How MicroRNAs Command the Battle against Cancer.

MicroRNAs (miRNAs) are small RNA molecules that regulate more than 30% of genes in humans. Recent studies have revealed that miRNAs play a crucial role in tumorigenesis. Large sets of miRNAs in human tumors are under-expressed compared to normal tissues. Furthermore, experiments have shown that interference with miRNA processing enhances tumorigenesis. Multiple studies have documented the causal role of miRNAs in cancer, and miRNA-based anticancer therapies are currently being developed. This review primarily focuses on two key points: (1) miRNAs and their role in human cancer and (2) the regulation of tumor suppressors by miRNAs. The review discusses (a) the regulation of the tumor suppressor p53 by miRNA, (b) the critical role of the miR-144/451 cluster in regulating the Itch-p63-Ago2 pathway, and (c) the regulation of PTEN by miRNAs. Future research and the perspectives of miRNA in cancer are also discussed. Understanding these pathways will open avenues for therapeutic interventions targeting miRNA regulation.

The SWIB/MDM2 motif of UBE4B activates the p53 pathway.

The tumor suppressor p53 plays a critical role in cancer pathogenesis, and regulation of p53 expression is essential for maintaining normal cell growth. UBE4B is an E3/E4 ubiquitin ligase involved in a negative-feedback loop with p53. UBE4B is required for Hdm2-mediated p53 polyubiquitination and degradation. Thus, targeting the p53-UBE4B interactions is a promising anticancer strategy for cancer therapy. In this study, we confirm that while the UBE4B U box does not bind to p53, it is essential for the degradation of p53 and acts in a dominant-negative manner, thereby stabilizing p53. C-terminal UBE4B mutants lose their ability to degrade p53. Notably, we identified one SWIB/Hdm2 motif of UBE4B that is vital for p53 binding. Furthermore, the novel UBE4B peptide activates p53 functions, including p53-dependent transactivation and growth inhibition, by blocking the p53-UBE4B interactions. Our findings indicate that targeting the p53-UBE4B interaction presents a novel approach for p53 activation therapy in cancer.

p63, a key regulator of Ago2, links to the microRNA-144 cluster.

As a key component of the RNA-induced silencing complex (RISC), Argonaute2 (Ago2) exhibits a dual function regulatory role in tumor progression. However, the mechanistic basis of differential regulation remains elusive. p63 is a homolog of the tumor suppressor p53. p63 isoforms play a critical role in tumorigenesis and metastasis. Herein, we show that p63 isoforms physically interact with and stabilize Ago2. Expression of p63 isoforms increases the levels of Ago2 protein, while depletion of p63 isoforms by shRNA decreases Ago2 protein levels. p63 strongly guides Ago2 dual functions in vitro and in vivo. Ectopic expression of the miR-144/451 cluster increases p63 protein levels; TAp63 transactivates the miR-144/451 cluster, forming a positive feedback loop. Notably, miR-144 activates p63 by directly targeting Itch, an E3 ligase of p63. Ectopic expression of miR-144 induces apoptosis in H1299 cells. miR-144 enhances TAp63 tumor suppressor function and inhibits cell invasion. Our findings uncover a novel function of p63 linking the miRNA-144 cluster and the Ago2 pathway. FACTS AND QUESTIONS: Identification of Ago2 as a p63 target. Ago2 exhibits a dual function regulatory role in tumor progression; however, the molecular mechanism of Ago2 regulation remains unknown. p63 strongly guides Ago2 dual functions in vitro and in vivo. Unraveling a novel function of p63 links the miRNA-144 cluster and the Ago2 pathway.

Hsp70 acts as a fine-switch that controls E3 ligase CHIP-mediated TAp63 and ΔNp63 ubiquitination and degradation.

The major clinical problem in human cancer is metastasis. Metastases are the cause of 90% of human cancer deaths. TAp63 is a critical suppressor of tumorigenesis and metastasis. ΔNp63 acts as a dominant-negative inhibitor to block the function of p53 and TAp63. Although several ubiquitin E3 ligases have been reported to regulate p63 stability, the mechanism of p63 regulation remains partially understood. Herein, we show that CHIP, an E3 ligase with a U-box domain, physically interacts with p63 and promotes p63 degradation. Notably, Hsp70 depletion by siRNA stabilizes TAp63 in H1299 cells and destabilizes ΔNp63 in SCC9 cells. Loss of Hsp70 results in a reduction in the TAp63-CHIP interaction in H1299 cells and an increase in the interaction between ΔNp63 and CHIP in SCC9 cells. Our results reveal that Hsp70 acts as a molecular switch to control CHIP-mediated ubiquitination and degradation of p63 isoforms. Furthermore, regulation of p63 by the Hsp70-CHIP axis contributes to the migration and invasion of tumor cells. Hence, our findings demonstrate that Hsp70 is a crucial regulator of CHIP-mediated ubiquitination and degradation of p63 isoforms and identify a new pathway for maintaining TAp63 or ΔNp63 stability in cancers.

Pirh2, an E3 ligase, regulates the AIP4-p73 regulatory pathway by modulating AIP4 expression and ubiquitination.

