UAB30, a novel RXR agonist, decreases tumorigenesis and leptomeningeal disease in group 3 medulloblastoma patient-derived xenografts.

BACKGROUND: Group 3 tumors account for approximately 25-30% of medulloblastomas and have the worst prognosis. UAB30 is a novel synthetic rexinoid shown to have limited toxicities in humans and significant efficacy in the pediatric neuroectodermal tumor, neuroblastoma. We hypothesized that treatment with UAB30 would decrease tumorigenicity in medulloblastoma patient-derived xenografts (PDXs). METHODS: Three group 3 medulloblastoma PDXs (D341, D384 and D425) were utilized. Cell viability, proliferation, migration and invasion assays were performed after treatment with UAB30 or 13-cis-retinoic acid (RA). Cell cycle analysis was completed using flow cytometry. A flank model, a cerebellar model, and a model of leptomeningeal metastasis using human medulloblastoma PDX cells was used to assess the in vivo effects of UAB30 and RA. RESULTS: UAB30 treatment led to cell differentiation and decreased medulloblastoma PDX cell viability, proliferation, migration and invasion and G1 cell cycle arrest in all three PDXs similar to RA. UAB30 and RA treatment of mice bearing medulloblastoma PDX tumors resulted in a significant decrease in tumor growth and metastasis compared to vehicle treated animals. CONCLUSIONS: UAB30 decreased viability, proliferation, and motility in group 3 medulloblastoma PDX cells and significantly decreased tumor growth in vivo in a fashion similar to RA, suggesting that further investigations into the potential therapeutic application of UAB30 for medulloblastoma are warranted.

Disparities in fertility-sparing surgery in adolescent and young women with stage I ovarian dysgerminoma.

BACKGROUND: In many cancers, racial and socioeconomic disparities exist regarding the extent of surgery. For ovarian dysgerminoma, fertility-sparing (FS) surgery is recommended whenever possible. The aim of this study was to investigate rates of FS versus non-fertility-sparing (NFS) procedures for stage I ovarian dysgerminoma in adolescents and young adults (AYAs) by ethnicity/race and socioeconomic status. MATERIALS AND METHODS: The National Cancer Data Base was queried for patients with ovarian dysgerminoma from 1998 to 2012. After selecting patients aged 15-39 y with stage I disease, a multivariate regression analysis was performed, and rates of FS and NFS procedures were compared, first according to ethnicity/race, and then by socioeconomic surrogate variables. RESULTS: Among the 687 AYAs with stage I ovarian dysgerminoma, there was no significant difference in rates of FS and NFS procedures based on ethnicity/race alone (P = 0.17), but there was a significant difference in procedure type for all three socioeconomic surrogates. The uninsured had higher NFS rates (30%) than those with government (21%) or private (19%) insurance (P = 0.036). Those in the poorest ZIP codes had almost twice the rate of NFS procedures (31%) compared with those in the most affluent ZIP codes (17%). For those in the least-educated regions, 24% underwent NFS procedures compared to 14% in the most-educated areas (P = 0.027). CONCLUSIONS: AYAs with stage I ovarian dysgerminoma in lower socioeconomic groups were more likely to undergo NFS procedures than those in higher socioeconomic groups, but there was no difference in rates of FS versus NFS procedures by ethnicity/race. Approaches aimed at reducing socioeconomic disparities require further examination.

Socioeconomic disparities affect survival in malignant ovarian germ cell tumors in AYA population.

