Molecular Characterization of Differentiated-Resistance MSC Subclones by Single-Cell Transcriptomes.

Background: The mechanism of tumorigenicity potentially evolved in mesenchymal stem cells (MSCs) remains elusive, resulting in inconsistent clinical application efficacy. We hypothesized that subclones in MSCs contribute to their tumorgenicity, and we approached MSC-subclones at the single-cell level. Methods: MSCs were cultured in an osteogenic differentiation medium and harvested on days 12, 19, and 25 for cell differentiation analysis using Alizarin Red and followed with the single-cell transcriptome. Results: Single-cell RNA-seq analysis reveals a discrete cluster of MSCs during osteogenesis, including differentiation-resistant MSCs (DR-MSCs), differentiated osteoblasts (DO), and precursor osteoblasts (PO). The DR-MSCs population resembled cancer initiation cells and were subjected to further analysis of the yes associated protein 1 (YAP1) network. Verteporfin was also used for YAP1 inhibition in cancer cell lines to confirm the role of YAP1 in MSC--involved tumorigenicity. Clinical data from various cancer types were analyzed to reveal relationships among YAP1, OCT4, and CDH6 in MSC--involved tumorigenicity. The expression of cadherin 6 (CDH6), octamer-binding transcription factor 4 (OCT4), and YAP1 expression was significantly upregulated in DR-MSCs compared to PO and DO. YAP1 inhibition by Verteporfin accelerated the differentiation of MSCs and suppressed the expression of YAP1, CDH6, and OCT4. A survey of 56 clinical cohorts revealed a high degree of co-expression among CDH6, YAP1, and OCT4 in various solid tumors. YAP1 inhibition also down-regulated HeLa cell viability and gradually inhibited YAP1 nuclear localization while reducing the transcription of CDH6 and OCT4. Conclusions: We used single-cell sequencing to analyze undifferentiated MSCs and to discover a carcinogenic pathway in single-cell MSCs of differentiated resistance subclones.

Single-cell transcriptomes reveal the mechanism for a breast cancer prognostic gene panel.

The clinical benefits of the MammaPrint® signature for breast cancer is well documented; however, how these genes are related to cell cycle perturbation have not been well determined. Our single-cell transcriptome mapping (algorithm) provides details into the fine perturbation of all individual genes during a cell cycle, providing a view of the cell-cycle-phase specific landscape of any given human genes. Specifically, we identified that 38 out of the 70 (54%) MammaPrint® signature genes are perturbated to a specific phase of the cell cycle. The MammaPrint® signature panel derived its clinical prognosis power from measuring the cell cycle activity of specific breast cancer samples. Such cell cycle phase index of the MammaPrint® signature suggested that measurement of the cell cycle index from tumors could be developed into a prognosis tool for various types of cancer beyond breast cancer, potentially improving therapy through targeting a specific phase of the cell cycle of cancer cells.

Immunophenotyping of pediatric brain tumors: correlating immune infiltrate with histology, mutational load, and survival and assessing clonal T cell response.

There is little known regarding the immune infiltrate present in pediatric brain tumors and how this compares to what is known about histologically similar adult tumors and its correlation with survival. Here, we provide a descriptive analysis of the immune infiltrate of 22 fresh pediatric brain tumor tissue samples of mixed diagnoses and 40 peripheral blood samples. Samples were analyzed using a flow cytometry panel containing markers for immune cell subtypes, costimulatory markers, inhibitory signals, and markers of activation. This was compared to the standard method of immunohistochemistry (IHC) for immune markers for 89 primary pediatric brain tumors. Both flow cytometry and IHC data did not correlate with the grade of tumor or mutational load and IHC data was not significantly associated with survival for either low grade or high grade gliomas. There is a trend towards a more immunosuppressive phenotype in higher grade tumors with more regulatory T cells present in these tumor types. Both PD1 and PDL1 were present in only a small percentage of the tumor infiltrate. T cell receptor sequencing revealed up to 10% clonality of T cells in tumor infiltrates and no significant difference in clonality between low and high grade gliomas. We have shown the immune infiltrate of pediatric brain tumors does not appear to correlate with grade or survival for a small sample of patients. Further research and larger studies are needed to fully understand the interaction of pediatric brain tumors and the immune system.

Precision Medicine in Pediatric Neurooncology: A Review.

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

Pediatric malignant germ cell tumors: A comparison of the neuro-oncology and solid tumor experience.