Pirh2 is an E3 ligase belonging to the RING-H2 family and shown to bind, ubiquitinate and downregulate p73 tumor suppressor function without altering p73 protein levels. AIP4, an E3 ligase belonging to the HECT domain family, has been reported to be a negative regulatory protein that promotes p73 ubiquitination and degradation. Herein, we found that Pirh2 is a key regulator of AIP4 that inhibits p73 function. Pirh2 physically interacts with AIP4 and significantly downregulates AIP4 expression. This downregulation is shown to involve the ubiquitination of AIP4 by Pirh2. Importantly, we demonstrated that the ectopic expression of Pirh2 inhibits the AIP4-p73 negative regulatory pathway, which was restored when depleting endogenous Pirh2 utilizing Pirh2-siRNAs. We further observed that Pirh2 decreases AIP4-mediated p73 ubiquitination. At the translational level and specifically regarding p73 cell cycle arrest function, Pirh2 still ensures the arrest of p73-mediated G1 despite AIP4 expression. Our study reveals a novel link between two E3 ligases previously thought to be unrelated in regulating the same effector substrate, p73. These findings open a gateway to explain how E3 ligases differentiate between regulating multiple substrates that may belong to the same family of proteins, as it is the case for the p53 and p73 proteins.

Preparing Leaders in Maternal-Child Health Nursing.

OBJECTIVE: To describe leadership and patient outcomes from an international leadership development program undertaken by a nursing organization (Sigma Theta Tau International Honor Society of Nursing) in partnership with Johnson & Johnson Corporate Contributions to strengthen the leadership base of maternal-child bedside nurses. DESIGN: Pretest/posttest design with no control group program evaluation. SETTING: Health care facilities, academic institutions, and public health clinics. PARTICIPANTS: Mentor/fellow dyads (N = 100) of the Maternal-Child Health Nurse Leadership Academy (MCHNLA). INTERVENTION/MEASUREMENTS: The MCHNLA engaged participants in an 18-month mentored leadership experience within the context of an interdisciplinary team project. Each mentor/fellow dyad was paired with a faculty member during the program. RESULTS: One hundred dyads have participated and conducted projects to improve health care for childbearing women and children up to age 5 years during the past decade. For the two cohorts for which consistent data were obtained, mentors and fellows enhanced leadership knowledge, skills, and behaviors. Review of 2010 to 2011 cohort project reports revealed they had the potential to influence more than 1000 students, 4000 nurses, and 1300 other health care students or professionals during the project period. CONCLUSIONS: This leadership development model is replicable in other areas of nursing and other professions.

Family child care providers' compliance with state physical activity regulations, Delaware Child Care Provider Survey, 2011.

INTRODUCTION: Delaware is one state that has implemented comprehensive child care regulations to foster healthy dietary and physical activity behaviors of young children. This study describes the Delaware family child care environment and providers' knowledge of and compliance with physical activity regulations. We analyzed the data to determine characteristics associated with predictors of knowledge of and compliance with these regulations. METHODS: A random stratified sample of 663 licensed Delaware family child care providers was mailed a survey on family child care characteristics and providers' awareness and practices of the child care regulations. Three logistic regression models were used to explore the association between provider characteristics and their knowledge of and compliance with the regulations. RESULTS: Ultimately, 313 of the 663 eligible family child care providers participated in the survey (47.2% response rate). Controlling for covariates, we found that family child care providers' education level was significantly associated with knowledge of the physical activity regulation. Another model showed that family child care providers with larger amounts of outdoor space were more likely to report compliance with the recommendation for unstructured physical activity than those without this described space (odds ratio, 2.45). A third model showed a significant association between available indoor space for all activities including running and reported greater compliance with the recommendation for structured physical activity than was reported by caregivers with less indoor space (odds ratio, 11.2). CONCLUSION: To provide the recommended levels of physical activity for children in child care, the available physical space environment is an important area of focus for advocates of physical activity recommendations within the family child care environment.

Consistency of compliance with nutrition-related regulations among Delaware child care centers.

BACKGROUND: As more calls are made in the literature for nutrition interventions to be delivered in child care settings, research on the implementation of these interventions becomes more important. This study examined compliance with Delaware's regulations related to nutrition in child care settings, which are designed to improve the nutrition-related environment in these settings. METHODS: A stratified random sample of licensed child care centers (n=233) was created from the total population of eligible centers in Delaware (N=450). Study staff visited each center and distributed self-administered surveys to the director and two randomly selected teachers. Surveys contained items about classroom-level compliance with the regulations along with center-level characteristics. Bivariate analyses were conducted to explore relationships between consistent compliance with each regulation component and center-level characteristics. RESULTS: A total of 179 of the 233 centers in the selected sample participated in the study. Compliance with the regulations varied within centers and across components; the highest levels of consistent compliance were reported for juice type (88.3%) and the lowest levels for whole grains (18.6%). Center characteristics, such as participation in the Child and Adult Care Food Program, were associated with consistent compliance for certain regulations components. CONCLUSIONS: Our results suggest that these types of regulations can be implemented across a diversity of centers, but that certain components (e.g., those relating to whole grains and water) may need further clarification. Our results also suggest that there are certain types of centers on which to focus training efforts to maximize compliance.