BACKGROUND: Malignant ovarian germ cell tumors (MOGCTs) are a rare form of ovarian malignancy. Socioeconomic status (SES) has been shown to affect survival in several gynecologic cancers. We examined whether SES impacted survival in adolescent and young adults (AYAs) with MOGCT. MATERIALS AND METHODS: The National Cancer Data Base was used to identify AYAs (aged 15-39 years) with MOGCT from 1998 to 2012. Three SES surrogate variables identified were as follows: insurance type, income quartile, and education quartile. Pooled variance t-tests and chi-square tests were used to compare tumor characteristics, the time from diagnosis to staging/treatment, and clinical outcome variables for each SES surrogate variable, while controlling for age and race/ethnicity in a multivariate model. Kaplan-Meier survival estimates were calculated using the log-rank test. RESULTS: A total of 3125 AYAs with MOGCT were identified. Subjects with lower SES measures had higher overall stage and T-stage MOGCTs at presentation. There was no significant difference in the time to staging/treatment, extent of surgery, or use of chemotherapy by SES. Subjects from a lower education background, from a lower income quartile, and without insurance had decreased survival (P ≤ 0.02 for all). Controlling for overall stage and T-stage, the difference in survival was no longer significant. CONCLUSIONS: AYAs with MOGCT from lower SES backgrounds presented with more advanced stage disease. Further studies that focus on the underlying reasons for this difference are needed to address these disparities.

Effects of Anterior Fundoplication on Postoperative Dysphagia and Reflux After Laparoscopic Esophagocardiomyotomy for Pediatric Achalasia.

Introduction: Achalasia among children often fails endoscopic management (e.g., dilation, botulinum toxin). Laparoscopic esophagocardiomyotomy (L-ECM) is a standard intervention to relieve obstruction but can induce gastroesophageal reflux (GER). Concurrent anterior fundoplication (A-fundo) has been evaluated in randomized trials among adults, demonstrating mixed results on controlling postoperative GER without exacerbating dysphagia. Furthermore, evidence for the best approach among children remains sparse. We hypothesized that, among children undergoing L-ECM without mucosal violation, routine A-fundo would not improve postoperative GER control while exacerbating dysphagia. Materials and Methods: Observational data of 47 consecutive achalasia patients ≤18 years who received L-ECM (2002-2023) at a single academic institution were collected. Patient records were culled for demographics, achalasia characteristics, and outcomes. Two L-ECM groups were identified: with or without A-fundo. Patients were screened for postoperative dysphagia (additional procedures) and GER (new antireflux medications). Univariate independence testing was conducted to identify statistically significant variables. Results: Among 47 patients undergoing L-ECM, 28 (59.6%) received concurrent A-fundo. Compared with patients undergoing L-ECM alone, patients with L-ECM/A-fundo had significantly longer hospital stays (P < .01) without statistically different rates of postoperative dysphagia (P = .81) or GER (P = .51). Five children (10.6%) experienced mucosal injury with L-ECM: 4 recognized intraoperatively received A-Fundo without subsequent leak; 1 mucosal injury was missed and did not receive A-Fundo, which subsequently leaked. Conclusion: In this largest observation of pediatric achalasia patients, A-fundo appeared clinically insignificant when determining contributors to control GER or exacerbate postoperative dysphagia. A-fundo should not be routinely adopted in children having L-ECM for achalasia without further multicenter analysis but appears beneficial in cases having inadvertent mucosal violation.

Current Realities of Wilms Tumor Burden and Therapy in Ghana.

BACKGROUND: Between 2005 and 2014, Ghana's Wilms tumor (WT) 2-year disease-free survival of 44% trailed behind that of high-income countries. This study aimed to uncover social determinants of health leading to preventable WT death in Ghana. METHODS: WT patient records (2014-2022) at Korle-Bu Teaching Hospital (KBTH; Ghana) were reviewed retrospectively. Demographics, clinical course, tumor characteristics, and survival were evaluated using t-tests, Pearson Chi-square, and multivariate Cox logistic regression. RESULTS: Of 127 patients identified, 65 were female. Median age was 44 months [IQR 25-66]. Forty-eight patients (38%) presented with distant metastasis (75% lung, 25% liver), which associated with hypoalbuminemia (p = 0.009), caregiver informal employment (p = 0.04), and larger tumors (p = 0.002). Despite neoadjuvant chemotherapy shrinking 84% of tumors, larger initial size associated with incomplete resection (p = 0.046). Of 110 nephrectomies, 31 patients had residual disease, negatively impacting survival (p = 2.7 × 10-5). Twenty-two patients (17%) abandoned treatment (45% before nephrectomy; 55% after nephrectomy), with seven patients ultimately lost to follow-up (LTFU). Decedents represented 43% of stage IV patients compared to 28% in other stages. Event-free survival (EFS) was 60% at 4 years with overall survival (OS) at 67%. CONCLUSIONS: Although Ghana's WT survival has improved, informal employment and distance from KBTH predisposed patients to delayed referral, greater tumor burden, hypoalbuminemia, and lower survival. TYPE OF STUDY: Prognosis Study. LEVEL OF EVIDENCE: II.

