Expression of the novel all-trans retinoic acid-related resistance gene HA117 in pediatric solid tumors

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Retinoic acid-induced survival effects in SH-SY5Y neuroblastoma cells

Neuroblastoma is a malignant childhood cancer arising from the embryonic sympathoadrenal lineage of the neural crest. Retinoic acid (RA) is included in the multimodal therapy of patients with high-risk neuroblastoma to eliminate minimal residual disease. However, the formation of RA-resistant cells substantially lowers 5-year overall survival rates. To examine mechanisms that lead to treatment failure, we chose human SH-SY5Y cells, which are known to tolerate incubation with RA by activating the survival kinases Akt and extracellular signal-regulated kinase 1/2. Characterization of downstream pathways showed that both kinases increased the phosphorylation of the ubiquitin ligase mouse double minute homolog 2 (Mdm2) and thereby enhanced p53 degradation. When p53 signaling was sustained by blocking complex formation with Mdm2 or enhancing c-Jun N-terminal kinase (JNK) activation, cell viability was significantly reduced. In addition, Akt-mediated phosphorylation of the cell-cycle regulator p21 stimulated complex formation with caspase-3, which also contributed to cell protection. Thus, treatment with RA augmented survival signaling and attenuated basal apoptotic pathways in SH-SY5Y cells, which increased cell viability.

Potential association of long noncoding RNA HA117 with tetralogy of Fallot

Tetralogy of Fallot (TOF) is a congenital heart disease characterized by abnormal cardiomyocyte differentiation in the right ventricular outflow tract (RVOT), and HA117 is a novel long noncoding RNA (lncRNA) with anti-differentiation roles. To investigate the potential association of HA117 with TOF, we collected 84 RVOT tissues from patients with TOF. We determined the expression of HA117 in RVOT samples from TOF patients and collected clinical data to conduct a cross-sectional and short-term follow-up study. McGoon ratio, Nakata index, and left ventricular end-diastolic volume index (LVEDVI) were negatively correlated with the expression of HA117 based on subgroup analysis, correlation analysis and logistic regression analysis. Additionally, cardiopulmonary bypass (CPB) time and ICU stay were longer in patients with higher expression of HA117 than in patients with lower expression of HA117. Furthermore, percentage improvement in SPO₂ was significantly reduced in patients with increased HA117 expression at 6 months after surgery. Our results suggested that the increased expression of the novel lncRNA HA117 is a risk factor for unfavorable McGoon ratio, Nakata index and LVEDVI in TOF patients. Additionally, an increased expression of HA117 might lead to adverse short-term outcomes in TOF patients.

HA117 endows HL60 cells with a stem-like signature by inhibiting the degradation of DNMT1 via its ability to down-regulate expression of the GGL domain of RGS6

All-trans retinoic acid (ATRA) induces complete remission in almost all patients with acute promyelocytic leukemia (APL) via its ability to induce the in vivo differentiation of APL blasts. However, prolonged ATRA treatment can result in drug resistance. In previous studies, we generated a multi-drug-resistant HL60/ATRA cell line and found it to contain a new drug resistance-related gene segment, HA117. In this study, we demonstrate that ATRA induces multi-drug-resistant subpopulations of HL60 cells with a putative stem-like signature by up-regulating the expression of the new gene segment HA117. Western blot analysis and quantitative real-time PCR demonstrated that HA117 causes alternative splicing of regulator of G-protein signaling 6 (RGS6) and down-regulation of the expression of the GGL domain of RGS6, which plays an important role in DNA methyltransferase 1 (DNMT1) degradation. Moreover, DNMT1 expression was increased in multi-drug resistance HL60/ATRA cells. Knockdown of HA117 restored expression of the GGL domain and blocked DNMT1 expression. Moreover, resistant cells displayed a putative stem-like signature with increased expression of cancer steam cell markers CD133 and CD123. The stem cell marker, Nanog, was significantly up-regulated. In conclusion, our study shows that HA117 potentially promotes the stem-like signature of the HL60/ATRA cell line by inhibiting by the ubiquitination and degradation of DNMT1 and by down-regulating the expression of the GGL domain of RGS6. These results throw light on the cellular events associated with the ATRA-induced multi-drug resistance phenotype in acute leukemia.

Translational Research in Pediatrics IV: Solid Tissue Collection and Processing

Solid tissues are critical for child-health research. Specimens are commonly obtained at the time of biopsy/surgery or postmortem. Research tissues can also be obtained at the time of organ retrieval for donation or from tissue that would otherwise have been discarded. Navigating the ethics of solid tissue collection from children is challenging, and optimal handling practices are imperative to maximize tissue quality. Fresh biopsy/surgical specimens can be affected by a variety of factors, including age, gender, BMI, relative humidity, freeze/thaw steps, and tissue fixation solutions. Postmortem tissues are also vulnerable to agonal factors, body storage temperature, and postmortem intervals. Nonoptimal tissue handling practices result in nucleotide degradation, decreased protein stability, artificial posttranslational protein modifications, and altered lipid concentrations. Tissue pH and tryptophan levels are 2 methods to judge the quality of solid tissue collected for research purposes; however, the RNA integrity number, together with analyses of housekeeping genes, is the new standard. A comprehensive clinical data set accompanying all tissue samples is imperative. In this review, we examined: the ethical standards relating to solid tissue procurement from children; potential sources of solid tissues; optimal practices for solid tissue processing, handling, and storage; and reliable markers of solid tissue quality.

High-dose chemotherapy combined with autologous peripheral blood stem cell transplantation in children with advanced malignant solid tumors: A retrospective analysis of 38 cases

The aim of the present study was to assess the toxicity and efficacy of autologous peripheral blood stem cell (APBSC) transplantation in children with advanced malignant solid tumors. The outcomes of 38 children with advanced malignant solid tumor, who were treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation in Beijing Tongren Hospital (Capital Medical University, Beijing, China) between September 2005 and November 2011, were retrospectively analyzed. The effects of treatment were evaluated according to the standard Bearman's criteria. The mean count of collected mononuclear cells and the cluster of differentiation 34⁺ cell count from 38 patients was 5.6±2.2×10⁸/kg and 3.8±2.6×10⁶/kg, respectively. From these 38 patients, the number of stem cells collected from 31 cases (81.6%) accorded with the transplantation standards. Three and 14 days after pretreatment in these 38 cases, there were 19 cases of grade I, 11 cases of grade II, five cases of grade III and three cases of grade IV (one case succumbed) adverse reaction. Following the treatment (23-40 days after pretreatment, during organ injury recovery), 37 cases obtained bone marrow reconstitution with a mean time of 12.3±3.1 days after APBSC reinfusion. The median survival time of the 37 patients was 49 months, and the survival rate at one, three and five years post-treatment was 91.9, 68.2 and 36.6%, respectively.