased dissociation rates of [3H]methyltrienolone and required increased dihydrotestosterone concentrations for transcriptional activation. In a 2-hybrid protein interaction assay in mammalian cells, the steroid binding domain interacts with an NH2-terminal-DNA binding domain fragment and with the full-length androgen receptor at physiological androgen concentrations in a dose-dependent manner. However, mutations at Val-889 and Arg-752 disrupt the NH2-/carboxyl-terminal interaction when introduced into the steroid binding domain fragment but not when present in the full-length androgen receptor. The N-C bimolecular interaction reduces the dissociation rate of bound androgen and slows the degradation rate of the carboxyl-terminal steroid binding domain fragment. The results suggest that steroid binding domain residues Val-889 and Arg-752 are critical to the NH2-/carboxyl-terminal interaction and that an intermolecular N-C interaction occurs during receptor dimerization that results in an antiparallel arrangement of androgen receptor monomers.

Evidence for an anti-parallel orientation of the ligand-activated human androgen receptor dimer

Domain interactions of the human androgen receptor (AR) dimer were investigated using a protein-protein interaction assay in which the NH2- and carboxyl-terminal regions of human AR were fused to the Saccharomyces cerevisiae GAL4 DNA-binding domain and herpes simplex virus VP16 transactivation domain to produce chimeric proteins. Transcriptional activation of a GAL4 luciferase reporter vector up to 100-fold was greater than Fos/Jun leucine zipper binding, indicating stable AR interaction between AR NH2-terminal residues 1-503 and steroid-binding domain residues 624-919 that was specific for and dependent on androgen binding to the steroid-binding domain and was inhibited by anti-androgen binding. Deletion mutagenesis within the NH2-terminal region indicated transactivation domain residues 142-337 were not required for dimerization, whereas deletions near the NH2 terminus (delta 14-150) or NH2-terminal to the DNA-binding domain (delta 339-499) reduced or eliminated the AR interaction, respectively. An NH2-/NH2-terminal interaction was also observed, but no interaction was detected between ligand-free or bound steroid-binding domains. The results indicate that high affinity androgen binding promotes interactions between the NH2-terminal and steroid-binding domains of human AR, raising the possibility of an androgen-induced anti-parallel AR dimer.

Drosophila immunity. A sequence homologous to mammalian interferon consensus response element enhances the activity of the diptericin promoter

Bacterial challenge of larvae or adults of Drosophila induces the rapid transcription of several genes encoding antibacterial peptides with a large spectrum of activity. One of these peptides, the 82-residue anti-gram negative diptericin, is encoded by a single intronless gene and we are investigating the control of expression of this gene. Previous studies using both transgenic experiments and footprint analysis have highlighted the role in the induction of this gene of a 30 nucleotide region which contains three partially overlapping motifs with sequence homology to mammalian NF-kappa B and NF-IL6 response elements and to the GAAANN sequence present in the interferon consensus response elements of some mammalian interferon-induced genes. We now show that the latter sequence binds in immune responsive tissues (fat body, blood cells) of Drosophila a approximately 45 kDa polypeptide which cross-reacts with a polyserum directed against mammalian interferon Regulatory Factor-I. Using a transfection assay of Drosophila tumorous blood cells, we show that the GAAANN sequence positively regulates the activity of the diptericin promoter. We propose that this motif cooperatively interacts with the other response elements in the regulation of the diptericin gene expression.

Hormone-dependent transactivation by the human androgen receptor is regulated by a dnaJ protein

Genetic studies were performed to examine the role of eukaryotic dnaJ protein, Ydj1p, in the regulated activation of human androgen receptor (hAR) after heterologous expression in Saccharomyces cerevisiae. Hormone-dependent activation of hAR was measured as a function of lacZ reporter gene expression, which was defective in ydj1-151 and ydj1-2 delta null mutant strains compared to the wild type. This defect was not due to receptor misfolding, since hAR in both wild type and mutant strains had a similar capacity to bind hormone. The target for Ydj1p action was determined to be the hAR hormone binding domain since an N-terminal fragment lacking this region was constitutively active in both wild type and ydj1-151 mutant strains. These data correlate hormone dependence of hAR activation with a requirement for Ydj1p function and are consistent with a role for dnaJ proteins in signal transduction by steroid hormone receptors.

Endometrial expression of progesterone receptor and uteroglobin genes during early pregnancy in the rabbit

The progesterone receptor (PR) plays a pivotal role in the maturation process of the secretory endometrium, implantation and maintenance of pregnancy in rabbits. To determine the dynamics of PR gene expression and its physiological significance, the endometrial expression of PR and PR mRNA were evaluated and compared with the expression of the progesterone-regulated uteroglobin (UG) gene during 0-5 days post-coitus in rabbits. The results of immunoblot experiments indicated the presence of PR in endometrial cell extracts from days 1-4 of pregnancy with maximum PR immunostaining on day 2, followed by a marked diminution until its complete disappearance on day 5. When endometrial PR mRNA content was assessed by Northern blots, the results were similar to those of PR immunostaining, with maximal concentrations on the second day after mating. However, PR mRNA levels were still high on day 3, despite the concomitant decrease in immunostainable PR. Endometrial UG gene expression, on the other hand, exhibited a different time sequence. Thus, the UG content in uterine flushings progressively increased from day 3 after mating, reaching maximal levels on the fifth day. The endometrial UG mRNA content presented a similar profile, as its maximum concentration occurred on days 4-5. The overall results indicate that endometrial PR is down-regulated at both the mRNA and protein levels, possibly by endogenous progesterone during early pregnancy. The striking observation that maximal expression of endometrial UG gene products occurred when PR and its mRNA are no longer detectable suggests an important role for this progesterone-binding uterine protein during the preimplantation period.