Minimally invasive adnexa-sparing surgery for benign ovarian and paratubal masses in children.

BACKGROUND: The precision of minimally invasive surgery (MIS) to resect benign ovarian and paratubal masses while preserving adnexa in children is unclear. This study evaluated the integrity of laparoscopy to spare adnexa while resecting benign pathologies in children. METHODS: The institutional pathology database was queried to identify patients aged 18 years and younger having any ovarian or tubal lesion resected at a comprehensive children's hospital between 2006 and 2021. Adnexa-sparing surgery was defined as preserving both the ovary and tube from which the lesion was resected. Postoperative ultrasounds were reviewed to document ovarian follicles, blood flow, volumes, and lesion recurrence. RESULTS: Adnexal preservation was implemented in 168 of 328 pathological resections. MIS approach was used in 149 cases. Median age was 13.4 [11.0-15.3]. Among sparing surgeries, MIS associated with benign pathology, shorter operative time (median minutes: 78 MIS [59-111.5]; 130 open [92.8-149.8]; 174 MIS-to-open [132.8-199.5]; p = 0.010), and reduced hospital stay (median days: 1 MIS (Lindfors, 1971; Lovvorn III et al., 1998) [1-2]; 2 open [2-2.9], 2 MIS-to-open [1-3.3]; p = 0.001). Postoperative ovarian volume ipsilateral to the MIS procedure (median, 7.6 ml [4.3-12.1]) was relatively smaller than the contralateral ovary (median, 9.1 ml [5.5-15.0]). Blood flow was documented to the ovary in 70/94 (74.4%) of patients after MIS adnexal-sparing surgery. Distinct follicles were detected in 48/74 (64.8%) of post-menarchal patients after MIS adnexal-sparing surgery. Five ovarian cysts recurred. CONCLUSIONS: MIS preserves adnexa reliably, with postoperative ovarian follicles and blood flow detected in most patients, and maintains ∼80% of contralateral volume, while achieving definitive tumor resection. LEVEL OF EVIDENCE: III.

The Role of PIM Kinases in Pediatric Solid Tumors.

PIM kinases have been identified as potential therapeutic targets in several malignancies. Here, we provide an in-depth review of PIM kinases, including their structure, expression, activity, regulation, and role in pediatric carcinogenesis. Also included is a brief summary of the currently available pharmaceutical agents targeting PIM kinases and existing clinical trials.

Sledding while towed behind motorized vehicles associates with more severe and lethal injuries☆.

