Manipulating the p53 pathway for cancer treatment

p53 is a tumour suppressor that is dysfunctional in most cancers. In some cancers, mutation of the TP53 gene results in expression of a mutant protein or loss of p53 expression, while in others wild-type p53 is retained but there is a defect in the mechanisms that allow for the activation of p53, including, but not limited to, upregulation of p53’s negative regulators (MDM2 and MDMX). Restoration of wild-type p53 function can lead to tumour regression and is therefore an attractive anti-cancer therapy. Several small molecule compounds that activate wild-type p53 have been described, and in this study the functions of two new compounds that stabilise p53 are described. While these drugs may be useful to activate p53-dependent apoptosis or senescence in wild-type p53 tumours, an alternative approach that depends on the use of transient p53 activation to protect normal cells while leaving p53 null or mutant tumour cells vulnerable to cytotoxic drugs is also explored. Finally, the identification of pharmacodynamic biomarkers for p53 stabilisation is described. In chapter 3 a new class of MDM2 inhibitor (MPD compounds) is described. The compounds are capable of stabilising and activating p53 in cells by inhibiting the E3 ligase activity of MDM2 in a mechanism that involves compound binding to the RING-tail of MDM2. Although the MPD compounds have limitations in terms of solubility and potency they have demonstrated a new method of achieving MDM2 inhibition and support design of further RING-tail binding compounds with more favourable chemical properties. In chapter 4 the function of a dual inhibitor of MDM2 and MDMX has been explored (HLI373). This compound is shown to activate p53 in cells and in vivo by interfering with ribosomal biogenesis, causing ribosomal stress and inhibiting MDM2. In addition it is capable of reducing MDMX expression at the promoter level by a mechanism that requires intact MDM2-p53 binding. Further work is required to fully define the mechanism of action of this compound and demonstrate its anticancer activity in xenograft and transgenic mouse models. In chapter 5 a chemoprotective approach for p53 activation, which might be applied to situations where tumours express mutant p53, is explored in cell lines. Low-dose actinomycin D treatment can activate p53 without occult DNA damage via the ribosomal stress pathway, thereby protecting wild-type p53 expressing cells from the cytotoxic effects of paclitaxel. Low-dose actinomycin D may therefore be used to limit chemotherapy-induced toxicity to normal cells while targeting a mutant p53 expressing tumour. In chapter 6 the potential for developing pharmacodynamic biomarkers for MDM2 inhibition in serum, peripheral blood mononuclear cells and hair follicles taken from patients prior to and following chemotherapy was examined. Measurement of serum MIC-1 level showed most promise, although further evaluation of this marker is needed before it could be used as a pharmacodynamic endpoint in a clinical study

iRFP is a real time marker for transformation based assays in high content screening

Anchorage independent growth is one of the hallmarks of oncogenic transformation. Here we show that infrared fluorescent protein (iRFP) based assays allow accurate and unbiased determination of colony formation and anchorage independent growth over time. This protocol is particularly compatible with high throughput systems, in contrast to traditional methods which are often labor-intensive, subjective to bias and do not allow further analysis using the same cells. Transformation in a single layer soft agar assay could be documented as early as 2 to 3 days in a 96 well format, which can be easily combined with standard transfection, infection and compound screening setups to allow for high throughput screening to identify therapeutic targets

5-deazaflavin derivatives as inhibitors of p53 ubiquitination by HDM2

Based on previous reports of certain 5-deazaflavin derivatives being capable of activating the tumour suppressor p53 in cancer cells through inhibition of the p53-specific ubiquitin E3 ligase HDM2, we have conducted an structure–activity relationship (SAR) analysis through systematic modification of the 5-deazaflavin template. This analysis shows that HDM2-inhibitory activity depends on a combination of factors. The most active compounds (e.g., 15) contain a trifluoromethyl or chloro substituent at the deazaflavin C9 position and this activity depends to a large extent on the presence of at least one additional halogen or methyl substituent of the phenyl group at N10. Our SAR results, in combination with the HDM2 RING domain receptor recognition model we present, form the basis for the design of drug-like and potent activators of p53 for potential cancer therapy