Malignant germ cell tumors (GCT) arise from abnormal migration of primordial germ cells and are histologically identical whether they occur inside or outside the central nervous system (CNS). However, the treatment strategy for GCTs varies greatly depending on the location of the tumor. These differences are in part due to the increased morbidity of surgery in the CNS but may also reflect differential sensitivity of the tumors to chemotherapy and radiation therapy (RT) or not-yet-understood biologic differences between these tumors. Historically, specialists caring for extracranial and intracranial GCT in the United States have practiced separately without much cross communication. The focus of this review is a discussion of differences between the management of CNS and extra-CNS GCTs and opportunities for collaboration and future research.

Plasmacytoma-like post-transplant lymphoproliferative disorder seen in pediatric combined liver and intestinal transplant recipients.

Post-transplant lymphoproliferative disease (PTLD) is a lymphoproliferative disorder secondary to chronic immunosuppression and is the most common malignancy in transplanted patients [Kamdar et al. Curr Opin Organ Transplant, 2011; 16:274-280]. Although PTLD usually presents as B or T cell lymphoma, plasmacytomas have been reported, mostly in the adult population. Six cases of pediatric plasmacytoma-like PTLD have been reported, all of which were treated with vincristine, adriamycin, and dexamethasone (VAD), high dose dexamethasone alone, or dexamethasone + thalidomide [Tcheng et al. Pediatric Blood Cancer, 2006; 47:218-223; Perry et al. Blood, 2013; 8:1377-1383]. We present two cases of pediatric plasmacytoma-like PTLD in combined liver and small bowel transplant patients both successfully treated with bortezomib and dexamethasone based on multiple myeloma protocols [Kyle and Rajkumar, Clin Lymphoma Myeloma, 2009; 9:278-288; Adams and Kaufmann, Cancer Invest, 2004; 22:304-311].

A single-institution retrospective cases series of childhood undifferentiated embryonal liver sarcoma (UELS): success of combined therapy and the use of orthotopic liver transplant.

BACKGROUND/INTRODUCTION: Undifferentiated embryonal liver sarcoma (UELS) makes up 9% to 15% of all malignant liver tumors in children. UELS is characteristically diagnosed between the ages of 6 and 10 years and presents with abdominal pain, vomiting, and an abdominal mass. There is currently no standardized treatment for UELS except attempt at complete surgical resection. There have been only about 150 cases of UELS reported in the literature all with historically poor overall survival of <37.5% at 5 years. This report is one of the largest single-institution reports of UELS consisting of 5 patients over 2 decades. The purpose of this study is to characterize presentation and to report treatment success in UELS in children, adolescents, and young adults and the use of liver transplantation and, lastly, to suggest a use of positron emission tomography/computed tomography (PET/CT) in monitoring of this disease process. METHODS: We conducted an Institutional Review Board-approved retrospective chart review. Data were collected from UELS patients younger than 21 years seen at the University of California Los Angeles over the past 20 years (January 2001 to September 2011). Descriptive analysis was conducted including multiple parameters of patient demographics, tumor characteristics, treatment modalities, and morbidity and mortality. RESULTS: Five patients with UELS were identified. Patients initially presented with fever, abdominal pain, or nausea. Ages ranged from 10 to 19 years old (median age 13 y old), and there was a 4:1 male-to-female predominance. Tumor size ranged from 6 to 22 cm in largest diameter. One patient presented with metastatic disease to the lungs and heart and 1 patient recurred 2 years from diagnosis with bilateral paraspinal masses. Treatment included local control surgery with neoadjuvant and adjuvant chemotherapy with an anthracycline/alkylating agent combination. One patient with recurrent and refractory disease achieved local control with an orthotopic liver transplantation (OLT). Metastatic disease was controlled with surgery and radiation therapy. 18-Fluorodeoxyglucose PET/CT was a useful imaging tool for judging response to therapy with complete loss of metabolic activity in tumor after neoadjuvant chemotherapy in 2 representative cases. Although follow-up is short for some patients, overall survival in these 5 patients was 100% with follow-up ranging from 21 to 68 months. Disease-free survival ranged from 8 to 46 months with no patients with residual disease. CONCLUSIONS: UELS is an aggressive high-grade primary liver sarcoma with high metastatic potential. This report represents one of the largest single-institution studies of UELS. Using multimodality therapy, patients have achieved 100% overall survival even in the setting of extensive disease, metastases, and recurrence. In cases of unresectable primary tumor or recurrent and refractory disease isolated to the liver, OLT is a potential therapeutic option. We report success with adjuvant chemotherapy and complete surgical resection with OLT as an alternative in unresectable or refractory cases. We also suggest a possible utility of PET/CT in monitoring treatment response in this disease.