INTRODUCTION: Our institution has recently experienced an increase in sledding-related injuries, particularly when towed behind motorized vehicles. The purpose of this study was to characterize injury severity and clinical outcomes between pediatric patients who sustain injuries owing to motorized sledding accidents to aid in injury prevention messaging. METHODS: This retrospective study queried all patients who presented with a sledding-related injury to a single ACS-verified Level 1 Pediatric Trauma Center located in the Southeastern United States between 01/2015 and 01/2022. Demographics, injury details, and clinical outcomes were compared between two groups: patients towed behind a motorized vehicle (MOTOR) and those who were not (GRAVITY). RESULTS: Of the 67 patients included in our analysis, 15 (22%) were in the MOTOR group. Patients in the MOTOR group presented with significantly higher injury severity (ISS) and lower Glasgow coma scale (GCS) scores. Additionally, patients in this MOTOR group more often received a blood transfusion and intubation, had longer intensive care and overall hospital lengths of stay, and incurred higher hospital costs. In a multivariate analysis, the use of a motorized vehicle to sled was independently associated with increased ISS (OR: 9.7, 95% CI 1.9-17.5; p = 0.02). Two deaths occurred after sledding while being towed behind a motorized vehicle. CONCLUSION: Children experiencing sledding accidents while being towed by motorized vehicles sustain significantly more severe injuries and require more intensive treatments that together lead to increased hospital costs. These findings provide the framework for community educational initiatives and injury prevention measures to mitigate risk among children engaged in sledding. LEVEL OF EVIDENCE: IV retrospective cohort study.

CRISPR/Cas9-mediated knockout of PIM3 suppresses tumorigenesis and cancer cell stemness in human hepatoblastoma cells.

Hepatoblastoma remains one of the most difficult childhood tumors to treat and is alarmingly understudied. We previously demonstrated that Proviral Insertion site in Maloney murine leukemia virus (PIM) kinases, specifically PIM3, are overexpressed in human hepatoblastoma cells and function to promote tumorigenesis. We aimed to use CRISPR/Cas9 gene editing with dual gRNAs to introduce large inactivating deletions in the PIM3 gene and achieve stable PIM3 knockout in the human hepatoblastoma cell line, HuH6. PIM3 knockout of hepatoblastoma cells led to significantly decreased proliferation, viability, and motility, inhibited cell-cycle progression, decreased tumor growth in a xenograft murine model, and increased animal survival. Analysis of RNA sequencing data revealed that PIM3 knockout downregulated expression of pro-migratory and pro-invasive genes and upregulated expression of genes involved in apoptosis and differentiation. Furthermore, PIM3 knockout decreased hepatoblastoma cancer cell stemness as evidenced by decreased tumorsphere formation, decreased mRNA abundance of stemness markers, and decreased cell surface expression of CD133, a marker of hepatoblastoma stem cell-like cancer cells. Reintroduction of PIM3 into PIM3 knockout cells rescued the malignant phenotype. Successful CRISPR/Cas9 knockout of PIM3 kinase in human hepatoblastoma cells confirmed the role of PIM3 in promoting hepatoblastoma tumorigenesis and cancer cell stemness.

PIM3 kinase promotes tumor metastasis in hepatoblastoma by upregulating cell surface expression of chemokine receptor cxcr4.

Patients presenting with metastatic hepatoblastoma have limited treatment options and survival rates as low as 25%. We previously demonstrated that Proviral Integration site in Maloney murine leukemia virus 3 (PIM3) kinase promotes tumorigenesis and cancer cell stemness in hepatoblastoma. In this study, we assessed the role of PIM3 kinase in promoting hepatoblastoma metastasis. We utilized a tail vein injection model of metastasis to evaluate the effect of CRISPR/Cas9-mediated PIM3 knockout, stable overexpression of PIM3, and pharmacologic PIM inhibition on the formation of lung metastasis. In vivo studies revealed PIM3 knockout impaired the formation of lung metastasis: 5 out of 6 mice injected with wild type hepatoblastoma cells developed lung metastasis while none of the 7 mice injected with PIM3 knockout hepatoblastoma cells developed lung metastasis. PIM3 overexpression in hepatoblastoma increased the pulmonary metastatic burden in mice and mechanistically, upregulated the phosphorylation and cell surface expression of CXCR4, a key receptor in the progression of cancer cell metastasis. CXCR4 blockade with AMD3100 decreased the metastatic phenotype of PIM3 overexpressing cells, indicating that CXCR4 contributed to PIM3's promotion of hepatoblastoma metastasis. Clinically, PIM3 expression correlated positively with CXCR4 expression in primary hepatoblastoma tissues. In conclusion, we have shown PIM3 kinase promotes the metastatic phenotype of hepatoblastoma cells through upregulation of CXCR4 cell surface expression and these findings suggest that targeting PIM3 kinase may provide a novel therapeutic strategy for metastatic hepatoblastoma.