The Role of Gender on the Associations Among Children’s Attitudes, Mathematics Knowledge, Digital Game Use, Perceptions of Affordances, and Achievement

This study explored associations among children’s prior attitudes, prior mathematics knowledge, and frequency of digital game use, with children’s perceptions of game affordances, and transfer to out-of-game performance when interacting with digital math games, with respect to gender. Participants were 187 children (ages 8–12). An SEM mediation path analysis using MPLUS software showed significant direct effects for all pathways for all children, and significant indirect effects on all pathways for male children and five of six pathways for female children. More favorable attitudes, prior math knowledge, and perception of the helping affordances were associated with increased posttest performance, while increased frequency of digital game use and stronger perception of the hindering affordances was associated with decreased posttest performance. The model showed stronger connections for male children between frequency of digital game use, prior mathematics knowledge, and hindering affordances to the posttest, while female children showed stronger connections between attitude and perception of helping affordances to the posttest

A phase 1 study of intravenous and oral rucaparib in combination with chemotherapy in patients with advanced solid tumors.

Background: This study evaluated safety, pharmacokinetics, and clinical activity of intravenous and oral rucaparib, a poly(ADP-ribose) polymerase inhibitor, combined with chemotherapy in patients with advanced solid tumours. Methods: Initially, patients received escalating doses of intravenous rucaparib combined with carboplatin, carboplatin/paclitaxel, cisplatin/pemetrexed, or epirubicin/cyclophosphamide. Subsequently, the study was amended to focus on oral rucaparib (once daily, days 1–14) combined with carboplatin (day 1) in 21-day cycles. Dose-limiting toxicities (DLTs) were assessed in cycle 1 and safety in all cycles. Results: Eighty-five patients were enrolled (22 breast, 15 ovarian/peritoneal, and 48 other primary cancers), with a median of three prior therapies (range, 1–7). Neutropenia (27.1%) and thrombocytopenia (18.8%) were the most common grade greater than or equal to3 toxicities across combinations and were DLTs with the oral rucaparib/carboplatin combination. Maximum tolerated dose for the combination was 240 mg per day oral rucaparib and carboplatin area under the curve 5 mg ml−1 min−1. Oral rucaparib demonstrated dose-proportional kinetics, a long half-life (≈17 h), and good bioavailability (36%). Pharmacokinetics were unchanged by carboplatin coadministration. The rucaparib/carboplatin combination had radiologic antitumour activity, primarily in BRCA1- or BRCA2-mutated breast and ovarian/peritoneal cancers. Conclusions: Oral rucaparib can be safely combined with a clinically relevant dose of carboplatin in patients with advanced solid tumours (Trial registration ID: NCT01009190)

The context, influences and challenges for undergraduate nurse clinical education: Continuing the dialogue

Introduction – Approaches to clinical education are highly diverse and becoming increasingly complex to sustain in complex milieu Objective – To identify the influences and challenges of providing nurse clinical education in the undergraduate setting and to illustrate emerging solutions. Method: A discursive exploration into the broad and varied body of evidence including peer reviewed and grey literature. Discussion - Internationally, enabling undergraduate clinical learning opportunities faces a range of challenges. These can be illustrated under two broad themes: (1) Legacies from the past and the inherent features of nurse education and (2) Challenges of the present, including, population changes, workforce changes, and the disconnection between the health and education sectors. Responses to these challenges are triggering the emergence of novel approaches, such as collaborative models. Conclusion(s) – Ongoing challenges in providing accessible, effective and quality clinical learning experiences are apparent

How Design Features in Digital Math Games Support Learning and Mathematics Connections