9-cis-UAB30, a novel rexinoid agonist, decreases tumorigenicity and cancer cell stemness of human neuroblastoma patient-derived xenografts.

Retinoic acid (RA) therapy has been utilized as maintenance therapy for high-risk neuroblastoma, but over half of patients treated with RA relapse. Neuroblastoma stem cell-like cancer cells (SCLCCs) are a subpopulation of cells characterized by the expression of the cell surface marker CD133 and are hypothesized to contribute to drug resistance and disease relapse. A novel rexinoid compound, 9-cis-UAB30 (UAB30), was developed having the same anti-tumor effects as RA but a more favorable toxicity profile. In the current study, we investigated the efficacy of UAB30 in neuroblastoma patient-derived xenografts (PDX). Two PDXs, COA3 and COA6, were utilized and alterations in the malignant phenotype were assessed following treatment with RA or UAB30. UAB30 significantly decreased proliferation, viability, and motility of both PDXs. UAB30 induced cell-cycle arrest as demonstrated by the significant increase in percentage of cells in G1 (COA6: 33.7 ±â€¯0.7 vs. 43.3 ±â€¯0.7%, control vs. UAB30) and decrease in percentage of cells in S phase (COA6: 44.7 ±â€¯1.2 vs. 38.6 ±â€¯1%, control vs. UAB30). UAB30 led to differentiation of PDX cells, as evidenced by the increase in neurite outgrowth and mRNA abundance of differentiation markers. CD133 expression was decreased by 40% in COA6 cells after UAB30. The ability to form tumorspheres and mRNA abundance of known stemness markers were also significantly decreased following treatment with UAB30, further indicating decreased cancer cell stemness. These results provide evidence that UAB30 decreased tumorigenicity and cancer cell stemness in neuroblastoma PDXs, warranting further exploration as therapy for high-risk neuroblastoma.

EZH2 inhibition decreases neuroblastoma proliferation and in vivo tumor growth.

Investigation of the mechanisms responsible for aggressive neuroblastoma and its poor prognosis is critical to identify novel therapeutic targets and improve survival. Enhancer of Zeste Homolog 2 (EZH2) is known to play a key role in supporting the malignant phenotype in several cancer types and knockdown of EZH2 has been shown to decrease tumorigenesis in neuroblastoma cells. We hypothesized that the EZH2 inhibitor, GSK343, would affect cell proliferation and viability in human neuroblastoma. We utilized four long-term passage neuroblastoma cell lines and two patient-derived xenolines (PDX) to investigate the effects of the EZH2 inhibitor, GSK343, on viability, motility, stemness and in vivo tumor growth. Immunoblotting confirmed target knockdown. Treatment with GSK343 led to significantly decreased neuroblastoma cell viability, migration and invasion, and stemness. GSK343 treatment of mice bearing SK-N-BE(2) neuroblastoma tumors resulted in a significant decrease in tumor growth compared to vehicle-treated animals. GSK343 decreased viability, and motility in long-term passage neuroblastoma cell lines and decreased stemness in neuroblastoma PDX cells. These data demonstrate that further investigation into the mechanisms responsible for the anti-tumor effects seen with EZH2 inhibitors in neuroblastoma cells is warranted.

PIM kinases mediate resistance to cisplatin chemotherapy in hepatoblastoma.