Current research shows that digital games can significantly enhance children’s learning. The purpose of this study was to examine how design features in 12 digital math games influenced children’s learning. The participants in this study were 193 children in Grades 2 through 6 (ages 8-12). During clinical interviews, children in the study completed pre-tests, interacted with digital math games, responded to questions about the digital math games, and completed post-tests. We recorded the interactions using two video perspectives that recorded children’s gameplay and responses to interviewers. We employed mixed methods to analyze the data and identify salient patterns in children’s experiences with the digital math games. The analysis revealed significant gains for 9 of the 12 digital games and most children were aware of the design features in the games. There were eight prominent categories of design features in the video data that supported learning and mathematics connections. Six categories focused on how the design features supported learning in the digital games. These categories included: accuracy feedback, unlimited/multiple attempts, information tutorials and hints, focused constraint, progressive levels, and game efficiency. Two categories were more specific to embodied cognition and action with the mathematics, and focused on how design features promoted mathematics connections. These categories included: linked representations and linked physical actions. The digital games in this study that did not include linked representations and opportunities for linked physical actions as design features did not produce significant gains. These results suggest the key role of mathematics-specific design features in the design of digital math games

A Phase I/II trial of Oral SRA737 (a Chk1 Inhibitor) given in combination with low-dose gemcitabine in patients with advanced cancer

Purpose: This was a phase I/II trial of the novel checkpoint kinase 1 (Chk1) inhibitor SRA737 given in combination with gemcitabine. Its objectives were to establish the safety profile, recommended phase 2 dose (RP2D), pharmacokinetics profile, and clinical activity of SRA737. Patients and Methods: Patients with advanced solid tumors were enrolled into dose-escalation cohorts and treated in 28-day cycles with oral SRA737 on days 2, 3, 9, 10, 16 and 17, and intravenous gemcitabine on days 1, 8 and 15. Treatment was continued until progression. Each expansion cohort included up to 20 patients with specific genetically defined tumors. Results: The RP2D was determined to be 500 mg SRA737 combined with low-dose (250 mg/m2) gemcitabine. Of 143 enrolled patients, 77 were treated at doses of at least 500 mg SRA737 combined with 250 mg/m2 gemcitabine. Common toxicities of nausea, vomiting, fatigue and diarrhea were primarily mild to moderate, and rarely led to treatment discontinuation. Anemia, neutropenia and thrombocytopenia were grade ≥3 in 8.3% to 11.7% of patients treated at the RP2D. The objective response rate (ORR) was 10.8% overall and notably the ORR in anogenital cancer was 25%. Partial tumor responses were observed in anogenital cancer, cervical cancer, high-grade serous ovarian cancer, rectal cancer, and small cell lung cancer. Conclusions: SRA737 in combination with low-dose gemcitabine was well tolerated with lower myelotoxicity than has been seen at standard doses of gemcitabine or with other combinations of Chk1 inhibitors with gemcitabine. Tumor responses were observed in anogenital and other solid tumors

Polydrug Use among IDUs in Tijuana, Mexico: Correlates of Methamphetamine Use and Route of Administration by Gender

Tijuana is situated on the Mexico–USA border adjacent to San Diego, CA, on a major drug trafficking route. Increased methamphetamine trafficking in recent years has created a local consumption market. We examined factors associated with methamphetamine use and routes of administration by gender among injection drug users (IDUs). From 2006–2007, IDUs ≥18 years old in Tijuana were recruited using respondent-driven sampling, interviewed, and tested for HIV, syphilis, and TB. Logistic regression was used to assess associations with methamphetamine use (past 6 months), stratified by gender. Among 1,056 participants, methamphetamine use was more commonly reported among females compared to males (80% vs. 68%, p < 0.01), particularly, methamphetamine smoking (57% vs. 34%; p < 0.01). Among females (N = 158), being aged >35 years (AOR, 0.2; 95% CI, 0.1–0.6) was associated with methamphetamine use. Among males (N = 898), being aged >35 years (AOR, 0.5; 95% CI, 0.3–0.6), homeless (AOR, 1.4 (0.9–2.2)), and ever reporting sex with another male (MSM; AOR, 1.9; 95% CI, 1.4–2.7) were associated with methamphetamine use. Among males, a history of MSM was associated with injection, while sex trade and >2 casual sex partners were associated with multiple routes of administration. HIV was higher among both males and females reporting injection as the only route of methamphetamine administration. Methamphetamine use is highly prevalent among IDUs in Tijuana, especially among females. Routes of administration differed by gender and subgroup which has important implications for tailoring harm reduction interventions and drug abuse treatment