Despite increasing incidence, treatment for hepatoblastoma has not changed significantly over the past 20 years. Chemotherapeutic strategies continue to rely on cisplatin, as it remains the most active single agent against hepatoblastoma. However, chemoresistance remains a significant challenge with 54-80% of patients developing resistance to chemotherapy after 4-5 cycles of treatment. Stem cell-like cancer cells (SCLCCs) are a subset of cells thought to play a role in chemoresistance and disease recurrence. We have previously demonstrated that Proviral Integration site for Moloney murine leukemia virus (PIM) kinases, specifically PIM3, play a role in hepatoblastoma cell proliferation and tumor growth and maintain the SCLCC phenotype. Here, we describe the development of a cisplatin-resistant hepatoblastoma xenograft model of the human HuH6 cell line and a patient-derived xenograft, COA67. We provide evidence that these cisplatin-resistant cells are enriched for SCLCCs and express PIM3 at higher levels than cisplatin-naïve cells. We demonstrate that PIM inhibition with AZD1208 sensitizes cisplatin-resistant hepatoblastoma cells to cisplatin, enhances cisplatin-mediated apoptosis, and decreases the SCLCC phenotype seen with cisplatin resistance. Together, these findings indicate that PIM inhibition may be a promising adjunct in the treatment of hepatoblastoma to effectively target SCLCCs and potentially decrease chemoresistance and subsequent disease relapse.

PP2A activation alone and in combination with cisplatin decreases cell growth and tumor formation in human HuH6 hepatoblastoma cells.

Despite an increase in incidence, treatments for hepatoblastoma remain virtually unchanged for the past 20 years, emphasizing the need for novel therapeutics. FTY720 (fingolimod) is an immunomodulator approved for use in multiple sclerosis in children that has been demonstrated to have anti-cancer properties in multiple cancer types. We have demonstrated that FTY720 activates PP2A in hepatoblastoma, but does not do so via inhibition of the endogenous inhibitors, CIP2A and I2PP2A, as previously observed in other cancers. PP2A activation in hepatoblastoma decreased cell viability, proliferation, and motility and induced apoptosis. In a subcutaneous xenograft model, FTY720 decreased tumor growth. FTY720 in combination with the standard chemotherapeutic, cisplatin, decreased proliferation in a synergistic manner. Finally, animals bearing subcutaneous hepatoblastoma xenografts treated with FTY720 and cisplatin in combination had significantly decreased tumor growth compared to those treated with either drug alone. These findings show that targeting PP2A with FTY70 shows promise in the treatment of hepatoblastoma and that combining FTY720 with cisplatin may be a novel and effective strategy to better treat this devastating pediatric liver tumor.

The presence of PIM3 increases hepatoblastoma tumorigenesis and tumor initiating cell phenotype and is associated with decreased patient survival.

PURPOSE: Hepatoblastoma is the most common primary liver cancer of childhood and has few prognostic indicators. We have previously shown that Proviral Integration site for Moloney murine leukemia virus (PIM3) kinase decreased hepatoblastoma tumorigenicity. We sought to determine the effect of PIM3 overexpression on hepatoblastoma cells and whether expression of PIM3 correlated with patient/tumor characteristics or survival. METHODS: The hepatoblastoma cell line, HuH6, and patient-derived xenograft, COA67, were utilized. Viability, proliferation, migration, sphere formation, and tumor growth in mice were assessed in PIM3-overexpressing cells. Immunohistochemistry was performed for PIM3 on patient samples. Correlation between stain score and clinical/pathologic characteristics was assessed. RESULTS: PIM3 overexpression rescued the anti-proliferative effect observed with PIM3 knockdown. Sphere formation was increased in PIM3 overexpressing cells. Cells with PIM3 overexpression yielded larger tumors than those with empty vector. Seventy-four percent of samples expressed PIM3. There was no statistical difference in patient characteristics between subjects with strong versus weak PIM3 staining, but patients with strong PIM3 staining had decreased survival. CONCLUSIONS: PIM3 expression plays a role in hepatoblastoma tumorigenesis. PIM3 was present in the majority of hepatoblastomas and higher PIM3 expression correlated with decreased survival. PIM3 warrants investigation as a therapeutic target and prognostic marker for hepatoblastoma.

Investigation of PP2A and Its Endogenous Inhibitors in Neuroblastoma Cell Survival and Tumor Growth.

High-risk neuroblastoma continues to carry a poor prognosis. Nearly 50% of these tumors relapse following extensive treatment regimens. Protein phosphatase 2A (PP2A), a tumor suppressor, has been shown to be downregulated in many human cancers via multiple mechanisms including upregulation of its endogenous inhibitors, I2PP2A or CIP2A. We hypothesized that inhibition of the endogenous PP2A inhibitors or activation of PP2A would decrease tumorigenicity in human neuroblastoma cells. Four human neuroblastoma cell lines were utilized. Expression of PP2A and its endogenous inhibitors I2PP2A and CIP2A was confirmed by immunoblotting. PP2A activation was measured via phosphatase activation assay. Multiple parallel methods including siRNA inhibition of the endogenous PP2A inhibitors and pharmacologic activation of PP2A were utilized. Cell viability, proliferation, migration, and invasion assays were performed. In vivo studies were utilized to determine the effects of PP2A activation on neuroblastoma tumor growth. Inhibition of the endogenous inhibitors of PP2A or pharmacologic activation of PP2A with the PP2A activator FTY720 led to decreased neuroblastoma cell viability, proliferation, migration, and invasion. Treatment of mice bearing SK-N-AS or SK-N-BE(2) neuroblastoma tumors with FTY720 resulted in a significant decrease in tumor growth compared to vehicle-treated animals. In conclusion, activation of PP2A may provide a novel therapeutic target for neuroblastoma.

Corruption of neuroblastoma patient derived xenografts with human T cell lymphoma.

BACKGROUND: Patient derived xenografts (PDXs) provide a unique opportunity for investigators to study tumor cell activity, response to therapeutics, and resistance patterns without exposing the human patient to experimental compounds, and thereby play a crucial role in pre-clinical evaluation of new therapies. It has been reported that PDXs may undergo a transformation to lymphoma, most commonly associated with Epstein Barr virus (EBV). If the character of a xenograft becomes compromised and remains undetected, it could have a detrimental impact on the research community as a whole. Our lab has established a number of pediatric solid tumor PDXs which accurately recapitulate the human tumors following several passages. One particular neuroblastoma PDX was noted to grow quickly and with an unusual phenotype, leading us to hypothesize that this PDX had undergone a transformation. METHODS: The PDX in question was investigated with histology, immunohistochemistry (IHC), EBER in situ hybridization, and PCR to determine its identity. RESULTS: Histology on the tumor revealed a small, round blue cell tumor similar to the original neuroblastoma from which it was derived. IHC staining showed that the tumor was composed of lymphocytes that were CD3 positive, <5% CD4 positive, and CD20 negative. The cells were Epstein Barr virus negative. PCR demonstrated that the tumor was human and not murine in origin. CONCLUSION: These findings indicate that a human T Cell lymphoma developed in place of this neuroblastoma PDX. Changes in PDX identity such as this one will significantly impact studies utilizing pediatric PDXs and the mechanism by which this occurred warrants further investigation.

Targeting PIM Kinases Affects Maintenance of CD133 Tumor Cell Population in Hepatoblastoma.

Hepatoblastoma is the most common primary liver tumor in children, but treatment has not changed significantly in the past 20 years. We have previously demonstrated that Proviral Integration site for Moloney murine leukemia (PIM) kinases promote tumorigenesis in hepatoblastoma. Stem cell-like cancer cells (SCLCCs) are a subset of cells thought to be responsible for chemoresistance, metastasis, relapse, and recurrence. The aim of this study was to identify SCLCCs in hepatoblastoma and determine the role of PIM kinases in SCLCCs. Hepatoblastoma cells were separated into CD133-enriched and CD133-depleted populations and the frequency of SCLCCs was assessed. CD133 expression was determined in the presence or absence of the PIM inhibitor, AZD1208. The effects of AZD1208 on proliferation, apoptosis, and motility were assessed in vitro and the effect of AZD1208 on tumor growth was examined in vivo. We identified CD133 as a marker for SCLCCs in hepatoblastoma and showed that PIM kinases promote a SCLCC phenotype. PIM kinase inhibition with AZD1208 decreased proliferation, migration, and invasion and increased apoptosis in both SCLCCs and non-SCLCCs in a long-term passaged hepatoblastoma cell line and patient-derived xenograft. Additionally, tumor growth in mice implanted with hepatoblastoma SCLCCs was decreased with PIM inhibition such that 57% of the tumors regressed. These findings identify CD133 as a marker for SCLCCs in hepatoblastoma and provide evidence that inhibition of PIM kinases decreases stemness and tumorigenicity of SCLCCs in hepatoblastoma, making them potential therapeutic targets for the treatment of hepatoblastoma.

Focal Adhesion Kinase Inhibition Contributes to Tumor Cell Survival and Motility in Neuroblastoma Patient-Derived Xenografts.

Patient-derived xenografts (PDXs) provide an opportunity to evaluate the effects of therapies in an environment that more closely resembles the human condition than that seen with long-term passage cell lines. In the current studies, we investigated the effects of FAK inhibition on two neuroblastoma PDXs in vitro. Cells were treated with two small molecule inhibitors of FAK, PF-573,228 (PF) and 1,2,4,5-benzentetraamine tetrahydrochloride (Y15). Following FAK inhibition, cell survival and proliferation decreased significantly and cell cycle arrest was seen in both cell lines. Migration and invasion assays were used to determine the effect of FAK inhibition on cell motility, which decreased significantly in both cell lines in the presence of either inhibitor. Finally, tumor cell stemness following FAK inhibition was evaluated with extreme limiting dilution assays as well as with immunoblotting and quantitative real-time PCR for the expression of stem cell markers. FAK inhibition decreased formation of tumorspheres and resulted in a corresponding decrease in established stem cell markers. FAK inhibition decreased many characteristics of the malignant phenotype, including cancer stem cell like features in neuroblastoma PDXs, making FAK a candidate for further investigation as a potential target for neuroblastoma therapy.

UAB30, A Novel Rexinoid Agonist, Decreases Stemness In Group 3 Medulloblastoma Human Cell Line Xenografts.

PURPOSE: In spite of advances in therapy for some subtypes, group 3 medulloblastoma continues to portend a poor prognosis. A subpopulation of medulloblastoma cells expressing the cell surface marker CD133 have been posited as possible stem cell like cancer cells (SCLCC), a potential source of drug resistance and relapse. Retinoids have been shown to affect SCLCC in other brain tumors. Based on these findings, we hypothesized that the CD133-enriched cell population group 3 medulloblastoma cells would be sensitive to the novel rexinoid, UAB30. METHODS: Human medulloblastoma cell lines were studied. Cell sorting based on CD133 expression was performed. Both in vitro and in vivo extreme limiting dilution assays were completed to establish CD133 as a SCLCC marker in these cell lines. Cells were treated with either retinoic acid (RA) or UAB30 and sphere forming capacity and CD133 expression were assessed. Immunoblotting was used to assess changes in stem cell markers. Finally, mice injected with CD133-enriched or CD133-depleted cells were treated with UAB30. RESULTS: CD133-enriched cells more readily formed tumorspheres in vitro at lower cell concentrations and formed tumors in vivo at low cell numbers. Treatment with RA or UAB30 decreased CD133 expression, decreased tumorsphere formation, and decreased expression of cancer stem cell markers. In vivo studies demonstrated that tumors from both CD133-enriched and CD133-depleted cells were sensitive to treatment with UAB30. CONCLUSIONS: CD133 is a marker for medulloblastoma SCLCCs. Both CD133-enriched and CD133-depleted medulloblastoma cell populations demonstrated sensitivity to UAB30, indicating its potential as a therapeutic option for group 3 medulloblastoma.